Preparation method of low-water-absorption voltage-resistant polyurethane acrylate

Abstract

The invention relates to the technical field of polyurethane, and discloses a preparation method of low-water-absorption voltage-resistant polyurethane acrylate, which comprises the following steps: adding 100 parts by weight of waterborne polyurethane acrylate, 1.6-2.5 parts by weight of defoaming agent, 25-30 parts by weight of reactive diluent, 1-8 parts by weight of fluorine-containing alkyl acrylate, 7.8-9.3 parts by weight of photoinitiator and the like into water; the low-water-absorption voltage-resistant polyurethane acrylate is obtained. The fluorine-containing alkyl acrylate contains two alkenyl groups which can be subjected to UV curing cross-linking reaction with the alkenyl groups of polyurethane acrylate, so that the mechanical properties such as tensile strength, elongation at break, hardness and the like can be improved. The fluorine-containing alkyl acrylate contains hydrophobic and low-surface-energy long-chain alkyl and fluorine-containing groups, so that the hydrophilicity of the waterborne polyurethane acrylate can be reduced, the waterborne polyurethane acrylate shows lower water absorption, and meanwhile, the breakdown voltage and the voltage resistance are improved.

Description

Technical Field

[0001] The invention relates to the technical field of polyurethane, in particular to a method for preparing low water absorption voltage-resistant polyurethane acrylate. Background Art

[0002] Waterborne polyurethane is usually prepared by polymerization reaction of polyol, isocyanate monomer, hydrophilic chain extender, etc. By using monomers such as hydroxyethyl acrylate to end-cap the polyurethane prepolymer, waterborne polyurethane acrylate with UV curing performance can be obtained, which has a wide range of practical applications in paints, coatings, inks, adhesives, enameled wires, etc. Improving the dielectric properties and voltage resistance of polyurethane can expand its practical applications in enameling, dielectric potting glue, insulating materials, etc.

[0003] The document "Preparation and Performance Study of High Voltage Resistant Polyurethane Elastomer Materials" reports that the polyurethane elastomer obtained by using polyether diol, isocyanate, dodecafluoroheptanol, etc. as reactants has the advantages of high hydrophobicity, low water absorption, good high voltage resistance, etc. Patent CN114032017B discloses a high breakdown voltage and long life polyurethane enameled wire paint composition based on modified branched fluorinated polyurethane and its preparation method. The fluorinated polyurethane and its enameled wire prepared by using modified branched fluorinated polyurethane, silicone polymer, blocked isocyanate crosslinker, etc. as raw materials have extremely high breakdown voltage, heat resistance and weather resistance, but the above polyurethane elastomer and branched fluorinated polyurethane do not have UV curing characteristics, and do not show high tensile strength and hardness and other mechanical properties. Summary of the invention

[0004] The invention solves the problems of high water absorption, poor voltage resistance and poor mechanical properties of polyurethane acrylate.

[0005] The technical solution of the present invention is a method for preparing low water absorption and voltage-resistant polyurethane acrylate: 100 parts by weight of aqueous polyurethane acrylate, 1.6-2.5 parts by weight of defoamer, 25-30 parts by weight of active diluent, 1-8 parts by weight of fluorine-containing alkyl acrylate, 4-20 parts by weight of cosolvent are added into water, and after stirring, 7.8-9.3 parts by weight of photoinitiator are added to obtain low water absorption and voltage-resistant polyurethane acrylate.

[0006] Preferably, the preparation method of fluorinated alkyl acrylate is:

[0007] (1) Add phenyl ether type fluorinated diamine, glycidyl methacrylate and hydroquinone in a molar ratio of 1:(2-2.2):(0.0016-0.002) to tetrahydrofuran, heat to 45-55°C, react for 2-3 hours, remove tetrahydrofuran by rotary evaporation, and recrystallize the product in chloroform after washing to obtain an acrylate intermediate.

[0008] (2) Adding an acrylic acid ester intermediate, potassium carbonate, and an alkyl chloride in a molar ratio of 1:(3-3.6):(2.2-2.6) to acetonitrile, heating to 40-55°C, reacting for 12-18 hours, removing the acetonitrile by rotary evaporation, washing with water and petroleum ether, and recrystallizing the product in chloroform to obtain a fluorinated alkyl acrylate. The reaction formula is:

[0009]

[0010] Preferably, the molecular formula of the alkyl chloride is Cl-C n H 2n+1 , n is any integer between 14 and 20.

[0011] Preferably, the active diluent is tripropylene glycol diacrylate, 1,6-hexanediol diacrylate or pentaerythritol triacrylate; and the photoinitiator is photoinitiator 1173 or benzoin ethyl ether.

[0012] Preferably, the cosolvent is n-butanol, isopropanol or tetrahydrofuran.

[0013] Technical effect of the present invention: The present invention adds fluorinated alkyl acrylate to waterborne polyurethane acrylate, which contains two alkenyl groups and can replace part of diluents such as tripropylene glycol diacrylate, and undergoes UV curing cross-linking reaction with the alkenyl groups of polyurethane acrylate, thereby increasing the cross-linking degree of the molecular chain of polyurethane acrylate, which is beneficial to improving mechanical properties such as tensile strength and hardness. At the same time, multiple flexible phenyl ether groups are introduced into the polyurethane acrylate molecular chain, which plays a good toughening role and is beneficial to improving the elongation at break of the paint film.

[0014] The fluorinated alkyl acrylate of the present invention contains a long-chain alkyl group and a fluorinated group with hydrophobicity and low surface energy, which can reduce the hydrophilicity of the waterborne polyurethane acrylate and show a lower water absorption rate. In addition, the surface hydrophobicity of the polyurethane acrylate is improved, which can reduce the formation of a hydration layer on the surface of the polyurethane acrylate by water molecules in the air, which is beneficial to improving the dielectric properties and showing a higher breakdown voltage, thereby improving its voltage resistance performance. The practical application of waterborne polyurethane acrylate in dielectric adhesives, enameled wires, etc. is expanded. DETAILED DESCRIPTION

[0015] The waterborne polyurethane acrylate of the present invention has an active ingredient content of 99% and is purchased from Wuhan Maikairui Chemical Co., Ltd.

[0016] The phenyl ether type fluorinated diamine was prepared according to the method of the document "Synthesis and Characterization of Polyimide Membrane Materials Based on Phenyl Ether Type Fluorinated Diamine" in the journal "Journal of Polymer Science" No. 1, January 2010. The structural formula is:

[0017]

[0018] Example 1

[0019] (1) Add 10 mmol of phenyl ether type fluorinated diamine, 20 mmol of glycidyl methacrylate, and 0.016 mmol of hydroquinone to 70 mL of tetrahydrofuran, heat to 55°C, react for 2 hours, remove tetrahydrofuran by rotary evaporation, and recrystallize the product after washing with water in chloroform to obtain an acrylate intermediate. The structural formula is:

[0020] (2) Add 5 mmol of the acrylate intermediate, 16 mmol of potassium carbonate, and 11 mmol of 1-chlorooctadecane to 50 mL of acetonitrile, heat to 45°C, react for 18 hours, remove the acetonitrile by rotary evaporation, wash with water and petroleum ether, and recrystallize the product in chloroform to obtain a fluorinated alkyl acrylate. The reaction formula is:

[0021]

[0022] (3) To 60 mL of water, 100 g of aqueous polyurethane acrylate, 1.6 g of defoamer, 30 g of tripropylene glycol diacrylate, 1 g of fluorinated alkyl acrylate, and 4 g of n-butanol were added, and after stirring, 7.8 g of photoinitiator 1173 was added to obtain a polyurethane acrylate with low water absorption and withstand voltage.

[0023] Example 2

[0024] (1) Add 10 mmol of phenyl ether type fluorinated diamine, 22 mmol of glycidyl methacrylate, and 0.02 mmol of hydroquinone to 80 mL of tetrahydrofuran, heat to 45° C., react for 3 h, remove tetrahydrofuran by rotary evaporation, and recrystallize the product after washing with water in chloroform to obtain an acrylate intermediate.

[0025] (2) Add 5 mmol of the acrylate intermediate, 18 mmol of potassium carbonate, and 13 mmol of 1-chloroeicosane to 40 mL of acetonitrile, heat to 55° C., react for 18 h, remove the acetonitrile by rotary evaporation, wash with water and petroleum ether, and recrystallize the product in chloroform to obtain a fluorinated alkyl acrylate.

[0026] (3) 100 g of aqueous polyurethane acrylate, 2.5 g of defoamer, 27.3 g of 1,6-hexanediol diacrylate, 4 g of fluorinated alkyl acrylate, and 13 g of isopropyl alcohol were added to 70 mL of water, and after stirring, 9.3 g of benzoin ethyl ether was added to obtain low water absorption and voltage-resistant polyurethane acrylate.

[0027] Example 3

[0028] (1) Prepare an acrylate intermediate according to the method of Example 1.

[0029] (2) Add 5 mmol of the acrylate intermediate, 15 mmol of potassium carbonate, and 12 mmol of 1-chlorotetradecane to 40 mL of acetonitrile, heat to 40° C., react for 18 hours, remove the acetonitrile by rotary evaporation, wash with water and petroleum ether, and recrystallize the product in chloroform to obtain a fluorinated alkyl acrylate.

[0030] (3) To 80 mL of water, 100 g of aqueous polyurethane acrylate, 2.2 g of defoamer, 25 g of pentaerythritol triacrylate, 8 g of fluorinated alkyl acrylate, and 20 g of isopropanol were added, and after stirring, 8.5 g of photoinitiator 1173 was added to obtain a polyurethane acrylate with low water absorption and withstand voltage.

[0031] Comparative Example 1

[0032] (1) To 60 mL of water, 100 g of aqueous polyurethane acrylate, 1.6 g of a defoamer, 30 g of tripropylene glycol diacrylate, and 4 g of n-butanol were added, and after stirring, 7.8 g of a photoinitiator 1173 was added to obtain polyurethane acrylate.

[0033] Comparative Example 2

[0034] (1) To 60 mL of water, 100 g of aqueous polyurethane acrylate, 1.6 g of a defoamer, 30 g of tripropylene glycol diacrylate, 1 g of hexafluorobutyl methacrylate, and 4 g of n-butanol were added, and after stirring, 7.8 g of a photoinitiator 1173 was added to obtain polyurethane acrylate.

[0035] Comparative Example 3

[0036] (1) Prepare an acrylate intermediate according to the method of Example 1.

[0037] (2) Add 5 mmol of acrylate intermediate, 16 mmol of potassium carbonate, and 11 mmol of 1-chloroethane to 50 mL of acetonitrile, heat to 45°C, react for 18 hours, remove acetonitrile by rotary evaporation, wash with water and petroleum ether, and recrystallize the product in chloroform to obtain fluorinated acrylate. The structural formula is as follows:

[0038]

[0039] (3) To 60 mL of water, 100 g of aqueous polyurethane acrylate, 1.6 g of a defoamer, 30 g of tripropylene glycol diacrylate, 1 g of a fluorinated acrylate, and 4 g of n-butanol were added, and after stirring, 7.8 g of a photoinitiator 1173 was added to obtain polyurethane acrylate.

[0040] Comparative Example 4

[0041] (1) Add 10 mmol of 4,4'-bis(4-aminophenoxy)diphenyl ether (CAS No., structural formula: ), 20mmol glycidyl methacrylate, 0.016mmol hydroquinone, heated to 55°C, reacted for 2h, rotary evaporation to remove tetrahydrofuran, washed with water, and recrystallized in chloroform to obtain an acrylate intermediate. The structural formula is:

[0042] (2) Add 5 mmol of acrylate intermediate, 16 mmol of potassium carbonate, and 11 mmol of 1-chlorooctadecane to 50 mL of acetonitrile, heat to 45°C, react for 18 hours, remove acetonitrile by rotary evaporation, wash with water and petroleum ether, and recrystallize the product in chloroform to obtain alkyl acrylate. The structural formula is:

[0043]

[0044] (3) To 60 mL of water, 100 g of aqueous polyurethane acrylate, 1.6 g of a defoamer, 30 g of tripropylene glycol diacrylate, 1 g of an alkyl acrylate, and 4 g of n-butanol were added, and after stirring, 7.8 g of a photoinitiator 1173 was added to obtain polyurethane acrylate.

[0045] The polyurethane acrylate prepared in each embodiment and comparative example was respectively cured by light in a UV curing machine (power 2 kW) for 40 seconds and dried to form a film. The tensile properties were tested according to GB / T 528-2009 standard. The hardness was tested according to GB / T 6739-2022 standard.

[0046] The film was dried, weighed, and soaked in water for 24 hours. The film was taken out, the surface water was dried with filter paper, and the film was weighed to calculate the water absorption rate. Water absorption rate = (mass after water absorption - mass before water absorption) ÷ mass before water absorption × 100%.

[0047] Polyurethane acrylate is coated on the surface of the copper wire conductor through a painting process, and then cured by light for 60 seconds in a UV curing machine (power 2kW), and dried to make an enameled wire. The breakdown voltage is tested according to GB / T 4074.5-2024 standard.

[0048] Table 1

[0049]

[0050] As can be seen from the above table, compared with Comparative Example 1, fluorinated alkyl acrylates are added to the polyurethane acrylates of Examples 1-3, which contain two alkenyl groups and can replace part of the diluents such as tripropylene glycol diacrylate, and undergo UV curing cross-linking reaction with the alkenyl groups of polyurethane acrylate, thereby increasing the cross-linking degree of the molecular chain of polyurethane acrylate, which is beneficial to improving mechanical properties such as tensile strength and hardness. At the same time, multiple flexible phenyl ether groups are introduced into the polyurethane acrylate molecular chain, which plays a good toughening role and is beneficial to improving the elongation at break of the paint film. Fluorinated alkyl acrylates contain hydrophobic and low surface energy alkyl and fluorine-containing groups, which can reduce the hydrophilicity of polyurethane acrylate and show lower water absorption. In addition, the surface hydrophobicity of polyurethane acrylate is improved, which reduces the formation of a hydration layer on the surface of polyurethane acrylate by water molecules in the air, which is beneficial to improving the dielectric properties and showing a higher breakdown voltage, thereby improving its voltage resistance performance.

[0051] In Comparative Example 2, only hexafluorobutyl methacrylate is added, which contains only one olefinic group, and the UV curing crosslinking with the olefinic group of polyurethane acrylate is weak, and there is almost no toughening effect, resulting in low tensile properties and hardness, poor mechanical properties, high water absorption, low breakdown voltage, and poor voltage resistance.

[0052] The fluorine-containing acrylate in Comparative Example 3 does not contain a long alkyl chain, resulting in a larger water absorption rate of the polyurethane acrylate, a lower breakdown voltage, and poor voltage resistance performance.

[0053] The alkyl acrylate of Comparative Example 4 does not contain a fluorine-containing group, resulting in a higher water absorption rate of the polyurethane acrylate, a lower breakdown voltage, and poor voltage resistance performance.

Claims

1. A method for preparing a low water absorption voltage-resistant polyurethane acrylate, characterized in that: The preparation method comprises: adding 100 parts by weight of aqueous polyurethane acrylate, 1.6-2.5 parts by weight of defoamer, 25-30 parts by weight of active diluent, 1-8 parts by weight of fluorine-containing alkyl acrylate, and 4-20 parts by weight of cosolvent into water, stirring, and then adding 7.8-9.3 parts by weight of photoinitiator to obtain low water absorption and voltage-resistant polyurethane acrylate; The structural formula of the fluorinated alkyl acrylate is as follows: n is any integer between 14 and 20.

2. The method for preparing the low water absorption voltage-resistant polyurethane acrylate according to claim 1, characterized in that: The active diluent is tripropylene glycol diacrylate, 1,6-hexanediol diacrylate or pentaerythritol triacrylate; the photoinitiator is photoinitiator 1173 or benzoin ethyl ether.

3. The method for preparing the low water absorption voltage-resistant polyurethane acrylate according to claim 1, characterized in that: The co-solvent is n-butanol, isopropanol or tetrahydrofuran.

4. The method for preparing the low water absorption voltage-resistant polyurethane acrylate according to claim 1, characterized in that: The preparation method of the fluorinated alkyl acrylate is as follows: (1) Add tetrahydrofuran to Phenyl ether type fluorinated diamine, glycidyl methacrylate, and hydroquinone are heated to 45-55°C, reacted for 2-3 hours, and rotary evaporated. The product is washed with water and recrystallized in chloroform to obtain an acrylate intermediate. (2) Adding an acrylic acid ester intermediate, potassium carbonate, and an alkyl chloride to acetonitrile, performing rotary evaporation after the reaction, washing with water and petroleum ether, and recrystallizing the product in chloroform to obtain a fluorinated alkyl acrylate.

5. The method for preparing the low water absorption voltage-resistant polyurethane acrylate according to claim 4, characterized in that: The molar ratio of phenyl ether type fluorinated diamine, glycidyl methacrylate and hydroquinone in (1) is 1:(2-2.2):(0.0016-0.002).

6. The method for preparing the low water absorption voltage-resistant polyurethane acrylate according to claim 4, characterized in that: The reaction temperature in (2) is 40-55°C, and the reaction time is 12-18h.

7. The method for preparing low water absorption voltage-resistant polyurethane acrylate according to claim 4, characterized in that: The molar ratio of the acrylate intermediate, potassium carbonate and alkyl chloride in (2) is 1:(3-3.6):(2.2-2.6).

8. The method for preparing the low water absorption voltage-resistant polyurethane acrylate according to claim 7, characterized in that: The molecular formula of the alkyl chloride is Cl-C n H 2n+1 , n is any integer between 14 and 20.

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