JP2013107995A - Coating composition and antireflection film using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating composition which can provide a coating film with a low refractive index excellent in abrasion resistance, antifouling property and appearance characteristic, and to provide an antireflection film using the coating composition.SOLUTION: The coating composition includes: a matrix-forming material which contains a hydrolyzable alkoxysilane represented by the formula (I) (in the formula, n=10 to 100); and silicone oil which comprises a polydimethylsiloxane represented by the formula (II) (in the formula, n=5 to 30 and A at both terminals is hydroxide group or -R'COOR) and has a viscosity of 10 to 100 mPa s.

Description

  The present invention relates to a coating composition for forming a coating film having a low refractive index and an antireflection film using the same.

Conventionally, MgF ₂ (refractive index 1.38), SiO ₂ (refractive index 1.47), etc. have been used as inorganic materials for low refractive index materials for the purpose of preventing reflection of image display panels such as displays. ing. In the organic material, a perfluoro resin (refractive index: 1.34 to 1.40) or the like is used. Usually, MgF ₂ is formed by a vapor phase method such as vacuum deposition or sputtering, SiO ₂ is formed by a vapor phase method similar to MgF ₂ or a liquid phase method by a sol-gel method, and perfluoro resin is formed by a liquid phase method. ing.

  In addition, as a technique capable of forming a coating film capable of obtaining an excellent antireflection performance with a low refractive index, a coating composition using a hydrolyzable organosilane such as tetramethoxysilane or tetraethoxysilane as a matrix forming material Has been proposed (see Patent Documents 1 and 2).

  In particular, a coating composition obtained by dispersing hollow silica particles having cavities surrounded by an outer shell in such a matrix-forming material is obtained by applying and drying the hollow silica particles in a porous matrix. A coating film having a structure in which particles are dispersed is formed. This coating composition has a particularly low refractive index and can form a transparent coating film, and is expected as a coating composition that is industrially practical for antireflection films and the like.

JP 2003-201443 A JP 2009-31769 A

  However, the coating composition using the hydrolyzable organosilane as the matrix forming material as described above has room for further improvement in the abrasion resistance, antifouling property and appearance characteristics of the coating film. A technique for further improvement has been desired.

  For example, in order to improve wear resistance and antifouling properties, it is conceivable to add silicone oil to the coating composition. However, the compatibility between the matrix-forming material and the silicone oil is low even when a commonly used silicone oil is combined with the conventional hydrolyzable organosilane matrix-forming material. For this reason, there is a problem that a defect occurs in the appearance of the coating film due to this.

  The present invention has been made in view of the circumstances as described above, and a coating composition capable of obtaining a coating film having a low refractive index excellent in abrasion resistance, antifouling property, and appearance characteristics, and It is an object to provide an antireflection film used.

（式中、ｎは１０〜１００の整数を示す。）で表される加水分解性アルコキシシランを含むマトリクス形成材料、および下記式（II）：

（式中、ｎは５〜３０の整数を示し、両末端のＡはそれぞれ独立に水酸基または−Ｒ’ＣＯＯＲ（Ｒは直鎖のアルキル基、Ｒ’は直鎖のアルキレン基を示す。）を示す。）で表されるポリジメチルシロキサンからなる粘度１０〜１００ｍＰａ・ｓのシリコーンオイルを含有することを特徴としている。 In order to solve the above problems, the coating composition of the present invention has the following formula (I):

(Wherein n represents an integer of 10 to 100) and a matrix-forming material containing a hydrolyzable alkoxysilane represented by the following formula (II):

(In the formula, n represents an integer of 5 to 30, and A at both ends each independently represents a hydroxyl group or —R′COOR (R represents a linear alkyl group, R ′ represents a linear alkylene group). It is characterized by containing a silicone oil having a viscosity of 10 to 100 mPa · s composed of polydimethylsiloxane represented by the following formula.

  This coating composition preferably contains hollow silica particles.

  The antireflection film of the present invention is characterized in that the coating composition is applied to a hard coat layer having a refractive index of 1.58 to 1.90 to form a low refractive index layer.

  According to the coating composition and antireflection film of the present invention, a coating film having a low refractive index excellent in abrasion resistance, antifouling property and appearance characteristics can be obtained.

  The present invention is described in detail below.

  The matrix-forming material blended in the coating composition of the present invention is blended with a hydrolyzable alkoxysilane represented by the above formula (I).

  In the formula (I), n represents an integer of 10 to 100, preferably an integer of 20 to 70. When n is within such a range, it is possible to suppress a decrease in coating film strength, and to suppress the occurrence of coating defects and appearance defects due to the occurrence of cracks in the coating film and an increase in viscosity.

  And the silicone oil with a viscosity of 10-100 mPa * s which consists of polydimethylsiloxane represented by the said Formula (II) is mix | blended with the coating composition of this invention. This viscosity is a value measured at 25 ° C. in accordance with JIS Z8803.

  The polydimethylsiloxane represented by the formula (II) has a linear siloxane structure in which both ends are blocked with a hydroxyl group or a higher fatty acid ester. The higher fatty acid ester is represented by -R'COOR, R represents a linear alkyl group, and R 'represents a linear alkylene group. R preferably has 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms. R 'preferably has 8 to 20 carbon atoms, more preferably 10 to 18 carbon atoms.

  In the formula (II), n represents an integer of 5 to 30, preferably 6 to 15. When n is within such a range, the slip property is exhibited and the solubility in the binder resin can be enhanced.

  The blending amount of the silicone oil is preferably 0.05 to 0.2% by mass with respect to the total amount of the matrix forming material and the hollow silica particles which are coating film components. When the blending amount of the silicone oil is within such a range, it is possible to sufficiently improve the wear resistance, antifouling property, and appearance characteristics, and to suppress an increase in haze and occurrence of repellency defects.

  Hollow silica particles can be blended in the coating composition of the present invention. The hollow silica particles are those in which a cavity is formed inside the outer shell.

  By blending the hollow silica particles with the coating composition of the present invention, the transparency of the coating film can be increased, and the antireflective performance can be improved with a low refractive index.

  As the hollow silica fine particles, for example, those having a cavity in the outer shell (shell) made of silica-based inorganic oxide can be used.

  Here, the silica-based inorganic oxide is (A) a single layer of silica, (B) a single layer of a composite oxide composed of silica and an inorganic oxide other than silica, and (C) the (A) layer ( B) The thing including the double layer with a layer is said.

  The outer shell may be porous with pores, or the pores may be closed and the cavity sealed with respect to the outside of the outer shell.

  The outer shell is preferably a plurality of silica-based coating layers composed of an inner first silica coating layer and an outer second silica coating layer. By providing the second silica coating layer on the outer side, the fine pores of the outer shell are closed, the outer shell is densified, and further, hollow silica particles in which the inner cavity is sealed can be obtained.

  The thickness of the outer shell is preferably 1 to 50 nm, and more preferably 5 to 20 nm. When the thickness of the outer shell is within such a range, the predetermined particle shape of the hollow silica particles can be maintained, and an increase in refractive index due to a decrease in the proportion of cavities in the hollow silica particles can be suppressed.

  The thickness of the outer shell is preferably in the range of 1/50 to 1/5 of the average particle diameter of the hollow silica particles. When the first silica coating layer and the second silica coating layer are provided as outer shells as described above, the total thickness of these layers may be in the range of 1 to 50 nm. In particular, in the case of a densified outer shell, the thickness of the second silica coating layer is preferably in the range of 20 to 40 nm.

  In addition, the solvent used when preparing the hollow silica particles and / or the gas that enters during drying may be present in the cavities of the hollow silica particles. Further, a precursor material for forming a cavity may remain in the cavity. This precursor material may remain slightly attached to the outer shell or may occupy the majority of the cavity.

  Here, the precursor substance is a porous substance that remains after a part of the constituent components of the core particle is removed from the core particle surrounded by the outer shell. For example, porous composite oxide particles made of silica and an inorganic oxide other than silica are used as the core particles.

Examples of inorganic oxides include Al ₂ O ₃ , B ₂ O ₃ , TiO ₂ , ZrO ₂ , SnO ₂ , Ce ₂ O ₃ , P ₂ O ₅ , Sb ₂ O ₃ , MoO ₃ , ZnO ₂ , WO _{3 and the} like. Can be used. These may be used alone or in combination of two or more. Examples of the combination of two or more inorganic oxides include TiO ₂ —Al ₂ O ₃ and TiO ₂ —ZrO ₂ .

  Note that the above-mentioned solvent or gas may be present in the pores of the porous material. If the removal amount of the component of the core particle at this time increases, the volume of the cavity increases and hollow silica particles having a low refractive index can be obtained. And the coating film by the composition for coating of this invention which mix | blended this hollow silica particle is transparent, is low refractive index, and is excellent in antireflection performance.

  The average particle diameter of the hollow silica particles is preferably 5 nm to 2 μm. In addition, an average particle diameter is a number average particle diameter by transmission electron microscope observation. When the average particle diameter of the hollow silica particles is within such a range, the hollow can be made to have a low refractive index, and the contribution of reduction in transparency and diffuse reflection (Anti-Glare) can be suppressed. .

  The hollow silica particles as described above can be produced, for example, by the method described in JP-A-2001-233611. In the present invention, other commercially available hollow silica particles can also be used.

  The blending amount of the hollow silica particles in the coating composition of the present invention is the mass ratio of the mass of the hollow silica particles to the matrix-forming material (the mass of the hollow silica particles) in consideration of the low refractive index and mechanical strength of the coating film. / Mass of the matrix forming material) is preferably 5/95 to 60/40.

  The coating composition of the present invention may contain a curing catalyst that crosslinks the matrix forming material.

  By blending a curing catalyst, when the coating composition is applied to a substrate to form a coating film and dried, the condensation reaction is promoted to increase the crosslinking density in the coating film, and the water resistance of the coating film is increased. And alkali resistance can be improved.

  In the coating composition of the present invention, various components can be blended as necessary within a range not impairing the effects of the present invention. Examples of such components include metal chelate compounds such as Zr chelate compounds and Ti chelate compounds, curing catalysts such as organic acids; water-dispersed colloidal silica, colloidal silica dispersed in a hydrophilic organic solvent such as alcohol, and the like. Silica particles that are not hollow; silane coupling agents; dyes; photosemiconductor fine particles; porous fillers of carbon and fluorine materials; metal fluoride fillers; conductive materials such as fibers and whiskers; leveling agents; Agents and the like.

  The coating composition of the present invention can be applied to a substrate to form a coating film, or it may be preferable that at least partial hydrolysis of the matrix-forming material may occur. It is preferable to blend a mixture of a solvent and a solvent.

  As such a solvent, for example, a hydrophilic organic solvent can be used. Examples of the hydrophilic organic solvent include lower aliphatic alcohols such as methanol, ethanol, isopropanol (IPA), n-butanol and isobutanol, ethylene glycol such as ethylene glycol, ethylene glycol monobutyl ether and ethylene glycol monoethyl ether acetate. Derivatives, diethylene glycol derivatives such as diethylene glycol and diethylene glycol monobutyl ether, diacetone alcohol and the like can be used. These may be used alone or in combination of two or more.

  Furthermore, together with these hydrophilic organic solvents, organic solvents such as toluene, xylene, hexane, heptane ethyl acetate, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, and methyl ethyl ketoxime can be used in combination.

  The coating composition of the present invention can be prepared by blending the above-described matrix-forming material, silicone oil, and, if necessary, the other components described above.

  And this coating composition is apply | coated to the surface of a base material, a coating film is formed, and a coating film of a low refractive index can be obtained by drying this coating film.

  When the coating film is formed in this way, a film having a larger area can be obtained more easily than the vapor phase method or the liquid phase method, and the film formation speed can be increased.

  The matrix-forming material can be used in the presence of water when water is added to the coating composition, during preparation of the coating composition, and / or during application to the substrate and drying of the coating film after preparation. Condensation to form a matrix. Such a matrix-forming material is applied to a substrate in the form of a paint to form a coating film, and then dried to form a porous coating film. This drying may be performed while heating.

  It is preferable to heat-treat the coating film formed on the surface of the substrate after drying. By this heat treatment, the mechanical strength of the coating film can be further improved. The heat treatment can be performed, for example, at 80 to 150 ° C. in an oxidizing atmosphere.

  Moreover, the film thickness of the coating film formed on the surface of the base material can be appropriately selected according to the use and the like, and is not particularly limited, but is, for example, 0.01 to 10.0 μm, preferably 0.01 to 0.00. 5 μm.

  According to the coating composition of the present invention, a coating film having a low refractive index can be easily formed. The refractive index of the coating film can be set to 1.10 to 1.40, for example.

  The method for applying the coating composition of the present invention to the surface of the substrate is not particularly limited, and examples thereof include brush coating, spray coating, dipping (dip coating), roll coating, gravure coating, micro gravure coating, and flow coating. , Curtain coating, knife coating, spin coating, table coating, sheet coating, single wafer coating, die coating, bar coating, reverse coating, cap coating, a method of applying in a pattern using an inkjet coater, and the like.

  Although it does not specifically limit as a base material which forms the coating film by the coating composition of this invention, For example, inorganic base materials, such as glass; Metal base material; Polycarbonate, polyethylene terephthalate, an acrylic resin, a fluororesin, a triacetyl cellulose Organic base materials such as polyimide resin can be used.

  Examples of the shape of the substrate include a plate shape and a film shape. Such a substrate may be made of a single material or may be laminated with different materials.

  It should be noted that when the coating composition of the present invention is applied to the surface of the substrate, the coating film is formed so that the coating film is uniformly formed or the adhesion between the coating film and the substrate is improved. It is preferable to pre-clean the surface. Examples of the pre-cleaning method include alkali cleaning, ammonium fluoride cleaning, plasma cleaning (including reduced pressure plasma and atmospheric pressure plasma), UV ozone cleaning, cerium oxide cleaning, and cleaning by corona discharge.

  The coating film formed by the coating composition of the present invention is suitable for an antireflection film. For example, when the refractive index of the substrate is 1.50 or less, a hard coat layer having a refractive index exceeding 1.50 is formed on the surface of the substrate, and the coating of the present invention is further formed on the surface of the hard coat layer. It is preferable to form a coating film of the composition for use as a low refractive index layer.

  The hard coat layer can be formed using various known high refractive index materials. By setting the refractive index of the hard coat layer to more than 1.50, particularly 1.58 to 1.90, the difference in refractive index from the coating film by the coating composition of the present invention increases, and the antireflection performance is excellent. An antireflection film can be obtained.

  Examples of the hard coat layer include an ultraviolet curable hard coat layer, an electron beam curable hard coat layer, and a thermosetting hard coat layer.

  Examples of the material of the hard coat layer include organic resin-based materials mainly composed of acrylic resin, urethane resin, and the like, and silicone resin-based materials. Further, by adding an antistatic agent, a dye or the like to the hard coat layer, an electromagnetic wave shielding function, an antistatic function, an infrared shielding function, and a color tone correction function can be provided.

  The antireflection film using the coating composition of the present invention includes, for example, a display (its outermost surface, optical filter, protective filter, etc.), various lenses, automobile mirrors and glasses (side mirrors, windshields, side glasses, rear glasses). Inner surface, etc.), other glass for vehicles, glass for building materials, screens and the like.

  Also, for special reflection prevention applications, photolithography is generally used for semiconductor circuit formation, color filter formation, transparent electrode pattern formation, etc., but ultraviolet laser is used as a light source for finer pattern formation. It is done. Since the reflected light of the ultraviolet laser has an adverse effect on pattern miniaturization, an antireflection film is required. The coating film obtained by the coating composition of the present invention can be applied to such applications.

  In addition, the coating composition of the present invention is applied to a transparent substrate such as glass to form a low refractive index coating film, and a transparent electrode layer typified by ITO is formed on this surface. Elements such as LED backlights for liquid crystal displays, organic EL (electroluminescence) backlights, and inorganic EL backlights that are excellent in light extraction efficiency can be manufactured.

  In addition, the coating composition of the present invention is applied to a transparent substrate such as glass to form a low refractive index coating film, thereby improving the transmittance or reflectance of light transmitted through the substrate. Applicable to. Such applications include, for example, touch panel substrates, backlight unit components (for example, light guide plates, cold cathode tubes, reflection sheets, etc.), liquid crystal brightness enhancement films (for example, prisms, transflective films, etc.), solar cell outermost surface members Illuminating lamps, reflective lenses, LCD color filters, various reflectors, amplified laser light sources, and the like.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

<Example 1>
[Preparation of coating composition]
As the matrix forming material, hydrolyzable alkoxysilane (“MS56S” manufactured by Mitsubishi Chemical Corporation, hydrolyzable alkoxysilane represented by the above formula (I), n = 50) was used.

  As a silicone oil, hydroxyl group-terminated polydimethylsiloxane (“A7813” manufactured by Momentive Co., Ltd., polydimethylsiloxane represented by the above formula (II), hydroxyl groups at both molecular ends, viscosity of 14.3 mPa · s (JIS Z8803, at 25 ° C.)) Using.

  As hollow silica particles, “CS60-IPA” manufactured by JGC Catalysts & Chemicals Co., Ltd., solvent dispersion sol (solid content 20%) was used.

  59.5 parts by mass of matrix forming material, 0.2 part by mass of silicone oil, and 40 parts by mass of hollow silica particles are blended, and then the solvent IPA (isopropyl alcohol) is used so that the total solid content becomes 3.0% by mass. The coating composition of the present invention was prepared by diluting with the following.

[Preparation of antireflection film]
Highly refracted on a polyester film (PET film, “A4300” manufactured by Toyobo Co., Ltd., thickness 100 μm) and an acrylic UV curable resin (“PET-HC301” manufactured by Dainichi Seika Kogyo Co., Ltd., solid content 60%) A hard coat layer (refractive index of 1.7) was formed by applying and curing a composition in which 30% by mass of titanium oxide (“760-T” manufactured by Teika Co., Ltd., solid content: 48%) was dispersed as a refractive index particle.

  On the surface of this hard coat layer, the coating composition prepared above was applied with a wire bar coater to form a coating film having a thickness of 100 nm, and further left to dry at 80 ° C. for 1 minute. Heat treatment was performed at 5 ° C. for 5 minutes in an oxygen atmosphere. In this way, an antireflection film was obtained.

<Example 2>
Except that 0.1 parts by mass of higher fatty acid ester-modified silicone oil (“TSF410” manufactured by Momentive Co., Ltd., polydimethylsiloxane represented by the above formula (II)) was used as the silicone oil, the same procedure as in Example 1 was performed. An antireflection film was obtained.

<Example 3>
An antireflection film was obtained in the same manner as in Example 1 except that the hydrolyzable alkoxysilane (n = 10) represented by the above formula (I) was used as the hydrolyzable alkoxysilane.

<Example 4>
An antireflection film was obtained in the same manner as in Example 1 except that the hydrolyzable alkoxysilane (n = 100) represented by the above formula (I) was used as the hydrolyzable alkoxysilane.

<Example 5>
As a silicone oil, 0.05 mass parts of hydroxyl group-terminated polydimethylsiloxane ("XC96-713" manufactured by Momentive Co., Ltd., polydimethylsiloxane represented by the above formula (II), hydroxyl groups at both terminals, viscosity 30 mPa · s) It was. Otherwise, an antireflection film was obtained in the same manner as in Example 1.

<Example 6>
As the silicone oil, hydroxyl-terminated polydimethylsiloxane (“YF3800” manufactured by Momentive Co., Ltd., polydimethylsiloxane represented by the above formula (II), molecular both ends —OH group, viscosity 80 mPa · s) was used. Otherwise, an antireflection film was obtained in the same manner as in Example 1.

<Example 7>
An antireflection film was obtained in the same manner as in Example 1 except that the hollow silica particles were not blended.

<Comparative Example 1>
An antireflection film was obtained in the same manner as in Example 1 except that no silicone oil was added.

<Comparative example 2>
An antireflection film was obtained in the same manner as in Example 1 except that 0.2 parts by mass of polyether-modified silicone oil (“BYK333” manufactured by Big Chemie Japan Co., Ltd.) was used as the silicone oil.

<Comparative Example 3>
An antireflection film was obtained in the same manner as in Example 1 except that 0.2 parts by mass of a hydroxyl group-terminated silicone oil (A is a hydroxyl group, n = 4 in the above formula (II)) was used as the silicone oil.

<Comparative example 4>
An antireflection film was obtained in the same manner as in Example 1 except that the hydrolyzable alkoxysilane (n = 140) represented by the above formula (I) was used.

  The following evaluation was performed about the antireflection film of an Example and a comparative example.

1. optical properties
[Total light transmittance]
It measured using the haze meter (Nippon Denshoku Industries Co., Ltd. "NDH2000").
[Minimum reflectance]
Using a spectrophotometer (“U-4100” manufactured by Hitachi, Ltd.), the reflectance at a wavelength of 4000 nm to 800 nm at an incident angle of 5 ° was measured.
[Haze]
It measured using the haze meter (Nippon Denshoku Industries Co., Ltd. "NDH2000").
[Refractive index of coating film]
Using a spectrophotometer ("U-4100" manufactured by Hitachi, Ltd.), the reflectance at a wavelength of 400 nm to 800 nm at an incident angle of 5 ° was measured, and then fitted with an optical simulation to derive the refractive index. .

2. Abrasion resistance The surface of the antireflection film was rubbed 10 times with steel wool # 0000 at 250 g / cm ² , and the presence or absence of scratches was visually evaluated according to the following criteria.
A: No scratch is generated.
B: Scratches are slightly generated.
C: Scratches occur.

3. Antifouling property The oil-based pen attached to the surface of the antireflection film was wiped off with a cellulose nonwoven fabric (“BEMCOT-S2” manufactured by Asahi Kasei Fibers Co., Ltd.), and the ease of removal was visually evaluated according to the following criteria.
○: The oil pen can be completely wiped off.
(Triangle | delta): The wiping trace of an oil-based pen remains.
X: The oil-based pen cannot be wiped off.

4). Appearance characteristics The antireflection film was visually observed in an area of 500 mm × 500 mm using a three-wavelength fluorescent lamp, and the number of light spots (spot-like defects that looked brighter than the normal part) was inspected.
○: Number of light spots is 1/500 mm ² or less Δ: Number of light spots is 2 to 9/500 mm ²
×: The number of light spots is 10 / mm ² or more

  The evaluation results are shown in Table 1.

  From Table 1, the Example which mix | blended the silicone oil of the viscosity of 10-100 mPa * s which consists of a matrix formation material containing the hydrolysable alkoxysilane represented by Formula (I), and the polydimethylsiloxane represented by Formula (II) The coating compositions 1 to 7 satisfied all of the optical properties, abrasion resistance, antifouling properties, and appearance properties as compared with Comparative Examples 1 to 4.

  In particular, by incorporating hollow silica particles, an antireflection film having a low refractive index and high transparency and further satisfying all of optical characteristics, abrasion resistance, antifouling properties and appearance characteristics could be obtained.

  In the evaluation of Table 1, when the abrasion resistance was C, the antifouling property was x, and the appearance characteristic was x, it was evaluated as not having the effect of the present invention. Further, when the wear resistance was B or less, the antifouling property was Δ or less, and two or more appearance characteristics were Δ or less, it was similarly evaluated that the effect of the present invention was not exhibited.

Claims (3)

Formula (I) below

(Wherein n represents an integer of 10 to 100) and a matrix-forming material containing a hydrolyzable alkoxysilane represented by the following formula (II):

(In the formula, n represents an integer of 5 to 30, and A at both ends each independently represents a hydroxyl group or —R′COOR (R represents a linear alkyl group, R ′ represents a linear alkylene group). A coating composition comprising a silicone oil having a viscosity of 10 to 100 mPa · s and comprising polydimethylsiloxane represented by the formula:   The coating composition according to claim 1, comprising hollow silica particles.   An antireflection film, wherein the coating composition according to claim 1 or 2 is applied to a hard coat layer having a refractive index of 1.58 to 1.90 to form a low refractive index layer.