JPH0318676B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention has excellent adhesion, corrosion resistance, and chemical resistance to materials such as metals, plastics, and glass, and is particularly effective against alkaline materials such as cement, mortar, and slate. The present invention relates to an aqueous coating composition exhibiting excellent properties. [Prior Art] Conventionally, silicon compounds have high weather resistance, high strength, chemical resistance, and excellent adhesion to inorganic materials, and have been used as various paints and sealants. In particular, when it comes to paints, while making use of the advantages of silicone compounds such as high hardness and high weather resistance, they are mixed with synthetic resins to compensate for their disadvantages of coating properties, or are mixed with synthetic resins. Various methods have been tried to incorporate it into the For example, water-based paints include mixtures of acrylic emulsions and water-based colloidal silica, and acrylic copolymers in which silicon compounds with unsaturated double bonds and α- and β-unsaturated fatty acids are copolymerized. An aqueous solution of an acrylic copolymer is provided. [Problems to be Solved by the Invention] The conventional water-based paints described above have no advantage over solvent-based paints when applied to alkaline base materials, such as cement base materials, when the water content of the base material is above a certain level. However, in the case of emulsion-type paints, the emulsion particles have a large particle size and structural viscosity, so they have poor permeability into porous base materials such as cement base materials, and they also have the so-called amine-neutralized paints. Anionic type water-based paints have the disadvantage of being easily attacked by alkalis in the base material. In addition, there is a problem with cement base materials called efflorescence, which is a phenomenon in which calcium hydroxide in cement reacts with carbon dioxide gas in the air and becomes calcium carbonate, which is deposited on the surface. Conventional two-component urethane, emulsion, and other paints have not sufficiently solved the problem at present. [Means for Solving the Problems] As a means for solving the above-mentioned conventional problems, the present invention provides a vinyl monomer (A) having a tertiary amino group and a hydrolyzable silyl group-containing vinyl monomer. (B) and the above monomer (A) and another vinyl monomer (C) copolymerizable with (B), which is an aqueous solution of a copolymer of the monomer (A). The tertiary amino group provides the aqueous coating composition with acid cationization. The present invention will be described in more detail as follows. [Monomer (A)] Since the aqueous coating composition of the present invention is intended to be cationized, examples of the vinyl monomer having a tertiary amino group used for this purpose include NN 'dimethylaminoethyl (meth)acrylate, NN'diethylaminoethyl (meth)
Acrylate, vinylpyridine, etc. are used. [Monomer (B)] As the monomer (B), for example, CH ₂ =CHSi(OC ₂ H ₅ ) ₃ CH ₂ =CHSi(OCH ₃ ) ₃ CH ₂ =C(CH ₃ )COOC ₃ H ₆ Si (OCH ₃ ) ₃ CH ₂ = C (CH ₃ ) COOC ₃ H ₆ Si (OC ₂ H ₄ OCH ₃ ) ₃ CH ₂ = CHCOOC ₃ H ₆ Si (OC ₂ H ₄ OCH ₃ ) ₃ CH ₂ = C ( _{Silane coupling agents such as} CH3 _{) COOC3H6Si ( OCH3 ) 2CH3} or _{e.g. NH2C3H6Si} ( _OC2H5 ) _{3NH2CONHC3H6Si ( OC2H5} ) ₃ NH ₂ C ₂ H ₄ NHC ₃ H ₆ Si(OCH ₃ ) ₃ and the like, and a silane coupling agent having an amino group such as in A reaction product with a vinyl monomer having a glycidyl group such as a reaction product with a vinyl monomer having a glycidyl group and a silane compound having a mercapto group such as HSC ₃ H ₆ Si (OC ₂ H ₅ ) ₃ , Silane coupling agent with glycidyl group and a reaction product with α/β unsaturated carboxylic acid. In the present invention, the above-mentioned monomer (B) is copolymerized as a component in the polymer, or a silane coupling agent having a glycidyl group is later added to the copolymer containing carboxylic acid. Alternatively, a silane coupling agent having an amino group or a silane compound having a mercapto group may be subjected to an addition reaction in a copolymer containing a glycidyl group. The proportion of the monomer (B) in the copolymer is preferably 1 to 50% by weight, preferably 3 to 30% by weight. If the amount is less than this, the various performances that are the main purpose of the present invention will not be satisfied, and if it is more than this, it is disadvantageous in terms of coverage and cost. [Monomer (C)] Monomers (C) copolymerizable with the above monomers (A) and monomers (B) include methyl (meth)acrylate, ethyl (meth)acrylate, butyl ( (meth)acrylate, 2-ethylhexyl (meth)acrylate, or stearyl (meth)acrylate or other C1 _{-C18 alkanol} (meth)
Esters of acrylic acid, styrene, aromatic vinyl monomers such as vinyltoluene, β-hydroxyethyl (meth)acrylate, β-hydroxypropyl (meth)acrylate, or Cardiura E (Ciel product) and α/β unsaturated carboxylic acids. or polyethylene glycol (meth)acrylate, polypropylene glycol (meth)
Acrylate, hydroxyl group-containing vinyl monomer such as N-methylolacrylamide, glycidyl (meth)
Acrylate, glycidyl group-containing vinyl monomers such as allyl glycidyl ether, amide group-containing vinyl monomers such as (meth)acrylamide, N-butoxymethylacrylamide, diacetone acrylamide, acrylic acid, methacrylic acid, maleic anhydride, itacon Examples include mono- and diesters of α- and β-unsaturated fatty acids such as acids, fumaric acid, maleic acid, and itaconic acid. [Polymerization] The copolymer of the present invention is synthesized by a normal solution polymerization method, and is diluted with water after the reaction.
As a solvent for polymerization, _C1 to _C3 alcohols such as methanol, ethanol, isopropyl alcohol, and n-propyl alcohol, acetone,
Ketones such as methyl ethyl ketone, glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and ethylene glycol monobutyl ether are preferably used. Polymerization initiators include common peroxides such as benzoyl peroxide, t-butyl peroxybenzoate, t-butyl peroxy 2-ethylhexanoate, azobisisobutyronitrile,
2,2′azobis2,4dimethylvaleronitrile,
Although an azo polymerization initiator such as 2.2azobis4methoxy-2.4dimethylvaleronitrile can be used, in the present invention, since a vinyl monomer (A) having a tertiary amino group is copolymerized, the monomer It is preferable to use an azo polymerization initiator that is not decomposed by the alkali of the polymer (A). Further, as the molecular weight of the copolymer increases, performance such as water resistance and chemical resistance improves, but permeability into the substrate deteriorates, and vice versa. Therefore, the molecular weight is preferably about 3,000 to 20,000, preferably about 5,000 to 10,000 as a number average molecular weight. [Cationation] In the present invention, the tertiary amino group contained in the above copolymer is cationized with an acid. The acid used for the cationization is preferably an inorganic acid such as hydrochloric acid, or an organic acid such as formic acid, acetic acid, or butyric acid. [Function/Effect] When the object to be coated is an alkaline base material such as a cement base material, the aqueous coating composition of the present invention improves permeability and adhesion to the base material due to ionic approach due to cationic properties. The properties become better. however,
This alone is insufficient in terms of performance, and in order to obtain various performances such as good adhesion to the base material and water resistance, it is necessary to modify the surface layer of the base material through chemical bonding with the base material. This can be achieved by integrating with the material. That is, in the aqueous coating composition of the present invention, the hydrolyzable silyl group -Si(OR)x contained therein is hydrolyzed after coating to become -Si(OH) x , reacting with the -OH component of the base material, and the chemical bond is formed. It satisfies various performances such as excellent adhesion and permeability. In particular, in the present invention, the tertiary amino groups are neutralized with acid in order to make the copolymer cationic.
Because (OR) x is partially hydrolyzed to -Si(OH) It exhibits the characteristic of a one-component curing type in that the above-mentioned curing reaction further progresses due to the internal catalytic action of the amino groups during coalescence. The composition according to the present invention can be used in conventional spray coating, dipping coating, electrostatic coating, and brush coating, and since it is water-based, there is no environmental pollution caused by solvents, isocyanates, etc., and there is no adverse effect on the human body. It will be suitable for work. Incidentally, this composition may be used alone as a top coat or a base coat, or may be used as a primer for a base material. [Example] Next, examples of the present invention will be given and specifically explained. Note that the blending parts are parts by weight. Example 1 Formula Methyl methacrylate 120 parts Butyl acrylate 75 parts β-hydroxyethyl methacrylate 30 parts NN dimethylaminoethyl methacrylate 30 parts γ-methacryloxypropyltrimethoxysilane
45 parts 2,2'azobis2,4dimethylvaleronitrile
6 parts octyl thioglycolate 6 parts 150 parts of isopropyl alcohol is placed in a flask equipped with a stirrer and a cooler, the temperature is raised to 80°C under a nitrogen stream, and the above mixture is added dropwise over 3 hours. . After the dropwise addition, 1 part of 2,2'azobis2,4dimethylvaleronitrile dissolved in 50 parts of isopropyl alcohol was added dropwise for 3 times, 30 minutes, 60 minutes, and 180 minutes, and the mixture was reacted at 80°C for 2 hours. The resulting copolymer solution has a viscosity of x, a nonvolatile content of 60%, and a color number of 2. To 100 parts of this copolymer solution, 6 parts of glacial acetic acid was added to effect cationization and diluted with water to obtain an aqueous coating composition with a slightly bluish tinge and a non-volatile content of 30%. Examples 2 to 3 The manufacturing method was exactly the same as in Example 1, and the amounts were as shown in the synthesis composition table to obtain an aqueous coating composition of the present invention. Comparative Examples (Conventional Method), 1 to 4 Comparative Examples 1 and 2 were synthesized in exactly the same manner as Examples 1 to 3, except that the monomer composition was different as shown in the synthesis composition table. Comparative Example 3 was emulsion polymerization, and deionized water was used as the solvent during polymerization. In Comparative Example 4, an acrylic polyol for urethane was used, and the solvent used was a mixed solvent of toluene and butyl acetate.

【table】

[Table] Comparative physical property test methods Test methods for the coating compositions of the above Examples and Comparative Examples will be explained. First, the coating compositions shown in Examples 1 to 3 and Comparative Examples (conventional method) 1 to 4 were adjusted to a solid content of 30%, and in Comparative Example 4, Duuranate was added to the obtained coating composition.
24A-90CX (Asahi Kasei HMDI non-yellowing isocyanate) was blended at a ratio of NCO:OH of 1:1, and the solid content was adjusted to 30% with urethane thinner. These samples were coated on a flexible asbestos slate board and dried at 20℃ for one week, and after the same drying conditions, they were immersed in an alkaline aqueous solution of pH 10 for 10 days at room temperature. Table 1 shows the results of testing with a bond tester.

[Table] Unable to measure due to condensation failure.
Test method: Mix Portland cement and seconds at a ratio of 1:3, add water, and use a hydraulic molding machine to form 7 x 15 test pieces at 50kg/
Press with a pressure of cm ² . After preparing the test pieces, the adhesion of the coating film was examined according to changes in moisture content.

[Table] In the above test, the drying time of the coating film was 7.
The secondary adhesion test was performed by immersing the sample in boiling water for 1 hour and peeling it off with a cross-cut tape. ◎ No abnormality at all 〇 Almost no abnormality □ Slight abnormality △ Considerable abnormality × No adhesion at all A surface absorption test was conducted according to the test method JIS A5424.
The coating compositions of Examples 1 to 3 and Comparative Examples 1 to 4 were applied to a Caical board whose weight had been measured in advance, and the increase in weight was determined after 24 hours and converted into g/m ² .

[Table] Discussion As is clear from the test tables 1, 2, and 3 for Examples 1, 2, and 3 of the present invention, the aqueous coating composition of the present invention has a strong bonding force with the base material. Effects such as adhesion and prevention of water permeation are very excellent, and on the contrary, in the comparative examples of the conventional method, Comparative Example 2 does not contain a hydrolyzable silyl group, Comparative Example 1 does not contain a hydrolyzable silyl group, and Comparative Example 1 is an anionic type even if it does contain it. Alternatively, Comparative Example 3, which is a commonly used emulsion, and Comparative Example 4, which is a solvent-based urethane paint, do not provide satisfactory performance compared to the products of the present invention.

Claims (1)

[Claims] 1 Vinyl monomer (A) having a tertiary amino group
and a hydrolyzable silyl group-containing vinyl monomer (B)
and another vinyl monomer (C) which is copolymerizable with the above monomers (A) and (B), wherein the tertiary monomer of the monomer (A) is An aqueous coating composition characterized in that an amino group is cationized with an acid.