JPH05186738A - Heat-cured, water-repellent coating film and cooking device coated therewith - Google Patents

Abstract

PURPOSE:To form a water-repellent coating film, which can be prepared by baking at a relatively low temperature and has a resistance to boiling water, on the surface of a base material, thereby permitting the color tone of the material to be utilized as it is and stains to be removed easily. CONSTITUTION:The title coating film, which has a persistent water repellence and a capability of cleaning stains off easily, is formed by coating the surface of a base material with a mixture comprising at least an epoxy resin, trimellitic anhydride, and 0.1-0.5wt.% fluoroalkylsiloxane compound based on the sum of the epoxy resin and the trimellitic anhydride, and curing the mixture with heat at a relatively low temperature to form a colorless and transparent coating film.

Description

Detailed Description of the Invention

[0001]

The present invention is applied to the surface of a substrate,
The present invention relates to a thermosetting water-repellent coating film which is cured by heating and has good water repellency and releasability for a long time, and a cooker in which this coating film is formed on the inner surface of a container.

[0002]

2. Description of the Related Art In recent years, even if dirt adheres, the demand for a coating film that can be easily removed and cleaned by wiping it off, and at the same time rust prevention by maintaining water repellency for a long time, is becoming stronger. ing. For this purpose, a fluorine coating film is generally used.

[0003]

The conventional fluorine-coated film has poor adhesion to the substrate, and in order to maintain the coating firmly adhered over a long period of time, the surface of the substrate is blasted or the like. The surface is extremely surface-roughened by the physical method by erosion etching by chemicals, or immediately after this treatment, the fluororesin primer coating is immediately applied on this surface, and after drying, the fluororesin coating for topcoat is applied again. After that, it was formed by baking at a high temperature of 380 ° C. For this reason, high temperature is required for roughening the surface of the base material and baking, so that a high level of technology is required for forming the film, and it is difficult to cope with the general coating form. Furthermore, the state of the applied fluorine coating cannot be utilized by making the best use of the surface state and color appearance of the base material due to the addition of the modified pigment and cannot meet the demand for coloring to various color tones. It was Further, since this coating film was soft, scratches were likely to occur. Furthermore, it could not be applied to the surface of plastics.

The present invention solves these problems, and by forming a thermosetting water-repellent coating film by coating and baking once, it is possible to cope with a very general form of coating, and The first purpose is to be able to maintain water repellency over a period of time, to form a colorless and transparent coating film, and to enable arbitrary coloring.

The second purpose is to provide a container which is free from deterioration of the coating film for a long period of time and is capable of easily releasing the deposits such as water stains and cooked foods and maintaining water repellency for the purpose of rust prevention. The cooker provided is provided.

[0006]

The first means of the present invention for achieving the above first object comprises at least an epoxy resin, trimellitic anhydride, and a fluoroalkyl siloxane compound. A thermosetting water-repellent coating film is formed by adding 0.1% by weight to 5.0% by weight of the fluoroalkylsiloxane compound to a mixture of a resin and the trimellitic anhydride.

Second aspect of the present invention for achieving the second object
The means is to construct a cooker by mounting a container having a thermosetting water-repellent coating film formed on the inner surface of the container.

[0008]

[Function] At least an epoxy resin is completely miscible mixed with trimellitic anhydride, and a fluoroalkylsiloxane compound is mixed with this system to form a coating film-forming composition, which is then degreased by a conventional method. This composition can be easily applied to the surface of a base material, and by subjecting the composition to baking at a relatively low temperature of 130 ° C. or higher, the fluoroalkyl siloxane compound migrates to the surface layer portion of the coating film and becomes a coating film component. It is chemically bonded to form a strong thermosetting water-repellent coating film.

The necessary conditions for forming this coating film are as described in 3 above.
The fluoroalkyl siloxane compound, which has a relatively low molecular weight among the three components, is mixed in a range where the components are compatible with each other, is stable in the mixed state, and is applied to the surface of the base material and heated. While moving to the surface layer portion, it reacts with hydroxyl groups and carboxyl groups generated in the curing reaction process of the epoxy resin and trimellitic acid to form a coating film component, which is fixed and forms the desired thermosetting water-repellent coating film.

In this state, the fluoroalkylsiloxane compound is not simply attached to the surface of the coating film, but the coating component is a state in which the fluoroalkylsiloxane compound is distributed in the surface layer portion. Even if the water disappears, the water-repellent layer is exposed by prompting by washing, rubbing, wiping, etc. the coating on the new layer of the coating. As a result, the easy removal of the adhered dirt can be maintained, and as a result, the rust preventive power of the metal can be maintained. As described above, since it is possible to secure sufficient adhesion and uniformity of the coating film by the ordinary degreasing treatment without performing the pretreatment of the substrate strictly like the conventional fluorine coating, it is extremely easy to form the coating film. ..

The effect is that even if the amount of the fluoroalkylsiloxane compound mixed is increased more than necessary, the above-mentioned effect on the surface portion is constant, and conversely, the mixed composition and the cured coating film become clouded, and at the same time, Since a repellency phenomenon appears on the surface of the base material during coating on the base material, as a result, the coating film causes repellency, impairs homogenization, and lowers adhesion to the base material.

In order to achieve the second object, the thermosetting water-repellent coating film of the present invention is formed on the inner surface of a stainless 430 container to form a water container, which is attached to form a jar pot. Since the firing temperature for forming the film is 130 ° C. or higher, which is a relatively low temperature, formation of an oxide film of stainless steel does not occur. Therefore, since the color feeling of the base material can be utilized as it is through the coating film, the beautiful feeling for filling the drinking water (food) is not impaired. Further, the water repellency can be easily re-added by the cleaning of the adherence of water stains to the vessel wall due to repeated boiling of water, and the water repellent can be re-added for a long period of time. Moreover, the coating film is hardly damaged.

For the second object, when the thermosetting water-repellent coating film of the present invention is formed on the inner surface of the container and attached to the main body to form a cooker, even if the cooked product sticks, Since the above effects can be obtained by releasing the mold and performing a simple cleaning, the beauty and cleanliness can be maintained for a long time.

[0014]

Example 1 An epoxy resin composed of a phenolic compound and epichlorohydrin was used as an epoxy resin 828 (produced by Yuka Shell Epoxy Co., Ltd.) and trimellitic anhydride were mixed at different mixing ratios. 1% by weight of hexadecafluorodecatyltrimethoxysilane as a fluoroalkylsiloxane compound is mixed with 2% by weight,
A solid content of 25% by weight was diluted with butanone to form a coating film forming composition. This composition was applied to the surface of a stainless steel 430 base material that had been degreased with an ordinary degreasing agent so that the coating thickness after baking was 15 ± 5 μm, and baking was performed at 200 ° C. for 60 minutes to give a colorless and transparent present invention. Was formed. After immersing this in boiling water for 200 hours, the state of the coating film surface,
The adhesion of the coating film to the substrate was tested and is shown in (Table 1).

[0015]

[Table 1]

As is clear from these results, the mixing range of trimellitic anhydride is preferably 10% by weight to 40% by weight.

Next, the total amount is 100 with respect to the mixture of 80% by weight of the epoxy resin and 20% by weight of trimellitic anhydride.
A thermosetting coating film was formed in the same manner as above by changing the mixing amount of hexadecafluorodecatyltrimethoxysilane so that the weight% was reached, and 10 μl of water was dropped on this surface.
The measurement result of this contact angle is shown in FIG. As is clear from this result, the upper limit of the mixing of hexadecafluorodecatyltrimethoxysilane is 5 from the turbid state of the mixed composition.
% By weight. Furthermore, the lower limit of the mixing of hexadecafluorodecatritylmethoxysilane that can maintain a constant contact angle is 0.1% by weight, and the object of the present invention can be achieved. The following are effective epoxy resins that produce the same results as shown here.

Hydroxydiphenyldimethylethane (bisphenol A), hydroxydiphenylmethylethylethane, hydroxydiphenyldiethylethane, dihydroxydiphenylethane (bisphenol F), tetrabromobisphenol A and F, tetrachlorobisphenol A and F, tetrafluorobisphenol A and F
Is.

Other effective compounds are 4,4'-dihydroxydiphenyl, 4,4'-dihydroxydiphenyl sulfone, and tetrafluoro compounds thereof.

As the fluoroalkylsiloxane compound which can achieve the object of the present invention, compounds generically called trioxyfluorosiloxane and trichlorofluorosiloxane are effective.

In applying the composition to the substrate, a mixed composition may be formed by arbitrarily diluting it with an alcohol, chlorine-based, ketone-based or aromatic hydrocarbon-based solvent. The method of application is spraying or dipping. It is pulled up and made with rollers. As the base material, a base material such as metal, glass, or plastics can be used as long as it can withstand the firing at the time of forming the coating film, and the performance shown above can be obtained. The base material to be applied may be plate-shaped.

(Example 2) Brominated epoxy resin (18-
20% Br) 80% by weight and trimellitic anhydride 20% by weight, to 99.5% by weight, 0.5% by weight of hexadecafluorodecatyltrichlorosilane was mixed, and 85% by weight of this mixture. 15 wt% of rutile-type titanium oxide was uniformly dispersed in the mixture, and diluted to a solid content of 25 wt% with a 2-butanone / trichloroethane = 50/50 mixed solvent to form a coating film forming composition. .. 15 ± 5 μm as the coating thickness after baking this composition on the surface of a soda glass base material with a plate thickness of 4 mm that has been degreased with an ordinary degreasing agent
And then baked at 180 ° C. for 60 minutes to form the coating film of the present invention. After this was immersed in boiling water for 200 hours, the state of the coating film surface and the adhesion of the coating film to the base material were tested. As a result, the appearance was good, and no peeling was observed in the second-eye tape peeling test. Moreover, the contact angle when 10 μl of water was dropped on the surface of the coating film was 114 °.

(Embodiment 3) A jar pot will be described below as an embodiment of the second invention of the present invention. Figure 2
This configuration will be described based on the configuration sectional view of the jar pot shown in FIG. Reference numeral 2 denotes a hot water holding container made of stainless steel coated with the coating film-forming composition obtained by the same method as that of Example 1. There is. This is attached to the main body 1 as a hot water storage container, and the upper part of this is a lid 3 which can be opened and closed by a hinge 4.
Is covered with. 5 is hot water stored in the hot water holding container 2. 6 is a pump knob for discharging hot water 5, 7
Is a hot water outlet. Reference numeral 8 is a power cord for supplying power to the main body 1.

Next, the operation will be described. The water in the hot water holding container 2 is heated and boiled in a state where power is supplied from the power cord 8 and is shut off from the outside by the lid 3, and then the temperature is constantly maintained at a temperature of 95 ° C. or higher. Therefore, since hot water is always kept in contact with the thermosetting water-repellent coating film shown above, the deposition and adhesion of the components dissolved in the hot water onto the coating film surface portion adheres as dirt and accumulates. .. The hot water 5 kept warm is discharged by the pump knob 6 as needed. When there is no hot water 5, pour new water to bring it to a boil. The jar pot is used in a state where this operation is repeated.

In order to test the performance of the thermosetting water-repellent coating film for practical use, a series of operations of pouring water, boiling water, holding for 60 minutes, discharging hot water, and pouring water were carried out for 1000 times.
Repeatedly repeated. During this time, the stains on the thermosetting water-repellent coating film were washed every 100 times by boiling and washing with a 2.5 wt% citric acid aqueous solution, and then the contact angle of water was measured by the same method as above. Is shown in FIG. From this result, the object of the present invention is satisfied for long-term use.
No rust was found.

Although an example of a jar pot has been described here, this effect can be similarly exerted on various cooking devices.

[0027]

As is apparent from the above embodiments, the first
According to the invention, at least 0.1% by weight to 5.0% by weight of a fluoroalkylsiloxane compound is added to a mixture of an epoxy resin and trimellitic anhydride on the surface of various substrates. By forming a thermosetting water-repellent coating film by one-time application and firing after ordinary degreasing treatment, it is possible to handle in a very general coating form and maintain water repellency for a long time. Since it is possible to form a colorless and transparent coating film, the state and color appearance of the surface of the substrate can be utilized, and further, arbitrary coloring is possible.

According to the second invention, the thermosetting water-repellent coating film is formed on the inner surface of the container of the cooking device and mounted on the main body, so that the water repellency does not change for long-term practical use. As a result, this effect is great because a cooking device can be constructed in which rust is not generated, stains can be easily washed, and the color appearance of the substrate can be utilized.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the amount of fluoroalkylsilane and the contact angle of water.

FIG. 2 is a configuration diagram of a jarbot according to an embodiment of the second invention.

FIG. 3 is a diagram showing a contact angle of water on an inner wall surface of a jar pot which is an embodiment of the second invention.

[Explanation of symbols]

 1 Main body 2 Hot water holding container 3 Lid 4 Hinge 5 Hot water 6 Pump knob 7 Hot water outlet

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C09K 3/18 104 8318-4H

Claims (2)

[Claims] 1. At least an epoxy resin, trimellitic anhydride, and a fluoroalkyl siloxane compound, and 0.1% of the fluoroalkyl siloxane compound is added to a mixture of the epoxy resin and the trimellitic anhydride. A thermosetting water-repellent coating film added by wt% to 5.0 wt%. 2. A cooker comprising the thermosetting water-repellent coating film according to claim 1 formed on the inner surface of a container.