JPS60212428A - Preparation of prepolymer solution of polyimide resin - Google Patents

Abstract

PURPOSE:A prepolymer solution containing an excessive amount of an aromatic acid dianhydride and another prepolymer solution containing an excessive amount of aromatic diamine are separately filtered, then mixed at the equivalent ratio to effect the reaction to give the titled solution free from impurities, because the above-mentioned two solutions have low viscosity so as to be easily filtered. CONSTITUTION:When equivalent amounts of an aromatic di-acid anhydride of formula I (Ar is benzene ring, formula II; X is -O-, -CH2-, -S-, -SO2-) and an aromatic diamine of the formula: H2N-Ar'-NH2 (Ar' is same as Ar) are allowed to react with each other, a prepolymer containing 5-50wt%, preferably 20-30wt% excessive amount of the dianhydride and another prepolymer containing the diamine in about same level of excessive amount are previously prepared and filtered separately, then they are mixed at an equivalent ratio to effect their reaction to give the objective prepolymer solution of polyamic acid of formula III.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preparing a prepolymer used in a polyimide resin represented by the following formula (1v).

It is. However, Z is 10, -C-, -CH2-, -
3-.

-8°2--o. , 8 The polyimide resin of the above formula (1v) compound is known as a heat-resistant resin and is represented by formula (1) 6 [wherein Ar is the same as Ar in formula (IV)] aromatic A solution of a vertical anhydride and an aromatic diamine represented by the formula (II), H2N -Ar -Nl2 (II) [in the formula, AI is the same as AI in the formula (JV)] is reacted by mixing equivalent amounts. It is obtained by heating a prepolymer solution of a polyamic acid represented by the formula (1), [wherein Ar is the same as the case of Ar and Ar in the formula GV].

However, both the above-mentioned formula (1) compound and formula (II) compound are extremely poorly soluble in organic solvents, and the formula (I) compound and formula (It) compound can be mixed in a solvent using a conventional method. When the resulting solution of the compound of formula (I[) is adjusted to a concentration of about 25% required as a product, it becomes a prepolymer with extremely high viscosity.

The polyimide resin represented by formula (1) is used in substrate adhesives and films for computers, heat-resistant electronic circuits whose reliability is highly dependent on aircraft, and the like.

For example, in the compound of formula (1), Ar is a benzene ring, and in the compound of formula (If), A1' is a benzophenone ring, that is, pyromellitic dianhydride (PMDA), and 4.4'- The polyimide reactant with oxydianiline (ODA) is a trademark of Dupont.
Alternatively, benzophenone tetracardionic dianhydride (hereinafter referred to as BTDA) or a mixture of this and PMDA is used as the compound of formula (1), and diaminobenzophenone (hereinafter referred to as DABP) is used as the compound of formula (1). Polyimide reactants using diamines such as (m-DABP) and (p-DABP) are LAR
It is known by names such as C-2 and LARC-3 (NASA).

However, there are no suitable good solvents that can dissolve these dianhydrides and diamines, and therefore, for example, m-D
When using a reaction product of ABP and BTDA (LARC-2) as an adhesive, it has conventionally been used as an adhesive (2-methoxyethyl)ether, N,N'-dimethylformamide, N-
These raw materials are placed in a polar organic solvent selected from methyl-2-pyrrolidone, dimethyl sulfoxide, tetrahydrofuran, 1°3-dioxane, 1,4-dioxane, 1,4-bis-(2-methoxyethoxy)ethane, etc. A high viscosity polyamic acid prepolymer face was used, which was added in an equivalent amount with stirring and reacted to dissolve it to about 25%.

In the fest prepared by such conventional methods, the raw material powder contains particles (solid impurities) such as metal powder mixed in during the manufacturing of the raw material. Ethyl) ether is known as the best solvent, but even a 25% by weight prepolymer varnish using these solvents has a molecular weight of 100,000 to 600,000 at room temperature or below.
Because the prepolymer cannot be heated due to its extremely high viscosity, in the range of 0.00 cp, it is difficult to remove dust even with special filters.

When the face adjustment liquid is used in electronic circuits that require high precision, the solid impurities contained in the bo1 imide resin obtained by heat molding not only cause bubbles in the resin, but also cause damage to the electronic circuit. This causes a short circuit, leading to a decrease in the precision of the molded product.

The present invention provides polyamic acid Prevo I prepared by a conventional method.
As a result of studies to solve this drawback of J-mer, we have arrived at the method of the present invention.

That is, the present invention provides [where Ar, Ar is a benzene ring, or -@''[1
: It's Lee. However, Z is -Q-, -C-.

δ -CH2+, -S -, -S 02- are shown. When preparing a prepolymer solution of a polyamic acid corresponding to a polyimide resin represented by ], a dianhydride-excess prepolymer solution with an excess of 5 to 50% by weight and a diamine-excess prepolymer solution were separately prepared in advance, and each was filtered. This is a two-step method for preparing a polyimide resin prepolymer solution, which is characterized in that the two solutions are then mixed in an equivalent ratio and reacted.

Figure 1 shows BTDA for the dianhydride and m-DAB for the diamine.
255A diglyme solution (bis(2-
Viscosity of polyamic acid prepolymer obtained in methoxyethyl ether solution) and raw material BTDA/m-DAB
It is a relationship diagram with P molar ratio.

η on the vertical axis is the N at 0.5 f/dt of the polyamic acid powder isolated from the diglyme prepolymer reaction solution;
This is a value obtained by measuring the viscosity in a N' dimethylacetamide solution (using an Ubbelohde viscometer).

The horizontal axis represents the molar ratio of BTDA (!: m-DABP)
1 (i.e., droplet volume response), the left side shows the excess amount of m-DABP, and the right side shows the transition of the excess amount of BTDA.

As can be seen from the η value curve in Figure 1, BTDA/m −
When D A B P is equimolar, the η value increases rapidly, and BT
If either DA or m-DABP is present in excess, the η value drops sharply. This tendency is particularly strong in the case of m-DABP. There is a correlation between the η value of the prepolymer and the viscosity of the solution mixed and reacted, so the viscosity of the prepolymer solution reacted at an excess molar ratio slightly deviated from the center point of the equimolar ratio suddenly decreases, and this If you miss both at the P stage,
It was found that the dust mixed in the prepolymer solution derived from the raw materials can be easily removed.Moreover, if the filtered prepolymer solutions of both types are mixed and adjusted so that they are finally equivalent, the viscosity of the obtained prepolymer solution can be reduced. It was found that the properties were equal to or larger than those obtained by the conventional method, and the physical properties were also excellent even when heat-molded into polyimide resin. The present invention has been completed based on these findings.

The reaction adjustment of the prepolymer of the present invention is carried out as follows.

n% of either aromatic acid anhydride or aromatic diamine in an organic polar solvent in an amount such that the molar ratio is 1:1.
A reduced amount of liquid A and conversely an n% increased liquid B are prepared separately in advance.

In that case, n can be arbitrarily selected from the range of 5 to sk, but in order to obtain a uniform solution of the viscosity of each A liquid and B liquid and each produced prepolymer for the next filtration, n
is preferably in the range of 20 to 30. When n is 5 or less, normal filtration is difficult, and when n is 50 or more, when the final equivalent amount of prepolymer is adjusted, only a non-uniform solution is obtained, and unreacted substances tend to remain in the polyamic acid prepolymer. There is. The amount of organic polar solvent to be used is determined as appropriate depending on the solubility of the raw materials, and the total amount is determined depending on the final varnish concentration. In addition, when preparing liquids A and B, the raw material to be used in excess for both liquids A and B is put into a solvent to form a slurry liquid, and the raw material to be used in small quantity is divided into several portions under stirring. It is best to add slowly and cumulatively to react. The reaction temperature is 0°C to room temperature, preferably 1
The temperature is 0-25°C. When the mixing is completed while maintaining this temperature, an aging reaction is further performed at this temperature for 1 to 20 hours, and then in order to remove the solid impurities contained in the A
Filter the solution and B solution.

In the present invention, both A and ζ'B have low viscosity at this stage, so filtration is easy, and ordinary solid-liquid separation means are sufficient.

In order to make the final polyamic acid prepolymer from the A and B solutions obtained in this way, the respective solutions are weighed and mixed so that they are equivalent. Preferably, the increase in the viscosity of the mixed solution is stabilized at 10 to 25°C. The aging reaction is further carried out for 1 to 20 hours until the product is a polyamic acid varnish.

Examples will be shown below, in which "parts" indicate "parts by weight".

Example Solution A and solution B were prepared as follows.

A separate flask was charged with 10-60 parts (0,050 mole) of m-DABP and 65.67 parts of bis(2-methoxyethyl) ether, and the inside of the flask was replaced with nitrogen.
Cooled to 0°C. BTDAll, 27 without stirring thoroughly.
(0.035 mole) was slowly charged in three portions every hour. After the charging was completed, the mixture was stirred and aged at 10° C. for 15 hours to obtain a deep red-tinged transparent liquid.

The viscosity of liquid A at 10°C was 110 cp.

B liquid BTDA 20.93 parts (0,065 mole) and bis(2-methoxyethyl) ether 94.68 parts were charged in the same manner as for A liquid, replaced with nitrogen, cooled, and then muffled with stirring.
-DABPlo, 60 parts (0-050 mole) was slowly charged in 3 portions every hour. 10℃ after charging
The mixture was stirred and aged for 15 hours to obtain a clear yellow solution. The viscosity of this B solution at 10°C was 1.070 cp.

Both solutions A and B obtained as described above were filtered separately through a glass filter using Toyo Roshi 5A, which was easy to carry out, and a considerable amount of solid matter adhered to the filter paper.

Then, 29.18 parts of liquid A and 42.0 parts of liquid B were filtered.
7 parts were accurately weighed into a separate flask and stirred at 10°C under a nitrogen stream. The viscosity rose rapidly during stirring, and after settling down in about 1 hour, it was further aged for 15 hours to form a deep red polyamic acid prepolymer (LARC-
A 25% bis(2-methoxyethyl) ether solution of 2) was obtained. The viscosity of this varnish is 194,500c at 10℃
The physical properties of the thermoformed polyimide were also excellent. (The solution viscosity was measured with a Tokyo Keiki B-type viscometer (BH type)) Comparative Example 21.2 parts (0-050 mole) of m-DABP and 160-35 parts of bis(2-methoxyethyl) ether were charged into a separate flask. Then, the mixture was purged with nitrogen and cooled to 10°C. 32.20 parts (0,050 mole) of BTDA was charged in 4 portions every hour, and after the charging was completed, it was stirred and aged at 10°C for 15 hours to produce a deep red polyamic acid prepolymer (LA).
A 25% bis(2-methoxyethyl) ether solution of RC-2) was obtained. The viscosity of this varnish is 169.0 at 10°C.
At 00 cp, black fine suspended matter that was thought to be contained in the raw material was observed, so filtration was attempted in the same manner as in the previous example, but it could not be easily filtered.

[Brief explanation of drawings]

Figure 1 shows benzophenone tetracarboxylic dianhydride (BTDA) and m-diaminobenzophenone (m-D
N of polyamic acid obtained in a 25% solution of bis(2-methoxyethyl) ether using
, N' dimethylacetamide solution (0.5t/dl)
It is a relationship diagram between the viscosity of the inside and the BTDA/m-DABP molar ratio. Patent applicant Mitsui Toatsu Chemical Co., Ltd.

Claims (2)

[Claims] (1) Equation (1). However, 2 is -o-, -c-, -cH2-. 1 -S-, -5O2- is shown. ] An aromatic diacid anhydride represented by the formula (n) -S-, -5O2- is shown. ] Obtained by a mixed reaction, formula (1) [wherein, Ar, Ar is A in formula (1) and formula (11)
r, has the same meaning as Ar. ] When preparing a prepolymer solution of polyamic acid represented by the following, a 5 to 50% by weight excess diacid anhydride excess prepolymer solution and a diamine excess prepolymer solution were separately prepared, and after filtering each, the equivalent ratio was determined. A two-step method for preparing a polyimide resin prepolymer solution, which comprises mixing and reacting these two solutions. (2) each of the excess prepolymer solutions is 20-30″
A method according to claim (1) in which the amount is in excess of % by weight.