Preparation method and application of transparent silicone coating

Abstract

The application relates to the technical field of silicone coating preparation, and discloses a preparation method and application of transparent silicone coating. The preparation method comprises the following steps: mixing tetraethyl orthosilicate, methyl triethoxysilane, phenyl trimethoxysilane, dimethyl diethoxysilane, chloropropyl triethoxysilane and KH560 according to a specific proportion to obtain a silicone solution; dropping mixed acid liquid into the silicone solution while stirring, hydrolyzing and polycondensing to obtain a silicone resin; mixing silicone modified hydroxyl acrylic resin, polyester resin, isocyanate curing agent, dispersant, specific transparent filler, light-resistant and oxidation-resistant auxiliary agent, defoaming agent and water-based solvent according to a specific proportion, grinding and filtering to obtain silicone modified hydroxyl acrylic resin coating; and mixing 100 parts of the silicone resin and 20-100 parts of the silicone modified hydroxyl acrylic resin coating to obtain transparent silicone coating. The coating has good adhesion and adhesion to photovoltaic substrates, high hardness and good wear resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of silicone coating preparation, in particular to a preparation method and application of transparent silicone coating. BACKGROUND

[0002] Silicone resin is a polysiloxane resin, which is generally prepared by sol-gel method from various siloxane monomers, inorganic high-temperature-resistant pigments and fillers, etc. The cured coating layer is similar to enamel structure, and has many advantages such as good weather resistance, high hardness, high temperature resistance, flame retardation, environmental protection and non-toxicity, etc. It has been more and more applied and concerned in technical fields such as rail transit, building curtain wall and non-stick pot.

[0003] Although the existing silicone resin (such as the solvent-free methyl silicone resin and its manufacturing process provided in the publication CN110144044A) is outstanding in properties such as weather resistance and hardness, it also has defects that cannot be ignored. The flexibility of this kind of silicone resin is very poor, and the deformation of photovoltaic substrate can easily cause the peeling and cracking of the silicone resin coating coated on the photovoltaic substrate. Without the aid of catalysts or curing agents, the curing speed of the silicone coating prepared by using this silicone resin on the photovoltaic substrate for photovoltaic backboard is slow, and it is difficult to reach the surface dryness in a short time, resulting in a long process cycle. Moreover, the adhesion of the silicone coating prepared by using this silicone resin on the photovoltaic substrate (especially the adhesion after PCT aging and the water boiling resistance) is poor, and the friction resistance also needs to be improved.

[0004] Based on this, the publication CN111621228A provides an easy-to-clean coating with high hardness and high toughness. The coating simultaneously adds a tough silicone resin and a brittle silicone resin. The tough silicone resin is selected from the group consisting of silicone-modified hydroxy acrylate resin, silicone-modified polyurethane resin, silicone-modified fluorocarbon resin, silicone-modified alkyd resin, silicone-modified epoxy resin and combinations thereof, while the brittle silicone resin is selected from the group consisting of methyl silicone resin, octyl silicone resin, oily silicone sol, phenyl silicone resin and combinations thereof. By adjusting the ratio of the tough silicone resin and the brittle silicone resin, the coating has high toughness and high hardness, and the wear resistance of the coating is also improved, and the coating also has easy-to-clean performance. However, this coating still has defects such as slow curing speed, poor adhesion (especially the adhesion after PCT aging and the water boiling resistance), etc., and it is difficult to be applied to prepare high-quality coated transparent photovoltaic backboard. SUMMARY

[0005] The present application aims to overcome the shortcomings of the prior art, and provides a preparation method and application of transparent silicone coating.

[0006] Based on this, the application discloses a preparation method of transparent silicone paint, comprising the following preparation steps:

[0007] S1, preparation of silicone resin:

[0008] S11, tetraethyl orthosilicate, methyl triethoxysilane, phenyl trimethoxysilane, dimethyl diethoxysilane, chloropropyl triethoxysilane and KH560 are mixed in a weight ratio of 10-20:30-40:10:5:5:10, stirred uniformly to obtain a silicone solution; water, acetic acid and isopropyl alcohol are mixed in a weight ratio of 18:2:1-10, stirred uniformly to obtain a mixed acid solution;

[0009] S12, the mixed acid solution is slowly added to the silicone solution while stirring, and the silicone solution is continuously stirred to carry out hydrolysis and polycondensation reaction, thereby obtaining the silicone resin;

[0010] S2, the silicone modified hydroxyl acrylic resin, polyester resin, isocyanate curing agent, dispersant, transparent filler, light-resistant and antioxidant auxiliary agent, defoaming agent, water-based solvent are mixed in a mass ratio of 20-30:5-20:9:0.2:30-40:0.6:0.2:20-30, ground, filtered to obtain the silicone modified hydroxyl acrylic resin paint;

[0011] The transparent filler comprises fumed silica, aluminum oxide and zinc oxide which are mixed in a mass ratio of 10-15:3-5:0.1-1;

[0012] S3, 100 parts of the silicone resin and 20-100 parts of the silicone modified hydroxyl acrylic resin paint are mixed and stirred uniformly to obtain the transparent silicone paint.

[0013] Preferably, in step S11, the tetraethyl orthosilicate, methyl triethoxysilane, phenyl trimethoxysilane, dimethyl diethoxysilane, chloropropyl triethoxysilane and KH560 are mixed in a weight ratio of 10-20:30:10:5:5:10.

[0014] Further preferably, in step S11, the tetraethyl orthosilicate, methyl triethoxysilane, phenyl trimethoxysilane, dimethyl diethoxysilane, chloropropyl triethoxysilane and KH560 are mixed in a weight ratio of 20:30:10:5:5:10;

[0015] The water, acetic acid and isopropyl alcohol are mixed in a weight ratio of 18:2:10.

[0016] Preferably, in step S12, the dropping time is 30-60 minutes, and the continuous stirring time is 3-6 hours.

[0017] The basic principle of obtaining the silicone resin by hydrolysis and polycondensation of the organosilane in the silicone solution in step S1 of the present application is as follows:

[0018] For example, the hydrolysis of dialkyldialkoxysilane (such as dimethyldiethoxysilane) produces a silanediol, and the subsequent polycondensation can produce linear polymers in various forms. Taking dimethyldimethoxysilane as an example, the reaction is as follows:

[0019]

[0020] For another example, the hydrolysis of alkyltrialkoxysilane (such as methyltriethoxysilane, phenyltrimethoxysilane) produces a silanetriol, and the subsequent polycondensation can produce three-dimensional cross-linked polymers in various forms. Taking methyltrimethoxysilane as an example, the reaction is as follows:

[0021]

[0022] For another example, the hydrolysis of tetraethyl orthosilicate produces a silanetetrol, and the subsequent polycondensation can produce nano-silica aggregates, resulting in a nanostructure, which provides the silicone resin with higher hardness.

[0023] In this way, the polycondensation between the silicon polyols can produce cross-linked polymers in various forms. Generally, the cross-linked polymers of siloxane with alkyl or phenyl substitution are harder and more brittle, and the brittleness can be adjusted by introducing different intermediates for copolymerization modification. However, step S1 of the present application can obtain silicone resins with active groups such as chloroalkyl and silicon hydroxyl groups through the blending, hydrolysis and co-polycondensation of multiple organosilanes with different functional groups.

[0024] The multiple active groups in the multiple organosilanes used in step S1 of the present application are used to adjust the hardness, gloss, toughness, curing rate and thermal stability of the silicone resin. It has been found through experiments that, among these organosilanes, tetraethyl orthosilicate also needs to contain a chloroalkyl group, and the obtained silicone resin is a novel silicone resin with a chloroalkyl group in the side chain. This is mainly because: the introduced chloroalkyl functional group can cross-link with other resins or the surface of the photovoltaic substrate during the curing process, making the coating more stable; and the introduction of nano-silica through tetraethyl orthosilicate can make the silicone resin have higher hardness.

[0025] Preferably, in step S2, the silicone-modified hydroxyl acrylate resin, the polyester resin, the isocyanate curing agent, the alkyl-modified polysiloxane dispersant, the transparent filler, the light-resistant and antioxidant auxiliary agent, the polyether-modified silicone oil defoaming agent and the water-based solvent are mixed in a mass ratio of 30:20:9:0.2:30:0.6:0.2:30;

[0026] The dispersant is an alkyl-modified polysiloxane dispersant, the defoaming agent is a polysiloxane defoaming agent or a polyether-modified silicone oil defoaming agent, and the light-resistant antioxidant aid comprises, by mass ratio, 1:2:1-4 of a hindered phenol antioxidant, a light stabilizer and a triazine type liquid ultraviolet light absorber.

[0027] The hindered phenol antioxidant is one or more of tetra[β-(3.5-di-tert-butyl, 4-hydroxyphenyl) propionic acid] pentaerythritol, β-(3.5-di-tert-butyl, 4-hydroxyphenyl) propionic acid octadecanol ester, β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid iso-octanol ester, triethylene glycol bis[β-(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate], or triethylene glycol bis β-(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate.

[0028] The light stabilizer is one or more of bis(2,2,6,6-tetramethylpiperidyl) sebacate, polybutanedioic acid (4-hydroxy-2266-tetramethyl-1-piperidinethanol) ester, or 2,4-di-tert-butyl-6-(5-chlorobenzotriazole-2-yl) phenol.

[0029] The aqueous solvent is a mixed solution of isopropyl alcohol, ethylene glycol butyl ether and isopropyl acetate.

[0030] Further preferably, in the step S2, the transparent filler comprises, by mass ratio, 15:5:1 of fumed silica, aluminum oxide and zinc oxide.

[0031] The particle size of the fumed silica is 2-200 nm, the particle size of the aluminum oxide is 50-100 nm, and the particle size of the zinc oxide is 20-100 nm.

[0032] Preferably, in the step S2, the grinding is performed by using a ball mill, and the grinding time is 2-4 hours.

[0033] Preferably, in the step S3, 100 parts of the organic silicon resin and 20-60 parts of the organic silicon-modified hydroxyl acrylic resin coating are mixed.

[0034] The application further discloses an application of the transparent organic silicon coating, and the transparent organic silicon coating is applied to prepare a coated transparent photovoltaic backboard.

[0035] The application method is: the transparent organic silicon coating is coated on the front surface and the back surface of a photovoltaic substrate, and is cured in a 100-190℃ baking tunnel for 2-10 minutes, so as to obtain a coated transparent photovoltaic backboard.

[0036] Preferably, the photovoltaic substrate is a polypropylene terephthalate film, a polycarbonate film, a polyethylene naphthalate film, a polybutylene terephthalate film, a polyethylene terephthalate film or a polymethyl methacrylate film.

[0037] The thickness of the photovoltaic substrate is 100-320 μm; the thickness of the transparent silicone coating formed by curing is 8-25 μm.

[0038] Preferably, the coating is performed by using a roll coating method, and the transparent silicone coating is coated on the front and back surfaces of the photovoltaic substrate by using a roll-to-roll processing technology.

[0039] The silicone resin prepared in step S1 has the following characteristics:

[0040] 1. Low molecular weight, the silicone resin is mostly in the form of a dimer oligomer, and the molecular weight is 1000-3000. The low molecular weight of the silicone resin makes it have higher reactivity, and the curing temperature is low, which is suitable for producing a coated photovoltaic back sheet.

[0041] 2. High reactivity, the silicone resin has many active groups (such as chloroalkyl and silicon hydroxyl), and the silicone resin has a large number of silicon hydroxyl groups (which can make the silicone resin self-crosslinking, and other active groups, such as chloroalkyl, can also rapidly crosslink with other resins, increasing the reactivity), and without the aid of a catalyst or a curing agent, the silicone resin can rapidly crosslink and polymerize at a certain temperature, the formed silicone coating rapidly reaches the surface dryness, the process cycle is shortened, and the production efficiency is improved.

[0042] 3. New performance, the synthesized silicone resin has chloroalkyl groups, and the chloroalkyl groups can crosslink with other resins or the surface of the photovoltaic substrate, increasing the reactivity, forming a crosslinked structure, making the coating more stable, and the combination of the coating and the surface of the photovoltaic substrate is more compact.

[0043] 4. The silicone resin introduces nanosilica through tetraethyl orthosilicate, which can make the silicone resin have better hardness and gloss.

[0044] 5. The silicone resin has soft segments (such as KH560, a kind of silane coupling agent) and hard segments (such as tetraethyl orthosilicate) at the same time, making the coating soft and hard, and promoting the improvement of the adhesion of the coating on the photovoltaic substrate.

[0045] Therefore, in the present application, the organic silicon resin of step S1 is further matched with the specific weight fraction ratio of the tough organic silicon resin coating (i.e. the organic silicon modified hydroxyl acrylic resin coating) of step S2, which can greatly improve the adhesion and adhesion force (especially the adhesion force after PCT aging and the boiling water resistance adhesion force) of the obtained transparent organic silicon coating on the photovoltaic substrate (such as PET film), and the transparent organic silicon coating applied on the photovoltaic substrate can quickly achieve the surface drying of the coating, and also has excellent hardness, wear resistance, self-cleaning property and DH 1000h transparency, and is especially suitable for preparing high-quality coated transparent photovoltaic backsheet.

[0046] Compared with the prior art, the present application at least includes the following beneficial effects:

[0047] The transparent organic silicon coating of the present application is prepared by matching the specific weight fraction ratio of the organic silicon resin and the organic silicon modified hydroxyl acrylic resin coating, and controlling the weight fraction ratio of each organosilane in the organic silicon resin, adding an appropriate amount of chloropropyl triethoxysilane on the basis of tetraethyl orthosilicate, and controlling the mass ratio of the three transparent fillers of fumed silica, aluminum oxide and zinc oxide in the organic silicon modified hydroxyl acrylic resin coating; in this way, the adhesion and adhesion force (especially the adhesion force after PCT aging and the boiling water resistance adhesion force) of the obtained transparent organic silicon coating on the photovoltaic substrate (such as PET film) can be greatly improved, and the transparent organic silicon coating is fluorine-free, environmentally friendly and non-toxic, the transparent organic silicon coating applied on the photovoltaic substrate can quickly achieve the surface drying of the coating, and also has excellent hardness, wear resistance, dirt resistance, weather resistance and DH 1000h transparency, and is especially suitable for preparing high-quality coated transparent photovoltaic backsheet. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 A cross-sectional structure diagram of the transparent photovoltaic backsheet prepared by using the transparent organic silicon coating of the present application.

[0049] Explanation of reference numerals: transparent organic silicon coating layer 1; photovoltaic substrate 2. DETAILED DESCRIPTION

[0050] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0051] Example 1

[0052] The preparation method of the transparent organic silicon coating of the present embodiment includes the following preparation steps:

[0053] S1, preparation of organic silicon resin:

[0054] S11, 10 parts of tetraethyl orthosilicate, 30 parts of methyl triethoxysilane, 10 parts of phenyl trimethoxysilane, 5 parts of dimethyl diethoxysilane, 5 parts of chloropropyl triethoxysilane and 10 parts of KH560 were mixed in sequence according to the weight fraction, and stirred uniformly to obtain a silicone solution; 18 parts of water, 2 parts of acetic acid and 10 parts of isopropyl alcohol were mixed according to the weight fraction, and stirred uniformly to obtain a mixed acid solution.

[0055] S12, the mixed acid solution was slowly added to the silicone solution while stirring, the dropping time was 30 minutes, and then the stirring was continued for 6 hours, so that the hydrolysis and polycondensation of each organosilane in the silicone solution were carried out in sequence, and a silicone resin was obtained.

[0056] S2, preparation of the silicone-modified hydroxyl acrylic resin coating:

[0057] The silicone-modified hydroxyl acrylic resin, the polyester resin, the isocyanate curing agent, the alkyl-modified polysiloxane dispersant, the transparent filler, the light-resistant and antioxidant aid, the polyether-modified silicone oil defoaming agent and the water-based solvent were mixed according to the mass ratio of 30:20:9:0.2:30:0.6:0.2:30, and then a ball mill was used for grinding for 2 hours, and a gauze was used for filtering to obtain the silicone-modified hydroxyl acrylic resin coating.

[0058] The transparent filler includes fumed silica, aluminum oxide and zinc oxide, and the mass ratio of the fumed silica, the aluminum oxide and the zinc oxide is 15:5:1. The particle size of the fumed silica is 2-200 nm (such as 50-120 nm), the particle size of the aluminum oxide is 50-100 nm, and the particle size of the zinc oxide is 20-100 nm (such as 30-80 nm).

[0059] The water-based solvent is a mixed solution of isopropyl alcohol, ethylene glycol butyl ether and isopropyl acetate.

[0060] The light-resistant and antioxidant aid includes tetra[β-(3.5-di-tert-butyl, 4-hydroxyphenyl) propionic acid] pentaerythritol alcohol, bis(2,2,6,6-tetramethylpiperidyl) sebacate and a triazine type liquid ultraviolet light absorber, and the mass ratio of the three is 1:2:4.

[0061] S3, preparation of the transparent silicone coating:

[0062] The silicone resin of step S1 and the silicone-modified hydroxyl acrylic resin coating of step S2 were mixed according to the weight fraction of 100:100, and stirred uniformly to obtain the transparent silicone coating of the embodiment.

[0063] The application of the transparent silicone coating prepared in the embodiment is that the transparent silicone coating is applied to prepare a coated transparent photovoltaic backsheet (the structure is shown in Figure 1 The specific application method is as follows:

[0064] The transparent silicone coating is coated on the front and back of the photovoltaic substrate 2, and the transparent silicone coating is coated on both sides of the photovoltaic substrate 2 by a roll-to-roll processing process in a roller coating mode; and then cured in a segmented oven at 100°C, 140°C, 160°C and 190°C, with a baking time of 2 minutes and a line speed of 60 meters per minute, to form a transparent silicone coating 1 with a thickness of 8-25 μm (such as 15 μm) on the front and back of the photovoltaic substrate 2; thus obtaining a transparent photovoltaic backsheet, so that the transparent photovoltaic backsheet can play a role in bonding and protecting the photovoltaic module.

[0065] The photovoltaic substrate 2 is a polyethylene terephthalate film with a thickness of 100-320 μm (such as 230 μm).

[0066] Example 2

[0067] The preparation method of a transparent silicone coating in this embodiment is as follows, and the preparation steps are as follows:

[0068] In step S3, 100 parts of the silicone resin of step S1 and 60 parts of the silicone-modified hydroxyl acrylic resin coating of step S2 are mixed and stirred uniformly to obtain the transparent silicone coating of this embodiment.

[0069] The application of a transparent silicone coating prepared in this embodiment is as follows, and the specific application method is as in Example 1, thus obtaining the transparent photovoltaic backsheet of this embodiment.

[0070] Example 3

[0071] The preparation method of a transparent silicone coating in this embodiment is as follows, and the preparation steps are as follows:

[0072] In step S3, 100 parts of the silicone resin of step S1 and 20 parts of the silicone-modified hydroxyl acrylic resin coating of step S2 are mixed and stirred uniformly to obtain the transparent silicone coating of this embodiment.

[0073] The application of a transparent silicone coating prepared in this embodiment is as follows, and the specific application method is as in Example 1, thus obtaining the transparent photovoltaic backsheet of this embodiment.

[0074] Example 4

[0075] The preparation method of a transparent silicone coating in this embodiment is as follows, and the preparation steps are as follows:

[0076] In step S11, 20 parts of tetraethyl orthosilicate, 30 parts of methyl triethoxysilane, 10 parts of phenyl trimethoxysilane, 5 parts of dimethyl diethoxysilane, 5 parts of chloropropyl triethoxysilane, and 10 parts of KH560 were mixed in sequence, and stirred uniformly to obtain a silicone solution.

[0077] The application of the transparent silicone coating prepared in this example was as follows. The specific application method referred to Example 1, and the transparent photovoltaic backsheet of this example was obtained.

[0078] Comparative Example 1

[0079] The preparation method of the transparent silicone coating of this comparative example was as follows. The preparation steps referred to Example 1, and the difference between this comparative example and Example 1 was as follows:

[0080] Step S2 of preparing the silicone-modified hydroxyl acrylic resin coating was omitted. In step S3, 100 parts of the silicone resin and 0 parts of the silicone-modified hydroxyl acrylic resin coating were mixed (i.e. no silicone-modified hydroxyl acrylic resin coating was added, and only the silicone resin was added), and stirred uniformly to obtain the transparent silicone coating of this comparative example.

[0081] The application of the transparent silicone coating prepared in this comparative example was as follows. The specific application method referred to Example 1, and the transparent photovoltaic backsheet of this comparative example was obtained.

[0082] Comparative Example 2

[0083] The preparation method of the transparent silicone coating of this comparative example was as follows. The preparation steps referred to Example 1, and the difference between this comparative example and Example 1 was as follows:

[0084] Step S1 of preparing the silicone resin was omitted. In step S3, 0 parts of the silicone resin and 100 parts of the silicone-modified hydroxyl acrylic resin coating were mixed (i.e. no silicone resin was added, and only the silicone-modified hydroxyl acrylic resin coating was added), and stirred uniformly to obtain the transparent silicone coating of this comparative example.

[0085] The application of the transparent silicone coating prepared in this comparative example was as follows. The specific application method referred to Example 1, and the transparent photovoltaic backsheet of this comparative example was obtained.

[0086] Comparative Example 3

[0087] The preparation method of the transparent silicone coating of this comparative example was as follows. The preparation steps referred to Example 1, and the difference between this comparative example and Example 1 was as follows:

[0088] In step S11, 5 parts of chloropropyl triethoxysilane was replaced by 5 parts of propyl triethoxysilane.

[0089] The application of the transparent silicone coating prepared in the present comparative example is as follows. The specific application method is referred to Example 1, and the transparent photovoltaic backsheet of the present comparative example is obtained.

[0090] Comparative Example 4

[0091] The preparation method of the transparent silicone coating of the present comparative example is as follows. The preparation steps are referred to Example 1, and the difference between the present comparative example and Example 1 is as follows:

[0092] In step S2, the mass ratio of fumed silica, alumina and zinc oxide in the transparent filler is changed to 1:5:15 (i.e., the total mass of the transparent filler is unchanged, and the mass of fumed silica is reduced and the mass of zinc oxide is increased).

[0093] The application of the transparent silicone coating prepared in the present comparative example is as follows. The specific application method is referred to Example 1, and the transparent photovoltaic backsheet of the present comparative example is obtained.

[0094] Comparative Example 5

[0095] The preparation method of the transparent silicone coating of the present comparative example is as follows. The preparation steps are referred to Example 1, and the difference between the present comparative example and Example 1 is as follows:

[0096] In step S2, the mass ratio of fumed silica, alumina and zinc oxide in the transparent filler is changed to 5:15:1 (i.e., the total mass of the transparent filler is unchanged, and the mass of fumed silica is reduced and the mass of alumina is increased).

[0097] The application of the transparent silicone coating prepared in the present comparative example is as follows. The specific application method is referred to Example 1, and the transparent photovoltaic backsheet of the present comparative example is obtained.

[0098] Performance Test

[0099] The transparent photovoltaic backsheet of Examples 1-4 and Comparative Examples 1-5 and the transparent photovoltaic backsheet made of the existing fluorocarbon coating are tested for performance, and the test results are shown in Table 1 below:

[0100] Table 1

[0101]

[0102]

[0103] From Table 1, it can be seen that:

[0104] Compared with the transparent photovoltaic backsheet made of the existing fluorocarbon coating, the adhesion, hardness and wear resistance of the transparent photovoltaic backsheet of Examples 1-4 after PCT aging are obviously improved, and it also has self-cleaning performance.

[0105] Compared with Example 1, the transparent silicone coating of Example 2 and Example 3, on the basis of 100 parts of silicone resin, appropriately reduces the weight parts of the added silicone-modified hydroxyl acrylic resin coating, and can further improve the hardness of the transparent silicone coating in the transparent photovoltaic backsheet of Example 2 and Example 3.

[0106] Compared with Example 1, appropriately changing the weight parts ratio of each organosilane in the silicone resin of Example 4 (such as increasing the weight parts of tetraethyl orthosilicate to 20 parts), the coating hardness of the obtained transparent silicone coating can be further improved.

[0107] Compared with Example 1, the transparent silicone coating of Comparative Example 1 (which does not add silicone-modified hydroxyl acrylic resin coating, only adds silicone resin) although the hardness is improved, but its initial adhesion, PCT aging adhesion and boiling water resistance adhesion are all decreased; the transparent silicone coating of Comparative Example 2 (which does not add silicone resin, only adds silicone-modified hydroxyl acrylic resin coating) not only has decreased hardness and wear resistance, but also has decreased PCT aging adhesion and boiling water resistance adhesion. It can be seen that the transparent silicone coating of the present application can have high hardness, excellent wear resistance, initial adhesion, PCT aging adhesion, boiling water resistance adhesion, self-cleaning and DH 1000h transparency by the synergistic cooperation of the specific silicone resin and the silicone-modified hydroxyl acrylic resin coating.

[0108] Compared with Example 1, after the silicone resin of Comparative Example 3 is replaced by propyl triethoxysilane instead of chloropropyl triethoxysilane, the PCT aging adhesion and wear resistance of the obtained transparent silicone coating are decreased.

[0109] Compared with Example 1, the PCT aging adhesion and wear resistance of the transparent silicone coating of Comparative Example 4 (in which the silicone-modified hydroxyl acrylic resin coating has too much zinc oxide in the transparent filler and too little fumed silica) are decreased; the PCT aging adhesion, boiling water resistance adhesion, hardness, wear resistance and DH 1000h transparency of the transparent silicone coating of Comparative Example 5 (in which the silicone-modified hydroxyl acrylic resin coating has too much aluminum oxide in the transparent filler and too little fumed silica) are all obviously decreased. It can be seen that the silicone-modified hydroxyl acrylic resin coating of the present application, by the cooperation of the specific mass ratio of the three transparent fillers of fumed silica, aluminum oxide and zinc oxide, can help to improve the PCT aging adhesion, boiling water resistance adhesion, hardness and wear resistance of the transparent silicone coating, and can effectively avoid the wet heat whitening phenomenon.

[0110] In conclusion, the transparent silicone coating of the present application, by the cooperation of the silicone resin and the silicone modified hydroxyl acrylic resin coating in specific weight ratio, and controlling the weight ratio of each organosilane in the silicone resin, adding appropriate amount of chloropropyl triethoxysilane, and controlling the mass ratio of the three transparent fillers of fumed silica, alumina and zinc oxide in the silicone modified hydroxyl acrylic resin coating; in this way, after the transparent silicone coating is coated on the photovoltaic substrate, it has excellent initial adhesion, adhesion after PCT aging, water boiling resistance, hardness, wear resistance, self-cleaning property and DH 1000h transparency, and is especially suitable for preparing coated transparent photovoltaic backsheet.

[0111] Although preferred embodiments of the embodiments of the present application have been described, those skilled in the art, once they know the basic creative concept, can make additional changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the embodiments of the present application.

[0112] The above describes the technical solutions provided by the present application in detail, and the principles and implementation modes of the present application are described by applying specific examples; the above description of the embodiments is only for helping to understand the method of the present application and its core idea; meanwhile, for those skilled in the art, according to the idea of the present application, the specific implementation modes and application ranges will have changes; in conclusion, the content of the present description should not be understood as limiting the present application.

Claims

1. A method for producing a transparent silicone coating, characterized by, The preparation steps include: S1, preparation of silicone resin: S11, tetraethyl orthosilicate, methyl triethoxysilane, phenyl trimethoxysilane, dimethyl diethoxysilane, chloropropyl triethoxysilane, KH560 are mixed in a weight ratio of 10-20:30-40:10:5:5:10, stirred uniformly to obtain a silicone solution; water, acetic acid and isopropyl alcohol are mixed in a weight ratio of 18:2:1-10, stirred uniformly to obtain a mixed acid solution; S12, slowly add the mixed acid solution to the silicone solution while stirring, continue to stir to make the silicone solution hydrolyze and condense, and obtain the silicone resin; S2, mix the silicone modified hydroxyl acrylic resin, polyester resin, isocyanate curing agent, dispersant, transparent filler, light-resistant antioxidant additive, defoaming agent, water-based solvent in a mass ratio of 20-30:5-20:9:0.2:30-40:0.6:0.2:20-30, grind, filter, and obtain the silicone modified hydroxyl acrylic resin coating; The transparent filler includes fumed silica, alumina and zinc oxide mixed in a mass ratio of 10-15:3-5:0.1-1. S3, mix 100 parts of the silicone resin and 20-100 parts of the silicone modified hydroxyl acrylic resin coating, and stir uniformly to obtain the transparent silicone coating.

2. The method for preparing a transparent organosilicon coating according to claim 1, characterized in that, In step S11, the tetraethyl orthosilicate, methyl triethoxysilane, phenyl trimethoxysilane, dimethyl diethoxysilane, chloropropyl triethoxysilane and KH560 are mixed in a weight ratio of 10-20:30:10:5:5:

10.

3. The method for preparing a transparent organosilicon coating according to claim 2, characterized in that, In step S11, the tetraethyl orthosilicate, methyl triethoxysilane, phenyl trimethoxysilane, dimethyl diethoxysilane, chloropropyl triethoxysilane and KH560 are mixed in a weight ratio of 20:30:10:5:5:

10. The water, acetic acid and isopropyl alcohol are mixed in a weight ratio of 18:2:

10.

4. The method for preparing a transparent organosilicon coating according to claim 1, characterized in that, In step S12, the dropping time is 30-60 minutes, and the stirring time is 3-6 hours.

5. The method for preparing a transparent organosilicon coating according to claim 1, characterized in that, In step S2, the silicone modified hydroxyl acrylic resin, polyester resin, isocyanate curing agent, alkyl modified polysiloxane dispersant, transparent filler, light-resistant antioxidant additive, polyether modified silicone oil defoaming agent and water-based solvent are mixed in a mass ratio of 30:20:9:0.2:30:0.6:0.2:

30. The dispersant is an alkyl modified polysiloxane dispersant, the defoaming agent is a polysiloxane defoaming agent or a polyether modified silicone oil defoaming agent, and the light-resistant antioxidant additive includes a hindered phenol type antioxidant, a light stabilizer and a triazine type liquid ultraviolet light absorber.

6. A method for preparing a transparent organosilicon coating according to claim 1 or 5, characterized in that, In step S2, the transparent filler includes fumed silica, alumina and zinc oxide mixed in a mass ratio of 15:5:

1.

7. The method for preparing a transparent organosilicon coating according to claim 1, characterized in that, In step S2, the grinding is performed by a ball mill, and the grinding time is 2-4 hours.

8. The method for preparing a transparent organosilicon coating according to claim 1, characterized in that, In step S3, 100 parts of the silicone resin and 20-60 parts of the silicone modified hydroxyl acrylic resin coating are mixed.

9. Use of a transparent silicone coating, characterized in that The transparent organic silicon coating is applied to prepare a coated transparent photovoltaic back sheet, and the transparent organic silicon coating is prepared by the method of any one of claims 1-8. The application method is: the transparent organic silicon coating is coated on the front and back of the photovoltaic substrate, and is cured in a 100-190 DEG C baking tunnel for 2-10 minutes to obtain a coated transparent photovoltaic back sheet.

10. Use of a transparent silicone coating according to claim 9, characterized in that, The photovoltaic substrate is a polytrimethylene terephthalate film, a polycarbonate film, a polyethylene naphthalate film, a polybutylene terephthalate film, a polyethylene terephthalate film or a polymethyl methacrylate film. The thickness of the photovoltaic substrate is 100-320 mu m; and the thickness of the transparent organic silicon coating formed after curing is 8-25 mu m.

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