A PI transfer film for graphite rolling and its preparation method

Abstract

The present invention discloses a PI transfer film for graphite calendering and a preparation method thereof. Using 4,4'-diaminodiphenyl ether, a modified monomer and 3,3',4,4'-biphenyltetracarboxylic dianhydride as raw materials for reaction, a polyamic acid solution is prepared. The polyamic acid solution, modified lignin and dimethyldiethoxysilane are subjected to hydrolysis grafting to obtain a casting solution. The casting solution is cast into a film, the temperature is raised to cause the condensation of the hydrolyzed and grafted siloxane, and the temperature is further raised to convert the polyamic acid molecules into a polyimide structure, thereby obtaining the PI transfer film. During the hydrolysis grafting and condensation of the polyamic acid solution, modified lignin and dimethyldiethoxysilane, an organosilicon structure is formed among the three, which can appropriately increase the crosslinking degree of the material, greatly improving the impact resistance and toughness of the transfer film. At the same time, a hydrophobic protective film is formed on the surface of the transfer film, further enhancing the water resistance of the transfer film.

Description

Technical Field

[0001] The present invention relates to the technical field of graphite rolling preparation, and particularly relates to a PI transfer film for graphite rolling and a preparation method thereof. Background Art

[0002] Polyimide film is the best film-like insulating material in the world. It is formed by polycondensation of pyromellitic dianhydride and diaminodiphenyl ether in a strongly polar solvent, followed by casting into a film and then imidization. During the graphite rolling process, in the double-layer rolling, the fired graphite sheet is directly placed on the heavy release film, then a transfer film with a lighter gram weight is laminated on the graphite sheet, and then pressed by a precision chrome-plated steel roller. After pressing, the light release film is peeled off, and finally collected. Existing polyimide transfer films, due to the large brittleness and easy moisture absorption of polyimide itself, when used in an environment with high air humidity, the transfer film absorbs water, resulting in a decline in performance, thereby affecting graphite rolling. Summary of the Invention

[0003] The purpose of the present invention is to provide a PI transfer film for graphite rolling and a preparation method thereof, which solves the problems that the current PI transfer film is brittle and its mechanical properties are easily reduced due to easy moisture absorption.

[0004] The purpose of the present invention can be achieved by the following technical solutions:

[0005] A preparation method of a PI transfer film for graphite rolling specifically includes the following steps:

[0006] Step A1: Mix 4,4'-diaminodiphenyl ether, a modified monomer, 3,3',4,4'-biphenyltetracarboxylic dianhydride, and N,N-dimethylacetamide, introduce nitrogen protection, and react for 3-5 h under the conditions of a rotation speed of 200-300 r / min and a temperature of 25-30 °C to obtain a polyamic acid solution. Dissolve lignin in DMF, stir and add dibutyltin dilaurate and isocyanatopropyltrimethoxysilane under the conditions of a rotation speed of 120-150 r / min and a temperature of 30-40 °C, and react for 2-3 h to obtain modified lignin;

[0007] Step A2: Mix the polyamic acid solution, modified lignin, dimethyldiethoxysilane, and DMF evenly, stir and add deionized water and hydrochloric acid solution under the conditions of a rotation speed of 200-300 r / min and a temperature of 65-70 °C, and react for 3-5 h to obtain a casting solution. Perform film scraping treatment, keep warm for 3-5 h at a temperature of 120-130 °C, raise the temperature to 250-260 °C, keep warm for 15-20 min, and then raise the temperature to 340-350 °C and keep warm for 10-15 min to obtain a PI transfer film.

[0008] Further, the dosage ratios of 4,4'-diaminodiphenyl ether, modified monomer, 3,3',4,4'-biphenyltetracarboxylic dianhydride and N,N-dimethylacetamide described in step A1 are 200 mmol: 50 mol: 150 mL: 400 mL, and the dosage ratios of lignin and isocyanatopropyltrimethoxysilane are 1 g: 1 mL, and the dosage of dibutyltin dilaurate is 1% of the mass of isocyanatopropyltrimethoxysilane.

[0009] Further, the dosage ratios of the polyamic acid solution, modified lignin, dimethyldiethoxysilane, DMF, deionized water and hydrochloric acid solution described in step A2 are 500 mL: 3 g: 10 mL: 20 mL: 40 mL: 5 mL, and the mass fraction of the hydrochloric acid solution is 10%.

[0010] Further, the modified monomer is prepared by the following steps:

[0011] Step B1: Mix cetyltrimethoxysilane, sodium hydroxide, isopropanol and deionized water evenly, and carry out a reaction for 10 - 15 h under the conditions of a rotation speed of 120 - 150 r / min and a temperature of 85 - 90 °C to obtain sodium cetylcyclotetrasiloxanetetrol. Mix sodium cetylcyclotetrasiloxanetetrol, triethylamine and tetrahydrofuran evenly, introduce nitrogen protection, and stir and add methyldichlorosilane under the conditions of a rotation speed of 150 - 200 r / min and a temperature of 0 °C, and carry out a reaction for 3 - 5 h, then raise the temperature to 20 - 25 °C and carry out a reaction for 20 - 25 h to obtain dihydridosilsesquioxane;

[0012] Step B2: Mix dihydridosilsesquioxane, caffeic acid, Caster catalyst and DMF evenly, introduce nitrogen protection, and carry out a reaction for 20 - 25 h under the conditions of a rotation speed of 60 - 80 r / min and a temperature of 80 - 85 °C to obtain intermediate 1. Mix intermediate 1, p-nitrophenylboronic acid, 5A molecular sieve and DMF evenly, introduce nitrogen protection, and carry out a reaction for 10 - 15 h under the conditions of a rotation speed of 120 - 150 r / min and a temperature of 60 - 65 °C to obtain intermediate 2;

[0013] Step B3: Mix intermediate 2, KH550, dicyclohexylcarbodiimide, toluene and DMF evenly, and carry out a reaction for 3 - 5 h under the conditions of a rotation speed of 200 - 300 r / min and a temperature of 30 - 40 °C to obtain intermediate 3. Mix 4-hydroxyphthalonitrile, potassium carbonate and DMF evenly, introduce nitrogen protection, and carry out a reaction for 1 - 1.5 h under the conditions of a rotation speed of 150 - 200 r / min and a temperature of 20 - 25 °C, then add intermediate 3 and continue the reaction for 20 - 25 h to obtain intermediate 4;

[0014] Step B4: Mix intermediate 4, sodium hydroxide, and DMF evenly, protect with nitrogen, react at a temperature of 90 - 95 °C for 10 - 15 h, raise the temperature to 100 - 110 °C, and continue to react for 25 - 30 h to obtain intermediate 5. Mix intermediate 5, acetic anhydride, and glacial acetic acid evenly, protect with nitrogen, react at a rotational speed of 60 - 80 r / min and a temperature of 100 - 105 °C for 10 - 15 h to obtain the modified monomer.

[0015] Further, the dosage ratio of cetyltrimethoxysilane, sodium hydroxide, isopropanol, and deionized water in step B1 is 150 mmol: 80 mmol: 120 mL: 5 mL, and the dosage ratio of cetylcyclotetrasiloxane tetrasodium silanolate, triethylamine, tetrahydrofuran, and methyldichlorosilane is 20 g: 5 g: 30 mL: 4 g.

[0016] Further, the molar ratio of dihydroxycage - type silsesquioxane and caffeic acid in step B2 is 1:2, the dosage of the Cast catalyst is 2‰ of the mass of caffeic acid, and the dosage ratio of intermediate 1, p - nitrophenylboronic acid, and 5A molecular sieve is 16 mmol: 8 mmol: 2 g.

[0017] Further, the molar ratio of intermediate 2, KH550, and dicyclohexylcarbodiimide in step B3 is 1:2:2.1, and the molar ratio of 4 - hydroxyphthalonitrile, potassium carbonate, and intermediate 3 is 2:1:1.

[0018] Further, the dosage ratio of intermediate 4, sodium hydroxide, and DMF in step B4 is 1 mmol: 5 mmol: 2 mL, and the dosage ratio of intermediate 5, acetic anhydride, and glacial acetic acid is 10 mmol: 1 mL: 2 mL.

[0019] The beneficial effects of the present invention: A PI transfer film for graphite rolling prepared by the present invention reacts with 4,4'-diaminodiphenyl ether, a modified monomer, and 3,3',4,4'-biphenyltetracarboxylic dianhydride as raw materials to obtain a polyamic acid solution. Treat lignin with isocyanatopropyltrimethoxysilane so that the hydroxyl group on lignin reacts with the isocyanate group on isocyanatopropyltrimethoxysilane to obtain modified lignin. Hydrolyze and graft the polyamic acid solution, modified lignin, and dimethyldiethoxysilane to obtain a casting solution. Scrape the casting solution, raise the temperature to condense the hydrolyzed and grafted siloxane, and continue to raise the temperature to convert the polyamic acid molecules into a polyimide structure to obtain the PI transfer film.

[0020] The modified monomer is hydrolyzed and grafted with cetyltrimethoxysilane to form sodium cetylcyclotetrasiloxanetetrasilanol. The sodium cetylcyclotetrasiloxanetetrasilanol is reacted with methyldichlorosilane to allow the tetrasilanol sodium to react with the chlorine atom sites, yielding dihydrocage-like silsesquioxane. Under the action of a Karstedt catalyst, the Si-H bond on the dihydrocage-like silsesquioxane and the double bond on caffeic acid are grafted to obtain Intermediate 1. Intermediate 1 is reacted with p-nitrophenylboronic acid to enable the catechol on Intermediate 1 to react with the boronic acid group on p-nitrophenylboronic acid, obtaining Intermediate 2. Intermediate 2 is reacted with KH550 to cause the carboxyl group on Intermediate 2 and the amino group on KH550 to undergo a dehydration reaction, obtaining Intermediate 3. Intermediate 3 is reacted with 4-hydroxyphthalonitrile to make the nitro group on Intermediate 3 react with 4-hydroxyphthalonitrile, obtaining Intermediate 4. Intermediate 4 is treated with sodium hydroxide to convert the nitrile group into a carboxyl group, obtaining Intermediate 5. Intermediate 5 is reacted under the action of acetic anhydride and glacial acetic acid to convert the phthalic carboxyl group on Intermediate 5 into a benzoic anhydride, obtaining the modified monomer.

[0021] The modified monomer contains cage-like silsesquioxane and long-chain alkyl groups, which can enhance the mechanical properties of the transfer film. During the hydrolysis grafting and condensation of polyamic acid solution, modified lignin, and dimethyldiethoxysilane, an organosilicon structure is formed among the three, which can appropriately increase the crosslinking degree of the material, significantly improving the impact resistance and toughness of the transfer film. Additionally, adding a lignin structure to the molecular chain segments can further enhance the mechanical properties. Meanwhile, a hydrophobic protective film is formed on the surface of the transfer film, and the long-chain alkyl groups have a hydrophobic effect, further improving the water resistance of the transfer film. Specific Embodiments

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Apparently, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. Embodiment

[0023] A preparation method of a PI transfer film for graphite rolling specifically includes the following steps:

[0024] Step A1: Mix 4,4'-diaminodiphenyl ether, a modified monomer, 3,3',4,4'-biphenyltetracarboxylic dianhydride, and N,N-dimethylacetamide, introduce nitrogen for protection, and react for 3 h under the conditions of a rotation speed of 200 r / min and a temperature of 25 °C to obtain a polyamic acid solution. Dissolve lignin in DMF, stir and add dibutyltin dilaurate and isocyanatopropyltrimethoxysilane under the conditions of a rotation speed of 120 r / min and a temperature of 30 °C, and react for 2 h to obtain modified lignin;

[0025] Step A2: Mix the polyamic acid solution, modified lignin, dimethyldiethoxysilane, and DMF evenly, stir and add deionized water and hydrochloric acid solution under the conditions of a rotation speed of 200 r / min and a temperature of 65 °C, and react for 3 h to obtain a casting solution. Perform film scraping treatment, keep warm at 120 °C for 3 h, raise the temperature to 250 °C, keep warm for 15 min, raise the temperature to 340 °C, and keep warm for 10 min to obtain a PI transfer film.

[0026] The dosage ratio of 4,4'-diaminodiphenyl ether, the modified monomer, 3,3',4,4'-biphenyltetracarboxylic dianhydride, and N,N-dimethylacetamide described in Step A1 is 200 mmol:50 mol:150 mL:400 mL, the dosage ratio of lignin and isocyanatopropyltrimethoxysilane is 1 g:1 mL, and the dosage of dibutyltin dilaurate is 1% of the mass of isocyanatopropyltrimethoxysilane.

[0027] The dosage ratio of the polyamic acid solution, modified lignin, dimethyldiethoxysilane, DMF, deionized water, and hydrochloric acid solution described in Step A2 is 500 mL:3 g:10 mL:20 mL:40 mL:5 mL, and the mass fraction of the hydrochloric acid solution is 10%.

[0028] The described modified monomer is prepared by the following steps:

[0029] Step B1: Mix cetyltrimethoxysilane, sodium hydroxide, isopropyl alcohol, and deionized water evenly, and react for 10 h under the conditions of a rotation speed of 120 r / min and a temperature of 85 °C to obtain sodium cetylcyclotetrasiloxanetetrasilanol. Mix sodium cetylcyclotetrasiloxanetetrasilanol, triethylamine, and tetrahydrofuran evenly, introduce nitrogen for protection, stir and add methyldichlorosilane under the conditions of a rotation speed of 150 r / min and a temperature of 0 °C, react for 3 h, and raise the temperature to 20 °C and react for 20 h to obtain dihydroxycage-like silsesquioxane;

[0030] Step B2: Mix dihydrocage silsesquioxane, caffeic acid, Cast catalyst, and DMF evenly, introduce nitrogen for protection, and react for 20 h under the conditions of a rotation speed of 60 r / min and a temperature of 80 °C to obtain Intermediate 1. Mix Intermediate 1, p-nitrophenylboronic acid, 5A molecular sieve, and DMF evenly, introduce nitrogen for protection, and react for 10 h under the conditions of a rotation speed of 120 r / min and a temperature of 60 °C to obtain Intermediate 2;

[0031] Step B3: Mix Intermediate 2, KH550, dicyclohexylcarbodiimide, toluene, and DMF evenly, and react for 3 h under the conditions of a rotation speed of 200 r / min and a temperature of 30 °C to obtain Intermediate 3. Mix 4-hydroxyphthalonitrile, potassium carbonate, and DMF evenly, introduce nitrogen for protection, and react for 1 h under the conditions of a rotation speed of 150 r / min and a temperature of 20 °C. Then add Intermediate 3 and continue to react for 20 h to obtain Intermediate 4;

[0032] Step B4: Mix Intermediate 4, sodium hydroxide, and DMF evenly, introduce nitrogen for protection, and react for 10 h under the condition of a temperature of 90 °C. Then raise the temperature to 100 °C and continue to react for 25 °C to obtain Intermediate 5. Mix Intermediate 5, acetic anhydride, and glacial acetic acid evenly, introduce nitrogen for protection, and react for 10 h under the conditions of a rotation speed of 60 r / min and a temperature of 100 °C to obtain the modified monomer.

[0033] The dosage ratios of cetyltrimethoxysilane, sodium hydroxide, isopropanol, and deionized water described in Step B1 are 150 mmol: 80 mmol: 120 mL: 5 mL, and the dosage ratios of cetylcyclotetrasiloxane tetrasilanolate, triethylamine, tetrahydrofuran, and methyldichlorosilane are 20 g: 5 g: 30 mL: 4 g.

[0034] The molar ratio of dihydrocage silsesquioxane to caffeic acid described in Step B2 is 1:2, the dosage of Cast catalyst is 2‰ of the mass of caffeic acid, and the dosage ratios of Intermediate 1, p-nitrophenylboronic acid, and 5A molecular sieve are 16 mmol: 8 mmol: 2 g.

[0035] The molar ratio of Intermediate 2, KH550, and dicyclohexylcarbodiimide described in Step B3 is 1:2:2.1, and the molar ratio of 4-hydroxyphthalonitrile, potassium carbonate, and Intermediate 3 is 2:1:1.

[0036] The dosage ratios of Intermediate 4, sodium hydroxide, and DMF described in Step B4 are 1 mmol: 5 mmol: 2 mL, and the dosage ratios of Intermediate 5, acetic anhydride, and glacial acetic acid are 10 mmol: 1 mL: 2 mL. Example

[0037] A preparation method of a PI transfer film for graphite rolling, specifically including the following steps:

[0038] Step A1: Mix 4,4'-diaminodiphenyl ether, a modified monomer, 3,3',4,4'-biphenyltetracarboxylic dianhydride, and N,N-dimethylacetamide, introduce nitrogen protection, and react for 4 h under the conditions of a rotation speed of 200 r / min and a temperature of 30 °C to obtain a polyamic acid solution. Dissolve lignin in DMF, stir and add dibutyltin dilaurate and isocyanatopropyltrimethoxysilane under the conditions of a rotation speed of 120 r / min and a temperature of 35 °C, and react for 3 h to obtain modified lignin;

[0039] Step A2: Mix the polyamic acid solution, modified lignin, dimethyldiethoxysilane, and DMF evenly, stir and add deionized water and hydrochloric acid solution under the conditions of a rotation speed of 200 r / min and a temperature of 70 °C, and react for 4 h to obtain a casting solution. Perform film scraping treatment, keep warm at 125 °C for 4 h, raise the temperature to 255 °C, keep warm for 20 min, raise the temperature to 345 °C, and keep warm for 15 min to obtain a PI transfer film.

[0040] The dosage ratio of 4,4'-diaminodiphenyl ether, the modified monomer, 3,3',4,4'-biphenyltetracarboxylic dianhydride, and N,N-dimethylacetamide described in Step A1 is 200 mmol:50 mol:150 mL:400 mL, and the dosage ratio of lignin and isocyanatopropyltrimethoxysilane is 1 g:1 mL, and the dosage of dibutyltin dilaurate is 1% of the mass of isocyanatopropyltrimethoxysilane.

[0041] The dosage ratio of the polyamic acid solution, modified lignin, dimethyldiethoxysilane, DMF, deionized water, and hydrochloric acid solution described in Step A2 is 500 mL:3 g:10 mL:20 mL:40 mL:5 mL, and the mass fraction of the hydrochloric acid solution is 10%.

[0042] The modified monomer is prepared by the following steps:

[0043] Step B1: Mix cetyltrimethoxysilane, sodium hydroxide, isopropyl alcohol, and deionized water evenly, and react for 10 h under the conditions of a rotation speed of 120 r / min and a temperature of 90 °C to obtain sodium hexadecylcyclotetrasiloxanetetrol. Mix sodium hexadecylcyclotetrasiloxanetetrol, triethylamine, and tetrahydrofuran evenly, introduce nitrogen protection, stir and add methyldichlorosilane under the conditions of a rotation speed of 200 r / min and a temperature of 0 °C, and react for 4 h, then raise the temperature to 25 °C and react for 20 h to obtain dihydroxycage-like silsesquioxane;

[0044] Step B2: Mix dihydrocage silsesquioxane, caffeic acid, Cast catalyst, and DMF evenly, introduce nitrogen for protection, and react for 20 h under the conditions of a rotation speed of 60 r / min and a temperature of 85 °C to obtain Intermediate 1. Mix Intermediate 1, p-nitrophenylboronic acid, 5A molecular sieve, and DMF evenly, introduce nitrogen for protection, and react for 15 h under the conditions of a rotation speed of 150 r / min and a temperature of 60 °C to obtain Intermediate 2;

[0045] Step B3: Mix Intermediate 2, KH550, dicyclohexylcarbodiimide, toluene, and DMF evenly, and react for 4 h under the conditions of a rotation speed of 200 r / min and a temperature of 35 °C to obtain Intermediate 3. Mix 4-hydroxyphthalonitrile, potassium carbonate, and DMF evenly, introduce nitrogen for protection, and react for 1.5 h under the conditions of a rotation speed of 150 r / min and a temperature of 25 °C. Then add Intermediate 3 and continue to react for 20 h to obtain Intermediate 4;

[0046] Step B4: Mix Intermediate 4, sodium hydroxide, and DMF evenly, introduce nitrogen for protection, and react for 15 h under the condition of a temperature of 90 °C. Then raise the temperature to 105 °C and continue to react for 30 h to obtain Intermediate 5. Mix Intermediate 5, acetic anhydride, and glacial acetic acid evenly, introduce nitrogen for protection, and react for 15 h under the conditions of a rotation speed of 60 r / min and a temperature of 100 °C to obtain the modified monomer.

[0047] The dosage ratios of cetyltrimethoxysilane, sodium hydroxide, isopropanol, and deionized water described in Step B1 are 150 mmol: 80 mmol: 120 mL: 5 mL, and the dosage ratios of cetylcyclotetrasiloxane tetrasilanolate, triethylamine, tetrahydrofuran, and methyldichlorosilane are 20 g: 5 g: 30 mL: 4 g.

[0048] The molar ratio of dihydrocage silsesquioxane and caffeic acid described in Step B2 is 1:2, the dosage of Cast catalyst is 2‰ of the mass of caffeic acid, and the dosage ratios of Intermediate 1, p-nitrophenylboronic acid, and 5A molecular sieve are 16 mmol: 8 mmol: 2 g.

[0049] The molar ratio of Intermediate 2, KH550, and dicyclohexylcarbodiimide described in Step B3 is 1:2:2.1, and the molar ratio of 4-hydroxyphthalonitrile, potassium carbonate, and Intermediate 3 is 2:1:1.

[0050] The dosage ratios of Intermediate 4, sodium hydroxide, and DMF described in Step B4 are 1 mmol: 5 mmol: 2 mL, and the dosage ratios of Intermediate 5, acetic anhydride, and glacial acetic acid are 10 mmol: 1 mL: 2 mL. Example

[0051] A preparation method of a PI transfer film for graphite rolling, specifically including the following steps:

[0052] Step A1: Mix 4,4'-diaminodiphenyl ether, a modified monomer, 3,3',4,4'-biphenyltetracarboxylic dianhydride and N,N-dimethylacetamide, introduce nitrogen protection, and react at a rotation speed of 300 r / min and a temperature of 30 °C for 5 h to obtain a polyamic acid solution. Dissolve lignin in DMF, stir and add dibutyltin dilaurate and isocyanatopropyltrimethoxysilane at a rotation speed of 150 r / min and a temperature of 40 °C, and react for 3 h to obtain modified lignin;

[0053] Step A2: Mix the polyamic acid solution, modified lignin, dimethyldiethoxysilane and DMF evenly, stir and add deionized water and hydrochloric acid solution at a rotation speed of 300 r / min and a temperature of 70 °C, and react for 5 h to obtain a casting solution. Perform film scraping treatment, keep warm at a temperature of 130 °C for 5 h, raise the temperature to 260 °C, keep warm for 20 min, raise the temperature to 350 °C, and keep warm for 15 min to obtain a PI transfer film.

[0054] The dosage ratio of 4,4'-diaminodiphenyl ether, the modified monomer, 3,3',4,4'-biphenyltetracarboxylic dianhydride and N,N-dimethylacetamide described in Step A1 is 200 mmol:50 mol:150 mL:400 mL, and the dosage ratio of lignin and isocyanatopropyltrimethoxysilane is 1 g:1 mL. The dosage of dibutyltin dilaurate is 1% of the mass of isocyanatopropyltrimethoxysilane.

[0055] The dosage ratio of the polyamic acid solution, modified lignin, dimethyldiethoxysilane, DMF, deionized water and hydrochloric acid solution described in Step A2 is 500 mL:3 g:10 mL:20 mL:40 mL:5 mL, and the mass fraction of the hydrochloric acid solution is 10%.

[0056] The modified monomer is prepared by the following steps:

[0057] Step B1: Mix cetyltrimethoxysilane, sodium hydroxide, isopropyl alcohol and deionized water evenly, and react at a rotation speed of 150 r / min and a temperature of 90 °C for 15 h to obtain sodium cetylcyclotetrasiloxanetetrol. Mix sodium cetylcyclotetrasiloxanetetrol, triethylamine and tetrahydrofuran evenly, introduce nitrogen protection, stir and add methyldichlorosilane at a rotation speed of 200 r / min and a temperature of 0 °C, react for 5 h, and raise the temperature to 25 °C and react for 25 h to obtain dihydridosilsesquioxane;

[0058] Step B2: Mix dihydrocage silsesquioxane, caffeic acid, Caster catalyst, and DMF evenly, and introduce nitrogen for protection. React for 25 h under the conditions of a rotation speed of 80 r / min and a temperature of 85 °C to obtain Intermediate 1. Mix Intermediate 1, 4-nitrophenylboronic acid, 5A molecular sieve, and DMF evenly, introduce nitrogen for protection, and react for 15 h under the conditions of a rotation speed of 150 r / min and a temperature of 65 °C to obtain Intermediate 2;

[0059] Step B3: Mix Intermediate 2, KH550, dicyclohexylcarbodiimide, toluene, and DMF evenly, and react for 5 h under the conditions of a rotation speed of 300 r / min and a temperature of 40 °C to obtain Intermediate 3. Mix 4-hydroxyphthalonitrile, potassium carbonate, and DMF evenly, introduce nitrogen for protection, and react for 1.5 h under the conditions of a rotation speed of 200 r / min and a temperature of 25 °C. Then add Intermediate 3 and continue to react for 25 h to obtain Intermediate 4;

[0060] Step B4: Mix Intermediate 4, sodium hydroxide, and DMF evenly, introduce nitrogen for protection, and react for 15 h under the condition of a temperature of 95 °C. Raise the temperature to 110 °C and continue to react for 30 h to obtain Intermediate 5. Mix Intermediate 5, acetic anhydride, and glacial acetic acid evenly, introduce nitrogen for protection, and react for 15 h under the conditions of a rotation speed of 80 r / min and a temperature of 105 °C to obtain the modified monomer.

[0061] The dosage ratios of cetyltrimethoxysilane, sodium hydroxide, isopropanol, and deionized water described in Step B1 are 150 mmol: 80 mmol: 120 mL: 5 mL, and the dosage ratios of sodium hexadecylcyclotetrasiloxanetetrasilanolate, triethylamine, tetrahydrofuran, and methyldichlorosilane are 20 g: 5 g: 30 mL: 4 g.

[0062] The molar ratio of dihydrocage silsesquioxane to caffeic acid described in Step B2 is 1:2, the dosage of Caster catalyst is 2‰ of the mass of caffeic acid, and the dosage ratios of Intermediate 1, 4-nitrophenylboronic acid, and 5A molecular sieve are 16 mmol: 8 mmol: 2 g.

[0063] The molar ratio of Intermediate 2, KH550, and dicyclohexylcarbodiimide described in Step B3 is 1:2:2.1, and the molar ratio of 4-hydroxyphthalonitrile, potassium carbonate, and Intermediate 3 is 2:1:1.

[0064] The dosage ratios of Intermediate 4, sodium hydroxide, and DMF described in Step B4 are 1 mmol: 5 mmol: 2 mL, and the dosage ratios of Intermediate 5, acetic anhydride, and glacial acetic acid are 10 mmol: 1 mL: 2 mL.

[0065] Comparative Example 1

[0066] In this comparative example, compared with Example 1, no modified monomer was added, and the remaining steps were the same.

[0067] Comparative Example 2

[0068] In this comparative example, compared with Example 1, lignin was used instead of modified lignin, and the remaining steps were the same.

[0069] Comparative Example 3

[0070] In this comparative example, compared with Example 1, the product prepared by using p-nitrostyrene instead of caffeic acid was used to replace Intermediate 3, and the remaining steps were the same.

[0071] Comparative Example 4

[0072] In this comparative example, compared with Example 1, 1,1'-biphenyl]-3,3',4,4'-tetrol was used to replace Intermediate 1, and the remaining steps were the same.

[0073] The transfer membranes prepared in Examples 1-3 and Comparative Examples 1-4 were made into specimens with a length of 12 cm, a width of 2 cm, and a thickness of 0.5 mm. The tensile strength of the film was measured with a universal tensile testing machine XLM. The specimens were immersed in water at a temperature of 25°C for 24 h and 72 h, and the tensile strength of the specimens was detected. The test results are shown in the following table.

[0074]

[0075] It can be seen from the above table that this application has good mechanical properties and good water resistance.

[0076] The above content is only an example and explanation of the concept of the present invention. Those skilled in the art of this technology make various modifications or supplements to the described specific embodiments or use similar methods to replace them. As long as they do not deviate from the concept of the invention or exceed the scope defined by this claim book, they should all belong to the protection scope of the present invention.

Claims

1. A method for preparing a PI transfer film for graphite calendering, characterized in that: Specifically, the method comprises the following steps: Step A1: mixing 4,4'-diaminodiphenyl ether, a modified monomer, 3,3',4,4'-biphenyltetracarboxylic acid dianhydride and N,N-dimethylacetamide, introducing nitrogen protection, reacting to obtain a polyamic acid solution, dissolving lignin in DMF, stirring, adding dibutyltin dilaurate and isocyanate propyltrimethoxysilane, reacting to obtain a modified lignin; Step A2: mixing and stirring the polyamic acid solution, modified lignin, dimethyldiethoxysilane and DMF, adding deionized water and hydrochloric acid solution, reacting to obtain a casting solution, performing a film scraping treatment, and maintaining the temperature at high temperature to obtain a PI transfer film; The modified monomer is prepared by the following steps: Step B1: Hexadecyltrimethoxysilane, sodium hydroxide, isopropanol and deionized water are mixed for reaction to obtain sodium hexadecylcyclotetrasiloxane tetrasilanolate, sodium hexadecylcyclotetrasiloxane tetrasilanolate, triethylamine and tetrahydrofuran are mixed evenly, nitrogen is introduced for protection, methyldichlorosilane is added for stirring and reaction is carried out to obtain dihydrogen cage-type silsesquioxane; Step B2: mixing dihydrogen cage silsesquioxane, caffeic acid, Custer catalyst and DMF uniformly, introducing nitrogen protection, and reacting to obtain intermediate 1; mixing intermediate 1, p-nitrophenylboric acid, 5A molecular sieve and DMF uniformly, introducing nitrogen protection, and reacting to obtain intermediate 2; Step B3: Intermediate 2, KH550, dicyclohexylcarbodiimide, toluene and DMF are mixed for reaction to obtain Intermediate 3, 4-hydroxyphthalonitrile, potassium carbonate and DMF are mixed evenly, nitrogen is introduced for protection, and the reaction is carried out, and Intermediate 3 is added and the reaction is continued to obtain Intermediate 4; Step B4: Intermediate 4, sodium hydroxide and DMF are mixed evenly, nitrogen is introduced to protect the reaction, and intermediate 5 is obtained. Intermediate 5, acetic anhydride and glacial acetic acid are mixed evenly, nitrogen is introduced to protect the reaction, and a modified monomer is obtained.

2. The method for preparing a PI transfer film for graphite calendering according to claim 1, characterized in that: The amount ratio of 4,4'-diaminodiphenyl ether, modified monomer, 3,3',4,4'-biphenyltetracarboxylic dianhydride and N,N-dimethylacetamide described in step A1 is 200mmol:50mol:150mL:400mL, and the amount ratio of lignin and isocyanatepropyltrimethoxysilane is 1g:1mL.

3. The method for preparing a PI transfer film for graphite calendering according to claim 1, characterized in that: The amount ratio of the polyamic acid solution, modified lignin, dimethyldiethoxysilane, DMF, deionized water and hydrochloric acid solution described in step A2 is 500mL:3g:10mL:20mL:40mL:5mL.

4. The method for preparing a PI transfer film for graphite calendering according to claim 1, characterized in that: The amount ratio of hexadecyltrimethoxysilane, sodium hydroxide, isopropanol and deionized water in step B1 is 150mmol:80mmol:120mL:5mL, and the amount ratio of hexadecylcyclotetrasiloxane sodium tetrasiloxide, triethylamine, tetrahydrofuran and methyldichlorosilane is 20g:5g:30mL:4g.

5. The method for preparing a PI transfer film for graphite calendering according to claim 1, characterized in that: The molar ratio of the dihydrogen cage silsesquioxane and caffeic acid in step B2 is 1:2, and the usage ratio of intermediate 1, p-nitrophenylboric acid and 5A molecular sieve is 16mmol:8mmol:2g.

6. The method for preparing a PI transfer film for graphite calendering according to claim 1, characterized in that: The molar ratio of intermediate 2, KH550 and dicyclohexylcarbodiimide in step B3 is 1:2:2.1, and the molar ratio of 4-hydroxyphthalonitrile, potassium carbonate and intermediate 3 is 2:1:

1.

7. The method for preparing a PI transfer film for graphite calendering according to claim 1, characterized in that: The usage ratio of intermediate 4, sodium hydroxide and DMF in step B4 is 1 mmol:5 mmol:2 mL, and the usage ratio of intermediate 5, acetic anhydride and glacial acetic acid is 10 mmol:1 mL:2 mL.

8. A PI transfer film for graphite calendering, characterized in that: Prepared according to any one of claims 1 to 7.

Images