JPH0665711B2 - Water-based protection ▲ Rust ▼ Paint - Google Patents

Description

TECHNICAL FIELD The present invention relates to a water-based anticorrosion coating having excellent anticorrosion performance and coating film performance without problems such as aggregation.

(B) Conventional technology In general, organic solvent-based paints are excellent in coating film performance, but they tend to be replaced with water-based paints due to their hazards to the human body and the risk of fire. On the other hand, water-based paints have no work environment or safety problems, but the coating film performance is inferior to that of organic solvent-based paints, and there is an inherent problem of corroding metal materials until it dries after application. There is. Therefore, in order to overcome such problems, there is known a method of adding a pigment such as molybdate, borate or phosphate to impart rust prevention property. May not be sufficient or may be inferior in rust preventive property as compared with the organic solvent type, and it cannot be said to be sufficient.

There is also a method of adding a water-soluble chromate, but it is not preferable due to the harmfulness of the additive itself. As described above, the fact is that there is no means for providing the water-based paint with anticorrosive properties and also improving the coating film performance.

(C) Problems to be solved by the invention The object of the present invention is to have excellent corrosion resistance and chemical stability, so that there is no problem such as cohesion, and the water resistance, adhesiveness, and mechanical properties of the produced film. An object of the present invention is to provide a water-based rust preventive coating having excellent coating performance such as dynamic strength.

D Means for Solving the Problems The object of the present invention is to provide (meth) acrylamide and its N-substituted derivative, hydroxyalkyl ester of (meth) acrylic acid having 3 or less carbon atoms, and a monomer represented by the following general formula A: 1.0-4.0% by weight of nonionic hydrophilic monomer selected from the group consisting of and 0-3.0% by weight of vinyl monomer containing carboxyl group
And a monomer mixture consisting of 79 to 30% by weight of an aromatic vinyl monomer and 14 to 69% by weight of a (meth) acrylic acid ester was added to a 0.1% aqueous solution of the active ingredient at a surface tension of 40 dyne / c at 25 ° C.
A glass of a copolymer having a chemical stability of 20% or more and being polymerized in an aqueous medium in the presence of 0.1 to 5.0% by weight with respect to the above-mentioned monomer mixture of dialkylsulfosuccinate having a m or more. It is achieved by a water-based anticorrosive paint prepared by blending a polymer aqueous emulsion having a transition temperature of -20 to 60 ° C with nitrite.

(Wherein, R ₁ represents H or CH _3, R ₂ is H, alkyl group of 4 or less, or C ₆ H ₄ carbon _{- (CH 2) m-H} , m is 0 to 20 integer,
n shows the integer of 0-100. Hereinafter, the present invention will be described in detail.

First, the essential copolymerization component of the present invention includes a nonionic hydrophilic monomer, a carboxyl group-containing vinyl monomer, an aromatic vinyl monomer-based monomer and a (meth ) Four kinds of monomers having acrylic acid ester as a main component, which will be described in order. First, as the nonionic hydrophilic monomer which is the first essential copolymerization component, acrylamide, N-methylol acrylamide, N-butoxymethyl acrylamide, N-hydroxymethyl diacetone acrylamide, N-formyl-N'-acryloyl methylene is used. (Meth) acrylamides such as diamine, methacrylamide, N-methylolmethacrylamide, N-butoxymethylmethacrylamide, N-formyl-N'-methacryloylmethylenediamine and N-substituted derivatives thereof; hydroxyethyl methacrylate, hydroxypropyl methacrylate, Hydroxyalkyl (meth) acrylates such as hydroxyethyl acrylate and hydroxypropyl acrylate; for example, represented by the following general formula (A): polyethylene glycol (9 mol) mono (meth) acrylate , Polyethylene glycol (23 mol) mono (meth) acrylate, methoxy polyethylene glycol (30 mol) mono acrylate and other polyethylene glycol mono (meth) acrylate, methoxy polyethylene glycol mono (meth) acrylate, alkyl-substituted phenoxy polyethylene glycol mono ( Examples thereof include monomers such as (meth) acrylate, and among them, (meth) acrylamide and N-substituted derivatives thereof, and monomers represented by the following general formula (A) are preferable for achieving the object of the present invention.

(Wherein, R ₁ represents H or CH _3, R ₂ is H, alkyl group of 4 or less, or C ₆ H ₄ carbon _{- (CH 2) m-H} , m is 0 to 20 integer,
n shows the integer of 0-100. ) It is necessary to set the copolymerization ratio of the monomer in the range of 1.0 to 4.0% by weight, preferably 1.5 to 3.0% by weight, based on the total amount of the monomer, and the ratio falls below the lower limit of the range. In this case, when the nitrite is added to the polymer aqueous emulsion, aggregation of the emulsion is caused, and if it exceeds the upper limit, the rust preventive performance of the finally obtained water-based rust preventive coating composition is deteriorated.

Examples of the carboxyl group-containing vinyl monomer that is the second essential copolymerization component include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, fumaric acid and itaconic acid. The copolymerization ratio of the monomer should be set within the range of 0 to 3.0% by weight, preferably 0 to 2.5% by weight, based on the total amount of the monomers. When the amount exceeds the upper limit of the recommended range of the present invention, the rust preventive performance of the finally obtained water-based rust preventive coating is deteriorated, which is not preferable.

When the water-based anticorrosive paint of the present invention is used in combination with a cement material, the copolymerization ratio of the above monomers is 0.3 to 3.0% by weight, preferably 0.5 to 2.5% by weight, based on the total amount of the monomers. It is necessary to set within the range, when the copolymerization ratio of the above monomer is below the lower limit of the recommended range, when the water-based anticorrosive paint of the present invention is blended with a cement material, it preferably exhibits strong thixotropy. If there is not, and exceeds the upper limit,
The finally obtained cement product is unfavorable because the anticorrosive performance is lowered.

The balance of the monomer is composed of the aromatic vinyl monomer and the (meth) acrylic acid ester, which are the third and fourth essential copolymerization components, and the aromatic vinyl monomer is styrene. , Α-methylstyrene, chlorostyrene, etc. can be exemplified, and styrene is particularly preferable, but the amount is required to be 79 to 30% by weight, preferably 75 to 35% by weight, based on the total amount of the monomers. This is preferable because it is possible to provide a water-based rust preventive coating having further excellent rust preventive performance and coating film performance.

The (meth) acrylic acid ester which is the fourth essential copolymerization component includes methyl, ethyl, propyl, butyl, 2-ethylhexyl of acrylic acid and methacrylic acid,
Examples thereof include esters such as octyl, methoxyethyl, phenyl, cyclohexyl, 2-phenylethyl, tetradecyl and dodecyl. Among them, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, dodecyl acrylate, 2-phenylethyl acrylate, methoxyethyl acrylate, octyl methacrylate, tetradecyl methacrylate, dodecyl methacrylate, It is preferable to select a (meth) acrylic acid ester having a glass transition temperature (Tg) of a homopolymer such as 2-ethylhexyl methacrylate that is 0 ° C. or lower. The amount is 14 ~ with respect to the total amount of monomers.
69% by weight is necessary, and preferably 18 to 64% by weight is preferable because the rust prevention performance, coating film performance and the like can be further improved.

As will be described later, the aromatic vinyl monomer and the (meth) which are the third and fourth essential copolymerization components are added within a range in which the chemical stability and the glass transition temperature of the copolymer can be maintained at a predetermined level. The acrylate ester can be used in combination with a monomer other than the first and second essential copolymerization components while adopting each as an essential component.

Further, in order to achieve the object of the present invention, the type and amount of the above-mentioned four vinyl monomers are set so that the Tg of the obtained copolymer is −
It is necessary to set the temperature in the range of 20 to 60 ° C, preferably -10 to 50 ° C. When the Tg is below the lower limit of the present invention, the rust preventive performance and coating film performance of the finally obtained water-based rust preventive coating are deteriorated, and when the Tg is above the upper limit, the film-forming property of emulsion is unsatisfactory. It is not desirable because it becomes sufficient and the adhesiveness to the steel material, the covering property, etc. are deteriorated.

The glass transition temperature (Tg) is defined by the following formula.

(However, Tg is the glass transition temperature (° K) of the polymer prepared from n types of monomers, Tgi is the glass transition temperature (° K) of the homopolymer of monomer i, and Wi is the monomer. The weight fraction of the monomer i with respect to the total amount is shown.) Incidentally, the aromatic vinyl monomer and the (meth) acrylic acid ester, which are the third and fourth essential copolymerization components adopted in the balance described above, are used. Is a halogenated vinyl halide such as vinyl chloride, vinyl bromide, vinyl fluoride, vinylidene chloride, etc., other than the first and second essential copolymerization components, while using each of them as a main component. Vinylidene; unsaturated ketones such as methyl vinyl ketone and methyl isopropenyl ketone; vinyl esters such as vinyl acetate and vinyl propionate; conjugated diene monomers such as butadiene and isoprene; and (meth) acrylic acid acid phosphoki Phosphoric acid group-containing monomers such as ethyl, acrylphosphoxypropyl (meth) acrylate, bis (meth) acryloxyethyl phosphate, vinyl phosphate; and other known monomers such as acrylonitrile Needless to say.

Next, the essential emulsifier used to achieve the object of the present invention has a surface tension of 0.1% aqueous solution of the active ingredient at 25 ° C. (using a Deniyu surface tension tester) of 40 dyne / cm or more, preferably 45 dyne / cm or more. Is used in an amount of 0.1 to 5.0% by weight with respect to the monomer mixture, for example, an alkyl group such as butyl, amyl, hexyl, cyclohexyl and the like dialkylsulfosuccinic acid alkali metal (Li, Na , K, etc.) and ammonium salts, among which the alkali metal or ammonium salt of dicyclohexyl sulfosuccinate gives good results. If the surface tension is below the range of the present invention, the rust preventive performance of the finally obtained coating will be insufficient.

As a method for producing emulsion, a usual emulsion polymerization method can be adopted other than using the above-mentioned monomer and emulsifier. As the polymerization catalyst, a so-called redox catalyst composed of a combination of a persulfate salt and a reducing sulfoxy compound, or a persulfate single catalyst can be preferably used.
The polymerization method may be batch type or continuous type, and the addition method of the monomer, the catalyst and the like in the batch type polymerization method may be batch charging, divided addition or continuous addition. Further, the amount of water to be present in the polymerization system, 30 to 90% by weight, preferably 40 to 90% by weight based on the total amount of the monomer and water.
80% by weight is desirable, and the amount of the emulsifier to be used needs to be 0.1 to 5.0% by weight, preferably 0.5 to 4% by weight, based on the monomer. If the amount of the emulsifier used is less than the lower limit of the recommended range of the present invention, a good emulsion cannot be produced, and if it exceeds the upper limit, the chemical stability of the emulsion obtained is decreased, which is not desirable. .

The emulsion according to the present invention thus obtained is
% Or more, preferably 30% or more, it is necessary to have chemical stability, and when such chemical stability is lower than the lower limit of the present invention, formation of aggregates during nitrite blending is prevented. It is unavoidable and undesirable.

Examples of the nitrite to be added to the above-described polymer aqueous emulsion include salts of alkaline earth metals such as calcium nitrite and barium nitrite. The blending amount of such nitrite is 0,0 with respect to the polymer in emulsion.
It is desirable to set it in the range of 05 to 5% by weight, preferably 0.2 to 3% by weight. Above all, it is preferable to use calcium nitrite as the nitrite, because the rust preventive performance can be remarkably improved.

Incidentally, the water-based anticorrosive paint according to the present invention, for example, ethylene glycol, propylene glycol, ethers such as hexyl glycol, esters, ether ester derivatives and the like, specifically methyl cellosolve, ethyl cellosolve,
Butyl cellosolve, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, butoxyethoxy propanol, propoxy propanol, butoxy propanol, carbitol acetate,
Butyl carbitol acetate, butyl cellosolve acetate, hexylene glycol diacetate, etc. and Texanol (trade name of Eastman Kodak Co., Ltd.) and other film-forming aids, 0.1 to 50% by weight based on the total solid content of the paint,
If the amount is preferably 0.2 to 30% by weight, the anticorrosive performance of the coating material, the coating film performance and the like can be further improved.

The water-based anticorrosive paint according to the present invention thus obtained,
Since it has extremely excellent chemical stability, rust prevention performance, coating film performance, etc., it is a plate-shaped, needle-shaped or rod-shaped molded body of metal material mainly composed of iron, and various shapes of structures. It can be preferably used in the field of coating of objects.

(E) Action The reason why the water-based anticorrosive paint according to the present invention exhibits various excellent performances has not been fully clarified yet, but it is considered as follows.

That is, considering a conventional water-based anticorrosion coating, when an electrolyte such as an alkali metal salt of nitrous acid is mixed with an anionic emulsion, the charge is instantly neutralized by the alkali metal cation generated by the dissociation of the salt, As a result, it is possible to improve chemical stability by using a nonionic emulsifier that is stabilized in the adsorption hydration layer and is not easily affected by alkali metal ions in order to cause destabilization and aggregation of emulsion particles. Can be expected. However, nonionic emulsifiers generally do not have sufficient compatibility with the resin, and the emulsifiers aggregate during film formation to form a path for facilitating the entry of water into the coating surface and inside, so that the water resistance decreases, It is considered that nitrite will easily flow out from the coating film and may not give satisfactory results even in rust prevention performance. On the other hand, the nonionic monomer of the present invention has an adsorption hydration layer. Since it has a large number of hydrogen-bonding atoms (nitrogen, oxygen, etc.) that are easy to make per unit weight of the monomer, it is thought that the chemical stability will be significantly improved, among which (meth) acrylamide. When a derivative, especially N-methylol (meth) acrylamide is used, the molecular structure,
It is possible to blend nitrite to emulsion by effectively localizing it on the surface of emulsion particles with a small amount of use due to its polymerizability, etc., and thereby significantly improving water resistance as well as chemical stability. Moreover, it is considered that the obtained water-based rust preventive paint will have excellent rust preventive performance. Further, usually, the stability of emulsion increases as the amount of emulsifier used increases, but in the present invention, when the amount of the emulsifier exceeds a specific amount, the emulsifier is preferentially adsorbed on the surface of emulsion particles to form nonionic hydrophilic monomers. It is thought that it becomes difficult to appear on the particle surface and the chemical stability is lowered.

Further, the dialkyl sulfosuccinate, which is a specific emulsifier used in the present invention, has good compatibility with the main component monomer of the present invention, and the emulsifier does not aggregate to form a water entry route, and is generated. Since the coating film has water repellent property and water is difficult to enter into the coating film, it is presumed that excellent rust preventive performance is exhibited since the outflow of nitrite from the coating film is almost eliminated. . Further, the emulsifier of the present invention does not leach out to the film surface by leaching on the film surface at the time of forming a coating film, and in combination with the polymer composition having Tg within a specific range, film-forming property or It is considered that various properties such as hardness and strength of the final product and rust prevention performance can be remarkably improved. When a cement material is added to the water-based anticorrosive paint obtained by adding nitrite to the emulsion of the present invention obtained by copolymerizing a specific amount of a carboxyl group-containing vinyl monomer, it is produced in the water layer. A low molecular weight water-soluble polymer containing a carboxyl group-containing vinyl monomer improves the dispersibility of the cement material, and the nonionic hydrophilic functional group present on the polymer particle surface is present in the cement material.
It is considered that the formation of a salt-forming bond between a polyvalent metal ion such as a ⁺⁺ and Al ⁺⁺⁺ and a carboxyl group existing on the polymer particle surface can be suppressed, and the mixture can be mixed and integrated well with the cement material.

F Effect of the Invention As described above, the effects of the specific polymer composition having a specific Tg, the nonionic hydrophilic monomer, and the specific emulsifier are combined, and the excellent chemical stability and rust preventive performance as well as the production It is a remarkable effect of the present invention that it is possible to provide a water-based anticorrosive coating having significantly improved coating properties such as film property, adhesiveness, mechanical strength, and water resistance.

Examples Hereinafter, the present invention will be described in more detail with reference to Examples, but the scope of the present invention is not limited by the description of these Examples. In the examples, parts and percentages are by weight unless otherwise specified. Further, the evaluation of the chemical stability and the rust preventive property was carried out using the following methods, respectively.

(1) Chemical stability (%) 5 parts of emulsion having a solid content of 20% was added with 5 parts of an aqueous solution of calcium chloride of various concentrations, and the presence or absence of aggregates was visually observed, and added when the aggregates were generated. The minimum concentration of calcium chloride solution is shown. The larger this value is, the more excellent the chemical stability is, and particularly 50% or more is remarkably excellent.

(2) Corrosion resistance (a) Salt water immersion method A test piece coated with a test paint on a polished steel bar is immersed in a 3% aqueous sodium chloride solution, and the rusting state after a predetermined period has been visually observed.

(B) Salt spray method It complied with JIS Z23-1. After sealing the peripheral portion of the plate-shaped sample with cellophane tape, a crosscut was put and sprayed with a 5% sodium chloride aqueous solution.

Example 1 A cylindrical polymerization tank having an inner diameter of 13 cm and a height of 18 cm equipped with a stirrer was charged with 18 parts of an emulsifier shown in Table 1 below and 755 parts of ion-exchanged water, and nitrogen was blown for 15 minutes at 80 ° C. under stirring. Next, after adding an aqueous solution of 4.5 parts of ammonium persulfate (APS) dissolved in 50 parts of ion-exchanged water, an aqueous solution of 22.5 parts of N-methylolacrylamide (NMAM) dissolved in 72.5 parts of ion-exchanged water and the following Polymerization is started by continuously dropping 873 parts of a monomer mixture solution having a composition excluding NMAM shown in Table 1 from separate feed ports. The dropping rate was adjusted so that the dropping of these monomers would be completed in 3 hours, and after the dropping was completed, the polymerization was continued for 1 hour and then taken out from the polymerization tank. After passing through 200 mesh gold steel, pH was adjusted with 28% NH ₃ aqueous solution. Was adjusted to 8.0 to prepare four types of emulsions (1 to 4). An emulsion (5) was prepared in the same manner as the emulsion (1) except that the monomer composition used was changed as shown in Table 1.

Table 1 also shows the results of evaluation of the chemical stability of the obtained 5 types of emulsions (No. 1 to 5).

Next, 100 parts of each of the above three types of emulsions (No. 1 to 3) was mixed with 1 part of 30% calcium nitrite aqueous solution and 10 parts of butyl carbitol acetate, and the test paint obtained was brushed to a steel bar (diameter 20 mm). X 125 mm) was coated with a brush at 110 g / m ² and dried at 100 ° C. for 30 minutes. Table 1 also shows the results of evaluating the rust-preventing property (a) of the obtained test piece by the salt water immersion method after 2 weeks.

From Table 1, when emulsions and emulsifiers satisfying the present invention are used (Nos. 1 and 2), the chemical stability of the emulsion and the rust preventive property of the coating are excellent, but the invention is out of scope. When an emulsifier is used (No. 3), the rust preventive property is remarkably inferior, and when the emulsifier or the monomer composition deviates from the present invention (Nos. 4 and 5), the chemical stability is extremely poor. To be understood.

Example 2 Four types of emulsions (No. 6) were prepared in the same manner as in Example 1 (No. 1) except that the monomer composition was changed as shown in Table 2.
.About.9) were produced.

The results of evaluation of chemical stability and rust prevention are also shown in Table 2.

The anticorrosion property (b) was adjusted by mixing 100 parts of emulsion with 1 part of 30% calcium nitrite and 10 parts of texanol to prepare a test paint, and adding 75 g to a mild steel plate (70 x 70 x 1.6 mm).
The test piece was coated at a rate of / m ² and dried at 100 ° C. for 30 minutes, and the rust preventive property after 48 hours was evaluated by the salt spray method.

As is clear from the above table, the products of the present invention (Nos. 6 to 8) have good chemical stability and rust-prevention properties, while the carboxyl group-containing vinyl monomer exceeds the range of the present invention. When used, it is understood that the anticorrosion property is extremely poor.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location C09D 133/14 PGB 7921-4J 133/24 PFW 7921-4J 151/00 PGZ 7308-4J

Claims (8)

[Claims] 1. A nonionic selected from the group consisting of (meth) acrylamide and N-substituted derivatives thereof, hydroxyalkyl ester of (meth) acrylic acid having 3 or less carbon atoms, and a monomer represented by the following general formula A: Hydrophilic monomer 1.0-4.0
0% to 3.0% by weight and vinyl monomer containing carboxyl group
Also, a monomer mixture consisting of 79 to 30% by weight of an aromatic vinyl monomer and 14 to 69% by weight of (meth) acrylic acid ester was added to a 0.1% aqueous solution of the active ingredient at a surface tension of 40 dyn at 25 ° C.
A copolymer obtained by polymerizing in an aqueous medium in the presence of 0.1 to 5.0% by weight with respect to the above monomer mixture of dialkylsulfosuccinate having an e / cm 2 or more, and having a chemical stability of 20% or more and a copolymer. A water-based anticorrosive paint prepared by blending a polymer aqueous emulsion having a glass transition temperature of -20 to 60 ° C with nitrite. (Wherein, R ₁ represents H or CH _3, R ₂ is H, alkyl group of 4 or less, or C ₆ H ₄ carbon _{- (CH 2) m-H} , m is 0 to 20 integer,
n shows the integer of 0-100. ) 2. The water-based rust preventive coating composition according to claim 1, wherein the dialkyl sulfosuccinate is an alkali metal salt or ammonium salt of dicyclohexyl sulfosuccinic acid. 3. The water-based rust preventive coating composition according to claim 1, wherein the aromatic vinyl monomer is styrene. 4. The nonionic hydrophilic monomer is (meth) acrylamide or an N-substituted derivative thereof, according to claim 1.
The water-based anticorrosive paint according to the item. 5. The water-based rust preventive coating composition according to claim 4, wherein the N-substituted derivative of (meth) acrylamide is N-methylol (meth) acrylamide. 6. The nonionic hydrophilic monomer is the above general formula (A).
The water-based anticorrosive paint according to claim 1, which is a monomer represented by 7. The water-based rust preventive coating composition according to claim 1, which comprises 0.05 to 5% by weight of nitrite with respect to the polymer in the emulsion. 8. The water-based rust preventive coating composition according to claim 1, wherein the nitrite is calcium nitrite.