JPH0478663B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field] The present invention relates to a silicon alkoxide coating agent used, for example, on painted surfaces that require a coating film with weather resistance and hardness. [Background Art] Silicon alkoxide coating agents are weather resistant and can produce highly hard coatings, so they can be applied to substrate surfaces made of plastic, wood, cement, etc., which have chemically weak defects. Protecting the substrate is being done. This silicon alkoxide-based coating agent produces Mn and Mw/Mn by hydrolysis and condensation of silicon alkoxide.
Unless the value falls within a certain range, it is not possible to obtain a uniform, high-quality coating film. Here, Mw is the weight average molecular weight, and Mn is the number average molecular weight. Silicon alkoxide coating agents include silicon alkoxide with catalysts, curing agents, etc.
In addition to one-part type silicon alkoxide coating agents that are added in advance and stored ready for use, there are two-part types that separate monomers, catalysts, and curing agents. One-liquid type products are easy to use, but have poor storage stability and can only be stored in a cool, dark place for about one month at best. On the other hand, in the two-component type, for example, the desired Mw and
Since the ratio is Mw/Mn, there is storage stability, but after mixing liquid B with liquid A,
It takes a considerable amount of time (this is called "ripening time") for Mw and Mw/Mn to reach the desired values.
Workability is very poor. In this case, if you increase the amount of catalyst mixed in an attempt to shorten the aging time, the condensation reaction will proceed too fast and the Mw will decrease.
There was a problem in that the time during which Mw/Mn was maintained at a desired value (this is called "life") became shorter. Furthermore, since a large amount is used in building material applications, and therefore a large amount is stored, there is also the problem that it is difficult to store it in a cool, dark place. [Object of the invention] In view of the above circumstances, the present invention aims to provide a silicon alkoxide coating agent that has good storage stability when not in use, has a short maturing time when in use, and has a long life. The purpose is [Disclosure of the Invention] In order to achieve the above object, the present invention provides a silicon alkoxide _- based coating agent in which a catalyst _and a curing agent are added to silicon alkoxide. where n = 0 to 2, R is an alkyl group having 1 to 4 carbon atoms, and R' is an alkyl group having 1 to 4 carbon atoms] A catalyst and a curing agent are added to silicon alkoxide and silica sol to form siloxane. The Mw (weight average molecular weight) of the prepolymer is
200-400, Mw/Mn (number average molecular weight) 1.0-1.2
It is characterized by consisting of a combination of liquid A, which has been adjusted to have the following properties, and liquid B, which contains a curing agent or a curing agent and a catalyst, which is added to liquid A to prepare a coating agent at the time of use. The gist is silicon alkoxide coating agents. This invention will be explained in detail below. In this invention, as silicon alkoxide,
Silicon alkoxide represented by the chemical formula R _N Si(OR') _4-o [where n = 0 to 2, R is an alkyl group having 1 to 4 carbon atoms, and R' is an alkyl group having 1 to 4 carbon atoms] The main component is silica sol, which is a suitable filler, and other fillers added to this include inorganic substances such as TiO ₂ . in particular,
For example, 30 to 200 parts by weight (solid content in the case of silica sol) of Si(OR _′ ) ₄ or silka sol (either organosilica sol or water-dispersed silica sol) as the SiO 2 component, RSi as the RSiO _3/2 component Preferably, 100 parts by weight of (OR') ₃ and 13 to 50 parts by weight of R ₂ Si(OR') ₂ as the R ₂ SiO component are blended. For this combination, 5
It becomes easier to obtain a thick coating film suitable for use as a building material, with a thickness of about 10 μm (it is possible to increase the thickness to about 20 to 40 μm by adding pigments, etc.). Furthermore, surfactants, thickeners, colorants, etc. may be added depending on the purpose. Liquid A is a prepolymer obtained by adding and mixing a diluting alcohol, a curing agent (water), and a catalyst to the silicon alkoxide (since the main chain is composed of siloxane bonds, hereinafter referred to as "siloxane prepolymer"). ”).
The siloxane prepolymer has an Mw (weight average molecular weight) of 200 to 400 and an Mw/Mn (number average molecular weight) of
It is adjusted to be 1.0 to 1.2. Solution A prepared in this way can be stored at room temperature for several months or more if kept tightly capped. If Mw is less than 200, the product will have storage stability, but it will take too long to ripen when used. If it exceeds 400, storage stability may decrease,
The life may be shortened, or the desired high hardness coating film may not be obtained. Moreover, when Mw/Mn exceeds 1.2, storage stability decreases. In liquid A, 80% or more, preferably 90% or more of the terminals of the siloxane prepolymer are preferably alkoxides. In other words, by converting the terminals of the siloxane prepolymer into alkoxide and eliminating residual moisture, the following results can be obtained: ≡Si−OR+H ₂ O→≡Si−OH+ROH ≡Si−OR+HO−Si≡→≡Si−O−Si≡+ROH ≡Si−OH+HO− It is preferable to prevent the three reactions Si≡→≡Si-O-Si≡+H ₂ O from occurring to improve storage stability. If it is less than 80%, the reaction may proceed during storage and result in polymerization, or the coating film may not have sufficient hardness after painting. Then, the end of the siloxane prepolymer is prepared as described above, and at the time of use, liquid B is added to quickly cause the above three reactions to quickly obtain the desired coating agent. And make it possible to have a long life. Mw, Mw/Mn, and the ratio of alkoxide at the end of the siloxane prepolymer are controlled by controlling the amounts of water and catalyst added as a curing agent, but the influence of water is particularly strong. The amount of water added is 1wt% relative to silicon alkoxide.
The content is preferably 12 wt% or less. When it is less than 1wt%,
It has good storage stability, but takes a long time to ripen. On the other hand, if it exceeds 12 wt%, problems will arise in storage stability. Examples of catalysts include sulfuric acid, hydrochloric acid, sulfuric acid,
Phosphoric acid, perchloric acid, formic acid, acetic acid, propionic acid,
At least one type of acidic catalyst is used, such as a dilute solution of an inorganic acid and/or an organic acid using oxalic acid, citric acid, malonic acid, trichloroacetic acid, etc. alone or in combination. When using an acidic catalyst, the amount added is based on the amount contained in liquids A and B based on the silicon alkoxide.
50ppm~5000ppm, more preferably 50ppm~
It is 1000ppm. Below 50ppm, the ripening time becomes very long. If it exceeds 5000 ppm, there is a tendency for storage stability and life to be adversely affected. In addition, when using the above-mentioned acidic catalyst in the range of 50 to 5000 ppm, it is preferable to add at least 20 wt % or more of water as a curing agent to the solid content of the coating liquid. Otherwise, there is a tendency that sufficient film-forming properties cannot be obtained. As the diluted solution, lower alcohols such as methanol and ethanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, acetic acid ester, etc. are used alone or in combination. When using, add liquid B to liquid A to increase Mw.
400-1600, more preferably 500-1600, Mw/
It is prepared so that Mn is 1.1 to 1.8, more preferably 1.2 to 1.8. The B liquid consists of at least a curing agent such as water, and a catalyst, a solvent, etc. are added as necessary. When Mw is less than 400, cracks occur easily during film formation, making it difficult to overcoat, and furthermore, peeling tends to occur. On the other hand, if it exceeds 1600, the gloss and transparency may decrease, or the coating film hardness may decrease, or it may become difficult to recoat. When Mw/Mn is less than 1.1, the coating film tends to crack or peel easily. Mw/Mn is 1.8
If it exceeds 50%, the gloss, transparency and hardness of the coating film tend to be insufficient. Note that the above values of Mw and Mw/Mn exclude the prepolymer bonded to the filler when the coating agent contains the filler. The B liquid consists of at least a curing agent such as water, and a catalyst and a solvent are added as necessary. In this case, the amount of water added as a hardening agent is 30 to 200 wt based on the solid content of the coating agent.
%, preferably in the range of 40 to 170 wt%. The solid content here refers to the content that ultimately remains as a coating film. If the amount added is less than 30wt%, the ends of the siloxane prepolymer remain alkoxide, making it difficult for polymerization to proceed and forming a coating film.
This tends to lead to a decrease in film-forming properties and the occurrence of cracks. Moreover, if it exceeds 200wt%, polymerization will progress too much and the life will tend to be shortened. In addition to the catalysts mentioned above, the following catalysts may be used for liquids A and B. For example, (C ₅ H ₅ ) _o MeX _4-o (hereinafter referred to as "cyclopentadiene catalyst") can be used. Specifically, there are dicyclopentadienyl zirconium dichloride, dicyclopentadienyl titanium dichloride, and the like. The amount of this catalyst added is 130 ppm to silicon alkoxide.
It is preferably 13000 ppm or less, particularly 400 to 7000 ppm.
Below 130 ppm, there is almost no catalytic effect.
If it exceeds 13,000 ppm, no increase in catalytic effect can be expected and the life tends to be shortened. Even if an acidic catalyst and a cyclopentadiene catalyst are used in combination, the appropriate value of the amount added does not change. Moreover, aminosilane can also be used as a catalyst. The amount of aminosilane added is based on silicon alkoxide, regardless of the amount of acidic catalyst added.
100ppm~10000ppm or less, especially 200~7000ppm
is preferred. When the amount added is less than 100 ppm, there is almost no catalytic effect. If it exceeds 10,000 ppm, the life of the liquid tends to be shortened and the hardness of the coating film tends to decrease. As the aminosilane, γ-amitopropyltriethoxysilane [H ₂ N (CH ₂ ) ₃ Si (OC ₂ H ₅ ) ₃ ],
N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane [ _H2N ( _CH2 ) _2NH ( _CH2 ) _3Si
(OCH ₃ ) ₃ ], N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane [H ₂ N
(CH ₂ ) ₂ NH (CH ₂ ) ₃ SiCH ₃ (OCH ₃ ) ₂ ]. Furthermore, the following catalysts can also be used. Metal salts of inorganic acids, metal salts of organic acids, quaternary ammonium salts of inorganic acids, quaternary ammonium salts of organic acids, amine salts of inorganic acids, and amine salts of organic acids can be used as catalysts. In this case, the types of acids include hydrochloric acid, nitric acid, phosphoric acid, formic acid, acetic acid, propionic acid, etc., and the types of metals include Pb,
There are Fe, Co, Mn, Zn, etc. Types of amines include trimethylamine, triethylamine, n
-butylamine, etc. Moreover, metathesis salts of the above-mentioned salts can also be used as catalysts. The amount added is 50 to 15000 ppm to silicon alkoxide.
A range of is preferred. If it is less than 50 ppm, the catalytic effect is too small and there is little point in adding it, and if it exceeds 15,000 ppm, not only will the catalytic effect not increase, but there will also be a tendency for the life to be shortened and the coating hardness to decrease. Organotin compounds can also be used as catalysts. Examples include dibutyltin methoxide, dibutyltin dilaurate, dibutyltin dioctate, and the like. The amount added is 50 to 50% to silicon alkoxide.
A range of 15000 ppm is preferred. If it falls below 50ppm,
The catalytic effect is too low, so there is little point in adding it.
If it exceeds 15,000 ppm, not only will there be no increase in catalytic activity, but there will also be a tendency for life to be shortened and coating film hardness to decrease.When using multiple of the catalysts listed above, the preferred addition amount for each is used individually. It is desirable to use within the range. The above preparation is preferably carried out at a temperature of 80°C or lower. The silicon alkoxide coating agent thus prepared can form a coating film on the surface of the object by being applied and heated. The heating conditions are preferably 50 to 200°C. If it is below 50℃, it will be difficult to cure, and if it exceeds 200℃, it will tend to crack easily. The painting method is
Examples include, but are not limited to, spray coating, roll coating, flow coater coating, and dip coating. Next, Examples 1 to 29 and Comparative Examples 1 to 3 will be explained. A silicon alkoxide as a main ingredient and a solvent were blended in the following proportions. Methyltrimethoxysilane 100 parts by weight Tetraethoxysilane 20 parts by weight IPA-Silica sol (OSCAL1432, SiO ₂ 30%)
105 parts by weight Dimethyldimethoxysilane 30 parts by weight Isopropanol (IPA) 100 parts by weight (Note) IPA-silica sol is manufactured by Catalysts Kasei Co., Ltd. This silicon alkoxide was blended with the types of catalysts shown in Table 1 and water in the amounts shown in the table to prepare Solution A. In addition, the formulation is in an atmosphere of 25℃,
Stirring was performed at 1000 rpm or 500 rpm for 10-30 minutes. After storing this solution A in a sealed state at 25° C. for more than one week, the thickening of the solution, gelation, changes in molecular weight, and the appearance of alkoxides at the terminals of the siloxane prepolymer were observed. The results are shown in Table 1. The molecular weight was measured using GPC (gel permeation chromatography manufactured by Toyo Soda Co., Ltd.), and the state of the alkoxide at the end of the prepolymer was measured using FT (Fourier transform)-IR (manufactured by JEOL Ltd.). , FT (Fourier transform)
- Measured using NMR (manufactured by JEOL Ltd.). Next, water and catalyst in the amounts shown in Table 1 were added to Solution A to prepare a coating solution.
The formulation is 10% at 1000rpm in an atmosphere of 25℃.
Stirring was performed for a minute. During this preparation, the time required for the coating solution to reach Mw of 400 or higher and Mw/Mn of 1.1 or higher (aging time); /Measure the time (life) until Mn exceeds 1.8, and use the results as the first
Shown in the table. In Table 1, E of the catalyst is hydrochloric acid, G is dicyclopentadienyl zirconium dichloride, T is dicyclopentadienyl titanium dichloride, and N is N-(β-aminoethyl)-γ.
-amitopropyltrimethoxysilane, Z is (C ₂ H ₅ ) ₂ ZrCl ₂ , GA is ammonium formate, D is dibutyltin dilaurate, and γ is γ-aminopropyltriethoxysilane. Next, Examples 30 to 32 and Comparative Examples 4 and 5 will be described. Silicon alkoxide as the main ingredient, solvent, etc. were blended in the following proportions. Methyltrimethoxysilane 100 parts by weight IPA-silica sol (OSCAL1432, SiO ₂ 30%)
60 parts by weight Isopropanol (IPC) 100 parts by weight Then, as shown in Table 1 (Part 5), catalyst and water were added in the amounts shown in the table, and A
A liquid was prepared. The formulation was performed under an atmosphere of 25° C. with stirring at 1000 rpm or 500 rpm for 10 to 30 minutes. After storing this solution A in a sealed state at 25°C for more than one week, the same procedures as in Example 1 were carried out to determine the viscosity of the solution, gelation, changes in molecular weight, and the appearance of alkoxides at the terminals of the siloxane prepolymer. I saw it. The results are shown in the table. Next, water in the amount shown in Table 1 (Part 5) was added to Solution A to prepare a coating solution.
The formulation is 10% at 1000rpm in an atmosphere of 25℃.
Stirring was performed for a minute. Further, during preparation, the aging time and life were measured in the same manner as in the previous case, and the results are shown in Table 1 (Part 5). In addition, E of the catalyst in Table 1 (Part 5) is hydrochloric acid.

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[Table] As shown in Table 1, the products of each example had better storage stability, shorter maturation time, and longer life than those of the comparative example. Furthermore, by blending water and catalyst with liquid A, Mw is 400,
Coating liquid in the state until Mw/Mn becomes 1.1 (first state), Mw is 400 or more, Mw/Mn is 1.1
After that, Mw becomes 1600 and Mw/Mn becomes 1.8.
For each of the coating liquid in the state where Mw exceeds 1600 (second state), the coating solution in which Mw/Mn exceeds 1.8 (third state), a 10 cm square with a thickness of 1 mm is used as a base material. Spray coated on an alumina substrate, set at room temperature for 2 minutes, and heat-treated in a dryer at 130°C for 20 minutes. In this case, a coating film with a thickness of 5 μm was obtained. The film forming properties and the state of the coating film were examined at that time, and the results are shown in Table 2. In the case of overcoating, the same conditions were applied. A JISA5403 asbestos slate flexible board (thickness 6 mm, 12 cm x 18 cm) was prepared, and Table 2 (Parts 1 to 1) was prepared for the examples shown in Table 4.
In 3), the thickness is 10μm, and in Table 2 (Part 4), it is 5μm.
A coating film with a thickness of
We investigated the occurrence of cracks. I did a test. The results are shown in Table 4. Note that a primer layer having a thickness of 5 μm was previously formed on this plate as a primer layer. As the material for forming the primer layer, a silicon-modified urethane material (manufactured by Toshiba Silicone Co., Ltd.) was used. Further, Table 3 shows the hardness of the coating film obtained from the coating liquid in each state (first to third states) in each of the above examples and some of the comparative examples. In addition,
Hardness is pencil hardness measured according to JIS K-5400.

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〔Effect of the invention〕

Since the silicon alkoxide coating agent according to the present invention has the above-mentioned structure, it has good storage stability when not in use and is suitable for large-scale storage such as for building materials, and has a short aging time when in use. It has a short and long life, and a glossy and highly hard coating film can be stably obtained.

Claims (1)

[Scope of Claims] 1. A silicon alkoxide-based coating agent in which a catalyst and a curing agent are added to silicon alkoxide, R _o Si (OR') _4-o [where n = 0 to 2, R is the number of carbon atoms] 1 to 4 alkyl group, R' is an alkyl group having 1 to 4 carbon atoms] A catalyst and a curing agent are added to silicon alkoxide and silica sol represented by the chemical formula, and the Mw (weight average molecular weight) of the siloxane prepolymer is
200-400, Mw/Mn (number average molecular weight) 1.0-1.2
It is characterized by consisting of a combination of liquid A, which has been adjusted to have the following properties, and liquid B, which contains a curing agent or a curing agent and a catalyst, which is added to liquid A to prepare a coating agent at the time of use. Silicon alkoxide coating agent. 2 The preparation of the coating agent has a Mw of 400 to 1600,
The silicon alkoxide coating agent according to claim 1, which is applied so that Mw/Mn is 1.1 to 1.8. 3. The silicon alkoxide coating agent according to claim 1 or 2, wherein 80% or more of the terminal ends of the siloxane prepolymer are alkoxide. 4 The curing agent added to liquid A is water, and the amount added is 30 to 200 wt based on the solid content of the coating agent.
% of the silicon alkoxide coating agent according to any one of claims 1 to 3. 5 As a catalyst (C ₅ H ₅ ) _o MeX _4-o [However, C ₅ H ₅
is cyclopentadiene, Me is an element from period 4 to 6 of group of the periodic table, X is a halogen element, n is 1 to
It is 3. ], aminosilane, inorganic acid, organic acid, metal salt of inorganic acid, metal salt of organic acid, quaternary ammonium salt of inorganic acid, quaternary ammonium salt of organic acid, amine salt of inorganic acid, amine of organic acid Claims 1 to 4 in which at least one of the group consisting of salts and organotin compounds is used.
The silicon alkoxide coating agent according to any one of the preceding paragraphs.