TWI583739B - A composition for a transparent film, a method for forming a transparent film, and a transparent film - Google Patents

Description

Composition for transparent film, method for forming transparent film, and transparent film

The present invention relates to a composition for a transparent film, a method for forming a transparent film, and a transparent film.

In the past, in the manufacture of an optical semiconductor element such as a light-emitting diode (LED), a transparent encapsulant composition used for encapsulation of an optical semiconductor element or the like is known (refer to Patent Document 1). The composition disclosed in Patent Document 1 contains a polyoxyalkylene modified by a specific alkoxydecane obtained by a dealcoholization reaction of a partial condensate of a polyoxyalkylene having a decyl alcohol group and a tetraalkoxy decane at both ends thereof, and hardening. catalyst.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] International Publication No. 2010/090280

In general, an optical device such as an optical semiconductor element or a solar cell is protected by a transparent film formed of the composition of the above Patent Document 1. Since the transparent film can be preferably used as a protective film, high durability is required. And, of course, high transparency is also required.

A method of improving the durability of a transparent film is to form a transparent film by firing a composition for a transparent film at a high temperature. Since the composition is fired at a high temperature, The impurities in the composition which is a cause of deterioration of the transparent film can be burned and removed, so that the durability of the transparent film can be improved. However, when the composition for a transparent film is fired at a high temperature, there is a problem that cracks easily occur on the transparent film. In particular, the thicker the thickness of the transparent film, the more likely it is to crack. Therefore, the composition for a transparent film is required to improve crack resistance.

In this case, the inventors of the present application repeated the results of active research and found that the type of the organic group directly bonded to the ruthenium atom in the condensation product of the alkoxydecane contained in the composition for the transparent film was found. With the content, better crack resistance and transparency are obtained.

The present invention has been completed based on the knowledge of the inventors and the like, and an object thereof is to provide a technique capable of imparting good crack resistance and transparency to a transparent film formed by firing at a high temperature.

In order to solve the above problems, the present invention is a composition for a transparent film, and the composition for a transparent film is a composition for a transparent film formed by firing at a high temperature of 500 ° C or higher, and is characterized by containing the following The condensation product (A) of the first alkoxydecane represented by the formula (1) and the second alkoxydecane represented by the following formula (2) as a starting material, and the organic solvent (B), and direct bonding The content of the methyl group of the ruthenium atom in the condensation product (A) is 15 to 25% based on the condensation product (A), (CH ₃ ) _n Si(OR ¹ ) _4-n (1) [Formula (1) In the formula, R ¹ is an alkyl group having 1 to 5 carbon atoms, n is an integer of 1 or 2, and plural (OR ¹ ) may be the same or different], Si(OR ² ) ₄ (2) [Formula (2) In the formula, R ² is an alkyl group having 1 to 5 carbon atoms, and a plurality of (OR ² ) may be the same or different.

According to this aspect, it is possible to impart good crack resistance and transparency to the transparent film formed by firing at a high temperature.

Another aspect of the present invention provides a method for forming a transparent film, comprising the steps of applying a composition of the above-described state on a substrate, and firing the composition at 500 ° C or higher to form a transparent film.

Another aspect of the present invention is a transparent film characterized by being formed by the above-described method of forming a transparent film.

According to the present invention, it is possible to provide a technique capable of imparting good crack resistance and transparency to a transparent film formed by firing at a high temperature.

Hereinafter, the present invention will be described in terms of preferred embodiments. The embodiments are not intended to limit the invention, and all of the features described in the embodiments or combinations thereof are not necessarily essential to the invention.

The composition of the present embodiment is a composition for forming a transparent film by firing at a high temperature of 500 ° C or higher (hereinafter, the composition is appropriately referred to as a composition for a transparent film). The composition for a transparent film of the present embodiment contains a condensation product (A) and an organic solvent (B). Further, the composition for a transparent film contains a surfactant (C) as an optional component. The following is for the transparent film of this embodiment. The components of the composition are described in detail.

<condensation product (A)>

The condensation product (A) is a condensation product of a first alkoxydecane represented by the following formula (1) and a second alkoxydecane represented by the following formula (2) as a starting material.

(CH ₃ ) _n Si(OR ¹ ) _4-n (1) [In the formula (1), R ¹ is an alkyl group having 1 to 5 carbon atoms, n is an integer of 1 or 2, and plural (OR ¹ ) Si(OR ² ) ₄ (2) [In the formula (2), R ² is an alkyl group having 1 to 5 carbon atoms, and plural (OR ² ) may be the same or different).

The first alkoxydecane and the second alkoxydecane are described in detail below.

(first alkoxy decane)

In the first alkoxy decane, the alkoxy decane (i) in the case where n in the above formula (1) is 1, is represented by the following formula (3).

(CH ₃ )Si(OR ²¹ ) _a (OR ²² ) _b (OR ²³ ) _c (3) [In the formula (3), R ²¹ , R ²² and R ^{23 are} each independently of the above formula (1) R ^{1 is the} same alkyl group having 1 to 5 carbon atoms, and a, b and c are integers satisfying the conditions of 0≦a≦3, 0≦b≦3, 0≦c≦3, and a+b+c=3 ].

The alkyl group having 1 to 5 carbon atoms in the above formulas (1) and (3) is exemplified by a linear alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group or a pentyl group; a branched chain alkyl group such as an ethyl group, a 1-methylpropyl group, a 2-methylpropyl group, a 1-methylbutyl group, a 2-methylbutyl group or a 3-methylbutyl group; a cyclic group such as a cyclopentyl group; alkyl. It is preferably an alkyl group having 1 to 3 carbon atoms, more preferably a methyl group and an ethyl group.

Specific examples of the alkoxydecane (i) are, for example, methyltrimethoxydecane, methyltriethoxydecane, methyltri-n-propoxydecane, methyltriisopropoxydecane, and methyltri-n-methyl Butoxy decane, methyl tri-tert-butoxy decane, methyl tri-tert-butoxy decane, methyl monomethoxy diethoxy decane, methyl dimethoxy monoethoxy decane, etc. Among them, methyltrimethoxydecane and methyltriethoxydecane are preferred from the viewpoint of reactivity.

The alkoxydecane (ii) in the case where n in the above formula (1) is 2 is represented by the following formula (4).

(CH ₃ )(CH ₃ )Si(OR ³¹ ) _d (OR ³² ) _e (4) [In the formula (4), R ³¹ and R ³² each independently represent the same as R ^{1 of the} above formula (1). An alkyl group having 1 to 5 carbon atoms, d and e are 0≦d≦2, 0≦e≦2, and an integer satisfying the condition of d+e=2].

Specific examples of the alkoxydecane (ii) are, for example, dimethyldimethoxydecane, dimethyldiethoxydecane, dimethyldipropoxydecane, dimethyldiisopropoxydecane, Dimethyldi-n-butoxy decane, dimethyldi-butoxy decane, dimethyldi-butoxy decane, dimethyl-monomethoxy-monoethoxy decane, etc., among which reactivity In terms of dimethyl dimethoxy decane and dimethyl diethoxy decane, it is preferred.

The first alkoxydecane is preferably an alkoxydecane wherein n is 2 in the formula (1), that is, an alkoxydecane represented by the following formula (5), in other words, the above formula (4) Alkoxydecane (ii) represented.

(CH ₃ ) ₂ Si(OR ¹ ) ₂ (5) [In the formula (5), R ¹ is an alkyl group having 1 to 5 carbon atoms, and plural (OR ¹ ) may be the same or different).

The first alkoxy decane can be easily bonded directly by containing an alkoxy decane having two methyl groups directly bonded to a ruthenium atom represented by the above formula (4) or (5). The content of the methyl group of the ruthenium atom relative to the condensation product (A) is adjusted to the range described later.

(second alkoxy decane)

The second alkoxysilane represented by the above formula (2) is, for example, represented by the following formula (6).

Si(OR ⁴¹ ) _f (OR ⁴² ) _g (OR ⁴³ ) _h (OR ⁴⁴ ) _i (6) [In the formula (6), R ⁴¹ , R ⁴² , R ⁴³ and R ^{44 are} each independently represented by the above formula (2) The alkyl group having the same carbon number of 1 to 5 as R ² . f, g, h, and i are 0≦f≦4, 0≦g≦4, 0≦h≦4, 0≦i≦4, and an integer satisfying the condition of f+g+h+i=4].

The alkyl group having 1 to 5 carbon atoms in the above formula (2) or (6) is the same as the alkyl group having 1 to 5 carbon atoms in the above formula (1) or (3).

Specific examples of the alkoxydecane represented by the above formula (6) are, for example, tetramethoxydecane, tetraethoxydecane, tetra-n-propoxydecane, tetraisopropoxydecane, tetra-n-butoxy Decane, tetra-second butoxy decane, tetra-butoxy decane, trimethoxy monoethoxy decane, dimethoxydiethoxy decane, monomethoxy triethoxy decane, etc. From the viewpoint of reactivity, tetramethoxynonane or tetraethoxysilane is preferred.

The condensation product (A) can be prepared by hydrolyzing the first alkoxydecane and the second alkoxydecane in the presence of, for example, an acid catalyst, water, or a solvent.

As the acid catalyst, any of an organic acid and an inorganic acid can be used. As the inorganic acid, sulfuric acid, phosphoric acid, nitric acid, hydrochloric acid or the like can be used, and among them, nitric acid is preferred. As the organic acid, a carboxylic acid such as formic acid, oxalic acid, fumaric acid, maleic acid, glacial acetic acid, acetic anhydride, propionic acid or n-butyric acid, or an organic acid having a sulfuric acid residue can be used. The organic acid having a sulfuric acid residue is exemplified by an organic sulfonic acid or the like. These ester compounds are exemplified by organic sulfates, organic sulfites, and the like. Among these, in particular, an organic sulfonic acid, for example, a compound represented by the following formula (7) is preferred.

R ¹³ -X (7) [In the formula (7), R ¹³ is a hydrocarbon group which may have a substituent, and X is a sulfonic acid group].

In the above formula (7), the hydrocarbon group as R ¹³ is preferably a hydrocarbon group having 1 to 20 carbon atoms. The hydrocarbon group may be either saturated or unsaturated, and may be any of a linear chain, a branched chain, and a cyclic chain. When the hydrocarbon group of R ¹³ is cyclic, an aromatic hydrocarbon group such as a phenyl group, a naphthyl group or a fluorenyl group is preferred, and a phenyl group is preferred. The aromatic ring in the aromatic hydrocarbon group may be bonded to one or a plurality of hydrocarbon groups having 1 to 20 carbon atoms as a substituent. The hydrocarbon group of the substituent on the aromatic ring may be either saturated or unsaturated, and may be any of a linear chain, a branched chain, and a cyclic chain. Further, the hydrocarbon group as R ¹³ may have one or a plurality of substituents, and examples of the substituent include a halogen atom such as a fluorine atom, a sulfonic acid group, a carboxyl group, a hydroxyl group, an amine group, a cyano group and the like.

The above acid catalyst is used as a hydrolysis of alkoxydecane in the presence of water. The amount of the acid catalyst to be used is preferably such that the concentration in the reaction system for the hydrolysis reaction is from 1 to 1,000 ppm, particularly from 5 to 800 ppm. Since the amount of water added can change the hydrolysis rate of the siloxane polymer, it can be determined according to the desired hydrolysis rate.

The solvent in the reaction system of the hydrolysis reaction is exemplified by, for example, methanol, ethanol, propanol, isopropanol (IPA), one of n-butanol, such as methyl 3-methoxypropionate, 3-ethoxyl. Alkoxycarboxylate of ethyl propionate, polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, glycerol, trimethylolpropane, hexanetriol, ethylene glycol monomethyl ether, B Glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethanol monoethyl ether, diethylene glycol monopropyl ether, diethyl a monoether of a polyhydric alcohol such as diol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether or propylene glycol monobutyl ether or a monoacetate such as methyl acetate Ethyl acetate, butyl acetate esters, such as acetone, methyl ethyl ketone, methyl isoamyl ketone and other ketones, such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene Alcohol dipropyl ether, ethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl Ethyl ether Monoalcohols of hydroxy group etherified by both the polyol ethers and the like. These solvents may be used singly or in combination of two or more.

By hydrolyzing the first alkoxydecane and the second alkoxydecane by the reaction system, a hydrolysis product of the first alkoxydecane and a hydrolysis product of the second alkoxydecane are formed to dehydrate the hydrolyzed product. Condensation to obtain a dehydrated product (A). The hydrolysis reaction is usually carried out for about 1 to 100 hours. However, it is preferred to heat the reaction in a temperature range not exceeding 80 ° C when the reaction time is shortened.

After completion of the reaction, a reaction solution containing the synthesized condensation product (A) and a solvent used in the reaction is obtained. For example, the condensation product (A) can be separated from the solvent by a conventional method, and the organic solvent (B) described later is substituted for the solvent to obtain a solution state. Further, the synthesized condensation product (A) can also be separated from the solvent by a conventional method and dried to obtain a solid state.

Here, in the composition for a transparent film of the present embodiment, the content of the methyl group of the halogen atom directly bonded to the condensation product (A) to the condensation product (A) is 15 to 25%. The content (content ratio) is a ratio of the molecular weight of the methyl group of the halogen atom directly bonded to the condensation product (A) to the molecular weight of the condensation product (A).

In the transparent film, the organic group directly bonded to the ruthenium atom in the condensation product constituting the transparent film has a function of alleviating the stress due to shrinkage at the time of firing of the condensation product. Therefore, the longer the chain length of the organic group or the larger the volume, the more the stress relieving function is exhibited. On the other hand, the carbon-carbon bond portion in the condensation product of the transparent film reacts due to high temperature to lower the transparency. Therefore, the organic group bonded to the ruthenium atom in the composition for a transparent film of the present embodiment is a methyl group, and the content thereof is 15% or more and 25% or less. By setting the organic group directly bonded to the ruthenium atom to a methyl group to a content of 25% or less, the carbon-carbon bond portion in the condensation product can be reduced, so that the transparency of the transparent film can be suppressed from being lowered. Further, by setting the content of the methyl group to 15% or more, it is possible to suppress the occurrence of cracks on the transparent film.

The ratios of the first alkoxydecane and the second alkoxydecane are based on the source The molecular weight of the unit of each component is determined by including the total molecular weight of the methyl group directly bonded to the ruthenium atom within the above range with respect to the molecular weight of the condensation product (A). Here, the above "unit" is defined as a structure in which a ruthenium atom in the condensation product (A) and an atom or molecule directly bonded to the ruthenium atom are bonded. For example, the unit derived from the second alkoxydecane has a structure represented by the following formula (8).

Specific examples of the condensation product (A) are as shown in the following formulas (9) to (11).

[In the formula (9), j: k is a range in which the content of the methyl group of the halogen atom directly bonded to the condensation product (A) is 15 to 25% with respect to the content of the condensation product (A)].

[In the formula (10), 1: m is a range in which the content of the methyl group of the halogen atom directly bonded to the condensation product (A) is 15 to 25% with respect to the content of the condensation product (A)].

[In the formula (11), (o+p): q and o: p are such that the methyl group of the ruthenium atom directly bonded to the condensation product (A) is 15 to 25 relative to the condensation product (A). The range of %].

Further, the content of the methyl group in the condensation product (A) can be derived from the analysis of the structure of the condensation product (A) by NMR. Further, the ratio (j: k, l: m, (o + p): q, and o: p) of each of the above formulas (9) to (11) may also be obtained by using NMR condensation product (A). The structure is parsed and exported. Specifically, the structure and ratio of each unit are measured by NMR, and based on the molecular weight of each unit, the content Z (%) of the molecular weight of the methyl group directly bonded to the ruthenium atom relative to the condensation product (A) can be derived. For example, in the above formula (9), when j:k is 2:1, the content Z of the methyl group can be calculated by the following formula.

<Organic solvent (B)>

The organic solvent (B) is not particularly limited, and examples thereof include alcohols such as methanol, ethanol, isopropanol, and butanol, acetone, diethyl ketone, and methyl ethyl ketone. Ketones, esters such as methyl acetate, ethyl acetate, butyl acetate, polyhydric alcohols such as propylene glycol, glycerol, dipropylene glycol, dipropylene glycol dimethyl ether, ethylene glycol dimethyl ether, ethylene glycol Ethers such as diethyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol Monoether glycols such as monomethyl ether, cyclic ethers such as tetrahydrofuran and dioxane, and ether esters such as propylene glycol monomethyl ether acetate and propylene glycol monoethyl ether acetate.

<Interacting Agent (C)>

The composition for a transparent film of the present embodiment contains a surfactant (C) as an optional component. By containing a surfactant, the coating property, flatness, and spreadability of the composition for a transparent film can be improved, and the uneven coating of the composition layer for transparent films formed after coating can be reduced. Such a surfactant can be used in the past, but is preferably a polyoxyn surfactant. Further, the surfactant is contained in an amount of 10 to 10,000 ppm by mass, preferably 100 to 5,000 ppm by mass, more preferably 500 to 1,500 ppm by mass based on the entire composition for a transparent film. The surfactants may be used singly or in combination.

The additive is also added to adjust the characteristics of the viscosity of the composition for a transparent film as needed.

<Method of Forming Transparent Film>

A method of forming a transparent film will be described with reference to Figs. 1(A) to 1(D). 1(A) to 1(D) are for explaining the embodiment A schematic cross-sectional view of the steps of forming a transparent film.

The method for forming a transparent film according to the present embodiment includes the step of applying the composition for a transparent film to a substrate, and baking the composition for the transparent film to be applied at 500 ° C or higher to form a transparent film.

First, as shown in FIG. 1(A), the substrate 2 on which the optical device 1 is mounted is prepared. The optical device 1 is, for example, an LED (Light Emitting Diode), an organic EL, or the like. The base material 2 is, for example, a back side protective layer or the like. Moreover, the base material 2 may be a surface side protective layer laminated on the light-receiving surface or the light-emitting surface side of the optical device 1, or the like. Further, a solar cell or the like may be mounted on the substrate 2.

Then, as shown in FIG. 1(B), the composition for a transparent film of the present embodiment is applied onto the surface of the substrate 2 on the side on which the optical device 1 is mounted, and the composition layer 3 for a transparent film is formed. The coating method of the composition for a transparent film is not particularly limited, and a conventional method can be employed. Thereby, the optical device 1 is covered with the composition layer 3 for a transparent film.

Then, as shown in Fig. 1(C), the substrate 2 on which the composition layer 3 for a transparent film is laminated is placed in a heating furnace 4 such as an electric furnace, and the composition layer for a transparent film is fired at a temperature of 500 ° C or higher. 3. As a result, as shown in FIG. 1(D), the transparent film composition is thermally cured to form a transparent film 5 on the surface of the substrate 2. The optical device 1 is encapsulated in a transparent film 5. When the baking temperature of the composition for a transparent film is 500° C. or higher, impurities which cause deterioration of the transparent film 5 can be burned and removed, so that the durability of the transparent film 5 can be improved, and the transparent film 5 can be preferably used as a protection. membrane.

The transparent film of this embodiment can be formed by the above steps. A transparent film formed of the composition for a transparent film having the above composition at a thickness of 2.0 μm The light transmittance at a wavelength of 400 to 800 nm is 95% or more.

As described above, the composition for a transparent film of the present embodiment is a composition for a transparent film formed by firing at a high temperature of 500 ° C or higher, and contains the first alkoxydecane represented by the above formula (1) and The condensation product (A) and the organic solvent (B) of the second alkoxydecane represented by the above formula (2) as a starting material. Further, the methyl group of the halogen atom directly bonded to the condensation product (A) is 15 to 25% based on the condensation product (A). According to this, it is possible to impart good crack resistance and transparency to the transparent film formed by firing at a high temperature.

The present invention is not limited to the above-described embodiments, and various modifications such as design changes may be added based on the knowledge of those skilled in the art, and embodiments including the modifications are also included in the scope of the present invention.

[Examples]

The embodiments of the present invention are described below, but the examples are merely illustrative of the invention and are not intended to limit the invention.

The components and contents of the composition for a transparent film used in the experiment are shown in Table 1. Further, in the following examples and comparative examples, a polyfluorene-based surfactant (SF8421EG: manufactured by Toray. Dow Conning Co., Ltd.) was used as a surfactant. Further, when propylene glycol monomethyl ether (PM) was used as the organic solvent, and the content thereof was 100% by weight based on the total mass of the composition for a transparent film, the amount of each component was reduced from 100% by weight to the total amount of the solvent.

In Table 1, structures A1 to A5 and A'6 to A'9 are condensation products represented by the following chemical formulas. The content (%) of the organic group (organic group directly bonded to Si) directly bonded to the ruthenium atom in each condensation product was calculated by NMR.

Structure A1: In the following general formula (12), X ("organic group directly bonded to Si" in Table 1) is a methyl group, and the methyl group directly bonded to the ruthenium atom is 18%.

Structure A2: In the following general formula (12), X is a methyl group, and the methyl group directly bonded to the ruthenium atom is 20%.

Structure A3: In the following general formula (12), X is a methyl group, and the methyl group directly bonded to the ruthenium atom is 23%.

Structure A4: In the following general formula (13), the methyl group directly bonded to the ruthenium atom is 21%.

Structure A5: In the following formula (14), it is directly bonded to a ruthenium atom. The methyl content is 20%.

Structure A'6: In the following formula (12), X is a methyl group, and the methyl group directly bonded to the ruthenium atom is 10%.

Structure A'7: In the following formula (12), X is a methyl group, and the methyl group directly bonded to the ruthenium atom is 30%.

Structure A'8: In the following formula (12), X is an ethyl group, and the methyl group directly bonded to the ruthenium atom is 20%.

Structure A'9: In the following formula (12), X is a phenyl group, and the content of the phenyl group directly bonded to the ruthenium atom is 20%.

Further, the ratios (r: s, (t+u): v, t: u, and w: y) of the respective units in the above formulas (12) to (14) satisfy the respective examples and comparative examples. The ratio of the content of the organic group directly bonded to Si].

(formation of transparent film)

The composition for a transparent film of each of Examples and Comparative Examples was applied onto a sample substrate so that the final thickness became 2.0 μm using an applicator (SS8261NUU: manufactured by Tokyo Ohka Kogyo Co., Ltd.). Next, the sample was placed on a hot plate, and prebaked at 150 ° C for 3 minutes. Subsequently, it was thermally cured by firing in a vertical oven (TS8000MB: manufactured by Tokyo Ohka Kogyo Co., Ltd.) in N ₂ at 500 ° C for 30 minutes to obtain a transparent film having a film thickness of 2.0 μm.

(transparency evaluation)

The light transmittance of each of the transparent films of the respective examples and comparative examples was measured. The measurement of the light transmittance was carried out using a spectrophotometer (MCPD-3000: manufactured by Otsuka Electronics Co., Ltd.). When the transmittance at a wavelength of 400 to 800 nm was 95% or more, it was evaluated as good (○), and when the transmittance at a wavelength of 400 to 800 nm was less than 95%, it was evaluated as poor (×). The results are shown in Table 1.

(Cracking resistance evaluation)

With respect to the transparent films of the respective Examples and Comparative Examples, the presence or absence of cracks was confirmed by a microscope. When the crack was not confirmed, it was evaluated as good (○), and when the crack was confirmed, it was evaluated as poor (×). The results are shown in Table 1.

As shown in Table 1, the methyl ester is directly bonded to the ruthenium atom in the condensation product, and the content of the methyl group relative to the condensation product is included in the range of 15 to 25%. Examples 1 to 4 obtained good transparency and crack resistance. On the other hand, in the condensation product, a methyl group was directly bonded to a ruthenium atom, but Comparative Example 1 in which the content of the methyl group was less than 15% was poor in crack resistance. Further, in the condensation product, the methyl group was directly bonded to the ruthenium atom, but Comparative Example 2 in which the content of the methyl group exceeded 25% was inferior in transparency. Further, in Comparative Example 3 in which the ethyl group was directly bonded to the ruthenium atom in the condensation product, and the content of each group in Comparative Example 4 in which the phenyl group was directly bonded to the ruthenium atom in the condensation product was contained in the range of 15 to 25%. , but the transparency is poor. From these results, it was confirmed that the methyl group was directly bonded to the ruthenium atom in the condensation product, and when the content of the methyl group was in the range of 15 to 25%, both transparency and crack resistance were obtained.

1‧‧‧Optical device

2‧‧‧Substrate

3‧‧‧Composition layer for transparent film

4‧‧‧heating furnace

5‧‧‧Transparent film

1(A) to 1(D) are schematic cross-sectional schematic views for explaining a method of forming a transparent film according to an embodiment.

1‧‧‧Optical device

2‧‧‧Substrate

3‧‧‧Composition layer for transparent film

4‧‧‧heating furnace

5‧‧‧Transparent film

Claims (5)

A composition for a transparent film which is formed by firing at a high temperature of 500 ° C or higher and having a light transmittance of 95% or more at a wavelength of 400 to 800 nm at a thickness of 2.0 μm, and is characterized in that the composition contains a condensation product (A) of a first alkoxydecane represented by the following formula (1) and a second alkoxydecane represented by the following formula (2) as a starting material, and an organic solvent (B), directly The ratio of the molecular weight of the methyl group bonded to the halogen atom in the condensation product (A) to the molecular weight of the condensation product (A) is 15 to 25%, (CH ₃ ) _n Si(OR ¹ ) _4-n (1 [In the general formula (1), R ¹ is an alkyl group having 1 to 5 carbon atoms, n is an integer of 1 or 2, and plural (OR ¹ ) may be the same or different], Si(OR ² ) ₄ (2) In the formula (2), R ² is an alkyl group having 1 to 5 carbon atoms, and a plurality of (OR ² ) may be the same or different. The composition of claim 1, wherein the first alkoxydecane comprises an alkoxydecane represented by the following formula (5), (CH ₃ ) ₂ Si(OR ¹ ) ₂ (5) In the formula (5), R ¹ is an alkyl group having 1 to 5 carbon atoms, and a plurality of (OR ¹ ) may be the same or different. A composition according to claim 1 or 2, which contains a surfactant. A method of forming a transparent film, comprising the steps of: A step of coating a composition according to any one of claims 1 to 3 on a substrate, and baking the composition at 500 ° C or higher to form a transparent film. A transparent film characterized by being formed by a method of forming a transparent film according to item 4 of the patent application.