JPS6314021B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a composition for forming a polyurethane coating with good drying properties. A polyurethane coating composition composed of an aliphatic or alicyclic polyisocyanate compound and a polyhydroxyl compound has better water resistance, solvent resistance, chemical resistance, and stain resistance than a polyurethane coating composition obtained from an aromatic polyisocyanate compound. Recently, it has been attracting attention in the field of paints because it has excellent properties such as durability and stability against sunlight and ultraviolet rays. However, although these aliphatic or alicyclic polyisocyanate compounds provide coating compositions with the above-mentioned excellent properties, they react more slowly with polyhydroxyl compounds than aromatic polyisocyanate compounds, and dry out more easily. It has the disadvantage of being inferior in quality. Conventionally, in a polyurethane composition consisting of a polyisocyanate compound and a polyhydroxyl compound, a method of adding a catalyst has been known in order to promote the reaction between the isocyanate group and the hydroxyl group, and examples of such a catalyst include, for example. , organometallic compounds such as dibutyltin dilaurate,
Tertiary amine compounds such as triethylenediamine have been used alone or in combination (Ind. Eng. Chem. Vol. 52 (7), pp. 609-610,
Publication No. 35-5057, Publication No. 35-5058, Publication No. 35-5058, Publication No. 35-5058, Special Publication Sho
36-13035, Special Publication No. 36-16947). However, although the addition of an organometallic compound to a polyurethane coating composition shortens drying time, it also significantly shortens the pot life of the composition, making it difficult to handle. Further, when a tertiary amine compound is used, drying cannot be improved unless a large amount is added, and in this case, the coating has a disadvantage of poor weather resistance. The present inventors, in Japanese Patent Application No. 53-63820,
We proposed a polyurethane coating composition with good drying properties, but due to the use of a large amount of aromatic carboxylic acid,
In some cases, the physical properties of the coating composition were impaired. The present inventors have conducted extensive research in order to overcome the drawbacks of these conventional polyurethane coating compositions and to develop a polyurethane coating composition that dries quickly and has a sufficiently long pot life, and as a result, the present invention has been developed. I arrived at the eggplant. That is, the present invention provides (A) an aliphatic or alicyclic polyisocyanate compound having two or more isocyanate groups in the molecule, (B) a polyhydroxyl compound having two or more hydroxyl groups in the molecule, (C) Organometallic compound and (D) General formula (In the formula, n is 0 or an integer of 1 to 4, and X is a hydrogen atom, a sulfo group, a hydroxyl group, an amino group, a halogen, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group) (R in the formula is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms);
The total weight of (D) is 0.01 to the total weight of (A) and (B)
3.0% by weight, and the amount of (C) is less than the amount of (D).
The present invention relates to a coating forming composition characterized in that the amount thereof is in the range of 0.1 to 10% by weight. Examples of aliphatic or alicyclic polyisocyanate compounds having two or more isocyanate groups used as component (A) of the present invention include 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2 , 4,4-trimethyl-1,6-hexamethylene diisocyanate,
Examples include 2,6-diisocyanate caproate, 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate, dicyclohexylmethane-4,4'-diisocyanate, hydrogenated xylylene diisocyanate, and hydrogenated tolylene diisocyanate. Furthermore, compounds obtained by reacting these aliphatic or alicyclic diisocyanate compounds with active hydrogen compounds such as water, formic acid, ethylene glycol, polyethylene glycol, neopentyl glycol, glycerin, trimethylolpropane, hexanetriol, pentaerythritol, etc. It is a compound having an isocyanate group. Particularly suitable are polyisocyanate compounds obtained from 1,6-hexamethylene diisocyanate and water or from said diisocyanate and trimethylolpropane. On the other hand, the polyhydroxyl compound having two or more hydroxyl groups used as component (B) of the present invention is a polyhydroxyl compound used in the general urethane-related technical field, such as acrylic polyol, polyester polyol, polyester polyol, etc. These include caprolactone polyol and polyether polyol. The quantitative ratio of the polyisocyanate compound as component (A) and the polyhydroxyl compound as component (B) is within a commonly used range. That is, the equivalent ratio of the isocyanate groups in component (A) to the hydroxyl groups in component (B) (NCO/OH equivalent ratio) is in the range of 0.80 to 1.50, preferably in the range of 0.90 to 1.20.
If the NCO/OH equivalent ratio is less than 0.80, physical properties such as water resistance, solvent resistance, chemical resistance, and weather resistance will deteriorate.
Moreover, if it is larger than 1.50, the drying property becomes too slow, which is not preferable in practice. Representative examples of the organometallic compound used as component (C) of the present invention include dibutyltin dilaurate, dibutyltin diacetate, dibutyltin di(2-ethylhexoate),
stannous 2-ethylcaproate, stannous oleate, copper naphthenate, lead naphthenate, zinc naphthenate, cobalt naphthenate, alkyltin trihalide, dialkyltin dihalide, trialkyltin halide, tetraalkyltin compound, etc. be. Among these organometallic compounds, particularly preferred are:
These are dibutyltin diacetate, dibutyltin dilaurate, and dibutyltin di(2-ethylhexoate). Examples of aromatic carboxylic acids represented by the general formula () used as component (D) of the present invention include:
Benzoic acid, phenyl acetic acid, 3-phenylpropionic acid, 4-phenylbutyric acid, 5-phenylvaleric acid,
Methyl group, ethyl group, propyl group, butyl group, methoxy group, ethoxy group, propoxy group, butoxy group, hydroxyl group, amino group at the ortho, meta, and para positions of O-sulfobenzoic acid and these aromatic carboxylic acids. , halogen, and a sulfo group. Further, examples of the aromatic carboxylic acid represented by the general formula () include phthalic acid, isophthalic acid, terephthalic acid, and monomethyl esters thereof;
Examples include any substituted compound selected from monoethyl ester, molepropyl ester, and monobutyl ester. Among these aromatic carboxylic acids, particularly preferred are 3-phenylpropionic acid, 4-phenylbutyric acid, 5-phenylvaleric acid, O-sulfobenzoic acid, O-methoxybenzoic acid, O-ethoxybenzoic acid, Phthalic acid, phthalic acid monomethyl ester,
It is phthalic acid monoethyl ester. The organometallic compound and the aromatic carboxylic acid are added in an amount of 0.01 to 3.0% by weight based on the total of the polyisocyanate compound and the polyhydroxyl compound. or,
The organometallic compound is added in an amount of 0.1-10% by weight of the aromatic carboxylic acid. The total amount of organometallic compound and aromatic carboxylic acid is 0.01% by weight or less, or the organometallic compound is 0.1% by weight relative to aromatic carboxylic acid.
In the following, no significant effect on promoting dryness is observed. Furthermore, if the total amount of the organometallic compound and the aromatic carboxylic acid is 3.0% by weight or more, or if the organometallic compound is 10% by weight or more relative to the aromatic carboxylic acid, the drying properties are improved, but on the other hand, the drying properties of the composition are improved. Since the viscosity increases too quickly, the pot life of the coating-forming composition is shortened, which is undesirable. The addition of organometallic compounds and aromatic carboxylic acids is
It may be added after mixing the polyisocyanate compound and the polyhydroxyl compound, or it may be added to the polyhydroxyl compound in advance and then mixed with the polyisocyanate compound. In any case, it is necessary for the organometallic compound and the aromatic carboxylic acid to coexist in a state where the polyisocyanate compound and the polyhydroxyl compound are substantially unreacted, so that at least both of them can initiate the reaction. must be mixed at the same time. Additives used in the field of polyurethane coatings, such as pigments, dyes, metal powders, leveling agents, thixotropic agents, etc., may be added to the coating forming composition of the present invention as desired without any problem. . After coating the coating composition of the present invention on the object to be coated, the drying method may be, for example, a drying method used for ordinary urethane paints, such as natural drying at room temperature or heat drying. . The present invention will be explained below with reference to Examples, but the scope of the present invention is not limited thereby. Note that all parts used in the examples are parts by weight. The polyisocyanate compounds and polyhydroxyl compounds used in the examples are as follows. (A) Polyisocyanate compound A polyisocyanate compound obtained from 1,6-hexamethylene diisocyanate and water, having a nonvolatile content of 100% by weight, an isocyanate group content of 23.5%, and a viscosity of 2000 centipoise at 25°C. (B) Polyhydroxyl compound Acridik A-801 manufactured by Dainippon Ink & Chemicals Co., Ltd., hydroxyl value 50, non-volatile content 50% by weight
Those with Example 1 Polyisocyanate compound 100 parts Polyhydroxyl compound 640 parts Ethyl acetate 200 parts N-Butyl acetate 130 parts Cellosolve acetate 50 parts Toluene 130 parts Xylene 150 parts 0.64 parts of O-ethoxybenzoic acid was added to the above coating forming composition. , dibutyltin dilaurate 0.013
Table 3 shows the time taken to dry the coating forming composition of the present invention, which was applied to a mild steel plate so as to have a dry film thickness of 50 μm, and allowed to stand at 20° C. Judgment is made by covering the paint film with gauze and placing it on top of it.
A 100g weight is placed on the coating for 1 minute, and the test is carried out at a time when no gauze marks remain on the coating film. Further, Table 3 shows the usable time range in which the coating forming composition can be spray coated after preparation as the pot life. Examples 2 to 7 In place of O-ethoxybenzoic acid and dibutyltin dilaurate in Example-1, coating-forming compositions were prepared in which aromatic carboxylic acids and organometallic compounds shown in Table 1 were added, respectively. Drying properties are shown in Table 3.

[Table] Comparative Examples 1 to 5 Drying time and pot life of coating forming compositions in which conventionally known catalysts shown in Table 2 were added in place of O-ethoxybenzoic acid and dibutyltin dilaurate in Example 1. It is shown in Table 3.

【table】

[Table] Example 8 Polyisocyanate compound 100 parts Polyhydroxyl compound 640 parts Ethyl acetate 200 parts N-Butyl acetate 130 parts Cellosolve acetate 50 parts Toluene 130 parts Xylene 150 parts O-ethoxybenzoic acid 7 parts Dibutyltin dilaurate 0.05 parts Table 4 shows the drying time, pot life, and physical properties of the coating film 7 days after coating of the coating composition. Comparative Example 6 Table 4 shows the drying time, pot life and physical properties of the coating 7 days after coating of the same coating forming composition as in Comparative Example-1. Comparative Example 7 40 O-ethoxybenzoic acid in Example-8
Table 4 shows the drying time, pot life, and physical properties of the coating film after 7 days of coating of the coating-forming composition in which 5 parts and 5 parts of dibutyltin dilaurate were used.

【table】

[Table] The results in Table 3 are shown in the attached drawing, with pot life on the horizontal axis and drying time on the vertical axis. In the figure, -0- indicates the data of Examples 1 to 7 plotted, and -●- indicates the data of Comparative Examples 1 to 5 plotted. The line connecting the examples is clearly below the line connecting the comparative examples, indicating that the drying time is short despite the long pot life.

[Brief explanation of the drawing]

The drawing is a graph showing the relationship between pot life and drying time of Examples and Comparative Examples.

Claims (1)

[Claims] 1. (A) an aliphatic or alicyclic polyisocyanate compound having two or more isocyanate groups in the molecule; and (B) a polyhydroxyl compound having two or more hydroxyl groups in the molecule. , (C) organometallic compound, and (D) general formula (In the formula, n is 0 or an integer of 1 to 4, and X is a hydrogen atom, a sulfo group, a hydroxyl group, an amino group, a halogen, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group.) Or general formula (R in the formula is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.)
The total weight of (D) is 0.01 to the total weight of (A) and (B)
A composition for forming a coating, characterized in that the amount of (C) is in the range of 3.0% by weight, and the amount of (C) is in the range of 0.1 to 10% by weight of the amount of (D). 2. The coating forming composition according to claim 1, wherein the polyisocyanate compound is a polyisocyanate compound obtained from 1,6-hexamethylene diisocyanate and water. 3. The coating forming composition according to claim 1, wherein the organometallic compound is an organotin compound. 4 The organotin compound is dibutyltin dilaurate,
The coating forming composition according to claim 3, which is dibutyltin diacetate or dibutyltin di(2-ethylhexoate). 5 (D) component is general formula (In the formula, n is 0 or an integer of 1 to 4, and X is a hydrogen atom, a sulfo group, a hydroxyl group, an amino group, a halogen, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group.) The coating forming composition according to claim 1, which is a carboxylic acid. 6 The aromatic carboxylic acid of general formula () is 3-phenylpropionic acid, 4-phenyl n-butyric acid, O
-Sulfobenzoic acid, O-ethoxybenzoic acid, the coating forming composition according to claim 5. 7 (D) component is general formula (R in the formula is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.) The coating forming composition according to claim 1, which is an aromatic carboxylic acid represented by the following formula. 8. The coating forming composition according to claim 7, wherein the aromatic carboxylic acid is phthalic acid, monomethyl phthalate, or monoethyl phthalate.