JPH07118608A - Hydrophilic coating film, its production and cooking utensil having hydrophilic coating film - Google Patents

Abstract

PURPOSE:To protect a substrate and impart the substrate with wettability by forming a hydrophilic coating film having heat-resistance, steam resistance and boiling water resistance on the surface of a substrate. CONSTITUTION:A surface of a substrate 1 is coated with a glycidoxyalkylalkylsiloxane 2 under acidic condition and baked to obtain a coating film having steam resistance and boiling water resistance durable over a long period and effective for protecting the substrate and imparting the substrate with wettabilit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is applied to the surface of a base material, and is formed by baking, and has long-term heat resistance.
The present invention relates to a coating film having a vapor-proof and boiling water-resistant property for protecting a substrate and wettability, and a cooker having the coating film formed on a container and a lid thereof.

[0002]

2. Description of the Related Art In recent years, many coating films have been developed which can maintain the protection of the base material for a long period of time. However, most of the coating films are water repellent and hydrophilic because they are intended to protect the base material. In order to provide the property, corona discharge treatment or silica sol is generally applied on the coating film.

[0003]

In the conventional corona discharge treatment on the coating film, the surface of the hydrophilic coating film is easily renewed to a water-repellent coating surface with the passage of time. Due to poor adhesion of silica sol to the silica sol, the silica sol may be eluted into water, and in any case, it was difficult to maintain the hydrophilicity for a long period of time.

The present invention is to solve these problems, and to form a coating film having heat resistance, steam resistance, and boiling water resistance to protect a substrate and wettability over a long period of time. The purpose of 1.

A second object is to be able to form a coating film having improved boiling water resistance. A third object is to be able to form a coating film having further improved heat resistance.

A fourth object of the present invention is to provide a method for producing a hydrophilic coating film which has heat resistance, steam resistance, and boiling water resistance to protect a substrate and wettability over a long period of time.

Further, it is an object of the present invention to provide a cooker provided with a container or a lid which can maintain the protection and wettability of a substrate by heat resistance, steam resistance and boiling water resistance without deterioration of the coating film over a long period of time. The fifth purpose.

[0008]

To achieve the first object, the first means of the present invention provides a hydrophilic coating film having at least dihydroxyglycylalkylsiloxane on a substrate.

The second means of the present invention for achieving the above-mentioned second object is obtained by a mixture obtained by adding 0.1% to 100% by weight of alkylsiloxane to the mixture of the above-mentioned first means. To form a hydrophilic coating film with boiling water resistance.

The third means of the present invention for attaining the third object is obtained by adding a mixture of 0.1% by weight to 100% by weight of phenylsiloxane to the mixture of the first means. To form a hydrophilic coating film with boiling water resistance.

The fourth means of the present invention for attaining the above-mentioned fourth object is to apply a glycidoxyalkylsiloxane or a mixture containing at least a glycidoxyalkylsiloxane to the surface of a base material under an acidic condition, and calcine. A method for producing a hydrophilic coating film obtained by the method is provided.

The fifth means of the present invention for achieving the above fifth object is the protection of the base material by the heat resistance, steam resistance and boiling water resistance of the above first, second or third means. The object is to form a cooker equipped with a container or a lid having a wettable hydrophilic coating film formed on its inner surface.

[0013]

[Function] When a glycidoxyalkylsiloxane is applied to the surface of a base material under an acidic condition and baked, the silanol group of the glycidoxyalkylsiloxane reacts with the hydroxyl group on the surface of the base material to dihydroxyglycyl. The alkyl siloxane is immobilized with a covalent bond. Further, the unreacted silanol groups react with the adjacent unreacted silanol groups, so that the dihydroxyglycylalkylsiloxanes immobilized on the surface of the base material are condensed with each other. On the other hand, the epoxide ring of glycidoxyalkylsiloxane is cleaved under acidic conditions and converted into a structure having two hydroxyl groups, and the hydroxyl groups are oriented on the surface. As a result, a coating film having wettability due to silanol groups can be obtained.

In this state, glycidoxyalkylsiloxane is covalently immobilized on the surface of the substrate, and the oxysilane ring of the glycidoxyalkylsiloxane is converted into a structure having two hydroxyl groups and oriented on the surface. Therefore, unlike the state of simply adhering, good wettability can be maintained for a long period of time. Further, since the glycidoxyalkylsiloxanes immobilized on the surface of the base material are polycondensed with each other, the protection of the base material due to heat resistance, steam resistance, and boiling water resistance can be maintained for a long period of time.

Further, a mixture of glycidoxyalkylsiloxane and alkylsiloxane added under acidic conditions or a mixture of glycidoxyalkylsiloxane and phenylsiloxane added under acidic conditions is applied to the surface of the substrate and baked, In addition to the above action, the glycidoxy alkyl siloxane and the alkyl siloxane or phenyl siloxane are copolycondensed to form a resin, so that the protective property of the substrate can be improved.

Further, when the hydrophilic coating film of the present invention is formed on the inner surface and the lid of the container and is attached to the main body to form a cooking device,
In addition to being able to maintain the protective properties of the container or lid base material for a long period of time, the container surface has wettability during heating and cooking compared to the case of a water-repellent coating film, so that heat conduction to the food can be improved. At the same time, abnormal heating of the container itself is less likely to occur, so that burning of the coating film and malfunction of the temperature sensor of the cooking device can be less likely to occur. Further, by making the lid surface also wettable, the amount of dew condensation on the lid surface due to the vapor generated in the container is reduced, and the amount of dew that flows down to the lid frame of the container when the lid is opened and closed can be reduced. On the other hand, because it has a certain degree of water repellency,
Even if the cooked food becomes sticky, it can be easily released from the mold, and the cleanliness can be maintained for a long time with simple washing.

[0017]

【Example】

(Example 1) S as a glycidoxyalkylsiloxane
H-6040 (manufactured by Toray Dow Corning Co., Ltd.) is applied under acidic conditions so that the thickness of this coating film after firing is 1 μm or less, and the coating is applied on a substrate and fired at 120 ° C. for 60 minutes. . After dipping the coated substrate in boiling water, 2.
FIG. 1 shows a cross-sectional structural diagram of a hydrophilic coating film obtained by boiling and washing with a 5% by weight citric acid aqueous solution. In FIG. 1, 1 is a base material and 2 is a glycidoxyalkylsiloxane. Further, FIG. 2 shows a model of the chemical reaction on the surface in the process of forming the hydrophilic coating film at this time.

Next, as a glycidoxyalkyl siloxane, SH-6040 (Toray Dow Corning Co., Ltd.) was used.
And a mixture of SZ-6070 (manufactured by Dow Corning Toray Co., Ltd.) as an alkyl siloxane are used under acidic conditions, and the thickness of the coating film after firing is applied to a substrate to be 1 μm or less. Then, it is baked at 120 ° C. for 60 minutes. FIG. 3 shows a model of the chemical reaction on the surface in the process of producing a hydrophilic coating film obtained by immersing the coated base material in boiling water and then boiling and washing it with a 2.5 wt% aqueous citric acid solution. Show. Further, the contact angle of water and the state of the coating film when 10 μl of water was dropped on the surface of the coating film with respect to the immersion time at this time are shown in (Table 1).

[0019]

[Table 1]

From these results, the glycidoxyalkylsiloxane coating is superior in wettability to the alkylsiloxane, and the coating of the mixture of glycidoxyalkylsiloxane and alkylsiloxane is more glycidoxyalkyl. The higher the siloxane mixing ratio, the better the wettability. Further, the higher the mixing ratio of the alkyl siloxane, the better the boiling water resistance, and the target of the present invention can be achieved.

S as the glycidoxyalkyl siloxane
H-6040 (manufactured by Toray Dow Corning Co., Ltd.) and SS-1830 (manufactured by Toray Dow Corning Co., Ltd.) as phenyl siloxane were used under acidic conditions and the thickness of this coating film after firing was 1 μm. It is coated on the substrate as follows and baked at 120 ° C. for 60 minutes. The coated substrate is left in a firing furnace maintained at 250 ° C., and 2.
FIG. 4 shows a model of the chemical reaction on the surface in the process when boiling cleaning is performed with a 5% by weight aqueous citric acid solution. In addition, water 1
The contact angle of water and the state of the coating film when 0 μl is dropped are shown in (Table 2).

[0022]

[Table 2]

From these results, the glycidoxyalkylsiloxane coating is more excellent in wettability than the alkylsiloxane, and the coating of the mixture of glycidoxyalkylsiloxane and alkylsiloxane is more glycidoxyalkyl. The higher the siloxane mixing ratio, the better the wettability. Further, the higher the mixing ratio of the alkyl siloxane, the better the heat resistance, and the target of the present invention can be achieved.

As the glycidoxyalkylsiloxane compound which can achieve the object of the present invention, compounds generally referred to as trialkoxyglycidoxyalkylsiloxane and trichloroglycidoxyalkylsiloxane are used, and as the alkylsiloxane compound, trialkoxy compounds are used. The compounds generically referred to as alkyl siloxane and trichloroalkyl siloxane are effective as the phenyl siloxane compound, and the compounds generically referred to as triphenyl alkyl siloxane and trichlorophenyl siloxane are effective.

In applying the composition to the substrate, the pH of the solution is adjusted to 7 or less by arbitrarily diluting it with a solvent in which water is mixed with alcohol, chlorine or ketone and adding an arbitrary acid. It may be adjusted, and the coating method may be spraying, dipping and pulling, a roller or the like. The base material is metal
Substrates such as glass can be used as long as they can withstand baking during the formation of a coating film such as glass, and the above-described performance can be obtained. The substrate to be applied may be plate-shaped.

(Embodiment 2) A rice cooker will be described as an embodiment of the cooker of the present invention. The operation of this configuration will be described based on the configuration cross-sectional view of the rice cooker shown in FIG. Reference numeral 4 denotes an inner lid made of the base material on which the hydrophilic coating film is formed, which is shown in the first embodiment.
It is attached to the outer lid 5 which can be opened and closed by. 7 is water and rice stored in a pan 8. Reference numeral 9 is a power cord for supplying power to the main body 3.

Next, the operation will be described. After power is supplied from the power cord 9 and the inner lid 4 and the outer lid 5 are shielded from the outside, the water and rice in the pot 8 are heated from this bottom portion to cook rice, and then the heat retaining state is always maintained. Therefore, the steam is always kept in contact with the hydrophilic coating film shown above. The rice cooker is used in a state where this operation is repeated.

In order to test the performance of the hydrophilic coating film for practical use, a series of operations in which water and rice were added to cook the rice and the temperature was kept for 60 minutes were repeated 1000 times. During this time 10
Every time, the stains on the hydrophilic coating film were washed by boiling with 2.5% by weight aqueous citric acid solution. As for the inner lid 4 made of a base material on which a hydrophilic coating film is formed in the course of this series of operations, the state of the coating film and the contact angle of water and vapor are condensed by the same method as described above to condense the lid of the main body 3. The amount of dew flowing into the frame was measured, and the results are shown in (Table 3).

[0029]

[Table 3]

From these results, the object of the present invention is satisfied for long-term use. In addition, no stickiness or rusting of the cooked food was observed.

(Embodiment 3) Next, a jar pot will be described as an embodiment of the cooking device of the present invention. The operation of this configuration will be described based on the configuration sectional view of the jar pot shown in FIG. Reference numeral 10 denotes a hot water holding container composed of the base material on which the hydrophilic coating film described in Example 1 is formed.
It is attached to a lid 13 that can be opened and closed by a hinge 12
Is covered with. Reference numeral 14 denotes hot water stored in the hot water holding container 10. Reference numeral 15 is a pump knob for discharging the hot water 14, and 16 is a hot water outlet. Reference numeral 17 is a power cord for supplying power to the main body 11.

Next, the operation will be described. The water in the hot water holding container 10 is heated and boiled in a state where power is supplied from the power cord 17 and the outside is shut off by the lid 13, and then the temperature is constantly maintained at a temperature of 95 ° C. or higher. Therefore, since the hot water 14 is always kept in contact with the hydrophilic coating film shown above, the deposition and adhesion of the components dissolved in the hot water onto the surface portion of the coating film adheres and accumulates as dirt. The hot water 14 kept warm is discharged by the operation of the pump knob 15 as necessary. When the hot water 14 is exhausted, it is boiled by pouring in new water. The jar pot is used in a state where this operation is repeated.

In order to test the performance of the hydrophilic coating film for practical use, a series of operations of pouring water in, boiling for 60 minutes, discharging hot water, and pouring water was repeated 1000 times. During this time, the stains on the hydrophilic coating film were washed by boiling every 100 times with a 2.5 wt% aqueous citric acid solution. In the middle of this series of operations, the state of the coating film was observed on the heated bottom surface of the hot water holding container 10 composed of the substrate on which the hydrophilic coating film was formed, and the contact angle of water was measured by the same method as described above. The results are shown in (Table 4).

[0034]

[Table 4]

After this, the time until boiling is measured,
The results are shown in (Table 5).

[0036]

[Table 5]

From these results, the object of the present invention is satisfied for long-term use. In addition, no clogging of scales and no rust were observed.

(Fourth Embodiment) An oven toaster will be described as an embodiment of the cooking device of the present invention. The operation of this configuration will be described based on the configuration sectional view of the oven toaster shown in FIG. 7. Reference numeral 18 is a window glass made of glass having the hydrophilic coating film shown in the first embodiment, which is attached to a door 19 and can be opened and closed by a handle 20. Reference numeral 21 is a cooking dish, and 22 is a heater for heating the cooking dish 21. Reference numeral 23 is a power cord for supplying power to the main body 24.

Next, the operation will be described. Power is supplied from the power cord 23, and the food is placed on the cooking plate 21 in a state of being shielded from the outside by the door 19 and cooked by heating. Therefore, while the hydrophilic film shown above is heated by the heater 22,
Since the water vapor released from the food is always kept in contact with the water vapor, the water vapor condenses on the window glass 18 and the window glass 18 becomes cloudy. The oven toaster is used in the state where this operation is repeated.

In order to practically test the performance of the hydrophilic coating film, bread is placed in the cooking dish 21 and heated, and then 6
A series of operations of cooling for 0 minutes was repeated 1000 times. During this time, the stains on the hydrophilic coating film were washed by boiling every 100 times with a 2.5 wt% aqueous citric acid solution. In the middle of this series of operations, the window glass 18 made of a base material on which a hydrophilic coating film is formed also shows the state of the coating film, the stickiness of dirt, and the dew condensation caused by the contact angle of water and vapor in the same manner as above. The amount was measured, and the results are shown in (Table 6).

[0041]

[Table 6]

From these results, the object of the present invention is satisfied for long-term use.

Although the examples of the rice cooker, the jar pot, and the oven toaster have been described above, this effect can also be exerted on various cookers.

[0044]

As is clear from the above examples, according to the first invention, the glycidoxyalkylsiloxane is applied to the surface of the base material under acidic conditions and baked to give glycidoxyalkyl. The silanol group of the siloxane reacts with the hydroxyl group on the surface of the base material to immobilize the glycidoxyalkylsiloxane on the surface of the base material with a covalent bond. Further, the unreacted silanol groups react with the adjacent unreacted silanol groups, so that the glycidoxyalkylsiloxanes immobilized on the surface of the base material are condensed with each other. On the other hand, the epoxide ring of glycidoxyalkylsiloxane is cleaved under acidic conditions and converted into a structure having two hydroxyl groups, and the hydroxyl groups are oriented on the surface. As a result, a coating film having wettability due to silanol groups can be obtained. This state is different from the state of simply adhering, and can maintain good wettability for a long period of time, and can also protect the substrate by heat resistance, steam resistance, and boiling water resistance.

Further, according to the above second or third invention, a mixture of glycidoxyalkylsiloxane and alkylsiloxane added under acidic conditions or a mixture of glycidoxyalkylsiloxane and phenylsiloxane added under acidic conditions is used. By coating on the surface of a base material and baking it, in addition to the above-mentioned action, glycidoxyalkylsiloxane and alkylsiloxane or phenylsiloxane are copolycondensed to form a resin, which can improve the protective property of the base material. it can.

Further, according to the above-mentioned fourth invention, when the hydrophilic coating film is formed on the inner surface and the lid of the container and is attached to the main body to constitute the cooking device, the container or the lid base material is protected for a long period of time. In addition to maintaining heat resistance, the container surface has better wettability during heating and cooking than when using a water-repellent coating, and at the same time abnormal heating of the container itself occurs. Because it becomes difficult,
It is possible to prevent the burning of the coating film and the malfunction of the temperature sensor of the cooking device from occurring. Further, by making the lid surface also wettable, the amount of dew condensation on the lid surface due to the vapor generated in the container is reduced, and the amount of dew that flows down to the lid frame of the container when the lid is opened and closed can be reduced. On the other hand, since it has a certain degree of water repellency, it can be easily released from the cooked food even if it sticks, and can be kept clean and clean for a long period of time with simple washing.

[Brief description of drawings]

FIG. 1 is a cross-sectional structural view of a hydrophilic coating film of the first invention.

FIG. 2 is a model diagram of the chemical reaction on the surface in the process of forming the hydrophilic coating film of the second invention.

FIG. 3 is a model diagram of the chemical reaction on the surface in the process of forming the hydrophilic coating film of the third invention.

FIG. 4 is a model diagram of the chemical reaction on the surface in the process of forming the hydrophilic coating film of the fourth invention.

FIG. 5 is a configuration diagram of a rice cooker that is an embodiment of the present invention.

FIG. 6 is a configuration diagram of a jar pot which is an embodiment of the present invention.

FIG. 7 is a configuration diagram of an oven toaster according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base material 2 Glycidoxyalkyl siloxane 3 Inner lid 10 Hot water holding container 14 Hot water 18 Window glass

Claims (5)

[Claims] 1. A hydrophilic coating film having at least dihydroxyglycylalkylsiloxane on a substrate. 2. Alkyl siloxane, based on dihydroxyglycylalkyl siloxane, in excess of 0% by weight.
A hydrophilic coating film having a mixture formed by adding less than 00% by weight on a substrate. 3. Phenylsiloxane based on dihydroxyglycylalkylsiloxane, more than 1% by weight of phenylsiloxane.
A hydrophilic coating film having a mixture formed by adding less than 00% by weight on a substrate. 4. A method for producing a hydrophilic coating film obtained by applying a glycidoxyalkylsiloxane or a mixture containing at least a glycidoxyalkylsiloxane to the surface of a substrate under acidic conditions and baking the mixture. 5. A cooker having a hydrophilic coating film formed by forming the hydrophilic coating film according to claim 1, 2 or 3 on the inner surface of a container or a lid thereof.