JP4694164B2 - Rust-proof coating agent and laminated metal material - Google Patents

Description

  The present invention relates to a coating agent for rust prevention and a laminated metal material provided with a film obtained by applying the coating agent.

  Metal-plated steel sheets such as electrogalvanized steel sheets and hot-dip galvanized steel sheets are widely used in automobiles, home appliances, structures and the like, and in recent years, there has been an increasing demand for surface-treated steel sheets having excellent rust prevention properties. Under such circumstances, a chromate treatment using hexavalent chromium has been adopted in order to further enhance the rust prevention property of the galvanized steel sheet. Chromate treatment improves the rust prevention of galvanized materials, but the problem of chromium contamination in the work environment and installation location due to hexavalent chromium has been pointed out, and so-called non-chromate antirust treatment agents that do not use chromium have been developed. It is an urgent need.

  As one of the new non-chromate antirust treatment agents, treatment agents based on various polymer compounds have been studied. For example, Patent Document 1 and Patent Document 2 disclose an attempt to coat an olefin-based powder resin on the surface of a steel sheet, and Patent Document 3 discloses a copolymer resin powder with an ethylene-unsaturated carboxylic acid. Powder coating is disclosed.

  However, when painting using such a powder resin, it is very difficult to coat to a thickness of 20 μm or less, and it cannot be used for applications requiring thin coating. In addition, it is difficult to obtain a coating film having excellent smoothness and uniformity, and in order to improve the smoothness and uniformity of the coating film, the flowability and average particle size of the powder resin are often limited.

  In order to make the coating thin and uniform, a method of applying to a steel plate or the like using a coating agent in which a resin is dissolved or dispersed in an organic solvent or an aqueous medium is used. The medium of the coating agent is an unsaturated carboxylic acid because it is preferable to use an aqueous medium rather than an organic solvent from the standpoints of environmental protection, resource saving, regulation of dangerous goods by the Fire Service Act, and workplace environment improvement. An aqueous antirust coating agent dispersed in an aqueous medium by neutralizing a carboxyl group in a resin with a basic compound using an ethylene-unsaturated carboxylic acid copolymer having a high content is used. For example, Patent Document 4, Patent Document 5, Patent Document 6 and the like include an aqueous rust-proof coating agent mainly composed of an ethylene-unsaturated carboxylic acid copolymer having an unsaturated carboxylic acid content of about 20% by mass. Is illustrated.

  However, when a resin having a high unsaturated carboxylic acid content is applied, the alkali resistance of the coating is remarkably lowered and cannot be used for applications requiring alkali resistance. Further, such a resin has insufficient alcohol resistance against methanol, ethanol, etc., particularly alcohol resistance under a high load. As means for improving the alkali resistance, Patent Document 7 and Patent Documents 8 and 9 by the present applicant disclosed rust prevention using an ethylene-acrylic acid ester-maleic anhydride copolymer having a low unsaturated carboxylic acid content. Coating agents have been proposed. Although the alkali resistance is remarkably improved by using this resin, it cannot be said that the alcohol resistance, particularly the alcohol resistance under a high load is sufficient. It is also disclosed that a crosslinking agent is added to improve alcohol resistance, but in order to develop the alcohol resistance of the coating by advancing the crosslinking reaction, a long drying process is required at a high temperature, In view of productivity, economy, etc., it was not a preferable method.

Japanese Patent Laid-Open No. 60-143952 JP-A-7-207215 JP-A-11-131259 Japanese Patent Publication No. 5-54823 JP-A-6-246229 JP 2000-198949 A JP 2002-348523 A JP 2002-348523 A JP 2003-171513 A

  In order to solve the above-mentioned problems, the present inventors can perform thin coating and have excellent rust resistance, alkali resistance, water resistance, alcohol resistance (especially under high load) by simply drying at a low temperature. An object of the present invention is to provide an aqueous coating agent capable of forming a film having alcohol resistance), workability, and adhesion to a metal material, and a laminated metal material coated therewith.

  As a result of diligent research, the present inventors applied a water-based coating agent containing a specific proportion of two types of polyolefin resin and wax in a specific ratio and preferably containing a rust preventive improver to the surface of a metal material. In addition, by forming a layer composed of the resin composition, it has been found that not only alcohol resistance under high load is remarkably improved, but also rust prevention is improved, and the above-mentioned excellent resistance including alkali resistance is also achieved. The present inventors have found that performance is also exhibited and have reached the present invention.

That is, the gist of the present invention is as follows.
(1) The following polyolefin resin (A), the following polyolefin resin (B), wax (C), and an aqueous medium are contained, and the mass ratio of the components (A) to (C) is (A) / (B) = 100/0 50/50, the rust prevention coating agent and satisfies the (C) / {(a) + (B)} = 10 / 100~80 / 100.

  Polyolefin resin (A): a copolymer composed of an unsaturated carboxylic acid or its anhydride (A1), an ethylene-based hydrocarbon (A2), and an acrylic ester or methacrylic ester (A3), The mass ratio of the components (A1) to (A3) is (A1) / {(A1) + (A2) + (A3)} = 0.01 / 100 to 5/100, (A2) / (A3) = 55/45 Polyolefin resin satisfying ~ 99/1.

Polyolefin resin (B): a copolymer composed of an unsaturated carboxylic acid or its anhydride (B1) and an ethylene hydrocarbon (B2), wherein the mass ratio of the components (B1) to (B2) is ( Polyolefin resin satisfying B1) / (B2) = 12/88 to 30/70.
(2) The coating agent for rust prevention according to (1), wherein the mass ratio of the polyolefin resins (A) and (B) is (A) / (B) = 98/2 to 50/50.
(3) Further containing a rust preventive improver (D), the amount of which is 1 to 100 parts by mass with respect to 100 parts by mass of the total mass of solids (A) to (C). The coating agent for rust prevention according to (1) or (2).
(4) A laminated metal material provided with a coating obtained by applying the rust preventive coating agent according to any one of (1) to (3) to a metal material and drying it.

  According to the present invention, it is possible to obtain a film having high rust resistance, water resistance and alcohol resistance, particularly alcohol resistance under high load, workability, and good adhesion to metal. Moreover, alkali resistance can be improved as needed.

The present invention will be described in detail below.

  The polyolefin resin (A) used in the present invention is a co-polymer composed of three components: (A1) an unsaturated carboxylic acid or its anhydride, (A2) an ethylene-based hydrocarbon, and (A3) an acrylic ester or a methacrylic ester. It is a polymer.

  The unsaturated carboxylic acid or its anhydride (A1) component needs to be (A1) / {(A1) + (A2) + (A3)} = 0.01 / 100 to 5/100 by mass ratio, This ratio is preferably 0.1 / 100 to 5/100, more preferably 0.5 / 100 to 5/100, and most preferably 1/100 to 4/100. When the content of the component (A1) is less than 0.01% by mass, it becomes difficult to make the polyolefin resin (A) aqueous (liquefied), and it is difficult to obtain a good aqueous dispersion. On the other hand, when the content of the component (A1) exceeds 5% by mass, it becomes easy to make it water-based, but since the amount of carboxyl groups increases, this reacts with an alkali compound and the alkali resistance of the coating tends to decrease. .

  The unsaturated carboxylic acid or anhydride thereof that can be used as the component (A1) is a compound having at least one carboxyl group or acid anhydride group in the molecule (in the monomer unit). In addition to acids, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, fumaric acid, crotonic acid and the like, unsaturated dicarboxylic acid half esters, half amides and the like can be mentioned. Among these, acrylic acid, methacrylic acid, and (anhydrous) maleic acid are preferable, and acrylic acid and maleic anhydride are particularly preferable. Moreover, the unsaturated carboxylic acid should just be copolymerized in polyolefin resin, The form is not limited, For example, random copolymerization, block copolymerization, graft copolymerization etc. are mentioned.

  Ethylene hydrocarbon (A2) and acrylic acid ester or methacrylic acid ester (A3) component, mass ratio (A2) / (A3) of component (A2) and component (A3) is 55/45 to 99/1. In view of rust prevention, it is preferably 70/30 to 98/2, more preferably 80/20 to 97/3, and 85/15 to 97/3. Is more preferable, and it is especially preferable that it is 88 / 12-97 / 3. If the ratio of the component (A3) to {(A2) + (A3)} is less than 1% by mass, it becomes difficult to make the polyolefin resin water-based, making it difficult to obtain a good aqueous dispersion, and film processability. And adhesion may be reduced. On the other hand, when the content of the compound (A3) exceeds 45% by mass, properties as a polyolefin resin due to the component (A2) are lost, and performance such as rust prevention and alcohol resistance is deteriorated.

  Examples of the ethylene hydrocarbon (A2) component include alkenes having 2 to 6 carbon atoms such as ethylene, propylene, isobutylene, 1-butene, 1-pentene and 1-hexene, and a mixture thereof may be used. Among these, alkenes having 2 to 4 carbon atoms such as ethylene, propylene, isobutylene and 1-butene are more preferable, and ethylene is particularly preferable.

  As the acrylic ester or methacrylic ester (A3) component, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, acrylic acid Hexyl, octyl acrylate, stearyl acrylate, and the like can be mentioned. Among them, methyl acrylate, ethyl acrylate, and butyl acrylate are preferable, and methyl acrylate and ethyl acrylate are particularly preferable because the resin is easily polymerized.

  As specific examples of the polyolefin resin (A), an ethylene-methyl acrylate-maleic anhydride copolymer or an ethylene-ethyl acrylate-maleic anhydride copolymer is most preferable. Here, the acrylic ester unit may be converted into an acrylic acid unit by hydrolyzing a small part of the ester bond when the resin is made into an aqueous solution as described later. It suffices if the ratio of each constituent component taking into account the change is within a specified range.

  In addition, unsaturated carboxylic anhydride units such as maleic anhydride units form an acid anhydride structure in which adjacent carboxyl groups are dehydrated and cyclized in the dry state of the resin, but in particular an aqueous medium containing a basic compound Among them, a part or all of them are ring-opened, so that the structure of carboxylic acid or a salt thereof is easily formed.

  Further, in the polyolefin resin (A) used in the present invention, other monomers may be copolymerized at 20% by mass or less of the entire resin. Examples thereof include alkyl vinyl ethers having 3 to 30 carbon atoms such as methyl vinyl ether and ethyl vinyl ether, dienes, (meth) acrylonitrile, halogenated vinyls, halogenated vinylidenes, carbon monoxide, and sulfur dioxide.

  The polyolefin resin (A) preferably has a melt flow rate of 0.01 to 500 g / 10 min at 190 ° C. and a load of 2160 g, which is a measure of molecular weight, more preferably 0.1 to 400 g / 10 min, and 1 to 300 g. / 10 minutes is more preferable. When the melt flow rate of the polyolefin resin (A) is less than 0.01 g / 10 minutes, it becomes difficult to make the resin water-based, and it is difficult to obtain a good aqueous resin dispersion. On the other hand, when the melt flow rate of the polyolefin resin (A) exceeds 500 g / 10 min, when the resin aqueous dispersion is combined with the polyolefin resin (B), the resulting coating tends to be hard and brittle. Strength and workability tend to decrease.

  The polyolefin resin (B) comprises an unsaturated carboxylic acid or its anhydride (B1) and an ethylene hydrocarbon (B2) component, and the mass ratio of (B1) / (B2) is 12/88 to 30/70. 15/85 to 25/75 is preferable, and 18/82 to 23/77 is more preferable. When the component (B1) is less than 12% by mass, it tends to be difficult to make it water-based. On the other hand, when the component (B1) exceeds 30% by mass, the water resistance of the resulting coating is remarkably lowered and sufficient rust prevention properties cannot be obtained, or the alkali resistance of the coating is deteriorated.

  The unsaturated carboxylic acid or anhydride (B1) component is a compound having at least one carboxyl group or acid anhydride group in the molecule (in the monomer unit), specifically, acrylic acid, methacrylic acid, Examples include maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, fumaric acid, crotonic acid and the like, as well as unsaturated dicarboxylic acid half esters and half amides. Of these, acrylic acid, methacrylic acid, and (anhydrous) maleic acid are preferable, and (meth) acrylic acid is particularly preferable. Moreover, the unsaturated carboxylic acid should just be copolymerized in polyolefin resin, The form is not limited, For example, random copolymerization, block copolymerization, graft copolymerization etc. are mentioned.

  Examples of the ethylene hydrocarbon (B2) component include alkenes having 2 to 6 carbon atoms such as ethylene, propylene, isobutylene, 1-butene, 1-pentene, and 1-hexene, and a mixture thereof can also be used. Among these, alkenes having 2 to 4 carbon atoms such as ethylene, propylene, isobutylene and 1-butene are more preferable, and ethylene is particularly preferable.

  The polyolefin resin (B) is most preferably an ethylene-acrylic acid copolymer or an ethylene-methacrylic acid copolymer. In addition, the carboxyl group in the acrylic acid or methacrylic acid unit tends to take a salt structure in an aqueous medium containing a basic compound described later.

  In the polyolefin resin (B), other monomers may be copolymerized at 20% by mass or less of the entire resin. For example, alkyl vinyl ethers having 3 to 30 carbon atoms such as methyl vinyl ether and ethyl vinyl ether, esters of (meth) acrylic acid such as methyl (meth) acrylate, ethyl (meth) acrylate, and butyl (meth) acrylate, Examples include vinyl esters such as vinyl formate and vinyl acetate, dienes, (meth) acrylonitrile, halogenated vinyls, halogenated vinylidenes, carbon monoxide, and sulfur dioxide.

  The polyolefin resin (B) used in the present invention preferably has a melt flow rate of 20 to 5000 g / 10 min at 190 ° C. and a load of 2160 g, which is a measure of molecular weight, more preferably 30 to 1000 g / 10 min, and 30 to 500 g. / 10 minutes is more preferable. When the melt flow rate of the polyolefin resin (B) is less than 20 g / 10 minutes, it becomes difficult to make the resin water-based, and it is difficult to obtain a good aqueous resin dispersion. On the other hand, when the melt flow rate of the polyolefin resin (B) exceeds 5000 g / 10 minutes, when the resin aqueous dispersion is combined with the polyolefin resin (A), the resulting coating tends to be hard and brittle. The mechanical strength and workability are likely to deteriorate.

  The method for synthesizing the polyolefin resins (A) and (B) used in the present invention is not particularly limited, but is generally obtained by high-pressure radical copolymerization of a monomer constituting the polyolefin resin in the presence of a radical generator. Further, the unsaturated carboxylic acid or its anhydride may be graft copolymerized (grafted modification).

  The coating agent of the present invention contains a wax (C). The types of wax are roughly classified into natural wax and synthetic wax. Natural waxes include plant waxes such as candelilla wax, carnauba wax, rice wax, and wax, animal waxes such as shellac wax and lanolin wax, mineral waxes such as montan wax and ozokerite, petroleum oils such as paraffin wax and microcrystalline wax. A wax etc. can be illustrated. Synthetic waxes include Fischer-Tropsch wax, polyethylene wax, polypropylene wax, and derivatives thereof (modified products such as acid modification), caster wax, opal wax, armor wax, glyceryl stearate, cetyl alcohols, stearic acid, etc. It can be illustrated. Among these, candelilla wax, carnauba wax, and paraffin wax are preferable because they exhibit excellent rust resistance and alcohol resistance, and candelilla wax and paraffin wax are particularly preferable.

  The coating agent for rust prevention of the present invention has the above-mentioned amounts of (A) to (C) in a predetermined ratio in order to satisfy all the performances such as alcohol resistance, alkali resistance, rust prevention property and workability of the coating film. It is necessary to contain in.

  In order to improve the alcohol resistance of the coating, particularly the alcohol resistance under a high load, the ratio of (C) to the total amount of the polyolefin resins (A) and (B) (C) / {(A) + (B) } Is required to be 10/100 to 80/100 (mass ratio), and 10/100 to 70/100 is preferable and 15/100 to 70/100 is more preferable from the viewpoint of alcohol resistance and rust resistance. 20/100 to 60/100 is more preferable, and 25/100 to 60/100 is particularly preferable. When the value of (C) / {(A) + (B)} is smaller than 10/100, the effect of improving the alcohol resistance is small, and when it exceeds 80/100, the workability tends to decrease. is there.

  In the present invention, the mass ratio (A) / (B) between the polyolefin resin (A) and the polyolefin resin (B) is an arbitrary value of 100/0 to 0/100 for applications that do not require alkali resistance. It can be. If it is this range, the film which has the outstanding rust prevention property can be obtained. When alkali resistance is required, (A) / (B) (mass ratio) is preferably 100/0 to 50/50, and 98/2 to 50 in terms of further improving rust prevention. / 50 is more preferable, 97/3 to 60/40 is more preferable, and 95/5 to 70/30 is most preferable. When the proportion of the polyolefin resin (B) exceeds 50% by mass, the alkali resistance of the coating tends to be lowered.

  The coating agent of the present invention contains an aqueous medium. The aqueous medium is a medium composed of a liquid containing water as a main component, and may contain a water-soluble organic solvent or a basic compound described later.

  In this invention, in order to improve rust prevention further, it is preferable to contain a rust prevention improver (D), and the ratio is 100 mass parts in total of the solid content of (A)-(C). It is preferable that it is 1-100 mass parts with respect to it, 3-60 mass parts is more preferable, 5-50 mass parts is further more preferable, and 5-40 mass parts is especially preferable. When the amount of (D) is less than 1 part by mass, the effect of improving rust prevention is small, and when it is more than 100 parts by mass, the adhesion with the metal material is lowered or the workability is lowered.

  Examples of the rust preventive improver (D) include conventionally known compounds such as silicon compounds such as silica and ions, oxides or phosphates of polyvalent metals. Metal oxides and polyvalent metal phosphates are preferred from the viewpoint of improving rust prevention. The polyvalent metal refers to a metal having a valence of 2 or more, and examples thereof include magnesium, calcium, barium, zinc, iron, nickel, copper, and aluminum. As the rust preventive improver (D), it is more preferable to use these sols from the viewpoint of the stability of the coating liquid. Moreover, as silica, colloidal silica is preferable. Two or more kinds of antirust improvers (D) may be mixed and used. The addition amount in the case of polyvalent metal ions is preferably 10 to 90 mol%, more preferably 20 to 80 mol%, based on the total amount of carboxyl groups of the polyolefin resins (A) and (B). When the addition amount of the polyvalent metal ion is less than 10 mol%, the degree of the effect of improving rust prevention is small, and when the addition amount exceeds 90 mol%, the liquid stability may be deteriorated. As the polyvalent metal phosphate, zinc phosphate, aluminum phosphate, and magnesium phosphate are preferable. In addition, the phosphate here means the phosphate in a broad sense including orthophosphate, polyphosphate, metaphosphate, etc., and may take any of these phosphate structures.

  A crosslinking agent component can also be added to the rust-preventing coating agent of the present invention in order to further improve the performance of rust prevention and solvent resistance. When the crosslinking agent component is added, the amount is preferably 0.1 to 50 parts by mass with respect to a total of 100 parts by mass of the solid components (A) to (C) in the coating agent. -40 mass parts is more preferable, and 0.5-30 mass parts is especially preferable. Crosslinkers include self-crosslinkable crosslinkers, compounds having a plurality of functional groups that react with carboxyl groups and hydroxyl groups in the molecule, and metals that can form complexes by coordination of multiple carboxyl groups or carboxylate anions. For example, isocyanate compounds, melamine compounds, benzoguanamine compounds, urea compounds, epoxy compounds, oxazoline group-containing compounds, carbodiimide compounds, zirconium salt compounds, silane coupling agents and the like are preferable. Among these, a melamine compound, an epoxy compound, an oxazoline group-containing compound, a zirconium salt compound, and a silane coupling agent are particularly preferable in terms of enhancing the rust prevention property and solvent resistance of the coated metal material. These crosslinking agents can be used in combination.

  Furthermore, the anticorrosive coating agent of the present invention includes various agents such as a leveling agent, an antifoaming agent, an anti-waxing agent, a pigment dispersant, an ultraviolet absorber, titanium oxide, zinc white, carbon black, etc. Other pigments or dyes may be added.

  The resin content in the coating agent can be appropriately selected depending on the film forming conditions, the desired thickness and performance of the resin film, and is not particularly limited.However, in order to maintain an appropriate viscosity and develop a good film forming ability, 1-60 mass% is preferable, 3-50 mass% is more preferable, 5-40 mass% is further more preferable, 10-35 mass% is especially preferable.

  Next, the manufacturing method of the coating agent for rust prevention of this invention is demonstrated.

  Although the method for obtaining the coating agent for rust prevention of the present invention is not particularly limited, for example, polyolefin resins (A), (B), and wax (C) are each made aqueous to prepare an aqueous dispersion, and then Examples include a method (1) of mixing these at a predetermined ratio, a method (2) of kneading the polyolefin resins (A), (B), and wax (C) at a predetermined ratio to make them aqueous. It is done. In the case of adding the rust preventive improver (D), for example, a sol thereof can be prepared and mixed with any of the dispersions. The method (1) is preferable from the viewpoint of simplicity and the storage stability of the coating agent.

  When preparing an aqueous dispersion of a polyolefin resin, the number average particle diameter of the polyolefin resin particles in the aqueous dispersion is 0.5 μm or less from the viewpoint of the stability of the aqueous dispersion and the surface smoothness when applied. Preferably, it is 0.3 μm or less, more preferably 0.2 μm or less, and particularly preferably 0.15 μm or less. The weight average particle diameter is also preferably 0.5 μm or less. By adopting a preparation method to be described later, the above particle diameter can be obtained.

  The aqueous dispersion of polyolefin resin preferably does not contain an emulsifier from the viewpoint of rust prevention, alkali resistance, and water resistance. In particular, any of the aqueous dispersions of resins (A) and (B) contains an emulsifier and the like. Is preferably not contained. Examples of the emulsifier used in the present invention include a cationic emulsifier, an anionic emulsifier, a nonionic emulsifier, and an amphoteric emulsifier. Examples of the anionic emulsifier include a sulfate ester of a higher alcohol, a higher alkyl sulfonate, Acid salts, alkylbenzene sulfonates, polyoxyethylene alkyl sulfate salts, polyoxyethylene alkyl phenyl ether sulfate salts, vinyl sulfosuccinates, and the like. Nonionic emulsifiers include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl. Ether, polyethylene glycol fatty acid ester, ethylene oxide propylene oxide block copolymer, polyoxyethylene fatty acid amide, ethylene oxide-propylene oxide copolymer They include sorbitan derivatives such as compounds and polyoxyethylene sorbitan fatty acid esters having a polyoxyethylene structure, such as the body. Examples of amphoteric emulsifiers, lauryl betaine, lauryl dimethyl amine oxide, and the like. The aqueous dispersion of wax (C) also preferably does not contain an emulsifier from the viewpoint of rust prevention, alkali resistance, and water resistance. However, an emulsifier is not used for a wax having a low carboxyl group content or no carboxyl group content. Since it is very difficult to obtain an aqueous dispersion without adding it, in such a case, it is particularly preferable to use a volatile base compound salt of a higher carboxylic acid as an emulsifier. The volatile base compound acts as an emulsifier because it has a carboxyl group and a salt structure at the time of aqueous formation, but since it volatilizes at the time of film formation, rust prevention, alkali resistance, water resistance due to the residue The impact is small. Examples of the higher carboxylic acid include lauric acid and stearic acid, and the volatile base compound is preferably ammonia or a tertiary organic amine compound described later.

  The aqueous dispersion of polyolefin resin preferably contains a basic compound in an amount of about 0.5 to 3.0 times equivalent to the carboxyl group in the polyolefin resin. By the basic compound, the carboxyl group of the polyolefin resin is neutralized, and aggregation between the fine particles is prevented by the electric repulsion between the carboxyl anions generated by the neutralization, and stability is imparted to the aqueous dispersion. The basic compound may be any compound that can neutralize the carboxyl group, but a volatile basic compound is preferable from the viewpoint of performance such as rust prevention, alkali resistance, and water resistance. As such a basic compound, ammonia or an organic amine compound is preferable, and among them, an organic amine compound having a boiling point of 30 to 250 ° C., more preferably 50 to 200 ° C. is preferable. When the boiling point is less than 30 ° C., the rate of volatilization when the resin described later becomes aqueous may increase, and the aqueous formation may not proceed completely. When the boiling point exceeds 250 ° C., it becomes difficult to disperse the organic amine compound from the resin film by drying, and rust prevention and water resistance of the film may be deteriorated. Specific examples of the organic amine compound include triethylamine, N, N-dimethylethanolamine, aminoethanolamine, N-methyl-N, N-diethanolamine, isopropylamine, iminobispropylamine, ethylamine, diethylamine, and 3-ethoxypropylamine. , 3-diethylaminopropylamine, sec-butylamine, propylamine, methylaminopropylamine, methyliminobispropylamine, 3-methoxypropylamine, monoethanolamine, diethanolamine, triethanolamine, morpholine, N-methylmorpholine, N- Examples thereof include ethyl morpholine.

  When preparing the aqueous dispersion of the polyolefin resin (A), it is preferable to add an organic solvent in order to promote the aqueous formation and reduce the dispersed particle diameter (the polyolefin resin (B) It is not necessary to use an organic solvent because it can be easily made aqueous without an organic solvent). The amount of the organic solvent used here is preferably 40% by mass or less, more preferably 1 to 40% by mass, further preferably 2 to 30% by mass, and particularly preferably 3 to 30% by mass of the aqueous resin dispersion. After the preparation of the aqueous dispersion, a part of this organic solvent may be reduced by distilling it out of the system by an operation called stripping according to the purpose. By such an operation, the amount of the organic solvent can be made 10% by mass or less, and if it is 3% by mass or less, it is environmentally preferable. In order to distill off the organic solvent by stripping, it is necessary to take measures in the production process such as increasing the degree of vacuum of the apparatus or extending the operation time. Therefore, the lower limit of the amount of the organic solvent considering such productivity is 0. About 0.01 mass%. However, even if it is less than 0.01% by mass, there is no particular problem in the performance as an aqueous dispersion. The removal of the organic solvent can be performed by heating the aqueous resin dispersion with stirring under normal pressure or reduced pressure, and distilling off the organic solvent. The content of the organic solvent can be quantified by gas chromatography. Further, when the aqueous medium is distilled off, workability may be deteriorated due to an increase in viscosity or the like, so water may be added to the aqueous dispersion in advance.

  As the organic solvent, a water-soluble organic solvent is preferably used. For example, a solvent having a solubility in water at 20 ° C. of 30 g / L or more is preferably used, and more preferably 50 g / L or more. Specific examples of such an organic solvent include methanol, ethanol, n-propanol, isopropanol, n-butanol, methyl ethyl ketone, cyclohexanone, because it is easy to make the resin aqueous and to easily remove the organic solvent from the aqueous medium. Tetrahydrofuran, dioxane, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, and ethylene glycol monobutyl ether are preferable, and ethanol, n-propanol, and isopropanol are particularly preferable from the viewpoint of low temperature drying property.

  The aqueous dispersion of the polyolefin resin (A), polyolefin resin (B), or (A), (B) two types of resin mixture should be prepared by heating and stirring the above-mentioned components in a container. Can do. At this time, it is not necessary to use an emulsifier. Preferable containers include those that can be sealed, have a tank into which a liquid is charged, and can properly stir the charged aqueous medium, resin, and other raw materials. The stirring method and the rotation speed of stirring are not particularly limited. Such devices are widely known to those skilled in the art as solid / liquid stirring devices and emulsifiers.

  The raw materials are put into such an apparatus and are preferably stirred and mixed at a temperature of 40 ° C. or lower. Next, the polyolefin resin is made sufficiently aqueous by continuing stirring for 5 to 120 minutes while maintaining the temperature in the tank at 60 to 200 ° C, preferably 80 to 200 ° C, more preferably 90 to 200 ° C. Then, the resin aqueous dispersion is obtained by cooling to 40 ° C. or lower, preferably with stirring. When the temperature in the tank is lower than 60 ° C., the polyolefin resin becomes insufficiently water-based. When the temperature in a tank exceeds 200 degreeC, there exists a possibility that the molecular weight of polyolefin resin may fall.

  In the present invention, the metal material on which the coating agent for rust prevention is coated is not particularly limited, but it is preferable to use it for galvanized steel because it has a high rust prevention effect. Examples of the galvanized steel plating method include an electroplating method and a hot dipping method, but any method may be used. Further, the surface of the galvanized steel may be subjected to chemical conversion treatment such as chromate treatment. The galvanized steel is typically used in the form of a plate.

  The coating agent for rust prevention of the present invention is excellent in film forming ability and can be easily formed by a known method. For example, gravure roll coating, reverse roll coating, wire bar coating, lip coating, air knife coating, curtain flow coating, spray coating, dip coating, brush coating, etc., uniformly coats various substrate surfaces, and at room temperature as required After setting in the vicinity, a uniform film can be formed in close contact with the surface of various substrates by subjecting it to drying or heat treatment for drying and baking. As a heating device at this time, a normal hot air circulation type oven, an infrared heater, or the like may be used. In addition, the heating temperature and the heating time are appropriately selected depending on the characteristics of the base material to be coated, the type of curing agent described later, the blending amount, etc. The heating temperature is preferably 30 to 250 ° C, more preferably 60 to 230 ° C, particularly preferably 80 to 210 ° C, and the heating time is preferably 1 second to 20 minutes, more preferably 5 seconds to 15 minutes, 10 seconds to 10 minutes are particularly preferred. In addition, when a crosslinking agent is added, in order to sufficiently advance the reaction between the carboxyl group in the polyolefin and the crosslinking agent, it is desirable to appropriately select the heating temperature and time depending on the type of the crosslinking agent.

  Further, the coating agent for rust prevention according to the present invention can reduce the number average particle diameter of the resin particles according to the above-described production method, and thus can be applied thinly on the surface of the substrate, for example, as a resin coating It can be 0.1-10 micrometers. In consideration of rust prevention, workability and the like, 0.2 to 8 μm is preferable, and 0.3 to 5 μm is particularly preferable. When the thickness of the coating is less than 0.1 μm, the effect of rust prevention becomes small.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

Various characteristics were measured or evaluated by the following methods.
(1) Structure of polyolefin resin ¹ H-NMR analysis (manufactured by Varian, 300 MHz) was performed at 120 ° C. in orthodichlorobenzene (d ₄ ). The amount of the unsaturated carboxylic acid or its anhydride was also determined by using infrared absorption spectrum analysis (Perkin Elmer System-2000 Fourier transform infrared spectrophotometer, resolution 4 cm-1).
(2) Residual ratio of ester group after making aqueous polyolefin resin (A) The aqueous dispersion of polyolefin resin (A) was dried at 150 ° C, and then 1H- in orthodichlorobenzene (d ₄ ) at 120 ° C. NMR analysis (manufactured by Varian, 300 MHz) was performed, and the residual ratio (%) of the ester group was determined with the ester group amount of the acrylate ester before being made aqueous as 100%.
(3) Melt flow rate of polyolefin resin This is a value measured by the method described in JIS 6730 (190 ° C., 2160 g load).
(4) Melting | fusing point of polyolefin resin It is the value measured by DSC (DSC-7 by Perkin Elmer) at the temperature increase rate of 10 degree-C / min.
(5) Solid content concentration of aqueous polyolefin resin dispersion An appropriate amount of the aqueous polyolefin resin dispersion was weighed and heated at 150 ° C. until the mass of the residue (solid content) reached a constant weight to determine the solid content concentration.
(6) Average particle diameter of polyolefin resin particles A number average particle diameter and a weight average particle diameter were determined using a Microtrac particle size distribution analyzer UPA150 (MODEL No. 9340) manufactured by Nikkiso Co., Ltd.

In the following evaluations (7) to (13), the coated metal plate was allowed to stand at room temperature for 1 day and then subjected to various evaluation tests.
(7) Water resistance evaluation The film was rubbed 10 times with a cloth wetted with water, and the state of the film was visually evaluated.
○: No change, Δ: Film is cloudy, X: Film is completely dissolved (8) Alkali resistance evaluation An aqueous NaOH solution adjusted to pH 12.0 at 20 ° C. is heated to 35 ° C. and stirred, and this aqueous solution The coated metal plate was immersed for 3 minutes. Then, it washed with water and evaluated the state of the film visually.
○: No change, Δ: Film is cloudy, X: Film is dissolved or peeled (9) Alcohol resistance evaluation under load A load of 0.5 kg / cm ² is applied with a cloth wetted with methanol and ethanol The film was rubbed 10 times to visually evaluate the state of the coating.
○: No change, Δ: The film is cloudy, ×: The film is completely dissolved (10) Rust prevention evaluation Using a JIS Z-2371 standard salt spray tester, spray a 5 mass% NaCl aqueous solution at 35 ° C. The film state was evaluated by the rusting area ratio (%) after 72 hours.
(11) Evaluation of workability The metal plate was bent so that the uncoated surface was in contact, and the presence or absence of cracks in the bent portion was examined.
(Circle): No crack, x: There is a crack (12) Adhesion evaluation (I): Crosscut tape peeling Peeling was evaluated according to JIS K5400 8.5.2. The grid area of 1 mm × 1 mm × 100 pieces was peeled off with an adhesive tape and evaluated by the number remaining without peeling. “N / 100” indicates that n of the 100 grids remain without being peeled after the test.
(13) Adhesion evaluation (II): Eriksen processing Eighteen mm Eriksen processing was performed, the adhesive tape was adhered to the processed portion, the tape was peeled off vigorously, and the state of the coating film was evaluated visually.
○: No peeling, x: Peeling Table 1 shows the composition of the polyolefin resin used in the following examples.

(Production of aqueous polyolefin resin dispersion E-1)
Using a stirrer equipped with a hermetic pressure-resistant 1 L glass container with a heater, 125.0 g of polyolefin resin [Bondaine HX-8210 (A), manufactured by Atofina), 75.0 g of isopropanol (hereinafter, IPA), 7 0.7 g (1.0 times equivalent to the carboxyl group of maleic anhydride in the resin) of triethylamine (hereinafter TEA) and 292.3 g of distilled water were charged into a glass container, and the rotation speed of the stirring blade was 300 rpm. As a result of stirring, no precipitation of resin granules was observed at the bottom of the container, confirming that it was in a floating state. Therefore, while maintaining this state, the heater was turned on and heated after 10 minutes. Then, the system temperature was kept at 130 ° C. and further stirred for 30 minutes. Then, after cooling to room temperature (about 25 ° C.) while stirring with air rotation at 300 rpm, pressure filtration (air pressure 0.2 MPa) with a 300 mesh stainless steel filter (wire diameter 0.035 mm, plain weave) As a result, a milky white uniform polyolefin resin aqueous dispersion E-1 was obtained.

  Various characteristics of this aqueous dispersion are shown in Table 2. The number average particle diameter and the weight average particle diameter were 0.090 μm and 0.125 μm, respectively, and the distribution was one peak, and the polyolefin resin was dispersed in a good state in the aqueous medium. Further, the aqueous dispersion did not change in appearance even after being left for 90 days. In addition, when the resin composition after water-ized was analyzed, 1% of ethyl acrylate units were hydrolyzed and changed into acrylic acid. That is, the ester group remaining rate was 99%. This ester group residual rate was 99% without change even after standing at room temperature for 90 days.

(Production of aqueous polyolefin resin dispersion E-2)
A polyolefin resin aqueous dispersion E, except that Bondin HX-8290 (I) (manufactured by Atofina) was used as the polyolefin resin, and the amount of amine and the type and amount of organic solvent relative to the carboxyl group in the resin were changed as shown in Table 2. A polyolefin resin aqueous dispersion E-2 was obtained in the same manner as in the production of -1. Various characteristics of the aqueous dispersion are shown in Table 2.

(Production of aqueous polyolefin resin dispersion E-3)
Bondin LX-4110 (U) (manufactured by Atofina) as the polyolefin resin, N, N-dimethylethanolamine (hereinafter, DMEA) as the amine, n-propanol (hereinafter, NPA) as the organic solvent, resin solids, and Except having changed the quantity of the organic solvent like Table 2, polyolefin resin aqueous dispersion E-3 was obtained by operation similar to manufacture of polyolefin resin aqueous dispersion E-1. Various characteristics of the aqueous dispersion are shown in Table 2.

(Production of aqueous polyolefin resin dispersion E-4)
Primacol 5980I (D) (manufactured by Dow Chemical Company) was used as the polyolefin resin. Using a stirrer equipped with a 1 L glass container that can be sealed with a heater, 60.0 g of Primacol 5980I, 16.8 g (1.0 times equivalent to the carboxyl group of acrylic acid in the resin) of TEA , And 223.2 g of distilled water were charged into a glass container and stirred with the stirring blade rotating at a rotational speed of 300 rpm. No sedimentation of resin particles was observed at the bottom of the container, confirming that it was in a floating state. It was done. Therefore, while maintaining this state, the heater was turned on and heated after 10 minutes. Then, the system temperature was kept at 120 ° C. and further stirred for 30 minutes. Then, after cooling to room temperature (about 25 ° C.) while stirring with air rotation at 300 rpm, pressure filtration (air pressure 0.2 MPa) with a 300 mesh stainless steel filter (wire diameter 0.035 mm, plain weave) As a result, a slightly white aqueous dispersion E-4 was obtained. At this time, almost no resin remained on the filter. Various characteristics of the aqueous dispersion are shown in Table 2.

(Preparation of candelilla wax dispersion W-1)
40.0 g of Candelilla wax (manufactured by Toa Kasei Co., Ltd., acid value: 15.8, saponification value: 55.4), 8 .8 g (2.0 times equivalent of the amount required for complete neutralization and saponification of wax) and 151.2 g of distilled water were charged in a glass container, and the stirring blade was rotated. When the speed was stirred at 400 rpm, no resin precipitation was observed at the bottom of the container, confirming that it was in a floating state. Therefore, while maintaining this state, the heater was turned on and heated after 10 minutes. Then, the system temperature was kept at 100 ° C. and further stirred for 10 minutes. Then, after cooling to room temperature (about 25 degreeC), stirring by air cooling with a rotational speed of 600 rpm, the pale yellow uniform wax aqueous dispersion W-1 was obtained. The solid content concentration was 20.0% by mass, and the number average particle size was 0.27 μm.

Example 1
Aqueous dispersion E-1 and aqueous dispersion E-4 were mixed so that the solid content mass ratio was 90/10.
Then, under stirring, an aqueous paraffin wax dispersion (EMUSTAR-0135, manufactured by Nippon Seiwa Co., Ltd.) (hereinafter referred to as 0135) is the solid mass of the total amount of the wax (C) and the polyolefin resins (A) and (B). The ratio was added to 40/100. Furthermore, colloidal silica (Snowtex O, manufactured by Nissan Chemical Co., Ltd.) (hereinafter referred to as ST-O) as a rust preventive improver (D) is added to this mixed solution to 20 parts by mass with respect to 100 parts by mass of the total solid content. A coating agent for aqueous rust prevention was prepared by addition.

  Painted with a Meyer bar on the hot-dip galvanized steel sheet (made by Nippon Test Panel Osaka Co., Ltd., size 70 mm x 150 mm x 0.8 mmt) degreased from the resulting aqueous anti-corrosion coating agent so that the coating thickness after drying is 2 μm And heat-treated at 100 ° C. for 2 minutes to obtain a coated steel sheet. Table 3 shows the performance evaluation results of the obtained coating.

Examples 2 and 3
As shown in Table 3, a water-based anticorrosive coating agent was prepared in the same manner as in Example 1 except that the addition amount of 0135 was 15 parts by mass (Example 2) and 70 parts by mass (Example 3). Using this coating agent, a coated steel plate was obtained in the same manner as in Example 1. Table 3 shows the performance evaluation results of the obtained coating.

Example 4
The same operation as in Example 1 was performed except that the film thickness after drying was 1 μm. Table 3 shows the performance evaluation results of the obtained coating.

Examples 5 and 6
Aqueous dispersions E-1 and E-4 were prepared so that the solid mass ratio was 70/30 (Example 5) and 55/45 (Example 6), and (D) was colloidal silica (Snowtex S). , Manufactured by Nissan Chemical Co., Ltd. (hereinafter ST-S), and the amount added was 40 parts by mass with respect to 100 parts by mass of the resin solid content. Was prepared. Using this coating agent, a coated steel plate was obtained in the same manner as in Example 1. Table 3 shows the performance evaluation results of the obtained coating.

Examples 7 and 8
Example 1 except that a polyethylene wax aqueous dispersion (EMUSTAR-0443, manufactured by Nippon Seiwa Co., Ltd.) (hereinafter, 0443) (Example 7) and a candelilla wax aqueous dispersion W-1 (Example 8) were used as the wax. A water-based anticorrosive coating agent was prepared in the same manner as described above. Using this coating agent, a coated steel plate was obtained in the same manner as in Example 1. Table 3 shows the performance evaluation results of the obtained coating.

Example 9
A water-based antirust coating agent was prepared in the same manner as in Example 1 except that the antirust improver (D) was not added. Using this coating agent, a coated steel plate was obtained in the same manner as in Example 1. Table 3 shows the performance evaluation results of the obtained coating.

Example 10
Example 1 except that only E-1 was used as the aqueous dispersion, 0135 as (C) was 40 parts by mass with respect to 100 parts by mass of the polyolefin resin (A), and the addition amount of ST-O was 20 parts by mass. A water-based anticorrosive coating agent was prepared in the same manner as described above. Using this coating agent, a coated steel plate was obtained in the same manner as in Example 1. Table 3 shows the performance evaluation results of the obtained coating.

Reference example 1
Example 1 except that only E-4 was used as the aqueous dispersion, 0135 as (C) was 40 parts by mass with respect to 100 parts by mass of the polyolefin resin (B), and the addition amount of ST-O was 20 parts by mass. A water-based anticorrosive coating agent was prepared in the same manner as described above. Using this coating agent, a coated steel plate was obtained in the same manner as in Example 1. Table 3 shows the performance evaluation results of the obtained coating.

Example 11
Aqueous dispersions E-1 and E-4 were used so that the solid content mass ratio was 80/20. A water-based antirust coating agent was prepared in the same manner as in Example 1 except that 20 parts by mass of Al) was used with respect to 100 parts by mass of the resin. Using this coating agent, a coated steel plate was obtained in the same manner as in Example 1. Table 4 shows the performance evaluation results of the obtained coating.

Example 12
Aqueous dispersions E-1 and E-4 were used so that the solid content mass ratio was 80/20, and magnesium oxide (manufactured by Wako Pure Chemical Industries, 0.01 μm) as a rust preventive improver (D) ( Hereinafter, an aqueous antirust coating agent was prepared in the same manner as in Example 1 except that MgO) was used. At this time, since the viscosity increased, the coating agent was prepared by diluting with water. Using this coating agent, a coated steel plate was obtained in the same manner as in Example 1. Table 4 shows the performance evaluation results of the obtained coating.

Example 13
A coating agent for aqueous rust prevention was prepared in the same manner as in Example 1 except that E-2 was used instead of the aqueous dispersion E-1. Using this coating agent, a coated steel plate was obtained in the same manner as in Example 1. Table 4 shows the performance evaluation results of the obtained coating.

Example 14
A coating agent for aqueous rust prevention was prepared in the same manner as in Example 1 except that E-3 was used instead of the aqueous dispersion E-1. Using this coating agent, a coated steel plate was obtained in the same manner as in Example 1. Table 4 shows the performance evaluation results of the obtained coating.

Example 15
The aqueous dispersions E-1 and E-4 were mixed so that the solid content mass ratio was 90/10. This and 0135 were mixed so that (C) / {(A) + (B)} = 20/100 (mass ratio). ST-O and a silane coupling agent (manufactured by Nihon Unicar Co., Ltd., A-1100) (hereinafter referred to as A-1100) as a crosslinking agent are further added to this mixed solution by 20 masses per 100 mass parts of the resin. An aqueous rust preventive coating agent was prepared by adding 1 part by mass and 1 part by mass. A coated steel sheet was obtained in the same manner as in Example 1 except that the coating thickness after drying was 1 μm using this coating agent and heat treatment was performed at 120 ° C. for 5 minutes. Table 4 shows the performance evaluation results of the obtained coating.

Comparative Example 1
An aqueous coating agent was prepared in the same manner as in Example 1 except that the wax (C) was not added. Using this coating agent, a coated steel plate was obtained in the same manner as in Example 1. Table 4 shows the performance evaluation results of the obtained coating.

Comparative Example 2
An aqueous coating agent was prepared in the same manner as in Example 1 except that (C) / {(A) + (B)} = 100/100 (mass ratio). Using this coating agent, a coated steel plate was obtained in the same manner as in Example 1. Table 4 shows the performance evaluation results of the obtained coating.

Comparative Example 3
Instead of the polyolefin resin (B), an ethylene-maleic acid alternating copolymer having a high unsaturated carboxylic acid content (manufactured by ALDRICH, weight average molecular weight 100,000 to 500,000, maleic acid content 50% by mass) Using. A 10 mass% aqueous solution was prepared by adding 1.0-fold equivalent of TEA to the carboxyl group in the ethylene-maleic acid alternating copolymer, and this aqueous solution was designated S-1. An aqueous coating agent was prepared in the same manner as in Example 1 except that S-1 was used and the solid mass ratio of E-1 and S-1 was 80/20. Using this coating agent, a coated steel plate was obtained in the same manner as in Example 1. Table 4 shows the performance evaluation results of the obtained coating.

By applying the coating agent for water rust prevention of Examples 1 to 15 to a metal plate, the rust prevention, water resistance, alcohol resistance under high load, workability, and adhesion to a steel plate were good. It was. Moreover, it was excellent also in alkali resistance except the example (Example 6, Reference Example 1 ) which contains many polyolefin resin (B) with high unsaturated carboxylic acid content. Moreover, the antirust improvement by addition of the antirust improver was recognized (Examples 1 and 9). Although the rust preventive property was lowered when the coating was thin (Example 4), the improvement of the rust preventive property was confirmed by adding a crosslinking agent (Example 15 ).

When no wax was added, there was no alcohol resistance under high load (Comparative Example 1). When the amount of the wax added was larger than the range of the present invention, the processability was remarkably reduced (Comparative Example 2). Moreover, even if it replaced with polyolefin resin (B) and used resin with many unsaturated carboxylic acid content, performance, such as rust prevention property and alkali resistance, was bad (comparative example 3).

Claims (4)

The following polyolefin resin (A), the following polyolefin resin (B), wax (C), and an aqueous medium are contained, and the mass ratio of the components (A) to (C) is (A) / (B) = 100/0. 50/50 , (C) / {(A) + (B)} = 10 / 100-80 / 100 satisfying the coating agent for rust prevention.
Polyolefin resin (A): a copolymer composed of an unsaturated carboxylic acid or its anhydride (A1), an ethylene-based hydrocarbon (A2), and an acrylic ester or methacrylic ester (A3), The mass ratio of the components (A1) to (A3) is (A1) / {(A1) + (A2) + (A3)} = 0.01 / 100 to 5/100, (A2) / (A3) = 55/45 Polyolefin resin satisfying ~ 99/1.
Polyolefin resin (B): a copolymer composed of an unsaturated carboxylic acid or its anhydride (B1) and an ethylene hydrocarbon (B2), wherein the mass ratio of the components (B1) to (B2) is ( Polyolefin resin satisfying B1) / (B2) = 12/88 to 30/70.   The coating agent for rust prevention according to claim 1, wherein the mass ratio of the polyolefin resins (A) and (B) is (A) / (B) = 98/2 to 50/50.   Furthermore, the rust preventive improver (D) is contained, and the amount thereof is 1 to 100 parts by mass with respect to 100 parts by mass of the total mass of solids (A) to (C). Or the coating agent for rust prevention of 2.   The laminated metal material which provides the coating film obtained by apply | coating the coating agent for rust prevention in any one of Claims 1-3 to a metal material, and drying.