JP7250593B2 - Particulate imide oligomer and method for producing the same - Google Patents

Description

The present invention relates to particulate imide oligomers and methods for producing the same.

Aromatic polyimides have excellent moldability, the highest level of heat resistance among polymers, and excellent mechanical and electrical properties. It is used as a material (heat-resistant composite material) in a wide range of fields such as general industrial applications and vehicle engine (periphery) components. Therefore, there is a demand for a method capable of producing polyimide, which is a matrix resin, inexpensively, simply, and in a short period of time.

As a method for producing polyimide, Patent Document 1 describes a method for producing polyimide powder in which a polyamic acid solution is heat-treated to precipitate polyimide particles from the solvent, and polyimide powder is directly collected from the solvent. In Patent Document 2, an aromatic tetracarboxylic acid component and an aromatic diamine component are reacted in a reaction solvent to precipitate fine particles, and then the reaction is continued while distilling off water to produce a polyimide powder. method is described. In Patent Document 3, an NMP solution of a terminal-modified imide oligomer is put into ion-exchanged water, the precipitated solid is separated by filtration to obtain a granular terminal-modified imide oligomer, and then the terminal-modified imide oligomer is pulverized. A manufacturing method for obtaining a terminally modified imide oligomer powder is described.

Further, Patent Documents 4 and 5 disclose a step of removing reaction water from a copolyimide melt obtained from an aromatic dianhydride component and an aromatic diamine component, and A method of making a polyimide composition is described that includes the step of molding into an article.

JP-A-7-33875 JP-A-11-302380 WO 2018/180930 A1 JP-A-2002-226583 JP-A-2002-226584

However, in the techniques described in Patent Documents 1 and 2, after preparing a polyimide solution by heating polyamic acid in a solution, the polyimide particles are precipitated, recovered, washed, and dried to obtain a polyimide powder. are manufacturing. Further, in the technique described in Patent Document 3, powdery imide oligomers are produced by precipitating (depositing) imide oligomers in a solution with a poor solvent, recovering, washing, and drying them.

Therefore, the techniques described in Patent Documents 1 to 3 have many complicated steps and require a long time (several hours) for production. , there is room for further improvement. In addition, the techniques described in Patent Documents 4 and 5 involve many complicated steps, and the resulting copolyimide is not in the form of a powder and is poor in handleability.

An object of one aspect of the present invention is to provide a production method capable of producing a particulate imide oligomer inexpensively, simply, and in an extremely short period of time as compared with conventional techniques, and to provide the particulate imide oligomer. do.

As a result of intensive studies in order to solve the above problems, the present inventors have found that particulate imide oligomers can be produced inexpensively, simply, and in an extremely short time (several minutes) by melt processing a solution of an amic acid oligomer. and that the obtained particulate imide oligomer has unprecedented novel physical properties and properties, and have completed the present invention.

That is, one embodiment of the present invention includes the following configurations.
[1] A particulate imide oligomer represented by the following general formula (1), which is irregularly shaped particles and has an average particle diameter of 100 to 500 μm when measured after being dispersed in water. particulate imide oligomers.

(In general formula (1), R ₁ and R ₂ represent divalent aromatic diamine residues which may be the same or different from each other, R ₃ and R ₄ may be the same or different from each other, represents a good tetravalent aromatic tetracarboxylic acid residue, one of _R5 and _R6 is a hydrogen atom and the other is a phenyl group, m and n are 1≤m, 0≤n, It satisfies the relationships of 1≦m+n≦20 and 0.05≦m/(m+n)≦1, and the arrangement of repeating units may be either block or random.)
[2] The particulate imide oligomer according to [1], which has an imidization rate of 80% or more as measured by ¹ H-NMR.
[3] The particulate imide oligomer according to [1] or [2], which has a solvent content of 20% by weight or less.
[4] The solvent is a mixed solvent of an alcohol solvent and an ether solvent, a single solvent of a hydroxy ether solvent, a mixed solvent of an alcohol solvent and a hydroxy ether solvent, or a mixture of an ether solvent and a hydroxy ether solvent. The solvent, or a mixed solvent of an alcohol solvent, an ether solvent, and a hydroxy ether solvent, the boiling point of which is 130° C. or less (the boiling point of each solvent in the mixed solvent) is 130° C. or less. of particulate imide oligomers.
[5] The particulate imide oligomer according to [3], wherein the solvent is a mixed solvent of methanol and 1,3-dioxolane.
[6] A method for producing a particulate imide oligomer, comprising the step of melt-processing a solution of an amic acid oligomer represented by the following general formula (2).

(In the general formula (2), R ₁ and R ₂ represent divalent aromatic diamine residues which may be the same or different from each other, R ₃ and R ₄ may be the same or different from each other, represents a good tetravalent aromatic tetracarboxylic acid residue, one of _R5 and _R6 is a hydrogen atom and the other is a phenyl group, m and n are 1≤m, 0≤n, It satisfies the relationships of 1≦m+n≦20 and 0.05≦m/(m+n)≦1, and the arrangement of repeating units may be either block or random.)
[7] The method for producing a particulate imide oligomer according to [6], wherein the melt processing is performed at a temperature of 250°C or lower.
[8] The method for producing a particulate imide oligomer according to [6] or [7], wherein in the step of melt processing, melt extrusion is performed using an extruder.
[9] The method for producing a particulate imide oligomer according to [8], wherein the residence time in the extruder is 1 to 30 minutes.

According to one aspect of the present invention, since no solvent, imidizing agent, or dehydrating agent is used during imidization, the imide oligomer obtained from the amic acid oligomer is precipitated (precipitated) with a poor solvent, or the obtained Eliminates the need to pulverize solids (imide oligomers). Therefore, it is possible to produce a particulate imide oligomer that is easy to handle, is inexpensive, simple, and can be produced in a very short time (several minutes) compared to the conventional technology, and a novel unprecedented production method. There is an effect that it is possible to provide a particulate imide oligomer having physical properties and characteristics.

FIG. 2 is a diagram of a particulate imide oligomer observed with an optical microscope in one embodiment of the present invention. It is the figure which observed the conventional particulate imide oligomer with the optical microscope.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to this, and various modifications are possible within the scope described, and implementations obtained by appropriately combining technical means disclosed in different embodiments and examples, respectively. The form is also included in the technical scope of the present invention. In this specification, unless otherwise specified, "A to B" representing a numerical range means "A or more (including A and greater than A), B or less (including B and less than B)". do. Also, the terms "weight" and "mass" are used synonymously.

[1. Particulate imide oligomer]
The particulate imide oligomer (hereinafter sometimes simply referred to as "imide oligomer") in one embodiment of the present invention is a particulate imide oligomer represented by the following general formula (1), comprising irregularly shaped particles , and the average particle size measured by dispersing in water is in the range of 100 to 500 μm.

In this specification, "imide oligomer" is synonymous with "terminal-modified imide oligomer" unless otherwise specified.

(In general formula (1), R ₁ and R ₂ represent divalent aromatic diamine residues which may be the same or different from each other, R ₃ and R ₄ may be the same or different from each other, represents a good tetravalent aromatic tetracarboxylic acid residue, one of _R5 and _R6 is a hydrogen atom and the other is a phenyl group, m and n are 1≤m, 0≤n, It satisfies the relationships of 1≦m+n≦20 and 0.05≦m/(m+n)≦1, and the arrangement of repeating units may be either block or random.)
In one embodiment of the present invention, the divalent aromatic diamine residue represented by R ₁ and R ₂ in general formula (1) is present between two amino groups of the aromatic diamines. It refers to an aromatic organic group that In one embodiment of the present invention, the tetravalent aromatic tetracarboxylic acid residues represented by R ₃ and R ₄ in the general formula (1) are four carbonyls of the aromatic tetracarboxylic acid. It refers to aromatic organic groups present between groups. Here, the aromatic organic group is an organic group having an aromatic ring. The aromatic organic group is preferably an organic group having 4 to 30 carbon atoms, more preferably an organic group having 4 to 18 carbon atoms, and even more preferably an organic group having 4 to 12 carbon atoms. . Further, the aromatic organic group is preferably a group containing carbon and hydrogen having 6 to 30 carbon atoms, more preferably a group containing carbon and hydrogen having 6 to 18 carbon atoms. More preferably, it is a group containing ∼12 carbons and hydrogen. The divalent aromatic diamine residues represented by R ₁ and R ₂ may be the same or different. Also, the divalent aromatic diamine residues represented by R ₁ and R ₂ may be different aromatic diamine residues for each repeating unit.

Specific examples of divalent aromatic diamine residues represented by R ₁ and R ₂ include 2-phenyl-4,4′-diaminodiphenyl ether (Ph-ODA), 9,9-bis( at least one selected from 4-aminophenyl)fluorene, 9,9-bis(4-(4-aminophenoxy)phenyl)fluorene, 1,3-diaminobenzene, and 4-phenoxy-1,3-diaminobenzene It is more preferable to have

The particulate imide oligomer represented by the general formula (1) is, for example, a particulate imide oligomer using 2-phenyl-4,4′-diaminodiphenyl ether, and is more likely to be synthesized by the following method. preferable. That is, the particulate imide oligomer represented by the general formula (1) is
(i) 1,2,4,5-benzenetetracarboxylic acids (especially the dianhydride thereof), 3,3',4,4'-biphenyltetracarboxylic acids (especially the dianhydride thereof), and one or more tetracarboxylic acids selected from the group consisting of bis(3,4-carboxyphenyl) ethers (especially acid dianhydrides thereof);
(ii) aromatic diamines, including 2-phenyl-4,4'-diaminodiphenyl ether;
(iii) 4-(2-phenylethynyl) phthalic anhydride (PEPA), an unsaturated acid anhydride for introducing unsaturated end groups into imide oligomers;
are charged so that the total amount of dicarboxylic acid groups and the total amount of primary amino groups are approximately equal, and reacted in the presence (or in the absence) of an organic solvent to synthesize an amic acid oligomer. More preferably, it is synthesized by a method of melt processing a solution of an amic acid oligomer.

When a plurality of dicarboxylic acid groups are adjacent to each other, "the number of carboxyl groups/2" is defined as "the number of dicarboxylic acid groups". For example, assume that the structure "COOH-COOH-COOH-COOH" contains two dicarboxylic acid groups.

In the particulate imide oligomer thus synthesized, R ₃ and R ₄ are each independently selected from tetravalent aromatic tetracarboxylic acid residues derived from one or more aromatic tetracarboxylic acids, They may be the same as each other, or they may be different from each other. When 1<m and 1<n (m and n are integers), R ₃ (or R ₄ ) in each repeating unit may be the same or different. Furthermore, when 1<m, one of the repeating unit in which R ₅ is a phenyl group and R ₆ is a hydrogen atom and the repeating unit in which R ₅ is a hydrogen atom and R ₆ is a phenyl group or both may optionally be included.

In general formula (1), m and n satisfy the relationships of 1≤m, 0≤n, 1≤m+n≤20 and 0.05≤m/(m+n)≤1. The particulate imide oligomer in one embodiment of the present invention may be 1 ≤ m ≤ 5, 0 < n ≤ 5, 1 < m + n ≤ 10, 0.5 ≦m/(m+n)<1 may be satisfied. Furthermore, the particulate imide oligomer in one embodiment of the present invention more preferably satisfies 4≦m+n, and more preferably satisfies 5≦m+n. When m and n satisfy the above relationship, the particulate imide oligomer in one embodiment of the present invention has excellent solution storage stability, and the cured polyimide has excellent heat resistance and mechanical strength. even better. Incidentally, m and n can be easily adjusted by controlling the types, molar ratios, etc. of tetracarboxylic acids and aromatic diamines used as raw materials.

In the present specification, the phrase "the arrangement of repeating units may be block or random" means that the repeating unit portion may be a block polymer or a random polymer. .

The particulate imide oligomer is more preferably an imide oligomer having an imide bond in the main chain, wherein (i) the ends (more preferably both ends) are derived from 4-(2-phenylethynyl) phthalic anhydride It has unsaturated terminal groups capable of addition polymerization, (ii) satisfies the relationship 1≤m+n≤20, and (iii) is solid at room temperature (eg, 23°C).

Examples of the 1,2,4,5-benzenetetracarboxylic acids include 1,2,4,5-benzenetetracarboxylic acid, 1,2,4,5-benzenetetracarboxylic dianhydride (PMDA), and acid derivatives (esters, salts, etc.) of 1,2,4,5-benzenetetracarboxylic acid. Among these, 1,2,4,5-benzenetetracarboxylic dianhydride is more preferred. When R ₃ and R ₄ are 1,2,4,5-benzenetetracarboxylic acids, the particulate imide oligomer is represented by general formula (1-2) below. In general formula (1-2), the definitions of R ₁ , R ₂ , R ₅ , R ₆ , m and n are the same as in general formula (1).

Examples of the 3,3′,4,4′-biphenyltetracarboxylic acids include 3,3′,4,4′-biphenyltetracarboxylic acid, 3,3′,4,4′-biphenyltetracarboxylic acid di Anhydrides (s-BPDA) and acid derivatives (esters, salts, etc.) of 3,3′,4,4′-biphenyltetracarboxylic acid are included. Among these, 3,3′,4,4′-biphenyltetracarboxylic dianhydride is more preferred. When R ₃ and R ₄ are 3,3′,4,4′-biphenyltetracarboxylic acids, the particulate imide oligomer is represented by the following general formula (1-3). In general formula (1-3), the definitions of R ₁ , R ₂ , R ₅ , R ₆ , m and n are the same as in general formula (1).

Examples of the bis(3,4-carboxyphenyl) ethers include bis(3,4-carboxyphenyl) ether, bis(3,4-carboxyphenyl) ether dianhydride (s-ODPA), and bis( 3,4-Carboxyphenyl) ether acid derivatives (esters, salts, etc.). Among these, bis(3,4-carboxyphenyl)ether dianhydride is more preferred. When R ₃ and R ₄ are bis(3,4-carboxyphenyl) ethers, the particulate imide oligomer is represented by general formula (1-4) below. In general formula (1-4), the definitions of R ₁ , R ₂ , R ₅ , R ₆ , m and n are the same as in general formula (1).

In one embodiment of the invention, R ₃ and/or R ₄ are 1,2,4,5-benzenetetracarboxylic acids, 3,3′,4,4′-biphenyltetracarboxylic acids and bis(3 ,4-carboxyphenyl)ethers may have a structure derived from aromatic tetracarboxylic acids other than ethers. That is, amic acid oligomers for producing the above particulate imide oligomers are mixed with 1,2,4,5-benzenetetracarboxylic acids, 3,3′,4,4′-biphenyltetracarboxylic acids, and bis(3,4- Aromatic tetracarboxylic acids other than carboxyphenyl)ethers may be added to the raw materials (used as monomers) for synthesis. Such other aromatic tetracarboxylic acids include, for example, 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA) and 2,3,3′,4′-biphenyltetracarboxylic acid. dianhydride (a-BPDA), 2,2',3,3'-biphenyltetracarboxylic dianhydride (i-BPDA), 2,2-bis(3,4-dicarboxyphenyl)methane dianhydride , bis(3,4-carboxyphenyl) ether dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride and the like. Other aromatic tetracarboxylic acids may be used alone or in combination of two or more.

Further, the amic acid oligomer for producing the particulate imide oligomer may be synthesized by adding other aromatic diamines other than 2-phenyl-4,4'-diaminodiphenyl ether to the raw materials (using them as monomers). good. Such other aromatic diamines include, for example, 1,4-diaminobenzene, 1,3-diaminobenzene, 1,2-diaminobenzene, 2,6-diethyl-1,3-diaminobenzene, 4, 6-diethyl-2-methyl-1,3-diaminobenzene, 3,5-diethyltoluene-2,6-diamine, 4,4'-diaminodiphenyl ether (4,4'-ODA), 3,4'-diamino diphenyl ether (3,4'-ODA), 3,3'-diaminodiphenyl ether, 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, bis(2,6-diethyl-4-aminophenyl)methane, 4,4′-methylene-bis(2,6-diethylaniline), bis(2-ethyl-6-methyl-4-aminophenyl)methane, 4 , 4′-methylene-bis(2-ethyl-6-methylaniline), 2,2-bis(3-aminophenyl)propane, 2,2-bis(4-aminophenyl)propane, 1,3-bis( 4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 1,4-bis(3-aminophenoxy)benzene, benzidine, 3, 3′-dimethylbenzidine, 2,2-bis(4-aminophenoxy)propane, 2,2-bis(3-aminophenoxy)propane, 2,2-bis[4′-(4″-aminophenoxy)phenyl ] hexafluoropropane, 9,9-bis(4-aminophenyl)fluorene, 9,9-bis(4-(4-aminophenoxy)phenyl)fluorene and the like. Among the above, 9,9-bis(4-aminophenyl)fluorene, 9,9-bis(4-(4-aminophenoxy)phenyl)fluorene, and 1,3-diaminobenzene are other aromatic diamines. It is more preferable as a class. Other aromatic diamines may be used alone or in combination of two or more.

In particular, in applications where mechanical strength is required, (i) 2-phenyl-4,4'-diaminodiphenyl ether and (ii) other aromatic diamines are used in combination in the synthesis of the amic acid oligomer. is preferred. In this case, the amount of the other aromatic diamines used is preferably more than 0 and 50 mol% or less, and more than 0 and 25 mol% or less, with the total amount of the aromatic diamines being 100 mol%. More preferably, it is more than 0 and 10 mol % or less. Other aromatic diamines used at this time include 9,9-bis(4-aminophenyl)fluorene, 9,9-bis(4-(4-aminophenoxy)phenyl)fluorene, and 1,3-diamino One or more selected from benzene are preferred.

Similarly, in applications where mechanical strength is required, it is preferable that 0.50 ≤ m / (m + n) < 1 in general formula (1), and 0.75 ≤ m / (m + n) < 1 more preferably 0.90≦m/(m+n)<1, and even more preferably 0.90≦m/(m+n)≦0.95.

A particulate imide oligomer obtained from such an amic acid oligomer has excellent handling properties, high solubility, and high mechanical properties.

As the unsaturated acid anhydride for terminal modification (endcapping), 4-(2-phenylethynyl)phthalic anhydride is preferably used. When synthesizing the amic acid oligomer, 4-(2-phenylethynyl)phthalic anhydride is preferably used in a range of 5 to 200 mol%, based on the total amount of aromatic tetracarboxylic acids being 100 mol%, preferably 5 to 150 mol. % is more preferable.

The particulate imide oligomer in one embodiment of the present invention is amorphous particles, and each particle has a sharp portion (not spherical). Whether or not the particulate imide oligomers are "irregularly shaped particles" can be easily determined, for example, by observing them using an optical microscope.

The imidization rate of the particulate imide oligomer can be calculated by measuring the peak area derived from aromatic ^1H and the peak area derived from residual amide ^1H in ^1H -NMR. The imidization rate is preferably 80% or more, more preferably 85% or more, even more preferably 90% or more, particularly preferably 95% or more, and 99% or more. is most preferred. The imidization rate of the particulate imide oligomer can be controlled by controlling the temperature and time of melt processing. A method for measuring the imidization rate will be described in detail in Examples.

The molecular weight (weight average molecular weight) of the particulate imide oligomer can be confirmed by GPC. The molecular weight is preferably 1,000 to 100,000, more preferably 3,000 to 50,000, even more preferably 5,000 to 30,000. The molecular weight of the particulate imide oligomer can be controlled by controlling the temperature and time of melt processing. The molecular weight measurement conditions are set by GPC so as to be optimal according to the structure of the particulate imide oligomer to be measured.

The average particle size of the particulate imide oligomer can be measured by dispersing the particulate imide oligomer in water. The average particle size is preferably in the range of 100 to 500 μm, more preferably in the range of 150 to 450 μm, even more preferably in the range of 200 to 400 μm. Also, the particle size distribution (D50) is preferably within the range of 300 to 400 μm. A method for measuring the average particle size will be described in detail in Examples.

The solvent content (residual solvent) in the particulate imide oligomer is preferably 20% by weight or less, more preferably 10% by weight or less, and even more preferably 7% by weight or less. The solvent is not particularly limited, but may be, for example, a mixed solvent of an alcohol-based solvent and an ether-based solvent used in synthesizing an amic acid oligomer; a single solvent of a hydroxyether-based solvent; an alcohol-based solvent and a hydroxyether-based solvent. a mixed solvent of an ether solvent and a hydroxy ether solvent; or a mixed solvent of an alcohol solvent, an ether solvent and a hydroxy ether solvent; In addition, whether these solvents are used as a single solvent or as a mixed solvent, the boiling point (the boiling point of each single solvent in the mixed solvent) is preferably 130 ° C. or less. preferable. Among these, a mixed solvent of methanol and 1,3-dioxolane is more preferable.

The solvent content can be measured by heating the particulate imide oligomer to around the glass transition temperature (Tg) by DSC to soften it and volatilize the solvent contained therein. That is, in the present specification, the solvent content (residual solvent) refers to a value calculated from the weight reduction rate of the particulate imide oligomer near the glass transition temperature in TGA-DSC.

The minimum melt viscosity of the particulate imide oligomer in one embodiment of the present invention is preferably 20000 Pa·sec or less, more preferably 10000 Pa·sec or less, and even more preferably 5000 Pa·sec or less, 3000 Pa·sec or less is particularly preferable. The minimum melt viscosity of the particulate imide oligomer in one embodiment of the present invention is preferably 1 to 20000 Pa·sec, but is not limited to this range. If the minimum melt viscosity is within the above range, the imide oligomer in one embodiment of the present invention is more excellent in moldability. In this specification, the minimum melt viscosity refers to a value measured by the method described in Examples below.

The particulate imide oligomer in one embodiment of the present invention may be a mixture of terminally modified imide oligomers having different molecular weights. Moreover, the particulate imide oligomer according to one embodiment of the present invention may be mixed with other soluble polyimides or thermoplastic polyimides. The above-mentioned thermoplastic polyimide is a polyimide that becomes soft by heating, and although commercially available products can be mentioned, it is not particularly limited.

The melt viscosity at 280° C. of the particulate imide oligomer in one embodiment of the present invention is preferably 200 to 1,000,000 Pa·sec, more preferably 200 to 800,000 Pa·sec, and more preferably 200 to 500,000 Pa·sec. is more preferred. When the melt viscosity at 280°C exceeds 1,000,000 Pa·sec, the imide oligomer tends to be difficult to flow. Therefore, when producing a fiber-reinforced composite material, it is difficult to impregnate the imide oligomer between the fibers, and it tends to be difficult to obtain a fiber-reinforced composite material in which defects such as voids or non-impregnated portions are reduced or eliminated. be. On the other hand, if the melt viscosity at 280°C is less than 200 Pa·sec, the resin tends to flow too easily, making it difficult to produce imide prepregs. As used herein, the melt viscosity at 280° C. refers to a value measured by the method described in Examples below.

The 5% weight loss temperature in air of the polyimide resin obtained by curing the particulate imide oligomer in one embodiment of the present invention is preferably 520° C. or higher, more preferably 530° C. or higher. , 535° C. or higher. It is considered that the 5% weight loss temperature in air has a correlation with the oxidation deterioration rate when the polyimide resin is used for a long period of time in a high temperature environment. The higher the 5% weight loss temperature in air, the longer the polyimide resin can be used in a high temperature environment. That is, it can be said that the higher the 5% weight loss temperature in air, the more excellent the long-term heat resistance stability of the particulate imide oligomer. The 5% weight loss temperature in air refers to the value measured by the method described in Examples below.

The particulate imide oligomer in one embodiment of the present invention can be made into, for example, a film-like polyimide by pressing, heat-melting, and curing. Particulate imide oligomers have novel physical properties and properties that have never been seen before, and are said to be excellent in handleability, excellent moldability, and fiber-reinforced composite materials exhibiting excellent heat resistance and mechanical properties. have advantages.

Particulate imide oligomers are used in general industrial applications such as aircraft, space industry equipment and vehicle engine (peripheral) parts, transport arms, robot arms, roll materials, friction materials, sliding members such as bearings, etc. , can be used in a wide range of fields where ease of moldability and high heat resistance are required. Aircraft members include, for example, engine fan cases, inner frames, moving blades (fan blades, etc.), stationary blades (structural guide vanes (SGV), etc.), bypass ducts, various types of piping, and the like. Vehicle members include, for example, brake members, engine members (cylinders, motor cases, air boxes, etc.), energy regeneration system members, and the like.

[2. Method for producing particulate imide oligomer]
To give a specific example, the particulate imide oligomer can be synthesized by the following method.
1. (i) 3,3′,4,4′-biphenyltetracarboxylic acids (especially the dianhydrides thereof), 1,2,4,5-benzenetetracarboxylic acids (especially the dianhydrides thereof), and One or more aromatic tetracarboxylic acids selected from the group consisting of bis(3,4-carboxyphenyl) ethers (especially dianhydrides thereof), and (ii) 2-phenyl-4,4'-diamino Aromatic diamines containing diphenyl ether and (iii) 4-(2-phenylethynyl) phthalic anhydride are prepared so that the total amount of dicarboxylic acid groups and the total amount of primary amino groups are approximately equal. .
2. Each of the prepared monomers is polymerized in an organic solvent at a reaction temperature of about 100° C. or lower (preferably about 80° C. or lower) to synthesize an amic acid oligomer in the form of a solution.
3. The amic acid oligomer solution is melt processed at a temperature of 250° C. or less. Particulate imide oligomers having terminal 4-(2-phenylethynyl)phthalic anhydride residues are thus obtained.

A specific example of a more preferred method for synthesizing the particulate imide oligomer includes the following method.
Aromatic diamines including 1.2-phenyl-4,4'-diaminodiphenyl ether are uniformly dissolved in an organic solvent.
2. Aromatic tetracarboxylic dianhydride is added to the resulting solution and uniformly dissolved. The aromatic tetracarboxylic dianhydrides include 3,3′,4,4′-biphenyltetracarboxylic dianhydride, 1,2,4,5-benzenetetracarboxylic dianhydride, and bis(3, It is one or more selected from 4-carboxyphenyl) ether dianhydrides.
3. The obtained solution is reacted at a reaction temperature of about 5 to 60° C. with stirring for about 1 to 180 minutes.
4. 4-(2-Phenylethynyl)phthalic anhydride is added to the obtained reaction solution and dissolved uniformly.
5. The obtained solution is reacted at a reaction temperature of about 5 to 60° C. with stirring for about 1 to 180 minutes. Thus, amic acid oligomers in solution are synthesized.
6. The resulting reaction liquid is melt-extruded at a temperature of 250° C. or lower to cause an imidization reaction and to form particles. After melt extrusion, if necessary, the obtained particles are cooled to around room temperature. This synthesizes the particulate imide oligomer.

All or part of the steps in the above synthesis are preferably performed under an inert gas atmosphere (an atmosphere of nitrogen gas, argon gas, etc.) or under reduced pressure.

Examples of the organic solvent used in the above synthesis include N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide (DMAc), N,N-diethylacetamide, N-methylcaprolactam, γ-butyrolactone (GBL). , cyclohexanone, and a mixed solvent of methanol and 1,3-dioxolane. Only one type of these organic solvents may be used, or two or more types may be used in combination. These organic solvents can be appropriately selected by applying known techniques relating to soluble polyimides. Among these, it is more preferable to use a mixed solvent of methanol and 1,3-dioxolane.

That is, a method for producing a particulate imide oligomer according to one embodiment of the present invention is a method including a step of melt-processing a solution of an amic acid oligomer represented by the following general formula (2).

(In formula (2), R ₁ and R ₂ represent divalent aromatic diamine residues that may be the same or different from each other, R ₃ and R ₄ are the same or different divalent represents an aromatic tetracarboxylic acid residue of R ₅ and R ₆ are a hydrogen atom or a phenyl group, one of which is a phenyl group, m and n are 1 ≤ m, 0 ≤ n, 1 ≦m+n≦20 and 0.05≦m/(m+n)≦1, and the arrangement of repeating units may be either block or random.)
A solution of amic acid oligomer can be produced by reacting aromatic tetracarboxylic acids, aromatic diamines, and an unsaturated acid anhydride for terminal modification in a solvent, as described above. The method for producing the solution of the amic acid oligomer can employ a known production method, and is not particularly limited to the method described above.

As the solvent used for preparing the solution of the amic acid oligomer, that is, the solvent for dissolving the amic acid oligomer, the solvent used during the reaction is suitable. , boiling point 202 ° C. (hereinafter, boiling point indicates temperature under normal pressure unless otherwise specified)), N,N-dimethylacetamide (DMAc, boiling point 165 ° C.), N,N-diethylacetamide (boiling point 185 ° C.) , N-methylcaprolactam (boiling point 120° C. under reduced pressure (25 mmHg)); ester solvents such as γ-butyrolactone (GBL, boiling point 204° C.); ketone solvents such as cyclohexanone (boiling point 156° C.) 1,3-dioxane (boiling point 105° C.), 1,4-dioxane (boiling point 101° C.), tetrahydrofuran (boiling point 66° C.), 1,3-dioxolane (boiling point 75° C.), 1,2-dimethoxyethane (boiling point 83 ° C.); ether solvents such as methanol (boiling point 65 ° C.), ethanol (boiling point 78 ° C.), 1-propanol (boiling point 98 ° C.), 2-propanol (boiling point 82 ° C.); ~95°C), ethoxymethanol (boiling point 102°C), 2-methoxyethanol (boiling point 124°C), 2-ethoxyethanol (boiling point 135°C), hydroxy ethers such as 1-methoxy-2-propanol (boiling point 119°C) solvent; Only one type of these solvents may be used, or two or more types may be used in combination. As the solvent, a mixed solvent such as a mixed solvent of methanol and 1,3-dioxolane may be used.

The boiling point of the solvent (under normal pressure) is preferably 200° C. or lower, more preferably 150° C. or lower, even more preferably 130° C. or lower, because of the ease of volatilization during melt processing. °C or less is most preferred. If the boiling point (under normal pressure) exceeds 200° C., the imide oligomer may not precipitate smoothly, or the solvent may be difficult to volatilize.

Further, the solvent is more preferably an ester solvent, a ketone solvent, an ether solvent, an alcohol solvent, a hydroxyether solvent, or a mixed solvent of these solvents, because imide oligomers are likely to precipitate during volatilization. , ether solvents, alcohol solvents, hydroxy ether solvents, and mixed solvents of these solvents are more preferred, and ether solvents, hydroxy ether solvents, and mixed solvents of these solvents and alcohol solvents are particularly preferred. preferable. The ether-based solvent preferably has two or more oxygen atoms per molecule because of its excellent solubility. Solvents that have too high an ability to dissolve the amic acid oligomer may hinder smooth deposition of the imide oligomer or may make it difficult to volatilize the solvent. Also, a solvent with too low an ability to dissolve the amic acid oligomers will not give a solution with a suitable concentration of the amic acid oligomers.

Among the solvents exemplified above, an alcohol-based solvent excellent in dissolving tetracarboxylic acids and aromatic diamines used as raw materials for amic acid oligomers, and an ether-based solvent excellent in dissolving the above tetracarboxylic acids and the resulting amic acid oligomers. A mixed solvent of a hydroxy ether solvent having both characteristics of an alcohol solvent and an ether solvent; a mixed solvent of an alcohol solvent and a hydroxy ether solvent; a mixed solvent of an ether solvent and a hydroxy ether solvent; Alternatively, a mixed solvent of an alcohol solvent, an ether solvent, and a hydroxy ether solvent is particularly preferred because it enables efficient polymerization of the amic acid oligomer. In consideration of solubility, the ether solvent more preferably has two or more oxygen atoms per molecule. In addition, whether these solvents are used as a single solvent or as a mixed solvent, the boiling point (the boiling point of each single solvent in the mixed solvent) is preferably 130 ° C. or less. preferable. In consideration of volatility, a mixed solvent of an alcoholic solvent and an etheric solvent is more preferable because it forms an azeotropic mixture and volatilizes. Alcohol-based solvents and hydroxy-ether-based solvents yield amic acid oligomers because the hydroxyl groups on the molecule stabilize radicals that may be formed from ether-based solvents during autoxidation by oxygen, for example. It has the advantage of making peroxides less likely to be generated in some cases. That is, alcohol solvents and hydroxy ether solvents also function as stabilizers for ether solvents. Unlike ether solvents, the hydroxy ether solvents act to stabilize themselves even when used alone. However, in anticipation of further stabilization, it may be used as a mixed solvent with an alcoholic solvent.

As the mixed solvent of the alcohol solvent and the ether solvent, specifically, for example, a mixed solvent of methanol and 1,3-dioxolane is suitable, and the weight ratio of methanol:1,3-dioxolane is 1:1. A mixed solvent of 4 to 4:1 is more preferred, and a mixed solvent of 1:2 to 2:1 is even more preferred.

The concentration of the amic acid oligomer solution is preferably 10 to 90% by weight, more preferably 20 to 70% by weight, even more preferably 30 to 50% by weight. When the concentration of the amic acid oligomer solution is within the above range, the particulate imide oligomer can be produced efficiently.

In the melt-processing step, the particulate imide oligomer is produced by melt-processing the amic acid oligomer while evaporating the solvent from the solution of the amic acid oligomer. The melt processing is preferably performed at a temperature of 250° C. or lower. Therefore, the set temperature of the processing machine in melt processing is preferably 150 to 300°C, more preferably 170 to 280°C, even more preferably 190 to 260°C. When the set temperature of the processing machine is less than 150°C, there is a tendency that an imide oligomer having a high imidization rate cannot be obtained. When the set temperature of the processing machine exceeds 300°C, the curing reaction of the imide oligomer tends to be accelerated. The imidization reaction can be easily controlled by adjusting the temperature during melt processing.

The method of melt processing is not particularly limited, but a method of melt extrusion using an extruder as a processing machine is convenient. The extruder that can be used in the melt processing step is an extruder that can heat the amic acid oligomer and extrude it while melt-kneading. Examples include a single-screw extruder and a twin-screw extruder. but is not particularly limited. Among them, a twin-screw extruder is preferred. The extruder may have a perforated plate at its tip.

It is desirable that the extruder has a temperature gradient from the feed port side toward the extrusion port side so that melt extrusion can be performed favorably. Specifically, the temperature on the supply port side is preferably room temperature to 150°C, more preferably room temperature to 120°C, and even more preferably room temperature to 80°C. The temperature on the extrusion port side is preferably above 150°C and 300°C or less, more preferably 170 to 280°C, even more preferably 190 to 260°C.

The extruder serves as a desolvator for volatilizing the solvent from the amic acid oligomer solution, a reactor for imidization reaction (dehydration reaction), and a pulverizer for granulating the obtained imide oligomer. Therefore, solvent volatilization (solvent removal), imidization reaction, and pulverization can be continuously performed in the extruder from the supply port side toward the extrusion port side.

That is, in the method for producing a particulate imide oligomer according to one embodiment of the present invention, for example, an extruder is used to melt-knead a solution of an amic acid oligomer while heating, and a solvent and an imidization reaction are added during the melt-kneading. Since the imidization reaction is carried out while volatilizing the water produced by , it is not necessary to add an imidizing agent and a dehydrating agent.

The residence time of the amic acid oligomer in the extruder is preferably 1 to 30 minutes, more preferably 2 to 20 minutes, even more preferably 3 to 10 minutes. The imidization reaction can be easily controlled by adjusting the residence time by controlling the shape and rotation speed of the extruding member such as a screw. If the residence time is less than 1 minute, there is a tendency that an imide oligomer with a high imidization rate cannot be obtained. If the residence time exceeds 30 minutes, the curing reaction of the imide oligomer tends to be accelerated.

That is, in the method for producing a particulate imide oligomer according to one embodiment of the present invention, by appropriately adjusting the shape and rotation speed of the extruding member, the temperature and residence time during melt extrusion, melt extrusion is performed. The imidization rate of the obtained particulate imide oligomer can be easily controlled.

The particulate imide oligomer extruded from the extruder is irregularly shaped particles. When the particulate imide oligomers are continuous and form flakes, they may be lightly pulverized. The resulting particulate imide oligomer can be subjected to a curing reaction without purification.

Whether or not the amic acid oligomer is imidized can be confirmed by confirming whether or not the peak derived from amide ¹ H (amide group) has disappeared in ¹ H-NMR.

In the production method according to one embodiment of the present invention, the particulate imide oligomer is produced by performing the step of melt processing, that is, no solvent, imidizing agent, or dehydrating agent is used during imidization. There is no need for post-processes such as a recovery process for precipitating (depositing) the imide oligomer in the solution with a poor solvent, a washing process, a drying process, and the like. Therefore, the production method according to one embodiment of the present invention can produce particulate imide oligomers inexpensively, simply, and in an extremely short period of time (several minutes) as compared with conventional techniques.

The particulate imide oligomer obtained by the production method according to one embodiment of the present invention is amorphous particles, and each particle has a sharp portion (not spherical). Whether or not the particulate imide oligomers are "irregularly shaped particles" can be easily determined, for example, by observing them using an optical microscope. For example, FIG. 1 is an optical microscope observation of the particulate imide oligomer produced by the above-described production method, and FIG. 2 is an optical microscope observation of the particulate imide oligomer produced by the conventional production method. , it is easily understood that the particulate imide oligomer in one embodiment of the present invention has a sharp portion in each particle and is an "amorphous particle".

[3. imide prepreg]
The particulate imide oligomer in one embodiment of the present invention can be made into an imide prepreg by being mixed with reinforcing fibers. By using the particulate imide oligomer according to one embodiment of the present invention, the imide prepreg has reduced residual volatile matter such as a solvent. In addition, in a resin composite material (for example, a carbon fiber reinforced composite material) produced using the imide prepreg, defects such as voids caused by volatilization and decomposition of volatile components such as solvents are reduced (or eliminated). , a very advantageous effect of having a glass transition temperature (Tg) equal to or higher than that of the resin alone. One embodiment of the present invention may include a fiber-reinforced laminate obtained by laminating the imide prepregs and heat-curing them.

The amount of residual volatile matter in the imide prepreg is preferably 20% by weight or less, more preferably 10% by weight or less, and even more preferably 7% by weight or less relative to the imide oligomer contained in the imide prepreg. . The volatile matter of the imide prepreg is mainly composed of the organic solvent used in the production of the amic acid oligomer, but also includes moisture desorbed from the amic acid oligomer whose imidization has not yet proceeded. If the amount of volatile matter remaining in the imide prepreg is within the above range, when a resin composite material (for example, a carbon fiber reinforced composite material) is produced using the imide prepreg, voids due to volatilization and decomposition of the solvent etc. Defects are reduced or eliminated, and a good composite material having a Tg equal to or higher than that of the resin alone can be obtained, which is preferable.

In addition, in one embodiment of the present invention, even with an imide oligomer having a relatively large molecular weight, an imide prepreg and a resin composite material can be produced without preparing a suspension of particulate imide oligomers. . Furthermore, the imide prepreg can maintain drape properties, and the obtained resin composite material has excellent heat resistance.

As used herein, the term "prepreg" means a resin-reinforcing fiber composite obtained by partially impregnating reinforcing fibers with particulate imide oligomers (semi-impregnated state). A "prepreg" contains a fiber arrangement that is not impregnated with a resin because it is in a semi-impregnated state, so that the drapeability is not impaired and the shapeability into a complicated shape is good. One form of "prepreg" often refers to a form having a resin-rich layer on the outer surface of reinforcing fibers.

The "drapability" means an index indicating the degree of suppleness of deformation of the resin-reinforced fiber composite. "Drapability" is an index that expresses the degree to which a resin-reinforced fiber composite conforms to a shape flexibly without breaking or breaking of reinforcing fibers when deformed along another object such as a mold. be. If the drape property is high, it is easy to shape into a curved surface, and if the drape property is low, it becomes difficult to shape into a curved surface. In addition, if the drape property is low, it naturally becomes difficult to form a press-molded product having a complicated shape.

The present invention is not limited to the above-described embodiments, but can be modified in various ways within the scope of the claims, and can be obtained by appropriately combining technical means disclosed in different embodiments. Embodiments are also included in the technical scope of the present invention.

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. In addition, all the pressures in the examples and comparative examples are actual pressures applied to the samples, and not indicated pressures (gauge pressures) of a press machine or the like.

[Various test methods for particulate imide oligomer]
(1) Measurement of Glass Transition Temperature (Tg) and Exothermic Start Temperature Measurement was performed using a Q100 (DSC) device manufactured by TA Instruments. The measurement conditions were 1st run: 40 to 450°C, temperature increase rate of 20°C/min, 2nd run: 40 to 500°C, temperature increase rate of 20°C/min. Then, the intersection point of the two tangent lines before and after the 2nd run heat flow (W/g) curve was lowered was defined as the glass transition temperature (Tg) of the particulate imide oligomer after curing. That is, the glass transition temperature (Tg) after curing of the particulate imide oligomer (powder) is the 2nd run Tg in DSC measurement. Further, when an exothermic peak was observed in the heat flow (W/g) curve, the temperature of the exothermic peak was defined as the curing exothermic peak temperature of the particulate imide oligomer.

(2) Measurement of imidization rate A particulate imide oligomer was dissolved in heavy DMF (deuterated N,N-dimethylformamide) as a measurement sample, and a proton nuclear magnetic resonance spectrometer (model: AV-400M, Co., Ltd.) was used. Peak areas were measured at 30° C. using ¹ H-NMR, manufactured by Bruker. Then, the imidization rate (mol%) of the particulate imide oligomer was calculated from the peak area derived from the aromatic ¹ H with a chemical shift of 7 to 9 ppm and the peak area derived from the residual amide ¹ H with a chemical shift around 11 ppm. bottom.

(3) Measurement of particle size distribution and average particle size A particulate imide oligomer was dispersed in water to prepare a measurement sample, and a laser diffraction particle size distribution measuring device (manufactured by Nikkiso Co., Ltd.: Microtrac) was used to measure particulate imide. The volume average particle size distribution of the oligomer was measured. The 50% cumulative volume average particle size was defined as the average particle size (μm) of the particulate imide oligomer.

(4) Tensile test Using Autograph AGS-X manufactured by Shimadzu Corporation, chuck distance: 20 mm, TS: 5 mm / min. A tensile test was performed to measure the mechanical properties (tensile modulus (N/mm ² ), breaking stress (N/mm ² ), and breaking strain (%)).

(5) Solubility test 10 g of N-methyl-2-pyrrolidone (NMP) was added to 0.1 g of particulate imide oligomer and stirred at room temperature for 1 hour so that the concentration was 1% by weight. A solubility test was performed by confirming the presence or absence of

(6) Particle shape An appropriate amount of particulate imide oligomer was taken, and the shape of aggregated particles was observed using an optical microscope (VHX-5000, manufactured by KEYENCE). Also, 3.7 g of methanol was placed in a screw tube, and after adding about 0.1 mg of particulate imide oligomer, ultrasonic waves were applied for 10 minutes using an ultrasonic cleaner. Then, the resulting suspension was collected with a Pasteur pipette, dropped on a glass plate, and thoroughly dried at room temperature in a fume hood. Then, the shape of each particle was observed by using an ultra-depth microscope (manufactured by KEYENCE Co., Ltd.) for the residue left after methanol was volatilized.

(7) Powder properties The powder properties of the particulate imide oligomer are relatively compared in terms of physical properties such as the difficulty of clumping and fluidity of the imide oligomer, and are good (A), somewhat good (B), normal (C ), Usable (Barely usable) (D), and Poor (E).

(8) Residual solvent rate A DMF (N,N-dimethylformamide) solution (concentration: about 20 mg/mL) of particulate imide oligomer was prepared and analyzed by GC/MS (GC: 6890N manufactured by Agilent technologies, MS: Agilent technologies 5973N, column: SUPELCOWAX 0.25 mm ID x 30 m), and the residual solvent ratio was determined.

The specific surface area and molecular weight of the particulate imide oligomer were measured by methods well known to those skilled in the art (BET specific surface area measurement method, molecular weight measurement method by GPC).

[Production Example 1]
After heating the inside of a 7 L autoclave equipped with a thermometer and stirrer to 45° C. with a heater, 1105 g (4.0 mol) of 2-phenyl-4,4′-diaminodiphenyl ether (Ph-ODA) and 1, A mixed solvent of 1650 g of 3-dioxolane and 1650 g of methanol (1:1 weight ratio) was introduced and nitrogen flow was started. After dissolving 2-phenyl-4,4′-diaminodiphenyl ether, 232.6 g of 1,2,4,5-benzenetetracarboxylic dianhydride (PMDA) was added to the autoclave three times at intervals (total of 697 .8 g (3.2 mol)) was added and polymerized at a set temperature of 45° C. for 3 hours to obtain an amic acid oligomer. 397.1 g (1.6 mol) of 4-(2-phenylethynyl) phthalic anhydride (PEPA) was added to the reaction solution containing this amic acid oligomer, and the ends were modified by reacting continuously for 1.5 hours. As a result, a solution of terminal-modified amic acid oligomer was obtained (solid concentration (theoretical value) = 2200/5500 = about 40% by weight).

The obtained terminal-modified amic acid oligomer has n=0, R ₁ is represented by a 2-phenyl-4,4′-diaminodiphenyl ether residue, and R ₃ is 1,2 in the above general formula (2). , 4,5-benzenetetracarboxylic acid dianhydride residues, with m=4 (tetramer) on average. The obtained solution of terminal-modified amic acid oligomer was used as varnish (N1).

[Production Example 2]
In a 3-necked 300 mL flask equipped with a thermometer and stir bar, 23.43 g (84.8 mmol) of 2-phenyl-4,4′-diaminodiphenyl ether and 82.5 g of N-methyl-2-pyrrolidone (NMP) and After dissolving the 2-phenyl-4,4′-diaminodiphenyl ether, 3.28 g (9.41 mmol) of 9,9-bis(4-aminophenyl)fluorene was added to the flask and stirred until dissolved. Subsequently, after adding 16.44 g (75.4 mmol) of 1,2,4,5-benzenetetracarboxylic dianhydride to the flask, nitrogen was sealed, and the polymerization reaction was performed at room temperature for 1.5 hours. Amic acid oligomers were obtained. 9.35 g (37.7 mmol) of 4-(2-phenylethynyl)phthalic anhydride and 15 g of NMP are added to the reaction solution containing this amic acid oligomer, and the reaction is performed at room temperature for 1.5 hours under nitrogen. was terminally denatured by Furthermore, a nitrogen inlet tube was attached to the flask, and the mixture was stirred at 200° C. for 5 hours under a nitrogen stream for imide bonding, followed by cooling to obtain an NMP solution of the terminal-modified imide oligomer (solid content concentration (theoretical value) = 52.5/150 = about 35% by weight).

The resulting terminal-modified imide oligomer is represented by the above general formula (1), wherein R ₁ is a 2-phenyl-4,4'-diaminodiphenyl ether residue or a 9,9-bis(4-aminophenyl)fluorene residue. , R ₂ is represented by a 9,9-bis(4-aminophenyl)fluorene residue, R ₃ and R ₄ are represented by 1,2,4,5-benzenetetracarboxylic dianhydride residues, On average, m=3.6 and n=0.4. An NMP solution of the obtained terminal-modified imide oligomer was used as varnish (N2).

[Example 1]
As a twin-screw extruder used in the melt processing step, MPU25TW (manufactured by Technobell Co., Ltd.), which is a co-directional twin-screw type, a screw diameter of 25 mmφ, and a maximum effective screw length (L/D) of 60, was used. The heater temperature of the cylinder part of the twin-screw extruder is set so that the varnish inlet (C0) is only water-cooled, the inlet side block (C1) is 40 ° C., and the downstream half block (C7 to C10) is 220° C. with a temperature gradient between them. No die was attached to the downstream end of the twin-screw extruder, leaving the die head open. The screw rotation speed was set to 30 rpm. This number of revolutions corresponds to a residence time of about 3 minutes.

When the varnish (N1) was charged from the varnish inlet (C0), yellow powder was discharged from the downstream end of the twin-screw extruder. Blocking was not observed in the obtained powder, and it had usable fluidity. No insoluble matter was identified in the solubility test. When this powder was measured by the various test methods described above, the imidization rate was 89.6 mol%, the average particle diameter was 312 μm (single peak with a shoulder), the specific surface area was 0.013 m ² /g, and the particle shape was irregular. It was fixed. The powder was therefore a particulate imide oligomer.

In addition, this powder was put into a hot press heated to 325° C. and preheated, and after confirming that it was melted, it was gradually pressurized and the air removal operation was repeated by pumping. After that, it is heated while applying a predetermined pressure, and after reaching 370 ° C. for 1 hour, the cured product film (press molded product) obtained by heating and pressing is subjected to a tensile test to determine the mechanical properties (tensile elasticity modulus at break, stress at break, and strain at break) showed good physical properties. Table 1 summarizes the results.

[Example 2]
Under the same conditions as in Example 1, except that the heater temperature of the cylinder part of the twin-screw extruder was 240 ° C. for approximately half of the blocks (C7 to C10) on the downstream side, the varnish (C0) from the varnish inlet (C0) N1) was introduced.

No blocking was observed in the obtained powder, and it had normal fluidity. No insoluble matter was identified in the solubility test. When this powder was measured by the various test methods described above, the imidization rate was 99.9 mol %, the average particle size was 393 μm (single peak with shoulder), and the particle shape was irregular. The powder was therefore a particulate imide oligomer.

Further, a cured product film obtained from this powder under the same conditions as in Example 1 was subjected to a tensile test to measure the mechanical properties, and good physical properties were obtained. Table 1 summarizes the results.

[Example 3]
Under the same conditions as in Example 1, except that the heater temperature of the cylinder part of the twin-screw extruder was set to 250 ° C. in approximately half of the blocks (C7 to C10) on the downstream side, the varnish (C0) from the varnish inlet (C0) N1) was introduced.

Blocking was not observed in the obtained powder, and it had rather good fluidity. No insoluble matter was identified in the solubility test. When this powder was measured by the various test methods described above, the imidization rate was 99.9 mol %, the average particle size was 407 μm (single peak with shoulder), and the particle shape was irregular. The powder was therefore a particulate imide oligomer.

Further, a cured product film obtained from this powder under the same conditions as in Example 1 was subjected to a tensile test to measure the mechanical properties, and good physical properties were obtained. Table 1 summarizes the results.

[Example 4]
The same conditions as in Example 1 except that the heater temperature of the cylinder part of the twin-screw extruder was set to 250 ° C. for approximately half of the blocks (C7 to C10, DH) on the downstream side, and the screw rotation speed was set to 100 rpm. , the varnish (N1) was introduced from the varnish inlet (C0). The above rotation speed corresponds to a residence time of about 1 minute.

Although blocking was not observed in the obtained powder, the flowability was unknown because the amount of the obtained powder was small. No insoluble matter was identified in the solubility test. When this powder was measured by the various test methods described above, the imidization rate was 99.0 mol %, the average particle size was 249 μm (single peak with shoulder), and the particle shape was irregular. The powder was therefore a particulate imide oligomer.

Further, a cured product film obtained from this powder under the same conditions as in Example 1 was subjected to a tensile test to measure the mechanical properties, and good physical properties were obtained. Table 1 summarizes the results.

[Example 5]
From the varnish inlet (C0) under the same conditions as in Example 1, except that the heater temperature of the cylinder part of the twin-screw extruder was set to 200 ° C. in approximately half of the blocks (C7 to C10, DH) on the downstream side. A varnish (N1) was introduced.

No blocking was observed in the obtained powder, and it had normal fluidity. No insoluble matter was identified in the solubility test. When this powder was measured by the various test methods described above, the imidization rate was 82.7 mol %, the average particle size was 184 μm (main peak, minor peak at 47 μm), and the particle shape was irregular. The powder was therefore a particulate imide oligomer.

Further, a cured product film obtained from this powder under the same conditions as in Example 1 was subjected to a tensile test to measure the mechanical properties, and good physical properties were obtained. Table 1 summarizes the results.

[Comparative Example 1]
The heater temperature of the cylinder part of the twin-screw extruder is set so that the varnish inlet (C0) is only water-cooled, the inlet side block (C1) is 40 ° C., the upstream intermediate block (C4) is 80 ° C., and the downstream side is Approximately half of the blocks (C6 to C10, DH) were set at 150° C., and a temperature gradient was set between them. The screw rotation speed was set to 10 rpm. This number of revolutions corresponds to a residence time of about 6 minutes. Other than that, under the same conditions as in Example 1, the varnish (N1) was introduced from the varnish inlet (C0).

When the varnish (N1) was charged from the varnish inlet (C0), yellow powder was discharged from the downstream end of the twin-screw extruder. Blocking was not observed in the obtained powder, and it had usable fluidity. No insoluble matter was identified in the solubility test. When this powder was measured by the various test methods described above, the imidization rate was 7.1 mol %, the average particle size was 55 μm (single peak), and the particle shape was irregular. Therefore, the powder was not substantially imidized and was not a particulate imide oligomer. Table 1 summarizes the results.

[Comparative Example 2]
The heater temperature of the cylinder part of the twin-screw extruder is set so that the varnish inlet (C0) is only water-cooled, the inlet side block (C1) is 40 ° C., the upstream intermediate block (C4) is 80 ° C., and the downstream side is Approximately half of the blocks (C6 to C10, DH) were set at 150° C., and a temperature gradient was set between them. The screw rotation speed was set to 30 rpm. This number of revolutions corresponds to a residence time of about 3 minutes. Other than that, under the same conditions as in Example 1, the varnish (N1) was introduced from the varnish inlet (C0).

When the varnish (N1) was charged from the varnish inlet (C0), yellow powder was discharged from the downstream end of the twin-screw extruder. Blocking was not observed in the obtained powder, and it had usable fluidity. No insoluble matter was identified in the solubility test. When this powder was measured by the various test methods described above, the imidization rate was 20.0 mol %, the average particle size was 48 μm (single peak), and the particle shape was irregular. Therefore, the powder was not fully imidized and was not a particulate imide oligomer. Table 1 summarizes the results.

[Comparative Example 3]
Without using a twin-screw extruder, pour the varnish (N1) into a glass container, leave it in a vacuum oven set at 45 ° C. for 18 hours, and then leave it in a hot air oven set at 250 ° C. for 1 hour. to give a yellow solid. That is, no powder was obtained.

When this solid was cut out and measured by the various test methods described above, the imidization rate was 99.9%. No insoluble matter was identified in the solubility test. A cured film obtained from this solid under the same conditions as in Example 1 was measured for mechanical properties by a tensile test, and the physical properties were good. Table 1 summarizes the results.

[Comparative Example 4]
100 g of varnish (N2) was put into 720 g of methanol, and the precipitated powder was separated by filtration. After repeating washing the obtained powder with 480 g of methanol for 30 minutes five times, the powder was separated by filtration. The obtained powder was dried under reduced pressure at 120° C. for 1 day to obtain a granular terminal-modified imide oligomer. Further, the obtained granular terminal-modified imide oligomer was pulverized with a hammer mill to obtain a terminal-modified imide oligomer powder.

Blocking was not observed in the obtained powder, and it had usable fluidity. No insoluble matter was identified in the solubility test. When this powder was measured by the various test methods described above, the imidization rate was 98.2 mol %, the average particle size was 71 μm (single peak), and the particle shape was irregular. Further, a cured product film obtained from this powder under the same conditions as in Example 1 was measured for mechanical properties by a tensile test, and the physical properties were good. Table 1 summarizes the results.

[Discussion on the results]
When comparing Examples 1 to 3, the heater temperature of the extruder (refers to the set temperature of approximately half blocks (C7 to C10) on the downstream side; the same applies hereinafter) from 220 ° C. to 240 ° C. and 250 ° C. , the imidization rate of the resulting powder (particulate imide oligomer) can be increased from 89.6 mol % to 99.9 mol %, and the fluidity of the powder is also improved.

Further, when comparing Example 3 and Example 4, by increasing the screw rotation speed, the retention time was shortened from 3 minutes to 1 minute while maintaining the imidization rate of the resulting powder (particulate imide oligomer). It can be seen that it is possible to increase production efficiency by

Comparing Example 1 and Example 5, even if the heater temperature of the extruder is lowered from 220°C to 200°C, powder (particulate imide oligomer) can be obtained without significantly lowering the imidization rate. I understand.

Comparing Examples 1 to 5 with Comparative Examples 1 to 2, when the heater temperature of the extruder is 150° C., the imidization rate is sufficiently high regardless of the screw rotation speed, that is, the residence time. It can be seen that a powder (particulate imide oligomer) having good physical properties cannot be obtained.

When comparing the physical properties of the cured film produced from the particulate imide oligomers obtained in Examples 1 to 5 with the physical properties of the cured film produced from the particulate imide oligomer obtained in Comparative Example 3 , are almost the same. However, in Comparative Example 3, it took 19 hours or more to obtain a solid from the varnish (N1), which is inferior in efficiency. Moreover, in Comparative Example 3, it is necessary to cut out the obtained solid and then process it into a cured product film, which is inferior in workability and handleability. In contrast, Examples 1 to 5 are found to be excellent in efficiency, workability and handleability.

In Comparative Example 4, a terminal-modified imide oligomer powder was obtained by a conventional production method (pulverization method). Therefore, in Comparative Example 4, reprecipitation from the varnish (N2) to obtain powder requires a large amount of methanol and a long time, resulting in poor efficiency. Moreover, in Comparative Example 4, the trouble of pulverizing with a hammer mill (pulverizer) is required to obtain a powder, and the workability and handleability are also inferior. In contrast, Examples 1 to 5 are found to be excellent in efficiency, workability and handleability.

INDUSTRIAL APPLICABILITY The present invention has excellent moldability, heat resistance, and excellent mechanical and electrical properties. It can be used as a material (heat-resistant composite material) in a wide range of fields such as peripheral) members.

Claims (3)

including a step of melt processing a solution of an amic acid oligomer represented by the following general formula (2) ;
The melt processing step is performed by a method of melt extrusion using an extruder,
In the melt processing step, the solution of the amic acid oligomer is melt-kneaded while heating, and the imidization reaction is performed while volatilizing the solvent and the water generated by the imidization reaction during the melt-kneading. A method for producing a particulate imide oligomer, comprising making the imide oligomer particulate.

(In the general formula (2), R ₁ and R ₂ represent divalent aromatic diamine residues which may be the same or different from each other, R ₃ and R ₄ may be the same or different from each other, represents a good tetravalent aromatic tetracarboxylic acid residue, one of _R5 and _R6 is a hydrogen atom and the other is a phenyl group, m and n are 1≤m, 0≤n, The relationships of 1≤m+n≤20 and 0.5≤m /(m+n)≤1 are satisfied, and the arrangement of the repeating units may be either block or random.) 2. The method for producing particulate imide oligomers according to claim 1 , wherein the melt processing is performed at a temperature of 250[deg.] C. or less. 3. The method for producing a particulate imide oligomer according to claim 1 , wherein the residence time in the extruder is 1 to 30 minutes.

Images