KR910006719B1 - Anticorrosive paint composition - Google Patents

Abstract

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Description

Antiseptic Coating Composition

The present invention relates to an antiseptic coating composition applied on a metal surface such as iron, iron alloy, etc. to prevent rust formation.

In general, methods for preventing rust on iron and its alloys are known, such as application of antiseptic paint, plating, and electrical antiseptic treatment. Also, large metal products and metal structures such as vehicles and ships are known. In order to prevent rust on legs, legs, tanks, etc., a method of applying an antiseptic paint thereon has been widely adopted due to ease of operation and economic reasons.

However, conventionally known antiseptic paints are insufficient in many respects, and the antiseptic effect exhibited thereby depends on the surface condition of the object to be painted. For example, the formation of rust in the object to be painted is completely prevented due to the unevenness or roughness of the object to be painted or the action of substances remaining on the surface of the object to be painted, or due to the inadequate properties of the above-mentioned paint itself. It cannot be prevented.

Currently, paints containing, for example, tannin or tannic acid as antiseptic coatings for iron or alloys thereof are GB-2075538A, Japanese Patent Laid-Open Nos. 57-139155 (1982) and 58-149966 (1983). Although known according to the present invention, these paints do not have sufficient antiseptic performance.

As a result of serious research by the inventors of the antiseptic paints, the inventors have found that it is necessary for the antiseptic paints to have the following special characteristics in order to produce an antiseptic paint having excellent antiseptic performance. For example, it should have an action of cleaning the surface of the object to be painted, such as dissolving rust on the surface of the object. (2) The anticorrosive paint is not chemically aggregated on the surface of the object to be painted, so that the coating film of the paint is smooth and It should be strongly adhered to the surface, (3) the film of paint thus formed should have excellent barrier properties against moisture and oxygen from the outside, and (4) the anticorrosive paint will bind to the above-mentioned metal on the surface of the metal object to be painted. To form a so-called floating state. However, until now, no antiseptic paint having all the above-mentioned characteristics is known.

As antiseptic coatings, antiseptic coating compositions comprising latex and tannin materials of vinylidene chloride copolymer have been proposed in Japanese Patent Laid-Open Nos. 63-105072 (1988) and 63-105073 (1988).

However, in the antiseptic paint described above, the latex of the vinylidene chloride copolymer acting as a colorant is prepared by an emulsion polymerization reaction in the presence of an anionic emulsifier and thus has an anion characteristic, thereby having a substantially unstable defect with respect to metal ions. Therefore, if the type and condition of the object to be painted or the conditions for painting are not suitable, a dense film of vinylidene chloride copolymer which sufficiently intercepts moisture or oxygen from the outside is not formed, and as a result, a stable antiseptic effect is obtained by such antiseptic paint. Cannot be displayed. That is, these preservatives still have drawbacks.

That is, when an antiseptic paint containing a latex of a vinylidene chloride copolymer stabilized by an anionic emulsifier as a colorant is applied on an iron plate on which red rust is formed or on a galvanized steel plate, metal ions dissolving on the surface of the object to be coated. This causes agglomeration of the latex and the formation of a film essential for the antiseptic effect is impossible.

The above-mentioned fact is a fatal drawback for repair coatings or antiseptic coatings for vehicles in which various metal materials are combined.

In order to improve the above, it is necessary to improve the stability of vinylidene chloride copolymer latex to metal ions, that is, the chemical stability of vinylidene chloride copolymer latex.

In order to obtain a vinylidene chloride copolymer latex having high chemical stability, it is generally effective to use a nonionic emulsifier, and in fact, the chemicals of the vinylidene chloride copolymer latex are added by adding a nonionic emulsifier to the vinylidene chloride copolymer latex. Stability can be improved. However, in order to obtain sufficiently high chemical stability, it is necessary to use a large amount of nonionic emulsifier and in the above-mentioned case, the film of the vinylidene chloride copolymer latex thus formed is blocked by oxygen and water due to the plasticizing action of the nonionic emulsifier. The property is very weak.

In addition, the binding of the chelating agent in the antiseptic coating composition is very effective. However, vinylidene chloride copolymer latex containing a nonionic emulsifier generally has a problem in that it is not able to control the preservative paint due to aggregation and gelation when a chelating agent such as tannic acid is added.

From the above aspect, for example, in the technique of Japanese Patent Laid-Open No. 57-18766 (1982), it has been proposed to use a latex obtained without using any nonionic emulsifier and in which the acid radical is firmly bound to the polymer molecule. The problem with the metal ion which is a problem at present is not improving at all.

It is an object of the present invention to provide an antiseptic coating composition comprising vinylidene chloride copolymer latex and chelating agent obtained by emulsion polymerization in the presence of a nonionic emulsifier, the copolymer latex having a sufficiently good chemical stability. It does not aggregate by the binding of the chelating agent and is stable against latex-coagulation by metal ions.

An object of the present invention, vinylidene chloride copolymer latex is 50 to 95% by weight of vinylidene chloride and 5 to 50% by weight of a monomer capable of copolymerizing with vinylidene chloride in the presence of 0.5 to 2.0 parts by weight of a nonionic emulsifier and a polymerization initiator. Obtained by emulsion polymerization of 100 parts by weight of the monomer mixture comprising a preliminary emulsion polymerization of less than 20% by weight of 100 parts by weight of the monomer mixture is present in the nonionic emulsifier and 0.5 to 2.0 parts by weight of the polymerization initiator is not more than 25% by weight And at least 80% by weight of the monomer mixture are added to the polymerization system continuously and uniformly, while at least 75% by weight of the nonionic emulsifier and the polymerization initiator are added to the polymerization system continuously and uniformly. Fluid polymerization, and the latex of the vinylidene chloride copolymer Containing at least 50% by weight of the added nonionic emulsifier and at least 0.25% by weight of the solid material of the vinylidene chloride copolymer latex, which is not extracted from the vinylidene chloride copolymer obtained by extraction. To provide an antiseptic coating composition comprising 100 parts by weight of vinylidene chloride copolymer latex calculated from a solid material and 0.1 to 10 parts by weight of a chelating agent.

In the present invention, a specific latex of vinylidene chloride copolymer obtained by emulsion polymerization in the presence of a specific emulsifier is used as a developer. That is, the specific latex of the vinylidene chloride copolymer is an emulsion polymerization reaction in the presence of 0.5 to 2.0 parts by weight of a vinylidene chloride monomer mixture and a monomer capable of copolymerizing vinylidene chloride in a specific ratio with respect to 100 parts of the monomer mixture. Obtained in the form of a non-ionic emulsifier, which is not extracted by methanol extraction, in an amount of at least 50% by weight of the amount of the nonionic emulsifier used and at least 0.25% by weight of the solid material of the copolymer latex. Remains in.

The amount of nonionic emulsifier in latex not extracted by the methanol extraction method mentioned here is the value obtained as follows.

That is, the film obtained by applying the copolymer latex on the base film so that the thickness of the solid material is 5 micrometers, forming a film at 20 DEG C and drying the film thus obtained is obtained using methanol as a solvent while using a Soxhlet extractor. Extract until the amount of nonionic emulsifier extracted with methanol is constant weight.

The amount subtracted from the amount of nonionic emulsifier using the amount of extracted nonionic emulsifier is the amount of nonionic emulsifier remaining in the latex.

The vinylidene chloride copolymer latex described above can be prepared by the following method (see EP 0242234A): (1) 50 to 95% by weight of vinylidene chloride and at least one monomer 5 to 50 copolymerizable with vinylidene chloride Prepare 100 parts by weight of the monomer mixture consisting of% by weight, (2) 0.5 to 2.0 parts by weight of the nonionic emulsifier, and (3) the required amount of polymerization initiator.

The proportion of vinylidene chloride in the monomer mixture described above is 50 to 95% by weight, preferably 60 to 93% by weight and most preferably 70 to 90% by weight. If this ratio is less than 50% by weight, the latex obtained is pH3 or more, so that the acidity becomes weak. Therefore, the cleaning effect of the paint on the surface of the object to be painted is reduced, and the adhesion of the paint film to the surface of the object to be painted is weak.

When the ratio of vinylidene chloride mentioned above is 70 weight% or more, the blocking characteristic of the coating film with respect to water and oxygen will become enough, and such a case is especially preferable. On the other hand, when the above-mentioned ratio exceeds 95% by weight, the obtained vinylidene chloride copolymer is easily crystallized, and the latex particles are cured within a short time after the copolymer is produced, causing latex to form an insufficient copolymer film.

As monomers copolymerizable with vinylidene chloride, vinyl chloride, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, methyl methyl acrylate, acrylonitrile, vinyl acetate, and acrylate acrylate 1 or more vinyl-based or vinylidene-based monomers selected from the group consisting of cydyl, glycidyl methacrylate, acrylic acid, methacrylic acid, metaconic acid, 2-hydroxyethyl methacrylate, and the like do. The proportion of the copolymerizable monomers described above is from 5 to 50% by weight, preferably from 7 to 40% by weight and most preferably from 10 to 30% by weight of the monomer mixture. When glycidyl acrylate or glycidyl methacrylate having crosslinking properties is used as part of the above-mentioned monomers, it is possible to obtain a paint film having excellent toughness, so that the glycerin methacrylate is contained in an amount of 0.5 to 5% by weight of the total amount of monomers. Particular preference is given to using cydyl.

Nonionic emulsifiers are used as emulsifiers for use in emulsion polymerization.

The nonionic emulsifier is used in the range of 0.5 to 2.0 parts by weight, preferably 1.0 to 2.0 parts by weight based on 100 parts by weight of the monomer mixture, but the amount of the nonionic emulsifier is as small as possible within the range having stability of the copolymer latex. desirable.

On the other hand, when a constant ratio exceeds 2.0 weight part, there exists a tendency for the barrier property with respect to oxygen and water of the copolymer thus obtained to deteriorate.

As the nonionic emulsifier, for example, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, fatty acid ester of polyoxyethylene, fatty acid ester of polyoxyethylene sorbitan and the like can be used, and the HLB value within the range of 7-20 It is desirable to have. Particularly preferred are polyoxyethylene alkyl ethers and polyoxyethylene alkyl phenyl ethers.

Next, as the polymerization initiator, water-soluble inorganic peracids and organic peracids, which are dissolved in a small amount in water, may be used depending on the environment, and these may be used as redox initiator components formed by combining an initiator with a reducing agent. Potassium persulfate, sodium persulfate, ammonium persulfate, hydrogen peroxide, etc. can be used as an inorganic peracid. As the organic peracid, tert-butyl hydroperoxide, succinic peroxide, tert-butyl peroxymaleic acid, cumene hydroperoxide, or the like can be used. Also, for example, water-soluble azo compounds such as 2,2'-azobis (2-amidinopropane) hydrochloride can be used.

As the reducing agent combined with the above-mentioned peracid, sodium bisulfite, longalite salt, oxalic acid, maleic acid, paraoxybenzoic acid, thiourea or ascorbic acid and the like are used.

The amount of the polymerization initiator used in the polymerization reaction depends on the molecular weight of the copolymer of the object, but is generally preferably 0.02 to 0.2 parts by weight based on 100 parts by weight of the monomer mixture.

It is also necessary for the polymerization initiator to be added continuously without interruption over time when the monomer mixture is added continuously to the polymerization system.

The method of emulsion polymerization in the present invention will be described in more detail below.

The emulsion polymerization is first a preliminary emulsion polymerization in which a portion of the monomer mixture, a portion of the nonionic emulsifier and a portion of the polymerization initiator are introduced into the autoclave and the monomer mixture introduced is polymerized to some extent in the former stage of the polymerization. Next, the subsequent monomer polymerization is carried out by adding the remaining monomer mixture, the remaining nonionic emulsifier, and the remaining polymerization initiator to the autoclave at a constant uniform rate.

In the above-mentioned case, it is preferable that an emulsifier and a polymerization initiator are added in aqueous solution state.

In the case of employing the above-described method, the so-called seed polymerization reaction is carried out at the previous stage of the polymerization reaction, and the above-described method is preferable in that the diameter of the latex particles is easy to adjust because the number of the latex particles is constant.

The amount of the monomer mixture used in the previous stage of the polymerization reaction is less than 20% by weight and preferably 5 to 15% by weight of the total monomer mixture, and the amount of the emulsifier in the previous stage of the polymerization reaction is 25% by weight of 0.5 to 2.0 parts by weight of the total emulsifier. It is below and preferably 10 to 25 weight%, and as for the required amount of a polymerization initiator, 20 to 45 weight% is used preferably.

That is, 75 weight percent of the emulsifier and the polymerization initiator during the period of continuously adding up to 80% by weight of the monomer mixture to the reaction system of the emulsion polymerization reaction at a uniform rate and continuously adding the above-described monomer mixture in the subsequent stage of the polymerization reaction. It is necessary to add more than% continuously to the reaction system simultaneously.

In each of the above-described methods, the composition or type of the monomer mixture and the nonionic emulsifier continuously added to the polymerization system may be the same or different. In addition, the composition and type of the monomer mixture used in the previous step of the polymerization reaction and the composition and type of the nonionic emulsifier may be the same or different from the composition and type of the material added continuously in the later step.

According to the above-mentioned emulsion polymerization method, the ratio of the nonionic emulsifier remaining in the state where the nonionic emulsifier is not extracted by the methanol extraction method and the ratio of the remaining nonionic emulsifier is 50% by weight or more of the used nonionic emulsifier and the solid of the copolymer latex. Latexes of vinylidene chloride copolymers of at least 0.25%, preferably at least 0.5%, by weight of the material can be prepared.

In the present invention, the vinylidene chloride copolymer latex is most suitably in the range of 800 to 2000 mm 3, and the particles having such diameter are suitably adjusted to the amount of the monomer mixture, emulsifier and polymerization initiator used in the previous stage of the polymerization reaction. It can be obtained easily by doing.

As for the temperature of an emulsion polymerization reaction, 30-60 degreeC is preferable.

In the emulsion polymerization of the monomer mixture described above, the polymerization yield is almost 100% and thus the composition of the copolymer thus obtained becomes almost identical to that of the monomer mixture.

0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight of the chelating agent, directly, ie, pH adjustment, with 100 parts by weight of the obtained vinylidene chloride copolymer latex exhibiting a pH of 1.5 to 3.0 (in terms of solids). The antiseptic coating composition according to the present invention is obtained by bonding without performing. To the antiseptic coating composition thus obtained, other additives may also be added, if necessary.

The chelating agent used in the present invention is a substance that dissolves in water having a pH of 1 to 4, and can form a chelate which is insoluble in water together with metals. Specific examples thereof include gallic acid, pyrogallol, tannin, tannic acid, and the like. I can lift it. Of these materials, pyrogallol and tannic acid are particularly preferred.

The tannic acid here is hydrolyzable tannin and is represented by gallotanine gallotanic acid or water tannin. These chelating agents may be used alone or in combination.

The chelating agent may be combined with the aforementioned vinylidene chloride copolymer latex as such or in an aqueous solution.

If the ratio of the chelating agent thus bonded is less than 0.1 part by weight, the formation of the chelate may not be carried out sufficiently, so that a desirable antiseptic effect cannot be obtained. On the other hand, when the above-mentioned ratio is 10 parts by weight or more, the waterproofness of the coating film thus formed is lowered and economically disadvantageous.

In order to improve the properties of the composition as a coating, it is preferable to combine the antiseptic coating composition and the alcohol according to the present invention.

The bonding ratio of the alcohol is 1.0 to 100 parts by weight, preferably 5 to 50 parts by weight, relative to 100 parts by weight of the vinylidene chloride copolymer latex (calculated as a solid material).

As alcohol, methanol, ethanol, isopropyl alcohol, butanol, ethylene glycol, propylene glycol, etc. can be used suitably. By combining the alcohol with the coating composition, very good practical effects are obtained as follows. That is, the level property of the paint is improved, the defoaming effect is obtained, and the degassing effect of hydrogen gas formed by the reaction with the metal at the same time as the application of the antiseptic coating composition is achieved.

In addition, additives that may be added to the antiseptic coating composition according to the present invention include, for example, film forming aids, plasticizers, viscosity improvers, pigments, including carbitol for improving film forming properties at low temperatures of 0 to 10 ° C. Silica, clays, dispersants containing various surfactants, wetting agents, and the like.

The antiseptic coating composition according to the invention is used as a coating or primer to be applied on metals, in particular iron or alloys thereof. When applying this antiseptic coating composition onto the surface of the object to be painted, the chelating agent combines with the metal of the object, in particular iron, to form a chemically stable chelate, i.e., a floating state material and the colorant is vinylidene chloride copolymer. Because it contains a specific latex, the coating film formed has very excellent barrier properties and at the same time its excellent cleaning action can appear on the surface of the object to be coated because the latex of the vinylidene chloride copolymer described above is acidic due to hydrochloric acid. That is to say an advantage is obtained of excellent adhesion of the coating composition to the surface of the object to be painted.

The used vinylidene chloride copolymer latex of the present invention is obtained by a special fluid polymerization treatment at a specific ratio of 0.5 to 2.0 parts by weight with respect to 100 parts by weight of the monomer mixture of vinylidene chloride in the presence of a nonionic emulsifier. Residual nonionic emulsifier in an amount of at least 50% by weight of the prepared nonionic emulsifier and at least 0.25% by weight relative to the solid material of the copolymer latex. Thus, the latex of the vinylidene chloride copolymer described above has very excellent chemical stability compared to the conventional latex obtained by using a nonionic emulsifier and also makes the chelating agent stable with the vinylidene chloride copolymer latex according to the present invention. Can be combined.

The foregoing is surprising when considering that latexes of vinylidene chloride copolymers to which nonionic emulsifiers have been added are often agglomerated by binding of chelating agents such as tannic acid and the like.

That is, according to the present invention, the chelating agent can be combined with the latex of vinylidene chloride copolymer given chemical stability by a nonionic emulsifier without causing aggregation. The binding of such chelating agents was thought to be impossible until now.

The cause of the above-mentioned phenomenon will be explained by future studies, but the nonionic emulsifier used in the copolymer which forms the latex particles without being extracted by methanol and the proportion of emulsifier remaining is used. It is contemplated that binding of up to 10 parts by weight of chelating agent with respect to 100 parts by weight of copolymer latex does not interfere with the stability of the copolymer latex when at least 50% by weight of the emulsifier and at least 0.25% by weight relative to the solid material of the copolymer latex. Can be.

In other words, the presence of a nonionic emulsifier having a unique shape makes the copolymer latex itself chemically stable, and at the same time the chelating agent is stably bound even when a large amount of nonionic emulsifier is required for the emulsion polymerization. In addition, the required amount of the nonionic emulsifier is less than 2.0 parts by weight with respect to 100 parts by weight of the monomer mixture, from this point can be formed a film excellent in barrier properties to oxygen and water.

In addition, since the vinylidene chloride copolymer latex used in the present invention is obtained without using any anionic emulsifier, the copolymer latex is also stable against metal ions and thus, airborne when applying the copolymer latex to the surface of the object to be painted. Cohesive latex is not aggregated by iron ions formed by dissolution.

In the case of using the antiseptic coating composition according to the present invention, it is possible to obtain a beautiful coating film having the above-mentioned adhesive property is large and dense and has high barrier properties as described above, and as a result of these properties, a very excellent antiseptic effect can be obtained.

In addition, by mixing an appropriate amount of alcohol with the above-described coating composition, the handling and use of the antiseptic coating composition as a coating becomes easy. That is, this antiseptic coating composition becomes very convenient in practical use.

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In the examples, "parts" means parts by weight.

Example 1

(1) Preparation of vinylidene chloride copolymer latex A

Previous stage

0.1 part of deionized water polyoxyethylene lauryl ether (manufactured by Kao Atlas Co., Ltd. under the trade name {EMULGEN 147}) was introduced into a glass built-in high temperature mixer equipped with a stirrer, and the temperature of the introduced material was polymerized at 45 ° C. After raising to the reaction temperature and sufficiently replacing the air of the autoclave with nitrogen gas, 9 parts of vinylidene chloride and 1 part of methyl acrylate were introduced into the autoclave under pressure, and an aqueous solution of 0.01 part of potassium persulfate and sodium bisulfite under pressure were introduced. 0.01 part of an aqueous solution was introduced into the autoclave. The contents of the autoclave were stirred for 5 hours to carry out an emulsion polymerization to prepare a latex.

Post step

6.0 parts of a 1% aqueous solution of sodium bisulfite were added to the latex in the autoclave obtained in the previous step, and then a mixture of 65 parts of vinylidene chloride, 21 parts of butyl acrylate, and 4 parts of glycidyl methacrylate was uniformly mixed into 5 parts per hour. The rate was added continuously to the autoclave. At the same time, 0.9 parts of polyoxyethylene lauryl ether (EMULGEN 147), 0.01 parts of potassium persulfate and 18.0 parts of deionized water were continuously added to the autoclave at a uniform rate at 1 part per hour to carry out the polymerization at 45 ° C.

About 1 hour after the addition of the monomer mixture was completed, the addition of the emulsifier and the polymerization initiator was completed. One hour after the addition of the emulsifier and the polymerization initiator, a mixture of 0.02 parts of potassium persulfate, 0.02 parts of sodium hydrogen sulfite and 4.0 parts of deionized water was added all at once, and then the contents of the autoclave were stirred at 45 ° C. for 3 hours to pH 2.3. Negative latex gave A.

At the same time, 1 to 2 drops of the latex A thus obtained were added dropwise to methanol, 10% cationic surfactant solution (CETHOQUAD C-12), and dropwise added to 5% FeCl ₃ solution and 5% FeCl ₃ solution. It was found that Latex A did not aggregate and was very good in chemical stability of Latex A.

Further, Latex A was applied onto a biaxially stretched polypropylene film such that the solid material had a thickness of 5 micrometers, and the treated film was dried at 20 ° C. to form a copolymer film and dried, and then the formed coating film was cellophane Peeled from the film by using an adhesive tape. After about 10 g of the coating film was cut into long strip-shaped pieces, the obtained pieces were extracted with methanol as a solvent using a Soxhlet extractor until the amount of the emulsifier extracted was a constant weight.

The amount of emulsifier extracted by the methanol extraction method was 0.2 parts corresponding to 20% by weight of the total amount of emulsifier used (1.0 parts).

The amount of nonionic emulsifier remaining in Latex A was 0.8 parts and the residual ratio of emulsifier was about 0.8% by weight relative to the solid material of Latex A.

(2) combination

An aqueous solution of 5 parts of tannic acid and 5 parts of isopropyl alcohol were added to 100 parts of Latex A (calculated as a solid material), and the mixture thus prepared was slowly stirred to prepare a preservative coating composition 1 according to the present invention.

(3) Evaluation of Antiseptic Coating Composition

The anticorrosive coating composition 1 was preliminarily degreased with perchloroethylene and left on the iron plate having a width of 7 cm, a length of 15 cm, and a thickness of 1 mm and left in a galvanized steel plate of the above-sized size for 1 week in the room so that a slight red rust occurred. It was applied with a brush and the treated plates were dried at 20 ° C. After the plate was dried, application of the antiseptic coating composition and drying thereof were repeated once more to form a coating film having a thickness of 40 micrometers.

When the coating composition was applied on an iron plate, the coating composition turned milky white immediately after application, but turned black at the same time as the coating film was formed. That is, a smooth and glossy black paint film was formed. The above fact is believed to be the result of the following phenomenon: That is, tannic acid is immediately bound to the new surface of the iron plate dissolved by the acidity of the coating composition described above to form a chelate. On the other hand, in the case of a galvanized steel sheet, a smooth and glossy transparent film was formed, and coating properties and film formation were good.

The coated steel sheet and the coated galvanized steel sheet were immersed in water at 40 ° C. for 48 hours, and subjected to the waterproof test described in Japanese Industrial Standard (JIS) K 5400 7.2. In the case of the flame retardant test described in Japanese Industrial Standard (JIS) K 5400 7.6 soaked for 96 hours, no abnormality was found in the plate dipped in each test, and the antiseptic effect of the antiseptic coating composition 1 according to the present invention was Satisfied. In addition, no rust was observed even if the plate was soaked in salt water for 800 hours.

Example 2

100 parts of latex A (calculated as a solid material) obtained in Example 1, an aqueous solution of 3 parts of pyrogallul, an aqueous solution of 5 parts of isopropyl alcohol and polyvinyl alcohol (manufactured by Nippon Kosei Co., Ltd., (AH-17)) 0.3 parts of an aqueous solution was added in the order described above. The mixture thus prepared was slowly stirred to prepare an antiseptic coating composition 2 according to the present invention.

Anticorrosive coating composition 2 was applied on the iron plate in the same manner as in Example 1 to obtain a glossy black coating film.

When the waterproof test and the salt water test were carried out in the same manner as in Example 1 on the iron plate thus obtained, no abnormality was observed at all.

Since the viscosity of the preservative coating composition 2 is appropriate, the amount of adhesion of the composition obtained by a single coating is large, and since the coating composition contains alcohol, it is easy to remove bubbles and the coating composition 2 is also easy to handle.

Example 3

(1) Preparation of vinylidene chloride latex B

Previous stage

80 parts of deionized water and 0.5 parts of polyoxyethylene nonylphenyl ether (manufactured by Gao Atlas Co., Ltd. under the trade name EMULGEN 935) were introduced into a glass built-in autoclave equipped with a stirrer and the temperature of the introduced material was 45 ° C. After raising to the polymerization temperature of the reaction mixture and sufficiently replacing the air in the autoclave with nitrogen gas, 8 parts of vinylidene chloride and 2 parts of ethyl acrylate were introduced to the autoclave under pressure, and then 0.01 parts of aqueous solution of potassium persulfate and sulfurous acid under pressure. An aqueous solution of 0.01 part of sodium hydrogen was introduced into the autoclave. The contents of the autoclave were stirred for 3 hours to carry out an emulsion polymerization to prepare a latex.

Post step

To the latex in the autoclave obtained in the previous step, 6.0 parts of a 1% aqueous solution of sodium bisulfite was added, and in the next step, a mixture of 72 parts of vinylidene chloride, 14 parts of ethyl acrylate and 4 parts of glycidyl methacrylate was uniformly mixed into 5 parts per hour. The rate was added continuously to the autoclave.

At the same time, 1.5 parts of polyoxyethylene nonylphenyl ether (EMULGEN 935), 0.004 parts of potassium persulfate and 18 parts of deionized water were continuously added to the autoclave at a uniform rate at 1 part per hour to carry out the polymerization reaction at 45 ° C. About 1 hour after the addition of the monomer mixture was completed, the addition of the emulsifier and the polymerization initiator was completed. After 1 hour of completion of the addition of the emulsifier and the polymerization initiator, a mixture of 0.02 parts of potassium persulfate, 0.02 parts of sodium hydrogen sulfite and 4.0 parts of deionized water was added all at once, and the contents of the autoclave were stirred at 45 ° C. for 3 hours to pH 2.5 Latex was obtained.

At the same time, if 1 to 2 drops of the latex B thus obtained were added dropwise in the same manner as in Example 1 to methanol, an aqueous solution of cationic surfactant and an aqueous solution of iron chloride, the treated latex B did not aggregate and the chemical stability of the latex B was very high. It turned out to be excellent.

The amount of emulsifier extracted from latex B by methanol extraction was 0.4 part, corresponding to 20% by weight of the total amount of emulsifier used (2.0 parts).

Therefore, the residual ratio of the nonionic emulsifier contained in the latex B was about 1.6% by weight based on the solid material of the latex B.

An aqueous solution of 2 parts of tannic acid was added to 100 parts of latex B (converted to a solid material), and the mixture thus prepared was slowly stirred to prepare an antiseptic coating composition 3 according to the present invention.

The anticorrosive coating composition 3 was applied with a brush on a cast iron plate having a width of 7 cm, a length of 15 cm, and a thickness of 1 cm, and the treated plate was dried at 20 ° C. After the plate was dried, coating of the antiseptic coating composition 3 and drying thereof were repeated once more to form a coating film having a thickness of about 40 micrometers. The coating composition turned milky white immediately after application but turned black simultaneously with the coating film formation. That is, a black glossy paint film was formed.

When the treated cast iron plate was subjected to the waterproof test and the flameproof test in a manner similar to that in Example 1, no abnormality was found on the cast iron plate tested.

Comparative Example 1

A control latex a containing no vinylidene chloride as a component was prepared in the same manner as in Example 1 except that the monomer in each step was changed to the monomer shown below.

Monomer at the previous stage

Styrene Part 2.0

3.0 parts of methyl metatylate and

Butyl acrylate 5.0 parts

Monomer in later stage

Styrene Part 18

22.5 parts of methyl methacrylate

Butyl acrylate 45 parts

3.5 parts glycidyl methacrylate and

Methacrylic acid 1.0 part

The pH value of the control latex a mentioned above was 4.

A control coating composition 1 was prepared by combining 5 parts of tannic acid and 5 parts of isopropyl alcohol together in the same manner as in Example 1 except for using the control latex a described above.

The coating composition was applied onto the iron plate in the same manner as in Example 1 except that the control coating composition 1 described above was used to obtain a glossy black coating film having the same shape as in Example 1.

However, when the treated iron sheet was treated in the same waterproof test and flameproof water test as in Example 1, red rust occurred and spread over the entire surface of the iron sheet.

Comparative Example 2

A control latex b containing both a nonionic emulsifier and an anionic emulsifier was prepared in the same manner as in Example 1 except that the emulsifier in the later step was changed to the emulsifier shown below.

Emulsifier in later stage

0.45 parts of sodium alkyl diphenyl ether disulfonate (manufactured by Nihon Neukazai Co., Ltd.).

When the control latex b thus prepared was added in methanol, cationic emulsifier aqueous solution and iron chloride aqueous solution, the added latex b immediately aggregated. In other words, the control latex b had poor chemical stability.

A control coating composition 2 was prepared by combining an aqueous solution of 3 parts of tannic acid with 100 parts of the control latex b (calculated as a solid material).

When the above-mentioned control coating composition 2 was applied on the iron plate, latex was agglomerated at the site where rust formed on the surface of the iron plate, resulting in an uneven black film having no gloss.

In addition, when the coated iron sheet was subjected to the same waterproof test and flame retardant test treatment as in Example 1, it was observed that red rust spread largely at the site where latex aggregation occurred due to red rust of the coating body.

The above-mentioned phenomenon can be said to be due to the aggregation of latex on the above-mentioned sites, which results in a decrease in the density of the membrane and deterioration of the gas barrier properties.

Comparative Example 3

To the control latex b obtained in Comparative Example 2 (calculated as a solid), 1.5 parts of a nonionic emulsifier and polyoxyethylene nonylphenyl ether (EMULGEN 935) were added to the control latex c containing a nonionic emulsifier. Prepared.

When 2 parts of tannic acid were combined with 100 parts of the control latex c (calculated as a solid material), the treated latex was agglomerated.

Comparative Example 4

Preparation of Control Latex D

Previous stage

80 parts of deionized water, 0.1 parts of sodium alkyl diphenyl ether disulfonate (manufactured by Nihon Nukazai Co., Ltd. under the trade name (NEWCOL 271A)) and polyoxyethylene nonylphenyl ether (Gao Atlas Company Limited) After introducing 0.2 parts of a (manufactured under the trade name EMULGEN 935) and raising the temperature of the introduced material to a polymerization temperature of 45 DEG C and sufficiently replacing the air in the autoclave with nitrogen gas, vinylidene chloride under pressure 8 parts and 2 parts of methyl acrylate are introduced into the autoclave.

Then, an aqueous solution of 0.01 parts of potassium persulfate and 0.01 parts of sodium hydrogen sulfite was introduced into an autoclave under pressure, and the contents of the autoclave were stirred for 3 hours to conduct an emulsion polymerization to prepare a latex.

Post step

6.0 parts of a 1% aqueous solution of sodium bisulfite was added to the latex in the autoclave obtained in the previous step, and then a mixture of 72 parts of vinylidene chloride, 14 parts of ethyl acrylate, and 4 parts of glycidyl methacrylate was uniformly mixed into 5 parts per hour. Add continuously at rate. At the same time a mixture of 0.3 parts of sodium alkyldiphenyl ether disulfonate (NEWCOL 271A), 0.8 parts of polyoxyethylene nonylphenyl ether (EMULGEN 935), 0.004 parts of potassium persulfate and 18 parts of deionized water was continuously fed at a uniform rate of 1 part per hour. In addition, a polymerization reaction was carried out at 45 ° C. About 1 hour after the completion of the monomer addition, the addition of the emulsifier and the polymerization initiator was completed.

One hour after completion of the addition of the emulsifier and polymerization initiator, a mixture of 0.02 parts of potassium persulfate, 0.02 parts of sodium hydrogen sulfite and 4.0 parts of deionized water was added all at once to the autoclave, and the contents of the autoclave were stirred at 45 ° C. for 3 hours. To obtain a control latex d at pH 2.5.

At the same time, when one or two drops of the latex d thus obtained were added dropwise to the aqueous methanol and cationic surfactant solution, the latex did not agglomerate, but when the latex d was added dropwise to the aqueous solution of iron chloride, the treated latex d immediately agglomerated. In other words, the latex d had insufficient stability against metal ions.

The amount of emulsifier extracted from the latex d by methanol extraction was 0.63 parts corresponding to 45% by weight of the total amount of emulsifier used (1.4 parts).

According to the methanol extraction method described above, all of the remaining emulsifiers were nonionic emulsifiers because the entire amount of sodium alkyldiphenyl ether disulfonate as an anionic emulsifier was substantially extracted by methanol. Thus, the amount of remaining nonionic emulsifier was 0.77 parts and the residual ratio of nonionic emulsifier was about 0.77% by weight relative to the latex d solid material.

5 parts of tannic acid and 5 parts of isopropyl alcohol were added to 100 parts of latex d (in terms of a solid material), and the mixture thus prepared was slowly stirred to prepare a control antiseptic coating composition 3.

When the anticorrosive coating composition 3 described above was applied to an iron plate and a galvanized steel plate, a glossy black coating film was obtained on the iron plate as in Example 1.

However, in the treated galvanized steel sheet, the agglomeration of the latex was observed during the application of the latex with a brush and the coating film was obtained in appearance but the film was insufficient in the gloss and density,

The above fact is due to insufficient stability of the latex to metal ions.

When the treated iron sheet and the galvanized steel sheet were subjected to the waterproof test and the flameproof test similarly to Example 1, no abnormality was found on the iron plate and the antiseptic effect was satisfactory.

However, on the treated galvanized steel sheet, the coating film protruded and white rust was observed on the tube. That is, the antiseptic effect of the control coating composition 3 on the galvanized steel sheet was insufficient.

Comparative Example 5

A control latex e of the present invention was prepared in the same manner as in Example 1 except that the nonionic emulsifier continuously added in the subsequent step was changed to that mentioned below.

Emulsifier and polymerization initiator in later stage

Polyoxyethylene lauryl ether 2.9 parts

(EMULGEN 147)

0.01 parts potassium persulfate

12.0 parts deionized water

Nogglomeration of latex e was not observed even when the control latex e prepared as described above was added dropwise to methanol, cationic surfactant aqueous solution and iron chloride aqueous solution. That is, the chemical stability of the control latex e was good.

In addition, the amount of the emulsifier extracted from the latex e by the methanol extraction method was 1.2 parts corresponding to 40% by weight of the total amount (3.0 parts) of the emulsifier used.

Therefore, the proportion containing the remaining nonionic emulsifier was about 1.8% by weight based on the solid material of the latex e.

When the aqueous solution of 2 parts of tannic acid was insufficient in the above-mentioned 100 parts of the control latex e (calculated as a solid material), the treated latex e was agglomerated, and thus the desired antiseptic coating composition could not be obtained.

Claims (5)

Vinylidene chloride copolymer latex is a monomer mixture 100 containing 50 to 95% by weight of vinylidene chloride and 5 to 50% by weight of monomer copolymerizable with vinylidene chloride in the presence of 0.5 to 2.0 parts by weight of a nonionic emulsifier and a polymerization initiator. Obtained by emulsion polymerization, wherein the preliminary emulsion polymerization is carried out in the presence of the nonionic emulsifier and 0.5 to 2.0 parts by weight of the polymerization initiator in less than 20% by weight of the monomer mixture, At least 80% by weight of the monomer mixture is continuously added to the polymerization reaction system continuously, and at least 75% by weight of the nonionic emulsifier and the polymerization initiator are added to the polymerization reaction system continuously and uniformly to perform the emulsion polymerization of the monomer mixture. In addition, the latex of the vinylidene chloride copolymer is phase Residual nonionic emulsifiers not extracted from the obtained vinylidene chloride copolymer are contained at least 50% by weight of the added nonionic emulsifier and at least 0.25% by weight of the solid material of the vinylidene chloride copolymer latex. Anticorrosive coating composition comprising 100 parts by weight of vinylidene chloride copolymer latex (calculated as a solid material) and 0.1 to 10 parts by weight of a chelating agent. The antiseptic coating composition according to claim 1, wherein said chelating agent is pyrogallol or tannic acid. The anticorrosive coating composition according to claim 1, comprising 100 parts by weight of the vinylidene chloride copolymer latex (calculated as a solid material) and 0.5 to 5 parts by weight of the chelating agent. The antiseptic coating composition according to claim 1, comprising 100 parts by weight of the vinylidene chloride copolymer latex (calculated as a solid material), 0.1 to 10 parts by weight of the chelating agent and 1.0 to 100 parts by weight of alcohol. The antiseptic coating composition according to claim 4, wherein the alcohol is isopropyl alcohol, ethylene glycol or propylene glycol.