JPH0383877A - Inorganic coating material composition - Google Patents

Abstract

PURPOSE:To improve crack resistance of coating film, comprising an oligomer prepared by hydrolyzing a mixture consisting essentially of three kinds of silicon compounds shown by the formula and subjecting to polycondensation as an essential component and having specific molecular weight and molecular weight distribution. CONSTITUTION:This inorganic coating material composition comprises an oligomer prepared by hydrolyzing a mixture consisting essentially of three kinds of silicon compounds and subjecting to polycondensation at one stage as an essential component. The three kinds of compounds are composed of 20-200 pts.wt. silicon compound shown by the general formula (R<1> and R<2> are each monofunctional group) wherein n=0 and/or colloidal silica, 100 pts.wt. silicon compound wherein n=1 and 27-80 pts.wt. silicon compound wherein n=2. The oligomer has 500-2,300 (calculated as polystyrene) weight-average molecular weight and 1.1-3Mw/Mn (Mn: number-average molecular weight) molecular weight distribution.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to an inorganic coating material, particularly an inorganic coating material composition containing silicon alkoxide as a main component and forming a coating film with excellent weather resistance and hardness. .

[Conventional technology]

BACKGROUND ART Inorganic coating material compositions containing silicon alkoxide as a main component have been studied in various ways because they are weather resistant and form highly hard coatings. For example, in JP-A-51-2736, a product containing colloidal silica and a partial condensate of R3i (OH)3 is disclosed, whereas in JP-A-56-125466, colloidal silica and a partial condensate of R31(oH)s are used. A mixture of condensates and linear oligosiloxanes is shown. Also, JP-A-5
No. 3-130732 discloses a composition containing colloidal silica, dialkyldialkoxysilane and alkyltrialkoxysilane.

[Problem to be solved by the invention]

However, since the coating film of these conventional inorganic coating material compositions is hard, if the base material undergoes considerable dimensional changes such as cement-based building materials, it cannot follow the movement of the base material due to the dimensional change. Cracks and peeling often occur in the paint film.

Therefore, this invention has developed an inorganic coating material that does not impair the characteristics of the silicon alkoxide coating material and that does not cause cracks in the coating film at all or rarely even when applied to a substrate with relatively large dimensional changes. The object of the present invention is to provide a bottom made of coating material.

[Means to solve the problem]

In order to solve the above problems, an inorganic coating material composition according to the present invention is produced by hydrolyzing and polycondensing a mixture containing the following (a), ('l:I) and (0) as main components in one step. It is said that the prepolymer formed by the reaction is an essential component. Moreover, the prepolymer has a weight average molecular weight Mw of 500 to 2300 in terms of polystyrene,
And the molecular weight distribution M w / Mn is 1.1 to 3.0 (
Mn is a number average molecular weight).

(a) A silicon compound and/or colloidal silica represented by n=0 in the following general formula (1) from 20 to
200 parts by weight (hereinafter, "parts by weight" is simply referred to as "parts")
.

(b) 100 parts of a silica compound represented by n=+++l in the following general formula (1).

(c1 27 to 80 parts of a silicon compound represented by nm 2 in the following general 2).

R', Si (OH) 4-IT IT-■
(2) In the formula, R1 and R8 are not particularly limited; ) and more! It is the basis of valence. In addition, R wealth is
For example, the main raw material is an alkyl group having 1 to 4 carbon atoms or an alkyl group. For example, (a) above, (
b) and (c) are silicon alkoxides.

The inorganic coating material composition of the present invention includes, for example,
Each of the above raw material silicon compound components (al, (b) and (c)
) is diluted with a suitable solvent, a curing agent and a catalyst are added thereto in the required amounts, and the hydrolysis and polycondensation reactions are carried out in one step to produce a prepolymer.

The molecular weight of the prepolymer is such that the weight average molecular weight Mw is 500 to 2300 in terms of polystyrene, and the molecular weight distribution M
w/M n < M n is the number average molecule N) is 1.
Must be 0 to 3.0, preferably Mw=60
0 to 1500, and Mw/Mn = 1.2 to 1.8
It is. When the molecular weight distribution of the prepolymer is smaller than the above range, curing shrinkage during polycondensation tends to increase, and cracks tend to occur in the coating film after baking. On the other hand, when it is larger than the above range, the reaction tends to be too slow and hard to cure, or even if cured, the coating film tends to be soft, or the leveling properties of the coating film tend to be very poor. When the weight average molecular weight of the prepolymer is smaller than the above range, there is a problem in that baking sometimes causes cracks in the coating film, and when it is larger, there is a problem in that the leveling properties of the coating film are poor.

The colloidal silica is obtained by dispersing particulate silica components in water, an organic solvent such as methanol, or a mixed solvent thereof, but the particle size, type of solvent, etc. are not particularly limited. In addition, when colloidal silica is used as the component (a), the above blending ratio is a part by weight that also includes the dispersion medium.

As the curing agent used in this invention, water is used, for example, and the amount thereof is not particularly limited, but it is preferably 45% or less, more preferably 25% or less in weight% of the coating material composition. Good.

Catalysts used in this invention are not particularly limited, but include acidic catalysts such as dilute solutions of inorganic acids such as hydrochloric acid, phosphoric acid, and sulfuric acid, and organic acids such as formic acid, acetic acid, and chloroacetic acid, and basic catalysts described later. These can be used alone or in combination of two or more.

Furthermore, when silica sol is used as the component (a), the silica sol is acidic and serves as a catalyst, so there is no need to add anything as a catalyst.

The inorganic coating material composition of this invention has a pH value of 3.
．． By adjusting the molecular weight to 8 to 6.0, it can be stably used within the above molecular weight range. When the pH value is outside the above range, the stability of the coating material composition is poor, and the usable period from the time of paint preparation may be limited.

Here, the pH value adjustment method is not particularly limited, but for example, if the pH value becomes less than 3.8 when mixing raw materials for the coating material, for example, a basic reagent such as ammonia may be used. The pH may be adjusted to within the above range by using the above-mentioned method, and even if the pH value exceeds 6.0, it may be adjusted using an acidic reagent such as hydrochloric acid. In addition, depending on the pH, if the reaction does not proceed with the molecular weight remaining small and it takes time to reach the above molecular weight range, the reaction may be accelerated by heating the coating material, or the reaction may be accelerated with an acidic reagent.
After lowering the H value and proceeding with the reaction, adjust the pH to the specified value using a basic reagent.
It may be possible to return it to a value.

pH adjusted as described above or
If a basic catalyst is added to a coating material that has not been properly prepared, at least during use, that is, before or during use, it will accelerate the condensation reaction and reduce the crosslinking points in the coating film. Since the amount can be increased, a stable coating film with good crack resistance can be obtained. Further, by promoting the crosslinking reaction, it is possible to shorten the curing time or lower the curing temperature, so it is economical and has the effect of being applicable to base materials that can only be baked at low temperatures. Examples of basic catalysts include amines (for example, triethanolamine, etc.), amonosilanes (for example, γ-anobrobyltriethoxysilane, N-(β-aminoethyl)-r-amonobyltriethoxysilane, pyrutriethoxysilane, N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane, etc.), inorganic acids (e.g., hydrochloric acid, nitric acid, phosphoric acid, etc.) and organic acids (e.g., formic acid, acetic acid, propionic acid, etc.). etc.) ammonia,
There are salts of trimethylamine, triethylamine, n-butylamine, etc., metathesis salts of inorganic and organic acid salts, and quaternary ammonium salts, but there are no particular limitations on the type and amount added.

In addition to the above-mentioned components, the inorganic coating material composition of the present invention prepared by the above-mentioned method includes, if necessary,
Various colorants, fillers other than the above-mentioned silica sol (organic fillers and/or inorganic fillers; for example, Al-based nasol,
Examples of the diluting solvent include methanol, ethanol, isopropanol (IPA), etc., in which one or more of various additives such as fumed silica, etc.), diluting solvent, thickener, surfactant, and ultraviolet absorber may be added. Alcohol, ethyl cellosolve, butyl cellosolve, ethylene glycol,
Examples include ethylene glycol monomethyl ether,
These may be used alone or in combination.

The method for applying the inorganic coating material composition of this invention includes:
Examples include spray coating, roll coating, flow coater coating, dip coating, etc., and are not particularly limited. Further, the drying/baking conditions after coating are not particularly limited either, but it is preferably carried out at about 60 to 200°C.

Furthermore, the inorganic coating material composition of the present invention may be applied directly to the base material (object to be coated), or depending on the base material, it may be coated on top of the base material after a surface treatment such as a primer. By preparing the composition to a good value of 0 or more, when painted on base materials with large dimensional changes such as cement-based building materials,
It is possible to produce an inorganic coating material in which no or very little cracking or peeling occurs in the coating film. Further, by using the composition of the present invention, a coating film without cracks or peeling can be formed even if the film thickness is increased to 5 nm or more.

The resulting coating film does not impair the characteristics of the silicon alkoxide coating material, that is, its excellent weather resistance and hardness.

[For production]

If the proportion of component (a) is less than 20 parts or more than 200 parts, there is a problem that crack resistance is poor. If the proportion of component (c) is less than 27 parts, there will be a problem of poor crack resistance, and if it exceeds 80 parts, there will be a problem that the coating film will be too soft and impractical.

If the Mw of the prepolymer, which is an essential component of the inorganic coating material composition of the present invention, is less than 500, there is a problem that cracks may sometimes occur in the coating film due to baking;
If it exceeds 00, there is a problem that the leveling properties of the coating film are poor. Mw/Mn of the same prepolymer is 1.1
If it is less than 3°, the curing shrinkage during polycondensation tends to increase, and the coating tends to crack after baking. If it exceeds 3°0, the reaction is too slow and it may be difficult to cure. Or, even after curing, the coating film tends to be soft, or the leveling properties of the coating film tend to be very poor.

A mixture containing the above components (a), (b) and (0) as main components is subjected to hydrolysis and polycondensation reaction in one step to prepare a prepolymer having the above specific Mw and Mw/Mn. Performance such as crank resistance is better when the prepolymer is prepared by performing the hydrolysis and polycondensation reactions in two steps.

〔Example〕

Specific examples and comparative examples of the present invention are shown below, but the present invention is not limited to the following examples.

For implementation, the base material was JIS A3403 asbestos slate flexible board 61 m thick (JXlBCIl
It was cut to size and used. Further, as a primer, a silicone-modified urethane primer manufactured by Toshiba Silicone Co., Ltd. was applied to a film thickness of 3 nm.

The following coating material composition was spray coated onto the base material coated with the primer so that the film thickness after curing was 5 nm, and after setting for 5 minutes, it was baked at the temperature shown below.

In addition, for the measurement of molecular weight, HLC802A and HLC8020 manufactured by Tosoh Corporation were used as GPC (gel permeation chromatography) devices.

Examples 1 to 6 and Comparative Examples 1 to 6 are based on claims 1 and 2.
Examples and comparative examples of the invention.

Example 1 - 100 parts of methyltrimethoxysilane, 10 parts of tetraethoxysilane, 10 parts of IPA organosilica sol ("○5CAL1432" manufactured by Catalyst Kakai Kogyo Co., Ltd., Si○, content 30%), 30 parts of dimethyldimethoxysilane and 100 parts of IPA were mixed, and further, 80 parts of Hso was added and stirred. Place this in a constant temperature bath at 60℃,
The molecular weight of the prepolymer was adjusted to Mw=870 (in terms of polystyrene) and Mw/Mn=1.31 to obtain an inorganic coating material composition. As mentioned above, since the silica sol is acidic, no catalyst was added.

Thereafter, it was painted and baked at 150° C. for 30 minutes.

Examples 2 to 6 and Comparative Examples 1 to 6 - Prepolymers having the molecular weights shown in Table 1 were produced in the same manner as in Example 1 using the formulations shown in Table 1 to obtain inorganic coating material compositions. . However, in Comparative Example 5, the temperature in the constant temperature bath was set to 40°C.

Thereafter, painting and baking were performed in the same manner as in Example 1.

Each of the obtained coatings was immersed in 60°C warm water for 8 hours -1
A repeated test was conducted in which one cycle was drying for 6 hours, and the number of cycles at which cracks occurred in the coating film was recorded. The results are shown in Table 1.

As shown in Table 1, each coating film of Examples is
In other words, the coating material of the example has a very large number of crack generation cycles compared to the above example, and is less likely to crack when coated on a substrate with relatively large dimensional changes. In Comparative Example 4, the coating film was too soft to be practical. In Comparative Example 5, the leveling property of the coating film was extremely poor;
It wasn't practical. In Comparative Example 6, cracks appeared in the coating film after curing by baking.

Examples 7 to 11 and comparative examples 7.8 below are based on claims 3
Examples and comparative examples of the invention.

Examples 7 to 11 A prepolymer was prepared in the same manner as in Example 5, and the molecular weight of the prepolymer was Mw-620 (in terms of polystyrene), Mw/Mn=! , 20, the respective pH values were adjusted with ammonia water (containing 1% ammonia) to the values shown in Table 2 to obtain inorganic coating material compositions.

When each of the obtained inorganic coating material assemblies was painted and baked at 150° C. for 30 minutes, a good coating film was obtained. On the other hand, each coating material was placed in a plastic container, sealed tightly, and stored in an atmosphere at 40° C. for 3 months. Painting and baking were performed once again using the coating material after storage, and it was confirmed whether there was any change in film-forming properties. The results are shown in Table 2.

- Comparative Example 7 - An inorganic coating material composition was obtained in the same manner as in Example 7, except that the pH value was adjusted to 3.5.

When this coating material was applied and baked at 150°C for 30 minutes, a good coating film was obtained.

On the other hand, put the same coating material in a plastic container, seal it tightly, and
It was stored in an atmosphere at 0°C for 3 months. When I painted and baked it again with the coating material after storage, a film was formed, but the leveling was extremely poor.

Comparative Example 8 An inorganic coating material composition was obtained in the same manner as in Example 7, except that the pH value was adjusted to 6.3.

When this coating material was applied and baked at 150°C for 30 minutes, a good coating film was obtained.

On the other hand, put the same coating material in a plastic container, seal it tightly, and
It was stored in an atmosphere at 0°C for 3 months. When the ε roller was painted and baked again with the coating material after storage, no paint film was formed.

Table 2 (Note) ○: A good coating film was obtained.

The following Examples 12 to 16 and Comparative Examples 9 to 11 are examples 12 to 11 which are examples and comparative examples of the invention of claim 4.
16 and Comparative Examples 9 to 11 - 100 g of the composition of Example 8
Inorganic coating material compositions were obtained by adding ammonium formate in the weights shown in Table 3.

Since hardening is accelerated, we aimed to reduce the temperature and shorten the baking time, as shown in Table 3, by changing the baking conditions, painting and baking, and conducting repeated hot water-drying tests. Performance was evaluated. In addition, in order to check the degree of hardening of the coating film, a regular glass plate (soda glass, 100 mm) was used.
80m) was similarly painted and baked, and the pencil hardness was measured.

Table 3 As shown in Table 3, the examples in which ammonium formate was added had a lower temperature and/or shorter baking time than the comparative examples in which ammonium formate was not added.
The coating film was less prone to cracking and had high hardness.

〔Effect of the invention〕

The inorganic coating material composition of the present invention has as an essential component a prepolymer obtained by one-step hydrolysis and polycondensation reaction of the above-mentioned specific silicon compound, and the prepolymer has the above-mentioned specific weight average molecular weight and molecular weight distribution. Therefore, even when coating is applied to a substrate with relatively large dimensional changes, cracks are less likely to occur in the coating film.

In the inorganic coating material composition of the present invention, the prepolymer has Mw=600 to 1500 and Mw
/ M n = 1.2 to 1.8, the coating film is less prone to cranking, the reaction is not too slow, the coating film is less likely to be soft, and the leveling property of the coating film is better. It might get better.

In the inorganic coating material composition of this invention, the pH
When the value is adjusted to 3.8 to 6.0, there is an added effect that the stability of the bottom of the coating material is improved.

In the inorganic coating material composition of the present invention, if a basic catalyst is added at least during use, the crack resistance of the coating film will be better, the curing time will be shortened, or It is possible to lower the curing temperature.

Claims (1)

[Scope of Claims] 1 A prepolymer obtained by hydrolyzing and polycondensing a mixture containing the following (a), (b), and (c) as main components in one step is an essential component, and the weight of the prepolymer is An inorganic coating material composition having an average molecular weight Mw of 500 to 2300 in terms of polystyrene and a molecular weight distribution Mw/Mn of 1.1 to 3.0 (Mn is number average molecular weight). (a) 20 to 20 silicon compounds and/or colloidal silica represented by n=0 in the following general formula (1)
0 parts by weight. (b) 100 parts by weight of a silicon compound represented by n=1 in the following general formula 1. (c) 27 to 80 parts by weight of a silicon compound represented by n=2 in the following general formula 1. R^1_nSi(OR^2)_4_-_n...(1)
[In formula (1), R^1 and R^2 are each a monovalent group, and if there are multiple R^1 and R^2, all R^1 or R^2 are the same may be a group, and one or more may be different. ] 2 The prepolymer has Mw=600 to 1500, and
The inorganic coating material composition according to claim 1, wherein Mw/Mn=1.2 to 1.8. 3. Claim 1, wherein the pH value is adjusted to 3.8 to 6.0.
Or the inorganic coating material composition according to 2. 4. The inorganic coating material composition according to claim 1, wherein a basic catalyst is added at least during use.