Polyurethane enameled rectangular copper wire for common mode inductor

Abstract

The invention discloses a polyurethane enameled flat copper wire for common mode inductance, comprising a brass flat wire and a polyurethane paint; the polyurethane paint is coated on the brass flat wire. The polyurethane paint comprises the following raw materials in parts by weight: 70-80 parts of a closed polyurethane resin emulsion, 10-15 parts of a filler, 1-1.5 parts of a dispersant, 0.5-1.0 parts of a defoamer, 0.8-1.0 parts of a leveling agent, and 4.5-6.0 parts of a curing agent; the closed polyurethane resin emulsion is prepared by mixing a closed polyurethane resin, γ-aminopropyltriethoxysilane, and deionized water. The closed polyurethane resin molecule comprises a polysiloxane chain and a fluorinated alkane chain, which improves the heat resistance and waterproofness of the polyurethane enameled flat copper wire. The curing agent molecule contains a DOPO structure and a diamino group, which improves the mechanical strength of the enameled flat copper wire and synergistically enhances the flame retardancy of the polyurethane enameled flat copper wire with the closed polyurethane resin.

Description

Technical Field

[0001] The invention relates to the technical field of insulating enameled wires, and in particular to a polyurethane enameled rectangular copper wire for common mode inductors. Background Art

[0002] Enameled wire is the main raw material for products such as motors and electrical appliances. In particular, the electric power industry has achieved sustained and rapid growth in recent years. The rapid development of electrical appliances has brought a wider application field for enameled wire, and with it comes higher requirements for enameled wire. Enameled wire made of polyurethane paint is widely used in weak current electrical products such as coils, motors, instruments, and household appliances such as common mode inductors due to its excellent properties such as low dielectric loss, easy dyeing, high coating rate, and direct solderability. However, in the actual use process, enameled wire made of polyurethane paint has problems such as insufficient mechanical strength and low heat resistance, which need to be solved urgently. In addition, the polyurethane material itself is flammable, resulting in potential fire hazards during use, which is not conducive to the safe use of polyurethane enameled wire.

[0003] In summary, it is of practical significance to develop a suitable modification method to improve the mechanical strength, heat resistance and flame retardancy of polyurethane enameled wire. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a polyurethane enameled rectangular copper wire for common mode inductors.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A polyurethane enameled flat copper wire for a common mode inductor comprises a brass flat wire and polyurethane lacquer; the polyurethane lacquer is coated on the brass flat wire.

[0007] The preparation of the polyurethane enameled rectangular copper wire for the common mode inductor comprises the following steps:

[0008] The polyurethane paint is coated on the brass flat wire by spin coating on a spin coater, and then placed at room temperature for 4-5 hours, and then transferred to an oven at 70-80° C. for 2-3 hours to obtain a polyurethane enameled flat copper wire;

[0009] Furthermore, the diameter of the brass flat wire is 1.5-2.5 mm, and the coating thickness of the polyurethane paint on the brass flat wire is 0.08-0.13 mm;

[0010] The polyurethane paint comprises the following raw materials in parts by weight: 70-80 parts of a closed polyurethane resin emulsion, 10-15 parts of a filler, 1-1.5 parts of a dispersant, 0.5-1.0 parts of a defoamer, 0.8-1.0 parts of a leveling agent, and 4.5-6.0 parts of a curing agent;

[0011] The blocked polyurethane resin emulsion is prepared by mixing blocked polyurethane resin, γ-aminopropyltriethoxysilane and deionized water in a mass ratio of 1:0.3-0.5:1.2-1.6, the filler is mica powder, the dispersant is vinyl acetate copolymer wax emulsion, the defoamer is an organosilicon defoamer, and the leveling agent is a polyether-modified polydimethylsiloxane copolymer;

[0012] The polyurethane paint is prepared by the following steps:

[0013] Add the blocked polyurethane resin emulsion, filler and dispersant to the reactor, mix and stir for 30-40 minutes, then add the defoamer and leveling agent, continue stirring for 20-30 minutes, then add the curing agent and stir for 15-25 minutes to obtain the polyurethane paint.

[0014] The preparation of the blocked polyurethane resin comprises the following steps:

[0015] Step A1: In a nitrogen atmosphere, p-nitrobenzoic acid and methanol are added to a round-bottom flask, stirring is started, the temperature is raised to 40-50° C., pyridine and 1,1,3,3-tetramethyl-1,3-bis[3-(oxiranylmethoxy)propyl]disiloxane are added, and the reaction is stirred at a constant temperature for 9-10 hours to obtain a reaction product 1;

[0016] Further, the amount ratio of p-nitrobenzoic acid, methanol, pyridine and 1,1,3,3-tetramethyl-1,3-bis[3-(oxiranylmethoxy)propyl]disiloxane is 0.2 mol:130-140 mL:0.0012-0.0015 mol:0.1 mol;

[0017] During the reaction of step A1, the carboxyl group of p-nitrobenzoic acid and the epoxy group of 1,1,3,3-tetramethyl-1,3-bis[3-(oxiranylmethoxy)propyl]disiloxane undergo ring-opening to generate a hydroxyl-containing reaction product 1;

[0018] Step A2: Add the reaction product 1, pyridine, triethylamine and dimethyl sulfoxide into a flask to obtain a mixed solution a, then add the above-mentioned heptafluorobutyryl chloride into dimethyl sulfoxide to obtain a mixed solution b, slowly dropwise add the mixed solution b into the mixed solution a in an ice-water bath at 0°C, after the dropwise addition is completed, heat to 40°C, stir and react at a constant temperature for 8-10 hours, and distill under reduced pressure to obtain a reaction product 2;

[0019] Further, the dosage ratio of the reaction product 1, pyridine, triethylamine and dimethyl sulfoxide is 0.1 mol: 0.01-0.015 mol: 0.1 mol: 135-145 mL; the dosage ratio of heptafluorobutyryl chloride and dimethyl sulfoxide is 0.1 mol: 50-60 mL; the dosage ratio of the mixed solution a and the mixed solution b is 140-150 mL: 55-65 mL;

[0020] During the reaction of step A2, the hydroxyl group of the reaction product 1 reacts with heptafluorobutyryl chloride to generate a reaction product 2;

[0021] Step A3: Add the reaction product 2 and toluene to a three-necked flask, heat to 45-55°C, start reflux stirring, then add sodium dithionite, and reflux stirring to react for 1-1.5h to obtain a diamino product; add xylene to a four-necked flask, pass nitrogen, and add the diamino product and triphosgene successively under stirring at 75°C. After the addition is completed, heat to 125°C and continue to react for 3.5h to obtain a modified isocyanate;

[0022] Further, the usage ratio of the reaction product 2, toluene and sodium dithionite is 0.1 mol: 190-200 mL: 0.2-0.25 mol; the usage ratio of xylene, diamino product and triphosgene is 210 mL: 0.1 mol: 0.1 mol;

[0023] During the reaction of step A3, the nitro group of the reaction product 2 is reduced to an amino group, i.e., a diamino product is obtained; the amino group of the diamino product reacts with triphosgene to generate chloroamide, which is then heated to dehydrochlorinate to generate a modified isocyanate;

[0024] Step A4: poly(1,4-butylene adipate) diol, toluene diisocyanate and modified isocyanate are added to a reaction flask, dibutyltin dilaurate is added, nitrogen is introduced, the temperature is raised to 70-80° C., and the reaction is stirred for 3.5-4.5 hours to obtain a prepolymer product; butanone and the above prepolymer product are added to a flask, stirring is started, and ethylenediamine and dimethylglyoxime are added. After stirring at room temperature for 20-30 minutes, the temperature is raised to 70-80° C., and the reaction is stirred for 2.5-3.5 hours to obtain a blocked polyurethane resin;

[0025] Furthermore, the dosage ratio of poly(1,4-butylene adipate diol), toluene diisocyanate, and modified isocyanate is 2.5-3.0 g: 1.5-2.5 g: 0.8-1.4 g, the dosage of dibutyltin dilaurate is 0.1%-0.3% of the dosage of poly(1,4-butylene adipate diol); the dosage ratio of butanone, prepolymer product, and dimethylglyoxime is 5-10 g: 1 g: 0.18-0.24 g, and the dosage of ethylenediamine is 2%-4% of the dosage of poly(1,4-butylene adipate diol);

[0026] During the reaction of step A4, the hydroxyl group of poly(1,4-butylene adipate) diol reacts with the isocyanate group of toluene diisocyanate and modified isocyanate, ethylenediamine participates in the chain extension reaction, and finally dimethylglyoxime protects the unreacted isocyanate group to obtain a blocked polyurethane resin.

[0027] The preparation of the curing agent comprises the following steps:

[0028] Step B1: Add fumaric acid and DOPO to a flask, start stirring, raise the temperature to 125-135°C, and stir at constant temperature for 3-4 hours to obtain reaction product a;

[0029] Furthermore, the ratio of fumaric acid to DOPO was 0.1 mol:0.1 mol;

[0030] During the reaction of step B1, DOPO adds to the carbon-carbon double bond of fumaric acid to obtain a reaction product a;

[0031] Step B2: Add the reaction product a and methanol into a round-bottom flask, introduce nitrogen and start stirring, raise the temperature to 40-50° C., add pyridine and glycidyl methacrylate, and stir at a constant temperature for 9-10 hours to obtain the reaction product b;

[0032] Further, the usage ratio of the reaction product a, methanol, pyridine and glycidyl methacrylate is 0.1 mol: 110-120 mL: 0.0012-0.0015 mol: 0.2 mol;

[0033] During the reaction of step B2, the carboxyl group of the reaction product a and the epoxy group of glycidyl methacrylate are ring-opened to generate a hydroxyl-containing reaction product b;

[0034] Step B3: α-methyl-4-nitrobenzeneacetic acid is added to DMF, and dichlorothionyl is added under stirring, and the mixture is refluxed and stirred at 50° C. for 4 hours to obtain α-methyl-4-nitrobenzeneacetyl chloride; the reaction product b, pyridine, triethylamine and dimethyl sulfoxide are added to a flask to obtain a mixed solution 1, and then the above α-methyl-4-nitrobenzeneacetyl chloride is added to dimethyl sulfoxide to obtain a mixed solution 2, and the mixed solution 2 is slowly added dropwise to the mixed solution 1 in a 0° C. ice-water bath. After the addition is completed, the temperature is raised to 40° C., and the mixture is stirred at a constant temperature for 8-10 hours, and the mixture is distilled under reduced pressure to obtain a reaction product c;

[0035] Further, the dosage ratio of α-methyl-4-nitrophenylacetic acid, DMF, and dichlorothionyl is 0.1 mol: 40 mL: 0.1-0.15 mol; the dosage ratio of reaction product b, pyridine, triethylamine, and dimethyl sulfoxide is 0.1 mol: 0.01-0.015 mol: 0.1 mol: 115-125 mL; the dosage ratio of α-methyl-4-nitrobenzeneacetyl chloride and dimethyl sulfoxide is 0.1 mol: 45-55 mL; the dosage ratio of mixed solution 1 and mixed solution 2 is 120-130 mL: 50-60 mL;

[0036] During the reaction of step B3, α-methyl-4-nitrophenylacetic acid reacts with thionyl chloride to generate α-methyl-4-nitrophenylacetyl chloride; the hydroxyl group of the reaction product b further reacts with α-methyl-4-nitrophenylacetyl chloride to generate a reaction product c;

[0037] Step B4: Add the reaction product c and toluene into a three-necked flask, heat to 45-55°C, start reflux stirring, then add sodium dithionite, and reflux stirring for 1-1.5h to obtain a curing agent;

[0038] Further, the usage ratio of the reaction product c, toluene and sodium dithionite is 0.1 mol: 190-200 mL: 0.2-0.25 mol;

[0039] During the reaction of step B4, the nitro group of the reaction product c is reduced to an amino group, thereby obtaining a curing agent.

[0040] Beneficial effects of the invention: The invention discloses a polyurethane enameled flat copper wire for common mode inductors, comprising a brass flat wire and polyurethane paint. The polyurethane paint comprises raw materials such as a closed polyurethane resin emulsion, a filler, a dispersant, a defoamer, a leveling agent and a curing agent; the closed polyurethane resin emulsion is prepared by mixing a closed polyurethane resin, γ-aminopropyltriethoxysilane and deionized water. The synthesized closed polyurethane resin molecule includes a polysiloxane chain and a fluorine-containing alkane chain; the Si-O-Si bond and Si-C bond contained in the polysiloxane chain have high bond energy and high energy required for breaking, so that the closed polyurethane resin has good thermal stability, improves the heat resistance of the polyurethane paint film, and thus improves the heat resistance of the polyurethane enameled flat copper wire; when the polysiloxane chain burns, it continuously migrates to the combustion surface to form a ceramic carbon layer, making the condensed phase carbon layer more compact; the introduction of the fluorine-containing alkane chain can reduce the surface friction coefficient of the enameled wire, improve the lubricity, and form a polyurethane paint insulation layer with self-lubricating properties, without the need to apply lubricating oil on the surface of the polyurethane paint; the fluorine-containing alkane chain has strong hydrophobicity, reduces the surface energy of the polyurethane paint film, improves the water resistance of the polyurethane paint, and is also conducive to maintaining good insulation performance, so that the waterproofness of the prepared polyurethane enameled flat copper wire meets the use requirements of common mode inductors.

[0041] The synthesized curing agent contains DOPO structure and diamino group in the molecule. The diamino group in the same molecule can cure the closed polyurethane resin more quickly and quickly form a dense cross-linking network, thereby improving the strength of the polyurethane paint film and further improving the mechanical strength of the polyurethane enameled flat copper wire; when the matrix burns, the DOPO structure dehydrates and degrades the polymer surface to form a carbon layer, and the phosphorus-containing derivatives produced at the same time cover the polymer surface, isolating the transfer of combustible gas and heat, and playing a physical shielding flame retardant role in the condensed phase, forming a synergistic flame retardant with the above-mentioned closed polyurethane resin containing polysiloxane chains, and improving the flame retardant properties of the polyurethane enameled wire; the flame-retardant DOPO structure is grafted into the polyurethane by curing and cross-linking, which can also prevent the migration and failure of the small molecule flame retardant DOPO. DETAILED DESCRIPTION

[0042] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] Example 1

[0044] A closed polyurethane resin, the preparation of which comprises the following steps:

[0045] Step A1: In a nitrogen atmosphere, p-nitrobenzoic acid and methanol were added to a round-bottom flask, stirring was started, the temperature was raised to 40°C, pyridine and 1,1,3,3-tetramethyl-1,3-bis[3-(oxiranylmethoxy)propyl]disiloxane were added, and the mixture was stirred at a constant temperature for 9 hours to obtain reaction product 1; the amount ratio of p-nitrobenzoic acid, methanol, pyridine and 1,1,3,3-tetramethyl-1,3-bis[3-(oxiranylmethoxy)propyl]disiloxane was 0.2 mol:130 mL:0.0012 mol:0.1 mol;

[0046] Step A2: adding the reaction product 1, pyridine, triethylamine and dimethyl sulfoxide into a flask to obtain a mixed solution a, then adding the above-mentioned heptafluorobutyryl chloride into dimethyl sulfoxide to obtain a mixed solution b, slowly dropping the mixed solution b into the mixed solution a in an ice-water bath at 0°C, after the dropping is completed, heating to 40°C, stirring at a constant temperature for 8 hours, and distilling under reduced pressure to obtain a reaction product 2; the amount ratio of the reaction product 1, pyridine, triethylamine and dimethyl sulfoxide is 0.1 mol: 0.01 mol: 0.1 mol: 135 mL; the amount ratio of heptafluorobutyryl chloride and dimethyl sulfoxide is 0.1 mol: 50 mL; the amount ratio of the mixed solution a to the mixed solution b is 140 mL: 55 mL;

[0047] Step A3: Add the reaction product 2 and toluene to a three-necked flask, heat to 45°C, start reflux stirring, then add sodium dithionite, and reflux stirring for reaction for 1 hour to obtain a diamino product; add xylene to a four-necked flask, introduce nitrogen, and add the diamino product and triphosgene successively under stirring at 75°C. After the addition is completed, heat to 125°C and continue to react for 3.5 hours to obtain a modified isocyanate; the amount ratio of the reaction product 2, toluene and sodium dithionite is 0.1 mol: 190 mL: 0.2 mol; the amount ratio of xylene, diamino product and triphosgene is 210 mL: 0.1 mol: 0.1 mol;

[0048] Step A4: Add poly(1,4-butylene adipate) diol, toluene diisocyanate, and modified isocyanate to a reaction flask, add dibutyltin dilaurate, introduce nitrogen, heat to 70°C, and react with stirring for 3.5 hours to obtain a prepolymer product; add butanone and the above prepolymer product to a flask, start stirring, then add ethylenediamine and dimethylglyoxime, stir at room temperature for 20 minutes, heat to 70°C, and react with stirring for 2.5 hours to obtain a closed type Polyurethane resin; the dosage ratio of poly(1,4-butylene adipate diol), toluene diisocyanate and modified isocyanate is 2.5g:1.5g:0.8g, the dosage of dibutyltin dilaurate is 0.1% of the dosage of poly(1,4-butylene adipate diol); the dosage ratio of butanone, prepolymer product and dimethylglyoxime is 5g:1g:0.18g, and the dosage of ethylenediamine is 2% of the dosage of poly(1,4-butylene adipate diol).

[0049] Example 2

[0050] A closed polyurethane resin, the preparation of which comprises the following steps:

[0051] Step A1: In a nitrogen atmosphere, p-nitrobenzoic acid and methanol were added to a round-bottom flask, stirring was started, the temperature was raised to 45°C, pyridine and 1,1,3,3-tetramethyl-1,3-bis[3-(oxiranylmethoxy)propyl]disiloxane were added, and the mixture was stirred at a constant temperature for 9.5 hours to obtain reaction product 1; the amount ratio of p-nitrobenzoic acid, methanol, pyridine and 1,1,3,3-tetramethyl-1,3-bis[3-(oxiranylmethoxy)propyl]disiloxane was 0.2 mol:135 mL:0.0013 mol:0.1 mol;

[0052] Step A2: adding the reaction product 1, pyridine, triethylamine and dimethyl sulfoxide into a flask to obtain a mixed solution a, then adding the above-mentioned heptafluorobutyryl chloride into dimethyl sulfoxide to obtain a mixed solution b, slowly dropping the mixed solution b into the mixed solution a in an ice-water bath at 0°C, after the dropping is completed, heating to 40°C, stirring and reacting at a constant temperature for 9 hours, and distilling under reduced pressure to obtain a reaction product 2; the amount ratio of the reaction product 1, pyridine, triethylamine and dimethyl sulfoxide is 0.1 mol: 0.013 mol: 0.1 mol: 140 mL; the amount ratio of heptafluorobutyryl chloride and dimethyl sulfoxide is 0.1 mol: 55 mL; the amount ratio of the mixed solution a to the mixed solution b is 145 mL: 60 mL;

[0053] Step A3: Add the reaction product 2 and toluene to a three-necked flask, heat to 50°C, start reflux stirring, then add sodium dithionite, and reflux stirring to react for 1.3 hours to obtain a diamino product; add xylene to a four-necked flask, pass nitrogen, add the diamino product and triphosgene successively under stirring at 75°C, after the addition is complete, heat to 125°C and continue to react for 3.5 hours to obtain a modified isocyanate; the amount ratio of the reaction product 2, toluene and sodium dithionite is 0.1 mol: 195 mL: 0.23 mol; the amount ratio of xylene, diamino product and triphosgene is 210 mL: 0.1 mol: 0.1 mol;

[0054] Step A4: Add poly(1,4-butylene adipate) diol, toluene diisocyanate, and modified isocyanate to a reaction flask, add dibutyltin dilaurate, introduce nitrogen, heat to 75°C, and react with stirring for 4.0 hours to obtain a prepolymer product; add butanone and the above prepolymer product to a flask, start stirring, then add ethylenediamine and dimethylglyoxime, stir at room temperature for 25 minutes, heat to 75°C, and react with stirring for 3.0 hours to obtain a closed type Polyurethane resin; the dosage ratio of poly(1,4-butylene adipate diol), toluene diisocyanate and modified isocyanate is 2.7g:2.0g:1.1g, the dosage of dibutyltin dilaurate is 0.2% of the dosage of poly(1,4-butylene adipate diol); the dosage ratio of butanone, prepolymer product and dimethylglyoxime is 7g:1g:0.21g, and the dosage of ethylenediamine is 3% of the dosage of poly(1,4-butylene adipate diol).

[0055] Example 3

[0056] A closed polyurethane resin, the preparation of which comprises the following steps:

[0057] Step A1: In a nitrogen atmosphere, p-nitrobenzoic acid and methanol were added to a round-bottom flask, stirring was started, the temperature was raised to 50° C., pyridine and 1,1,3,3-tetramethyl-1,3-bis[3-(oxiranylmethoxy)propyl]disiloxane were added, and the mixture was stirred at a constant temperature for 10 h to obtain a reaction product 1; the amount ratio of p-nitrobenzoic acid, methanol, pyridine and 1,1,3,3-tetramethyl-1,3-bis[3-(oxiranylmethoxy)propyl]disiloxane was 0.2 mol:140 mL:0.0015 mol:0.1 mol;

[0058] Step A2: adding the reaction product 1, pyridine, triethylamine and dimethyl sulfoxide into a flask to obtain a mixed solution a, then adding the above-mentioned heptafluorobutyryl chloride into dimethyl sulfoxide to obtain a mixed solution b, slowly dropping the mixed solution b into the mixed solution a in an ice-water bath at 0°C, after the dropping is completed, heating to 40°C, stirring and reacting at a constant temperature for 10 hours, and distilling under reduced pressure to obtain a reaction product 2; the amount ratio of the reaction product 1, pyridine, triethylamine and dimethyl sulfoxide is 0.1 mol: 0.015 mol: 0.1 mol: 145 mL; the amount ratio of heptafluorobutyryl chloride and dimethyl sulfoxide is 0.1 mol: 60 mL; the amount ratio of the mixed solution a to the mixed solution b is 150 mL: 65 mL;

[0059] Step A3: Add the reaction product 2 and toluene to a three-necked flask, heat to 55°C, start reflux stirring, then add sodium dithionite, and reflux stirring to react for 1.5 hours to obtain a diamino product; add xylene to a four-necked flask, pass nitrogen, and add the diamino product and triphosgene successively under stirring at 75°C. After the addition is completed, heat to 125°C and continue to react for 3.5 hours to obtain a modified isocyanate; the amount ratio of the reaction product 2, toluene and sodium dithionite is 0.1 mol: 200 mL: 0.25 mol; the amount ratio of xylene, diamino product and triphosgene is 210 mL: 0.1 mol: 0.1 mol;

[0060] Step A4: Add poly(1,4-butylene adipate) diol, toluene diisocyanate, and modified isocyanate to a reaction flask, add dibutyltin dilaurate, introduce nitrogen, heat to 80°C, and react with stirring for 4.5 hours to obtain a prepolymer product; add butanone and the above prepolymer product to a flask, start stirring, then add ethylenediamine and dimethylglyoxime, stir at room temperature for 30 minutes, heat to 80°C, and react with stirring for 3.5 hours to obtain a closed type Polyurethane resin; the dosage ratio of poly(1,4-butylene adipate diol), toluene diisocyanate and modified isocyanate is 3.0g:2.5g:1.4g, the dosage of dibutyltin dilaurate is 0.3% of the dosage of poly(1,4-butylene adipate diol); the dosage ratio of butanone, prepolymer product and dimethylglyoxime is 10g:1g:0.24g, and the dosage of ethylenediamine is 4% of the dosage of poly(1,4-butylene adipate diol).

[0061] Example 4

[0062] A curing agent, the preparation of which comprises the following steps:

[0063] Step B1: Add fumaric acid and DOPO to a flask, start stirring, heat to 125°C, and stir at constant temperature for 3 hours to obtain reaction product a; the amount ratio of fumaric acid to DOPO is 0.1 mol:0.1 mol;

[0064] Step B2: Add the reaction product a and methanol into a round-bottom flask, introduce nitrogen and start stirring, heat to 40°C, add pyridine and glycidyl methacrylate, and react at constant temperature with stirring for 9 hours to obtain the reaction product b; the amount ratio of the reaction product a, methanol, pyridine and glycidyl methacrylate is 0.1 mol: 110 mL: 0.0012 mol: 0.2 mol;

[0065] Step B3: Add α-methyl-4-nitrobenzeneacetic acid to DMF, add dichlorothionyl under stirring, and reflux and stir at 50°C for 4 hours to obtain α-methyl-4-nitrobenzeneacetyl chloride; add the reaction product b, pyridine, triethylamine and dimethyl sulfoxide to a flask to obtain a mixed solution 1, then add the above α-methyl-4-nitrobenzeneacetyl chloride to dimethyl sulfoxide to obtain a mixed solution 2, slowly dropwise add the mixed solution 2 to the mixed solution 1 in a 0°C ice-water bath, and after the dropwise addition is completed, heat to 40°C, and stir and react at a constant temperature for 8 hours. , distill under reduced pressure to obtain reaction product c; the usage ratio of α-methyl-4-nitrophenylacetic acid, DMF, and dichlorothionyl is 0.1mol:40mL:0.1mol; the usage ratio of reaction product b, pyridine, triethylamine, and dimethyl sulfoxide is 0.1mol:0.01mol:0.1mol:115mL; the usage ratio of α-methyl-4-nitrophenylacetyl chloride and dimethyl sulfoxide is 0.1mol:45mL; the usage ratio of mixed solution 1 and mixed solution 2 is 120mL:50mL;

[0066] Step B4: Add the reaction product c and toluene into a three-necked flask, heat to 45°C, start reflux stirring, then add sodium dithionite, and reflux stirring to react for 1 hour to obtain a curing agent; the dosage ratio of the reaction product c, toluene and sodium dithionite is 0.1 mol: 190 mL: 0.2 mol.

[0067] Example 5

[0068] A curing agent, the preparation of which comprises the following steps:

[0069] Step B1: Add fumaric acid and DOPO to a flask, start stirring, heat to 130°C, and stir at constant temperature for 3.5 hours to obtain reaction product a; the ratio of fumaric acid to DOPO is 0.1 mol:0.1 mol;

[0070] Step B2: Add the reaction product a and methanol into a round-bottom flask, introduce nitrogen and start stirring, heat to 45°C, add pyridine and glycidyl methacrylate, and react at constant temperature with stirring for 9.5 hours to obtain the reaction product b; the amount ratio of the reaction product a, methanol, pyridine and glycidyl methacrylate is 0.1 mol: 115 mL: 0.0013 mol: 0.2 mol;

[0071] Step B3: α-methyl-4-nitrobenzeneacetic acid is added to DMF, and dichlorothionyl is added under stirring, and the mixture is refluxed and stirred at 50° C. for 4 hours to obtain α-methyl-4-nitrobenzeneacetyl chloride; the reaction product b, pyridine, triethylamine and dimethyl sulfoxide are added to a flask to obtain a mixed solution 1, and then the above α-methyl-4-nitrobenzeneacetyl chloride is added to dimethyl sulfoxide to obtain a mixed solution 2, and the mixed solution 2 is slowly added dropwise to the mixed solution 1 in an ice-water bath at 0° C. After the addition is completed, the temperature is raised to 40° C. and the mixture is stirred at a constant temperature for 9 hours. The reaction product c was obtained by distillation under reduced pressure; the dosage ratio of α-methyl-4-nitrophenylacetic acid, DMF and dichlorothionyl was 0.1 mol: 40 mL: 0.13 mol; the dosage ratio of reaction product b, pyridine, triethylamine and dimethyl sulfoxide was 0.1 mol: 0.013 mol: 0.1 mol: 120 mL; the dosage ratio of α-methyl-4-nitrophenylacetyl chloride and dimethyl sulfoxide was 0.1 mol: 50 mL; the dosage ratio of mixed solution 1 and mixed solution 2 was 125 mL: 55 mL;

[0072] Step B4: Add the reaction product c and toluene into a three-necked flask, heat to 50°C, start reflux stirring, then add sodium dithionite, and reflux stirring to react for 1.3 hours to obtain a curing agent; the amount ratio of the reaction product c, toluene and sodium dithionite is 0.1 mol: 195 mL: 0.23 mol.

[0073] Example 6

[0074] A curing agent, the preparation of which comprises the following steps:

[0075] Step B1: Add fumaric acid and DOPO to a flask, start stirring, heat to 135°C, and stir at constant temperature for 4 hours to obtain reaction product a; the amount ratio of fumaric acid to DOPO is 0.1 mol:0.1 mol;

[0076] Step B2: Add the reaction product a and methanol into a round-bottom flask, introduce nitrogen and start stirring, heat to 50°C, add pyridine and glycidyl methacrylate, and react at constant temperature and stirring for 10 hours to obtain the reaction product b; the amount ratio of the reaction product a, methanol, pyridine and glycidyl methacrylate is 0.1 mol: 120 mL: 0.0015 mol: 0.2 mol;

[0077] Step B3: Add α-methyl-4-nitrobenzeneacetic acid to DMF, add dichlorothionyl under stirring, and reflux and stir at 50°C for 4 hours to obtain α-methyl-4-nitrobenzeneacetyl chloride; add the reaction product b, pyridine, triethylamine and dimethyl sulfoxide to a flask to obtain a mixed solution 1, and then add the above α-methyl-4-nitrobenzeneacetyl chloride to dimethyl sulfoxide to obtain a mixed solution 2. In a 0°C ice-water bath, slowly drop the mixed solution 2 into the mixed solution 1. After the dropwise addition is completed, the temperature is raised to 40°C, and the reaction is stirred at a constant temperature for 10 hours. , distill under reduced pressure to obtain reaction product c; the usage ratio of α-methyl-4-nitrophenylacetic acid, DMF, and dichlorothionyl is 0.1mol:40mL:0.15mol; the usage ratio of reaction product b, pyridine, triethylamine, and dimethyl sulfoxide is 0.1mol:0.015mol:0.1mol:125mL; the usage ratio of α-methyl-4-nitrophenylacetyl chloride and dimethyl sulfoxide is 0.1mol:55mL; the usage ratio of mixed solution 1 and mixed solution 2 is 130mL:60mL;

[0078] Step B4: Add the reaction product c and toluene into a three-necked flask, heat to 55°C, start reflux stirring, then add sodium dithionite, and reflux stirring to react for 1.5 hours to obtain a curing agent; the amount ratio of the reaction product c, toluene and sodium dithionite is 0.1 mol: 200 mL: 0.25 mol.

[0079] Example 7

[0080] A polyurethane enameled flat copper wire for a common mode inductor comprises a brass flat wire and polyurethane lacquer; the polyurethane lacquer is coated on the brass flat wire.

[0081] The polyurethane paint is prepared by the following steps:

[0082] Add a blocked polyurethane resin emulsion, a filler, and a dispersant to a reaction kettle, mix and stir for 30 minutes, then add a defoamer and a leveling agent, continue stirring for 20 minutes, then add the curing agent obtained in Example 4, and stir for 15 minutes to obtain a polyurethane paint; the blocked polyurethane resin emulsion is prepared by mixing the blocked polyurethane resin obtained in Example 1, γ-aminopropyltriethoxysilane and deionized water in a mass ratio of 1:0.3:1.2, the filler is mica powder, the dispersant is a vinyl acetate copolymer wax emulsion, the defoamer is an organosilicon defoamer, and the leveling agent is a polyether-modified polydimethylsiloxane copolymer;

[0083] The preparation of the polyurethane enameled rectangular copper wire for the common mode inductor comprises the following steps:

[0084] The polyurethane paint is coated on the brass flat wire by spin coating on a spin coater, and then placed at room temperature for 4 hours, and then transferred to an oven at 70°C for 2 hours to obtain a polyurethane enameled flat copper wire; the diameter of the brass flat wire is 1.5 mm, and the coating thickness of the polyurethane paint on the brass flat wire is 0.08 mm.

[0085] Example 8

[0086] A polyurethane enameled flat copper wire for common mode inductance comprises a brass flat wire and polyurethane varnish; the wire is obtained by coating the polyurethane varnish on the brass flat wire.

[0087] The polyurethane paint is prepared by the following steps:

[0088] Add a blocked polyurethane resin emulsion, a filler, and a dispersant to a reaction kettle, mix and stir for 35 minutes, then add a defoamer and a leveling agent, continue stirring for 25 minutes, then add the curing agent obtained in Example 4, and stir for 20 minutes to obtain a polyurethane paint; the blocked polyurethane resin emulsion is prepared by mixing the blocked polyurethane resin obtained in Example 1, γ-aminopropyltriethoxysilane and deionized water in a mass ratio of 1:0.4:1.4, the filler is mica powder, the dispersant is a vinyl acetate copolymer wax emulsion, the defoamer is an organosilicon defoamer, and the leveling agent is a polyether-modified polydimethylsiloxane copolymer;

[0089] The preparation of the polyurethane enameled rectangular copper wire for the common mode inductor comprises the following steps:

[0090] The polyurethane paint is coated on the brass flat wire by spin coating on a spin coater, and then placed at room temperature for 4.5 hours, and then transferred to an oven at 75°C for 2.5 hours to obtain a polyurethane enameled flat copper wire; the diameter of the brass flat wire is 2.0 mm, and the coating thickness of the polyurethane paint on the brass flat wire is 0.10 mm.

[0091] Example 9

[0092] A polyurethane enameled flat copper wire for common mode inductance comprises a brass flat wire and polyurethane varnish; the wire is obtained by coating the polyurethane varnish on the brass flat wire.

[0093] The polyurethane paint is prepared by the following steps:

[0094] Add a blocked polyurethane resin emulsion, a filler, and a dispersant to a reaction kettle, mix and stir for 40 minutes, then add a defoamer and a leveling agent, continue stirring for 30 minutes, then add the curing agent obtained in Example 4, and stir for 25 minutes to obtain a polyurethane paint; the blocked polyurethane resin emulsion is prepared by mixing the blocked polyurethane resin obtained in Example 1, γ-aminopropyltriethoxysilane and deionized water in a mass ratio of 1:0.5:1.6, the filler is mica powder, the dispersant is a vinyl acetate copolymer wax emulsion, the defoamer is a silicone defoamer, and the leveling agent is a polyether-modified polydimethylsiloxane copolymer;

[0095] The preparation of the polyurethane enameled rectangular copper wire for the common mode inductor comprises the following steps:

[0096] The polyurethane paint is coated on the brass flat wire by spin coating on a spin coater, and then placed at room temperature for 5 hours, and then transferred to an oven at 80° C. and placed for 3 hours to obtain a polyurethane enameled flat copper wire; the diameter of the brass flat wire is 2.5 mm, and the coating thickness of the polyurethane paint on the brass flat wire is 0.13 mm.

[0097] Comparative Example 1

[0098] This comparative example is a commercially available polyurethane enameled rectangular copper wire.

[0099] Comparative Example 2

[0100] Compared with Example 9, the modified isocyanate used in the preparation of the blocked polyurethane resin was replaced with toluene diisocyanate, and the rest was exactly the same as Example 9 to prepare a polyurethane enameled rectangular copper wire for a common mode inductor.

[0101] Comparative Example 3

[0102] Compared with Example 9, the curing agent used in the preparation of the polyurethane paint was replaced with 2-aminoethyl methacrylate, and the rest was exactly the same as Example 9 to prepare a polyurethane enameled rectangular copper wire for a common mode inductor.

[0103] The polyurethane enameled rectangular copper wire for common mode inductors prepared by the present invention is further tested for its effect, and the test results are as follows.

[0104] The polyurethane paint used in the polyurethane enameled rectangular copper wire for common mode inductors obtained in Examples 7-9 and Comparative Examples 1-3 was tested for surface hardness according to GB / T6739-2022 "Determination of paint film hardness by pencil method for paints and varnishes"; the water resistance test was performed according to GB / T1733-1993 "Determination of water resistance of paint films"; the paint film was subjected to a 230°C thermal shock test with reference to GB / T6109.1-2008, and a heat resistance test was performed to observe whether the paint film cracked; the oxygen index was tested according to GB / T2406.2-2009 "Determination of combustion behavior by oxygen index method for plastics", and the results were recorded in Table 1;

[0105] Table 1: Test results

[0106]

[0107] According to the data in Table 1, compared with Example 1, it can be seen that the polyurethane paint used for the polyurethane enameled flat copper wire for the common mode inductor obtained by the present invention has good strength, water resistance, heat resistance and flame retardancy compared with the commercially available polyurethane enameled flat copper wire, so that the polyurethane enameled flat copper wire has good mechanical strength, heat resistance, water resistance and flame retardancy; compared with Example 2, it can be seen that the introduction of polysiloxane chains and fluorine-containing alkane chains into the closed polyurethane resin helps to improve the heat resistance, water resistance and flame retardancy of the polyurethane paint, thereby improving the heat resistance, water resistance and flame retardancy of the polyurethane enameled flat copper wire; compared with Example 3, it can be seen that the curing agent contains DOPO and diamino, which is conducive to improving the flame retardant performance and strength of the polyurethane paint, thereby improving the flame retardant performance and mechanical strength of the polyurethane enameled flat copper wire.

[0108] The above contents are merely examples and explanations of the concept of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A polyurethane enameled rectangular copper wire for common mode inductors, characterized in that: The invention comprises a brass flat wire and polyurethane paint; the polyurethane paint is coated on the brass flat wire; the polyurethane paint comprises the following raw materials in parts by weight: 70-80 parts of a closed polyurethane resin emulsion, 10-15 parts of a filler, 1-1.5 parts of a dispersant, 0.5-1.0 parts of a defoamer, 0.8-1.0 parts of a leveling agent and 4.5-6.0 parts of a curing agent; the closed polyurethane resin emulsion is prepared by mixing a closed polyurethane resin, γ-aminopropyltriethoxysilane and deionized water in a mass ratio of 1:0.3-0.5:1.2-1.6; The preparation of the blocked polyurethane resin comprises the following steps: Step A1: In a nitrogen atmosphere, p-nitrobenzoic acid and methanol are added to a round-bottom flask, stirring is started, the temperature is raised to 40-50° C., pyridine and 1,1,3,3-tetramethyl-1,3-bis[3-(oxiranylmethoxy)propyl]disiloxane are added, and the reaction is stirred at a constant temperature for 9-10 hours to obtain a reaction product 1; Step A2: Add the reaction product 1, pyridine, triethylamine and dimethyl sulfoxide into a flask to obtain a mixed solution a, then add heptafluorobutyryl chloride into dimethyl sulfoxide to obtain a mixed solution b, slowly dropwise add the mixed solution b into the mixed solution a in an ice-water bath at 0°C, after the dropwise addition is completed, heat to 40°C, stir and react at a constant temperature for 8-10 hours, and distill under reduced pressure to obtain a reaction product 2; Step A3: Add the reaction product 2 and toluene to a three-necked flask, heat to 45-55°C, start reflux stirring, then add sodium dithionite, and reflux stirring to react for 1-1.5h to obtain a diamino product; add xylene to a four-necked flask, pass nitrogen, and add the diamino product and triphosgene successively under stirring at 75°C. After the addition is completed, heat to 125°C and continue to react for 3.5h to obtain a modified isocyanate; Step A4: poly(1,4-butylene adipate) diol, toluene diisocyanate and modified isocyanate are added to a reaction flask, dibutyltin dilaurate is added, nitrogen is introduced, the temperature is raised to 70-80° C., and the reaction is stirred for 3.5-4.5 hours to obtain a prepolymer product; butanone and the above prepolymer product are added to a flask, stirring is started, and ethylenediamine and dimethylglyoxime are added. After stirring at room temperature for 20-30 minutes, the temperature is raised to 70-80° C., and the reaction is stirred for 2.5-3.5 hours to obtain a blocked polyurethane resin; The preparation of the curing agent comprises the following steps: Step B1: Add fumaric acid and DOPO to a flask, start stirring, raise the temperature to 125-135°C, and stir at constant temperature for 3-4 hours to obtain reaction product a; Step B2: Add the reaction product a and methanol into a round-bottom flask, introduce nitrogen and start stirring, raise the temperature to 40-50° C., add pyridine and glycidyl methacrylate, and stir at a constant temperature for 9-10 hours to obtain the reaction product b; Step B3: Add α-methyl-4-nitrophenylacetic acid to DMF, add dichlorothionyl under stirring, and reflux and stir at 50° C. for 4 h to obtain α-methyl-4-nitrophenylacetyl chloride; Add the reaction product b, pyridine, triethylamine and dimethyl sulfoxide into a flask to obtain a mixed solution 1, then add the above-mentioned α-methyl-4-nitrobenzeneacetyl chloride into dimethyl sulfoxide to obtain a mixed solution 2, slowly dropwise add the mixed solution 2 into the mixed solution 1 in an ice-water bath at 0°C, after the dropwise addition is completed, heat to 40°C, stir and react at a constant temperature for 8-10 hours, and distill under reduced pressure to obtain a reaction product c; Step B4: Add the reaction product c and toluene into a three-necked flask, heat to 45-55°C, start reflux stirring, then add sodium dithionite, and reflux stirring for 1-1.5h to obtain a curing agent; The diameter of the brass flat wire is 1.5-2.5 mm, and the coating thickness of the polyurethane paint on the brass flat wire is 0.08-0.13 mm; the filler is mica powder, the dispersant is vinyl acetate copolymer wax emulsion, the defoamer is an organosilicon defoamer, and the leveling agent is a polyether modified polydimethylsiloxane copolymer.

2. The polyurethane enameled rectangular copper wire for common mode inductors according to claim 1, characterized in that: In step A1, the usage ratio of p-nitrobenzoic acid, methanol, pyridine and 1,1,3,3-tetramethyl-1,3-bis[3-(oxiranylmethoxy)propyl]disiloxane is 0.2 mol:130-140 mL:0.0012-0.0015 mol:0.1 mol.

3. The polyurethane enameled rectangular copper wire for common mode inductors according to claim 1, characterized in that: In step A2, the amount ratio of reaction product 1, pyridine, triethylamine and dimethyl sulfoxide is 0.1 mol: 0.01-0.015 mol: 0.1 mol: 135-145 mL; the amount ratio of heptafluorobutyryl chloride and dimethyl sulfoxide is 0.1 mol: 50-60 mL; the amount ratio of mixed solution a and mixed solution b is 140-150 mL: 55-65 mL.

4. The polyurethane enameled rectangular copper wire for common mode inductors according to claim 1, characterized in that: In step A3, the usage ratio of reaction product 2, toluene and sodium dithionite is 0.1 mol: 190-200 mL: 0.2-0.25 mol; the usage ratio of xylene, diamino product and triphosgene is 210 mL: 0.1 mol: 0.1 mol.

5. The polyurethane enameled rectangular copper wire for common mode inductors according to claim 1, characterized in that: In step A4, the dosage ratio of poly(1,4-butylene adipate diol), toluene diisocyanate, and modified isocyanate is 2.5-3.0 g: 1.5-2.5 g: 0.8-1.4 g, the dosage of dibutyltin dilaurate is 0.1%-0.3% of the dosage of poly(1,4-butylene adipate diol); the dosage ratio of butanone, prepolymer product, and dimethylglyoxime is 5-10 g: 1g: 0.18-0.24g, the amount of ethylenediamine used is 2%-4% of the amount of poly(1,4-butylene adipate)diol used.

6. The polyurethane enameled rectangular copper wire for common mode inductors according to claim 1, characterized in that: In step B1, the usage ratio of fumaric acid and DOPO is 0.1 mol:0.1 mol; in step B2, the usage ratio of reaction product a, methanol, pyridine and glycidyl methacrylate is 0.1 mol:110-120 mL:0.0012-0.0015 mol:0.2 mol.

7. The polyurethane enameled rectangular copper wire for common mode inductors according to claim 1, characterized in that: In step B3, the amount ratio of α-methyl-4-nitrophenylacetic acid, DMF, and dichlorothionyl is 0.1 mol: 40 mL: 0.1-0.15 mol; the amount ratio of the reaction product b, pyridine, triethylamine and dimethyl sulfoxide is 0.1 mol: 0.01-0.015 mol: 0.1 mol: 115-125 mL; the amount ratio of α-methyl-4-nitrobenzeneacetyl chloride and dimethyl sulfoxide is 0.1 mol: 45-55 mL; the amount ratio of mixed solution 1 and mixed solution 2 is 120-130 mL: 50-60 mL.

8. The polyurethane enameled rectangular copper wire for common mode inductors according to claim 1, characterized in that: In step B4, the usage ratio of the reaction product c, toluene and sodium dithionite is 0.1 mol:190-200 mL:0.2-0.25 mol.

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