WO2019079995A1

WO2019079995A1 - Flat vacuum glass sealing method

Info

Publication number: WO2019079995A1
Application number: PCT/CN2017/107620
Authority: WO
Inventors: 宋驁天; 杜争; 叶岩; 曹雪峰; 王墨涵; 郑剑锋
Original assignee: 深圳孔雀科技开发有限公司
Priority date: 2017-10-25
Filing date: 2017-10-25
Publication date: 2019-05-02
Also published as: CN109415253B; CN109415253A

Abstract

A flat vacuum glass sealing method, comprising: in a vacuum chamber, heating a pre-assembled member comprising flat glass, a sealing material, and a support member, vacuumizing the vacuum chamber at the same time to remove air inside the pre-assembled member, then applying pressure perpendicular to the horizontal direction of the glass to the pre-assembled member to implement sealing, and finally, cooling and solidifying to obtain sealed flat vacuum glass. The method is a one-step process: applying pressure to the interior of a vacuum chamber to make a material flow to form a stable structure, and performing heating and sealing, thereby implementing the simultaneous execution of sealing and vacuumization. Compared with conventional technology, the method improves the production efficiency. By making, when the sealing material is softened, the material flow by means of a hot pressing process to form a stable structure avoiding stress concentration, a yield higher than that of conventional technology is obtained.

Description

Sealing method of flat plate vacuum glass

Technical field

The invention relates to the technical field of vacuum glass manufacturing, and in particular to a sealing method of a flat glass vacuum glass.

Background technique

The flat vacuum glass is a glass deep-processing product in which a vacuum sealing layer is formed between two parallel flat glass sheets to realize heat insulation and sound insulation. Wherein, the vacuum sealing layer is hermetically sealed by sealing a periphery thereof with a specific material, and a specific arrangement of supporting members (for example, supporting columns) is provided in the sealing layer to support external atmospheric pressure to maintain the shape of the vacuum layer.

The hermetic sealing of vacuum glass is a key technology for vacuum glass. Sealing refers to the process of forming a hermetic sealing layer having a certain mechanical strength by connecting with a flat glass by using a specific material. At present, the production of vacuum glass has the following sealing technology routes depending on the sealing material used:

1) Sealing with low melting point glass powder

The low-melting glass frit is a mixture of oxidized inorganic metals, which is usually fired into a glass by a specific formulation and crushed to form a micron or nano-sized powder. The low-melting glass powder is generally formed into a slurry and formed into a specific shape of the slurry wet embryo at the sealing portion by printing, casting, extrusion or wet coating, and then formed into a certain shape by drying and discharging. Dry powder of glass powder. Subsequently, it is sealed in a kiln at a temperature higher than its glass softening point (Tg, about 400-500 ° C), and is heated by a specific process system (generally heating and heat sealing time is 40 minutes to 2 hours) and then cooled. Annealing to form a dense glass seal layer of a certain thickness and width.

2) Sealing with metal soldering

Soldering refers to the technique of sealing with solder below 400 °C. The brazing material may be a solder paste (a paste having a certain viscosity formed by mixing and dispersing a solder powder, a solvent, and a flux), a brazing preform (a solder dense member processed into a specific shape), or the like. Prior to sealing, the glass substrate needs to be processed to achieve the connection of the metal solder. Methods of treatment include coating, sintering transition joining materials, and the like. The brazing material is then placed in a sealed position for heat sealing. It is desirable to heat the solder to a melting point (or eutectic temperature; a softening point for the amorphous) or a temperature above the melting point for a certain period of time followed by cooling at a specific rate to effect the sealing process. This sealing process typically lasts 10-40 minutes.

3) Sealing with sealant

Sealing with a sealant refers to a technique of sealing with a low vapor pressure adhesive. By applying sealant to The sealing portion forms a layer of glue of a certain thickness and is cured in a certain environment for a certain period of time (generally more than one hour). After curing, a sealing layer having a certain airtightness and mechanical strength can be formed.

Sealing with the above materials requires specific processes and equipment for sealing. For example, the Chinese patent "CN 102079619B (a glass plate composite sealing method)" describes a metal brazing process for glass at a predetermined position. Sealing method between plates and sealing by local heating; Chinese patent "CN 103382079B (sealing method for tempered vacuum glass, preparation method and tempered vacuum glass)" introduces an infrared heating glass Method for sealing vacuum glass by powder; Chinese patent "CN 103588387B (Processing method for tempered vacuum glass)" introduces a method for sealing in a sealing furnace by using low-melting glass powder, and adopts a subsequent process from one The suction port extracts the vacuum in the sealing layer and seals it again; the Chinese patent "CN 103373805B (tempered, semi-tempered vacuum glass and its manufacturing method)" also uses a heating furnace below 430 ° C to carry out low melting glass powder The sealing is performed, and the vacuum is extracted from the sealing layer from a suction port by a subsequent process and sealed again.

In the Chinese patent "CN 102079619B (a glass plate composite sealing method)", metal brazing is used for sealing, and it is pointed out that the method can be used as a basic condition for making vacuum glass. The patent describes the features of the metal brazing process, including: the metal brazing process is carried out under inert gas protection, or in an H ₂ gas or N ₂ gas environment; the metal brazing process is carried out in a vacuum environment; And the metal brazing process is carried out in the form of local heating of the sealing area by laser heating, flame heating, current heating, induction heating or microwave heating, or by dip soldering.

The inter-glass metal brazing process described in this patent employs external heating of the external heat source including laser heating, flame heating, current heating, induction heating or microwave heating. Since glass is a brittle material, if a large temperature difference is formed inside the glass, thermal stress will locally occur in the glass. When the thermal stress exceeds the strength of the glass (the glass compressive stress is about 49-196×10 ⁸ Pa, the tensile stress is about 34.3-83.3×10 ⁶ Pa), the glass will break. For general float glass, if the internal temperature difference exceeds 40 ° C / mm, it is very likely to break. According to the experimental results, for a 4 mm thick glass, the median temperature difference at which the first fragmentation occurred was 129.2 °C. If the local heating method in this patent is used, it is difficult to avoid the stress generated by the temperature gradient. In particular, induction heating, microwave heating, and short-wavelength laser heating (referring to a laser with a wavelength below 1300 nm, float sodium soda glass has a absorption rate below 5% in this wavelength range) will directly heat the portion of the metal solder, while the glass It is impossible to absorb the external heat source and can only be heated by the heat conduction of the metal solder. When the metal solder is melted, it is generally lower than 350 ° C. If the commercial material with a suitable cost is 200 ± 50 ° C, it is very likely that a large temperature difference will be formed on the contact surface of the metal solder and the glass, resulting in broken glass. Cracking, resulting in a process failure yield decline. And there is residual stress or sealing thickness error on the edge-sealing structure after processing. If the method of first sealing and then pumping in the patent is adopted, the local stress may be excessive during the pumping process, resulting in failure of the sealing structure.

In the Chinese patent "CN 103382079B (sealing method, preparation method and tempered vacuum glass for tempered vacuum glass)", a method for achieving sealing by using local infrared heating low temperature glass powder paste sealing tape is described. In this method, the paste is heated by a specific wavelength of infrared heating method, after a 1-10 minute binder discharge process, a 1-8 minute preliminary temperature rise process, and a 0.1-2 minute rapid temperature rise process, The low melting point sealing material is heated to 400 to 550 ° C to soften the material, followed by cooling to 150 ° C to complete the sealing process. In this method, the characteristics of this process are described, both after sealing, followed by vacuuming, sealing, and inspection steps.

In this patent, a glass paste is used as the sealing material. Since the organic powder or the inorganic binder is contained in the glass paste slurry, if it remains in the sealing structure after sealing, the strength and airtightness of the sealing structure are affected, so it must be removed during the sealing process. Since the binder in the paste is in the form of a dispersed porous medium, it is difficult to remove the binder by the method of the method of the patent, and even if the holding time is long enough, it may remain in the sealing structure.

At the same time, the technical solution adopts the steps of sealing, vacuuming, sealing and inspection, and all the processes need to be completed for at least several hours, which is very time consuming. Moreover, in the process of sealing, the sealed edge structure cannot control the tolerance, and the height and the unevenness may occur. In the subsequent vacuuming process, the stress may be broken due to uneven stress, resulting in a decrease in the yield.

In summary, the prior art has the following problems:

(1) The existing vacuum glass manufacturing technology divides the sealing and vacuuming into two processes, requiring a large variety of equipment and low efficiency;

(2) Due to process limitations, existing vacuum products are designed with suction ports (front or side). The position of the suction port will cause stress concentration points due to discontinuous structure, which may be caused by external wind pressure or thermal stress during long-term use. Fragmentation occurred.

(3) In the existing sealing process of vacuum glass, since the existing heat sealing method cannot accurately control the thickness uniformity of the sealing layer, internal stress is generated in the subsequent vacuuming process, and if the stress exceeds the strength limit of the material, Will invalidate the structure, so the yield is not high.

Summary of the invention

The invention provides a sealing method for a flat vacuum glass which improves production efficiency and production yield, and comprises the following technical solutions:

A method for sealing a flat vacuum glass, comprising: heating a pre-assembly including a flat glass, a sealing material and a support in a vacuum chamber while evacuating the vacuum chamber to remove the interior of the pre-assembly; Gas, then apply a pressure perpendicular to the horizontal direction of the glass to the pre-assembly to achieve sealing, and finally cool and solidify to obtain a sealed Flat vacuum glass.

Further, when the temperature is sealed, the vacuum in the vacuum chamber is lower than 1 × 10 ^-3 Pa, and the applied pressure reaches the set maximum pressing force.

Further, the degree of vacuum in the vacuum chamber is less than 6 × 10 ^-4 Pa, and the maximum pressing force is at least 80 kPa, preferably at least 0.15 MPa.

Further, the heating process comprises: preheating the pre-assembly to a temperature lower than a predetermined temperature difference of the sealing temperature, holding the pre-assembly temperature uniformly for a period of time; and then heating the pre-assembly to the sealing Connect the temperature.

Further, the heating process comprises: preheating the pre-assembly to a temperature lower than the sealing temperature by 10-50 ° C in 1-60 minutes, and maintaining the temperature of the pre-assembly evenly for 1-10 minutes; then in 20 seconds The pre-assembly is heated to the sealing temperature within -10 minutes.

Further, the pre-assembly is preheated to a predetermined temperature difference below the sealing temperature by a heating platform for carrying the pre-assembly, a pressing mechanism for applying pressure to the pre-assembly, and a heat radiant heating element. The temperature is then heated to a sealing temperature by a heating mechanism for carrying the pre-assembly described above, a pressing mechanism for applying pressure to the pre-assembly.

Further, in the preheating stage, the temperature gradient between the surface temperature of the glass substrate of the pre-assembly and the temperature of the lower surface of the glass substrate does not exceed 30 ° C / mm.

Further, the vacuum chamber is evacuated while the preheating is started; after the preheating phase is finished, the vacuum in the vacuum chamber is less than 1×10 ^-3 Pa, preferably less than 6×10 ^-4 Pa.

Further, the pre-assembly is pressed by a pressing plate, a rolling mechanism or a compression air bag, and the pre-assembly is preferably pressed by a compression air bag.

Further, the heating comprises sequentially preheating to a temperature lower than a predetermined temperature difference of the sealing temperature, and heating to a sealing temperature; the applying pressure starts from the last stage of the preheating, preferably from the last 20% of the preheating Start and then reach the set maximum pressing force when heated to the sealing temperature.

Further, the above maximum pressing force is at least 80 kPa, preferably at least 0.15 MPa.

Further, after the sealing temperature is reached, the heat is maintained for 1-1800 s to achieve sealing, and the maximum pressing force is maintained during the heat preservation process.

Further, the sealing material is a metal sealing material, and is cooled at 30-100 ° C/s during the cooling and solidification process. However, the speed quickly cools below the freezing point of the material.

Further, the sealing material is a glass frit sealing material, and is cooled to an annealing temperature of the material during the cooling and solidification process to be annealed.

Further, during the cooling and solidification process, when cooling to less than 30 ° C below the freezing point temperature, an inert gas is introduced into the vacuum chamber to accelerate the cooling.

Further, the amount of nitrogen gas introduced into the inert gas cannot exceed 50 kPa in the vacuum chamber.

Further, the sealing material is a glass frit sealing paste or a high vacuum sealant, and the pre-assembly is formed by the following method:

First, the above-mentioned glass frit sealing paste or high-vacuum sealant is applied to the surface to be sealed of the bottom glass surface by casting, dispensing, screen printing or hand-applied to form a sealing strip having a wavy thickness; The slurry or sealant that has not yet fully solidified is then dried to form a dry embryo or semi-solidified state; then the support member is placed and the cover glass is assembled to form a glass, non-hermetic seal layer, glass loose sandwich structure.

Further, the sealing material is a metal sealing material, and the pre-assembly is formed by the following method:

First, the glass surface sealing position is metallized to form a metallization layer; then the metal sealing tape is calendered into a wave shape and placed on the metallization layer; then the support member is arranged and the cover glass is assembled to form Glass, metallized layer, voided metal sealing tape, metallized layer, glass multi-layer sandwich structure.

Further, the flat glass, the sealing material and the support are sufficiently deaerated before the pre-assembly is formed.

Further, the above degassing is achieved by means of high temperature baking or plasma cleaning in a dry atmosphere.

The method of the invention is a one-step process, applying pressure in a vacuum environment to make the material flow to form a stable structure and heat sealing, thereby achieving sealing and vacuuming simultaneously, and greatly improving production compared with the conventional technology. effectiveness. When the sealing material is softened, a hot pressing process is used to make the material flow to form a stable structure to avoid stress concentration, which is higher than the conventional technology.

DRAWINGS

1 is a schematic view of a pre-assembled loose structure according to an embodiment of the present invention, wherein 11 denotes a bottom glass, 12 denotes a sealing material, and 13 denotes a cover glass.

2 is a schematic view showing a vacuum chamber using a pressing plate pressing mechanism and an internal structure thereof according to an embodiment of the present invention, wherein, 21 A heating platform is shown, 22 is a pre-assembly, 23 is a platen pressing mechanism, and 24 is a vacuum chamber.

3 is a schematic view showing a vacuum chamber using an airbag pressing mechanism and an internal structure thereof, wherein 31 denotes a heating platform, 32 denotes a pre-assembly, 33 denotes an airbag pressing mechanism, and 34 denotes a vacuum chamber.

4 is an environmental condition curve in a vacuum chamber according to an embodiment of the present invention, including a temperature curve, a vacuum degree curve, and a pressing force curve.

Detailed ways

The present invention will be further described in detail below with reference to the accompanying drawings. In the following embodiments, many of the details are described in order to provide a better understanding of the invention. However, those skilled in the art can easily realize that some of the features may be omitted in different situations, or may be replaced by other components, materials, and methods. In some instances, some of the operations related to the present invention have not been shown or described in the specification in order to avoid that the core portion of the present invention is overwhelmed by excessive description, and those skilled in the art will describe these in detail. Related operations are not necessary, they can fully understand the relevant operations according to the description in the manual and the general technical knowledge in the field.

In addition, the features, operations, or characteristics described in the specification may be combined in any suitable manner to form various embodiments. At the same time, the steps or actions in the method description can also be sequentially changed or adjusted in a manner that can be apparent to those skilled in the art. Therefore, the various sequences in the specification and the drawings are only for the purpose of describing a particular embodiment, and are not intended to

In the present invention, the degree of vacuum means absolute pressure.

At present, some techniques have been carried out by sealing in a non-vacuum atmosphere, and then vacuuming and sealing through a suction hole, which can be called a "two-step process". According to the description of the background art, the prior art has problems such as low efficiency and low yield. The embodiment of the present invention is a one-step process for applying pressure in a vacuum environment to cause a material to flow to form a stable structure and to heat the seal.

The principle of the method of the embodiment of the invention is that the sealing is performed in the high vacuum chamber, the intermediate interlayer of the two glasses has formed a vacuum, and then the material is heated to a specific temperature by heating (for example, heating by heat radiation to assist heat conduction). The non-hermetic loose structure in which a specific material is deposited is welded (for metal materials) or sintered (for glass powder materials) to achieve sealing. During the sealing process, when the sealing material melts or softens, a certain pressure is applied to the flat glass by the outside, so that the melt flows and macroscopically deforms, and after the physical and chemical reaction in the sealing process is completed, the glass is cooled. The sealing material solidifies. The solidified sealing structure can form a specific uniform thickness, the internal residual stress is small, and the intact structure will be ensured in the atmospheric pressure. And it can realize the sealing and extraction vacuum in the same process, greatly improving The production speed.

In certain preferred embodiments of the invention, the method of the invention comprises the following specific steps:

(1) Degassing of raw materials

In the general atmospheric environment, a certain amount of water and gas are adsorbed on the surface and inside of any material. If the water or gas remains on the surface of the glass, the support (such as the support column), the edge seal material or inside, it is sealed into a vacuum. The glass will continue to be released afterwards, which will affect the vacuum inside the vacuum glass, resulting in a decrease in performance. For the floating flat glass, the material used for the vacuum glass needs to be sufficiently degassed and then sent to the vacuum chamber for sealing.

The raw materials used in the method of the embodiment of the invention include: flat glass, metal or non-metal support column, glass surface metallization layer, metal strip for sealing (pure low melting point metal strip, other metal or non-metal surface plated with low melting point metal) Belt), glass powder slurry, low vapor pressure sealant for high vacuum. Degassing of raw materials can be achieved by high temperature baking and plasma cleaning in a dry atmosphere.

(2) Pre-assembly of raw materials

1 shows a pre-assembled loose structure in an embodiment of the invention, comprising a bottom glass 11, a sealing material 12, and a cover glass 13.

The pre-assembled vacuum glass is pre-assembled into a specific state, and can be specifically divided into two processes according to the sealing materials (metal, glass frit paste, high vacuum sealant, etc.) used:

If a glass frit sealing paste or a high vacuum sealant is used, the slurry or sealant is first applied to the surface of the bottom glass to be sealed by casting, dispensing, screen printing or hand-applied, and formed. A sealing strip of a certain width, the thickness of the sealing strip being wavy. The slurry or sealant that has not yet completely solidified is then dried in an air environment to form a dry embryo or semi-solidified state having a certain mechanical strength. The support columns are then placed and the cover glass is assembled to form a glass, non-hermetic seal layer, glass loose sandwich structure. Thus in the vacuum chamber, the gas can be extracted through the tiny gap formed by the loose structure.

If a metal sealing material is used, the glass surface sealing position needs to be metallized to form a metallization layer, for example, a thermal spray transition metal layer, and the metal layer is coated by CVD or PVD. The metal sealing tape is then calendered into a specific wave shape and placed on the metallization layer. The support post is then placed and the cover glass is assembled to form a multi-layer sandwich structure of glass, metallized layer, voided metal sealing strip, metallized layer, glass.

(3) heating in a vacuum chamber

2 shows a vacuum chamber using a pressing plate pressing mechanism and an internal structure thereof in the embodiment of the present invention, including adding The hot stage 21, the pre-assembly 22, the platen pressing mechanism 23, and the vacuum chamber 24.

FIG. 3 shows another vacuum chamber and its internal structure using an airbag pressing mechanism in the embodiment of the present invention, including a heating platform 31, a pre-assembly 32, an airbag pressing mechanism 33, and a vacuum chamber 34.

The pre-assembled pre-assembled components are passed through the parallel drive into the vacuum chamber. The vacuum chamber includes access doors (not shown in Figures 2 and 3), conveyors (not shown in Figures 2 and 3), heating platforms, compression mechanisms, and vacuum systems (not shown in Figures 2 and 3) show). Among them, the furnace door can be designed as a quick opening vacuum door and a flapper valve for isolating the vacuum chamber from the atmosphere.

The transfer device includes a translational transfer and a vertical lift mechanism, wherein the translational transfer is a roller or track transfer for transporting the pre-assembly to the heating platform. The vertical lifting mechanism then places the pre-assembly in a predetermined position on the heating platform.

The heating platform can be composed of a resistive heating element, a cooling medium pipe, and a heat conducting block and a heat conducting felt. Wherein the heating element can be a resistive or dielectric heating element. The cooling medium pipe is used for sealing and controllable cooling solidification, and is forced by external convection circulation. The specific cooling medium may be heat transfer oil or water. The heating and cooling components can be directly embedded in the thermal block, which is used to increase the temperature uniformity of the plate, and is made of a solid material having a high vapor conductivity of low vapor pressure, such as graphite, copper, aluminum, and the like. The thermal conductive felt is used to increase the thermal conductivity of the interface between the lower surface of the glass and the heating platform. Since the flatness of the glass surface is about 0.15 mm/m, the surface roughness of the finished thermal conductive block is less than 50 μm/m, but the assembly flatness error is about 0.1 mm/ m, resulting in incomplete fit between the two rough surfaces, there is a great interface contact thermal resistance in the vacuum. The thermal conductive felt is a soft material with good compressibility (such as high thermal conductivity carbon fiber multiaxial braid, graphite felt, vacuum silicone grease, composite rubber filled with high thermal conductivity material) for adding the above two surfaces. The contact area enhances heat transfer.

The pre-assembly is placed on the heating platform and heated by the bottom-up heat conduction of the platform. There is a pressing mechanism at the upper part of the pre-assembly, which also has a corresponding heating element for heat conduction heating.

At the same time, a heat radiating heating element arranged on the side is also included for assisting the heating to accelerate the heating rate. However, even though carefully designed components produce poor temperature uniformity (approximately ±5 ° C), such components can only be used for heating during the preheating phase of the workpiece. The specific process regime in the heating process can be:

In the preheating stage, the pre-assembly is heated by the heating platform, the pressing mechanism and the heat radiant heating element, for example, heating to a sealing temperature of 10 to 50 ° C for 1-10 minutes, and holding the temperature for 1-10 minutes to make the workpiece temperature uniform. If a glass frit paste material is used, it is also necessary to hold the baking at a baking temperature (generally a temperature lower than the preheating end temperature) for a period of time. During the preheating phase, the temperature of the upper surface of the base glass and the surface temperature of the heating platform are monitored by a thermocouple, and the temperature gradient between the two points is required to not exceed 30 ° C / mm. At the same time as preheating, the vacuum pump unit is started to start pumping. After the preheating phase, the vacuum (absolute pressure) in the chamber should be lower than 10 ^-3 Pa, preferably lower than 6 × 10 ^-4 Pa.

After the preheating phase is completed, the pre-assembly is heated to the sealing temperature, at which point the thermal radiant heating element should be turned off or turned down. The power is only heated by the heating platform and the pressing mechanism (the temperature control accuracy can be controlled at ±0.5 °C), and the pre-assembly is quickly heated to the sealing temperature, and the heating time is 20 seconds to 10 minutes.

(4) Apply pressure and seal in the vacuum chamber

A pressing mechanism that can be vertically moved is designed above the cover glass. The pressing mechanism may be a pressing plate or a rolling mechanism driven by an external hydraulic pressure, a pneumatic pressure, a motor or a spring, or a compression airbag. In a preferred embodiment of the invention, a compression airbag is used, which can provide, for example, a compression pressure of at most 2 MPa, which is applied to the cover glass and can be transmitted between the two glasses by force transmission. The wavy loose sealing structure is compact. At the last 20% of the preheating phase, a specific pressing force is applied (ie, the force is applied to the sealing layer. For example, in this embodiment, the airbag is pressed, and the force at the sealing layer is about: air pressure inside the airbag × sealing The area of the joint layer / the total area of the glass), and the maximum pressing force is set when heated to the sealing temperature, the maximum pressing force is at least 80 kPa, and the maximum design pressure of the system (for example, the airbag is pressed to 2 MPa) ). After the sealing temperature is reached, the sealing process is achieved by holding 1-1800 s. Depending on the materials used, the time can be different, such as 5s-240s using metal sealing materials, and 600-1800s using glass frit sealing paste, during which the pressing force remains unchanged, and then enters the cooling and solidification stage.

(5) Cooling and solidification in a vacuum chamber

After the sealing is completed, controlled cooling solidification is carried out according to the characteristics of the materials used. If a metal sealing material is used, it needs to be rapidly cooled to below the freezing point of the material, and the solidification speed is generally 30-100 ° C / s. If a glass frit sealing material is used, it needs to be cooled to the annealing temperature of the material for annealing, for example, annealing at an annealing temperature for 10-30 min. Cooling can be achieved by forced convection cooling in a pipe embedded in the heat conducting block. Heat transfer oil is used as the cooling medium, and the heat transfer oil outlet temperature generally does not exceed 150 ° C to ensure the cooling rate. In the above process, the pressing force is continuously maintained, and the pressing mechanism also requires corresponding cooling. When cooling to below the freezing point temperature of 30 ° C or less, an inert gas such as nitrogen gas may be introduced into the vacuum chamber to accelerate the cooling, and the amount of nitrogen introduced may not cause the chamber pressure to exceed 50 kPa. After cooling to a certain temperature (generally below 100 ° C), the pressing force is removed. At this time, the glass sealing position has formed a dense, non-residual stress, uniform thickness, and a highly mechanical strength airtight sealing structure. At this point, the furnace door can be discharged and enter the atmospheric environment to carry out the final stage of cooling. The final stage of cooling can be air cooled until cooled to normal temperature.

During the solidification and cooling process, the application of a pressing force of 1 atmosphere or more can cause the material in the sealing structure to flow before solidification, and the leveling forms a relatively uniform thickness, and the glass can be prevented from being broken by a suitable pressing method. . This allows for a more complete hermetic sealing structure after annealing. After exposure to the atmosphere, thermal energy can keep the glass body and the edge-sealing structure from chipping.

By using the method of the embodiment of the invention, the production speed and the yield of the vacuum glass can be greatly improved, according to the estimation. With the metal sealing material process, the sealing process and the vacuuming process can be completed in 15 minutes, whereas in the conventional process, only the vacuuming process takes several hours, because the conventional process is a tailed vacuum glass, that is, the sealing is completed. After that, a vacuum is drawn through the cavity through a very small suction pipe, and then the suction pipe is sealed. Therefore, the vacuuming process is limited to a small conductance and takes a very long time to complete. At the same time, the method of the embodiment of the invention applies a pressure close to atmospheric pressure during the sealing process, so that the molten material flows, forming a more stable structure, eliminating internal residual stress after cooling, and no stress concentration point occurs. The probability of breaking after exposure to the atmosphere is extremely low, increasing the yield. In the traditional method, since the thickness of the sealing layer cannot be precisely controlled, in the process of vacuum extraction, uneven force is generated under the action of internal and external pressure difference, and the stress concentration point is easily generated, causing the glass or the sealing structure to be broken.

As an illustrative example, FIG. 4 shows an environmental condition curve in a vacuum chamber in an embodiment of the present invention, including a temperature curve, a vacuum degree curve, and a pressing force curve, and the variation trend of these curves follows The process of heating, applying pressure, and cooling solidification changes.

The technical solutions and effects of the present invention are described in detail below by way of examples. It is to be understood that the embodiments are not to be construed as limiting.

Example 1

3mm thick floatarized calcium glass is used as the glass substrate; tinned copper strip is used as sealing metal material, the width is 5mm, the thickness is 0.4mm, the coating thickness is 40μm, and the specific tin plating material is SnAg3.5; The high-temperature sintered type connecting silver paste is a metallized layer, which is applied to the sealing position by screen printing, and is fixed by sintering at 700 ° C for 60 s (with glass tempering) to form a metallized layer having a thickness of 20 μm and a width of 6 mm; The 304 stainless steel was turned into a support column of 0.4 mm high and 0.8 mm diameter by turning, and arranged by a robot to form a matrix with a pitch of 40 mm.

Subsequently, manual pre-assembly is carried out, and the wave-shaped tin-plated copper strips formed by the assembly are not more than 0.05 mm in a random arrangement. It is then fed into a vacuum processing chamber that is compressed by a bladder. The vacuum chamber is made of 304 stainless steel, equipped with mechanical pump and molecular pump unit for vacuuming, the ultimate vacuum is 6×10 ^-4 Pa; the heating element is made of nickel-chromium resistance wire and tungsten quartz heat radiant tube; The deionized water in the 10mm round tube forced convection, and the outside was circulated through the water cooling unit. The cooling water inlet temperature was 30 ° C and the outlet temperature was 80 ° C. The heat conducting block is made of graphite and has a thickness of 20 mm. The electric resistance wire and the water-cooled pipe are alternately embedded in the heat conducting block. The heat radiant tube is placed on the side of the middle of the cavity, and a reflector is disposed on the outside to direct the radiation to the workpiece. The pressing mechanism adopts a 6mm thick vacuum airbag cloth. The inside of the airbag is nitrogen gas, which is heated by the heater on the upper surface. The airbag can provide a maximum pressure of 2 MPa (by adjusting the air pressure), and the temperature resistance is 300 °C. The inside of the airbag is inflated so that its lower surface is close to the upper surface of the workpiece. The airbag is connected to the upper cover of the vacuum chamber by a hermetic sealing, the airbag is inflated by an external air supply device, and has an air suction device on the other side for evacuating the airbag.

The pre-assembly was placed on the heated thermal block, the door of the vacuum chamber was closed, and the chamber was evacuated to 6 x 10 ^-4 Pa. At the same time, the heating is turned on, heated to 200 ° C of the workpiece to stop the heat radiation heating, and kept warm for 5 minutes to wait for the temperature to be uniform. Subsequently, only the resistance wire heating element was turned on, and the workpiece was quickly heated to 250 ° C for 30 seconds. During the incubation period, the inside of the balloon is inflated to a process pressure of about 1 MPa. After the end of the heat preservation, maintain the airbag pressure, turn off the resistance heating, turn on the external water cooling cycle, and quickly cool the workpiece to 180 °C in 1 minute. At this time, the airbag is filled with cold nitrogen under the premise of maintaining the pressure to lower the temperature inside the airbag. At this time, nitrogen gas was introduced into the vacuum chamber to raise the vacuum chamber to 100 Pa. Subsequently, the workpiece was cooled at a rate of 3 ° C per second, the workpiece was cooled to 100 ° C, and nitrogen gas was introduced into the vacuum chamber to raise the pressure to 2000 Pa to accelerate the cooling rate. Finally, the workpiece is cooled to within 60 ° C and the door is opened to remove the workpiece.

In the embodiment of the present invention, the new process is used to realize the sealing and vacuuming simultaneously, and the production speed is greatly improved compared with the conventional technology. At the same time, when the sealing material is softened, a flexible hot pressing process is adopted, so that a certain flow of the material forms a stable structure to avoid stress concentration, which is higher than the conventional process. Specifically, the production speed of the single-piece vacuum glass can be shortened from 6 hours to 30 minutes in the conventional method, and the yield due to stress concentration is increased from 50% to over 90%.

Example 2

5mm thick float-fat calcium glass is used as the glass substrate; high-density box-shaped preform is made of tin-lead (SnPb40Ag1) metal material, the width is 4mm, the thickness is 0.5mm; the high-temperature sintering type silver paste is used. Material (for the metallized layer, applied to the sealing position by screen printing to form a wet film of 6 mm width and 20 μm thickness, and dried at 150 ° C for 10 minutes, and sintered at 700 ° C for 3 minutes (glass tempered) Fixed, forming a metallized layer with a thickness of 14 μm and a width of 6 mm; using a 304 stainless steel to be turned into a 0.4 mm high, 0.8 mm diameter non-chamfered cylinder as a support column, and arranged by a mechanical arrangement into a matrix of 40 mm pitch.

Subsequent pre-assembly, the composition of the glass-metallization layer-pre-assembly-metallization layer-glass, ensuring that the pre-assembly is flat, and setting the horizontal limit fixture on the outside of the pre-assembly to avoid the vacuum process The movement of the glass caused by the flow of air. It is then fed into a vacuum processing chamber that is compressed by a bladder. The vacuum chamber is made of 304 stainless steel, equipped with mechanical pump and molecular pump unit for vacuuming, the ultimate vacuum is 6×10 ^-4 Pa; the heating element is made of nickel-chromium resistance wire and tungsten quartz heat radiant tube; The deionized water in the 10mm round tube forced convection, and the outside was circulated through the water cooling unit. The cooling water inlet temperature was 30 ° C and the outlet temperature was 80 ° C. The heat conducting block is made of graphite and has a thickness of 20 mm. The electric resistance wire and the water-cooled pipe are alternately embedded in the heat conducting block. The heat radiant tube is placed on the side of the middle of the cavity, and a reflector is disposed on the outside to direct the radiation to the workpiece. The pressing mechanism adopts a 6mm thick vacuum airbag cloth. The inside of the airbag is nitrogen gas, which is heated by the heater on the upper surface. The airbag can provide a maximum pressure of 2 MPa (by adjusting the air pressure), and the temperature resistance is 300 °C. The inside of the airbag is inflated so that its lower surface is close to the upper surface of the workpiece. The airbag is connected to the upper cover of the vacuum chamber by a hermetic seal, the airbag is inflated by an external air supply device, and has an air suction device on the other side for evacuating the airbag.

The pre-assembly was placed on the heated thermal block, the door of the vacuum chamber was closed, and the chamber was evacuated to 6 x 10 ^-4 Pa. At the same time, the heating is turned on, and the heat radiation power is reduced after heating to the workpiece at 120 ° C, and the temperature is kept uniform for 1 minute. During the incubation period, the inside of the balloon is inflated to a process pressure of about 1 MPa. Subsequently, the heat radiation power was increased to raise the workpiece to 160 ° C, and then the heat radiation was turned off for heat preservation for 2 minutes. Subsequently, only the resistance wire heating element was turned on, and the workpiece was heated up to 200 ° C quickly (within 2 minutes) for 30 seconds. After the end of the heat preservation, maintain the airbag pressure, turn off the resistance heating, turn on the external water cooling cycle, and quickly cool the workpiece to 180 °C in 1 minute. At this time, the airbag is filled with cold nitrogen under the premise of maintaining the pressure to lower the temperature inside the airbag. At this time, nitrogen gas was introduced into the vacuum chamber to raise the vacuum chamber to 800 Pa. The workpiece was then cooled at a rate of 3 ° C per second, the workpiece was cooled to 100 ° C, nitrogen was introduced into the vacuum chamber, and the pressure was raised to 80 kPa to accelerate the cooling rate. Finally, the workpiece is cooled to within 60 ° C and the door is opened to remove the workpiece.

In the embodiment of the present invention, the new process is used to realize the sealing and vacuuming simultaneously, and the production speed is greatly improved compared with the conventional technology. At the same time, when the sealing material is softened, a flexible hot pressing process is adopted, so that a certain flow of the material forms a stable structure to avoid stress concentration, which is higher than the conventional process. Specifically, the production speed of the single-piece vacuum glass can be shortened from 6 hours to 10 minutes in the conventional method, and the yield due to stress concentration is increased from 50% to over 90%.

Example 3

5mm thick floatarized calcium glass is used as the glass substrate; low melting glass powder (85wt%) is mixed with terpineol (14.5wt%) and ethyl cellulose (0.5wt%) is made into a thick paste through a three-roll mill. material. The slurry was applied to the sealing area around the glass plate to form a wet film of 6 mm width and 0.6 mm thickness. Subsequently, 304 stainless steel was turned into a 0.4 mm high, 0.8 mm diameter non-chamfered cylinder as a support column by turning, and arranged by a mechanical arrangement into a matrix of 40 mm pitch, and the upper cover glass was aligned.

A horizontal limit clamp is placed on the outside of the combined glass to avoid glass movement due to airflow during vacuuming. It is then fed into a vacuum processing chamber that is compressed by a bladder. The vacuum chamber is made of 304 stainless steel, equipped with mechanical pump and molecular pump unit for vacuuming, the ultimate vacuum is 6×10 ^-4 Pa; the heating element is made of nickel-chromium resistance wire and tungsten quartz heat radiant tube; The deionized water in the 10mm round tube forced convection, and the outside was circulated through the water cooling unit. The cooling water inlet temperature was 30 ° C and the outlet temperature was 80 ° C. The heat conducting block is made of graphite and has a thickness of 20 mm. The electric resistance wire and the water-cooled pipe are alternately embedded in the heat conducting block. The heat radiant tube is placed in the upper part of the cavity, and a reflector is arranged on the outside to direct the radiation to the workpiece. The pressing mechanism uses a stainless steel pressure plate to provide a maximum pressure of 5 MPa by providing a pressing force to the cylinder outside the vacuum chamber.

Place the assembly on the heated and thermally conductive block, close the door of the vacuum chamber, and open the mechanical pump to evacuate the chamber to 10 Pa. At the same time, the heating is turned on, heated to 120 ° C after the workpiece, and then kept warm for 10 minutes to wait for the temperature to be uniform. Then, it was heated to 240 ° C after the workpiece and then kept warm for 30 minutes to wait for the temperature to be evenly kept. The molecular pump was turned on and the chamber was evacuated to 6 × 10 ^-4 Pa. It was then heated to 530 ° C at a rate of 2 ° C per minute and held for 45 minutes. At this time, the pressure plate was opened to apply a pressure of 1.5 MPa to the glass to cause the glass frit to flow into a stable structure. After the end of the holding, the pressure was maintained, the heating was turned off, the external water cooling cycle was turned on, and the temperature was cooled to 400 ° C at a rate of 3 ° C per minute. At this time, the pressure plate is filled with cold nitrogen under the premise of maintaining the pressure to lower the temperature inside the air bag. At this time, nitrogen gas was introduced into the vacuum chamber to raise the vacuum chamber to 100 Pa. The workpiece was then cooled at a rate of 5 ° C per minute, the workpiece was cooled to 100 ° C, nitrogen was introduced into the vacuum chamber, the pressure was raised to 80 kPa, and the cooling rate was accelerated. Finally, the workpiece is cooled to within 60 ° C and the door is opened to remove the workpiece.

The invention has been described above with reference to specific examples, which are merely intended to aid the understanding of the invention and are not intended to limit the invention. For the person skilled in the art to which the invention pertains, several simple derivations, variations or substitutions can be made in accordance with the inventive concept.

Claims

A method for sealing a flat glass vacuum glass, comprising: heating a pre-assembly including a flat glass, a sealing material and a support in a vacuum chamber while evacuating the vacuum chamber to remove The gas inside the pre-assembly is then applied to the pre-assembly with a pressure perpendicular to the horizontal direction of the glass to achieve sealing, and finally cooled and solidified to obtain a sealed flat glass vacuum glass.
The sealing method according to claim 1, wherein at the sealing temperature, the degree of vacuum in the vacuum chamber is less than 1 × 10 -3 Pa, and the applied pressure reaches a set maximum pressing force. .
The sealing method according to claim 2, wherein the vacuum chamber has a degree of vacuum of less than 6 × 10 -4 Pa, and the maximum pressing force is at least 80 kPa, preferably at least 0.15 MPa.
The sealing method according to claim 1, wherein the heating comprises: first preheating the pre-assembly to a temperature lower than a sealing temperature by a predetermined temperature difference, and maintaining the temperature for a period of time The pre-assembly is temperature uniform; the pre-assembly is then heated to the sealing temperature.
The sealing method according to claim 4, wherein the heating comprises: preheating the pre-assembly to a temperature lower than a sealing temperature of 10 - 50 ° C in 1-60 minutes, and maintaining the heat - 1 The pre-assembly temperature was made uniform for 10 minutes; then the pre-assembly was heated to the sealing temperature within 20 seconds to 10 minutes.
The sealing method according to claim 4, wherein said heating means for carrying said pre-assembly, said pressing means for applying pressure to said pre-assembly, said heat radiant heating element The pre-assembly is preheated to a temperature below the sealing temperature by a predetermined temperature difference; then the pre-preparation is performed by a heating platform for carrying the pre-assembly, a pressing mechanism for applying pressure to the pre-assembly The assembly is heated to the sealing temperature.
The sealing method according to claim 6, wherein in the preheating stage, the temperature gradient between the surface temperature of the glass substrate on the pre-assembly and the temperature of the lower surface of the glass substrate does not exceed 30 ° C / mm .
The sealing method according to claim 4, wherein the vacuum chamber is evacuated while the preheating is started; after the preheating phase is finished, the vacuum in the vacuum chamber is low It is 1 × 10 -3 Pa, preferably less than 6 × 10 -4 Pa.
The sealing method according to claim 1, wherein the pre-assembly is pressed by a pressing plate, a rolling mechanism or a compression air bag, and the pre-assembly is preferably pressed by a compression air bag.
The sealing method according to claim 1, wherein the heating comprises, in order, preheating to a temperature lower than a sealing temperature by a predetermined temperature difference, heating to a sealing temperature; the applying pressure from the preheating The final stage begins, preferably starting from the last 20% of the preheating and then reaching the set maximum pressing force upon heating to the sealing temperature.
The sealing method according to claim 10, wherein said maximum pressing force is at least 80 kPa, preferably at least 0.15 MPa.
The sealing method according to claim 10, wherein after the sealing temperature is reached, the heat is maintained for 1-1800 s to achieve sealing, and the maximum pressing force is maintained during the heat retaining process.
The sealing method according to claim 1, wherein the sealing material is a metal sealing material, and is rapidly cooled to a freezing point of the material at a cooling rate of 30-100 ° C / s during the cooling and solidification process. the following.
The sealing method according to claim 1, wherein the sealing material is a glass frit sealing material, and is cooled to an annealing temperature of the material during the cooling solidification to be annealed.
The sealing method according to claim 13 or 14, wherein in the cooling and solidifying process, when cooling to less than 30 ° C below the freezing point temperature, an inert gas is introduced into the vacuum chamber to accelerate the cooling.
The sealing method according to claim 15, wherein the amount of nitrogen gas introduced into the inert gas is such that the pressure in the vacuum chamber exceeds 50 kPa.
The sealing method according to claim 1, wherein the sealing material is a glass frit sealing paste or a high vacuum sealant, and the pre-assembly is formed by the following method:

First, the glass frit sealing paste or high vacuum sealant is applied to the surface of the bottom glass surface to be sealed by casting, dispensing, screen printing or hand-applied to form a wavy sealing strip. The slurry or sealant that has not yet completely solidified is then dried to form a dry embryo or semi-solidified state; then the support member is arranged and the cover glass is assembled to form a glass, non-hermetic sealing layer, loose loose glass sandwich structure.
The sealing method according to claim 1, wherein the sealing material is a metal sealing material, and the pre-assembly is formed by the following method:

First, the glass surface sealing position is metallized to form a metallization layer; then the metal sealing tape is calendered into a wave shape and placed on the metallization layer; then the support member is arranged and the cover glass is assembled Forming a multi-layer sandwich structure of glass, metallized layer, voided metal sealing tape, metallized layer, and glass.
The sealing method according to claim 1, wherein the flat glass, the sealing material and the support are sufficiently degassed before the pre-assembly is formed.
The sealing method according to claim 19, wherein the outgassing is achieved by means of high temperature baking or plasma cleaning in a dry atmosphere.