Microcrystalline glass heating plate, preparation method thereof and heating device

Abstract

The application relates to a microcrystalline glass heating plate, a preparation method thereof and a heating device. The preparation method of the microcrystalline glass heating plate comprises the following steps: covering heating ink containing graphene and glass powder on a first microcrystalline glass to form a liquid film; performing sintering treatment on the liquid film to form a heating layer; and performing packaging treatment on the heating layer to prepare the microcrystalline glass heating plate; wherein the sintering treatment comprises the following steps: through gradient temperature rising treatment, the liquid film is heated to a sintering temperature, is kept warm for 25 min to 35 min, and is subjected to gradient temperature falling treatment; the sintering treatment satisfies the following conditions: (1) the temperature rising time at a temperature higher than 400 DEG C is not more than 30 min; (2) the sintering temperature is 40 DEG C to 60 DEG C lower than the softening point of the first microcrystalline glass; and (3) the sintering temperature is 150 DEG C to 200 DEG C higher than the initial melting temperature of the glass powder. The method can obtain the microcrystalline glass heating plate with stable heating performance and good bonding strength.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heating plates, in particular to a microcrystalline glass heating plate, a preparation method thereof and a heating device. BACKGROUND

[0002] A heating plate is a heating assembly made by covering a heating ink on a glass substrate and then performing sintering, drying or curing processes. The heating plate can be used to prepare heating devices such as tunnel furnaces and electric furnaces. The heating ink usually contains conductive fillers such as metal powder or carbon materials. Compared with metal powder such as silver powder, the heating ink with carbon materials as conductive fillers has the advantage of low cost.

[0003] Among many carbon materials, graphene is known as the "King of New Materials" and has excellent electrical conductivity and thermal conductivity, good thermal stability and high heating efficiency. Compared with carbon black, graphene has high resistance to high-temperature oxidation and can withstand 450℃ high temperature for a short time in an oxygen environment. However, when graphene-based heating ink is processed into a heating plate by high-temperature sintering, the sheet resistance is likely to increase, the heating layer is likely to crack or fall off, the heating temperature of the heating plate is likely to decay, and it is difficult to apply to high-temperature heating environments above 500℃. SUMMARY

[0004] Therefore, it is necessary to provide a microcrystalline glass heating plate, a preparation method thereof and a heating device to overcome the problems that the sheet resistance of a graphene-based heating ink is likely to increase when processed into a heating plate by high-temperature sintering, the heating layer is likely to crack or fall off, the heating temperature of the heating plate is likely to decay, and it is difficult to apply to high-temperature heating environments above 500℃.

[0005] The above object of the present application is achieved by the following technical solutions:

[0006] In a first aspect, the present application provides a preparation method of a microcrystalline glass heating plate, comprising the following steps:

[0007] covering a heating ink containing graphene and glass powder on the first microcrystalline glass to form a liquid film;

[0008] sintering the liquid film to form a heating layer;

[0009] packaging the heating layer to prepare the microcrystalline glass heating plate;

[0010] The sintering process comprises the following steps: heating the liquid film to a sintering temperature by gradient heating, keeping the temperature for 25min to 35min, and performing gradient cooling;

[0011] The sintering process satisfies:

[0012] (1) the temperature rising time at a temperature higher than 400℃ is not more than 30 min;

[0013] (2) the sintering temperature is 40℃-60℃ lower than the softening point of the first glass-ceramic;

[0014] (3) the sintering temperature is 150℃-200℃ higher than the initial melting temperature of the glass powder.

[0015] In one embodiment, the sintering temperature is 540℃-560℃.

[0016] In one embodiment, the glass powder satisfies one or more of the following conditions:

[0017] (1) the initial melting temperature of the glass powder is 350℃-400℃;

[0018] (2) the sintering temperature of the glass powder is 500℃-600℃;

[0019] (3) the thermal expansion coefficient of the glass powder is ≤100×10 -7 / K.

[0020] In one embodiment, the gradient temperature rising process comprises the following steps:

[0021] heating at 100℃-150℃ for 5-10 min;

[0022] heating at 300℃-350℃ for 5-10 min;

[0023] ramping up to the sintering temperature at a rate of 400℃ / h-500℃ / h.

[0024] In one embodiment, the gradient temperature falling process has a falling rate of 50℃ / h-200℃ / h.

[0025] In one embodiment, the heat generating layer is subjected to a packaging process, comprising the following steps:

[0026] covering the sealing glue on the first glass-ceramic to form an adhesive layer surrounding the heat generating layer;

[0027] covering a second glass-ceramic on the heat generating layer and the adhesive layer, and subjecting to a curing process to prepare the glass-ceramic heat generating plate.

[0028] In one embodiment, one or more of the following conditions are satisfied:

[0029] (1) the temperature of the curing process is 200℃-250℃;

[0030] (2) the curing treatment time is 50-60 min.

[0031] In one embodiment, the method for covering the heat-generating ink containing graphene and glass powder on the first microcrystalline glass comprises one or more of screen printing, blade coating, brush coating, spin coating and spraying.

[0032] In one embodiment, the heat-generating ink further comprises a binder, a dispersant, a defoaming agent and a leveling agent.

[0033] In one embodiment, the heat-generating ink comprises the following raw materials by mass:

[0034] the glass powder 20-40 parts,

[0035] the graphene 5-20 parts,

[0036] the binder 40-60 parts,

[0037] the dispersant 1-5 parts,

[0038] the defoaming agent 0.1-1 part, and

[0039] the leveling agent 0.1-1 part.

[0040] In a second aspect of the present application, a microcrystalline glass heat-generating plate is provided, which is prepared by the above-mentioned method.

[0041] In a third aspect of the present application, a heating device is provided, which comprises the above-mentioned microcrystalline glass heat-generating plate.

[0042] The present application has the following beneficial effects:

[0043] The first microcrystalline glass is used as the substrate of the heating plate. Compared with ordinary glass and quartz glass, the first microcrystalline glass has a thermal expansion coefficient and a softening point close to those of the glass powder, high mechanical strength, good thermal stability, and higher thermal fusion bonding strength with the glass powder. The prepared heating plate has better bonding strength. During the sintering process, by controlling the parameters such as heating time, holding time and sintering temperature, the thermal oxidation of graphene in the high-temperature oxygen environment can be prevented, the resistance of the heating plate is prevented from rising to reduce the heating performance, and the thermal fusion bonding between the glass powder and the first microcrystalline glass is facilitated, thereby improving the bonding strength of the heating plate. In addition, through the packaging process, the thermal oxidation of graphene during the heating process can be avoided, and the substantial attenuation of the heating performance is prevented; through the gradient heating treatment and the gradient cooling treatment, the peeling or cracking of the heating layer caused by the difference in the thermal expansion coefficient can be prevented. Therefore, the preparation method provided in the present application can obtain a microcrystalline glass heating plate with stable heating performance and good bonding strength, which can continuously heat at a heating temperature of 500 DEG C for 12 months without attenuation of the heating performance. DETAILED DESCRIPTION

[0044] To make the above objectives, features and advantages of the present application more apparent, the specific embodiments of the present application are described in detail below. In the following description, a large number of specific details are set forth in order to provide a sufficient understanding of the present application. However, the present application can be implemented in many different ways other than those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the present application, so the present application is not limited to the specific embodiments disclosed below.

[0045] In addition, the terms "first", "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise specifically limited.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used in the specification of the present application are only for the purpose of describing the specific embodiments of the present application, and are not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0047] The first aspect of the application provides a preparation method of a microcrystalline glass heating plate to solve the problem that the sheet resistance of a graphene-based heating ink is prone to increase when the heating ink is processed into a heating plate through high-temperature sintering, the formed heating layer is prone to breakage or peeling, the heating temperature of the heating plate is prone to decay, and the heating plate is difficult to be applied to a high-temperature heating environment above 500℃.

[0048] In some embodiments, the preparation method of the microcrystalline glass heating plate comprises the following steps:

[0049] covering the heating ink containing graphene and glass powder on the first microcrystalline glass to form a liquid film;

[0050] sintering the liquid film to form a heating layer;

[0051] packaging the heating layer to prepare the microcrystalline glass heating plate;

[0052] The sintering process comprises the following steps: through gradient temperature rising treatment, the liquid film is heated to a sintering temperature, and the temperature is kept for 25min to 35min, and then gradient temperature reduction treatment is performed.

[0053] The sintering process satisfies:

[0054] (1) the temperature rising time at a temperature higher than 400℃ is not more than 30min;

[0055] (2) the sintering temperature is 40℃ to 60℃ lower than the softening point of the first microcrystalline glass;

[0056] (3) the sintering temperature is 150℃ to 200℃ higher than the initial melting temperature of the glass powder.

[0057] It can be understood that the thermal expansion coefficient of ordinary glass is (80-100)×10 -7 / K, but its mechanical strength is low, it is easy to break under stress, and it is easy to burst at high temperature. The thermal expansion coefficient of quartz glass is (4-6)×10 -7 / K, but its thermal expansion coefficient is too low, the softening point is above 1600℃, and it is difficult to be hot-melt combined with the glass powder in the heating ink, resulting in low bonding strength of the heating plate. Microcrystalline glass, also known as glass ceramic, is a kind of polycrystalline solid material containing a large amount of microcrystalline phase and glass phase, and its thermal expansion coefficient is (10-20)×10 -7 / K, and the softening point is about 600℃, which is matched with the thermal expansion coefficient and softening point of the glass powder. At the same time, the mechanical strength of microcrystalline glass is high, the wear resistance is good, and it has good chemical stability and thermal stability, and can also maintain high mechanical strength in high-temperature environment.

[0058] The first microcrystalline glass is used as the substrate of the heating plate. Compared with ordinary glass and quartz glass, the first microcrystalline glass has a thermal expansion coefficient and a softening point close to those of the glass powder, high mechanical strength, good thermal stability, and higher thermal fusion bonding strength with the glass powder. The prepared heating plate has better bonding strength. During the sintering process, by controlling the parameters such as heating time, holding time, and sintering temperature, the thermal oxidation of graphene in an oxygen-containing environment at high temperature can be prevented, the resistance of the heating plate can be prevented from rising to reduce the heating performance, and the thermal fusion bonding between the glass powder and the first microcrystalline glass can be promoted to improve the bonding strength of the heating plate. In addition, through the packaging process, the thermal oxidation of graphene during the heating process can be avoided, and the substantial attenuation of the heating performance can be prevented. Through the gradient heating and gradient cooling processes, the peeling or cracking of the heating layer caused by the difference in the thermal expansion coefficient can be prevented. Therefore, the preparation method provided in the application can obtain a microcrystalline glass heating plate with stable heating performance and good bonding strength, which can continuously heat at a heating temperature of 500℃ for 12 months without attenuation of the heating performance.

[0059] Understandably, the holding time in the sintering process is 25 min to 35 min, including but not limited to 25 min, 26 min, 27 min, 28 min, 29 min, 30 min, 31 min, 32 min, 33 min, 34 min, and 35 min. Preferably, the holding time is 30 min.

[0060] Understandably, graphene will rapidly oxidize in an oxygen-containing environment above 400℃, so the heating time at a temperature higher than 400℃ is not more than 30 min. Preferably, the heating time at a temperature higher than 350℃ is not more than 30 min.

[0061] Understandably, the sintering temperature is 40℃ to 60℃ lower than the softening point of the first microcrystalline glass, including but not limited to 40℃, 42℃, 44℃, 46℃, 48℃, 50℃, 52℃, 54℃, 56℃, 58℃, and 60℃. Preferably, the sintering temperature is 50℃ lower than the softening point of the first microcrystalline glass.

[0062] Understandably, the sintering temperature is 150℃ to 200℃ higher than the initial melting temperature of the glass powder, including but not limited to 150℃, 155℃, 160℃, 165℃, 170℃, 175℃, 180℃, 185℃, 190℃, 195℃, and 200℃. Preferably, the sintering temperature is 200℃ higher than the initial melting temperature of the glass powder.

[0063] Optionally, the sintering temperature is 540℃~560℃, including but not limited to: 540℃, 542℃, 544℃, 546℃, 548℃, 550℃, 552℃, 554℃, 556℃, 558℃, 560℃. Preferably, the sintering temperature is 550℃.

[0064] Optionally, the softening point of the first glass-ceramic is 580℃~680℃, including but not limited to: 580℃, 590℃, 600℃, 610℃, 620℃, 630℃, 640℃, 650℃, 660℃, 670℃, 680℃. Preferably, the softening point of the first glass-ceramic is 600℃~630℃.

[0065] Optionally, the initial melting temperature of the glass powder is 350℃~400℃, including but not limited to: 350℃, 355℃, 360℃, 365℃, 370℃, 375℃, 380℃, 385℃, 390℃, 395℃, 400℃.

[0066] Optionally, the sintering temperature of the glass powder is 500℃~600℃, including but not limited to: 500℃, 510℃, 520℃, 530℃, 540℃, 550℃, 560℃, 570℃, 580℃, 590℃, 600℃. Preferably, the sintering temperature of the glass powder is 500℃~580℃.

[0067] Optionally, the coefficient of thermal expansion of the glass powder is ≤100×10 -7 / K, including but not limited to: 100×10 -7 / K, 90×10 -7 / K, 80×10 -7 / K, 70×10 -7 / K, 60×10 -7 / K, 50×10 -7 / K, 40×10 -7 / K, 30×10 -7 / K, 20×10 -7 / K, 10×10 -7 / K. Preferably, the coefficient of thermal expansion of the glass powder is ≤80×10 -7 / K. More preferably, the coefficient of thermal expansion of the glass powder is ≤60×10 -7 / K.

[0068] Optionally, the gradient temperature treatment comprises the following steps:

[0069] heating at 100℃~150℃ for 5min~10min;

[0070] heating at 300℃~350℃ for 5min~10min;

[0071] The temperature is raised to the sintering temperature at a temperature raising rate of 400-500℃ / h.

[0072] The water in the liquid film can be removed by heating at 100-150℃ for 5-10 minutes, and the organic matter in the liquid film can be removed by heating at 300-350℃ for 5-10 minutes. The temperature raising rate of 400-500℃ / h can shorten the temperature raising time and prevent the graphene in the liquid film from being oxidized by heat.

[0073] It can be understood that the heating temperature when heating at 100-150℃ for 5-10 minutes includes but is not limited to 100℃, 110℃, 120℃, 130℃, 140℃, and 150℃, and the heating time includes but is not limited to 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, and 10 minutes.

[0074] It can be understood that the heating temperature when heating at 300-350℃ for 5-10 minutes includes but is not limited to 300℃, 310℃, 320℃, 330℃, 340℃, and 350℃, and the heating time includes but is not limited to 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, and 10 minutes.

[0075] It can be understood that the temperature raising rate when raising the temperature to the sintering temperature at a temperature raising rate of 400-500℃ / h includes but is not limited to 400℃ / h, 410℃ / h, 420℃ / h, 430℃ / h, 440℃ / h, 450℃ / h, 460℃ / h, 470℃ / h, 480℃ / h, 490℃ / h, and 500℃ / h.

[0076] Optionally, the temperature lowering rate of the gradient temperature lowering treatment is 50-200℃ / h, including but not limited to 50℃ / h, 60℃ / h, 70℃ / h, 80℃ / h, 90℃ / h, 100℃ / h, 110℃ / h, 120℃ / h, 130℃ / h, 140℃ / h, 150℃ / h, 160℃ / h, 170℃ / h, 180℃ / h, 190℃ / h, and 200℃ / h.

[0077] Optionally, the heat generating layer is subjected to a packaging treatment, including the following steps:

[0078] The sealing glue is covered on the first microcrystalline glass to form an adhesive layer surrounding the heat generating layer;

[0079] The second microcrystalline glass is covered on the heat generating layer and the adhesive layer, and is subjected to a curing treatment to prepare a microcrystalline glass heat generating plate.

[0080] Optionally, the temperature of the curing treatment is 200-250°C, including but not limited to 200°C, 210°C, 220°C, 230°C, 240°C, 250°C. Preferably, the temperature of the curing treatment is 200-220°C.

[0081] Optionally, the time of the curing treatment is 50-60min, including but not limited to 50min, 52min, 54min, 56min, 58min, 60min. Preferably, the time of the curing treatment is 55-60min.

[0082] Optionally, the method of covering the graphene and glass powder-containing heat-generating ink on the first microcrystalline glass comprises one or more of screen printing, blade coating, brush coating, spin coating, and spraying. Preferably, the method of covering the graphene and glass powder-containing heat-generating ink on the first microcrystalline glass is screen printing.

[0083] In some embodiments, the heat-generating ink further comprises a binder, a dispersant, a defoaming agent, and a leveling agent.

[0084] Optionally, the heat-generating ink comprises the following mass fractions of raw materials:

[0085] glass powder 20-40 parts,

[0086] graphene 5-20 parts,

[0087] binder 40-60 parts,

[0088] dispersant 1-5 parts,

[0089] defoaming agent 0.1-1 part, and

[0090] leveling agent 0.1-1 part.

[0091] Optionally, the number of layers of the graphene is ≤10 layers, including but not limited to 10 layers, 9 layers, 8 layers, 7 layers, 6 layers, 5 layers, 4 layers, 3 layers, 2 layers, 1 layer. Preferably, the number of layers of the graphene is ≤5 layers.

[0092] Optionally, the flake diameter D50 of the graphene is ≤10μm, including but not limited to 10μm, 9μm, 8μm, 7μm, 6μm, 5μm, 4μm, 3μm, 2μm, 1μm. The D50 is also known as the median diameter or median particle size, which refers to the particle size corresponding to the cumulative percentage of the sample reaching 50%.

[0093] Optionally, the specific surface area of the graphene is ≥250m 2 / g, including but not limited to 250m 2 / g, 280m 2 / g, 300m2 / g, 320 m 2 / g, 350 m 2 / g, 380 m 2 / g, 400 m 2 / g, 450 m 2 / g, 500 m 2 / g.

[0094] Optionally, the binder comprises a non-ionic cellulose aqueous solution, which is an aqueous film-forming material having a dispersing wetting effect on the powder, and can be completely decomposed without residue at 300℃.

[0095] Optionally, the non-ionic cellulose ether comprises one or more of methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose and hydroxyethyl methyl cellulose. Preferably, the non-ionic cellulose ether comprises one or more of hydroxypropyl methyl cellulose and hydroxyethyl methyl cellulose.

[0096] Optionally, the mass fraction of the non-ionic cellulose ether in the binder is 2% to 5%, including but not limited to 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%.

[0097] Optionally, the viscosity of the binder at 20℃ is 1000 cP·s to 20000 cP·s, including but not limited to 1000 cP·s, 2000 cP·s, 3000 cP·s, 4000 cP·s, 5000 cP·s, 6000 cP·s, 7000 cP·s, 8000 cP·s, 9000 cP·s, 10000 cP·s, 12000 cP·s, 15000 cP·s, 18000 cP·s, 20000 cP·s. Preferably, when the mass fraction of the non-ionic cellulose ether is 2%, the viscosity of the binder at 20℃ is 1000 cP·s to 5000 cP·s; when the mass fraction of the non-ionic cellulose ether is 5%, the viscosity of the binder at 20℃ is 10000 cP·s to 20000 cP·s. More preferably, the binder is a hydroxypropyl methyl cellulose aqueous solution, the mass fraction of the hydroxypropyl methyl cellulose is 2%, and the viscosity at 20℃ is 4000 cP·s.

[0098] Optionally, the special dispersant for graphene comprises one or more of polyurethane dispersants, polyamide dispersants and polyacrylate dispersants. Among them, the glass powder has a low oil absorption value and is easy to be wetted, while the specific surface area of graphene is large and the oil absorption value is high, so a high molecular polymer with a graphene-philic functional group should be selected as the dispersant.

[0099] Optionally, the defoaming agent comprises a polyether-modified silicone-based defoaming agent. The defoaming agent is used to expel the tiny bubbles inside the liquid film during the surface drying process, so that the heat-generating layer is tightly combined, and the undesirable surface state after high-temperature sintering is avoided.

[0100] Optionally, the leveling agent comprises one or more of an acrylic leveling agent and a silicone-based leveling agent. The leveling agent is used to make the surface of the liquid film flat, so that the thickness of the heat-generating layer after sintering is uniform, the state is beautiful, and good square resistance uniformity is obtained.

[0101] Optionally, the preparation method of the heat-generating ink comprises the following steps: mixing the binder, the dispersant, the defoaming agent, and the leveling agent, adding the glass powder and the graphene at a speed of 500 rpm to 800 rpm, and dispersing at a speed of 2000 rpm to 2500 rpm for 20 min to obtain a slurry; grinding the slurry until the fineness is ≤10 μm to obtain the heat-generating ink.

[0102] In a second aspect of the present application, a microcrystalline glass heat-generating plate is provided, which is prepared by the above-mentioned preparation method of the microcrystalline glass heat-generating plate.

[0103] In some embodiments, the microcrystalline glass heat-generating plate comprises a first microcrystalline glass, a heat-generating layer, and a second microcrystalline glass which are sequentially stacked, and a sealing layer which is arranged between the first microcrystalline glass and the second microcrystalline glass and surrounds the heat-generating layer.

[0104] Optionally, the thickness of the first microcrystalline glass and the thickness of the second microcrystalline glass are each independently 2 mm to 6 mm, preferably 4 mm.

[0105] Optionally, the thickness of the heat-generating layer is 30 μm to 40 μm, including but not limited to 30 μm, 32 μm, 34 μm, 36 μm, 38 μm, and 40 μm.

[0106] Optionally, the square resistance of the heat-generating layer is 50 Ω / □ to 70 Ω / □, including but not limited to 50 Ω / □, 52 Ω / □, 54 Ω / □, 56 Ω / □, 58 Ω / □, 60 Ω / □, 62 Ω / □, 64 Ω / □, 66 Ω / □, 68 Ω / □, and 70 Ω / □.

[0107] In a third aspect of the present application, a heating device is provided, which comprises the above-mentioned microcrystalline glass heat-generating plate.

[0108] Optionally, the heating device comprises one or more of a tunnel furnace, an electric furnace, and a muffle furnace.

[0109] The present application will be further described in detail below in conjunction with specific embodiments.

[0110] In the following specific examples and comparative examples, the raw materials used, unless otherwise specified, are commercially available products; the instruments used, unless otherwise specified, are commercially available products; the processes used, unless otherwise specified, are routinely selected by those skilled in the art. The sources of some raw materials are as follows:

[0111] Glass Powder Ami Micro-nano New Materials (Guangzhou) Co., Ltd. FD56, initial melting temperature 395℃, linear expansion coefficient 78x10 -7 / K, oil absorption value 10cm 3 / 100g~20cm 3 / 100g.

[0112] Graphene is selected from at least one of the following products: Changzhou Sixth Element Material Technology Co., Ltd. SE1232, specific surface area 260m 2 / g~350m 2 / g, D50<10μm; Suzhou Beikona Nanometer Technology Co., Ltd. JCHQGP high-quality few-layer graphene powder, number of layers 3, specific surface area 420m 2 / g~550m 2 / g, D50<10μm.

[0113] The binder is selected from at least one of the following products: an aqueous solution of hydroxypropyl methyl cellulose with a concentration of 2% and a viscosity of 4000cP·s at 20℃ from Shandong Gomes Chemical Co., Ltd.; an aqueous solution of hydroxypropyl methyl cellulose with a concentration of 2% and a viscosity of 4000cP·s at 20℃ from Shandong Yiteng New Material Co., Ltd.

[0114] The aqueous dispersant is selected from at least one of the following commercially available products: Guangzhou Yansili Chemical Co., Ltd. YG-210 aqueous graphite slurry super dispersant; Shanghai Deruyoude Trading Co., Ltd. B6090 special dispersant for water-based graphene conductive and thermal conductive coating.

[0115] The aqueous defoaming agent is selected from at least one of the following commercially available products: BYK-345 leveling agent BYK-345; WINCRETEGOSURFYNOL-485W water-based ink low viscosity wetting leveling agent.

[0116] The aqueous leveling agent is selected from at least one of the following commercially available products: BYK052 auxiliary industrial water-based defoaming agent; WINCRETEGEOTEGO AIREX901W silicone water-based defoaming agent.

[0117] Example 1

[0118] (1) The formula of the heat-generating ink of the present example is shown in Table 1.

[0119] Table 1. Formulation of heat-generating ink of Examples 1-5 (unit: mass parts)

[0120]

[0121] (2) Preparation of the heating ink: the bonding agent, dispersing agent, leveling agent and defoaming agent were added into the can, which was placed in a high-speed mixer, and the glass powder and graphene were added at a speed of 500 rpm-800 rpm and dispersed at a speed of 2000 rpm-2500 rpm for 20 min to obtain a slurry; the slurry was ground by a three-roll machine for 2-3 times until the fineness was less than 5 μm as tested by a doctor blade fineness gauge.

[0122] (3) Preparation of the glass-ceramic heating plate: the first glass-ceramic with high-temperature-resistant sintered silver electrode on the surface was taken, a silk screen printing screen plate with a printing area of 10 cm x 10 cm and a mesh diameter of 200 mesh was used to print the heating ink on the first glass-ceramic to form a liquid film.

[0123] The liquid film was subjected to the following sintering treatment to form a heating layer:

[0124] The liquid film was placed in an oven and baked at 120°C for 5 min to completely volatilize the water in the liquid film;

[0125] The liquid film was transferred into a muffle furnace and baked at 350°C for 10 min to completely decompose the organic matter in the liquid film;

[0126] The temperature was raised from 350°C to 550°C at a rate of 400°C / h, i.e. the heating time was 30 min, so that the glass powder in the liquid film was gradually melted and the gas was discharged; the temperature was kept at 550°C for 30 min, and then cooled to room temperature at a rate of 3°C / min.

[0127] The Krytox® K5800 was coated on the first glass-ceramic to form a bonding layer around the heating layer; the second glass-ceramic was covered on the heating layer and the bonding layer, and the silver electrode was exposed; the sample was placed at room temperature for 24 h and heated at 200°C for 60 min to completely cure the bonding layer to form a sealing layer, thereby obtaining the glass-ceramic heating plate.

[0128] Example 2

[0129] This example is basically the same as Example 1, except that the formula of the heating ink is different. As shown in Table 1, the mass ratio of the glass powder to graphene in the heating ink is 1:0.8.

[0130] Example 3

[0131] This example is basically the same as Example 1, except that the formula of the heating ink is different. As shown in Table 1, the mass ratio of the glass powder to graphene in the heating ink is 1:0.6.

[0132] Example 4

[0133] This example is basically the same as Example 1, except that the formulation of the heat generating ink. As can be seen from Table 1, the mass ratio of glass powder and graphene in the heat generating ink is 1:0.4.

[0134] Example 5

[0135] This example is basically the same as Example 1, except that the formulation of the heat generating ink. As can be seen from Table 1, the mass ratio of glass powder and graphene in the heat generating ink is 1:0.2.

[0136] In addition, the area of the heat generating layer of this example is reduced from 10 cm x 10 cm to 5 cm x 5 cm.

[0137] Comparative Example 1

[0138] This comparative example is basically the same as Example 1, except that the heat generating layer is not encapsulated, i.e. there is no second microcrystalline glass covering the heat generating layer, and there is no sealing layer formed by curing the sealing glue around the heat generating layer.

[0139] Comparative Example 2

[0140] This comparative example is basically the same as Example 1, except that the graphene in the heat generating ink is replaced with the same mass of carbon black, and the carbon black is selected from the carbon black powder of Timcal Super P Li.

[0141] Comparative Example 3

[0142] This comparative example is basically the same as Example 1, except for the sintering process, which is as follows:

[0143] The liquid film is subjected to the following sintering process to form the heat generating layer:

[0144] Place in an oven and bake at 120°C for 5 min to completely volatilize the water in the liquid film;

[0145] Transfer to a muffle furnace and bake at 350°C for 10 min to completely decompose the organic matter in the liquid film;

[0146] Increase the temperature from 350°C to 550°C at a rate of 200°C / h, i.e. the temperature increasing time is 60 min, to gradually melt the glass powder in the liquid film and discharge the gas; keep the temperature at 550°C for 30 min, and cool to room temperature at a rate of 3°C / min.

[0147] Comparative Example 4

[0148] The comparative example is basically the same as example 1, except for the sintering treatment, the specific steps are as follows:

[0149] The liquid film is subjected to the following sintering treatment to form a heat generating layer:

[0150] Place in an oven and bake at 120°C for 5 min to completely volatilize the water in the liquid film;

[0151] Transfer to a muffle furnace and bake at 350°C for 10 min to completely decompose the organic matter in the liquid film;

[0152] Increase the temperature from 350°C to 550°C at a rate of 133.33°C / h, i.e. the temperature increasing time is 90 min, to gradually melt the glass powder in the liquid film and discharge gas; keep at 550°C for 30 min and cool to room temperature at a rate of 3°C / min.

[0153] Comparative Example 5

[0154] The comparative example is basically the same as example 1, except for the sintering treatment, the specific steps are as follows:

[0155] The liquid film is subjected to the following sintering treatment to form a heat generating layer:

[0156] Place in an oven and bake at 120°C for 5 min to completely volatilize the water in the liquid film;

[0157] Transfer to a muffle furnace and bake at 350°C for 10 min to completely decompose the organic matter in the liquid film;

[0158] Increase the temperature from 350°C to 550°C at a rate of 100°C / h, i.e. the temperature increasing time is 120 min, to gradually melt the glass powder in the liquid film and discharge gas; keep at 550°C for 30 min and cool to room temperature at a rate of 3°C / min.

[0159] Comparative Example 6

[0160] The comparative example is basically the same as example 1, except for the sintering treatment, the specific steps are as follows:

[0161] The liquid film is subjected to the following sintering treatment to form a heat generating layer:

[0162] Place in an oven and bake at 120°C for 5 min to completely volatilize the water in the liquid film;

[0163] Transfer to a muffle furnace and bake at 350°C for 10 min to completely decompose the organic matter in the liquid film;

[0164] The liquid film is placed in an oven and baked at 120°C for 5 min to completely evaporate the water in the liquid film.

[0165] Comparative Example 7

[0166] This comparative example is basically the same as Example 1, except for the sintering treatment, and the specific steps are as follows:

[0167] The liquid film is subjected to the following sintering treatment to form a heat generating layer:

[0168] The liquid film is placed in an oven and baked at 120°C for 5 min to completely evaporate the water in the liquid film.

[0169] The liquid film is placed in a muffle furnace and baked at 350°C for 10 min to completely decompose the organic matter in the liquid film.

[0170] The liquid film is heated at a rate of 400°C / h from 350°C to 550°C, i.e. the heating time is 30 min, to gradually melt the glass powder in the liquid film and discharge the gas; it is kept at 550°C for 20 min, and cooled to room temperature at a rate of 3°C / min.

[0171] Comparative Example 8

[0172] This comparative example is basically the same as Example 1, except for the sintering treatment, and the specific steps are as follows:

[0173] The liquid film is subjected to the following sintering treatment to form a heat generating layer:

[0174] The liquid film is placed in an oven and baked at 120°C for 5 min to completely evaporate the water in the liquid film.

[0175] The liquid film is placed in a muffle furnace and baked at 350°C for 10 min to completely decompose the organic matter in the liquid film.

[0176] The liquid film is heated at a rate of 400°C / h from 350°C to 550°C, i.e. the heating time is 30 min, to gradually melt the glass powder in the liquid film and discharge the gas; it is kept at 550°C for 20 min, and cooled to room temperature at a rate of 3°C / min.

[0177] Comparative Example 9

[0178] This comparative example is basically the same as Example 1, except for the sintering treatment, and the specific steps are as follows:

[0179] The liquid film is subjected to the following sintering treatment to form a heat generating layer:

[0180] Put into the oven, 120 ℃ under baking 5 min, the water in the liquid film completely volatilize;

[0181] Into the muffle furnace, 350 ℃ under baking 10 min, the organic matter in the liquid film completely decompose;

[0182] 400 ℃ / h heating rate, from 350 ℃ to 550 ℃, namely the heating time is 30 min, the glass powder in the liquid film gradually melt and discharge gas; at 550 ℃ for 90 min, and cooling to room temperature with 3 ℃ / min cooling rate.

[0183] Comparative Example 10

[0184] The example 1 is basically the same, the difference is sintering treatment, the specific steps are as follows:

[0185] The liquid film is sintered as follows to form the heating layer:

[0186] Put into the oven, 120 ℃ under baking 5 min, the water in the liquid film completely volatilize;

[0187] Into the muffle furnace, 350 ℃ under baking 10 min, the organic matter in the liquid film completely decompose;

[0188] 200 ℃ / h heating rate, from 350 ℃ to 450 ℃, namely the heating time is 30 min, the glass powder in the liquid film gradually melt and discharge gas; at 450 ℃ for 30 min, and cooling to room temperature with 3 ℃ / min cooling rate.

[0189] Comparative Example 11

[0190] The example 1 is basically the same, the difference is sintering treatment, the specific steps are as follows:

[0191] The liquid film is sintered as follows to form the heating layer:

[0192] Put into the oven, 120 ℃ under baking 5 min, the water in the liquid film completely volatilize;

[0193] Into the muffle furnace, 350 ℃ under baking 10 min, the organic matter in the liquid film completely decompose;

[0194] 300 ℃ / h heating rate, from 350 ℃ to 500 ℃, namely the heating time is 30 min, the glass powder in the liquid film gradually melt and discharge gas; at 500 ℃ for 30 min, and cooling to room temperature with 3 ℃ / min cooling rate.

[0195] Comparative Example 12

[0196] The comparative example is basically the same as example 1, except for the sintering process, the specific steps are as follows:

[0197] The liquid film is subjected to the following sintering process to form the heat generating layer:

[0198] Place in the oven, bake at 120℃ for 5min, so that the water in the liquid film is completely volatilized;

[0199] Into the muffle furnace, bake at 350℃ for 10min, so that the organic matter in the liquid film is completely decomposed;

[0200] The temperature is raised from 350℃ to 600℃ at a rate of 500℃ / h, i.e. the heating time is 30min, so that the glass powder in the liquid film is gradually melted and the gas is discharged; keep at 600℃ for 30min, and cool to room temperature at a rate of 3℃ / min.

[0201] Comparative Example 13

[0202] The comparative example is basically the same as example 1, except for the sintering process, the specific steps are as follows:

[0203] The liquid film is subjected to the following sintering process to form the heat generating layer:

[0204] Place in the oven, bake at 120℃ for 5min, so that the water in the liquid film is completely volatilized;

[0205] Into the muffle furnace, bake at 350℃ for 10min, so that the organic matter in the liquid film is completely decomposed;

[0206] The temperature is raised from 350℃ to 550℃ at a rate of 400℃ / h, i.e. the heating time is 30min, so that the glass powder in the liquid film is gradually melted and the gas is discharged; keep at 550℃ for 30min, directly taken out from the muffle furnace, placed in room temperature for rapid cooling.

[0207] Test Example

[0208] The following tests are carried out on the glass-ceramic heat generating plate, the results of examples 1-5 are shown in table 2, and the results of comparative examples 1-13 are shown in table 3.

[0209] (1) Bonding strength: observe the fusion of the heat generating layer and the first glass-ceramic and record.

[0210] (2) Surface pencil hardness: refer to GB / T6739-2006 Paints and varnishes: determination of film hardness by pencil test, use AiRuPo QHQ-A hand-push pencil hardness tester (or called paint film scratch hardness tester, three-in-one oil paint hardness tester) to test the surface pencil hardness of the heating layer.

[0211] (3) Thickness: use thickness gauge to test the thickness of the first microcrystalline glass and the first microcrystalline glass covered with the heating layer, and calculate the thickness of the heating layer.

[0212] (4) Square resistance: use Shengli multimeter VC9801 to test the square resistance of the heating layer.

[0213] (5) Heating stability: make the microcrystalline glass heating plate heat to 500℃ under constant voltage; use the FLIR handheld infrared thermal imager E5-XT to test the heating temperature 30 cm vertically from the heating surface, test the heating temperature every 30 min, continuously test for 10 times, and according to the heating temperature attenuation, infer the heating stability of the microcrystalline glass heating plate at 500℃.

[0214] Table 2. Test data of examples 1-5

[0215]

[0216] Note: the substrate refers to the first microcrystalline glass described above.

[0217] Table 3. Test data of comparative examples 1-13

[0218]

[0219] Note: the substrate refers to the first microcrystalline glass described above.

[0220] From table 2, it can be seen that by using the sintering process of the present application, a microcrystalline glass heating plate with high bonding strength and heating stability can be prepared. Under the same sintering process, as the addition amount of graphene in the heating ink gradually decreases, the square resistance of the heating layer gradually increases, and the required heating voltage also gradually increases.

[0221] In table 3, examples 1 and comparative examples 1-13 are compared one by one, and it can be seen that:

[0222] (1) The heating layer of Comparative Example 1 is not encapsulated, and the microcrystalline glass heating plate is exposed to a high-temperature oxygen environment during heating. After the initial voltage is set to heat to 500°C, the heating temperature decreases, and the decrease is fast at the initial stage. When the heating temperature decreases to 400°C, the decrease slows down, and the final stable temperature is 280°C. It can be seen that graphene is rapidly oxidized in a high-temperature oxygen environment above 400°C, and the heat oxidation resistance is good below 280°C. Therefore, the heating time above 400°C should be controlled during sintering.

[0223] (2) In Comparative Example 2, graphene is replaced by carbon black. Under the same sintering process, the prepared heating layer has a very high square resistance, indicating that carbon black has poor heat oxidation resistance and is not suitable for a high-temperature heating environment of 500°C.

[0224] (3) In Comparative Examples 3-5, the heating time from 350°C to 550°C is extended from 30 min to 60 min, 90 min, and 120 min, respectively. Due to the long heating time, graphene is partially decomposed by heat oxidation, resulting in an increase in the resistance of the heating plate and a decrease in the heating performance.

[0225] (4) In Comparative Examples 6-9, the holding time at 550°C is changed from 30 min to 10 min, 20 min, 60 min, and 90 min, respectively. Since the softening point of the first microcrystalline glass is 600°C, the holding time is shortened, the thermal fusion bonding degree between the first microcrystalline glass and the glass powder is low, and the heating layer is easily detached during multiple heating tests. When the holding time is extended, graphene is partially decomposed by heat oxidation, resulting in an increase in the square resistance of the heating plate and a decrease in the heating performance.

[0226] (5) In Comparative Examples 10-12, the sintering temperature is changed from 550°C to 450°C, 500°C, and 600°C, respectively. When the sintering temperature is too low, the thermal fusion bonding degree between the heating layer and the first microcrystalline glass is low, or even no fusion occurs. When the sintering temperature is too high, graphene is rapidly decomposed by heat oxidation, and the square resistance increases significantly.

[0227] (6) In Comparative Example 13, no gradient cooling is performed. Due to the difference in the thermal expansion coefficient between the heating layer and the first microcrystalline glass, the shrinkage stress generated during rapid cooling is too large, resulting in the fragmentation of the surface of the heating layer.

[0228] In summary, the microcrystalline glass heating plate prepared using the heating ink formulation of Example 1 has a low square resistance and requires a low heating voltage, which has the advantages of low energy consumption and high safety. At the same time, the sintering process of Examples 1-5 can effectively prevent the increase in the square resistance caused by the oxidation of graphene, and obtain a microcrystalline glass heating plate with high bonding strength and good heating stability.

[0229] Any combination of the technical features in the above-described embodiments can be made, and for the sake of brevity, not all possible combinations are described, however, it is to be understood that the application encompasses all such possible combinations.

[0230] The above-described embodiments only express several implementation manners of the application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the scope of the patent right of the application. It should be pointed out that, for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the application, and these all belong to the protection scope of the application. Therefore, the protection scope of the application should be subject to the appended claims, and the description can be used to explain the content of the claims.

Claims

1. A method for preparing a microcrystalline glass heating plate, characterized in that, Includes the following steps: The heating ink containing graphene and glass powder is applied to the first microcrystalline glass to form a liquid film. The liquid film is sintered to form a heating layer; The heating layer is encapsulated to prepare the microcrystalline glass heating plate; The sintering process includes the following steps: heating the liquid film to the sintering temperature through a gradient heating process, holding it at that temperature for 25 min to 35 min, and then performing a gradient cooling process at a cooling rate of 50℃ / h to 200℃ / h; the gradient heating process includes the following steps: heating at 100℃ to 150℃ for 5 min to 10 min, heating at 300℃ to 350℃ for 5 min to 10 min, and then heating to the sintering temperature at a heating rate of 400℃ / h to 500℃ / h. The sintering process satisfies: (1) The sintering temperature is 540℃~560℃; (2) The heating time at temperatures above 400℃ shall not exceed 30 minutes; (3) The sintering temperature is 40°C to 60°C lower than the softening point of the first microcrystalline glass; (4) The sintering temperature is 150°C to 200°C higher than the initial melting temperature of the glass powder.

2. The method for preparing the microcrystalline glass heating plate as described in claim 1, characterized in that, The sintering temperature is 540℃~560℃.

3. The method for preparing the microcrystalline glass heating plate as described in claim 2, characterized in that, The glass powder satisfies one or more of the following conditions: (1) The initial melting temperature of the glass powder is 350℃~400℃; (2) The sintering temperature of the glass powder is 500℃~600℃; (3) The coefficient of thermal expansion of the glass powder is ≤100×10 -7 / K.

4. The method for preparing the microcrystalline glass heating plate according to any one of claims 1 to 3, characterized in that, The encapsulation process for the heating layer includes the following steps: Apply sealant to the first microcrystalline glass to form an adhesive layer around the heating layer; The second microcrystalline glass is placed over the heating layer and the adhesive layer, and then cured to prepare the microcrystalline glass heating plate.

5. The method for preparing the microcrystalline glass heating plate as described in claim 4, characterized in that, The curing temperature is 200℃~250℃.

6. The method for preparing the microcrystalline glass heating plate as described in claim 4, characterized in that, The curing time is 50 min to 60 min.

7. The method for preparing the microcrystalline glass heating plate according to any one of claims 1-3 and 5-6, characterized in that, Methods for coating a first microcrystalline glass with a heat-generating ink containing graphene and glass powder include one or more of screen printing, blade coating, brush coating, spin coating, and spray coating.

8. The method for preparing the microcrystalline glass heating plate according to any one of claims 1-3 and 5-6, characterized in that, The heating ink also includes binders, dispersants, defoamers, and leveling agents.

9. The method for preparing the microcrystalline glass heating plate as described in claim 8, characterized in that, The heating ink comprises the following raw materials in parts by weight: The glass powder is 20 to 40 parts. The graphene is 5 to 20 parts. The adhesive is 40 to 60 parts. The dispersant is 1 to 5 parts. The defoamer is 0.1 to 1 part, and The leveling agent is 0.1 to 1 part.

10. A microcrystalline glass heating plate, characterized in that, It is prepared by the method of preparing microcrystalline glass heating plate as described in any one of claims 1 to 9.

11. A heating device, characterized in that, Including the microcrystalline glass heating plate as described in claim 10.

Images