KR20120022200A - Silicon-based abrasion coating compositions containing curing catalysts which have condensable functional groups - Google Patents

Abstract

PURPOSE: A silicon-based coating composition with wear resistance including solidifying catalyst with condensable group is provided to lengthen gelation time which shows storage stability of coating agent and remarkably increase low temperature cross hardening and storage ability. CONSTITUTION: A silicon-based coating composition with wear resistance comprises a mixture consisting of partial condensate of silanol which forms methylpolysiloxane and colloid silica dispersion and 0.02-2.5 weight% of trialkoxysilyl amine or trialkoxysilyl ammonium salt based on solid content of the mixture. A mixing ratio of the partial condensate to colloidal silica dispersion liquid of silanol is 30-80 : 20-70 weight ratios.

Description

Silicon-based abrasion coating compositions containing curing catalysts which have condensable functional groups

The present invention relates to a wear resistant silicone coating composition comprising a curing catalyst having a condensable functional group, and particularly to a trialkoxysilyl amine or trialkoxysilyl ammonium salt having a condensable functional group as a curing catalyst in a partial condensate of silanol and a colloidal silica dispersion. In this case, all the reactants have a silanol group after hydrolysis, so that the compatibility is excellent, and after curing, the catalyst forms a covalent bond with the product to reduce the physical properties of the product as a foreign substance or to prevent separation during use. A wear-resistant silicone coating composition comprising a curing catalyst having a functional group.

Generally, automotive parts such as headlamp lenses, optical materials such as eyeglasses, building materials such as windows, electrical materials such as various kitchen utensils and display covers, etc., have optical properties to prevent deterioration of flaws and transparency due to frequent contact. Wear-resistant coatings using excellent polymethyl methacrylate resins, polycarbonate resins, and the like are essentially used.

The wear-resistant coating of various transparent or opaque plastics improves the wear resistance, which is a weak point of the plastic, without changing the mechanical and physical properties such as fracture strength, impact strength, specific gravity, light transmittance, etc. As a method, the method of coating a hard film on a plastic surface is used normally.

In addition, even in the case of a metal substrate, there is a need for a coating agent capable of improving surface hardness and improving storage stability while satisfying adhesion.

An object of the present invention is to use a curing catalyst having a condensable functional group and to form a coating composition composed of a partial condensate of silanol and a colloidal silica dispersion, thereby preventing the catalyst from leaving after curing due to the curing catalyst having a condensable functional group. In addition, the present invention provides a wear-resistant silicone coating composition comprising a curing catalyst having a condensable functional group having improved abrasion resistance and adhesion.

The present invention for achieving the above object is a mixture consisting of a partial condensate of a silanol and a colloidal silica dispersion forming a methylpolysiloxane, and a curing having a condensable functional group of 0.02 to 2.5% by weight based on the solids content of the mixture It is characterized by containing a trialkoxysilyl amine or trialkoxysilyl ammonium salt which is a catalyst.

When the partial condensate of the silanol and the colloidal silica dispersion are mixed, the ratio of the partial condensate of the silanol and the colloidal silica dispersion is mixed in a weight ratio of 30 to 80:20 to 70.

The particle size of the colloidal silica dispersion is 2 ~ 30nm.

A diluent is added to the mixture of the partial condensate of silanol and the colloidal silica dispersion,

The dosage of the diluent is adjusted so that the solids content of the total composition is 5-45% by weight.

The diluent is selected from one kind or two or more kinds of polar solvents that can be mixed with water, alkanols having 1 to 8 carbon atoms or mixtures thereof, and water.

The diluent is one or two selected from n-butanol, 2-ethoxyethanol, methanol, ethanol, propanol, isopropanol, isobutanol, t-butanol, dimethylformamide, dimethyl sulfoxide, acetone and methyl cellosolves. Adopted a mixture of the above,

The diluent is 55 to 95% by weight of the total composition.

The present invention relates to a silicone-based coating composition wherein a condensation functional curing catalyst, trialkoxysilyl amine or trialkoxysilyl ammonium salt, is added to a coating mixture of a partial condensate of silanol and a colloidal silica dispersion. When the gelation time of storage stability is increased and the curing catalyst having a condensation functional group can prevent the separation of the catalyst after curing, low-temperature crosslinking curing and storage properties are greatly improved, and thus automobile parts, optical materials, building materials, and kitchen utensils are greatly improved. And it has a very useful effect that can be applied to various fields such as electrical materials.

In order to improve the wear resistance of plastic materials, a colloidal silica dispersion or silica gel such as silica gel is added to a solvent such as water and alcohol, which are hydrolysis media, and then mixed with a silicon alkoxide which can be hydrolyzed. Can be formed.

When coating polymetal methacrylate or polyacrylimide resin, primer treatment is not required.However, since the adhesion between the polycarbonate resin and the coating agent is weak, when the polycarbonate resin is coated, the polycarbonate resin and the silicone-based anti-wear coating agent are used. In order to improve the adhesiveness of the acrylic resin is used as a primer.

The wear-resistant coating composition uses a silicon alkoxide monomer, a trifunctional monomer, and tetraethoxysilane, a tetrafunctional monomer, increases wear resistance, but cracks occur due to warpage or impact transmitted from the outside when the coating agent is dried and used. Not desirable

The silicone-based coating composition forms a polysiloxane, which may use a curing catalyst having a condensable functional group to lower the curing temperature of the polysiloxane and shorten the curing time.

The curing catalyst having a condensable functional group is required to delay the condensation reaction during storage of the coating agent to prevent gelation and to promote the condensation reaction upon heating after being coated on a plastic or metal substrate.

Suitable catalysts include alkali metal salts of carboxylic acids (e.g. sodium acetate, potassium acetate, etc.), amine carboxylates (e.g. dimethylamine acetate, ethanolamine acetate, dimethylaniline formate, etc.), quaternary ammonium carboxyl Rate (e.g. tin octoate, etc.), amines (e.g. triethylamine, triethanolimine, pyridine, etc.) and alkali hydroxides (e.g. sodium hydroxide, ammonium hydroxide, etc.).

However, the above curing catalysts have a short gelling time during storage of the coating agent, resulting in poor storage stability, difficult cross-linking curing at low temperatures, and poor curing and poor adhesion in plastics having a low glass transition temperature.

Accordingly, the present invention is to provide a wear-resistant silicone-based coating composition comprising a curing catalyst having a condensable functional group that improves the storage stability of the coating agent while preventing the separation of the catalyst after curing, and improved wear resistance and adhesion.

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

The wear resistant silicone-based coating composition comprising a curing catalyst having a condensable functional group according to the present invention is a mixture consisting of a partial condensate of silanol forming a methylpolysiloxane and a colloidal silica dispersion, and a curing catalyst having a condensable functional group in the mixture. Trialkoxysilyl amine or trialkoxysilyl ammonium salt.

The mixing ratio at the time of mixing the partial condensate of silanol and colloidal silica dispersion in the said mixture is mixed by the weight ratio of the partial condensate of silanol (30-80): colloidal silica dispersion (20-70).

When the proportion of the partial condensate of silanol is less than 30%, cracks occur in the coating layer, and when the partial condensate exceeds 80%, abrasion resistance is lowered. Therefore, mixing within the above range is preferable.

In addition, the composition of the present invention is added to these mixtures, but diluent is adjusted so that the solids content of the total composition is 5 to 45% by weight.

Here, the solid content means a component that remains as a solid after curing, and refers to silica except for water in alkyltrialkoxysilane and colloidal silica.

More strictly, the trialkoxysilyl amine or trialkoxysilyl ammonium salt used as a curing catalyst is also included, but since the quantity is insignificant, it can be ignored.

The particle size of the colloidal silica dispersion may be adopted to have an average particle diameter of 1 ~ 150nm, it is preferable to use a particle diameter of 2 ~ 30nm for good storage stability.

Types of colloidal silica dispersions include acidic hydrosols and basic hydrosols, both colloidal silica dispersions which may be used but have a lower alkali content (e.g. silica containing 1% by weight or less of Na ₂ O). Produces a stable coating composition.

In addition, in order to increase the packing density of the colloidal silica dispersion and improve abrasion resistance, colloidal particles having different particle diameters may be mixed and used.

The trialkoxysilyl amine or trialkoxysilyl ammonium salt, which is a curing catalyst having a condensable functional group of the present invention, has a function of lowering the curing temperature of the polysiloxane, shortening the curing time, and enhancing adhesion between the coating film and the substrate.

In addition, the amount of the curing catalyst having a condensable functional group of the present invention can be adjusted according to the desired curing conditions, it is preferably added in a ratio of 0.02 ~ 2.5% by weight based on the solids content of the mixture.

This is because when the amount of the curing catalyst is less than 0.02% by weight, there is a problem that hardening does not occur because the effect of the catalyst is not observed, and when the content is more than 2.5% by weight, the adhesion between the coating film and the substrate becomes weak. It is preferable to add within.

In order to obtain a partial condensate of silanol in the mixture, it is preferable to add acetic acid to the alkyltrialkoxysilane, and hydrolyze in an aqueous dispersion of colloidal silica to mature for 2 to 3 hours or more.

Alkyltrialkoxysilane satisfies the following formula.

In Formula 1, R is an alkyl group having 1 to 3 carbon atoms or an aryl group having 6 to 13 carbon atoms, and R 'is an alkyl group having 1 to 3 carbon atoms.

Such a hydrolysis reaction of the present invention can be represented by the following reaction formula 1 when R is a methyl group in Formula 1, the partial condensate of silanol is shown in Scheme 1 below.

Scheme 1

On the other hand, the solid content of the partial condensate of silanol and the colloidal silica dispersion is adjusted by varying the input amount of the diluent.

The amount of the diluent is preferably added in an amount of 55 to 95% by weight based on the total composition, and when the diluent is less than 55% by weight, the thickness of the coating film is so thick that cracking may easily occur, and exceeds 95% by weight. In this case, since the thickness becomes too thin and the wear resistance decreases, it is preferable to inject it within the above range.

As a diluent, one or two or more kinds of polar solvents that can be mixed with water and alkanols having 1 to 8 carbon atoms or mixtures thereof and mixed with water can be used.Also, alcohols are about 20 to 80 to sufficiently dissolve the partial condensate. It should be contained in weight percent.

In the present invention, isopropanol and n-butanol are added as diluents to adjust the solids content. Other suitable alcohols that may be used are lower aliphatic alcohols such as methanol, ethanol, propanol, 2-ethoxyethanol, isobutanol and t-butanol, and these alcohols may be used in combination.

In addition, polar solvents that may be mixed with water in the diluent include dimethylformamide, dimethyl sulfoxide, acetone, methyl cellosolve, and the like, and may be used in less than 20% by weight of the mixed solvent system.

On the other hand, the final composition of the present invention is used to adjust the pH to about 3.5 to 8.0 using acetic acid, more preferably about 5.0 to 6.5. If necessary, a weak base (eg ammonium hydroxide) or a weak acid (eg acetic acid) can be added to the composition to adjust the pH to the desired range.

When the pH is too small or too large, the storage stability is lowered, so it is preferable to adjust the above range.

Such a coating composition of the present invention can be prepared as follows.

The wear resistant coating composition of the present invention is prepared by hydrolyzing an alkyltrialkoxysilane in the presence of a colloidal silica dispersion followed by condensation polymerization.

A small amount of alkyltrialkoxysilane and acetic acid are mixed and an aqueous colloidal silica dispersion is added to this solution. The temperature of the reaction mixture is maintained at about 0-40 ° C.

When the alkyltrialkoxysilane is sufficiently hydrolyzed for about 6 to 8 hours, the initial two-phase liquid mixture becomes a single liquid phase. The general hydrolysis reaction is carried out continuously for about 12-48 hours, which depends on the desired viscosity of the final product and the longer the duration of the hydrolysis reaction, the higher the viscosity of the product. Upon completion of the hydrolysis, a polysiloxane can be obtained, which is diluted with the solvent described above to add a trialkoxysilyl amine or trialkoxysilyl ammonium salt, which is a curing catalyst having a condensable functional group, and add acetic acid to bring the pH to about 5.0 to 6.5. Adjustments can be made to the coating composition.

The coating composition prepared is cured on a solid substrate in a relatively short time at a temperature of about 75-150 ° C. to form a transparent wear resistant coating.

The coating composition of the present invention obtained above can be used for various solid substrates by conventional methods such as flowing, spraying, dipping, etc. to form the surface film.

Substrates for use in the present invention are plastics and metals, in particular plastics are acrylic polymers such as polymethylmethacrylate, polycarbonates, polyamides, polyimides, acrylonitrile-styrene copolymers, styrene-acrylonitrile-butadiene air Synthetic organic polymer substrates such as coalesce, polyvinylchloride, polyethylene, polyester and the like.

Hereinafter, the present invention will be described with reference to Examples, but the present invention is not limited thereto.

The trialkoxysilyl amine of the present invention is represented by the following formula (2),

In Formula 1, R ₁ is hydrogen or an alkyl group having 1 to 3 carbon atoms or an aryl group having 6 to 13 carbon atoms, R ₂ is an alkylene group having 1 to 8 carbon atoms, and R ₃ is an alkyl group having 1 to 3 carbon atoms.

In addition, the trialkoxysilyl ammonium salt of the present invention is represented by the following formula (3),

In Chemical Formula 2, R ₁ is hydrogen or an alkyl group having 1 to 3 carbon atoms or an aryl group having 6 to 13 carbon atoms, R ₂ is an alkylene group having 1 to 8 carbon atoms, R ₃ is an alkyl group having 1 to 3 carbon atoms, and X ⁻ Is an acetate, carbonate, bicarbonate, or hydroxide anion.

Examples and Comparative Examples

To prepare the composition as shown in Table 1, in Examples (1-1, 1-2, 1-3) 3- (trimethoxy, which is a trialkoxysilyl amine or trialkoxysilyl ammonium salt which is a curing catalyst having a condensable functional group Silyl) propan-1-amine, N, N-dimethyl-3- (trimethoxysilyl) propan-1-amine, N, N, N-trimethyl-3- (trimethoxysilyl) propane-1-ammonium acetate In Comparative Examples (1-1, 1-2, 1-3, 1-4), hydrochloric acid, sodium acetate, potassium t-butoxide and dimethylbenzylamine were prepared by the following method.

Methyltrimethoxysilane and acetic acid were put into a stirrer and stirred at a temperature of 0 ° C.

And while maintaining the temperature of 0 ℃ colloidal silica dispersion (Ludox LS-30, particle size: 12 nm, pH 8.4, SiO ₂ / Na ₂ O = 30 / 0.1% by weight) was slowly added while stirring. After all were added dropwise, the reaction was continued for 24 hours to obtain a methylpolysiloxane mixture. Isopropanol and n-butanol were added to this methyl polysiloxane mixture for dilution, followed by addition of a curing catalyst. This solution was titrated to pH 5.6 with acetic acid to prepare a wear resistant coating solution.

In order to observe the gelation time of the solution prepared above, that is, storage stability, the gelation time of the room temperature storage state was measured, and the results are shown in Table 1 below.

Composition ingredient (g) Example Comparative example 1-1 1-2 1-3 1-1 1-2 1-3 1-4 Curing catalyst 3- (trimethoxysilyl) propan-1-amine 0.2 N, N-dimethyl-3- (trimethoxysilyl) propan-1-amine 0.2 N, N, N-trimethyl-3- (trimethoxysilyl) propane-1-ammonium acetate 0.2 Hydrochloric acid 0.2 Sodium acetate 0.2 Potassium t-butoxide 0.2 Dimethylbenzylamine 0.2 Acetic acid 1.6 1.6 1.6 1.6 1.6 1.6 1.6 Methyltrimethoxysilane 20 20 20 20 20 20 20 Colloidal Silica Dispersion 20 20 20 20 20 20 20 menstruum Isopropanol 30 30 30 30 30 30 30 n-butanol 30 30 30 30 30 30 30 Storage safety (gel time) 150 days 160 days 180 days 8 hours 54 days 2 days 87 days

As shown in Table 1, Examples (1-1, 1-2, 1-3) have improved storage safety compared to Comparative Examples (1-1, 1-2, 1-3, 1-4). It can save quite a long time.

Experimental Example 2 Abrasion Resistance and Adhesion Test

Test Methods

① How to measure wear resistance

In order to perform abrasion test of a specimen coated with a polycarbonate or polymethyl methacrylate resin having a wear resistance of 2 mm (9 cm x 9 cm), a load of 250 g was added using a taper wear machine (Model-5130, Taber) 100 cycles were worn using the wheel CS-10. It measured using% haze before abrasion, and% haze after abrasion.

② Measuring method of adhesion

The adhesion of the specimens with abrasion resistant coatings was measured by a cross cut test, using a cutter with six blades from BYK-Gardner to draw six parallel lines on the coated surface at 2 mm intervals, again perpendicular to them. Drew a line. The 3M Scotch tape was attached to the cut coating surface and the tape was quickly removed from the coated surface with the tape and coated surface at an angle of 90 ^° . This method was performed three times to observe whether the coating adhered to the polycarbonate or polymethylmethacrylate resin.

Example 2

To prepare a composition as shown in Table 2, the ratio of colloidal silica dispersion / methyltrimethoxysilane (weight ratio) was 20/80, 50/50, 60/40 and 70/30, respectively. The prepared wear-resistant coating solution was filtered using Whatman filter paper, and the polycarbonate resin was washed with isopropanol before drying, dried, and then the acrylic resin primer was poured on the surface of the polycarbonate resin and maintained at 90 ° C. in a drying oven for 20 minutes. After drying, the filtered coating solution was poured into a polycarbonate resin coated with an acrylic resin primer, dried at room temperature for 5 minutes, and cured by heating for 1 hour while maintaining at 90 ° C. in a drying oven. The above abrasion resistance and adhesion were tested for comparison with an uncoated polycarbonate plate (δ% haze value = 23.77), and the measurement results of the examples showed good wear resistance and adhesion as shown in Table 2 below. .

Composition ingredient (g) Example 2-1 2-2 2-3 2-4 Curing catalyst N, N, N-trimethyl-3- (trimethoxysilyl) propane-1-ammonium acetate 0.2 0.2 0.2 0.2 Acetic acid 1.6 1.6 1.6 1.6 Methyltrimethoxysilane 32 20 16 12 Colloidal Silica Dispersion 8 20 24 28 menstruum Isopropanol 30 30 30 30 n-butanol 30 30 30 30 Abrasion Resistance (δ% Haze) 3.2 2.8 2.9 3.1 Adhesive Good Good Good Good

Experimental Example 3: Wear resistance and adhesion test of polymethyl methacrylate plate

The wear-resistant coating solution was thermoset on polymethyl methacrylate resin instead of polycarbonate resin under the same conditions as in Example. Abrasion resistance and adhesion tests were carried out by the method given above and the results are shown in Table 3.

Composition ingredient (g) Example Comparative example 3-1 3-2 3-1 Curing catalyst N, N-dimethyl-3- (trimethoxysilyl) propan-1-amine 0.2 N, N, N-trimethyl-3- (trimethoxysilyl) propane-1-ammonium acetate 0.2 Dimethylbenzylamine 0.2 Acetic acid 1.6 1.6 1.6 Methyltrimethoxysilane 20 20 20 Colloidal Silica Dispersion 20 20 20 menstruum Isopropanol 30 30 30 n-butanol 30 30 30 Abrasion Resistance (d% Haze) 0.7 0.5 14.0 Adhesive Good Good Good

As shown in Table 3, Examples (3-1 and 3-2) of the present invention have good wear resistance and adhesiveness, whereas Comparative Example (3-1) has good adhesiveness but weak wear resistance. have.

Therefore, this invention can obtain the silicone type coating composition which added the trialkoxy silyl amine or trialkoxy silyl ammonium salt which is a hardening catalyst which has a condensable functional group to the coating mixture of the partial condensate of silanol and colloidal silica dispersion.

The silicone-based coating composition may be used when the coating layer is formed on the surface of a plastic or metal substrate to form a coating layer, and may be greatly improved in wear resistance by coating on the surface of the substrate to which the acrylic primer is applied.

As a result, the storage stability of the coating becomes longer when the coating is stored, and the trialkoxysilyl amine or the trialkoxysilyl ammonium salt, which is a curing catalyst having a condensable functional group, is contained, so that all reactants have silanol groups after hydrolysis. It is excellent and can prevent the separation of the catalyst after curing, so that low-temperature cross-linking curing and storage properties are greatly improved, it can be applied to various fields such as automotive parts, optical materials, building materials, kitchen appliances and electrical materials.

Claims (7)

Trialkoxysilyl amine or trialkoxysilyl, a mixture consisting of a partial condensate of silanol forming a methylpolysiloxane and a colloidal silica dispersion, and a curing catalyst having a condensable functional group of 0.02 to 2.5% by weight based on the solids content of the mixture. Wear-resistant silicone-based coating composition comprising a curing catalyst having a condensable functional group characterized in that the ammonium salt. The method according to claim 1,
The ratio of the partial condensate of the silanol and the colloidal silica dispersion is a ratio of the condensation functional group, characterized in that the partial condensate of the silanol and the colloidal silica dispersion are mixed in a weight ratio of 30 to 80:20 to 70 Wear-resistant silicone-based coating composition comprising a curing catalyst having. The method according to claim 1,
The partial condensate of the silanol is obtained by hydrolyzing an alkyltrialkoxysilane satisfying the following Formula 1,
[Formula 1]
RSi (OR ') ₃
(Wherein R is an alkyl group having 1 to 3 carbon atoms or an aryl group having 6 to 13 carbon atoms, and R 'is an alkyl group having 1 to 3 carbon atoms)
Wear-resistant silicone coating composition comprising a curing catalyst having a condensable functional group, characterized in that. The method according to claim 1,
Wear-resistant silicone coating composition comprising a curing catalyst having a condensable functional group characterized in that the pH of the total composition composed of the mixture and the curing catalyst is 3.5 ~ 8.0. The method according to any one of claims 1 to 4,
A diluent is added to the mixture of the partial condensate of silanol and the colloidal silica dispersion,
Wear-resistant silicone-based coating composition comprising a curing catalyst having a condensable functional group characterized in that the amount of the diluent is adjusted so that the solid content of the total composition is 5 to 45% by weight. The method according to claim 5,
The diluent comprises a curing catalyst having a condensable functional group, characterized in that selected from the mixture of water and alkanol having 1 to 8 carbon atoms or mixtures thereof, one or two or more polar solvents that can be mixed with water. Wear-resistant silicone coating composition. The method according to claim 5,
The diluent is one or two selected from n-butanol, 2-ethoxyethanol, methanol, ethanol, propanol, isopropanol, isobutanol, t-butanol, dimethylformamide, dimethylsulfoxide, acetone and methylcellosolves. Adopted a mixture of the above,
Wear-resistant silicone-based coating composition comprising a curing catalyst having a condensable functional group, characterized in that the diluent is 55 to 95% by weight of the total composition.