Modified polyurethane coating, preparation method thereof and photovoltaic silicon wafer cutting main roller

Abstract

The invention relates to the technical field of photovoltaic cutting, in particular to a modified polyurethane coating, a preparation method of the modified polyurethane coating and a photovoltaic silicon wafer cutting main roller. The modified polyurethane coating provided by the invention is prepared from the following raw materials in parts by mass: 98 to 102 parts of isocyanate, 18 to 20 parts of polyol and 0.1 to 1 part of silicon carbide. The preparation method of the modified polyurethane coating comprises the following steps: uniformly mixing isocyanate, polyol and silicon carbide, pouring into a mold, and vulcanizing to obtain the modified polyurethane coating. The photovoltaic silicon wafer cutting main roller comprises a main roller base body and a coating arranged on the surface of the main roller base body. The coating comprises the modified polyurethane coating. According to the modified polyurethane coating disclosed by the invention, silicon carbide is added into the polyurethane coating, so that the mechanical strength, the wear resistance and the thermal stability are remarkably improved, and when the modified polyurethane coating is applied to the surface of a main roller for cutting a photovoltaic silicon wafer, the service life of the main roller is prolonged, the cost is reduced, and the cutting efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photovoltaic cutting, in particular to a modified polyurethane coating, a preparation method thereof and a photovoltaic silicon wafer cutting main roller. BACKGROUND

[0002] Photovoltaic silicon wafer cutting is a key step in the manufacturing process of solar cells, mainly using multi-wire cutting technology. The cutting wire used in photovoltaic silicon wafer cutting is mainly diamond cutting wire, also known as diamond wire. The diamond wire is made of high-carbon steel wire as the base wire, with diamond micro-powder particles electroplated on the surface. This cutting wire can achieve cutting of silicon wafers through high-speed grinding motion, with the advantages of fast cutting speed, high wafer yield, and small environmental pollution. The main roller is one of the core components in photovoltaic silicon wafer cutting. The main function of the main roller is to support and guide the high-speed moving diamond wire to make it contact with the surface of the silicon material, and to achieve the cutting of the silicon wafer through grinding. The main roller is usually made of metal and coated with a special coating to improve wear resistance and reduce friction during cutting. The design and manufacture of the main roller have a significant impact on cutting efficiency and silicon wafer quality.

[0003] In the process of photovoltaic silicon wafer cutting, a layer of polyurethane material is coated on the surface of the main roller. The main purpose of using polyurethane coating is to improve cutting efficiency and silicon wafer quality. Polyurethane coating has excellent wear resistance, temperature resistance and chemical stability. These properties help to protect the diamond wire during cutting, reduce wear and tear, and thus prolong the service life of the diamond wire. In addition, the polyurethane coating can also improve the smoothness of the cutting process, reduce damage to the edges of the silicon waafers, and improve the overall quality of the silicon wafers, which is crucial for improving the conversion efficiency of solar cells.

[0004] The polyurethane coating on the surface of the main roller is mainly used to improve wear resistance and reduce friction to protect the main roller and improve cutting efficiency. However, the polyurethane coating also has some shortcomings. Although the polyurethane coating has certain wear resistance and scratch resistance, these properties may gradually decrease during long-term high-load cutting operations, leading to wear and damage of the polyurethane coating. Once the polyurethane coating is worn or damaged, the main roller needs to be replaced. Frequent coating and replacement of the main roller will result in additional time and cost.

[0005] Therefore, the present application is proposed. SUMMARY

[0006] The first object of the present application is to provide a modified polyurethane coating. Silicon carbide is added to the polyurethane coating to form a dense structure inside and on the surface of the polyurethane coating, significantly improving the mechanical strength, wear resistance and thermal stability of the polyurethane coating.

[0007] The second object of the present application is to provide a preparation method of the modified polyurethane coating, which is simple in steps.

[0008] The third object of the present application is to provide a photovoltaic silicon wafer cutting main roller, which uses a modified polyurethane coating on the surface of the main roller, prolongs the service life of the main roller, reduces the cost, and improves the cutting efficiency.

[0009] In order to achieve the above object of the present application, the following technical solutions are adopted: In a first aspect, the present application provides a modified polyurethane coating, which comprises the following raw materials in terms of mass fraction: 98-102 parts of isocyanate, 18-20 parts of polyol and 0.1-1 parts of silicon carbide.

[0010] Further, the modified polyurethane coating comprises the following raw materials in terms of mass fraction: 100 parts of isocyanate, 18.9 parts of polyol and 0.4-1 parts of silicon carbide Further, the isocyanate comprises toluene-2,4-diisocyanate. And / or, the polyol comprises polytetrahydrofuran.

[0011] Further, the particle size of the silicon carbide is 250-300 nm.

[0012] In a second aspect, the present application further provides a preparation method of the modified polyurethane coating as described above, comprising the following steps: After mixing the isocyanate, the polyol and the silicon carbide uniformly, pouring into a mold, and vulcanizing, the modified polyurethane coating is obtained.

[0013] Further, the mixing uniformly comprises: mixing the isocyanate and the silicon carbide uniformly to obtain material A; stirring the material A and the polyol at 100-120℃ for 1.5-3h to obtain material B.

[0014] Further, the temperature of the mold is 100-115℃.

[0015] Further, the vulcanizing comprises: performing primary vulcanization at 100-110℃ for 0.5-2h, and after correction, performing secondary vulcanization at 100-110℃ for more than 16h.

[0016] In a third aspect, the present application further provides a photovoltaic silicon wafer cutting main roller, which comprises a main roller base body and a coating arranged on the surface of the main roller base body. The coating comprises the modified polyurethane coating as described above.

[0017] Further, the thickness of the modified polyurethane coating is 12-13mm.

[0018] Compared with the prior art, the present application has the following beneficial effects: The modified polyurethane coating provided by the present application adds silicon carbide into the polyurethane coating to form a dense structure inside and on the surface of the polyurethane coating, thereby significantly improving the mechanical strength, wear resistance and thermal stability of the polyurethane coating.

[0019] The modified polyurethane coating is used on the surface of a main roller for cutting photovoltaic silicon wafers, thereby prolonging the service life of the main roller, reducing the cost and improving the cutting efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments will be briefly introduced as follows. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. Other related drawings can be obtained by those skilled in the art without creative labor.

[0021] Figure 1 The PLM pictures of the silicon carbide particles in the modified polyurethane coating of Example 1 of the present application. DETAILED DESCRIPTION

[0022] The technical solutions of the present application will be described clearly and completely in combination with the drawings and specific embodiments. However, those skilled in the art will understand that the following described embodiments are part of the embodiments of the present application, but not all the embodiments, and are only used to illustrate the present application, and should not be regarded as limiting the scope of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application. The specific conditions are not specified in the embodiments, and are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not specified by the manufacturer, and are conventional products that can be purchased on the market.

[0023] A modified polyurethane coating, a preparation method thereof and a main roller for cutting photovoltaic silicon wafers will be described in detail as follows.

[0024] In some embodiments of the present application, a modified polyurethane coating is provided, which comprises the following raw materials in terms of mass fraction: Isocyanate 98-102 parts, polyol 18-20 parts and silicon carbide (SiC) 0.1-1 part.

[0025] The modified polyurethane coating provided by the present application adds silicon carbide into the polyurethane coating to form a dense structure inside and on the surface of the polyurethane coating, thereby significantly improving the mechanical strength, wear resistance and thermal stability of the polyurethane coating.

[0026] The addition of silicon carbide can significantly improve the compression resistance, tensile resistance and impact resistance of the polyurethane coating.

[0027] Silicon carbide has a Mohs hardness slightly lower than diamond, which is the hardest material known in nature, with a Mohs hardness of 10, while the Mohs hardness of silicon carbide is between 9.2 and 9.8, so that the polyurethane coating modified by silicon carbide has better wear resistance.

[0028] Silicon carbide has excellent thermal conductivity, with a theoretical thermal conductivity of 490 W / (m·K), and its introduction into the polyurethane coating can effectively improve the thermal stability thereof.

[0029] In different embodiments of the present application, the mass fractions of the raw materials of the modified polyurethane coating can be as follows, respectively: The mass fraction of isocyanate can be 98 parts, 99 parts, 100 parts, 101 parts, 102 parts, or a range value formed by any two of them; The mass fraction of polyol can be 18 parts, 18.5 parts, 19 parts, 19.5 parts, 20 parts, or a range value formed by any two of them; The mass fraction of silicon carbide can be 0.1 parts, 0.2 parts, 0.4 parts, 0.6 parts, 0.8 parts, 1 part, or a range value formed by any two of them.

[0030] In some embodiments of the present application, the modified polyurethane coating comprises the following raw materials in terms of mass fraction: 100 parts of isocyanate, 18.9 parts of polyol, and 0.4-1 parts of silicon carbide.

[0031] In order to obtain a modified polyurethane coating with more excellent performance, the contents of the raw materials of the modified polyurethane coating are optimized, which is beneficial to further improve the performance of the modified polyurethane coating.

[0032] In the modified polyurethane coating, if the content of silicon carbide is too high, the hardness of the modified polyurethane coating is too high, and the mechanical processing difficulty is increased; if the content of silicon carbide is too low, the wear resistance of the polyurethane coating is low, and the main roll groove is easy to fatigue and wear.

[0033] In some embodiments of the present application, the isocyanate comprises toluene-2,4-diisocyanate (liquid).

[0034] In some embodiments of the present application, the polyol comprises polytetrahydrofuran (granules); preferably, the particle size of the polytetrahydrofuran is 3-5 mm.

[0035] In some embodiments of the present application, the particle size of the silicon carbide (powder) is 250-300 nm; typically but not limitedly, for example, the particle size of the silicon carbide can be 250 nm, 260 nm, 270 nm, 280 nm, 290 nm, 300 nm, or a range value formed by any two of them; preferably, the particle size of the silicon carbide is 300 nm.

[0036] In some embodiments of the present application, a preparation method of the modified polyurethane coating is also provided, comprising the following steps: After mixing the isocyanate, the polyol and the silicon carbide, pouring into a mold, and vulcanizing, a modified polyurethane coating is obtained.

[0037] In some embodiments of the present application, the mixing comprises: mixing the isocyanate and the silicon carbide to obtain material A; stirring the material A and the polyol at 100-120°C for 1.5-3h to obtain material B.

[0038] In some embodiments of the present application, the mixing comprises: drying the isocyanate at 100-120°C for 1-3h, adding the silicon carbide into the dried isocyanate, and stirring to uniformly disperse the silicon carbide in the dried isocyanate to obtain material A; Under vacuum conditions, stirring the material A and the polyol at 100-120°C for 1.5-3h, and after sufficient mixing, obtaining material B (melted modified polyurethane).

[0039] The main purpose of mixing under vacuum conditions is to prevent a large number of bubbles from being generated during stirring.

[0040] In some embodiments of the present application, the temperature of the mold is 100-115°C; typically but not limitedly, for example, the temperature of the mold can be 100°C, 105°C, 110°C, 115°C, or a range value formed by any two of them.

[0041] In some embodiments of the present application, the vulcanization comprises: primary vulcanization at 100-110°C for 0.5-2h, and after correction, secondary vulcanization at 100-110°C for more than 16h.

[0042] In some embodiments of the present application, the vulcanization comprises: primary vulcanization at 105±2°C for 55-65min, and after correction, secondary vulcanization at 105±2°C for 16h.

[0043] In some embodiments of the present application, the correction comprises: checking whether the pouring product has defects and correcting the pouring product coating layer hardness adjustment to meet the standard.

[0044] The application also provides a photovoltaic silicon wafer cutting main roller in some embodiments of the application, comprising a main roller base and a coating layer arranged on the surface of the main roller base. The coating layer comprises the modified polyurethane coating layer.

[0045] The photovoltaic silicon wafer cutting main roller is a main roller in a photovoltaic silicon wafer cutting machine.

[0046] The modified polyurethane coating layer is used in the photovoltaic silicon wafer cutting main roller, which improves the mechanical strength, makes the main roller more suitable for service in a high-load and high-wear environment, improves the wear resistance, makes the main roller exhibit better wear resistance in high-speed friction with a diamond wire, thereby prolongs the service life of the main roller and improves the cutting efficiency, and improves the thermal stability, which can timely conduct the heat generated by the high-speed friction between the diamond wire and the main roller.

[0047] In some embodiments of the application, the thickness of the modified polyurethane coating layer is 12-13 mm; preferably 12.5 mm.

[0048] The application also provides a preparation method of the photovoltaic silicon wafer cutting main roller in some embodiments of the application, comprising the following steps: After the isocyanate, the polyol and the silicon carbide are uniformly mixed, they are poured into a main roller coating mold, and after vulcanization, the photovoltaic silicon wafer cutting main roller is obtained.

[0049] In some embodiments of the application, the main roller coating mold is a mold cavity composed of a double-bottom-free barrel side and a main roller core and a cover plate.

[0050] Examples 1-7 The preparation method of the modified polyurethane coating layer provided in this example comprises the following steps: The toluene-2,4-diisocyanate is dried at 105°C for 2h, the silicon carbide is added into the dried toluene-2,4-diisocyanate, and a stirrer is used to uniformly stir at a speed of 4r / min for 5min, so that the silicon carbide is uniformly dispersed in the dried isocyanate to obtain material A; The material A and the polytetrahydrofuran are added into a mixing bin, and continuously stirred at 105°C for 2h while maintaining a vacuum condition in the mixing bin to obtain material B; The material B is poured into a main roller coating mold (the main roller coating mold is a mold cavity composed of a double-bottom-free barrel side and a main roller core and a cover plate); After pouring, it is placed into an oven for primary vulcanization at 105°C for 1h, and then demolding is performed to check whether the poured product has defects and correct the poured product (three-component proportion calibration, coating layer hardness, pore defect quality state); the corrected poured product is again placed into the oven for secondary vulcanization at 105°C for 16h to obtain the modified polyurethane coating layer, and the thickness of the modified polyurethane coating layer is 12.5mm.

[0051] The mass fractions of toluene-2,4-diisocyanate, polytetrahydrofuran, and silicon carbide, as well as the particle size of silicon carbide, are shown in Table 1.

[0052] Table 1

[0053] Comparative Example 1 The preparation method of the polyurethane coating provided in this comparative example is the same as that in Example 1, except that silicon carbide was not added.

[0054] Test case Visual examination of the silicon carbide particles in Example 1 and the silicon carbide particles in the modified polyurethane coating under a high-power microscope was performed, and the results are as follows: Figure 1 As shown; Figure 1 Images (a1) and (a2) show pure silicon carbide particle PLM (full life cycle) at 200x and 500x magnification, respectively. Figure 1 Images (b1), (b2), (c1), and (c2) show silicon carbide particles in the modified polyurethane coating at 200x and 500x magnification, respectively, representing the PLM (full life cycle) of the particles.

[0055] from Figure 1 It can be seen that silicon carbide has a large particle size and poor dispersion, and exhibits agglomeration.

[0056] The performance of the modified polyurethane coatings prepared in Examples 1-7 and the polyurethane coating prepared in Comparative Example 1 was tested, and the results are shown in Table 2.

[0057] Test methods: The Shore hardness tester, TAB tester and stylus roughness tester were used respectively.

[0058] Table 2

[0059] The performance of photovoltaic silicon wafer cutting main rollers containing the modified polyurethane coatings of Examples 1-7 and the polyurethane coating of Comparative Example 1 were tested, and the results are recorded in Table 3.

[0060] Table 3

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A modified polyurethane coating, characterized in that, By weight, it includes the following raw materials: 98-102 parts isocyanate, 18-20 parts polyol and 0.1-1 parts silicon carbide.

2. The modified polyurethane coating according to claim 1, characterized in that, By weight, it includes the following raw materials: 100 parts isocyanate, 18.9 parts polyol and 0.4 to 1 part silicon carbide.

3. The modified polyurethane coating according to claim 1, characterized in that, The isocyanate includes toluene-2,4-diisocyanate; And / or, the polyol includes polytetrahydrofuran.

4. The modified polyurethane coating according to claim 2, characterized in that, The silicon carbide has a particle size of 250~300nm.

5. The method for preparing the modified polyurethane coating according to any one of claims 1 to 4, characterized in that, Includes the following steps: After mixing isocyanate, polyol and silicon carbide, the mixture is poured into a mold and vulcanized to obtain the modified polyurethane coating.

6. The method for preparing the modified polyurethane coating according to claim 5, characterized in that, The mixing process includes: mixing isocyanate and silicon carbide to obtain material A; and stirring material A and polyol at 100-120°C for 1.5-3 hours to obtain material B.

7. The method for preparing the modified polyurethane coating according to claim 5, characterized in that, The temperature of the mold is 100~115℃.

8. The method for preparing the modified polyurethane coating according to claim 5, characterized in that, The vulcanization process includes: a first vulcanization at 100-110°C for 0.5-2 hours, followed by a second vulcanization at 100-110°C for more than 16 hours after correction.

9. A photovoltaic silicon wafer cutting main roller, characterized in that, Includes a main roller substrate and a coating disposed on the surface of the main roller substrate; The coating comprises the modified polyurethane coating as described in any one of claims 1 to 4.

10. The photovoltaic silicon wafer cutting main roller according to claim 9, characterized in that, The thickness of the modified polyurethane coating is 12-13 mm.

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