JPH0129371B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field] The present invention relates to a novel method for synthesizing imide compounds such as polyimide or their precursors using a phenolic novolak resin as a solvent during synthesis. [Prior Art] Conventionally, polyimides have generally been produced by combining organic tetracarboxylic dianhydrides and organic diamines with basic polar compounds such as dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, and hexamethylphosphoramide. A polyimide precursor is synthesized by reacting in a solvent or an organic polar solvent such as a phenolic solvent such as m-cresol, p-cresol, phenol, m-chlorophenol, p-chlorophenol, or xylenol, and further, this polyimide precursor is It was synthesized by heating the compound to cause dehydration and ring closure. In this conventional polyimide synthesis method,
There are problems in that the organic polar solvents used are expensive, or even if they are inexpensive, they have a strong odor. Moreover, the above-mentioned organic solvent needs to be completely removed when forming a polyimide molded product, and if even a small amount of this remains, there is a problem that the properties of the polyimide molded product will be significantly impaired. [Objective and Summary of the Invention] Therefore, the inventors have developed a solvent that is inexpensive, odorless, and does not cause problems such as significant deterioration of the properties of the molded product even if it remains in the final molded product. As a result of intensive studies aimed at providing a method for synthesizing the polyimide used, it was discovered that a phenolic novolac resin can be a convenient solvent for achieving the above object, and the present invention was completed. That is, the present invention relates to a method for synthesizing an imide compound or its precursor, which is characterized by reacting an organic tetracarboxylic dianhydride or its derivative with an organic diamine in a phenolic novolac resin. [Effects of the Invention] According to the synthesis method of the present invention, an inexpensive and odorless phenolic novolac resin is used as a solvent, so imide compounds such as polyimide or their precursors can be synthesized at low cost and in a favorable working environment. can. Furthermore, the phenolic novolak resin used as a solvent in this synthesis method is generally used as a curing agent for epoxy resins and various additives, and can also be made into a cured molded product using hexamethylenetetramine or the like as a curing agent. For this reason, even when the imide compound such as polyimide or its precursor obtained by the synthesis method of the present invention is separated from the phenolic novolak resin contained in the reaction product and used for various materials, it can be used for various materials. Even if it is used with some residual phenolic resin, the properties of the resulting molded product will not be significantly impaired as in the past, and it can be used with various additives and cured as a mixture with the phenolic novolak resin. It has the advantage that it can be applied as an agent or as a molded article. This is an excellent feature that is significantly different from conventional polyimide synthesis methods, in which it was essential to remove the organic polar solvent. Further, the above-mentioned phenolic novolak resin has a melting point or softening point usually in the range of about 25 to 150°C, and is liquid, semi-solid or solid at room temperature. In the synthesis method of the present invention, the phenolic novolak resin in any of the above states may be used, unlike the organic polar solvents used in conventional polyimide synthesis methods, which are all liquid at room temperature. That is, in the present invention, it is possible to selectively use a phenolic novolak resin that is semi-solid or solid at room temperature and carry out the synthesis reaction in a heated and melted state, and such a synthesis method has not been employed in the past. This method can be said to be unprecedented and unique to this invention. [Structure of the Invention] The organic tetracarboxylic dianhydride used in the synthesis method of the present invention is represented by the following general formula. [However, R ₁ represents a tetravalent aliphatic residue or a tetravalent aromatic residue having at least two carbon atoms, and this aromatic residue is represented by one of the following structural formulas.

【formula】

【formula】

【formula】

【formula】

【formula】

[Formula] (where R ₂ is -O-, -S-,

【formula】

[expression] or

[Formula] R ₃ is a divalent aromatic organic group having 6 to 30 carbon atoms, R ₄ is a divalent organic group having 2 to 30 carbon atoms, such as -CH ₂ CH ₂ -, - CH ₂ CH(OH)CH ₂ −, −CH ₂
-C(CH ₃ ) ₂ -CH ₂ -, etc.)] Specific examples of this organic tetracarboxylic dianhydride include 3,3',4,4'-butanetetracarboxylic dianhydride, cyclo Pentanetetracarboxylic dianhydride, 5-(2.5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1.2-dicarboxylic anhydride, bicyclo[2.2.2]cactene-( 7)-2・
3,5,6-tetracarboxylic dianhydride, Aliphatic tetracarboxylic dianhydride, pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, etc. Acid dianhydride, 2.3.
6,7-naphthalenetetracarboxylic dianhydride,
1,2,4,5-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride thing, 2・2-bis [4
-(2,3-dicarboxyphenoxy)phenyl]
Examples include aromatic tetracarboxylic dianhydrides such as propane dianhydride and 4,4'-bis(2,3-dicarboxyphenoxy)diphenyl ether dianhydride. One type of these may be used alone, or two or more types may be used in combination. In addition, the organic tetracarboxylic dianhydride derivatives used in the synthesis method of this invention include:
Tetracarboxylic oxides, lower alkyl esters of the above tetracarboxylic dianhydrides,
Examples include polyhydric alcohol esters. Next, the organic diamine used in the synthesis method of this invention is represented by the following general formula. H ₂ N−R ₅ −NH ₂ [However, R ₅ represents a divalent aliphatic residue or a divalent aromatic residue having at least two carbon atoms, and this aromatic residue is, for example, It is represented by one of the following structural formulas.

【formula】

【formula】

【formula】

【formula】

(However, Q is a monovalent aliphatic residue, aromatic residue or halogen atom, X is -O-, -SO ₂ -,

[Formula] −CH ₂ −,

〔Example〕

Examples of this invention will be described below. In addition,
In the following, the logarithmic viscosity in N-methyl-2-pyrrolidone (hereinafter referred to as NMP) is
Logarithmic viscosity in sulfuric acid means the logarithmic viscosity measured at 30℃ at a concentration of 0.5g/100ml in NMP, and logarithmic viscosity measured at 30℃ at a concentration of 0.5g/100ml in sulfuric acid. means. Also,
IR spectrum (infrared absorption spectrum) is KBr
It was measured by the method. Furthermore, the term % hereinafter means % by weight. Example 1 300 g of phenol novolak resin (softening point: 78-86°C, viscosity at 150°C by Ubbelohde viscometer: 1.8-3.4 poise), which is a condensate of phenol and formaldehyde, was placed in a 500 ml separable flask, and nitrogen gas was added. Melt by heating to 180℃ while flowing
The temperature rose to . Next, while stirring the inside of this flask,
Add 14.88 g (0.06 mol) of 3'-diaminodiphenylsulfone and dissolve completely, then 2.
Gradually add 17.64 g (0.06 mol) of 2,3',4'-biphenyltetracarboxylic dianhydride, and then
The reaction was carried out at 180°C for 4 hours. In addition, after the above addition, approximately
After 20 minutes, water began to distill out of the system. After the above reaction, the phenolic novolac resin was poured into a flat vat while in a molten state and cooled.
The resulting reaction mixture was a brown transparent resin. This reaction mixture was dissolved in NMP, acetone was added thereto, and the mixture was separated into an acetone-soluble component and an acetone-insoluble component. This acetone-insoluble matter was dried under reduced pressure at 80° C. for 4 hours to obtain a powder. The logarithmic viscosity of this powder in NMP was 0.31. Also, the IR of this powder
In the spectrum (Figure 1), a characteristic absorption of the imide group at 1780 cm ^-1 and a characteristic absorption of the amide group at 1650 cm ^-1 were observed, and the yield was 99.8%. Next, the above powder was heat treated at 250°C for 4 hours, and then its ¹³ C NMR spectrum was examined, and the results are shown in Figure 3. This spectrum and the ¹³ C of polyimide obtained by the conventional method shown in Figure 4.
Since the NMR spectra are almost the same, it is clear that the powder is made of polyimide that has been almost completely imidized by the heat treatment. The above ^13C NMR spectrum is from JEOL.
The measurement was performed using an FX-60 type NMP device manufactured by JEOL LTD. using DMSO (dimethyl sulfoxide) _d6 as a solvent. Moreover, the polyimide obtained by the conventional method shown in FIG. 4 was synthesized as follows. That is, equal moles of 3,3'-diaminodiphenylsulfone and 2,3,3',4'-biphenyltetracarboxylic dianhydride were mixed in NMP at 30°C or below.
Synthesize a polyimide precursor by reacting for 240 minutes,
This was reprecipitated in water-acetone to obtain a polyimide precursor powder. This powder was heated to 180℃ for 1 hour.
Next, the mixture was heated at 250°C for 4 hours to obtain polyimide powder. This polyimide powder is soluble in NMP.
Logarithmic viscosity in NMP was 1.1. Furthermore, in the IR spectrum of this powder (Fig. 2), a characteristic absorption of imide groups was observed at 1780 cm ^-1 . Example 2 A reaction was carried out in the same manner as in Example 1 except that the reaction conditions were 130° C. for 3 hours to obtain a brown transparent resin-like reaction mixture. This reaction mixture is powdered,
Acetone was added to separate the acetone-soluble and acetone-insoluble components. This acetone-insoluble matter was heated to 80℃ for 4 hours.
After drying under reduced pressure for hours, a powder with a yield of 62.3% was obtained. This powder was soluble in NMP and had a logarithmic viscosity of 0.27 in NMP. In addition, in the IR spectrum of this powder (Figure 5), a characteristic absorption of the imide group is observed at 1780 cm ^-1 and a characteristic absorption of the amide group is observed at 1650 cm ^-1 . The imidization rate was approximately 74% based on the intensity of the absorption band. In addition, the ¹ H NMR spectrum of this powder (6th
Figure) and the ¹ H NMR spectrum of partially imidized polyamic acid obtained by the conventional method (Figure 7) were almost the same. From this, it is clear that the powder is made of partially imidized polyamic acid. The above ¹ H NMR spectrum is the same as above.
Measured using an NMP device. Further, the partially imidized polyamic acid according to the conventional method shown in FIG. 7 was synthesized as follows. That is, equal moles of 3,3'-diaminodiphenylsulfone and 2,3,3',4'-biphenyltetracarboxylic dianhydride were mixed in NMP at 30°C or below.
After reacting for 240 minutes, the reaction product was reprecipitated in water-acetone and the powder thus obtained was heated at 80°C.
The mixture was heated and dried under reduced pressure for 24 hours to obtain partially imidized polyamic acid. Example 3 300 g of phenol novolak resin (same as Example 1), 4,4'-diaminodiphenylmethane
A reaction was carried out in the same manner as in Example 1 using 11.88 g (0.06 mol) and 13.08 g (0.06 mol) of pyromellitic dianhydride. However, the reaction conditions are 180
℃ for 3 hours. This reaction gave a pale yellow, opaque, resinous reaction mixture. This reaction mixture was pulverized, and in the same manner as in Example 2, the acetone-insoluble matter was separated and dried under reduced pressure to obtain a powder. This powder was insoluble in NMP and had a logarithmic viscosity of 0.37 in sulfuric acid. Further, in the IR spectrum of this powder (Fig. 8), characteristic absorption of imide groups was observed at 1780 cm ^-1 , and almost no characteristic absorption of amide groups was observed at 1650 cm ^-1 . That is, this powder consisted of almost completely imidized polyimide, and the yield was 99.2%. Examples 4 to 9 Reaction was carried out in the same manner as in Example 1 using 300 g of phenol novolac resin (same as in Example 1) and 0.06 mol each of organic tetracarboxylic dianhydride and organic diamine shown in the table below. I went there. However, the reaction conditions were 180°C for 3 hours. Through this reaction, transparent resin-like reaction mixtures were obtained in Examples 4, 5, 8, and 9, and opaque resin-like reaction mixtures were obtained in Examples 6 and 7. Acetone-insoluble components were separated from each of the above reaction mixtures in the same manner as in Example 2 and dried under reduced pressure to obtain powder. If the powder obtained is soluble in NMP,
The logarithmic viscosity in NMP was measured and the powder was
In the case of insolubility in NMP, the logarithmic viscosity was measured in sulfuric acid and the results are shown in the table below. Furthermore, when the IR spectra of the above powders were measured, characteristic absorption of imide groups was observed at 1780 cm ^-1 in all powders, and no characteristic absorption of amide groups was observed at 1650 cm ^-1 . Based on these results, all of the above powders were identified as polyimide, and the yields thereof were as shown in the table below.

[Table] In the above table, a-BPDA refers to 2,3,3',4'-biphenyltetracarboxylic dianhydride, and BTDA refers to 3,3',4,4'-benzo Phenonetetracarboxylic dianhydride, PMDA
pyromellitic dianhydride, DAM 4,4'-diaminodiphenylmethyl, 3.
3'-DDS means 3,3'-diaminodiphenylsulfone, 4,4'-BAPP means 2,2'-bis(4-aminophenoxyphenyl)propane,
4,4'-BAPS means 4,4'-di(4-aminophenoxy)diphenyl sulfone, and DDE means 4,4'-diaminodiphenyl ether. Example 10 Phenolic novolak resin obtained by condensation reaction of a 1:1 molar ratio mixture of m-cresol and phenol with formaldehyde in a 500 ml separable flask (softening point 92-102°C, measured by Ubbelohde viscometer) (viscosity 1-3 poise at 150℃)
300g was added and heated to melt while flowing nitrogen gas, and the temperature was raised to 180°C. Next, 8.32 g (0.042 g) of 4,4'-diaminodiphenylmethane was added to the flask while stirring.
mol) and dissolve completely, then 3.
19.32 g (0.06 mol) of 3', 4, 4'-benzophenone tetracarboxylic dianhydride was gradually added, and the mixture was then reacted at 180°C for 4 hours. Note that after the above addition
After 20 to 30 minutes, water began to distill out of the system. After the above reaction, the phenolic novolac resin was poured into a flat vat while in a molten state and cooled. The resulting reaction mixture was a brown transparent resinous material. Acetone-insoluble matter was separated from this reaction mixture in the same manner as in Example 2 and dried under reduced pressure to obtain polyimide powder with a yield of 97.8%. This powder was insoluble in NMP and had a logarithmic viscosity of 0.12 in sulfuric acid. Also,
The IR spectrum (Figure 9) of the above reaction mixture shows
Characteristic absorption of imide group was observed at 1780 cm ^-1 , and 1650
Almost no characteristic absorption of the amide group was observed at cm ^-1 . Example 11 The amount of 4,4′-diaminodiphenylmethane used
The amount of 3,3',4,4'-benzophenonetetracarboxylic dianhydride used is 11.88g (0.06 mol).
The reaction was carried out in the same manner as in Example 10 except that the amount was changed to 13.52 g (0.042 mol) to obtain a brown transparent resin-like reaction mixture. Acetone-insoluble matter was separated from this reaction mixture in the same manner as in Example 2 and dried under reduced pressure to obtain polyimide powder with a yield of 98.2%. This powder was insoluble in NMP and had a logarithmic viscosity of 0.09 in sulfuric acid. The IR spectrum (Figure 10) of this reaction mixture shows
Characteristic absorption of imide group was observed at 1780 cm ^-1 , and 1650
No characteristic absorption of the amide group was observed at cm ^-1 . Example 12 300 g of phenol novolac resin (same as in Example 1), 7.32 g of 2,4-tolylenediamine
(0.06 mol) and 9.66 g (0.03 mol) of 3,3',4,4'-benzophenonetetracarboxylic dianhydride
The reaction was carried out in the same manner as in Example 1 using .
The reaction conditions were 180°C for 4 hours. This reaction gave a brown transparent resinous reaction mixture. Acetone-insoluble matter was separated from this reaction mixture in the same manner as in Example 2 and dried under reduced pressure to obtain imide powder with a yield of 98.6%. This powder was soluble in NMP and had a logarithmic viscosity of 0.02 in NMP. Also,
The weight average molecular weight of this powder was measured by GPC method and was found to be 530. Furthermore, in the IR spectrum of this powder (Fig. 11), a characteristic absorption of imide groups was observed at 1780 cm ^-1 , and no characteristic absorption of amide groups was observed at 1650 cm ^-1 . Example 13 300 g of phenol novolac resin (same as in Example 1), 4.08 g (0.03 mol) of silylene diamine
A reaction was carried out in the same manner as in Example 1 using 17.64 g (0.06 mol) of 2,3,3',4'-biphenyltetracarboxylic dianhydride. The reaction conditions are
The temperature was 180°C for 4 hours. This reaction gave a light brown transparent resinous reaction mixture. Acetone-insoluble matter was separated from this reaction mixture in the same manner as in Example 2 and dried under reduced pressure to obtain imide powder with a yield of 97.8%. This powder was soluble in NMP and had a logarithmic viscosity of 0.08 in NMP. Also,
The weight average molecular weight of this powder was determined to be 704 by GPC method. Further, in the IR spectrum of this powder (Fig. 12), a characteristic absorption of imide groups was observed at 1780 cm ^-1 , and no characteristic absorption of amide groups was observed at 1650 cm ^-1 .

[Brief explanation of drawings]

Figure 1, Figure 5, Figure 8, Figure 9, Figure 10,
Figures 11 and 12 are characteristic diagrams showing the infrared absorption spectra of imide compounds or their precursors obtained by the method of the present invention, respectively, and Figure 2 shows the infrared absorption spectrum of polyimide obtained by the conventional method. The characteristic diagram, Figure 3, shows the ^13C characteristics of the imide compound obtained by the method of this invention.
FIG. 4 is a characteristic diagram showing ^{the 13} C NMR spectrum of polyimide obtained by the conventional method, and FIG. 6 is a characteristic diagram showing ^{the 1} H NMR spectrum of the imide compound precursor obtained by the method of the present invention.
FIG. 7 is a characteristic diagram showing a ¹ H NMR spectrum of a partially imidized polyamic acid obtained by a conventional method.

Claims (1)

[Scope of Claims] 1. An organic tetracarboxylic dianhydride or its derivative and an organic diamine are mixed in a phenolic novolak resin having a melting point or softening point of 25°C or higher, and a temperature higher than the melting point or softening point of the resin. A method for synthesizing an imide-based compound or its precursor, characterized by reacting at temperature. 2. The phenolic novolak resin has a melting point or softening point of 35 to 150°C and is in a semi-solid or solid form at room temperature, and the organic tetracarboxylic dianhydride or its derivative and the organic diamine are added to the phenolic novolak resin. A method for synthesizing an imide compound or a precursor thereof according to claim 1, wherein the reaction is carried out at a temperature higher than the melting point or higher than the softening point.