CN116731364A - Preparation method of polyimide film - Google Patents

Preparation method of polyimide film Download PDF

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CN116731364A
CN116731364A CN202310894779.5A CN202310894779A CN116731364A CN 116731364 A CN116731364 A CN 116731364A CN 202310894779 A CN202310894779 A CN 202310894779A CN 116731364 A CN116731364 A CN 116731364A
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polyimide film
polyimide
stretching
film
solvent
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刘贺
于耀伟
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Guangdong Shuangla Zhizao Technology Co ltd
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Guangdong Shuangla Zhizao Technology Co ltd
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    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18Manufacture of films or sheets
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08GMACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G73/00Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
    • C08G73/06Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
    • C08G73/10Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
    • C08G73/1003Preparatory processes
    • C08G73/1007Preparatory processes from tetracarboxylic acids or derivatives and diamines
    • C08G73/1028Preparatory processes from tetracarboxylic acids or derivatives and diamines characterised by the process itself, e.g. steps, continuous
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08GMACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G73/00Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
    • C08G73/06Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
    • C08G73/10Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
    • C08G73/1067Wholly aromatic polyimides, i.e. having both tetracarboxylic and diamino moieties aromatically bound
    • C08G73/1071Wholly aromatic polyimides containing oxygen in the form of ether bonds in the main chain
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2379/00Characterised by the use of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen, or carbon only, not provided for in groups C08J2361/00 - C08J2377/00
    • C08J2379/04Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
    • C08J2379/08Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08KUse of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00Use of inorganic substances as compounding ingredients
    • C08K3/32Phosphorus-containing compounds
    • C08K2003/321Phosphates
    • C08K2003/325Calcium, strontium or barium phosphate

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  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Shaping By String And By Release Of Stress In Plastics And The Like (AREA)
  • Manufacture Of Macromolecular Shaped Articles (AREA)

Abstract

The invention discloses a preparation method of a polyimide film, and particularly relates to the technical field of film preparation. The preparation method of the polyimide film comprises the steps of (1) adding diamine monomer, dianhydride monomer and inorganic filler into a solvent, and polymerizing to obtain polyamide acid resin with solid content of 15-30% and viscosity of (20-35) ten thousand cp; (2) Uniformly mixing the polyamic acid resin obtained in the step (1), a catalyst and a dehydrating agent, casting to an annular steel belt, and heating to perform imidization reaction to obtain a polyimide adhesive film with imidization rate of 75-95%; (3) And (3) stripping the polyimide film obtained in the step (2), transversely stretching, baking at 250-800 ℃, rolling, and annealing at 250-400 ℃ to obtain the polyimide film, wherein the relation between the solvent content w and the thickness T (mum) of the polyimide film is 0.4 xT less than or equal to 100 xW less than or equal to 0.7 xT, and the T is 12.5-65. The polyimide film prepared by the invention has the characteristics of low thermal expansion coefficient and high dimensional stability.

Description

Preparation method of polyimide film
Technical Field
The invention relates to the technical field of film preparation, in particular to a preparation method of a polyimide film.
Background
As electronic devices become thinner and lighter, wiring of flexible circuit boards (FPCs) inside the electronic devices also tends to be high-density, so that higher performance requirements are also put forward on Polyimide (PI) films as substrates of the electronic devices, particularly in terms of thermodynamic performance of the PI films, for example, the thermal shrinkage rate of the PI films is less than or equal to 0.05%, the thermal expansion coefficient is less than or equal to 16ppm/°c, that is, the PI films are required to have a thermal expansion coefficient similar to that of a metal layer and higher dimensional stability at the same time, so as to reduce problems of peeling, warping and the like after compounding.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a polyimide film, which solves the problems that in the prior art, the processability is poor due to the excessively high imidization rate, and the molecular orientation of a finished film is poor due to the excessively low imidization rate, so that the performance of the film is affected; and the film performance is reduced due to the excessively high content of the film solvent, liquid spots are easy to generate on the surface of the film, and the film is easy to break due to the excessively low content of the film solvent, so that the processability is affected.
In order to solve the technical problems, the aim of the invention is realized by the following technical scheme:
a preparation method of a polyimide film comprises the following steps:
(1) Diamine monomer, dianhydride monomer and inorganic filler are added into a solvent, and polyamide acid resin with solid content of 15-30% and viscosity of (20-35) ten thousand cp is obtained after polymerization;
(2) Uniformly mixing the polyamic acid resin obtained in the step (1), a catalyst and a dehydrating agent, casting to an annular steel belt, and heating to perform imidization reaction to obtain a polyimide adhesive film with imidization rate of 75-95%;
(3) Stripping the polyimide film obtained in the step (2), transversely stretching, baking at 250-800 ℃, rolling, and annealing at 250-400 ℃ to obtain a polyimide film;
the relation between the solvent content w of the polyimide film and the thickness T (unit μm) of the polyimide film is 0.4 xT less than or equal to 100 xW less than or equal to 0.7 xT, and the range of T is 12.5-65.
Specifically, the preparation method of the polyimide film can be carried out according to the following steps:
(1) Sequentially adding diamine monomer, dianhydride monomer and inorganic filler into a solvent for polycondensation reaction, and obtaining polyamide acid resin with solid content of 15-30% and viscosity of (20-35) ten thousand cp after polymerization;
(2) Adopting a chemical imidization process, namely uniformly mixing the polyamide acid resin obtained in the step (1), a catalyst and a dehydrating agent, casting to an annular steel belt, and heating by hot air to carry out imidization reaction to obtain a polyimide adhesive film with imidization rate of 75-95%;
(3) And (3) stripping the polyimide film obtained in the step (2), transversely stretching the polyimide film, and baking at the temperature of 250-800 ℃ while transversely stretching the polyimide film, wherein the baking process is a process of heating and then cooling, and annealing at the temperature of 250-400 ℃ after rolling the polyimide film to obtain the polyimide film.
Preferably, in the step (1), the solid content of the polyamic acid resin is 18.5-28% and the viscosity is (25-30) ten thousand cp.
Preferably, in the step (1), the solvent is one or more of N, N '-dimethylformamide, N' -dimethylacetamide and N-methylpyrrolidone.
Preferably, in step (1), the diamine monomer is one or more of p-phenylenediamine, 4 '-diaminodiphenyl ether, 4' -diaminodiphenyl sulfone, 4 '-diaminodiphenyl ketone, and 3,4' -diaminodiphenyl ether.
Preferably, in the step (1), the inorganic filler is one or more of inorganic salt, oxide, nitride and carbide.
Preferably, in step (1), the molar ratio of diamine monomer to dianhydride monomer is 1 (0.8-1.2), more preferably the molar ratio is 1:1.
Preferably, in the step (1), the mass of the inorganic filler is 0.05 to 0.3% of the mass of the polyimide film in the step (3).
Preferably, in the step (2), the catalyst is one or more of pyridine, 2-picoline, 3-picoline and isoquinoline.
Preferably, in the step (2), the dehydrating agent is acetic anhydride and/or propionic anhydride.
Preferably, in the step (2), the imidization rate of the polyimide film is 80-90%.
Preferably, in the step (3), the stretching ratio of the transverse stretching is 1.008 to 1.090, more preferably, the stretching ratio is 1.01 to 1.07. More preferably, the stretching ratio of the transverse stretching is the stretching ratio at the maximum transverse stretching.
Preferably, in the step (3), after the polyimide film is peeled off, the polyimide film is transversely stretched by a needle plate or a chain clip.
Preferably, in the step (3), the thickness T of the polyimide film is in the range of 25 to 50.
The polyimide film with low thermal expansion coefficient and high dimensional stability is prepared by controlling the solvent content, imidization rate and the subsequent stretching rate at the maximum transverse stretching position of the polyimide film and combining a chemical imidization process.
Compared with the prior art, the invention realizes the following technical effects:
(1) By controlling the imidization rate of the polyimide adhesive film, the orientation degree of the polyimide polymer chain segment is effectively regulated and controlled, and the problems that the subsequent stretching process is difficult to carry out, the processability is poor, the imidization rate is too low, the molecular orientation degree of the adhesive film is insufficient, and the subsequent polymer chain segment lacks an oriented template, so that the molecular orientation of a finished film is poor, and the performance of the film is affected are solved.
(2) According to the thickness of different polyimide films, the solvent content of the polyimide film is regulated and controlled, so that the problems that the polyimide film performance is reduced due to the fact that the solvent content of the polyimide film is too high, liquid spots are easy to generate on the surface of the polyimide film, the solvent content of the polyimide film is too low, the polyimide film is easy to break in the subsequent stretching process, and the processability is affected are solved.
Detailed Description
The technical solutions of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It should be understood that the terms "comprises" and "comprising," when used in this specification and the appended claims, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
It is also to be understood that the terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in this specification and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
It should be further understood that the term "and/or" as used in the present specification and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes such combinations.
Example 1
(1) 200.2g of 4,4' -diaminodiphenyl ether, 218g of pyromellitic dianhydride and 1.0g of calcium hydrophosphate are sequentially added into 2.38kg of N, N-dimethylformamide, and the mixture is subjected to polycondensation reaction for 2 hours to obtain polyamide acid (PAA) resin, wherein the viscosity is 20 ten thousand cp, and the solid content is 15%;
(2) After vacuum defoamation, adding chemical imidizing reagent into PAA resin, specifically adding 204.2g of acetic anhydride and 25.8g of isoquinoline, uniformly mixing, casting to an annular steel belt through a die head, and heating by hot air to carry out imidization reaction to obtain polyimide adhesive film with the solvent content of 8% and the imidization rate of 80%;
(3) And (3) stripping the polyimide film obtained in the step (2), transversely stretching the polyimide film through a needle plate (or a chain clamp), wherein the stretching rate at the maximum transverse stretching position is 1.01, baking at 250-800 ℃ while transversely stretching, and annealing at 250-400 ℃ after winding to obtain the polyimide film with the thickness of 12.5 mu m.
Example 2
(1) 200.2g of 4,4' -diaminodiphenyl ether, 218g of pyromellitic dianhydride and 1.0g of calcium hydrophosphate are sequentially added into 1.68kg of N, N-dimethylformamide, and the mixture is subjected to polycondensation reaction for 2 hours to obtain polyamide acid (PAA) resin, wherein the viscosity is 25 ten thousand cp, and the solid content is 20%;
(2) After vacuum defoamation, adding chemical imidizing reagent into PAA resin, specifically adding 204.2g of acetic anhydride and 25.8g of isoquinoline, uniformly mixing, casting to an annular steel belt through a die head, and heating by hot air to carry out imidization reaction to obtain polyimide adhesive film with the solvent content of 8% and the imidization rate of 85%;
(3) And transversely stretching the polyimide film through a needle plate (or a chain clamp), wherein the stretching rate at the maximum transverse stretching position is 1.03, baking at 250-800 ℃ while transversely stretching, and annealing at 250-400 ℃ after rolling to obtain the polyimide film with the thickness of 12.5 mu m.
Example 3
(1) 200.2g of 4,4' -diaminodiphenyl ether, 218g of pyromellitic dianhydride and 1.0g of calcium hydrophosphate are sequentially added into 1.85kg of N, N-dimethylformamide, and the mixture is subjected to polycondensation reaction for 2 hours to obtain polyamide acid (PAA) resin, wherein the viscosity is 25 ten thousand cp, and the solid content is 18.5%;
(2) After vacuum defoamation, adding chemical imidizing reagent into PAA resin, specifically adding 204.2g of acetic anhydride and 25.8g of isoquinoline, uniformly mixing, casting to an annular steel belt through a die head, and heating by hot air to carry out imidization reaction to obtain polyimide adhesive film with the solvent content of 12% and the imidization rate of 75%;
(3) And (3) stripping the polyimide film obtained in the step (2), transversely stretching the polyimide film through a needle plate (or a chain clamp), wherein the stretching rate at the maximum transverse stretching position is 1.03, baking at 250-800 ℃ while transversely stretching, and annealing at 250-400 ℃ after winding to obtain the polyimide film with the thickness of 25 mu m.
Example 4
(1) 200.2g of 4,4' -diaminodiphenyl ether, 218g of pyromellitic dianhydride and 1.0g of calcium hydrophosphate are sequentially added into 0.98kg of N, N-dimethylformamide, and the mixture is subjected to polycondensation reaction for 2 hours to obtain polyamide acid (PAA) resin, wherein the viscosity is 35 ten thousand cp, and the solid content is 30%;
(2) After vacuum defoamation, adding chemical imidizing reagent into PAA resin, specifically adding 204.2g of acetic anhydride and 25.8g of isoquinoline, uniformly mixing, casting to an annular steel belt through a die head, and heating by hot air to carry out imidization reaction to obtain polyimide adhesive film with the solvent content of 15% and the imidization rate of 80%;
(3) And (3) stripping the polyimide film obtained in the step (2), transversely stretching the polyimide film through a needle plate (or a chain clamp), wherein the stretching rate at the maximum transverse stretching position is 1.05, baking at 250-800 ℃ while transversely stretching, and annealing at 250-400 ℃ after winding to obtain the polyimide film with the thickness of 25 mu m.
Example 5
(1) 200.2g of 4,4' -diaminodiphenyl ether, 218g of pyromellitic dianhydride and 1.0g of calcium hydrophosphate are sequentially added into 1.08kg of N, N-dimethylformamide, and the mixture is subjected to polycondensation reaction for 2 hours to obtain polyamide acid (PAA) resin, wherein the viscosity is 32 ten thousand cp, and the solid content is 28%;
(2) After vacuum defoamation, adding chemical imidizing reagent into PAA resin, specifically adding 204.2g of acetic anhydride and 25.8g of isoquinoline, uniformly mixing, casting to an annular steel belt through a die head, and heating by hot air to carry out imidization reaction to obtain polyimide adhesive film with the solvent content of 17% and the imidization rate of 90%;
(3) And (3) stripping the polyimide film obtained in the step (2), transversely stretching the polyimide film through a needle plate (or a chain clamp), wherein the stretching rate at the maximum transverse stretching position is 1.07, baking at 250-800 ℃ while transversely stretching, and annealing at 250-400 ℃ after winding to obtain the polyimide film with the thickness of 25 mu m.
Example 6
(1) 200.2g of 4,4' -diaminodiphenyl ether, 218g of pyromellitic dianhydride and 1.0g of calcium hydrophosphate are sequentially added into 1.68kg of N, N-dimethylformamide, and the mixture is subjected to polycondensation reaction for 2 hours to obtain polyamide acid (PAA) resin, wherein the viscosity is 28 ten thousand cp, and the solid content is 20%;
(2) After vacuum defoamation, adding chemical imidizing reagent into PAA resin, specifically adding 204.2g of acetic anhydride and 25.8g of isoquinoline, uniformly mixing, casting to an annular steel belt through a die head, and heating by hot air to carry out imidization reaction to obtain polyimide adhesive film with the solvent content of 30% and the imidization rate of 80%;
(3) And (3) stripping the polyimide film obtained in the step (2), transversely stretching the polyimide film through a needle plate (or a chain clamp), wherein the stretching rate at the maximum transverse stretching position is 1.05, baking at 250-800 ℃ while transversely stretching, and annealing at 250-400 ℃ after winding to obtain the polyimide film with the thickness of 50 mu m.
Example 7
(1) 200.2g of 4,4' -diaminodiphenyl ether, 218g of pyromellitic dianhydride and 1.0g of calcium hydrophosphate are sequentially added into 1.68kg of N, N-dimethylformamide, and the mixture is subjected to polycondensation reaction for 2 hours to obtain polyamide acid (PAA) resin, wherein the viscosity is 28 ten thousand cp, and the solid content is 20%;
(2) After vacuum defoamation, adding chemical imidizing reagent into PAA resin, specifically adding 204.2g of acetic anhydride and 25.8g of isoquinoline, uniformly mixing, casting to an annular steel belt through a die head, and heating by hot air to carry out imidization reaction to obtain polyimide adhesive film with the solvent content of 40% and the imidization rate of 80%;
(3) And (3) stripping the polyimide film obtained in the step (2), transversely stretching the polyimide film through a needle plate (or a chain clamp), wherein the stretching rate at the maximum transverse stretching position is 1.05, baking at 250-800 ℃ while transversely stretching, and annealing at 250-400 ℃ after winding to obtain the polyimide film with the thickness of 65 mu m.
Comparative example 1
(1) 200.2g of 4,4' -diaminodiphenyl ether, 218g of pyromellitic dianhydride and 1.0g of calcium hydrophosphate are sequentially added into 1.85kg of N, N-dimethylformamide, and the mixture is subjected to polycondensation reaction for 2 hours to obtain polyamide acid (PAA) resin, wherein the viscosity is 25 ten thousand cp, and the solid content is 18.5%;
(2) After vacuum defoamation, adding chemical imidizing reagent into PAA resin, specifically adding 204.2g of acetic anhydride and 25.8g of isoquinoline, uniformly mixing, casting to an annular steel belt through a die head, and heating by hot air to carry out imidization reaction to obtain polyimide adhesive film with the solvent content of 15% and the imidization rate of 50%;
(3) And (3) stripping the polyimide film obtained in the step (2), transversely stretching the polyimide film through a needle plate (or a chain clamp), wherein the stretching rate at the maximum transverse stretching position is 1.01, baking at 250-800 ℃ while transversely stretching, and annealing at 250-400 ℃ after winding to obtain the polyimide film with the thickness of 12.5 mu m.
Comparative example 2
(1) 200.2g of 4,4' -diaminodiphenyl ether, 218g of pyromellitic dianhydride and 1.0g of calcium hydrophosphate are sequentially added into 1.49kg of N, N-dimethylformamide, and the mixture is subjected to polycondensation reaction for 2 hours to obtain polyamide acid (PAA) resin, wherein the viscosity is 30 ten thousand cp, and the solid content is 22%;
(2) After vacuum defoamation, adding chemical imidizing reagent into PAA resin, specifically adding 204.2g of acetic anhydride and 25.8g of isoquinoline, uniformly mixing, casting to an annular steel belt through a die head, and heating by hot air to carry out imidization reaction to obtain polyimide adhesive film with the solvent content of 25% and the imidization rate of 60%;
(3) And (3) stripping the polyimide film obtained in the step (2), transversely stretching the polyimide film through a needle plate (or a chain clamp), wherein the stretching rate at the maximum transverse stretching position is 1.05, baking at 250-800 ℃ while transversely stretching, and annealing at 250-400 ℃ after winding to obtain the polyimide film with the thickness of 25 mu m.
Comparative example 3
(1) 200.2g of 4,4' -diaminodiphenyl ether, 218g of pyromellitic dianhydride and 1.0g of calcium hydrophosphate are sequentially added into 1.68kg of N, N-dimethylformamide, and the mixture is subjected to polycondensation reaction for 2 hours to obtain polyamide acid (PAA) resin, wherein the viscosity is 28 ten thousand cp, and the solid content is 20%;
(2) After vacuum defoamation, adding chemical imidizing reagent into PAA resin, specifically adding 204.2g of acetic anhydride and 25.8g of isoquinoline, uniformly mixing, casting to an annular steel belt through a die head, and heating by hot air to carry out imidization reaction to obtain polyimide adhesive film with the solvent content of 40% and the imidization rate of 65%;
(3) And (3) stripping the polyimide film obtained in the step (2), transversely stretching the polyimide film through a needle plate (or a chain clamp), wherein the stretching rate at the maximum transverse stretching position is 1.05, baking at 250-800 ℃ while transversely stretching, and annealing at 250-400 ℃ after winding to obtain the polyimide film with the thickness of 50 mu m.
Comparative example 4
(1) 200.2g of 4,4' -diaminodiphenyl ether, 218g of pyromellitic dianhydride and 1.0g of calcium hydrophosphate are sequentially added into 1.08kg of N, N-dimethylformamide, and the mixture is subjected to polycondensation reaction for 2 hours to obtain polyamide acid (PAA) resin, wherein the viscosity is 32 ten thousand cp, and the solid content is 28%;
(2) After vacuum defoamation, adding chemical imidizing reagent into PAA resin, specifically adding 204.2g of acetic anhydride and 25.8g of isoquinoline, uniformly mixing, casting to an annular steel belt through a die head, and heating by hot air to carry out imidization reaction to obtain polyimide adhesive film with the solvent content of 17% and the imidization rate of 96%;
and (3) peeling the polyimide film obtained in the step (2), transversely stretching the polyimide film by a needle plate (or a chain clamp), wherein the stretching rate at the maximum transverse stretching position is 1.02, and baking at 250-800 ℃ while transversely stretching to prepare a film with the thickness of 25 mu m, wherein the edge of the film is broken at the maximum stretching position and cannot be rolled.
Comparative example 5
(1) 200.2g of 4,4' -diaminodiphenyl ether, 218g of pyromellitic dianhydride and 1.0g of calcium hydrophosphate are sequentially added into 2.38kg of N, N-dimethylformamide, and the mixture is subjected to polycondensation reaction for 2 hours to obtain polyamide acid (PAA) resin, wherein the viscosity is 20 ten thousand cp, and the solid content is 15%;
(2) After vacuum defoamation, adding chemical imidizing reagent into PAA resin, specifically adding 204.2g of acetic anhydride and 25.8g of isoquinoline, uniformly mixing, casting to an annular steel belt through a die head, and heating by hot air to carry out imidization reaction to obtain polyimide adhesive film with the solvent content of 4% and the imidization rate of 80%;
(3) And (3) peeling the polyimide film obtained in the step (2), transversely stretching the polyimide film by a needle plate (or a chain clamp), wherein the stretching rate at the maximum transverse stretching position is 1.01, and baking at 250-800 ℃ while transversely stretching to prepare a film with the thickness of 12.5 mu m, wherein the edge of the film breaks during transverse stretching and cannot be rolled.
The polyamide acid (PAA) resins of examples 1 to 7 and comparative examples 1 to 5 were examined for solid content, viscosity, solvent content, imidization rate, elongation, thickness, thermal expansion coefficient, and thermal shrinkage rate of the polyimide film, and the test methods were as follows.
(1) Polyimide film imidization rate test
Characterization of the imidization rate (ID) of the adhesive film using an infrared spectrum analyzer, the formula:
wherein S1 and S2 are peak areas of the adhesive film at 725cm < -1 > and 1500cm < -1 >, respectively, and S1 'and S2' are peak areas of the adhesive film at 725cm < -1 > and 1500cm < -1 > after the adhesive film is heated by an oven at 450 ℃ for 15 minutes.
(2) Polyimide film solvent content (w) test
The mass w1 of the polyimide film is heated in an oven at 450 ℃ for 20 minutes to obtain dry film mass w2, w= (w 1-w 2)/w 1.
Stretch ratio calculation
Stretch ratio = L1/L2, L1 being the maximum stretch breadth and L2 being the breadth just above the pin (or chain clip).
Coefficient of thermal expansion (CET) test
The film was tested for coefficient of thermal expansion using a relaxation-resistant TMA4000SE test standard ASTM D-696-91.
Thermal shrinkage test
The test standard is ASTM D-5214-91.
The polyamide acid (PAA) resins of examples 1 to 7 and comparative examples 1 to 5 were tested for their solids content, viscosity, solvent content, imidization rate, elongation, and thickness, coefficient of thermal expansion, and thermal shrinkage of polyimide films by the above test methods, and the results are shown in table 1 below.
TABLE 1 results of Performance test for examples 1-7 and comparative examples 1-5
While the invention has been described with reference to certain preferred embodiments, it will be understood by those skilled in the art that various changes and substitutions of equivalents may be made and equivalents will be apparent to those skilled in the art without departing from the scope of the invention. Therefore, the protection scope of the invention is subject to the protection scope of the claims.

Claims (10)

1. The preparation method of the polyimide film is characterized by comprising the following steps of:
(1) Diamine monomer, dianhydride monomer and inorganic filler are added into a solvent, and polyamide acid resin with solid content of 15-30% and viscosity of (20-35) ten thousand cp is obtained after polymerization;
(2) Uniformly mixing the polyamic acid resin obtained in the step (1), a catalyst and a dehydrating agent, casting to an annular steel belt, and heating to perform imidization reaction to obtain a polyimide adhesive film with imidization rate of 75-95%;
(3) Stripping the polyimide film obtained in the step (2), transversely stretching, baking at 250-800 ℃, rolling, and annealing at 250-400 ℃ to obtain a polyimide film;
the relation between the solvent content w of the polyimide film and the thickness T (unit μm) of the polyimide film is 0.4 xT less than or equal to 100 xW less than or equal to 0.7 xT, and the range of T is 12.5-65.
2. The method for producing a polyimide film according to claim 1, wherein in the step (1), the solvent is one or more of N, N '-dimethylformamide, N' -dimethylacetamide and N-methylpyrrolidone.
3. The method of claim 2, wherein in the step (1), the diamine monomer is one or more of p-phenylenediamine, 4 '-diaminodiphenyl ether, 4' -diaminodiphenyl sulfone, 4 '-diaminodiphenyl ketone, and 3,4' -diaminodiphenyl ether.
4. The method of claim 3, wherein in the step (1), the inorganic filler is one or more of inorganic salt, oxide, nitride and carbide.
5. The method of producing a polyimide film according to claim 4, wherein in the step (1), the molar ratio of the diamine monomer to the dianhydride monomer is 1 (0.8 to 1.2).
6. The method of producing a polyimide film according to claim 4, wherein in the step (1), the mass of the inorganic filler is 0.05 to 0.3% of the mass of the polyimide film in the step 3.
7. The method of claim 5, wherein in step (2), the catalyst is one or more of pyridine, 2-picoline, 3-picoline, and isoquinoline.
8. The method according to claim 6, wherein in the step (2), the dehydrating agent is acetic anhydride and/or propionic anhydride.
9. The method of claim 8, wherein in the step (3), the stretching ratio of the transverse stretching is 1.008 to 1.090.
10. The method of producing a polyimide film according to claim 9, wherein in the step (3), the thickness T of the polyimide film is in the range of 25 to 50.
CN202310894779.5A 2023-07-20 2023-07-20 Preparation method of polyimide film Pending CN116731364A (en)

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