JP2010111844A - Water-based heat-resistant resin composition, coating using the water-based heat-resistant resin composition, electric appliance and kitchen appliance using the coating - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-based heat-resistant resin composition for electric appliances and kitchen appliances, forming a coating film excellent in adhesion to a ceramic substrate or an aluminum substrate even after high-temperature baking and excellent in hardness, a coating comprising the water-based heat-resistant resin composition as a coating film component, or to provide electric appliances or kitchen appliances using the coating to form the coating film. <P>SOLUTION: The water-based heat-resistant resin composition including (A) a polyamideimide resin having a number-average molecular weight of 20,000-30,000, (B) an alkyl amine, (C) water, and (D) an organic solvent, the coating containing the water-based heat-resistant resin composition as the coating film component, and the electric appliances and the kitchen appliances using the coating to form the coating film are provided. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a water-based heat-resistant resin composition, a paint using the water-based heat-resistant resin composition, a home appliance and a kitchen appliance using the paint.

  In recent years, water-based resin solutions that use water as a medium instead of organic solvents have attracted attention in terms of environmental conservation, safety and health, economy, and painting workability. Carboxyl groups remaining at the end of the resin and basic compounds A water-solubilizing method of a polyamideimide resin that causes the above to act is reported (see, for example, Patent Document 1) and applied to various uses.

This water-soluble polyamideimide resin can be diluted to an arbitrary concentration with water, has excellent mixing properties with an aqueous fluororesin dispersion, and the coating film has excellent heat resistance and hardness. It is useful as a fluororesin binder in paints for home appliances or kitchen appliances, and has great demand.
This paint for home appliances or kitchen appliances has a paint composition of a mixed system of a fluororesin that exhibits non-adhesiveness and a polyamide-imide resin that exhibits adhesion to a base material. In order to orient the film on the surface of the coating film, high-temperature baking at around 400 ° C. at which the fluororesin melts is required.

Japanese Patent No. 3491624

  However, the coating film obtained from the conventional water-soluble polyamide-imide resin has a good adhesion to the coating material after baking at high temperature and the hardness of the coating film itself when the ceramic substrate or aluminum substrate is used as the coating material. There was a problem of being inferior.

  An object of the present invention is to provide a water-based heat-resistant resin composition capable of forming a coating film having excellent adhesion to a ceramic base material and an aluminum base material and having excellent hardness even after high-temperature firing, and this water-based heat-resistant resin composition It is providing the coating material which uses a thing as a coating-film component, and the household appliances or kitchen appliance which formed the coating film using this coating material.

As a result of studying a water-based heat-resistant resin composition that can form a coating film having excellent adhesion to a ceramic base material or an aluminum base material even after high-temperature firing and excellent in hardness, Compared with the coating film obtained from the conventional water-based polyamideimide resin by using an alkylamine as the basic compound and giving the appropriate molecular weight to the polyamideimide resin, after high temperature firing In addition, the present inventors have found that it is possible to greatly improve the adhesion to a pottery base material or an aluminum base material and to improve the hardness.
That is, the means for solving the above problems are as follows.

(1) An aqueous heat-resistant resin comprising (A) a polyamideimide resin having a number average molecular weight of 20000 to 30000, (B) an alkylamine, (C) water, and (D) an organic solvent. Composition.

(2) The blending amount of (B) alkylamine is 2.5 to 5 equivalents with respect to the acid value of the combined carboxyl group and ring-opened acid anhydride group contained in (A) polyamideimide resin. The water-based heat-resistant resin composition according to (1) above.

(3) Water system as described in said (1) or (2) whose content of (C) water is 30-80 mass% with respect to the total mass of (C) water and (D) organic solvent. Heat resistant resin composition.

(4) Any of (1) to (3) above, wherein the content of (D) the organic solvent is 20 to 70% by mass relative to the total mass of (C) water and (D) the organic solvent. The water-based heat resistant resin composition described in 1.

(5) (A) Polyamideimide resin is obtained by copolymerizing a diisocyanate compound or diamine compound as an amine component and a tribasic acid anhydride or tribasic acid chloride as an acid component in a polar solvent. The water-based heat-resistant resin composition according to any one of (1) to (4), which is a polyamideimide resin.

(6) The aqueous system according to any one of (1) to (5), wherein the acid value of the (A) polyamideimide resin, which is a combination of the carboxyl group and the ring-opened acid anhydride group, is 25 to 50 mgKOH / g. Heat resistant resin composition.

(7) A paint comprising the aqueous heat-resistant resin composition according to any one of (1) to (6) as a coating film component.

(8) A paint obtained by mixing a fluororesin with the paint according to (7).

(9) A home electric appliance in which a coating film is formed using the paint according to (8).

(10) A kitchen appliance in which a coating film is formed using the paint according to (8).

  According to the present invention, compared with a coating film obtained from a conventional water-based heat-resistant resin composition, the adhesion to a ceramic base material or an aluminum base material is greatly improved even after high-temperature firing, and the hardness is also high. Water-based heat-resistant resin composition capable of obtaining an improved coating film, paint having the water-based heat-resistant resin composition as a coating film component, and home appliance or kitchen having a coating film formed using the paint An instrument can be provided.

<Water-based heat-resistant resin composition>
The aqueous heat-resistant resin composition of the present invention contains (A) a polyamideimide resin having a number average molecular weight of 20000 to 30000, (B) an alkylamine, (C) water, and (D) an organic solvent. It is characterized by.
By setting it as such a composition, it becomes possible to form the coating film which is excellent in the adhesiveness to a ceramic base material or an aluminum base material, and excellent in hardness, even after high temperature baking.
Below, each component of the water-system heat resistant resin composition of this invention is demonstrated one by one.

[(A) Polyamideimide resin]
The (A) polyamideimide resin used in the present invention is obtained, for example, by copolymerizing a diisocyanate compound or diamine compound as an amine component and a tribasic acid anhydride or tribasic acid chloride as an acid component. Is preferred. The typical compounds used in the above production method are listed below.

First, as the diisocyanate compound, 4,4′-diphenylmethane diisocyanate, xylylene diisocyanate, 3,3′-diphenylmethane diisocyanate, 3,3′-dimethoxybiphenyl-4,4′-diisocyanate, paraphenylene diisocyanate, hexamethylene diisocyanate, Examples include tolylene diisocyanate, naphthalene diisocyanate, and tolylene diisocyanate. From the viewpoint of reactivity, it is preferable to use 4,4′-diphenylmethane diisocyanate.
Examples of the diamine compound include 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylsulfone, 3,3′-diaminodiphenylsulfone, xylylenediamine, and phenylenediamine. It is done.

  Examples of the tribasic acid anhydride include trimellitic acid anhydride, and examples of the tribasic acid anhydride chloride include trimellitic acid anhydride chloride. From the viewpoint of environmental burden, it is preferable to use trimellitic anhydride or the like.

  When synthesizing the polyamideimide resin, dicarboxylic acid, tetracarboxylic dianhydride and the like can be reacted at the same time as long as the properties of the polyamideimide resin are not impaired.

  Examples of the dicarboxylic acid include terephthalic acid, isophthalic acid, and adipic acid. Examples of the tetracarboxylic dianhydride include pyromellitic dianhydride, benzophenone tetracarboxylic dianhydride, and biphenyltetracarboxylic dianhydride. Is mentioned.

The amount of diisocyanate compound or diamine compound, tribasic acid anhydride or tribasic acid anhydride chloride, and the amount of dicarboxylic acid and tetracarboxylic dianhydride used as required is the molecular weight of the polyamideimide resin produced, From the viewpoint of the degree of cross-linking, the diisocyanate compound or diamine compound is preferably 0.8 to 1.1 mol, and preferably 0.95 to 1.08 mol, relative to a total amount of 1.0 mol of the acid component. More preferably, 1.0 to 1.08 mol is particularly preferable.
In the acid component, dicarboxylic acid and tetracarboxylic dianhydride are preferably used in a total amount of 0 to 50 mol% from the viewpoint of maintaining the properties of the polyamideimide resin.

Examples of the solvent used for the polymerization of the (A) polyamideimide resin used in the present invention include polar solvents, and N-methyl-2-pyrrolidone, γ-butyrolactone, dimethylacetamide, dimethylformamide, and the like can be used. In order to perform the amidimidization reaction at a high temperature in a short time, it is preferable to use a high boiling point solvent such as N-methyl-2-pyrrolidone.
Moreover, there is no restriction | limiting in particular in the usage-amount of a solvent, However, It is set as 50-500 mass parts with respect to 100 mass parts of total amounts of an isocyanate component or an amine component, and an acid component. It is preferable from the viewpoint.
The conditions for synthesizing the polyamide-imide resin are various and cannot be specified in general. Usually, the reaction is performed at a temperature of 80 to 180 ° C., and in an atmosphere of nitrogen or the like in order to reduce the influence of moisture in the air. preferable.

  The (A) polyamideimide resin synthesized by the above method is obtained, for example, as a polyamideimide resin solution dissolved in the solvent. (A) When the polyamideimide resin is used in the aqueous heat-resistant resin composition of the present invention, it can be used in the state of the polyamideimide resin solution.

  The (A) polyamideimide resin used in the present invention has a number average molecular weight of 20,000 to 30,000. When the number average molecular weight is less than 20000, various properties such as hardness and heat resistance of the coating film tend to be reduced after high-temperature baking, and when the number average molecular weight exceeds 30000, the solubility in water decreases and the substrate Adhesion with the resin also decreases. From these viewpoints, the number average molecular weight of the polyamideimide resin is particularly preferably 22000 to 27000, and more preferably 24000 to 26000.

  The number average molecular weight of the (A) polyamideimide resin is sampled at the time of resin synthesis, measured by gel permeation chromatography (GPC) using a standard polystyrene calibration curve, and synthesized until the target number average molecular weight is reached. By continuing the above, it is possible to manage within the above range.

  The (A) polyamideimide resin used in the present invention preferably has an acid value of 25 to 50 mgKOH / g, which is a combination of a carboxyl group and a ring-opened acid anhydride group. When the acid value is 25 mgKOH / g or more, the carboxyl group that reacts with the basic compound becomes sufficient, water-solubilization becomes easy, and the adhesion to a ceramic substrate or an aluminum substrate after high-temperature baking tends to be improved. It is in. Further, when the acid value is 50 mgKOH / g or less, the finally obtained water-based heat-resistant resin composition becomes difficult to gel with the passage of time. From these viewpoints, the acid value obtained by combining the carboxyl group and the ring-opened acid anhydride group is particularly preferably 32 to 42 mgKOH / g.

  In addition, the acid value which combined the carboxyl group of the (A) polyamideimide resin and the ring-opened acid anhydride group can be obtained by the following method. First, (A) 0.5 g of polyamide-imide resin is taken, 0.15 g of 1,4-diazabicyclo [2,2,2] octane is added thereto, and 60 g of N-methyl-2-pyrrolidone and ion exchange are added. Add 1 ml of water and stir until the (A) polyamideimide resin is completely dissolved. This was titrated with a potentiometric titrator using a 0.05 mol / l ethanolic potassium hydroxide solution to obtain an acid value combining the carboxyl group and the ring-opened acid anhydride group of the polyamide-imide resin. .

[(B) Alkylamine]
The water-based heat-resistant resin composition of the present invention contains (B) an alkylamine, and this (B) alkylamine component becomes a basic compound used for water-solubilization of the (A) polyamideimide resin. . Examples of (B) alkylamine include triethylamine, tripropylamine, tributylamine, N, N-dimethylcyclohexylamine, N, N-dimethylbenzylamine, triethylenediamine, N, N, N ′, N′-tetramethyl. Ethylenediamine, N, N, N ′, N ″, N ″ -pentamethyldiethylenetriamine, N, N ′, N′-trimethylaminoethylpiperazine, diethylamine, diisopropylamine, dibutylamine, ethylamine, isopropylamine, butylamine, etc. Among them, tertiary amines such as triethylamine and tributylamine are preferable.
In addition, in combination with alkylamine, N-methylmorpholine, monoethanolamine, diethanolamine, triethanolamine, dipropanolamine, tripropanolamine, N-ethylethanolamine, N, N-dimethylethanolamine, cyclohexanol It is possible to use amines having polar groups, such as amines, N-methylcyclohexanolamines, and N-benzylethanolamines. In addition to the above basic compound, for example, a caustic alkali such as sodium hydroxide or potassium hydroxide or aqueous ammonia may be used in combination.

  In addition, (B) alkylamine is preferably used in an amount of 2.5 to 5 equivalents relative to the acid value of the combined carboxyl group and ring-opened acid anhydride group contained in (A) polyamideimide resin. If it is 2.5 equivalents or more, water-solubilization of the resin is facilitated, and if it is 5 equivalents or less, adhesion to a ceramic substrate or aluminum substrate after high-temperature firing and hardness tend to be improved. From these viewpoints, it is particularly preferable that the acid value is 3.5 to 4.5 equivalents based on the combined acid value of the carboxyl group and the ring-opened acid anhydride group.

  (B) Alkylamine forms a salt with a carboxyl group at the end of (A) polyamideimide resin to become a hydrophilic group. As a method for forming a salt, (A) a polyamideimide resin component, (B) an alkylamine component, and (C) water described later may be mixed at 10 ° C. to 150 ° C., or (A) polyamide After mixing the imide resin component and the (B) alkylamine component, water (C) described later may be added at the above temperature. As for the temperature which forms a salt, 30 to 100 degreeC is more preferable.

[(C) Water]
The aqueous heat-resistant resin composition of the present invention contains (C) water, and (C) water is preferably ion-exchanged water. The blending amount of the (C) water component is preferably 30 to 80% by mass with respect to the total mass of the (C) water component and the (D) organic solvent component described later. If the blending amount is 30% by mass or more, water content is sufficient because the contained water is sufficient, and if it is 80% by mass or less, gelation or turbidity tends not to occur. From these viewpoints, 40 to 70% by mass is particularly preferable.

[(D) Organic solvent]
The aqueous heat-resistant resin composition of the present invention contains (D) an organic solvent in addition to (A) the polyamideimide resin, (B) alkylamine and (C) water. (D) Although there is no restriction | limiting in particular as an organic solvent, For example, a dimethylformamide, a dimethylacetamide, a dimethylsulfoxide, (gamma) -butyrolactone, N-methyl-2-pyrrolidone etc. are mentioned. (A) When the polyamideimide resin is dissolved in a solvent and used as a polyamideimide resin solution, the same organic solvent can be used as the (D) organic solvent. (D) As a compounding quantity of the organic solvent, it is preferable that it is 20-70 mass% with respect to the total mass of (C) water component and (D) organic solvent component.

<Paint>
The coating material of the present invention is characterized by containing the water-based heat-resistant resin composition of the present invention described above as a coating film component.
As described above, the water-based heat-resistant resin composition of the present invention can form a coating film having excellent adhesion and hardness to a ceramic base material and an aluminum base material even after high-temperature firing. By using a water-based heat-resistant resin composition as a coating film component, a coating material that can form a coating film having excellent adhesion and hardness can be obtained.

In addition, the water-based heat-resistant resin composition of the present invention is excellent in miscibility with the fluororesin aqueous dispersion, heat resistance and hardness of the coating film, and as a binder for fluororesins in paints for household appliances or kitchen appliances. It is suitable, used as a paint mixed with a fluororesin, and used for forming a coating film on household appliances or kitchen appliances. The formed coating film is excellent in adhesion with the surface to be coated, and the coating film itself has high hardness.
The paint of the present invention can be suitably used as an electric home appliance, particularly for an IH heater. Moreover, it can be used conveniently as a kitchen appliance for an enamel pan, a frying pan, etc.

The properties required for the fluororesin to be mixed are non-adhesiveness, corrosion resistance, heat resistance and chemical resistance, and are mainly tetrafluoroethylene resin, tetrafluoroethylene-perfluorovinyl ether copolymer or tetrafluoride. An ethylene-hexafluoropropylene copolymer is used.
As the form of the fluororesin, either an aqueous dispersion or a powder can be used, and the shape is not particularly limited. Although there is no restriction | limiting in particular in the mixing amount of a fluororesin, In order to obtain a coating film with good balance, such as high adhesiveness and non-adhesiveness, it is 50 ~ with respect to 100 mass parts of (A) polyamideimide resin. It is preferable to set it as 800 mass parts, and it is more preferable to set it as 100-500 mass parts.

The water-based heat-resistant resin composition according to the present invention and the coating material of the present invention comprising the water-based heat-resistant resin composition as a coating film component are applied to a coating material and cured to form a coating film on the surface of the coating material.
In particular, the water-based heat-resistant resin composition according to the present invention has a coating film excellent in adhesion to a ceramic base material and an aluminum base material after baking at a high temperature and excellent in hardness as compared with a conventional water-based heat-resistant resin composition. Therefore, it has great benefits for various uses such as home appliances or kitchen appliances in which boiling resistance is required for the coating film.

  Next, examples of the present invention will be described. However, the present invention is not limited to these examples, and it is needless to say that the present invention includes many other embodiments based on the gist of the invention.

Example 1
Trimellitic anhydride: 1056.7 g, 4,4-diphenylmethane diisocyanate: 1390.2 g, N-methyl-2-pyrrolidone: 2169.9 g were put into a flask equipped with a thermometer, a stirrer, and a condenser tube and dried. While stirring in a nitrogen stream, the temperature was gradually raised over 2 hours to 130 ° C. The temperature was kept at 130 ° C. while keeping attention to the sudden foaming of carbon dioxide gas generated by the reaction, and the heating was continued for 6 hours, and then the reaction was stopped to obtain a polyamideimide resin solution.

The obtained polyamideimide resin solution had a nonvolatile content (200 ° C.-2 h) of 50 mass% and a viscosity (30 ° C.) of 182.4 Pa · s. The number average molecular weight of the polyamideimide resin was 26000, and the acid value of the combined carboxyl group and ring-opened acid anhydride group was 35 mgKOH / g. The number average molecular weight was measured under the following conditions.
Model: Hitachi, Ltd. Product name: L6000
Detector: manufactured by Hitachi, Ltd. Product name: L4000 type UV
Wavelength: 270nm
Data processor: ATT 8
Column: Hitachi Chemical Co., Ltd. Product name: Gelpack GL-S300MDT-5 × 2
Column size: Diameter 8mm x 300mm
Solvent: DMF / THF = 1/1 (liter) + phosphoric acid 0.06M + lithium bromide 0.06M Sample concentration: 5 mg / 1 ml
Injection volume: 5 μl
Pressure: 4.8 × 10 ⁶ Pa (49 kgf / cm ² )
Flow rate: 1.0 ml / min

  900 g of this polyamideimide resin solution was placed in a flask equipped with a thermometer, a stirrer, and a cooling tube, and gradually heated to 70 ° C. while stirring in a dried nitrogen stream. When the temperature reached 70 ° C., 127.8 g (4.5 equivalents) of triethylamine was added, and the mixture was sufficiently stirred while being kept at 70 ° C. Then, ion-exchanged water was gradually added while stirring. Finally, ion-exchanged water was added until 3533.0 g (solvent ratio: 70% by mass) to obtain a transparent and uniform aqueous heat-resistant resin composition.

(Example 2)
Trimellitic anhydride: 480.3 g, 4,4′-diphenylmethane diisocyanate: 669.4 g, N-methyl-2-pyrrolidone: 1061.3 g were put in a flask equipped with a thermometer, a stirrer, and a condenser tube and dried. While stirring in a nitrogen stream, the temperature was gradually raised over 1 hour to 90 ° C. The temperature was kept at 90 ° C. while paying attention to the sudden foaming of carbon dioxide gas generated by the reaction, and the heating was continued for 8 hours from the start of heating. Then, the reaction was stopped to obtain a polyamideimide resin solution.
The polyamideimide resin solution had a nonvolatile content (200 ° C.-2 h) of 50 mass% and a viscosity (30 ° C.) of 161.0 Pa · s. The number average molecular weight of the polyamideimide resin was 22,000, and the acid value of the combined carboxyl group and ring-opened acid anhydride group was 45 mgKOH / g.
500 g of this polyamideimide resin solution was put in a flask equipped with a thermometer, a stirrer, and a cooling tube, and gradually heated while stirring in a dried nitrogen stream to reach 90 ° C. When the temperature reached 90 ° C., 81.6 g (3.5 equivalents) of N, N, N ′, N′-tetramethylethylenediamine was added, and after sufficiently stirring while maintaining 90 ° C., gradually, Ion exchange water was added. Finally, ion-exchanged water was added until 459.2 g (solvent ratio 50% by mass) to obtain a transparent and uniform aqueous heat-resistant resin composition.

(Example 3)
Trimellitic anhydride: 672.4 g, 4,4′-diphenylmethane diisocyanate: 902.2 g, N-methyl-2-pyrrolidone: 1705.8 g were put in a flask equipped with a thermometer, a stirrer and a condenser tube and dried. In a nitrogen stream, the temperature was gradually raised over 1 hour with stirring, and the temperature was raised to 120 ° C. While paying attention to the sudden foaming of carbon dioxide gas generated by the reaction, the temperature was gradually raised to 150 ° C., and the heating was continued for 5 hours from the start of heating. Then, the reaction was stopped to obtain a polyamideimide resin solution.
The polyamideimide resin solution had a nonvolatile content (200 ° C.-2 h) of 40 mass% and a viscosity (30 ° C.) of 156.6 Pa · s. Further, the number average molecular weight of the polyamideimide resin was 27000, and the acid value obtained by combining the carboxyl group and the acid anhydride group was 32 mgKOH / g.
200 g of this polyamideimide resin solution was placed in a flask equipped with a thermometer, a stirrer, and a cooling tube, and gradually heated to 50 ° C. while stirring in a dried nitrogen stream. When the temperature reached 50 ° C., 42.3 g (5 equivalents) of tributylamine was added, and after sufficiently stirring while maintaining the temperature at 50 ° C., ion-exchanged water was gradually added while stirring. Finally, ion-exchanged water was added until it reached 94.2 g (solvent ratio 40% by mass) to obtain a transparent and uniform aqueous heat-resistant resin composition.

Example 4
Trimellitic anhydride: 1216.3 g, 4,4′-diphenylmethane diisocyanate: 1216.3 g, N-methyl-2-pyrrolidone: 1918.2 g were put in a flask equipped with a thermometer, a stirrer and a condenser tube and dried. While stirring in a nitrogen stream, the temperature was gradually raised over 1 hour to 120 ° C. The temperature was kept at 120 ° C. while paying attention to the sudden bubbling of carbon dioxide gas generated by the reaction, and the heating was continued for 7 hours from the start of heating. Then, the reaction was stopped to obtain a polyamideimide resin solution.
The polyamideimide resin solution had a nonvolatile content (200 ° C.-2 h) of 50 mass% and a viscosity (30 ° C.) of 180.8 Pa · s. The number average molecular weight of the polyamideimide resin was 29000, and the acid value of the combined carboxyl group and ring-opened acid anhydride group was 35 mgKOH / g.
700 g of this polyamideimide resin solution was put into a flask equipped with a thermometer, a stirrer, and a cooling tube, and gradually heated to 80 ° C. while stirring in a dried nitrogen stream. When the temperature reached 80 ° C., 477.3 g (4.7 equivalents) of triethylamine was added, and after sufficiently stirring while maintaining at 80 ° C., ion-exchanged water was gradually added while stirring. Finally, ion-exchanged water was added until the amount reached 600.0 g (solvent ratio: 65% by mass) to obtain a transparent and uniform aqueous heat-resistant resin composition.

(Comparative Example 1)
Trimellitic anhydride: 1106.2 g, 4,4-diphenylmethane diisocyanate: 1455.8 g, N-methyl-2-pyrrolidone: 2562.0 g were put into a flask equipped with a thermometer, a stirrer, and a condenser tube and dried. While stirring in a nitrogen stream, the temperature was gradually raised over 2 hours to 130 ° C. The temperature was maintained at 130 ° C. while paying attention to the sudden bubbling of carbon dioxide gas generated by the reaction, and the heating was continued for 6 hours, and then the reaction was stopped to obtain a polyamideimide resin solution.
This polyamideimide resin solution had a nonvolatile content (200 ° C.−2 h) of 50 mass% and a viscosity (30 ° C.) of 85.0 Pa · s. The number average molecular weight of the polyamideimide resin was 17,000, and the acid value of the combined carboxyl group and ring-opened acid anhydride group was 40 mgKOH / g.
2700 g of this polyamideimide resin solution was put into a flask equipped with a thermometer, a stirrer, and a cooling pipe, and gradually heated to 50 ° C. while stirring in a dried nitrogen stream. When the temperature reached 50 ° C., 447.1 g (4 equivalents) of triethylamine was added, and the mixture was sufficiently stirred while being kept at 50 ° C., and then ion-exchanged water was gradually added while stirring. Finally, ion-exchanged water was added until the amount reached 1348.8 g (solvent ratio: 50% by mass) to obtain a transparent and uniform aqueous heat-resistant resin composition.

(Comparative Example 2)
Trimellitic anhydride: 382.9 g, 4,4′-diphenylmethane diisocyanate: 503.9 g, N-methyl-2-pyrrolidone: 886.8 g were put into a flask equipped with a thermometer, a stirrer and a condenser tube and dried. The mixture was gradually heated to 80 ° C. over 1 hour with stirring in a nitrogen stream. The temperature was kept at 80 ° C. while paying attention to the sudden foaming of carbon dioxide gas generated by the reaction, and the heating was continued for 7 hours from the start of heating. Then, the reaction was stopped to obtain a polyamideimide resin solution.
The polyamideimide resin solution had a nonvolatile content (200 ° C.-2 h) of 50 mass% and a viscosity (30 ° C.) of 82.6 Pa · s. The number average molecular weight of the polyamideimide resin was 15000, and the acid value of the combined carboxyl group and ring-opened acid anhydride group was 50 mgKOH / g.
200 g of this polyamideimide resin solution was placed in a flask equipped with a thermometer, a stirrer, and a cooling tube, and gradually heated to 90 ° C. while stirring in a dried nitrogen stream. When the temperature reached 90 ° C., 70.8 g (8 equivalents) of N-methylmorpholine was added, and the mixture was sufficiently stirred while maintaining at 90 ° C., and then ion-exchanged water was gradually added while stirring. Finally, ion-exchanged water was added until the amount reached 180.5 g (solvent ratio: 65% by mass) to obtain a transparent and uniform aqueous heat-resistant resin composition.

(Comparative Example 3)
Trimellitic anhydride: 233.8 g, benzophenone tetracarboxylic anhydride: 98.0 g, 4,4′-diphenylmethane diisocyanate: 384.6 g, N-methyl-2-pyrrolidone: 1671.6 g, thermometer, stirrer, cooling The mixture was placed in a flask equipped with a tube, and gradually heated to 120 ° C. over 1 hour while stirring in a dried nitrogen stream. While paying attention to the sudden foaming of carbon dioxide gas generated by the reaction, the temperature was gradually raised to 150 ° C., and the heating was continued for 5 hours from the start of heating. Then, the reaction was stopped to obtain a polyamideimide resin solution.
The polyamideimide resin solution had a nonvolatile content (200 ° C.−2 h) of 30 mass% and a viscosity (30 ° C.) of 2.1 Pa · s. Moreover, the number average molecular weight of the polyamideimide resin was 23000, and the acid value of the combined carboxyl group and acid anhydride group was 30 mgKOH / g.
200 g of this polyamideimide resin solution was put into a flask equipped with a thermometer, a stirrer, and a cooling tube, and gradually heated to 110 ° C. while stirring in a dried nitrogen stream. When the temperature reached 110 ° C., 17.6 g (6 equivalents) of N, N-dimethylethanolamine was added, and after sufficiently stirring while maintaining at 110 ° C., ion-exchanged water was gradually added while stirring. Finally, ion-exchanged water was added until 217.6 g (solvent ratio: 60% by mass) to obtain a transparent and uniform aqueous heat-resistant resin composition.

(Comparative Example 4)
Trimellitic anhydride: 999.0 g, 4,4-diphenylmethane diisocyanate: 1314.4 g, N-methyl-2-pyrrolidone: 2051.5 g were put into a flask equipped with a thermometer, a stirrer, and a cooling tube and dried. While stirring in a nitrogen stream, the temperature was gradually raised over 2 hours to 140 ° C. The temperature was kept at 140 ° C. while keeping attention to the sudden foaming of carbon dioxide gas generated by the reaction, and the heating was continued for 8 hours. Then, the reaction was stopped to obtain a polyamideimide resin solution.
The polyamideimide resin solution had a nonvolatile content (200 ° C.-2 h) of 45 mass% and a viscosity (30 ° C.) of 153.4 Pa · s. The number average molecular weight of the polyamideimide resin was 40,000, and the acid value of the combined carboxyl group and ring-opened acid anhydride group was 25 mgKOH / g.
1000 g of this polyamideimide resin solution was put into a flask equipped with a thermometer, a stirrer, and a cooling tube, and gradually heated to 60 ° C. while stirring in a dried nitrogen stream. When the temperature reached 60 ° C., 101.5 g (5 equivalents) of triethylamine was added, and after sufficiently stirring while maintaining 60 ° C., ion-exchanged water was gradually added while stirring. Finally, ion-exchanged water was added until 1189.0 g (solvent ratio: 70% by mass) to obtain a transparent and uniform aqueous heat-resistant resin composition.

(Test example)
The aqueous heat-resistant resin composition obtained in Examples 1 to 4 and Comparative Examples 1 to 4 and an aqueous dispersion of tetrafluoroethylene resin were combined with aqueous heat-resistant resin: tetrafluoroethylene resin = 25: 75 ( Resin mass ratio) was diluted with ion-exchanged water so that the solid content of the coating was 25% to prepare a test coating. This paint was applied on each enameled TP substrate (0.5 × 70 × 150 mm, manufactured by Partec Co., Ltd.) and aluminum substrate (1 × 50 × 150 mm, manufactured by Partec Co., Ltd.), and the following adhesion and pencil hardness were applied. A test was conducted. The test results are shown in Table 1.
In Table 1, the acid value of (A) polyamide-imide resin is the acid value of the resin combined with the carboxyl group and ring-opened acid anhydride group, and the blending amount (equivalent) of (B) alkylamine Is a numerical value for the acid value of the combined carboxyl group and ring-opened acid anhydride group contained in the (A) polyamideimide resin, (C) the water content and (D) the organic solvent Content is a numerical value with respect to the total mass which each combined (C) water and (D) organic solvent.

(Test method)
<Adhesion>
The substrate produced by the above method was pre-dried at 80 ° C. for 10 minutes and then baked at 400 ° C. for 5 minutes to obtain a coating film having an average thickness of 10 μm at five locations. A 10 × 10 square of 1 mm square was produced on this coating film, and this square was peeled five times with an adhesive tape (manufactured by Nichiban Co., Ltd.), and the number of remaining squares was counted.
<Pencil hardness>
The substrate produced by the above method was pre-dried at 80 ° C. for 10 minutes and then baked at 400 ° C. for 5 minutes to obtain a coating film having an average thickness of 10 μm at five locations. The coating film was shaved with a pencil, and the hardness of the pencil at the time of scratching was recorded.

From the said Table 1, the coating film produced from the water-based heat resistant resin composition obtained in Examples 1-4 is the coating film produced from the water-based heat resistant resin composition obtained in Comparative Examples 2-4. In comparison, it was found that the adhesion after baking at 400 ° C. for 5 minutes was greatly improved.
Moreover, the coating film produced from the aqueous heat-resistant resin composition obtained in Examples 1 to 4 was compared with the coating film produced from Comparative Example 1 and produced from the conventional aqueous heat-resistant resin composition. Thus, it was found that the hardness of the coating film after baking at 400 ° C. for 5 minutes was improved.
From this result, by using the water-based heat-resistant resin composition of the present invention, a coating film having excellent adhesion and hardness to a ceramic substrate even after high-temperature baking is obtained as compared with the conventional water-based heat-resistant resin composition. It turns out that it becomes possible. For this reason, it has great benefits for various applications that require high adhesion and hardness to ceramic substrates and aluminum substrates fired at high temperatures, such as home appliances or kitchen appliances. It is clear that

Claims (10)

  (A) A water-based heat-resistant resin composition comprising a polyamideimide resin having a number average molecular weight of 20000 to 30000, (B) an alkylamine, (C) water, and (D) an organic solvent.   (B) The compounding amount of the alkylamine is 2.5 to 5 equivalents with respect to the acid value of the combined carboxyl group and ring-opened acid anhydride group contained in the (A) polyamideimide resin. 1. The water-based heat resistant resin composition according to 1.   The water-based heat-resistant resin composition according to claim 1 or 2, wherein the content of (C) water is 30 to 80% by mass with respect to the total mass of (C) water and (D) an organic solvent.   (D) Content of organic solvent is 20-70 mass% with respect to the total mass of (C) water and (D) organic solvent, The aqueous system of any one of Claims 1-3 Heat resistant resin composition.   (A) A polyamideimide resin obtained by copolymerizing a diisocyanate compound or diamine compound as an amine component and a tribasic acid anhydride or tribasic acid chloride as an acid component in a polar solvent It is resin, The water-system heat-resistant resin composition of any one of Claims 1-4.   (A) The acid value which combined the carboxyl group and the ring-opened acid anhydride group of the polyamide-imide resin is 25-50 mgKOH / g, The water-based heat resistant resin of any one of Claims 1-5 Composition.   The coating material which uses the water-system heat-resistant resin composition of any one of Claims 1-6 as a coating-film component.   Furthermore, the coating material of Claim 7 containing a fluororesin.   A home appliance in which a coating film is formed using the paint according to claim 8.   A kitchen appliance in which a coating film is formed using the paint according to claim 8.