JP2007170777A - Frame for glass top plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a frame 13 capable of adhering a glass top plate 11 with superior heat-proof, water-proof, alkali adhesive-proof durability. <P>SOLUTION: This frame is a stainless steel frame 13 on which the glass top plate 11 is adhered to be assembled in a cooker 10, and a chemical conversion coating composed of oxide or hydroxide of zirconium including adsorbed water is formed on a surface of the stainless steel plate. A ratio of the adsorbed water and zirconium hydroxide to the whole chemical conversion coating is adjusted within a range of 5-95 mass%. Adhesion strength of the glass top plate/stainless steel plate is not deteriorated even when they are exposed under wet, alkaline, high-temperature atmosphere for a long time. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a stainless steel frame suitable as a member of a cooker that has excellent adhesion durability with a glass top plate for a cooker and is given an excellent clean feeling in combination with the glass top plate.

A cooker with a glass top plate is easy to wipe off, such as spilled food, is clean and easy to use, such as the ability to stably place pans on a flat glass surface. IH cooking heaters, gas stoves, etc. The penetration rate is increasing year by year.
In the gas heating cooker 10 employing the glass top plate 11 (FIG. 3), the glass top plate 11 with the opening 12 facing the burner is supported by the frame 13, and the glass top plate 11 and the frame 13 are bonded. Bonded with agent 14. The IH cooking heater does not require the opening 12.

  A heat-resistant silicone resin or the like is used for the adhesive 14, and sealing is performed between the glass top plate 11 and the frame 13 so that spillage or the like does not enter the inside of the cooking device 10. For frame 13, enamel frames have been used in the past, but they are more expensive than conventional cookers that do not have a glass top plate. Excellent stainless steel is beginning to be used. When the silverstone tone is imparted to the stainless steel frame 13, the design of the cooking device 10 is further improved.

  Stainless steel used as the glass top plate frame 13 requires heat resistance and high temperature strength to support the glass top plate 11 on which high-temperature pans, pans, etc. are temporarily placed. Sex is also required. However, a stainless steel plate whose surface is covered with a passive film mainly composed of chromium oxide has a short-term adhesive force when exposed to a high-temperature and high-humidity atmosphere even if it is bonded after being cleaned by degreasing. May decrease. Adhesive strength also decreases due to spills that occur during cooking and residual alkali detergent used during cleaning.

  When the adhesive strength is reduced, the gap between the glass top plate 11 and the stainless steel frame 13 is not covered with the glass top plate 11 until the glass top plate 11 peels off from the stainless steel frame 13. It tends to occur. Therefore, when the glass top plate frame 13 is made of a stainless steel plate, it is effective to improve the reliability of the product by using a stainless steel plate that has been surface treated with excellent heat resistance, water resistance, alkali resistance, and adhesion durability. .

  As a pretreatment to improve the adhesion durability of stainless steel plate, an organic primer such as epoxy resin, organic phosphate compound, polyacrylic acid, etc. is applied to the adhesive joint surface of the stainless steel frame 13 to be bonded to the glass top plate 11. A method is conceivable. Organic primers are effective in improving adhesion in wet and alkaline environments, but the organic components of the film decompose in use forms where hot pans and pans are repeatedly placed on the glass top plate 11 and frame 13. Even when a heat-resistant adhesive such as silicone is used, the adhesive strength cannot be maintained.

When a stainless steel frame 13 with a chromate film that does not contain organic components is bonded to the glass top plate 11 with a silicone-based heat-resistant adhesive, adhesion durability comparable to that of enamel coating is achieved even in wet, alkaline, and high-temperature environments. . However, the chromate treatment is very costly for the treatment of waste liquid containing Cr ^{6+ with} a large environmental load, and it is difficult to adopt it from the point of consideration of the environment through green procurement from the processing manufacturer.

  Chromium-free treatments using chemicals such as titanium, zirconium, molybdenum, and phosphate have been developed as chemical conversion treatments instead of chromate treatment, and improvements in paint adhesion and water-resistant adhesion are also being investigated. . The present inventors have also introduced stainless steel sheets subjected to various chromium-free treatments (Patent Documents 1 to 5).

JP 2005-120469 A JP 2000-234187 A JP 2001-89868 JP-A-7-197273 Japanese Patent No. 3302684

  As a result of investigating the characteristics of a joined body obtained by bonding a stainless steel plate treated with a coating pretreatment agent or a surface treatment agent with a silicone-based heat-resistant adhesive, a stainless steel plate provided with a chemical conversion film containing an organic component has a temperature of 500 to 150 to 200 ° C. When heated for ˜1000 hours or longer, the adhesive strength was inferior to when a solid stainless steel plate was heated under the same conditions. Moreover, an unpleasant odor was also generated due to thermal decomposition of the organic components. The stainless steel plate provided with a chemical conversion film that does not contain organic components had the same decrease in adhesive strength after the heating test as that of a solid stainless steel plate, but the adhesion durability in wet and alkaline environments was inferior to the chromate treatment level. .

  In addition, various chromium-free chemical conversion films that have been proposed so far have a coating structure that places importance on corrosion resistance on the premise that they are applied to plated steel sheets. For example, a chemical conversion film containing a large amount of soluble components for imparting self-repairing properties, or a chemical conversion film containing components other than the adhesion durability and coating film adhesion improving components. On the other hand, a stainless steel plate having excellent corrosion resistance of the material itself has not been proposed with a coating structure specialized for improving adhesion durability in all wet, alkaline, and high temperature environments without impairing the design.

  The present inventors have provided various conversion coatings on a stainless steel plate used for a glass top plate frame of a cooker, and have heat resistance, excellent enamel water resistance, and alkali resistance adhesion required for the glass top plate frame. The effect of chemical conversion film on durability was investigated and examined. As a result, it has been found that a zirconium oxide or hydroxide-based film containing no organic component is an effective chemical conversion film.

  The present invention is based on such knowledge, and by forming a chemical conversion film on the surface of the stainless steel plate, mainly composed of zirconium oxide or hydroxide containing adsorbed water and containing no organic component, heat resistance and adhesion durability An object of the present invention is to provide a frame for a stainless steel glass top plate improved in the above.

The glass top plate frame of the present invention is a stainless steel frame that supports and bonds the glass top plate and incorporates it into the cooker body. The stainless steel plate used for the frame is provided with a chemical conversion film made of zirconium oxide or hydroxide containing adsorbed water, and the ratio of adsorbed water and zirconium hydroxide in the total chemical conversion film is 5 to 90. It is adjusted to the mass% range.
Zirconium oxide or hydroxide containing adsorbed water is produced by applying an oxyzirconium salt aqueous solution to the surface of a stainless steel plate and heating and drying. For example, zirconium oxynitrate is used as the oxyzirconium salt.

Action / Effect

  The present inventors have investigated and examined various surface treatments of stainless steel sheets in order to obtain enamel heat resistance, water resistance, and alkali resistance durability required for a glass top plate frame of a cooking device. As a result, by forming a conversion coating consisting of zirconium oxide or hydroxide containing no adsorbed water and no organic components on the surface of stainless steel plate, in addition to excellent heat resistance at the hollow level, water and alkali resistant adhesion It has been found that durability is also improved.

Zirconium, which is a transition metal, acts as a binder when an oxide or hydroxide forms a three-dimensional network structure chemical conversion film, like chromium, titanium, vanadium, and the like. Moreover, the zirconium oxide film is excellent in water resistance, alkali resistance, and heat resistance. The zirconium oxide or hydroxide forming the chemical conversion film is represented by ZrO _x (OH) _y (H ₂ O) _z [2x + y = 4, Z is an arbitrary number]. It is considered that the zirconium site that is a skeleton and bonded with adsorbed water becomes amorphous and forms a continuous film.

In the present invention, the ratio of adsorbed water: H ₂ O, zirconium hydroxide: Zr (OH) _y occupying in the chemical conversion film is adjusted to a range of 5 to 95% by mass, and active sites chemically bonded to the adhesive at the time of bonding OH groups and adsorbed water to be an OH group supply source are dispersed in the chemical conversion film at a high density. Since excessive adsorption of adsorbed water and zirconium hydroxide is avoided, it is presumed that the zirconium site also has a function of forming a chemical bond such as a coordination bond when bonded to the adhesive. In this respect, high adhesive force can be expected even when compared with a film made of silicate, alumina or the like formed by a sol-gel method or the like.

  Zirconium oxide film obtained by applying an aqueous oxyzirconium salt solution and baking for a long time in the temperature range of 150 to 1000 ° C. is used as a surface protective film for glass, ceramics, etc. because it exhibits water and oil repellency. (Patent Document 6). However, since the ratio of adsorbed water and hydroxide in the film is extremely small, high adhesion durability cannot be obtained even when applied to a chemical conversion treatment of a stainless steel plate.

A composite film produced from an oxyzirconium salt aqueous solution in which an alkali metal or a water-absorbing resin is dispersed is also known as a functional thin film having an antifogging function and a soil removing function utilizing hydrophilicity (Patent Documents 7 and 8). On the contrary, in this film, since the ratio of adsorbed water and hydroxide is extremely large, even when applied to a stainless steel plate, good adhesion durability cannot be obtained.
JP 2005-68009 A JP 2003-310411 A Japanese Patent Laid-Open No. 2002-355916

In contrast, in the present invention, by providing an inorganic chemical conversion film in which the ratio of adsorbed water and zirconium hydroxide is appropriately controlled, excellent adhesion durability is imparted in any of a humid atmosphere, an alkaline atmosphere, and a high temperature environment. ing. The influence of adsorbed water and zirconium hydroxide on adhesion durability can be explained as follows.
Depending on the strength of the adhesive itself, the material strength of the adherend (stainless steel plate) itself, the strength at the adhesive interface of the adhesive layer / adherent, etc. The weakest part becomes the starting point of fracture and determines the adhesive strength. When a rigid material such as a stainless steel plate is joined with an adhesive having an appropriate adhesive strength, the most important factor that determines the adhesive strength is the strength of the adhesive interface.

  The strength of the bonding interface is determined by the sum of various bonding forces and the strength of chemical bonds such as hydrogen bonds that act between the adhesive and the adherend. It is microscopically densely bonded, in other words, the wettability of the adherend to the adhesive is important. In this regard, the zirconium oxide film is more likely to get wet with the adhesive as the hydrophilic film with more adsorbed water and zirconium hydroxide, and the higher the polarity, the higher the adhesive force due to hydrogen bonding with the adhesive is expected. . However, when a film having too high hydrophilicity is exposed to a humid atmosphere for a long period of time, water easily enters the adhesive interface at the end face of the bonded portion, and the adhesive bond at the interface is broken by heat, vibration, etc., and the adhesive strength is reduced.

  In the present invention, the chemical conversion film provided on the surface of the stainless steel plate has a three-dimensional network structure including adsorbed water, zirconium oxide and zirconium hydroxide, and the ratio of adsorbed water and zirconium hydroxide in the chemical conversion film. By properly managing the above, good wettability to the adhesive is ensured, and the individual molecules constituting the adhesive are microscopically bonded to the surface of the stainless steel plate at a high density. Moreover, since the hydrophilicity of the chemical conversion film is moderately suppressed, there is no excessive adsorbed water or zirconium hydroxide at the bonding interface. Therefore, even in a wet environment, there is no decrease in the adhesive force due to the permeated water, and high adhesion durability is maintained. The excellent water resistance, alkali resistance, and heat resistance of the zirconium oxide film itself are also one of the reasons why high adhesion durability is sustained.

  The stainless steel plate used as the frame material does not have any particular restrictions on the steel type, and any stainless steel plate of austenite, ferrite, and martensite can be used. Further, any stainless steel plate with any surface finish such as BA, 2B, 2D, HL, No. 4 can be similarly applied.

  Prior to film formation, pretreatment such as polishing, degreasing, and pickling is performed to increase the homogeneity of the chemical conversion treatment. Depending on the case, you may give the surface adjustment which improves the wettability of a stainless steel plate temporarily. In any pretreatment, a treatment liquid of a system that does not contain an organic component that causes a decrease in heat-resistant adhesion is desired. However, water-soluble components such as organic solvents such as alcohol that are completely evaporated in the drying process before chemical conversion treatment and surfactants that are completely removed in the water washing process can be used as pretreatment additives even if they are organic substances. .

A chemical conversion film having excellent adhesion durability is formed by applying a chemical conversion treatment liquid to a pretreated stainless steel plate and baking it. The chemical conversion treatment solution is prepared by dissolving or dispersing a raw material to be zirconium oxide or hydroxide in an aqueous solution. The raw materials include zirconium oxyhydroxide [ZrO (OH) ₂ · nH ₂ O], zirconium oxychloride [ZrOCl · 8H ₂ O], zirconium oxyhydroxide [ZrO (OH) Cl · H ₂ O], oxysulfuric acid Zirconium [ZrOSO ₄ · nH ₂ O], zirconium oxynitrate [ZrO (NO ₃ ) ₂ · nH ₂ O], zirconium oxycarbonate ammonium salt [(NH ₄ ) ₂ ZrO (CO ₃ ) ₂ ], zirconium oxyphosphate [ZrO There are oxyzirconium salts such as (H ₂ PO ₄ ) ₂ ], zirconium oxides such as zirconium oxide [ZrO ₂ ] and zirconium silicate [ZrSiO ₄ ], and complex oxides. Alternatively, it is dispersed as a sol.

  In order to promote dissolution of the oxyzirconium salt, the chemical conversion treatment solution may be adjusted to pH with nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid or the like, if necessary. Of the solution or dispersion containing the oxyzirconium salt, a chemical conversion treatment solution having excellent stability is used for surface modification of the stainless steel plate. However, when an excessive amount of acid is added to adjust the pH, the stainless steel plate is etched more than necessary, and the beautiful appearance is damaged. Further, there is a concern that chromium may be eluted from the stainless steel plate even in a small amount.

  Depending on the type of salt or acid used as the raw material, sulfate radicals, hydrochloric acid radicals, nitrate radicals, phosphate radicals, etc. are included in the chemical conversion treatment liquid. When the chemical conversion treatment liquid is applied to a stainless steel plate, a chemical conversion film is formed. Acid radicals may adversely affect the appearance and adhesion of stainless steel sheets. When non-oxidizing acids such as sulfuric acid and hydrochloric acid come into contact with the stainless steel plate or remain on the chemical conversion film, the passive film may be destroyed, resulting in a decrease in corrosion resistance and appearance damage. If the phosphoric acid component remains in the chemical film, depending on the type of adhesive, it may cause poor adhesion due to insufficient curing of the adhesive.

  On the other hand, nitric acid, which is an oxidizing acid, is less affected by corrosion as it is used in the passivation treatment of stainless steel sheets, so it is an inorganic chemical compound with excellent adhesion durability without degrading the original design of stainless steel sheets. A film is formed. For these reasons, a chemical conversion film formed from a chemical conversion treatment solution in which zirconium oxynitrate is dissolved or dispersed is optimal. Zirconium oxynitrate aqueous solution is the same kind as an aqueous solution in which zirconium oxide is dissolved in nitric acid, and can be easily obtained as a trade name: Zircosol ZN (manufactured by Daiichi Rare Element Chemical Industries, Ltd.). A chemical conversion treatment solution can be prepared.

  When the chemical conversion film contains silica, alumina or the like, the adhesion durability is further improved. Therefore, fine particles such as silica and alumina may be added to the chemical conversion treatment liquid. Silica, alumina, and the like are considered to have an OH group that contributes to the adhesion reaction and to be composite dispersed in the film, thereby improving the film strength and further increasing the specific surface area, resulting in improved adhesion durability. . Specifically, when 1 to 18% by mass of silica fine particles or alumina fine particles having a primary particle size of 5 to 100 nm are blended, the adhesion durability derived from the addition of silica and alumina is observed. Silica and alumina fine particles include silica sol, alumina sol, colloidal silica, fumed silica, and the like, and those having good and stable dispersibility in the chemical conversion treatment liquid are preferred.

  A chemical conversion film is formed by applying a chemical conversion treatment solution to a stainless steel plate by a roll coating method, a spin coating method, a spray method, a dipping method or the like, and baking without washing with water. If the firing temperature is too low or the firing time is too short, it becomes a hydrophilic film containing excessively adsorbed water, resulting in a decrease in moisture resistance and alkali resistance. On the other hand, if the firing temperature is too high or the firing time is too long, the amount of adsorbed water and zirconium hydroxide contained in the chemical conversion film will be significantly reduced, and after the moisture and alkali resistance tests due to the presumed lack of bonding strength with the adhesive. The adhesive strength of the remarkably decreases.

The adsorbed water and zirconium hydroxide contained in the chemical conversion coating are obtained from the XPS spectrum of oxygen O1s by ESCA. Zirconium oxide: ZrO ₂ (530 eV), zirconium hydroxide: Zr (OH) ₄ (531 eV), adsorbed water: H _It can be quantified by separating the waveform into ₂ O (532 eV). By adjusting the total proportion of adsorbed water and zirconium hydroxide in the chemical conversion film to a range of 5 to 90% by mass (preferably 20 to 80% by mass), it is excellent in a wet atmosphere, an alkaline atmosphere, and a high temperature environment. Adhesive durability can be obtained.

The amount of adsorbed water and zirconium hydroxide can be adjusted by the firing temperature and firing time. The firing conditions are preferably set in the range of firing time: 1 to 2 minutes and firing temperature (final plate temperature): 150 to 200 ° C. . The coating amount of the chemical conversion treatment liquid is preferably such that a chemical conversion film having a zirconium equivalent deposition amount of 1 mg / m ² or more (preferably 5 mg / m ² or more) is formed in order to ensure sufficient adhesion. If the coating amount is too large, the adhesion durability is saturated, and there is a concern that the coating will fall off from the stainless steel plate when continuously pressing into a frame shape as the chemical coating becomes thicker. In order to prevent the film from falling off due to thickening, the upper limit of the coating amount is preferably 200 mg / m ² (more preferably 100 mg / m ² ).

  The surface-treated stainless steel sheet, which has improved adhesion durability with a chemical film containing adsorbed water and zirconium hydroxide at a specific ratio, is processed into a frame shape, and then an adhesive is applied to the glass top plate at room temperature or by heat curing. Be joined. During processing, press oil or a protective film is used as necessary to prevent damage to the chemical conversion film or the steel sheet surface. When there is a possibility that the press oil component, the adhesive component of the protective film, etc. adhere to the chemical conversion film and cause adhesion failure, it is preferable to degrease and wash the processed stainless steel plate. The chemical film that has been fired at a low temperature tends to reduce the amount of adhesion to obtain the required adhesive strength by leaching the film components with water, so grasp the relationship between the film firing temperature and the amount of film dissolved by washing in advance. It is preferable to wash with. When the chemical film is heated and dried after washing with water, it is desirable to avoid a drying temperature that is too high so that the adsorbed water and zirconium hydroxide contained in the chemical film are reduced and the adhesive strength is not lowered.

Stainless steel sheets with a chemical conversion film composed mainly of oxides and hydroxides of zirconium have excellent adhesion durability even in wet, alkaline, and high-temperature environments without compromising the original design of stainless steel. Show.
Adhesives include emulsion adhesives for general industrial use, rubber adhesives such as chloroprene rubber, hot melt adhesives, cyanoacrylate adhesives, silicone rubber adhesives, and epoxy resins as structural adhesives. Adhesive, second generation acrylic resin adhesive (SGA), UV curable adhesive (UVA), etc., polybenzimidazole adhesive, polyimide adhesive, silicone adhesive, modified as heat resistant adhesive There are silicone adhesives, heat-resistant silicone rubber adhesives, etc.

  The adhesive is selected in consideration of required strength, application, workability, usage environment, etc., but any adhesive can be used as long as the characteristics of the adhesive itself are maintained. In particular, because it is used in cooking appliances that emphasize the difference in thermal expansion between the glass top plate and stainless steel plate, boil-out, etc., heat resistance, etc., heat-resistant silicone, silicone rubber, etc. An adhesive is preferred.

Plate thickness: 0.5 mm SUS304 stainless steel plate was used as the original plate. After alkali degreasing and pickling to such an extent that the appearance of the steel plate does not deteriorate, a chemical conversion treatment solution to which zirconium oxynitrate: 20 g / l is added is applied, and the plate is placed in an oven at an atmospheric temperature of 260 ° C. without being washed with water. Temperature: Firing was performed at a firing temperature varied in the range of 80 to 300 ° C. As a result of analyzing the chemical conversion film obtained after firing by the fluorescent X-ray method, the amount of deposited zirconium was about 70 mg / m ² .

A test piece having a diameter of 8 mm was cut out from the chemically treated stainless steel plate, and the bonding state between zirconium and oxygen contained in the chemical conversion film was observed by XPS.
As can be seen from the observation results in FIG. 1, in the bonding state of the 3d orbit of Zr, the zirconium oxide (ZrO ₂ ) shows a symmetric peak centered at the normal peak (182 eV), but the higher the firing temperature, the higher the peak. It is shifting to the energy side.

On the other hand, in the bonded state of oxygen for 1 s, zirconium oxide (ZrO ₂ ) has a peak at 530 eV, zirconium hydroxide [Zr (OH) ₄ ] has a peak at 531 eV, and adsorbed water (H ₂ O) has a peak at 532 eV. Similarly to the conclusion obtained from the observation result of the bonding state of Zr, the ratio of adsorbed water and zirconium hydroxide increases on the higher energy side as the firing temperature becomes lower.
When the waveform was separated, the ratio of adsorbed water and zirconium hydroxide was about 95% by mass in the conversion film formed at the firing temperature: 80 ° C., and the amount of adsorbed water and zirconium hydroxide in the conversion film formed at the firing temperature: 300 ° C. The ratio was about 30% by mass.

[Invention Example]
The stainless steel plate after the chemical conversion treatment was cut into a 25 mm × 100 mm test piece. Then, heat-resistant glass (crystallized glass) having the same quality as the glass top plate and having a thickness of 10 mm is cut into a test piece of the same size, and a heat curable silicone adhesive is applied at a wrap length of 12.5 mm. A spacer is placed so that the layer thickness of the steel layer becomes 800 μm, and a stainless steel plate / glass plate is bonded together, fixed with clips, and then heat-cured at 150 ° C. for 1 hour to obtain a shear tensile test piece compliant with JIS K6850 Was made.

  The shear tensile test piece was allowed to stand at room temperature: after curing for 24 hours, it was immersed in boiling water for 72 hours. Subsequently, the adhesive strength (shear tensile strength) of the adhesion test piece was measured using an autograph manufactured by Shimadzu Corporation. The measurement result of the adhesive strength is shown in FIG. 2 in relation to the ratio of adsorbed water and zirconium hydroxide obtained from the XPS analysis result of the surface-treated stainless steel sheet. As apparent from FIG. 2, the higher the firing temperature, the lower the proportion of adsorbed water and zirconium hydroxide contained in the chemical conversion film, and the lower the adhesive strength. Baking temperature: At 100 to 250 ° C., the adhesive strength was strong and the glass plate was broken. Moreover, the ratio of adsorbed water and zirconium hydroxide in the chemical conversion film: 5 to 90% by mass is necessary to ensure the required adhesive strength, and the conversion film of that ratio is generated at a firing temperature of 100 ° C. or higher. Can be read from the results of FIG.

[Comparative Example 1]
Thickness: 0.5mm SUS304 stainless steel plate is degreased and pickled, coated with chromate, coated with epoxy resin paint, baked at 200 ° C for 60 seconds, and water-cooled to dry film thickness: 15μm A resin coating was formed.
Each of the chemically treated stainless steel plate, solid stainless steel plate and stainless steel plate provided with an epoxy resin coating is formed into a glass top frame shape and bonded to the glass top plate with a thermosetting silicone adhesive. A top plate was produced by heating and curing in 1 hour. And the frying pan heated for 5 minutes with high heat was temporarily placed on the top plate for 1 minute. The heating of the frying pan and the temporary placement on the top plate were repeated 10 times at the same place on the top plate, and the occurrence of unpleasant odor due to the decomposition of the organic resin was investigated.
An unpleasant odor was not detected on the top plate made of a chemically treated stainless steel plate or a solid stainless steel plate, but an unpleasant odor occurred on a top plate made of a stainless steel plate with an epoxy resin coating on the adhesive surface side. Decomposition of the organic resin was confirmed. Moreover, an unpleasant odor became stronger every time the temporary placement operation was repeated.

[Comparative Example 2]
A top plate produced in the same manner as in Comparative Example 1 was incorporated into a stove having the shape shown in FIG.
A stock solution of alkaline detergent for range (manufactured by Kao: Range Magic Rin) was dropped on the glass top plate 11 and left for 1 month. A pan containing 5 liters of water was placed on the end of the top plate so as not to get on the frame, and the peeling state of the glass top plate 11 / frame 13 was visually observed.
There was no gap at the bonding interface between the glass top plate 11 and the frame 13 in the case of the chemical conversion treated stainless steel plate or the stainless steel plate provided with the epoxy resin coating, but when using a solid stainless steel plate, the frame 13 is removed from the adhesive. Peeling occurred and a gap was formed at the bonding interface. When hot water was spilled on the top board in this state, the hot water entered the stove.

The same stainless steel plate as in Example 1 was subjected to alkaline degreasing and pickling, and then the chemical conversion solution shown in Table 1 was applied, placed in an oven without being washed with water, and fired at a plate temperature of 150 to 200 ° C.
For comparison, the chemical conversion treatment liquid shown in Table 2 was applied to a similarly degreased and washed stainless steel plate and fired under the same conditions. In the table, test No. 16 is a conventional titanium-based chromium-free chemical conversion treatment solution containing no organic component, test Nos. 17 and 18 are conventional titanium-based chromium-free chemical conversion treatment solution containing an organic component, and test No. 19 is The chemical conversion treatment solution containing only silica sol as an adhesive improvement component and Test No. 20 each used a chromate treatment solution.

About the stainless steel plate by which chemical conversion treatment was carried out, the adhesion amount of the metal contained in a chemical conversion film was measured by the fluorescent X ray method. The ratio of adsorbed water and zirconium hydroxide in the chemical conversion film is the XPS spectrum of oxygen O1s measured by ESCA. Zirconium oxide: ZrO ₂ (530eV), zirconium hydroxide: Zr (OH) ₄ (531 eV), adsorbed water : H ₂ O As a result of waveform separation at (532 eV), all of the chemical conversion films of the present invention examples (Nos. 1 to 15) were in the range of 5 to 90% by mass.

In the same manner as in Example 1, a surface-treated stainless steel plate, a heat-resistant glass test piece and an adhesive were bonded together using an adhesive to prepare a shear tensile test piece. The shear tensile test piece was allowed to stand at room temperature: after curing for 24 hours or longer, it was subjected to the following adhesion durability test, and whether the appearance was damaged or not was determined from the observation result of the surface-treated stainless steel sheet.
[Initial shear tensile test]
The shear tensile strength of the adhesion test piece was measured using an autograph manufactured by Shimadzu Corporation, and the initial adhesive strength was evaluated by the measured value of the shear tensile strength.

[Shear tensile test after immersion in boiling water]
After the adhesion test piece was immersed in boiling water for 72 hours, the moisture resistance was evaluated from the shear tensile strength measured in the same manner as in the initial shear tensile test.
[Shear tensile test after immersion in alkaline detergent]
After the adhesion test piece was immersed for 500 hours in a commercial kitchen alkaline detergent (60 ° C.), the alkali resistance was evaluated from the shear tensile strength measured in the same manner as in the initial shear tensile test.

[Shear tensile test after standing at high temperature]
Atmosphere temperature: After leaving the adhesion test piece in an oven at 180 ° C. for 500 hours, the heat resistance was evaluated from the shear tensile strength measured in the same manner as in the initial shear tensile test.
[Visual observation of surface-treated stainless steel sheet]
Visually observe the surface-treated stainless steel sheet, ○ for specimens that have almost the same appearance as the stainless steel sheet before chemical conversion treatment, △ for specimens where slight etching marks or chemical film irregularities are detected, chemical conversion The test piece in which coloring and processing unevenness were observed remarkably by the film was evaluated as x, and the design properties of the stainless steel plate were evaluated.

  As can be seen from the investigation results in Table 3, the surface-treated stainless steel plates of Test Nos. 1 to 15 (examples of the present invention) were such that the glass plate was broken even after immersion in boiling water, after immersion in alkaline detergent, and after standing at high temperature. High adhesion was shown. Regarding the design properties, etching marks and slight processing unevenness were detected in part, but all maintained the same appearance as the original plate.

On the other hand, Comparative Example 16 subjected to titanium-based chromium-free chemical conversion treatment and Comparative Example 19 applied only with silica sol have high initial adhesive strength, but after dipping in boiling water or alkaline detergent, the adhesive strength is greatly increased. It was falling.
In Comparative Examples 17 and 18 provided with a chemical film containing an organic resin and a large amount of organic components, the adhesive strength after immersion in boiling water or an alkaline detergent was sufficient, but the adhesive strength after standing at high temperature was greatly reduced. Was. The significant decrease in the adhesive strength is considered to be caused by the decomposition of the organic component, and was lower than that of Comparative Example 21 in which the untreated stainless steel plate was bonded.
In Comparative Example 20 provided with the chromate film, Cr ⁶⁺ harmful to the environment was detected although the adhesion durability was excellent. A yellowish surface attributed to Cr ⁶⁺ was observed and the design was poor.

  As described above, the glass top plate frame of the present invention adheres the glass top plate with a strong adhesive force, and adds the beautiful appearance inherent to stainless steel to the cooker provided with the glass top plate. The adhesive strength of the stainless steel plate / glass top plate does not decrease much even when the bonded portion is exposed to a humid atmosphere, an alkali atmosphere, or a high temperature atmosphere. Moreover, since no organic resin component is used, no unpleasant odor is generated even when exposed to a high temperature atmosphere. Therefore, the design and cleanliness of both the glass top plate and the stainless steel plate are superimposed, and a cooker with high quality reliability at the enamel product level is provided.

A graph showing the XPS diffraction results of the conversion coating used to determine the bonding state between zirconium and oxygen Graph showing the effect of the firing temperature of the conversion coating on the total ratio of adsorbed water and zirconium hydroxide and the bond strength Schematic perspective view of a cooker with a glass top

Explanation of symbols

10: Cooker 11: Glass top 12: Opening for burner 13: Stainless steel frame 14: Adhesive

Claims (4)

  It is a frame that attaches the glass top plate and assembles it to the main body of the cooker, and is made of a stainless steel plate provided with a chemical conversion film made of zirconium oxide or hydroxide containing adsorbed water. A glass top plate frame, wherein the ratio of water and zirconium hydroxide is in the range of 5 to 90% by mass.   The glass top plate frame according to claim 1, wherein the zirconium oxide or hydroxide containing adsorbed water is produced from an aqueous oxyzirconium salt solution.   The glass top plate frame according to claim 2, wherein the oxyzirconium salt is zirconium oxynitrate.   The glass top plate frame according to claim 1, wherein silica and / or alumina fine particles are dispersed in the chemical conversion film.

Images