WO2016143853A1

WO2016143853A1 - Window film and laminated glass using same

Info

Publication number: WO2016143853A1
Application number: PCT/JP2016/057584
Authority: WO
Inventors: 中島　彰久
Original assignee: コニカミノルタ株式会社
Priority date: 2015-03-11
Filing date: 2016-03-10
Publication date: 2016-09-15
Also published as: JP2018070383A

Abstract

The present invention addresses the problem of providing a window film having exceptional heat moldability and curved-shape-following properties, and a laminated glass using the same. The window film of the present invention is affixed to glass having an at least partially curved shape, wherein the window film is characterized by being a laminated film of a polyester film A having at least a film thickness of 5 μm or greater and a heat shrinkage rate within a range of 0.2-1%, and a polyester film B having at least a film thickness of 5 μm or greater and a heat shrinkage rate within a range of 2-10%. Heat shrinkage rate (%) = {(L(23°C) - L(150°C))/L(23°C)} × 100 L(23°C): sample length when allowed to stand for one day in an environment at 23°C and 55% RH. L(150°C): sample length when allowed to stand for one day in an environment at 23°C and 55% RH after standing for 30 minutes in an environment at 150°C.

Description

Window film and laminated glass using the same

The present invention relates to a window film and a laminated glass using the window film. More specifically, the present invention relates to a window film excellent in thermoformability and curved surface shape followability, and a laminated glass using the window film.

In recent years, as a windshield or window glass for automobiles, a resin film called a window film is sandwiched between two glass substrates from the viewpoint of preventing strength and scattering of glass pieces when damaged. Glass is used. Usually, sunlight enters the automobile through such a laminated glass, and the temperature inside the automobile rises due to the heat energy. The air conditioner is operated to suppress the rise of the temperature inside the vehicle due to such sunlight, but it is highly insulated for the purpose of saving energy by blocking the heat of sunlight entering from the car window and suppressing the operation of the air conditioner. Or the heat ray blocking laminated glass which has heat ray blocking property is distribute | circulating to the market. Laminated glass used for such purposes generally has a heat-shielding window film disposed between a pair of glass substrates to block transmission of heat rays (infrared rays or near-infrared rays) in sunlight, and indoors. Methods for suppressing temperature rise and cooling load are known.

As a support for a window film, a general polyester film having a heat shrinkage in the range of 0.2 to 1% is usually used (for example, see Patent Document 1).

It is also known to use a window film for laminated glass using a polyester film having a heat shrinkage rate in the range of 2 to 10% (see, for example, Patent Document 2).

However, since the windshield and window glass of the above-mentioned automobile are processed to be curved, they are generally thermoformed using a heat gun or the like before being bonded together. If a polyester film in the range of% is used, the thermal shrinkage rate is small, so that there is a problem that curved surface followability is inferior and thermoforming takes time.

On the other hand, if a polyester film with a heat shrinkage rate in the range of 2 to 10% is used, the time for thermoforming is shortened. However, if too much time is spent, the window film shrinks (shrinks) and fails to be formed. There is a problem that thermoforming is difficult.

JP 2013-209246 A JP 2010-215493 A

The present invention has been made in view of the above-mentioned problems and situations, and a solution to that problem is to provide a window film excellent in thermoformability and curved surface shape followability, and a laminated glass using the window film.

In order to solve the above-mentioned problems, the present inventor, in the process of examining the cause of the above-mentioned problems, the heat is generated by the window film in which two polyester films A and B having a specific film thickness and a heat shrinkage rate are laminated. It has been found that a window film excellent in moldability and curved surface shape followability can be obtained.

That is, the above-mentioned problem according to the present invention is solved by the following means.

1. It is a window film to be bonded to glass having a curved shape at least in part,
The window film support includes a polyester film A having a thickness of 5 μm or more and a thermal contraction rate of 0.2 to 1%, and a thermal contraction rate of 2 to 10 and a thickness of 5 μm or more. %, A window film characterized by being a film laminated with a polyester film B within a range of%.

Thermal shrinkage (%) = {(L (23 ° C.) − L (150 ° C.)) / L (23 ° C.)} × 100
L (23 ° C.): Sample length when left for 1 day in an environment of 23 ° C. and 55% RH L (150 ° C.): After standing for 30 minutes in an environment of 150 ° C., in an environment of 23 ° C. and 55% RH 1. Sample length when left for 1 day 2. The window film as set forth in claim 1, wherein the ratio (A / B) of the film thickness ratio between the polyester film A and the polyester film B is in the range of 90/10 to 50/50.

3. The window film according to

claim

1 or 2, further comprising a near-infrared absorbing layer between the polyester film A and the polyester film B.

4. The window film according to

claim

1 or 2, further comprising a near-infrared reflective layer between the polyester film A and the polyester film B.

5. A laminated glass in which the window film according to any one of Items 1 to 4 is sandwiched between glasses having a curved shape at least in part,
Laminated glass, wherein the polyester film A surface side of the window film is disposed at a position in contact with a concave portion of the curved glass.

By the above means of the present invention, it is possible to provide a window film excellent in thermoformability and curved surface shape followability and a laminated glass using the same.

The expression mechanism or action mechanism of the effect of the present invention is not clear, but is presumed as follows.

The window film of the present invention is a film in which two polyester films A and B having a specific film thickness and heat shrinkability are laminated as a support, and is used for glass having a curved shape at least partially. In addition, by disposing a polyester film having a small heat shrinkage rate on the concave side of the curved surface, the shrinkage of the film on the concave side is small and the shrinkage of the film on the opposite side is large when thermoformed using a heat gun or the like. Therefore, it is presumed that the generation of wrinkles on the side in contact with the curved surface shape is suppressed, the curved surface shape following property to the concave portion of the film is improved, and the thermoformability is improved.

Schematic sectional view showing an example of the configuration of the window film of the present invention Schematic sectional view showing an example of the configuration of the window film of the present invention having a near infrared absorption layer Schematic sectional view showing an example of the configuration of the window film of the present invention having a near-infrared reflective layer An example of the window film of the present invention having a multilayer reflective layer Schematic of the laminated glass comprising the window film of the present invention

The window film of the present invention is characterized in that it is a laminated film of two polyester films A and B having a specific film thickness and heat shrinkage rate. This feature is a technical feature common to the inventions according to claims 1 to 5.

As an embodiment of the present invention, from the viewpoint of manifestation of the effect of the present invention, the ratio value (A / B) of the film thickness of the polyester film A and the polyester film B is in the range of 90/10 to 50/50. When it is used for glass having a curved surface shape at least in part, the film thickness of the polyester film having a small heat shrinkage rate is increased and disposed on the concave portion side of the curved surface shape, thereby achieving thermoformability and curved surface shape. A window film excellent in followability can be obtained.

It is suitable as a heat-shielding window film used for laminated glass to provide a layer that absorbs near infrared rays or a layer that reflects near infrared rays between the polyester film A and the polyester film B.

In the laminated glass of the present invention, the fact that the polyester film A surface side of the window film is disposed at a position in contact with the concave portion of the glass having the curved shape improves the thermoformability and increases the productivity. To preferred.

Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In the present application, “˜” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.

<< Outline of Window Film of the Present Invention >>
The window film of the present invention is a window film to be bonded to glass having a curved surface shape at least in part, wherein the window film has a film thickness of at least 5 μm and a heat shrinkage ratio of 0.2 to 1% as described below. The polyester film A within the range and the polyester film B having a thickness of 5 μm or more and a thermal shrinkage ratio of 2 to 10% are laminated.

Here, the heat shrinkage rate is determined by the following measurement method.

<Heat shrinkage>
The thermal shrinkage rate of the polyester film whose film thickness is adjusted to 5 μm or more according to the present invention is obtained by the following conditions and formula using a sample sampled from about 10 places from the longitudinal direction or the lateral direction of the film, and the average value thereof. Can be used. As the sample, for example, a sample with a length of 100 mm and a width of 10 mm is used, and the vertical length can be set to the following sample length. Moreover, each environment can use an environmental test room or a thermostat.

Thermal shrinkage (%) = {(L (23 ° C.) − L (150 ° C.)) / L (23 ° C.)} × 100
L (23 ° C.): Sample length when left for 1 day in an environment of 23 ° C. and 55% RH L (150 ° C.): After standing for 30 minutes in an environment of 150 ° C., in an environment of 23 ° C. and 55% RH Sample length when left for 1 day at the time of laminating two polyester films having different heat shrinkage ratios, and when bonding by thermocompression bonding to glass having a curved surface shape, due to the difference in heat shrinkage ratio, curved surface It suppresses the generation of wrinkles on the side in contact with the shape, improves the curved surface shape followability, and provides excellent thermoformability.

<Configuration of window film of the present invention>
Hereinafter, the components of the window film of the present invention will be sequentially described.

First, the basic configuration of the window film of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic sectional view showing an example of the structure of the window film of the present invention (the numbers in parentheses indicate the numbers in the figure).

The window film 1 of the present invention has a film thickness of 5 μm or more and a thermal shrinkage rate of 0.2 to 1%, and a polyester film A (2) in a range of 0.2 to 1% and a film thickness of 5 μm or more and a heat shrinkage rate of 2 to 10% It is the structure which laminated | stacked the polyester film B (3) in the range. Between the polyester film A (2) and the polyester film B (3), an adhesive layer 4 may be provided and bonded, or may be omitted and laminated by thermocompression bonding.

Moreover, it is preferable that the adhesion layer 5 for bonding to glass is formed in the surface of the polyester film A (2), and the said adhesion layer 5 is similarly formed in the surface of the polyester film B (3). May be.

As the adhesive layer 4 and the adhesive layer 5, a polyvinyl butyral (PVB) resin, an epoxy resin or the like, which is preferably a polyvinyl acetal resin film, can be preferably used.

2A and 2B are schematic cross-sectional views showing an example of the configuration of the window film 10 of the present invention having a layer that absorbs near infrared rays or a layer that reflects near infrared rays.

The window film 10 of the present invention having a layer that absorbs near infrared rays or a layer that reflects near infrared rays, which is a preferred embodiment of the present invention, is close to the polyester film A (2) and the polyester film B (3). It is the laminated structure bonded so that the layer 6 which absorbs infrared rays, or the layer 7 which reflects near infrared rays may be pinched | interposed. The polyester film A (2) and the polyester film B (3) are preferably bonded to the surface of the layer 6 that absorbs near infrared rays or the layer 7 that reflects near infrared rays via an adhesive layer 4, respectively. .

[1] Polyester film A and polyester film B
The polyester film A according to the present invention is a polyester film having a film thickness of 5 μm or more and a heat shrinkage ratio in the range of 0.2 to 1%, and the polyester film B has a film thickness of 5 μm or more and a heat shrinkage ratio of 2 It is characterized by being a polyester film in a range of ˜10%.

Regarding the film thickness of the polyester film, Nikon Digimicro (MF501) manufactured by Nikon Corporation was used and measured at 10 points in the lateral direction of the film in an environment of 23 ° C. and 55% RH. can do.

[1.1] Polyester Resin A polyester resin that can be used in the polyester film A and the polyester film B (hereinafter sometimes simply referred to as a polyester film) according to the present invention is obtained by polymerizing a dicarboxylic acid and a diol. From the viewpoint of heat resistance, 70% or more of the dicarboxylic acid structural unit (structural unit derived from dicarboxylic acid) is derived from the aromatic dicarboxylic acid, and 70% or more of the diol structural unit (structural unit derived from diol). It is preferably derived from an aliphatic diol.

The proportion of the structural unit derived from the aromatic dicarboxylic acid is 70% or more, preferably 80% or more, and more preferably 90% or more.

The proportion of the structural unit derived from the aliphatic diol is 70% or more, preferably 80% or more, more preferably 90% or more. Two or more polyester resins may be used in combination.

Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, orthophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-biphenyldicarboxylic acid, and 4,4′-biphenyl ether. Dicarboxylic acid, 4,4'-biphenylmethane dicarboxylic acid, 4,4'-biphenylsulfone dicarboxylic acid, 4,4'-biphenylisopropylidenedicarboxylic acid, 1,2-bis (phenoxy) ethane-4,4'-dicarboxylic Acid, 2,5-anthracene dicarboxylic acid, 2,6-anthracene dicarboxylic acid, 4,4′-p-terphenylene dicarboxylic acid, 2,5-pyridinedicarboxylic acid, and the like (for example, 5 -Alkyl group-substituted products such as methyl isophthalic acid) and reactive derivatives (eg, Dimethyl phthalate, and alkyl ester derivatives such as diethyl terephthalate) and the like can also be used. Among these, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, and alkyl ester derivatives thereof are more preferable.

These aromatic dicarboxylic acids may be used alone or in combination of two or more, and together with the aromatic dicarboxylic acid, an aliphatic dicarboxylic acid such as adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, etc. One or more alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid may be used in combination.

Examples of the aliphatic diol include ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, Aliphatic diols such as decamethylene glycol and 2,2-dimethyl-1,3-propanediol; 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, cyclohexanediol, trans- or cis-2 Alicyclic diols such as 1,2,4,4-tetramethyl-1,3-cyclobutanediol; p-xylenediol, bisphenol A, tetrabromobisphenol A, tetrabromobisphenol A-bis (2-hydroxyethyl) Aromatic diols such as ether) It can, can also be used these substituents.

Of these, ethylene glycol, 1,3-propanediol, 1,4-butanediol, and 1,4-cyclohexanedimethanol are preferable from the viewpoint of heat resistance of the binder resin, and ethylene glycol and 1,3-propanediol are more preferable. 1,4-butanediol is preferred, and ethylene glycol is particularly preferred.

These diols may be used alone or in combination of two or more. Further, as the diol component, a long chain diol having a molecular weight of 400 to 6000, specifically, one or more of polyethylene glycol, poly-1,3-propylene glycol, polytetramethylene glycol and the like are used in combination with the diols. And may be copolymerized.

As the polyester resin, monoalcohols such as butyl alcohol, hexyl alcohol, and octyl alcohol, and polyhydric alcohols such as trimethylolpropane, glycerin, and pentaerythritol can be used as long as the object of the present invention is not impaired.

A known esterification method or transesterification method can be applied to the production of the polyester resin. Examples of the polycondensation catalyst used in the production of the polyester resin include known antimony compounds such as antimony trioxide and antimony pentoxide, germanium compounds such as germanium oxide, titanium compounds such as titanium acetate, and aluminum compounds such as aluminum chloride. Although it can, it is not limited to these.

Preferred polyester resins include polyethylene terephthalate resin (PET), polyethylene terephthalate-isophthalate copolymer resin, polyethylene-1,4-cyclohexanedimethylene-terephthalate copolymer resin, polyethylene-2,6-naphthalene dicarboxylate resin, polyethylene -2,6-naphthalene dicarboxylate-terephthalate copolymer resin, polyethylene-terephthalate-4,4'-biphenyldicarboxylate resin, poly-1,3-propylene-terephthalate resin, polybutylene terephthalate resin, polybutylene-2, 6-naphthalene dicarboxylate resin, polybutylene succinate resin (PBS), polybutylene succinate adipate resin (PBSA), polyethylene succinate tree (PES), polybutylene succinate-carbonate resin (PBSC), and the like polyethylene succinate terephthalate resin (PEST).

More preferable polyester resins include polyethylene terephthalate resin, polyethylene terephthalate-isophthalate copolymer resin, polyethylene-1,4-cyclohexanedimethylene-terephthalate copolymer resin, polybutylene terephthalate resin, and polyethylene-2,6-naphthalene dicarboxylate. Resin, polybutylene succinate resin (PBS), and polybutylene succinate adipate resin (PBSA).

The intrinsic viscosity (value measured at 25 ° C. in a mixed solvent of phenol / 1,1,2,2-tetrachloroethane = 60/40 mass ratio) of the polyester resin is in the range of 0.7 to 2.0 cm ³ / g. More preferably, it is in the range of 0.8 to 1.5 cm ³ / g. Since the molecular weight of the polyester resin is sufficiently high when the intrinsic viscosity is 0.7 or more, the molded product made of the polyester resin composition obtained by using the polyester resin has mechanical properties necessary for the molded product and is transparent. Property is improved. When the intrinsic viscosity is 2.0 or less, the moldability is good.

<Other additives>
In order to facilitate handling, the polyester film according to the present invention may contain particles within a range that does not impair transparency. Examples of particles used in the present invention include inorganic particles such as calcium carbonate, calcium phosphate, silica, kaolin, talc, titanium dioxide, alumina, barium sulfate, calcium fluoride, lithium fluoride, zeolite, molybdenum sulfide, and crosslinked polymers. Examples thereof include organic particles such as particles and calcium oxalate. Examples of the method of adding particles include a method of adding particles in a polyester as a raw material, a method of adding directly to an extruder, and the like. Well, you may use two methods together. In the present invention, additives may be added in addition to the above particles as necessary. Examples of such additives include plasticizers, stabilizers, lubricants, crosslinking agents, antiblocking agents, antioxidants, dyes, pigments, ultraviolet absorbers, and the like.

[1.2] Method for Producing Polyester Film A method for producing a polyester film according to the present invention includes a step of forming a melt-extruded film on a drum of a polyester resin melt, a step of peeling the film from the drum, Stretching the peeled film in the longitudinal direction with a heated roller and then stretching in the transverse direction while holding both ends of the film with a clip in the tenter, and then heat setting (relaxing heat treatment process) while relaxing the strain with the clip Preferably, this relaxation heat treatment step can be used to control the heat shrinkage rate within a desired range.

Also, in order to align the thermal shrinkage in the longitudinal direction (also referred to as MD direction or longitudinal direction) and the lateral direction (also referred to as TD direction or lateral direction), the longitudinal direction in the tenter is not longitudinal stretching with a heat roller. It is also preferable to perform biaxial stretching in the transverse direction and to perform relaxation heat treatment both longitudinally and laterally.

The polyester film according to the present invention is obtained by heating and melting a composition containing other additives such as a polyester resin and a plasticizer to a temperature showing fluidity, and then casting a melt containing the fluid polyester resin. Can be manufactured.

In the melt casting film forming method, the melt extrusion method is preferable from the viewpoint of mechanical strength and surface accuracy. A plurality of raw materials used for melt extrusion are usually preferably kneaded and pelletized in advance.

Pelletization may be performed by a known method. For example, dry cellulose ester, plasticizer, and other additives are fed to an extruder using a feeder and kneaded using a single-screw or twin-screw extruder, and then formed into a strand from a die. It can be done by extrusion, water cooling or air cooling and cutting.

Additives may be mixed before being supplied to the extruder, or may be supplied by individual feeders.

A small amount of additives such as particles and antioxidants are preferably mixed in advance in order to mix uniformly.

The extruder is preferably processed at a temperature as low as possible so that it can be pelletized so that the shearing force is suppressed and the resin does not deteriorate (molecular weight reduction, coloring, gel formation, etc.). For example, in the case of a twin screw extruder, it is preferable to rotate in the same direction using a deep groove type screw. From the uniformity of kneading, the meshing type is preferable.

Film formation is performed using the pellets obtained as described above. Of course, the raw material powder can be directly fed to the extruder by a feeder without being pelletized to form a film as it is.

Using a single-screw or twin-screw type extruder, the melting temperature at the time of extrusion is about 200-300 ° C, filtered through a leaf disk type filter, etc. to remove foreign matter, and then formed into a film from a T-die. A polyester film is formed by niping the film with a cooling roller and an elastic touch roller and solidifying the film on the cooling roller.

When introducing into the extruder from the supply hopper, it is preferable to prevent oxidative decomposition or the like under vacuum, reduced pressure, or inert gas atmosphere.

The extrusion flow rate is preferably adjusted stably by introducing a gear pump or the like. Further, a stainless fiber sintered filter is preferably used as a filter used for removing foreign substances. The stainless steel fiber sintered filter is a united stainless steel fiber body that is intricately intertwined and compressed, and the contact points are sintered and integrated. The density of the fiber is changed depending on the thickness of the fiber and the amount of compression, and the filtration accuracy is improved. Can be adjusted.

Additives such as plasticizers and particles may be mixed with the resin in advance, or may be kneaded in the middle of the extruder. In order to add uniformly, it is preferable to use a mixing apparatus such as a static mixer.

The polyester film temperature on the touch roller side when the polyester film is nipped with a cooling roller and a touch roller (also referred to as a take-off roller) is preferably Tg (Tg + 110 ° C.) or less of the film. The touch roller used for such a purpose is preferably a roller having an elastic surface from the viewpoint of preventing scratches on the film surface, and a known roller for the touch roller can be used.

The touch roller is also called a pinching rotator. A commercially available touch roller can also be used.

When peeling the polyester film from the cooling roller, it is preferable to control the tension to prevent deformation of the film.

Moreover, it is preferable that the polyester film film obtained as described above is stretched by a stretching operation after passing through the step of contacting the cooling roller.

The polyester film may be an unstretched film or a stretched film, but is preferably stretched. In the case of stretching, the film may be uniaxially stretched in the longitudinal direction or the transverse direction, or may be stretched in the biaxial direction of the longitudinal direction and the transverse direction. When a biaxially stretched film is used, it may be biaxially stretched simultaneously or sequentially biaxially stretched. In the case of biaxial stretching, the mechanical strength is improved and the film performance is improved.

There is no particular limitation on the stretching method. For example, a method in which a circumferential speed difference is applied to a plurality of rollers, and the film is stretched in the longitudinal direction by utilizing the difference between the circumferential speeds of the rollers. And a method of stretching in the vertical direction, a method of stretching in the horizontal direction and stretching in the horizontal direction, a method of stretching in the vertical and horizontal directions, and stretching in both the vertical and horizontal directions. Of course, these methods may be used in combination.

In the case of the so-called tenter method, driving the clip portion by the linear drive method is preferable because smooth stretching can be performed and the risk of breakage and the like can be reduced. The tenter may be a pin tenter or a clip tenter.

The stretching temperature when performing the stretching step is preferably in the vicinity of the glass transition temperature of the polyester resin of the film raw material, specifically, (glass transition temperature-30) ° C. to (glass transition temperature + 100) ° C. It is preferably (glass transition temperature−20) ° C. to (glass transition temperature + 80) ° C. If the stretching temperature is (glass transition temperature −30) ° C. or higher, a sufficient stretching ratio can be obtained, and if the stretching temperature is within (glass transition temperature + 100) ° C., the resin flow hardly occurs and is stable. It is preferable because it can be stretched.

The draw ratio defined by the area ratio is preferably in the range of 1.1 to 25 times, more preferably in the range of 1.3 to 10 times. A stretching ratio of 1.1 times or more is preferable because it leads to an improvement in toughness accompanying stretching. If the draw ratio is within 25 times, the effect of only increasing the draw ratio can be obtained, and breakage and the like can be suppressed.

The stretching speed (one direction) is preferably in the range of 10 to 20000% / min, more preferably in the range of 100 to 10000% / min. If it is 10% / min or more, it can be performed in a short time to obtain a sufficient draw ratio, which is preferable in terms of productivity. If it is less than 20000% / min, the stretched film hardly breaks, which is preferable.

The polyester film according to the present invention is preferably heat-set by being left in the range of about 1 to 10 minutes while maintaining the temperature after the stretching, in order to fix the deformation of the resin molecules due to the stretching.

Furthermore, it is preferable to manufacture by a relaxation heat treatment step, and it is possible to control the heat shrinkage rate within a desired range by performing the relaxation heat treatment.

Relaxation heat treatment is the process of stretching the polyester film in the stretching process, then releasing the tension applied to the film in the stretching device, for example, in the tenter or until winding after exiting the tenter. In addition, the process of intentionally reducing the width of the clip holding the film edge is performed, and the relaxation rate can be obtained by the following equation (S).

Formula (S) Relaxation rate (%) = (AB) / A × 100
(In the formula, A: width of the film stretched (unit: m), B: width after shrinking (unit: m))
The relaxation heat treatment is preferably performed at a treatment temperature in the range of 80 to 200 ° C., and more preferably at a treatment temperature in the range of 100 to 180 ° C. Further, both in the longitudinal direction and in the lateral direction, the relaxation rate is preferably within a range of 0.1 to 10%, and more preferably, the relaxation rate is within a range of 2 to 6%.

The polyester film that has been subjected to the relaxation heat treatment is further wound through a drying step if necessary.

Before winding, the end may be slit and cut to the product width, and knurled (embossed) may be applied to both ends to prevent sticking and scratching during winding. The knurling method can be performed by heating or pressurizing using a metal ring having an uneven pattern on the side surface. Clip holding parts such as tenters at both ends of the film are usually cut out and reused because the polyester film is deformed and cannot be used as a product.

[1.3] Physical properties of polyester film The thickness of the polyester film according to the present invention needs to be 5 μm or more from the viewpoint of the mechanical strength of the film, but is preferably in the range of 5 to 200 μm. More preferably, it is in the range of 15 to 100 μm, and still more preferably in the range of 20 to 70 μm. If the thickness of the polyester film is 5 μm or more, wrinkles or the like are less likely to occur during handling, and if the thickness is 200 μm or less, the handleability and transparency are excellent, and a thin film support can be provided. it can.

The ratio value (A / B) of the film thicknesses of the polyester film A and the polyester film B according to the present invention is preferably in the range of 90/10 to 50/50. More preferably, it is in the range of 90/10 to 60/40.

When the polyester film A is bonded to the concave portion of the curved glass, the curl direction when the polyester film A is heat-shrinked when the thickness of the polyester film A is equal to or thicker than the thickness of the polyester film B is the curved shape of the glass. Therefore, it is estimated that the curved surface followability is improved.

The polyester film according to the present invention is preferably long, specifically, preferably has a length of about 100 to 10,000 m, and is wound up in a roll shape. The width of the support is preferably 1 m or more, more preferably 1.4 m or more, and particularly preferably 1.4 to 4 m.

As the optical characteristics of the polyester film according to the present invention, the visible light transmittance measured by JIS S3107 (2013) is preferably 60% or more, more preferably 70% or more, and further preferably 80% or more. It is.

The haze is preferably less than 1%, and more preferably less than 0.5%. By setting the haze to less than 1%, there is an advantage that the transparency of the film becomes higher and it becomes easier to use as a film for optical applications.

[2] Optical functional layer The window film of the present invention preferably contains a layer for controlling the reflectance and transmittance of a specific wavelength, and in particular, a near-infrared absorbing layer or a near-infrared ray that selectively absorbs near-infrared rays. Having a near-infrared reflective layer that selectively reflects is preferable for use as a heat-shielding film.

When the pinhole is vacated due to scratches on the heat-insulating layer, the heat-shielding property of the portion is deteriorated. The configuration of the present invention is also a preferable aspect from the point that it is possible to suppress the occurrence of scratches due to external force by sandwiching.

[2.1] Near-infrared absorption layer Although it does not restrict | limit especially as a material contained in a near-infrared absorption layer, For example, the ultraviolet curable resin which is a binder component, a photoinitiator, an infrared absorber, etc. are mentioned. It is preferable that the binder component contained in the near-infrared absorbing layer is cured. Here, the curing means that the reaction proceeds and cures by active energy rays such as ultraviolet rays or heat.

The inorganic infrared absorber contained in the near infrared absorbing layer is preferably a metal oxide particle from the viewpoint of visible light transmittance, near infrared absorptivity, suitability for dispersion in a resin, for example, tin oxide, Examples thereof include zinc oxide, titanium oxide, tungsten oxide, and indium oxide. Specific examples of heat-absorbing particles include aluminum-doped tin oxide particles, indium-doped tin oxide particles, antimony-doped tin oxide (ATO) particles, gallium-doped zinc oxide (GZO) particles, indium-doped zinc oxide (IZO) particles, aluminum-doped Zinc oxide (AZO) particles, niobium doped titanium oxide particles, tin doped indium oxide (ITO) particles, tin doped zinc oxide particles, silicon doped zinc oxide particles, general formula MxWyOz (where M is H, He, alkali metal, alkaline earth) Metal, rare earth element, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge , Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, M , Ta, Re, Be, Hf, Os, Bi, I, one or more elements, W is tungsten, O is oxygen, 0.001 ≦ x / y ≦ 1, 2.2 <z / composite tungsten oxide fine particles represented by y ≦ 3.0) and general formula XB ₆ (wherein element X is La, Ce, Pr, Nd, Gd, Tb, Dy, Ho, Y, Sm, Eu) , Er, Tm, Yb, Lu, Sr, or Ca).

Among these, tin-doped indium oxide (ITO), antimony-doped tin oxide (ATO), cesium-containing tungsten oxide (Cs _0.33 WO ₃ ) and the like are preferable. These may be used alone or in combination of two or more. The average particle size of the inorganic infrared absorber is preferably 5 to 100 nm, more preferably 10 to 50 nm. If it is 5 nm or more, the dispersibility in the resin and the near-infrared absorption are improved. On the other hand, if it is 100 nm or less, the visible light transmittance does not decrease. The average particle size is measured by taking an image with a transmission electron microscope, randomly extracting, for example, 50 particles, measuring the particle size, and averaging the results. Moreover, when the shape of particle | grains is not spherical, it defines as what was calculated by measuring a major axis.

The content of the inorganic infrared absorber in the near-infrared absorbing layer is preferably 1 to 80% by mass, and more preferably 5 to 50% by mass with respect to the total mass of the near-infrared absorbing layer. If the content is 1% or more, a sufficient near-infrared absorption effect appears, and if it is 80% or less, a sufficient amount of visible light can be transmitted.

Organic infrared absorbing materials include polymethine, phthalocyanine, naphthalocyanine, metal complex, aminium, imonium, diimonium, anthraquinone, dithiol metal complex, naphthoquinone, indolephenol, azo And triallylmethane compounds. Particularly preferred are metal complex compounds, aminium compounds (aminium derivatives), phthalocyanine compounds (phthalocyanine derivatives), naphthalocyanine compounds (naphthalocyanine derivatives), diimonium compounds (diimonium derivatives), squalium compounds (squarium derivatives), and the like. Used.

The near-infrared absorbing layer may contain other infrared absorbers such as metal oxides, organic infrared absorbers, metal complexes and the like other than those described above within the scope of the effects of the present invention. Specific examples of such other infrared absorbers include, for example, diimonium compounds, aluminum compounds, phthalocyanine compounds, organometallic complexes, cyanine compounds, azo compounds, polymethine compounds, quinone compounds, diphenylmethane compounds. And triphenylmethane compounds.

The ultraviolet curable resin used as the binder component is superior in hardness and smoothness to other resins, and further tin-doped indium oxide (ITO), antimony-doped tin oxide (ATO), cesium-containing tungsten oxide (Cs _0.33 WO _3). ) And the dispersibility of the thermally conductive metal oxide is also advantageous. The ultraviolet curable resin can be used without particular limitation as long as it forms a transparent layer by curing, and examples thereof include silicone resins, epoxy resins, vinyl ester resins, acrylic resins, and allyl ester resins. More preferred is an acrylic resin from the viewpoint of hardness, smoothness and transparency.

The acrylic resin is a reactive silica particle in which a photosensitive group having photopolymerization reactivity is introduced on its surface as described in International Publication No. 2008/035669 from the viewpoint of hardness, smoothness, and transparency. (Hereinafter also simply referred to as “reactive silica particles”). Here, examples of the photopolymerizable photosensitive group include a polymerizable unsaturated group represented by a (meth) acryloyloxy group. The ultraviolet curable resin contains a photopolymerizable photosensitive group introduced on the surface of the reactive silica particles and a compound capable of photopolymerization, for example, an organic compound having a polymerizable unsaturated group. There may be. In addition, a polymerizable unsaturated group-modified hydrolyzable silane reacts with a silica particle that forms a silyloxy group and is chemically bonded to the silica particle by a hydrolysis reaction of the hydrolyzable silyl group. Can be used as conductive silica particles. Here, the average particle diameter of the reactive silica particles is preferably in the range of 0.001 to 0.1 μm. By setting the average particle diameter in such a range, transparency, smoothness, and hardness can be satisfied in a well-balanced manner.

As the photopolymerization initiator, known ones can be used, and they can be used alone or in combination of two or more.

The thickness of the near infrared absorbing layer is preferably in the range of 0.1 to 50 μm, and more preferably in the range of 1 to 20 μm. If it is 0.1 μm or more, the infrared absorption ability tends to be improved, while if it is 50 μm or less, the crack resistance of the coating film is improved.

The method for forming the near infrared absorbing layer is not particularly limited. For example, the near infrared absorbing layer containing the above-mentioned components is prepared by applying a coating solution for the near infrared absorbing layer, applying the coating solution using a wire bar, and drying. And the like.

[2.2] Near-infrared reflective layer The near-infrared reflective layer according to the present invention is not particularly limited, and is a commercially available infrared reflective film manufactured by 3M as described in US Pat. No. 6,049,419. (3M Scotch Tent (registered trademark) multi-layer NANO series: transparent infrared reflective film having a light transmittance of less than 20% in the light wavelength range of 850 to 1100 nm) and multilayers described in JP2012-81748A Film (a film in which 50 or more layers of two or more thermoplastic resins having different optical properties are alternately laminated. The average reflectance at a light wavelength of 400 to 700 nm is 15% or less, and a light wavelength of 900 to The average reflectivity at 1200 nm is 70% or more.) And the metal oxide and binder described in Table 2012/057199. The near-infrared reflective film etc. which laminated | stacked many high refractive index layers and low refractive index layers alternately can be used.

Among them, the near-infrared reflective layer according to the present invention includes a high refractive index layer containing the first water-soluble binder resin and the first metal oxide particles, and the second water-soluble binder resin and the second metal oxide. A layer in which a large number of low refractive index layers containing physical particles are alternately laminated is preferable.

The near-infrared reflective layer used in the present invention may have any structure including at least one laminate (unit) composed of a high refractive index layer and a low refractive index layer. It is preferable to have a configuration in which two or more of the above laminates composed of low refractive index layers are laminated. In this case, the uppermost layer and the lowermost layer of the near-infrared reflective layer may be either a high refractive index layer or a low refractive index layer, but both the uppermost layer and the lowermost layer are preferably low refractive index layers. When the uppermost layer is a low refractive index layer, the coating property is improved, and when the lowermost layer is a low refractive index layer, it is preferable from the viewpoint of improving the adhesion to the substrate.

Here, whether an arbitrary refractive index layer of the near-infrared reflective layer is a high refractive index layer or a low refractive index layer is determined by comparing the refractive index with the adjacent refractive index layer. Specifically, when a refractive index layer is used as a reference layer, if the refractive index layer adjacent to the reference layer has a lower refractive index than the reference layer, the reference layer is a high refractive index layer (the adjacent layer is a low refractive index layer). It is judged to be a rate layer.) On the other hand, if the refractive index of the adjacent layer is higher than that of the reference layer, it is determined that the reference layer is a low refractive index layer (the adjacent layer is a high refractive index layer). Therefore, whether the refractive index layer is a high refractive index layer or a low refractive index layer is a relative one determined by the relationship with the refractive index of the adjacent layer. Depending on the relationship, it can be a high refractive index layer or a low refractive index layer.

Here, there are two components constituting the high refractive index layer (hereinafter also referred to as “high refractive index layer component”) and components constituting the low refractive index layer (hereinafter also referred to as “low refractive index layer component”). In some cases, a layer (mixed layer) containing the high refractive index layer component and the low refractive index layer component is mixed at the interface of the two layers. In this case, in the mixed layer, a set of portions where the high refractive index layer component is 50% by mass or more is defined as a high refractive index layer, and a set of portions where the low refractive index layer component exceeds 50% by mass is defined as a low refractive index layer. . Specifically, when the low refractive index layer includes, for example, different metal oxide particles in the low refractive index layer and the high refractive index layer, the concentration profile of the metal oxide particles in the layer thickness direction in these laminated films , And the composition can determine whether the mixed layer that can be formed is a high refractive index layer or a low refractive index layer. The concentration profile of the metal oxide particles in the laminated film is sputtered at a rate of 0.5 nm / min using the XPS surface analyzer, etching from the surface to the depth direction, with the outermost surface being 0 nm. It can be observed by measuring the atomic composition ratio. Further, even when the metal oxide particles are not contained in the low refractive index component or the high refractive index component and are formed only from the water-soluble resin, similarly, in the concentration profile of the water-soluble resin, for example, It was confirmed that the mixed region was present by measuring the carbon concentration in the layer thickness direction, and further, its composition was measured by EDX (energy dispersive X-ray spectroscopy), and was etched by sputtering. Each layer can be regarded as a high refractive index layer or a low refractive index layer.

The XPS surface analyzer is not particularly limited, and any model can be used, but ESCALAB-200R manufactured by VG Scientific Fix Co. was used. Mg is used for the X-ray anode, and measurement is performed at an output of 600 W (acceleration voltage: 15 kV, emission current: 40 mA).

In general, in the near-infrared reflective layer, it is possible to design a large difference in refractive index between the low refractive index layer and the high refractive index layer, from the viewpoint that the infrared light reflectance can be increased with a small number of layers. preferable. In this embodiment, in at least one of the laminates (units) composed of the low refractive index layer and the high refractive index layer, the difference in refractive index between the adjacent low refractive index layer and high refractive index layer is 0.1 or more. Preferably, it is 0.3 or more, more preferably 0.35 or more, and particularly preferably 0.4 or more. When the near-infrared reflective layer has two or more laminates (units) of a high refractive index layer and a low refractive index layer, the refraction of the high refractive index layer and the low refractive index layer in all the laminates (units) It is preferable that the rate difference is within the preferable range. However, even in this case, the refractive index layer constituting the uppermost layer or the lowermost layer of the near-infrared reflective layer may be configured outside the above-described preferred range.

From the above viewpoint, the number of refractive index layers of the near-infrared reflective layer (units of high refractive index layer and low refractive index layer) is preferably 100 layers or less, that is, 50 units or less, and 40 layers (20 Unit) or less, and more preferably 20 layers (10 units) or less.

Since the reflection at the interface between adjacent layers depends on the refractive index ratio between the layers, the higher the refractive index ratio, the higher the reflectance. In addition, when the optical path difference between the reflected light on the surface of the layer and the reflected light on the bottom of the layer is a relationship expressed by n · d = wavelength / 4 when viewed as a single layer film, the reflected light is controlled to be strengthened by the phase difference. The reflectance can be increased. Here, n is the refractive index, d is the physical film thickness of the layer, and n · d is the optical film thickness. By utilizing this optical path difference, reflection can be controlled. Using this relationship, the refractive index and film thickness of each layer are controlled to control the reflection of visible light and near infrared light.

That is, the reflectance in a specific wavelength region can be increased by the refractive index of each layer, the film thickness of each layer, and the way of stacking each layer.

In the near-infrared reflective layer according to the present invention, the thickness per layer of the high refractive index layer is preferably in the range of 20 to 800 nm, and more preferably in the range of 50 to 350 nm. The thickness of the low refractive index layer per layer is preferably in the range of 20 to 800 nm, and more preferably in the range of 50 to 350 nm.

Here, when measuring the thickness of each layer per layer, the high refractive index layer and the low refractive index layer may have a clear interface between them or may be gradually changed. When the interface gradually changes, the maximum refractive index−minimum refractive index = Δn in the region where the refractive index continuously changes due to the mixing of the layers, the minimum refractive index between two layers + Δn The point of / 2 is regarded as the layer interface.

When the optical film of the present invention is used as a heat-shielding window film, a multilayer film in which films having different refractive indexes are laminated on a polymer film is formed, and the transmittance in the visible light region indicated by JIS R3106-1998 is formed. It is preferable to design the optical film thickness and unit so as to have a region with a reflectance exceeding 40% in a region of a wavelength of 900 to 1400 nm.

<Refractive index layer: high refractive index layer and low refractive index layer>
(High refractive index layer)
The high refractive index layer contains the first water-soluble binder resin and the first metal oxide particles, and may contain a curing agent, other binder resin, a surfactant, and various additives as necessary. Good.

The refractive index of the high refractive index layer used in the present invention is preferably 1.80 to 2.50, more preferably 1.90 to 2.20.

(First water-soluble binder resin)
When the first water-soluble binder resin used in the present invention is dissolved in water at a concentration of 0.5 mass% at the temperature at which the water-soluble binder resin is most dissolved, the G2 glass filter (maximum pores 40 to 40) is used. 50 mass), the mass of the insoluble matter that is filtered off when it is filtered is within 50 mass% of the added water-soluble binder resin.

The weight average molecular weight of the first water-soluble binder resin used in the present invention is preferably in the range of 1,000 to 200,000. Further, it is more preferably within the range of 3000 to 40000.

The weight average molecular weight referred to in the present invention can be measured by a known method, for example, static light scattering, gel permeation chromatography (GPC), time-of-flight mass spectrometry (TOF-MASS), etc. In the present invention, it is measured by a gel permeation chromatography method which is a generally known method.

The content of the first water-soluble binder resin in the high refractive index layer is preferably within the range of 5 to 50% by mass with respect to the solid content of 100% by mass of the high refractive index layer. It is more preferable to be within the range.

The first water-soluble binder resin applied to the high refractive index layer is preferably polyvinyl alcohol. Moreover, it is preferable that the water-soluble binder resin which exists in the low-refractive-index layer mentioned later is also polyvinyl alcohol. Therefore, in the following, polyvinyl alcohol contained in the high refractive index layer and the low refractive index layer will be described together.

<Polyvinyl alcohol>
In the present invention, the high refractive index layer and the low refractive index layer preferably contain two or more types of polyvinyl alcohol having different saponification degrees. Here, in order to distinguish, polyvinyl alcohol as a water-soluble binder resin used in the high refractive index layer is polyvinyl alcohol (A), and polyvinyl alcohol as a water-soluble binder resin used in the low refractive index layer is polyvinyl alcohol (B). That's it. In addition, when each refractive index layer contains a plurality of polyvinyl alcohols having different saponification degrees and polymerization degrees, the polyvinyl alcohol having the highest content in each refractive index layer is changed to polyvinyl alcohol (A ) And polyvinyl alcohol (B) in the low refractive index layer.

In the present invention, the “degree of saponification” is the ratio of hydroxy groups to the total number of acetyloxy groups (derived from the starting vinyl acetate) and hydroxy groups in polyvinyl alcohol.

In addition, when referring to “polyvinyl alcohol having the highest content in the refractive index layer” herein, the degree of polymerization is calculated assuming that the polyvinyl alcohol having a saponification degree difference of 3 mol% or less is the same polyvinyl alcohol. . However, a low polymerization degree polyvinyl alcohol having a polymerization degree of 1000 or less is a different polyvinyl alcohol (even if there is a polyvinyl alcohol having a saponification degree difference of 3 mol% or less, it is not regarded as the same polyvinyl alcohol). Specifically, when polyvinyl alcohol having a saponification degree of 90 mol%, a saponification degree of 91 mol%, and a saponification degree of 93 mol% is contained in the same layer by 10 mass%, 40 mass%, and 50 mass%, respectively. These three polyvinyl alcohols are the same polyvinyl alcohol, and these three mixtures are polyvinyl alcohol (A) or (B). In addition, the above-mentioned “polyvinyl alcohol having a saponification degree difference of 3 mol% or less” suffices to be within 3 mol% when attention is paid to any polyvinyl alcohol. For example, 90 mol%, 91 mol%, 92 mol%, 94 mol % Of polyvinyl alcohol, when paying attention to 91 mol% of polyvinyl alcohol, the difference in saponification degree of any polyvinyl alcohol is within 3 mol%, so that the same polyvinyl alcohol is obtained.

The difference in the absolute value of the saponification degree between the polyvinyl alcohol (A) and the polyvinyl alcohol (B) is preferably 3 mol% or more, and more preferably 5 mol% or more. If it is such a range, since the interlayer mixing state of a high refractive index layer and a low refractive index layer will become a preferable level, it is preferable. Moreover, although the difference of the saponification degree of polyvinyl alcohol (A) and polyvinyl alcohol (B) is so preferable that it is separated, it is 20 mol% or less from the viewpoint of the solubility to water of polyvinyl alcohol. It is preferable.

In addition, the saponification degree of polyvinyl alcohol (A) and polyvinyl alcohol (B) is preferably 75 mol% or more from the viewpoint of solubility in water. Furthermore, the intermixed state of the high refractive index layer and the low refractive index layer is that one of the polyvinyl alcohol (A) and the polyvinyl alcohol (B) has a saponification degree of 90 mol% or more and the other is 90 mol% or less. Is preferable for achieving a preferable level. It is more preferable that one of the polyvinyl alcohol (A) and the polyvinyl alcohol (B) has a saponification degree of 95 mol% or more and the other is 90 mol% or less. In addition, although the upper limit of the saponification degree of polyvinyl alcohol is not specifically limited, Usually, it is less than 100 mol% and is about 99.9 mol% or less.

In addition, the polymerization degree of the two types of polyvinyl alcohols having different saponification degrees is preferably 1000 or more, particularly preferably those having a polymerization degree in the range of 1500 to 5000, more preferably in the range of 2000 to 5000. Those are more preferably used. This is because when the polymerization degree of polyvinyl alcohol is 1000 or more, there is no cracking of the coating film, and when it is 5000 or less, the coating solution is stabilized. In the present specification, “the coating solution is stable” means that the coating solution is stable over time. When the degree of polymerization of at least one of polyvinyl alcohol (A) and polyvinyl alcohol (B) is in the range of 2000 to 5000, it is preferable because cracks in the coating film are reduced and the reflectance at a specific wavelength is improved. It is preferable that both the polyvinyl alcohol (A) and the polyvinyl alcohol (B) are 2000 to 5000, since the above effects can be exhibited more remarkably.

“Polymerization degree P” in the present specification refers to the viscosity average degree of polymerization, and is measured according to JIS K6726 (1994). After PVA is completely re-saponified and purified, it is measured in water at 30 ° C. From the intrinsic viscosity [η] (cm ³ / g), it is obtained by the following formula (1).

Formula (1)
P = ([η] × 10 ³ /8.29) ^{(1 / 0.62)}
The polyvinyl alcohol (B) contained in the low refractive index layer preferably has a saponification degree in the range of 75 to 90 mol% and a polymerization degree in the range of 2000 to 5000. When polyvinyl alcohol having such characteristics is contained in the low refractive index layer, it is preferable in that interfacial mixing is further suppressed. This is considered to be because there are few cracks of a coating film and set property improves.

The polyvinyl alcohol (A) and (B) used in the present invention may be a synthetic product or a commercially available product. Examples of commercially available products used as the polyvinyl alcohol (A) and (B) include, for example, PVA-102, PVA-103, PVA-105, PVA-110, PVA-117, PVA-120, PVA-124, PVA -203, PVA-205, PVA-210, PVA-217, PVA-220, PVA-224, PVA-235 (manufactured by Kuraray Co., Ltd.), JC-25, JC-33, JF-03, JF-04 , JPF-05, JP-03, JP-04, JP-05, JP-45 (above, manufactured by Nippon Vinegar Poval Co., Ltd.) and the like.

As long as the first water-soluble binder resin used in the present invention does not impair the effects of the present invention, in addition to ordinary polyvinyl alcohol obtained by hydrolyzing polyvinyl acetate, modified polyvinyl alcohol partially modified Alcohol may be included. When such a modified polyvinyl alcohol is included, the adhesion, water resistance, and flexibility of the film may be improved. Examples of such modified polyvinyl alcohol include cation-modified polyvinyl alcohol, anion-modified polyvinyl alcohol, nonionic-modified polyvinyl alcohol, and vinyl alcohol polymers.

Examples of the cation-modified polyvinyl alcohol include primary to tertiary amino groups and quaternary ammonium groups in the main chain or side chain of the polyvinyl alcohol as described in JP-A-61-10383. It is obtained by saponifying a copolymer of an ethylenically unsaturated monomer having a cationic group and vinyl acetate.

Examples of the ethylenically unsaturated monomer having a cationic group include trimethyl- (2-acrylamido-2,2-dimethylethyl) ammonium chloride and trimethyl- (3-acrylamido-3,3-dimethylpropyl) ammonium chloride. N-vinylimidazole, N-vinyl-2-methylimidazole, N- (3-dimethylaminopropyl) methacrylamide, hydroxylethyltrimethylammonium chloride, trimethyl- (2-methacrylamidopropyl) ammonium chloride, N- (1, And 1-dimethyl-3-dimethylaminopropyl) acrylamide. The ratio of the cation-modified group-containing monomer of the cation-modified polyvinyl alcohol is 0.1 to 10 mol%, preferably 0.2 to 5 mol%, relative to vinyl acetate.

Anion-modified polyvinyl alcohol is described in, for example, polyvinyl alcohol having an anionic group as described in JP-A-1-206088, JP-A-61-237681 and JP-A-63-307979. Examples thereof include a copolymer of vinyl alcohol and a vinyl compound having a water-soluble group, and a modified polyvinyl alcohol having a water-soluble group as described in JP-A-7-285265.

Nonionic modified polyvinyl alcohol includes, for example, a polyvinyl alcohol derivative in which a polyalkylene oxide group is added to a part of vinyl alcohol as described in JP-A-7-9758, and JP-A-8-25795. Block copolymer of vinyl compound having hydrophobic group and vinyl alcohol, silanol-modified polyvinyl alcohol having silanol group, reactive group modification having reactive group such as acetoacetyl group, carbonyl group and carboxy group Polyvinyl alcohol etc. are mentioned.

Also, examples of vinyl alcohol polymers include EXEVAL (registered trademark, manufactured by Kuraray Co., Ltd.) and Nichigo G polymer (registered trademark, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.).

Two or more kinds of modified polyvinyl alcohol can be used in combination, such as the degree of polymerization and the type of modification.

The content of the modified polyvinyl alcohol is not particularly limited, but is preferably in the range of 1 to 30% by mass with respect to the total mass (solid content) of each refractive index. If it is in such a range, the said effect will be exhibited more.

In the present invention, it is preferable to use two types of polyvinyl alcohols having different saponification levels between layers having different refractive indexes.

For example, when polyvinyl alcohol (A) having a low saponification degree is used for the high refractive index layer and polyvinyl alcohol (B) having a high saponification degree is used for the low refractive index layer, the polyvinyl alcohol ( A) is preferably contained in the range of 40% by mass to 100% by mass with respect to the total mass of all polyvinyl alcohols in the layer, more preferably 60% by mass to 95% by mass, and the low refractive index layer The polyvinyl alcohol (B) is preferably contained in the range of 40% by mass to 100% by mass with respect to the total mass of all the polyvinyl alcohols in the low refractive index layer, and 60% by mass to 95% by mass. Is more preferable. When polyvinyl alcohol (A) having a high saponification degree is used for the high refractive index layer and polyvinyl alcohol (B) having a low saponification degree is used for the low refractive index layer, the polyvinyl alcohol ( A) is preferably contained in the range of 40% by mass to 100% by mass with respect to the total mass of all polyvinyl alcohols in the layer, more preferably 60% by mass to 95% by mass, and the low refractive index layer The polyvinyl alcohol (B) is preferably contained in the range of 40% by mass to 100% by mass with respect to the total mass of all the polyvinyl alcohols in the low refractive index layer, and 60% by mass to 95% by mass. More preferred. When the content is 40% by mass or more, interlayer mixing is suppressed, and the effect of less disturbance of the interface appears remarkably. On the other hand, if content is 100 mass% or less, stability of a coating liquid will improve.

(Other binder resins)
In the present invention, in the high refractive index layer, the first water-soluble binder resin other than polyvinyl alcohol is not limited as long as the high refractive index layer containing the first metal oxide particles can form a coating film. But it can be used without restriction. Moreover, also in the low refractive index layer described later, as the second water-soluble binder resin other than the polyvinyl alcohol (B), the low refractive index layer containing the second metal oxide particles is coated as described above. Any device can be used without limitation as long as it can be formed. However, in view of environmental problems and flexibility of the coating film, water-soluble polymers (particularly gelatin, thickening polysaccharides, polymers having reactive functional groups) are preferable. These water-soluble polymers may be used alone or in combination of two or more.

In the high refractive index layer, the content of other binder resin used together with polyvinyl alcohol preferably used as a water-soluble binder resin is in the range of 5 to 50% by mass with respect to 100% by mass of the solid content of the high refractive index layer. It can also be used within.

In the present invention, it is not necessary to use an organic solvent and it is preferable from the viewpoint of environmental conservation. Therefore, the binder resin is preferably composed of a water-soluble polymer. That is, in the present invention, a water-soluble polymer other than polyvinyl alcohol and modified polyvinyl alcohol may be used as the binder resin in addition to the polyvinyl alcohol and modified polyvinyl alcohol as long as the effect is not impaired. The water-soluble polymer is when it is filtered through a G2 glass filter (maximum pores 40-50 μm) when dissolved in water at a concentration of 0.5% by mass at the temperature at which the water-soluble polymer is most soluble. The mass of the insoluble matter separated by filtration is within 50% by mass of the added water-soluble polymer. Among such water-soluble polymers, gelatin, celluloses, thickening polysaccharides, or polymers having reactive functional groups are particularly preferable. These water-soluble polymers may be used alone or in combination of two or more.

(First metal oxide particles)
In the present invention, the first metal oxide particles applicable to the high refractive index layer are preferably metal oxide particles having a refractive index of 2.0 or more and 3.0 or less. More specifically, for example, titanium oxide, zirconium oxide, zinc oxide, alumina, colloidal alumina, lead titanate, red lead, yellow lead, zinc yellow, chromium oxide, ferric oxide, iron black, copper oxide, oxidation Examples thereof include magnesium, magnesium hydroxide, strontium titanate, yttrium oxide, niobium oxide, europium oxide, lanthanum oxide, zircon, and tin oxide. In addition, composite oxide particles composed of a plurality of metals, core / shell particles whose metal structure changes into a core / shell shape, and the like can also be used.

In order to form a transparent and high refractive index layer having a higher refractive index, the high refractive index layer includes metal oxide fine particles having a high refractive index such as titanium and zirconium, that is, titanium oxide fine particles and / or zirconia oxide. It is preferable to contain fine particles. Among these, titanium oxide is more preferable from the viewpoint of the stability of the coating liquid for forming the high refractive index layer. Among titanium oxides, the rutile type (tetragonal type) has a lower catalytic activity than the anatase type, and the weather resistance of the high refractive index layer and the adjacent layer is higher, and the refractive index is higher. Is more preferable.

In the case where the core / shell particles are used as the first metal oxide particles in the high refractive index layer, due to the interaction between the silicon-containing hydrated oxide of the shell layer and the first water-soluble binder resin, From the effect of suppressing interlayer mixing between the high refractive index layer and the adjacent layer, core-shell particles in which titanium oxide particles are coated with a silicon-containing hydrated oxide are more preferable.

When the content of the first metal oxide particles used in the present invention is in the range of 15 to 80% by mass with respect to 100% by mass of the solid content of the high refractive index layer, the refractive index with the low refractive index layer This is preferable from the viewpoint of providing a difference. Furthermore, it is more preferably in the range of 20 to 77% by mass, and still more preferably in the range of 30 to 75% by mass. In addition, content in case metal oxide particles other than the said core-shell particle are contained in a high refractive index layer will not be specifically limited if it is a range which can have the effect of this invention.

In the present invention, the volume average particle size of the first metal oxide particles applied to the high refractive index layer is preferably 30 nm or less, more preferably in the range of 1 to 30 nm, and more preferably in the range of 5 to 15 nm. More preferably, it is in the range. A volume average particle size in the range of 1 to 30 nm is preferable from the viewpoint of low visible light transmittance and low haze.

The volume average particle diameter of the first metal oxide particles used in the present invention is a method of observing the particles themselves using a laser diffraction scattering method, a dynamic light scattering method, or an electron microscope, a refractive index layer, and the like. The particle diameter of 1000 arbitrary particles was measured by a method of observing the particle image appearing on the cross section or surface of the sample with an electron microscope, and particles having particle diameters of d1, d2,. In a population of n1, n2... Ni... Nk particulate metal oxides, where the volume per particle is vi, the volume average particle diameter mv = {Σ (vi · di )} / {Σ (vi)} is the average particle size weighted by the volume.

Furthermore, the first metal oxide particles used in the present invention are preferably monodispersed. The monodispersion here means that the monodispersity obtained by the following formula (2) is 40% or less. This monodispersity is more preferably 30% or less, and particularly preferably in the range of 0.1 to 20%.

Formula (2)
Monodispersity = (standard deviation of particle size) / (average value of particle size) × 100 (%)
<Core shell particle>
As the first metal oxide particles applied to the high refractive index layer used in the present invention, it is preferable to use “titanium oxide particles surface-treated with a silicon-containing hydrated oxide”. The titanium oxide particles may be referred to as “core / shell particles” or “Si-coated TiO ₂ ”.

In the core / shell particles used in the present invention, the titanium oxide particles are coated with a silicon-containing hydrated oxide, and the average particle diameter which is preferably a core portion is in the range of 1 to 30 nm, more preferably the average The surface of the titanium oxide particles having a particle size in the range of 4 to 30 nm has a coating amount of silicon-containing hydrated oxide in the range of 3 to 30% by mass as SiO _{2 with} respect to the titanium oxide as the core. In this way, a shell made of a silicon-containing hydrated oxide is coated.

That is, in the present invention, by including the core-shell particles, the interaction between the silicon-containing hydrated oxide of the shell layer and the first water-soluble binder resin causes the high refractive index layer and the low refractive index layer to The effect of suppressing the intermixing between the layers and the effect of preventing the deterioration of the binder and choking due to the photocatalytic activity of titanium oxide when titanium oxide is used as the core are exhibited.

In the present invention, the core / shell particles preferably have a silicon-containing hydrated oxide coating amount in the range of 3 to 30% by mass as SiO _{2 with} respect to titanium oxide as the core, more preferably 3 It is in the range of ˜10% by mass, more preferably in the range of 3 to 8% by mass. If the coating amount is 30% by mass or less, a high refractive index layer can be made to have a high refractive index, and if the coating amount is 3% by mass or more, core / shell particle particles can be stably formed. can do.

Furthermore, in the present invention, the average particle diameter of the core / shell particles is preferably in the range of 1 to 30 nm, more preferably in the range of 5 to 20 nm, and still more preferably in the range of 5 to 15 nm. . When the average particle diameter of the core / shell particles is in the range of 1 to 30 nm, optical properties such as near infrared reflectance, transparency, and haze can be further improved.

In addition, the average particle diameter as used in the field of this invention means a primary average particle diameter, and can be measured from the electron micrograph by a transmission electron microscope (TEM) etc. You may measure by the particle size distribution meter etc. which utilize a dynamic light scattering method, a static light scattering method, etc.

Moreover, when obtaining from an electron microscope, the average particle diameter of primary particles is the particle itself or the particles appearing on the cross section or surface of the refractive index layer are observed with an electron microscope, and the particle diameter of 1000 arbitrary particles is measured. It is obtained as its simple average value (number average). Here, the particle diameter of each particle is represented by a diameter assuming a circle equal to the projected area.

As a method for producing core / shell particles applicable to the present invention, a known method can be employed. For example, JP-A-10-158015, JP-A-2000-053421, JP-A-2000-063119. Reference can be made to JP-A-2000-204301, JP-A-4550753, and the like.

In the present invention, the silicon-containing hydrated oxide applied to the core / shell particles may be either a hydrate of an inorganic silicon compound, a hydrolyzate or a condensate of an organosilicon compound. In the present invention, silanol A compound having a group is preferable.

The core / shell particles used in the present invention may be those in which the entire surface of the titanium oxide particles that are the core is coated with a silicon-containing hydrated oxide, or part of the surface of the titanium oxide particles that are the core. It may be coated with a silicon hydrated oxide.

(Curing agent)
In the present invention, a curing agent can also be used to cure the first water-soluble binder resin applied to the high refractive index layer. For example, when polyvinyl alcohol is used as the first water-soluble binder resin, boric acid and its salt are preferable as the curing agent. Specific examples of the curing agent include, for example, epoxy curing agents (diglycidyl ethyl ether, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-diglycidyl cyclohexane, N, N-diglycidyl- 4-glycidyloxyaniline, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, etc.), aldehyde curing agents (formaldehyde, glioxal, etc.), active halogen curing agents (2,4-dichloro-4-hydroxy-1,3,5) , -S-triazine, etc.), active vinyl compounds (1,3,5-trisacryloyl-hexahydro-s-triazine, bisvinylsulfonylmethyl ether, etc.), aluminum alum and the like.

The content of the curing agent in the high refractive index layer is preferably 1 to 10% by mass and more preferably 2 to 6% by mass with respect to 100% by mass of the solid content of the high refractive index layer.

In particular, when polyvinyl alcohol is used as the first water-soluble binder resin, the total amount of the curing agent used is preferably 1 to 600 mg per 1 g of polyvinyl alcohol, more preferably 100 to 600 mg per 1 g of polyvinyl alcohol.

(Low refractive index layer)
The low refractive index layer used in the present invention includes a second water-soluble binder resin and second metal oxide particles, and further includes a curing agent, a surface coating component, a particle surface protective agent, a binder resin, and a surfactant. Various additives may be included.

The refractive index of the low refractive index layer used in the present invention is preferably in the range of 1.10 to 1.60, more preferably 1.30 to 1.50.

(Second water-soluble binder resin)
As the second water-soluble binder resin applied to the low refractive index layer used in the present invention, polyvinyl alcohol is preferably used. Furthermore, it is more preferable that polyvinyl alcohol (B) different from the saponification degree of polyvinyl alcohol (A) present in the high refractive index layer is used in the low refractive index layer used in the present invention. In addition, description about polyvinyl alcohol (A) and polyvinyl alcohol (B), such as a preferable weight average molecular weight of 2nd water-soluble binder resin here, is demonstrated by the water-soluble binder resin of the said high refractive index layer. The description is omitted here.

The content of the second water-soluble binder resin in the low refractive index layer is preferably in the range of 20 to 99.9% by mass with respect to 100% by mass of the solid content of the low refractive index layer, and 25 to 80 More preferably, it is in the range of mass%.

In the low refractive index layer, the content of other binder resin used together with polyvinyl alcohol preferably used as the second water-soluble binder resin is 0 to 10 mass with respect to 100 mass% of the solid content of the low refractive index layer. % Can also be used.

(Second metal oxide particles)
As the second metal oxide particles applied to the low refractive index layer used in the present invention, silica (silicon dioxide) is preferably used, and specific examples thereof include synthetic amorphous silica and colloidal silica. . Of these, it is more preferable to use an acidic colloidal silica sol.

The second metal oxide particles (preferably silicon dioxide) applied to the low refractive index layer preferably have an average particle size in the range of 3 to 100 nm. The average particle size of primary particles of silicon dioxide dispersed in a primary particle state (particle size in a dispersion state before coating) is more preferably in the range of 3 to 50 nm, and in the range of 3 to 40 nm. Is more preferably 3 to 20 nm, most preferably 4 to 10 nm. Moreover, as an average particle diameter of secondary particle | grains, it is preferable from a viewpoint with few hazes and excellent visible light transmittance | permeability that it is 30 nm or less.

The average particle size of the metal oxide particles applied to the low refractive index layer is determined by observing the particles themselves or the particles appearing on the cross section or surface of the refractive index layer with an electron microscope and measuring the particle size of 1000 arbitrary particles. The simple average value (number average) is obtained. Here, the particle diameter of each particle is represented by a diameter assuming a circle equal to the projected area.

The colloidal silica used in the present invention is obtained by heating and aging a silica sol obtained by metathesis with an acid of sodium silicate or the like and passing through an ion exchange resin layer. For example, JP-A-57-14091 JP, 60-219083, JP 60-218904, JP 61-20792, JP 61-188183, JP 63-17807, JP 4-207 No. 93284, JP-A-5-278324, JP-A-6-92011, JP-A-6-183134, JP-A-6-297830, JP-A-7-81214, JP-A-7-101142 Described in Japanese Patent Laid-Open No. 7-179029, Japanese Patent Laid-Open No. 7-137431, and International Publication No. 94/26530. Than is.

Such colloidal silica may be a synthetic product or a commercially available product. The surface of the colloidal silica may be cation-modified, or may be treated with Al, Ca, Mg, Ba or the like.

Hollow particles can also be used as the second metal oxide particles applied to the low refractive index layer. When hollow particles are used, the average particle pore diameter is preferably in the range of 3 to 70 nm, more preferably in the range of 5 to 50 nm, and still more preferably in the range of 5 to 45 nm. The average particle pore diameter of the hollow particles is the average value of the inner diameters of the hollow particles. In the present invention, when the average particle pore diameter of the hollow particles is in the above range, the refractive index of the low refractive index layer is sufficiently lowered. The average particle diameter is 50 or more at random, which can be observed as an ellipse in a circular, elliptical or substantially circular shape by electron microscope observation. Is obtained. The average particle hole diameter means the smallest distance among the distances between the outer edges of the hole diameter that can be observed as a circle, an ellipse, or a substantially circle or ellipse, between two parallel lines.

The content of the second metal oxide particles in the low refractive index layer is preferably 0.1 to 70% by mass, and preferably 30 to 70% by mass with respect to 100% by mass of the solid content of the low refractive index layer. More preferably, it is more preferably 45 to 65% by mass.

(Curing agent)
The low refractive index layer used in the present invention may further contain a curing agent, similar to the high refractive index layer. There is no particular limitation as long as it causes a curing reaction with the second water-soluble binder resin contained in the low refractive index layer. In particular, boric acid and its salt and / or borax are preferred as the curing agent when polyvinyl alcohol is used as the second water-soluble binder resin applied to the low refractive index layer. In addition to boric acid and its salts, known ones can be used.

The content of the curing agent in the low refractive index layer is preferably in the range of 1 to 10% by mass and preferably in the range of 2 to 6% by mass with respect to 100% by mass of the solid content of the low refractive index layer. It is more preferable.

Further, specific examples of the curing agent are the same as those of the above-described high refractive index layer, and thus the description thereof is omitted here.

[Other additives for each refractive index layer]
Various additives can be used in the high refractive index layer and the low refractive index layer used in the present invention, if necessary. The content of the additive in the high refractive index layer is preferably 0 to 20% by mass with respect to 100% by mass of the solid content of the high refractive index layer. Examples of the additive include surfactants, amino acids, emulsion resins, lithium compounds described in paragraphs [0140] to [0154] of JP2012-139948A and other additives described in paragraph [0155] of the same publication. Can be mentioned.

[Method of forming near-infrared reflective layer group]
The method for forming the near-infrared reflective layer used in the present invention is preferably formed by applying a wet coating method. Furthermore, the first water-soluble binder resin is formed on the polyester film A or polyester film B in the present invention. And wet coating the coating solution for the high refractive index layer containing the first metal oxide particles and the coating solution for the low refractive index layer containing the second water-soluble binder resin and the second metal oxide particles. The manufacturing method containing is preferable.

The wet coating method is not particularly limited. For example, roll coating method, rod bar coating method, air knife coating method, spray coating method, slide curtain coating method, US Pat. No. 2,761,419, US Pat. No. 2,761791 And a slide hopper coating method, an extrusion coating method and the like described in a book. In addition, as a method of applying a plurality of layers in a multilayer manner, a sequential multilayer application method or a simultaneous multilayer application method may be used.

Hereinafter, the simultaneous multilayer coating by the slide hopper coating method, which is a preferred manufacturing method (coating method) used in the present invention, will be described in detail.

(solvent)
The solvent applicable for preparing the coating solution for the high refractive index layer and the coating solution for the low refractive index layer is not particularly limited, but water, an organic solvent, or a mixed solvent thereof is preferable.

Examples of the organic solvent include alcohols such as methanol, ethanol, 2-propanol and 1-butanol, esters such as ethyl acetate, butyl acetate, propylene glycol monomethyl ether acetate and propylene glycol monoethyl ether acetate, diethyl ether and propylene. Examples include ethers such as glycol monomethyl ether and ethylene glycol monoethyl ether, amides such as dimethylformamide and N-methylpyrrolidone, and ketones such as acetone, methyl ethyl ketone, acetylacetone and cyclohexanone. These organic solvents may be used alone or in combination of two or more.

From the viewpoint of environment and simplicity of operation, the solvent of the coating solution is particularly preferably water or a mixed solvent of water and methanol, ethanol, or ethyl acetate.

(Concentration of coating solution)
The concentration of the water-soluble binder resin in the coating solution for the high refractive index layer is preferably in the range of 1 to 10% by mass. The concentration of the metal oxide particles in the coating solution for the high refractive index layer is preferably in the range of 1 to 50% by mass.

The concentration of the water-soluble binder resin in the coating solution for the low refractive index layer is preferably in the range of 1 to 10% by mass. The concentration of the metal oxide particles in the coating solution for the low refractive index layer is preferably in the range of 1 to 50% by mass.

(Method for preparing coating solution)
The method for preparing the coating solution for the high refractive index layer and the coating solution for the low refractive index layer is not particularly limited. For example, a water-soluble binder resin, metal oxide particles, and other additives added as necessary. The method of adding and stirring and mixing is mentioned. At this time, the order of addition of the water-soluble binder resin, the metal oxide particles, and other additives used as necessary is not particularly limited, and each component may be added and mixed sequentially while stirring. However, they may be added and mixed at once. If necessary, it is adjusted to an appropriate viscosity using a solvent.

In the present invention, it is preferable to form a high refractive index layer using an aqueous high refractive index coating solution prepared by adding and dispersing core / shell particles. At this time, the core / shell particles are added to the coating solution for the high refractive index layer as a sol having a pH measured in the range of 5.0 to 7.5 at 25 ° C. and a negative zeta potential of the particles. It is preferable to prepare it.

(Viscosity of coating solution)
The viscosity at 40 to 45 ° C. of the coating solution for the high refractive index layer and the coating solution for the low refractive index layer when performing simultaneous multilayer coating by the slide hopper coating method is preferably within the range of 5 to 150 mPa · s. -Within the range of s is more preferable. The viscosity at 40 to 45 ° C. of the coating solution for the high refractive index layer and the coating solution for the low refractive index layer when performing simultaneous multilayer coating by the slide curtain coating method is preferably within the range of 5 to 1200 mPa · s. A range of 25 to 500 mPa · s is more preferable.

The viscosity at 15 ° C. of the coating solution for the high refractive index layer and the coating solution for the low refractive index layer is preferably 100 mPa · s or more, more preferably in the range of 100 to 30000 mPa · s, and in the range of 3000 to 30000 mPa · s. The inside is more preferable, and the range of 10,000 to 30,000 mPa · s is particularly preferable.

(Coating and drying method)
The coating and drying method is not particularly limited, but the high refractive index layer coating solution and the low refractive index layer coating solution are heated to 30 ° C. or higher, and the high refractive index layer coating solution and the low refractive index are coated on the substrate. After the simultaneous application of the rate layer coating solution, the temperature of the formed coating film is preferably cooled (set) preferably to 1 to 15 ° C. and then dried at 10 ° C. or higher. More preferable drying conditions are a wet bulb temperature of 5 to 50 ° C. and a film surface temperature of 10 to 50 ° C. Moreover, as a cooling method immediately after application | coating, it is preferable to carry out by a horizontal set system from a viewpoint of the uniformity improvement of the formed coating film.

What is necessary is just to apply | coat so that the coating thickness of the coating liquid for high refractive index layers and the coating liquid for low refractive index layers may become the preferable thickness at the time of drying as shown above.

Here, the set means a step of increasing the viscosity of the coating composition and reducing the fluidity of substances in each layer and in each layer by means such as applying cold air to the coating to lower the temperature. To do. A state in which the cold air is applied to the coating film from the surface and the finger is pressed against the surface of the coating film is defined as a set completion state.

After application, the time (setting time) from application of cold air to completion of setting is preferably within 5 minutes, preferably within 2 minutes. Further, the lower limit time is not particularly limited, but it is preferable to take 45 seconds or more. If the set time is too short, there are places where mixing of the components in the layer becomes insufficient. On the other hand, if the set time is too long, the interlayer diffusion of the metal oxide particles proceeds, and the difference in refractive index between the high refractive index layer and the low refractive index layer is insufficient. In addition, if the high elasticity of the heat ray blocking film unit between the high refractive index layer and the low refractive index layer occurs quickly, the setting step may not be provided.

The set time is adjusted by adjusting the concentration of water-soluble binder resin and metal oxide particles, and adding other components such as various known gelling agents such as gelatin, pectin, agar, carrageenan, gellan gum, etc. Can be adjusted.

The temperature of the cold air is preferably 0 to 25 ° C, more preferably 5 to 10 ° C. Further, the time during which the coating film is exposed to the cold air is preferably 10 to 120 seconds, although it depends on the transport speed of the coating film.

FIG. 3 is an example of a window film of the present invention having a reflective layer formed of a multilayer film, and is a schematic cross-sectional view showing a configuration provided with a reflective layer unit having a reflective layer group on one surface side of a polyester film.

In FIG. 3, the window film 10 of the present invention has a reflective layer unit U. Furthermore, the reflective layer unit U includes, as an example, a high refractive index reflective layer containing a first water-soluble binder resin and first metal oxide particles, and a second water-soluble layer on the polyester film A (2). The reflective layer group ML is formed by alternately laminating a low refractive index reflective layer containing a conductive binder resin and second metal oxide particles. The reflective layer group ML is composed of n layers of reflective layers T ₁ to T _n , for example, T ₁ , T ₃ , T ₅ , (omitted), T _n−2 , T _n with a refractive index of 1.10 to It is composed of a low refractive index layer in the range of 1.60, and T ₂ , T ₄ , T ₆ , (omitted), and T _n-1 are high in the refractive index range of 1.80 to 2.50. An example of the configuration is a refractive index layer. The refractive index as used in the field of this invention is the value measured in the environment of 25 degreeC.

Further, a polyester film B (3) is laminated on the outermost layer of the reflective layer unit. Between the outermost layer of the reflective layer unit and the polyester film B (3), a hard coat layer for improving scratch resistance can be provided, and the surface of the polyester film A (2) where the reflective layer unit is not provided. It is also preferable to provide an adhesive layer 5 for bonding the window film to another substrate.

[2.3] Easy-Adhesion Layer Before providing the near-infrared absorbing layer or the near-infrared reflecting layer according to the present invention, the polyester film according to the present invention is preferably provided with an easy-adhesion layer.

The resin forming the easy adhesion layer is not particularly limited as long as it is highly transparent and durable. For example, acrylic resins, urethane resins, fluorine resins, silicone resins and the like can be used alone or as a mixture. These easy-adhesion layers are coated with a resin or resin composition solution by a known technique such as a gravure coating method, a reverse roll coating method, a roll coating method, a dip coating method, and after drying, ultraviolet rays as necessary. It can be formed by irradiating and curing with an electron beam. The thickness of the easy adhesion layer is preferably 0.5 to 5 μm, more preferably 1 to 3 μm. If the thickness of the easy-adhesion layer is thin, the surface of the substrate cannot be uniformly coated, and the effect of improving the corrosion resistance tends to be insufficient. On the other hand, even if it is formed too thick, no further improvement in scratch resistance is observed.

As the material for the easy adhesion layer, gelatin, polyvinyl alcohol, partially acetalized polyvinyl alcohol, hydrophilic resins such as vinyl acetate-maleic anhydride copolymer, and cellulose ester resins such as cellulose diacetate and cellulose nitrate are preferable. You may use individually or in mixture.

Effective solvents for the coating solution for the easy adhesion layer include acetone, methyl ethyl ketone, methanol, isopropanol, methylene chloride, ethylene chloride, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, 1-methoxy-2-propanol, ethyl acetate, dimethyl Formamide or the like can be used, and these may be mixed and used as necessary.

[2.4] Other functional layers The window film of the present invention has a conductive layer, an antistatic layer, a gas barrier layer, an antifouling layer, a deodorizing layer, a flow layer for the purpose of adding further functions on the polyester film. A droplet layer, a slippery layer, a hard coat layer, an abrasion resistant layer, an electromagnetic wave shielding layer, an ultraviolet absorption layer, a printing layer, a fluorescent light emitting layer, a hologram layer, a release layer, an adhesive layer, and the like may be provided.

[3] Laminated glass The laminated glass of the present invention has an adhesive layer represented by polyvinyl butyral (PVB), which is preferably a polyvinyl acetal resin film, as the adhesive layer 5 on the surface of the polyester film A according to the present invention. Through the laminated glass. By using the polyvinyl acetal resin film, the curved surface followability of the window film of the present invention is improved.

FIG. 4 is a schematic view of a laminated glass provided with the window film of the present invention.

The laminated glass 20 of the present invention may be a flat laminated glass, or a laminated glass using curved glass used for a windshield of a car. Since the window film of the present invention has improved thermoformability and curved surface followability, it is suitably used for laminated glass using the curved glass 8, in which case the polyester film A side is a concave portion of the curved shape. It is preferable to arrange on the side.

The laminated glass according to the present invention preferably has a visible light transmittance of 70% or more, particularly when used as a car window glass. The visible light transmittance can be measured by using, for example, a spectrophotometer (U-4000 type, manufactured by Hitachi, Ltd.), JIS R3106 (1998) “Test of transmittance, reflectance, and solar heat gain of plate glass” It can be measured according to “Method”.

The solar heat acquisition rate of the laminated glass of the present invention is preferably 60% or less, and more preferably 55% or less. If it is this range, the heat ray from the outside can be interrupted more effectively. In addition, the solar heat acquisition rate is measured using, for example, a spectrophotometer (manufactured by Hitachi, Ltd., U-4000 type) in the same manner as described above using JIS R3106 (1998) “Transmissivity / Reflectance / Solar Heat of Plate Glasses”. It can be determined according to “Acquisition rate test method”.

<Glass substrate>
A commercially available glass material can be used as the glass substrate used for the laminated glass of the present invention.

The type of glass is not particularly limited, but usually soda lime silica glass is preferably used. In this case, it may be a colorless transparent glass or a colored transparent glass.

Of the two glass substrates, the outdoor glass substrate close to the incident light is preferably colorless transparent glass. Moreover, it is preferable that the glass substrate of the indoor side far from the incident light side is a green-colored colored transparent glass or dark colored transparent glass. The green colored transparent glass preferably has ultraviolet absorption performance and infrared absorption performance. By using these, the solar radiation energy can be reflected as much as possible on the outdoor side, and the solar radiation transmittance of the laminated glass can be further reduced.

Although the green colored transparent glass is not particularly limited, for example, soda lime silica glass containing iron is preferable. For example, a soda lime silica glass containing 0.3 to 1 mass% of total iron in terms of Fe ₂ O _{3 in} a soda lime silica base glass. Furthermore, since absorption of light having a wavelength in the near-infrared region is dominated by divalent iron out of total iron, the mass of FeO (divalent iron) is calculated in terms of Fe ₂ O ₃ , It is preferably 20 to 40% by mass of iron.

In order to impart ultraviolet absorption performance, a method of adding cerium or the like to a soda lime silica base glass can be mentioned. Specifically, it is preferable to use soda lime silica glass having the following composition substantially. SiO ₂ : 65 to 75% by mass, Al ₂ O ₃ : 0.1 to 5% by mass, Na ₂ O + K ₂ O: 10 to 18% by mass, CaO: 5 to 15% by mass, MgO: 1 to 6% by mass, terms of Fe ₂ O ₃ were total iron 0.3 to 1 mass%, the total cerium CeO ₂ in terms and / or _TiO 2: 0.5 ~ 2% by weight.

Further, the dark transparent glass is not particularly limited, but, for example, soda lime silica glass containing iron at a high concentration is preferable.

When the laminated glass of the present invention is used for a window of a vehicle or the like, it is preferable that the thickness of both the indoor side glass base material and the outdoor side glass base material is 1.5 to 3.0 mm. In this case, the indoor side glass base material and the outdoor side glass base material can have the same thickness or different thicknesses. In using laminated glass for an automobile window, for example, both the indoor side glass base material and the outdoor side glass base material may have a thickness of 2.0 mm or a thickness of 2.1 mm. Moreover, when using laminated glass for an automobile window, for example, the total thickness of the laminated glass is reduced by setting the thickness of the indoor glass substrate to less than 2 mm and the thickness of the outdoor glass plate to 2 mm or more. In addition, it can resist external force from the outside of the vehicle. The indoor glass substrate and the outdoor glass substrate may be flat or curved. Since vehicles, particularly automobile windows, are often curved, the shape of the indoor side glass substrate and the outdoor side glass substrate is often curved. In this case, the polyester film A according to the present invention is preferably provided on the concave surface side of the outdoor glass substrate.

The method for producing the laminated glass of the present invention is not particularly limited. For example, after producing a window film by sandwiching both sides of the infrared reflective layer unit used in the present invention with the polyester film A and the polyester film B according to the present invention, After forming a polyvinyl acetal resin film as an adhesive layer on the polyester film, sandwiching the window film between two glass substrates, and then removing the excess portion protruding from the edge of the glass substrate as necessary , A method of heating at 100 to 150 ° C. for 10 to 60 minutes, and performing a combined degassing process by pressure degassing.

The surface of the adhesive layer may be provided with a release sheet before being used as a window film.

The release sheet only needs to be able to protect the tackiness of the pressure-sensitive adhesive. For example, an acrylic film or sheet, a polycarbonate film or sheet, a polyarylate film or sheet, a polyethylene naphthalate film or sheet, a polyethylene terephthalate film Or a plastic film or sheet such as a sheet or a fluorine film, or a resin film or sheet in which titanium oxide, silica, aluminum powder, copper powder or the like is kneaded, or a resin film or sheet in which a release agent is coated on the resin in which these are kneaded. Is used.

The thickness of the release sheet is not particularly limited, but it is usually preferably in the range of 12 to 250 μm.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "mass part" or "mass%" is represented.

Example 1
<Preparation of window film 1>
[Preparation of Polyester Film A]
After melting a polyethylene terephthalate chip having an intrinsic viscosity of 0.58 cm ³ / g measured at 25 ° C. at 280 ° C., it was extruded on a cooling drum from a T-die by a conventional method, and then using a roller heated to 90 ° C. in the longitudinal direction. After stretching by 3.3 times, the film was stretched by 3.6 times at 140 ° C. in the transverse direction in the tenter and then heat-set at 230 ° C. Subsequently, the width of the tenter was reduced, and a relaxation heat treatment with a relaxation rate defined by the following formula S of 3.6% was performed to obtain a polyester film A having a thermal shrinkage rate of 0.6% and a film thickness of 20 μm. It was.

<Relaxation rate>
Formula S Relaxation rate (%) = (AB) / A × 100
(In the formula, A: width of the film stretched (unit: m), B: width after shrinking (unit: m))
<Heat shrinkage>
A sample having a length of 100 mm and a width of 10 mm was used as a sample, and the vertical length was set to the following sample length.

Thermal shrinkage (%) = (L (23 ° C.) − L (150 ° C.)) / L (23 ° C.) × 100
L (23 ° C.): Sample length when left for 1 day in an environment of 23 ° C. and 55% RH L (150 ° C.): After standing for 30 minutes in an environment of 150 ° C., in an environment of 23 ° C. and 55% RH Sample length when left for 1 day at [Preparation of polyester film B]
A polyethylene terephthalate chip having an intrinsic viscosity of 0.64 cm ³ / g measured at 25 ° C. was melted at 280 ° C., and then extruded by a conventional method onto a cooling drum from a T die and then using a roller heated to 90 ° C. in the longitudinal direction. After stretching by 3.3 times, the film was stretched by 3.6 times at 140 ° C. in the tenter in the transverse direction. Subsequently, the film was heat-set at 180 ° C., heat treatment was not performed, and a polyester film B having a heat shrinkage rate of 5.5% and a film thickness of 20 μm was obtained.

[Near-infrared absorbing layer 1]
A butyral resin layer having a film thickness of 10 μm, in which a cesium-containing tungsten oxide (Cs _0.33 WO ₃ ) as a near-infrared absorber is mixed at 1.4 g / m ² on the polyester film A, is formed by a die coater. The window film 1 was obtained by coating and then thermocompression bonding with the polyester film B at a temperature of 80 ° C.

<Preparation of window films 2-8>
In the production of the window film 1, the heat fixing temperature, the relaxation heat treatment, and the film thickness of the polyester film A and the polyester film B were changed as shown in Table 1 to change the heat shrinkage rate in the same manner. 2 to 8 were produced.

<Preparation of window film 9>
In the production of the window film 1, a window film 9 was obtained in the same manner except that the near-infrared reflective layer 1 was produced and used instead of the near-infrared absorbing layer 1 by the following method.

A high refractive index layer containing a first water-soluble binder resin and first metal oxide particles as a near-infrared reflecting layer, and a low refraction containing a second water-soluble binder resin and second metal oxide particles The window film shown in FIG. 3 in which the rate layers were alternately laminated was produced as follows.

The undercoat layer coating solution 1 is applied to the polyester film A with an extrusion coater so as to be 15 ml / m ^2, and after passing through a 50 ° C. no-air zone (1 second), it is 30 ° C. at 30 ° C.
The substrate was dried for 2 seconds to obtain a support coated with an undercoat layer.

<Preparation of undercoat layer coating solution 1>
10g deionized gelatin
30 ml of pure water
Acetic acid 20g
The following crosslinking agent 0.2 mol / g gelatin The following nonionic fluorine-containing surfactant 0.2 g
The undercoat layer coating solution 1 was made up to 1000 ml with an organic solvent of methanol / acetone = 2/8.

<Preparation of deionized gelatin>
Ocein from which lime was removed by performing lime treatment, water washing and neutralization treatment was extracted in hot water at 55 to 60 ° C. to obtain ossein gelatin. The obtained ossein gelatin aqueous solution was subjected to both ion exchanges in a mixed bed of anion exchange resin (Diaion PA-31G) and cation exchange resin (Diaion PK-218).

[Formation of near-infrared reflective layer]
Using a slide hopper coating apparatus capable of multi-layer coating, 9 layers of low refractive index layers and 8 layers of high refractive index are formed on the polyester film A coated with the undercoat layer so that the lowermost layer is a low refractive index layer. A total of 17 layers were simultaneously applied alternately. During the coating process, the coating solution L1 for the low refractive index layer and the coating solution H1 for the high refractive index layer were kept warm at 45 ° C., and the polyester film A was heated to 45 ° C.

Immediately after application, 5 ° C. cold air was blown for 5 minutes to set. Thereafter, warm air of 80 ° C. was blown and dried to form a near-infrared reflective layer consisting of 17 layers. The film thickness after drying of the high refractive index layer and the low refractive index layer was 130 nm. Furthermore, the polyester film B was laminated | stacked on the near-infrared reflective layer, and the window film 9 which is a near-infrared reflective film was obtained.

[Preparation of coating liquid L1 for low refractive index layer]
First, 680 parts of a colloidal silica (manufactured by Nissan Chemical Industries, Ltd., Snowtex (registered trademark) OXS) aqueous solution as 10% by mass of second metal oxide particles, and 4.0% by mass of polyvinyl alcohol (Kuraray Co., Ltd.). (Manufactured by PVA-103: polymerization degree 300, saponification degree 98.5 mol%) 30 parts of an aqueous solution and 150 parts of a 3.0% by weight boric acid aqueous solution were mixed and dispersed. Pure water was added to prepare 1000 parts of colloidal silica dispersion L1 as a whole.

Next, the obtained colloidal silica dispersion L1 was heated to 45 ° C., and 4.0% by mass of polyvinyl alcohol (B) as a polyvinyl alcohol (manufactured by Nippon Vinyl Bipo-Poval Co., Ltd., JP-45: polymerization) 4500, saponification degree 86.5 to 89.5 mol%) and 760 parts of an aqueous solution were sequentially added with stirring. Thereafter, 40 parts of a 1% by weight betaine surfactant (manufactured by Kawaken Fine Chemical Co., Ltd., Sofazoline (registered trademark) LSB-R) aqueous solution was added to prepare a coating solution L1 for a low refractive index layer.

[Preparation of coating liquid H1 for high refractive index layer]
(Preparation of rutile titanium oxide as core of core / shell particles)
An aqueous suspension of titanium oxide was prepared such that the titanium oxide hydrate was suspended in water and the concentration when converted to TiO ₂ was 100 g / L. To 10 L (liter) of the suspension, 30 L of sodium hydroxide aqueous solution (concentration: 10 mol / L) was added with stirring, then heated to 90 ° C. and aged for 5 hours. Next, the mixture was neutralized with hydrochloric acid, washed with water after filtration.

In the above reaction (treatment), the raw material titanium oxide hydrate is obtained by thermal hydrolysis of an aqueous titanium sulfate solution according to a known method.

The base-treated titanium compound was suspended in pure water so that the concentration when converted to TiO ₂ was 20 g / L. Therein, it was added with stirring citric acid 0.4 mol% with respect to TiO ₂ weight. Then, when the temperature of the mixed sol solution reached 95 ° C., concentrated hydrochloric acid was added so that the hydrochloric acid concentration was 30 g / L. Further, the mixture was stirred for 3 hours while maintaining the liquid temperature at 95 ° C. to prepare a titanium oxide sol liquid.

As described above, when the pH and zeta potential of the obtained titanium oxide sol solution were measured, the pH was 1.4 and the zeta potential was +40 mV. Moreover, when the particle size was measured with a Zetasizer Nano manufactured by Malvern, the monodispersity was 16%.

Further, the titanium oxide sol solution was dried at 105 ° C. for 3 hours to obtain titanium oxide powder fine particles. The powder fine particles were subjected to X-ray diffraction measurement using JDX-3530 type manufactured by JEOL Datum Co., Ltd. and confirmed to be rutile titanium oxide fine particles. The volume average particle diameter of the fine particles was 10 nm.

Then, a 20.0 mass% titanium oxide sol aqueous dispersion containing rutile-type titanium oxide fine particles having a volume average particle diameter of 10 nm was added to 4 kg of pure water to obtain a sol solution serving as core particles.

(Preparation of core / shell particles by shell coating)
To 2 kg of pure water, 0.5 kg of 10.0 mass% titanium oxide sol aqueous dispersion was added and heated to 90 ° C. Next, 1.3 kg of an aqueous silicic acid solution prepared so that the concentration when converted to SiO ₂ is 2.0% by mass is gradually added, followed by heat treatment at 175 ° C. for 18 hours in an autoclave, and further concentrated. Thus, a sol solution (solid content concentration of 20% by mass) of core-shell particles (average particle size: 10 nm), which is a titanium oxide having a rutile structure as a core particle and SiO ₂ as a coating layer, was obtained.

(Preparation of coating liquid H1 for high refractive index layer)
28.9 parts of a sol solution containing core / shell particles as the first metal oxide particles having a solid content concentration of 20.0% by mass obtained above, and 10.5 parts of a 1.92% by mass citric acid aqueous solution. And 2.0 parts of an aqueous solution of 10% by weight polyvinyl alcohol (manufactured by Kuraray Co., Ltd., PVA-103: polymerization degree 300, saponification degree 98.5 mol%) and 9.0 parts of a 3% by weight aqueous boric acid solution. By mixing, a core-shell particle dispersion H1 was prepared.

Next, while stirring the core / shell dispersion H1, 16.3 parts of pure water and 5.0% by mass of polyvinyl alcohol (A) as polyvinyl alcohol (manufactured by Kuraray Co., Ltd., PVA-124: polymerization degree 2400, Ken 33.5 parts of an aqueous solution was added. Furthermore, 0.5 part of 1% by weight of a betaine surfactant (manufactured by Kawaken Fine Chemical Co., Ltd., Sofazoline (registered trademark) LSB-R) aqueous solution was added, and a high refractive index of 1000 parts as a whole using pure water A layer coating solution H1 was prepared.

<Preparation of window films 10 to 16>
In the production of the window film 9, the heat fixing temperature, relaxation heat treatment, and the film thickness of the polyester film A and the polyester film B were changed as shown in Table 1, and the heat shrinkage rate was changed in the same manner. 10 to 16 were produced.

≪Evaluation≫
Using the window films 1 to 16 produced above, both sides of the film are sandwiched between butyral sheets for laminated glass, and sandwiched between the front glass of an automobile so that the polyester film A side becomes the concave side of the laminated glass, and vacuum thermocompression bonding Thus, a laminated glass for automobiles was produced.

The laminated glass window film produced was evaluated according to the following criteria:
(Outdoor observation distortion)
5: When looking outside through the glass, it is not particularly distorted 4: When looking outside through the glass, the part with a strong curved surface is slightly distorted 3: When looking outside through the glass, the part with a strong curved surface is distorted 2: When looking outside through the glass The entire surface is slightly distorted 1: The entire image appears distorted (wrinkles)
3: No wrinkle on the entire glass surface 2; Wrinkle on the glass edge 1: Wrinkle on the entire glass surface Table 1 shows the structure of the window film and the evaluation results.

As shown in Table 1, the window films 1 to 6 and 9 to 14 of the present invention have excellent curved surface followability when used for laminated glass for automobiles, so that generation of wrinkles is suppressed and visibility through which the outside is viewed through the glass is shown. It turns out that it is excellent in. It can also be seen that the film thicknesses of the window films A and B are preferably B ≦ A.

Further, even if a near-infrared absorbing layer or a multilayered near-infrared reflecting layer is sandwiched between the polyester films A and B as the functional layer, the excellent effects of the present invention can be exhibited similarly.

Example 2
An adhesive layer having a thickness of 10 μm was provided on the polyester film A side of each of the window films 1 of the present invention and the window film 7 as a comparative example, and a release sheet was bonded thereon.

The

window films

1 and 7 were laminated on the outer surface of a commercially available car windshield with the release sheet facing outward, and thermoformed with a heat gun. Then, the release sheet was peeled off from the

window films

1 and 7, and was applied by 10 installers so that there was no wrinkle inside the windshield. As a result, while the time required for construction with the window film 1 of the present invention is an average of 5 minutes, the time required when using the window film 7 as a comparative example takes an average of 12 minutes. It turned out that the window film of a structure is easy to apply to the curved glass for motor vehicles.

Example 3
Copolyester containing terephthalic acid as the dicarboxylic acid component, ethylene glycol and cyclohexanedimethanol (7: 3) as the glycol component, naphthalenedicarboxylic acid and cyclohexanedicarboxylic acid (7: 3) as the dicarboxylic acid component, and ethylene glycol as the glycol component The copolyester contained was alternately extruded from a multilayer extrusion die to produce a near-infrared reflective film having a 200-layer structure and a center of the reflection wavelength at a wavelength of 1000 nm. 0.2 μm.

Adhesive layers are provided on both sides of the near-infrared reflective film, the polyester film A having the configuration of the window film 1 of the present invention is provided on one adhesive layer, and the polyester film B having the configuration of the window film 1 of the present invention is provided on the other adhesive layer. Further, a PVB adhesive layer having a thickness of 10 μm was provided on the polyester film A side, and a release sheet was bonded thereon.

In addition, adhesive layers are provided on both sides of the near-infrared reflective film, polyester A having a structure of window film 7 as a comparative example is applied to one adhesive layer, and polyester film B having a structure of window film 7 is applied to the other adhesive layer. Further, a PVB adhesive layer having a thickness of 10 μm was provided on the polyester film A side, and a release sheet was bonded thereon.

The obtained window film was evaluated in the same manner as in Example 2.

As a result, it was found that the construction time was about half when the window film 1 having the configuration of the present invention was used, compared with the case where the window film 7 having the configuration of the comparative example was used. Further, when the glass edge portion having a higher curvature is seen, there is no problem in the configuration of the present invention, but in the configuration of the comparative example, it is observed that the edge portion is wavy.

Since the window film of the present invention is excellent in thermoformability and curved surface shape followability, it is suitable for window films for automobiles and laminated glass using the same.

1 Window film 2 Polyester film A
3 Polyester film B
4 Adhesive Layer 5 Adhesive Layer 6 Near-Infrared Absorbing Layer 7 Near-Infrared Reflecting Layer 8 Laminated Glass 10 Window Film 20 Laminated Glass ML Near-Infrared Reflecting Layer Laminate U Optical Reflecting Unit T1-Tn, Ta1-Tan, Tb1-Tbn Refractive Index Layer

Claims

It is a window film to be bonded to glass having a curved shape at least in part,
The window film support includes a polyester film A having a thickness of 5 μm or more and a thermal contraction rate of 0.2 to 1%, and a thermal contraction rate of 2 to 10 and a thickness of 5 μm or more. %, A window film characterized by being a film laminated with a polyester film B within a range of%.
Thermal shrinkage (%) = {(L (23 ° C.) − L (150 ° C.)) / L (23 ° C.)} × 100
L (23 ° C.): Sample length when left for 1 day in an environment of 23 ° C. and 55% RH L (150 ° C.): After standing for 30 minutes in an environment of 150 ° C., in an environment of 23 ° C. and 55% RH Sample length when left for 1 day
2. The window film according to claim 1, wherein the ratio (A / B) of the film thickness ratio between the polyester film A and the polyester film B is in the range of 90/10 to 50/50.
The window film according to claim 1 or 2, further comprising a near-infrared absorbing layer between the polyester film A and the polyester film B.
The window film according to claim 1 or 2, further comprising a near-infrared reflective layer between the polyester film A and the polyester film B.
A laminated glass in which the window film according to any one of claims 1 to 4 is sandwiched by glass having a curved surface shape at least partially,
Laminated glass, wherein the polyester film A surface side of the window film is disposed at a position in contact with a concave portion of the curved glass.