CN1786052A - Preparation method of polyimide - Google Patents

Abstract

The present invention relates to a novel preparation method of polyimide, which comprises reacting dianhydride and diamine to form polyamic acid (polyamic acid), and then coating the polyamic acid or coating it by methods such as casting On the support, remove the solvent by controlling the volatile content of the polyamic acid below 10% by weight, and control the tension below 20kgf/ ^cm2 for winding, then enter the high-temperature oven in batch mode, using gradient The polyamic acid is dehydrated and cyclized into polyimide by heating at a temperature, and a flexible laminate with high yield and good appearance can be obtained. According to the method of the invention, the polyimide soft film with good quality can be obtained at low cost.

Description

Production method of polyimide

technical field

The present invention relates to a novel method of manufacturing polyimide by coating or casting on a support, especially by controlling the volatile content of polyamic acid and using gradient after winding with a specific tension Novel manufacturing method of polyimide with high yield and appearance and flexible laminate obtained by heating at high temperature.

Background technique

Polyimide is a high-temperature-resistant material with a wide range of uses. It is insoluble in solvents and does not melt. It can be formed into a film from polyamic acid in solution. Or it can be used as an adhesive or an insulating material for wires, or it can be imidized after being formed into the final product shape. Polyimide has high thermal stability, can withstand all packaging conditions, and can withstand the temperature test of metallization. It has electrical characteristics, low surface and overall leakage rates, and is also suitable for high-frequency circuits.

Due to these characteristics of polyimide, it is widely used in communications, consumer electronics, personal communication assistants, gas separation membranes and other fields. Polyimide is usually coated on a metal foil such as copper foil to make a flexible circuit board, and is used in electronic communication equipment such as notebook computers, consumer electronics products, and mobile phones.

In the production of flexible circuit boards, the following methods are currently used: (1) Coating polyamic acid resin on metal foil or polyimide film, continuously passing through high-temperature infrared rays or heating furnaces generally higher than 350°C Polyamic acid is cyclized to form polyimide, but at this high temperature, due to the difference in thermal expansion coefficient between metal foil and polyimide, the resulting polyimide film often warps, resulting in the winding of the polyimide film. When the winding is not good, the yield rate is reduced, and the equipment used is expensive; (2) the polyamic acid resin is coated on the metal foil or the polyimide film, and the braided iron mesh is used as a pad on both sides of the metal foil to The batch type enters the high-temperature infrared ray or heating furnace that is generally higher than 350°C to cyclize the polyamic acid to form polyimide, but the woven iron mesh is often deformed at this high temperature, resulting in wrinkles in the finished polyimide product, reducing the yield rate; and (3) coating polyamic acid resin on metal foil or polyimide film, separated by high temperature resistant release film or polyimide film, and entering into high temperature infrared ray or heating furnace Polyamic acid is cyclized to form polyimide, but the operating temperature of this method should not be too high, otherwise the release film will melt or the polyimide resin will stick, making the appearance of the finished product poor, but the operating temperature will decrease If the cyclization rate is more than 95% if the cyclization rate is to be achieved, the operation time will be longer and the production efficiency will be reduced.

In view of the above, in order to improve the shortcomings of the above-mentioned conventional methods, the present inventors conducted extensive research on the process conditions for the cyclization of polyamic acid to polyimide, thus completing the present invention.

Contents of the invention

The present invention relates to a novel preparation method of polyimide, comprising reacting dianhydride and diamine to form polyamic acid, and then coating the polyamic acid on the polyamic acid by coating or casting. On the support, remove the solvent by controlling the volatile content of the polyamic acid below 10% by weight, and control the tension below 20kgf/ ^cm2 for winding, then enter the high-temperature oven in batch mode, using gradient temperature The polyamic acid is dehydrated and cyclized into polyimide by heating, and a flexible laminate with high yield and good appearance can be obtained.

The method for preparing polyamic acid in the present invention is to react dianhydride and diamine to form a polymer containing -NH-CO-functional groups and carboxylic acid groups. And the cyclization reaction referred to in the present invention is a process of further dehydrating and condensing the -NH-CO-functional group and the carboxylic acid group to form a cyclic group, also called imidization reaction.

According to the method of the present invention, the polyimide resin metal foil soft film with no wrinkle, good appearance and excellent mechanical properties can be obtained with high yield and high cyclization rate.

Detailed ways

Examples of dianhydrides for the preparation of polyamic acid in the present invention include (but not limited to) aromatic dianhydrides such as pyromellitic dianhydride (PMDA), 4,4-diphthalic dianhydride (BPDA), 4,4 - Hexafluoroisopropylidene diphthalic dianhydride (6FDA), 1-(trifluoromethyl)-2,3,5,6-benzenetetracarboxylic dianhydride (P3FDA), 1,4-bis(tri Fluoromethyl)-2,3,5,6-benzenetetracarboxylic dianhydride (P6GDA), 1-(3',4'-dicarboxyphenyl)-1,3,3-trimethylindan- 5,6-dicarboxylic dianhydride, 1-(3',4'-dicarboxyphenyl)-1,3,3-trimethylindane-6,7-dicarboxylic dianhydride, 1-( 3',4'-dicarboxyphenyl)-3-methylindane-5,6-dicarboxylic dianhydride, 1-(3',4'-dicarboxyphenyl)-3-methylindane -6,7-dicarboxylic dianhydride, 2,3,9,10-perylenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,6-dichloro Naphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,3,6,7-tetrachloronaphthalene- 2,4,5,8-tetracarboxylic dianhydride, phenanthrene-1,8,9,10-tetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 1,2',3,3'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-biphenyl tetracarboxylic dianhydride, 3,3',4,4'-diphenyl Methanone tetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 4,4'-isopropylidene diphthalic anhydride, 3,3'-isopropylidene Diphthalic dianhydride, 4,4'-oxydiphthalic dianhydride, 4,4'-sulfonyl diphthalic dianhydride, 3,3'-oxydiphthalic dianhydride, 4,4'- Methylene diphthalic dianhydride, 4,4'-thiodiphthalic dianhydride, 4,4'-ethylene diphthalic dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride , 1,2,4,5-naphthalene tetracarboxylic dianhydride, 1,2,5,6-naphthalene tetracarboxylic dianhydride, benzene-1,2,3,4-tetracarboxylic dianhydride, pyrazine- 2,3,5,6-tetracarboxylic dianhydride, etc., among which pyromellitic dianhydride (PMDA), 4,4-diphthalic dianhydride (BPDA), 4,4-hexafluoroisoiso Propyl diphthalic dianhydride (6FDA), 1-(trifluoromethyl)-2,3,5,6-benzenetetracarboxylic dianhydride (P3FDA), 1,4-bis(trifluoromethyl)- 2,3,5,6-Phenylenetetracarboxylic dianhydride (P6GDA).

Examples of diamines for preparing polyamic acid in the present invention include (but not limited to) aromatic diamines such as 4,4'-oxydiphenylamine (ODA), 5-amino-1-(4'-amino Phenyl)-1,3,3-trimethylindane, 6-amino-1-(4'-aminophenyl)-1,3,3-trimethylindane, 4,4'- Methylenebis(o-chloroaniline), 3,3'-dichlorodiphenylamine, 3,3'-sulfonyldiphenylamine, 4,4'-diaminobenzophenone, 1,5-diamine Naphthalene, bis(4-aminophenyl)diethylsilane, bis(4-aminophenyl)diphenylsilane, bis(4-aminophenyl)ethylphosphine oxide, N-(bis (4-aminophenyl))-N-methylamine, N-(bis(4-aminophenyl))-N-phenylamine, 4,4'-methylenebis(2-methyl Aniline), 4,4'-methylenebis(2-methoxyaniline), 5,5'-methylenebis(2-aminophenol), 4,4'-methylenebis(2- methylaniline), 4,4'-oxybis(2-methoxyaniline), 4,4'-oxybis(2-chloroaniline), 2,2'-bis(4-aminophenol) , 5,5'-oxybis(2-aminophenol), 4,4'-thiobis(2-methylaniline), 4,4'-thiobis(2-methoxyaniline), 4,4'-thiobis(2-chloroaniline), 4,4'-sulfonylbis(2-methylaniline), 4,4'-sulfonylbis(2-ethoxyaniline), 4, 4'-sulfonylbis(2-chloroaniline), 5,5'-sulfonylbis(2-aminophenol), 3,3'-dimethyl-4,4'-diaminobenzophenone , 3,3'-dimethoxy-4,4'-diaminobenzophenone, 3,3'-dichloro-4,4'-diaminobenzophenone, 4,4'- Diaminobiphenyl, m-phenylenediamine, p-phenylenediamine, 4,4'-methylenediphenylamine, 4,4'-thiodiphenylamine, 4,4'-sulfonyldiphenylamine, 4 , 4'-isopropylidene diphenylamine, 3,3'-dimethylbenzidine, 3,3'-dimethoxybenzidine, 3,3'-dicarboxybenzidine, 2,4-tolyl Diamine, 2,5-tolyldiamine, 2,6-tolyldiamine, m-xylylenediamine, 2,4-diamino-5-chlorotoluene, 2,4-diamino- 6-chlorotoluene, etc. Preferably it is 4,4'-oxydiphenylamine (ODA).

The reaction of the dianhydride and diamine can be carried out in an aprotic polar solvent, and the type of the aprotic polar solvent is not particularly limited as long as it does not react with reactants and products. Specific examples can include, for example, N, N-dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), N, N-dimethylformamide (DMF), tetrahydrofuran (THF), dioxane, chloroform (CHCl ₃ ), dichloromethane, etc. Among them, 1-methylpyrrolidone (NMP) and N,N-dimethylacetamide (DMAc) are preferably used.

The reaction of the dianhydride and diamine is generally carried out at a temperature ranging from room temperature to 70° C., and the ratio of the aromatic diamine to aromatic dianhydride is in the range of 0.5 to 2.0, preferably in the range of 0.75 to 1.25.

According to the method of the present invention, after the dianhydride and diamine react to form polyamic acid, the polyamic acid resin is coated on the support by methods such as coating or casting, and then the solvent contained therein is removed by controlling the polyamic acid. The volatile matter content in the amic acid is 10% by weight or less. Then use a rewinding machine to wrap the support coated with polyamic acid on the steel pipe of the rewinding machine with the coated resin facing inward or outward, and control the tension below 20kgf/cm ² , and then loosen it. The roll leaves a gap between the layers, allowing heat convection to enter the layers to achieve the purpose of cyclization. The wrap length can be up to 150 meters, preferably a length of 20 to 120 meters.

The support used in the method of the present invention can be metal foils such as polyimide films such as Kapton and Upliex, copper foil, aluminum foil, stainless steel foil, nickel foil, etc., and copper foil is more commonly used.

Then move the unrolled windings to the oven, so that the temperature gradient of the oven is controlled in the range of 100 to 380°C, that is, starting from 100°C, the temperature is gradually increased to as high as 380°C at a rate of 1-2°C/min Afterwards, cool it down. During the temperature rise from 160 to 380°C, you can stay at several specific temperatures for tens of minutes, for example, start at 160 to 180°C and stay for about 30 minutes, then gradually increase the temperature at a rate of 2°C/min to about After staying at 210 to 230°C for about 30 minutes, then gradually raising the temperature to about 270 to 290°C at a heating rate of 2°C/min and staying for about 30 minutes, and then gradually raising the temperature at a heating rate of 2°C/minute to about 340 to 350° C. for a further dwell of eg about 30 minutes, finally raised to 370° C. and held for about 10 minutes before being cooled.

In the cyclization process of the present invention, catalysts such as triethylamine and acetic anhydride may also be added to accelerate the cyclization reaction. When a catalyst is used in the cyclization process, the temperature gradient used can be relatively low.

When copper foil is used as the support, in order to avoid copper foil oxidation, it is better to blow inert gas such as nitrogen in the process of heating and cyclization in the oven to keep the oxygen concentration in the oven below 1.0% by volume, preferably 0.5% by volume. % or less, preferably less than 0.1% by volume, it can prevent the copper foil from oxidative discoloration.

In the method of the present invention, in order to leave a space between the layers of the winding to facilitate the passage of heat convection, a smooth rod can also be inserted every few meters during the winding, and removed after the winding is completed.

Below will further illustrate the present invention with embodiment and comparative example, in these embodiments and comparative example, the measuring method of volatile matter and the measuring method of cyclization rate (imidization rate) are as follows:

Volatile content measurement method

Take a 10 cm × 10 cm resin metal foil sample and weigh it accurately as W1, place the sample in an oven at 220°C for 20 minutes, take it out and weigh it accurately as W2, and make another uncoated sample of the same 10 cm × 10 cm A metal foil sample of cloth resin is weighed as W3. Volatile % was calculated by the following formula.

Volatile matter (%)=(W1-W2)/(W1-W3)×100%

Cyclization rate (imidization rate) measurement method:

Use FTIR (Fourier Transform Infrared Spectrometer) to measure the absorption area ratio ([area _(1720cm-1) /area _(1500cm-1) ]T) of the resin at temperature T between 1720cm ^-1 and 1500cm ^- 1, and then use FTIR to measure the resin The absorption area ratio ([area _(1720cm-1) /area _(1500cm-1) ^] T ₁ ) of 1720cm ^- 1 to 1500cm-1 after 1 hour at a temperature of 350°C, the cyclization rate (%) is calculated by the following formula:

Cyclization rate (%)=[area _(1720cm-1) /area _(1500cm-1) ]T/[area _(1720cm-1) /area _(1500cm-1) ]T ₁ ×100%

Example 1

After pyromellitic dianhydride (PMDA) and 4,4'-oxydianiline (ODA) were reacted using N-methylpyrrolidone (NMP) as a solvent, a polyamic acid resin with a solid content of 15% was obtained. The fabric machine is coated on a copper foil with a thickness of 18 microns and a width of 520 mm. The NMP solvent is evaporated by hot air or an IR oven. The solvent content of the support resin is measured to be 3.2% by weight. The acid resin copper foil is wound on the steel pipe, the tension is controlled below 20kgf/ ^cm2 , and a smooth rod is inserted every 15 meters of winding while winding, and after a total of 100 meters of winding, the outermost ring is covered with polyimide After the tape is set, remove the smooth bar to unwind the copper foil. Then move it into an oven where nitrogen gas is fed and the oxygen content is controlled below 0.1%, and the heating and cyclization reaction is carried out with the following temperature gradient.

Cyclization conditions:

1.Stay at 180°C for 30 minutes (heat up to 220°C in 30 minutes)

2.Stay at 220°C for 30 minutes (heat up to 280°C in 30 minutes)

3.Stay at 280°C for 30 minutes (heat up to 350°C in 30 minutes)

4. Stay at 350°C for 30 minutes (heat up to 370°C in 10 minutes)

5. Stay at 370°C for 10 minutes (cool down)

Subsequently, the cyclization rate was measured using the method for measuring the cyclization rate described above and the appearance was checked. The results are shown in Table 1.

Example 2

After pyromellitic dianhydride (PMDA) and 4,4'-oxydianiline (ODA) were reacted using N-methylpyrrolidone (NMP) as a solvent, a polyamic acid resin with a solid content of 15% was obtained. Add triethylamine and acetic anhydride to the resin as catalysts, use a coating machine to coat on a copper foil with a thickness of 18 microns and a width of 520 mm, and use hot air or an IR oven to evaporate the NMP solvent. The solvent content of the support resin is measured as 5.3% by weight, using a rewinding machine to wind the copper foil coated with polyamic acid resin on the steel pipe, the tension is controlled below 20kgf/ ^cm2 , and a smooth rod is inserted every 15 meters of winding while winding, and the coiling is done together. After winding for 100 meters, after the outermost circle is fixed with polyimide tape, remove the smooth bar to unwind the copper foil. Then move it into an oven where nitrogen gas is fed and the oxygen content is controlled below 0.1%, and the heating and cyclization reaction is carried out with the following temperature gradient.

Cyclization conditions:

1.Stay at 120°C for 30 minutes (heat up to 180°C in 30 minutes)

2.Stay at 180°C for 30 minutes (heat up to 250°C in 30 minutes)

3.Stay at 250°C for 30 minutes (heat up to 300°C in 30 minutes)

4. Stay at 300°C for 10 minutes (cooling down)

Subsequently, the cyclization rate was measured using the method for measuring the cyclization rate described above and the appearance was checked. The results are shown in Table 1.

Example 3 and 4

The same conditions as in Example 1 were carried out, but the volatile content of the resin was controlled to 3.3% by weight and 3.5% by weight in Example 3 and Example 4, respectively. The obtained results are shown in Table 1.

Comparative example 1

The conditions were the same as those described in Example 1, but the volatile content of the resin was controlled at 3.4% by weight and a 40-mesh iron mesh was used as a separator. The results obtained are shown in Table 1 below.

Comparative example 2

The same conditions as in Example 1 were carried out, but the volatile content of the resin was controlled at 3.7% by weight and an Upilex polyimide film was used as a separator. The results obtained are shown in Table 1 below.

Comparative example 3

The same conditions as in Example 1 were carried out, but the volatile content of the resin was controlled at 3.5% by weight and Kapton polyimide film was used as a separator. The results obtained are shown in Table 1 below.

Comparative example 4

The conditions were the same as those described in Example 1, but the volatile content of the resin was controlled at 11% by weight. The results obtained are shown in Table 1 below.

Table 1 Example 1 Example 2 Example 3 Example 4 Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 Copper foil length (m) 100 100 50 120 50 50 50 50 Copper foil width (mm) 250 250 520 250 250 250 250 250 Partition none none none none 40 mesh iron mesh Upilex Polyimide Membrane Kapton polyimide membrane none Volatile matter (weight%) 3.2 5.3 3.3 3.5 3.4 3.7 3.5 11 Cyclization rate of outer ring (%) >100% >100% 98% >100% >100% >100% >100% >100% Cyclization rate of inner ring (%) 98% 96% 96% 96% 98% 98% 98% 98% Exterior Good looking wrinkle-free Good looking wrinkle-free Good looking wrinkle-free Good looking wrinkle-free The iron mesh is deformed, so the appearance is poor and wrinkled The polyimide membrane has poor appearance due to swelling and deformation, and horizontal wrinkles The polyimide membrane has poor appearance due to swelling and deformation, and horizontal wrinkles The surface of the copper foil is stained with resin, and the appearance is not good

As shown by the data in Table 1, the method of the present invention in Examples 1 to 4 controls the volatile content of the resin below 10% by weight, and does not carry out cyclization reaction through spacers at the same time, and can obtain a polymer with good appearance and no wrinkles. imide film. On the contrary, in Comparative Examples 1 to 3, although the solvent content of the resin is also controlled below 10% by weight, because it utilizes spacers such as iron mesh or polyimide in the heating and cyclization process, due to the spacers in the The difference in thermal expansion coefficient between the copper foil and the heating process causes the appearance of wrinkles of the polyimide resin film formed by cyclization, which is not good. In Comparative Example 4, although there is no spacer, since the solvent content of the resin is higher than 10% by weight, during the cyclization process, the copper foil has resin sticking phenomenon and the appearance is not good.

From the above data, it can be seen that the novel cyclization method of polyimide of the present invention can obtain a polyimide resin metal foil soft film with no wrinkles, good appearance and excellent mechanical properties with high yield and high cyclization rate.

Claims (9)

1. the method for making of a polyimide, comprise make dicarboxylic anhydride and diamine reactant form polyamic acid after, by polyamic acid coating or mat molding method are coated on the support, remove again solvent by the volatile content of control polyamic acid below 10 weight %, and with tension control at 20kgf/cm ²After below reeling, enter high temperature oven, make the polyamic acid cyclodehydration become polyimide from 100 to 380 ℃ scope gradient-heated in the gradient increased temperature mode in batch formula mode.

2. method as claimed in claim 1, wherein dicarboxylic anhydride and diamine reactant are to carry out under catalyst exists according to circumstances.

3. method as claimed in claim 2, wherein this catalyst is to be selected from least a of triethylamine and diacetyl oxide or its mixture.

4. method as claimed in claim 1, wherein the volatile content of this polyamic acid is to be controlled at below 8% weight.

5. method as claimed in claim 1, wherein this support carrier is at least a tinsel that is selected from Kapton, Copper Foil, aluminium foil, stainless steel foil, nickel foil.

6. method as claimed in claim 5, wherein this support carrier is a Copper Foil.

7. method as claimed in claim 6, wherein this cyclization is to carry out in oxygen content is lower than the rare gas element of 1.0 volume %.

8. method as claimed in claim 6, wherein this cyclization is to carry out in oxygen content is lower than the rare gas element of 0.5 volume %.

9. method as claimed in claim 6, wherein this cyclization is to carry out in oxygen content is lower than the rare gas element of 0.1 volume %.