JP2010095640A - Laminated film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated film having good coating appearance free from appearance defects such as uneven application and coating streaks when a binder compound and spherical particles are laminated on a thermoplastic resin film; and to provide a backlight and a solar cell. <P>SOLUTION: The laminated film has a coating layer satisfying the following three requirements: (1) the coating layer has a binder compound and a spherical particle on at least either surface of a substrate of a thermoplastic resin film; (2) the spherical particle has a coefficient of variation (CV) of ≤15%; and (3) the proportion of small-diameter particles existing in the spherical particles is ≥1%. A solar cell and a backlight is respectively constructed using the laminated film. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a laminated film used for electronic parts or displays. More specifically, the present invention relates to a laminated film such as an antireflection film or an antiglare film disposed on a display surface, a laminated film such as a reflective film or a light diffusion film incorporated in a backlight for a liquid crystal display, and a laminated film for a solar battery backsheet. It is.

  Films in which a coating layer containing spherical particles is laminated on a thermoplastic resin film is widely used. In the field of optical films, there are severe demands for appearance defects such as coating stripes and uneven coating. Often done.

  As a laminated film for a liquid crystal backlight, a light diffusion film (Patent Document 1) obtained by laminating a coating layer composed of a binder resin and spherical particles on a thermoplastic resin film, and a coating composed of an ultraviolet absorbing binder resin and spherical particles on a white film. A reflective film (Patent Document 2) in which layers are laminated is known.

Anti-glare-treated anti-reflection films have been proposed in which the appearance defects of the coating layer are reduced by optimizing the particle diameter and coating thickness of the coating layer composed of spherical particles and a binder resin (patent) Reference 3).
JP 2002-99220 A International Publication 2007/148544 JP 2007-249191 A

  In laminated films for liquid crystal backlights, appearance defects appear as luminance unevenness and are affected by the display quality of the display, so those with no appearance defects are required, and antiglare films etc. are used on the outermost surface of the display A higher level of appearance quality is required.

  When forming a coating layer from spherical particles and a binder compound, fluctuations in the dispersion state of the particles and partial fluctuations in the film thickness occur, and appearance defects such as coating unevenness and coating stripes often occur suddenly. .

  In the present invention, when laminating a binder compound and spherical particles on a thermoplastic resin film, the spherical particles are devised from a viewpoint different from the conventional one, thereby reducing the appearance defects such as coating unevenness and coating stripes. It is intended to provide films and backlights and solar cells.

The present invention employs the following means in order to solve such problems. That is, this invention is a laminated film characterized by having a coating layer that satisfies the following three requirements (1) to (3).
(1) It is a coating layer containing a binder compound and spherical particles on at least one surface of the base thermoplastic resin film.
(2) The coefficient of variation CV of the spherical particles is 15% or less.
(3) The small particle existence ratio of the spherical particles is 1% or more.

  In addition, the solar cell, the backlight and the display of the present invention are each configured by using the laminated film of the present invention.

  According to the present invention, by providing a laminated film in which specific spherical particles are provided on at least one surface of a base thermoplastic resin film, it is possible to provide a laminated film that can reduce appearance defects such as coating unevenness and coating stripes. Can do.

  The present invention provides a laminated film with less appearance defects such as coating unevenness and coating streaks by devising the above-mentioned problem, that is, the spherical particles constituting the coating layer laminated on the base thermoplastic resin film. This is an intensive study.

  As a result, when a coating layer containing spherical particles is applied to at least one surface of the base thermoplastic resin film, a specific one having a coefficient of variation CV of the spherical particles of less than 15% is used, and the particle size is relatively relatively small. As a result of using a specific condition for the abundance ratio of small spherical particles, it has been found that this problem can be solved.

The small particle diameter existence ratio according to the present invention indicates an existence ratio equal to or less than the particle diameter calculated from the volume average particle diameter of spherical particles × 0.4. For example, assuming that 1000 granular particles having a volume average particle diameter of 5 μm are contained, the small particle existence ratio is as follows when 100 spherical particles having a particle diameter of 2 μm or less are present: 10%.
The small particle existence ratio (%) = (Number of spherical particles of 2 μm or less: 100 / total number: 1000) × 100 = 10.

The small particle size existence ratio according to the present invention is preferably 1% or more. If the small particle existence ratio is less than 1%, the particle dispersibility after adjusting the paint may be lowered, and the coating appearance may be deteriorated. On the other hand, the upper limit is not particularly limited, but if it exceeds 10%, the luminance may decrease in the use of a laminated film for backlight.

  The spherical particles according to the present invention preferably have a coefficient of variation CV of 15% or less. Here, the coefficient of variation CV is a value obtained by dividing the standard deviation of the particle diameter by the volume average particle diameter. This variation coefficient CV is measured by, for example, a method described later. The variation coefficient CV is more preferably 10% or less. When the coefficient of variation CV is greater than 15%, the luminance may be lowered in the use of a laminated film for backlight.

  The volume average particle diameter of the spherical particles according to the present invention is not particularly limited, but is preferably 0.05 μm or more, more preferably 0.5 μm or more, further preferably 1 μm or more, particularly preferably. 3 μm or more. That is, when the volume average particle diameter is smaller than 0.05 μm, the luminance may decrease in the laminated film application for backlight, and in the antiglare film application, the light is smaller than the visible light wavelength region. Refraction may not occur and the antiglare effect may not be obtained. On the contrary, the upper limit of the volume average particle diameter is not particularly limited, but if it exceeds 100 μm, there is a possibility of causing problems such as image blur and cloudiness in the application used on the outermost surface of the display. The following control is preferable.

  Here, a method for collecting spherical particles, a method for measuring a volume average particle diameter, a coefficient of variation, and a small particle diameter existence ratio will be described.

(1) Collection of spherical particles The coated layer of the laminated film was scraped off with a sharp blade, the coated layer was collected from the laminated film, and the binder compound component was extracted using an organic solvent.

(2) Volume average particle diameter of spherical particles, coefficient of variation CV of spherical particles
For the measurement of the volume average particle diameter and the coefficient of variation CV of the spherical particles collected in (1) above, Coulter Multisizer III (manufactured by Beckman Coulter Co., Ltd.) is used as a particle size distribution measuring device utilizing the pore electrical resistance method. Was used.
That is, the number and volume of the particles were measured by measuring the electric resistance of the electrolyte corresponding to the volume of the particles when the particles pass through the pores. First, a very small amount of sample was dispersed in a thin surfactant aqueous solution, and then added to the designated electrolyte container in such an amount that the aperture (detection portion pore) passage rate was 10 to 20% while observing the display on the monitor. Thereafter, the particle size measurement was continued and automatically calculated until the number of passing particles reached 100,000, and the volume average particle size, the standard deviation of the volume average particle size, and the coefficient of variation CV were obtained. The value of the variation coefficient CV can be obtained by the following equation.
Coefficient of variation CV (%) = standard deviation of volume average particle diameter (μm) × 100 / volume average particle diameter (μm).

(3) Ratio of small-diameter particles present The spherical particles collected in (1) above were analyzed by image analysis using a multi-image analyzer (manufactured by Beckman Coulter), and 1000 spherical particles were analyzed. The number of spherical particles having a particle size equal to or less than the particle size calculated from the size × 0.4 was counted.
-Small particle diameter existence ratio (%) = {(volume average particle diameter × 0.4) μm or less spherical particles / 1000} × 100.

  The kind of the spherical particles according to the present invention is not particularly limited, and any of organic and inorganic types can be used.

  As such organic spherical particles, acrylic resin particles, silicone resin particles, nylon resin particles, polystyrene resin particles, polyethylene resin particles, polyamide resin particles such as benzoguanamine, urethane resin particles, and the like can be used. As the inorganic spherical particles, silicon oxide, aluminum hydroxide, aluminum oxide, zinc oxide, barium sulfide, magnesium silicate, or a mixture thereof can be used.

  However, it is preferable to use organic spherical particles from the viewpoints of dispersibility, coating properties, economy and the like with commonly used resin binder compounds.

  Among these organic spherical particles, an acrylic polymer, a polystyrene polymer, and a copolymer of an acrylic vinyl monomer and a styrene vinyl monomer are preferable. Particularly, two types of copolymers of an acrylic vinyl monomer and a styrene vinyl monomer are used. Since the refractive index can be changed by adjusting the copolymerization ratio, it can be suitably used in the present invention.

  In the present invention, since it is necessary to disperse the spherical particles in a solvent in the coating step of the coating layer, solvent resistance is required, and therefore the spherical particles preferably have a crosslinked structure. . In the case of not having such a crosslinked structure, spherical particles are eluted in the coating step, and there is a problem that it becomes impossible to provide a coating layer in which the particle shape and particle size are maintained.

  In order to form such a crosslinked structure, it is preferable to form a crosslinked structure using a vinyl compound having a plurality of functional groups in one molecule. In particular, in the present invention, vinyl having a plurality of functional groups in one molecule is used. As the compound, it is preferable to use a polyfunctional acrylic compound such as a bifunctional acrylic compound, a trifunctional acrylic compound, or a tetrafunctional or higher polymerizable acrylic compound.

  In the present invention, “Techpolymer” (R) (manufactured by Sekisui Plastics Co., Ltd.) can be used. If the coefficient of variation is 15% or less, methyl methacrylate and ethylene glycol disulfide such as the SSX series are used. Spherical particles made of a copolymer with methacrylate can be most preferably used.

  The content of the spherical particles in the coating layer according to the present invention is not particularly limited and cannot be uniquely limited because it depends on the particle type, dispersibility in the coating liquid, etc. Is preferably 3% by weight or more, more preferably 5% by weight or more, further preferably 10% by weight or more, and particularly preferably 15% by weight or more. That is, when the content is less than 3% by weight, there is no problem of appearance defects, but the luminance may be lowered in the use for a laminated film for a backlight. In addition, the upper limit of the content of the spherical particles is not particularly limited, but when it exceeds 300% by weight, the brightness decreases in the backlight application or the image blur or cloudiness in the application used on the outermost surface of the display. May cause problems.

  The thickness of the coating layer according to the present invention can be selected according to various uses and is not particularly limited, but is preferably 0.05 μm or more. When the thickness of the coating layer is less than 0.05 μm, problems such as dropping off of spherical particles may occur. The thickness of the coating layer is more preferably 3 μm or more, and further preferably 5 μm or more. Moreover, the upper limit of the thickness of the coating layer is not particularly limited, but if it exceeds 100 μm, problems such as drying unevenness and coating unevenness may occur, which is not economically preferable.

  The binder compound according to the present invention is not particularly limited, but a resin mainly composed of an organic component is preferable. For example, polyester resin, polyurethane resin, acrylic resin, methacrylic resin, polyamide resin, polyethylene resin, polypropylene resin, polyvinyl chloride resin. , Polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, fluorine resin, and the like. These resins may be used alone, or two or more copolymers or a mixture thereof may be used. Among these binder compounds, polyester resins, polyurethane resins, acrylic or methacrylic resins are preferably used from the viewpoints of heat resistance, particle dispersibility, coatability, and glossiness.

  When the laminated film of the present invention is used on the outermost surface of a display such as an antireflection film or an antiglare film, surface hardness and low reflectance are required. Therefore, as the binder compound, a photopolymerizable compound, Compounds such as fluorine compounds and silicon compounds are preferably used. For example, those disclosed in detail in paragraphs [0013] to [0068] of JP-A-2007-249191 can be used.

  When the laminated film of the present invention is used as a backlight or a solar battery, the base thermoplastic resin film is deteriorated by a lamp such as a cold cathode tube or sunlight, particularly ultraviolet rays (for example, optical deterioration such as yellowing). In addition, the ultraviolet light absorber and / or the light stability are not limited to the extent that the effect of the present invention is not inhibited in the binder resin forming the coating layer provided on the base thermoplastic resin film. It is preferable to contain an agent.

  Such ultraviolet absorbers and light stabilizers are roughly classified into inorganic and organic types, but the form to be contained is not particularly limited, and may be a method such as mixing with a resin forming such a coating layer. For example, when it is desired to prevent bleeding from the coating layer, a method such as copolymerization with a resin forming the coating layer may be used.

  As such inorganic ultraviolet absorbers, titanium oxide, zinc oxide, cerium oxide and the like are generally known, and at least one selected from the group consisting of titanium oxide, zinc oxide and cerium oxide is bleed out. It is preferably used from the viewpoints of economy, light resistance, ultraviolet absorption, and photocatalytic activity. Such ultraviolet absorbers may be used in combination of several kinds as required. Of these, titanium oxide or zinc oxide is most preferable from the viewpoints of economy, ultraviolet absorption, and photocatalytic activity.

  Examples of such organic ultraviolet absorbers include benzotriazole and benzophenone. In particular, benzotriazole can be suitably used because it contains nitrogen in the structure and thus has a function as a flame retardant, but is not particularly limited thereto. Since these ultraviolet absorbers only absorb ultraviolet rays and cannot capture organic radicals generated by ultraviolet irradiation, the base thermoplastic resin film may be deteriorated in a chain by these radicals. In order to capture these radicals and the like, a light stabilizer is preferably used in combination, and a hindered amine (HALS) compound is preferably used as the light stabilizer.

  Here, as the copolymerization monomer for fixing the organic ultraviolet absorber and / or the light stabilizer, vinyl monomers such as acrylic and styrene are highly versatile and economically preferable. Among these copolymerizable monomers, since the styrene vinyl monomer has an aromatic ring and is easily yellowed, copolymerization with an acrylic vinyl monomer is most preferably used in terms of light resistance.

  As the benzotriazole substituted with a reactive vinyl monomer, 2- (2′-hydroxy-5′-methacryloxyethylphenyl) -2H-benzotriazole (trade name: RUVA-93); Otsuka Chemical ( In addition, 4-methacryloyloxy-2,2,6,6-tetramethylpiperidine (“Adeka Stab LA-82”) can be used in which a hindered amine compound is substituted with a reactive vinyl monomer. "; Manufactured by ADEKA Co., Ltd.) can be used.

  In the present invention, the organic ultraviolet absorber includes a resin containing an organic ultraviolet absorber such as benzotriazole or benzophenone, a resin copolymerized with a benzotriazole-based or benzophenone-based reactive monomer, or a hindered amine. A resin containing and / or copolymerizing a light stabilizer such as a (HALS) -based reactive monomer can be used within a range that does not impair the effects of the present invention.

  These production methods and the like are disclosed in detail in paragraphs [0019] to [0039] of JP-A-2002-90515. Among them, HALS HYBRID (registered trademark) (manufactured by Nippon Shokubai Co., Ltd.) containing an acrylic monomer and UV absorber copolymer as an active ingredient can be used.

  In the present invention, when a binder compound having a hydroxyl group is used, a curing agent is often used in combination. As such a curing agent, a polyfunctional compound is preferably used in order to increase the coating film strength and increase the adhesion with the base thermoplastic resin film, and when used with an acrylic resin having a hydroxyl group as a binder compound. The polyisocyanate compound is most preferably used.

  Although it does not specifically limit as a polyisocyanate compound, From a viewpoint of light resistance and a weather resistance, an aliphatic type is preferable, and especially a hexamethylene type and an isophorone type are especially preferable. As a commercial product, "Desmodur" (registered trademark) N3200 (manufactured by Sumika Bayer Urethane Co., Ltd.), "Coronate" (registered trademark) HL (manufactured by Nippon Polyurethane Co., Ltd.), "Takenate" (Registered trademark) D120N (manufactured by Mitsui Takeda Chemical Co., Ltd.) and “Takenate” (registered trademark) D140N (manufactured by Mitsui Takeda Chemical Co., Ltd.) can be used as the isophorone type.

  Further, the hydroxyl value of the binder compound used in combination is preferably 20 or more, more preferably 30 or more, and particularly preferably 35 or more. When the hydroxyl value is less than 20, the coating strength or adhesion may be lowered. Although an upper limit is not specifically limited, When it becomes 80 or more, an external application external appearance may fall and it is unpreferable.

  Although it does not specifically limit as a base-material thermoplastic resin film of this invention, A cellulose acylate film, a polyethylene terephthalate film, a polyether sulfone film, a poly (meth) acrylic-type resin film, a polyurethane-type resin film, a polycarbonate Films, polysulfone films, polyether films, polyolefin films, polyvinyl chloride, etc. are used, and when used on the outermost surface of a display such as a polarizing plate, among the various films, the transparency is high and the optically complex. A cellulose acylate film having a small refraction and easy to produce is preferably used.

  Moreover, when using as a backlight use or a solar cell backsheet use, if a visible ray reflectance is high, the higher thermoplastic resin film is more preferable. For this purpose, a white thermoplastic resin film containing bubbles and / or incompatible particles therein is preferably used. Examples of these white thermoplastic resin films include, but are not limited to, polyolefins and polyesters such as porous unstretched or biaxially stretched polypropylene films and porous unstretched or stretched polyethylene terephthalate films. Polyester is preferably used from the viewpoint of moldability and productivity.

  Regarding these production methods and the like, paragraphs [0034] to [0057] of JP-A-8-262208, paragraphs [0007] to [0018] of JP-A-2002-90515, paragraph of JP-A-2002-138150 [0008] to [0034] and the like are disclosed in detail. Among these, the porous white biaxially stretched polyethylene terephthalate film disclosed in JP-A-2002-90515 is preferable as the base thermoplastic resin film according to the present invention for the reasons described above.

  The configuration of the base thermoplastic resin film according to the present invention may be appropriately selected depending on the intended use and required properties, and is not particularly limited, but is not limited to a single layer having at least one layer and / or A composite film having two or more layers is preferable, and it is preferable that at least one or more layers contain bubbles and / or inorganic particles.

  An example of a single layer configuration (= 1 layer) is, for example, a substrate thermoplastic resin film having only a single A layer, and a configuration in which bubbles are contained in the A layer. Among them, Lumirror (registered trademark) E20 (manufactured by Toray Industries, Inc.), SY64, SY74 (manufactured by SKC) and the like can be used.

  In addition, as an example of a two-layer structure, a base material thermoplastic resin film having a two-layer structure of A layer / B layer, in which a B layer is laminated on the A layer, and at least one of these A and B layers is included. The thing of the structure into which air bubbles were contained is mentioned. Among them, Tetoron (registered trademark) film UXZ1, UXSP (manufactured by Teijin DuPont Films Co., Ltd.) and the like can be used.

  Further, as an example of a three-layer structure, a base material thermoplastic resin film having a three-layer laminated structure in which three layers of A layer / B layer / A layer and A layer / B layer / C layer are laminated as described above. And a structure in which bubbles are contained in at least one of the layers. Among these, Lumirror (registered trademark) E6SL, E6SR, E6SQ, Tetoron (registered trademark) film UX (manufactured by Teijin DuPont Films, Inc.) and the like can be mentioned.

  The solvent to be dried contained in the paint according to the present invention means an organic compound having a property of dissolving a substance. Specifically, aromatic hydrocarbons such as toluene, xylene and styrene, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, alcohols such as methanol, isopropyl alcohol and isobutyl alcohol, chlorobenzene and orthodichloro Chlorinated aromatic hydrocarbons such as benzene, methane derivatives such as monochloromethane, chlorinated aliphatic hydrocarbons containing ethane derivatives such as monochloroethane, esters such as methyl acetate, ethyl acetate, butyl acetate, ethyl ether, 1 Ethers such as 1,4-dioxane, glycol ethers such as ethylene glycol monomethyl ether, alicyclic hydrocarbons such as cyclohexane, and aliphatic hydrocarbons such as normal hexane. Of these, aromatic hydrocarbon-based, ketone-based and ester-based organic solvents are preferable.

  Although it is not particularly limited as long as it can dissolve the binder resin, etc., it is preferable to avoid the use of toluene and xylene due to the recent VOC (volatile organic compound) regulations, etc. In this respect, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methyl acetate, ethyl acetate, and butyl acetate are preferable. In addition, it is preferable to use a mixture of two or more solvents having different boiling points in that the drying speed can be adjusted.

  In the present invention, the coating layer can be formed by any method when it is formed on at least one surface of the base thermoplastic resin film. For example, gravure coating, roll coating, spin coating, reverse coating, reverse kiss coating, bar coating, screen coating, blade coating, air knife coating, slit die coating, lip coating, dipping, etc. Application methods (inline coating) during the production of a base thermoplastic resin film using the various coating methods described above, or a method of applying (offline coating) on a base thermoplastic resin film after completion of crystal orientation can be mentioned. The reverse kiss coat coating method can be preferably used because there are few restrictions on the effective work width and it can flexibly cope with the product width.

  Various additives can be added to the white film and / or coating layer according to the present invention as long as the effects of the present invention are not impaired. Examples of additives include organic and / or inorganic fine particles, fluorescent brighteners, crosslinking agents, heat stabilizers, oxidation stabilizers, organic lubricants, antistatic agents, nucleating agents, dyes, fillers, and dispersants. In addition, a coupling agent or the like can be used.

  Since the laminated film of the present invention thus obtained can reduce appearance defects such as coating unevenness and coating stripes, an antireflection film or an antiglare film disposed on the display surface, a liquid crystal display backlight, etc. It can be conveniently used for a laminated film such as a reflective film or a light diffusing film incorporated in the film, or a laminated film for a solar battery back sheet. When these are used for a backlight or a solar cell, the laminated film of the present invention is installed with the coating layer facing the light source. In addition, paper substitutes, ie cards, labels, stickers, home delivery slips, video printer paper, inkjet, barcode printer paper, posters, maps, dust-free paper, display boards, white boards, thermal transfer, offset printing, telephones It can also be used as a base material for receiving sheets used for various printing records such as cards and IC cards.

  The measurement method and evaluation method are shown below.

(1) Collection of spherical particles The coated layer of the laminated film was scraped off with a sharp blade, the coated layer was collected from the laminated film, and the binder compound component was extracted using an organic solvent.

(2) Volume average particle diameter of spherical particles, coefficient of variation CV of spherical particles
For the measurement of the volume average particle diameter and the coefficient of variation CV of the spherical particles collected in (1), Coulter Multisizer III (manufactured by Beckman Coulter, Inc.) is used as a particle size distribution measuring device utilizing the pore electrical resistance method. Using. The number and volume of particles were measured by measuring the electrical resistance of the electrolyte corresponding to the volume of the particles as they pass through the pores. First, a small amount of sample is dispersed in a thin surfactant aqueous solution, and then added to the container of the specified electrolyte solution in such an amount that the aperture (detection portion pore) passage rate is 10 to 20% while viewing the monitor display. The particle size was continuously measured until the number of passing particles reached 100,000, and the particle size was automatically calculated to obtain the volume average particle size, the standard deviation of the volume average particle size, and the coefficient of variation CV. The value of the variation coefficient CV can be obtained by the following equation.
Coefficient of variation CV (%) = standard deviation of volume average particle diameter (μm) × 100 / volume average particle diameter (μm).

(3) Small-diameter particle abundance ratio The spherical particles collected in (1) were analyzed by image analysis using a multi-image analyzer (manufactured by Beckman Coulter), and 1000 spherical particles were analyzed. The number of spherical particles having a particle diameter equal to or less than that calculated from × 0.4 was counted.
Small particle existence ratio (%) = {(volume average particle diameter × 0.4) μm or less spherical particles / 1000} × 100.

(4) Particle dispersibility 100 g of the paint obtained after blending in Examples or Comparative Examples was collected, and the state after 1 minute was determined as follows. Class A was accepted, Class B and Class C were rejected. did.
Class A: No precipitation of particles is observed.
Class B: Only the supernatant part of the paint is separated into two layers, and some particle precipitation is observed.
Class C: The particles are completely precipitated at the bottom of the container.

(5) Appearance of coating With respect to the coating samples obtained in the examples or comparative examples, 10 externally selected judges were able to visually determine the appearance defects using fluorescent lamp reflected light. Judgment was carried out according to the following criteria, class A was accepted and class B was rejected.
Class A: All 10 persons could not detect coating stripes and coating unevenness.
Class B: Even one person could detect coating stripes and coating unevenness.

Example 1
Hals Hybrid (registered trademark) UV-G720T (acrylic copolymer, 40% concentration solution, manufactured by Nippon Shokubai Co., Ltd.): 10 kg, ethyl acetate: 18 kg, non-porous acrylic particles (Sekisui Plastics Industries ( TECHPOLYMER (registered trademark) TRX05S, volume average particle diameter 5.0 μm, coefficient of variation CV 9%, small particle existence ratio 1.4%, product lot GK6268): 1.5 kg, Desmodur (registered trademark) N3200 (Hexa) Methylene-based aliphatic polyisocyanate (manufactured by Sumika Bayer Urethane Co., Ltd., concentration 100%): 0.50 kg was sequentially added while stirring, and finally a coating solution (30 kg in total) was prepared by stirring for 30 minutes. Here, the particle dispersibility was confirmed.

One side of 300 μm white polyester film (“Lumirror” (registered trademark) E6SQ, 1100 mm × 900 m) was continuously applied by a reverse kiss method so that the coating amount after drying was 3.5 g / m ^2. Coating was carried out. In addition, drying conditions were carried out at 60 ° C./80° C./120° C./100° C. from the front chamber at a drying chamber of 3.5 m × 4 chambers, respectively, at a speed of 20 m / min. The work appearance was confirmed and judged.

(Example 2)
Spherical particles are non-porous acrylic particles (non-porous acrylic particles as spherical particles (TECHPOLYMER (registered trademark) TRX05S manufactured by Sekisui Plastics Co., Ltd.), volume average particle diameter 5.0 μm, coefficient of variation CV 9%, small particle existence ratio It was produced in the same manner as in Example 1 except that the product lot was HA6234), and the coating appearance of the obtained white film was confirmed and determined.

(Comparative Example 1)
Spherical particles are non-porous acrylic particles (non-porous acrylic particles as spherical particles (TECHPOLYMER (registered trademark) TRX05S manufactured by Sekisui Plastics Co., Ltd.), volume average particle diameter 5.0 μm, coefficient of variation CV 9%, small particle existence ratio It was produced in the same manner as in Example 1 except that 0.57% and the product lot HA6206) was used, and the coating appearance of the obtained white film was confirmed and determined.

(Comparative Example 2)
Spherical particles are non-porous acrylic particles (non-porous acrylic particles as spherical particles (TECHPOLYMER (registered trademark) TRX05S manufactured by Sekisui Plastics Co., Ltd.), volume average particle diameter 5.0 μm, coefficient of variation CV 9%, small particle existence ratio Except that it was 0.82%, product lot HA6208), it was produced in the same manner as in Example 1, and the coating appearance of the obtained white film was confirmed and determined.

(Comparative Example 3)
Spherical particles made of non-porous acrylic particles (TECHPOLYMER (registered trademark) MBX series, XX-09FP, refractive index 1.49, volume average particle diameter 5.0 μm, coefficient of variation CV 27%, small particles manufactured by Sekisui Plastics Co., Ltd.) Except that it was set to 5.2%), it was created in the same manner as in Example 1, and the coating appearance of the obtained white film was confirmed and determined.

  In any of Examples 1 and 2, the particle dispersibility was good, and the coating appearance of the obtained laminated film was also good. When the proportion of small-diameter particles was less than 1%, the particle dispersibility was abruptly deteriorated, and defects such as streaks and unevenness occurred frequently in the coating appearance (Comparative Examples 1 and 2). Moreover, even when the small particle existence ratio was 1% or more, when the coefficient of variation CV was larger than 15 (Comparative Example 3), the particle dispersibility was slightly worse and unevenness was observed in the coating appearance.

Claims (5)

A laminated film having a coating layer that satisfies the following three requirements (1) to (3).
(1) It is a coating layer containing a binder compound and spherical particles on at least one surface of the base thermoplastic resin film.
(2) The coefficient of variation CV of the spherical particles is 15% or less.
(3) The small particle existence ratio of the spherical particles is 1% or more.   The laminated film according to claim 1, wherein the base thermoplastic resin film is a polyester film.   The laminated film according to claim 1 or 2, wherein the substrate thermoplastic resin film is a white film.   The backlight comprised using the laminated | multilayer film in any one of Claims 1-3.   The solar cell comprised using the laminated | multilayer film in any one of Claims 1-3.