JPH0511111B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to an imide group-containing aromatic polyamine having an imide group as a heat-resistant skeleton in the main chain and an amino group at the end, and a method for producing the same. Furthermore, the present invention relates to an imide group-containing aromatic polyamine with improved solubility, which is useful as a heat-resistant curing agent for epoxy resins, and a method for producing the same. [Prior Art] It is already known that aromatic polyamines are used as curing agents to improve the heat resistance of epoxy resins. On the other hand, one of the heterocyclic polymers that exhibits high heat resistance.
Attempts are being made to improve heat resistance by introducing a polyimide skeleton into epoxy resins.
However, these imide skeleton-containing polymers and oligomers generally have a high melting point and poor solubility, resulting in poor moldability. In order to improve moldability, it is known to form polyimide via intermediates such as polyamides, polyamide esters, and alcohol half esters of tetracarboxylic acids. Curing causes many side reactions, and it is difficult not only to introduce the desired imide group, but also to cure the aromatic polyamine to give a heat-resistant cured product. [Object of the Invention] The present invention has improved the above-mentioned drawbacks. An aromatic polyamine containing an imide group with excellent solubility, useful as a curing agent for epoxy resin, having an imide group as a heat-resistant skeleton in the main chain and an aromatic amino group at the end that improves the heat resistance of the cured epoxy resin. The present invention provides a method for manufacturing the same. That is, the gist of the present invention is the following general formula [X is a tetravalent aromatic tetracarboxylic acid residue containing an aromatic hydrocarbon ring, and the two carbonyl groups bonded to the same nitrogen atom are bonded to each other of the aromatic hydrocarbon rings contained in said X. bonded to adjacent carbon atoms, Y ₁ is

[Structure of the invention]

The present invention will be explained in detail below. First, the imide group-containing aromatic polyamine according to the present invention can be obtained, for example, by the following method. That is, aromatic tetracarboxylic acid or its derivative and at least 0-alkyl substituted aniline-
It can be produced by reacting an excess amount of two or more aromatic diamines containing a formaldehyde condensate. Furthermore, the heat resistance of the cured epoxy resin product is improved by reacting a small amount of the 0-alkyl-substituted aniline-formaldehyde condensate with an aromatic tetracarboxylic acid or its derivative, and then reacting with an excess amount of other aromatic diamine. An imide group-containing aromatic polyamine having an aromatic diamine component at the end can be produced. Aromatic tetracarboxylic acids that are a component of the present invention include pyromellitic acid, 3,3',4,4'-benzophenonetetracarboxylic acid, 3,3',4,4'-
Diphenyl ether tetracarboxylic acid, 3,3',
4,4'-biphenyltetracarboxylic acid, 2,3,
6,7-naphthalenetetracarboxylic acid, 2,3,
4,5-thiophenetetracarboxylic acid, 2,2-
Bis(3,4-dicarboxyphenyl)propane and the like and one or more of these isomers are used. These aromatic tetracarboxylic acid components can be used in the form of derivatives such as lower alkyl esters and dianhydrides, but from the viewpoint of reactivity, it is preferable to use dianhydrides. At least one type of 0-alkyl-substituted aniline-formaldehyde condensate is used as the two or more types of aromatic diamines that are one component of the present invention.
This alkyl group has 1 to 4 carbon atoms, preferably an ethyl group. For example, 0-ethylaniline-formaldehyde condensate is
31961, in an aqueous medium, hydrochloric acid,
It is obtained by the reaction of 0-alkylaniline and formaldehyde at 60 to 100°C in the presence of a strong inorganic acid such as sulfuric acid. This reaction produces by-products such as triamine and tetramine in addition to 3,3'-diethyl-4,4'-diaminodiphenylmethane, which is a diamine component. Although the diamine component can be easily obtained by separating these by distillation, it is also possible to use these by-products in the present invention without separating them. However, if the amount of polyamine greater than triamine increases, gelation tends to occur during production of the imide group-containing aromatic polyamine, so the polyamine is preferably 70% by weight or less. Also, by adding aniline during the condensation reaction of 0-ethylaniline, 3,3'-diethyl-4,4'-diaminodiphenylmethane, 3
-ethyl-4,4'-diaminodiphenylmethane,
A mixture consisting mainly of three components of 4,4'-diaminophenylmethane is obtained, which can also be effectively used in the present invention. 0-toluidine instead of aniline,
A condensate of 0-ethylaniline to which an aniline derivative without a substituent at the p-position, such as 0-chloroaniline, is added can also be used. Aromatic diamines other than the 0-alkyl-substituted aniline-formaldehyde condensate, which is a component of the present invention, have the formula H ₂ N-R-NH ₂ (where R is a divalent linkage having up to 30 carbon atoms). As a base-
It is a divalent aromatic group bonded by SO ₂ -. ) is used. One or more of these aromatic diamines may be used, but 4,4'-diaminodiphenylsulfone and 3,3'-diaminodiphenylsulfone are preferred in view of the heat resistance of the cured epoxy resin. The imide group-containing aromatic polyamine of the present invention can be produced by reacting the above-mentioned aromatic tetracarboxylic acid component, 0-alkyl-substituted aniline-formaldehyde condensate, and other aromatic diamine in a solvent. . As a solvent,
In addition to amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone, phenols such as m-cresol, dimethyl sulfoxide, and the like are used.
An imide group-containing aromatic polyamine can be easily produced by heating predetermined amounts of the three components in these solvents or, if necessary, reacting them in the presence of an imidization catalyst such as a tertiary amine. Although the ratio of these three components is appropriately determined depending on the purpose, it is necessary that the total number of moles of aromatic diamine is larger than the number of moles of aromatic tetracarboxylic acid. Usually, the ratio (sum of moles of aromatic diamine)/(number of moles of aromatic tetracarboxylic acid) can be expressed as (n+1)/n, and the value of n is preferably in the range of 1 to 10. Furthermore, the ratio of the two types of aromatic diamines can be varied depending on the purpose. In order to further improve the solubility, this objective can be achieved by using a large amount of the 0-alkyl-substituted aniline-formaldehyde condensate. The important thing here is 2
The reaction order rather than the proportion of aromatic diamines in the species is important. When curing epoxy resins with aromatic amines, it is known that there are differences in reactivity and heat resistance of the cured resin depending on the type of amine.
Therefore, the aromatic diamine should be determined in consideration of the reactivity and physical properties of the target epoxy resin, and the reaction should be conducted so that the aromatic diamine forms the terminal amino group. That is, an aromatic tetracarboxylic acid and a small amount of 0-
The alkyl-substituted aniline-formaldehyde condensate should be reacted, followed by an excess of the other aromatic diamine. Naturally, depending on the purpose, 0-alkyl-substituted aniline-
The formaldehyde condensate may come to the end, or both may come to the end randomly. The imide group-containing aromatic polyamine of the present invention is dissolved in ethers such as tetrahydrofuran and dioxane in addition to amide solvents that can be used during production, and can be easily mixed with an epoxy compound in solution. Various additives and reinforcing agents such as carbon powder, various metals, metal oxides, silica, asbestos, etc. can be easily mixed into these solutions depending on the purpose. In particular, it is easy to impregnate reinforcing fibers such as glass fibers, aramid fibers, carbon fibers, alumina fibers, and silicon carbide fibers, and is suitable for use in producing fiber-reinforced composite materials with good heat resistance. Furthermore, it can be used for adhesives, coating materials, molded products, etc., which have good heat resistance. [Example] Hereinafter, an imide group-containing aromatic polyamide and a method for producing the same will be specifically shown in Examples, but the invention is not limited thereto unless it exceeds the scope of the claims. Example 1 3,3'-diethyl-4,4'diaminodiphenylmethane (bp242℃/ 6mmHg) 12.8g to N-
Methyl-2-pyrrolidone (hereinafter abbreviated as NMP) 50
This was added dropwise over about 30 minutes to a solution of 32.5 g of 3,3',4,4'-benzophenonetetracarboxylic dianhydride (hereinafter abbreviated as BTDA) in 100 ml of NMP. Next, the generated amic acid solution was converted into 4,4′-
Diaminodiphenylsulfone (hereinafter referred to as 4,4'-DDS)
) was added dropwise to a 100 ml solution of 25.0 g of NMP over about 30 minutes. The mixture was stirred at room temperature for 3 hours, left overnight, and then heated to 200°C, and the imidization reaction was carried out for 4 hours while distilling off the produced water together with NMP. After cooling, the product homogeneous solution was poured into a large amount of methanol to precipitate an imide group-containing aromatic polyamine. After separation, it was washed with methanol and vacuum dried at 100°C for 50 hours. The yield was 95%. The infrared absorption spectrum of the obtained imide group-containing aromatic polyamine is shown in FIG. 3480, 3380 due to primary amino group
cm ^-1 , absorptions at 1780 and 720 cm ^-1 due to imide groups are obvious. Further, the obtained imide group-containing aromatic polyamine was dissolved in N,N'-dimethylformamide (hereinafter abbreviated as DMF) at a concentration of at least 30% by weight. Example 2 30.0 g of 3,3'-diethyl-4,4'-diaminodiphenylmethane, 76.0 g of BTDA, and 3,3'-diaminodiphenyl sulfone (hereinafter referred to as 3,3, An imide group-containing aromatic polyamine was produced in substantially the same manner as in Example 1 using 58.6 g of the compound (abbreviated as '-DDS). The yield was 94%. The infrared absorption spectrum of the obtained product is shown in FIG. Similar to FIG. 1 obtained in Example 1, the presence of primary amino groups and imide groups is clear. Further, the obtained imide group-containing aromatic polyamine was dissolved in DMF and tetrahydrofuran (hereinafter abbreviated as THF) at a concentration of at least 30% by weight. Comparative Example 1 An imide group-containing aromatic polyamine was produced in substantially the same manner as in Example 1 using 5.2 g of BTDA and 8.0 g of 4,4'-DDS. The formation of amic acid by mixing both components and the formation of imide groups by heating were confirmed in the infrared absorption spectrum. The resulting product was added to DMF at a concentration of 30% by weight.
When the solution was dissolved in the solution, a homogeneous solution could not be obtained due to the presence of fine insoluble matter. Comparative Example 2 An imide group-containing aromatic polyamine was produced in substantially the same manner as in Example 1 using 4.3 g of BTDA and 6.6 g of 3,3'-DDS. The formation of amic acid by mixing both components and the formation of imide groups by heating were confirmed in the infrared absorption spectrum. When the obtained product was dissolved in DMF and THF at a concentration of 30% by weight,
Although it was completely dissolved in DMF and a homogeneous solution was obtained,
It did not dissolve in THF. Reference Examples 1 and 2 100 parts by weight of the imide group-containing aromatic polyamine obtained in Examples 1 and 2, 100 parts by weight of amine epoxy compound (Araldite "MY-720" manufactured by Ciba Geigy)
The weight parts were dissolved in DMF and THF to a concentration of 25% by weight, respectively, and carbon fibers (Toray Industries, Inc. "Trading Card T-
400”) and dried to produce prepreg.
10 sheets of the obtained prepreg were laminated and heated under pressure at 180°C.
A curing reaction was carried out at 4 hours at 220° C., followed by post-curing at 220° C. for 24 hours. The glass transition temperatures (TMA method) of the obtained cured products were 220°C and 210°C, respectively.
Also, the bending strength at 200℃ is 140Kg/mm ²
(Vf=63%) and 150Kg/mm ² (Vf=65%). [Effects of the Invention] The imide group-containing aromatic polyamine obtained by the present invention has excellent solubility, and epoxy resin solutions can be easily produced, and can be used for various purposes to obtain heat-resistant epoxy resin cured products. In addition, when the solubility is improved and the resin is soluble in a low boiling point solvent, the solvent can be removed by a simple operation, and the inherent heat resistance of the resin can be easily exhibited.

[Brief explanation of the drawing]

Figures 1 and 2 show Examples 1 and 2, respectively.
The infrared absorption spectrum of the imide group-containing aromatic polyamine obtained in the above is shown. 3480, 3380cm ^-1 due to primary amino group and 1780 due to imide,
Absorption of 720 cm ^-1 is obvious.

Claims (1)

[Claims] 1. General formula [X is a tetravalent aromatic tetracarboxylic acid residue containing an aromatic hydrocarbon ring, and the two carbonyl groups bonded to the same nitrogen atom are bonded to each other of the aromatic hydrocarbon rings contained in said X. Bonded to adjacent carbon atoms, Y ₁ is an aromatic diamine residue represented by the formula (R ₁ and R ₂ are hydrogen atoms or alkyl groups, and at least one is an alkyl group), and Y ₂ is 30 is a divalent aromatic diamine residue containing up to 1 carbon atoms and two aromatic hydrocarbon rings bonded by -SO ₂ - as two linking groups, and m is 1 or more. represents an integer. ] An imide group-containing aromatic polyamine represented by: 2 aromatic tetracarboxylic acid or its derivative;
In a method for producing an imide group-containing aromatic polyamine by reacting this with an excess amount of aromatic diamine, first, an aromatic tetracarboxylic acid or a derivative thereof and less than the equimolar amount of H ₂ N-Y ₁ -NH ₂ [Y ₁ is [Formula] R ₂ is a hydrogen atom or an alkyl group, and at least one of them is an alkyl group)] is reacted with an aromatic diamine, and then this is reacted with H ₂ N−Y ₂ −NH ₂ (Y ₂ has up to 30 carbon atoms and as a divalent linking group -
reacting an aromatic diamine represented by (which is a divalent aromatic hydrocarbon group containing two aromatic hydrocarbon rings bonded by SO ₂ -), and A method for producing an imide group-containing aromatic polyamine represented by the following general formula, characterized in that the sum of the numbers exceeds the number of moles of the aromatic tetracarboxylic acid or its derivative. [X is a tetravalent aromatic tetracarboxylic acid residue containing an aromatic hydrocarbon ring, and the two carbonyl groups bonded to the same nitrogen atom are bonded to each other of the aromatic hydrocarbon rings contained in said X. Bonded to adjacent carbon atoms, Y ₁ is an aromatic diamine residue represented by the formula (R ₁ and R ₂ are hydrogen atoms or alkyl groups, and at least one is an alkyl group), and Y ₂ is 30 is a divalent aromatic diamine residue containing up to 1 carbon atoms and two aromatic hydrocarbon rings bonded by -SO ₂ - as two linking groups, and m is 1 or more. represents an integer. ]