JPH08217877A - Polyimide resin and polyimide film - Google Patents

Abstract

PURPOSE: To obtain the subject resin, suitably usable for TAB and FPC applications, comprising a specific compound and a linear diamine compound, excellent in heat resistance, having a high elastic modulus, low water absorption properties, a low hygroscopic expansion coefficient and a linear expansion coefficient so as to reduce warping and curling in use as a composite material with a copper foil. CONSTITUTION: This resin comprises a compound of the formula, preferably pyromellitic dianhydride and a linear diamine compound (preferably p- phenylenediamine). The mixing ratio of the compound of the formula to the pyromellitic dianhydride is preferably (100:0)-(10:90).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyimide resin and a polyimide film, more specifically, it has excellent heat resistance, high elastic modulus, low water absorption, low coefficient of hygroscopic expansion, and a composite material with a copper foil. TAB (Tape-Automa) having a coefficient of linear expansion suitable for reducing warpage and curl when used.
ted-Bonding) or FPC (Flexible-Printed-Circui)
t) Polyimide resin and polyimide film suitable for use.

[0002]

2. Description of the Related Art Polyimide resins have excellent heat resistance and electrical insulation properties, and have been widely used as industrial materials such as electrical equipment. The polyimide resin is
As described above, it has various excellent properties as compared with other polymers, but with the advancement of technology, the properties required for polyimide resins also become more advanced, and it is desired to have various performances depending on the application. ing.

Particularly, in recent years, the polyimide resin used has been strongly demanded to have dimensional stability because it is often used for electric / electronic materials which are more and more miniaturized and refined. ing. In particular, in film applications, it is desired that the dimensional change due to stress or temperature change be small, since it includes many processes in which stress is applied and temperature changes in the processing process. It is effective that the film has a high elastic modulus to reduce the dimensional change due to stress, and that the film has a small linear expansion coefficient to reduce the dimensional change due to the temperature change.

However, the applications in which the polyimide resin is used as a film are flexible printed circuit board applications,
Mainly used for base film for TAB, copper wire coating, etc., all of which are used in combination with metal such as copper or glass, so the coefficient of linear expansion is compared with metal such as copper or glass. If it becomes extremely small, the amount of expansion and contraction of the copper foil or the like due to heat becomes larger than the amount of expansion and contraction of the polyimide resin, so that warping and curling occur. In particular, in the case of a three-layer laminate of copper foil / adhesive / polyimide resin having an adhesive as an intermediate layer, the polyimide resin and the copper foil are separated from each other in the process of cooling from the bonding temperature of the copper foil or the curing temperature of the adhesive to room temperature. Curling occurs due to the difference in linear expansion coefficient.

This finding is based on, for example, Japanese Patent Laid-Open No. 05-0705.
No. 91 publication also discloses a high elastic modulus polyimide film having a linear expansion coefficient equivalent to that of a copper foil. However, copper and glass do not absorb moisture, but polyimide resin absorbs moisture and causes dimensional changes and deterioration of electrical characteristics.Therefore, it is more preferable that the polyimide resin has a coefficient of linear expansion slightly larger than that of the copper foil. 17 to 49 pp
It seems preferable to have a linear expansion coefficient of about m.

Further, it is important that the polyimide resin has a low water absorption coefficient and a low hygroscopic expansion coefficient from the viewpoint of electrical characteristics and dimensional stability. As described above, the polyimide resin is desired to have a high coefficient of linear expansion and a coefficient of linear expansion close to that of a material such as a metal such as copper foil or glass to be composited, in addition to a high elastic modulus, and a low hygroscopicity and a low hygroscopic expansion coefficient. Be done.

It is conventionally known that it is effective to use a monomer having high linearity as a raw material in order to obtain a polyimide resin having a high elastic modulus. For example, it has been found that a polyimide resin synthesized using only highly linear monomers such as pyromellitic dianhydride and paraphenylenediamine has a very high elastic modulus. However, the polyimide resin having such a structure is very brittle, and has a coefficient of linear expansion which is extremely small, so that curling occurs when it is bonded to a metal material such as a copper foil, which is not preferable in practice and has a large moisture absorption rate. turn into.

Therefore, it is disclosed in US Pat. No. 4,886,874 that the linear expansion coefficient can be made close to that of a copper foil with flexibility by copolymerizing a diamine compound with 4,4'-diaminodiphenyl ether. However, in the copolymer of pyromellitic dianhydride, paraphenylenediamine, and 4,4'-diaminodiphenyl ether shown therein, the elastic modulus becomes a little small when the coefficient of linear thermal expansion is brought close to that of copper foil, which is not practical. There was no improvement in water absorption.

Further, by using 4,4'-oxydiphthalic acid as an acid dianhydride and copolymerizing a linear diamine and a flexible diamine in combination with a diamine component, it is possible to realize a highly elastic polyimide film having low water absorption. Is disclosed in Japanese Patent Application Laid-Open No. 05-271410. However,
The polyimide film shown here has a smaller coefficient of linear expansion than that of the copper foil, and when the coefficient of linear expansion is close to that of the copper foil, the elastic modulus tends to decrease.

Further, it is known that it is effective to introduce a fluorine-containing monomer in order to reduce the water absorption of the polyimide resin. However, there are problems that the fluorine-containing monomer is expensive and that the polyimide resin containing fluorine has poor adhesiveness to a metal material such as copper foil. As described above, it has been difficult to realize all of a high elastic modulus, a linear expansion coefficient of an appropriate size, a low water absorption coefficient, and a low hygroscopic expansion coefficient in a polyimide resin.

[0011]

The present invention is excellent in heat resistance, has a high elastic modulus, a linear expansion coefficient of an appropriate size, a low water absorption rate,
An object of the present invention is to provide a polyimide resin and a polyimide film that realize all of the low hygroscopic expansion coefficients.

[0012]

In order to solve the above problems, the inventors of the present invention have earnestly studied the molecular structure of a polyimide resin, and as a result, an aromatic polyimide resin synthesized using a compound having a specific structure as a raw material has been found. The present invention has been completed by discovering that it has heat resistance, high elastic modulus, appropriate linear expansion coefficient, low water absorption coefficient, and low hygroscopic expansion coefficient. That is, the present invention is the first
And the following formula (I)

[0013]

Embedded image And a linear diamine compound.

Secondly, the present invention comprises a polyimide resin characterized by comprising a linear diamine compound and a mixture of the compound represented by the formula (I) and pyromellitic dianhydride in an arbitrary ratio. Regarding

The present invention thirdly relates to the use of paraphenylenediamine as the linear diamine compound.
Fourthly, the present invention relates to a polyimide film comprising the above-mentioned polyimide resin.

The present invention will now be described in detail. The polyimide resin of the present invention can be obtained from a polyamic acid polymer solution as its precursor, and this polyamic acid polymer solution can be produced by a known method. That is, it can be obtained by polymerizing in a polar organic solvent using substantially equimolar amounts of the tetracarboxylic dianhydride component and the diamine component.

The linear diamine used in the present invention does not contain a bending group such as an ether group, a methylene group, an isopropylidene group, a hexafluoroisopropylidene group and a carbonyl group in the main chain, and has a nitrogen atom of two amino groups. A diamine compound having a structure in which atoms and the carbon atoms to which they are attached are aligned. For example, the following compounds can be exemplified.

[0018]

Embedded image

[In the formula, X is F, Cl, Br, CH ₃ ,
Represents CH ₃ O or CF ₃ . In order to achieve the object of the present invention, the compound represented by the above formula (I) is used alone or as a mixture with pyromellitic dianhydride in any proportion as an acid dianhydride component, and a diamine component is used. It is essential to use a linear diamine compound as, it is possible to suppress the water absorption of the polyimide resin obtained by using this acid dianhydride low, using pyromellitic dianhydride or linear diamine compound It is possible to realize a high elastic modulus, and by combining them, a linear expansion coefficient of an appropriate size can be realized.

This is because the electron-donating ester group contained in the compound represented by the above formula (I) suppresses the polarizability of the imide group to a low level, and as a result, the amount of water molecules adsorbed on the imide group is reduced. It is considered to be the cause of low water absorption.

Further, by polymerizing with pyromellitic dianhydride or a linear diamine compound, the linearity of the molecule can be maintained and a high elastic modulus can be maintained. Furthermore, by combining these monomers, the flexibility and rigidity of the molecule are compatible with each other. As a result, it has a linear expansion coefficient of an appropriate size, a high elastic modulus, a linear expansion coefficient of an appropriate size, and a low expansion coefficient. The water absorption rate will be realized.

The ratio of the compound represented by the formula (I) and pyromellitic dianhydride as an acid dianhydride component may be mixed arbitrarily, but if the ratio of pyromellitic dianhydride is large, a film obtained is Since it becomes brittle, the mixing ratio of the compound represented by the formula (I) and pyromellitic dianhydride is 1
It is preferably in the range of 00:00 to 10:90. The smaller the proportion of pyromellitic dianhydride, the smaller the water absorption, and the larger the proportion of pyromellitic dianhydride, the higher the elastic modulus of the obtained polyimide resin and the smaller the coefficient of linear expansion. Therefore, by lowering the ratio of pyromellitic dianhydride when used in applications where low water absorption is particularly required, and by increasing the ratio of pyromellitic dianhydride when used in applications where high elastic modulus is required. A polyimide resin or polyimide film suitable for each application can be obtained.

It is more preferable to use para-phenylenediamine as the linear diamine. Since para-phenylenediamine does not have an aliphatic substituent or the like, it has excellent heat resistance and the molecules are efficiently oriented, so that the elastic modulus of the polyimide resin can be kept high.

The polyamic acid, which is the precursor of the polyimide resin of the present invention, has an average molecular weight of 10,000 to 1,000.
It is desirable to be 10,000. Average molecular weight is 10,
When it is less than 000, the finished polyimide film becomes brittle, and when it exceeds 1,000,000, the viscosity of the polyamic acid solution becomes too high, which is not preferable because it is difficult to handle.

Examples of the organic polar solvent used in the polyamic acid polymer formation reaction include sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, N,
Formamide solvents such as N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, N,
N-diethylacetamide and other acetamide solvents, N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone and other pyrrolidone solvents, phenol, o-, m- or p-cresol,
Examples thereof include xylenol, halogenated phenol, phenolic solvents such as catechol, hexamethylphosphoramide, γ-butyrolactone and the like, and it is desirable to use these alone or as a mixture, and further, aroma such as xylene and toluene. Group hydrocarbons can also be used in part.

There is no limitation on the order of addition of the raw materials in the synthetic method for obtaining the polyamic acid polymer, and various methods such as ordering, mixing and dividing may be added in combination. Further, this polyamic acid polymer is added to an organic polar solvent in an amount of 5-4.
It is preferably dissolved in 0% by weight, preferably 10 to 30% by weight from the viewpoint of handling. The method for synthesizing the polyamic acid polymer solution will be specifically described as follows.

Synthetic Method 1: An organic polar solvent and one or more linear diamines are placed in a container and stirred with cooling. Then, the compound represented by the formula (I) is added to the reaction solution in substantially equimolar amounts, and the mixture is cooled and stirred for preferably 20 minutes or more to obtain a polyamic acid copolymer solution.

Synthetic Method 2: An organic polar solvent and one or more linear diamines are placed in a container and stirred with cooling. Then, a mixture of the compound represented by formula (I) and pyromellitic dianhydride is added to the above reaction solution so that the number of moles of the acid dianhydride component and the number of moles of the diamine component are equal, and preferably, The mixture is cooled and stirred for 20 minutes or more to obtain a polyamic acid copolymer solution.

Synthesis method 3: An organic polar solvent and a compound represented by the formula (I) are placed in a container, and the mixture is cooled and stirred. Next, the linear diamine is added to the above reaction solution in excess of substantially equimolar amount, and the mixture is cooled and stirred for preferably 20 minutes or more. Further, pyromellitic dianhydride is added to the above reaction solution while gradually cooling and stirring so that the number of moles of the acid dianhydride component and the number of moles of the diamine component are equal, and a polyamic acid copolymer solution is added. To get

In order to obtain the polyimide resin or polyimide film of the present invention from the aromatic polyamic acid polymer solution thus obtained, a thermal method of thermally dehydrating and ring-closing or a chemical method of using a dehydrating agent is used. Any of these may be used, but the chemical method is preferable because the resulting polyimide resin and polyimide film have excellent mechanical properties such as elongation and tensile strength.

Examples of the dehydrating agent used here include aliphatic acid anhydrides such as acetic anhydride and aromatic acid anhydrides such as benzoic anhydride. Examples of the catalyst include aliphatic tertiary amines such as triethylamine, aromatic tertiary amines such as dimethylaniline, pyridine, picoline,
Examples include heterocyclic tertiary amines such as isoquinoline.

A method for producing a polyimide film will be specifically described. A solution prepared by mixing the above polyamic acid polymer or a solution thereof with a stoichiometric or more dehydrating agent and a catalytic amount of a tertiary amine is cast or coated on a drum or an endless belt to form a film. Approximately 1-9 at temperatures below ℃
Dry for 0 minutes to obtain a self-supporting polyamic acid film.
Then, this is peeled off from the drum or the endless belt to fix the ends. Then, the polyimide film of the present invention is obtained by imidizing by gradually heating to about 100 to 500 ° C., cooling and then removing the fixing of the end portions.

The polyimide resin and the polyimide film of the present invention can be compounded with various organic additives, inorganic fillers or various reinforcing materials. As such an additive, a commonly used additive can be appropriately used, but it is not particularly limited. Also, the amount thereof can be arbitrarily determined, and it can be added at any stage of the production process of the polyimide resin and the polyimide film.

INDUSTRIAL APPLICABILITY The polyimide resin and polyimide film of the present invention are excellent in heat resistance, have a high elastic modulus, a low water absorption rate and a low coefficient of hygroscopic expansion, and are useful as electric and electronic equipment applications, and particularly copper foil. TAB (Tape-Automated-Bonding) or FPC (Flexi) having a coefficient of linear expansion suitable for reducing warpage and curl when used as a composite material with
It is useful for ble-Printed-Circuit) applications, and can also be used as copper wire coating material, lead frame fixing tape, heat resistant adhesive tape, heat insulating material for aircraft and satellites, etc.

[0035]

EXAMPLES Next, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. Example 1 N, N-dimethylformamide and 1 equivalent of para-phenylenediamine were placed in a separable flask, stirred well at room temperature until the diamine compound was completely dissolved, and then cooled with ice. Next, the formula (I)

[0036]

[Chemical 4] 1 equivalent of the compound represented by
A dimethylformamide solution was obtained. The amount of N, N-dimethylformamide used was such that the monomer charge concentration of para-phenylenediamine and the compound represented by formula (I) was 18% by weight.

The polyamic acid solution thus obtained was cast-coated on a glass plate, dried at about 100 ° C. for about 15 minutes, the polyamic acid coating film was peeled from the glass plate, and the coating film was fixed on a supporting frame. The film was heated at about 150 ° C. for about 4 minutes, at about 250 ° C. for about 4 minutes, at about 350 ° C. for about 4 minutes, and dehydrated and ring-closed dried to obtain a polyimide film of about 75 μm.

The polyimide film thus obtained was examined for water absorption, elastic modulus, linear expansion coefficient, hygroscopic expansion coefficient, and warpage of a three-layer laminate of copper foil / adhesive / polyimide film. Regarding the warp, the quality of the warp was judged by visually observing a three-layer laminate of copper foil / adhesive / polyimide film (size 35 mm x 40 mm) left in an environment of 20 ° C and 65% RH for 48 hours. did. The results are shown in Table 1.

Example 2 N, N-dimethylformamide and 2 equivalents of paraphenylenediamine were placed in a separable flask, stirred well at room temperature until the diamine compound was completely dissolved, and then cooled with ice. Then, 1 equivalent of the compound of formula (I) is added to give 2
The mixture was cooled and stirred for 0 minutes. Then, 1 equivalent of pyromellitic dianhydride was gradually added, and the mixture was cooled and stirred for 20 minutes to obtain a N, N-dimethylformamide solution of polyamic acid. Example 1
The film was baked in the same manner as in 1. to obtain a polyimide film of about 75 μm.

The physical properties of the obtained polyimide film are as follows.
It is as shown in Table 1. Comparative Example 1 A separable flask was charged with N, N-dimethylformamide and 4,
After taking 1 equivalent of 4'-diaminodiphenyl ether and stirring well at room temperature until the diamine compound is completely dissolved,
Cooled with ice. Next, 1 equivalent of pyromellitic dianhydride was added, and the mixture was cooled and stirred for 40 minutes. A N, N-dimethylformamide solution of polyamic acid was obtained. Firing was performed in the same manner as in Example 1 to obtain a polyimide film of about 75 μm.

The physical properties of the obtained polyimide film are as follows.
It is as shown in Table 1. Comparative Example 2 N, N-dimethylformamide and 1 equivalent of para-phenylenediamine were placed in a separable flask, well stirred at room temperature until the diamine compound was completely dissolved, and then cooled with ice. Next, add 2 equivalents of pyromellitic dianhydride, and add 40
The mixture was cooled and stirred for a minute. Then 1 equivalent of 4,4'-diaminodiphenyl ether was added. Then cool and stir for 1 hour,
A N, N-dimethylformamide solution of polyamic acid was obtained.
Firing was performed in the same manner as in Example 1 to obtain a polyimide film of about 75 μm.

The physical properties of the obtained polyimide film are as follows.
It is as shown in Table 1. Comparative Example 3 A separable flask was charged with N, N-dimethylformamide, 2 equivalents of paraphenylenediamine and 1 equivalent of 4,4'-diaminodiphenyl ether, and well stirred at room temperature until the diamine compound was completely dissolved, and then cooled with ice. did. next,
3,3 ', 4,4'-benzophenone tetracarboxylic dianhydride 2
After adding an equivalent amount and cooling and stirring for 20 minutes, 1 equivalent of pyromellitic dianhydride was added and cooling and stirring for 1 hour to obtain a N, N-dimethylformamide solution of polyamic acid. Firing was performed in the same manner as in Example 1 to obtain a polyimide film of about 75 μm.

The physical properties of the obtained polyimide film are as follows.
It is as shown in Table 1. Comparative Example 4 N, N-dimethylformamide and 3 equivalents of paraphenylenediamine were placed in a separable flask, well stirred at room temperature until the diamine compound was completely dissolved, and then cooled with ice. Next, after adding 4 equivalents of 4,4'-oxydiphthalic anhydride and cooling and stirring for 20 minutes, 1 equivalent of 4,4'-diaminodiphenyl ether was added and cooling and stirring for 1 hour to obtain N, N of polyamic acid. -A dimethylformamide solution was obtained. Firing was performed in the same manner as in Example 1 to obtain a polyimide film of about 75 μm.

The physical properties of the obtained polyimide film are as follows.
It is as shown in Table 1. Comparative Example 5 A separable flask was charged with N, N-dimethylformamide and 4,
After taking 2 equivalents of 4'-diaminodiphenyl ether and stirring well at room temperature until the diamine compound is completely dissolved,
Cooled with ice. Next, 1 equivalent of the compound represented by formula (I) and 1 equivalent of pyromellitic dianhydride were added, and the mixture was cooled and stirred for 1 hour to obtain a N, N-dimethylformamide solution of polyamic acid. Firing was performed in the same manner as in Example 1 to obtain a polyimide film of about 75 μm. The physical properties of the obtained polyimide film are as shown in Table 1.

[0045]

[Table 1]

In Table 1, the characteristics of the polyimide film having the most general composition are shown as Comparative Example 1,
It is obvious that there is a drawback that the water absorption rate and the hygroscopic expansion coefficient are large. On the other hand, in Example 1 which is the present invention, it is apparent that the low water absorption coefficient and the low hygroscopic expansion coefficient can be realized without changing the elastic modulus and the linear expansion coefficient.

Further, in Comparative Examples 2 and 4, although the elastic modulus and the coefficient of hygroscopic expansion are excellent, the coefficient of linear expansion is small. In Comparative Example 3, the elastic modulus and the coefficient of hygroscopic expansion are excellent, but the water absorption is large. In Comparative Example 5, the water absorption rate is excellent, but the elastic modulus is low and the linear expansion coefficient is too large.
On the other hand, it is apparent that in Example 2 of the present invention, it is possible to realize a linear expansion coefficient and a low water absorption coefficient or a low hygroscopic expansion coefficient of an appropriate size while having a relatively high elastic modulus.

As described above, the polyimide film synthesized by polymerizing the compound represented by the formula (I) of the present invention and the linear diamine exhibits the property of imparting low water absorption to a general-purpose polyimide film, and has elasticity. A low water absorption rate can be realized without greatly changing the coefficient or linear expansion coefficient. Also,
By using a mixture of the compound represented by the formula (I) and pyromellitic dianhydride as the acid dianhydride component, it is possible to obtain a low water absorption property suitable for applications requiring a high elastic modulus such as a base film for TAB. A polyimide film can be realized.

[0049]

INDUSTRIAL APPLICABILITY The polyimide resin and polyimide film of the present invention are excellent in heat resistance and have all of a high elastic modulus, an appropriate linear expansion coefficient, a low water absorption coefficient and a low hygroscopic expansion coefficient.

Claims (4)

[Claims] 1. The following formula (I): A polyimide resin comprising a compound represented by and a linear diamine compound. 2. A polyimide resin comprising a compound represented by formula (I), pyromellitic dianhydride and a linear diamine compound. 3. The polyimide resin according to claim 1, wherein the linear diamine compound is paraphenylenediamine. 4. A polyimide film comprising the polyimide resin according to any one of claims 1 to 3.