Preparation method of edge-tear-resistant polyimide film

Abstract

The invention relates to a preparation method of a polyimide film with a tear-resistant edge, which sequentially comprises the following steps: A, preparing polyamic acid resin, namely sequentially adding a diamine monomer and a dianhydride monomer into a solvent, and carrying out condensation polymerization to generate the polyamic acid resin; b, casting the obtained polyamide acid resin to a steel belt, and removing part of the solvent to obtain a polyimide adhesive film; and C, stripping the polyimide adhesive film, putting the polyimide adhesive film into a needle plate or a chain clamp, fixing two sides of the polyimide adhesive film, transversely stretching the polyimide adhesive film, heating the polyimide adhesive film, and finally cutting the polyimide adhesive film to obtain the polyimide film. The polyimide film can be prepared in a high-speed state, the preparation method is simple, the quality of the film reaches the standard under the condition of high production speed, the edge of the film is not torn, the production efficiency is greatly improved, and higher economic benefits are brought.

Description

Technical Field

[0001] The invention relates to a method for preparing a polyimide film, in particular to a method for preparing a polyimide film with tear-resistant edges. Background Art

[0002] Polyimide (PI) film has excellent mechanical, electrical insulation and thermal stability, and is widely used in microelectronics, rail transportation, aerospace and other fields. In the production and processing of PI film, transverse stretching is an indispensable step to improve its performance. As the thickness and width of PI film continue to increase, the force on the edge of the film during the transverse stretching process increases. At the same time, as the production speed continues to increase, the heating time of the film in the drying oven is shortened, the degree of imidization decreases, and the mechanical strength of the edge is also reduced, resulting in more and more cracks or even breaks on the edge of the PI film, which seriously affects production efficiency. Summary of the invention

[0003] The main purpose of the present invention is to provide a method for preparing a polyimide film with tear-resistant edges.

[0004] The technical means adopted by the present invention are as follows: A method for preparing a polyimide film with tear-resistant edges of the present invention comprises the following steps in sequence: A. preparing a polyamic acid resin, adding a diamine monomer and a dianhydride monomer in a solvent in sequence, and generating a polyamic acid resin after a polycondensation reaction; B. Casting the obtained polyamic acid (PAA) resin onto a steel belt, and removing part of the solvent to obtain a PI film; the solvent removal ratio here can be selected differently according to the thickness of the film, which is a conventional choice of ordinary technicians in this field and will not be repeated here.

[0005] C. After the polyimide (PI) film is peeled off, it is inserted into a needle plate or a chain clamp, fixed on both sides, stretched horizontally and heated, and finally cut to obtain a polyimide (PI) film.

[0006] The solvent is one or more of N,N'-dimethylformamide, N,N'-dimethylacetamide and N-methylpyrrolidone.

[0007] The diamine monomer is an aromatic diamine, preferably at least one of p-phenylenediamine, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminobenzophenone and 3,4'-diaminodiphenyl ether; the dianhydride monomer is an aromatic dianhydride, preferably at least one of pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride and 3,3',4,4'-benzophenone tetracarboxylic dianhydride.

[0008] The molar ratio of the diamine monomer to the dianhydride monomer is 1:(0.8-1.2), preferably 1:1, and the ratio of the molar number of the rigid diamine monomer to the total molar number of the diamine monomer is ≥30%, or the ratio of the molar number of the rigid dianhydride monomer to the total molar number of the dianhydride monomer is ≥30%. The rigid diamine monomer is preferably p-phenylenediamine, and the rigid dianhydride monomer is preferably pyromellitic dianhydride.

[0009] The solid content of the polyamic acid resin is set to be 15-30% by mass, preferably 18-25% by mass, and the viscosity is 100,000-400,000 CP, preferably 200,000-300,000 CP.

[0010] After peeling, the edge positions on both sides of the needle plate or chain clip have an edge width of 1 to 5 cm, and their maximum thickness is 20% to 40% thicker than the central position, and the edge portion is finally cut off.

[0011] The imidization agent is added to the edge position, and the adding method includes but is not limited to spraying, coating and the like. The imidization agent components include an organic anhydride dehydrating agent, an organic base catalyst and the same solvent as the PAA resin, wherein the organic anhydride dehydrating agent includes one of acetic anhydride, propionic anhydride, butyric anhydride, benzoic anhydride, maleic anhydride or a mixture thereof in any proportion; the organic base catalyst includes one of isoquinoline, pyridine, 2-methylpyridine, 3-methylpyridine or a mixture thereof in any proportion; wherein the molar ratio of the organic anhydride dehydrating agent to the organic base catalyst is 1:1 to 10:1, preferably 3:1 to 8:1. The mass fraction of the imidization agent, i.e., m (organic anhydride dehydrating agent + organic base catalyst) / m 总 (organic anhydride dehydrating agent + organic base catalyst + solvent), is 40% to 70%, and the rate of adding the imidization agent at the edges on both sides is the same, which is 3 to 15 kg / h, preferably 5 to 13 kg / h.

[0012] A plasticizer is added to the PAA resin. The plasticizer is one of triisopropylphenyl phosphate, triphenyl phosphate and resorcinol tetraphenyl diphosphate, preferably resorcinol tetraphenyl diphosphate, and the added amount is 1 to 10% of the total mass of the diamine monomer and the dianhydride monomer, preferably 3 to 8%.

[0013] The film is stretched to the maximum width and enters the highest temperature section oven. The heating temperature of the highest temperature section oven reaches 600-800°C, preferably 650-750°C, and the heating method is hot air, electric heating pipe or ceramic heating plate, preferably ceramic heating plate. The length of the highest temperature section oven is 2-6 meters, and supplementary heating is applied to the edge of the film in the highest temperature section oven. The difference between the heating temperature and the surface temperature of the thin surface is within ±10°C. The production speed of this solution is 10-30m / min, preferably 13-20m / min.

[0014] The beneficial effects of the present invention are: the polyimide film can be prepared at high speed, the preparation method is simple, and the film quality meets the standard under high production speed without tearing, which greatly improves the production efficiency and brings higher economic benefits. DETAILED DESCRIPTION

[0015] The invention discloses a method for preparing a polyimide film with tear-resistant edges, which comprises the following steps in sequence: A. preparing a polyamic acid resin, adding a diamine monomer and a dianhydride monomer in a solvent in sequence, and generating a polyamic acid resin after a polycondensation reaction; B. Casting the obtained polyamic acid (PPA) resin onto a steel belt, and removing part of the solvent to obtain a polyimide (PI) film; C. After the PI film is peeled off, it is inserted into a needle plate or a chain clamp, fixed on both sides, stretched horizontally and heated, and finally cut to obtain a PI film.

[0016] The solvent is one or more of N,N'-dimethylformamide, N,N'-dimethylacetamide and N-methylpyrrolidone.

[0017] The diamine monomer is an aromatic diamine, preferably at least one of p-phenylenediamine, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminobenzophenone and 3,4'-diaminodiphenyl ether; the dianhydride monomer is an aromatic dianhydride, preferably at least one of pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride and 3,3',4,4'-benzophenone tetracarboxylic dianhydride.

[0018] The molar ratio of the diamine monomer to the dianhydride monomer is 1:(0.8-1.2), preferably 1:1, and the ratio of the molar number of the rigid diamine monomer to the total molar number of the diamine monomer is ≥30%, or the ratio of the molar number of the rigid dianhydride monomer to the total molar number of the dianhydride monomer is ≥30%. The rigid diamine monomer is preferably p-phenylenediamine, and the rigid dianhydride monomer is preferably pyromellitic dianhydride.

[0019] The solid content of the polyamic acid resin is set to be 15-30% by mass, preferably 18-25% by mass, and the viscosity is 100,000-400,000 CP, preferably 200,000-300,000 CP.

[0020] After peeling, the edge positions on both sides of the needle plate or chain clip have an edge width of 1 to 5 cm, and their maximum thickness is 20% to 40% thicker than the central position, and the edge portion is finally cut off.

[0021] The imidization agent is added to the edge position, and the adding method includes but is not limited to spraying, coating and the like. The imidization agent components include an organic anhydride dehydrating agent, an organic base catalyst and the same solvent as the PAA resin, wherein the organic anhydride dehydrating agent includes one of acetic anhydride, propionic anhydride, butyric anhydride, benzoic anhydride, maleic anhydride or a mixture thereof in any proportion; the organic base catalyst includes one of isoquinoline, pyridine, 2-methylpyridine, 3-methylpyridine or a mixture thereof in any proportion; wherein the molar ratio of the organic anhydride dehydrating agent to the organic base catalyst is 1:1 to 10:1, preferably 3:1 to 8:1. The mass fraction of the imidization agent, i.e., m (organic anhydride dehydrating agent + organic base catalyst) / m 总 (organic anhydride dehydrating agent + organic base catalyst + solvent), is 40% to 70%, and the rate of adding the imidization agent at the edges on both sides is the same, which is 3 to 15 kg / h, preferably 5 to 13 kg / h.

[0022] A plasticizer is added to the PAA resin. The plasticizer is one of triisopropylphenyl phosphate, triphenyl phosphate and resorcinol tetraphenyl diphosphate, preferably resorcinol tetraphenyl diphosphate, and the added amount is 1 to 10% of the total mass of the diamine monomer and the dianhydride monomer, preferably 3 to 8%.

[0023] The film is stretched to the maximum width and enters the highest temperature section oven. The heating temperature of the highest temperature section oven reaches 600-800°C, preferably 650-750°C, and the heating method is hot air, electric heating pipe or ceramic heating plate, preferably ceramic heating plate. The length of the highest temperature section oven is 2-6 meters, and supplementary heating is applied to the edge of the film in the highest temperature section oven. The difference between the heating temperature and the surface temperature of the thin surface is within ±10°C. The production speed of this solution is 10-30m / min, preferably 13-20m / min.

[0024] Example 1 (1) Preparation of polyamic acid (PAA) resin: 4,4'-diaminodiphenyl ether (ODA) and pyromellitic dianhydride (PMDA) monomers were added to N,N'-dimethylformamide in sequence. After polycondensation reaction, polyamic acid resin was generated. The molar ratio of diamine to dianhydride was 1:1. The solid content was 15%. The viscosity of the PAA resin was 150,000 CP. The plasticizer was hydroquinone tetraphenyl diphosphate, and the added amount was 3% of the total mass of dianhydride and diamine.

[0025] (2) PAA resin was cast onto a steel belt, and an imidizing agent was added at the edge. The imidizing agent was a mixture of acetic anhydride and isoquinoline, wherein the molar ratio of acetic anhydride to isoquinoline was 3:1, the mass fraction of the imidizing agent was 45%, and the heating rate of the imidizing agent at both sides was 4 kg / h. The maximum thickness of the PI film obtained by heating at the edge was 20% thicker than that at the center.

[0026] (3) After the PI film is peeled off, it is inserted into the needle plate, fixed on both sides, stretched horizontally and baked at high temperature, and finally cut to obtain the PI film. The maximum stretching point is located in the highest temperature section. The oven length of the highest temperature section is 3 meters. A ceramic heating plate is used for heating. The heating temperature is 600℃. The supplementary heating temperature of the film edge is 590℃. The production speed is 10m / min.

[0027] The edges of the PI film were intact during the preparation process.

[0028] Example 2 (1) Preparation of polyamic acid (PAA) resin: 4,4'-diaminodiphenyl ether (ODA) and pyromellitic dianhydride (PMDA) monomers were added to N,N'-dimethylformamide in sequence. After polycondensation reaction, polyamic acid resin was generated. The molar ratio of diamine to dianhydride was 1:1. The solid content was 15%. The viscosity of the PAA resin was 150,000 CP. The plasticizer was triphenyl phosphate, and the added amount was 6% of the total mass of dianhydride and diamine.

[0029] (2) PAA resin was cast onto a steel belt, and an imidizing agent was added at the edge. The imidizing agent was a mixture of acetic anhydride and pyridine, wherein the molar ratio of acetic anhydride to pyridine was 4:1, the mass fraction of the imidizing agent was 50%, and the heating rate of the imidizing agent at both sides was 5.5 kg / h. The maximum thickness of the PI film obtained by heating at the edge was 25% thicker than that at the center.

[0030] (3) After the PI film is peeled off, it is put into the chain clamp, fixed on both sides, stretched horizontally and baked at high temperature, and finally cut to obtain the PI film. The maximum stretching point is located in the highest temperature section. The oven length of the highest temperature section is 4 meters. A ceramic heating plate is used for heating. The heating temperature is 650℃. The supplementary heating temperature of the edge of the film is 640℃. The production speed is 13m / min.

[0031] The edges of the PI film were intact during the preparation process.

[0032] Example 3 To prepare polyamic acid (PAA) resin, 4,4'-diaminodiphenyl ether (ODA), p-phenylenediamine (PDA), pyromellitic anhydride (PMDA) and 3,3',4,4'-benzophenonetetracarboxylic anhydride (BTDA) monomers were added to N,N'-dimethylformamide in sequence, wherein the molar proportion of PDA in the total diamine monomers, namely ODA and PDA, was 30%. After polycondensation reaction, polyamic acid resin was generated, the molar ratio of diamine to dianhydride was 1:1, the solid content was 20%, the viscosity of PAA resin was 300,000 CP, and the plasticizer was resorcinol tetraphenyl diphosphate, the addition amount was 8% of the total mass of dianhydride and diamine.

[0033] (2) PAA resin was cast onto a steel belt, and an imidizing agent was added at the edge. The imidizing agent was a mixture of acetic anhydride and 3-methylpyridine, wherein the molar ratio of acetic anhydride to 3-methylpyridine was 5:1, the mass fraction of the imidizing agent was 60%, and the heating rate of the imidizing agent at both sides was 7.5 kg / h. The maximum thickness of the PI film obtained by heating at the edge was 25% thicker than that at the center.

[0034] (3) After the PI film is peeled off, it is inserted into the needle plate, fixed on both sides, stretched horizontally and baked at high temperature, and finally cut to obtain the PI film. The maximum stretching point is located in the highest temperature section. The oven length of the highest temperature section is 6 meters. A ceramic heating plate is used for heating. The heating temperature is 700℃. The supplementary heating temperature of the film edge is 710℃. The production speed is 20m / min.

[0035] The edges of the PI film were intact during the preparation process.

[0036] Example 4 To prepare polyamic acid (PAA) resin, 4,4'-diaminodiphenyl ether (ODA), 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) and pyromellitic dianhydride (PMDA) were added to N,N'-dimethylformamide in sequence, wherein the molar proportion of PMDA in the total dianhydride monomers, i.e., BTDA and PMDA, was 50%. After polycondensation reaction, polyamic acid resin was generated, the molar ratio of diamine to dianhydride was 1:1, the solid content was 20%, the viscosity of PAA resin was 300,000 CP, and the plasticizer was resorcinol tetraphenyl diphosphate, the addition amount was 10% of the total mass of dianhydride and diamine.

[0037] (2) PAA resin was cast onto a steel belt, and an imidizing agent was added at the edge. The imidizing agent was a mixture of acetic anhydride and isoquinoline, wherein the molar ratio of acetic anhydride to isoquinoline was 6:1, the mass fraction of the imidizing agent was 60%, and the heating rate of the imidizing agent at both sides was 10 kg / h. The maximum thickness of the PI film obtained by heating at the edge was 30% thicker than that at the center.

[0038] (3) After the PI film is peeled off, it is put into the chain clamp, fixed on both sides, stretched horizontally and baked at high temperature, and finally cut to obtain the PI film. The maximum stretching point is located in the highest temperature section. The oven length of the highest temperature section is 2 meters. It is heated by an electric heating tube at a heating temperature of 800°C. The supplementary heating temperature of the film edge is 800°C. The production speed is 22m / min.

[0039] The edges of the PI film were intact during the preparation process.

[0040] Example 5 To prepare polyamic acid (PAA) resin, 4,4'-diaminodiphenyl ether (ODA), p-phenylenediamine (PDA), 4,4'-diaminobenzophenone (DABP) and 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (BPDA) monomers were added to N,N'-dimethylformamide in sequence, wherein the molar proportion of PDA in the total diamine monomers, namely ODA, PDA and DABP, was 40%. After polycondensation reaction, polyamic acid resin was generated, the molar ratio of diamine to dianhydride was 1:1, the solid content was 30%, the viscosity of PAA resin was 250,000 CP, and the plasticizer was resorcinol tetraphenyl diphosphate, the addition amount was 7% of the total mass of dianhydride and diamine.

[0041] (2) PAA resin was cast onto a steel belt, and an imidizing agent was added at the edge. The imidizing agent was a mixture of acetic anhydride and isoquinoline, wherein the molar ratio of acetic anhydride to isoquinoline was 8:1, the mass fraction of the imidizing agent was 70%, and the heating rate of the imidizing agent at both edges was 13 kg / h. The maximum thickness of the PI film obtained by heating at the edge was 40% thicker than that at the center.

[0042] (3) After the PI film is peeled off, it is put into the chain clamp, fixed on both sides, stretched horizontally and baked at high temperature, and finally cut to obtain the PI film. The maximum stretching point is located in the highest temperature section. The oven length of the highest temperature section is 5 meters. The ceramic heating plate is used for heating. The heating temperature is 750℃. The supplementary heating temperature of the film edge is 740℃. The production speed is 25m / min.

[0043] The edges of the PI film were intact during the preparation process.

[0044] Comparative Example 1 The molar ratio of acetic anhydride to isoquinoline was 0.8:1, and the other steps were the same as those in Example 1. Microcracks appeared on the edge of the PI film during the preparation process.

[0045] Comparative Example 2 The addition rate of the imidization agent on both sides of the edge was 2 kg / h, and the other steps were the same as in Example 2. Microcracks appeared on the edge of the PI film during the preparation process.

[0046] Comparative Example 3 The highest temperature section of the film heating is 550° C., the supplementary heating temperature of the film edge is 560° C., and the other steps are the same as those in Example 3. Cracks appeared at the edge of the PI film during the preparation process.

[0047] Comparative Example 4 The molar ratio of PDA in the total diamine monomers, namely ODA and PDA, was 20%, and the other steps were the same as those in Example 3. Cracks appeared at the edge of the PI film during the preparation process.

[0048] Comparative Example 5 The molar ratio of PMDA in the total of the dianhydride monomers, namely BTDA and PMDA, was 15%, and the other steps were the same as those in Example 4. The edge of the PI film was broken during the preparation process and could not be continuously rolled up.

[0049] Comparative Example 6 There was no additional heating at the edge of the film, and the maximum stretching was before the highest temperature section, and the other steps were the same as in Example 5. The edge of the PI film was broken during the preparation process and could not be continuously rolled up.

[0050] Comparative Example 7 The plasticizer was resorcinol tetraphenyl diphosphate, and the addition amount was 0.5% of the total mass of dianhydride and diamine, the length of the highest temperature section oven was 1.5 meters, and the other steps were the same as Example 5. The edge of the PI film was broken during the preparation process and could not be continuously rolled up.

[0051] Comparative Example 8 The maximum thickness of the PI film obtained by heating at the edge was 15% thicker than that at the center, and the other steps were the same as those in Example 1. The edge of the PI film was broken during the preparation process and could not be continuously rolled up.

[0052] Comparative Example 9 The maximum thickness of the heated PI film at the edge is 50% thicker than that at the center, and the other steps are the same as those in Example 1. The edges of the PI film cannot be completely removed during cutting.

Claims

1. A method for preparing a polyimide film with tear-resistant edges, characterized in that: It includes the following steps in sequence: A. preparing polyamic acid resin, adding diamine monomer and dianhydride monomer in a solvent in sequence, and generating polyamic acid resin after polycondensation reaction; B. Casting the obtained polyamic acid resin onto a steel belt, and removing part of the solvent to obtain a PI film; C. After the polyimide film is peeled off, it is inserted into a needle plate or a chain clamp, fixed on both sides, stretched horizontally and heated, and finally cut to obtain a polyimide film.

2. The method for preparing a polyimide film with tear-resistant edges according to claim 1, characterized in that: The solvent is one or more combinations of N,N'-dimethylformamide, N,N'-dimethylacetamide and N-methylpyrrolidone.

3. The method for preparing a polyimide film with tear-resistant edges according to claim 1, characterized in that: The diamine monomer is at least one of p-phenylenediamine, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminobenzophenone and 3,4'-diaminodiphenyl ether; the dianhydride monomer is at least one of pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride and 3,3',4,4'-benzophenone tetracarboxylic dianhydride.

4. The method for preparing a polyimide film with tear-resistant edges according to claim 1, characterized in that: The molar ratio of diamine monomer to dianhydride monomer is 1:(0.8-1.2), the molar ratio of rigid diamine monomer to the total molar ratio of diamine monomer is ≥30%, or the molar ratio of rigid dianhydride monomer to the total molar ratio of dianhydride monomer is ≥30%.

5. The method for preparing a polyimide film with tear-resistant edges according to claim 1, characterized in that: The solid content of the polyamic acid resin is set to be 15-30% by weight, and the viscosity is 100,000-400,000 CP.

6. The method for preparing a polyimide film with tear-resistant edges according to claim 1, characterized in that: After peeling, the maximum thickness of the edges on both sides of the needle plate or chain clip is 20% to 40% thicker than the central position, the edge width is 1 to 5 cm, and the edge part is finally cut off.

7. The method for preparing a polyimide film with tear-resistant edges according to claim 6, characterized in that: An imidization agent is added to the edge position, and the imidization agent components include an organic anhydride dehydrating agent, an organic base catalyst and a solvent that is the same as the polyamic acid resin. The organic anhydride dehydrating agent includes one of acetic anhydride, propionic anhydride, butyric anhydride, benzoic anhydride, and maleic anhydride, or a mixture thereof in any proportion; the organic base catalyst includes one of isoquinoline, pyridine, 2-methylpyridine, and 3-methylpyridine, or a mixture thereof in any proportion; wherein the molar ratio of the organic anhydride dehydrating agent to the organic base catalyst is 1:1 to 10:1, and the mass fraction of the imidization agent, i.e., m(organic anhydride dehydrating agent+organic base catalyst) / m 总 (organic acid anhydride dehydrating agent + organic base catalyst + solvent), is 40% to 70%, and the rate of adding the imidization reagent on both sides is the same, which is 3 to 15 kg / h respectively.

8. The method for preparing a polyimide film with tear-resistant edges according to claim 1, characterized in that: A plasticizer is added to the polyamic acid resin. The plasticizer is one of triisopropylphenyl phosphate, triphenyl phosphate and resorcinol tetraphenyl diphosphate. The added amount is 1-10% of the total mass of the diamine monomer and the dianhydride monomer.

9. The method for preparing a polyimide film with tear-resistant edges according to claim 1, characterized in that: The film is stretched to its maximum width and enters the highest temperature section oven. The heating temperature of the highest temperature section oven reaches 600-800℃. The heating method is hot air, electric heating tube or ceramic heating plate. The length of the highest temperature section oven is 2-6 meters. At the same time, supplementary heating is applied to the edge of the film in the highest temperature section oven. The difference between the heating temperature and the surface temperature of the film is within ±10℃.

10. The method for preparing a polyimide film with tear-resistant edges according to claim 1, characterized in that: The production speed is 10-30m / min.