Preparation method of polyimide adhesive film and copper-clad plate

Abstract

In order to solve the problem that existing polyphenyl ether modified polyimide is insufficient in high temperature resistance, the invention provides a preparation method of a polyimide adhesive film and a copper-clad plate, and the preparation method of the polyimide adhesive film comprises the following operation steps: preparation of diamine end modified polyphenyl ether; carrying out esterification polycondensation reaction on 2, 5-diaminobenzoic acid and terminal hydroxylated polyphenyl ether to obtain diamine terminal modified polyphenyl ether; preparation of polyisoimide: carrying out polymerization reaction on diamine end modified polyphenyl ether, dicarboxylic anhydride and diamine to obtain polyamic acid grafted with polyphenyl ether, and carrying out isoimide cyclization reaction on the polyamic acid to obtain carboxyl-terminated polyisoimide; and isomerizing the polyisoimide to obtain the polyimide adhesive film. The polyimide adhesive film provided by the invention has excellent dielectric properties, mechanical properties and high temperature resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of modified resin materials, and in particular relates to a preparation method of a polyimide adhesive film and a copper-clad laminate. Background Art

[0002] Polyimide (abbreviated as PI) refers to a type of polymer containing an imide ring (-CO-NR-CO-) on the main chain. It is one of the organic polymer materials with the best comprehensive performance. As a special engineering material, polyimide has been widely used in aviation, aerospace, microelectronics, nano, liquid crystal, separation membrane, laser and other fields.

[0003] Although polyimide itself has certain heat resistance and low dielectric loss, in some application environments, the material itself has higher dielectric properties and heat resistance requirements, such as some locations that require soldering, or some extreme application environments. It is difficult for simple polyimide to meet its dielectric properties and heat resistance requirements. An existing method is to improve the dielectric properties of polyimide by blending polyphenylene ether in polyimide. However, this method will reduce the heat resistance of the material itself accordingly. Although the cross-linking density can be further added to increase the heat resistance to a certain extent, it still cannot meet the better temperature resistance requirements. In order to improve the mixing uniformity of polyimide and polyphenylene ether, in the prior art, carboxyl groups are connected to the ends of polyimide to react with polyphenylene ether with terminal hydroxyl groups to improve the full dispersion and cross-linking of the two. However, this method still cannot give full play to the role of polyimide and polyphenylene ether. Summary of the invention

[0004] Aiming at the problem that the existing polyimide modified with polyphenylene ether has insufficient high temperature resistance, the present invention provides a method for preparing a polyimide adhesive film and a copper clad laminate.

[0005] The technical solution adopted by the present invention to solve the above technical problems is as follows: In one aspect, the present invention provides a method for preparing a polyimide film, comprising the following steps: Preparation of diamine end-modified polyphenylene ether: esterification polycondensation reaction of 3,5-diaminobenzoic acid and end-hydroxylated polyphenylene ether to obtain diamine end-modified polyphenylene ether; Preparation of polyisoimide: Polyphenylene ether end-modified with diamine, dibasic acid anhydride and diamine are polymerized to obtain polyamic acid grafted with polyphenylene ether, and polyamic acid is subjected to isoimide cyclization reaction to obtain carboxyl-terminated polyisoimide; The polyimide film is obtained by isomerization of polyisoimide.

[0006] Optionally, in the preparation of the diamine end-modified polyphenylene ether, the reaction temperature is 120-155° C. and the reaction time is 2-8 hours.

[0007] Optionally, in the preparation of the diamine end-modified polyphenylene ether, a first catalyst is added, the added mass of the first catalyst is 0.005 to 0.05 times that of 3,5-diaminobenzoic acid, and the second catalyst is selected from one or more of dicyclohexylcarbodiimide, 4-dimethylaminopyridine, N,N'-diisopropylcarbodiimide, N,N'-diisopropylcarbodiimide / 4-dimethylaminopyridine, 1-(3-dimethylaminopropyl)-3-ethyl-carbodiimide hydrochloride / N,N'-diisopropylcarbodiimide.

[0008] Optionally, in the preparation of the polyisoimide, the molar ratio of the diamine-terminated polyphenylene ether, the dibasic acid anhydride and the diamine is (0.01-0.1): (0.5-1.5):1.

[0009] Optionally, in the polymerization reaction of the diamine end-modified polyphenylene ether, the dibasic acid anhydride and the diamine, the reaction temperature is -10 to 90°C.

[0010] Optionally, the dibasic acid anhydride is selected from one or more of 3,3,4,4-biphenyltetracarboxylic dianhydride and 4,4'-biphenyl ether tetracarboxylic dianhydride; and / or The diamine is selected from one or more of 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, and 4,4'-diamino-3,3'-dimethylbiphenyl.

[0011] Optionally, a second catalyst is added to the isocyanide cyclization reaction, and the added mass of the second catalyst is 0.2 to 0.9 times the molar number of the dibasic acid anhydride, and the second catalyst includes one or more selected from the group consisting of a combination catalyst pyridine / trifluoroacetic anhydride, a combination catalyst 4-dimethylaminopyridine / dicyclohexylcarbodiimide, a combination catalyst 4-dimethylaminopyridine / N,N'-diisopropylcarbodiimide, and a combination catalyst 4-dimethylaminopyridine / 1-(3-dimethylaminopropyl)-3-ethyl-carbodiimide hydrochloride.

[0012] Optionally, in the isoimide cyclization reaction, the reaction temperature is 25-60° C., and the reaction time is 1-5 h. Optionally, the isomerization of polyisoimide to obtain polyimide comprises the following operations: The polyisoimide solution is cast into a film on a polytetrafluoroethylene plate; The solvent is dried at a temperature range of 90 to 120° C. and the polyisoimide is isomerized by heating to obtain a polyimide film.

[0013] In another aspect, the present invention provides a copper clad laminate, comprising a copper foil and a polyimide film layer, wherein the polyimide film layer is disposed on the copper foil, and the polyimide film layer is prepared by the preparation method described above.

[0014] According to the preparation method of the polyimide film provided by the present invention, 3,5-diaminobenzoic acid is used to modify the end of the hydroxylated polyphenylene ether, and the terminal carboxyl group of the 3,5-diaminobenzoic acid and the polyphenylene ether are esterified to make the end of the polyphenylene ether grafted with two amine groups, and then the polyphenylene ether is further modified by the end of the diamine to replace part of the diamine and to be co-polymerized with the dibasic acid anhydride and the diamine, so that the polyphenylene ether segment can be fully grafted onto the polyimide main chain. Compared with the existing direct blending or the method of grafting the polyphenylene ether to the end of the polyimide, the preparation method provided by the present invention can further realize the block chemical bonding dispersion of the polyphenylene ether in the polyisoimide segment, and the obtained polyimide has improved dielectric properties, mechanical properties and high temperature resistance. DETAILED DESCRIPTION

[0015] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0016] An embodiment of the present invention provides a method for preparing a polyimide film, comprising the following steps: Preparation of diamine end-modified polyphenylene ether: esterification polycondensation reaction of 3,5-diaminobenzoic acid and end-hydroxylated polyphenylene ether to obtain diamine end-modified polyphenylene ether; Preparation of polyisoimide: Polyphenylene ether end-modified with diamine, dibasic acid anhydride and diamine are polymerized to obtain polyamic acid grafted with polyphenylene ether, and polyamic acid is subjected to isoimide cyclization reaction to obtain carboxyl-terminated polyisoimide; The polyimide film is obtained by isomerization of polyisoimide.

[0017] The terminal hydroxylated polyphenylene ether is modified by using 3,5-diaminobenzoic acid, and the terminal carboxyl group of 3,5-diaminobenzoic acid and the polyphenylene ether are esterified, so that two amine groups are grafted on the terminal of the polyphenylene ether, and the polyphenylene ether is further modified by using diamine to replace part of the diamine and to be co-polymerized with the dibasic acid anhydride and the diamine, so that the polyphenylene ether chain segment can be fully grafted onto the polyimide main chain. Compared with the existing direct blending or the method of grafting the polyphenylene ether to the end of the polyimide, the preparation method provided by the present invention can further realize the block chemical bonding dispersion of the polyphenylene ether in the polyisoimide chain segment, and the obtained polyimide has improved dielectric properties, mechanical properties and high temperature resistance.

[0018] In some embodiments, in the preparation of the diamine-terminated polyphenylene ether, the reaction temperature is 120-155° C. and the reaction time is 2-8 hours.

[0019] In some embodiments, a first catalyst is added in the preparation of the diamine end-modified polyphenylene ether, the added mass of the first catalyst is 0.005 to 0.05 times that of 3,5-diaminobenzoic acid, and the second catalyst is selected from one or more of dicyclohexylcarbodiimide, 4-dimethylaminopyridine, N,N'-diisopropylcarbodiimide, N,N'-diisopropylcarbodiimide / 4-dimethylaminopyridine, 1-(3-dimethylaminopropyl)-3-ethyl-carbodiimide hydrochloride / N,N'-diisopropylcarbodiimide.

[0020] Since the active end group (-OH) of the terminal hydroxylated polyphenylene ether is connected to the benzene ring, its reaction activity is lower than that of the end group (-OH) of the fatty chain hydrocarbon, and the nucleophilic-elimination polycondensation reaction is relatively difficult. The first catalyst is added in the preparation method, which can effectively promote the polycondensation reaction. At the same time, the carbodiimide catalyst can form an active intermediate between the terminal carboxyl group and the catalyst, thereby effectively improving the group selectivity of the catalytic reaction process, and improving the reaction efficiency and conversion rate.

[0021] In some embodiments, in the preparation of the diamine-terminated polyphenylene ether, the reaction is carried out in a first solvent to facilitate the completion of the reaction process in a homogeneous medium system.

[0022] In some embodiments, the first solvent is selected from one or more of 1,3-dimethyl-2-imidazolidinone (DMI), N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide.

[0023] In some embodiments, in the preparation of the polyisoimide, the molar ratio of the diamine-terminated polyphenylene ether, the dibasic acid anhydride and the diamine is (0.01-0.1): (0.5-1.5):1.

[0024] In some embodiments, during the polymerization reaction of the diamine-terminated polyphenylene ether, the dibasic acid anhydride and the diamine, the reaction temperature is -10 to 90°C.

[0025] The reaction time is determined by measuring the actual acid value of the reaction system. When the actual acid value of the system reaches the theoretical acid value, the reaction is completed. The determination method adopts potassium hydroxide titration method, and the acid value is expressed in mgKOH / g.

[0026] In some embodiments, the dibasic acid anhydride is selected from phenyl dibasic acid anhydride, and the diamine is selected from phenyl diamine.

[0027] In some embodiments, the dibasic acid anhydride is selected from one or more of 3,3,4,4-biphenyltetracarboxylic dianhydride and 4,4'-biphenyl ether tetracarboxylic dianhydride.

[0028] In some embodiments, the diamine is selected from one or more of 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, or 4,4'-diamino-3,3'-dimethylbiphenyl.

[0029] In some embodiments, the polymerization reaction of the diamine-terminated polyphenylene ether, dibasic acid anhydride and diamine is carried out in a second solvent. It should be noted that in the preparation of the diamine-terminated polyphenylene ether, a diamine-terminated polyphenylene ether solution is prepared, and dibasic acid anhydride and diamine are further added to the diamine-terminated polyphenylene ether solution for reaction, so the second solvent is the first solvent.

[0030] In some embodiments, a second catalyst is added to the isoimide cyclization reaction, the added mass of the second catalyst is 0.2 to 0.9 times the molar number of the dibasic acid anhydride, and the second catalyst includes one or more selected from the group consisting of a combination catalyst of pyridine / trifluoroacetic anhydride, a combination catalyst of 4-dimethylaminopyridine / dicyclohexylcarbodiimide, a combination catalyst of 4-dimethylaminopyridine / N,N'-diisopropylcarbodiimide, and a combination catalyst of 4-dimethylaminopyridine / 1-(3-dimethylaminopropyl)-3-ethyl-carbodiimide hydrochloride. The molar ratio between the combination catalysts is 1:1.

[0031] In some embodiments, in the isoimide cyclization reaction, the reaction temperature is 25-60° C., the reaction time is 1-5 h, In some embodiments, the isomerization of polyisoimide to obtain polyimide comprises the following operations: The polyisoimide solution is cast into a film on a polytetrafluoroethylene plate; The solvent is dried at a temperature range of 90 to 120° C. and the polyisoimide is isomerized by heating to obtain a polyimide film.

[0032] Another embodiment of the present invention provides a copper clad laminate, comprising a copper foil and a polyimide film layer, wherein the polyimide film layer is disposed on the copper foil, and the polyimide film layer is prepared by the preparation method described above.

[0033] The present invention is further described below by way of examples.

[0034] Example 1 This embodiment is used to illustrate the polyimide film and the preparation method thereof disclosed in the present invention, and includes the following steps: S1. Preparation of diamine-terminated polyphenylene ether: 0.05 mol of terminal hydroxylated polyphenylene ether was stirred and dissolved in 50 ml of 1,3-dimethyl-2-imidazolidinone, 0.05 mol of 3,5-diaminobenzoic acid and 0.001 mol of dicyclohexylcarbodiimide were added, nitrogen was introduced, the temperature was raised to 150° C., and the reaction was carried out at a constant temperature for 5 hours; after the reaction was completed, the reaction system was cooled to 120° C. and the reaction was carried out under reduced pressure distillation for 1 hour to evaporate the water molecules and part of the solvent produced by the reaction; a diamine-terminated polyphenylene ether solution with a solid content of 40% was obtained; The 3,5-diaminobenzoic acid and the terminal hydroxylated polyphenylene ether are subjected to an esterification polycondensation reaction to obtain a diamine terminal modified polyphenylene ether; The hydroxylated polyphenylene ether is selected from the compound shown in structural formula 1: R'-OH Structural formula 1 Wherein R' is selected from the segment shown in structural formula 2: Structural formula 2 S2. Preparation of polyisoimide: Add 0.1 mol (20.023 g) of 4,4'-diaminodiphenyl ether to the diamine end-modified polyphenylene ether solution, stir and disperse, then add 0.1 mol (31.025 g) of 4,4'-biphenyl ether tetracarboxylic dianhydride and heat to 70°C, and measure the actual acid value of the reaction system every 1 hour until the theoretical acid value is reached, stop the reaction, and obtain a polyamic acid solution. Add 0.01 mol of 4-dimethylaminopyridine / N,N'-diisopropylcarbodiimide to the polyamic acid solution, stir and react at a constant temperature of 45°C for 5 hours to obtain a polyisoimide solution; S3. Cast the polyisoimide solution on a polytetrafluoroethylene plate, transfer it to a forced air drying oven, dry the solvent within a temperature range of 100°C, and carry out an isomerization reaction according to a heating program of 150°C / 1h+170°C / 2h+190°C3h+210°C / 4h+230°C / 2h to obtain a polyimide film.

[0035] Example 2 This example is used to illustrate the polyimide adhesive film and the preparation method thereof disclosed in the present invention, and includes most of the operation steps in Example 1, except that: In step S2, the amount of 4,4'-diaminodiphenyl ether added is 0.05 mol, and the amount of 4,4'-biphenyl ether tetracarboxylic dianhydride added is 0.05 mol.

[0036] Example 3 This example is used to illustrate the polyimide adhesive film and the preparation method thereof disclosed in the present invention, and includes most of the operation steps in Example 1, except that: In step S2, 4,4'-diaminodiphenylmethane is used to replace 4,4'-diaminodiphenyl ether; and 3,3,4,4-biphenyltetracarboxylic dianhydride is used to replace 4,4'-biphenyl ether tetracarboxylic dianhydride.

[0037] Comparative Example 1 This comparative example is used to compare and illustrate the polyimide adhesive film and the preparation method thereof disclosed in the present invention, and includes most of the operation steps in Example 1, except that: The operation of step S1 is not performed, and in step S2, the diamine end-modified polyphenylene ether solution is replaced by the polyphenylene ether solution represented by structural formula 1.

[0038] Comparative Example 2 This comparative example is used to compare and illustrate the polyimide adhesive film and the preparation method thereof disclosed in the present invention, and includes most of the operation steps in Example 1, except that: The operation of step S1 is not performed, and 1,3-dimethyl-2-imidazolidinone is used in step S2 to replace the diamine end-modified polyphenylene ether solution.

[0039] Performance Testing The polyimide film prepared above was subjected to the following performance tests: Heat resistance 1) Glass transition temperature (Tg) The glass transition temperature (Tg) of the film was measured on a DSC-25 differential scanning calorimeter. Test conditions: N2 atmosphere, heating rate 10°C / min, temperature range room temperature ~ 400°C. Sample shape: sheet film Dielectric properties test The dielectric properties test was conducted on a vector network analyzer-cylindrical resonant cavity. Test conditions: test frequency is 10 GHz. Sample size: 70 mm × 70 mm × 0.25 mm.

[0040] Mechanical properties test The mechanical properties test of the film was carried out on a Shenzhen Xinsansi CMT-6503 microcomputer-controlled electronic universal tensile testing machine to test the tensile properties of the film. Test conditions: test temperature: room temperature, sample size: 100mm×10mm×0.25mm, loading speed: 2mm / min.

[0041] The test results obtained are entered in Table 1.

[0042] Table 1 It can be seen from the test results in Table 1 that the polyimide film prepared by the preparation method provided by the present invention is prepared by end-modifying the polyphenylene ether and then copolymerizing it with diamine and dibasic acid anhydride to achieve block chemical bonding and dispersion of the polyphenylene ether in the polyisoimide segment, and the obtained polyimide has good improvements in dielectric properties, mechanical properties and high temperature resistance.

[0043] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a polyimide film, characterized in that: The steps include: Preparation of diamine end-modified polyphenylene ether: esterification polycondensation reaction of 3,5-diaminobenzoic acid and end-hydroxylated polyphenylene ether to obtain diamine end-modified polyphenylene ether; Preparation of polyisoimide: Polyphenylene ether end-modified with diamine, dibasic acid anhydride and diamine are polymerized to obtain polyamic acid grafted with polyphenylene ether, and polyamic acid is subjected to isoimide cyclization reaction to obtain carboxyl-terminated polyisoimide; The polyimide film is obtained by isomerization of polyisoimide.

2. The method for preparing a polyimide film according to claim 1, characterized in that: In the preparation of the diamine end-modified polyphenylene ether, the reaction temperature is 120-155° C. and the reaction time is 2-8 hours.

3. The method for preparing a polyimide film according to claim 1, characterized in that: In the preparation of the diamine end-modified polyphenylene ether, a first catalyst is added, the added mass of the first catalyst is 0.005 to 0.05 times that of 3,5-diaminobenzoic acid, and the second catalyst is selected from one or more of dicyclohexylcarbodiimide, 4-dimethylaminopyridine, N,N'-diisopropylcarbodiimide, N,N'-diisopropylcarbodiimide / 4-dimethylaminopyridine, 1-(3-dimethylaminopropyl)-3-ethyl-carbodiimide hydrochloride / N,N'-diisopropylcarbodiimide.

4. The method for preparing a polyimide film according to claim 1, characterized in that: In the preparation of the polyisoimide, the molar ratio of the diamine end-modified polyphenylene ether, the dibasic acid anhydride and the diamine is (0.01-0.1): (0.5-1.5):

1.

5. The method for preparing a polyimide film according to claim 1, characterized in that: In the polymerization reaction of the diamine end-modified polyphenylene ether, dibasic acid anhydride and diamine, the reaction temperature is -10 to 90°C.

6. The method for preparing a polyimide adhesive film according to claim 1, characterized in that: The dibasic acid anhydride is selected from one or more of 3,3,4,4-biphenyltetracarboxylic dianhydride and 4,4'-biphenyl ether tetracarboxylic dianhydride; and / or The diamine is selected from one or more of 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, and 4,4'-diamino-3,3'-dimethylbiphenyl.

7. The method for preparing a polyimide film according to claim 1, characterized in that: A second catalyst is added to the isocyanide cyclization reaction, and the added mass of the second catalyst is 0.2 to 0.9 times the molar number of the dibasic acid anhydride. The second catalyst includes one or more selected from the combination catalyst pyridine / trifluoroacetic anhydride, the combination catalyst 4-dimethylaminopyridine / dicyclohexylcarbodiimide, the combination catalyst 4-dimethylaminopyridine / N,N'-diisopropylcarbodiimide, and the combination catalyst 4-dimethylaminopyridine / 1-(3-dimethylaminopropyl)-3-ethyl-carbodiimide hydrochloride.

8. The method for preparing a polyimide adhesive film according to claim 1, characterized in that: In the isoimidyl cyclization reaction, the reaction temperature is 25-60° C. and the reaction time is 1-5 h.

9. The method for preparing a polyimide adhesive film according to claim 1, characterized in that: The isomerization of polyisoimide to obtain polyimide comprises the following operations: The polyisoimide solution is cast into a film on a polytetrafluoroethylene plate; The solvent is dried at a temperature range of 90 to 120° C. and the polyisoimide is isomerized by heating to obtain a polyimide film.

10. A copper clad laminate, characterized in that: The invention comprises a copper foil and a polyimide film layer, wherein the polyimide film layer is arranged on the copper foil, and the polyimide film layer is prepared by the preparation method according to any one of claims 1 to 9.

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