JP2001240889A - Lubrication-treated steel material having excellent rust prevention property, and coating composition therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To actualize a Lubrication-treated steel material having improved processability, degreasing power and blocking resistance and excellent rustproofing properties in stack in the presence of water in an oil uncoated state. SOLUTION: This steel material is coated with a coating composition containing 74-97.7 mass % of an acrylic resin having 30-150 acid value and 5-90 deg.C glass transition temperature, 2-20 mass % of a water repellent selected from a carboxylic acid ester, a metallic soap, polyethylene fine powder and fluororesin fine powder and 0.3-6 mass % of a mixture of an alkylamidocarboxylic acid or its salt and an alkanolamine and dried to form an organic coating film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to steel sheets to be pressed (for example, hot-rolled pickled sheets, cold-rolled steel sheets, plated steel sheets,
And a coating composition for lubricating steel pipes (in this specification, steel materials for press working such as steel sheets and steel pipes are collectively referred to as steel materials), and a coating composition obtained by using this coating composition. Particularly, the present invention relates to a lubricated steel material excellent in rust prevention during stacking.

[0002]

2. Description of the Related Art It is a conventional means to use a lubricating oil when pressing a steel material for press working such as a steel plate or a steel pipe. However, in recent years, due to environmental problems when using lubricating oil, rather than applying lubricating oil at the time of press working, various lubricants are applied to the surface of steel at an appropriate stage up to the stage of manufacturing or processing. Lubricated steel materials having an organic film containing them have been widely used.

[0003] The main component of the paint (coating composition) for forming the organic film is a conventionally known drying or baking such as an acrylic resin, an epoxy resin, a melamine resin, a phenol resin, or a urethane resin. It is a curable coating film forming component. This resin component is blended with one or more of fatty acid, fatty acid ester, fatty acid soap, metal soap, alcohol, polyethylene fine powder, graphite, molybdenum disulfide, fluororesin fine powder, etc. as a lubricant to lubricate steel materials. Used for processing (for example,
No. 250099).

[0004] Generally, coating compositions for lubricated steel are:
It is important to form a film with the following properties in practical use: a) Lubricity during press working, b) From the time of manufacturing lubricated steel to the time after depressing and degreasing after pressing. C) degreasing and cleaning properties (film removal properties), and d) blocking resistance (the properties of the coatings not sticking to each other even when layered).

In order to satisfy these requirements, Japanese Patent Application Laid-Open No.
No. 7397 discloses a lubricant for a lubricated steel material in which a water-soluble rust inhibitor such as polyethylene glycol and hydroxybenzotriazoles, imidazoles, amino acids and the like is blended with an organic polymer compound having a carboxylic acid. ,
Since the film contains polyethylene glycol, the film swells due to dew condensation in a humid environment, and there is a problem of blocking in a stacked state.

JP-A-9-296132 discloses a lubricant for lubricated steel using a zinc, calcium or aluminum salt of phosphoric acid and molybdic acid as a rust preventive agent. There is a lubricated steel material using a mixture of sulfonamide carboxylic acid and a cyclic amine as a rust inhibitor, and JP-A-10-1690 discloses a lubricated steel sheet using an alkylene sulfoamide carboxylic acid as a rust inhibitor. Lubricants are each disclosed.

[0007]

The above-mentioned coating compositions for various lubricated steel materials are focused on lubricity during press working. Therefore, it has many difficulties in terms of rust prevention, and it is difficult to use it in harsh corrosive atmospheres such as storage along the coast or along roads with heavy traffic, or transporting thin sheets by sea using coils. Rust formation has been a problem. This rusting is particularly noticeable under stack conditions such as storage and transportation.

[0008] Therefore, at present, there is no lubricated steel coating composition which satisfies all of the workability, degreasing property, anti-blocking property and anti-rust property. The present invention, in addition to processability, degreasing, blocking resistance, had been a problem conventionally,
It is an object of the present invention to provide a lubricated steel material excellent in rust resistance under oilless stack conditions and a coating composition therefor.

[0009]

The inventors of the present invention have investigated and studied the rusting phenomenon during unlubricated stacking, which has been a problem with conventional lubricated steel materials. Or, in an environment where steel pipes are stacked, water vapor condenses from the air in the gaps between steel materials,
Due to the action of the condensed moisture and the load under the stack condition, the film is damaged in this gap, and the battery action due to the presence of moisture also contributes, accelerating the rusting process of the steel material. I figured out.

Therefore, the present inventors can exert a rust-preventive force corresponding to the above-mentioned mechanism, and have the other characteristics described above.
In other words, as a result of further research to provide a coating composition for lubricated steel that also satisfies workability, degreasing, and deblocking properties, a specific water repellent and a rust inhibitor were added to a certain acrylic resin. The inventors have found that the obtained composition is optimal, and have completed the present invention.

According to the present invention, (A) an acrylic resin having an acid value of 30 to 150, a glass transition temperature of 5 to 90 ° C. and 74 to 97.7 mass% based on the total amount of the following (A) to (C): B) 2-20% by mass of water repellent (preferably selected from carboxylate, metal soap, polyethylene fine powder and fluororesin fine powder)
And (C) a rust inhibitor consisting of a mixture of an alkylamidocarboxylic acid or a salt thereof and a nitrogen-containing basic compound (preferably alkanolamine) in an amount of 0.3 to 6% by mass. A lubricated steel material having a coating composition for steel materials and an organic film formed from the coating composition.

[0012]

DETAILED DESCRIPTION OF THE INVENTION The acrylic resin used as a film-forming component in the lubricating steel coating composition of the present invention has an acid value of 30 to 150, preferably 40 to 120, and a glass transition temperature of 5 to 5. 90 ° C., preferably 10-85 ° C. If the acid value is less than 30, the formed film is not sufficiently degreased and washed (removable) with an alkaline aqueous solution, and if the acid value exceeds 150, the rust resistance of the film is reduced. The glass transition temperature is
When the temperature is lower than 5 ° C., the adhesiveness of the resin is increased and the blocking resistance is reduced.

The acrylic resin used in the present invention may be a commonly used thermoplastic acrylic resin for coatings, and may be obtained by any polymerization method. Such an acrylic resin and a method for producing the same are described, for example, in Kyozo Kitaoka, “Introduction to Synthetic Resins for Paints” (published by Kobunshi Kanko Kaisha,
1974).

The acrylic resin is a vinyl (ie, α, β-ethylenic) unsaturated carboxylic acid or a vinyl unsaturated carboxylic acid ester (a linear or branched alcohol having 1 to 25 carbon atoms and an unsaturated carboxylic acid). (Esters with the above) and polymerized (mainly monofunctional). Specific examples of these monomers include:
Acrylic or methacrylic acid (hereinafter abbreviated as (meth) acrylic acid), sorbic acid, itaconic acid, maleic acid, fumaric acid, methyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate , Isobutyl (meth) acrylate, 2-ethyl-hexyl (meth) acrylate, hexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, 2-hydroxyethyl
(Meth) acrylate, 2-hydroxypropyl (meth)
Acrylate, glycidyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, and the like.

In the polymerization, a monomer mixture of two or more components comprising at least one vinyl unsaturated carboxylic acid and at least one vinyl unsaturated carboxylic acid ester is generally used. Polymerization can be carried out by a solution polymerization method or an emulsion polymerization method. By adjusting the proportion of the unsaturated carboxylic acid component in the monomer mixture, a polymer having a desired acid value in the range of 30 to 150 can be obtained. Similarly, regarding the glass transition temperature (Tg) of the polymer, by adjusting the type and the use ratio of the carboxylic acid and the carboxylic acid ester component, it is possible to obtain a polymer having a glass transition temperature of 5 to 90 ° C. Can be. The polymer acrylic resin may be neutralized with ammonia or amine to improve the stability of the coating composition.

As the water repellent of the lubricating steel coating composition of the present invention, a water repellent which does not inhibit the film forming property and film removing property of the coexisting acrylic resin and the rust preventive action of the rust preventive is used. The water repellent used in the present invention is preferably one or more selected from carboxylate, metal soap, polyethylene fine powder, and fluororesin fine powder.
All of these water repellents are known to be effective as lubricants, but the water repellent used in the present invention does not necessarily have to exhibit lubricity.

Carboxylic esters useful as water repellents are alkyl esters of aliphatic or aromatic monocarboxylic acids or polyvalent carboxylic acids such as di- or tricarboxylic acids. Specific examples of such carboxylic acid esters include butyl stearate, di-2-ethylhexyl phthalate, diheptyl phthalate, di-n-octyl phthalate, dinonyl phthalate, diisodecyl phthalate, ditridecyl phthalate, and di-adipic acid. 2-ethylhexyl,
Trioctyl trimellitate, ethylene glycol distearate, glycerin tricaprylate, trimethylolpropane tristearate and the like can be mentioned.

Examples of the metal soap include aluminum stearate, calcium stearate, zinc stearate, magnesium stearate and the like. Representative examples of the fluororesin are polytetrafluoroethylene resin and polyvinylidene fluoride resin. The average particle size of the polyethylene fine powder and the fluororesin fine powder is not particularly limited, but the preferable average particle size is about 0.1 to 10 μm.

The lubricating steel coating composition of the present invention includes:
A mixture of an alkylamidocarboxylic acid or a salt thereof and a basic compound containing nitrogen is blended as a rust preventive. With the sulfonamide carboxylic acids described in JP-A-4-78679, the high rust-preventing ability achieved by the present invention cannot be obtained. Alkyl amide carboxylic acid or salt thereof:
The mixing ratio with the nitrogen-containing basic compound is preferably in the range of 2: 1 to 1: 5 in molar ratio.

The alkylamidocarboxylic acid used as one component of the rust preventive is an amide compound obtained by reacting a fatty acid having 6 to 22 carbon atoms with an aminocarboxylic acid and / or a lactam.

The fatty acids having 6 to 22 carbon atoms include hexanoic acid, 4-methylpentanoic acid, 2-ethylbutanoic acid, 2,2
-Dimethylbutanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, eicosanoic acid, docosanoic acid, oleic acid, erucic acid, 2,4 -Hexadienoic acid, 9,12-octadecadienoic acid, 3,5,5-trimethylhexanoic acid and the like. The alkyl chain of these fatty acids may be linear or branched, but is more preferably a branched alkyl chain.
Examples of the aminocarboxylic acid include aminoacetic acid, N-methylaminoacetic acid, 2-aminopropionic acid, 3-aminopropionic acid, 2-aminobutyric acid, 3-aminobutyric acid, and 4-aminobutyric acid. Lactams include azetidinone, pyrrolidone, ε-caprolactam and the like.

The alkylamide carboxylic acid component of the rust inhibitor may be used in the form of a carboxylate by reacting with an appropriate base in order to increase water solubility. The carboxylate may be, for example, a sodium salt, a potassium salt, an ammonium salt, an alkanol ammonium salt and the like.

As the nitrogen-containing basic compound, which is the other component of the rust preventive, ordinary amines can be used. Examples of such compounds include, but are not limited to, workability, blocking resistance, degreasing property, rust prevention property, and the like. Considering performance, alkanolamines are preferred. Alkanolamines include monoethanolamine, diethanolamine, triethanolamine,
Monopropanolamine, dipropanolamine, tripropanolamine, dimethylethanolamine, diethylethanolamine, ethyldiethanolamine, butyldiethanolamine and the like can be mentioned.

The alkylamidocarboxylic acid and the alkanolamine as the rust preventive may be added separately, or a commercial product which is a mixture of these may be added. Examples of such commercially available products include Hostacore IS / 1 [Clariant Japan
Co., Ltd.].

The lubricating steel coating composition of the present invention containing the above-mentioned acrylic resin, water repellent, and rust preventive is based on (A) acrylic resin 74 to 100 based on the total weight of these three components. 97.7% by mass, (B) 2 to 20% by mass of water repellent, (C)
Rust inhibitor 0.3 to 6% by mass, containing the above three components.

When the amount of the water repellent is less than 2% by mass, the water repellency becomes insufficient and rust prevention and workability deteriorate. When the amount exceeds 20% by mass, the effect of the water repellent is saturated. However, further improvement in water repellency cannot be expected, which is economically disadvantageous. The preferred amount of the water repellent is 5 to 15% by mass.

If the amount of the mixture of the alkylamide carboxylic acid, which is a rust preventive, and the basic compound containing nitrogen is less than 0.3% by mass, the rust preventive properties are insufficient. Decrease. The preferred amount of the rust inhibitor is 1 to
4% by mass.

In the coating composition of the present invention, a mixture of an alkylamidocarboxylic acid and a basic compound containing nitrogen is used as a rust preventive, but other known rust preventives such as benzotriazoles and sulfonamidocarboxylic acids are used. An acid or the like can be used in combination as long as the effects of the present invention are not reduced. Also,
Various additives (e.g., colorant, surfactant, defoamer, pH adjuster, etc.) commonly used in paints can be arbitrarily added, but they may substantially add to the properties of the coating composition of the present invention. Should be selected so as not to cause any serious adverse effects.

In order to lubricate steel using the coating composition of the present invention, the coating composition is diluted with water or a solvent to obtain a coating composition. A solid film may be formed by coating a steel material with a flow coater, spray, electrostatic coating, electrodeposition coating, or the like, and drying it with hot air or active energy ray irradiation. When the acrylic resin is obtained by emulsion polymerization or solution polymerization, by adding and mixing a rust inhibitor and a water repellent, and a small amount of other additives as necessary, and adjusting the concentration as necessary as necessary. , A coating composition can be prepared.

The coating composition of the present invention has an adhesion amount after drying.
It is preferable that the steel material is coated so as to be in the range of 0.2 to 6.0 g / m ² , preferably 0.5 to 3.0 g / m ² . The amount of adhesion is 0.
When it is less than ² g / m 2, lubricity and anticorrosive properties is insufficient, 6.0 g /
be greater than m ^2, more lubricity and corrosion resistance improving effect of hardly obtained. The drying temperature of the coating film is 50 ~ 150 ℃
The temperature is preferably set to

When a steel material is lubricated with the coating composition of the present invention, a resinous organic film containing a water repellent and a rust inhibitor is formed in an acrylic resin. This film has lubricity sufficient for press working. This lubricity is mainly attributable to the acrylic resin film itself, but the water repellent also contributes somewhat to lubricity depending on the type.

The film formed from the coating composition of the present invention is easily removed by alkali cleaning, so that the film has good degreasing and cleaning properties (film removing property), and can be completely removed by degreasing and cleaning performed before the chemical conversion treatment. Therefore, there is no adverse effect on the chemical conversion treatment. Also, the blocking resistance is good. Further, it is possible to exhibit an unprecedented excellent rust prevention property that rust does not occur even if the stack is stored for a long time without oil coating.
Accordingly, rust is prevented from being generated during the production, storage, transportation, pressing and after depressurization of the lubricated steel material.

[0033]

EXAMPLES The monomer compositions and properties (Tg
= Glass transition temperature, ° C), using a coating composition containing the components shown in Table 2 as a water-based coating composition having a solid content of 25% by mass in accordance with a conventional coating preparation method. Prepared. Composition of coating composition shown in Table 2
(% By mass of the water repellent and the rust inhibitor) is the mass% based on the total amount of the resin, the water repellent and the rust inhibitor, and the amount of the resin is the balance. All aqueous coating compositions have a pH value with aqueous ammonia.
Adjusted to 8.0.

Using this coating composition, one side of a 0.8 mm thick cold-rolled steel sheet whose surface was cleaned by degreasing was coated with a bar coater so that the dry film coating amount was 3 g / m ^2. ,
The coating film was dried by hot-air drying at 110 ° C. for 10 minutes to obtain a lubricated steel sheet. The lubricated steel sheet was tested for cylindrical drawability (evaluation of lubricity), degreasing and cleaning, blocking resistance, and rust prevention during stacking according to the following test procedures.
The test results are also shown in Table 2.

[0035]

[Table 1]

[0036]

[Table 2]

[Test method] 1) Cylindrical drawability Measure the maximum blank diameter that can be drawn out with a punch diameter of 33.0 mm φ and a holding pressure of 1000 kg / cm ² , and determine the limit draw ratio by the following formula.
(A) was calculated.

Critical drawing ratio = maximum blank diameter / punch diameter The critical drawing ratio (B) of the unlubricated steel sheet is similarly determined, and the ratio of the critical drawing ratio of the lubricated test steel sheet to the unlubricated steel sheet (A / B) Was used to evaluate the cylindrical drawability according to the following criteria.

×: A / B <1.0 Δ: A / B = 1.0 to 1.1 ○: A / B> 1.1 A / B = Limited drawing ratio of lubricated steel sheet / critical drawing ratio of untreated steel sheet.

2) Degreasing and cleaning properties Fine cleaner FC4326 [Nippon Parkerizing
Was sprayed at a temperature of 60 to 70 ° C. at a spray pressure of 1 kg / cm ² for 5 seconds to perform degreasing cleaning, and then visually inspected for water repellency and evaluated according to the following criteria.

×: whole surface of water cissing △: partial water cissing ○: no water cissing

3) Blocking resistance Two lubricated steel sheets each having a size of 0.8 × 70 × 150 mm were overlaid so that the dried coating films were in close contact with each other, and a load of 67 kg / cm ² was applied. After aging at a temperature of 50 ° C. for 1 minute, aging was performed under a light load of 500 g / m ² at 40 ° C. for 16 hours, and further aging was performed at room temperature under no load for 50 days. Thereafter, the stacked steel sheets were separated, and the blocking resistance was evaluated according to the following criteria based on the adhesion state of the coating film at the time of separation.

×: Adhesion is present Δ: Adhesion is slightly present ○: No adhesion is present

4) Rust resistance Two lubricated steel sheets of 0.8 × 70 × 150 mm size are superposed on each other so that the dried coating surfaces are in close contact with each other, and a load of 50 kg / cm ² is applied. And aged at a temperature of 50 ° C. for 48 hours. One drop of pure water was interposed between the dried coating surfaces. Thereafter, the laminated steel sheets were separated, and the rust prevention was evaluated according to the following criteria based on the rusting state of the coating film surface.

×: Rust is present Δ: Rust is slightly present ○: No rust is present

As can be seen from the test results in Table 2, each of the coating compositions according to the present invention can provide a lubricated steel material which satisfies all of cylindrical drawability, degreasing and washing properties, blocking resistance and rust prevention. it can. In particular, the rust prevention test of this example was carried out with no oil applied, and a strict test condition of maintaining a high temperature (50 ° C.) under the stack condition with moisture interposed was adopted. Even after 48 hours under this stacking condition, no corrosion occurred, indicating that the film has a high degree of rust prevention.

On the other hand, Japanese Patent Publication No. 4-78679 described in the prior art
The publication discloses that no corrosion has occurred even after 24 hours of a stack test in an oiled state. The rust preventive used in Test No. 10 in Table 2 of this example corresponds to the rust preventive used in this publication. However, the test in Table 2
As can be seen from the results of No. 10, when the conventional composition disclosed in the above publication was tested under the test conditions of the present invention in the state of no oil coating, rust was generated. It is evident that the coating composition of (1) has remarkably improved rust prevention as compared with the prior art.

Further, in the comparative examples in which the properties of the acrylic resin were out of the range of the present invention or in which no water repellent or rust inhibitor was added, at least one property was deteriorated. Furthermore, in the comparative example using a commercially available rust preventive oil, the cylindrical drawability is low.

[0049]

The lubrication treatment of steel using the coating composition of the present invention significantly improves the rust prevention property at the time of stacking, which has been a problem in the past, and has improved workability (lubricity),
It becomes possible to obtain a lubricated steel material having good performance in degreasing and blocking resistance.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C10M 133/08 C10M 133/08 133/16 133/16 173/02 173/02 // C10N 10:04 C10N 10:04 10:06 10:06 20:00 20:00 AZ 20:06 20:06 Z 30:00 30:00 A 30:12 30:12 40:24 40:24 Z 50:02 50:02 50:08 50:08 (72) Inventor Hiroyuki Ito 2-3-9 Fujisaki, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture F-term (reference) 4H104 BB17C BB32C BB33C BE04C BE11C CA02C CB08A CB09A CD01C CD02C EA04A EA08C EA22A FA02 FA03 LA01 PA11 QA08 QA12

Claims (4)

[Claims] (1) Based on the total amount of the following (A) to (C),
(A) an acid value of 30 to 150, an acrylic resin having a glass transition temperature of 5 to 90 ° C., 74 to 97.7 mass%, and (B) a water repellent of 2 to 20 mass%,
(C) A rust preventive comprising a mixture of an alkylamidocarboxylic acid or a salt thereof and a nitrogen-containing basic compound in an amount of 0.3 to 6% by mass, a coating composition for lubricated steel. 2. The coating composition for lubricated steel according to claim 1, wherein the water repellent is at least one member selected from the group consisting of carboxylate, metal soap, polyethylene fine powder and fluororesin fine powder. 3. The coating composition for lubricated steel according to claim 1, wherein the nitrogen-containing basic compound is an alkanolamine. 4. A lubricated steel material having an organic film formed from the coating composition according to claim 1. Description: