A double-layer coated photovoltaic glass tempering process

Abstract

The present invention belongs to the field of photovoltaic glass processing technology, and specifically relates to a double-layer coated photovoltaic glass tempering process, comprising the following steps: providing a double-layer coated photovoltaic glass; sending the double-layer coated photovoltaic glass into a tempering furnace for heating treatment; during the heating treatment, along the length and width directions of the tempering furnace, the tempering furnace is divided into a number of temperature control zones and sections, and the coated surface and the non-coated surface are heated simultaneously by double-sided heating, and the temperature of the coated surface is 10°C to 20°C lower than the temperature of the corresponding point of the non-coated surface; the double-layer coated photovoltaic glass is subjected to rapid cooling treatment; the double-layer coated photovoltaic glass is subjected to cooling treatment; and the double-layer coated photovoltaic glass is sent out of the tempering furnace for cleaning. The present invention sets the temperature of the coated surface to be lower than the temperature of the non-coated surface during the heating treatment process, thereby solving the problem of warping of the board head of the double-layer coated photovoltaic glass after tempering.

Description

Technical Field

[0001] The invention belongs to the technical field of photovoltaic glass processing, and in particular relates to a double-layer coated photovoltaic glass tempering process. Background Art

[0002] Photovoltaic glass is an important component of photovoltaic modules. With the development of the photovoltaic market, high transmittance requirements have been put forward for photovoltaic glass. Double-layer coated photovoltaic glass has the characteristics of high transmittance and small color difference, and will become the mainstream product in the future.

[0003] In current production, when tempering double-layer coated photovoltaic glass, the double-layer coated photovoltaic glass is conveyed to the tempering furnace by a conveyor roller. The non-coated surface of the double-layer coated photovoltaic glass is in direct contact with the conveyor roller. During the tempering heat treatment, the non-coated surface contacts the quartz conveyor roller in the tempering furnace. On the one hand, it receives heat conduction from the conveyor roller, and on the other hand, it receives radiant heat from the heating wire and the radiation plate under the conveyor roller. The coated surface receives radiant heat from the upper heating wire, which is radiant heating. When the temperature of the tempering furnace is set, the temperature of the coated surface is higher than the temperature of the non-coated surface.

[0004] After the double-layer coated photovoltaic glass was processed using the above-mentioned tempering process, a serious problem of board head warping occurred, making it difficult to meet the requirements of use. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a double-layer coated photovoltaic glass tempering process. Compared with the traditional tempering process, the present invention sets the temperature of the non-coated surface to be higher than the temperature of the coated surface during the heating treatment process, that is, contrary to the temperature setting of the traditional tempering process, the temperature of the coated surface is made lower than the temperature of the non-coated surface, and the tempering furnace is divided into several temperature control zones and sections, and rapid cooling and cooling treatment are performed after the heating treatment, which solves the problem of warping of the double-layer coated photovoltaic glass after tempering.

[0006] The present invention is specifically achieved through the following technical solutions.

[0007] The present invention provides a double-layer coated photovoltaic glass tempering process, comprising the following steps:

[0008] S1. Provide a double-layer coated photovoltaic glass that has been ground and polished at the edges, chamfered at the four corners and cleaned.

[0009] S2. The double-layer coated photovoltaic glass obtained in S1 is sent into a tempering furnace for heating treatment. During the heating treatment, the tempering furnace is divided into several temperature control zones and sections along the length and width directions of the tempering furnace, and the coated surface and the non-coated surface are heated simultaneously by double-sided heating. The temperature of the coated surface is lower than the temperature of the corresponding position of the non-coated surface, and the temperature difference is 10°C to 20°C.

[0010] S3, subjecting the double-layer coated photovoltaic glass obtained in S2 to rapid cooling.

[0011] S4, cooling the double-layer coated photovoltaic glass obtained in S3.

[0012] S5. Send the double-layer coated photovoltaic glass obtained in S4 out of the tempering furnace for cleaning.

[0013] In a preferred embodiment of the present invention, in S2, the length of the tempering furnace is designed according to the characteristics, heat absorption curve and production capacity of the double-layer coated photovoltaic glass, and the tempering furnace is divided into several zones in length, and divided into sections in width according to the number of heating wire distribution groups in each zone. Such zoning and segmentation are conducive to ensuring uniform heat absorption of the glass in the furnace and preventing the glass from bursting during heating or rapid cooling.

[0014] like Figure 1 As shown, along the length direction of the tempering furnace, i.e. the horizontal direction, the tempering furnace is divided into 52 temperature control zones, i.e., zones 1 to 52. And according to the characteristics of the double-layer coated photovoltaic glass, the temperature curve of the double-layer coated photovoltaic glass is set. The temperature curve is set as a peak type and is divided into three parts. The first part is the temperature rising zone, which is set as zones 1 to 29; the second part is the slow rising zone, which is set as zones 30 to 45; and the third part is the temperature dropping zone, which is set as zones 46 to 52.

[0015] The tempering furnace is divided into five sections along the width direction, ie, the longitudinal direction, of the tempering furnace, ie, the first section to the fifth section.

[0016] Temperature curve distribution of non-coated surface:

[0017] The temperature of the heating zone of the third section is set as: from 630℃ in the first zone to 710℃~715℃ in the 29th zone, the temperature of the slow rising zone of the third section is set as: from 30 zone to 45 zone, the temperature is 715℃~730℃, and the temperature of the cooling zone of the third section is set as: from 46 zone to 52 zone, the temperature is 700℃~710℃.

[0018] The temperature of section 3 is set as the reference value. In the same zone, the temperature of section 2 is 4°C to 5°C lower than that of section 3; the temperature of section 1 is set as the reference value. In the same zone, the temperature of section 1 is 5°C lower than that of section 2; the temperature of section 3 is set as the reference value. In the same zone, the temperature of section 4 is 4°C to 5°C lower than that of section 3; the temperature of section 5 is set as the reference value. In the same zone, the temperature of section 5 is 5°C lower than that of section 4.

[0019] The temperature gradually increases along the length direction, then remains relatively stable, and finally gradually decreases. From the length direction, the temperature in the middle of the double-layer coated photovoltaic glass is higher than the temperature at both ends. Since the front and rear ends of the double-layer coated photovoltaic glass absorb heat faster than the middle, the above heating temperature control zone distribution can ensure that the glass is heated evenly. Similarly, the width of the tempering furnace is divided into 5 sections, and the temperature on both sides is lower than the temperature in the middle, which ensures that the double-layer coated photovoltaic glass is heated evenly and minimizes deformation.

[0020] The softening point of double-layer coated photovoltaic glass is 720°C. The above temperature is set near the softening point of the double-layer coated photovoltaic glass to ensure that the double-layer coated photovoltaic glass minimizes deformation while meeting the tempering requirements.

[0021] The temperature of the coated surface is lower than the temperature of the corresponding position of the non-coated surface, and the temperature difference is 10℃~20℃. This setting can ensure that the warping of the board head is less than 0.5mm after the double-coated glass is tempered.

[0022] In a preferred embodiment of the present invention, in order to further improve the temperature distribution in the tempering furnace and make the double-layer coated photovoltaic glass more evenly heated, a heat balance device is provided in the first to 26th zones of the tempering furnace, the heat balance device includes a first heat balance tube, a first heat-resistant steel tube, a second heat balance tube and a second heat-resistant steel tube, holes are opened on the first heat-resistant steel tube and the second heat-resistant steel tube, a first heating wire is provided above the double-layer coated photovoltaic glass, a plurality of first heat-resistant steel tubes are installed at the lower end of the first heating wire, one end of the first heat balance tube is connected to the first heat-resistant steel tube, and the other end of the first heat balance tube is connected to the compressed air end, a second heating wire is provided below the double-layer coated photovoltaic glass, a radiation plate is provided above the second heating wire, a plurality of second heat-resistant steel tubes are installed at the upper end of the radiation plate, one end of the second heat balance tube is connected to the second heat-resistant steel tube, and the other end of the second heat balance tube is connected to the compressed air end. 0.05MPa to 0.15MPa compressed air is blown into the tempering furnace to accelerate the air flow in the tempering furnace and make the temperature quickly and evenly balanced. The present invention provides a heat balance device in the 1st to 26th zones of the tempering furnace to blow air into the tempering furnace, which can not only solve the problem of uneven temperature distribution in the tempering furnace caused by zone heating, but also further realize uniform heating of the double-layer coated photovoltaic glass.

[0023] The thickness of the double-layer coated photovoltaic glass of the present invention is 2 mm, and the thicker the glass, the longer the heating time, and the lower the speed of the conveying roller. During the heating process of the double-layer coated photovoltaic glass, the heating time of the double-layer coated photovoltaic glass of the present invention is set to no less than 20 seconds / mm to 45 seconds / mm, and the heating treatment time is 90s to 115s, ensuring that after the double-layer coated photovoltaic glass absorbs heat, the temperature distribution is uniform and reaches the temperature required for tempering, thereby avoiding overheating of the double-layer coated photovoltaic glass and causing deformation of the panel surface.

[0024] In a preferred embodiment of the present invention, in S3, the rapid cooling treatment is air cooling, and a high-pressure upper wind grid and a high-pressure lower wind grid are respectively provided above and below the double-layer coated photovoltaic glass. The high-pressure upper wind grid and the high-pressure lower wind grid simultaneously convey rapid cooling wind to perform rapid cooling treatment on the double-layer coated photovoltaic glass. The wind pressure of the rapid cooling wind is 9KPa to 12KPa, and the rapid cooling treatment time is 3s to 4s. The height of the double-layer coated photovoltaic glass from the high-pressure upper wind grid and the high-pressure lower wind grid is 8mm to 12mm. The air cooling cost is low, and the use of high-pressure air rapid cooling forms uniform compressive stress on the glass surface and tensile stress inside, thereby improving the strength of the glass.

[0025] In a preferred embodiment of the present invention, in S4, the cooling treatment is air cooling, and a medium-pressure upper wind grid and a medium-pressure lower wind grid are respectively provided above and below the double-layer coated photovoltaic glass. The medium-pressure upper wind grid and the medium-pressure lower wind grid simultaneously convey cooling air to cool the double-layer coated photovoltaic glass. The wind pressure of the cooling air is 3KPa to 5KPa, and the cooling treatment time is 20s to 30s. The height of the double-layer coated photovoltaic glass from the medium-pressure upper wind grid and the medium-pressure lower wind grid is 20mm to 25mm. When the cooling treatment is performed again after the rapid cooling treatment, not only the surface stress of the double-layer coated photovoltaic glass is made more uniform, but also the problem of plate head warping can be alleviated.

[0026] The thinner the glass, the more consistent the temperature is when the upper and lower surfaces and the center of the glass are cooled, making it difficult to form a temperature difference, and thus difficult to generate surface stress. The thicker the glass, the faster the temperature of the upper and lower surfaces of the glass decreases when cooled, and the temperature rise of the center of the glass is slower than that of the upper and lower surfaces, making it easy to form a temperature difference. The thickness of the double-layer coated photovoltaic glass of the present invention is 2 mm, which is relatively thin. Therefore, during the rapid cooling treatment, the present invention cools for 3s to 4s at a wind pressure of 9KPa to 12KPa, thereby solving the technical problem that it is difficult for 2mm thick photovoltaic glass to form a temperature difference, and thus it is difficult to generate surface stress, so that the impact strength and four-point bending strength of the double-layer coated photovoltaic glass meet the requirements. After the rapid cooling treatment, the present invention further cools for 20s to 30s at 3KPa to 5KPa, thereby further making the surface stress of the double-layer coated photovoltaic glass more uniform and improving the flatness of the double-layer coated photovoltaic glass.

[0027] In a preferred embodiment of the present invention, in S2, the speed at which the double-layer coated photovoltaic glass is fed into the tempering furnace is 500mm / s to 600mm / s, and the speed at which the double-layer coated photovoltaic glass is fed out of the tempering furnace is 750mm / s to 950mm / s.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present invention sends the double-layer coated photovoltaic glass into a tempering furnace for heating treatment first, then performs rapid cooling treatment and cooling treatment, and finally sends it out of the tempering furnace for cleaning. During the heating treatment, a number of temperature control zones are divided along the length direction of the tempering furnace, and a number of sections are divided along the width direction of the tempering furnace, thereby ensuring that the double-layer coated photovoltaic glass is heated evenly during the heating process, and setting the temperature of the coated surface lower than the temperature of the corresponding position of the non-coated surface, with a temperature difference of 10°C to 20°C, thereby solving the problem of warping of the double-layer coated photovoltaic glass after tempering. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the horizontal temperature control zone and the longitudinal section division of the present invention.

[0031] Figure 2 Schematic diagram of the coating process of photovoltaic glass to be coated.

[0032] Figure 3 Schematic diagram of the heating process of double-layer coated photovoltaic glass in a tempering furnace.

[0033] Figure 4 It is a schematic diagram of the transmission process of double-layer coated photovoltaic glass on the conveyor roller during the heating process.

[0034] Description of reference numerals:

[0035] 1. Photovoltaic glass to be coated, 2. Rubber roller, 3. Conveying mechanism, 4. Tempering furnace, 41. First heat balance tube, 42. First heating wire, 43. First heat-resistant steel tube, 44. Second heating wire, 45. Second heat balance tube, 46. Second heat-resistant steel tube, 5. Double-layer coated photovoltaic glass, 6. Conveying roller. DETAILED DESCRIPTION

[0036] In order to enable those skilled in the art to better understand and implement the technical solution of the present invention, the present invention is further described below in conjunction with specific embodiments and drawings, but the embodiments are not intended to limit the present invention.

[0037] After research, it was found that when using traditional tempering technology to temper double-layer coated photovoltaic glass, the reason why the board head is prone to warping is:

[0038] Double-layer coating refers to coating the surface of photovoltaic glass with a base film and a surface film. The base film is mainly composed of silicon dioxide, with a refractive index of about 1.44 and a thickness of about 80nm. The surface film is the same as conventional single-layer coating, with a refractive index of about 1.29 and a thickness of about 110nm.

[0039] On the one hand, the equipment used for photovoltaic glass coating is a roller coater. When the photovoltaic glass 1 to be coated enters the roller coater, Figure 2As shown, since the rubber roller 2 has a downward pressure on the photovoltaic glass 1 to be coated, the downward pressure is as follows: Figure 2 As shown in A, it is generally 0.9mm~1.0mm, the rubber roller 2 is lower than the head of the photovoltaic glass 1 to be coated, and the conveying direction is opposite. The photovoltaic glass 1 to be coated is placed on the conveying mechanism 3, and the conveying direction of the photovoltaic glass 1 to be coated is shown in B, and the conveying direction of the rubber roller 2 is shown in C. The head of the photovoltaic glass 1 to be coated will also be coated in the thickness direction, while the tail of the photovoltaic glass 1 to be coated will not be coated. Although the coated photovoltaic glass has been cured, part of the organic matter will volatilize, but because the surface film is a dense structure of porous silica, the porosity is smaller than that of the bottom film, and some organic matter will remain in the bottom film. Volatilized, during the heating process of the tempering furnace, the board head is at the intersection of the thickness cross section and the upper surface, and the organic matter remaining in the film layer will volatilize, causing drastic deformation of the board head.

[0040] On the other hand, due to the anti-reflection properties of the double-layered photovoltaic glass anti-reflection film, the double-layered photovoltaic glass easily absorbs heat in the infrared region. Therefore, the head of the double-layered photovoltaic glass with a thickness of more than 1 / 2 is prone to heat absorption, causing the upper part to absorb heat quickly and cause warping.

[0041] Furthermore, if Figure 3 and Figure 4 As shown, when the double-layer coated photovoltaic glass 5 is heated in the tempering furnace 4, the double-layer coated photovoltaic glass 5 moves forward on the conveying roller 6, and there are gaps between multiple double-layer coated photovoltaic glasses 5 on the conveying roller 6. The first heating wire 42 and the second heating wire 44 are respectively provided above and below the double-layer coated photovoltaic glass 5 to heat the double-layer coated photovoltaic glass 5. The front and rear ends of the double-layer coated photovoltaic glass 5 are heated faster than the middle part, and as shown in FIG. Figure 4 As shown, due to the large spacing of the conveying rollers 6, usually between 200mm and 80mm, the front and rear ends of the double-layer coated photovoltaic glass 5 become soft and sag. After the heating treatment, when it enters the wind grid area in the tempering furnace 4 and is rapidly cooled, it will also cause different degrees of cooling and shrinkage in the middle part of the double-layer coated photovoltaic glass 5. Compared with the middle part, the front and rear ends of the double-layer coated photovoltaic glass 5 have different local temperatures and mutations, resulting in uneven microstructure.

[0042] To this end, the present invention proposes a double-layer coated photovoltaic glass tempering process, comprising the following steps:

[0043] S1. Provide double-layer coated photovoltaic glass that has been ground and polished on the edges, chamfered on the four corners and cleaned.

[0044] S2. Sending the double-layer coated photovoltaic glass into a tempering furnace for heat treatment; during the heating treatment, the tempering furnace is divided into a number of temperature control zones and sections along the length and width directions of the tempering furnace, and the coated surface and the non-coated surface are heated simultaneously by double-sided heating, and the temperature of the coated surface is lower than the temperature of the corresponding position of the non-coated surface, and the temperature difference is 10°C to 20°C.

[0045] It should be noted that, during the heating process, the temperature of the coated surface is set lower than the temperature of the corresponding position of the non-coated surface, and the temperature difference is 10°C to 20°C, so as to reduce the warping caused by the excessive heat absorption of the coated surface, and at the same time, reduce the volatilization rate of organic matter to avoid causing drastic deformation of the board head. Several temperature control zones are divided along the length direction of the tempering furnace, and several sections are divided along the width direction of the tempering furnace. According to the different heat absorption capacity of different positions of the double-layer coated photovoltaic glass, the heating temperature is set in different temperature zones and sections to ensure that the double-layer coated photovoltaic glass is heated evenly during the heating process.

[0046] S3, subjecting the double-layer coated photovoltaic glass after the heating treatment to rapid cooling treatment. The rapid cooling treatment forms compressive stress on the surface of the double-layer coated photovoltaic glass and tensile stress inside, thereby achieving a glass tempering effect.

[0047] S4, cooling the double-layer coated photovoltaic glass after the rapid cooling treatment. The cooling treatment not only makes the surface stress of the double-layer coated photovoltaic glass more uniform, but also can alleviate the problem of plate head warping.

[0048] S5, sending the double-layer coated photovoltaic glass after the cooling treatment out of the tempering furnace for cleaning.

[0049] After being treated with the above-mentioned tempering process, the problem of warping of the panel head of the double-layer coated photovoltaic glass was solved.

[0050] The following examples and comparative examples are provided below to specifically illustrate the contents of the present invention.

[0051] In the following examples and comparative examples, the heating process of the double-layer coated photovoltaic glass in the tempering furnace is as follows: Figure 3As shown, the thickness of the double-layer coated photovoltaic glass 5 is 2 mm. When the double-layer coated photovoltaic glass 5 is heated in the tempering furnace 4, a first heating wire 42 and a second heating wire 44 are respectively provided above and below the double-layer coated photovoltaic glass 5 to heat the double-layer coated photovoltaic glass 5. The heating power of the first heating wire 42 and the second heating wire 44 is 4200KW to 5000KW, and the heat generation of the first heating wire 42 and the second heating wire 44 is respectively controlled by thermocouples. In order to further improve the temperature distribution in the tempering furnace 4 and make the double-layer coated photovoltaic glass 5 heated more evenly, a heat balance device is provided in the 1st to 26th zones of the tempering furnace 4, and the heat balance device includes a first heat balance tube 41, a first heat-resistant steel tube 43, a second heat balance tube 45, and a second heat-resistant steel tube 46. Holes are provided on the first heat-resistant steel tube 43 and the second heat-resistant steel tube 46. A plurality of first heat-resistant steel tubes 43 are installed at the lower end of the first heating wire 42. One end of the first heat balance tube 41 is connected to the first heat-resistant steel tube 43, and the other end is connected to the compressed air end. A radiation plate is installed above the second heating wire 44. A plurality of second heat-resistant steel pipes 46 are installed on the upper end of the radiation plate, one end of the second heat balance pipe 45 is connected to the second heat-resistant steel pipe 46, and the other end is connected to the compressed air end, and 0.05MPa~0.15MPa compressed air is injected into the first heat-resistant steel pipe 43 through the first heat balance pipe 41, and 0.05MPa~0.15MPa compressed air is injected into the second heat-resistant steel pipe 46 through the second heat balance pipe 45, and the compressed air enters the tempering furnace 4 through the holes on the first heat-resistant steel pipe 43 or the second heat-resistant steel pipe 46, thereby accelerating the air flow, ensuring uniform temperature distribution in the furnace and accelerating the glass to absorb heat.

[0052] Example 1

[0053] A double-layer coated photovoltaic glass tempering process comprises the following steps:

[0054] S1. Provide a double-layer coated photovoltaic glass that has been subjected to edge grinding and polishing, four-corner chamfering and cleaning treatment. The double-layer coated photovoltaic glass in this embodiment is an embossed photovoltaic glass coated with Covestro double-layer film liquid. The thickness of the double-layer coated photovoltaic glass is 2 mm.

[0055] S2, send the double-layer coated photovoltaic glass obtained in S1 into Figure 3 The double-layer coated photovoltaic glass is fed into the tempering furnace at a speed of 553 mm / s. During the heating process, the coated surface and the non-coated surface are heated simultaneously by double-sided heating, and the heating time is 103 s.

[0056] Along the length direction of the tempering furnace, the tempering furnace is divided into 52 temperature control zones, including zone 1 to zone 52. Along the width direction of the tempering furnace, the tempering furnace is divided into 5 sections, including section 1 to section 5.

[0057] The 52 temperature control zones of the tempering furnace are divided into three parts. The first part is the heating zone, which is set from zone 1 to zone 29; the second part is the slow heating zone, which is set from zone 30 to zone 45; the third part is the cooling zone, which is set from zone 46 to zone 52.

[0058] Temperature curve distribution of non-coated surface:

[0059] The temperature of the 45th zone in the slow-rise zone of the third section is set to 715°C.

[0060] In the heating zone of the third section, the temperature of the first to the 29th zones is increased by 2℃ to 3℃ per zone until the temperature of the 29th zone is 710℃, and the temperature of the 30th to the 45th zones is increased by 0℃ to 1℃ per zone until the temperature of the 45th zone is 715℃. The cooling zone of the third section is reduced by 2℃ to 4℃ per zone until it is reduced to 710℃ in the 52nd zone. It should be noted that during the heating process of the first to the 29th zones, the heating rate between each zone is not a fixed value, but can vary within the range of 2℃ to 3℃. Similarly, the heating rate of the 30th to the 45th zone is also a range value, and the cooling rate of the cooling zone is also a range value.

[0061] Taking the 3rd section temperature setting as the reference value, in the same zone, the temperature of the 2nd section is 5°C lower than that of the 3rd section. Taking the 2nd section temperature setting as the reference value, in the same zone, the temperature of the 1st section is 5°C lower than that of the 2nd section. Taking the 3rd section temperature setting as the reference value, in the same zone, the temperature of the 4th section is 5°C lower than that of the 3rd section. Taking the 4th section temperature setting as the reference value, in the same zone, the temperature of the 5th section is 5°C lower than that of the 4th section.

[0062] The temperature of the coated surface is lower than the temperature of the corresponding position of the non-coated surface, specifically 15°C lower.

[0063] S3. The double-layer coated photovoltaic glass obtained in S2 is subjected to rapid cooling treatment. The rapid cooling treatment adopts air cooling treatment. The wind pressure of the rapid cooling wind is 10KPa. The rapid cooling treatment is performed for 3s. The height of the double-layer coated photovoltaic glass from the high-voltage upper wind grid is 8mm, and the height of the double-layer coated photovoltaic glass from the high-voltage lower wind grid is 8mm.

[0064] S4. The double-layer coated photovoltaic glass obtained in S3 is cooled by air cooling. The pressure of the cooling air is 5 KPa. The cooling time is 20 s. The height of the double-layer coated photovoltaic glass from the medium pressure upper wind grid is 20 mm. The height of the double-layer coated photovoltaic glass from the medium pressure lower wind grid is 20 mm.

[0065] S5. Send the double-layer coated photovoltaic glass obtained in S4 out of the tempering furnace for cleaning. The speed of sending the double-layer coated photovoltaic glass out of the tempering furnace is 880 mm / s.

[0066] Example 2

[0067] A double-layer coated photovoltaic glass tempering process comprises the following steps:

[0068] S1. Provide a double-layer coated photovoltaic glass that has been subjected to edge grinding and polishing, four-corner chamfering and cleaning treatment. The double-layer coated photovoltaic glass in this embodiment is an embossed photovoltaic glass coated with Covestro double-layer film liquid, and has a thickness of 2 mm.

[0069] S2, send the double-layer coated photovoltaic glass obtained in S1 into Figure 3 The double-layer coated photovoltaic glass is fed into the tempering furnace at a speed of 528 mm / s. During the heating process, the coated surface and the non-coated surface are heated simultaneously by double-sided heating, and the heating time is 90 seconds.

[0070] Along the length direction of the tempering furnace, the tempering furnace is divided into 52 temperature control zones, including zone 1 to zone 52. Along the width direction of the tempering furnace, the tempering furnace is divided into 5 sections, including section 1 to section 5.

[0071] The 52 temperature control zones of the tempering furnace are divided into three parts. The first part is the heating zone, which is set from zone 1 to zone 29; the second part is the slow heating zone, which is set from zone 30 to zone 45; the third part is the cooling zone, which is set from zone 46 to zone 52.

[0072] Temperature curve distribution of non-coated surface:

[0073] The temperature of the 45th zone of the slow rise zone of the 3rd section is set to 720°C.

[0074] In the heating zone of the third section, the temperature of zones 1 to 29 is set to increase by 2℃ to 3℃ per zone until the temperature of zone 29 is increased to 710℃. The temperature of zones 30 to 45 is increased by 0℃ to 2℃ per zone until the temperature reaches 720℃ in zone 45. The temperature reduction zone of the third section is reduced by 0℃ to 3℃ per zone until it reaches 704℃ in zone 52. It should be noted that during the heating process of zones 1 to 29, the heating rate between each zone is not a fixed value, but can vary within the range of 2℃ to 3℃. Similarly, the heating rate of zones 30 to 45 is also a range value, and the cooling rate of the cooling zone is also a range value.

[0075] Taking the temperature setting of the 3rd section as the reference value, within the same zone, the 1st to 28th zones of the 2nd section will be reduced by 5°C respectively, and the 29th to 52nd zones of the 2nd section will be reduced by 4°C respectively.

[0076] The temperature of the first section is set as the reference value of the temperature of the second section. In the same zone, the temperature of the first section is 5°C lower than that of the second section.

[0077] Taking the temperature setting of the 3rd section as the reference value, within the same zone, the 1st to 28th zones of the 4th section will be reduced by 5°C respectively, and the 29th to 52nd zones of the 4th section will be reduced by 4°C respectively.

[0078] The temperature setting of the 5th section is based on the temperature setting of the 4th section. In the same zone, the temperature of the 5th section is 5°C lower than that of the 4th section.

[0079] Coating surface temperature setting:

[0080] The temperatures of the coated surfaces in sections 1, 2, 4 and 5 are 10°C lower than the temperatures in the same area of ​​the non-coated surface respectively; the temperatures of the coated surfaces in sections 1 to 28 of section 3 are 20°C lower than the temperatures in the same area of ​​the non-coated surface, and the temperatures of the coated surfaces in sections 29 to 52 are 15°C lower than the temperatures in the same area of ​​the non-coated surface.

[0081] S3. The double-layer coated photovoltaic glass obtained in S2 is subjected to rapid cooling treatment. The rapid cooling treatment adopts air cooling treatment. The rapid cooling wind pressure is 9 KPa. The rapid cooling treatment time is 4 seconds. The height of the double-layer coated photovoltaic glass from the high-voltage upper wind grid is 12 mm. The height of the double-layer coated photovoltaic glass from the high-voltage lower wind grid is 12 mm.

[0082] S4. The double-layer coated photovoltaic glass obtained in S3 is cooled by air cooling. The cooling air pressure is 3 KPa. The cooling time is 30 s. The height of the double-layer coated photovoltaic glass from the medium pressure upper wind grid is 25 mm. The height of the double-layer coated photovoltaic glass from the medium pressure lower wind grid is 25 mm.

[0083] S5. Send the double-layer coated photovoltaic glass obtained in S4 out of the tempering furnace for cleaning. The speed of sending the double-layer coated photovoltaic glass out of the tempering furnace is 950 mm / s.

[0084] Example 3

[0085] A double-layer coated photovoltaic glass tempering process comprises the following steps:

[0086] S1. Provide a double-layer coated photovoltaic glass that has been processed by edge grinding and polishing, four-corner chamfering and cleaning. The double-layer coated photovoltaic glass is an embossed photovoltaic glass coated with Covestro double-layer film liquid, with a thickness of 2mm.

[0087] S2, send the double-layer coated photovoltaic glass obtained in S1 into Figure 3 The double-layer coated photovoltaic glass is fed into the tempering furnace at a speed of 584 mm / s. During the heating process, the coated surface and the non-coated surface are heated simultaneously by double-sided heating, and the heating time is 115 seconds.

[0088] Along the length direction of the tempering furnace, the tempering furnace is divided into 52 temperature control zones, including zone 1 to zone 52. Along the width direction of the tempering furnace, the tempering furnace is divided into 5 sections, including section 1 to section 5.

[0089] The 52 temperature control zones of the tempering furnace are divided into three parts. The first part is the heating zone, which is set from zone 1 to zone 29; the second part is the slow heating zone, which is set from zone 30 to zone 45; the third part is the cooling zone, which is set from zone 46 to zone 52.

[0090] Temperature curve distribution of non-coated surface:

[0091] The temperature of the 45th zone of the slow rise zone of the 3rd section is set to 725°C.

[0092] The temperature rise zones of the third section are set as follows: Zones 1 to 13 are heated at an increase of 0°C to 4°C per zone, and Zones 14 to 28 are heated at an increase of 0°C to 3°C per zone, until the temperature reaches 710°C in Zone 29.

[0093] The temperature of zones 30 to 45 is increased by 0°C to 5°C per zone until it reaches 725°C in zone 45.

[0094] The temperature in the cooling zone of the third section is reduced by 0℃ to 3℃ in each zone until it is reduced to 700℃ in zone 52. It should be noted that during the heating and cooling process, the heating rate or cooling rate between each zone is not a fixed value, but can vary within a certain range of values.

[0095] Taking the temperature setting of the 3rd section as the reference value, within the same zone, the 1st to 28th zones of the 2nd section will be reduced by 5°C respectively, and the 29th to 52nd zones will be reduced by 4°C respectively.

[0096] The temperature of the first section is set with the temperature of the second section as the reference value. In the same zone, the temperature of the first section is 5°C lower than that of the second section.

[0097] Taking the temperature setting of the 3rd section as the reference value, within the same zone, the 1st to 28th zones of the 4th section will be reduced by 5°C respectively, and the 29th to 52nd zones will be reduced by 4°C respectively.

[0098] The temperature setting of the 5th section is based on the temperature setting of the 4th section. In the same zone, the temperature of the 5th section is 5°C lower than that of the 4th section.

[0099] Coating surface temperature setting:

[0100] The temperatures of the coated surfaces in sections 1, 2, 4 and 5 are 18°C ​​lower than the temperatures in the same area of ​​the non-coated surface respectively; the temperatures of the coated surfaces in sections 1 to 28 of section 3 are 18°C ​​lower than the temperatures in the same area of ​​the non-coated surface, and the temperatures of the coated surfaces in sections 29 to 52 are 17°C lower than the temperatures in the same area of ​​the non-coated surface.

[0101] S3. The double-layer coated photovoltaic glass obtained in S2 is subjected to rapid cooling treatment. The rapid cooling treatment adopts air cooling. The rapid cooling air pressure is 12 KPa. The rapid cooling treatment time is 3 s. The height of the double-layer coated photovoltaic glass from the high-voltage upper wind grid is 12 mm. The height of the double-layer coated photovoltaic glass from the high-voltage lower wind grid is 12 mm.

[0102] S4. Cool the double-layer coated photovoltaic glass obtained in S3. The cooling method is air cooling. The cooling air pressure is 5 KPa. The cooling time is 20 seconds. The height of the double-layer coated photovoltaic glass from the medium pressure upper wind grid is 25 mm. The height of the double-layer coated photovoltaic glass from the medium pressure lower wind grid is 25 mm.

[0103] S5. Send the double-layer coated photovoltaic glass obtained in S4 out of the tempering furnace for cleaning, and the speed at which the double-layer coated glass is sent out of the tempering furnace is 930 mm / s.

[0104] Comparative Example 1

[0105] Comparative Example 1 provides a double-layer coated photovoltaic glass tempering process. Compared with Example 1, the difference is that the temperature of the coated surface and the temperature of the non-coated surface are swapped, and specifically includes the following steps:

[0106] S1. Provide a double-layer coated photovoltaic glass that has been processed by edge grinding and polishing, four-corner chamfering and cleaning. The double-layer coated photovoltaic glass is an embossed photovoltaic glass coated with Covestro double-layer film liquid. The thickness of the double-layer coated photovoltaic glass is 2mm.

[0107] S2, send the double-layer coated photovoltaic glass obtained in S1 into Figure 3 The double-layer coated photovoltaic glass is fed into the tempering furnace at a speed of 553 mm / s. During the heating process, the coated surface and the non-coated surface are heated simultaneously by double-sided heating, and the heating time is 103 s.

[0108] Along the length direction of the tempering furnace, the tempering furnace is divided into 52 temperature control zones, including zone 1 to zone 52. Along the width direction of the tempering furnace, the tempering furnace is divided into 5 sections, including section 1 to section 5.

[0109] The 52 temperature control zones of the tempering furnace are divided into three parts. The first part is the heating zone, which is set from zone 1 to zone 29; the second part is the slow heating zone, which is set from zone 30 to zone 45; the third part is the cooling zone, which is set from zone 46 to zone 52.

[0110] Coating surface temperature curve distribution:

[0111] The temperature of the 45th zone in the slow-rise zone of the third section is set to 715°C.

[0112] In the heating zone of the third section, the temperature of the first to the 29th zones is increased by 2℃ to 3℃ per zone until the temperature of the 29th zone is 710℃, and the temperature of the 30th to the 45th zones is increased by 0℃ to 1℃ per zone until the temperature of the 45th zone is 715℃. The cooling zone of the third section is reduced by 2℃ to 4℃ per zone until it is reduced to 710℃ in the 52nd zone. It should be noted that during the heating process of the first to the 29th zones, the heating rate between each zone is not a fixed value, but can vary within the range of 2℃ to 3℃. Similarly, the heating rate of the 30th to the 45th zone is also a range value, and the cooling rate of the cooling zone is also a range value.

[0113] Taking the 3rd section temperature setting as the reference value, in the same zone, the temperature of the 2nd section is 5°C lower than that of the 3rd section. Taking the 2nd section temperature setting as the reference value, in the same zone, the temperature of the 1st section is 5°C lower than that of the 2nd section. Taking the 3rd section temperature setting as the reference value, in the same zone, the temperature of the 4th section is 5°C lower than that of the 3rd section. Taking the 4th section temperature setting as the reference value, in the same zone, the temperature of the 5th section is 5°C lower than that of the 4th section.

[0114] The temperature of the non-coated surface is lower than the temperature of the corresponding position of the coated surface, specifically 15°C lower.

[0115] S3. The double-layer coated photovoltaic glass obtained in S2 is subjected to rapid cooling treatment. The rapid cooling treatment adopts air cooling treatment. The wind pressure of the rapid cooling wind is 10KPa. The rapid cooling treatment is performed for 3s. The height of the double-layer coated photovoltaic glass from the high-voltage upper wind grid is 8mm, and the height of the double-layer coated photovoltaic glass from the high-voltage lower wind grid is 8mm.

[0116] S4. The double-layer coated photovoltaic glass obtained in S3 is cooled by air cooling. The pressure of the cooling air is 5 KPa. The cooling time is 20 s. The height of the double-layer coated photovoltaic glass from the medium pressure upper wind grid is 20 mm. The height of the double-layer coated photovoltaic glass from the medium pressure lower wind grid is 20 mm.

[0117] S5. Send the double-layer coated photovoltaic glass obtained in S4 out of the tempering furnace for cleaning. The speed of sending the double-layer coated photovoltaic glass out of the tempering furnace is 880 mm / s.

[0118] Comparative Example 2

[0119] Comparative Example 2 provides a double-layer coated photovoltaic glass tempering process. Compared with Example 2, the difference is that the temperature of the coated surface and the temperature of the non-coated surface are switched, and specifically includes the following steps:

[0120] S1. Provide a double-layer coated photovoltaic glass that has been processed by edge grinding and polishing, four-corner chamfering and cleaning. The double-layer coated photovoltaic glass is an embossed photovoltaic glass coated with Covestro double-layer film liquid, with a thickness of 2mm.

[0121] S2, send the double-layer coated photovoltaic glass obtained in S1 into Figure 3 The double-layer coated photovoltaic glass is fed into the tempering furnace at a speed of 528 mm / s. During the heating process, the coated surface and the non-coated surface are heated simultaneously by double-sided heating, and the heating time is 90 seconds.

[0122] Along the length direction of the tempering furnace, the tempering furnace is divided into 52 temperature control zones, including zone 1 to zone 52. Along the width direction of the tempering furnace, the tempering furnace is divided into 5 sections, including section 1 to section 5.

[0123] The 52 temperature control zones of the tempering furnace are divided into three parts. The first part is the heating zone, which is set from zone 1 to zone 29; the second part is the slow heating zone, which is set from zone 30 to zone 45; the third part is the cooling zone, which is set from zone 46 to zone 52.

[0124] Temperature curve distribution of coating surface:

[0125] The temperature of the 45th zone of the slow rise zone of the 3rd section is set to 720°C.

[0126] In the heating zone of the third section, the temperature of zones 1 to 29 is set to increase by 2℃ to 3℃ per zone until the temperature of zone 29 is increased to 710℃. The temperature of zones 30 to 45 is increased by 0℃ to 2℃ per zone until the temperature reaches 720℃ in zone 45. The temperature reduction zone of the third section is reduced by 0℃ to 3℃ per zone until it reaches 704℃ in zone 52. It should be noted that during the heating process of zones 1 to 29, the heating rate between each zone is not a fixed value, but can vary within the range of 2℃ to 3℃. Similarly, the heating rate of zones 30 to 45 is also a range value, and the cooling rate of the cooling zone is also a range value.

[0127] Taking the temperature setting of the 3rd section as the reference value, within the same zone, the 1st to 28th zones of the 2nd section will be reduced by 5°C respectively, and the 29th to 52nd zones of the 2nd section will be reduced by 4°C respectively.

[0128] The temperature of the first section is set as the reference value of the temperature of the second section. In the same zone, the temperature of the first section is 5°C lower than that of the second section.

[0129] Taking the temperature setting of the 3rd section as the reference value, within the same zone, the 1st to 28th zones of the 4th section will be reduced by 5°C respectively, and the 29th to 52nd zones of the 4th section will be reduced by 4°C respectively.

[0130] The temperature setting of the 5th section is based on the temperature setting of the 4th section. In the same zone, the temperature of the 5th section is 5°C lower than that of the 4th section.

[0131] Non-coated surface temperature setting:

[0132] The temperatures of the non-coated surfaces in sections 1, 2, 4 and 5 are 10°C lower than the temperatures in the same area of ​​the coated surface respectively; the temperatures of the non-coated surfaces in zones 1 to 28 of section 3 are 20°C lower than the temperatures in the same area of ​​the coated surface, and the temperatures of the non-coated surfaces in zones 29 to 52 are 15°C lower than the temperatures in the same area of ​​the coated surface.

[0133] S3. The double-layer coated photovoltaic glass obtained in S2 is subjected to rapid cooling treatment. The rapid cooling treatment adopts air cooling treatment. The rapid cooling wind pressure is 9 KPa. The rapid cooling treatment time is 4 seconds. The height of the double-layer coated photovoltaic glass from the high-voltage upper wind grid is 12 mm. The height of the double-layer coated photovoltaic glass from the high-voltage lower wind grid is 12 mm.

[0134] S4. The double-layer coated photovoltaic glass obtained in S3 is cooled by air cooling. The cooling air pressure is 3 KPa. The cooling time is 30 s. The height of the double-layer coated photovoltaic glass from the medium pressure upper wind grid is 25 mm. The height of the double-layer coated photovoltaic glass from the medium pressure lower wind grid is 25 mm.

[0135] S5. Send the double-layer coated photovoltaic glass obtained in S4 out of the tempering furnace for cleaning. The speed of sending the double-layer coated photovoltaic glass out of the tempering furnace is 950 mm / s.

[0136] Comparative Example 3

[0137] Comparative Example 3 provides a double-layer coated photovoltaic glass tempering process. Compared with Example 3, the difference is that the temperature of the coated surface and the temperature of the non-coated surface are switched, and specifically includes the following steps:

[0138] S1. Provide a double-layer coated photovoltaic glass that has been processed by edge grinding and polishing, four-corner chamfering and cleaning. The double-layer coated photovoltaic glass is an embossed photovoltaic glass coated with Covestro double-layer film liquid, with a thickness of 2mm.

[0139] S2, send the double-layer coated photovoltaic glass obtained in S1 into Figure 3 The double-layer coated photovoltaic glass is fed into the tempering furnace at a speed of 584 mm / s. During the heating process, the coated surface and the non-coated surface are heated simultaneously by double-sided heating, and the heating time is 115 seconds.

[0140] Along the length direction of the tempering furnace, the tempering furnace is divided into 52 temperature control zones, including zone 1 to zone 52. Along the width direction of the tempering furnace, the tempering furnace is divided into 5 sections, including section 1 to section 5.

[0141] The 52 temperature control zones of the tempering furnace are divided into three parts. The first part is the heating zone, which is set from zone 1 to zone 29; the second part is the slow heating zone, which is set from zone 30 to zone 45; the third part is the cooling zone, which is set from zone 46 to zone 52.

[0142] Coating surface temperature curve distribution:

[0143] The temperature of the 45th zone of the slow rise zone of the 3rd section is set to 725°C.

[0144] The temperature rise zones of the third section are set as follows: Zones 1 to 13 are heated at an increase of 0°C to 4°C per zone, and Zones 14 to 28 are heated at an increase of 0°C to 3°C per zone, until the temperature reaches 710°C in Zone 29.

[0145] The temperature of zones 30 to 45 is increased by 0°C to 5°C per zone until it reaches 725°C in zone 45.

[0146] The temperature in the cooling zone of the third section is reduced by 0℃ to 3℃ in each zone until it is reduced to 700℃ in zone 52. It should be noted that during the heating and cooling process, the heating rate or cooling rate between each zone is not a fixed value, but can vary within a certain range of values.

[0147] Taking the temperature setting of the 3rd section as the reference value, within the same zone, the 1st to 28th zones of the 2nd section will be reduced by 5°C respectively, and the 29th to 52nd zones will be reduced by 4°C respectively.

[0148] The temperature of the first section is set with the temperature of the second section as the reference value. In the same zone, the temperature of the first section is 5°C lower than that of the second section.

[0149] Taking the temperature setting of the 3rd section as the reference value, within the same zone, the 1st to 28th zones of the 4th section will be reduced by 5°C respectively, and the 29th to 52nd zones will be reduced by 4°C respectively.

[0150] The temperature setting of the 5th section is based on the temperature setting of the 4th section. In the same zone, the temperature of the 5th section is 5°C lower than that of the 4th section.

[0151] Non-coated surface temperature setting:

[0152] The temperatures of the non-coated surfaces in sections 1, 2, 4 and 5 are 18°C ​​lower than the temperature of the same area on the coated surface; the temperatures of the non-coated surfaces in sections 1 to 28 of section 3 are 18°C ​​lower than the temperature of the same area on the coated surface, and the temperatures of the non-coated surfaces in sections 29 to 52 are 17°C lower than the temperature of the same area on the coated surface.

[0153] S3. The double-layer coated photovoltaic glass obtained in S2 is subjected to rapid cooling treatment. The rapid cooling treatment adopts air cooling. The rapid cooling air pressure is 12 KPa. The rapid cooling treatment time is 3 s. The height of the double-layer coated photovoltaic glass from the high-voltage upper wind grid is 12 mm. The height of the double-layer coated photovoltaic glass from the high-voltage lower wind grid is 12 mm.

[0154] S4. Cool the double-layer coated photovoltaic glass obtained in S3. The cooling method is air cooling. The cooling air pressure is 5 KPa. The cooling time is 20 seconds. The height of the double-layer coated photovoltaic glass from the medium pressure upper wind grid is 25 mm. The height of the double-layer coated photovoltaic glass from the medium pressure lower wind grid is 25 mm.

[0155] S5. Send the double-layer coated photovoltaic glass obtained in S4 out of the tempering furnace for cleaning, and the speed at which the double-layer coated glass is sent out of the tempering furnace is 930 mm / s.

[0156] Comparative Example 4

[0157] Comparative Example 4 provides a double-layer coated photovoltaic glass tempering process. Compared with Example 1, the difference is that there are no 52 temperature control zones and 5 sections. During the heating process, the temperature of the coated surface and the temperature of the non-coated surface are kept constant, the temperature of the non-coated surface is 715°C, and the temperature of the coated surface is 15°C lower than the temperature of the non-coated surface. Specifically, the following steps are included:

[0158] S1. Provide a double-layer coated photovoltaic glass that has been processed by edge grinding and polishing, four-corner chamfering and cleaning. The double-layer coated photovoltaic glass is an embossed photovoltaic glass coated with Covestro double-layer film liquid. The thickness of the double-layer coated photovoltaic glass is 2mm.

[0159] S2. The double-layer coated photovoltaic glass obtained in S1 is sent into a tempering furnace for heating treatment. The speed of sending the double-layer coated photovoltaic glass into the tempering furnace is 553 mm / s. During the heating treatment, the coated surface and the non-coated surface are heated simultaneously by double-sided heating, and the heating treatment time is 103 seconds.

[0160] During the heating process, the temperature of the coated surface and the temperature of the non-coated surface are kept constant, the temperature of the non-coated surface is 715°C, and the temperature of the coated surface is lower than the temperature of the corresponding position of the non-coated surface, specifically 15°C lower.

[0161] S3. The double-layer coated photovoltaic glass obtained in S2 is subjected to rapid cooling treatment. The rapid cooling treatment adopts air cooling treatment. The wind pressure of the rapid cooling wind is 10KPa. The rapid cooling treatment is performed for 3s. The height of the double-layer coated photovoltaic glass from the high-voltage upper wind grid is 8mm, and the height of the double-layer coated photovoltaic glass from the high-voltage lower wind grid is 8mm.

[0162] S4. The double-layer coated photovoltaic glass obtained in S3 is cooled by air cooling. The pressure of the cooling air is 5 KPa. The cooling time is 20 s. The height of the double-layer coated photovoltaic glass from the medium pressure upper wind grid is 20 mm. The height of the double-layer coated photovoltaic glass from the medium pressure lower wind grid is 20 mm.

[0163] S5. Send the double-layer coated photovoltaic glass obtained in S4 out of the tempering furnace for cleaning. The speed of sending the double-layer coated photovoltaic glass out of the tempering furnace is 880 mm / s.

[0164] Comparative Example 5

[0165] Comparative Example 5 provides a double-layer coated photovoltaic glass tempering process. Compared with Example 1, the difference is that the temperature of the coated surface is 30° C. lower than the temperature of the corresponding position of the non-coated surface, and specifically includes the following steps:

[0166] S1. Provide a double-layer coated photovoltaic glass that has been processed by edge grinding and polishing, four-corner chamfering and cleaning. The double-layer coated photovoltaic glass is an embossed photovoltaic glass coated with Covestro double-layer film liquid. The thickness of the double-layer coated photovoltaic glass is 2mm.

[0167] S2, send the double-layer coated photovoltaic glass obtained in S1 into Figure 3 The double-layer coated photovoltaic glass is fed into the tempering furnace at a speed of 553 mm / s. During the heating process, the coated surface and the non-coated surface are heated simultaneously by double-sided heating, and the heating time is 103 s.

[0168] Along the length direction of the tempering furnace, the tempering furnace is divided into 52 temperature control zones, including zone 1 to zone 52. Along the width direction of the tempering furnace, the tempering furnace is divided into 5 sections, including section 1 to section 5.

[0169] The 52 temperature control zones of the tempering furnace are divided into three parts. The first part is the heating zone, which is set from zone 1 to zone 29; the second part is the slow heating zone, which is set from zone 30 to zone 45; the third part is the cooling zone, which is set from zone 46 to zone 52.

[0170] Temperature curve distribution of non-coated surface:

[0171] The temperature of the 45th zone in the slow-rise zone of the third section is set to 715°C.

[0172] In the heating zone of the third section, the temperature of the first to the 29th zones is increased by 2℃ to 3℃ per zone until the temperature of the 29th zone is 710℃, and the temperature of the 30th to the 45th zones is increased by 0℃ to 1℃ per zone until the temperature of the 45th zone is 715℃. The cooling zone of the third section is reduced by 2℃ to 4℃ per zone until it is reduced to 710℃ in the 52nd zone. It should be noted that during the heating process of the first to the 29th zones, the heating rate between each zone is not a fixed value, but can vary within the range of 2℃ to 3℃. Similarly, the heating rate of the 30th to the 45th zone is also a range value, and the cooling rate of the cooling zone is also a range value.

[0173] Taking the 3rd section temperature setting as the reference value, in the same zone, the temperature of the 2nd section is 5°C lower than that of the 3rd section. Taking the 2nd section temperature setting as the reference value, in the same zone, the temperature of the 1st section is 5°C lower than that of the 2nd section. Taking the 3rd section temperature setting as the reference value, in the same zone, the temperature of the 4th section is 5°C lower than that of the 3rd section. Taking the 4th section temperature setting as the reference value, in the same zone, the temperature of the 5th section is 5°C lower than that of the 4th section.

[0174] The temperature of the coated surface is lower than the temperature of the corresponding position of the non-coated surface, specifically 30°C lower.

[0175] S3. The double-layer coated photovoltaic glass obtained in S2 is subjected to rapid cooling treatment. The rapid cooling treatment adopts air cooling treatment. The wind pressure of the rapid cooling wind is 10KPa. The rapid cooling treatment is performed for 3s. The height of the double-layer coated photovoltaic glass from the high-voltage upper wind grid is 8mm, and the height of the double-layer coated photovoltaic glass from the high-voltage lower wind grid is 8mm.

[0176] S4. The double-layer coated photovoltaic glass obtained in S3 is cooled by air cooling. The pressure of the cooling air is 5 KPa. The cooling time is 20 s. The height of the double-layer coated photovoltaic glass from the medium pressure upper wind grid is 20 mm. The height of the double-layer coated photovoltaic glass from the medium pressure lower wind grid is 20 mm.

[0177] S5. Send the double-layer coated photovoltaic glass obtained in S4 out of the tempering furnace for cleaning. The speed of sending the double-layer coated photovoltaic glass out of the tempering furnace is 880 mm / s.

[0178] The double-layer coated photovoltaic glass after the above-mentioned embodiment and comparative example is tested, and the double-layer coated photovoltaic glass needs to meet the following technical standards:

[0179] Bow shape: ≤0.25%.

[0180] Waveform: Use a 300mm long blade ruler, close to the glass surface, and use a feeler gauge to measure the gap between the blade ruler and the glass. The gap should not be greater than 0.5mm.

[0181] The warping of the board head is ≤0.5mm.

[0182] Drop ball: A 227g steel ball drops from a height of 1m for photovoltaic glass with a thickness of 2.0mm to 2.5mm without breaking. A 1040g steel ball drops from a height of 1m for photovoltaic glass with a thickness of 3.2mm without breaking.

[0183] Light transmittance: ≥94%.

[0184] Adhesion: ≤1 level.

[0185] The double-layer coated photovoltaic glass obtained by the above-mentioned embodiments and comparative examples was tested by the following method.

[0186] 1. Light transmittance: Detected by spectrophotometer.

[0187] 2. The impact resistance, bow, waveform, surface stress and head warping are tested according to the standard GB / T 34328-2017.

[0188] The ultimate goal of the present invention requires that the board head warpage is ≤0.5mm, and the specific test data are shown in Table 1.

[0189] Table 1 Performance test data of double-layer coated photovoltaic glass of Examples 1 to 3 and Comparative Examples 1 to 5

[0190]

[0191] It can be seen from the data in Table 1 that the double-layer coated photovoltaic glass obtained by the double-layer coated photovoltaic glass tempering process of Examples 1 to 3 has a board head warpage of ≤0.5mm, which meets the requirements. In Comparative Examples 1 to 3, the temperature of the coated surface is higher than the temperature of the non-coated surface, and the board head warpage does not meet the requirements. This shows that in Examples 1 to 3, setting the coated surface temperature to be lower than the non-coated surface temperature helps to reduce the board head warpage. In Comparative Example 4, the glass is heated at a constant temperature, which leads to severe board head warpage. In Comparative Example 5, although the coated surface temperature is set to be lower than the non-coated surface temperature, the temperature difference is too large, which makes the glass easy to break. Therefore, during the heating process, not only is it required that the coated surface temperature is lower than the non-coated surface temperature, but it is also necessary to ensure that the temperature difference between the two is not too large, generally 10°C to 20°C.

[0192] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, they are also intended to be included.

Claims

1. A double-layer coated photovoltaic glass tempering process, characterized in that: The following steps are involved: Provide double-layer coated photovoltaic glass with edge grinding and polishing, corner chamfering and cleaning; The double-layer coated photovoltaic glass is sent into a tempering furnace for heating treatment; during the heating treatment, the tempering furnace is divided into a plurality of temperature control zones and sections along the length and width directions of the tempering furnace, and the coated surface and the non-coated surface are heated simultaneously by a double-sided heating method, and the temperature of the coated surface is lower than the temperature of the corresponding position of the non-coated surface, and the temperature difference is 10°C to 20°C; Rapidly cooling the double-layer coated photovoltaic glass after the heating treatment; Cooling the double-layer coated photovoltaic glass after the rapid cooling treatment; The double-layer coated photovoltaic glass after the cooling treatment is sent out of the tempering furnace for cleaning; Double-layer coating refers to coating the surface of photovoltaic glass with a bottom film and a surface film respectively. The surface film is a dense structure of porous silicon dioxide, and its porosity is smaller than that of the bottom film. During the heating process, the tempering furnace is divided into 52 temperature control zones along the length direction of the tempering furnace, including zone 1 to zone 52; the 52 temperature control zones are divided into three parts: The first part is the temperature rise zone, which is set from zone 1 to zone 29; The second part is the slow rise area, which is set from zone 30 to zone 45; The third part is the cooling zone, which is set from zone 46 to zone 52; The tempering furnace is divided into 5 sections along the width direction of the tempering furnace, including the first section to the fifth section; Temperature curve distribution of non-coated surface: The temperature of the heating zone of the third section is set as follows: the temperature of the first zone is increased from 630°C to the temperature of the 29th zone is 710°C to 715°C; the temperature of the slow rising zone of the third section is set as follows: the temperature of the 30th zone is increased to the temperature of the 45th zone is 715°C to 730°C; the temperature of the cooling zone of the third section is set as follows: the temperature of the 46th zone is decreased to the temperature of the 52nd zone is 700°C to 710°C; Taking the temperature setting of section 3 as the reference value, in the same zone, the temperature of section 2 is 4°C to 5°C lower than that of section 3; taking the temperature setting of section 2 as the reference value, in the same zone, the temperature of section 1 is 5°C lower than that of section 2; taking the temperature setting of section 3 as the reference value, in the same zone, the temperature of section 4 is 4°C to 5°C lower than that of section 3; taking the temperature setting of section 5 as the reference value, in the same zone, the temperature of section 5 is 5°C lower than that of section 4.

2. The double-layer coated photovoltaic glass tempering process according to claim 1, characterized in that: A heat balance device is provided in the first to 26th zones of the tempering furnace, the heat balance device comprises a first heat balance pipe, a first heat-resistant steel pipe, a second heat balance pipe and a second heat-resistant steel pipe, and holes are provided on the first heat-resistant steel pipe and the second heat-resistant steel pipe; A first heating wire is arranged above the double-layer coated photovoltaic glass, and a plurality of first heat-resistant steel pipes are installed at the lower end of the first heating wire, one end of the first heat balance pipe is connected to the first heat-resistant steel pipe, and the other end of the first heat balance pipe is connected to the compressed air end; a second heating wire is arranged below the double-layer coated photovoltaic glass, and a radiation plate is installed above the second heating wire, and a plurality of second heat-resistant steel pipes are installed on the upper end of the radiation plate, one end of the second heat balance pipe is connected to the second heat-resistant steel pipe, and the other end of the second heat balance pipe is connected to the compressed air end.

3. The double-layer coated photovoltaic glass tempering process according to claim 1, characterized in that: The heating treatment time is 90s to 115s.

4. The double-layer coated photovoltaic glass tempering process according to claim 1, characterized in that: The rapid cooling treatment adopts air cooling. A high-pressure upper wind grid and a high-pressure lower wind grid are respectively arranged above and below the double-layer coated photovoltaic glass. The high-pressure upper wind grid and the high-pressure lower wind grid simultaneously transport rapid cooling air to perform rapid cooling treatment on the double-layer coated photovoltaic glass. The wind pressure of the rapid cooling air is 9KPa~12KPa, and the rapid cooling treatment time is 3s~4s.

5. The double-layer coated photovoltaic glass tempering process according to claim 4, characterized in that: The height of the double-layer coated photovoltaic glass from the high-voltage upper wind grid and the high-voltage lower wind grid is 8mm to 12mm.

6. The double-layer coated photovoltaic glass tempering process according to claim 1, characterized in that: The cooling treatment adopts air cooling. A medium-pressure upper wind grid and a medium-pressure lower wind grid are respectively arranged above and below the double-layer coated photovoltaic glass. The medium-pressure upper wind grid and the medium-pressure lower wind grid simultaneously transport cooling air to cool the double-layer coated photovoltaic glass. The wind pressure of the cooling air is 3KPa~5KPa, and the cooling treatment time is 20s~30s.

7. The double-layer coated photovoltaic glass tempering process according to claim 6, characterized in that: The height of the double-layer coated photovoltaic glass from the medium pressure upper wind grid and the medium pressure lower wind grid is 20mm to 25mm.

8. The double-layer coated photovoltaic glass tempering process according to claim 1, characterized in that: The thickness of the double-layer coated photovoltaic glass is 2 mm.

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