阅读说明：本技术 高硬度覆膜形成用涂布剂组合物 (Coating agent composition for forming high-hardness coating film ) 是由 阿部晋士 于 2021-04-20 设计创作，主要内容包括：本发明提供一种形成覆膜的聚硅氮烷能够溶解在安全性高的有机溶剂中,并能够形成高硬度且疏水性优异的覆膜的高硬度覆膜形成用涂布剂组合物。所述高硬度覆膜形成用涂布剂组合物的特征在于,含有：(A)具有下述式(1)所表示的重复单元及下述式(2)所表示的重复单元,且所述式(2)所表示的重复单元的数量相对于所述式(1)所表示的重复单元与所述式(2)所表示的重复单元的合计数量的比为0.2～0.5的聚硅氮烷；(B)闪点为21℃～55℃的脂肪族烃类溶剂；及(C)二丁醚,相对于所述(B)成分及所述(C)成分的掺合量的合计量,所述(C)成分的掺合量为0.1～20质量％。式中,R为选自碳原子数为1～6的脂肪族烃基、碳原子数为6～12的芳香族烃基、及碳原子数为1～6的烷氧基的基团。(The invention provides a coating agent composition for forming a high-hardness coating film, which can dissolve polysilazane for forming the coating film in a high-safety organic solvent and can form a coating film with high hardness and excellent hydrophobicity. The coating agent composition for forming a high-hardness coating film is characterized by containing: (A) polysilazane which has a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2), and in which the ratio of the number of repeating units represented by the formula (2) to the total number of repeating units represented by the formula (1) and the formula (2) is 0.2 to 0.5; (B) an aliphatic hydrocarbon solvent having a flash point of 21 to 55 ℃; and (C) dibutyl ether, with respect to the component (B) andthe total amount of the component (C) is 0.1 to 20% by mass.)

1. A coating agent composition for forming a high-hardness coating film, characterized by comprising:

(A) polysilazane which has a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2), and in which the ratio of the number of repeating units represented by the formula (2) to the total number of repeating units represented by the formula (1) and the formula (2) is 0.2 to 0.5;

(B) an aliphatic hydrocarbon solvent having a flash point of 21 to 55 ℃; and

(C) the content of the dibutyl ether is as follows,

the amount of the component (C) blended is 0.1 to 20% by mass based on the total amount of the components (B) and (C),

wherein R is a group selected from an aliphatic hydrocarbon group having 1 to 6 carbon atoms, an aromatic hydrocarbon group having 6 to 12 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms, and R in one molecule of polysilazane is the same or different.

2. The coating agent composition for forming a high-hardness coating film according to claim 1, wherein R in the formula (2) is a methyl group.

3. The coating agent composition for forming a high-hardness coating film according to claim 1, wherein the amount of the component (A) is 0.1 to 20% by mass based on the total amount of the components (A) to (C).

4. The coating agent composition for forming a high-hardness coating film according to claim 2, wherein the amount of the component (A) is 0.1 to 20% by mass based on the total amount of the components (A) to (C).

5. The coating agent composition for forming a high-hardness coating film according to any one of claims 1 to 4, wherein the component (B) contains at least one aliphatic hydrocarbon solvent selected from aliphatic hydrocarbons having 9 to 12 carbon atoms.

6. The coating agent composition for forming a high-hardness coating film according to any one of claims 1 to 4, further comprising (D) a curing catalyst.

7. The coating agent composition for forming a high-hardness coating film according to claim 5, further comprising (D) a curing catalyst.

8. A cured coating film formed from a cured product of the coating agent composition for forming a high-hardness coating film according to any one of claims 1 to 7.

9. A high-hardness coating film formed from the cured film according to claim 8, wherein the pencil hardness of the coating film on a glass substrate is 3H or more as measured by the method described in JIS K5600-5-4: 1999.

10. A transportation vehicle provided with the cured coating film according to claim 8.

Technical Field

The present invention relates to a coating agent composition for forming a high-hardness coating film.

Background

Polysilazanes are used in various applications as materials for forming moisture-proof films for semiconductor display devices such as organic EL display devices and electronic displays, and interlayer insulating films, passivation films, protective films, planarization films, and the like in devices such as semiconductors and LEDs. Further, studies have been made to utilize the transparency and hardness of a polysilazane cured film as a coating agent for vehicle bodies, building exterior walls, and the like.

As a coating agent containing polysilazane, patent document 1 discloses a composition containing inorganic polysilazane. However, although inorganic polysilazanes can form a dense film, they are pointed out to be harmful to health because they require an aromatic hydrocarbon solvent such as toluene or xylene as a solvent, and the usable sites are limited.

Therefore, studies on an organopolysilazane having an organic group introduced into a side chain while improving solubility in an organic solvent have been advanced (patent document 2). However, the higher the proportion of organic groups, the less the curing property, and the strength of the cured film is also reduced.

Further, if water droplets remain on the vehicle body or the building exterior wall, dirt adheres along the water droplets, and thus there is an increasing demand for improving the hydrophobicity of the coating surface.

In order to improve the hydrophobicity, patent document 3 adds a silicone modified with carboxyl groups at both ends to a polysilazane compound. In addition, patent document 4 modifies a side chain of polysilazane with perfluoropolyether. However, the cured films of patent documents 3 and 4 have a significantly reduced strength, and a fluorine-containing compound is not preferable from the viewpoint of environmental protection.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2011-142207

Patent document 2: international publication No. 2015/163360

Patent document 3: international publication No. 2016/121544

Patent document 4: japanese patent laid-open publication No. 2013-185038

Disclosure of Invention

Technical problem to be solved by the invention

The present invention has been made to solve the above problems, and an object of the present invention is to provide a coating agent composition for forming a high-hardness coating film, which can dissolve polysilazane for forming a coating film in an organic solvent with high safety and can form a coating film having high hardness and excellent hydrophobicity.

Means for solving the problems

In order to solve the above-mentioned problems, the present invention provides a coating agent composition for forming a high-hardness coating film, comprising:

(A) polysilazane which has a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2), and in which the ratio of the number of repeating units represented by the formula (2) to the total number of repeating units represented by the formula (1) and the formula (2) is 0.2 to 0.5;

(B) an aliphatic hydrocarbon solvent having a flash point of 21 to 55 ℃; and

(C) the content of the dibutyl ether is as follows,

the amount of the component (C) blended is 0.1 to 20% by mass based on the total amount of the components (B) and (C) blended.

Wherein R is a group selected from an aliphatic hydrocarbon group having 1 to 6 carbon atoms, an aromatic hydrocarbon group having 6 to 12 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms, and R in one molecule of polysilazane is the same or different.

In such a coating agent composition for forming a high-hardness coating film, polysilazane forming the coating film can be dissolved in a highly safe organic solvent, and a coating film having high hardness and excellent hydrophobicity can be formed.

In addition, R in the formula (2) is preferably a methyl group.

Such a polysilazane having a methyl group is easy to prepare and has a high hardness of a coating film.

The amount of the component (A) is preferably 0.1 to 20% by mass based on the total amount of the components (A) to (C).

Such a coating agent composition has good coatability and forms a uniform coating film.

The coating agent composition preferably contains the component (B) at least one aliphatic hydrocarbon solvent selected from aliphatic hydrocarbons having 9 to 12 carbon atoms.

Such a coating agent composition has little influence on the environment and odor, has excellent workability due to high volatility of the solvent, does not leave the solvent in the coating film, and forms a coating film having high hardness.

The coating agent composition preferably further contains (D) a curing catalyst.

Such a coating agent composition can be cured at normal temperature or in a short time, and is excellent in workability.

The present invention also provides a cured coating film formed from a cured product of the coating agent composition for forming a high-hardness coating film.

Such a cured coating has high hardness and excellent hydrophobicity.

The present invention also provides a high-hardness coating film formed from the cured film, wherein the pencil hardness of the coating film on a glass substrate, measured by the method described in JIS K5600-5-4: 1999, is 3H or more.

Such a high-hardness coating film is a high-hardness coating film that is less likely to cause scratches and less conspicuous damage and has high design properties. The high-hardness coating film can be used as a coating film for transportation vehicles and an anti-damage coating film for residential equipment such as water tanks and bathrooms.

The present invention also provides a transport vehicle provided with the cured coating film.

The cured coating film of the present invention has high hardness and excellent hydrophobicity, and is therefore particularly suitable for use in transportation vehicles.

Effects of the invention

As described above, in the coating agent composition for forming a high-hardness coating film of the present invention, polysilazane for forming a coating film is soluble in an organic solvent having low odor, low toxicity, and high safety, and therefore, the coating agent composition has good handling properties, improved storage stability and wettability with respect to a substrate, and imparts high hardness and water repellency to a cured coating film.

Detailed Description

As described above, there is a need for development of a coating agent in which a coating film-forming component is soluble in a highly safe solvent, and which has high hardness and excellent hydrophobicity.

The inventors of the present invention have conducted extensive studies to solve the above-mentioned problems, and as a result, have found that a coating agent composition for forming a high-hardness coating film, which contains polysilazane having a modification ratio satisfying a predetermined range, an aliphatic hydrocarbon solvent having a flash point within a predetermined range, and dibutyl ether at a predetermined blending ratio, imparts high hardness and hydrophobicity to the coating film, and have completed the present invention.

That is, the present invention is a coating agent composition for forming a high-hardness coating film, containing: (A) polysilazane which has a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2), and in which the ratio of the number of repeating units represented by the formula (2) to the total number of repeating units represented by the formula (1) and the formula (2) is 0.2 to 0.5; (B) an aliphatic hydrocarbon solvent having a flash point of 21 to 55 ℃; and (C) dibutyl ether, the amount of blending of the component (C) is 0.1-20% by mass relative to the total amount of the amounts of blending of the component (B) and the component (C).

Wherein R is a group selected from an aliphatic hydrocarbon group having 1 to 6 carbon atoms, an aromatic hydrocarbon group having 6 to 12 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms, and R in one molecule of polysilazane is the same or different.

The present invention will be described below with reference to embodiments thereof, which are merely illustrative examples, and the present invention is not limited thereto. Further, it goes without saying that various modifications may be made within a scope not departing from the technical idea of the present invention.

< coating agent composition for Forming high hardness coating film >

The coating agent composition for forming a high-hardness coating film of the present invention is a composition containing the component (a), the component (B), and the component (C) described later as essential components, and optionally containing the component (D) and other additives.

[ (A) ingredient: polysilazanes)

(A) The polysilazane as the component is a component which is cured to form a coating film (cured film).

The polysilazane used in the coating agent composition for forming a high-hardness coating film of the present invention has a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2).

In the formula (2), R is a group selected from an aliphatic hydrocarbon group having 1 to 6 carbon atoms, an aromatic hydrocarbon group having 6 to 12 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms. Preferably selected from the group consisting of aliphatic hydrocarbon groups having 1 to 3 carbon atoms, aromatic hydrocarbon groups having 6 to 8 carbon atoms, and alkoxy groups having 1 to 3 carbon atoms, and examples thereof include methyl, ethyl, phenyl, methoxy, and ethoxy groups. Among them, methyl groups are particularly preferable which are easy to handle and hardly cause a decrease in the hardness of the cured film. In a molecule of polysilazane, R in each repeating unit may be suitably selected, and R may be optionally the same or different.

The polysilazane is characterized in that the ratio of the number of repeating units represented by the formula (2) to the total number of repeating units represented by the formula (1) and the formula (2) is 0.2 to 0.5, preferably 0.3 to 0.4. If the amount is less than 0.2, the solubility in aliphatic hydrocarbons is poor, and if the amount is more than 0.5, the hardness of the cured film is lowered, which is not preferable.

Since the polysilazane contains the organic group R, the water contact angle (to be described later) can be 90 DEG or more (deg), and the polysilazane is excellent in water repellency.

In addition, the polysilazane has a weight average molecular weight of preferably 200 to 1,000,000, more preferably 500 to 100,000, and even more preferably 1,000 to 20,000, from the viewpoint of solubility in the component (B) as a diluting solvent component or workability in coating treatment. When the weight average molecular weight is 200 or more, the volatility is not high, and the organic solvent is hardly volatilized at the time of drying and surface treatment, and therefore the coating can be uniformly applied to the substrate, which is preferable. If the weight average molecular weight is 1,000,000 or less, the coating composition is preferably uniformly applied to a substrate because the coating composition has good solubility in an organic solvent and also has low dissolution viscosity.

The weight average molecular weight referred to herein means a weight average molecular weight obtained by Gel Permeation Chromatography (GPC) measured under the following conditions, using polystyrene as a standard.

[ measurement conditions ]

Developing solvent: tetrahydrofuran (THF)

Flow rate: 0.6 ml/min

A detector: UV detector

A chromatographic column: TSK GuardColumn SuperH-L

TSKgel SuperMultiporeHZ-M(4.6mml.D.×15cm×4)

(both manufactured by TOSOH CORPORATION)

Column temperature: 40 deg.C

Sample injection amount: 20 μ L (0.5% by mass in THF)

The polysiloxane having the repeating unit represented by the formula (1) and the repeating unit represented by the formula (2) may have a branched structure or a cyclic structure in addition to the repeating units.

In the polysilazane, the amount of the component (A) to be blended is preferably 0.1 to 20% by mass, more preferably 0.25 to 10% by mass, based on the total amount of the components (A) to (C) to be blended. Within this range, the coating property is good and a uniform cured film is formed.

[ (B) ingredient: aliphatic hydrocarbon solvent

The coating agent composition for forming a high-hardness coating film used in the present invention contains an aliphatic hydrocarbon solvent as a diluting solvent. In the present invention, the "aliphatic hydrocarbon solvent" refers to a solvent composed of an organic compound containing an aliphatic hydrocarbon as a main component.

The aliphatic hydrocarbon solvent is characterized by having a flash point in the range of 21 ℃ to 55 ℃, preferably in the range of 23 ℃ to 45 ℃. When the flash point is less than 21 ℃, special storage conditions are required, which is not preferable, and when the flash point is more than 55 ℃, the volatility of the solvent is lowered, and the workability is deteriorated, which is not preferable. In the present invention, when the aliphatic hydrocarbon solvent is a mixture of two or more types, "flash point" refers to the flash point of the component having the lowest flash point. The flash point can be measured by a method prescribed in JIS K2265, for example, by the Tager closed cup method (tag closed cup method) described in JIS K2265-1: 2007.

The aliphatic hydrocarbon solvent preferably contains at least one aliphatic hydrocarbon selected from aliphatic hydrocarbons having 9 to 12 carbon atoms. An aliphatic hydrocarbon solvent containing an aliphatic hydrocarbon within the above range is preferable because it has little influence on the environment and little odor, and is highly volatile, and therefore, it is excellent in handling properties.

Examples of the aliphatic hydrocarbon solvent include chain aliphatic hydrocarbons such as n-nonane, isononane, n-decane, isodecane, n-undecane, isoundecane, n-dodecane, and isododecane, and cyclic aliphatic hydrocarbons such as p-menthane, and isononane and isododecane are preferable because they have high volatility, little odor, and good handleability.

As long as the aliphatic hydrocarbon solvent has a flash point within the above range, a commercially available product can be used. Examples of such a solvent include Isopar G (44 ℃ C.), Isopar H (54 ℃ C.): manufactured by Exxon Mobil Corporation, KYOWASOL C-900(23.1 deg.C.): KH Neochem co., ltd., marukasl R (48 ℃), SWACLEAN 150(33 ℃): manufactured by Maruzen Petrochemical Co., Ltd, IP SOLVENT 1620(49 ℃ C.), IP CLEAN LX (45 ℃ C.): showa Shell, SPCN-40(44 ℃ C.), SP Clean100(53 ℃ C.): isu Chemical co., ltd. Wherein, the flash point is in parentheses. These solvents are classified into fourth class of flammable liquids of fire-fighting law, second class of petroleum water-insoluble liquids, and are easy to handle because storage conditions and the like are more loosely restricted than those of the first class of petroleum and the like having a lower flash point.

[ (C) ingredient: dibutyl ether ]

The coating agent composition for forming a high-hardness coating film used in the present invention is characterized by containing dibutyl ether to improve the solubility or storage stability of polysilazane and the wettability to a substrate.

The moisture content of the component (C) is preferably 1,000ppm or less, more preferably 500ppm or less. When the water content is 1,000ppm or less, the polysilazane does not react with water, and therefore does not cause heat generation, generation of hydrogen gas or ammonia gas, thickening, gelation, or the like, and thus is preferable.

The component (C) is characterized in that the amount of the component (C) is 0.1 to 20% by mass, preferably 0.35 to 15% by mass, based on the total amount of the components (B) and (C). If the amount is less than 0.1% by mass, the solubility of polysilazane in the aliphatic hydrocarbon solvent and the wettability of the coating agent composition to a substrate are not sufficient, which is not preferable, and if the amount is more than 20% by mass, the ether odor peculiar to dibutyl ether is increased, which may cause a problem in handling properties, which is not preferable.

[ (D) ingredient: curing catalyst)

The coating agent composition for forming a high-hardness coating film used in the present invention may further contain (D) a curing catalyst in addition to the components (a) to (C). Addition of a curing catalyst is preferable because a coating film can be formed even under unheated conditions such as outdoor environment or coating of an organic substrate having no heat resistance.

The curing catalyst is preferably an organosilicon compound having 1 or more alkoxysilyl groups (alkoxysilyl groups) and 1 or more amino groups in one molecule, or a compound containing a metal element.

Specific examples of the organosilicon compound include aminosilanes such as 3-aminopropylmethyldimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3- (2-aminoethylamino) propyltrimethoxysilane and 3- (2-aminoethylamino) propylmethyldiethoxysilane, and partial hydrolyzates of these aminosilanes, and 3-aminopropyltrimethoxysilane or 3-aminopropyltriethoxysilane is preferable because it has a high curing rate and excellent handling properties.

Specific examples of the metal element-containing compound include compounds containing metal elements such as titanium, aluminum, tin, zinc, and palladium, and preferably metal compounds of titanium or aluminum that are less likely to be colored.

The curing catalyst may be added alone, or 2 or 3 or more kinds may be added at an arbitrary ratio. The amount of the curing catalyst added is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, based on 100 parts by mass of the polysilazane as the component (A).

[ other ingredients ]

The coating agent composition for forming a high-hardness coating film used in the present invention may contain, depending on the purpose, components such as a leveling agent, an inorganic filler, a flame retardant, and a light absorbing agent, such as an alkoxy group-containing organosilicon compound, a silicone compound, and a low-molecular silazane structure-containing compound, in addition to the curing catalyst.

The total amount of other components added is preferably 0.1 to 200 parts by mass, more preferably 1 to 100 parts by mass, based on 100 parts by mass of the polysilazane as the component (A).

< method for Forming film >

The coating agent composition for forming a high-hardness coating film of the present invention can be used as it is for coating a substrate. Examples of the method for forming (coating) the coating agent composition for forming a high-hardness coating film include, but are not limited to, roll coating methods such as a closed blade coater (chamber coater), a single-roll kiss coater (one-roll kiss coater), a reverse kiss coater (reverse kiss coater), a bar coater (bar coater), a reverse roll coater (reverse roll coater), a forward roll coater (position roll coater), a blade coater, and a blade coater, spin coating methods, dispensing methods, dip coating methods, spray coating methods, transfer methods, and slit coating methods. When the above-described coating method cannot be used, a wipe coating method (a wipe き potting method), i.e., a dip dyed by dipping the coating agent composition for forming a high-hardness coating film into any cloth or paper, may be used to coat the base material.

Examples of the substrate to be coated include a silicon substrate, a glass substrate, a metal substrate, a resin-coated metal substrate, a resin film, and the like, and if necessary, the substrate may be coated on a semiconductor film or a substrate provided with a circuit or the like in a process of forming a semiconductor element. The thickness of the coating film varies depending on the purpose of use of the film, but is usually 10 to 100,000nm, preferably 100 to 1,000nm, in terms of the thickness of the cured film.

< curing method >

The method of forming a polysilazane resin coating film by applying the coating agent composition for forming a high-hardness coating film of the present invention by the above-mentioned film-forming method and then curing the formed coating film is not particularly limited, but drying and curing treatment are preferably performed. The purpose of this treatment is to completely remove the solvent contained in the coating film and to carry out a curing reaction to promote a conversion reaction from silazane bonds to siloxane bonds.

The temperature of the drying and curing treatment may be appropriately selected depending on the base material to be used, but is preferably 0 to 300 ℃, more preferably 25 to 150 ℃. The time of the drying and curing treatment varies depending on the treatment temperature, but it is 1 hour to 2 weeks.

In addition to heating, the drying/curing treatment may be performed by steam heating treatment, atmospheric pressure plasma treatment, low temperature plasma treatment, UV treatment, excimer light treatment, or the like. The selection can be made according to the combination with the substrate to which each corresponds.

< cured coating film >

For example, the coating agent composition for forming a high-hardness coating film of the present invention is cured by the above-mentioned curing method to form a cured coating film (cured film). The cured coating film is formed from a cured product of the coating agent composition, and therefore has high hardness and excellent hydrophobicity.

The pencil hardness of the cured film on the glass substrate is preferably 3H or more as measured by the method described in JIS K5600-5-4: 1999. Such a cured film is a coating film which is less likely to cause scratches and less conspicuous damage and has high design properties, and therefore is suitable for forming an antifouling coating film for transportation vehicles and an anti-damage coating film for living equipment such as sinks and sanitary wares.

Since the cured coating has high hardness and excellent hydrophobicity, a transportation vehicle provided with the cured coating has particularly excellent antifouling properties, scratch resistance, and hydrophobicity during rainy days and the like.

As described above, the coating agent composition for forming a high-hardness coating film of the present invention is dissolved in a highly safe organic solvent, has high storage stability, has good wettability to a substrate, and forms a high-hardness cured film having excellent hydrophobicity.

Examples

The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited thereto.

< preparation example of (A) polysilazane

PSZ-1 to PSZ-5 were prepared as polysilazanes having a methyl group in the following manner.

[ Polysilazane production-1 (PSZ-1) ]

0.04 mol of methyldichlorosilane was dropped into 300ml of dehydrated pyridine of-10 ℃ under stirring in a nitrogen atmosphere, and then 0.16 mol of dichlorosilane having a purity of 99% or more was blown into the pyridine together with nitrogen under stirring. Then, 0.60 mol of ammonia having a purity of 99% or more was blown, and the formed salt was removed by pressure filtration, thereby obtaining a polysilazane solution. The weight average molecular weight of the resulting polysilazane was 2,600.

The polysilazane solution was heated to 150 ℃ and 150ml of pyridine was distilled off. Subsequently, 300ml of dibutyl ether was added to remove pyridine by azeotropic distillation, and dibutyl ether (PSZ-1) was added so that the polysilazane was 20 mass% based on the whole solution.

[ Polysilazane production-2 (PSZ-2) ]

0.06 mol of methyldichlorosilane was dropped into 300ml of dehydrated pyridine of-10 ℃ under stirring in a nitrogen atmosphere, and then 0.14 mol of dichlorosilane having a purity of 99% or more was blown into the pyridine together with nitrogen under stirring. Then, 0.60 mol of ammonia having a purity of 99% or more was blown, and the formed salt was removed by pressure filtration, thereby obtaining a polysilazane solution. The weight average molecular weight of the resulting polysilazane was 2,000.

The polysilazane solution was heated to 150 ℃ and 150ml of pyridine was distilled off. Subsequently, 300ml of dibutyl ether was added, and pyridine was removed by azeotropic distillation, and dibutyl ether (PSZ-2) was added so that the polysilazane was 20 mass% based on the whole solution.

[ Polysilazane production-3 (PSZ-3) ]

0.10 mol of methyldichlorosilane was dropped into 300ml of dehydrated pyridine of-10 ℃ under stirring in a nitrogen atmosphere, and then 0.10 mol of dichlorosilane having a purity of 99% or more was blown into the pyridine together with nitrogen under stirring. Then, 0.60 mol of ammonia having a purity of 99% or more was blown, and the formed salt was removed by pressure filtration, thereby obtaining a polysilazane solution. The weight average molecular weight of the obtained polysilazane was 1,500.

The polysilazane solution was heated to 150 ℃ and 150ml of pyridine was distilled off. Subsequently, 300ml of dibutyl ether was added to remove pyridine by azeotropic distillation, and dibutyl ether (PSZ-3) was added so that the polysilazane was 20 mass% based on the whole solution.

[ Polysilazane production-4 (PSZ-4) ]

0.02 mol of methyldichlorosilane was dropped into 300ml of dehydrated pyridine of-10 ℃ under stirring in a nitrogen atmosphere, and then 0.18 mol of dichlorosilane having a purity of 99% or more was blown into the pyridine together with nitrogen under stirring. Then, 0.60 mol of ammonia having a purity of 99% or more was blown, and the formed salt was removed by pressure filtration, thereby obtaining a polysilazane solution. The weight average molecular weight of the resulting polysilazane was 2,900.

The polysilazane solution was heated to 150 ℃ and 150ml of pyridine was distilled off. Subsequently, 300ml of dibutyl ether was added, and pyridine was removed by azeotropic distillation, and dibutyl ether (PSZ-4) was added so that the polysilazane was 20 mass% based on the whole solution.

[ Polysilazane production-5 (PSZ-5) ]

0.12 mol of methyldichlorosilane was dropped into 300ml of dehydrated pyridine of-10 ℃ under stirring in a nitrogen atmosphere, and then 0.08 mol of dichlorosilane having a purity of 99% or more was blown into the pyridine together with nitrogen under stirring. Then, 0.60 mol of ammonia having a purity of 99% or more was blown, and the formed salt was removed by pressure filtration, thereby obtaining a polysilazane solution. The weight average molecular weight of the resulting polysilazane was 2,900.

The polysilazane solution was heated to 150 ℃ and 150ml of pyridine was distilled off. Then, 300ml of dibutyl ether was added to remove pyridine by azeotropic distillation, and dibutyl ether (PSZ-5) was added so that the polysilazane was 20 mass% based on the whole solution.

The following materials were used as components (B) to (D).

(B) Aliphatic hydrocarbon solvent

Isopar G: manufactured by Exxon Mobil Corporation (flash point: 44 ℃ C.)

KYOWASOL C-900: KH Neochem Co., Ltd. (flash point: 23.1 ℃ C.)

MARUKASOL R: manufactured by Maruzen Petrochemical Co., Ltd. (flash point: 48 ℃ C.)

Isopar L: manufactured by Exxon Mobil Corporation (flash point: 65 ℃ C.)

(C) Dibutyl ether: manufactured by Kanto Chemical Co., Inc. (flash point: 25 ℃ C.)

(D) Curing catalyst

KBE-903: 3-aminopropyltriethoxysilane: Shin-Etsu Chemical Co., Ltd

Examples 1 to 5 and comparative examples 1 to 5

A coating agent composition for forming a high-hardness coating film was prepared by blending polysilazane, an aliphatic hydrocarbon solvent, and dibutyl ether at the ratio (mass%) shown in table 1, and further adding 0.5 mass part of the curing catalyst shown in table 1 to 100 mass parts of polysilazane.

The prepared coating agent composition for forming a high-hardness coating film was coated on a glass substrate using a tissue paper (tissue paper), and allowed to stand for 1 week at 25 ℃/40% RH to obtain a cured coating film (cured film).

< introduction of methylsilane >

The ratio of the number of repeating units represented by formula (2) to the total number of repeating units represented by formula (1) and formula (2) in each polysilazane prepared is shown in table 1 as "methyl silane incorporation rate".

< evaluation of solubility >

The appearance of the coating agent compositions for forming a high-hardness coating film prepared in examples 1 to 5 and comparative examples 1 to 5 was visually observed. The color and transparency were indicated as "good", and the color with white turbidity and precipitation was indicated as "x". The results are shown in table 1.

< evaluation of odor >

5 panelists who had previously grasped the odor of dibutyl ether were prepared, and the odor of the coating agent compositions for forming a high-hardness coating film prepared in examples 1 to 5 and comparative examples 1 to 5 was smelled, and evaluated according to the number of panelists who felt the odor of dibutyl ether, according to the following evaluation criteria. The results are shown in table 1.

O: ether odor was observed in 0 to 1 cases.

X: more than 2 had an ether odor.

< evaluation of Water contact Angle >

The contact angle of the cured film on the glass substrate to water (20. mu.l) was measured using a contact angle measuring instrument Drop Master (manufactured by Kyowa Interface Science co., ltd.). The results are shown in table 1.

< evaluation of Pencil hardness >

The pencil hardness of the cured film on the glass substrate was measured by a pencil hardness tester (manufactured by pepalless co., ltd.) according to the method described in JIS K5600-5-4: 1999. The results are shown in table 1.

As shown in table 1, the coating agent compositions for forming a high-hardness coating film of examples 1 to 5 were superior in solubility in an aliphatic hydrocarbon solvent, as compared with the coating agent composition for forming a high-hardness coating film of comparative example 1, which had a methylsilane incorporation rate of 0.1, and the coating agent composition for forming a high-hardness coating film of comparative example 4, which did not contain dibutyl ether. Further, since the coating agent compositions of examples 1 to 5 contain an appropriate amount of dibutyl ether, the storage stability was good and the wettability to the substrate was also improved. From this, it is found that if the ratio of the repeating unit represented by formula (2) (methylsilane incorporation ratio) is too low (comparative example 1) or dibutyl ether is not contained (comparative example 4), the coating agent composition cannot be used as a coating agent composition, but the coating agent composition for forming a high-hardness coating film of the present invention has excellent solubility in aliphatic hydrocarbon solvents and good storage stability.

Furthermore, the pencil hardness of the cured films formed from the cured products of the coating agent compositions for forming a high-hardness coating film of examples 1 to 5 was higher than that of the cured films formed from the coating agent composition for forming a high-hardness coating film of comparative example 2 having a methylsilane incorporation rate of 0.6 and the coating agent composition for forming a high-hardness coating film of comparative example 3 containing an aliphatic hydrocarbon solvent having a flash point of 65 ℃. From this, it is understood that if the ratio of the repeating unit represented by formula (2) (methylsilane incorporation rate) is too high (comparative example 2) or the flash point of the aliphatic hydrocarbon solvent is too high (comparative example 3), the hardness of the cured film is lowered, but the coating agent composition for forming a high-hardness film of the present invention provides a cured film (coating film) having high hardness.

Further, it was found that the coating agent compositions for forming a high-hardness coating film of examples 1 to 5 had less odor than the coating agent composition for forming a high-hardness coating film of comparative example 5, which contained 30 mass% of dibutyl ether. From this, it is found that the coating agent composition for forming a high-hardness coating film of the present invention has less unpleasant odor and excellent workability, and is a coating agent that can be used in any place without limitation.

As described above, in the coating agent composition for forming a high-hardness coating film of the present invention, polysilazane for forming a coating film can be dissolved in an organic solvent having high safety such as low odor property and low toxicity, and therefore, the coating agent composition is excellent in handling property, improved in storage stability and wettability to a substrate, and imparted with high hardness and hydrophobicity to a cured film.

Industrial applicability

The coating agent composition for forming a high-hardness coating film of the present invention is soluble in highly safe organic solvents, has improved storage stability and wettability to a substrate, and can be suitably used as a coating agent for vehicle bodies, building exterior walls, and the like because it imparts excellent hydrophobicity and high hardness to a cured film.

The present invention is not limited to the above embodiments. The above embodiments are merely exemplary, and any embodiments having substantially the same configuration as the technical idea described in the claims of the present invention and exhibiting the same operational effects are included in the scope of the present invention.