JPH0553819B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a heat-resistant resin using pyromellitic dianhydride, benzophenonetetracarboxylic dianhydride, P-phenylene diamine, and 4,4'-diaminodiphenyl ether as raw materials. . The purpose of this is that the cured resin that has been imidized through ring-closing treatment has a significantly high thermal decomposition onset temperature, and that it has the same wear resistance, chemical resistance, electrical insulation, film properties, and mechanical properties as a polyimide resin. The object of the present invention is to provide a heat-resistant resin that has excellent adhesive properties, flexibility, etc., and is useful as an electrical insulating material, a coating, an adhesive, a paint, a molded product, a laminate, a fiber, or a film material. Conventionally, diamines containing at least two carbon atoms have been used to prepare diamines containing a tetravalent group containing at least two carbon atoms, and in which at most two of the carbonyl groups of the dianhydride group are Any one of the carbon atoms in the group
reacting with the attached tetracarboxylic dianhydride, thereby forming a polyamic acid product, which is then heated to a temperature above 50°C to convert the polyamic acid product to a polyimide. It is well known that polyimides can be prepared by The produced polyimides are characterized in that they have repeating units consisting of diamine and tetracarboxylic dianhydride groups, and furthermore, the diamine group has a divalent group containing at least two carbon atoms. and the tetracarboxylic dianhydride group contains a divalent group containing at least 2 carbon atoms, in which case at most two of the carbonyl groups of the dianhydride group are carbon atoms of the tetravalent group. It is also known that it is characterized by being bonded to any one of the atoms. Furthermore, as the tetracarboxylic dianhydride, pyromellitic dianhydride,
Benzophenonetetracarboxylic dianhydride, 2,
3,6,7-naphthalenetetracarboxylic dianhydride, 3,3',4,4'-diphenyltetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2 , 2',3,3'-diphenyltetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxydiphenyl)propane dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride Anhydride, bis(3,4-dicarboxydiphenyl)ether dianhydride, ethylenetetracarboxylic dianhydride, naphthalene-1,2,4,5-
Tetracarboxylic dianhydride, naphthalene-1,
4,5,8-tetracarboxylic dianhydride, decahydronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,
5,6,7-hexahydronaphthalene-1,2,
5,6-tetracarboxylic dianhydride, 2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,7-dichloronaphthalene-
1,4,5,8-tetracarboxylic dianhydride,
2,3,4,7-tetrachloronaphthalene-1,
4,5,8-tetracarboxylic dianhydride, phenanthrene-1,8,9,10-tetracarboxylic dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride, pyrrolidine- 2, 3,
4,5-tetracarboxylic dianhydride, pyrazine-
2,3,5,6-tetracarboxylic dianhydride,
2,2-bis(2,5-dicarboxyphenyl)
Propane dianhydride, 1,1,-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,1-
Bis(3,4-dicarboxyphenyl)ethane dianhydride, bis(2,3-dicarboxyphenyl)
Methane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, bis(3,4,-dicarboxyphenyl)sulfone dianhydride, benzene-1,2,3,4-tetracarboxylic dianhydride thing,
1,2,3,4-butanetetracarboxylic dianhydride, thiophene-2,3,4,5-tetracarboxylic dianhydride, etc. are used, and diamines such as m-phenylenediamine and p-phenylenediamine are used. Nylene diamine, 4,4'-diaminodiphenylpropane,
4,4'-diaminodiphenylmethane, benzidine, 4,4'-diaminodiphenyl sulfide,
4,4'-diaminodiphenylsulfone, 3,3'-
Diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ether, 2,6-diaminopyridine, bis(4-aminophenyl)phosphine oxide, bis(4-aminophenyl)-N-methylamine, 1,5-diaminonaphthalene , 3, 3'-
dimethyl-4,4'-diaminobiphenyl, 3,
3'-dimethoxybenzidine, 2,4-bis(β-
Amino-t-butyl)toluene, bis(p-β-
Amino-t-butylphenyl) ether, p-bis(2-methyl-4-aminopentyl)benzene, p-bis(1,1-dimethyl-5-aminopentyl)benzene, m-xylylene dimian, p
-xylylenediamine, bis(p-aminocyclohexyl)methane, ethylenediamine, propylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, 3-
Methylheptamethylenediamine, 4,4-dimethylheptamethylenediamine, 2,11-diaminododecane, 1,2-bis(3-aminopropoxy)
Ethane, 2,2-dimethylpropylenediamine,
3-methoxyhexamethylene diamine, 2,5-
Dimethylhexamethylenediamine, 5-methylnonamethylenediamine, 1,4-diaminocyclohexane, 1,12-diaminooctadecane, 2,5
-diamino-1,3,4-oxadiazole, etc. have also already been used. However, electronics, OA equipment,
In the fields of robotics, nuclear power, aerospace, and other so-called advanced technology industries, there is a strong demand for equipment to be highly integrated, lighter, thinner, and smaller, and ultra-precise in harsh operating environments. There has been a strong demand for high heat resistance,
Until now, nothing had been found that had a thermal decomposition onset temperature of 480°C or higher. For example, Du
Polyimide resin varnish Pyre manufactured by Pont (USA)
The thermal decomposition onset temperature of cured ML is only 400℃. The present inventors have conducted intensive research with the aim of increasing the thermal decomposition initiation temperature to 480°C or higher while maintaining the excellent properties of polyimide resin. 1 to 20 mol% of phenotetracarboxylic dianhydride and P-
99-60 mol% of phenylene diamine and 1-40 mol% of 4,4'-diaminodiphenyl ether are reacted under anhydrous conditions in an inert gas atmosphere in an organic polar solvent at 0-100°C. In addition, they discovered a completely new fact that a polyamic acid product with an intrinsic viscosity of 0.5 to 2.5 and a highly heat-resistant polyimide resin having a thermal decomposition initiation temperature of a cured product after imidization of 480 to 580°C was discovered, and the present invention was completed. This is what we have reached. That is, the present invention is characterized by the fact that, as a result of a detailed study of the various factors that affect the thermal decomposition initiation temperature, new findings have been obtained that, together with the resin structure, the resin polymerization degree has a significantly large effect. Various efforts have been made to improve heat resistance. That is, the first method is to increase the stability of the bonds contained in the resin, or in other words, the energy of the bonds as much as possible. The heat resistance of aliphatic chain resins consisting only of single bonds is extremely poor. This means that the bond energy of a single bond is, for example, C-C (80Kcal/
mol) and C-N (62 Kcal/mol). On the other hand, the bond energies of double bonds and triple bonds are, for example, C=C (142Kcal/mol), C≡C
(186Kcal/mol), C=N (121Kcal/mol), C≡
N (191 Kcal/mol) is much larger. Therefore, in order to improve heat resistance, it is necessary to introduce multiple bonds, aromatic rings, etc. into the main chain of the resin. Since aromatic rings and heterocycles are stabilized by resonance, they are considered to be advantageous in further improving heat resistance. The second method is to introduce an aromatic ring with good symmetry into the main chain of the resin to increase the melting point and glass transition point. Generally, there is a difference between the melting point (hereinafter referred to as Tm), the enthalpy of melting (hereinafter referred to as △Hm), and the entropy of melting (hereinafter referred to as △Sm).
There is a relationship of =△Hm/△Sm. Here, △Hm is a quantity related to intermolecular force, and △Sm is a quantity mainly related to the bendability and symmetry of molecules. Tm is △ than △Hm
It is known that it is largely influenced by Sm, and that the more para-bonded aromatic rings there are in the main chain of the resin, the smaller ΔSm and the higher Tm. That is, in order to improve heat resistance, it is necessary to introduce an aromatic ring with good symmetry. In this way, the theory of improving heat resistance has almost been completed, and the molecular structure of heat-resistant resins has been designed based on this theory. However, the heat resistance referred to here is the so-called thermal decomposition temperature,
Most of the research focused on the temperature at which decomposition occurs violently. In the present invention, the problem is not the conventional thermal decomposition temperature, but the thermal decomposition initiation temperature, which is the temperature at which decomposition begins. Until now, there has not been much research on this subject. As a result of detailed study of the thermal decomposition temperature and the thermal decomposition start temperature, the present inventors have found that a material having a high thermal decomposition temperature does not necessarily have a high thermal decomposition start temperature. Of course, in order to improve heat resistance, molecular design based on theory is fundamental, and it is clear that the molecular structure has the greatest effect.On top of that, we discovered that the degree of resin polymerization is a significant factor affecting the thermal decomposition initiation temperature. did. In other words, this is a completely new finding that the smaller the degree of tree polymerization, the higher the thermal decomposition initiation temperature. Generally, the higher the resin polymerization degree, the higher the thermal decomposition temperature, and this is theoretically clear. However, it was not known until now that the temperature at which thermal decomposition begins decreases. The thermal decomposition initiation temperature referred to herein refers to the temperature at which weight loss begins due to heating as determined by differential thermal balance analysis. Although the reason for the lower thermal decomposition onset temperature is not clear,
Side chain functional groups with weak binding energy in molecular structure,
Alternatively, in addition to the natural thermal decomposition in which single bonds are broken in the main chain, volatile components such as water, unreacted raw materials, and residual solvents generated when polyamic acid is ring-closing by methods such as heating may reduce the degree of polymerization. It is thought that this is because large resins generally have high melt viscosity, so they cannot be volatilized and are trapped in the cured resin. The degree of resin polymerization is mainly determined by
It is determined by the molar ratio of the raw materials, tetracarboxylic dianhydride and diamine, and increases as the molar ratio approaches 1, but even if the molar ratio is constant, reaction conditions such as raw material purity, water content, reaction It can be adjusted by adjusting the temperature, reaction time, amount of reaction terminator, reaction solvent system, etc. The method of the present invention comprises pyromellitic dianhydride 99-
80 mol% and 1-20 mol% of benzophenonetetracarboxylic dianhydride and P-phenylenediamine99
~60 mol% and 1 to 40 mol% of 4,4'-diaminodiphenyl ether are reacted under anhydrous conditions in an inert gas atmosphere in an organic polar solvent at 0 to 100°C. The intrinsic viscosity of the product is
0.5 to 2.5, and the thermal decomposition initiation temperature of the cured product after imidization is 480 to 580°C.
The pyromellitic dianhydride in the present invention has the effect of increasing the thermal decomposition initiation temperature. The higher the proportion of pyromellitic dianhydride, the higher the temperature at which thermal decomposition begins, but the resin becomes more rigid. The benzophenonetetracarboxylic dianhydride in the present invention has the effect of improving the rigidity of the resin. The higher the proportion of benzophenone tetracarboxylic dianhydride, the better the rigidity will be, but the target thermal decomposition initiation temperature will be lower. The content of tetracarboxylic dianhydride is preferably 20 mol% or less. P-phenylenediamine in the present invention has the effect of increasing the thermal decomposition initiation temperature. The higher the proportion of 4,4'-diaminodiphenyl ether in the diamine component in the resin, the better the rigidity will be, but the target thermal decomposition initiation temperature will be lower, so P-phenylenediamine should be 60 mol%. On the other hand, 4,4'-diaminodiphenyl ether is 40
It is preferably less than mol%. The solvent of the reaction system in the present invention has a dipole moment whose functional group does not react with pyromellitic dianhydride and benzophenonetetracarboxylic dianhydride, or with P-phenylene diamine and 4,4'-diaminodiphenyl ether. It is an organic polar solvent with In addition to being inert to the system and solvent to the product, the organic polar solvent must be solvent to at least one, preferably both, of the reaction components. Typical solvents of this type include N,N-dimethylformamide, N,N-dimethylacetamide, N,
N-diethylformamide, N,N-diethylacetamide, N,N-dimethylmethoxyacetamide, dimethylsulfoxide, hexamethylphosphamide, N-methyl-2-pyrrolidone, pyridine, dimethylsulfone, tetramethylenesulfone, dimethyltetramethylenesulfone These solvents may be used alone or in combination. In addition, non-solvents such as benzene, benzonitrile, dioxane, butyrolactone, xylene, toluene, and cyclohexane are used in combination as solvents, and can be used as dispersion media for raw materials, reaction regulators, or to control the volatilization of solvents from products. It is used as a coating agent, film smoothing agent, etc. It is generally preferred that the present invention be carried out under anhydrous conditions. This is because pyromellitic dianhydride and benzophenonetetracarboxylic dianhydride are ring-opened by water and may be inactivated to stop the reaction. For this reason, it is necessary to remove both the moisture in the raw materials and the moisture in the solvent. However, in order to adjust the progress of the reaction and control the degree of resin polymerization, water is sometimes intentionally added. Further, the present invention is preferably carried out in an inert gas atmosphere. This is to prevent oxidation of P-phenylenediamine and 4,4'-diaminodiphenyl ether. Dry nitrogen gas is generally used as the inert gas. The reaction in the present invention can be carried out in the following various ways. The diamine and the tetracarboxylic dianhydride are mixed in advance, and the mixture is added little by little to the organic solvent while stirring. This method is relatively advantageous in exothermic reactions such as those for polyimide resins. Conversely, there is also a method of adding a solvent to a mixture of diamine and tetracarboxylic dianhydride while stirring. A commonly used method is to dissolve only the diamine in a solvent and add tetracarboxylic dianhydride to it in a proportion that allows the reaction rate to be controlled. It is also possible to dissolve the diamine and the tetracarboxylic dianhydride separately in a solvent and slowly add the two solutions in a reactor. Furthermore, it is also possible to prepare in advance a polyamic acid product containing an excess of diamine and a polyamic acid product containing an excess of tetracarboxylic dianhydride, and then further react them in a reactor. The temperature of the reaction is 0
~100°C is preferred. This is because if the temperature is below 0°C, the reaction rate is slow, and if it is above 100°C, the produced polyamic acid gradually starts the ring-closing reaction. Usually, the reaction is carried out at around 20°C, and as it is an exothermic reaction, cooling is required. The degree of polymerization of polyamic acid can be controlled in a planned manner. The closer the moles of tetracarboxylic dianhydride and diamine are to equimolar, the higher the degree of polymerization becomes. When the amount of either raw material increases by 5% or more, the degree of polymerization decreases significantly. Generally, it is common practice to use 1 to 3% more of one raw material in terms of workability and processability. In order to control the degree of polymerization, it is also possible to end-block with phthalic anhydride or aniline, or add water to ring-open one of the acid anhydride groups to inactivate it. The polyamic acid product according to the invention preferably has an intrinsic viscosity of 0.5 to 2.5. If it is lower than 0.5, it is good for improving the thermal decomposition start temperature, but the thermal decomposition temperature becomes low and the film forming property also decreases. If it is higher than 2.5, the film will have excellent formability, but the temperature at which thermal decomposition starts will decrease. When used, the polyamic acid product produced by the method of the present invention has the adhesion and adhesion properties of various silane coupling agents, borane coupling agents, titanate coupling agents, aluminum coupling agents, and other chelate coupling agents. Improvers, various solvents, and flow agents may be added, and in addition to these, ordinary acid curing agents, amine curing agents,
Small amounts of polyamide curing agents and curing accelerators such as imidazole and tertiary amines may be added, as well as flexibility agents and viscosity modifiers such as polysulfides, polyesters, low molecular weight epoxies, talc, clay, etc.
Fillers such as mica, feldspar powder, quartz powder, and magnesium oxide, colorants such as carbon black and ferroncyanine blue, flame retardants such as tetrabromophenylmethane and tributyl phosphate, antimony trioxide, and barium metaphoate. Small amounts of flame retardant aids, such as, may also be added, and the addition of these opens up many applications. Specifically, the present invention is used as a coating film for protecting the surfaces of various electronic equipment, and as a heat-resistant insulating film for forming multilayer wiring thereon. For example, it is a wiring structure for electronic circuits such as semiconductors, transistors, linear ICs, hybrid ICs, light emitting diodes, LSIs, and super LSIs. Furthermore, it is used for other purposes such as imparting heat resistance to various materials, preventing microwaves, and preventing radiation. Examples include waveguides for computers, nuclear equipment, interior materials for X-ray equipment, etc. Next, it is used as a high-temperature coating varnish, such as electric wire coating, magnet wire, dipping coating for various electrical parts, and protective coating for metal parts.It is also used as an impregnating varnish for glass class, fused silica cloth, graphite fiber, and poron. Used for fiber impregnation, radar dome,
Used in printed circuit boards, radioactive waste containers, turbine blades, spacecraft and other structures that require high-temperature performance and excellent electrical properties. In addition, as a molding material, graphite powder, graphite fiber, molybdenum disulfide, and polytetrafluoroethylene are added and used to produce self-lubricating sliding surfaces, such as piston rings, valve seats, bearings, seals, etc. It is also used to make jet engine parts, high-strength structural molded parts, etc. by adding glass fiber, graphite fiber, or boron fiber. Furthermore, it is used as a high-temperature adhesive for bonding electrical circuit parts and structural parts of spacecraft. The present invention will be explained below with reference to Examples. Example 1 1 mole of purified anhydrous diamine listed in Table 1 was placed in a 4-necked flask equipped with a thermometer, a stirrer, and a dry nitrogen gas inlet, and anhydrous N,N-dimethyl was added to this. A mixed solvent of 95% acetamide and 5% anhydrous diacetone alcohol was added and dissolved in an amount sufficient to make the solid content of the total raw materials 15%. Next, 1 mol of the purified anhydrous tetracarboxylic dianhydride listed in Table 1 was added little by little with stirring, while cold water at about 15°C was circulated to cool the rapid exothermic reaction from the outside. . After the addition, the internal temperature was set at 20°C and stirring was continued for 10 hours to advance the reaction, but the viscosity of the reaction system gradually increased. During this process, samples were taken one after another and their characteristics were determined using the method described below. That is, a portion of the collected sample was poured into water to precipitate polyamic acid, filtered, and then dried under reduced pressure. 0.5g of the product in N-
It was dissolved in 100 ml of methyl-2-pyrrolidone, and its intrinsic viscosity was measured at a temperature of 30°C using an Ubbelohde capillary viscometer. Further, another part of the collected sample was diluted with N-methyl-2-pyrrolidone to a concentration of 5% and cast onto a glass plate while rotating a wheeler at 150 rpm/min. When this is heated under reduced pressure at 80°C, then 150°C, 250°C, and 350°C for 30 minutes each time, dehydration and ring closure occur, resulting in imidization, and a film with a thickness of 2 to 3 μm is completed. The thermal decomposition start temperature and thermal decomposition temperature of the film were measured using a differential thermal balance analyzer at a heating rate of 5° C./min in air.
The results are shown in Table 1.

【table】

[Table] As shown in Table 1, the thermal decomposition temperature increases as the intrinsic viscosity increases. This has been known for a long time and is no surprise. However, when looking at the thermal decomposition initiation temperature, the smaller the intrinsic viscosity, the higher it becomes. This fact was completely unknown until now and is surprising. It is not clear why the smaller the intrinsic viscosity, the higher the temperature at which thermal decomposition begins, but it is due to the inherent heat that breaks the side chain functional group, which has a weak bond energy in the molecular structure, or the single bond in the main chain. In addition to decomposition, volatile components such as water, unreacted raw materials, and residual solvents generated when polyamic acid is ring-closed by heating or other methods cannot be volatilized due to the high melt viscosity of resins with a high degree of polymerization. It is thought that this is because the particles are trapped in the cured resin without being absorbed. In addition, as shown in Table 1, the thermal decomposition starting temperature is 480℃.
Compounds that can maintain the above are pyromellitic dianhydride (working numbers No. 1, 2, 3, 4), 2, 3,
Tetracarboxylic dianhydride component of 6,7-naphthalenetetracarboxylic dianhydride (Working No. 6, 7, 8) and p-phenylenediamine (Working No.
No. 1, 6) and m-phenylenediamine (Execution number
No. 2, 7) and 2,7-diaminonaphthalene (Working No. 3, 8) are the main diamine components, and these compounds have a benzene ring and a fused benzene ring in their structures, respectively. limited to those that Among them, those containing a benzene ring are better, but this is because the chemical reactivity of fused benzene rings is somewhat low, and the molecular arrangement during heat curing is not done in an orderly manner due to structural masking. It is thought that this is because of this. Furthermore, among those containing a benzene ring, when p-phenylenediamine and m-phenylenediamine are compared, p-phenylenediamine is superior. This is considered to be due to the thermodynamically obvious reason that the entropy change of p-bonds is smaller than that of m-bonds. Furthermore, as is clear from Table 1, the film properties are better as the intrinsic viscosity increases. This fact has been known for a long time. Furthermore, it can be seen that compounds having a flexible single bond in their molecular structure, ie, benzophenone tetracarboxylic dianhydride and 4,4'-diaminodiphenyl ether, are excellent. However, on the other hand, it is inferior in heat resistance. Example 2 According to Example 1, pyromellitic dianhydride was selected as the tetracarboxylic dianhydride component, and p-phenylenediamine was selected as the amine component, which had the highest thermal decomposition initiation temperature, and the tetracarboxylic acid had the best film properties. Benzophenonetetracarboxylic dianhydride was selected as the dianhydride component, and 4,4'-diaminodiphenyl ether was selected as the amine component.
The reaction was carried out in the same manner as in Example 1 using the charging ratios shown in the table, and the characteristics thereof were measured. Second result
Shown in the table.

【table】

【table】

[Table] According to Table 2, those having thermal decomposition start temperatures of 480°C or higher are Example Nos. 1 to 4, 6 to 9, and 11 to 14. Among the tetracarboxylic dianhydride components, the charging ratio of benzophenone tetracarboxylic dianhydride is
More than 20 mol% (Execution number No. 16, 17, 18, 19,
20), the temperature at which thermal decomposition starts falls below 480℃. Next, among the diamine components, when the charging ratio of 4,4'-diaminodiphenyl ether exceeds 40 mol% (Execution No. 5, 10, 15, 20), the thermal decomposition initiation temperature reaches 480 °C. It disappears. As a result, in order to set the thermal decomposition initiation temperature to 480℃, pyromellitic dianhydride in the tetracarboxylic dianhydride component must be
It can be seen that it is necessary to make the content of p-phenylenediamine in the diamine component 80 mol% or more, and 60 mol% or more. Film properties are closely related to intrinsic viscosity, and it is considered that the film cannot be used unless the intrinsic viscosity is 0.5 or more. Further, those having an intrinsic viscosity of more than 2.5 have excellent film properties by themselves, but the thermal decomposition start temperature becomes lower than 480°C. This shows that the intrinsic viscosity must be between 0.5 and 2.5. Example 3 A polyamic acid product having an intrinsic viscosity of 1.5 was obtained using the method of Example 2 and the raw material charging ratios listed in Table 3. This product was diluted with N-methyl-2-pyrrolidone to a concentration of 20% by weight, and was poured using a spinner to a thickness of approximately 10 μm onto the surface of a silicon semiconductor device on which a microcircuit was formed. It was extended. This was heated to 80℃, then 150℃, 250℃, and 350℃.
An imidized resin film was created by heating for 30 minutes at a time. The performance of this film is shown in Table 3.

[Table] Example No. 1 in Table 3 is a polyimide resin containing only pyromellitic dianhydride and p-phenylenediamine. Although it has excellent heat resistance and electrical properties, it is one of the highest in the resin's molecular structure.
Because the proportion of aromatic rings in the unit is too large, the resin is rigid, making it difficult to use such a film in various mechanical shocks or in environments with rapid changes in temperature and humidity. Further, the shrinkage during curing is extremely large, and the coating on the surface of an electronic circuit element on which a fine circuit is formed may break or damage the circuit due to the shrinkage, resulting in a lack of reliability in practical use. Furthermore, in Table 3, Examples Nos. 6, 8, and 9 used a large amount of benzophenone tetracarboxylic dianhydride or 4,4'-diaminodiphenyl ether, which was outside the scope of the present invention. Only the film properties are excellent, but
The temperature at which thermal decomposition begins does not reach 480℃, and the withstand voltage is low.
Such polyimide resins cannot withstand the high temperatures that occur during vermetic sealing of devices, and cannot be applied to power transistors that are loaded with high bias. In contrast, implementation number No. in Table 3.
2, 3, 4, 5, and No. 7 are according to the present invention, and are tetracarboxylic acids consisting of 99 to 80 mol% of pyromellitic dianhydride and 1 to 20 mol% of benzophenone tetracarboxylic dianhydride. A dianhydride is reacted with a diamine consisting of 99 to 60 mol % of p-phenylene diamine and 1 to 40 mol % of 4,4'-diaminodiphenyl ether. As is clear from these results, the higher the proportion of benzophenonetetracarboxylic dianhydride in the tetracarboxylic dianhydride, the lower the thermal decomposition onset temperature, but it remains above 480°C, and the electrical properties and film properties are excellent. ing. Furthermore, as the proportion of 4,4'-diaminodiphenyl ether in the diamine increases, the temperature at which thermal decomposition begins decreases, as mentioned above, but it remains above 480°C, and the electrical properties and film properties are excellent. Furthermore, the more 4,4'-diaminodiphenyl ether is present, the better the adhesion to the substrate is, probably because it has -O- as an ether in its molecular structure. As described above, the polyimide resin of the present invention is a novel polymer having an unprecedentedly high thermal decomposition initiation temperature and excellent other properties.

Claims (1)

[Claims] 1 99-80 mol% of pyromellitic dianhydride, 1-20 mol% of benzophenonetetracarboxylic dianhydride, 99-60 mol% of P-phenylenediamine, and 1-40 mol% of 4,4'-diaminodiphenyl ether mol % is reacted under anhydrous conditions in an inert gas atmosphere in an organic polar solvent at 0 to 100°C, and the polyamic acid product has an intrinsic viscosity of 0.5 to 2.5 and is a cured product after imidization. A method for producing a heat-resistant resin whose thermal decomposition initiation temperature is 480 to 580°C.