JP2013007929A - Deposition coating liquid and coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a deposition coating liquid capable of depositing a dense coating film and a dense coating film deposited using the deposition coating liquid.SOLUTION: A deposition coating liquid contains: a binder containing a crosslinked siloxane polymer and a chain siloxane oligomer; and silica-based microparticles dispersed in the binder. The chain siloxane oligomer is grafted on the surface of the silica-based microparticle. An absolute value of zeta potential of the silica-based microparticle with the chain siloxane oligomer grafted is 25 millivolt or more at a pH of 5-7.

Description

  The present invention relates to a coating solution for film formation and a coating film.

For example, a technique for forming an organic antireflection film on the surface of a plastic lens such as an eyeglass lens is widely known. As a coating solution for forming an organic antireflection film, for example, a coating solution described in Patent Document 1 is known.
The coating liquid described in Patent Document 1 is manufactured as follows. First, an organosilicon compound having a fluorine atom is diluted with an organic solvent, and further an organosilicon compound having an epoxy group is added thereto. Then, if necessary, hydrolytic condensation polymerization is performed by adding water or dilute hydrochloric acid, acetic acid or the like. Next, a dispersion liquid in which silica-based fine particles having an average particle diameter of 1 to 150 nm are colloidally dispersed in an organic solvent is added. Thereafter, if necessary, a curing catalyst, a photopolymerization initiator, an acid generator, a surfactant, an ultraviolet absorber, an antioxidant and the like are added and sufficiently stirred. The coating liquid is manufactured as described above.
However, the present inventors have observed and tested an antireflection film formed using this coating solution, and found that silica-based fine particles are aggregated in the antireflection film. When such agglomeration of silica-based fine particles occurs, it is difficult to form a dense coating film, and there is a problem that water resistance, chemical resistance, heat resistance, and scratch resistance are lowered.

JP 2007-102096 A

  An object of the present invention is to provide a coating solution for film formation capable of forming a dense coating film and a dense coating film formed using the coating solution for film formation.

Such an object is achieved by the present invention described below.
The film-forming coating solution of the present invention comprises a binder having a cross-linked siloxane polymer and a chain siloxane oligomer,
Having silica-based fine particles dispersed in the binder,
The chain siloxane oligomer is grafted on the surface of the silica-based fine particles,
The absolute value of zeta potential of the silica-based fine particles grafted with the chain siloxane oligomer is 25 millivolts or more at pH 5-7.
Thereby, aggregation of the silica-based fine particles can be effectively prevented, and a film-forming coating solution capable of forming a dense coating film can be provided.

In the coating solution for film formation of the present invention, the silica-based fine particles preferably have an average particle size of 55 nm or less.
Thereby, the formed coating film becomes denser.
In the film-forming coating solution of the present invention, the content of the crosslinkable siloxane polymer in the binder is preferably 60 to 80 wt%.
Thereby, the formed coating film becomes denser.

In the film-forming coating solution of the present invention, the binder preferably further contains a linear siloxane polymer.
Thereby, the formed coating film becomes denser.
In the film-forming coating solution of the present invention, the content of the linear siloxane polymer in the binder is preferably 20 to 30 wt%.
Thereby, the formed coating film becomes denser.

In the film-forming coating solution of the present invention, it is preferable that the binder further contains a cyclic siloxane oligomer.
Thereby, the film-forming coating solution is stabilized.
In the film-forming coating solution of the present invention, the content of the cyclic siloxane oligomer in the binder is preferably 1 to 15 wt%.
Thereby, the fall of the intensity | strength of the formed coating film can be suppressed, aiming at stabilization of the coating liquid for film-forming.

In the coating solution for film formation of the present invention, the silica-based fine particles are preferably hollow silica particles.
Thereby, a coating film having a lower refractive index can be formed.
The film-forming coating liquid of the present invention is preferably a coating liquid for forming an antireflection film.
Thereby, for example, an antireflection film formed on a lens (plastic lens) such as an eyeglass lens can be formed with the coating liquid for film formation.

In the coating liquid for film formation of the present invention, acidic hydrolysis is carried out into a silane coupling agent containing at least one of a silane compound represented by the following general formula (1) and a halogenated silane represented by the following general formula (2). First, a catalyst A is added, and at least one of the silane compound and the halogenated silane is hydrolyzed and polycondensed in an environment of pH 3.0 to 5.0 to obtain a liquid A containing a chain siloxane oligomer. Process,
It is preferably obtained by the second step of adding silica-based fine particles to the liquid A obtained in the first step and hydrolyzing / condensing the siloxane oligomer in an environment of pH 5.0 to 7.0.
R ¹ _n R ² _p SiZ _{4- (n + p)} (1)
^(Wherein, R 1, ^{R 2} are, .Z hydrolyzable group containing at least one epoxy group in the organic group having 1 to 16 carbon atoms .n, p is, 1 ≦ an integer of 0 to 2 n + p ≦ 3.)
X _m R ³ _3-m Si-Y-SiR ³ _3-m X _m (2)
(In the formula, R ³ is a monovalent hydrocarbon group having 1 to 6 carbon atoms. Y is a divalent organic group containing one or more fluorine atoms. X is a hydrolyzable group. M is an integer of 1 to 3. .)
Thereby, the coating liquid for film formation can be manufactured easily.
The coating film of the present invention is characterized by being formed using the coating solution for film formation of the present invention.
Thereby, a dense coating film can be provided.

It is typical sectional drawing which shows the coating film concerning suitable embodiment of this invention. It is the graph which showed the relationship between pH value of silica sol, and reaction rate. It is an optical microscope photograph of the coating film of an Example and a comparative example.

Hereinafter, the film-forming coating solution and coating film of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
FIG. 1 is a schematic sectional view showing a coating film according to a preferred embodiment of the present invention, FIG. 2 is a graph showing the relationship between the pH value of silica sol and the reaction rate, and FIG. 3 is an example and a comparative example. It is an optical microscope photograph of the coating film. In the following, for convenience of explanation, the upper side in FIG. 1 is referred to as “upper” and the lower side is referred to as “lower”.

1. Film-forming coating liquid The film-forming coating liquid of the present invention has a binder containing a cross-linked siloxane polymer and a chain siloxane oligomer, and silica-based fine particles dispersed in the binder, The chain siloxane oligomer is grafted on the surface of the silica-based fine particles.
By grafting a chain-like siloxane oligomer onto the surface of the silica-based fine particles, the affinity between the binder and the silica-based fine particles can be increased, and the aggregation of the silica-based fine particles can be effectively suppressed. The dispersibility of the system fine particles can be improved. Therefore, the coating film formed using the coating liquid for film formation having such a configuration is a homogeneous and dense film. At the same time, the coating film can exhibit excellent adhesion, film strength, water resistance, chemical resistance, heat resistance and scratch resistance.

[binder]
As described above, the binder contains a crosslinked siloxane polymer and a chain siloxane oligomer. In addition, a linear siloxane polymer and a cyclic siloxane oligomer may be included.
The molecular weight (average molecular weight) of the cross-linked siloxane polymer is not particularly limited, but is preferably about 2500 to 15000, and more preferably about 5000 to 9000. By setting it as such a numerical range, while maintaining the dispersibility of the silica type fine particle in a binder high, the intensity | strength of a coating film can be raised.

Further, the content of the crosslinkable siloxane polymer in the binder is not particularly limited, but is preferably about 60 to 80 wt%, and more preferably 70 to 80 wt%. Thereby, the content of the crosslinkable siloxane polymer becomes an appropriate amount, and the above effect becomes more remarkable.
The molecular weight (average molecular weight) of the chain siloxane oligomer is not particularly limited, but is preferably about 500 to 5000, and more preferably about 1250 to 3250. Thereby, aggregation of the silica-based fine particles can be effectively prevented and the dispersibility of the silica-based fine particles is further improved.

The content of the chain siloxane oligomer in the binder is not particularly limited, but is preferably about 20 to 30 wt%. Thereby, it becomes an amount suitable for grafting the chain siloxane oligomer onto the silica-based fine particles. That is, generation of a chain siloxane oligomer that is not grafted onto the silica-based fine particles can be suppressed, and a denser coating film can be formed.
Further, the number of silicon contained in the main chain of the chain siloxane oligomer is not particularly limited, but is preferably three. Thereby, the above effect becomes more remarkable.

Further, when a linear siloxane polymer is contained, the linear siloxane polymer enters between the crosslinked siloxane polymers or between the crosslinked siloxane polymer and the silica-based fine particles. Thus, the obtained coating film becomes denser.
The molecular weight (average molecular weight) of such a linear siloxane polymer is not particularly limited, but is preferably about 1000 to 10000, more preferably about 2500 to 6500. Thereby, it becomes easy to enter between the crosslinkable siloxane polymers or between the crosslinkable siloxane polymer and the silica-based fine particles, and a denser coating film can be formed.
The content of the linear siloxane polymer in the binder is not particularly limited, but is preferably about 5 to 10 wt%. Thereby, the content of the linear type siloxane polymer becomes an appropriate amount, and the above effect becomes more remarkable.

Moreover, when the cyclic | annular siloxane oligomer is included, the coating liquid for film-forming will be stabilized by the synergistic effect with another binder component. Although it does not specifically limit as molecular weight (average molecular weight) of a cyclic siloxane oligomer, It is preferable that it is about 900-6000.
The content of the cyclic siloxane oligomer in the binder is not particularly limited, but is preferably about 1 to 15 wt%. Thereby, the above effect becomes more remarkable. In addition, when the content of the cyclic siloxane oligomer is less than the lower limit value, the stability of the coating solution for film formation may be lowered. On the contrary, when the content exceeds the upper limit value, the resulting coating film is obtained. There is a risk that the durability of the material may be reduced.
Moreover, it is preferable that the silicon contained in the ring of a cyclic siloxane oligomer is about 3-5. Thereby, since the magnitude | size of the air layer which can be formed in a ring can be made smaller, the fall of durability of a coating film can be prevented more effectively.

[Silica fine particles]
The silica-based fine particles are not particularly limited, but it is preferable to use hollow silica particles having cavities inside. The hollow silica particles are composed of SiO _2. Since such hollow silica particles have a low refractive index, the refractive index of the coating film 1 can be made sufficiently low, and can be suitably used as an antireflection film. Moreover, since such hollow silica particles are fine particles in the colloidal region and have excellent dispersibility, the silica-based fine particles can effectively prevent or suppress aggregation.

The average particle size of the silica-based fine particles is not particularly limited, but is preferably 55 nm or less, and more preferably about 41 nm or more and 52 nm or less. By setting such a numerical range, the silica-based fine particles can be stably present in the coating liquid for film formation. When the average particle size of the silica-based fine particles exceeds the maximum value, many unnecessary irregularities are formed on the surface of the coating film 1, and the haze value of the coating film may be increased.
The refractive index of the silica-based fine particles is preferably as low as possible. Specifically, it is preferably about 1.40 or less, and more preferably 1.35 or less. Thereby, the coating film which can exhibit the more superior antireflection performance can be formed using the coating liquid for film-forming.

  The content of the silica-based fine particles in the coating liquid for film formation is not particularly limited, but the content of the silica-based fine particles in the coating film formed using the coating liquid for film formation is 5.0 wt% as a solid content. % Is preferably about 3% to 30.0% by weight, and more preferably about 10.0% to 20.0% by weight. Thereby, the reflectance of a coating film can be made low and sufficient antireflection performance can be exhibited.

  As described above, a chain siloxane oligomer is grafted on the surface of such silica-based fine particles. Thereby, the affinity with respect to the binder or solvent of a silica type microparticle can be made high, and a dispersibility can be improved. Therefore, aggregation of the silica-based fine particles can be prevented, and the silica-based fine particles can be uniformly dispersed in the coating liquid for film formation. Therefore, a coating film formed using such a coating solution for film formation becomes dense and has excellent adhesion, film strength, and scratch resistance.

  Here, in the coating liquid for film formation of the present invention, the absolute value of the zeta potential at pH 5 to 7 of the silica-based fine particles grafted with the chain siloxane oligomer on the surface is 25 millivolts or more. By setting such a numerical range, the silica-based fine particles can be stably present in the coating liquid for film formation. Therefore, the agglomeration of the silica-based fine particles is effectively prevented by the synergistic effect with the grafting described above, and the coating film formed using such a coating liquid for film formation is dense, adhesive, Excellent strength and scratch resistance.

2. Coating Film Next, the coating film 1 formed with the above-described coating liquid for film formation will be described.
As shown in FIG. 1, the coating film 1 is formed on, for example, a lens substrate (plastic lens) 100 such as a spectacle lens and used as an antireflection film having antireflection performance.
The lens substrate 100 includes a lens fabric 101, a primer layer 102 formed on the surface of the lens fabric 101, and a hard coat layer 103 formed on the surface of the primer layer 102. A coating film 1 is formed on the surface. The lens substrate 100 is not limited to this, and the primer layer 102 and the hard coat layer 103 may be omitted.

[Lens substrate 100]
(Lens fabric 101)
The lens fabric 101 is not particularly limited, and various plastic lenses can be used. More specifically, as the lens fabric 101, for example, a thiourethane plastic lens substrate (manufactured by Seiko Epson Corporation, trade name “Seiko Super Sovereign Fabric”, refractive index 1.67) can be used.

(Primer layer 102)
The primer layer 102 is interposed between the lens fabric 101 and the hard coat layer 103 and is a layer for improving the adhesion. This primer layer 102, for example, expresses the refractive index of the primer (A) having adhesion to both the lens fabric 101 and the hard coat layer 103, and acts as a filler to improve the crosslinking density of the primer layer 102. Then, the lens fabric 101 can be formed by coating a composition containing the component (B) for improving water resistance and weather resistance.

  As the component (A), for example, various resin materials such as polyester resin, polyurethane resin, epoxy resin, melamine resin, polyolefin resin, urethane acrylate resin, and epoxy acrylate resin can be used. On the other hand, as the component (B), for example, metal oxide fine particles containing titanium oxide can be used, and the average particle diameter thereof is, for example, about 1 nm to 200 nm.

(Hard coat layer 103)
The hard coat layer 103 is a layer for protecting the surface of the lens fabric 101. The hard coat layer 103 is not particularly limited, but can be formed by coating the primer layer 102 with a composition containing the following components (C) and (D).

As the component (C), metal oxide particles containing titanium oxide can be used, and the average particle size is, for example, about 1 nm to 200 nm. The titanium oxide contained in the metal oxide particles preferably has a rutile crystal structure. On the other hand, as the component (D), an organic silicon compound represented by the general formula: R ¹ SiX ¹ ₃ (wherein R ¹ is an organic group having 2 or more carbon atoms having a polymerizable reactor, and X 1 is hydrolysis) Represents a group).
The example of the lens substrate 100 has been described above. In addition, before forming the coating film 1 on the lens substrate 100, it is preferable to perform plasma treatment (atmospheric plasma) on the lens substrate 100.

[Coating film 1]
The coating film 1 is obtained by applying a coating solution such as a film formation on the lens substrate 100 and drying it. The method for applying the film forming coating solution is not particularly limited, and for example, a coating method such as a spin coating method, a dip coating method, a roll coating method, a slit coater method, or a transfer method can be used. Among these, it is preferable to use a spin coat method, and this makes the coating film 1 have excellent film thickness uniformity and low dust generation.

The thickness of the coating film 1 is not particularly limited, but is preferably about 50 nm or more and 200 nm or less, more preferably about 80 nm or more and 120 nm or less, and further preferably about 100 nm.
The thermal expansion coefficient of the coating film 1 is preferably substantially equal to the thermal expansion coefficient of the lens fabric (base material) 101. Specifically, when the thermal expansion coefficient of the lens fabric 101 is A, the thermal expansion coefficient of the coating film 1 is preferably about 0.9A to 1.1A, and more preferably 1.0A. . Thereby, when the lens substrate 100 on which the coating film 1 is formed rises in temperature, the lens fabric 101 and the coating film 1 expand to the same extent, so that it is possible to prevent unintended stress from being applied to the coating film 1. it can. Therefore, breakage of the coating film 1, specifically, the generation of cracks can be effectively prevented or suppressed.

The Young's modulus of the coating film 1 is preferably larger than the Young's modulus of the lens fabric 101. Thereby, when the lens cloth 101 is bent by an external force, the coating film 1 can also be easily bent following the bending of the lens cloth 101, so that it is possible to prevent unintentional stress from being applied to the coating film 1. be able to. Therefore, breakage of the coating film 1, specifically, the generation of cracks can be effectively prevented or suppressed.
The refractive index of the coating film 1 is not particularly limited, but is preferably 1.40 or less. Thereby, the outstanding antireflection performance can be exhibited.

3. Next, a method for producing a coating liquid for film formation will be described.
The manufacturing method of the coating liquid for film-forming has the following 1st process and 2nd process.
[First step]
In the first step, an acidic hydrolysis catalyst is added to a silane coupling agent containing a silane compound represented by the following general formula (1) and a halogenated silane represented by the following general formula (2), and a pH of 3.0 to This is a step of obtaining a liquid A containing a chain siloxane oligomer by hydrolyzing and condensation-polymerizing a silane compound and a halogenated silane in an acidic environment of 5.0.

R ¹ _n R ² _p SiZ _{4- (n + p)} (1)
(In formula, R < ¹ >, R < ² > is a C1-C16 organic group and at least one contains an epoxy group. Z is a hydrolysable group. N and p are integers of 0-2, 1 ≦ n + p ≦ 3.)
X _m R ³ _3-m Si-Y-SiR ³ _3-m X _m (2)
(In the formula, R ³ represents a hydrocarbon group having 1 to 6 carbon atoms, Y represents a divalent organic group containing one or more fluorine atoms, and X represents a hydrolyzable group. , M is an integer of 1 to 3.)

  The compound represented by the formula (1) is appropriately selected according to the purpose such as adhesion to the substrate, hardness and low reflectivity of the resulting coating film, and the life of the composition. Sidoxymethyltrimethoxysilane, glycidoxymethyltriethoxysilane, α-glycidoxyethyltrimethoxysilane, α-glycidoxyethyltriethoxysilane, β-glycidoxyethyltriethoxysilane, β-glycidoxy Propyltrimethoxysilane, α-glycidoxypropyltrimethoxysilane, α-glycidoxypropyltriethoxysilane, β-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, (3,4- Epoxycyclohexyl) methyltrimethoxysilane, γ-glycidoxypropylvinyldiethoxysilane, - glycidoxypropyl phenyl diethoxy silane, .delta. (3,4-epoxycyclohexyl) butyl triethoxy silane, and the like.

Among these, the silane compound represented by the formula (1) is preferably n + p = 1, that is, a trifunctional silane compound having three (—SiZ groups). Thereby, the chain | strand-shaped siloxane oligomer mentioned later can be produced | generated efficiently.
The content of the silane compound is preferably 0.1 wt% or more and 50.0 wt% or less with respect to the total amount of the silane coupling agent, and is 4.0 wt% or more and 15.0 wt% or less. Is more preferable. Thereby, the coating film 1 can exhibit more excellent antireflection properties, antifouling properties, water repellency, scratch resistance, chemical resistance, and the like.

The halogenated silane represented by the formula (2) is not particularly limited, but the number of fluorine atoms is preferably 4 or more and 50 or less, and more preferably 4 or more and 24 or less. Thereby, the coating film formed using the coating liquid for film formation can exhibit excellent antireflection properties, antifouling properties, water repellency, scratch resistance, chemical resistance, and the like.
When the number of fluorine atoms contained in the halogenated silane represented by the formula (2) is less than the lower limit, depending on the content of the halogenated silane, the above-described effects may not be exhibited sufficiently. There is. On the other hand, when the number of fluorine atoms exceeds the upper limit, depending on the content of the halogenated silane and the like, the density of the coating film may decrease.

As Y in said Formula (2), the thing of the following structure is preferable, for example.
_{-CH 2 CH 2 (CF 2)} n CH 2 CH 2 -
_{-C 2 H 4 -CF (CF 3} ) - (CF 2) n -CF (CF 3) -C 2 H 4 -
(N is an integer of 2 to 20.)
Moreover, as R < ³ > in said Formula (2), what is necessary is just a C1-C6 alkyl group, for example, alkyl groups, such as a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, a cyclohexyl group, etc. And a phenyl group. Among these, R ³ is preferably a methyl group for the purpose of obtaining excellent scratch resistance.
Moreover, m in the formula (2) is an integer of 1 to 3, but is preferably 2 or 3, more preferably 3. Thereby, the coating film 1 can be made harder.

  X in the formula (2) represents a hydrolyzable group. Specific examples include halogen atoms such as Cl, organooxy groups represented by ORX (RX is a monovalent hydrocarbon group having 1 to 6 carbon atoms), particularly methoxy group, ethoxy group, propoxy group, isopropoxy group, butoxy. An alkoxy group such as an isopropenoxy group, an acyloxy group such as an acetoxy group, a ketoxime group such as a methylethylketoxime group, and an alkoxyalkoxy group such as a methoxyethoxy group. Among these, an alkoxy group is preferable, and a silane compound having a methoxy group or an ethoxy group is particularly preferable because it is easy to handle and the reaction during hydrolysis is easily controlled. Examples of such X include the following structures.

_{(CH 3 O) 3 Si-} C 2 H 4 -C 4 F 8 -C 2 H 4 -Si (OCH 3) 3
_{(CH 3 O) 3 Si-} C 2 H 4 -C 6 F 12 -C 2 H 4 -Si (OCH 3) 3
_{(CH 3 O) 3 Si-} C 2 H 4 -C 8 F 16 -C 2 H 4 -Si (OCH 3) 3
_{(C 2 H 5 O) 3} Si-C 2 H 4 -C 4 F 8 -C 2 H 4 -Si (OC 2 H 5) 3
_{(C 2 H 5 O) 3} Si-C 2 H 4 -C 6 F 12 -C 2 H 4 -Si (OC 2 H 5) 3
_{(C 2 H 5 O) 2} (CH 3) Si-C 2 H 4 -C 6 F 12 -C 2 H 4 -Si (CH 3) (OC 2 H 5) 2

  The content of the halogenated silane is preferably 50.0% by weight or more and 99.9% by weight or less with respect to the total amount of the silane coupling agent, and is 85.0% by weight or more and 96.0% by weight. The following is more preferable. Thereby, the coating film 1 formed using the coating liquid for film formation can exhibit more excellent antireflection properties, antifouling properties, water repellency, scratch resistance, chemical resistance, and the like.

The acidic hydrolysis catalyst is added to hydrolyze / condensate the silane compound represented by the formula (1) and the halogenated silane represented by the formula (2). Examples of such an acidic hydrolysis catalyst include inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid, and organic acids such as oxalic acid, acetic acid, trifluoroacetic acid, methanesulfonic acid, trifluoromethanesulfonic acid, and lactic acid. .
When the silane compound represented by the formula (1) and the halogenated silane represented by the formula (2) are each hydrolyzed and polycondensed in an environment of pH 3.0 to 5.0, a trimer is obtained. A chain siloxane oligomer and a cyclic siloxane oligomer of about tetramer to hexamer are produced, and a liquid A containing them is obtained.

The liquid A contains more chain siloxane oligomers than cyclic siloxane oligomers. The reason for this will be described in detail below.
FIG. 2 is a graph showing the relationship between the pH value of silica sol and the reaction rate (Surface Technology Vol. 50, No. 2, pages 161-164, “Simple overview of sol-gel method and its use”, Motoyuki Toki, see ).

As shown in FIG. 2, the hydrolysis reaction rate gradually decreases from pH 1 to 7, and gradually increases from pH 7 to 14. On the other hand, the condensation polymerization reaction rate gradually decreases from pH 1 to 2, gradually increases from pH 2 to 7, and gradually decreases again from pH 7 to 14. Moreover, the hydrolysis reaction rate and the condensation polymerization reaction rate become substantially equal at about pH 4.
In the pH range of 3.0 to 5.0, which is the pH environment of this step, the hydrolysis reaction rate and the condensation polymerization reaction rate are relatively slow and the rates are almost equal. In such an environment, it is difficult for the silane compound represented by the formula (1) and the halogenated silane represented by the formula (2) to be polymerized, and a trimer siloxane oligomer is mainly generated. A slight amount of a siloxane oligomer of about a monomer to a hexamer is produced. Here, it is conventionally known that a trimer siloxane oligomer is in a chain form, and a tetramer or higher siloxane oligomer is cyclic. Therefore, the liquid A contains more chain-like siloxane oligomer than cyclic siloxane oligomer.

The weight ratio of the chain siloxane oligomer and the cyclic siloxane oligomer in the liquid A is not particularly limited, but the chain siloxane oligomer: cyclic siloxane oligomer is about 8: 2 to 9.5: 0.5. Preferably there is. Thereby, the coating liquid for film formation which can form the denser coating film 1 is obtained.
In addition, although said reaction should just be about pH 3.0-5.0, it is more preferable that it is about pH 4.0. As described above, in the environment of pH 4.0, the hydrolysis reaction rate and the condensation polymerization reaction rate are equal, so that more chain-like siloxane oligomers can be efficiently produced while suppressing the formation of cyclic siloxane oligomers. Can do.

  The reaction time for hydrolysis / condensation polymerization in the first step is not particularly limited, but is preferably about 100 hours or more and 150 hours or less at room temperature, more preferably about 120 hours. As described above, in the environment of pH 3.0 to 5.0, both the hydrolysis reaction and the polycondensation reaction of the silane compound represented by the formula (1) are relatively slow. Thus, the reaction can be sufficiently performed. The same applies to the halogenated silane represented by the formula (2).

[Second step]
In the second step, silica-based fine particles are added to the liquid A obtained in the first step, and the chain siloxane oligomer contained in the liquid A is hydrolyzed and polycondensed in an environment of pH 5.0 to 7.0. It is a process.
Silica-based fine particles are hollow silica particles having cavities inside. The hollow silica particles are composed of SiO _2. Since such hollow silica particles have a low refractive index, the refractive index of the formed coating film can be sufficiently lowered, and can be suitably used as an antireflection film. Moreover, since such hollow silica particles are fine particles in a colloidal region and have excellent dispersibility, aggregation of the hollow silica particles can be effectively prevented or suppressed.
Such silica-based fine particles can be added to the liquid A in a state of being dispersed in a dispersion medium. Thereby, aggregation of the silica-based fine particles can be effectively prevented, and the pH of the mixture with the liquid A can be shifted to the basic side by the mutual effect with the dispersion medium.

The dispersion medium for dispersing the silica-based fine particles is not particularly limited, but is preferably neutral or basic. Thereby, the pH of the mixture with the liquid A can be shifted from the region of 3.0 to 5.0 to the basic side.
Examples of such a dispersion medium include water, an organic solvent, or a mixed solvent thereof. Specifically, water such as pure water, ultrapure water, and ion exchange water, alcohols such as methanol, ethanol, isopropanol, n-butanol, and methyl isocarbinol, acetone, 2-butanone, ethyl amyl ketone, diacetone Ketones such as alcohol, isophorone, cyclohexanone, amides such as N, N-dimethylformamide, N, N-dimethylacetamide, diethyl ether, isopropyl ether, tetrahydrofuran, 1,4-dioxane, 3,4-dihydro-2H- Ethers such as pyran, glycol ethers such as 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, ethylene glycol dimethyl ether, 2-methoxyethyl acetate, 2-ethoxyethyl acetate, 2-butoxy Glycol ether acetates such as tilacetate, methyl acetate, ethyl acetate, isobutyl acetate, amyl acetate, ethyl lactate, esters such as ethylene carbonate, aromatic hydrocarbons such as benzene, toluene, xylene, hexane, heptane, iso- Aliphatic hydrocarbons such as octane and cyclohexane, halogenated hydrocarbons such as methylene chloride, 1,2-dichloroethane, dichloropropane and chlorobenzene, sulfoxides such as dimethyl sulfoxide, N-methyl-2-pyrrolidone, N- Examples include pyrrolidones such as octyl-2-pyrrolidone.

The pH of the dispersion liquid in which the silica-based fine particles are dispersed is not particularly limited as long as the pH of the mixture can be adjusted to 5.0 to 7.0 when mixed with the liquid A. However, the pH is about 7.0. preferable.
By adding such a dispersion to the liquid A, silica-based fine particles are supplied into the liquid A, and the pH of the mixture of the liquid A and the dispersion is set to 5.0 to 7.0. The chain siloxane oligomer contained in the liquid A is hydrolyzed and polycondensed.

As shown in FIG. 2, in the range of pH 5.0 to 7.0, the condensation polymerization reaction rate is faster than the hydrolysis reaction rate. Therefore, a plurality of chain siloxane oligomers are formed by the hydrolysis / condensation polymerization. A cross-linked siloxane polymer and a linear siloxane polymer formed by bonding are formed. At the same time, the chain siloxane oligomer is grafted onto the surface of the silica-based fine particles. Accordingly, the surface of the silica-based fine particle has a cross-linked siloxane polymer, a linear siloxane polymer, a binder containing a chain siloxane oligomer and a cyclic siloxane oligomer, and silica-based fine particles dispersed in the binder. Liquid B in which a chain siloxane oligomer is grafted is obtained.
In this step, in particular, more cross-linked siloxane polymer can be produced.

  Here, it is preferable that the hydrolysis reaction rate in the second step is slower than the hydrolysis reaction rate in the first step, and the condensation polymerization reaction rate in the second step is faster than the condensation polymerization reaction rate in the first step. As a result, the condensation polymerization reaction rate can be made relatively fast, and the difference between the hydrolysis reaction rate and the condensation polymerization reaction rate can be made relatively large. A liquid B containing can be produced. That is, more cross-linked siloxane polymer can be produced. Moreover, aggregation of silica-based fine particles can be prevented or suppressed more effectively.

The hydrolysis / condensation polymerization in the second step is not particularly limited as the rate of the hydrolysis reaction, but is preferably 30% or less of the rate of the condensation polymerization reaction. Thereby, the above effect becomes more remarkable.
For example, a coating liquid for film formation can be obtained by mixing the liquid B with a solvent as necessary.

Thus, by grafting the chain siloxane oligomer and treating the surface of the silica-based fine particles, the affinity of the silica-based fine particles to the binder and solvent can be increased, and the dispersibility can be improved. Silica-based fine particles can be uniformly dispersed in the coating solution for film formation. Therefore, a coating film formed using such a coating solution for film formation becomes denser and has excellent adhesion, film strength, and scratch resistance.
In addition, since a crosslinkable siloxane polymer is included as a binder component, a coating film formed using such a film-forming coating solution has excellent adhesion, film strength, and scratch resistance.

  The reaction time of hydrolysis / condensation polymerization in the second step is not particularly limited, but it is preferably about 20 hours to 30 hours at a low temperature of 0 ° C. or higher and 20 ° C. or lower, preferably about 10 hours at 10 ° C. More preferably. As described above, since the polycondensation reaction of the siloxane oligomer is relatively fast in an environment of pH 5.0 to 7.0, the above reaction can be reliably and sufficiently performed by setting the time as described above. it can.

3. Method for Forming Coating Film 1 Using Film-Forming Coating Solution Coating film 1 can be formed, for example, as follows.
[Coating process]
First, a film-forming coating solution is applied onto the lens substrate 100 (hard coat layer 103). The coating method is not particularly limited, and for example, a coating method such as spin coating, dip coating, roll coating, slit coater, or transfer can be used. Among these, it is preferable to use a spin coating method, and this makes the coating film thickness uniform and low dust generation excellent.

[Baking]
Next, the film-forming coating solution applied on the lens substrate 100 is temporarily fired at a temperature of about 90 ° C. to 110 ° C. for about 1 minute to 10 minutes. The pre-baking can be performed in a nitrogen gas atmosphere or an air atmosphere as an inert gas.
Next, the pre-baked film forming coating solution is finally fired. The main baking is performed at a temperature of about 110 ° C. to 130 ° C. for about 1 hour to 2 hours. The main baking can be performed in an atmosphere of nitrogen gas as an inert gas or in an air atmosphere.
Through the above-described steps, the coating film 1 formed using the film-forming coating solution is formed.
The film forming coating solution and the coating film of the present invention have been described above, but the present invention is not limited to this.

1. Preparation of preparation liquid and coating liquid for film formation (Example 1)
In a stainless steel container, 2.8 parts by weight of a silane compound (alkoxysilane) represented by the following formula (A), 27.8 parts by weight of a halogenated silane represented by the following formula (B), and 0.1 × 152.9 parts by weight of a 10 ⁻³ mol / L nitric acid aqueous solution was added and mixed well to obtain a mixed solution (first mixed solution) having a pH of 4.0 at 25 ° C. This mixed liquid was stirred at 25 ° C. for 120 hours to obtain a preparation liquid which was a liquid having a solid content of 10.0% by weight.

  This preparative solution and a hollow silica-isopropanol dispersion sol (manufactured by Catalytic Chemical Industry Co., Ltd .; solid content concentration 20% by weight, average primary particle size 35 nm, outer shell thickness 8 nm) are liquid / hollow silica in a solid content ratio of 70/30. The resulting mixture was mixed well to obtain a mixed solution (second mixed solution) having a pH of 5.5 at 25 ° C. This mixed solution was stirred at 10 ° C. for 24 hours to obtain a coating solution for film formation having a solid content of 6.3% by weight.

(Comparative Example 1)
In a stainless steel container, 2.8 parts by weight of the silane compound represented by the above formula (A), 27.8 parts by weight of the halogenated silane represented by the above formula (B), and 0.1 mol / L hydrochloric acid 152.9 parts by weight of an aqueous solution was added and mixed well to obtain a mixed solution having a pH of 1.0 at 25 ° C. This mixed liquid was stirred at 25 ° C. for 5 minutes to obtain a preparation liquid which was a liquid having a solid content of 10.0% by weight.

  This preparative solution and a hollow silica-isopropanol dispersion sol (manufactured by Catalytic Chemical Industry Co., Ltd .; solid content concentration 20% by weight, average primary particle size 35 nm, outer shell thickness 8 nm) are liquid / hollow silica in a solid content ratio of 70/30. And mixed well to obtain a mixed solution having a pH of 1.0 at 25 ° C. This mixed solution was stirred at 25 ° C. for 24 hours to obtain a coating solution for film formation having a solid content of 6.3% by weight.

2. Coating Film Formation A coating liquid was obtained by adding 420 parts of propylene glycol monomethyl ether to the film-forming coating liquids of Example 1 and Comparative Example 1 described above and diluting them. Next, the coating liquid was applied onto the lens substrate by a spin coating method, and this was temporarily fired at 100 ° C. for 10 minutes in the air. Next, the main calcination was performed in the air at 120 ° C. for 1.5 hours. This formed the coating film. The thickness (average thickness) of this coating film was 100 nm.
The lens substrate was obtained as follows.

(1) Preparation of primer composition In a stainless steel container, 3700 parts by weight of methyl alcohol, 250 parts by weight of water, and 1000 parts by weight of propylene glycol monomethyl ether were added and stirred sufficiently, followed by titanium oxide, zirconium oxide, silicon oxide. 2800 parts by weight of a composite fine particle sol (anatase type crystal structure, methanol dispersion, total solid concentration 20% by weight, Catalytic Kasei Kogyo Co., Ltd., trade name Optlake 1120Z U-25 / A8) was added and mixed. . Next, 2200 parts by weight of polyurethane resin was added and stirred and mixed, then 2 parts by weight of a silicone surfactant (manufactured by Nippon Unicar Co., Ltd., trade name L-7604) was added and stirring was continued all day and night, and then a 2 μm filter. Filtration was performed to obtain a primer composition.

(2) Preparation of hard coat composition Take 1000 parts by weight of butyl cellosolve in a stainless steel container, add 1200 parts by weight of γ-glycidoxypropyltrimethoxysilane, stir well, and then add 300 moles of 0.1 mol / liter hydrochloric acid. Part was added and stirring was continued for a whole day and night to obtain a silane hydrolyzate. To this silane hydrolyzate, 30 parts by weight of a silicone surfactant (manufactured by Nippon Unicar Co., Ltd .; trade name L-7001) was added and stirred for 1 hour, and then mainly composed of titanium oxide, tin oxide and silicon oxide. 7300 parts by weight of a composite fine particle sol (rutile crystal structure, methanol dispersion, manufactured by Catalyst Kasei Kogyo Co., Ltd .; trade name OPTRAIQUE 1120Z 8RU-25, A17) was added and mixed with stirring for 2 hours. Next, 250 parts by weight of an epoxy resin (manufactured by Nagase Kasei Co., Ltd., trade name Denacol EX-313) was added and stirred for 2 hours, and then 20 parts by weight of iron (III) acetylacetonate was added and stirred for 1 hour. Filtration with a filter gave a hard coat composition.

(3) Formation of primer layer and hard coat layer A thiourethane plastic lens substrate (manufactured by Seiko Epson Corporation, trade name Seiko Super Sovereign Fabric, Refractive Index 1.67) was prepared. Then, the prepared lens base material was subjected to an alkali treatment (immersion in a 2.0 N aqueous potassium hydroxide solution maintained at 50 ° C. for 5 minutes, followed by washing with pure water, and then to 0.5 N sulfuric acid maintained at 25 ° C. It was immersed for 1 minute to neutralize), washed with pure water, dried and allowed to cool. And it is immersed in the primer composition prepared in (1), and the lifting speed is 30 cm / min. And baked at 80 ° C. for 20 minutes to form a primer layer on the lens substrate surface. And the lens base material in which the primer layer was formed was immersed in the hard coat composition prepared in (2), and the lifting speed was 30 cm / min. And baked at 80 ° C. for 30 minutes to form a hard coat layer on the primer layer. Then, it heated for 3 hours in the oven set to 125 degreeC, and obtained the plastic lens in which the primer layer and the hard-coat layer were formed. The formed primer layer had a thickness of 0.5 μm, and the hard coat layer had a thickness of 2.5 μm.
Then, a plastic lens on which a primer layer and a hard coat layer are formed and subjected to plasma treatment (atmospheric plasma) was used as the lens substrate.

3. Measurement (3-1) Measurement of zeta potential and average particle diameter With respect to the coating liquid for film formation of Example 1 and Comparative Example 1, the zeta potential and average particle diameter of silica-based fine particles were measured. The zeta potential and average particle diameter were measured by ultrasonic spectroscopy (Dispersion Technology, DT1200). As a result, in the film-forming coating liquid of Example 1, the zeta potential of silica-based fine particles at pH 5.5 was -33.1 millivolts and the average particle diameter was 47.5 nm. Then, the zeta potential of silica-based fine particles at pH 1.0 was -19.7 millivolts, and the average particle size was 58.4 nm.

4). Evaluation (4-1) Warm water resistance The lens substrate (the coating film of Example 1 and the coating film of Comparative Example 1) was dipped in accordance with the spectacle frame shape and then immersed in warm water at 60 ° C. for 20 days. . Thereafter, the lens was taken out from the warm water, cooled with water, scraped off water droplets, and then the state of film peeling of the coating film was visually evaluated according to the following criteria A to D. The results are shown in Table 2 below.
A: No film peeling (peeling area ratio 0%)
B: Almost no film peeling (peeling area ratio of 1 to 19%)
C: Slight peeling (peeling area ratio 20 to 49%)
D: Film peeling occurs (peeling area ratio of 50% or more)

  As is clear from Table 1, the coating film of Example 1 was superior to the coating film of Comparative Example 1 in hot water resistance. Thereby, it is clear that the coating film of Example 1 (coating film of the present invention) is a dense film compared to the coating film of Comparative Example 1 (conventional coating film).

(4-2) Silica-based fine particle cohesiveness The coating films of Example 1 and Comparative Example 1 were observed using an optical microscope (system biological microscope BX50 manufactured by Olympus Corporation). The result is shown in FIG. 3A shows Example 1, and FIG. 3B shows Comparative Example 1.
As is clear from FIG. 3, the coating film of Example 1 has very few points A that appear white compared to the coating film of Comparative Example 1. Specifically, in the range of 0.71 mm (vertical) × 0.95 mm (horizontal), 118 points A were generated in the coating film of Example 1, and were generated in the coating film of Comparative Example 1. The number of points A was 727. That is, in the coating film of Example 1, the point A decreased by 83.8% compared to the coating film of Comparative Example 1.

  Here, the point A is a secondary particle in which silica particles are aggregated. Further, the point A is relatively large, and a part of the point A protrudes from the surface of the coating film to the outside in many cases. Therefore, there is a high possibility that the secondary particles are peeled off from the coating film when the coating film is wiped with a cloth or the like. When such secondary particles are peeled off, cracks are generated from the portions, scratches are spread, and liquid or the like easily enters the film. That is, the more secondary particles, the lower the heat resistance and scratch resistance. Therefore, it is clear that the coating film of Example 1 is superior in heat resistance and scratch resistance as compared with the coating film of Comparative Example 1.

  DESCRIPTION OF SYMBOLS 1 ... Coating film 100 ... Lens substrate 101 ... Lens cloth 102 ... Primer layer 103 ... Hard-coat layer

Claims (11)

A binder having a crosslinked siloxane polymer and a chain siloxane oligomer;
Having silica-based fine particles dispersed in the binder,
The chain siloxane oligomer is grafted on the surface of the silica-based fine particles,
The coating liquid for film formation, wherein the absolute value of zeta potential of the silica-based fine particles grafted with the chain siloxane oligomer is 25 millivolts or more at pH 5-7.   The coating liquid for film formation according to claim 1, wherein the average particle diameter of the silica-based fine particles is 55 nm or less.   The coating solution for film formation according to claim 1 or 2, wherein the content of the crosslinkable siloxane polymer in the binder is 60 to 80 wt%.   The coating liquid for film formation according to any one of claims 1 to 3, wherein the binder further contains a linear siloxane polymer.   The coating solution for film formation according to claim 4, wherein the content of the linear siloxane polymer in the binder is 20 to 30 wt%.   The coating liquid for film formation according to claim 1, wherein the binder further contains a cyclic siloxane oligomer.   The coating solution for film formation according to claim 6, wherein the content of the cyclic siloxane oligomer in the binder is 1 to 15 wt%.   The coating liquid for film formation according to claim 1, wherein the silica-based fine particles are hollow silica particles.   The coating solution for film formation according to any one of claims 1 to 8, which is a coating solution for forming an antireflection film. An acidic hydrolysis catalyst is added to a silane coupling agent containing at least one of a silane compound represented by the following general formula (1) and a halogenated silane represented by the following general formula (2), and the pH is 3.0 to 5. A first step of obtaining a liquid A containing a chain siloxane oligomer by hydrolysis / condensation polymerization of at least one of the silane compound and the halogenated silane in an environment of 0;
A silica-based fine particle is added to the liquid A obtained in the first step, and the second step of hydrolyzing and polycondensing the siloxane oligomer in an environment of pH 5.0 to 7.0. The coating solution for film formation according to any one of 8.
R ¹ _n R ² _p SiZ _{4- (n + p)} (1)
^(Wherein, R 1, ^{R 2} are, .Z hydrolyzable group containing at least one epoxy group in the organic group having 1 to 16 carbon atoms .n, p is, 1 ≦ an integer of 0 to 2 n + p ≦ 3.)
X _m R ³ _3-m Si-Y-SiR ³ _3-m X _m (2)
(In the formula, R ³ is a monovalent hydrocarbon group having 1 to 6 carbon atoms. Y is a divalent organic group containing one or more fluorine atoms. X is a hydrolyzable group. M is an integer of 1 to 3. .)   A coating film formed using the coating liquid for film formation according to claim 1.

Images