JP2003051373A - Top plate for cooker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooker and a top plate for a cooker having an excellent antifouling property. SOLUTION: The pH of aqueous emulsion containing fluorocarbon silane hydrolysate produced under the presence of a surfactant, and silicate is adjusted, and crystallized glass of surface roughness Ry 0.5-25 μm is applied and dried to form a heat resistant water repellent coating layer on a surface. Thereby, the heat resisting and antifouling property of the top plate 2 becomes excellent.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a top plate for a cooker.

[0002]

2. Description of the Related Art Crystallized glass is widely used as a top plate of an electromagnetic induction heating type cooking device, an electric heating type cooking device for heating by infrared rays emitted from a heating element, and a heating cooking device such as a gas table. For example, an electromagnetic induction heating type cooking device is a cooking device that heats and cooks a metal pan 3 installed on a top plate 2 by electromagnetic induction heating as shown in FIG. Various kinds of dirt stick to the top plate of such a cooker during cooking. Of these, if oil stains, sugar soy sauce stains, etc. are burnt out, the top plate firmly sticks and is difficult to remove.

Therefore, a method of covalently bonding a molecule containing a fluorinated alkyl chain to the top plate and forming a water-repellent / oil-repellent thin film on the surface of the top plate so that the attached dirt can be easily removed. Was considered (Japanese Patent Laid-Open No. 4-194266).

Various proposals have been made for a silane-containing aqueous solution which can provide water and oil repellency on the surface of a glass substrate. A silicon alkoxide represented by Si (OR) ₂ in order to form a water-repellent transparent film on the surface of a glass substrate and produce a water-repellent glass, and a substituted silicon alkoxide in which a part of the alkoxyl group is substituted with a fluoroalkyl group. , A method of using a solution in which alcohol, water, and an acid or a base are mixed has been developed (Japanese Patent Laid-Open No. Hei 4-
338137).

Further, an excellent emulsion of a hydrolyzable alkoxysilane compound has been developed which can provide a substrate with water and oil repellency without requiring a special curing operation (USP 5,550,184). .

[0006]

However, the method of covalently bonding a molecule containing a fluorinated alkyl chain to the top plate has a problem of low heat resistance. This is because the crystallized glass generally used for the top plate of the cooker has excellent thermal shock and mechanical strength, but contains alkali ions such as lithium ions in order to promote crystallization. The top plate may reach a temperature of 300 ° C or higher during cooking, and at such high temperature, the alkali ions inside the crystallized glass diffuse to the surface and the thin film Si
This is because the above-mentioned alkali ions attack the portion of oxygen bound to and the covalent bond between Si and oxygen is broken, and the thin film peels off.

In a silane-containing aqueous solution capable of providing a water-repellent / oil-repellent coating film on the surface of a glass substrate, a silicon alkoxide partially substituted with a fluoroalkyl group is soluble in an alcohol / water solvent. Since it is difficult, there is a problem that the concentration cannot be increased. Furthermore, this aqueous solution has a problem that the storage property is not good because the reaction proceeds with time and the viscosity increases because the acid or base is contained in the solution containing silicon alkoxide and alcohol. There is also. Furthermore, there is a problem that it is not good for the environment in that alcohol is used.

[0008] Therefore, the present invention has been made to solve the above problems, and an object of the present invention is to provide a cooker and a cooker top plate having a coating layer having superior water repellency and heat resistance on the top plate.

[0009]

In order to solve the above problems, the cooker top plate of the present invention is a crystal having a water-repellent / oil-repellent coating film on the surface of which a molecule containing a fluorocarbon group is covalently bonded. Glass surface, the crystallized glass surface has a surface roughness Ry defined in JIS-B-0601-94 of 0.5 to 25.
μm.

This makes it possible not only to prevent dirt such as oil from sticking to the glass surface, but also to prevent the water-repellent / oil-repellent coating film from peeling off due to alkali ions contained in the crystallized glass.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 is a cooker top plate whose top plate is mainly composed of crystallized glass, wherein molecules containing fluorocarbon groups are covalently bonded to the surface of said crystallized glass. Excellent antifouling property due to the formed water and oil repellent coating film,
Demonstrates scuff resistance, water and oil repellency, JIS-B-0601-94
By setting the surface roughness Ry specified in 1 to 0.5 to 25 μm, fine irregularities are formed.Therefore, when the surface is flat, the surface is worn evenly during use, the coating film is destroyed and the antifouling property is prevented. While the function deteriorates in a short period of time, since the inner surface of the recess is less likely to be worn, the initial surface structure is maintained, and the antifouling function can be maintained for a long period of time.

[0012] According to a second aspect of the invention, particularly the coating film of repellent according to claim 1, wherein the _{R f - (CH 2) p} -Si {- (O-CH 2 CH 2) n -OR '} ₃ (1) (R _f is a perfluoroalkyl group having 3 to 18 carbon atoms or a mixture thereof, and R'is 1 to 3 carbon atoms.
Identical or different alkyl groups, p = 2
4, and n = 2-10. And a hydrolyzate formed from at least one fluorocarbon silane represented by the formula (1) in the presence of a surfactant, and Si-R ₄ (2) (R is OCH ₃ , OCH ₂ CH ₃ , and (OCH ₂ CH ₂ ) _m OCH ₃ (m = 1 to 1
It is at least one group selected from 0). ) Is used to form a heat-resistant water-repellent coating film formed by coating and drying an aqueous emulsion containing the silicate on the surface of the crystallized glass base material, so that it is less susceptible to alkali ions contained in the crystallized glass. Since it has excellent heat resistance, it can effectively prevent burning. Also, since it is excellent in strength, it is less likely to be scratched, and scratches due to contact with the bottom of the pan etc. are reduced.

According to a third aspect of the present invention, in particular, the content of the fluorocarbon silane in the aqueous emulsion according to the second aspect is 0.1 to 20% by weight, and the molar fraction of silicate to the fluorocarbon silane is 0.3 to 10. The fluorocarbon silane and the surfactant used to form the hydrolyzate have a weight ratio of 1: 1 to 10:
1. A fluorocarbon silane hydrolyzate-containing aqueous emulsion in which the pH of the aqueous emulsion is adjusted to 7 or more is applied to the surface of a crystallized glass substrate and dried to form a stable aqueous emulsion. You can

[0014] According to a fourth aspect of the invention, particularly the coating film of repellent according to claim 1, wherein the _{R f - (CH 2) p} -Si {- (O-CH 2 CH 2) n -OR '} ₃ (1) (R _f is a perfluoroalkyl group having 3 to 18 carbon atoms or a mixture thereof, and R'is 1 to 3 carbon atoms.
Identical or different alkyl groups, p = 2
4, and n = 2-10. ) Is produced from at least one fluorocarbon silane represented by) in the presence of a nonionic surfactant represented by C ₉ H ₁₉ —C ₆ H ₄ —O— (CH ₂ CH ₂ O) ₅₀ —H (3). a _{hydrolyzate, Si-R 4 (2)} (R is OCH _3, OCH ₂ CH _3, and _{(OCH 2 CH 2) m OCH} 3 (m = 1~1
It is at least one group selected from 0). ) A heat-resistant water-repellent coating film formed by applying and drying an aqueous emulsion containing a silicate represented by) on the surface of a crystallized glass substrate, and crystallizing the cooker top plate according to claim 1. Since it is not easily affected by the alkali ions contained in the glass and has excellent heat resistance, it is possible to effectively prevent burning. Also, since it is excellent in strength, it is less likely to be scratched, and scratches due to contact with the bottom of the pan etc. are reduced.

According to a fifth aspect of the present invention, in particular, the content of the fluorocarbon silane in the aqueous emulsion according to the fourth aspect is 0.1 to 20 wt%, and the molar ratio of silicate to the fluorocarbon silane is 0.3 to 10. The fluorocarbon silane and the surfactant used to form the hydrolyzate have a weight ratio of 1: 1 to 10:
1. A fluorocarbon silane hydrolyzate-containing aqueous emulsion in which the pH of the aqueous emulsion is adjusted to 4 or more is applied to the surface of a crystallized glass substrate and dried to form a stable aqueous emulsion. You can

According to the sixth aspect of the present invention, the top plate of the cooker is required to have high mechanical strength and high heat resistance. Therefore, the main crystal of the crystallized glass according to any one of the first to fifth aspects is particularly preferable. Is a β-quartz solid solution, and the coefficient of thermal expansion at 30 to 750 ° C. is −10 to 10 × 10 ⁻⁷ / ° C., so that thermal damage can be practically prevented. In addition,
When the coefficient of thermal expansion is out of this range, thermal damage is likely to occur due to repeated use.

In the invention according to claim 7, since the top plate of the cooker is required to have high mechanical strength and high heat resistance, the main part of the crystallized glass according to any one of claims 1 to 5 is particularly required. Since the crystal is a β-quartz solid solution and the coefficient of thermal expansion at 30 to 750 ° C is -10 to 30 × 10 ^-7 / ° C,
Practically, thermal damage can be made less likely to occur.

[0018]

Embodiments of the present invention will be described with reference to the drawings and tables.

In the present invention, the crystallized glass of the top plate which is the substrate is 0.1 to 25 μm, preferably 0.5 to 15 μm.
It has a surface roughness of Ry (JIS B0601-94). On a flat surface, the surface wears uniformly as it is used, so the surface structure containing fluorine easily deteriorates, and the antifouling function deteriorates in a short period of time, but if fine irregularities are formed Since the inner surface of the recess is less likely to be worn, the initial surface state is maintained and the antifouling function can be maintained for a long period of time. If the surface roughness is less than 0.5 μm, the above effect cannot be obtained, and if it exceeds 25 μm, contaminants enter the concave portions and are difficult to remove.

[0020] In the aqueous emulsion to form a heat-resistant water-repellent coating layer of the present invention, the hydrolyzable alkoxysilane _{compound, R f - (CH 2)} p -Si {- (O-CH 2 CH 2) n -OR '} ₃ (1), R _f is a perfluoroalkyl group having 3 to 18 carbon atoms or a mixture thereof, and a plurality of R'is the same or different alkyl groups having 1 to 3 carbon atoms. A fluorocarbon silane is used, which is a group with p = 2-4 and n = 2-10. Preferably, R _f has an average of 8 to
Mixed perfluoroalkyl groups having 12 carbon atoms, R ′ is methyl, p = 2, and n =
2 to 4. More preferably, n = 2-3. n
When is 2, the preferred fluorocarbon silane hydrolyzate is perfluoroalkylethyltris (2-
A hydrolyzate of (2-methoxyethoxy) ethoxy) silane, where when n is 3, a preferred fluorocarbon silane hydrolyzate is a hydrolyzate of perfluoroalkylethyltris (2- (2-methoxyethoxy) ethoxy) silane. It is a decomposed product. You may mix and use 2 or more types of fluorocarbon silane.

Further, the aqueous emulsion of the present invention contains a component which is copolymerized with the hydrolyzate of the fluorocarbon silane in order to improve heat resistance. Was hydrolyzed in water, from the viewpoint of solubilizing, in the present invention is represented by _{Si-R 4 (2),} R is OCH _3, OCH ₂ CH _3, and _{(OCH 2 CH 2) m OCH} 3
A silicate that is at least one group selected from (m = 1 to 10) is used. Oil-soluble Si (OCH ₃ ) ₄ or S
Dissolution of i (OCH ₂ CH ₃ ) ₄ in water has hitherto been carried out only in a water / alcohol system, but it is usually hydrolyzed and dissolved in water by stirring for 3 hours or more. From the viewpoint that the stirring time with the hydrolyzed fluorocarbon silane aqueous emulsion can be shortened and adjusted easily,
_{Si - {(OCH 2 CH 2} ) m OCH 3} 4 more preferably a water-soluble silicate represented by (m = 1~3), Si - {(CH 2 CH 2) 2 OCH
A water-soluble silicate represented by ₃ } ₄ is particularly preferable.

The surfactants used in the aqueous emulsions of the present invention form stable fluorocarbon silane hydrolysates. The emulsion keeps the alkoxysilane totally hydrolyzed and the presence of an effective amount of surfactant having an HLB value high enough to suppress the self-condensation of the hydrolyzed alkoxysilane compound. And is obtained by emulsifying an alkoxysilane that is hydrolyzable in water. The surfactant usable in the present invention can be selected from anionic type, cationic type, nonionic type, and amphoteric type. Preferred surfactants have an HLB value greater than 12, and more preferably 16
It is bigger. When using a surfactant having an HLB value of 12 to 16, it is usually necessary to incorporate a very large amount of surfactant in order to obtain a stable emulsion. As long as the above HLB value is satisfied, two or more compatible surfactants may be mixed and used.

Specifically, R_f-FH₂CH₂−O− (CH₂CH₂O)₁₁
-H, C₉H₁₉-C₆H_Four−O− (CH₂CH₂O)_{Five 0}-H and other nonions
System surfactant, R_f-CH₂CH₂SCH₂CH (OH) CH₂N (CH₃)₃+ Cl^-
Cationic surfactants such as C₁₂H_{twenty five}(OCH₂CH₂)_FourOSO₃ ^-
NH_Four ⁺, C₁₂H₂₇-C₆H_Four-SO₃ ^-Na ⁺Anionic surface activity such as
A sex agent can be given. R_fIs perfluoroalkyl
A group, usually having 3 to 18 carbon atoms. Interactivity
After applying the aqueous emulsion to the base material and drying it,
By heat aging, in the chemical structure of the surfactant,
At least the structure of the hydrophilic part is usually lost, but
It also has hydrophilic parts that are lost by heat aging between
Is preferred. The hydrophilic part of polyethylene glycol is
Since it decomposes by drying and disappears in a short time,
Include polyethylene glycol in the molecular chain of the surfactant
Examples thereof include nonionic surfactants.

The content of fluorocarbon silane in the aqueous emulsion is at least 0.1 wt%, preferably 2 to 2
It is 0 wt%, more preferably 7 to 15 wt%. If it is less than 0.1 wt%, the water repellency is insufficient, and if it is more than 20 wt%, it is difficult to obtain the stability of the aqueous emulsion. The mole fraction of silicate to fluorocarbon silane is 0.3.
Is ~ 10. If the mole fraction is less than 0.3, the heat resistance of the coating layer is insufficient, while if it is greater than 10,
The aqueous emulsion gels and the heat resistance of the coating layer is impaired. From the viewpoint of easy handling of the aqueous emulsion, in order to obtain a stable aqueous emulsion, the mole fraction of silicate to fluorocarbon silane is preferably 0.3 to 5, and 0.4 to 2
Is more preferable. The weight ratio of fluorocarbon silane to the surfactant used to form its hydrolyzate in the aqueous emulsion is from 1: 1 to 10: 1, preferably
It is 10: 2 to 10: 5, and more preferably 10: 3. If the proportion of the surfactant is too low, the aqueous emulsion cannot be kept stable, and if the proportion is too high, hydrophilic groups tend to remain on the substrate even after drying, and good water repellency cannot be provided.

In order to make the coating layer heat resistant so that it retains water repellency even after 5 hours at 350 ° C., it is necessary to adjust the pH of the aqueous emulsion to be alkaline. The higher the pH value, the higher the heat resistance, and it is preferable to adjust the pH to 11 or more. However, as a surfactant for forming a hydrolyzate of fluorocarbon silane, a nonionic interface represented by C ₉ H ₁₉ -C ₆ H ₄ -O- (CH ₂ CH ₂ O) ₅₀ -H (3) is used. When an activator is used, the heat-resistant water-repellent coating layer can be obtained by adjusting the pH of the aqueous emulsion to 4 or more. In addition, pH
Is adjusted using a suitable alkali such as aqueous ammonia. The aqueous emulsion of the present invention can contain additives such as a pigment, a biocide, an ultraviolet absorber, and an antioxidant within a range that does not affect the properties of the aqueous emulsion and the heat resistance of the coating layer.

The coating of the aqueous emulsion on the substrate is carried out by a known method such as a dipping method, a spray method or a spin coating method. When applied to a glass substrate, the dipping method is preferable because it does not impair transparency. It may be overheated to accelerate the drying process. Usually, the drying is performed in the temperature range of 100 to 300 ° C. for 1 to 24 hours. If necessary, the substrate coated with the aqueous emulsion and dried is washed with water after drying to remove the residual surfactant.

The top plate for a cooker according to the present invention includes an electromagnetic induction heating cooker for heating a cooking container placed on a cooking surface by a coil provided below the top plate to generate magnetic lines of force, and a top plate. Consisting of crystallized glass, such as an electric heating cooker that heats the object to be heated on the cooking surface by infrared rays emitted from a heating element such as a halogen heater or a nichrome heater provided under It can be used in cookers with top plates.

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.
Aqueous emulsions used in the following Examples and Comparative Examples were prepared by dissolving a surfactant in water, and then slowly adding fluorocarbon silane with stirring to suppress self-condensation of fluorocarbon silane to a hydrolyzed state. It was kept and adjusted by adding other components.

[0029] (Examples 1-3) fluorocarbons hydrolyzate used _{was, R f - (CH 2)} 2 -Si {- (O-CH 2 C
It is represented by H _{2) 2} -OCH _3}. R _f is F (CF ₂ ) _k CH ₂ C
H ₂ (k = 6, 1-2 wt%; k = 8, 62-64 wt%; k = 1
0,23 to 30 wt%; k = 12-18, 2-6 wt%). Surfactant was used nonionic surface active agents represented by _{R f -FH 2 CH 2 -O- (} CH 2 CH 2 O) 11 -H. The content in the aqueous emulsion was 30 parts by weight per 100 parts by weight of fluorocarbon silane. Tetrakis [2- (2-
(Methoxyethoxy) ethyl] silicate (Si (DEGM) ₄ )
Was used. The pH was adjusted to 10.8 by adding aqueous ammonia using a pH meter. The prepared aqueous emulsion was allowed to stand, and after 1 week, it was visually observed whether gelation or precipitation had occurred. It was stable when it was smooth like water. Next, a heat-resistant crystallized glass used for a top plate of an electromagnetic cooker was used as a base material to prepare a test piece. Surface roughness of crystallized glass used in Examples
Ry is 1.0 μm. The aqueous emulsion was applied by dip coating. Dip coating is lowered at a speed of 300 mm / min, waits 10 minutes in that state, 50 m
It was pulled up at a speed of m / min. Drying after application is 60 at 200 ℃
I went for a minute. Using the obtained test piece, the transparency of the coated surface was visually observed, and the case where it was the same as before coating was defined as “transparent”. Further, pure water was dropped on the surface of the coated substrate, and the contact angle was measured by a contact angle meter (Kyowa Interface Science). Table 1 shows the stability of the aqueous emulsion, the transparency of the coated surface, and the water repellency.

Comparative Examples 1 to 5 In Comparative Examples 1 to 3, after preparing a fluorocarbon silane hydrolyzate-containing aqueous emulsion having the same composition as in Examples 1 to 3, pH was adjusted to 2.0 using hydrochloric acid. did. In Comparative Example 4, an aqueous emulsion was prepared without adding silicate, and the pH was 10.8.
Adjusted to. Further, in Comparative Example 5, the surface roughness Ry of the crystallized glass of the substrate was set to 25 μm, and the surface treatment with the same composition as in Example 3 was performed. The stability of the aqueous emulsion, the transparency of the coated surface, and the water repellency are shown in Table 1, respectively.

[0031]

[Table 1]

In Comparative Example 5, the stain removability was compared with that in Example 3.

The stain removability was tested as follows.

After the surface of the test piece was washed with ethanol,
Salad oil 0.02g is dropped with a dropper and this is φ1.5cm.
Spread to. The test piece to which the salad oil is attached is left to stand in an electric furnace at 300 ° C for 20 minutes, taken out, cooled to room temperature, and wiped with Kimwipe. When it is completely wiped off with a dry wipe, it is marked with "○", when it is wiped off with a little force using water, it is marked with a "△", and when there is a mark even after applying a force, it is marked with "×" to remove dirt. evaluated. The results are shown in (Table 2).

[0035]

[Table 2]

In Examples 1 to 3, the water repellency of the coating layer surface was the same as that before aging even after 10 hours at 350 ° C., showing excellent heat resistance. The compositions are the same as 1 to 3, respectively, and Comparative Examples 1 to 3 in which pH is adjusted to 2.0
It can be seen that there is a significant difference in heat resistance when compared with. Further, in Comparative Example 4, even if the pH is 10.8, the adhesion of the film becomes poor unless silicate is added.

In Example 3, the stains can be removed relatively easily, but in Comparative Example 5, the trace of baking remains and it cannot be completely removed.

[0038] (Example 4 to 7) 10 wt% of _{R f - (CH 2) 2} -S
i [− (O−CH ₂ CH ₂ ) ₂ −OCH ₃ ] ₃ (R _f is F (CF ₂ ) _k CH ₂ CH ₂ 2 (k
= 6, 1-2 wt%; k = 8, 62-64 wt%; k = 10, 23-30
wt%; k = 12-18, 2-6 wt%) a mixture of perfluoroalkyl represented by the formula), 30 parts by weight of _Rf- CH ₂ CH ₂ relative to 100 parts by weight of fluorocarbon silane and 100 parts by weight of fluorocarbon silane. -O- (CH ₂ CH ₂ -O- (CH ₂ CH ₂ O) ₂₁₁ -H is a nonionic surfactant represented by tetrakis [-(so that the mole fraction of silicate to fluorocarbon silane is 1). 2-Methoxyethoxy) ethyl] silicate (Si (DEGM) ₄ ) was added to adjust the aqueous emulsion, and the pH was adjusted to 9.8, 10.0, 11.0, and 11.6 to obtain Examples 4, 5, 6, and 7, respectively. The stability of the aqueous emulsion, the transparency of the coating layer, and the water repellency are shown in (Table 3).

[0039]

[Table 3]

Examples 4 to 7 show that even if the aqueous emulsion is alkaline, the higher the pH, the more the water-repellent coating layer having improved heat resistance can be obtained.

(Examples 8 to 13) Instead of the surfactant used in Examples 1 to 3, C ₉ H ₁₉ -C ₆ H ₄ -O- (CH ₂ CH ₂ O) _50-.
A nonionic surfactant represented by H was used. further,
In Examples 8-10, after preparing the aqueous emulsion, p
H was used as it was without adjustment, and in Examples 11 to 13, pH was adjusted to 10.8 using aqueous ammonia. The results are shown in (Table 4).

[0042]

[Table 4]

(Comparative Examples 6 to 10) Comparative Examples 6 to 10 also had C ₉ H _{19
-C 6 H 4 -O- (CH 2} CH 2 O) was used nonionic surface active agents represented by ₅₀ -H. Further, in Comparative Examples 6 to 8, the pH was adjusted to 2.0 using hydrochloric acid. Comparative Examples 9 and 10 prepared aqueous emulsions without the addition of silicates, Comparative Example 10
Then the pH was adjusted to 10.8.

Example 8 and Example 11 and Comparative Example 6, Example 9 and Example 12 and Comparative Example 7, Example 10 and Example 13 and Comparative Example 8 have the same composition but different pH. in a while, from these _{comparisons, C 9 H 19 -C 6 H} 4 -O- (CH 2 CH 2 O) 50
When a surfactant represented by -H is used, the pH value is 4.0
It is shown that an excellent heat resistant water repellent coating layer can be formed by adjusting the above. In addition, Comparative Example 9
And 10 show that even if the pH is adjusted to 4.0 or higher, an excellent coating layer cannot be obtained unless silicate is added.

[0045]

As described above, according to the present invention, the coating layer obtained by adjusting the pH of the fluorocarbon silane hydrolyzate-containing aqueous emulsion on the surface of the crystallized glass forming the top plate, and then coating and drying Since the surface of the top plate has excellent heat resistance and water repellency, it is possible to provide a top plate for a cooker excellent in antifouling property.

[Brief description of drawings]

FIG. 1 is an external perspective view showing an embodiment of a cooking device according to the present invention.

[Explanation of symbols]

1 Induction cooker body 2 top plate 3 pots

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Akihiro Umeda             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 3K051 AB02 CD44                 4G059 AA01 AA15 AC19 AC22 FA01                       FA05 FA22 FB06                 4G062 AA11 BB01 MM01 NN29 QQ02

Claims (7)

[Claims] 1. A crystallized glass having a water-repellent / oil-repellent coating film on the surface of which a molecule containing a fluorocarbon group is covalently bonded, the crystallized glass surface being defined in JIS-B-0601-94. A top plate for a cooker having a surface roughness Ry of 0.5 to 25 μm. 2. A coating film of the water and oil repellency is _{R f - (CH 2) p} -Si {- (O-CH 2 CH 2) n -OR '} 3 (1) (R f is a carbon atom 3 to 18 perfluoroalkyl groups or mixtures thereof, wherein R'has 1 to 3 carbon atoms
Identical or different alkyl groups, p = 2
4, and n = 2-10. And a hydrolyzate formed from at least one fluorocarbon silane represented by the formula (1) in the presence of a surfactant, and Si-R ₄ (2) (R is OCH ₃ , OCH ₂ CH ₃ , and (OCH ₂ CH ₂ ) _m OCH ₃ (m = 1 to 1
It is at least one group selected from 0). The heat-resistant, water-repellent coating film formed by applying and drying an aqueous emulsion containing a silicate represented by the formula 1) on the surface of a crystallized glass substrate. 3. The content of the fluorocarbon silane in the aqueous emulsion is 0.1 to 20 wt%, and the mole fraction of silicate to the fluorocarbon silane is 0.3 to 10%.
And the weight ratio of the fluorocarbon silane to the surfactant used to form the hydrolyzate is 1: 1 to 10: 1 and the pH of the aqueous emulsion is
The top plate for a cooker according to claim 2, wherein the fluorocarbon silane hydrolyzate-containing aqueous emulsion having a ratio of 7 or more is applied and dried on the surface of the crystallized glass substrate. 4. A coating film of the water and oil repellency is _{R f - (CH 2) p} -Si {- (O-CH 2 CH 2) n -OR '} 3 (1) (R f is a carbon atom 3 to 18 perfluoroalkyl groups or mixtures thereof, wherein R'has 1 to 3 carbon atoms
Identical or different alkyl groups, p = 2
4, and n = 2-10. ) Is produced from at least one fluorocarbon silane represented by) in the presence of a nonionic surfactant represented by C ₉ H ₁₉ —C ₆ H ₄ —O— (CH ₂ CH ₂ O) ₅₀ —H (3). a _{hydrolyzate, Si-R 4 (2)} (R is OCH _3, OCH ₂ CH _3, and _{(OCH 2 CH 2) m OCH} 3 (m = 1~1
It is at least one group selected from 0). The heat-resistant, water-repellent coating film formed by applying and drying an aqueous emulsion containing a silicate represented by (4) on the surface of a crystallized glass substrate. 5. The content of fluorocarbon silane in the aqueous emulsion is 0.1 to 20 wt%, and the mole fraction of silicate to the fluorocarbon silane is 0.3 to 10%.
And the weight ratio of the fluorocarbon silane to the surfactant used to form the hydrolyzate is 1: 1 to 10: 1 and the pH of the aqueous emulsion is
The cooker and the top plate for a cooker according to claim 4, wherein the cooker and the cooker top plate are formed by applying and drying a fluorocarbon silane hydrolyzate-containing aqueous emulsion having a ratio of 4 or more on the surface of a crystallized glass substrate. 6. The main crystal of crystallized glass is β-quartz solid solution, and the coefficient of thermal expansion at 30 to 750 ° C. is -10 to 10 × 10.
^{It is -7} / degreeC, The top plate for cookers of Claims 1-5. 7. The main crystal of crystallized glass is β-quartz solid solution, and the coefficient of thermal expansion at 30 to 750 ° C. is -10 to 30 × 10.
^The top plate for a cooker according to claim 1, wherein the top plate has a temperature of ^-7 / ° C.