JP3002710B2 - Low particle-containing polyimide precursor, polyimide solution and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyimide precursor or a polyimide solution, and more particularly to a polyimide precursor or a polyimide solution having a low particle content and capable of obtaining a heat-resistant resin suitable as an optical material.

[0002]

2. Description of the Related Art Hitherto, polyimide has been widely used in the field of electronic materials as an excellent heat-resistant resin, and its application as an optical material has been evaluated based on its properties and accumulated processing techniques (Jornal of Lightwave Technology, vo
l. 6,1034 (1988)). When applying as an optical material,
Reduction of light loss is an important issue depending on the application, and its factors include absorption and scattering.

In general, polyimide resins are often colored yellow or brown, which causes absorption loss of visible light and may cause a problem in application to optical applications.
In response to this, development of a fluorine-containing polyimide resin that is transparent even in the visible light region has already been made, and the loss due to light absorption has been improved.

[0004] On the other hand, voids or particles cause light scattering loss, and the effect is evaluated for voids, but particles are not evaluated for electronic material grade (pore size 0.2 µm filter treatment) or higher (SPIE). Vol.682 Molecular and Polymer
ic Optoelectronic Materials: Fundamentals and Appli
cations 191 (1986)).

[0005] Low viscosity varnishes for coating relatively thin films used in the field of electronic materials usually have a pore size of 0.2.
A high-viscosity varnish suitable for thick film coating of about 5 μm or more, which has been subjected to a filter treatment with a pore size of 1 μm. When measuring the content of particles in these varnishes,
Particles of 0.3 μm or more are usually 10,000 to 20
000 particles / g or more, and particles having a particle size of 1 μm or more are usually 10 particles / g or less in a low-viscosity varnish.
Pcs / g or more.

[0006] The reduction of the content of particles in a solution by a filtration treatment is achieved by repeating the filtration with a filter having a smaller pore diameter more times.
However, it is clear that the treatment under such conditions requires a longer time, and since there is generally a logarithmic inverse relationship between the filtration flow rate of the liquid to be treated in the filter treatment and the viscosity thereof, a high This problem is particularly pronounced when the purpose is to produce a viscosity varnish.

[0007] Increasing the filtration flow rate in order to shorten the processing time can be achieved by increasing the filtration area or increasing the filtration pressure difference which is logarithmically proportional to the filtration flow rate. Rather, the latter is limited by the maximum pressure limit in filter use. At the same time, extension of the treatment time is not preferable from the viewpoint of the quality stability of the polyimide precursor solution at room temperature. That is, since the viscosity of the polyimide precursor solution changes with time even at room temperature, a high-viscosity solution of constant quality cannot be stably obtained.

Although the polyimide resin is widely used in the field of electronic equipment as a high heat-resistant insulating material, as described above, a high-viscosity varnish usually has 10,000 to 20,000 particles of 0.3 μm or more per particle. Since it contains particles of g or more, it was not always sufficient for application to optical materials.

[0009]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a high-viscosity polyimide precursor solution suitable for coating a thick film of about 5 μ or more, especially when a polyimide resin having excellent heat resistance is used as an optical material. At
An object of the present invention is to provide a polyimide or a polyimide precursor solution which substantially improves the problem of particles that cause light scattering, which is one of the causes of undesired light loss as an optical material.

[0010]

An object of the present invention is to provide a solution containing a polyamic acid, a derivative thereof, or a polyimide, wherein the content of particles having a particle size of 0.3 μm or more is 10000 particles / g or less. And found that the present invention was completed.

That is, when the relationship between the number of particles contained in the polyimide or the polyimide precursor solution and the loss based on the light scattering was examined, as expected, the dispersion of the measured data was large when the particle content was large. The scattering loss was large. As the particle content was reduced, the scattering loss tended to decrease.
When the number of particles having a size of 3 μm or more becomes 10,000 particles / g or less, and more preferably 5000 particles / g or less, the dispersion of the measurement data becomes sufficiently small, and the scattering loss is small, and the influence of the particle scattering loss is substantially improved. I found what I could do.

Therefore, the present invention has been made based on new findings on the relationship between the content of particles and light loss, and contains polyimide or a derivative thereof at a solid concentration of 3 to 60%, The solution viscosity is 1 to 1
A low-particle-containing polyimide solution having a particle size of 200 poise and a content of particles of 0.3 μm or more of 10,000 particles / g or less, and a polyamic acid or a derivative thereof, which is a precursor of polyimide, is solidified. A low-particle-containing polyimide precursor solution containing 3 to 60% as a partial concentration, a solution viscosity of 1 to 3000 poise, and a content of particles of 0.3 μm or more of 10,000 or less. It is.

In the present specification, a polyimide means a polymer having a repeating unit represented by the following formula (1):
The polyamic acid refers to a polyamide precursor having a repeating unit represented by the following formula (2) or a derivative thereof, and the polyamide precursor refers to a compound having a repeating unit represented by the following formula (3). Unless otherwise specified, copolymers are also included. Also, unless otherwise specified,
Diamine is a derivative thereof such as isocyanate,
Tetracarboxylic acid includes its derivatives such as acid anhydride, acid chloride, acid bromide, lower alkyl ester, etc., and diamine component also means a mixture of one or more different diamines. Means also a mixture of one or more different tetracarboxylic acids.

[0014]

Embedded image

(In the formula, R ¹ represents a divalent organic group, R ² represents a tetravalent organic group, and R ³ represents a lower alkyl group.) In a more preferred embodiment of the present invention, light loss due to scattering is provided. And a solution of a fluorinated polyamic acid, a derivative thereof, or a fluorinated polyimide, which has a feature of not only reducing the light loss but also reducing the light loss due to absorption in the visible light region having the widest use range. These can be obtained by using a fluorinated diamine or a fluorinated tetracarboxylic acid for either the diamine component or the tetracarboxylic acid component.

For example, JP-A-1-71737, JP-A-1-201170, and JP-A-2-110498 have excellent transparency, low refractive index, dielectric constant, and low water absorption. There is a polymer whose main component is a fluorine-containing polymer whose properties such as thermal expansion coefficient, refractive index and dielectric constant can be adjusted to desired values by polymerization.

In the polyimide or polyimide precursor solution of the present invention, the characteristics of the obtained polyimide can be adjusted by mixing and copolymerizing a diamine and a tetracarboxylic acid at a desired ratio. Specifically, as far as physical properties allow, known diamines, isocyanates, it is possible to copolymerize by introducing tetracarboxylic acids or derivatives thereof, and depending on the application, such diamines, isocyanates, It is necessary and preferable to carry out the modification using tetracarboxylic acid or a derivative thereof.

In the copolymerized polyimide or copolymerized polyimide precursor solution for such a purpose, the content of the diamine for the purpose of improving the properties is 50% or less, preferably 20% or less.
It is desirable that

The synthesis reaction is generally carried out in a solvent such as N-methylpyrrolidone, N, N-dimerformamide, N, N-dimethylacetamide, dimethyl sulfoxide, sulfolane, butyl lactone, phenol, cresol and halogenated phenol. The reaction is performed at a relatively low temperature around 100 ° C. or lower and around room temperature to obtain a solution of a polyamic acid or a derivative thereof, and is reacted at a relatively high temperature near 150 ° C. or higher near the boiling point of the solvent. Thus, a polyimide solution can be obtained.
The polyimide solution can also be obtained by allowing an acid anhydride and an organic base such as pyridine to act on a polyamic acid solution. In the polyimide or polyimide precursor solution thus obtained, the reaction solvent can be used as a varnish solvent as it is, or can be replaced with a different solvent.

Further, the polyimide or polyimide precursor can be precipitated and isolated by distilling off the solvent or adding a poor solvent, and can be dissolved again in a suitable solvent at a desired ratio or concentration to form a solution. It is possible to adjust the properties of the resulting polyimide or polyimide precursor solution.

One method of producing the solution of the present invention is to use a solvent, a diamine component and a tetracarboxylic acid component, which have been previously filtered through a filter having a pore size of 0.2 μm or less, to obtain a polyamic acid or a derivative thereof obtained by a polymerization reaction. Alternatively, a polyimide precursor containing 3 to 60% of polyimide as a solid content and having a solution viscosity of 1 to 1200 poise is further subjected to a filtration treatment with a membrane filter having a pore size of 0.2 μm or less. And a polyimide or a derivative thereof as a solid content concentration of 3
６０60%, the solution viscosity is 1-1200 poise, and the content of particles of 0.3 μm or more is 100
A method for producing a low-particle-containing polyimide solution or a polyimide precursor solution, which is not more than 00 particles / g (hereinafter referred to as Production Method 1). In addition, another manufacturing method is to dissolve a diamine component and a tetracarboxylic acid component or a derivative thereof in a solvent, and in a polyimide precursor solution obtained by a polymerization reaction, a rise in solution viscosity due to the polymerization reaction is moderate, The solution and the solution viscosity of the tetracarboxylic acid component or a derivative thereof when the component is 30 poise or less, a polyimide precursor solution comprising a combination of a diamine and a tetracarboxylic acid or a derivative thereof,
Under the condition that the solution viscosity is 30 poises or less, the particles are removed by a filtration treatment with a membrane filter having a pore size of 0.2 μm or less, and then a polyimide precursor solution having a viscosity of 30 poises or more is obtained by completing the polymerization reaction. Containing 3-60% as a solid concentration of a polyamic acid or a derivative thereof, which is a precursor of polyimide, and having a solution viscosity of 3%.
A method for producing a low-particle-containing polyimide precursor solution (hereinafter, referred to as Production Method 2), which has a particle size of 0 to 3000 poise and a content of particles of 0.3 μm or more is 10000 particles / g or less. .

The synthesis reaction of a polyimide or a precursor solution thereof using an ordinary diamine component such as 4,4'-oxydianiline which is a typical diamine of a polyimide precursor solution is a reaction which generates a large amount of heat. Yes, the solution viscosity rises in a relatively short time to reach the final viscosity. Therefore, particles of 0.3 μm or more in the solution of such a polyimide or its precursor are used for 100 μm.
In order to prepare a solution having a viscosity of 00 particles / g or less, a solution having the same viscosity as that of the product must be filtered through a filter having a pore size of 0.2 μm or less, and it is very difficult to prepare a high-viscosity solution.

Therefore, the present inventors have studied to reduce the load of this filtration as much as possible, and prepared a solvent, a diamine component and a tetracarboxylic acid component used for the synthesis in advance using a filter having a pore size of 0.2 μm or less. Thus, the invention of the production method 1 which can be applied industrially has been achieved by using the product treated with. In addition, it has been found that it is preferable to perform a pretreatment with a filter having a pore size of 1 μm or more before performing a filter treatment with a pore size of 0.2 μm or less, particularly in the case of a high-viscosity solution, from the viewpoint of the filtration treatment speed.

In the production method 1, since the polyimide or the precursor solution thereof is subjected to a filtration treatment after reaching the final viscosity,
This method is advantageous in that there is little variation in quality between the obtained products, and is characterized by being applicable to a relatively wide variety of polyimides or precursor solutions thereof.

The present inventors have further searched for a method for preparing a low-particle-containing polyimide or a precursor solution thereof which is industrially suitable, and studied the reaction between various diamines and tetracarboxylic acid. In the combination of diamine and tetracarboxylic acid, it was found that the polymerization reaction proceeded slowly even in the initial stage, and finally gave a high-viscosity solution having a large degree of polymerization. Was.

That is, an aromatic diamine having an amino group and a polyfluoroalkyl group or a polyfluoroalkoxy group as substituents on the same aromatic ring and a tetracarboxylic acid or a derivative thereof as starting materials are dissolved and mixed in a solvent. The resulting polyimide precursor solution gradually increases in solution viscosity after mixing, so that the period of low viscosity suitable for filter treatment is sufficiently long, and therefore, there is no change in quality before and after filter treatment, and polymerization after filter treatment is performed. It has been found that a uniform and high-viscosity polyimide precursor solution can be obtained by completing the reaction.

Although the reason why such a preferable phenomenon is exhibited is not clear, these diamines have a polyfluoroalkyl group or a polyfluoroalkoxy group which is an electron-withdrawing group on the aromatic ring to which the amino group is bonded. It is considered that the electron density of the compound decreases and the reactivity of the amino group decreases. In addition, these substituents are substituents which also have an advantageous effect of improving characteristics such as improvement of hygroscopicity and alkali resistance of the obtained polyimide.

Also in the production method 2, a solvent, a diamine component and a tetracarboxylic acid component used in the synthesis, which have been previously treated with a filter having a pore size of 0.2 μm or less, are used. It is preferable to perform a pretreatment with a filter having a pore size of 1 μm or more before performing the treatment from the viewpoint of the filtration processing speed.

In the production method of the present invention, particles are removed by subjecting a solution of a polyamic acid, a derivative thereof, or a polyimide to a filter treatment having a pore diameter of 0.2 μm or less in a clean atmosphere. 0.3 μm
In order to reduce the number of particles to 10000 particles / g or less, it is preferable that the filtration operation using a membrane filter is a continuous circulation treatment. In particular, in the production method 2, the low-particle-containing polyimide precursor solution having a low viscosity obtained by the filtration operation is subdivided into clean bottles at that time, and the polymerization reaction is completed in the clean bottle to increase the viscosity to a predetermined viscosity. Is more efficient.

The diamine and tetracarboxylic acid or their derivatives used in the low-particle-containing polyimide solution or its precursor solution of the present invention need not be particularly limited, but the polyimide or at least the polyimide precursor is obtained as a solution. Anything is fine. Among these, as a diamine that gives a preferred polyimide, the following general formula

[0031]

Embedded image

(Wherein, R is an alkyl group or an alkoxy group having or not having a side chain having 1 to 20 carbon atoms, and a part or all thereof is F, Cl or Br, respectively)
Is a substituent which may be R bonded to each aromatic ring
May be the same or different. X is a single bond, -O
-, - CO -, - C (CH 3) 2 -, - C (CF 3) 2 -,
—S—, —SO— or —SO ₂ —, and the X bonding between the aromatic rings may be the same or different. n is 0 or an integer of 5 or less, and each aromatic ring may be the same or different. l is 0 or an integer of 10 or less. ), And particularly preferred specific examples are m-phenylenediamine, diaminotoluene,
5-diaminoxylene, diaminodulene, 2,5-diaminoanisole, 2,5-diaminoacetophenone,
2,5-diaminobenzophenone, 3,3′-diaminobenzophenone, 3,4′-diaminobenzophenone,
2,5-diaminodiphenyl, benzidine, 1,1-bis (4-aminophenyl) ethane, 2,2- (4-aminophenyl) propane, 2,2- (4-aminophenyl) hexafluoropropane, 2, 2'-dimethyl-
4,4'-benzidine, 3,3 ', 5,5'-tetramethylbenzidine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 4,4'
-Diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulphoxide, 3,3'-diaminodiphenyl sulphoxide, 3,3'-diaminodiphenyl sulphone, 4,
4'-oxydianiline, 2,2-bis (4- (4-aminophenoxy) phenyl) propane, 2,2-bis (4- (4-aminophenoxy) phenyl) hexafluoropropane, 3,3'- Dimethyl-4,4'-diaminodiphenyl ether, 3,3'-dimethyl-4,4 '
-Diaminodiphenylmethane, diaminobenzotrifluoride, 1,4-bis (p-aminophenoxy) benzene, 4,4'-bis (p-aminophenoxy) biphenyl, N, N-bis (4-aminophenyl) methylamine, N, N-bis (4-aminophenyl) amine, N,
N-bis (4-aminophenyl) -n-butylamine,
4,4′-diaminoazobenzene, 3,3′-diaminoazobenzene, m-xylylenediamine, p-xylylenediamine, 2,5-diaminohalogenobenzene, 2,
4-diaminopentafluorophenoxybenzene, diaminopolyfluoroalkoxybenzene, 3,3′-dichloro-4,4′-benzidine, octafluoro-4,
4′-benzidine, diaminonaphthalene, 1,3-bis (4-aminophenyl) hexafluoropropane,
4'-bis (4-aminophenoxy) diphenyl sulfone, 3,3'-dimethyl-4,4'-benzidine, dimethylbenzidine, 4,4'-diamino-1,4-terphenyl, 1,4-phenylenediamine , 2-methyl-
1,4-phenylenediamine (2,5-diaminotoluene) Examples thereof include phenylenediamine, diaminotoluene, diaminoxylene, diaminodulene, and diamines or isocyanate compounds thereof which can be preferably used in Production Method 2 described below. .

The diamine component particularly suitable for applying the production method 2 is represented by the general formula:

[0034]

Embedded image

(Wherein R has a side chain having 1 to 20 carbon atoms)
An alkyl group or an alkoxy group having or not having
And part or all of them are F, Cl or Br, respectively.
Is a substituent which may be R bonded to each aromatic ring
May be the same or different. However, -NH_Twoof
At least one aromatic ring attached has at least one
Fluo having or not having a side chain having 1 to 20 carbon atoms
A loalkyl or fluoroalkoxy group is bonded.
You. X is a single bond, -O-, -CO-, -C (CH _Three)
_Two-, -C (CF_Three)_Two-, -S-, -SO- or -S
O_TwoAnd X bonding between the aromatic rings is the same.
But it may be different. n is 0 or an integer of 5 or less
May be the same or different for each aromatic ring.
No. l is 0 or an integer of 10 or less. )
Yes, specifically, 2-trifluoromethyl-1,4-
Phenylenediamine, 5-trifluoromethyl-1,3
-Phenylenediamine (3,5-diaminobenzotrif
Rulide), diaminobenzotrifluoride, 2-pen
Tafluoroethyl-1,4-phenylenediamine, 2-
Nanofluorobutyl-1,4-phenylenediamine, 5
-Pentafluoroethyl-1,3-phenylenediamine
, 5-Nanofluorobutyl-1,3-phenylenediamine
Min, 6-nanofluorobutyl-1,3-phenylene
Amine, diaminoperfluoroalkylbenzene, 5-
(3,3,2,2-tetrafluoropropyloxy)-
1,3-phenylenediamine, 2- (4,4,4,3,
2,2-hexafluorobutyloxy) -1,4-fe
Nilendiamine, 5- (4,4,4,3,2,2-hex
Safluorobutyloxy) -1,3-phenylenediamine
6- (4,4,4,3,2,2-hexafluorobu
Tyloxy) -1,3-phenylenediamine, 5-
(4,4,4,3,3,2,2-heptafluorobutyl
Oxy) -1,3-phenylenediamine, 6- (4,
4,4,3,3,2,2-heptafluorobutyloxy
B) -1,3-phenylenediamine, diaminopolyfur
Oroalkoxybenzene, 2,4-diaminopentaful
Orophenoxybenzene, 2,2-bis (4-aminophen
Enyl) hexafluoropropane, 2,2-bis (amido)
Nophenyl) hexafluoropropane, 2,2'-bis
(Trifluoromethyl) -4,4'-benzidine, 3,
3'-bis (trifluoromethyl) -4,4'-benzyl
Gin, bis (trifluoromethyl) benzidine, bis
(Perfluoroalkyl) benzidine, 2,2'-bis
(Trifluoromethyl) -4,4'-diaminodiphenyl
Ether, 3,3'-bis (trifluoromethyl)-
4,4'-diaminodiphenyl ether, bis (trif
(Fluoromethyl) diaminodiphenyl ether, 1,4-
Bis (4-amino-2-trifluoromethylphenoxy)
B) benzene, 4,4'-bis (4-amino-2-tri
Fluoromethylphenoxy) biphenyl, 2,2-bis
(4- (4-amino-2-trifluoromethylphenoxy)
Phenyl) propane, 2,2-bis (4- (4-a
Mino-2-trifluoromethylphenoxy) phenyl)
Hexafluoropropane, 2,2-bis (4- (amino
Perfluoroalkylphenoxy) phenyl) hexaf
Fluoropropane, 1,3-bis (2- (4-amino-2
-Trifluoromethylphenoxy) hexafluoro-2
-Propyl) benzene, 1,4-bis (2- (4-amido)
No-2-trifluoromethylphenoxy) hexafluoro
B-2-Propyl) benzene or their isocyanates
Nartrate can be exemplified.

In addition, the production method 2 can be applied to a combination of a diamine component containing 10% or more of these diamines and a tetracarboxylic acid component. It is particularly preferable that the content of these diamine components is 30% or more. .

On the other hand, tetracarboxylic acids or derivatives thereof to be combined with these diamines have the general formula

[0038]

Embedded image

(Wherein Y represents two —COOH groups, —CO
Cl group, an -COBr group, -COOR group, -CONH ₂ group, or one of -CO-O-CO- group. R is an alkyl group or an alkoxy group having or not having a side chain having 1 to 20 carbon atoms, and a part or the whole thereof is a substituent which may be F, Cl or Br.
R bonded to each aromatic ring may be the same or different. X is a single bond, -O -, - CO -, - C (CH 3)
_{2 -, - C (CF 3} ) 2 -, - S -, - SO- or -S
X which is O ₂ — and bonds between the aromatic rings may be the same or different. n is 0 or an integer of 5 or less, and each aromatic ring may be the same or different. l is 0 or an integer of 10 or less. ), Specifically, pyromellitic acid, trifluoromethylpyromellitic acid, bis (trifluoromethyl) pyromellitic acid, perfluoroalkylpyromellitic acid, bis (perfluoroalkyl) pyromellitic Acid, biphenyltetracarboxylic acid, benzophenonetetracarboxylic acid,
2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane, tetracarboxydiphenyl ether, tetracarboxynaphthalene, tetracarboxydiphenylsulfone, terphenyltetracarboxylic acid,
2,2-bis (3,4-dicarboxyphenyl) propane, 2,2-bis (4- (3,4-dicarboxyphenyloxyphenyl)) propane, 2,2-bis (4- (3,
4-dicarboxyphenoxyphenyl)) hexafluoropropane, 1,4-bis (3,4-dicarboxyphenoxy) benzene, 4,4′-bis (3,4-dicarboxyphenoxy) biphenyl and the like, and acid derivatives thereof Examples of the acid derivative include esters, acid chlorides, and acid anhydrides.

Further, in addition to the diamines and tetracarboxylic acids exemplified above, it is also useful to add and copolymerize other components. Such materials include diaminopolysiloxanes, diaminosilanes, tetracarboxypolysiloxanes, and tetracarboxysilanes in order to increase the adhesive strength of the polyimide film to the substrate. Specifically, the general formula

[0041]

Embedded image

(Wherein Q ¹ is a methyl, ethyl, propyl, phenyl or other monovalent organic group, Q ² is an alkylene group having 1 to 10 carbon atoms, a phenylene group or another divalent organic group) , P is 0 or a positive integer.), For example, 1,3-bis (3-aminopropyl) tetramethyldisiloxane, 1,4-bis (3-aminopropyldimethylsilyl) benzene, Bis (4-aminophenyl) diethylsilane, bis (3,4-dicarboxyphenyl) dimethylsilane, 1,3-bis (3,4-dicarboxyphenyl) tetramethyldisiloxane and the like can be mentioned.

The diamine component, the tetracarboxylic acid component or their derivatives can be used in combination of two or more kinds.

[0044]

The present invention will be described below in detail with reference to examples. Example 1 The following operations were performed in class 10000 (measured value 300 or less)
Class 1 in a clean room as required
A clean bench and a clean oven of 00 (measured value 10 or less) were used.

As a diamine component, 2,2′-bis (trifluoromethyl) -4,4′-benzidine was dissolved in chloroform, and a PTFE membrane filter (manufactured by Advantech) having a pore size of 0.2 μm was used. After treatment in an atmosphere, the number of particles contained in 10 ml of the solution was measured using a liquid particle counter (manufactured by Rion, KL-20-K). there were. Diamine solution filtered, solvent is distilled off under reduced pressure and dried,
Used for polymerization reaction.

As a tetracarboxylic acid component, 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride was dissolved in acetone, and treated and measured in the same manner. 0.3 μm
The number of the above particles was 10 or less. The solvent of the filtered tetracarboxylic anhydride solution was distilled off and dried under reduced pressure, and used for the polymerization reaction.

N, N-dimethylacetamide was similarly treated as a solvent to obtain N, N-dimethylacetamide having a particle number of 0.3 μm or more and 10 or less contained in 10 ml.

13.70 g of 2,2'-bis (trifluoromethyl) prefiltered as described above
-4,4'-benzidine and 19.05 g of 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane were dissolved in 185 g of N, N-dimethylacetamide, and the mixture was dissolved under a nitrogen atmosphere for about 36 hours. Reaction, solid content 15
% Polyamic acid solution was obtained. The viscosity of this solution at 25 ° C. was 110 poise (RHEOLAB manufactured by Physica).
The measurement was performed by the cone and plate method using MC20. The same applies hereinafter). PTFE with a pore size of 0.2 μm
The solution 1 was treated with dry nitrogen under a pressure of 2.7 kg / cm ² using a membrane filter (manufactured by Advantech) and diluted with a solvent using a liquid fine particle counter.
When the number of particles contained in 0 ml was measured,
The number of particles of 0.3 μm or more is 5330,
The content of particles having a particle size of 0.3 μm or more in terms of 1 g of the polyamic acid solution was 8,900.

This polyamic acid solution was spin-coated on a silicon wafer and held at 70 ° C. for 2 hours, 160 ° C. for 1 hour, and 300 ° C. for 1 hour to form a 10 μm polyimide film.

The light loss was measured by the streak light method using a 1 mW He-Ne laser. The light loss of the polyimide film obtained here was 0.7 dB / cm.
Met.

Examples 2 to 12 The light loss of a polyimide film prepared using a polyimide precursor solution adjusted under different conditions was evaluated in the same manner as in Example 1, and the results are shown in Tables 1 and 2. Indicated.

Comparative Example 1 A polyamic acid solution was prepared by a general operation in the same manner as in Example 1 except that the diamine component, the tetracarboxylic acid component and the solvent to be used were not subjected to a filter treatment in advance.
The film was treated with a PTFE membrane filter (manufactured by Advantech) having a pore size of 0.2 μm under a pressure of 5 kg / cm ² of dry nitrogen, and the light loss of the polyimide film formed in the same manner as in Example 1 was measured. The results are shown in Table 2.

Comparative Example 2 Light loss of a polyimide film prepared using a polyimide precursor solution adjusted under different conditions was evaluated in the same manner as in Example 1, and the results are shown in Table 2.

[0054]

[Table 1]

[0055]

[Table 2]

In the following Examples and Reference Examples, the diamine component, the tetracarboxylic acid component, and the solvent used were not previously reduced to particles by filter treatment.

Example 13 100.0 g of 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride was placed in a 3 L flat bottom separable flask equipped with a stirring spring and a nitrogen inlet tube.
25.2 mmol), 72.1 g of 2,2′-bistrifluoromethyl-4,4′-diaminobiphenyl (22
(5.2 mmol) was charged under a nitrogen atmosphere. 97,8 g of N, N-dimethylacetamide was added thereto,
Upon stirring with a motor blade, the monomer dissolved in 25 minutes, at which time the viscosity was 1 poise. Next, using a pump (SXW 1-822 manufactured by Nippon Feeder), a filter having a pore size of 0.1 μm (F-16 manufactured by Nippon Millipore, Inc.) was used.
WGV) for 15 minutes, the number of particles in the solution was 500 μm / 0.3 μm or more.
g, and the viscosity at this time was 2 poise.

Subsequently, the mixture was dispensed into 10 100 cc clean bottles, sealed and allowed to stand at room temperature. The viscosity of the solution after 36 hours was constant at 1200 poise for each bottle, and 0.3
The number of particles of μm or more was 520 / g.

Examples 14 to 20 The same polymerization reaction and filtration as in Example 13 were carried out using the raw material compositions shown in Table 3. The results are shown in Table 3 above.

[0060]

[Table 3]

REFERENCE EXAMPLE 1 80.3 g (1,1) of 2,2-bis (4- (4- (aminophenoxy) phenyl) hexafluoropropane was placed in a 1 L flat bottom separable flask equipped with a stirring spring and a nitrogen inlet tube.
54.8 mmol), N, N-dimethylacetamide 4
56.1 g was charged, and pyromellitic anhydride 33.8 g
(154.8 mmol) was added over 30 minutes. The monomer was dissolved 15 minutes after the completion of the addition. At this time, the viscosity was already 50 poise or more, and circulating filtration similar to that in Example 13 was practically impossible. No containing polyimide precursor solution was obtained.

REFERENCE EXAMPLE 2 50.3 g (248.5 m) of oxydianiline was charged into a 2 L flat bottom separable flask equipped with a stirring spring and a nitrogen inlet tube.
mol), 938.9 g of N, N-dimethylacetamide
And 54.2 g (248.5 mmol) of PMDA
Was added over 30 minutes. The monomer was dissolved 25 minutes after the completion of the addition, but the viscosity at this time was already 50 poise or more, and circulating filtration similar to that in Example 13 was practically impossible. No containing polyimide precursor solution was obtained.

REFERENCE EXAMPLE 3 243.1 g of 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride was placed in a 3 L flat bottom separable flask equipped with a stirring spring and a nitrogen inlet tube.
(547.2 mmol), 175.3 g of 2,2′-bistrifluoromethyl-4,4′-diaminobiphenyl
(547.5 mmol) under a nitrogen atmosphere.
2362.3 g of N, N-dimethylacetamide was added thereto, and the mixture was stirred with a motor blade.
Dissolved in minutes. The viscosity of the solution after 36 hours was 260 poise. The obtained solution was 3.0 kg by a nitrogen pressurizer.
/ Cm ² , and filtered through a 0.1 μm pore size filter (F-16 WGFV, manufactured by Nippon Millipore Co., Ltd.).
c Dispensed into clean bottles. Although the number of particles of 0.3 μm or more was a sufficiently low number of particles of 2000 particles / g, the solution viscosity varied from 65 to 220 poise between bottles, which was extremely inconvenient in preparing a polyimide film, and was not practical. It was not enduring.

[0064]

According to the present invention, it is possible to substantially improve the problem of particles that cause light scattering, which is a factor of undesired light loss in optical material applications. In particular, in the case of a fluorinated polyimide precursor or a fluorinated polyimide solution, a polyimide film formed therefrom is extremely useful in practice because it has characteristics such as heat resistance and low moisture absorption.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toru Matsuura 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Inside Nippon Telegraph and Telephone Corporation (72) Inventor Shigekuni Sasaki 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (56) References JP-A-3-72528 (JP, A) JP-A-4-288331 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08G 73/00-73/26 C08L 79/00-79/08

Claims (7)

(57) [Claims] 1. A polyimide or a derivative thereof containing 3 to 60% as a solid concentration and having a solution viscosity of 1 to 1200%.
A low-particle-containing polyimide solution which is poise and has a content of particles of 0.3 μm or more of 10,000 particles / g or less. 2. A polyamic acid or a derivative thereof, which is a precursor of polyimide, is contained in a solid content concentration of 3 to 60%, and has a solution viscosity of 1 to 1200 poise.
A polyimide precursor solution having a low particle content, wherein the content of particles having a particle size of not less than 1 μm is 10000 particles / g or less. 3. A polyamic acid or a derivative thereof, which is a precursor of polyimide, is contained in a solid content of 3 to 60%, and the solution has a viscosity of 30 to 3000 poise.
The content of particles of 3 μm or more is 10,000 particles / g
A low particle-containing polyimide precursor solution characterized by the following. 4. A polyamic acid, a derivative thereof or a polyimide obtained by a polymerization reaction using a solvent, a diamine component and a tetracarboxylic acid component which have been filtered through a filter having a pore size of 0.2 μm or less in advance as a solid content concentration. The polyimide precursor containing 3 to 60% and having a solution viscosity of 1 to 1200 poise and a polyimide solution is further subjected to a filtration treatment with a membrane filter having a pore size of 0.2 µm or less. 2. The method for producing the solution according to 2. 5. A polyimide precursor solution obtained by dissolving a diamine component and a tetracarboxylic acid component or a derivative thereof in a solvent and performing a polymerization reaction, the solution viscosity of the polyimide precursor solution slowly increases due to the polymerization reaction, and the diamine and the tetracarboxylic acid or A polyimide precursor solution comprising a combination of a diamine and a tetracarboxylic anhydride or a derivative thereof having a solution viscosity of 30 poise or less at the time of dissolving the derivative is prepared under the condition that the solution viscosity is 30 poise or less. 2
4. The polyimide precursor according to claim 3, wherein the particles are removed by a filtration treatment with a membrane filter of not more than μm, and then the polymerization reaction is completed to obtain a polyimide precursor solution having a viscosity of 30 poise or more. The method for producing the solution. 6. The low particle according to claim 1, wherein the diamine component or the tetracarboxylic acid component contains at least one kind of fluorine-containing diamine or tetracarboxylic acid or a derivative thereof. Containing solution. 7. An amino group having 1 to 20 carbon atoms in the same aromatic ring.
6. The method according to claim 5, wherein a diamine component containing 10% or more of a diamine to which a fluoroalkyl group or a fluoroalkoxy group is bonded is used.