KR20190105914A - Room temperature curing coating materials containing silan oligomer - Google Patents

Abstract

The purpose of the present invention is to provide a silane oligomer coating agent which is curable at room temperature, allows a coating film to exhibit contamination resistance, has excellent weatherability and suppresses aging variations of a coating solution, thereby enabling preservation stability to be exhibited for a long period of time. The coating agent of the present invention has been completed by mixing the reactants at a certain mixing ratio after separately preparing reactants by hydrolytically condensing hydrolyzable alkoxysilanes into a silane partial hydrolysate and a silane hydrolyzed condensate and hydrolytically condensing a long-chain alkyl silane into colloidal silica in different reaction containers. According to the present invention, the coating agent can be widely applied to materials such as plastics, metal and others on which it has been difficult to perform a coating process such as plastics, metal and the like, enables room temperature curing, has excellent adhesion to the object to be coated and has an increased coating film hardness and improved contamination resistance and long-term preservation stability by varying ratios of a partial hydrolysate, a condensate and a reactive silica sol according to types of an object to be coated, thereby prescribing the coating agent.

Description

Room temperature curing coating materials containing silan oligomer

The present invention relates to a room temperature-curable coating agent containing a silane oligomer as a main component, and more particularly, a partial hydrolysis reaction product (a), a hydrolysis condensation reaction product (b), and a long chain alkylsilane of a hydrolyzable silane mixture. The present invention relates to a room temperature-curable high-strength silane oligomer coating prepared by mixing hydrolyzed and condensed reactants (c) with silica and mixing them, and in addition to the high hardness, abrasion resistance, chemical resistance and heat resistance of conventional silicone coating agents, It is possible to form a coating film with excellent crack resistance and surface contamination resistance, especially at room temperature curing, excellent long-term storage stability of the coating agent, and to form a high-strength coating film on various material surfaces such as plastic, metal, ceramic, Good stain resistance is shown even in a state.

Conventional silicone compound-based coating agent forms a high-strength coating film compared to organic paints such as acryl, and has excellent chemical resistance, heat resistance, and oxidation resistance, and is stable to ultraviolet rays, and has excellent weather resistance. Therefore, it is widely used in various industrial facilities, electronic products, automobiles, etc. As it is applied, it occupies a very important position industrially. However, when the coating material is metal or plastic, the functionalities of the coating material and the coating material are different from each other, so that it is difficult to attach, and the toughness may be insufficient to cause microcracks, and it is difficult to obtain a highly beautiful gloss. In addition, the conventional silicone compound-based coating agent is deteriorated (aging change) due to its own reaction with time after manufacture, there is a limit that hardening at room temperature.

Japanese Unexamined Patent Publication JP09-071654 "Organopolysiloxane Resin and Manufacturing Method Thereof and Curable Organopolysiloxane Resin Composition Using the Same" is a long-term storage stability of a coating agent, enables the formation of a coating film at a low temperature, and contains a relatively large amount of silanol groups. A composition has been proposed. In the composition of the present invention, when hydrolyzing the alkoxysilane, water is used in excess of the alkoxysilane (usually 1 to 50 times), and the alcohol produced by hydrolysis condensation is distilled off at a relatively low temperature of 80 ° C or lower. As a result, the long-term storage stability of the composition is improved, but it is difficult to cure at room temperature, and if the heat treatment is not performed, the surface hardness is very low, and the crack resistance is also a problem. There is a problem in that the production efficiency and economic efficiency is reduced.

Many attempts have been made to solve the above problems of the silicone coating, but there is still a definite alternative.

Accordingly, an object of the present invention is to provide a silane oligomer coating agent that can be cured at room temperature, the coating film is stain resistant, has excellent weather resistance, and exhibits long-term storage stability by suppressing aging change of the coating solution.

In the present invention, the hydrolyzable alkoxysilanes selected to solve the above problems are three kinds of silane partial hydrolyzate, silane hydrolyzate and long-chain alkylsilane hydrolyzate in different reaction apparatuses based on sol-gel process. The silane oligomer was separately prepared and then mixed at a predetermined ratio to complete the coating. By varying the ratio of the three oligomers according to the type of the coating material, it is possible to apply widely to materials that were difficult to coat such as plastic and metal.

The silane oligomer transparent coating agent prepared according to the present invention is excellent in storage stability of the coating liquid, can be cured at room temperature in a one-part type, and can obtain a coating film exhibiting a high water repellency and surface staining effect.

The silane oligomer coating agent of the present invention contains a silane oligomer made by hydrolyzing a hydrolyzable alkoxysilane mixture as a main component. In the present invention, three different silane oligomers were prepared, and a coating agent was prepared by mixing them in an appropriate ratio according to the type and shape of the workpiece. The coating agent of the present invention is prepared by preparing an alkoxysilane mixture by varying the hydrolysis conditions and mixing them. The coating agent is cured at room temperature, exhibits high strength, and can be stored at room temperature for a long time by suppressing the aging change of the coating solution. Excellent pollution resistance.

The present invention relates to a transparent coating agent composed mainly of a silane oligomer prepared by condensation of a hydrolyzable alkoxysilane having a molecular formula such as R ¹ _m Si (OR ² ) _{4 -m} with partial hydrolysis. In the above formula, R ¹ = an organic group having ^{1 to} 18 carbon atoms, R ² = an alkyl group, and m is an integer of 0, 1 or 2.

In the present invention, the three different types of silane oligomers (a), (b) and (c) were prepared as follows, respectively, and these were mixed at a constant ratio at room temperature to complete a coating agent.

The silane oligomer (a) is represented by the above molecular formula R ¹ _m Si (OR ² ) _{4 -m} , and R ¹ is an alkyl group or an aryl group with respect to 1 mole of trialkoxysilane wherein R ¹ and R ² are alkyl groups and m is 1 , R ² is an alkyl group and m is 2, dialkoxysilane 0.01 to 0.5 mole and, R ² is an alkyl group, and a partial hydrolyzate of the alkoxysilane mixture is mixed at a ratio of 0.01 to 0.5 mole of tetraalkoxysilane m is 0.

The silane oligomer (b) partially hydrolyzes the alkoxysilane mixture of the same composition as the silane oligomer (a) separately and then proceeds with a condensation reaction.

The silane oligomer (c) is represented by the molecular formula R ¹ _m Si (OR ² ) _{4 -m} , wherein R ¹ is a hexyl, octyl or decyl group having 6 or more carbon atoms, R ² is an alkyl group and m is 1 long chain. Titanium alkoxide and zirconium alkoxide were added to the long-chain alkyl silane and partially hydrolyzed and condensed with acidic colloidal silica.

The silane oligomer (a) is added to the acid catalyst so that 0.1-0.5 mol of water and pH 3-5 with respect to 1 mol of hydrolyzable groups of the alkoxysilane mixture at room temperature or below 50 ℃, homogeneity of the solution at the same temperature It sustained partial hydrolysis over 24 hours.

The silane oligomer (b) is added to the acid catalyst so that 0.5-1.5 mol of water and pH 3-5 with respect to 1 mol of the hydrolyzable group of the alkoxysilane mixture at room temperature or 50 degrees C or less, and at 50 degrees C or more and 90 degrees C or less. Hydrolysis and condensation reaction were carried out, followed by dealcoholization at 100-110 ° C.

The silane oligomer (c) is a long chain alkylsilane: titanium alkoxide: zirconium alkoxide: colloidal silica (solid content 20% by weight) = 1-10: 1-10: 0.1-5: 75-97% by weight after mixing pH was adjusted to 2-5 and hydrolysis condensation reaction was performed.

In addition, the present invention is a silicone-based coating agent containing all of the silane oligomer (a), silane oligomer (b) and silane oligomer (c) can be easily expanded by varying the mixing ratio according to the material and physical properties of the surface to be coated. It relates to a room temperature-curable silane oligomer coating.

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

Silane  Oligomer (a):

One or more of the trialkoxysilanes in which R1 and R2 are alkyl groups, m is 1, and R1 is an alkyl group or an aryl group, and m is 2, in the formula R ¹ _m Si (OR ² ) _{4 -m} The silane oligomer obtained by partially hydrolyzing one or more of the tetraalkoxysilanes in which R2 is an alkyl group and m is 0 and mixes them with an acid catalyst. It is more preferable to add dialkoxysilane and tetraalkoxysilane in order to impart hardness, toughness, adhesion and crack resistance of the coating film rather than trialkoxysilane alone.

As for the mixing ratio of these silanes, 0.01-0.5 mol of dialkoxysilanes and 0.01-0.5 mol of tetraalkoxysilanes are suitable with respect to 1 mol of trialkoxysilanes. Here, the trialkoxysilane is preferably a silane containing a methoxy group, and the dialkoxysilane and the tetraalkoxysilane are also silane containing a methoxy group. However, in the case of dialkoxysilane, a silane coupling agent may be selected. As an organic functional group of a silane coupling agent, a vinyl group, an epoxy group, and a methacryloxy group are suitable. Double epoxy groups are most suitable.

In addition, in order to induce a smooth hydrolysis reaction with 0.01-0.5 mol of water with respect to 1 mol of hydrolyzable groups of the mixed silane, an acid catalyst is added and maintained at a pH of 3-5 and maintained at not higher than 50 ° C while stirring. The final partial hydrolyzate was prepared.

In the present invention, an appropriate amount of an organic solvent can be used as a solvent. The selected alkoxysilanes were mixed with the organic solvent, water and a hydrolysis catalyst were added while stirring, and partial hydrolysis was performed by stirring for 3 hours or more while maintaining the temperature (up to 50 ° C. or less). The hydrolysis catalyst is suitable for the organic acid or inorganic acid, and the physical properties of the partial hydrolyzate vary depending on the amount of water added, the solution temperature, and the stirring time. For example, when the amount of water added is 0.5 mole or more relative to 1 mole of the hydrolyzable group, or when the temperature exceeds 50 ° C., the hydrolyzed or partially condensation of the hydrolyzed silicon composite occurs excessively, making it difficult to attain room temperature curing of the coating film during coating. At the same time, the hardness of the coating film is also lowered. In addition, when the addition amount of water is 0.01 mol or less, the hydrolysis reaction itself becomes impossible. This is believed to be due not only to the increase in molecular weight, but also to the reduction of reactors such as silanol, alkoxy, due to excessive heterogeneous hydrolysis or condensation progression. As a result, the room temperature curing ability is lowered and the hardness of the coating film is also lowered, so it is necessary to pay close attention so that the amount of water added, the temperature of the solution and the stirring time do not exceed the limit.

As the hydrolysis catalyst, a conventionally known catalyst is used, and in particular, an acidic hydrogen halide, a carboxylic acid, a sulfonic acid, an acidic or weakly acidic inorganic salt, a solid acid such as an ion exchange resin, or the like is preferable. Examples of these include organic acids represented by hydrogen fluoride, hydrochloric acid, nitric acid, sulfuric acid, acetic acid, maleic acid, methyl sulfonic acid, and cation exchange resins having a sulfonic acid group or a carboxylic acid group on its surface. The amount of hydrolysis catalyst is suitably 0.001-10 mol with respect to 1 mol of hydrolysable groups. In addition, it is preferable to hydrolyze under weakly acidic conditions, and especially to react in pH 3-5. If the hydrolysis does not proceed under weakly acidic conditions, the resulting silanol groups may become unstable and may not facilitate room temperature curing.

The partial hydrolyzate prepared in this way becomes a low molecular weight organic silicone oligomer containing a large amount of silanol groups, which becomes an important component to allow the coating film to be cured at room temperature. That is, the following reaction proceeds.

≡Si-OR + H ₂ O → ≡Si-OH + ROH

The silane partial hydrolyzate thus produced is in a state in which alkoxy groups are partially hydrolyzed in the form of low molecular weight oligomers so that silanol groups and unreacted alkoxy groups coexist (공 Si-OH + OR-SiOR). That is, the silanol group and the alkoxy group are present in a large amount, thereby exhibiting the characteristics of the highly reactive oligomer. Thus, the silane oligomer including a large amount of the reactor becomes a main component capable of forming a solid coating film at room temperature, and reacts with the other oligomer components to form a high hardness coating film. That is, the silane oligomer including the large amount of the reactor plays a role of maximizing the hardness of the coating film by a chemical bonding reaction with the long-chain alkylsilane hydrolysis condensate as the component (c). More specifically, since the physical properties of the coating film are greatly changed depending on the combination ratio of the trialkoxysilane or dialkoxysilane, the composition selection becomes important. In other words, the combination ratio of tetraalkoxysilane, trialkoxysilane and dialkoxysilane should be careful because it affects the adhesion of the coating film to the coating material and the hardness of the coating film. For example, the trialkoxysilane generally serves as a main component material for forming a strong water repellent coating, the tetraalkoxysilane added thereto serves to increase the hardness of the coating film, and the dialkoxysilane improves the flexibility and adhesion of the coating film. It has its own characteristics. Therefore, the three alkoxysilanes can be suitably combined in accordance with the type and use of the coating material to form a high-strength coating film corresponding to the required physical properties. In particular, in the case of dialkoxysilane, when the silane coupling agent having an organic functional group is selected, adhesion to polymer organic materials such as plastic may be enhanced.

Examples of trialkoxysilane represented by R ¹ Si (OR ² ) ₃ in the molecular formula include methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, methyltributoxysilane and ethyl Trimethoxysilane, ethyltriethoxysilane, ethyltriethoxysilane, ethyltriisopropoxysilane, propyltrimethoxysilane, propyltriethoxysilane, propyltriisopropoxysilane, butyltrimethoxysilane, hexyl Trichlorsilane, hexyltrimethoxysilane, phenyltrimethoxysilane, methyltriisopropenoxysilane, vinyltrimethoxysilane, aryltrimethoxysilane, ethyltrichlorsilane, propyltrichlorsilane, butyl trichlorsilane , Decyltrichlorsilane, decyltrimethoxysilane, phenyltrichlorsilane, cyclohexyltrichlorsilane, cyclohexyltrimethoxysilane, gamma-methacryloxypropyltrimethoxysilane, gamma -Methacryloxypropyltriethoxysilane, gamma-acryloxypropyltrimethoxysilane, gamma-glycithoxypropyltrimethoxysilane, gamma-glycithoxypropyltriethoxysilane, beta-93,4-epoxycyclohexyl ) Ethyltrimethoxysilane, gamma-chloropropyltrimethoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, 3,3,3-trifluoropropyltriethoxysilane, pafluorooctylethyltri Methoxysilane, gamma-mercaptopropyltrimethoxysilane, gamma-aminopropyltrimethoxysilane, gamma-aminopropyltriethoxysilane, N- (2-aminoethyl) aminopropyltrimethoxysilane, etc. may be mentioned. have.

Examples of dialkoxysilane represented by R ¹ Si (OR ² ) ₂ in the molecular formula include dimethyldimethoxysilane, dimethyldiethoxysilane, methylethyldimethoxysilane, diethyldimethoxysilane and diethyldiethoxy Silane, methylpropyldimethoxysilane, methylpropyldiethoxysilane, diisopropyldimethoxysilane, phenylmethyldimethoxysilane, vinylmethyldimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyl Methyldiethoxysilane, beta- (3,4-epoxycyclohexyl) ethylmethyldimethoxysilane, gamma-methacryloxypropylmethyldimethoxysilane, gamma-methacryloxypropylmethyldiethoxysilane, gamma-mercaptopropylmethyl Dimethoxysilane, gamma-aminopropylmethyldiethoxysilane, N- (2-aminoethyl) aminopropylmethyldimethoxysilane, and the like.

Examples of tetralkoxysilane represented by Si (OR ² ) ₄ in the molecular formula include tetramethoxysilane and tetraethoxysilane.

As a result, the partial hydrolyzate of such an inorganic alkoxysilane and organic alkoxysilane mixture alone forms a coating film of high hardness and can be cured even at room temperature. While the partial hydrolyzate acts to increase the hardness of the coating film, the coating film is brittle and tends to crack.

Silane  Oligomer (b):

At least one of the trialkoxysilanes in which R1 and R2 are alkyl groups, m is 1, and at least one of the dialkoxysilanes in which R1 and R2 are alkyl groups and m is 2 in the formula R ¹ _m Si (OR ² ) _{4 -m} Are selected from each other and a mixture of these is a silane mixture, which is an alkoxysilane mixture having the same composition as the silane oligomer (a). It is a silane oligomer obtained by partial hydrolysis with an acid catalyst and then condensation. The difference between the silane oligomer (b) and the silane oligomer (a) is not only partial hydrolysis, but also condensation reaction at a high temperature. Thus, the molecular weight of the oligomer is increased while reducing the amount of the reactor, such as silanol groups, it is possible to obtain a more flexible coating in terms of physical properties, and also to obtain an effect of improving the gloss of the coating. In particular, since it contains a small amount of silanol groups and alkoxy groups, it is possible to maintain a more robust chemical bond with the silanol oligomer (a) to form one binder, that is, a compound that can compensate for the disadvantages of each other.

The partial hydrolysis was carried out at 50 ° C. or lower, and the amount of water was 0.5-1.5 moles with respect to 1 mole of the mixed silane hydrolyzable group, and an acid catalyst was added to pH 2-5 to induce a smooth hydrolysis reaction.

And condensation reaction was performed at 50 degreeC or more and 90 degrees C or less, and the alcohol produced was distilled off at 100 degreeC or more and 110 degrees C or less. In this way, a dealcohol condensed silane oligomer having an increased degree of condensation can be obtained. As a result, a relatively high molecular weight silicone oligomer is made. Thus, the rise of the oligomer viscosity and the change of the drying rate appear, and more accurate molecular weight measurements can be determined through instrumental analysis.

The next condensation reaction, which is partially hydrolyzed as described above, is as follows.

2≡Si-OH → ≡Si-O-Si≡ + H2O

The partial hydrolysis condensation reaction product is in a state in which the silanol group ((Si-OH-Si≡) produced as a result of the hydrolysis reaction and the siloxane group (= Si-O-Si =) by deshrink-polymerization are mixed. . The partial hydrolysis condensation reactant contains a small amount of the reactor and is added to the coating to exhibit the adhesion, crack prevention and gloss enhancement of the coating film. This includes a silanol group, an alkoxy group, and the like, and has a relatively high molecular weight of organosiloxane, which improves the flexibility of the coating film and adhesion to the coating material, and serves to impart stain resistance and glossiness of the coating film.

In the case of the coating agent made of only the silane oligomer (a), curing at room temperature is possible and the hardness of the coating film is high, but it is brittle, cracks are easily generated, and adhesion to the coating is weak. By adding the silane oligomer (b), this problem can be alleviated. The silane oligomer (b) may be prepared through a hydrolysis and condensation process using the alkoxysilane mixture as a starting material as in the silane oligomer (a). The hydrolysis condensate thus produced has the effect of giving toughness to the coating, improving gloss and increasing adhesion to the coating. More specifically, hydrolysis may be performed by adding an appropriate amount of an organic solvent to the hydrolyzable alkoxysilane mixture. At this time, the amount of water is 0.5-1.5 mole is appropriate for 1 mole of hydrolyzable group, and if it is less than 0.5 mole, the rate of hydrolysis and condensation reaction is slow, and the reaction is difficult to proceed. If the molar exceeds 1.5 mole, the rate of hydrolysis is too fast. It may become homogeneous or gel too high in viscosity. The hydrolysis should proceed at room temperature, and the mixture is stirred for 3 hours while maintaining the temperature not exceeding 50 ° C. to prepare the partial hydrolyzate, and then the temperature is adjusted to 50 ° C. or higher and 90 ° C. or lower and the stirring is continued for 3 hours to proceed the condensation reaction. After that, the temperature is increased again to a temperature range of 100 ° C.-110 ° C. to condense the condensation reaction by distilling away the added alcohol and the remaining alcohol such as alcohol. The silane hydrolyzed condensate produced through this process becomes an organosiloxane silane oligomer in which a small amount of silanol groups and silyl groups remain.

Water used for hydrolysis is preferably added to a polar organic solvent. Examples of the polar organic solvent include alcohols such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol, t-butanol, diacetone alcohol, ethylene glycol, monoethylene glycol monoether, propylene glycol, propylene glycol monoether, and the like. .

The silane oligomer (b) thus prepared is added and mixed with the silane oligomer (a) to mitigate the easily broken property of the coating film of the partial hydrolyzate, thereby increasing flexibility and improving adhesion. That is, the partial hydrolyzate of the organoalkoxysilane of the silane oligomer (a) and the partial hydrolysis condensate of the silane oligomer (b) complement each other's defects to obtain better coating film strength and improved adhesion to the coating. It becomes possible. This improvement in flexibility and adhesion appears to be due to the relatively low amounts of silanol groups and other reactors and higher molecular weights. The partial hydrolysis condensate of the silane oligomer (b) chemically reacts with the silane oligomer (a) to somewhat mitigate brittle defects.

The partial hydrolysis condensate of the organosilicon compound shows a clear difference in the properties and durability of the coating film compared to the silicone polymer without a reactor in terms of additives. The partial hydrolysis-condensation product of the silane oligomer (b) of the present invention has some silanol groups and alkoxy groups, which are terminal groups, and thus acts on the crosslinking reaction with other components, thereby providing flexibility to the coating film and preventing cracks. Long term. On the other hand, in the case of the polysiloxane having no reactor at all, since there is no end group, the polysiloxane cannot be firmly fixed to the inside of the membrane, leading to a decrease in strength and a decrease in solvent resistance. Therefore, the partial hydrolysis condensation product of the organoalkoxysilane, which is a silane oligomer (b) component, has a relatively small amount of reactor, but is limited in crosslinking with components (a), (b) and (c) to fix the inside of the hard coating membrane. It should be manufactured to be possible. At this time, it is important that if the content of the residual reactor is more than necessary, the rate of participating in the condensation reaction between the silane hydrolysis condensate and the metal oxide fine particle component becomes high, and the crack prevention function is lowered.

After all, when the content of the silanol group in the silane oligomer is more than necessary, the condensation reaction proceeds during curing, but the hardness is high, but the crack resistance is low. On the contrary, when the content of silanol groups is too low, it is difficult to immobilize inside the membrane, leading to a decrease in strength and a decrease in solvent resistance.

In addition, when the content of the residual alkoxy group is more than necessary, the proportion involved in the condensation reaction between the silane hydrolysis condensate and the metal oxide fine particle component is increased, and the crack prevention function is lowered.

Silane  Oligomer (c):

In general, the alkoxysilane having a long chain alkyl group (long-chain alkyl group) is a material having a very high water repellency, a very low degree of hydrolysis by a conventional hydrolysis method. In the present invention, a certain amount of titanium alkoxide and zirconium alkoxide were added to the long-chain alkoxysilane and mixed, followed by partial hydrolysis and condensation reaction using a large amount of acidic colloidal silica. In this way, the degree of hydrolysis of the long-chain alkoxysilane was increased, and the surface of the colloidal silica was also modified.

Therefore, in the present invention, by modifying the surface of the colloidal silica, it was possible to maintain the room temperature curing ability of the coating while maintaining the inherent role of the colloidal silica. In addition, this method can solve the root cause of the poor stability of the product due to the aging of the coating solution. It is thought that the change of aging reaction is suppressed because the power of the condensation reaction, which proceeds slowly during the storage of the coating liquid, is lost by replacing the silanol groups present in the surface of the colloidal silica particles with hydrophobic portions in the course of hydrolysis. .

Compared to the hydrolysis of long-chain alkylsilanes using conventional methods using acid catalysts and water, the degree of hydrolysis is further increased when titanium alkoxide and zirconium alkoxide are added in a certain amount and these mixtures are hydrolyzed using acid and water. In addition, when the long-chain alkylsilane to which titanium alkoxide and zirconium alkoxide were added is hydrolyzed using acidic colloidal silica, it was confirmed that the degree of hydrolysis can be further increased. As a result, titanium alkoxide and zirconium alkoxide, together with the silica component, increase the degree of hydrolysis of the non-hydrolyzable long-chain alkylsilane and at the same time play a role of improving the hardness of the coating film, preventing contamination and damaging the coating film from ultraviolet rays.

Colloidal silica is a very important component in terms of increasing the hardness of the coating film, but also provides a cause of the aging change (deterioration) of the coating agent. A large amount of silanol groups present on the surface of the colloidal silica may be involved in the coupling reaction with other film-forming components, but the excess silanol groups cause the aging change to accelerate the condensation reaction of the silane oligomer in the coating liquid. That is, the condensation reaction proceeds in the coating solution to increase the molecular weight of the oligomer and act as an element that inhibits the room temperature curing ability of the coating solution. As a result of observing through several experiments in the present invention, the hydrolysis of the long-chain alkylsilane is a mixture of titanium alkoxide and zirconium alkoxide in an appropriate ratio, and hydrolysis when the hydrolysis proceeds by adding a large amount of acidic silica sol The reaction was found to be the most effective.

The proportion of the silane oligomer (c) in the coating agent of the present invention is preferably from 17 to 45% by weight. This can obtain a higher hardness coating film in the same amount compared to conventional colloidal silica and can obtain a coating coating excellent in fouling resistance. Titanium alkoxide and zirconium alkoxide are added to the long-chain alkylsilane within 0.01 mole or more to 0.5 mole, acidic colloidal silica is slowly added at room temperature, partially hydrolyzed at 50 ° C. or more, and then the remaining alcohol is distilled at 100 ° C. or more to condensation reaction. By promoting the hydrolysis, it was possible to increase the degree of hydrolysis of long-chain alkylsilanes that are difficult to hydrolyze. Examples of long-chain alkylsilanes include hexyltrimethoxysilane, hexyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, and the like. Double octyltriethoxysilane (octyltriethoxysilane) This is the best fit.

Titanium alkoxide is suitable for titanium isopropoxide, and zirconium alkoxide is suitable for zirconium butoxide. That is, titanium isopropoxide and zirconium butoxide may be mixed with the long chain alkylsilane in a predetermined ratio, and an acid catalyst and an appropriate amount of water may be added thereto to hydrolyze the long chain alkylsilane. At this time, the pH is in the range of 2-6 is suitable and the amount of water is 5-50% by weight of the mixed amount of titanium isopropoxide and zirconium butoxide. Hydrolysis proceeds in the range of 50-80 ° C.

Commercial colloidal silica contains 20-50 weight% of silica as solid content. When water-dispersible colloidal silica is used, water present as a component other than solid content is used for hydrolysis of the hydrolyzable silane. The colloidal silica may be used dispersed in an organic solvent, or may be used by mixing colloidal silica of dispersion with an aqueous solvent. When water-disperse colloidal silica and organic solvent-dispersed colloidal silica are mixed, hydrolysis may be performed by adding and adjusting an inorganic acid or an organic acid in the pH range. The pH of the solution during hydrolysis is suitably in the range of 1.0-5.0. A series of hydrolysis condensation processes are then performed. Thus synthesized silica sol has a reactor capable of chemically bonding with other components of the coating agent to form a more robust coating film and has the effect of suppressing the aging change of the coating liquid. On the other hand, when the silane oligomer (c) is excessive, there is a risk that the coating film is easily broken.

Specifically, the method for preparing the silane oligomer (c) is first slowly added and mixed with titanium alkoxide and zirconium alkoxide to a long-chain alkylsilane such as octyltrialkoxysilane, followed by addition of acidic colloidal silica and stirring at room temperature. Hydrolysis starts, where each component is a long chain alkylsilane: titanium alkoxide: zirconium alkoxide: colloidal silica (solid content 20% by weight) = 1-10: 1-5: 0.1-3.0: 70-90% by weight It is preferable to mix with.

The mixing ratio of octyltrialkoxysilane and colloidal silica is preferably 10-90 times colloidal silica based on the weight of solids. More suitably 30-80 times. At this time, if the solid content weight of the colloidal silica is not 10 times of the octyltrialkoxysilane, the hydrolysis of the octyltrialkoxysilane is insufficient, so that the storage stability of the coating agent is lowered and the hardness of the coating film is lowered. On the other hand, when the solid content weight of colloidal silica exceeds 90 times of octyltrialkoxysilane, the stain resistance of a coating film falls and the effect which suppresses the aging change of a coating liquid falls. The mixture may be stirred while slowly adding colloidal silica to the octyltrialkoxysilane. At this time, the temperature of the stirring solution is maintained at room temperature but the stirring is continued for 1 hour while not exceeding 50 ° C. Then, the temperature of the stirred solution was then stirred at 50 ° C. or higher and 90 ° C. or lower, more preferably at 70 ° C. for about 5 hours to proceed with primary partial hydrolysis, and then heated to 105 ° C. to maintain residual alcohol at atmospheric pressure. The condensation reaction is promoted while the components are distilled off. In this way, the degree of hydrolytic condensation of the octyltrialkoxysilane can be improved and the surface modification degree of colloidal silica can be maximized in proportion thereto. In other words, a large amount of silanol groups present in the colloidal silica particles are replaced by alkoxy groups or other reactive groups.

In order to maintain stability in the reaction, an organic solvent may be mixed, wherein the organic solvent is a polar organic solvent. Examples of the polar organic solvent include alcohols such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol, t-butanol, diacetone alcohol, ethylene glycol, monoethylene glycol monoether, propylene glycol, propylene glycol monoether, and the like.

Characteristic of octyltrialkoxysilane and colloidal silica hydrolysis condensate in the present invention is very excellent in terms of coating film strength, room temperature curing ability and coating stability (aging change) compared to the case of using only colloidal silica alone Is to get it. This is considered to be the result of the excessive substitution of silanol groups on the surface of colloidal silica with alkoxy groups during hydrolysis. As a result, various reactors were effective in increasing the surface hardness of the coating film in a relatively small amount by strengthening the chemical bonds with the later added film components.

Therefore, it can be seen that the partial hydrolysis condensation product of the hydrolyzable alkoxysilane prepared in the present invention is a more advanced result that can improve the problems of the conventional silicone-based coating agent. The appropriate content of the silane oligomer (c) in the coating agent of the present invention is 17-45% by weight, the hardness of the coating film is lowered when less than 17% by weight, the gloss of the coating film is lowered or cracks are exceeded when it exceeds 45% by weight. May cause

Organic solvents:

Organic solvents compatible with the coating of the present invention should be selected that do not react with the hard coating material, for example, aliphatic hydrocarbon solvents such as hexane, heptane, isooctane, isododecane, aromatic hydrocarbons such as toluene, xylene Alcohol solvents such as solvents, methanol, ethanol, isopropanol, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether Ester solvents, such as glycol ether solvents, such as ethyl acetate, butyl acetate, and a propylene glycol monomethyl ether acetate ester, are mentioned.

In the present invention, pH adjusters, leveling agents, thickeners, curing catalysts, pigments, metal oxide particles, antioxidants, ultraviolet absorbers, antistatic agents and the like may be added as necessary without adversely affecting the effects of the present invention.

The coating agent of the present invention can be easily prepared in suitable physical properties according to the type of the coating material such as metal, plastic, ceramics and the like by varying the mixing ratio of the three components (a), (b) and (c). The room temperature-curable silane oligomer coating agent of the present invention is a silane oligomer (a): (b): (c) = 50-80: 0.1-15: 17, each of the mixing ratio based on the solid content concentration according to the material and required physical properties of the surface to be coated Characterized in differently obtained in the range -45% by weight. For example, when the workpiece is glass or ceramics, the silane oligomer (a) is mixed in the range of 50-80 wt% (hereinafter solid concentration), silane oligomer (b) 0.1-5 wt%, silane oligomer (c) 19-45 wt% To prepare a coating agent, if the coating material is a metal, the silane oligomer (a) 50-80% by weight, the silane oligomer (b) 1-10% by weight, the silane oligomer (c) 19-40% by weight, the coating material In the case of plastics, it is suitable to mix 50-80 weight% of silane oligomer (a), 3-15 weight% of silane oligomer (b), and 17-35 weight% of silane oligomer (c).

In the present invention, a partial hydrolyzate of the hydrolyzable silane mixture, a hydrolysis condensate, and a long-chain alkylsilane are used to separate silica sol from each other to modify the surface of the colloidal silica, and they are mixed at a predetermined ratio to prepare a coating agent. Double hydrolyzate contains a large amount of silanol groups and can be cured at room temperature with a highly reactive low molecular weight silane oligomer. In addition, the hydrolyzed condensate is a compound of the pre-polysiloxane step, containing an appropriate amount of silanol groups and alkoxy groups, thereby enabling more robust chemical bonding with the partial hydrolyzate. Therefore, the mixture of the partial hydrolyzate and the hydrolysis condensate has an effect of improving room temperature curing and adhesion with the coating material, compared to the coating prepared by the conventional hydrolysis condensation product.

In addition, in the present invention, a reaction product obtained by hydrolyzing a superhydrophobic hydrolyzable long-chain alkoxysilane with a metal alkoxide and a large amount of colloidal silica was added, thereby improving the hardness of the coating film, enhancing stain resistance, and providing long-term storage stability of the coating solution.

In addition, the present invention can easily prepare a coating agent of a suitable physical properties according to the type of the coating material, such as metal, plastic, ceramics, etc. by varying the mixing ratio of the three components (a), (b) and (c). Can be.

Hereinafter, the configuration of the present invention will be described in detail by presenting a synthesis example, an example, and a comparative example. However, it is apparent to those skilled in the art that the scope of the present invention is not limited to the following description.

Synthesis Example 1

36.0 g of methyltrimethoxysilane, 4.0 g of phenyltrimethoxysilane, 1.0 g of tetramethoxysilane and 20.0 g of methyl alcohol were added to a 2-liter Erlenmeyer flask equipped with a thermometer, a stirrer and a cooler, followed by mixing and stirring for 30 minutes. It was made to be. Then, 20 g of an aqueous 1.5% nitric acid solution was added dropwise for 1 hour and kept below 50 ° C. After the dropwise addition, the mixture was stirred at room temperature for 3 hours, and then suspended at room temperature for 48 hours to prepare a silane oligomer (a-1).

Synthesis Example 2

36.0 g of methyltrimethoxysilane, 3.0 g of dimethyldimethoxysilane, 1.0 g of tetramethoxysilane and 20.0 g of methyl alcohol were added to a 2-liter Erlenmeyer flask equipped with a thermometer, a stirrer and a cooler, followed by mixing and stirring for 30 minutes. It was made. Then, 15 g of 1.5% nitric acid solution was added dropwise for 1 hour and kept below 50 ° C. After the dropwise addition, the mixture was stirred at room temperature for 3 hours, and then suspended at room temperature for 48 hours to prepare a silane oligomer (a-2).

Synthesis Example 3

The same mixed alkoxysilane as in Synthesis Example 1, that is, 36.0 g of methyltrimethoxysilane, 3.0 g of dimethyldimethoxysilane and 1.0 g of tetramethoxysilane was added dropwise for 30 hours with 30 g of 1.5% nitric acid solution maintained at 50 ° C or lower. . After dropping, the mixture was stirred at room temperature for 2 hours, and then stirred at 70 ° C. for 6 hours to proceed with the condensation reaction. Then, the temperature was raised to 105 ℃ dealcohol treatment under atmospheric pressure to prepare a silane oligomer (b-1).

Synthesis Example 4

The same mixed alkoxysilane as in Synthesis Example 2, that is, 36.0 g of methyltrimethoxysilane, 3.0 g of dimethyldimethoxysilane and 1.0 g of tetramethoxysilane was added dropwise for 30 hours with 30 g of 1.5% nitric acid solution maintained at 50 ° C or lower. . After dropping, the mixture was stirred at room temperature for 2 hours, and then stirred at 70 ° C. for 6 hours to proceed with the condensation reaction. Thereafter, the mixture was heated to 105 ° C. and subjected to dealcoholization under atmospheric pressure to prepare a silane oligomer (b-2).

Synthesis Example 5

12 g of octyl triethoxysilane was added to a 2-liter Erlenmeyer flask equipped with a thermometer, a stirrer and a cooler, and 50 ml of isopropyl alcohol and 50 ml of butanol were mixed. 30 ml of titanium isopropoxide and 10 ml of zirconium butoxide were added in this order and stirred at room temperature. Then, 250 g of colloidal silica (20 wt% solids, pH = 2.5) was slowly added over 1 hour, followed by slowly adding 20 ml of an aqueous 0.05 mol hydrochloric acid (HCl) solution, followed by stirring at room temperature for 30 minutes. After stirring for 3 hours at 70 ℃ and cooled to room temperature to prepare a titanium-zirconium alkoxide mixed silane oligomer (c-1).

Synthesis Example 6

12 g of octyltriethoxysilane was added to a 2-liter Erlenmeyer flask equipped with a thermometer, a stirrer, and a cooler, 120 ml of ethanol was added thereto, and 30 ml of titanium isopropoxide and 10 ml of zirconium butoxide were added in this order and stirred at room temperature. Then, 250 g of colloidal silica (20 wt% solids, pH = 2.5) was slowly added over 1 hour, followed by 20 ml of aqueous hydrochloric acid (HCl) solution at 0.05 molar concentration, followed by stirring at room temperature for 30 minutes, followed by 70 ° C. After stirring for 10 hours at room temperature and cooled to room temperature to prepare an octyltriethoxysilane-titanium-zirconium alkoxide mixed silane oligomer (c-2).

Example 1 combining the synthesized silane oligomers (a-1), (a-2), (b-1), (b-2), (c-1) and (c-2) as shown in Table 1 , 2, 3, 4 and Comparative Examples 1 and 2 to prepare a coating, and tested the room temperature curing ability, hardness, adhesion and coating solution storage stability as shown in Table 1 below.

Room temperature Hardenability

Commercially available plate glass was cut into 10 cm length and 10 cm lengths and used as a coating test piece. First, the surface of the specimen glass was sufficiently washed with water and a neutral detergent and dried, and then the coating was flow coated. And it was left to dry in a room (20 ℃) blocked from direct sunlight. Then, after measuring the drying time, the pencil hardness was measured 48 hours after coating. When room temperature curing is possible by checking whether or not room temperature curing is possible, that is, when the pencil hardness is 3H or more, Table 1 indicates 3, when only dry contact is possible within 6 hours, and 2 when dry touch and room temperature curing are not possible. .

Hardness

The surface hardness of the coating film was measured with a 0.5kg load after mounting on a hardness tester using a Japanese Mitsubishi Corporation pencil (uniwriting & drowing 9H-6B, Mitsubishi Pencil). Hardness is indicated by pencil hardness value.

Adhesion

Coating the plate glass specimen using a commercially available cutter knife and cutting the surface of the sample coating film that has been cured (at least 48 hours after coating), i.e., cutting the coating film in the shape of a checkerboard, and then lifting the cutting part using a magnifying glass. It was visually confirmed whether a phenomenon or detachment was carried out. At this time, if there is no lifting and desorption, 3 is indicated. On the contrary, only one of the two phenomena occurs, 2, and 1, both occur.

Coating Preservation Stability

After the coating was prepared, it was stored for a long time at room temperature (20 ° C.), and the change of the coating (phase separation, discoloration, formation of precipitates) and the coating on the glass surface were periodically performed to measure the drying time and hardness. At this time, if there is no change for more than 6 months, 2, if changes occur after 6 months, and 1 if changes occur before 6 months.

Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Silane oligomer (a-1) 10 g - 5 g 20 g 20 g 30 g Silane oligomer (a-2) - 10 g 5 g - - - Silane oligomer (b-1) 5 g - 3 g 5 g 5 g - Silane oligomer (b-2) - 5 g 2 g - - - Silane oligomer (c-1) 10 g - 5 g 20 g - - Silane oligomer (c-2) - 10 g 5 g - - - Colloidal silica - - - - 10 g 10 g Isopropyl Alcohol 20 ml 20 ml 20 ml 20 ml 20 ml 20 ml Room temperature curing ability 3 3 3 3 2 One Hardness 6H 6H 5H 6H 2H 2H Adhesion 3 3 3 3 2 One Coating Preservation Stability 3 3 3 3 One One

Progress of the Invention

(1) Separation and production by hydrolysis step

The partial hydrolyzate and hydrolysis condensate of the hydrolyzable silane mixture were prepared separately from each other and mixed to form a coating. Double hydrolyzate contains a large amount of silanol groups and can be cured at room temperature with a highly reactive low molecular weight silane oligomer. In addition, the hydrolyzed condensate is a compound of the pre-polysiloxane step, containing an appropriate amount of silanol groups and alkoxy groups, thereby allowing a more firm bond with the partial hydrolyzate.

Therefore, the mixing of the partial hydrolyzate and the hydrolysis condensate has an effect of improving room temperature curing and adhesion with the coating material, compared to the coating prepared by the conventional hydrolysis condensation product.

(2) Hydrolyzable Long chain Alkylsilane  Introduction

The hydrolyzable hydrolyzable long-chain alkoxysilane was hydrolyzed with metal alkoxide and a large amount of colloidal silica to add a coating to improve the hardness, strengthen the stain resistance and provide long-term storage stability to the coating.

(3) Blood  The physical properties of the coating can be easily adjusted according to the type

By varying the mixing ratio of the three components (a), (b) and (c), it is possible to prepare a coating of suitable physical properties according to the type of the coating material such as metal, plastic, ceramics and the like.

Claims (5)

Silane oligomers (a), (b) and (c) are each prepared from hydrolyzable alkoxysilanes,
The silane oligomer (a) is represented by the molecular formula R ¹ _m Si (OR ² ) _{4 -m} , and R ¹ _m Si (OR ² ) is used for 1 mole of trialkoxysilane in which R ¹ and R ² are alkyl groups and m is 1. Represented by _{4- m} , R ¹ is an alkyl group or an aryl group, R ² is an alkyl group, 0.01-0.5 mole of dialkoxysilane having m 2 and the molecular formula R ¹ _m Si (OR ² ) _{4 -m} , and R ² is an alkyl group And a partial hydrolyzate of the alkoxysilane mixture mixed at a ratio of 0.01-0.5 mol of tetraalkoxysilane where m is 0,
The silane oligomer (b) is obtained by partial hydrolysis of the alkoxysilane mixture having the same composition as the silane oligomer (a) and then condensation.
The silane oligomer (c) is represented by the molecular formula R ¹ _m Si (OR ² ) _{4 -m} wherein R ¹ is a hexyl group, octyl group or decyl group of 6 or more carbon atoms, R ² is an alkyl group and m is 1 long chain Titanium alkoxide and zirconium alkoxide were added to the alkylsilane, partially hydrolyzed with acid colloidal silica, and then condensed.
Room temperature-curable silane oligomer coating agent prepared by mixing the silane oligomers (a), (b) and (c) at a constant ratio at room temperature.
The method according to claim 1,
The silane oligomer (a) is added at 0.1 or 0.5 moles of water and pH 3-5 with respect to 1 mole of the hydrolyzable group of the alkoxysilane mixture at room temperature or 50 ° C. or lower, and the solution at room temperature or 50 ° C. or lower. A coating agent, characterized in that produced by partial hydrolysis reaction for at least 24 hours while maintaining the homogeneity of.
The method according to claim 1,
The silane oligomer (b) is added to the acid catalyst such that 0.5-1.5 mol of water and pH 3-5 with respect to 1 mol of the hydrolyzable group of the alkoxysilane mixture at room temperature or 50 캜 or lower, and at 50 캜 or higher and 90 캜 or lower. A coating agent, characterized in that produced by the hydrolysis and condensation reaction and then subjected to a de-alcohol treatment at 100-110 ℃.
The method according to claim 1,
The silane oligomer (c) is a long chain alkylsilane: titanium alkoxide: zirconium alkoxide: colloidal silica = 1-10: 1-10: 0.1-5: 75-97% by weight of the mixture after mixing at a pH of 2-5 A coating agent, characterized in that produced by the hydrolysis condensation reaction after the adjustment.
The method according to claim 1,
The room temperature-curable silane oligomer coating agent prepared by mixing the silane oligomers (a), (b) and (c) at a constant ratio at room temperature is a silane oligomer based on the solid content concentration of each mixing ratio according to the material and required properties of the surface to be coated. (a): (b): (c) = 50-80: 0.1-15: coating agent, characterized in that obtained differently in the range of 17-45% by weight.