JP2020012078A - Silica dispersion and production method of the same, photocurable composition using the same, and cured product - Google Patents

Abstract

To provide a silica dispersion that gives a good effect of improving scratch resistance of a cured film of a photocurable coating composition.SOLUTION: The silica dispersion comprises a liquid compound having a radically polymerizable unsaturated bond, in which surface-treated sol-gel silica particles are dispersed. The surface-treated sol-gel silica is a material surface-treated with at least one of a predetermined organic silicon compound having a (meth)acrylic group and a (partially) hydrolyzed condensed product of the compound, and is prepared by adding 10 pts.mass or more of a predetermined organic silicon compound having a (meth)acrylic group to a dispersion containing sol-gel silica particles having a median diameter of 1 to 60 nm in a volume-based particle size distribution, with respect to 100 pts.mass of the sol-gel silica particles.SELECTED DRAWING: None

Description

  The present invention relates to a silica dispersion that can be introduced into a photocurable coating composition, a method for producing the same, a photocurable composition using the same, and a cured product thereof.

  Photocurable coating compositions are widely used for coating transparent plastic materials because of their short curing times and curability at low temperatures. Plastic materials have a lower surface hardness than glass, and are easily damaged on the surface. Therefore, the photocurable coating film used is required to have high scratch resistance and abrasion resistance.

  As a method of improving the scratch resistance of a coating film, the addition of silica particles to a photocurable coating composition has been proposed. It is known that the abrasion resistance of the film is improved (Patent Documents 1 to 5). The abrasion resistance effect by the addition of silica basically increases in proportion to the amount of silica added. However, when the amount of silica added reaches about 20% by mass, the addition of silica does not improve the abrasion resistance. And the effect of improving the scratch resistance is limited. Therefore, there is a need for a silica material having a higher scratch resistance improving effect.

  Although the improvement of scratch resistance has been studied so far by treating the silica particle surface with various organic compounds, the effect of the type of silica particles used on the scratch resistance has been considered in most cases. In many cases, an aqueous dispersion of colloidal silica prepared by a water glass method is used as a raw material. On the other hand, for example, Patent Document 6 reports that high scratch resistance tends to be exhibited when acidic colloidal silica having a low sodium component is used, and the type of silica used has a large effect on scratch resistance. there is a possibility.

  Conventional types of silica include ion-exchange silica and sol-gel silica. Ion-exchange silica is generally produced by partially ion-exchanging an aqueous solution of sodium silicate.When ion-exchange silica is used as a raw material, it is used when complexing with an organic solvent-based paint. In addition, it is necessary to replace the water solvent with an organic solvent, which requires a complicated process. Further, in the process, there is a high possibility that the surface treating agent is decomposed and self-condensed by water, which may hinder the surface treatment of the particles. In addition, it often contains a certain amount of an alkali metal component, which may not be suitable for use in coatings for electronic materials.

  On the other hand, silica obtained by hydrolysis of alkoxysilane such as tetraalkoxysilane is called sol-gel method (Stover method) silica, and is known to be spherical particles having a uniform particle diameter. In addition, since no alkali metal component is contained as an impurity in the production method, there is no risk of contamination by an alkali metal, and in addition, the steps from particle preparation to surface treatment can be performed in an alcohol solvent. Side reactions such as decomposition and self-condensation of the surface treatment agent due to the reaction between the agent and excess water can be suppressed. However, as compared with conventional ion-exchange silica, the effect of adding sol-gel silica to the photocurable coating composition has not been clarified in many parts.

JP-A-2017-132975 Japanese Patent No. 618947 Japanese Patent No. 3999285 Japanese Patent No. 3436492 International Publication No. 2017/111094 Japanese Patent No. 4104678

  The present invention has been made in view of the above circumstances, and a silica dispersion liquid which gives a cured film of a photocurable coating composition a good scratch resistance improving effect, a method for producing the same, and a photocurable composition using the same It is an object to provide a product and a cured product thereof.

  The present inventors have conducted intensive studies to achieve the above object, and as a result, adopted sol-gel silica as silica particles, and treated the surface of the sol-gel silica particles with an organosilicon compound having a predetermined (meth) acrylic group. In this case, it has been found that a silica dispersion liquid having a high effect of improving the scratch resistance of the photocurable film can be obtained by adding it to the photocurable composition, and the present invention has been accomplished. In the present invention, “(meth) acryl group” means “acryl group” or “methacryl group”.

（式中、Ｒ¹は水素原子又は炭素原子数１〜８のアルキル基であり、Ｒ²は炭素原子数１〜２０のアルキレン基であり、Ｒ³はそれぞれ独立に水素原子又は炭素原子数１〜８のアルキル基であり、Ｒ⁴はそれぞれ独立に水酸基、炭素原子数１〜６のアルコキシ基、又はハロゲン原子であり、ｎは１〜３の整数である。）
〔２〕
ゾルゲルシリカ粒子の²⁹Ｓｉ−ＮＭＲスペクトルにおける−８０〜−１３０ｐｐｍのピーク面積（Ｑ）に対する−１０５〜−１３０ｐｐｍのピーク面積（Ｑ⁴）の割合（Ｑ⁴／Ｑ）が０．８以下である〔１〕記載のシリカ分散液。
〔３〕
ゾルゲルシリカ粒子の体積基準の粒度分布におけるＤ９０／Ｄ１０の値が３．２以下である〔１〕又は〔２〕記載のシリカ分散液。
〔４〕
（メタ）アクリル基を有する有機ケイ素化合物が、下記式（２）で表される化合物を含む〔１〕〜〔３〕のいずれかに記載のシリカ分散液。

（式中、Ｒ³、Ｒ⁴、ｎは前記と同様である。）
〔５〕
（メタ）アクリル基を有する有機ケイ素化合物が、下記式（３）で表される化合物を含む〔１〕〜〔３〕のいずれかに記載のシリカ分散液。

（式中、Ｒ³、Ｒ⁴、ｎは前記と同様である。）
〔６〕
（メタ）アクリル基を有する有機ケイ素化合物が、下記式（４）で表される化合物を含む〔１〕〜〔３〕のいずれかに記載のシリカ分散液。

（式中、Ｒ³、Ｒ⁴、ｎは前記と同様である。）
〔７〕
表面処理ゾルゲルシリカ粒子が、更に下記式（５）で表されるシラン化合物の１種以上で表面処理されたものである〔１〕〜〔６〕のいずれかに記載のシリカ分散液。
Ｒ⁵ ₃ＳｉＹ （５）
（式中、Ｒ⁵は炭素原子数１〜２０の１価炭化水素基であり、Ｙは水酸基、炭素原子数１〜６のアルコキシ基、アミノ基、アシルオキシ基又はハロゲン原子である。）
〔８〕
ラジカル重合性不飽和結合を有する液状化合物が、１，６−ヘキサンジオールジアクリレート、トリメチロールプロパントリアクリレート及びジペンタエリスリトールヘキサアクリレートのうち少なくとも１種を含む〔１〕〜〔７〕のいずれかに記載のシリカ分散液。
〔９〕
前記ラジカル重合性不飽和結合を有する液状化合物１００質量部に対して、前記表面処理ゾルゲルシリカ粒子を５〜２５０質量部含む〔１〕〜〔８〕のいずれかに記載のシリカ分散液。
〔１０〕
ナトリウム含有量が１００ｐｐｍ以下である〔１〕〜〔９〕のいずれかに記載のシリカ分散液。
〔１１〕
〔１〕〜〔１０〕のいずれかに記載のシリカ分散液を含む光硬化性組成物。
〔１２〕
〔１１〕に記載の光硬化性組成物を硬化させてなる硬化物。
〔１３〕
（Ａ１）下記式（６）で表されるシラン化合物、その（部分）加水分解縮合物又はこれらの混合物を塩基性物質の存在下で親水性有機溶媒及び水の混合溶媒中で加水分解・縮合することによってゾルゲルシリカ粒子の有機溶媒・水分散液を得る工程と、
Ｓｉ（ＯＲ⁶）₄ （６）
（但し、Ｒ⁶はそれぞれ独立に水素原子又は炭素原子数１〜６の１価炭化水素基である。）
（Ａ２）前記ゾルゲルシリカ粒子の分散液に、該ゾルゲルシリカ粒子１００質量部に対して下記式（１）で表される（メタ）アクリル基を有する有機ケイ素化合物及びその（部分）加水分解縮合物のうちの少なくとも１種を１０質量部以上添加して、前記ゾルゲルシリカ粒子の表面を処理する工程と、

（式中、Ｒ¹は水素原子又は炭素原子数１〜８のアルキル基であり、Ｒ²は炭素原子数１〜２０のアルキレン基であり、Ｒ³はそれぞれ独立に水素原子又は炭素原子数１〜８のアルキル基であり、Ｒ⁴はそれぞれ独立に水酸基、炭素原子数１〜６のアルコキシ基、又はハロゲン原子であり、ｎは１〜３の整数である。）
（Ａ３）工程（Ａ２）で得られた、（メタ）アクリル基を有する有機ケイ素化合物で表面処理されたゾルゲルシリカ粒子の分散液に、ラジカル重合性不飽和結合を有する液状化合物を添加し、前記の親水性有機溶媒、水、及び場合により前記表面処理によって生じたアルコールを留去によって除く工程
とを有するシリカ分散液の製造方法。
〔１４〕
工程（Ａ１）で得られたゾルゲルシリカ粒子の²⁹Ｓｉ−ＮＭＲスペクトルにおける−８０〜−１３０ｐｐｍのピーク面積（Ｑ）に対する−１０５〜−１３０ｐｐｍのピーク面積（Ｑ⁴）の割合（Ｑ⁴／Ｑ）が０．８以下である〔１３〕記載のシリカ分散液の製造方法。
〔１５〕
工程（Ａ１）で得られたゾルゲルシリカ粒子の粒度分布におけるＤ９０／Ｄ１０の値が３．２以下である〔１３〕又は〔１４〕記載のシリカ分散液の製造方法。
〔１６〕
工程（Ａ２）において、（メタ）アクリル基を有する有機ケイ素化合物が、下記式（２）で表される化合物を含む〔１３〕〜〔１５〕のいずれかに記載のシリカ分散液の製造方法。

（式中、Ｒ³、Ｒ⁴、ｎは前記と同様である。）
〔１７〕
工程（Ａ２）において、（メタ）アクリル基を有する有機ケイ素化合物が、下記式（３）で表される化合物を含む〔１３〕〜〔１５〕のいずれかに記載のシリカ分散液の製造方法。

（式中、Ｒ³、Ｒ⁴、ｎは前記と同様である。）
〔１８〕
工程（Ａ２）において、（メタ）アクリル基を有する有機ケイ素化合物が、下記式（４）で表される化合物を含む〔１３〕〜〔１５〕のいずれかに記載のシリカ分散液の製造方法。

（式中、Ｒ³、Ｒ⁴、ｎは前記と同様である。）
〔１９〕
工程（Ａ２）において、更に下記式（５）で表されるシラン化合物の１種以上を添加して、工程（Ａ１）で得られたゾルゲルシリカ粒子の表面を処理する〔１３〕〜〔１８〕のいずれかに記載のシリカ分散液の製造方法。
Ｒ⁵ ₃ＳｉＹ （５）
（式中、Ｒ⁵は炭素原子数１〜２０の１価炭化水素基であり、Ｙは水酸基、炭素原子数１〜６のアルコキシ基、アミノ基、アシルオキシ基又はハロゲン原子である。）
〔２０〕
工程（Ａ３）で得られたシリカ分散液のナトリウム含有量が１００ｐｐｍ以下である〔１３〕〜〔１９〕のいずれかに記載のシリカ分散液の製造方法。 Accordingly, the present invention provides the following silica dispersion, a method for producing the same, a photocurable composition using the same, and a cured product thereof.
[1]
In a liquid compound having a radical polymerizable unsaturated bond, a silica dispersion in which surface-treated sol-gel silica particles are dispersed,
The surface-treated sol-gel silica is a surface-treated product of at least one of an organosilicon compound having a (meth) acrylic group represented by the following formula (1) and a (partly) hydrolyzed condensate thereof, and is based on volume. In a dispersion containing sol-gel silica particles having a median diameter in the particle size distribution of 1 to 60 nm, an organosilicon compound having a (meth) acrylic group represented by the following formula (1) based on 100 parts by mass of the sol-gel silica particles A silica dispersion which is a surface-treated product to which 10 parts by mass or more is added.

(Wherein, R ¹ is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R ² is an alkylene group having 1 to 20 carbon atoms, and R ³ are each independently a hydrogen atom or 1 carbon atom. And R ⁴ is each independently a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom, and n is an integer of 1 to 3.)
[2]
The ratio (Q ⁴ / Q) of the peak area (Q ⁴ ) at −105 to −130 ppm to the peak area (Q) at −80 to −130 ppm in the ²⁹ Si-NMR spectrum of the sol-gel silica particles is 0.8 or less [ 1] The silica dispersion according to the above.
[3]
The silica dispersion according to [1] or [2], wherein the value of D90 / D10 in the volume-based particle size distribution of the sol-gel silica particles is 3.2 or less.
[4]
The silica dispersion according to any one of [1] to [3], wherein the organosilicon compound having a (meth) acryl group contains a compound represented by the following formula (2).

(In the formula, R ³ , R ⁴ , and n are the same as described above.)
[5]
The silica dispersion according to any one of [1] to [3], wherein the organosilicon compound having a (meth) acrylic group contains a compound represented by the following formula (3).

(In the formula, R ³ , R ⁴ , and n are the same as described above.)
[6]
The silica dispersion according to any one of [1] to [3], wherein the organosilicon compound having a (meth) acrylic group contains a compound represented by the following formula (4).

(In the formula, R ³ , R ⁴ , and n are the same as described above.)
[7]
The silica dispersion according to any one of [1] to [6], wherein the surface-treated sol-gel silica particles are further surface-treated with one or more silane compounds represented by the following formula (5).
R ⁵ ₃ SiY ⁽⁵⁾
(In the formula, R ⁵ is a monovalent hydrocarbon group having 1 to 20 carbon atoms, and Y is a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an amino group, an acyloxy group, or a halogen atom.)
[8]
The liquid compound having a radical polymerizable unsaturated bond includes at least one of 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, and dipentaerythritol hexaacrylate [1] to [7]. The silica dispersion according to the above.
[9]
The silica dispersion according to any one of [1] to [8], containing the surface-treated sol-gel silica particles in an amount of 5 to 250 parts by mass based on 100 parts by mass of the liquid compound having a radical polymerizable unsaturated bond.
[10]
The silica dispersion according to any one of [1] to [9], wherein the sodium content is 100 ppm or less.
[11]
A photocurable composition comprising the silica dispersion according to any one of [1] to [10].
[12]
A cured product obtained by curing the photocurable composition according to [11].
[13]
(A1) Hydrolysis / condensation of a silane compound represented by the following formula (6), its (partially) hydrolyzed condensate or a mixture thereof in a mixed solvent of a hydrophilic organic solvent and water in the presence of a basic substance Obtaining an organic solvent / water dispersion of sol-gel silica particles by doing
Si (OR ⁶ ) ₄ (6)
(However, R ⁶ is each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 6 carbon atoms.)
(A2) In a dispersion of the sol-gel silica particles, an organosilicon compound having a (meth) acrylic group represented by the following formula (1) based on 100 parts by mass of the sol-gel silica particles, and a (partially) hydrolyzed condensate thereof Adding at least one of the above by 10 parts by mass or more, treating the surface of the sol-gel silica particles,

(Wherein, R ¹ is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R ² is an alkylene group having 1 to 20 carbon atoms, and R ³ are each independently a hydrogen atom or 1 carbon atom. And R ⁴ is each independently a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom, and n is an integer of 1 to 3.)
(A3) A liquid compound having a radical polymerizable unsaturated bond is added to the dispersion liquid of the sol-gel silica particles surface-treated with the organosilicon compound having a (meth) acrylic group obtained in the step (A2). Removing the hydrophilic organic solvent, water and, in some cases, the alcohol produced by the surface treatment by distillation.
[14]
The ratio (Q ⁴ / Q) of the peak area (Q ⁴ ) of −105 to −130 ppm to the peak area (Q) of −80 to −130 ppm in the ²⁹ Si-NMR spectrum of the sol-gel silica particles obtained in the step (A1). [13] The process for producing a silica dispersion according to [13], wherein
[15]
The method for producing a silica dispersion according to [13] or [14], wherein the value of D90 / D10 in the particle size distribution of the sol-gel silica particles obtained in step (A1) is 3.2 or less.
[16]
The process for producing a silica dispersion according to any one of [13] to [15], wherein in the step (A2), the organosilicon compound having a (meth) acrylic group contains a compound represented by the following formula (2).

(In the formula, R ³ , R ⁴ , and n are the same as described above.)
[17]
The process for producing a silica dispersion according to any one of [13] to [15], wherein in the step (A2), the organosilicon compound having a (meth) acrylic group contains a compound represented by the following formula (3).

(In the formula, R ³ , R ⁴ , and n are the same as described above.)
[18]
The method for producing a silica dispersion according to any one of [13] to [15], wherein in the step (A2), the organosilicon compound having a (meth) acrylic group contains a compound represented by the following formula (4).

(In the formula, R ³ , R ⁴ , and n are the same as described above.)
[19]
In step (A2), one or more silane compounds represented by the following formula (5) are further added to treat the surface of the sol-gel silica particles obtained in step (A1) [13] to [18]. The method for producing a silica dispersion according to any one of the above.
R ⁵ ₃ SiY ⁽⁵⁾
(In the formula, R ⁵ is a monovalent hydrocarbon group having 1 to 20 carbon atoms, and Y is a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an amino group, an acyloxy group, or a halogen atom.)
[20]
The method for producing a silica dispersion according to any one of [13] to [19], wherein the silica content of the silica dispersion obtained in the step (A3) is 100 ppm or less.

According to the present invention, it is possible to provide a silica dispersion liquid that provides a cured film having a high scratch resistance improving effect. Therefore, the silica dispersion liquid is added to various photocurable compositions such as a photocurable paint. Thus, a cured film having excellent scratch resistance can be obtained.
In addition, since the silica dispersion of the present invention does not contain an alkali metal component as an impurity in the production method, a cured film of a composition containing the same has no fear of contamination by an alkali metal and unexpected performance deterioration. And the like, and further improvement in scratch resistance.
In addition, in the steps from the preparation of the silica particles to the surface treatment thereof, there is no step of replacing the aqueous solvent with the organic solvent, and the particles can be produced by simpler steps.
Furthermore, since the decomposition and self-condensation of the surface treatment agent due to the reaction between the organosilicon compound having a (meth) acryl group, which is the surface treatment agent, and water are suppressed, the surface treatment effect can be more effectively exhibited. It becomes possible.

  It is known that the substitution of the (meth) acryl group on the silica surface at a high density lowers the mobility of the (meth) acryl group and shows higher reactivity than usual, but is obtained in the present invention. Silica exhibits very high reactivity when the (meth) acryl group is substituted on the surface of silica particles at high density. Therefore, the photocurable composition containing the silica dispersion of the present invention contains a photoinitiating catalyst. A cured film can be formed without any problem. Since a photoreaction initiator may cause a decrease in weather resistance of the cured film, a decrease in abrasion resistance, and yellowing, a photocurable film having a high scratch resistance can be obtained without adding a photoreaction initiator. The silica dispersion of the present invention that gives a curable composition is useful as a raw material of a photocurable composition such as a hard coat paint.

Hereinafter, the present invention will be described in detail.
[Silica dispersion]
The silica dispersion of the present invention is prepared by adding at least one of the organosilicon compound represented by the above formula (1) and a (partially) hydrolyzed condensate to a liquid compound having a radical polymerizable unsaturated bond. It is a silica dispersion in which the treated sol-gel silica particles are dispersed.

  In the present invention, the term “dispersion liquid” refers to a state of stable dispersion (colloidal dispersion) in which particles do not settle with time, unless otherwise specified. A stable dispersion state may occur when the Brownian velocity of a particle becomes faster than the sedimentation velocity due to its own weight. On the other hand, since the sedimentation speed of the particles is low in the viscous liquid, it takes a long time to determine the presence or absence of the aggregated and sedimented particles. In such a case, it is preferable to efficiently determine the presence or absence of settled particles by applying a centrifugal force using a centrifuge to promote the settling of the particles. This makes it possible to confirm whether or not the state is a stable dispersion state.

<Silica particles>
The silica particles of the present invention are sol-gel silica particles substantially composed of SiO ₂ units obtained by hydrolyzing and condensing a tetrafunctional silane compound and / or a (partly) hydrolytic condensation product thereof.

In the present invention, the sol-gel silica particles “substantially consist of SiO ₂ units” means that the particles are basically composed of SiO ₂ units, but are not necessarily composed of only these units. It means that the surface has many silanol groups as is generally known. In some cases, the hydrolyzable group (hydrocarbyloxy group) derived from the tetrafunctional silane compound as a raw material and / or a partial hydrolytic condensation product thereof is partially converted to a silanol group without being converted to a small amount. It means that it may remain on the surface or inside.

Particle Size The primary particle size of the silica particles can be determined by directly observing the shape of the particles using an electron microscope or from the surface area of the particles determined by a gas adsorption method. The secondary particle size can be determined by a dynamic light scattering method using laser light. Except when there is no aggregation of the particles and the primary particle diameter and the secondary particle diameter are almost equal, the transparency of the dispersion liquid containing the particles and the cured product is greatly affected by the secondary particle diameter. The secondary particle diameter determined by a dynamic light scattering method using a laser beam is used as the particle diameter of. As a measuring device using the dynamic light scattering method, Nanotrac UPA-EX150 (manufactured by Nikkiso Co., Ltd.) or the like can be used.

  The silica particles used in the present invention have a median diameter (D50) of 1 to 60 nm, preferably 5 to 40 nm, particularly preferably 10 to 30 nm, which is a particle diameter at which 50% by volume is cumulative in the volume-based particle size distribution. is there. D50 of 1 nm or more is preferable because the scratch resistance is good, and D50 of 60 nm or less is preferable because the transparency of the cured film when the silica dispersion is added to the photocurable composition becomes good. .

  In the sol-gel silica particles of the present invention, in the volume-based particle size distribution, when the particle diameter at which the cumulative volume becomes 10% by volume is D10 and the particle size at which the cumulative volume becomes 90% by volume is D90 from the smaller particle diameter side, D90 / D10 is satisfied. The value is preferably 3.2 or less, more preferably 3 or less. The lower limit is not particularly limited, but is preferably 1 or more. When D90 / D10 is 3.2 or less, it indicates that the particle size distribution is narrow. Such a particle size distribution is preferable in that it is easy to control the transparency and fluidity of the dispersion, and when a silica dispersion is added to the photocurable composition, it is regularly arranged in the cured film. The incorporation of particles having high properties is preferable in that the scratch resistance and crack resistance of the cured film are improved.

  The sol-gel silica of the present invention uses a silane having a small number of carbon atoms of an alkoxy group of a raw material tetraalkoxysilane used for hydrolytic condensation, using an alcohol having a small number of carbon atoms as a solvent, increasing the hydrolysis temperature, tetraalkoxy. The particle size can be appropriately adjusted by changing the reaction conditions such as lowering the concentration of the silane at the time of hydrolysis and lowering the concentration of the hydrolysis catalyst.

-NMR peak area ratio Q ⁴ / Q
As described above, the silica particles of the present invention use sol-gel method silica having a small particle diameter obtained by hydrolysis of a tetrafunctional silane compound such as tetraalkoxysilane, and ion-exchange an aqueous sodium silicate solution. It is distinguished from the silica dispersion using the obtained ion exchange silica.

As a method for distinguishing the silica in the dispersion from the sol-gel method silica and the ion-exchange method silica, Q in the siloxane unit (tetrafunctional siloxane unit including Q ^{1 to} Q ⁴ units represented by the following formulas) ^It is effective to compare the ratio of ⁴ units and the alkali metal component.

（Ｘは、水素原子又は炭素原子数１〜４のアルキル基である。）

(X is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.)

In the present invention, the ratio of the Q ⁴ unit to the entire Q unit of the siloxane can be determined by ²⁹ Si-NMR measurement, and the peak area of −105 to −130 ppm relative to the peak area (Q) of −80 to −130 ppm ( Q ⁴ ) (Q ⁴ / Q). Since the sol-gel method silica used in the present invention has many unreacted alkoxy groups and silanol groups inside the silica, Q ⁴ / Q usually takes a value of 0.8 or less. (Q ⁴ / Q) is more preferably from 0.2 to 0.8, further preferably from 0.55 to 0.75. When (Q ⁴ / Q) is from 0.2 to 0.8, the curable composition containing the silica dispersion of the present invention has good scratch resistance.

  In the present invention, the peak area (integral value) means the area when the signal intensity is plotted against the chemical shift value (parts per million (ppm)). The quadrature is preferably provided with a threshold according to a specific reference S / N ratio. The S / N ratio is preferably 5 or more, more preferably 10 or more, and still more preferably 20 or more. If it is less than 5, the baseline becomes thicker and the accuracy of integration becomes worse, which may not be preferable. The integration may be obtained by a Simpson method using an electronic computer, or may be obtained by cutting a print medium having a uniform planar density displaying a spectrum into a spectral shape and measuring the mass.

²⁹ Si nuclear magnetic resonance spectroscopy may be performed on either a solid or a liquid.However, in solid-state nuclear magnetic resonance spectroscopy, it is necessary to dry the sample as a pretreatment, and the silicon in the sample is not necessarily dried. It does not necessarily reflect the connection state. Therefore, it is preferable to confirm by nuclear magnetic resonance spectroscopy in a liquid state. At this time, since the ²⁹ Si nucleus has a negative gyromagnetic ratio (γ _B ), the nuclear Overhauser effect is reversed, and the nuclear magnetic relaxation existing around the resonance nucleus is suppressed. Therefore, it is preferable that the measurement conditions be such that the negative nuclear Overhauser effect is not remarkable.

In the case of pulse-Fourier transform nuclear magnetic resonance, this problem can be solved by using an appropriate pulse sequence. For example, it is preferable to use an off-resonance type pulse sequence. In the liquid ²⁹ Si nuclear magnetic resonance spectroscopy, it is preferable that the measurement is performed using a material containing no silicon for the sample tube and the probe. Polytetrafluoroethylene (Teflon (registered trademark)) can be exemplified as a material usable for nuclear magnetic resonance spectroscopy containing no silicon. In liquid ²⁹ Si nuclear magnetic resonance spectroscopy, an appropriate moderating agent can be used to shorten the measurement time. As the moderating agent, known reagents (for example, Organometallics, 2008, Vol. 27, No. 4, pp. 500-502, and references therein) can be used. In particular, chromium (III) acetylacetonate is excellent in solubility in an organic solvent and does not cause aggregation of titanium oxide. For example, by using a few drops of a solution obtained by dissolving chromium (III) acetylacetonate in deuterated chloroform (chloroform-d ₃ ) at a concentration of about 1 mol · dm ⁻³ , the relaxation effect and the deuterium lock effect can be reduced. It is preferable because both can be obtained.

The notation of the resonance magnetic field can be expressed as a difference from the resonance magnetic field based on the resonance of the ²⁹ Si nucleus of tetramethylsilane in parts per million (ppm). If according to this notation, Q units -80 to-130 ppm, T unit (XSiO _3/2 (X is as defined above. Hereinafter, the same.)) Is -30 to-80 ppm, D units (X ₂ SiO _2/2 ) can be detected in the range of -10 to -30 ppm, and the M unit (X ₃ SiO _1/2 ) can be detected in the range of -10 to 15 ppm. A notational negative value indicates that the resonance magnetic field has a difference on the higher magnetic field side than the reference line. The width of the resonance line depends on the strength of the magnetic field of the nuclear magnetic resonance apparatus used for the measurement, and the preferable range of the resonance line is a value when a magnetic field of 11.75 T (tesla) is applied as an example. The magnetic field that can be used in the nuclear magnetic resonance apparatus is preferably 5T or more and 20T or less, more preferably 8T or more and 15T or less, and still more preferably 10T or more and 13T or less. When the magnetic field is less than 5T, the measurement may be difficult due to a small S / N ratio, and when the magnetic field exceeds 20T, the size of the resonance device may be large and the measurement may be difficult.

  The NMR measurement conditions in the present invention are as described below.

<Alkali metal component in silica dispersion>
From the viewpoint of improving the scratch resistance, the silica dispersion of the present invention preferably has a small alkali metal content such as sodium, particularly preferably 100 ppm or less, more preferably 50 ppm or less, still more preferably 20 ppm or less, and still more preferably 10 ppm or less. Is most preferred. The method for measuring the content of the alkali metal component is also as described later.

<Organosilicon compound having (meth) acrylic group>
The surface of the silica particles used in the present invention is coated with an organosilicon compound represented by the following formula (1). That is, the organosilicon compound having the (meth) acrylic group is (partially) hydrolyzed into a silanol compound, and the silica particles are treated with the silanol compound and subjected to a dehydration condensation reaction with the silanol group on the silica particle surface, Alternatively, the dispersibility of silica particles in a liquid acrylic compound described below is improved by subjecting the alkoxy group of the compound and a silanol group on the silica surface to a dealcoholation condensation reaction using the compound without hydrolysis. Can be.

In the formula (1), R ¹ is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. The alkyl group may be linear, branched, or cyclic, and includes, for example, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, and a pentyl group. , A hexyl group, a cyclopentyl group, a cyclohexyl group, and the like, but those having 1 to 3 carbon atoms are preferable, and in consideration of the balance between storage stability and photopolymerizability, R ¹ is more preferably a hydrogen atom or a methyl group. Preferably, a methyl group is more preferable.

R ² is an alkylene group having 1 to 20 carbon atoms. The alkylene group may be linear, branched or cyclic, and includes, for example, a methylene group, an ethylene group, a trimethylene group, a propylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, a heptamethylene group, and an octamethylene group. , A nonamethylene group, a cyclohexylene group, and the like. When the number of carbon atoms is large (8 or more carbon atoms), the fluidity and storage stability of the silica dispersion become particularly good, and when the number of carbon atoms is small ( When the number of carbon atoms is 3 or less, it is particularly effective in improving the scratch resistance when introduced into the cured film.

R ³ is each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. Examples of the alkyl group include the same as those exemplified for R ¹ , but those having 1 to 3 carbon atoms are preferred, and among these, a methyl group having small steric hindrance does not inhibit the reaction with the silica surface. Especially preferred for.

R ⁴ is each independently a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom. Examples of the halogen atom include fluorine, chlorine, bromine, and iodine atoms. Examples of the alkoxy group include a methoxy group, an ethoxy group, and an n-propoxy group. Among these, an alkoxy group is preferable, and a methoxy group is particularly preferable in consideration of reactivity with the silica surface.

n is an integer of 1 to 3, preferably 2 or 3, and most preferably 3, in consideration of reactivity with the silica surface. When n is 2 or 3 in the formula (1), R ⁴ may be the same group or different groups.

（式中、Ｒ³、Ｒ⁴、ｎは前記と同様である。） As the organosilicon compound having a (meth) acryl group, compounds represented by the following formulas (2) to (4) are preferable.

(In the formula, R ³ , R ⁴ , and n are the same as described above.)

Specific examples of the organosilicon compound having a (meth) acryl group include, for example,
1- (meth) acryloyloxymethylmethyldimethoxysilane,
1- (meth) acryloyloxymethyltrimethoxysilane,
1- (meth) acryloyloxymethylmethyldiethoxysilane,
1- (meth) acryloyloxymethyltriethoxysilane,
1- (meth) acryloyloxymethyltrihydroxysilane,
1- (meth) acryloyloxymethyldimethoxysilane,
1- (meth) acryloyloxymethyltylpropyldimethoxysilane,
2- (meth) acryloyloxyethylmethyldimethoxysilane,
2- (meth) acryloyloxyethyltrimethoxysilane,
2- (meth) acryloyloxyethylmethyldiethoxysilane,
2- (meth) acryloyloxyethyltriethoxysilane,
2- (meth) acryloyloxyethyltrihydroxysilane,
2- (meth) acryloyloxyethylethyldimethoxysilane,
2- (meth) acryloyloxyethylpropyldimethoxysilane,
3- (meth) acryloyloxypropylmethyldimethoxysilane,
3- (meth) acryloyloxypropyltrimethoxysilane,
3- (meth) acryloyloxypropylmethyldiethoxysilane,
3- (meth) acryloyloxypropyltriethoxysilane,
3- (meth) acryloyloxypropyltrihydroxysilane,
3- (meth) acryloyloxypropylethyldimethoxysilane,
3- (meth) acryloyloxypropylpropyldimethoxysilane,
4- (meth) acryloyloxybutylmethyldimethoxysilane,
4- (meth) acryloyloxybutyltrimethoxysilane,
4- (meth) acryloyloxybutylmethyldiethoxysilane,
4- (meth) acryloyloxybutyltriethoxysilane,
4- (meth) acryloyloxybutyltrihydroxysilane,
4- (meth) acryloyloxybutylethyldimethoxysilane,
4- (meth) acryloyloxybutylpropyldimethoxysilane,
5- (meth) acryloyloxypentylmethyldimethoxysilane,
5- (meth) acryloyloxypentyltrimethoxysilane,
5- (meth) acryloyloxypentylmethyldiethoxysilane,
5- (meth) acryloyloxypentyltriethoxysilane,
5- (meth) acryloyloxypentyltrihydroxysilane,
5- (meth) acryloyloxypentylethyldimethoxysilane,
5- (meth) acryloyloxypentylpropyldimethoxysilane,
6- (meth) acryloyloxyhexylmethyldimethoxysilane,
6- (meth) acryloyloxyhexyltrimethoxysilane,
6- (meth) acryloyloxyhexylmethyldiethoxysilane,
6- (meth) acryloyloxyhexyltriethoxysilane,
6- (meth) acryloyloxyhexyltrihydroxysilane,
6- (meth) acryloyloxyhexylethyldimethoxysilane,
6- (meth) acryloyloxyhexylpropyldimethoxysilane,
7- (meth) acryloyloxyheptylmethyldimethoxysilane,
7- (meth) acryloyloxyheptyltrimethoxysilane,
7- (meth) acryloyloxyheptylmethyldiethoxysilane,
7- (meth) acryloyloxyheptyltriethoxysilane,
7- (meth) acryloyloxyheptyltrihydroxysilane,
7- (meth) acryloyloxyheptylethyldimethoxysilane,
7- (meth) acryloyloxyheptylpropyldimethoxysilane,
8- (meth) acryloyloxyoctylmethyldimethoxysilane,
8- (meth) acryloyloxyoctyltrimethoxysilane,
8- (meth) acryloyloxyoctylmethyldiethoxysilane,
8- (meth) acryloyloxyoctyltriethoxysilane,
8- (meth) acryloyloxyoctyltrihydroxysilane,
8- (meth) acryloyloxyoctylethyldimethoxysilane,
8- (meth) acryloyloxyoctylpropyldimethoxysilane,
9- (meth) acryloyloxynonylmethyldimethoxysilane,
9- (meth) acryloyloxynonyltrimethoxysilane,
9- (meth) acryloyloxynonylmethyldiethoxysilane,
9- (meth) acryloyloxynonyltriethoxysilane,
9- (meth) acryloyloxynonyltrihydroxysilane,
9- (meth) acryloyloxynonylethyldimethoxysilane,
9- (meth) acryloyloxynonylpropyldimethoxysilane,
10- (meth) acryloyloxydecylmethyldimethoxysilane,
10- (meth) acryloyloxydecyltrimethoxysilane,
10- (meth) acryloyloxydecylmethyldiethoxysilane,
10- (meth) acryloyloxydecyltriethoxysilane,
10- (meth) acryloyloxydecyltrihydroxysilane,
10- (meth) acryloyloxydecylethyldimethoxysilane,
10- (meth) acryloyloxydecylpropyldimethoxysilane,
11- (meth) acryloyloxyundecylmethyldimethoxysilane,
11- (meth) acryloyloxyundecyltrimethoxysilane,
11- (meth) acryloyloxyundecylmethyldiethoxysilane,
11- (meth) acryloyloxyundecyltriethoxysilane,
11- (meth) acryloyloxyundecyltrihydroxysilane,
11- (meth) acryloyloxyundecylethyldimethoxysilane,
11- (meth) acryloyloxyundecylpropyldimethoxysilane,
12- (meth) acryloyloxidedecylmethyldimethoxysilane,
12- (meth) acryloyloxidedecyltrimethoxysilane,
12- (meth) acryloyloxidedecylmethyldiethoxysilane,
12- (meth) acryloyloxidedecyltriethoxysilane,
12- (meth) acryloyloxidedecyltrihydroxysilane,
12- (meth) acryloyloxidedecylethyldimethoxysilane,
12- (meth) acryloyloxidedecylpropyldimethoxysilane,
13- (meth) acryloyloxytridecylmethyldimethoxysilane,
13- (meth) acryloyloxytridecyltrimethoxysilane,
13- (meth) acryloyloxytridecylmethyldiethoxysilane,
13- (meth) acryloyloxytridecyltriethoxysilane,
13- (meth) acryloyloxytridecyltrihydroxysilane,
13- (meth) acryloyloxytridecylethyldimethoxysilane,
13- (meth) acryloyloxytridecylpropyldimethoxysilane,
14- (meth) acryloyloxytetradecylmethyldimethoxysilane,
14- (meth) acryloyloxytetradecyltrimethoxysilane,
14- (meth) acryloyloxytetradecylmethyldiethoxysilane,
14- (meth) acryloyloxytetradecyltriethoxysilane,
14- (meth) acryloyloxytetradecyltrihydroxysilane,
14- (meth) acryloyloxytetradecylethyldimethoxysilane,
14- (meth) acryloyloxytetradecylpropyldimethoxysilane and the like. These may be used alone or in combination of two or more.

  Among these, 3- (meth) acryloyloxypropyltrimethoxysilane, 8- (meth) acryloyloxyoctyltrimethoxysilane, 1- (meta) are particularly preferred from the viewpoints of improving the scratch resistance of the coating film and availability. Acryloyloxymethyltrimethoxysilane is preferred.

  The addition amount of the organosilicon compound having a (meth) acrylic group is to improve the abrasion resistance by increasing the crosslink density, to improve the dispersibility of silica particles in a liquid compound having a radical polymerizable unsaturated bond, and to improve the flowability. From the viewpoint, it is necessary to add 10 parts by mass or more to 100 parts by mass of the silica particles, and it is preferable to add 15 parts by mass or more. In addition, in order to suppress a decrease in the hardness of the cured film due to the remaining unreacted organosilicon compound, the addition amount is preferably 30 parts by mass or less, more preferably 20 parts by mass or less.

<Other silane compounds for surface treatment>
The silica particles used in the present invention may be further coated with one or more silane compounds represented by the following formula (5).
R ⁵ ₃ SiY ⁽⁵⁾

In the above formula (5), R ⁵ is a monovalent hydrocarbon group having 1 to 20 carbon atoms, preferably a monovalent hydrocarbon group having 1 to 4 carbon atoms, particularly preferably 1 to 2 carbon atoms. Examples of the monovalent hydrocarbon group represented by R ⁵ include an alkyl group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, and an n-butyl group. And an n-propyl group, particularly preferably a methyl group and an ethyl group. Further, some or all of the hydrogen atoms of these monovalent hydrocarbon groups may be substituted with halogen atoms such as fluorine, chlorine and bromine, preferably with fluorine atoms.

  Y is a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an amino group, an acyloxy group or a halogen atom. Examples of the alkoxy group include a methoxy group, an ethoxy group, and an n-propoxy group. Examples of the amino group include an N, N-dimethylamino group and a group of an N, N-diethylamino group. And the same as the halogen atom. Among these, a hydroxyl group and a methoxy group are preferable.

  Specific examples of the compound represented by the formula (5) include monosilanol compounds such as trimethylsilanol and triethylsilanol, monochlorosilanes such as trimethylchlorosilane and triethylchlorosilane, monoalkoxysilanes such as trimethylmethoxysilane and trimethylethoxysilane, and trimethylsilyldimethyl. Monoamine silanes such as amine and trimethylsilyldiethylamine, and monoacyloxysilanes such as trimethylacetoxysilane, preferably trimethylsilanol, trimethylmethoxysilane and trimethylsilyldiethylamine, particularly preferably trimethylsilanol and trimethylmethoxysilane. These may be used alone or in combination of two or more.

  The amount of the compound represented by the above formula (5) is preferably 1 to 20 parts by mass, more preferably 5 to 15 parts by mass, particularly preferably 8 to 12 parts by mass with respect to 100 parts by mass of the untreated sol-gel silica particles. Parts by weight. When the addition amount is 20 parts by mass or less, the remaining of the unreacted silane compound can be suppressed, and the scratch resistance when the silica dispersion is cured as a photocurable composition becomes favorable, which is preferable. Is preferably 1 part by mass or more, because the storage stability of the silica dispersion is improved.

<Liquid compound having radical polymerizable unsaturated bond>
The liquid compound having a radically polymerizable unsaturated bond, which is a dispersion medium in the silica dispersion of the present invention, is not particularly limited as long as it is a monomer or oligomer having one or more radically polymerizable unsaturated bonds and capable of undergoing a curing reaction. For example, (meth) acrylate compounds, styrene compounds, maleimide compounds, fumaric acid ester compounds and the like can be mentioned. These may be used alone or in combination of two or more. Among these, (meth) acrylate compounds are preferred from the viewpoint of excellent polymerizability and easy curing even at around room temperature. The boiling point at atmospheric pressure is preferably 90 ° C. or more, more preferably 120 ° C. or more, from the viewpoint of easy removal of volatile by-products.

The (meth) acrylate compound may be either a monofunctional (meth) acrylate or a polyfunctional (meth) acrylate.
Examples of the monofunctional (meth) acrylate include ethyl acrylate, butyl acrylate, ethylhexyl acrylate, 2-hydroxyethyl acrylate, isobornyl acrylate, and tetrahydrofurfuryl acrylate.

  Examples of the polyfunctional (meth) acrylate include 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate (HDDA), tetraethylene glycol diacrylate, neopentyl glycol diacrylate, ethylene glycol diacrylate, and polyethylene. Glycol (n = 2-15) diacrylate, polypropylene glycol (n = 2-15) diacrylate, polybutylene glycol (n = 2-15) diacrylate, 2,2-bis (4-acryloxyethoxyphenyl) propane 2,2-bis (4-acryloxydiethoxyphenyl) propane, trimethylolpropane diacrylate, bis (2-acryloxyethyl) -hydroxyethyl-isocyanurate, trimethylolpropane triacrylate (TMPTA), tris (2-acryloxyethyl) isocyanurate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate (DPHA), modified with caprolactone Dipentaerythritol hexaacrylate (acrylated product of an adduct of dipentaerythritol and ε-caprolactone), caprolactone-modified dipentaerythritol hydroxypentaacrylate, ditrimethylolpropanetetraacrylate, N-vinylpyrrolidone, aliphatic urethane acrylate oligomer, aliphatic And polyester acrylate oligomers. Among these, 1,6-hexanediol diacrylate (HDDA), trimethylolpropane triacrylate, and dipentaerythritol hexaacrylate are particularly preferred.

  In the silica dispersion of the present invention, the surface-treated silica particles are preferably dispersed in 5 to 250 parts by mass, preferably 10 to 200 parts by mass, based on 100 parts by mass of the liquid compound having a radical polymerizable unsaturated bond. Is more preferably 25 to 150 parts by mass, and most preferably 50 to 125 parts by mass. When the silica is dispersed in an amount of 5 parts by mass or more, the effect of improving the scratch resistance when added to the photocurable composition becomes good, and when the silica is dispersed in an amount of 250 parts by mass or less, the fluidity of the dispersion is good. Become.

  The silica dispersion of the present invention may contain a base neutralizer, an acid neutralizer, a base adsorbent, an acid adsorbent, a polymerization inhibitor, an antioxidant, an ultraviolet absorber, and a light stabilizer as long as the effects of the present invention are not impaired. Additives such as an agent may be added to enhance storage stability.

<Method for producing silica dispersion>
Next, an example of the method for producing the silica dispersion of the present invention will be described in detail.
The surface-treated silica particles used in the present invention are hydrophobic spherical silica particles obtained by subjecting hydrophilic sol-gel silica particles to surface treatment, and the silica dispersion containing the same is subjected to the following steps (A1) to (A3):
Step (A1): synthesis step of sol-gel silica particles,
Step (A2): a sol-gel silica surface treatment step using an organosilicon compound having a (meth) acrylic group,
Step (A3): Dispersing medium replacement step,
Obtained by Hereinafter, each step will be described.

Step (A1): Step of synthesizing sol-gel silica particles In the step (A1), a silane compound represented by the following formula (6), a (partially) hydrolyzed condensate thereof, or a mixture thereof is prepared in the presence of a basic substance. This is a step of obtaining an organic solvent / water dispersion of hydrophilic sol-gel silica particles by hydrolysis and condensation in a mixed solvent of a hydrophilic organic solvent and water.
Si (OR ⁶ ) ₄ (6)

In the above formula (6), R ⁶ is each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 6 carbon atoms. The monovalent hydrocarbon group preferably has 1 to 4 carbon atoms, and particularly preferably has 1 to 2 carbon atoms. Specific examples include a methyl group, an ethyl group, an n-propyl group, and an n-butyl group. An alkyl group; an aryl group such as a phenyl group; Preferred are alkyl groups such as a methyl group, an ethyl group, an n-propyl group and an n-butyl group, and particularly preferred are a methyl group and an ethyl group.

  Specific examples of the silane compound represented by the above formula (6) include tetraalkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane and tetra-n-butoxysilane; tetraarylsilanes such as tetraphenoxysilane And the like. Of these, preferred are tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane and tetra-n-butoxysilane, and particularly preferred are tetramethoxysilane and tetraethoxysilane. In addition, examples of these hydrolysis condensates include methyl silicate, ethyl silicate and the like.

  The hydrophilic organic solvent used for hydrolyzing and condensing the silane compound may be any solvent that dissolves the silane compound represented by the formula (6) or a (partial) hydrolyzed condensate thereof and water. There is no particular limitation, for example, alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol; cellosolves such as methyl cellosolve, ethyl cellosolve, butyl cellosolve, cellosolve acetate; ketones such as acetone and methyl ethyl ketone; dioxane And ethers such as tetrahydrofuran. Of these, alcohols and cellosolves are preferred, alcohols are more preferred, and methanol and ethanol are particularly preferred. As the number of carbon atoms in the alcohol increases, the particle diameter of the resulting spherical silica particles increases. Therefore, methanol is preferred to obtain the desired silica particles having a small particle diameter.

Examples of the basic substance include ammonia, dimethylamine, diethylamine, and the like, preferably ammonia and diethylamine, and particularly preferably ammonia. After dissolving a required amount of these basic substances in water, the resulting aqueous solution (basic) may be mixed with the hydrophilic organic solvent.
The amount of water used at this time is preferably 0.5 to 5 mol per 1 mol of the total of the hydrocarbyloxy groups of the silane compound represented by the above formula (6) and / or its (partially) hydrolyzed condensate. , 0.6 to 3 mol, more preferably 0.7 to 2 mol.

  The ratio of the hydrophilic organic solvent to water is preferably 0.5 to 10, more preferably 2 to 9, and particularly preferably 3 to 8 by mass ratio. At this time, the larger the amount of the hydrophilic organic solvent, the smaller the particle size of the silica particles.

  The amount of the basic substance is 0.01 to 2 mol based on 1 mol of the total of the hydrocarbyloxy groups of the tetrafunctional silane compound represented by the general formula (6) and / or the (partly) hydrolyzed condensation product thereof. Preferably, it is 0.02 to 0.5 mol, more preferably 0.04 to 0.12 mol. At this time, the smaller the amount of the basic substance, the smaller the particle size of the silica particles.

  The hydrolysis and condensation of the silane compound represented by the formula (6) can be performed by a known method. For example, the silane compound is added to a mixture of a hydrophilic organic solvent containing a basic substance and water. Can be performed.

  After the addition of the silane compound represented by the formula (6), the reaction is preferably performed at a reaction temperature of 20 to 120 ° C. for a reaction time of 1 to 8 hours, more preferably at a reaction temperature of 20 to 100 ° C. and a reaction time of 1 to 6 hours. .

The values of the median diameter (D50), D90 / D10, and NMR peak area ratio Q ⁴ / Q of the sol-gel silica particles obtained in the step (A1) are as described above.

  The concentration of the sol-gel silica particles in the organic solvent / water dispersion in the step (A1) is preferably 5 to 30% by mass, and more preferably 10 to 25% by mass.

（式中、Ｒ¹、Ｒ²、Ｒ³、Ｒ⁴、ｎは前記と同様である。） Step (A2): silica surface treatment step In this step, the dispersion of the hydrophilic sol-gel silica particles obtained in step (A1) is treated with an organosilicon compound represented by the following formula (1) and its (part) In this step, the surface of the hydrophilic spherical silica particles is treated by adding at least one kind of hydrolytic condensate.

(In the formula, R ¹ , R ² , R ³ , R ⁴ , and n are the same as described above.)

As the organosilicon compound having a (meth) acryl group represented by the above formula (1) or a (partially) hydrolyzed condensate thereof, the same compounds as those described above can be preferably used.
The amount of use is also as described above.

The silica particles used in the present invention may be further coated with one or more compounds represented by the following formula (5).
R ⁵ ₃ SiY ⁽⁵⁾
(In the formula, R ⁵ and Y are the same as described above.)

As the compound represented by the above formula (5), the same compounds as those described above can be preferably used.
The amount of use is also as described above.

  Further, in order to promote the reaction between the surface treatment agent and the silica surface, the hydrophilic spherical silica particle dispersion used in the step (A2) preferably contains a basic substance. Examples of the basic substance include ammonia, dimethylamine, diethylamine and the like, preferably ammonia, diethylamine, and particularly preferably ammonia. When ammonia is used, the surface treatment efficiency is improved, and it can be removed by distillation, which is effective for simplifying the purification process. The content of the basic substance is preferably 1 to 5 mol, more preferably 2 to 3 mol, per 1 mol of the hydrolyzable group of the compound represented by the above formulas (1) and (5).

  The hydrolysis-condensation reaction (surface treatment) in the step (A2) can be performed under the same conditions as in the step (A1), and the reaction is preferably performed at a reaction temperature of 20 to 120 ° C. and a reaction time of 1 to 8 hours. The reaction temperature is more preferably 20 to 100 ° C. and the reaction time is 1 to 6 hours.

Step (A3): Dispersion Medium Substitution Step In this step, the dispersion of the silica particles surface-treated with the organosilicon compound having a (meth) acrylic group, obtained in the step (A2), preferably has a boiling point of 90. This is a step of adding a liquid compound having a radical polymerizable unsaturated bond at a temperature of not less than ° C., and removing the hydrophilic organic solvent, water, and, in some cases, alcohol generated by condensation by distillation.
At this time, the liquid compound having a radical polymerizable unsaturated bond may be added to the dispersion in advance, or may be added to the dispersion after the alcohol or the like has been distilled off. Preferably, distillation is performed.
By this step, a silica dispersion in which silica particles surface-treated with an organosilicon compound are dispersed in a liquid compound having a radical polymerizable unsaturated bond is obtained.

  Examples of the liquid compound having a radical polymerizable unsaturated bond include the same compounds as described above, and preferred examples thereof are also as described above.

  Examples of the method for distilling off the volatile organic products such as the hydrophilic organic solvent, water, and alcohol generated by the condensation include distillation at atmospheric pressure and distillation under reduced pressure, but distillation under reduced pressure is preferred. When heating is performed in vacuum distillation, the temperature is preferably from 30 to 100C, more preferably from 40 to 80C, most preferably from 50 to 70C. Heating to 30 ° C. or higher is preferable because the time required for distilling off the solvent can be shortened. Heating to 100 ° C. or lower is preferable because polymerization of the acrylic compound by heat and transesterification between the solvent and the acrylic moiety are performed. Can be suppressed, and the abrasion resistance when added to the photocurable composition may be improved.

  The amount of the liquid compound to be added is not particularly limited as long as the silica concentration in the finally obtained dispersion falls within the above-mentioned range. The ratio of the silica particles to the liquid compound having a radical polymerizable unsaturated bond in the silica dispersion obtained in the step (A3) is as described above.

(Photocurable composition)
In the present invention, the above silica dispersion can be used as it is as a photocurable composition. Further, if necessary, additives such as a photoreaction initiator, a polymerization inhibitor, an antioxidant, an ultraviolet absorber, and a light stabilizer may be added to the silica dispersion within a range that does not impair the effects of the present invention. Thus, a photocurable composition having excellent scratch resistance can be obtained.

<Photoinitiator>
The photoreaction initiator excites by receiving light, applies excitation energy to the siloxane containing a (meth) acryloxy group, and starts a curing reaction by irradiation with ultraviolet rays.
From the viewpoint of reactivity, photoreaction initiators are acetophenone and its derivatives, benzophenone and its derivatives, o-benzoyl benzoate, benzoin and benzoin ether and its derivatives, xanthone and its derivatives, disulfide compounds, quinone compounds, and halogenated compounds. Examples include hydrocarbons, amines, and organic peroxides. From the viewpoint of compatibility and stability, it contains a substituted or unsubstituted benzoyl group such as acetophenone and its derivatives, benzophenone and its derivatives, o-benzoyl benzoate, benzoin and benzoin ether and its derivatives, xanthones and its derivatives. Compounds or organic peroxides are more preferred.

  Specific examples of the photoreaction initiator include acetophenone, propiophenone, 2-hydroxy-2-methylpropiophenone, 2,2-dimethoxy-1,2-diphenylethan-1-one (IRGACURE 651: manufactured by BASF) ), 2-hydroxy-2-methyl-1-phenyl-propan-1-one (DAROCUR 1173: manufactured by BASF), 1-hydroxy-cyclohexyl-phenyl-ketone (IRGACURE 184: manufactured by BASF), 1- [4 -(2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one (IRGACURE 2959: BASF), 2-hydroxy-1- {4- [4- (2- (Hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propane 1-one (IRGACURE 127: BASF), 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one (IRGACURE 907: BASF), 2-benzyl-2-dimethyl Amino- (4-morpholinophenyl) -butanone-1 (IRGACURE 369: BASF), 2- (dimethylamino) -2-[(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) ) Phenyl] -1-butanone (IRGACURE 379: BASF); 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (LUCIRIN TPO: BASF), bis (2,4,6-trimethylbenzoyl) -Phenylphosphine oxide (IRGACURE 819: BASF) 1,2-octanedione, 1- [4- (phenylthio)-, 2- (O-benzoyloxime)] (IRGACURE OX01: manufactured by BASF), ethanone, 1- [9-ethyl-6- (2-Methylbenzoyl) -9H-carbazol-3-yl]-, 1- (O-acetyloxime) (IRGACURE OXE 02: manufactured by BASF); oxyphenylacetic acid, 2- [2-oxo-2-phenylacetoxy Ethoxy] ethyl ester and oxyphenylacetic acid, mixture of 2- (2-hydroxyethoxy) ethyl ester (IRGACURE 754: BASF), phenylglyoxylic acid methyl ester (DAROCUR MBF: BASF), ethyl-4- Dimethylaminobenzoate (DAROCUR EDB: BA F), 2-ethylhexyl-4-dimethylaminobenzoate (DAROCUR EHA: manufactured by BASF), bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide (CGI 403: BASF) Co., Ltd.), benzoyl peroxide, cumene peroxide and the like.

Among these photoreaction initiators, acetophenone, propiophenone, 2-hydroxy-2-methylpropiophenone, 2,2-dimethoxy-1,2-diphenylethane-1 from the viewpoint of compatibility and photoreactivity. -One, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy- 2-methyl-1-propan-1-one, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propan-1-one 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino- (4-morpholin Phenyl) -butanone-1,2- (dimethylamino) -2-[(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1-butanone; 2,4,6-trimethyl Benzoyl-diphenyl-phosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide; 1,2-octanedione, 1- [4- (phenylthio)-, 2- (O-benzoyloxime) ], Ethanone, 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl]-, 1- (O-acetyloxime); oxyphenylacetic acid, 2- [2-oxo- Preferred is a mixture of 2-phenylacetoxyethoxy] ethyl ester and oxyphenylacetic acid, 2- (2-hydroxyethoxy) ethyl ester, These can be either alone or in combination of two or more.
When the photoreaction initiator is used, the compounding amount is preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of the solid content in the photocurable composition.

<Polymerization inhibitor>
Examples of the polymerization inhibitor include hydroquinone, p-methoxyphenol, t-butylcatechol, phenothiazine, benzofuroxan, nitrosobenzene, 2-methyl-2-nitrosopropane dimer, Nt-butyl-α-phenylnitrone and the like. Can be
When the polymerization inhibitor is used, the amount added is about 100 to 10,000 ppm based on the mass of the organosilicon compound having a (meth) acryl group used in the composition.

<Antioxidant>
The antioxidant can be used to prevent oxidation of the cured product of the composition and improve weather resistance, and examples thereof include hindered amine-based and hindered phenol-based antioxidants.
Examples of the hindered amine antioxidant include, for example, N, N ′, N ″, N ′ ″-tetrakis- (4,6-bis (butyl- (N-methyl-2,2,6,6-tetramethyl) Piperidin-4-yl) amino) -triazin-2-yl) -4,7-diazadecane-1,10-diamine, dibutylamine-1,3,5-triazine.N, N'-bis- (2,2 , 6,6-Tetramethyl-4-piperidyl-1,6-hexamethylenediamine.N- (2,2,6,6-tetramethyl-4-piperidyl) butylamine polycondensate, poly [{6- ( 1,1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene (2,2,6,6-tetramethyl-4-piperi A polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol, [bis (2,2,6,6-tetramethyl-decandioate) 1 (octyloxy) -4-piperidyl) ester, reaction product of octane with 1,1-dimethylethylhydroperoxide (70% by mass)]-polypropylene (30% by mass), bis (1,2,2,6) 6-pentamethyl-4-piperidyl) [[3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl] butylmalonate, methyl 1,2,2,6,6-pentamethyl-4- Piperidyl sebacate, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate , 1- [2- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] ethyl] -4- [3- (3,5-di-tert-butyl-4-hydroxy Phenyl) propionyloxy] -2,2,6,6-tetramethylpiperidine, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, 8-acetyl-3-dodecyl-7,7,9,9 -Tetramethyl-1,3,8-triazaspiro [4.5] decane-2,4-dione; and the like, but is not limited thereto.

Examples of the hindered phenolic antioxidant include, for example, pentaeristol-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] and thiodiethylene-bis [3- (3,5 -Di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, N, N'-hexane-1,6-diylbis [ 3- (3,5-di-tert-butyl-4-hydroxyphenylpropioamide)], 3,5-bis (1,1-dimethylethyl) -4-hydroxy C7-C9 side chain alkyl ester of benzenepropanoic acid, 2,4-dimethyl-6- (1-methylpentadecyl) phenol, diethyl [[3,5-bis (1,1-di Methylethyl) -4-hydroxyphenyl] methyl] phosphonate, 3,3 ′, 3 ″, 5,5 ′, 5 ″ -hexane-tert-butyl-4-a, a ′, a ″-(mesitylene -2,4,6-tolyl) tri-p-cresol, calcium diethylbis [[[3,5-bis- (1,1-dimethylethyl) -4-hydroxyphenyl] methyl] phosphonate], 4,6- Bis (octylthiomethyl) -o-cresol, ethylenebis (oxyethylene) bis [3- (5-tert-butyl-4-hydroxy-m-tolyl) propionate], hexamethylenebis [3- (3,5- Di-tert-butyl-4-hydroxyphenyl) propionate], 1,3,5-tris (3,5-di-tert-butyl-4-hydroxybenzyl) -1,3,5-triadiate -2,4,6- (1H, 3H, 5H) -trione, the reaction product of N-phenylbenzeneamine with 2,4,4-trimethylpentene, 2,6-di-tert-butyl-4- ( 4,6-bis (octylthio) -1,3,5-triazin-2-ylamino) phenol and the like, but are not limited thereto.
The above antioxidants may be used alone or in combination of two or more.

<Ultraviolet absorber>
UV absorbers, which are light fastness stabilizers, can be used to prevent light degradation and improve weatherability, for example, benzotriazole-based, triazine-based, benzophenone-based, benzoate-based UV absorbers Is mentioned.
Examples of the ultraviolet absorber include 2,4-di-tert-butyl-6- (5-chlorobenzotriazol-2-yl) phenol and 2- (2H-benzotriazol-2-yl) -4,6- Di-tert-pentylphenol, 2- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol, methyl 3- (3- (2H-benzotriazole-2) -Yl) -5-tert-butyl-4-hydroxyphenyl) propionate / polyethylene glycol 300 reaction product, 2- (2H-benzotriazol-2-yl) -6- (linear and branched dodecyl) -4 A benzotriazole-based ultraviolet absorber such as -methylphenol, 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-[(f Triazine-based ultraviolet absorbers such as (sil) oxy] -phenol, benzophenone-based ultraviolet absorbers such as octabenzone, and 2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate; Examples include a benzoate-based ultraviolet absorber, and an organic compound in which the above components are modified with a silyl group and / or an acryl group. However, the present invention is not limited thereto.
The UV absorbers may be used alone or in combination of two or more.

<Light stabilizer>
The light stabilizer can be used to prevent photo-oxidative deterioration of the cured product, and examples thereof include benzotriazole-based, hindered amine-based, and benzoate-based compounds.
As the light stabilizer, a hindered amine is preferable. Above all, it is preferable to use a tertiary amine-containing hindered amine-based light stabilizer for improving the storage stability of the composition. As tertiary amine-containing hindered amine light stabilizers, Tinuvin 622LD, Tinuvin 144, Tinuvin 123, CHIMASSORB 119FL (all manufactured by BASF); MARKLA-57, LA-62, LA-67, LA-63 (all asahi) And light stabilizers such as SANOL LS-765, LS-292, LS-2626, LS-1114, and LS-744 (all manufactured by Sankyo Co., Ltd.).

<Other additives>
The composition of the present invention, in addition to the above additives, if necessary, a silicone resin, a leveling agent, a thickener, a pigment, a dye, a metal powder, a heat ray reflection / absorption imparting agent, a flexibility imparting agent, Other additives such as an antistatic agent, an antifouling agent, and a water repellency agent can be added within a range that does not adversely affect the object and effects of the present invention. For example, as a leveling agent, "KP-341" manufactured by Shin-Etsu Chemical Co., Ltd., "BYK-180" and "BYK-190" manufactured by BYK Chemie, "LE-604" manufactured by Kyoeisha Chemical Co., Ltd., and the like can be used. it can.

(Cured product)
The composition of the present invention can be cured by irradiating it with ultraviolet light in an atmosphere such as air or nitrogen. Examples of lamps in a wavelength range within which the reaction can be performed include high-pressure mercury lamps (UV-7000) and metal halide lamps (MHL-250, MHL-450, MHL-150, MHL-70) manufactured by Ushio Inc. Metal halide lamp (JM-MTL2KW) manufactured by JMtech, ultraviolet irradiation lamp (OSBL360) manufactured by Mitsubishi Electric Corporation, ultraviolet irradiation machine (UD-20-2) manufactured by Nippon Battery Co., Ltd., manufactured by Toshiba Corporation Examples include a fluorescent lamp (FL-20BLB), an H bulb, an H plus bulb, a D bulb, a Q bulb, and an M bulb manufactured by Fusion. The irradiation amount is preferably from 100 to 12,000 mJ / cm ² , more preferably from 300 to 8,000 mJ / cm ² , and still more preferably from 500 to 6,000 mJ / cm ² .

(Coated articles)
The composition of the present invention is applied to at least one surface of a substrate, directly or via at least one other layer, and cured by the above-described light irradiation to obtain a coated article having a coating formed thereon. be able to.

Examples of the substrate include, but are not particularly limited to, plastic moldings, wood products, ceramics, glass, metals, and composites thereof.
Furthermore, the surface of these substrates is treated, specifically, a chemical conversion treatment, a corona discharge treatment, a plasma treatment, a substrate treated with an acid or an alkali solution, or a surface layer different from the substrate body. It is also possible to use decorative plywood or the like which is coated with a type of paint. In particular, when a cured film comprising the above coating composition is formed on a polycarbonate substrate, it may be possible to improve the scratch resistance and weather resistance of the polycarbonate.

  Further, the surface of the substrate on which other functional layers have been formed in advance may be coated with the composition of the present invention. Other functional layers include a primer layer, a rust-proof layer, a gas barrier layer, a waterproof layer, a heat ray shielding layer, and the like, and any one or a plurality of these layers may be formed in advance on the substrate. The coated article further includes a vapor-deposited layer formed by a chemical vapor deposition (CVD) method, a hard coat layer, a rust prevention layer, a gas barrier layer, a waterproof layer, and a heat ray shield on the surface on which the cured film made of the above composition is formed. It may be covered with one or more layers such as a layer, an antifouling layer, a photocatalyst layer and an antistatic layer. Further, the coated article has a hard coat layer, a rustproof layer, a gas barrier layer, a waterproof layer, a heat ray shielding layer, an antifouling layer, and a photocatalyst layer on the side opposite to the side on which the cured film made of the composition is formed. Or a single layer or a plurality of layers such as an antistatic layer.

  The method for applying the composition may be appropriately selected from known methods, for example, using various application methods such as brush coating, spraying, dipping, flow coating, roll coating, curtain coating, spin coating, and knife coating. it can.

  In the coated article of the present invention, the thickness of the cured film is not particularly limited and may be appropriately selected depending on the intended use, but is preferably from 0.1 to 50 μm, and the hardness, the scratch resistance, and the long-term stability of the cured film In order to satisfy good adhesion and no cracks, the thickness is particularly preferably 1 to 20 μm. The film thickness can be appropriately adjusted by means of a coating method.

  One of the features of the coated article of the present invention is the visible light transmittance of the cured film. The visible light transmittance is generally evaluated by the haze (haze) of the cured film, and it is considered that the smaller the haze, the better the visible light transmittance. As the haze, a value measured by a turbidity meter NDH2000 (manufactured by Nippon Denshoku Industries Co., Ltd.) can be used. The haze of a cured film generally increases as the film thickness increases. In the coated article of the present invention, the haze is preferably 2.0 or less, more preferably 1.5 or less, and still more preferably 1.0 or less when the thickness of the cured film is 5 μm or less.

  One of the features of the coated article of the present invention is the excellent scratch resistance of the cured film. As the evaluation, comparison can be made by a scratch resistance test of the cured film. The abrasion resistance test was carried out according to ASTM 1044, and the haze after 500 rotations under a load of 500 gf was measured by mounting a worn wheel SC-10F in a Taber abrasion test, and the haze difference (ΔHz) before and after the test was compared. , ΔHz is smaller, the scratch resistance is better. In the coated article of the present invention, ΔHz is preferably 10 or less, more preferably 5 or less, still more preferably 4 or less, and most preferably 3 or less.

  Hereinafter, the present invention will be specifically described with reference to Synthesis Examples, Examples, and Comparative Examples. The following examples do not limit the present invention at all.

(Synthesis of silica dispersion)
[Example 1-1]
Step (A1):
To a 1-liter glass reactor equipped with a stirrer, a dropping funnel and a thermometer, 396 g of methanol, 16 g of water, and 20 g of 28% by mass aqueous ammonia were added and mixed. This solution was adjusted to 50 ° C., and 323 g of tetramethoxysilane and 81 g of 5.5% by mass ammonia water were simultaneously dropped while stirring. After completion of the dropwise addition, the mixture was stirred at 50 ° C. for 1 hour to carry out hydrolysis to obtain a dispersion of sol-gel silica particles. The nonvolatile component content (105 ° C., 3 hours) of the obtained dispersion was 18% by mass.

Step (A2):
To 837 g of the dispersion obtained in the above step (A1), 22.6 g of 3-methacryloxypropyltrimethoxysilane (KBM-503: manufactured by Shin-Etsu Chemical Co., Ltd.) was added at 25 ° C., and the mixture was stirred for 2 hours. Continuously, a silica particle dispersion liquid surface-treated with an organosilicon compound having a methacryl group was obtained.

-Step (A3):
To the dispersion obtained in the above step (A2), at 25 ° C., 1,6-hexanediol diacrylate (HDDA, boiling point: 259 ° C.) equivalent to the mass of the silica particles was added. The HDDA dispersion containing 50% by mass of silica coated with a methacrylic group-containing organosilicon compound was obtained by distilling off the low boiling components at 50 ° C. under reduced pressure (6,650 Pa).

[Example 1-2]
In the step (A2) of Example 1-1, an organosilicon compound having a methacrylic group was obtained in the same procedure as in Example 1-1, except that the amount of 3-methacryloxypropyltrimethoxysilane was changed to 30.1 g. To obtain an HDDA dispersion containing 50% by mass of silica surface-treated.

[Example 1-3]
In the step (A2) of Example 1-1, after adding 22.6 g of 3-methacryloxypropyltrimethoxysilane and continuing stirring for 2 hours, trimethylsilanol (LS-310: manufactured by Shin-Etsu Chemical Co., Ltd.) HDDA dispersion containing 50% by mass of silica surface-treated with an organosilicon compound having a methacrylic group and a silane compound in the same procedure as in Example 1-1, except that 15.1 g of was added and stirring was continued for 1 hour. A liquid was obtained.

[Example 1-4]
In the step (A2) of Example 1-3, except that 3-methacryloxypropyltrimethoxysilane was changed to 27.5 g of 8-methacryloxyoctyltrimethoxysilane (KBM-5803: manufactured by Shin-Etsu Chemical Co., Ltd.). By the same procedure as in Example 1-3, an HDDA dispersion containing 50% by mass of silica surface-treated with an organosilicon compound having a methacryl group and a silane compound was obtained.

[Example 1-5]
In the step (A2) of Example 1-3, the procedure was the same as that of Example 1-3 except that 3-methacryloxypropyltrimethoxysilane was changed to 20.0 g of methacryloxymethyltrimethoxysilane (manufactured by Gelest). Then, an HDDA dispersion liquid containing 50% by mass of silica surface-treated with an organosilicon compound having a methacryl group and a silane compound was obtained.

[Comparative Example 1-1]
Example 1 Example 1 was repeated except that the addition amount of the organosilicon compound having a (meth) acrylic group (KBM-503: manufactured by Shin-Etsu Chemical Co., Ltd.) was changed to 7.5 g in the step (A2) of Example 1-1. In the same manner as in Example 1, an HDDA dispersion containing 50% by mass of silica surface-treated with an organosilicon compound having a methacryl group was obtained.

[Comparative Example 1-2]
100 parts by mass of a hydrophobic spherical sol-gel silica powder having no (meth) acrylic group (QSG-10 (silica particles surface-hydrophobized with a trimethylsiloxy group), manufactured by Shin-Etsu Chemical Co., Ltd.) and 100 parts by mass of HDDA It was added so as to be in parts by mass and mixed to obtain a HDDA dispersion of silica.

[Comparative Example 1-3]
HDDA is added to 100 parts by mass of hydrophobic spherical sol-gel silica powder having no (meth) acrylic group (QSG-100 (silica particles subjected to surface hydrophobization treatment with trimethylsiloxy group), manufactured by Shin-Etsu Chemical Co., Ltd.). It was added so as to be in parts by mass and mixed to obtain a HDDA dispersion of silica.

[Comparative Example 1-4]
4.5 g of 3-methacryloxypropyltrimethoxysilane (KBM-503: manufactured by Shin-Etsu Chemical Co., Ltd.) per 100 g of a 30% by mass IPA dispersion of ion-exchanged silica (IPA-ST, manufactured by Nissan Chemical Industries, Ltd.) And 1.3 g of ion-exchanged water, and stirring was continued for 2 hours under reflux. After adding an equal amount of HDDA to the mass of the silica particles at 25 ° C. to the obtained silica particle dispersion, the low boiling components in the dispersion are distilled off at 50 ° C. under reduced pressure (6,650 Pa). Thereby, an HDDA dispersion liquid containing 50% by mass of silica coated with an organosilicon compound having a methacryl group was obtained.

  The following evaluation was performed about the silica dispersion liquid obtained by the said Example and the comparative example. The results are shown in Tables 1 and 2. The content of the organosilicon compound having a (meth) acryl group in the table is [the amount of the organosilicon compound having a (meth) acryl group] / [mass of sol-gel silica before surface treatment] × 100 ( % By mass).

[Particle size]
The silica particle dispersion was diluted with methanol so that the silica particles became 1% by mass, and the particle size distribution when the particles were dispersed by irradiating ultrasonic waves for 10 minutes was determined by the dynamic light scattering method / laser Doppler method. It was measured with a Nanotrac particle size distribution analyzer (UPA-EX150: manufactured by Nikkiso Co., Ltd.), and the volume-based median diameter (D50) and D90 / D10 value were calculated.

[Q ⁴ / Q]
²⁹ Si-NMR measurement was performed under the following conditions.
Apparatus: Pulse-Fourier transform nuclear magnetic resonance apparatus (JNM-ECX500II: manufactured by JEOL Ltd.)
Magnetic field strength: 11.75T
Number of integration: 10640
S / N ratio:> 5
Sample tube material: Polytetrafluoroethylene Solvent: Deuterated chloroform Reference material: Tetramethylsilane Relaxant: Chromium (III) acetylacetonate

In the obtained spectrum, the ratio (Q ⁴ / Q) of the peak area (Q ⁴ ) of −105 to −130 ppm to the peak area (Q) of −80 to −130 ppm was calculated.

[Liquidity]
The case where fluidity was visually observed was evaluated as “「 ”, and the case where there was almost no fluidity was evaluated as“ X ”.

[Sodium content]
After the silica dispersion is incinerated, the amount of sodium contained in the silica dispersion is determined using an inductively coupled plasma emission spectroscopy (IPC-OES) apparatus (Agilent-730, manufactured by Agilent Technologies). did.

＊粒子の沈降により検出不可

* Not detectable due to settling of particles

As shown in Table 1, in Examples 1-1 to 1-5, a fluid liquid in which silica was dispersed at a high concentration in HAAD was obtained.
On the other hand, as shown in Table 2, in Comparative Example 1-1, silica aggregated, and did not show fluidity. This result indicates that the coating with the added (meth) acrylic group-containing organosilicon compound was insufficient, and the compatibility between silica and HDDA was insufficient, so that aggregation occurred between the silicas and the fluidity was impaired. ing.
In the case of Comparative Example 1-2 and Comparative Example 1-3, aggregation of silica did not occur, but strong thickening occurred and did not show fluidity. This result indicates that, even when the silica surface is sufficiently hydrophobized, the silica surface does not have a (meth) acrylic group, so that the viscosity increases due to insufficient affinity with HDDA. Is shown.
In Comparative Example 1-3, particles having a particle diameter of 70 nm or more were used, so that light scattering was large and cloudiness of the dispersion was observed.
In the case of Comparative Examples 1-4, the use of ion-exchanged silica resulted in an extremely high sodium content in the obtained fluid liquid. On the other hand, the silica dispersion obtained in the present invention contains almost no sodium atom, and thus can be used without problems in applications where contamination with alkali metals is a problem.

[Example 2-1]
Based on 100 parts by mass of the silica / HDDA dispersion obtained in Example 1-1, 2-hydroxy-2-methyl-1-phenyl-propan-1-one (trade name: DAROCUR 1173, manufactured by BASF). 4 parts by mass were added to prepare a photocurable composition.

The obtained composition was coated on a polycarbonate plate (thickness: 5 mm, product name: Takiron PC Clear-1600 type, manufactured by Takiron C.I.) using a bar coater # 8, and then 600 mJ / N 2 in a nitrogen atmosphere using a high-pressure mercury lamp. Irradiation with ultraviolet light of cm ² (integrated ultraviolet energy at a wavelength of 300 to 390 nm, eye ultraviolet integrated illuminometer UVPF-A1 (PD-365): manufactured by Iwasaki Electric Co., Ltd.) to cure the film to a thickness of 15.1 μm. A membrane was prepared.

[Example 2-2]
Curing is performed in the same manner as in Example 2-1 except that the silica / HDDA dispersion obtained in Example 1-2 is used instead of the silica / HDDA dispersion obtained in Example 1-1. A membrane was prepared.

[Example 2-3]
Curing is performed in the same procedure as in Example 2-1 except that the silica / HDDA dispersion obtained in Example 1-3 is used instead of the silica / HDDA dispersion obtained in Example 1-1. A membrane was prepared.

[Example 2-4]
Cured in the same procedure as in Example 2-1 except that the silica / HDDA dispersion obtained in Example 1-4 was used instead of the silica / HDDA dispersion obtained in Example 1-1. A membrane was prepared.

[Example 2-5]
Cured in the same procedure as in Example 2-1 except that the silica / HDDA dispersion obtained in Example 1-5 was used instead of the silica / HDDA dispersion obtained in Example 1-1. A membrane was prepared.

[Example 2-6]
For 100 parts by mass of the silica / HDDA dispersion obtained in Example 1-3, 10 parts by mass of trimethylolpropane triacrylate (TMPTA), 2-hydroxy-2-methyl-1-phenyl-propane-1- 4 parts by mass of ON (DAROCUR 1173: manufactured by BASF) was added to prepare a photocurable composition. A cured film was prepared from the obtained composition under the same conditions as in Example 2-1.

[Example 2-7]
A cured film was prepared in the same procedure as in Example 2-6 except that 10 parts by mass of dipentaerythritol hexaacrylate (DPHA) was used instead of TMPTA.

[Example 2-8]
The silica / HDDA dispersion obtained in Example 1-3 was directly coated on a polycarbonate plate (thickness: 5 mm, product name: Takiron PC Clear-1600, manufactured by Takiron C.I.) using a bar coater # 8. By using a high-pressure mercury lamp and irradiating ultraviolet rays of 2,400 mJ / cm ^{2 in} a nitrogen atmosphere, a cured film having a thickness of 14.8 μm was prepared.

[Comparative Example 2-1]
4 parts by mass of 2-hydroxy-2-methyl-1-phenyl-propan-1-one (DAROCUR 1173: BASF) was added to 100 parts by mass of HDDA to prepare a photocurable composition. A cured film was prepared from the obtained composition under the same conditions as in Example 2-1.

[Comparative Example 2-2]
Cured in the same procedure as in Example 2-1 except that the silica / HDDA dispersion obtained in Comparative Example 1-4 was used instead of the silica / HDDA dispersion obtained in Example 1-1. A membrane was prepared.

[Comparative Example 2-3]
Cured in the same manner as in Example 2-6, except that the silica / HDDA dispersion obtained in Comparative Example 1-4 was used instead of the silica / HDDA dispersion obtained in Example 1-3. A membrane was prepared.

[Comparative Example 2-4]
Cured in the same manner as in Example 2-7, except that the silica / HDDA dispersion obtained in Comparative Example 1-4 was used instead of the silica / HDDA dispersion obtained in Example 1-3. A membrane was prepared.

  The following evaluations were performed on the polycarbonate plates on which the cured films obtained in Examples 2-1 to 2-8 and Comparative Examples 2-1 to 2-4 were formed. Table 3 shows the results.

[transparency]
The haze was measured using a turbidimeter (NDH2000: manufactured by Nippon Denshoku Industries Co., Ltd.). Those having a haze value of 2 or less were evaluated as “○”, and those having a haze value larger than 2 were evaluated as “x”.

[Scratch resistance]
According to ASTM 1044, a worn wheel SC-10F was mounted in a Taber abrasion test, and the haze after 500 rotations with a load of 500 gf was measured using a haze meter (NDH5000SP: manufactured by Nippon Denshoku Industries Co., Ltd.), and the abrasion test was performed. The difference (ΔHz) from the previous value was calculated.

[Adhesion]
According to JIS K5400, using a razor blade, the cured film was cut into 6 pieces vertically and horizontally at intervals of 2 mm to make 25 grids, and cellophane tape (registered trademark, manufactured by Nichiban Co., Ltd.) was adhered well. After that, when the film was rapidly peeled in the forward direction by 90 °, the number of squares (X) in which the cured film remained without peeling was evaluated by X / 25. X = 25 was evaluated as “○”, and X <25 was evaluated as “×”.

Regarding the physical properties of the cured film of the photocurable composition shown in Table 3, in Examples 2-1 to 2-8 satisfying the requirements of the present invention, ΔHz was 3.6 or less, indicating excellent scratch resistance.
On the other hand, when no silica particles were contained as in Comparative Example 2-1, ΔHz was 10 or more, and the scratch resistance was significantly reduced.
Further, in Comparative Examples 2-2 to 2-4, despite the fact that the silica particles contained the same degree as in Examples 2-1 to 2-8, ΔHz was 5 or more, and the effect of improving the scratch resistance was poor. It was limited.
The raw material of the silica particles used in Comparative Examples 2-2 to 2-4 is ion-exchange silica in which siloxane condensation has progressed further, and the peak ratio of ²⁹ Si-NMR: Q ⁴ / Q is 0.80. The bigger favors it.
On the other hand, the silica raw material used in Examples 2-1 to 2-8 is a sol-gel method silica, and when compared with ion exchange method silica, the peak ratio of ²⁹ Si-NMR: Q ⁴ / Q is 0.70 to 0.70. 0.75, satisfying that the sodium content is 100 ppm or less.
Therefore, the above results suggest that more excellent scratch resistance was developed due to the use of the sol-gel method silica. In addition, in Example 2-8, a cured film having high abrasion resistance was obtained even without adding a photoreaction initiator.
From the above, the silica dispersion obtained in the present invention is useful as a raw material for an excellent hard coat paint, which is less affected by yellowing and deterioration of weather resistance due to a photoreaction initiator.

Claims (20)

In a liquid compound having a radical polymerizable unsaturated bond, a silica dispersion in which surface-treated sol-gel silica particles are dispersed,
The surface-treated sol-gel silica is a surface-treated product of at least one of an organosilicon compound having a (meth) acrylic group represented by the following formula (1) and a (partly) hydrolyzed condensate thereof, and is based on volume. In a dispersion containing sol-gel silica particles having a median diameter in the particle size distribution of 1 to 60 nm, an organosilicon compound having a (meth) acrylic group represented by the following formula (1) based on 100 parts by mass of the sol-gel silica particles A silica dispersion which is a surface-treated product to which 10 parts by mass or more is added.

(Wherein, R ¹ is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R ² is an alkylene group having 1 to 20 carbon atoms, and R ³ are each independently a hydrogen atom or 1 carbon atom. And R ⁴ is each independently a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom, and n is an integer of 1 to 3.) The ratio (Q ⁴ / Q) of the peak area (Q ⁴ ) of −105 to −130 ppm to the peak area (Q) of −80 to −130 ppm in the ²⁹ Si-NMR spectrum of the sol-gel silica particles is 0.8 or less. Item 6. The silica dispersion according to Item 1.   The silica dispersion according to claim 1 or 2, wherein the value of D90 / D10 in the volume-based particle size distribution of the sol-gel silica particles is 3.2 or less. The silica dispersion according to any one of claims 1 to 3, wherein the organosilicon compound having a (meth) acryl group includes a compound represented by the following formula (2).

(In the formula, R ³ , R ⁴ , and n are the same as described above.) The silica dispersion according to any one of claims 1 to 3, wherein the organosilicon compound having a (meth) acryl group includes a compound represented by the following formula (3).

(In the formula, R ³ , R ⁴ , and n are the same as described above.) The silica dispersion according to any one of claims 1 to 3, wherein the organosilicon compound having a (meth) acryl group includes a compound represented by the following formula (4).

(In the formula, R ³ , R ⁴ , and n are the same as described above.) The silica dispersion according to any one of claims 1 to 6, wherein the surface-treated sol-gel silica particles are further surface-treated with one or more silane compounds represented by the following formula (5).
R ⁵ ₃ SiY ⁽⁵⁾
(In the formula, R ⁵ is a monovalent hydrocarbon group having 1 to 20 carbon atoms, and Y is a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an amino group, an acyloxy group, or a halogen atom.)   The liquid compound having a radical polymerizable unsaturated bond contains at least one of 1,6-hexanediol diacrylate, trimethylolpropane triacrylate and dipentaerythritol hexaacrylate. Silica dispersion.   The silica dispersion according to any one of claims 1 to 8, comprising 5 to 250 parts by mass of the surface-treated sol-gel silica particles with respect to 100 parts by mass of the liquid compound having a radical polymerizable unsaturated bond.   The silica dispersion according to any one of claims 1 to 9, having a sodium content of 100 ppm or less.   A photocurable composition comprising the silica dispersion according to claim 1.   A cured product obtained by curing the photocurable composition according to claim 11. (A1) Hydrolysis / condensation of a silane compound represented by the following formula (6), its (partially) hydrolyzed condensate or a mixture thereof in a mixed solvent of a hydrophilic organic solvent and water in the presence of a basic substance Obtaining an organic solvent / water dispersion of sol-gel silica particles by doing
Si (OR ⁶ ) ₄ (6)
(However, R ⁶ is each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 6 carbon atoms.)
(A2) In a dispersion of the sol-gel silica particles, an organosilicon compound having a (meth) acrylic group represented by the following formula (1) based on 100 parts by mass of the sol-gel silica particles, and a (partially) hydrolyzed condensate thereof Adding at least one of the above by 10 parts by mass or more, treating the surface of the sol-gel silica particles,

(Wherein, R ¹ is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R ² is an alkylene group having 1 to 20 carbon atoms, and R ³ are each independently a hydrogen atom or 1 carbon atom. And R ⁴ is each independently a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, or a halogen atom, and n is an integer of 1 to 3.)
(A3) A liquid compound having a radical polymerizable unsaturated bond is added to the dispersion liquid of the sol-gel silica particles surface-treated with the organosilicon compound having a (meth) acrylic group obtained in the step (A2). Removing the hydrophilic organic solvent, water and, in some cases, the alcohol produced by the surface treatment by distillation. The ratio (Q ⁴ / Q) of the peak area (Q ⁴ ) of −105 to −130 ppm to the peak area (Q) of −80 to −130 ppm in the ²⁹ Si-NMR spectrum of the sol-gel silica particles obtained in the step (A1). 14. The method for producing a silica dispersion according to claim 13, wherein is 0.8 or less.   The method for producing a silica dispersion according to claim 13 or 14, wherein the value of D90 / D10 in the particle size distribution of the sol-gel silica particles obtained in step (A1) is 3.2 or less. The method for producing a silica dispersion according to any one of claims 13 to 15, wherein in the step (A2), the organosilicon compound having a (meth) acryl group includes a compound represented by the following formula (2).

(In the formula, R ³ , R ⁴ , and n are the same as described above.) The method for producing a silica dispersion according to any one of claims 13 to 15, wherein in the step (A2), the organosilicon compound having a (meth) acrylic group contains a compound represented by the following formula (3).

(In the formula, R ³ , R ⁴ , and n are the same as described above.) The method for producing a silica dispersion according to any one of claims 13 to 15, wherein in the step (A2), the organosilicon compound having a (meth) acrylic group contains a compound represented by the following formula (4).

(In the formula, R ³ , R ⁴ , and n are the same as described above.) The process of any one of claims 13 to 18, wherein in the step (A2), the surface of the sol-gel silica particles obtained in the step (A1) is treated by further adding one or more silane compounds represented by the following formula (5). 3. The method for producing a silica dispersion according to claim 1.
R ⁵ ₃ SiY ⁽⁵⁾
(In the formula, R ⁵ is a monovalent hydrocarbon group having 1 to 20 carbon atoms, and Y is a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an amino group, an acyloxy group, or a halogen atom.)   The method for producing a silica dispersion according to any one of claims 13 to 19, wherein the sodium content of the silica dispersion obtained in the step (A3) is 100 ppm or less.