KR20020011575A - Thermoset Hard Coating Composition Prepared Using Metal Alkoxide Silane - Google Patents

Abstract

PURPOSE: Provided is a thermosetting hard coating composition containing a metal alkoxide silane compound, which is excellent in storage stability and can be used for forming a coating film excellent in wetness, adhesive force, and hardness. CONSTITUTION: The thermosetting hard coating composition is produced by mixing 15-40wt% of the metal alkoxide silane compound represented by the formula 1, 15-30wt% of colloid silica, 30-60wt% of an organic solvent such as methanol and ethanol, 10-40wt% of water, and 0.01-8wt% of a hydrolysis catalyst such as hydrochloric acid and nitric acid and performing a hydrolysis at an ordinary temperature for 1-2 hours and then performing a polycondensation at a temperature of 40-80deg.C for 2-4 hours. In the formula, R and R' are hydrogen, alkyl, hydroxy, phenyl or an oxygen atom contained substituent and R'' is an alkyl group having a carbon less than C10 alkyl.

Description

Thermoset Hard Coating Composition Prepared Using Metal Alkoxide Silane}

The present invention relates to a thermosetting hard coating composition prepared by a sol-gel process, and more particularly to a thermosetting hard coating composition containing a polysiloxane component to form a coating film having excellent wettability and high hardness upon coating.

Plastic is widely used due to its light weight, excellent impact resistance and processability, but has a problem of low surface hardness and poor weather resistance and chemical resistance. to be. Therefore, research has been conducted to solve the above problems while maintaining the inherent physical properties of the plastic by applying various coatings on the surface of the plastic.

On the other hand, since the silicone-based coating agent prepared mainly from the organic silane (silane) has excellent chemical, physical and electrical properties, it has been applied to various fields such as electrical, electronic, aviation industry, building materials.

In particular, thermosetting coatings are mainly applied to plastics for the electrical, electronic and aviation industries because they can increase the hardness on the coated surface as much as possible, greatly improve weather resistance and wettability, as well as increase chemical resistance. have. As such a hard coating agent, Korean Patent Publication No. 99-75175 is prepared by mixing a conductive polymer solution and a silica sol solution in an appropriate ratio, and discloses a polymer hard coating composition satisfying both transparency and conductivity, Or when coating on a transparent substrate such as a synthetic resin film has excellent conductivity, transparency and film hardness of 5 to 8H, it is disclosed that it can form a polymer hard coating film that can be applied for electromagnetic shielding and antistatic applications . In the present invention, excellent conductivity and membrane properties may be obtained by mixing the conductive polymer aqueous solution and the silica sol solution at a specific ratio, but when tetraethoxysilane (TEOS), which is a component of the silica sol, is used alone, adhesion and membrane It was difficult to satisfy all the film conditions such as hardness, appearance, and wettability. Korean Patent Publication No. 2000-19871 discloses a method for producing a conductive organic-inorganic hybrid coating liquid prepared by mixing a water-soluble conductive polymer solution, tetraethoxysilane as a raw material of silica sol, and an alcohol solvent in an appropriate ratio. Since the said invention only uses tetraethoxysilane independently, the film | membrane characteristic was not satisfactory. In addition, Korean Patent Publication No. 99-61673 discloses a weather resistance by including a copolymer containing a hydroxy group and a hydrolyzable silyl group in an acrylic main chain, a copolymer containing a small amount of a carboxyl group and an amine group in an acrylic main chain, and a heat curing agent. Disclosed is a thermosetting silicone crosslinkable resin composition excellent in chemical resistance, adhesion, corrosion resistance, storage stability, and stain resistance. However, the present invention includes a plurality of polymerization stages, and the polymerization stage of the components has a complicated disadvantage.

In general, the conditions of the thermosetting coating agent (1) the surface hardness of the coating surface should be greatly improved, and (2) the coating material should be firmly attached and bonded to the plastic to improve the weather resistance and chemical resistance of the coating surface. However, since the film used as the thermosetting coating film mainly consists of a polymer resin system, there are many cases in which the use of the thermosetting coating film is limited due to problems of durability and abrasion resistance that occur when mounted for a long time. In order to compensate the above disadvantages, 1) a method of properly adjusting the ratio of the silane of the 2, 3, 4 functional group in consideration of the hardness and properties of the hard coating agent according to the subject, 2) the organic group and the alkoxy group of the silane compound A method of making a kind of catalyst a basic composition of a thermosetting hard coating agent, and 3) a method of controlling physical properties of a coating film by adding a curing catalyst, a diluent leveling agent, a surfactant, and a UV absorber have been developed and applied. However, in the method of 1), although the strength of the coating film is improved and the film is dense, the surface property can be firmly exhibited, but there is a problem in that the flexibility is lowered, and there are many process difficulties in order to control each functional group. In addition, the method of 2) can obtain a thermosetting hard coating having excellent stability, such as workability and storage property, compared to using an organic catalyst, but has a problem in durability. The method of 3) may improve the physical properties of the thermosetting hard coating agent, but has a disadvantage in that it is economically poor because various additives must be used.

Therefore, recently, in order to solve the above problems, research on the development of a thermosetting resin and a coating process having hardness, weather resistance, and adhesiveness through inorganic coating has been continuously conducted. The most prominent field is the thermosetting hard coating film produced by the sol-gel method. However, since the thermosetting coating prepared by the sol-gel method is affected by the type and amount of the catalyst in the solution, the type of the silane compound used, the type of the functional group, the concentration and the acidity, and the like, the properties of the final resin are different. And the shelf life of the solution varies greatly.

Therefore, there is an urgent need for a technique capable of preparing a compound having excellent storage stability by appropriately adjusting the various factors in order to obtain the best physical properties.

In contrast, the present inventors have developed a hard coating composition obtained by hydrolyzing and polycondensing a metal alkoxide silane compound in the presence of water, an organic solvent, colloidal silica, and a hydrolysis catalyst, wherein the coating composition is a polycarbonate sheet. Or a methyl methacrylate (PMMA) resin, it was found that a hard coating film having excellent properties such as adhesion, film hardness, and appearance can be obtained.

Accordingly, an object of the present invention is to provide a thermosetting hard coating composition having good storage stability and which can be prepared by a relatively simple manufacturing process.

Another object of the present invention is to provide a thermosetting hard coating composition which forms a thermosetting coating film having excellent wettability and high hardness when coated on a subject.

In order to achieve the above and other objects, the thermosetting hard coating composition of the present invention is based on the total weight of the final composition, 15 to 40% by weight of the metal alkoxide silane compound represented by Formula 1, 15 to 30% by weight of colloidal silica, organic Prepared by mixing and hydrolyzing 30 to 60% by weight of solvent, 10 to 40% by weight of water and 0.01 to 8% by weight of hydrolysis catalyst followed by condensation polymerization:

Formula 1

R and R 'in the formula are hydrogen, alkyl group, hydroxy group, phenyl group or oxygen atom containing substituent group; R or R 'may be substituted with the same compound; And R ″ is an alkyl group having no more than C ₁₀ .

Hereinafter, the content of the present invention will be described in detail.

More specifically, the thermosetting hard coating composition of the present invention hydrolyzes the metal alkoxide silane compound for 1 to 2 hours at room temperature in the presence of an organic solvent, water, colloidal silica, and a hydrolysis catalyst, and then, in the temperature range of 40 to 80 ° C. Prepared by condensation polymerization for 2 to 4 hours, based on the total weight of the final hard coating composition, 15 to 40% by weight of the metal alkoxide silane compound, 30 to 60% by weight of organic solvent, 10 to 40% by weight of water, 20 to 35% by weight colloidal silica and 0.01 to 8% by weight hydrolysis catalyst are used. In this process, the resulting hard coating composition is present in a silica-sol state suitable for application to the subject. One specific example of the hydrolysis and polycondensation reaction can be represented by the following scheme.

Scheme

R ″ in the above scheme is the same as that of formula (1).

Representative examples of the metal alkoxide silane compound used in the present invention include tetraethoxysilane (TEOS), methyltrimethoxysilane (MTMS), etc., and 15 to 40% by weight, preferably 20 based on the total weight of the final composition. 35 weight% is used. If the amount of the metal alkoxide silane compound is less than 15% by weight, the desired effect cannot be achieved. If the amount of the metal alkoxide silane compound is greater than 40% by weight, the physical properties of the thermosetting coating film are greatly reduced, which is not preferable.

Organic solvents used in thermosetting hard coating compositions include those commonly known in the art, such as methanol, ethanol, isopropyl alcohol, chloroform, toluene, benzene, hexane, or mixtures thereof. It is not limited. At this time, the amount of the organic solvent used is 30 to 60% by weight, preferably 40 to 54% by weight based on the total weight of the final composition. When the organic solvent is used in less than 30% by weight in the final composition, the spreadability is lowered, the coating is difficult, and when the organic solvent exceeds 60% by weight there is a problem that the resulting coating film becomes cloudy.

In addition, as the hydrolysis catalyst, a conventional catalyst known in the art may be used, and representative examples of the catalyst include hydrochloric acid, nitric acid, sulfuric acid, acetic acid, or a mixture thereof.

As the colloidal silica, an aqueous colloidal silica dispersion containing 10 to 40% of silica particles having a particle diameter of 5 to 40 μm may be used, and the amount of the colloidal silica is 15 to 35% by weight, preferably based on the total weight of the final hard coating composition. Is in the range of 20 to 30% by weight. In this case, when the amount of colloidal silica is less than 15% by weight, the hardness of the surface of the coating film after coating and curing is significantly reduced, and when it exceeds 35% by weight, cracks occur when the coating film is generated. There is.

In addition, water is used in the range of 10 to 40% by weight, preferably 15 to 35% by weight, based on the total weight of the composition. When water is used at less than 10% by weight, a substance having a sufficient molecular weight cannot be produced, and when 40% by weight is exceeded, the molecular weight increases too much to cause gelation.

The manufacturing process of the hard coating composition is simple and has excellent storage stability. In addition, the polycarbonate sheet, polymethyl methacrylate (PMMA) resin coated using the composition has a high surface hardness, and at the same time has the advantage of excellent weather resistance, chemical resistance and wettability that can be used for a long time.

The present invention can be more clearly understood by the following examples, which are only intended to illustrate the present invention and are not intended to limit the scope of the invention.

Example 1

In a three-necked flask reactor with a stirrer, 51 parts by weight in solution A consisting of 45% by weight of tetradoxysilane (TEOS) compound of Aldrich Chem. Co. and 55% by weight of ethanol was maintained at a temperature of 25 ° C. In the course of stirring for about 20 minutes, an aqueous colloidal silica dispersion containing 30% by weight of silica particles having a particle diameter of 5 to 40 µm was added and mixed with 24 parts by weight of colloidal silica. 20 parts by weight of water and 5 parts by weight of acetic acid were added dropwise to the mixture for about 1 hour with good stirring, followed by hydrolysis while stirring at room temperature for about 1 hour, and condensation polymerization at 60 ° C. for about 2 hours to give a silica-sol state. Solution B was prepared.

Examples 2-8

Except for changing the composition and blending ratio of the components in Example 1 as shown in Table 1 was carried out in the same manner as in Example 1, to prepare a variety of thermosetting hard coating resin compositions.

ingredient Example One 2 3 4 5 6 7 8 Solution A Alkoxide silane (% by weight) Tetraethoxy silane 45 43 42 25 25 25 0 0 Methyltrimethoxy silane 20 18 17 43 45 Ethanol (% by weight) 55 57 58 55 57 58 57 55 Solution B Solution A (parts by weight) 51 50 49 51 50 50 50 49 Colloidal silica (parts by weight) 24 25 26 24 25 26 25 26 Water (parts by weight) 20 20 20 20 20 20 20 20 Acetic acid (parts by weight) 5 5 5 5 5 5 5 5

Comparative Example 1

Tetraethoxy silane (Aldrich Chem. Co.) and ethanol were mixed at a weight ratio of 7:93, stirred for about 30 minutes, and then 0.5% by weight of hydrochloric acid was added, followed by stirring for 16 hours to obtain a silica-sol solution.

Comparative Example 2

A silica-sol solution was obtained under the same experimental conditions as in Comparative Example 1 except that methyltrimethoxy silane (Aldrich Chem. Co.) was used.

Comparative Example 3

After mixing 30% by weight of tetraethoxy silane (Aldrich Chem. Co.) and 70% by weight of ethanol for about 1 hour based on the final product weight, 1% by weight of water and 1% by weight of hydrochloric acid are added to the premixed solution. Mixed. Then, the mixture was stirred in a closed state for 24 hours to sufficiently proceed the hydrolysis and polymerization reaction to prepare a thermosetting hard coating composition.

Example 4

Evaluation of physical properties

The thermosetting hard coating agents of Examples 1 to 8 and Comparative Examples 1 to 3 were each 3 mm thick. A 10 cm × 10 cm sized transparent polycarbonate sheet was coated using a dipping method at a pulling speed of 10 cm / min, then dried at room temperature for about 5 to 10 minutes, and then heated at about 130 ° C. in a heating furnace. Heat treatment was performed for 20-30 minutes. Then, natural cooling at room temperature to form a thermosetting hard coating film on the polycarbonate plate.

The physical properties of the hard-coated polycarbonate specimen as described above were measured by the following items and methods, and the results are shown in Table 2 below. Measurement items and measuring methods are as follows.

The state of the film: The surface condition of the coating film on the specimen was visually investigated by considering the coating uniformity, haze or crack generation, and was very good (◎), good (○), normal (△) and poor (× And separated by).

Surface Hardness: Using the pencil with hardness of 9H-H, F, HB, B-6B, etc., place it face up the manufactured film under constant load, and then hold the pencil at about 45 ° and push it at a constant speed. It was.

Adhesive force: 100 checkerboard scales were made on the surface of the specimen at 2 mm intervals, and then the cellophane adhesive tape was sufficiently pressed and pulled in 90 ° direction at once to examine the relative peeling state between the substrate and the coating film.

Adhesion Pencil hardness Exterior Wetting (Glass Specimen) Example 1 0/100 4H ○ Good Example 2 0/100 4H ◎ Good Example 3 0/100 4H ◎ Good Example 4 1/100 4H ○ Good Example 5 1/100 5H ○ Good Example 6 1/100 7H (some cracks) ○ Good Example 7 5/100 7H ○ Good Example 8 5/100 7H ○ Good Comparative Example 1 6/100 4H △ Good Comparative Example 2 20/100 3H △ Good Comparative Example 3 10/100 4H ○ Good

As can be seen from the table, as in Comparative Examples 1 and 2, the hard coating composition hydrolyzed and condensed by simply adding water, an organic solvent and an acid catalyst to the metal alkoxide silane compound had good wettability, but adhesion and appearance. It was not good compared with Examples 1-8 in terms of surface, and it turned out that pencil hardness is also equal or less. In addition, in Comparative Example 3, when the hard coating composition containing no colloidal silica was used, it was found that the adhesive strength with the subject was lowered as compared with Examples 1 to 8.

The thermosetting hard coating composition comprising the metal alkoxide silane compound and the colloidal silica compound of the present invention is not only easy to manufacture and excellent in storage stability, but also has excellent adhesion and hardness when coated on a coating such as a polycarbonate resin. The branches form a coating film.

Simple modifications and variations of the present invention can be readily used by those skilled in the art, and all such variations or modifications can be considered to be included within the scope of the present invention.

Claims (6)

Based on the total weight of the final composition, 15 to 40% by weight of the metal alkoxide silane compound represented by the following formula (1), 15 to 30% by weight of colloidal silica, 30 to 60% by weight of organic solvent, 10 to 40% by weight of water, and hydrolysis A thermosetting hard coating composition, prepared by mixing hydrolysis and polycondensation by mixing 0.01 to 8% by weight of a catalyst: Formula 1 R and R 'in the formula are hydrogen, alkyl group, hydroxy group, phenyl group or oxygen atom containing substituent group; R and R 'may be substituted with the same compound; And R ″ is an alkyl group having no more than C ₁₀ . According to claim 1, wherein the thermosetting hard coating composition is 15 to 40% by weight of the metal alkoxide silane compound based on the total weight of the final composition 15 to 30% by weight of the colloidal silica, 30 to 60% by weight organic solvent, water 10 to 40 Thermosetting hard coating composition, characterized in that prepared by hydrolysis at room temperature for 1 to 2 hours in the presence of 0.01% to 8% by weight of the hydrolysis catalyst, and polycondensation reaction at 40 to 80 ℃ for 2 to 4 hours The thermosetting hard coating composition of claim 1, wherein the hydrolysis catalyst is selected from the group consisting of hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, acetic acid, and mixtures thereof. The thermosetting hard coating composition of claim 1, wherein the organic solvent is selected from the group consisting of methanol, ethanol, isopropyl alcohol, chloroform, toluene, benzene, hexane, and mixtures thereof. The thermosetting hard coating composition of claim 1, wherein the colloidal silica is an aqueous colloidal silica dispersion having a particle diameter of 5 to 30 μm and containing 10 to 40% by weight of silica fine particles. A polycarbonate or polymethacrylate resin product prepared by applying the thermosetting hard coating composition of any one of claims 1 to 5.