Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/36—Removing material
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F1/00—Etching metallic material by chemical means

Definitions

• the present invention relates to a coating agent for forming an etching resist film, which is used to form an etching resist film on the surface of grain-oriented electrical steel sheet.
• Grain-oriented electrical steel sheets have excellent magnetic properties and are primarily used as material for the iron cores of transformers. To improve the energy efficiency of transformers, there is a need to reduce the iron loss of grain-oriented electrical steel sheets.
• One known method for reducing the iron loss of grain-oriented electrical steel sheets is to introduce linear grooves into the surface of the sheet. In this method, non-uniform strain is introduced by forming linear grooves on the surface of the steel sheet. This subdivides the width of the magnetic domains and reduces iron loss.
• Patent Document 1 describes a method for forming linear grooves on the surface of a steel sheet by uniformly applying a coating agent for forming an etching resist film to the surface of the steel sheet and performing a baking process to form an etching resist film, then irradiating the formed etching resist film with a laser to remove the etching resist film in linear patterns, and then performing an etching process.
• the inventors have found that there is room for improvement in the characteristics of the etching resist coating formed on the surface of grain-oriented electrical steel sheets in the above-mentioned conventional technology.
• the width of the portion of the etching resist coating removed by the laser irradiation (hereinafter sometimes referred to as the "coating removal portion") can vary greatly, or the width of the coating removal portion can differ significantly from the laser beam diameter.
• the etching resist coating's ability to be accurately removed in accordance with the laser irradiation pattern (hereinafter sometimes referred to as "laser removability") is poor. If the laser removability of the etching resist coating is poor, the coating removal portion cannot be accurately formed, and as a result, it can be difficult to form linear grooves in the designed shape on the surface of the grain-oriented electrical steel sheet.
• etching resist film when electrolytic etching was performed using an etching resist film according to conventional technology, parts of the surface of the etching resist film could discolor, changing its appearance.
• the change in color tone of the etching resist film suggests a decrease in the resistance of the etching resist film to the electrolytic etching solution (hereinafter sometimes referred to as "resist characteristics").
• resist characteristics when using a strong alkaline aqueous solution to peel and remove the etching resist film that is no longer needed after the etching process is completed, parts of the etching resist film could not peel off and remain on the surface of the grain-oriented electrical steel sheet.
• the present invention was made in consideration of the above-mentioned problems with conventional technology, and aims to provide a coating agent for forming an etching resist film that can form an etching resist film that has excellent laser removability, resist properties, and peelability.
• the gist and configuration of the present invention are as follows.
• a solvent in terms of solid content, 100 parts by weight of a water-based alkyd resin, 0.10 parts by mass or more and 30 parts by mass or less of melamine resin; 50 parts by mass or more and 200 parts by mass or less of aluminum-containing oxide;
• the composition contains 30 parts by mass or more and 100 parts by mass or less of a titanium-containing oxide, and 0.10 parts by mass or more and 5.0 parts by mass or less of carbon black, the total amount of solid contents of the aqueous alkyd resin, the melamine resin, the aluminum-containing oxide, the titanium-containing oxide, and the carbon black accounts for 80 mass% or more of the total solid contents; Coating agent for forming etching resist film.
• the aqueous alkyd resin is an aqueous alkyd resin obtained by reacting an alkyd resin with a polymerizable vinyl monomer.
• the proportion of the total solid content in the coating agent for forming an etching resist is 10% by mass or more and 80% by mass or less;
• the solvent contains ethylene glycol mono-n-butyl ether.
• the etching resist film formed by applying the coating agent for forming an etching resist film according to the present invention to the surface of a grain-oriented electrical steel sheet and baking it has superior laser removability, resist properties, and peelability compared to conventional techniques.
• the present invention provides a method for producing a medicament for the treatment of a pulmonary arthritis.
• the solvent in solids equivalent, 100 parts by weight of a water-based alkyd resin, 0.10 parts by mass or more and 30 parts by mass or less of melamine resin; 50 parts by mass or more and 200 parts by mass or less of aluminum-containing oxide;
• the composition contains 30 parts by mass or more and 100 parts by mass or less of a titanium-containing oxide, and 0.10 parts by mass or more and 5.0 parts by mass or less of carbon black, the total amount of solid contents of the aqueous alkyd resin, the melamine resin, the aluminum-containing oxide, the titanium-containing oxide, and the carbon black accounts for 80 mass% or more of the total solid contents;
• This invention relates to a coating agent for forming an etching resist film.
• the coating agent for forming an etching resist film according to the present invention is composed primarily of a water-based alkyd resin, to which a melamine resin crosslinking agent, an aluminum-containing oxide, a titanium-containing oxide, and carbon black are added, and the resulting mixture is dissolved or mixed in a solvent.
• the coating agent for forming an etching resist film according to the present invention is applied to the surface of a grain-oriented electrical steel sheet and baked at a predetermined temperature for a predetermined time, causing the solvent to evaporate and a crosslinking reaction to occur, forming an etching resist film on the surface of the grain-oriented electrical steel sheet.
• the term "coating agent for forming an etching resist film” refers to a liquid coating agent primarily composed of resin, which is used to form an etching resist film.
• the term “etching resist film” refers to a solid film formed on the surface of a substrate after the above-described process using the coating agent for forming an etching resist film.
• the commonly used term “etching resist” sometimes refers to a coating agent for forming an etching resist film, and sometimes refers to an etching resist film.
• the two terms "coating agent for forming an etching resist film” and “etching resist film” are used strictly separately.
• the coating agent for forming an etching resist film is applied, leaving continuous or discontinuous linear regions in a direction intersecting the rolling direction as non-coated regions.
• the coated regions protected by the etching resist film prevent contact between the surface of the grain-oriented electrical steel sheet and the etching solution, preventing corrosion of the grain-oriented electrical steel sheet.
• corrosion occurs when the surface of the grain-oriented electrical steel sheet comes into contact with the etching solution, forming linear grooves.
• the etching resist film is removed as needed.
• solid content refers to the remaining solid components contained in the coating agent for forming an etching resist film, excluding substances that are lost by evaporation, such as solvents and water.
• the term "solids content equivalent” refers to the content of each component in a coating agent for forming an etching resist film being expressed based on its solid content.
• the coating agent for forming an etching resist film according to the present invention is prepared by mixing a water-based alkyd resin, a melamine resin, an aluminum-containing oxide, a titanium-containing oxide, and carbon black in a solvent.
• the water-based alkyd resin and melamine resin used in the preparation may themselves contain solvent.
• the aluminum-containing oxide, titanium-containing oxide, and carbon black may adsorb moisture from the air. For this reason, when expressing the content of each component, it is appropriate to express the content converted into solids content rather than the content of the actual mixed components.
• the mass of the solid content of the water-based alkyd resin contained in the coating agent for forming an etching resist film is defined as 100 parts by mass, and the content of the other components is expressed in parts by mass converted based on this.
• each component expressed in terms of solid content
• the content of each component, expressed in terms of solid content remains unchanged before and after the application and baking of the coating agent for forming an etching resist film. Therefore, by quantitatively analyzing the components of the etching resist film after baking, it is possible to determine the content of each component, converted to solid content, contained in the coating agent for forming an etching resist film before baking.
• the coating agent for forming an etching resist film according to the present invention contains 100 parts by mass of water-based alkyd resin in a solvent, calculated as solid content.
• the water-based alkyd resin is the main component of the coating agent for forming an etching resist film according to the present invention, and also serves as the main component of the etching resist film after application and baking.
• Water-based resin is a general term for both water-dispersible resins in which the resin is uniformly dispersed in water, and water-soluble resins that are easily soluble in water.
• any conventionally known water-based alkyd resin can be used without particular limitation.
• Alkyd resins which are the raw materials for water-based alkyd resins, are obtained by a dehydration condensation reaction between a polybasic acid, a polyhydric alcohol, and fats and oils or processed fats and oils, and optionally by further reacting with a monobasic acid.
• the coating agent for forming an etching resist film according to the present invention is a water-based alkyd resin obtained by reacting an alkyd resin with a polymerizable vinyl monomer.
• a coating agent for forming an etching resist film can be obtained that is capable of forming an etching resist film with excellent resist properties and removability.
• polybasic acids used in the synthesis of alkyd resins include phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, tetrahydrophthalic acid, succinic acid, maleic acid, adipic acid, sebacic acid, azelaic acid, himic acid, itaconic acid, methylhexahydrophthalic acid, 1,4-cyclohexanedicarboxylic acid, methylcyclohexenetricarboxylic acid, pyromellitic acid, and anhydrides thereof. These polybasic acids can be used alone or in combination of two or more.
• polyhydric alcohols used in the synthesis of alkyd resins include ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, butanediol, decanediol, diethylene glycol, pentanediol, neopentyl glycol, butylethylpropanediol, glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, sorbitol, 1,4-cyclohexanedimethanol, tricyclodecanedimethanol, etc. These polyhydric alcohols can be used alone or in combination of two or more.
• Fats and oils and processed oil products examples include tung oil, linseed oil, dehydrated castor oil, safflower oil, soybean oil, castor oil, tall oil, rice bran oil, and their fatty acids, hygienic fatty acids, etc.
• processed fats and oils obtained using the above-mentioned fats and oils as the main raw material can be used. Examples of such processed fats and oils include modified oils, isomerized oils, polymerized oils, maleated oils, boiled oils, etc., which are obtained using the above-mentioned fats and oils as the main raw material. These fats and oils and processed fats can be used alone or in combination of two or more.
• Monobasic Acids examples include benzoic acid, p-t-butylbenzoic acid, methylbenzoic acid, versatic acid, isodecanoic acid, isotridecanoic acid, crotonic acid, non-drying oil fatty acids, etc. These monobasic acids may be used alone or in combination of two or more.
• polymerizable Vinyl Monomer in a preferred embodiment of the present invention, conventionally known polymerizable vinyl monomers can be used without particular limitation as the polymerizable vinyl monomer to be reacted with the alkyd resin to obtain the aqueous alkyd resin.
• Examples of the polymerizable vinyl monomer to be used in the reaction with the alkyd resin include (meth)acrylic acid ester monomers such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, ethylcyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, toluyl (meth)acrylate, and glycidyl (meth)acrylate; aromatic polymerizable unsaturated monomers such as styrene, ⁇ -methylstyrene, chlorostyrene, vinyltoluene, vinylnaphthalene, phenyl (meth)acrylate, benzyl (meth)acrylate, and vinyl benzoate; vinyl acetate; vinyl monomers such as vinyl chloride and vinyl propionate; N
• Water-based alkyd resins may be commercially available or synthesized from raw materials. When using commercially available products, it is preferable to use those synthesized using one of the compounds listed above as raw materials.
• synthesizing water-based alkyd resins from raw materials the following procedure is preferably used. First, a predetermined amount of polybasic acid, polyhydric alcohol, oil or fat or processed oil product, and optionally a monobasic acid are added to a reaction vessel, and the contents are heated while stirring to cause a dehydration condensation reaction. When the acid value of the solids reaches 3 to 30 mg KOH/g, heating is stopped and the mixture is cooled. Note that the acid value of the solids is preferably measured in accordance with Japanese Industrial Standard JIS K 0070.
• a solvent is added to the resulting reaction mixture to prepare an alkyd resin solution.
• the alkyd resin solution is heated while stirring, and a previously prepared mixture of polymerizable vinyl monomer and polymerization initiator is added dropwise. After the dropwise addition is complete, the polymerization initiator is further added dropwise to the reaction mixture, and the mixture is stirred and allowed to react. Furthermore, a neutralizer and solvent are added to the reaction mixture and mixed to obtain a solution containing the water-based alkyd resin.
• the water-based alkyd resin synthesized by the above procedure preferably has an acid value of 30 mg KOH/g or more and 80 mg KOH/g or less, a hydroxyl value of 50 mg KOH/g or more and 150 mg KOH/g or less, a number average molecular weight of 2,000 or more and 10,000 or less, and a weight average molecular weight of 10,000 or more and 50,000 or less.
• the solvent used in synthesizing the water-based alkyd resin is not particularly limited.
• Preferred solvents include, for example, glycol ethers such as ethylene glycol mono-n-butyl ether, diethylene glycol mono-n-butyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-butyl ether, propylene glycol mono-t-butyl ether, dipropylene glycol monomethyl ether, methyl cellosolve, ethyl cellosolve, and t-butyl cellosolve; and alcohols such as isopropyl alcohol and butyl alcohol.
• glycol ethers such as ethylene glycol mono-n-butyl ether, diethylene glycol mono-n-butyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-butyl ether, propy
• the polymerization initiator used when synthesizing the water-based alkyd resin is not particularly limited.
• Preferred polymerization initiators include, for example, dibenzoyl peroxide and 2,2'-azobisbutyronitrile.
• neutralizing agent used when synthesizing the water-based alkyd resin.
• Preferred neutralizing agents include, for example, triethylamine and diethylethanolamine.
• the coating agent for forming an etching resist according to the present invention contains 0.10 parts by mass or more and 30 parts by mass or less of a melamine resin in a solvent, calculated as solid content.
• the melamine resin is contained in the coating agent for forming an etching resist as a crosslinking agent that crosslinks the aqueous alkyd resin.
• the inclusion of the melamine resin improves adhesion between the etching resist film and the grain-oriented electrical steel sheet.
• Examples of the melamine resin that can be used include methylated melamine and butylated melamine.
• the content of melamine resin is set to 0.10 parts by mass or more and 30 parts by mass or less per 100 parts by mass of water-based alkyd resin, calculated as solids.
• the content of melamine resin is preferably 1.0 part by mass or more, and more preferably 2.0 parts by mass or more.
• the content of melamine resin is preferably 20 parts by mass or less, and more preferably 15 parts by mass or less.
• the coating agent for forming an etching resist film according to the present invention contains 50 parts by mass or more and 200 parts by mass or less of an aluminum-containing oxide in a solvent, calculated as solid content.
• the type of aluminum-containing oxide is not particularly limited, and various known oxides can be used. For example, alumina, alumina-coated silica, kaolinite, etc. are preferably used.
• the inclusion of an aluminum-containing oxide increases the thermal conductivity of the etching resist film and improves its laser removability. These aluminum-containing oxides can be used alone or in combination of two or more.
• Alumina also known as alumina sol, is not particularly limited in shape and may be, for example, granular or fibrous. From the perspective of mixability in the coating agent and the appearance of the coating, it is preferable for the size to be granular, with an average particle size of 5.0 nm or more and 100 nm or less, and for fibrous, a length of 50 nm or more and 200 nm or less.
• size of the alumina specifically refers to the stability as a paint, such as the aluminum-containing oxide not settling or deteriorating in quality when used as a coating agent for forming an etching resist film.
• Kaolinite also known as kaolin, is a hydrous silicate of aluminum and contains alumina and silica. From the perspective of coating stability, the particle size of kaolinite is preferably 1.0 ⁇ m or more and 30 ⁇ m or less.
• Alumina-coated silica is a mixture of alumina and silica.
• Alumina-coated silica has a morphology in which the alumina is unevenly distributed on the surface of the silica, making it preferable from the standpoint of the stability of the coating agent.
• the particle diameter of the alumina-coated silica is preferably 1.0 ⁇ m or more and 30 ⁇ m or less.
• the content of aluminum-containing oxide is set to 50 parts by mass or more and 200 parts by mass or less per 100 parts by mass of water-based alkyd resin, calculated as solid content.
• the content of aluminum-containing oxide is preferably 100 parts by mass or more.
• the content of aluminum-containing oxide is preferably 150 parts by mass or less.
• the coating agent for forming an etching resist film according to the present invention contains a titanium-containing oxide in a solvent in an amount of 30 parts by mass or more and 100 parts by mass or less, calculated as solid content.
• the type of titanium-containing oxide is not particularly limited, and various known titanium-containing oxides can be used. For example, titania (rutile type) and titania (anatase type) are preferably used.
• titania (rutile type) and titania (anatase type) are preferably used.
• the inclusion of a titanium-containing oxide increases the thermal conductivity of the etching resist film and improves its laser removability. These titanium-containing oxides can be used alone or in combination of two or more types.
• the solvent contains 30 parts by mass or more of titanium-containing oxide per 100 parts by mass of the solids content of the water-based alkyd resin, calculated as solids content, laser removability and resist properties are improved.
• the titanium-containing oxide is contained in an amount of 100 parts by mass or less, it becomes easier to mix the titanium-containing oxide uniformly into the coating agent, improving adhesion. Therefore, the content of titanium-containing oxide is set to 30 parts by mass or more and 100 parts by mass or less per 100 parts by mass of water-based alkyd resin, calculated as solids content.
• the content of titanium-containing oxide is preferably 40 parts by mass or more.
• the content of titanium-containing oxide is preferably 80 parts by mass or less.
• the coating agent for forming an etching resist film according to the present invention contains 0.10 parts by mass or more and 5.0 parts by mass or less of carbon black in the solvent, calculated as solid content.
• the type of carbon black is not particularly limited, and various known carbon blacks can be used.
• the solvent contains 0.10 parts by mass or more of carbon black, calculated as solid content, per 100 parts by mass of the solid content of the aqueous alkyd resin, the laser removability is improved.
• the solvent contains 5.0 parts by mass or less of carbon black, the laser removability is also improved.
• the carbon black content is set to 0.10 parts by mass or more and 5.0 parts by mass or less, calculated as solid content, per 100 parts by mass of the aqueous alkyd resin.
• the carbon black content is preferably 1.0 part by mass or more.
• the carbon black content is preferably 3.0 parts by mass or less.
• the total solid content of the aqueous alkyd resin, the melamine resin, the aluminum-containing oxide, the titanium-containing oxide, and the carbon black accounts for 80% by mass or more of the total solid content.
• total solid content refers to the total solid content of all components contained in the coating agent for forming an etching resist film.
• the effects of the present invention exhibited by the etching resist film are not impaired.
• the total solid content of the aqueous alkyd resin, the melamine resin, the aluminum-containing oxide, the titanium-containing oxide, and the carbon black, and the total solid content, and this total content may be 100% by mass or less.
• the coating agent for forming an etching resist film according to the present invention contains a water-based alkyd resin, a melamine resin, an aluminum-containing oxide, a titanium-containing oxide, and carbon black in a solvent.
• the solvent functions to uniformly dissolve the resin and uniformly mix the pigment, and also facilitates application of the coating agent for forming an etching resist film.
• the solvent preferably contains ethylene glycol mono-n-butyl ether.
• the solvent can be mixed with a hydrophilic solvent.
• hydrophilic solvents include glycol ethers such as diethylene glycol mono-n-butyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-butyl ether, propylene glycol mono-t-butyl ether, dipropylene glycol monomethyl ether, methyl cellosolve, ethyl cellosolve, and t-butyl cellosolve, as well as alcohols such as isopropyl alcohol and butyl alcohol. These solvents can be used alone or in combination of two or more.
• the solvent may be mixed with a hydrophobic solvent such as toluene or xylene. These hydrophobic solvents can be used alone or in combination of two or more.
• the proportion of solvent in the coating agent for forming an etching resist film is not particularly limited, but is preferably 20% by mass or more and 90% by mass or less. In other words, the proportion of total solids in the coating agent for forming an etching resist film is preferably 10% by mass or more and 80% by mass or less. If the amounts of solvent and total solids in the coating agent for forming an etching resist film are within the above ranges, the storage stability of the coating agent for forming an etching resist film and the workability when applying it to grain-oriented electrical steel sheet will be good.
• the coating agent for forming an etching resist film according to the present invention further contains one or more components selected from surfactants, rust inhibitors, lubricants, leveling agents, neutralizing agents, antifoaming agents, antioxidants, and coloring pigments in a solvent. These components are added to further improve the performance and uniform application of the etching resist film. These other components can be used alone or in combination of two or more. When the total amount of the solid content of these other components is 20 mass% or less of the total solid content, the performance of the etching resist film can be sufficiently maintained.
• the method for producing a coating agent for forming an etching resist film is not particularly limited, but preferably follows the procedure below. First, a portion of a solution containing an aqueous alkyd resin is placed in a reaction vessel equipped with a stirrer, thermometer, reflux condenser, etc., and an aluminum-containing oxide, a titanium-containing oxide, and carbon black, as well as a hydrophilic solvent, are added and uniformly dispersed.
• the remainder of the solution containing the aqueous alkyd resin and a melamine resin are added and dispersed to obtain a dispersion.
• a leveling agent, a neutralizing agent, an antifoaming agent, and a solvent or water are added to the obtained dispersion as necessary to obtain a coating agent for forming an etching resist film.
• the steel sheet to which the coating agent for forming an etching resist film is applied is any steel sheet that will eventually become a grain-oriented electrical steel sheet and has been hot-rolled.
• Grain-oriented electrical steel sheets are generally manufactured by the following process: a steel slab is hot-rolled to form a hot-rolled steel sheet; the hot-rolled steel sheet or the hot-rolled annealed steel sheet obtained by hot-rolling the hot-rolled steel sheet is then cold-rolled once or twice or more times with intermediate annealing between them to form a cold-rolled steel sheet; the cold-rolled steel sheet is then subjected to primary recrystallization annealing to form a primary recrystallized sheet; and the primary recrystallized sheet is then subjected to secondary recrystallization annealing to obtain a secondary recrystallized sheet.
• the thickness of the grain-oriented electrical steel sheets is preferably 0.50 mm or less, and more preferably 0.30 mm or less.
• a grain-oriented electrical steel sheet that is a finished product obtained after completing all processes up to the secondary recrystallization annealing described above.
• the other is a steel sheet that is an intermediate product during the manufacturing process of a grain-oriented electrical steel sheet.
• steel sheets to which the coating agent for forming an etching resist film is applied are collectively referred to as "steel sheets" regardless of whether they are the finished products or intermediate products described above.
• the steel sheet to be etched after applying the coating agent for forming an etching resist film may be either the finished product or the intermediate product described above.
• an intermediate product is etched to form grooves on the steel sheet surface and then further rolled, the grooves formed by the etching process may disappear.
• the etching resist film formed on the surface of the grain-oriented electrical steel sheet may be burned away or altered at the high temperatures encountered when the steel sheet is heat-treated. Therefore, when the intermediate product described above is used as the steel sheet to which the coating agent for forming an etching resist film is applied, it is preferable to apply the coating agent for forming an etching resist film, followed by baking, laser irradiation, and etching in succession, and then carry out the subsequent steps involving heat treatment. Note that this series of steps for forming grooves on the surface of the grain-oriented electrical steel sheet may be carried out once, or may be carried out two or more times.
• the coating agent for forming an etching resist film according to the present invention is uniformly applied to the surface of the steel sheet.
• the method for applying the coating agent for forming an etching resist film is not particularly limited, and it can be applied by methods such as roll coating, flow coating, knife coating, or spray coating.
• the surface to which the coating agent for forming an etching resist film is applied may be one surface of the steel material, or both surfaces of the steel material.
• the method for baking is not particularly limited, and commonly used methods such as hot air, infrared heating, and induction heating can be used.
• the baking temperature can be any temperature commonly used. It is preferable that the baking temperature be a maximum steel sheet temperature of 120°C or higher and 350°C or lower.
• maximum steel sheet temperature refers to the temperature measured on the surface of the steel sheet and the maximum temperature reached during the heat treatment process. If the maximum steel sheet temperature is 120°C or higher, the curing of the coating agent for forming the etching resist film progresses sufficiently. If the maximum steel sheet temperature is 350°C or lower, thermal decomposition of the etching resist film can be prevented. It is more preferable that the maximum steel sheet temperature be 300°C or lower.
• the baking time in the baking process i.e., the time from the start of heating until the maximum steel sheet temperature is reached, is not particularly limited, but it is preferably approximately 10 to 60 seconds.
• the deposition amount of the etching resist film per side is preferably 0.50 g/ m2 or more. By setting the deposition amount of the etching resist film to 0.50 g/ m2 or more, it is possible to provide a grain-oriented electrical steel sheet with an etching resist film that is particularly excellent in resist properties.
• the deposition amount of the etching resist film per side is more preferably 3.0 g/ m2 or more. Furthermore, the deposition amount of the etching resist film per side is preferably 20 g/ m2 or less. By setting the deposition amount of the etching resist film to 20 g/ m2 or less, it is possible to prevent deterioration of the adhesion of the film and increase in costs.
• the deposition amount of the etching resist film per side can be determined by dissolving and removing only the etching resist film from the grain-oriented electrical steel sheet with the etching resist film after baking treatment using hot alkali or the like, and measuring the change in weight of the grain-oriented electrical steel sheet before and after removal.
• the surface of the steel sheet coated with the etching resist film is irradiated with a laser while scanning the laser in a direction intersecting the rolling direction of the steel sheet.
• This laser irradiation locally heats and removes the etching resist film in the irradiated areas, resulting in the formation of film-removed areas where the surface of the steel sheet is exposed.
• the film-removed areas are selectively etched in the etching step described below, forming linear grooves in the surface of the steel sheet.
• the arrangement and dimensions of the linear grooves formed by etching affect the final magnetic properties of the grain-oriented electrical steel sheet, so the pattern of the etching resist film, i.e., the arrangement and dimensions of the film-removed areas, can be determined in consideration of the magnetic properties of the grain-oriented electrical steel sheet.
• the linear coating removal portions are arranged in a direction that intersects with the rolling direction, and the angle between the rolling direction and the direction in which the linear coating removal portions are arranged is preferably 50° or more, more preferably 60° or more, and most preferably 90°.
• the coating removal portions may be arranged in a continuous line, or discontinuously.
• the coating removal portions 4 may be arranged at equal intervals, or may not be arranged at equal intervals.
• the width of the coating removal portions may be, for example, 0.20 mm.
• the laser scanning in the laser irradiation step is preferably performed periodically in the rolling direction of the steel sheet.
• the interval between the linear coating removal portions in the rolling direction of the steel sheet is preferably 1.0 mm or more and 30 mm or less.
• the laser light source may be any laser capable of removing the etching resist coating, but from the viewpoint of output, it is preferable to use a solid-state laser such as a fiber laser or a CO2 laser.
• the laser output, irradiation energy per unit scanning length, scanning speed, beam diameter, and beam long/short axis ratio may be determined taking into consideration the shape of the coating removal portion, productivity, cost, etc.
• the steel sheet with the etching resist coating after laser irradiation is etched to form grooves on the surface of the steel sheet in the coating-removed areas.
• the etching method is not particularly limited, but can be, for example, electrolytic etching.
• electrolytic etching it is preferable to use an electrolyte such as NaCl, KCl, CaCl 2 , or NaNO 3 .
• the current density is preferably about 5 to 20 A/dm 2
• the electrolysis time is preferably about 5 to 20 seconds.
• the etching treatment conditions are preferably adjusted so that, in a cross section perpendicular to the extension direction of the groove formed by the etching treatment, the angle between the sidewall of the groove and the sheet thickness direction is within 60 degrees, and the height of the convex portion formed at the bottom of the groove is less than half the maximum depth of the groove. Adjusting the groove shape in this way introduces non-uniform strain, enhancing the effect of reducing iron loss.
• the groove depth can be, for example, 20 ⁇ m.
• the remaining processing required to convert the steel sheet into a grain-oriented electrical steel sheet is carried out appropriately depending on the processing stage of the steel sheet in the above-mentioned grain-oriented electrical steel sheet manufacturing process, thereby making it possible to manufacture grain-oriented electrical steel sheet with reduced iron loss.
• an etching resist film remains after grooves are formed by etching.
• This etching resist film may or may not be peeled off after etching. If the etching resist film is not peeled off, it can also function as an insulating tension film.
• removing the etching resist film there are no particular restrictions on the method of removal, and well-known methods can be used. For example, one method of removing the etching resist film is to immerse the grain-oriented electrical steel sheet in an alkaline solution such as an aqueous NaOH solution to soften the etching resist film, and then use a brush to wash off and remove the etching resist film.
• the water-based alkyd resin designated by symbol a1 in Table 1 was produced using the method described below. First, 75 parts by weight of linseed oil, 16 parts by weight of glycerin, 40 parts by weight of phthalic anhydride, 1 part by weight of maleic anhydride, 20 parts by weight of pentaerythritol, and 5 parts by weight of xylene were added to a reaction vessel equipped with a stirrer, thermometer, reflux condenser, dehydrator, and nitrogen gas inlet tube. The mixture was heated and stirred under a nitrogen atmosphere until the temperature reached 220°C. The reaction was continued until the acid value of the solid content of the mixture reached 8 mgKOH/g, after which it was cooled.
• the acid value of the solid content was measured in accordance with Japanese Industrial Standard JIS K 0070.
• 72 parts by mass of ethylene glycol mono-n-butyl ether was added as a solvent to the resulting reaction mixture and mixed to obtain an alkyd resin solution with an oil length of 55%, an acid value of 8 mgKOH/g, a hydroxyl value of 120 mgKOH/g, a heating residue of 65%, a number average molecular weight of 3,200, and a weight average molecular weight of 19,500.
• the starting materials listed in Table 1 were mixed according to the following procedure to prepare a coating agent for forming an etching resist film having the components and solids content shown in Table 2.
• a portion of the resin-containing solution was placed in a disperser, and aluminum-containing oxide, titanium-containing oxide, carbon black, and an organic pigment (f1 or f2) among the other components, along with 10% by mass of ethylene glycol mono-n-butyl ether as a solvent, were added and uniformly dispersed.
• a particle gauge was used to confirm that the particle diameter of components other than the resin or solvent was 10 ⁇ m or less.
• the remaining resin and melamine resin were added and dispersed to obtain a dispersion.
• a surfactant (f3 or f4) among the other components was added to the resulting dispersion.
• triethylamine was added as a neutralizing agent, and ethylene glycol mono-n-butyl ether was added as a solvent to adjust the pH of the coating agent for forming an etching resist film to 9.0 and the solids content to 63% by mass.
• Table 2 shows the components and solids-equivalent content of the 33 different coating materials for forming etching resist films obtained, each with a different component composition.
• the content of each component shown in Table 2, expressed in mass %, is the proportion of the solids of each component to the total solids. Furthermore, the content expressed in parts by mass is the parts by mass of other components based on 100 parts by mass of resin (symbol a1, a2, or a3).
• resin symbol a1, a2, or a3
• ⁇ Adhesion amount> The amount of the etching resist film deposited after baking was measured by a gravimetric method. Specifically, the etching resist film alone was dissolved and removed from the test material using a heated potassium hydroxide solution, and the change in weight of the steel sheet before and after dissolution and removal was measured. The amount of deposition was calculated by dividing the measured weight change by the area of one side of the test material.
• ⁇ Adhesion> The test material was cut to a width of 30 mm and a length of 50 mm, and a piece of cellophane adhesive tape 24 mm wide and 50 mm long was attached to the surface of the cut test material on which the etching resist film was formed (the test surface). Next, the test material was bent 180° using a 5 mm diameter round rod with the test surface as the compression side, and the cellophane adhesive tape was peeled off. The area ratio of the etching resist film that had adhered to the cellophane adhesive tape and peeled off was calculated, and the adhesion was evaluated according to the following criteria. A rating of A or B was considered a pass, and an F was considered a fail. (Evaluation criteria) A: The area ratio is 5.0% or less. B: The area ratio is greater than 5.0% and less than 10%. F: The area ratio is greater than 10%.
• ⁇ Scratch resistance> Two test pieces of each type were prepared by cutting the test material into pieces 100 mm wide and 200 mm long. For each of the two test pieces, the test surfaces on which the etching resist film was formed were placed one on top of the other, and the test pieces were slid in the longitudinal direction at a relative speed of 2 cm/s for 10 seconds while applying a pressure of 196 kPa (2 kgf/ cm2 ) in the normal direction of the test surfaces. Next, scratches on the surface of the test surface were visually observed to calculate the scratch occurrence area ratio, and the scratch resistance was evaluated according to the following criteria. A rating of A, B, or C was considered a pass, and F was considered a fail. (Evaluation criteria) A: Almost no scratches are observed. B: A few scratches are observed. C: Scratches are clearly observed. F: Scratches are observed to the extent that the base metal is exposed.
• the laser removability of the etching resist film was evaluated as follows. First, a steel sheet with an etching resist film was irradiated with a laser. The output of the light source used for laser irradiation was 2.0 kW, the beam diameter was 50 ⁇ m, and the long/short axis ratio of the beam was 1.02. The scanning speed was 10 m/s. The laser irradiation conditions were set with the goal of achieving a width of approximately 40 ⁇ m in the film-removed area. Next, the width of the film-removed area after laser irradiation was measured using an optical microscope and evaluated according to the following criteria. A rating of A or B was considered acceptable, and an F was considered unacceptable.
• the test material was cut into a size of 30 mm wide and 250 mm long and subjected to electrolytic etching. The appearance of the surface of the etched resist film after electrolytic etching was visually observed, and the area ratio of the part where discoloration was observed was calculated to evaluate the resist properties.
• a 20% aqueous NaCl solution was used as the electrolytic solution for electrolytic etching.
• the electrolytic etching conditions were an electrolytic solution temperature of 25°C, a current density of 8 A/ dm2 , and a current application time of 3 min.
• the resist properties were evaluated according to the following criteria. A rating of A or B was considered to be pass, and an F was considered to be fail. (Evaluation criteria)
• F The area ratio of the discolored area is greater than 5.0%.
• ⁇ Removability> The test material for which the resist properties were evaluated was immersed in a 25% aqueous sodium hydroxide solution at 50°C for 10 seconds, then removed and washed with water to remove the etching resist film. The test surface of the test material after the etching resist film had been removed was visually observed, and the area ratio of the part where the etching resist film had peeled off was calculated to evaluate the removability.
• the removability was evaluated according to the following criteria. A rating of A or B was considered to be pass, and F was considered to be fail. (Evaluation criteria) A: The area ratio of the peeled portion is 100%. B: The area ratio of the peeled portion is 90% or more but less than 100%. F: The area ratio of the peeled portion is less than 90%.
• the etching resist films formed using the coating agent for forming an etching resist film according to the present invention passed the characteristic evaluation results for all evaluation items.
• test materials No. 24 to 32 in which the content of the coating agent for forming an etching resist film, converted into solids, did not satisfy the numerical range of content specified in the present invention, and test material No. 33, which used a water-based epoxy resin as the resin, failed the characteristic evaluation results for one of the evaluation items.

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