JP4832094B2 - Light diffusion film for optics - Google Patents

Description

  The present invention relates to an optical light diffusion film used for a liquid crystal display. More specifically, the present invention relates to an optical light diffusing film having a light diffusing layer excellent in high light diffusibility, high luminance, antistatic property, scratch resistance and adhesion to a substrate.

  As the full-scale ubiquitous era begins, the display device field, an interface that connects information and people, is a growing field. The main technologies of displays are roughly classified into CRT and flat panel display (FPD). FPD includes a light-receiving (non-light-emitting) liquid crystal display (LCD), a self-luminous plasma display (PDP), electroluminescence (EL), field emission display (FED), fluorescent display tube (VFD), and light emission. There is a diode (LED). In particular, liquid crystal displays (LCDs) are rapidly expanding as displays for IT-related devices such as liquid crystal TVs, liquid crystal PCs, notebook PCs, mobile phones, digital cameras, car navigation systems, and communication devices. In particular, notebook PCs, mobile phones, and mobile devices are strongly required to be lightweight and durable with respect to displays due to operability.

  Accordingly, backlight technology, which is one of the components constituting these devices, is required to have a high display capacity and high functionality that are excellent in size, weight, thickness, and impact resistance. The backlight technology requires an external light source because the liquid crystal itself does not emit light, and a backlight (4) is used for color display such as a liquid crystal TV as shown in FIG. The backlight is a light source installed on the back surface of the liquid crystal panel, and includes a fluorescent lamp (a hot cathode tube or a cold cathode tube), a light guide plate, a light diffusion film, and the like as the backlight (4).

  In a color display such as a liquid crystal TV or a liquid crystal PC, a cold cathode fluorescent tube having a diameter of several mm or less is used to light at a high voltage by an inverter. Many cold cathode fluorescent lamps are placed on the edge of a personal computer monitor. The reflector (3) has a role of concealing the frame on the back side and preventing scratches as the liquid crystal display becomes thinner. The light guide plate (2) is a member for evenly applying light to the display panel, and mainly an acrylic or polyolefin material is used. In the light guide plate, dots are formed on the plate in order to diffuse light entering from the light source. The light diffusion film (1) disposed on the surface of the light guide plate is a translucent film that scatters and diffuses light, and is mainly used to make the entire wide surface uniform brightness.

  In general, a light diffusion layer (film surface layer) is provided on the surface of the light diffusion film for the purpose of improving the light diffusibility and widening the viewing angle. As the film base material for the light diffusion film, polycarbonate resin, polyester resin and polyolefin resin are mainly used. A light diffusion layer is formed by applying a resin binder paint containing polymer particles such as spherical and / or spherical acrylic particles and styrene particles on the surface of the base material to form a light diffusion film. Further, a resin binder paint containing polymer fine particles such as spherical and / or spherical acrylic particles and styrene particles is applied to the back surface of the light diffusion film to form a protective layer on the back surface to form the light diffusion film. create. There is a problem that the back protective layer is easily damaged by contact with the light guide plate when constituting the backlight, and the damaged part may cause bright spots or dark spots, which may impair the quality of the display device. .

  A polyester film containing a silicon-based matting agent (see Patent Document 1) or the like is known as a method for irregularly reflecting light by fine irregularities on the surface. This method has a problem that it is difficult to achieve both a low parallel light transmittance and a high total light transmittance, and there is no performance effect as an optical light diffusion film.

  Further, a technique has been developed in which inorganic fine particles are contained in a resin binder in the surface light diffusion layer of the light diffusion film (see Patent Document 2). However, a large amount of inorganic fine particles are difficult to disperse in a resin binder, and there is no coating stability and there are aggregates of inorganic fine particles. Many gaps are generated during coating and drying, and light transmittance is lowered. Moreover, since the adhesiveness with a base film is bad, the function as a sufficient optical light-diffusion film cannot be fulfilled.

  In the case of color liquid crystal displays, a high-brightness optical light diffusion film has been developed. Transparent light particles such as acrylic beads are dispersed in a resin binder, and coated and dried on one or both sides of the base material for optical light diffusion. A method for producing a sheet has been proposed (see Patent Document 3).

JP-A-2-7002 Japanese Patent Laid-Open No. 7-5305 JP-A-6-67003

  However, the proposed technique does not satisfy all the functions described above. In addition, there is a demand for an optical light diffusion film, a surface light diffusion layer forming material, and a back surface protective layer forming material that have higher performance than before.

  Therefore, the object of the present invention is that the surface light diffusing layer has high light diffusibility, high brightness, antistatic property, light collecting property (originally the role of the prism sheet), scratch resistance and adhesion to the substrate. It is to provide an optical light diffusing film in which the back protective layer satisfies the required performance such as sticking property, prevention of scratches on the light guide plate, and adhesion to the substrate.

As a result of intensive studies to solve the above problems, the present inventors have achieved the above object by the following present invention. That is, the present invention includes a base film, an antistatic back protective layer (hereinafter sometimes simply referred to as “back protective layer”) provided on one surface of the base film, In an optical light diffusing film comprising an antistatic surface light diffusing layer (hereinafter sometimes simply referred to as “light diffusing layer”) provided on the surface, both the back protective layer and the light diffusing layer are polyurea colloidal particles (hereinafter “ In some cases, polyurethane gel fine particles (hereinafter sometimes referred to as “fine particles B1”) and / or thermoplastic polyurethane fine particles (hereinafter referred to as “fine particles B2”) covered with the fine particles A are coated with the fine particles A. The fine particles B1 and B2 may be referred to as “fine particles B”), the resin binder C, and the antistatic agent D. Providing an optical light diffusing film, characterized by being formed as a component (hereinafter simply referred to as "light diffusion film").

In the present invention, the fine particle B1 is a three-dimensionally crosslinked fine particle obtained from a polyisocyanate having at least one trifunctional or higher functional group and a compound having an active hydrogen group in the molecule, and the fine particle B2 is diisocyanate and bifunctional. Fine particles obtained from a compound having an active hydrogen group, and the surface of the fine particles B1 or B2 is covered with fine particles A precipitated from a polyurea colloid solution, and the particle diameter of these fine particles (B1 or B2) is The range is 0.5 to 100 μm; the fine particles A are composed of a solvated portion and a non-solvated portion with respect to the solvent, and the particle size of the non-solvated portion is 0.01 μm to 1 The fine particles A are fine particles obtained by the reaction of an oil-modified polyol, a polyisocyanate and a polyamine, It solvation portion is composed of hydrogen bonds of the urea bond; the light diffusing film preferably has a surface resistance of at 10 ¹³ Ω / cm ² or less.

  Further, the present invention provides a paint for forming a back protective layer or a paint for forming a light diffusing layer, wherein the fine particles B, the resin binder C, and the antistatic agent D are dissolved and dispersed in an organic solvent or an aqueous medium. provide.

  In the coating composition for forming a back protective layer of the present invention, among the total amount (100% by mass) of the fine particles B and the resin binder C, the fine particles B are 0.1 to 50% by mass, and the resin binder C is 99.99%. In the coating material for forming a surface light diffusing layer of the present invention described above, the total amount (100% by mass) of the fine particles B and the resin binder C is 80 to 20% by mass. The resin binder C is 20 to 80% by mass; in the paint of the present invention, the antistatic agent D is 25 to 0.1 with respect to the total amount (100% by mass) of the fine particles B and the resin binder C. It is preferred that the content is% by weight; and that at least one crosslinking agent is further contained.

  According to the present invention, it comprises a light diffusion layer / base film / back protective layer, the light diffusion layer and the back protective layer have excellent adhesion to the base film, and has high light diffusibility, high brightness, and antistatic properties. And a light diffusion film excellent in flexibility and the like.

  Since the light diffusing film of the present invention uses the fine particles B in the light diffusing layer, it has excellent performance such as optical characteristics, blocking resistance, processability, adhesion to a substrate, scratch prevention and flexibility. When the acrylic light guide plate and polyolefin light guide plate are used in the back protective layer, the light guide plate is prevented from being damaged by particles of the back protective layer of the light diffusion film, and is of high quality. It is useful for the light diffusion film of the backlight technology which comprises a display apparatus.

Next, the present invention will be described in more detail with reference to the best mode for carrying out the invention. The light diffusion film of the present invention comprises a base film, a back protective layer provided on one side of the base film, and a light diffusion layer provided on the other side of the base film. The protective layer and the light diffusing layer are characterized in that the fine particles B, the resin binder C, and the antistatic agent D, both of which are covered with the fine particles A, are formed as film forming components.

  Next, the back protective layer and the light diffusion layer of the light diffusion film will be described in detail. The back protective layer and the light diffusion layer are formed using fine particles B coated with the fine particles A, a resin binder C, and an antistatic agent D as a film forming component. These components B to D are dissolved and dispersed in a solvent or the like, or a solvent is used as a paint, and the paint is applied onto the base film as a back protective layer and a light diffusion layer forming paint and dried to protect the back. It is preferable to form a layer and a light diffusion layer. The paint in this case is a composition comprising fine particles B coated with the fine particles A, a resin binder C, and an antistatic agent D.

  Next, the fine particles B covered with the fine particles A used in the light diffusion film of the present invention will be described below. The fine particles B1 covered with the fine particles A are prepared by combining a polyisocyanate in which at least one of the compounds is trifunctional or more and a compound having an active hydrogen group in the molecule (hereinafter sometimes simply referred to as “polyurethane raw material”) with polyurea. It can be obtained by emulsion polymerization in an inert solvent in the presence of a colloidal solution (emulsifier). The surface of the fine particles B1 thus obtained is covered with the fine particles A precipitated from the polyurea colloid solution.

  On the other hand, the fine particles B2 coated with the fine particles A are not mixed with a diisocyanate and a compound having a bifunctional active hydrogen group (hereinafter sometimes simply referred to as “polyurethane raw material”) in the presence of a polyurea colloid solution (emulsifier). It can be obtained by emulsion polymerization in an active solvent. The surface of the fine particles B2 thus obtained is covered with the fine particles A precipitated from the polyurea colloid solution.

  Both the fine particles B1 and B2 are coated with the fine particles A precipitated from the polyurea colloid solution, and the particle diameter of the fine particles B is in the range of 0.5 to 100 μm. The fine particles A in the polyurea colloid solution are composed of a portion solvated with respect to the solvent and a non-solvated portion, and the particle diameter of the non-solvated portion is 0.01 μm to 1.0 μm. These are fine particles obtained by the reaction of an oil-modified polyol, polyisocyanate, and polyamine, and the non-solvated portion consists of urea-bonded hydrogen bonds.

  The fine particles B used in the light diffusing film of the present invention are mainly used in the case of an organic solvent-based resin binder in order to prevent swelling due to the solvent, and in the case of an aqueous resin binder, the fine particle B2 is used. Is preferably used.

  A preferable production method of the fine particles B described above is that a polyurea colloid solution is charged in a jacket-type synthesis kettle equipped with a stirrer or an emulsifier in an inert solvent, and a polyurethane raw material is added and emulsified therein, and these raw materials are reacted. Examples thereof include a method of synthesizing the fine particles B and a method of emulsifying the polyurethane raw material separately in an inert solvent in the presence of a polyurea colloid solution and reacting them.

  The synthesis temperature is not particularly limited, but a preferred temperature is 40 ° C to 120 ° C. Moreover, the polyurea colloid solution used at the time of synthesis can be used in an amount of 0.01 parts by mass or more, preferably 0.1 to 20 parts by mass, per 100 parts by mass of each polyurethane raw material. is there. If the amount used is less than 0.01 parts by mass, the emulsifiability of the polyurethane raw material is insufficient, and large agglomerates of fine particles B are generated during the synthesis process, making it difficult to obtain a desired fine particle B dispersion. On the other hand, when the amount used exceeds 20 parts by mass, there is no problem with the emulsifiability of the polyurethane raw material, and the dispersion of fine particles B can be produced, but it is an excessive amount as an emulsifier and has no particular advantage. The lower the concentration of the polyurethane raw material in the inert solvent, the easier it is to obtain fine particles having a smaller particle diameter. However, the preferable concentration of the polyurethane raw material is 20 to 70% by mass in terms of productivity.

  That is, the fine particles B used in the light diffusion film of the present invention have the following configuration. Examples of the compound having an active hydrogen group used for the synthesis of the fine particles B include short-chain diols such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, 1, Aliphatic glycols such as 6-hexamethylene glycol and neopentyl glycol and their alkylene oxide low molar adducts (number average molecular weight less than 500), 1,4-bishydroxymethylcyclohexane and 2-methyl-1,1-cyclohexanedimethanol Such as alicyclic glycol and its alkylene oxide low molar adduct (number average molecular weight of less than 500), aromatic glycol such as xylylene glycol and its alkylene oxide low molar adduct (less than number average molecular weight of 500), bisphenol A, Thio Scan phenol and sulfonic bisphenol bisphenol and alkylene oxide low molar adducts such as (number average molecular weight of less than 500), and compounds such as alkyl dialkanolamine such as alkyl diethanolamine of C1~C18 thereof.

  Examples of the polyhydric alcohol compound include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, tris- (2-hydroxyethyl) isocyanurate, 1,1,1-trimethylolethane, and 1,1, Examples thereof include 1-trimethylolpropane. These can be used alone or in combination of two or more.

Examples of the polymer polyol as the compound having an active hydrogen group include the following.
(1) Polyether polyols such as those obtained by polymerizing or copolymerizing alkylene oxides (ethylene oxide, propylene oxide, butylene oxide, etc.) and / or heterocyclic ethers (tetrahydrofuran, etc.) are specifically exemplified. Is a polymer polyol having a diol of poly (ethylene glycol), polypropylene glycol, polyethylene glycol-polytetramethylene glycol (block or random), polytetramethylene ether glycol and polyhexamethylene glycol, and / or a hydroxyl group having two or more functional groups. .

(2) Polyester polyols such as aliphatic dicarboxylic acids (eg succinic acid, adipic acid, sebacic acid, glutaric acid and azelaic acid) and / or aromatic dicarboxylic acids (eg isophthalic acid and terephthalic acid) And low molecular weight glycols (eg, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, 1,6-hexamethylene glycol, neopentyl glycol and 1,4-bishydroxymethyl And the like, specifically, polyethylene adipate diol, polybutylene adipate diol, polyhexamethylene adipate diol, polyneopentyl adipate diol, polyethylene / butylene acrylate. Petojioru, polyneopentyl / hexyl adipate diol, poly-3-methylpentane adipate diol, and polybutylene isophthalate diol of the diol and / or polyester polyols having such bifunctional or more hydroxyl group.

(3) Polylactone polyol, for example, a polylactone polyol having a diol such as polycaprolactone diol or polycaprolactone triol and / or poly-3-methylvalerolactone diol and / or a hydroxyl group having two or more functional groups.
(4) Polycarbonate diol, for example, a diol such as polyhexamethylene carbonate diol and / or a polycarbonate diol having a hydroxyl group having two or more functional groups.
(5) Polyolefin polyol, for example, polybutadiene glycol and polyisoprene glycol, or a polyolefin polyol having a diol such as a hydride thereof and / or a hydroxyl group having two or more functional groups.

(6) Diols such as hydrogenated dimer polyols and castor polyols and / or hydroxyl groups having two or more functional groups,
(7) Polymethacrylate diols such as α, ω-polymethyl methacrylate diol and α, ω-polybutylmethacrylate diol, and acrylic polyols having a bifunctional or higher functional hydroxyl group.

  Although the molecular weight of these polyols is not particularly limited, any of those that react with polyisocyanate can be used, and the number average molecular weight is usually preferably about 500 to 2,000. Moreover, these polyols can be used individually or in combination of 2 or more types. As the polyol, the fine particle B2 is preferably a polyol having two active hydrogen groups, while the fine particle B1 is particularly preferably a polyol having three or more active hydrogen groups.

  As the polyisocyanate used for the synthesis of the fine particles B, any of those conventionally used for producing polyurethane can be used and is not particularly limited. Preferred examples of the polyisocyanate include toluene-2,4-diisocyanate, 4-methoxy-1,3-phenylene diisocyanate, 4-isopropyl-1,3-phenylene diisocyanate, 4-chloro-1,3-phenylene diisocyanate, 4-Butoxy-1,3-phenylene diisocyanate, 2,4-diisocyanate diphenyl ether, 4,4′-methylenebis (phenylene isocyanate) (MDI), durylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate (XDI), 1,5 Aromatic diisocyanates such as naphthalene diisocyanate, benzidine diisocyanate, o-nitrobenzidine diisocyanate and 4,4′-diisocyanate dibenzyl, methylene di Socyanates, 1,4-tetramethylene diisocyanate, aliphatic diisocyanates such as 1,6-hexamethylene diisocyanate and 1,10-decamethylene diisocyanate, 1,4-cyclohexylene diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), It can be obtained by reacting 1,5-tetrahydronaphthalene diisocyanate, isophorone diisocyanate, alicyclic diisocyanates such as hydrogenated MDI and hydrogenated XDI, or these diisocyanates with low molecular weight polyols and polyamines so that the ends are isocyanates. Of course, polyurethane prepolymers can also be used.

  Moreover, those having a polyfunctional isocyanate group in which these compounds are isocyanurate bodies, burette bodies, adduct bodies, and polymeric bodies, and conventionally known ones can be used and are not particularly limited. For example, dimer of 2,4-toluylene diisocyanate, triphenylmethane triisocyanate, tris- (p-isocyanatephenyl) thiophosphite, polyfunctional aromatic isocyanate, polyfunctional aromatic aliphatic isocyanate, polyfunctional aliphatic Examples thereof include blocked polyisocyanates such as isocyanate, fatty acid-modified polyfunctional aliphatic isocyanate, and blocked polyfunctional aliphatic isocyanate, and polyisocyanate prepolymers.

  Of these, it is possible to use either aromatic or aliphatic, preferably modified products such as diphenylmethane diisocyanate and tolylene diisocyanate for aromatic systems, hexamethylene diisocyanate and isophorone diisocyanate for aliphatic systems, and fine particles In the production of B1, those containing two or more isocyanate groups in the molecule are preferred, so that the polyisocyanate multimer, adducts with other compounds, and low molecular weight polyols and polyamines become terminal isocyanates. A urethane prepolymer that has been reacted with is also preferably used. Moreover, in manufacture of microparticles | fine-particles B2, what contains two isocyanate groups in a molecule | numerator is preferable. These are exemplified below with structural formulas, but are not limited thereto.

  In the synthesis of the fine particles B, the type, amount and use ratio of the polyurethane raw material are determined depending on the purpose of use, but in the case of the fine particles B1 to be obtained, any component must be trifunctional or more. . For example, when the polyisocyanate is bifunctional, the compound having an active hydrogen group is trifunctional or more, and when the compound having an active hydrogen group is bifunctional, the polyisocyanate having trifunctional or more is It is necessary, and the number of functional groups used depends on the purpose of use. Of course, all the components may be trifunctional or more. The NCO / OH ratio is determined by the compound used and the performance required for the product, but is preferably in the range of 0.5 to 1.2. On the other hand, in the case of the fine particles B2, the type, usage amount and use ratio of the polyurethane raw material are determined in the same manner as in the case of the fine particles B1 depending on the purpose of use of the fine particles B2.

  The inert solvent used for the reaction of all the compounds and forming the continuous phase of the resulting dispersion of fine particles B is substantially non-solvent and free of active hydrogen with respect to the fine particles B to be produced. is there. Examples include pentane, hexane, heptane, octane, decane, petroleum ether, petroleum benzine, ligroin, petroleum spirit, cyclohexane, methylcyclohexane, toluene, xylene, ethylcyclohexane, dimethylcyclohexane, etc. having the structure of alicyclic hydrocarbons. Hydrocarbon, dimethylpolysiloxane, etc. may be used alone or as a mixture, and these inert solvents have a boiling point of 150 ° C. or lower from the viewpoint of productivity in the separation step of the fine particles B synthesized with the inert solvent. Is preferred. The reaction temperature in the synthesis of the fine particles B of the light diffusion film of the present invention may be low if a known catalyst is used, but a reaction temperature of 40 ° C. or higher is preferable from the work surface.

  The fine particles A in the polyurea colloid solution used as an emulsifier when synthesizing the fine particles B are composed of a solvated portion and a non-solvated portion with respect to the solvent, and the particle size of the non-solvated portion is preferred. Is a particle of 0.01 μm to 1.0 μm, and such a polyurea colloid solution is prepared by, for example, reacting an oil-modified polyol, a polyisocyanate (or a terminal NCO prepolymer comprising these compounds) and a polyamine in a non-aqueous solvent. It is obtained by.

  In this reaction, as the reaction proceeds, a hydrogen bond between urea bonds forms an insoluble urea domain in the solvent, and at the same time, the oil-modified polyol chain is solvated in the solvent, thereby The fine particles A are prevented from becoming enormous due to aggregation of urea domains, and a stable polyurea colloid solution can be easily obtained.

  Furthermore, the oil-modified polyol used has little crystallinity in a non-aqueous solvent, and the polymer chain mainly composed of the oil-modified polyol can move to some extent in the solvent even in the process of polymerization that occurs as the reaction proceeds. Therefore, separation of the non-soluble crystal part and the soluble non-crystalline part is easily performed, and a urea domain having the non-soluble crystal part due to the hydrogen bond between urea bonds as the center of the particle is formed, and a solvent is formed around it. The summed polymer chains are regularly oriented outwardly. This is a fundamentally different action from the surfactant in a known method for producing a colloidal solution obtained by polymerization in the conventional micelle.

  The method for producing the polyurea colloid solution will be described more specifically. First, an oil-modified polyol and polyisocyanate are first reacted in a non-aqueous solvent or without a solvent to synthesize a prepolymer having an NCO group. Next, this prepolymer is charged into a jacket-type synthesis kettle equipped with a stirrer, and the concentration is adjusted by adding a non-aqueous solvent so that the concentration becomes 5 to 70% by mass. While stirring this solution, a polyamine solution adjusted to a concentration of 1 to 20% by mass in advance is gradually added to react, and a polyurea colloid solution is produced by polyureaization reaction.

  In addition to the above method, the polyamine may be added by adding the prepolymer or a solution thereof to the polyamine solution. The temperature for the synthesis of the fine particles A is not particularly limited, but a preferable temperature is 20 to 120 ° C. The reaction concentration, temperature, stirrer form, stirring force, polyamine solution and prepolymer or the addition rate of the solution for the synthesis of fine particles A are not particularly limited, but the reaction between the polyamine and the isocyanate group of the prepolymer is fast. Therefore, it is preferable to control the reaction so that a rapid reaction is not performed.

  The oil-modified polyol used for the production of the polyurea colloid solution is a polyol having 2 or less functional groups, and a preferred molecular weight is 700 to 3,000, but is not limited thereto. Specific examples of the oil-modified polyol include, for example, various fats and oils by alcoholysis using a lower alcohol or glycol, a method of partially saponifying fats and oils, a method of esterifying a hydroxyl group-containing fatty acid with glycol, and the like. Those containing two or less hydroxyl groups are preferred, and examples of the hydroxyl group-containing fatty acid include ricinoleic acid, 12-hydroxystearic acid, castor oil fatty acid, hydrogenated castor oil fatty acid, and the like.

  The reaction between the oil-modified polyol and the polyisocyanate is performed under the condition of 1 <NCO / OH ≦ 2, and the molecular weight of the solvated prepolymer chain is controlled. The molecular weight of the prepolymer synthesized in this way is not particularly limited, but a preferred range is about 500 to 15,000. In the fine particles A used in the light diffusion film of the present invention, examples of the polyisocyanate used include all known polyisocyanates. Particularly preferred are aliphatic or alicyclic diisocyanates such as hexamethylene diisocyanate, water-added TDI, water-added MDI, isophorone diisocyanate, and hydrogenated XDI.

  As the non-aqueous solvent used for the production of the polyurea colloid solution, any non-aqueous solvent that does not have active hydrogen can be used as long as it dissolves the oil-and-fat-modified polyol, diisocyanate, and polyamine that are raw materials used. Particularly preferred are pentane, hexane, heptane, octane, decane, petroleum ether, petroleum benzine, ligroin, petroleum spirit, cyclohexane, methylcyclohexane, toluene, xylene, ethylcyclohexane and dimethylcyclohexane having an alicyclic hydrocarbon structure. A hydrocarbon, dimethylpolysiloxane or the like may be used alone or as a mixture. In addition, in the synthesis | combination of the said fine particle B used for the light-diffusion film of this invention, "dissolution" includes both melt | dissolution at normal temperature and high temperature.

  Examples of the polyamine used for the production of the polyurea colloid solution include a short-chain diamine, an aliphatic polyamine, an alicyclic polyamine, an aromatic polyamine, and hydrazine. Short chain diamines and aliphatic polyamines include, for example, methylene diamine, ethylene diamine, diaminopropane, diaminobutane, trimethylene diamine, trimethyl hexamethylene diamine, hexamethylene diamine, octamethylene diamine, polyoxypropylene diamine and polyoxypropylene triamine Aliphatic polyamines such as phenylenediamine, 3,3′-dichloro-4,4′-diaminodiphenylmethane, 4,4′-methylenebis (phenylamine), 4,4′-diaminodiphenyl ether and 4,4′-diaminodiphenyl Aromatic polyamines such as sulfone, cyclopentanediamine, cyclohexyldiamine, 4,4-diaminodicyclohexylmethane, 1,4-diaminocyclohexane, bis-amino Propyl piperazine, thiourea, methyl iminobispropylamine, and alicyclic diamines, such as norbornane diamine and isophorone diamine. Further, hydrazine such as hydrazine, carbohydrazide, adipic acid dihydrazide, sebacic acid dihydrazide and phthalic acid dihydrazide can be used. These can be used alone or in combination of two or more.

  The type, amount and ratio of the oil-modified polyol, polyisocyanate and polyamine used in the production of the polyurea colloid solution control the size and stability of the fine particles A in the solvent used. Determined by purpose. That is, the fine particles A in the polyurea colloid solution covering the fine particles B used in the light diffusing film of the present invention include a urea domain of a crystal part that is not solvated in the solvent, and a solvent extending in the solvent from the urea domain. It is formed by a summed polymer chain.

  The size of the urea domain of the fine particles A in the polyurea colloid solution and the size and form of the solvated polymer chain influence the properties of the polyurea colloid solution. Thus, the fine particles A formed of urea domains and solvated polymer chains are polyurea colloidal solutions that are stable in the solvent, and the particle size of the urea domains of the fine particles A in the solution is usually 0.00. The molecular weight of one solvated polymer chain is about 500 to 15,000, and the mass ratio of both is 0.5 for the urea domain (urea bond or polyamine) / polymer chain. A range of ˜30 is preferred.

  When the ratio of the urea bond is less than the above range, the non-solvating urea domain in the obtained fine particles A is hardly formed, the fine particles A are easily dissolved in the non-aqueous solvent, and a good polyurea colloid solution is not generated. On the other hand, when the ratio of the urea bond exceeds the above range, the non-solvating urea domain becomes large, the stability of the resulting polyurea colloid solution is lowered, and the fine particles A are easily aggregated.

  The form of the fine particles A used in the present invention in a solvent is assumed to be as shown in FIG. Regarding the control of the particle size of the fine particles A, it is possible to control both the size of the entire particle including the solvated polymer portion and the urea domain and the size of each of the solvated polymer portion and the urea domain. . The particle size of the fine particles A described above represents the urea domain portion.

  In order to produce a stably controlled polyurea colloidal solution, it is desirable that the solvated polymer part and the urea domain part are clearly phase-separated as shown in FIG. It is necessary to manufacture such that the chain and the urea domain of the crystal part are not mixed. For this purpose, a synthesis condition is required in which the polymer part solvated in the synthesis process and the urea domain part are easily separated.

  The synthesis of the polyurea colloidal solution gives better results as the concentration of both the prepolymer solution containing NCO groups and the polyamine solution is lower, and the addition rate of adding the other solution to one solution is lower, and the stirring is better. Propeller mixer agitation is sufficient. Further, when the concentration of the raw material solution is high or when the addition rate of the solution is high, it is preferable to synthesize while mixing with a high shearing force by using a homogenizer or the like. Although the reaction temperature is determined by the type of solvent used and the solubility of the urea domain in the solvent, the preferred temperature is 20 to 120 ° C. at which the synthesis can be easily controlled, but is not particularly limited to this temperature range. The formation of the urea domain may be a method of forming in the synthesis process, or a method of forming a synthesis at a high temperature in the cooling process.

  The important factors of the fine particles A in the polyurea colloid solution are the type and concentration of the surface groups, and further the dispersibility and the dispersed particle size in an inert solvent. That is, the action as an emulsifier of the polyurea colloid solution is a W / O, O / O type emulsifier, and the correlation between the hydrophilicity and hydrophobicity of the polyisocyanate and the compound having an active hydrogen group and the inert solvent. Act on. As a result of considering these conditions, the particle size of the fine particles B used in the light diffusion film of the present invention can be adjusted by adjusting the amount of the polyurea colloid solution added to the polyisocyanate and the compound having an active hydrogen group. In the above range, the larger the amount added, the smaller the particle size, and the smaller the amount, the larger the particle size.

  Fine particles B can be obtained by separating the inert solvent from the dispersion solution of fine particles B obtained from the raw materials as described above under normal pressure or reduced pressure. As a device used for particle formation, any known device such as a spray dryer, a vacuum dryer with a filtration device, a vacuum dryer with a stirring device, a shelf dryer, etc. can be used, and the preferred drying temperature is the vapor pressure of an inert solvent, fine particles B Although it is influenced by the softening temperature, particle size, etc., it is preferably 40-80 ° C. under reduced pressure.

  The particle diameter of the fine particles B thus produced is 0.5 μm to 100 μm and is a true sphere. The control of the particle size depends on the emulsification type (propeller type, vertical type, homogenizer, spiral band type, etc.) of the synthetic kettle and the stirring force when the composition of the fine particles B is the same. It is influenced by the concentration of the polyurethane raw material in the active solvent, the type of polyurea colloid solution and the amount added. The mechanical agitation and shearing force for emulsifying the polyurethane raw material are determined in the initial stage of emulsification, and the stronger this, the smaller the particle size of the fine particles B. Subsequent stirring and shear forces are not significantly affected. On the other hand, when the force is too strong, aggregation of the fine particles B is promoted, which is not preferable.

  Further, in the light diffusing film of the present invention, in the production of the fine particles B, at least a part or all of the raw material includes a plasticizer, a stabilizer, an antioxidant, an ultraviolet absorber, an antistatic agent, an abrasive, an extender, etc. It is also possible to obtain fine particles B suitable for various demands by mixing the various additives and synthesizing the fine particles B.

  These microparticles B are almost perfectly spherical microparticles as shown in the electron micrograph (magnification 500 times) in FIG. 2, and as shown in the imaginary diagram of FIG. Since the fine particles A deposited from the solution are attached or coated and the fine particles A are excellent in non-adhesiveness and heat resistance, the fine particles B can be obtained by simply removing the fine particles B from the dispersion solvent. In order to achieve this, there are various advantages such as no complicated and costly pulverization process and classification operation as in the prior art.

  Next, as the resin binder C used in the present invention, for example, acrylic resin, siloxane modified acrylic resin, polyurethane resin, siloxane modified polyurethane resin, fluorine modified urethane resin, polyester resin, polyvinyl alcohol, partially saponified polyvinyl alcohol, Acetoacetyl group-modified polyvinyl alcohol, acetal group-modified polyvinyl alcohol, butyral group-modified polyvinyl alcohol, silanol group-modified polyvinyl alcohol, ethylene-vinyl alcohol copolymer, ethylene-vinyl alcohol-vinyl acetate copolymer resin, epoxy resin, modified epoxy series Resin, phenoxy resin, modified phenoxy resin, phenoxy ether resin, phenoxy ester resin, fluorine resin, melamine resin, alkyd resin, phenol resin , Such as cellulose and chitosan it can be used.

Examples of the antistatic agent D used in the present invention include polyvinyl alcohol, cation-modified polyvinyl alcohol, alkali metal salt-containing ether polyurethane, a compound comprising an ion conductive polymer and a supporting electrolytic salt (supporting electrolytic salt is represented by the general formula M ⁺ X ⁻ M ⁺ is one selected from Li ⁺ , Na ⁺ and K ⁺ , and X ⁻ is ClO ₄ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , CF ₃ SO ₃ ⁻ , CF ₃ CO ₂ ⁻ , CF ₃ SO ₂ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , (CF ₃ SO ₂ ) ₃ C ⁻ , (C ₂ F ₅ SO ₂ ) ₃ C ^{− and the} like Inorganic or organic compounds), ionic conductive agents (imidazolium ions, pyridinium ions, ammonium ions, phosphonium ions, and other organic cation components, and NO ₃ ⁻ , CH ₃ CO ₂ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , CF _3. CO ₂ ^-, (CF ₃ S _{^{2) 2 N -, CF 3}} SO 2 - fluorinated ion compounds such as and _{^{CH 3 CO 2 -, NO 3}} - salts of inorganic or organic anions such as), polyamines, quaternary cationic salt-containing acrylic resin, special Organic conductive materials such as modified polyesters, special cationic resins, cellulose derivatives, polyacetylene, polyparaphenylene, polythiophene, polypyrrole, polyaniline and sulfonated polyaniline, metal oxides such as carbon black, tin oxide, zinc oxide and titanium oxide and Various metal alkoxides and conductive filler-containing polymers such as ITO powder can be used.

  The coating material for forming a back protective layer or the coating material for forming a surface light diffusion layer according to the present invention is characterized in that the fine particles B, the resin binder C, and the antistatic agent D are dissolved and dispersed in an organic solvent or an aqueous medium. When the coating material of the present invention is a paint for forming a back protective layer, the use ratio of the fine particles B is 0.1 to 50% by mass in the total amount (100% by mass) of the fine particles B and the resin binder C, preferably Is 0.5 to 10% by mass, while the proportion of the resin binder C used is 99.9 to 50% by mass, preferably 99.5 to 90% by mass. If the amount of the fine particles B used is too small, the flexibility of the back protective layer formed is insufficient. Moreover, when there is too much usage-amount of microparticles | fine-particles B, it is inadequate in the coating-film intensity | strength and cost surface of a back surface protective layer formed. Moreover, when there is too little usage-amount of the resin binder C, the adhesiveness with respect to the base material sheet of the back surface protective layer formed is inadequate. Moreover, when there is too much usage-amount of the resin binder C, the blocking resistance and protection performance of the back surface protective layer formed are inadequate.

  When the coating material of the present invention is a coating material for forming a surface light diffusion layer, the use ratio of the fine particles B is 80 to 20% by mass, preferably 60% of the total amount (100% by mass) of the fine particles B and the resin binder C. The use ratio of the resin binder C is 20 to 80% by mass, preferably 40 to 75% by mass. If the amount of the fine particles B used is too small, the optical properties such as light diffusibility of the formed light diffusion layer are insufficient. On the other hand, if the amount of the fine particles B used is too large, the haze reduction of the formed light diffusion layer, the poor dispersion of the fine particles of the coating material to be obtained, and the coating property are insufficient. On the other hand, if the amount of the resin binder C used is too small, the coating strength and adhesion of the light diffusion layer formed are insufficient. Moreover, when the usage-amount of the resin binder C is too much, optical characteristics, such as the light diffusibility of the light-diffusion layer formed, are inadequate.

Moreover, each said coating material of this invention contains the said antistatic agent D. FIG. The usage-amount of the antistatic agent D is 25-0.1 mass% with respect to the total amount (100 mass%) of the microparticles | fine-particles B and the resin binder C, Preferably it is 20-1 mass%. If the amount of the antistatic agent D used is too small, the antistatic property of each layer formed is insufficient, and if the amount of the antistatic agent D used is too large, it is uneconomical. It is insufficient in terms of bleeding out. A preferred amount of the antistatic agent is such that the surface resistance value of the back protective layer and the light diffusion layer of the finally obtained light diffusion film is 10 ¹³ Ω / cm ² or less.

  Furthermore, it is preferable that each paint of the present invention contains at least one crosslinking agent. These crosslinking agents include polyisocyanates, stabilized polyisocyanates, melamine crosslinking agents, amine crosslinking agents, aziridine crosslinking agents, silane crosslinking agents, organometallic compounds, carbodiimide crosslinking agents, oxazoline crosslinking agents, and the like. It is done. These cross-linking agents may be added in advance to the paint of the present invention, or may be added immediately before use of the paint. The use of a cross-linking agent is not essential but is preferably used. The amount of the crosslinking agent used is preferably in the range of 2 to 40 parts by mass per 100 parts by mass of the resin binder C. If the amount of the crosslinking agent used is too large, the flexibility of the formed layer is lowered, which is not preferable.

  Each paint of the present invention is obtained by dissolving and dispersing each of the above components in an organic solvent or an aqueous medium. Preferable organic solvents include, for example, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, butyl acetate, cyclohexanone, toluene, xylene, acetone, tetrahydrofuran, dimethylformamide, N-methyl-2-pyrrolidone, and the aqueous medium is water. And a mixed solvent of water and an organic solvent. When an aqueous medium is used as the coating medium, a water-soluble resin, a water-dispersible resin, an emulsion, or the like is used as the resin binder. Although the total solid content concentration of each paint is not particularly limited, it is usually preferably in the range of 20 to 50% by mass.

  The light diffusing film of the present invention forms a light diffusing layer from the light diffusing layer forming paint on one surface of the base film, and uses the back protective layer paint on the other surface of the base film to protect the back surface. Obtained by forming a layer. Examples of the base film used here include films of polyethylene terephthalate having a thickness of 30 to 300 μm, acrylic resin, polycarbonate, polyolefin, and the like. The method for forming each layer is performed by applying the coating material using various conventionally known coating apparatuses, drying, and aging treatment as necessary. The back protective layer thus formed preferably has a thickness of 2 to 15 μm, and the light diffusion layer preferably has a thickness of 15 to 60 μm. The light diffusing film of the present invention thus obtained is composed of a light diffusing layer / base film / back protective layer, and has excellent adhesion to the base film of the light diffusing layer and the back protective layer. Excellent brightness, antistatic properties and flexibility.

  Hereinafter, the present invention will be described more specifically with reference to synthesis examples, examples and comparative examples, but the present invention is not limited thereto. Moreover, in the following sentence, “part” indicates mass part, and “%” indicates mass%.

(Preparation of polyurea colloid solution)
[Synthesis Example 1]
100 parts of bifunctional oil-modified polyol (trade name URIC Y-202, manufactured by Ito Oil Co., Ltd.) having a hydroxyl value of 119.5 and 100 parts of n-octane were charged into a synthetic kettle equipped with a stirrer to dissolve the polyol. While stirring, the temperature was controlled at 50 ° C., 47.3 parts of isophorone diisocyanate prepared in advance so that NCO / OH = 2 was gradually added over 1 hour, and the reaction was continued for 3 hours under these conditions. A prepolymer was synthesized by reacting at 3 ° C. for 3 hours. Next, the concentration was adjusted to 50% with n-octane to obtain a prepolymer solution (PP-1) containing 3.0% of NCO groups. The molecular weight of this prepolymer is 1,383.

  40 parts of the above PP-1 and 60 parts of n-octane were charged into a synthesis kettle equipped with a stirrer and dissolved. While controlling the temperature at 70 ° C. while stirring, 24.3 parts of a 10% solution of n-octane of isophoronediamine prepared in advance was gradually added over 5 hours to complete the reaction, and (polyamine (urea bond part) ) / Prepolymer chain) × 100 = 12.15% polyurea colloid solution (solid content 18.0%) (C-1) was obtained. This solution was a blue opalescent stable solution.

[Synthesis Example 2]
100 parts of bifunctional oil-modified polyol (trade name URIC Y-202, manufactured by Ito Oil Co., Ltd.) having a hydroxyl value of 119.5 and 100 parts of n-octane were charged into a synthetic kettle equipped with a stirrer to dissolve the polyol. While stirring, the temperature was controlled at 50 ° C., 26.0 parts of isophorone diisocyanate prepared in advance so that NCO / OH = 1.1 was gradually added over 1 hour, and the reaction was continued for 3 hours under these conditions. Further, a prepolymer was synthesized by performing a reaction at 80 ° C. for 4 hours. Next, the concentration was adjusted to 50% with n-octane to obtain a prepolymer solution (PP-2) containing 0.36% of NCO groups. The molecular weight of this prepolymer is 11,834.

  20 parts of the above PP-2 and 80 parts of n-octane were charged into a synthetic kettle equipped with a stirrer to dissolve the prepolymer. While controlling the temperature at 70 ° C. while stirring, 14.4 parts of a 1% solution of n-octane of isophoronediamine prepared in advance was gradually added over 8 hours to complete the reaction, and (polyamine / prepolymer chain) ) × 100 = 1.44% polyurea colloid solution (solid content: 8.9%) (C-2) was obtained. This solution was a blue opalescent stable solution.

(Production of fine particles B1)
[Synthesis Example 3]
20 parts of polybutylene adipate diol having an average molecular weight of 1,000 is dissolved at 60 ° C., and isocyanurate polyisocyanate of hexamethylene diisocyanate represented by the following structural formula (product name: Duranate TPA-100, manufactured by Asahi Kasei Kogyo Co., Ltd.) NCO% = 23.1) 7.3 parts were added and mixed uniformly. This product was gradually added to a mixed solution of 5.0 parts of polyurea colloid solution (C-1) of Synthesis Example 1 and 25 parts of n-octane prepared in advance in a 1 liter stainless steel container, and emulsified with a homogenizer for 15 minutes. . This emulsion was a stable emulsion having an average dispersoid particle size of 5 μm and no separation.

  Next, this was charged into a reaction kettle equipped with a vertical stirrer, the temperature was raised to 80 ° C. while rotating at 400 rpm, the reaction for 6 hours was completed, and a dispersion of fine particles B1 was obtained. This solution was vacuum dried at 100 Torr to separate n-octane to obtain fine particles B1 (1). This was a spherical white powder having an average particle diameter of 5 μm.

[Synthesis Example 4]
In a 500 ml separable flask, 4 parts of polyurea colloid solution (C-2) and 150 parts of isooctane were charged and mixed. Next, 100 parts of a trifunctional polylactone polyol having an average molecular weight of 785, which was preheated to 50 ° C., was gradually added and emulsified while mixing this solution with a homomixer. Further, 68.3 parts of hexamethylene diisocyanate adduct polyisocyanate represented by the following structural formula (manufactured by Asahi Kasei Corporation, trade name Duranate 24A-100, NC 0% = 23.5) was gradually added.

  Next, while rotating the homomixer, the temperature was raised to 80 ° C., and after reaction for 3 hours, 0.005 part of dibutyltin dilaurate was added as a reaction catalyst, and the reaction was further performed for 4 hours to obtain a dispersion of fine particles B1. . Fine particles B1 (2) were obtained from this dispersion in the same manner as in Example 1. This was a spherical white powder having an average particle size of 15 μm.

(Production of fine particles B2)
[Synthesis Example 5]
In a 2 liter stainless steel container, 44 parts of polyurea colloid solution (C-1) and 356 parts of n-octane were charged and mixed, and kept at 40 ° C. To this, 250 parts of polybutylene adipate having an average molecular weight of 1,020, 30 parts of 1,4-butanediol and 144.7 parts of MDI were heated to 40 ° C. and uniformly mixed, and the mixture was emulsified with a homogenizer for 30 minutes. . This emulsion was a stable emulsion having an average dispersoid particle size of 5 μm and no separation of particles.

  Next, this was charged in a reaction kettle equipped with a vertical stirrer, the temperature was raised to 80 ° C. while rotating at 400 rpm, and the reaction for 3 hours was completed to obtain a polyurethane dispersion. This dispersion was transferred to a vacuum dryer, and the inert solvent was separated under reduced pressure of 50 mmHg or less to obtain powdery fine particles B2 (3). This was a spherical white powder having an average particle diameter of 5 μm.

[Synthesis Example 6]
In a 2 liter stainless steel container, 184 parts of polyurea colloid solution (C-2) and 216 parts of n-octane were charged and mixed, and kept at 40 ° C. To this, 250 parts of polybutylene adipate having an average molecular weight of 1,020, 30 parts of 1,4-butanediol and 144.5 parts of MDI were heated and uniformly mixed at 40 ° C. and emulsified with a homogenizer for 30 minutes. . This emulsion was a stable emulsion having an average dispersoid particle size of 16 μm and no separation of particles.

  Next, this was charged in a reaction kettle equipped with a vertical stirrer, the temperature was raised to 80 ° C. while rotating at 400 rpm, the reaction for 3 hours was completed, and a dispersion of fine particles B2 was obtained. This dispersion was transferred to a vacuum dryer, and the inert solvent was separated under reduced pressure of 50 mmHg or less to obtain powdered fine particles B2 (4). This was a spherical white powder having an average particle diameter of 16 μm.

(Manufacture of solution type polyurethane)
[Synthesis Example 7]
A 2 liter stainless steel container was charged with a predetermined amount of a solvent (dimethylformamide / methyl ethyl ketone = 1/1) having a non-volatile content of 30% and 0.005 part of dibutyltin dilaurate, and maintained at 40 ° C. To this, 250 parts of polybutylene adipate having an average molecular weight of 1,020, 30 parts of 1,4-butanediol and 144.5 parts of MDI were heated and uniformly mixed at 40 ° C., and the mixture was gradually stirred. When the heat of reaction disappeared, the temperature was raised to 80 ° C. and the reaction for 3 hours was finished to obtain a solution-type polyurethane resin (binder 5).

(Manufacture of water-based polyurethane)
[Synthesis Example 8]
In a 2-liter glass container, 11.1 parts of a hydrophilic group-containing compound component (dimethylolbutanoic acid), 150 parts of polycarbonate diol having a molecular weight of 1,000, and 30 parts of tetrahydrofuran were added and dissolved uniformly to adjust the solution concentration. Subsequently, 66.6 parts of IPDI was added and the reaction was carried out at 80 ° C. After confirming that the prescribed NCO% was obtained, the mixture was cooled to 50 ° C and ion-exchanged water to be 35% of the solid content and neutralized. 7.6 parts of triethylamine as an agent was added, the inside of the system was uniformly emulsified, and the reaction was continued for 8 hours while maintaining 60 ° C. Finally, the tetrahydrofuran in the system was recovered by vacuum degassing. An aqueous polyurethane resin (binder 6) was obtained.

[Examples 1-4, Comparative Examples 1-2]
The light diffusion layer coating material (solid content concentration 35%) and the back surface protection layer coating material (solid content concentration 20%) of Examples 1 to 4 and Comparative Examples 1 and 2 were prepared according to the compositions shown in Tables 1 and 2 (note that The solvent is not shown in the table).

Binder C1; acrylic polyol (trade name Thermolac EF-43, manufactured by Soken Chemicals, hydroxyl value = 25, nonvolatile content = 50%, ethyl acetate / IPA solution)
Binder C2; thermoplastic saturated copolymerized polyester resin (trade name Elitel UE3200, manufactured by Unitika Ltd., non-volatile content = 30% compound (MEK / TOL = 1/1 dissolved product, molecular weight = 16,000, Tg = 65) )
Binder C3; butyral resin (trade name S-REC BL-S, manufactured by Sekisui Chemical Co., Ltd., nonvolatile content = 30%, molecular weight = 23,000, Tg = 61, MEK dissolved product)
Binder C4; acrylic resin (trade name Aquabrid ASi-91, manufactured by Daicel Chemical Industries, non-volatile content = 30%, pH = 7.7)

Antistatic agent D1: Cationic type (quaternary ammonium salt) polyacrylate (trade name Julimer SP-50TF, manufactured by Nippon Pure Chemical Co., Ltd.)
Antistatic agent D2: a solution obtained by replacing the cationic type (quaternary ammonium salt) polyacrylate (trade name Elecondo PQ-50B, manufactured by Soken Chemical Co., Ltd.) with DMF as a solvent)
Antistatic agent D3: cationic polymer (trade name Texnol CP-81, a solution obtained by substituting NMP with a product of Nippon Emulsifier Co., Ltd.)
Antistatic agent D4; cationic acrylic polymer (trade name TK cation B, Takamatsu Yushi Co., Ltd., solvent-substituted NMP)

Cross-linking agent, PHDI; HDI biuret type (trade name Duranate 24A-100, manufactured by Asahi Kasei Chemicals Corporation)
PCD: Carbodilite V-02 (Nisshinbo Industries, Ltd.)
・ Aging condition: 40 ℃, 2 days

MEK; methyl ethyl ketone, DMF, dimethylformamide, IPA, isopropyl alcohol, TOL, toluene, NMP, 1-methyl-2-pyrrolidone

Binder C1; acrylic polyol (trade name Thermolac EF-43, manufactured by Soken Chemical Co., Ltd., hydroxyl value = 25, nonvolatile content = 50% (ethyl acetate / IPA solution))
Binder C2; thermoplastic saturated copolymer polyester resin (trade name Elitel UE3200, manufactured by Unitika Ltd., non-volatile content = 30% compound, molecular weight = 16,000, Tg = 65, MEK / TOL dissolved product)
Binder C3; butyral resin (trade name S-REC BL-S, manufactured by Sekisui Chemical Co., Ltd., nonvolatile content = 30%, molecular weight = 23,000, Tg = 61, MEK dissolved product)

Antistatic agent D5: Cationic type (quaternary ammonium salt) polyacrylate (trade name Julimer SP-50TF, manufactured by Nippon Pure Chemical Co., Ltd.) replaced with DMF as a solvent)

Cross-linking agent, PHDI; HDI biuret type, Duranate 24A-100 (manufactured by Asahi Kasei Chemicals Corporation)
・ Aging condition: 40 ℃, 2 days

・ Si: Trade name SIPERNAT310 (average particle size 5.5 μm, manufactured by Degussa)
MEK; methyl ethyl ketone, DMF, dimethylformamide, IPA, isopropyl alcohol, TOL, toluene

  The paint used for the optical light diffusion film of the present invention is a light diffusion layer and back protective layer forming paint prepared by dissolving or dispersing fine particles B, resin binder C, and antistatic agent D in an organic solvent or water. is there.

  Any known dispersion method may be used as a method for dissolving or dispersing the components B to D, and is not particularly limited. For example, a paint can be prepared by dispersing with a ball mill, basket mill, sand mill, roll mill, attritor, wet jet mill, dissolver, paint shaker, extrusion mixer, homogenizer, ultrasonic disperser, or the like. After preparing the light diffusing layer and the back surface protective layer forming paint, the light diffusing layer and back surface protective layer forming paint added with the crosslinking agent were also used. Any known coating method may be used as a method for applying the paint to the film, and it is not particularly limited. For example, a gravure coater, a spin coat, a reverse coater, a knife coater, a comma coater, an air knife coater and the like can be mentioned.

  Using each paint obtained in each Example and Comparative Example, the light diffusion layer was applied to the surface of a polyethylene terephthalate film (manufactured by Toray) with a thickness of 100 μm by a reverse coater so that the thickness after drying was 20 μm. After that, the solvent was dried in a dryer. Moreover, after apply | coating the back surface protective layer so that the thickness after drying might be set to 5 micrometers, the solvent was dried in the dryer. When the coatings using the crosslinking agents of Examples 1 to 4 and Comparative Examples 1 to 2 were used, the light diffusing layer and the back protective layer were formed by aging in an oven at 40 ° C. for 48 hours after application and drying. .

[Test example]
The performance of the light diffusing layer and the coating film of the back protective layer and the light diffusing film in the Examples and Comparative Examples obtained above was tested for the following items, and the results shown in Table 3 were obtained.

<Surface resistance value>
The antistatic property of the light diffusion film is measured using MCP-HT450 manufactured by Mitsubishi Chemical Corporation. The measurement conditions were a temperature of 23 ° C., a humidity of 65% RH, an applied voltage of 100 V, and 30 seconds. In order to exert the antistatic effect, 1 × 10 ¹³ Ω / cm ² or less is desirable.

<Transparency>
Using a direct reading haze computer HGM-2DP manufactured by Suga Test Instruments Co., Ltd., the haze value and total light transmittance of the light diffusion film were measured.
Haze value = measured value-base material haze value

<Glossiness>
The glossiness (60 ° incident light / 60 ° reflected light) of the light diffusion film was measured using a digital variable angle gloss meter manufactured by Suga Test Instruments Co., Ltd.

<Scratch resistance>
The coating film of the light diffusing layer of the light diffusing film was rubbed with Scotch Bright (manufactured by Sumitomo 3M Co., Ltd.) under a load of about 10 g / cm ² , and surface damage was visually confirmed.
○: 0 or more and less than 5 scratches that can be confirmed Δ: 5 or more and less than 10 scratches that can be confirmed ×: 10 or more scratches that can be confirmed

<Adhesion>
The adhesion between the coating film of the light diffusing layer of the light diffusing film and the substrate PET film was determined by a cross cut test (cellophane tape peeling cross-cut method).
◎: Unpeeled squares are 95% or more ○: Unpeeled squares are less than 95% 70% or more Δ: Unpeeled squares are less than 70% 40% or more X: Unpeeled squares are less than 40%

  As described above, according to the present invention, the light diffusion layer / base film / back protective layer is formed, and the light diffusion layer and the back protective layer have excellent adhesion to the base film, and have high light diffusibility and high brightness. A light diffusing film excellent in properties, antistatic properties and flexibility is provided.

Imaginary view of cross section of fine particles A in polyurea colloid solution used in the present invention Photograph of fine particles B used in the light diffusion film of the present invention Imaginary view of cross section of fine particle B used in light diffusion film of present invention The figure which shows the backlight structure of the light-diffusion film of this invention

Explanation of symbols

1: Solvated polymer chain 2: Unsolvated urea domain 3: Fine particle B
4: Fine particle A

Claims (10)

In an optical light diffusion film comprising a base film, an antistatic back protective layer provided on one surface of the base film, and an antistatic surface light diffusion layer provided on the other surface of the base film even the back passivation layer and the surface light diffusion layer is either a thermoplastic which is covered by a polyurethane gel particles are coated with polyurea colloidal particles (fine particles A) (fine particles B1) and / or polyurea colloidal particles (fine particles A) An optical light diffusing film comprising polyurethane fine particles (fine particles B2), a resin binder (C) and an antistatic agent (D) as film-forming components.   The fine particle B1 is a three-dimensionally crosslinked fine particle obtained from a polyisocyanate having at least one trifunctional or higher functionality and a compound having an active hydrogen group in the molecule, and the fine particle B2 has a diisocyanate and a bifunctional active hydrogen group. Fine particles obtained from a compound, and the surface of the fine particles B1 or B2 is covered with fine particles A precipitated from a polyurea colloid solution, and the particle diameter of these fine particles (B1 or B2) is 0.5 to 100 μm. The optical light diffusing film according to claim 1, wherein the optical light diffusing film is in the range of 1 above.   The optical system according to claim 1, wherein the fine particles A are composed of a solvated portion and a non-solvated portion with respect to the solvent, and the particle size of the non-solvated portion is 0.01 µm to 1.0 µm. Light diffusion film.   The optical light diffusing film according to claim 1, wherein the fine particles A are fine particles obtained by a reaction of an oil-and-fat-modified polyol, a polyisocyanate, and a polyamine, and the unsolvated portion is formed of a hydrogen bond of a urea bond. The optical light diffusion film according to claim 1, wherein the surface resistance value is 10 ¹³ Ω / cm ² or less. A paint for forming the antistatic back protective layer and the antistatic surface light diffusing layer constituting the optical light diffusing film according to any one of claims 1 to 5, comprising: polyurea colloidal particles ( Polyurethane gel fine particles ( fine particles B1 ) covered with fine particles A ) and / or thermoplastic polyurethane fine particles ( fine particles B2 ) covered with polyurea colloidal particles (fine particles A) , a resin binder (C) and an antistatic agent ( D) the paint you characterized by being dissolved and dispersed in an organic solvent or aqueous medium. It is a coating material for forming the antistatic back protective layer, and among the total amount (100% by mass) of the fine particles B1 and / or the fine particles B2 and the resin binder C, the fine particles B1 and / or the fine particles B2 are 0. a .1～50 wt%, paint of claim 6 resin binder C is 99.9 wt%. It is a coating material for forming the antistatic surface light diffusion layer, and among the total amount (100% by mass) of the fine particles B1 and / or the fine particles B2 and the resin binder C, the fine particles B1 and / or the fine particles B2 are 80%. a 20 wt%, paint of claim 6 resin binder C is 20 to 80 mass%.   The coating material according to claim 6, wherein the antistatic agent D is 25 to 0.1% by mass with respect to the total amount (100% by mass) of the fine particles B1 and / or the fine particles B2 and the resin binder C.   The paint according to claim 6, further comprising at least one crosslinking agent.