JP2010275410A - Hydrophilic resin composition, water-based coating composition, and method for forming film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrophilic resin composition which can form a film having minute and good physical properties on a surface to be coated without deteriorating the safety or hygiene aspect of a working environment and with a low energy loss in a film formation process; to provide a water-based coating composition; and to provide a method for forming a film. <P>SOLUTION: The hydrophilic resin composition includes (A) a Diels-Alder reaction product of maleic anhydride and unsaturated fatty acid, (B) a basic compound, and (C) an inorganic filler, the water-based coating composition contains this hydrophilic resin composition, and the method for forming a film employs this water-based coating composition. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a hydrophilic resin composition, an aqueous coating composition, and a coating film forming method using the same.

  As steel core materials such as motors, transformers, and reactors, silicon steel plates having excellent magnetic properties are widely used. A coating film for insulation is formed on the surface of the silicon steel sheet. Conventionally, a composition containing an organic solvent based on a thermosetting resin has been used for forming the coating film. This is because a coating film excellent in coating film hardness, weather resistance, impact resistance, corrosion resistance, water resistance and the like is formed.

  However, in such an organic solvent type resin composition, since many organic solvents are scattered and evaporated in the coating process and the curing and drying process, the working environment has been severely restricted from the viewpoint of safety and hygiene.

  Therefore, the use of a solventless resin composition that does not use an organic solvent or an aqueous resin composition that uses an aqueous resin has been studied. For example, as a solventless resin composition, a polyester resin diluted with a reactive diluent or the like to lower the viscosity is known (for example, see Patent Document 1). However, since this solventless resin composition contains a highly volatile component such as a reactive diluent even in the absence of a solvent, an explosion-proof measure against such a volatile component is applied in the coating process and the curing and drying process. In addition, there is a problem that the volatile component itself deteriorates the working environment.

  On the other hand, the water-based resin composition does not have the safety and health problems of the solvent type and the solventless type. However, there is a problem that a coating film having sufficient physical properties cannot be obtained and the latent heat of vaporization of water as a solvent is large, resulting in enormous energy loss in the curing and drying process.

  On the other hand, the use of a powder coating material that does not use any solvent, reactive diluent, or the like has been studied (for example, see Patent Document 2). Since no solvent or reactive diluent is used, there is no such problem. However, there is a problem in that it is difficult to form a coating film that has poor coating film forming ability and can sufficiently protect the surface to be coated, and it is necessary to introduce a new facility called an electrostatic powder coating apparatus. .

JP 2008-266383 A Japanese Patent Laid-Open No. 11-80659

  The present invention has been made to solve the above-described problems of the prior art, and does not impair the safety and hygiene of the work environment, and has little energy loss in the coating film forming process, and the surface to be coated. An object of the present invention is to provide a hydrophilic resin composition, an aqueous coating composition, and a method for forming a coating film that can form a coating film having dense and good physical properties.

  A hydrophilic resin composition according to one embodiment of the present invention is characterized by containing (A) a Diels-Alder reaction product of maleic anhydride and an unsaturated fatty acid, (B) a basic compound, and (C) an inorganic filler. Yes.

  Moreover, the aqueous coating composition which concerns on the other aspect of this invention is characterized by containing the said hydrophilic resin composition.

  Furthermore, a coating film forming method according to still another aspect of the present invention is characterized in that the aqueous coating composition is applied.

  According to the present invention, the safety and hygiene aspects of the work environment are not impaired, the energy loss in the coating film forming process is small, and the coating film having dense and good physical properties on the surface to be coated is formed. A hydrophilic resin composition, an aqueous coating composition, and a method for forming a coating film can be provided.

Embodiments of the present invention will be described below.
The hydrophilic resin composition of the present invention contains (A) a Diels-Alder reaction product of maleic anhydride and an unsaturated fatty acid, (B) a basic compound, and (C) an inorganic filler.

  The unsaturated fatty acid in the component (A) is a monobasic unsaturated fatty acid obtained from fats and oils such as soybean oil fatty acid, linseed oil fatty acid, coconut oil fatty acid, tall oil fatty acid, rice bran oil fatty acid, corn oil fatty acid. , Sunflower oil fatty acid, safflower oil fatty acid, olive oil fatty acid, rapeseed oil fatty acid, sesame oil fatty acid, poppy oil fatty acid, eno oil fatty acid, hemp seed oil fatty acid, grape kernel oil fatty acid, cottonseed oil fatty acid, walnut oil fatty acid, rubber seed oil fatty acid, fish oil Examples include fatty acids, dehydrated castor oil fatty acids, and mixtures thereof. These may be used alone or in combination of two or more. Among these, soybean oil fatty acid and linseed oil fatty acid are preferable from the viewpoint of reactivity.

  The Diels-Alder reaction between these unsaturated fatty acids and maleic anhydride can be performed by a known method. For example, the reaction is carried out at a reaction temperature of 150 to 260 ° C. and a reaction time of 1 to 4 hours. Maleic anhydride and unsaturated fatty acid have a range in which the number of moles of maleic anhydride is 1 to 3 times the number of moles of unsaturated fatty acid, that is, the molar ratio of maleic anhydride to unsaturated fatty acid is 1: 1 to 3: It is preferable to make it react in the ratio which becomes in the range of 1. If the proportion of maleic anhydride is less than the above range, solubility in water and the like will decrease. On the contrary, when the reaction amount of maleic anhydride is larger than the above range, the physical properties of the coating film, for example, the dielectric breakdown voltage is lowered. More preferably, the maleic anhydride and the unsaturated fatty acid are reacted at a ratio such that the molar ratio is in the range of 1: 1 to 2: 1.

  The basic compound (B) includes tertiary amines such as triethanolamine, triethylamine, N, N-dimethylaminoethanol, secondary amines such as diethanolamine, and secondary amines such as 2-amino-2-methylpropanol. A primary amine, ammonia, etc. are mentioned. These may be used alone or in combination of two or more. Among these, triethanolamine is preferable from the viewpoint of odor.

  The basic compound of the component (B) is preferably blended in an amount of 2 to 12% by mass with respect to the entire aqueous resin composition, and more preferably in the range of 5 to 10% by mass. If the compounding amount of the basic compound is less than 2% by mass of the entire aqueous resin composition, the solubility in water is reduced. Conversely, if it exceeds 12% by mass, the physical properties of the coating film such as dielectric breakdown voltage are reduced. descend.

  The inorganic filler (C) is a component that is blended mainly as a thixotropic agent for maintaining the coating thickness and leveling the coating. For example, talc, silica, alumina, aluminum hydroxide, magnesia, water Powders such as magnesium oxide, titania, aluminum nitride, boron nitride, barium sulfate are used. These may be used alone or in combination of two or more. Among these, talc and silica are preferable, and talc is particularly preferable from the viewpoint of leveling properties, coating film physical properties (electrical insulating properties, etc.), price, and the like.

  It is preferable to mix | blend 15-40 mass% of this inorganic filler of (C) component with respect to the whole aqueous resin composition, and it is more preferable in it being the range of 20-35 mass%. If the blending amount of the inorganic filler is less than 15% by mass of the entire aqueous resin composition, it becomes difficult to form a sufficiently thick coating film, and the leveling property of the coating film also decreases. On the other hand, if it exceeds 40% by mass, the sedimentation property may be lowered.

  In the hydrophilic resin composition of the present invention, (D) an aqueous resin can be blended for the purpose of improving the drying property. Examples of the aqueous resin include water-soluble resins such as a water-soluble phenol resin, a water-soluble acrylic resin, and a water-soluble epoxy resin. An aqueous resin dispersion in which a resin such as melamine resin is dispersed in an aqueous medium can also be used. As the (D) aqueous resin, a water-soluble phenol resin is preferable from the viewpoint of electrical insulation of the coating film.

  The water-soluble resin as the component (D) is preferably blended in an amount of 2 to 12% by mass with respect to the entire aqueous resin composition, and more preferably in the range of 5 to 10% by mass. If the blending amount of the water-soluble resin is less than 2% by mass of the entire aqueous resin composition, the above-mentioned effects due to the addition cannot be sufficiently obtained. Conversely, if it exceeds 12% by mass, the dielectric breakdown voltage may be lowered. There is.

  If necessary, the hydrophilic resin composition of the present invention may further contain an antifoaming agent, a leveling agent, an anti-settling agent, an antistatic agent, a dispersant, a curing catalyst, a thickening agent, a film-forming aid, and the like. An agent can be mix | blended in the range which does not inhibit the effect of this invention.

  The water-based coating composition of the present invention is prepared by adding water to the above hydrophilic resin composition as necessary to obtain an appropriate viscosity. The aqueous coating composition of the present invention preferably has a viscosity measured at 25 ° C. in accordance with JIS C 2105 of 1 to 10 dPa · s, more preferably 2 to 5 dPa · s. By setting the viscosity to 1 dPa · s or more, a certain amount of coating thickness can be secured, and by setting the viscosity to 10 dPa · s or less, poor surface smoothness of the coating can be suppressed. .

  The aqueous coating composition of the present invention is applied to a surface to be coated such as a steel plate and dried and cured. As a coating method, a conventionally known method such as a roll coater method, a knife coater method, a brush coating method, an air spray method, an airless spray method, an electrostatic coating method, or the like can be used. Further, the drying method is preferably heat drying, and for example, it can be cured by heating at a temperature of 170 ° C. for 0.5 to 1 hour.

  The coating film formed from the aqueous coating composition of the present invention has a sufficient film thickness and excellent coating film properties. Moreover, the curing conditions of the coating film are relatively relaxed and can be cured with less energy consumption.

  The water-based coating composition of the present invention is suitable for metal insulation in electrical and electronic parts of industrial equipment such as automobiles, vehicles and electrical equipment, for example, electrical insulation and rust prevention applications such as slot cores of motors. It is suitable for coating a molded product made of these silicon steel plates.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples at all. In the following description, “part” means “part by mass”.

Example 1
To the flask, 3 parts of maleic anhydride and 10 parts of linseed oil fatty acid (trade name TOENOL #LOFA, manufactured by Toei Chemical Co., Ltd.) were added, reacted at 240 ° C. for 4 hours, and then cooled to a temperature of 100 ° C. or lower. To this reaction product, 7 parts of triethanolamine, 7 parts of a water-soluble phenol resin (trade name BRL-204 manufactured by Showa Polymer Co., Ltd .; indicated as water-soluble phenol resin (I)) and 46 parts of pure water were added and mixed. Furthermore, talc (trade name talc SSS manufactured by Nippon Talc Co., Ltd .; particle size D ₅₀ (laser diffraction method) 12 μm, specific surface area 4.5 m ² / g, oil absorption 28 ml / 100 g) is added and mixed, and is aqueous. A coating composition was produced.

  Next, the aqueous coating composition was applied to a silicon steel plate to a thickness of 20 μm using a hand coater, and heated and cured at 170 ° C. for 0.5 hours to form a coating film having a thickness of 15 μm.

(Example 2)
An aqueous coating composition was produced in the same manner as in Example 1 except that soybean oil fatty acid (trade name TOENOL # 1125 manufactured by Toei Chemical Co., Ltd.) was used instead of linseed oil fatty acid.

  Next, the water-based coating composition was coated on a silicon steel plate to a thickness of 20 μm using a hand coater, heated at 170 ° C. for 1 hour and cured to form a coating film having a thickness of 15 μm.

(Example 3)
Example 1 except that instead of the water-soluble phenol resin (BRL-204), a water-soluble phenol resin (trade name BRL-1583 manufactured by Showa Polymer Co., Ltd .; expressed as water-soluble phenol resin (II)) was used. In the same manner, an aqueous coating composition was produced.

  Next, the water-based coating composition was coated on a silicon steel plate to a thickness of 20 μm using a hand coater, heated at 170 ° C. for 1 hour and cured to form a coating film having a thickness of 15 μm.

Example 4
An aqueous coating composition was produced in the same manner as in Example 1 except that crystalline silica (trade name: Crystallite AA; particle size D ₅₀ (laser diffraction method) 6 μm, manufactured by Tatsumori) was used instead of talc. did.

  Next, the water-based coating composition was coated on a silicon steel plate to a thickness of 20 μm using a hand coater, heated at 170 ° C. for 1 hour and cured to form a coating film having a thickness of 15 μm.

(Example 5)
An aqueous coating composition was produced in the same manner as in Example 1 except that ammonia water (25%) was used instead of triethanolamine.

  Next, the water-based coating composition was coated on a silicon steel plate to a thickness of 20 μm using a hand coater, heated at 170 ° C. for 1 hour and cured to form a coating film having a thickness of 15 μm.

(Comparative Example 1)
To the flask, 20 parts of an acrylic acid-based water-soluble polymer (trade name Aquaric (registered trademark) L, manufactured by Nippon Shokubai Co., Ltd.), 7 parts of triethanolamine and 46 parts of pure water are added and mixed. Further, talc (talc SSS) was added and mixed to produce an aqueous coating composition.

  Next, the aqueous coating composition was applied to a silicon steel plate to a thickness of 20 μm using a hand coater, and heated and cured at 170 ° C. for 0.5 hours to form a coating film having a thickness of 15 μm.

(Comparative Example 2)
An aqueous coating composition was produced in the same manner as in Example 1 except that tetrahydrophthalic anhydride was used in place of maleic anhydride.

  Next, the water-based coating composition was coated on a silicon steel plate to a thickness of 20 μm using a hand coater, heated at 170 ° C. for 1 hour and cured to form a coating film having a thickness of 15 μm.

(Comparative Example 3)
To the flask, 6 parts of maleic anhydride and 20 parts of linseed oil fatty acid (TOENOL #LOFA) were added, reacted at 240 ° C. for 4 hours, and then cooled to a temperature of 100 ° C. or lower. To this reaction product, 14 parts of triethanolamine, 14 parts of a water-soluble phenol resin (BRL-204) and 46 parts of pure water were added and mixed to prepare an aqueous coating composition.

  Next, the above-mentioned aqueous coating composition was applied to a silicon steel plate to a thickness of 20 μm using a hand coater, and heated and cured at 170 ° C. for 0.5 hours to form a coating film having a thickness of 15 μm.

  Various characteristics of the water-based coating compositions and cured products (coating films) obtained in the above Examples and Comparative Examples were evaluated by the methods described below. The results are shown in Table 1 together with the blending amounts of the respective components of the aqueous coating composition.

[viscosity]
The viscosity of the water-based coating composition was measured at 25 ° C. using a B-type viscometer in accordance with JIS C 2103 (an electrical insulating varnish test method).
[Drying time]
The drying time of the aqueous coating composition was measured according to JIS C2103.
[Sedimentation]
20 g of the aqueous coating composition was put in a test tube and allowed to stand at 25 ° C., and the number of days until a precipitate was visually observed on the bottom of the test tube was examined.

[Dielectric breakdown voltage]
The dielectric breakdown voltage of the aqueous coating composition was measured according to JIS C2103.
[Appearance of coating film]
Evaluation was made in accordance with JIS C 2103 coating method.
[Corrosion resistance]
The silicon steel plate on which the coating film was formed was treated at 80 ° C. and 85% RH for 500 hours, and then the steel plate surface was visually observed. The evaluation was made based on the presence or absence of thread-like corrosion. The case where no thread-like corrosion was observed was judged as “good”, and the case where thread-like corrosion was found was judged as “bad”. In addition, thread-like corrosion means the corrosion which advances to a to-be-coated object surface in a thread form.

  As is apparent from Table 1, the aqueous coating composition according to the examples of the present invention has good paintability, a short drying time, and excellent workability. In particular, in Examples 1 to 3 and 5 using talc as the inorganic filler, sedimentation is also effectively suppressed. The coating film also has a good appearance, is excellent in insulation and corrosion resistance, and has been confirmed to function sufficiently as a coating film for silicon steel sheets.

  On the other hand, Comparative Example 1 using an acrylic acid-based water-soluble polymer has poor workability because of its high viscosity, and in Comparative Example 2 using tetrahydrophthalic anhydride instead of maleic anhydride, filamentous corrosion occurs. Further, in Comparative Example 3 in which the inorganic filler was not blended, the coating film appearance, insulation, and corrosion resistance were all poor.

Claims (10)

  (A) A hydrophilic resin composition comprising a Diels-Alder reaction product of maleic anhydride and an unsaturated fatty acid, (B) a basic compound, and (C) an inorganic filler.   (D) The hydrophilic resin composition according to claim 1, further comprising an aqueous resin.   The hydrophilic resin composition according to claim 2, wherein the (D) aqueous resin is a water-soluble phenol resin.   The component (A) is obtained by reacting maleic anhydride and an unsaturated fatty acid in a molar ratio of 1: 1 to 3: 1. A hydrophilic resin composition.   The hydrophilic resin composition according to any one of claims 1 to 4, wherein the unsaturated fatty acid in the component (A) is linseed oil fatty acid and / or soybean oil fatty acid.   The hydrophilic resin composition according to claim 1, wherein the (C) inorganic filler is talc and / or silica. The hydrophilic resin composition according to claim 1, wherein the basic compound (B) is triethanolamine.
It is obtained   An aqueous coating composition comprising the hydrophilic resin composition according to any one of claims 1 to 7.   The water-based coating composition according to claim 8, which is used for a silicon steel sheet.   A method for forming a coating film, which comprises applying the water-based coating composition according to claim 8 or 9.