PO membrane coating liquid and preparation process thereof

Abstract

The present application relates to the field of coating technology, and in particular to a coating liquid for PO membranes and a preparation process thereof. The PO membrane coating liquid comprises, by mass, 10-30 parts of nano-aluminum sol, 8-20 parts of surfactant, 6-12 parts of polyvinyl alcohol resin, 10-15 parts of borate ester active agent, and 25-75 parts of water; the borate ester active agent is prepared by esterification of boric acid with a polyol, followed by reaction with a dibasic acid anhydride and a polyetheramine; the borate ester active agent is used in combination with the nano-aluminum sol, surfactant, and polyvinyl alcohol resin, so that the PO membrane coating liquid not only has good hydrophilicity, antistatic properties, and anti-fog effect, but also has excellent adhesion performance and dispersibility, thereby improving the adhesion and cohesion of the film layer, thereby improving the drip durability and light transmittance of the prepared PO membrane and reducing the haze.

Description

Technical Field

[0001] The present application relates to the field of coating technology, and in particular to a coating liquid for PO membranes and a preparation process thereof. Background Art

[0002] Greenhouse film can reduce field humidity, mitigate pest and disease incidence, and improve crop yield and quality. However, it has poor fog and drip resistance. Especially in winter, water produced by crop respiration accumulates on the film, forming droplets. This causes incident light to reflect or refract, reducing the film's light transmittance and affecting crop photosynthesis. Furthermore, the droplets fall onto crop leaves, forming a film that creates conditions for pathogens to infect and thrive, leading to vegetable diseases.

[0003] To improve the mist-dissipating and drip-removing properties of greenhouse films, drip-removing functional films were developed to allow the water from the mist on the film to drip down the greenhouse walls. These films are generally categorized as internally added and externally coated. Internally added greenhouse films exhibit poor drip retention, while coated films are more widely used. Coated greenhouse films are typically PO films, which are produced using high-grade olefin raw materials and other additives through an external spraying and drying process. The PO film coating solution is primarily formulated with aluminum sol and silica sol, with a surfactant added for surface modification to improve the film's dripping properties.

[0004] However, the existing PO membrane has a good effect in eliminating mist and dripping in the initial stage of use. However, after a period of time, the PO membrane will have serious water droplets, and sometimes the membrane will turn white and the coating will fall off, seriously affecting farmers' subsequent production and use. The main reason for the above problems is that the film layer formed by the PO membrane coating liquid has poor adhesion and low cohesion, resulting in a poor long-term dripping effect of the PO membrane. Summary of the Invention

[0005] The present application solves the problem that the film layer formed by the existing PO membrane coating liquid has poor adhesion and low cohesion, resulting in poor long-term dripping of the PO membrane. The present application provides a coating liquid for PO membrane and a preparation process thereof.

[0006] In one aspect, the present application provides a coating liquid for a PO membrane.

[0007] A coating liquid for PO membrane, comprising, by weight, 10-30 parts of nano-aluminum sol, 8-20 parts of surfactant, 6-12 parts of polyvinyl alcohol resin, 10-15 parts of borate ester active agent and 25-75 parts of water;

[0008] The borate ester active agent is prepared by esterifying boric acid with polyol and then reacting with dibasic acid anhydride and polyetheramine.

[0009] By adopting the above technical solution, the borate ester active agent is connected to the molecule with the boron atom as the central atom with hydroxyl, carboxyl and etheramine hydrophilic functional groups. The carboxyl groups in the borate ester active agent have a strong interaction with the positively charged nano-aluminum sol and the polyvinyl alcohol resin, thereby improving the cohesive force of the film layer formed by the PO membrane coating liquid and the interaction with other raw materials, thereby reducing the loss rate of the surfactant during use; the hydroxyl, etheramine and carboxyl groups in the borate ester active agent improve the interaction between the film layer formed by the PO membrane coating liquid and the PO base membrane, thereby improving the dispersibility of the PO membrane coating liquid and the uniformity of the film layer formed.

[0010] The borate ester surfactant is used in combination with nano-aluminum sol, surfactant and polyvinyl alcohol resin, so that the coating liquid for PO membrane not only has good hydrophilicity, antistatic and anti-drip effect, but also has excellent adhesion performance and dispersibility, which improves the adhesion and cohesion of the formed film layer, thereby improving the drip durability and light transmittance of the PO membrane and reducing the haze.

[0011] Preferably, the preparation process of the borate ester active agent is as follows:

[0012] The polyol and boric acid are mixed in proportion, stirred and reacted at 100-300°C for 3-8 hours to obtain a boric acid ester; then, dianhydride is added, stirred and reacted at 100-300°C for 3-8 hours to prepare a modified boric acid ester;

[0013] Adding water to the modified borate at a solid content of 10-15%, stirring and emulsifying at high speed at 30-100°C for 20-60 minutes to prepare an emulsion; adding water to the polyetheramine at a solid content of 10-20%, mixing to prepare a mixed solution; adding the emulsion to the mixed solution, stirring and reacting at a temperature of 50-300°C for 1-3 hours, then standing, filtering, and drying to prepare a borate ester active agent;

[0014] The molar ratio of the polyol to the boric acid is (1.0-1.2):1, and the molar ratio of the boric ester, the dianhydride and the polyetheramine is (1.0-1.5):1:1.

[0015] By adopting the above technical solution, a borate ester active agent is prepared, and hydroxyl, carboxyl and etheramine hydrophilic functional groups are connected to the molecule with a boron atom as the central atom, thereby improving the cohesive force of the PO membrane coating liquid in forming the film layer and the interaction force between the PO membrane coating liquid and other raw materials, improving the dispersibility, hydrophilicity and uniformity of the PO membrane coating liquid in forming the film layer, thereby improving the drip durability and light transmittance of the PO membrane and reducing the haze.

[0016] Preferably, the polyol is one of trimethylolethane, xylitol, pentaerythritol and sorbitol; and the dianhydride is one of maleic anhydride, succinic anhydride, pyromellitic anhydride and glutaric anhydride.

[0017] By adopting the above technical solution, preferably a polyol containing more hydroxyl groups and / or ether bonds is used to improve the dispersibility, polarity and adhesion properties of the borate ester active agent.

[0018] Preferably, the average molecular weight of the polyetheramine is ≥900.

[0019] By adopting the above technical solution, polyetheramine with an average molecular weight ≥900 is preferred to overcome the steric hindrance of polar groups such as hydroxyl or carboxyl groups in other raw materials in the PO membrane coating liquid when combined with the amino groups in the borate ester active agent; the longer molecular chain of polyetheramine is beneficial to improving the dispersibility of the borate ester active agent, thereby improving the drip durability and light transmittance of the PO membrane and reducing the haze.

[0020] Preferably, the particle size of the nano-aluminum sol is 10-30 nm.

[0021] By adopting the above technical solution, nano-aluminum sol with smaller particle size is preferred, which improves the light transmittance of the PO film and reduces the haze.

[0022] Preferably, the surfactant is at least one of silicone polyoxyethylene ether, sorbitan lauryl ester, emulsifier OP-10, fatty alcohol polyoxyethylene ether, polyvinyl pyrrolidone, hydroxypropyl methylcellulose, isomeric fatty alcohol polyoxyethylene ether, dodecyl dihydroxyethyl betaine, sodium dodecylaminopropionate, and dodecyl betaine.

[0023] By adopting the above technical solution, surfactants are used to improve the drip durability and light transmittance of the PO film and reduce the haze.

[0024] Preferably, the surfactant is a composition of sorbitan dodecanoate, emulsifier OP-10 and dodecyl dihydroxyethyl betaine in a mass ratio of 2:1:(2-3).

[0025] By adopting the above technical solution, the preferred surfactant has a good compatibility effect with the borate ester surfactant, polyvinyl alcohol resin and nano-aluminum sol, so that the PO film coating liquid has good dispersibility, and thus the formed film layer has a higher transmittance and lower haze; the interaction between the raw material components of the PO film coating liquid and the adhesion to the PO base film are improved, so that the formed film layer has a higher cohesive force, thereby improving the long-term dripping period of the PO film.

[0026] Preferably, the PO membrane coating solution further comprises 1-2 parts by mass of sodium alginate and 0.8-1.5 parts by mass of a silane coupling agent.

[0027] By adopting the above technical solution, sodium alginate and silane coupling agent are used in combination in the coating liquid for PO membrane, which improves the dripping long-term effect and light transmittance of the film layer formed by the coating liquid for PO membrane, and reduces the haze; further improves the dripping long-term effect and light transmittance of the film layer formed by the coating liquid for PO membrane and reduces the haze.

[0028] On the other hand, the present application provides a process for preparing a coating liquid for a PO membrane.

[0029] A process for preparing a coating liquid for a PO membrane comprises the following steps:

[0030] The surfactant is stirred and mixed with nano-aluminum sol at a temperature of 30-40° C. to prepare a first mixture;

[0031] The polyvinyl alcohol resin, the borate ester active agent and water at a temperature of 30-40° C. are stirred and mixed to prepare a second mixed liquid; the first mixture is added to the second mixed liquid and stirred and mixed to prepare a PO film coating liquid.

[0032] By adopting the above technical solution, a PO film coating liquid with a long dripping period, high light transmittance and low haze is prepared.

[0033] Preferably, after the sodium alginate and the silane coupling agent are added to the second mixed liquid, the first mixture is then added to the second mixed liquid to which the sodium alginate and the silane coupling agent are added.

[0034] By adopting the above technical solution, the addition order of sodium alginate and silane coupling agent is optimized, so that the coating liquid for PO membrane has a smaller particle size, better uniformity and stability, and the strength of the formed film layer is improved, thereby improving the dripping longevity and transmittance of the PO membrane formed by the coating liquid for PO membrane, and reducing haze.

[0035] In summary, this application has the following beneficial effects:

[0036] 1. A coating liquid for a PO membrane comprises, by weight, 10-30 parts of nano-aluminum sol, 8-20 parts of a surfactant, 6-12 parts of a polyvinyl alcohol resin, 10-15 parts of a borate ester active agent, and 25-75 parts of water; the borate ester active agent is prepared by an esterification reaction between boric acid and a polyol, followed by reaction with a dibasic acid anhydride and a polyetheramine; the borate ester active agent is used in combination with the nano-aluminum sol, the surfactant, and the polyvinyl alcohol resin, so that the coating liquid for the PO membrane not only has good hydrophilicity, antistatic properties, and anti-fog effects, but also has excellent adhesion and dispersibility, thereby improving the adhesion and cohesion of the formed film layer, thereby improving the drip durability and light transmittance of the prepared PO membrane and reducing the haze.

[0037] 2. The surfactant adopts a composition of sorbitan dodecanoate, emulsifier OP-10 and dodecyl dihydroxyethyl betaine in a mass ratio of 2:1:(2-3). The surfactant has a good compatibility with the borate surfactant, polyvinyl alcohol resin and nano-aluminum sol, so that the PO film coating liquid has good dispersibility, and thus the formed film layer has high light transmittance and low haze; it makes the raw material components of the PO film coating liquid have a higher interaction force, has a higher adhesion to the PO base film, improves the cohesion of the formed film layer, and thus improves the long-term dripping period of the PO film.

[0038] 3. Sodium alginate and silane coupling agent are used in the coating liquid for PO membrane. The silane coupling agent has a poor effect on improving the dispersion of sodium alginate. Sodium alginate, silane coupling agent, surfactant, nano-aluminum sol and borate ester surfactant are used in combination to enhance the cohesion and adhesion of the formed film layer. Furthermore, the addition sequence of sodium alginate and silane coupling agent is optimized, so that the coating liquid for PO membrane has a smaller particle size, better uniformity and stability, further improving the dripping longevity and light transmittance of the PO membrane formed by the coating liquid for PO membrane, and reducing the haze. DETAILED DESCRIPTION

[0039] raw material

[0040] Polyvinyl alcohol resin (polyvinyl alcohol 2488, active ingredient content 99%, melting point: 230-240°C), sodium alginate (food grade, implementation standard: national standard, active ingredient content 99%, white powder particles).

[0041] Preparation Example of Boric Acid Ester

[0042] Preparation Example 1, a borate ester active agent, the preparation process is as follows:

[0043] A polyol (pentaerythritol) and boric acid in a molar ratio of 1.2:1 were added to a stirred tank, and the mixture was stirred and reacted at 300°C for 3 hours to obtain a borate ester. Then, dianhydride (maleic anhydride) was added, and the mixture was stirred and reacted at 300°C for 3 hours to prepare a modified borate ester.

[0044] Water was added to the stirring kettle (added so that the solid content of the modified borate was 15%), and then emulsified at a temperature of 100° C. and a stirring speed of 2000 r / min for 60 minutes to prepare an emulsion.

[0045] A polyetheramine (using polyetheramine ED-2003) was mixed with water to prepare a mixed solution with a solid content of 20%. The mixed solution was added to a reactor and mixed with the emulsion, and then stirred and reacted at 300° C. for 1 hour. The mixture was then allowed to stand, filtered, and dried to prepare a borate ester active agent.

[0046] The molar ratio of borate ester, dianhydride and polyetheramine is 1.5:1:1.

[0047] Preparation Example 2, a borate ester active agent, differs from Preparation Example 1 in that the types of raw materials, weights, and preparation process parameters are different, as follows:

[0048] A polyol (using trimethylolethane) and boric acid in a molar ratio of 1.2:1 were added to a stirred kettle, and the mixture was stirred and reacted at 200°C for 5 hours to obtain a borate ester. Then, dianhydride (using maleic anhydride) was added, and the mixture was stirred and reacted at 200°C for 5 hours to prepare a modified borate ester.

[0049] Water was added to the stirring kettle (based on the solid content of the modified borate being 12%), and emulsification was carried out for 40 minutes at a temperature of 80° C. and a stirring speed of 1800 r / min to prepare an emulsion.

[0050] A polyetheramine (using polyetheramine ED-2003) was mixed with water to prepare a mixed solution with a solid content of 15%. The mixed solution was added to a reactor and mixed with the emulsion, and then stirred and reacted at 200° C. for 2 hours. The mixture was then allowed to stand, filtered, and dried to prepare a borate ester active agent.

[0051] The molar ratio of borate ester, dianhydride and polyetheramine is 1.2:1:1.

[0052] Preparation Example 3, a borate ester active agent, differs from Preparation Example 1 in that the types of raw materials, weights, and preparation process parameters are different, as follows:

[0053] A polyol (using sorbitol) and boric acid in a molar ratio of 1:1 were added to a stirred tank, and the mixture was stirred and reacted at 100°C for 8 hours to obtain a borate ester. Then, a dianhydride (using maleic anhydride) was added, and the mixture was stirred and reacted at 100°C for 8 hours to prepare a modified borate ester.

[0054] Water was added to the stirring kettle (added so that the solid content of the modified borate was 10%), and emulsification was carried out for 20 minutes at a temperature of 30° C. and a stirring speed of 1500 r / min to prepare an emulsion.

[0055] A polyetheramine (using polyetheramine ED-900) was mixed with water to prepare a mixed solution with a solid content of 10%. The mixed solution was added to a reactor and mixed with the emulsion, followed by stirring and reacting at 50° C. for 3 hours. The mixture was then allowed to stand, filtered, and dried to prepare a borate ester active agent.

[0056] The molar ratio of borate ester, dianhydride and polyetheramine is 1:1:1.

[0057] Preparation Example 4, a borate ester active agent, differs from Preparation Example 1 in that the polyetheramine is polyetheramine ED-600; the dianhydride is succinic anhydride; and the pentaerythritol is 1,4-butanediol.

[0058] Preparation Example 5, a borate ester active agent, differs from Preparation Example 1 in that the molar ratio of pentaerythritol to boric acid is 1.5:1; the molar ratio of borate ester, dianhydride and polyetheramine is 1.5:1:0.5.

[0059] Preparation Example 6, a borate ester active agent, differs from Preparation Example 1 in that the molar ratio of pentaerythritol to boric acid is 0.7:1; the molar ratio of borate ester, maleic anhydride and polyetheramine is 1.5:0.5:1.

[0060] Example

[0061] Example 1, a coating liquid for PO membrane, using raw materials as shown in Table 1, and its preparation process is as follows:

[0062] A surfactant and nano-aluminum sol at a temperature of 40° C. (nano-aluminum sol: solid content 20%, particle size 10 nm) were added into a stirring kettle, and stirred and mixed at 500 r / min to prepare a first mixture.

[0063] The polyvinyl alcohol resin and water at a temperature of 40° C. were stirred and mixed at 500 r / min for 40 minutes, and then a borate ester activator was added to prepare a second mixed solution.

[0064] Then, sodium alginate and silane coupling agent were added into the second mixed solution, and stirred and mixed at 500 r / min for 20 minutes.

[0065] The first mixture was added to the second mixed solution after sodium alginate and silane coupling agent were added, and the mixture was stirred at 500 r / min for 60 minutes to prepare a PO film coating solution.

[0066] Example 2, a coating liquid for PO membrane, differs from Example 1 in that the types of raw materials, weights of raw materials and preparation process are different. The types and weights of raw materials are shown in Table 1, and the preparation process is as follows:

[0067] Add a surfactant and nano-aluminum sol (nano-aluminum sol: solid content 23%, particle size 20 nm) at a temperature of 35° C. into a stirring kettle, and stir and mix at 450 r / min to prepare a first mixture.

[0068] The polyvinyl alcohol resin and water at a temperature of 35° C. were stirred and mixed at 450 r / min for 30 minutes, and then a borate ester activator was added to prepare a second mixed solution.

[0069] Then, sodium alginate and silane coupling agent were added into the second mixed solution, and the mixture was stirred and mixed at 500 r / min for 15 minutes.

[0070] The first mixture was added to the second mixed solution after sodium alginate and silane coupling agent were added, and the mixture was stirred and mixed at 450 r / min for 50 minutes to prepare a PO film coating solution.

[0071] Example 3, a coating liquid for PO membrane, differs from Example 1 in that the types of raw materials, weights of raw materials and preparation processes are different. The types of raw materials and weights of raw materials are shown in Table 1. The preparation process is as follows:

[0072] Add a surfactant and nano-aluminum sol at a temperature of 30° C. (nano-aluminum sol: solid content 25%, particle size 30 nm) into a stirring kettle, and stir and mix at 400 r / min to prepare a first mixture.

[0073] The polyvinyl alcohol resin and water at a temperature of 30° C. were stirred and mixed at 400 r / min for 20 minutes, and then a borate ester activator was added to prepare a second mixed solution.

[0074] Then, sodium alginate and silane coupling agent were added into the second mixed solution, and the mixture was stirred and mixed at 500 r / min for 10 minutes.

[0075] The first mixture was added to the second mixed solution after sodium alginate and silane coupling agent were added, and the mixture was stirred and mixed at 400 r / min for 30 minutes to prepare a PO film coating solution.

[0076] Table 1. List of types and weights of raw materials used in Examples 1 to 3

[0077]

[0078]

[0079] Examples 4 to 6 are coating solutions for PO membranes. The difference from Example 1 is that the borate ester active agent is prepared in accordance with Preparation Examples 4 to 6, respectively.

[0080] Example 7, a coating liquid for PO membrane, differs from Example 1 in that the surfactant used is a composition of sorbitan dodecanoate, emulsifier OP-10 and dodecyl dihydroxyethyl betaine in a mass ratio of 2:1:2.

[0081] Example 8, a coating liquid for PO membrane, differs from Example 1 in that the surfactant used is a composition of sorbitan dodecanoate, emulsifier OP-10 and dodecyl dihydroxyethyl betaine in a mass ratio of 2:1:3.

[0082] Example 9 is a coating liquid for PO membranes. The difference from Example 1 is that the surfactant used is a composition of sorbitan dodecanoate and polyvinyl pyrrolidone in a mass ratio of 2:1.

[0083] Example 10 is a coating liquid for PO membranes. The difference from Example 1 is that the surfactant used is a composition of sorbitan dodecanoate, emulsifier OP-10 and dodecyl dihydroxyethyl betaine in a mass ratio of 2:1:5.

[0084] Example 11 is a coating liquid for PO membranes. The difference from Example 1 is that the surfactant used is a composition of emulsifier OP-10, polyvinyl pyrrolidone and sodium laurylaminopropionate in a mass ratio of 2:1:5.

[0085] Example 12, a coating liquid for PO membrane, differs from Example 1 in that silane coupling agent KH-570 (γ-methacryloxypropyl) is used in equal amounts to replace silane coupling agent KH-560; and hydroxymethyl cellulose is used in equal amounts to replace sodium alginate.

[0086] Example 13, a coating liquid for PO membrane, differs from Example 1 in that no silane coupling agent is used.

[0087] Example 14 is a coating liquid for PO membrane, which differs from Example 1 in that sodium alginate is not used.

[0088] Example 15 is a coating liquid for PO membrane, which differs from Example 1 in that sodium alginate and silane coupling agent are not used.

[0089] Example 16, a coating liquid for PO membrane, differs from Example 1 in that sodium alginate and a silane coupling agent are added to a first mixed liquid, and then the first mixture to which sodium alginate and a silane coupling agent are added is added to a second mixed liquid, and the mixture is stirred and mixed at 500 r / min for 60 minutes to prepare a PO membrane coating liquid.

[0090] Comparative Example

[0091] Comparative Example 1 is a coating solution for a PO membrane, which differs from Example 15 in that no borate ester activator is used.

[0092] Comparative Example 2 is a coating solution for PO membranes, which differs from Example 15 in that an equal amount of sodium alginate is used to replace the borate ester active agent.

[0093] Comparative Example 3 is a coating liquid for PO membranes, which differs from Example 15 in that maleic anhydride is not used in the borate ester activator.

[0094] Comparative Example 4 is a coating liquid for PO membranes, which differs from Example 15 in that polyetheramine is not used in the borate ester active agent.

[0095] Comparative Example 5 is a coating solution for PO membranes. The difference from Example 15 is that phosphoric acid is used in an equal amount to replace boric acid in the borate ester active agent.

[0096] Performance testing

[0097] Test 1: Long-term drip performance

[0098] The film is fixed on a constant temperature water bath at 60℃, with the water surface about 5 cm above the film and the ambient temperature at room temperature (23±2)℃. When the droplet area on the film is ≥30.0%, it is considered to be invalid. The time is recorded, which is called the long-term effect period and serves as a reference for the long-term effect data of the droplet.

[0099] Test 2: Light transmittance and haze

[0100] According to GB / T 2410-2008, the transmittance and haze of the test samples were tested using a transmittance and haze tester. Each sample was measured 10 times and the average value was taken.

[0101] The calculation formula of haze: T d =(T4 / T2-T3 / T1)*100

[0102] The formula for calculating light transmittance is: T = T2 / T1*100

[0103] Where: T d -Haze (%); T-transmittance (%); T4-scattered light intensity between the tested sample and the instrument (au); T3-light intensity scattered by the tested instrument (au); T2-light intensity transmitted through the sample (au); T1-incident light intensity (au).

[0104] Test samples: Examples 1-18 and Comparative Examples 1-5 were respectively and evenly coated on a PO base film with a thickness of 0.08 mm that was not coated with the coating liquid to prepare a PO film with a total thickness of 0.12 mm. The PO film prepared by Examples 1-18 was used as the example sample; the PO film prepared by Comparative Examples 1-5 was used as the comparative sample.

[0105] Test results: For the test results of the long-term effect, light transmittance and haze of the PO films of Examples 1-18 and Comparative Examples 1-5, refer to Table 2.

[0106] Table 2. Test results of long-term effect, light transmittance and haze of PO films of Examples 1-18 and Comparative Examples 1-5

[0107] distinguish Long-term effect / d Transmittance / % Haze / % Example 1 23 92.5 16.6 Example 2 23 92.8 16.7 Example 3 21 92.7 16.4 Example 4 18 91.0 17.8 Example 5 17 91.2 18.9 Example 6 17 90.6 19.3 Example 7 26 95.4 12.4 Example 8 27 96.1 11.9 Example 9 23 93.9 14.5 Example 10 24 94.5 13.8 Example 11 24 93.6 15.6 Example 12 19 91.4 17.5 Example 13 17 92.0 17.2 Example 14 17 92.5 16.6 Example 15 15 92.2 16.9 Example 16 16 91.3 17.8 Comparative Example 1 11 85.5 24.7 Comparative Example 2 13 90.3 18.6 Comparative Example 3 13 90.3 18.7 Comparative Example 4 13 89.8 18.5 Comparative Example 5 13 87.3 19.5

[0108] Combining Examples 1-16 and Comparative Examples 1-5 and Table 2, it can be seen that:

[0109] The long-term effect and light transmittance of the PO membrane prepared using the coating liquid for the PO membrane of Examples 1 to 16 are higher than those of Comparative Examples 1 to 5, and the haze of the PO membrane prepared using the coating liquid for the PO membrane of Examples 1 to 16 is lower than that of Comparative Examples 1 to 5, indicating that the borate ester active agent prepared by esterification reaction between boric acid and polyol and then reacting with dibasic acid anhydride and polyetheramine has a good compatibility effect with polyvinyl alcohol resin, nano aluminum sol and surfactant, so that the PO membrane prepared using the coating liquid for the PO membrane has a higher long-term effect of dripping, light transmittance and lower haze.

[0110] The reasons may be that: the borate ester surfactant has hydrophilic functional groups such as hydroxyl, carboxyl and amine attached to the molecule with boron atom as the central atom. The carboxyl groups in the borate ester surfactant have a strong interaction with the positively charged nano-aluminum sol and polyvinyl alcohol resin, which improves the cohesion of the film layer formed by the PO membrane coating liquid and the interaction with other raw materials, thereby reducing the loss rate of the surfactant during use; the hydroxyl, etheramine and carboxyl groups in the borate ester surfactant improve the interaction between the film layer formed by the PO membrane coating liquid and the PO base membrane, thereby improving the dispersibility of the PO membrane coating liquid and the uniformity of the film layer formed; the combination of the borate ester surfactant with the nano-aluminum sol, surfactant and polyvinyl alcohol resin makes the PO membrane coating liquid not only have good hydrophilicity, antistatic and anti-fog effects, but also have excellent adhesion performance and dispersibility, thereby improving the adhesion and cohesion of the film layer, thereby improving the dripping durability and light transmittance of the PO membrane and reducing the haze.

[0111] The long-term effect of the PO membranes of Examples 1 to 3 is higher than that of Example 4, which may be because the molecular chain length of the polyetheramine coordinated on the boron element in the borate ester active agent used in Example 1 is longer and the steric hindrance is smaller than that of Example 4; compared with succinic anhydride, succinic anhydride contains carbon-carbon double bonds and has a larger polarity, indicating that after the modification of the borate ester by using polyetheramine with an average molecular weight ≥900 and succinic anhydride, the borate ester active agent has higher dispersion performance and at the same time improves the interaction between it and raw materials such as surfactants, so that the formed film layer has stronger adhesion and better dispersibility, thereby improving the drip long-term effect and light transmittance of the prepared PO membrane and reducing the haze.

[0112] The long-term effect and light transmittance of the PO films of Examples 1 to 3 are higher than those of Examples 5 to 6, and the haze of the PO films of Examples 1 to 3 is lower than that of Examples 5 to 6, indicating that among the borate ester active agents, the molar ratio of polyol to boric acid is (1.0-1.2):1, and the molar ratio of borate (prepared by reacting polyol with boric acid), dianhydride and polyetheramine is (0.8-1.2):1:1, which have better compatibility effects.

[0113] The reason may be that the content of hydroxyl, carboxyl and amino functional groups in the borate ester active agent affects the adhesion of the borate ester active agent, the interaction with other raw materials and the dispersion performance, which in turn affects the drip longevity, transmittance and haze of the PO membrane prepared using the PO membrane coating liquid.

[0114] Compared with Examples 1 to 3, the relative content of boric acid and the content of polyetheramine in the borate ester active agent used in Example 5 are reduced. This may be due to the relatively reduced content of etheramine groups in the borate ester active agent, which weakens the interaction between the borate ester active agent and sodium alginate, and reduces the dispersion performance of the PO membrane coating liquid. This results in reduced cohesion and poor uniformity of the film layer formed by the PO membrane coating liquid, which in turn leads to reduced dripping life and transmittance of the PO membrane and increased haze.

[0115] Compared with Examples 1 to 3, the contents of pentaerythritol and maleic anhydride in Example 6 are reduced. The reduced content of pentaerythritol leads to a decrease in the dispersion performance of the borate ester active agent and a decrease in the uniformity of the formed film layer; the reduced content of maleic anhydride may lead to a decrease in the carboxyl content and polarity of the prepared borate ester active agent, thereby resulting in a decrease in the dripping long-term and transmittance of the PO film and an increase in haze.

[0116] The long-term effect and light transmittance of the PO membrane using the coating liquid of Example 7 to Example 8 are higher than those of Example 1 to Example 3 and Example 9 to Example 11, and the haze of the PO membrane using the coating liquid of Example 7 to Example 8 is lower than that of Example 1 to Example 3 and Example 9 to Example 11, indicating that the surfactant uses a composition of sorbitan dodecanoate, emulsifier OP-10 and dodecyl dihydroxyethyl betaine in a mass ratio of 2:1:(2-3), and the surfactant has a good compatibility with the borate surfactant, polyvinyl alcohol resin and nano-aluminum sol, so that the PO membrane coating liquid has good dispersibility, thereby making the formed film layer have high light transmittance and low haze; the raw material components of the PO membrane coating liquid have a higher interaction force, have a higher adhesion to the PO base film, improve the formed film layer has a higher cohesive force, and thus improve the long-term effect of dripping of the PO membrane.

[0117] This may be due to the following: sorbitan dodecanoate, emulsifier OP-10, and dodecyl dihydroxyethyl betaine all have a C12 alkane chain at one end of their molecular chains, which imparts excellent dispersion properties and compatibility with the PO base membrane. The hydrophilic polar group at the other end provides the PO membrane coating solution with excellent stability in water and enhances the cohesion and adhesion of the formed membrane layer. The phenyl group in the emulsifier OP-10 molecular chain enhances the hardness and strength of the membrane layer, thereby increasing the dripping life of the PO membrane. The dialkyl dihydroxyethyl betaine molecular chain contains two long hydroxyl-bearing side chains and a carboxyl group. This strong interaction between the dialkyl dihydroxyethyl betaine and the borate surfactant enhances the cohesion of the membrane layer and reduces the loss of the surfactant during use.

[0118] The long-term effect of the PO membrane using the coating liquid for PO membrane of Example 1 to Example 3 is longer than that of Example 12 to Example 16; this indicates that the combination of sodium alginate and silane coupling agent in the coating liquid for PO membrane improves the long-term effect of dripping and the transmittance of the film layer formed by the coating liquid for PO membrane, and reduces the haze; and further improves the long-term effect of dripping, the transmittance and the haze of the film layer formed by the coating liquid for PO membrane.

[0119] The possible reasons are that: the silane coupling agent has a poor effect in improving the dispersion of sodium alginate, thereby enhancing the cohesion and adhesion of the formed film layer; further, the order of adding sodium alginate and silane coupling agent is optimized, so that the PO film coating liquid has a smaller particle size, better uniformity and stability, and improves the strength of the formed film layer, thereby improving the dripping longevity and transmittance of the PO film formed by the PO film coating liquid, and reducing the haze.

[0120] Compared to Example 16, the PO membrane coating solutions used in Examples 1 through 3 exhibited superior drip life, light transmittance, and haze. This may be because, compared to Example 16, sodium alginate and nano-aluminum sol are less likely to combine to form a larger melt in Examples 1 through 3. This improves the compatibility between the sodium alginate and silane coupling agent, the nano-aluminum sol, the borate ester activator, and the polyvinyl alcohol resin, resulting in the PO membrane coating solution having better dispersibility, cohesion, strength, and uniformity. This, in turn, improves the drip life and light transmittance of the formed film layer, while reducing haze.

[0121] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A coating liquid for PO membrane, characterized in that The composition comprises, by weight, 10-30 parts of nano-aluminum sol, 8-20 parts of surfactant, 6-12 parts of polyvinyl alcohol resin, 10-15 parts of borate ester active agent and 25-75 parts of water; The borate ester active agent is prepared by reacting boric acid with a polyol through an esterification reaction, and then reacting with a dibasic acid anhydride and a polyetheramine. The preparation process of the borate ester active agent is as follows: polyol and boric acid are mixed in proportion, stirred and reacted at 100-300°C for 3-8 hours to obtain a borate ester; then dianhydride is added, stirred and reacted at 100-300°C for 3-8 hours to obtain a modified borate ester; water is added to the modified borate ester at a solid content of 10-15%, and stirred and reacted at 30-100°C. emulsifying under high-speed stirring for 20-60 minutes to prepare an emulsion; adding water to the polyetheramine at a solid content of 10-20%, mixing to prepare a mixed solution; adding the emulsion to the mixed solution, stirring and reacting at a temperature of 50-300°C for 1-3 hours, then standing, filtering, and drying to prepare a borate ester active agent; the molar ratio of the polyol to the boric acid is (1.0-1.2):1, and the molar ratio of the borate ester, dianhydride, and polyetheramine is (1.0-1.5):1:1; The average molecular weight of the polyetheramine is ≥900; the particle size of the nano-aluminum sol is 10-30 nm.

2. A PO membrane coating liquid according to claim 1, characterized in that: The polyol is one of trimethylolethane, xylitol, pentaerythritol and sorbitol; the dianhydride is one of maleic anhydride, succinic anhydride, pyromellitic anhydride and glutaric anhydride.

3. A coating liquid for PO membrane according to claim 1, characterized in that: The surfactant is at least one of silicone polyoxyethylene ether, sorbitan lauryl ester, emulsifier OP-10, fatty alcohol polyoxyethylene ether, polyvinyl pyrrolidone, hydroxypropyl methylcellulose, isomeric fatty alcohol polyoxyethylene ether, dodecyl dihydroxyethyl betaine, sodium dodecylaminopropionate, and dodecyl betaine.

4. A coating liquid for PO membrane according to claim 3, characterized in that: The surfactant is a composition of sorbitan dodecanoate, emulsifier OP-10 and dodecyl dihydroxyethyl betaine in a mass ratio of 2:1:(2-3).

5. The coating liquid for PO membrane according to claim 1, characterized in that: The PO membrane coating liquid further comprises 1-2 parts by mass of sodium alginate and 0.8-1.5 parts by mass of a silane coupling agent.

6. A process for preparing a PO membrane coating liquid according to any one of claims 1 to 5, characterized in that: The method comprises the following preparation steps: The surfactant is stirred and mixed with nano-aluminum sol at a temperature of 30-40° C. to prepare a first mixture; The polyvinyl alcohol resin, the borate ester active agent and water at a temperature of 30-40° C. are stirred and mixed to prepare a second mixed solution; The first mixture is added to the second mixed liquid and stirred to prepare a PO film coating liquid.

7. A process for preparing the PO membrane coating liquid according to claim 5, characterized in that: The method comprises the following preparation steps: stirring and mixing a surfactant and a nano-aluminum sol at a temperature of 30-40° C. to prepare a first mixture; stirring and mixing a polyvinyl alcohol resin, a borate ester active agent and water at a temperature of 30-40° C. to prepare a second mixed liquid; then adding the sodium alginate and a silane coupling agent into the second mixed liquid and mixing; and finally adding the first mixture into the second mixed liquid and stirring and mixing to prepare a PO film coating liquid.

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