JPH04268332A - Production of aromatic polyoxazole moleculary composite material - Google Patents

Abstract

PURPOSE:To produce a molecularly composite material excellent in mechanical strengths, etc. CONSTITUTION:A homogeneous solution of a precursor of an aromatic polyoxazole and a matrix polymer in an organic solvent is freed from the organic solvent and a ring closure reaction into an oxazole ring is effected by heating to produce molecularly composite material comprising a rigid polymer comprising the aromatic polyoxazole and the matrix polymer. This material is one in which can be artomatic polyoxazole is homogeneously dispersed in the matrix polymer and which is excellent in mechanical strength, heat resistance, dimensional 1accuracy, etc.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method for producing a molecular composite material of a rigid aromatic polyoxazole and a matrix polymer, and particularly to a molecular composite material suitable for use as a structural material for aircraft, automobiles, space equipment, etc. It relates to a method of manufacturing materials.

0002

[Prior art and problems to be solved by the invention] In recent years,
Plastic materials with excellent mechanical properties and heat resistance, called engineering plastics, have come to be used to reduce the weight of aircraft, automobiles, etc. In addition, in order to improve strength and rigidity, F
The development of composite materials such as RP has become active,
It is widely used in practical applications.

It is known that the strength of these composite materials is greatly influenced by the interfacial adhesion between the fibers and the matrix resin, in addition to the strength of the plastic or the fiber itself used as a reinforcing material. Furthermore, the quality of impregnating the reinforcing fiber preform with the matrix resin affects not only the manufacturing aspect but also the strength of the product. For these reasons, even if fibers or resins exhibiting high strength and high elasticity are used as materials, it is not always possible to obtain a composite material with excellent strength.

[0004] Therefore, by finely dispersing a so-called rigid polymer such as an aromatic polyamide down to the molecular level in a polymer serving as a matrix resin, a so-called polymer blend composite material (molecular composite material) was developed to overcome the above problems. However, attempts to obtain high-strength composite materials have been proposed and research and development efforts are underway.

[0005] Aromatic polymers suitably used in molecular composite materials include those having a heterocyclic ring such as an oxazole ring, a thiazole ring, an imidazole ring, and an oxazinone ring in the repeating unit. Due to its excellent mechanical strength, aromatic polyoxazole is considered promising as a reinforcing polymer for molecular composite materials.

By the way, even if one attempts to manufacture a molecular composite by simply mixing a reinforcing polymer and a matrix polymer, it is difficult to obtain uniform dispersion of the reinforcing polymer into the matrix polymer, and it is difficult to obtain a uniform dispersion of the reinforcing polymer into the matrix polymer. It is not possible to obtain molecular composites with excellent properties. To this end, various attempts have been made so far.

For example, Japanese Patent Application Laid-open No. 1-287167 discloses a reinforcing polymer (A) consisting of a polyazole having a substantially rod-like skeleton and a matrix polymer (B) having fusibility.
) A method for producing a polymer composite comprising introducing a polymer solution mainly containing A method for producing a polymer composite is disclosed in which a molecular solution is immersed in a coagulation bath and then post-coagulated via an apparently optically isotropic phase.

Further, Japanese Patent Publication No. 2-7976 discloses a reinforcing polymer A consisting of polyazole having a substantially rod-like skeleton, a glass transition temperature of 200° C. or more, a flow initiation temperature of 500° C. or less, and When the material is held at a temperature between the transition temperature and the flow start temperature for any period of time within 5 hours, the apparent crystal size formed is 25 Å.
Matrix polymer B consisting of a difficult-to-crystalline aromatic copolyamide as follows: A/(A+B)=0.15 to 0.
70 (by weight).

However, the method for producing a polymer composite disclosed in JP-A No. 1-287167 and JP-A No. 2-7
In the production of composite materials using the polymer composition disclosed in No. 976, uniform dispersion of the reinforcing polymer into the matrix polymer cannot be expected to be very uniform, and the mechanical strength etc. of the resulting molecular composite material does not improve significantly. . This seems to be because the reinforcing polymer exhibiting rigidity and the matrix do not have good compatibility, so that the reinforcing polymer and the matrix polymer are not sufficiently dispersed.

[0010] Therefore, an object of the present invention is to solve the above problems and provide a method for manufacturing a molecular composite material having excellent mechanical strength and the like.

[0011]

[Means for Solving the Problems] In view of the above problems, as a result of intensive research, the present inventors have discovered that an aromatic polyoxazole precursor and a matrix polymer are uniformly dissolved in an organic solvent, and after the organic solvent is removed, heating is performed. They discovered that it is possible to create a molecular composite material in which aromatic polyoxazole is uniformly dispersed in a matrix polymer, thereby completing the present invention.

That is, the method of the present invention for producing a molecular composite material from an aromatic polyoxazole and a matrix polymer comprises: (a) preparing a homogeneous solution of an aromatic polyoxazole precursor and a matrix polymer in an organic solvent; (b) After removing the organic solvent, heating is performed to cause an oxazole ring-closing reaction of the precursor.

The present invention will be explained in detail below. Aromatic Polyoxazole Precursor The aromatic polyoxazole precursor used in the present invention can be synthesized from an aromatic diaminodihydroxy compound and a dicarboxylic acid derivative.

An aromatic diaminodihydroxy compound is a compound having an amino group and a hydroxyl group on both sides of an aromatic residue, and the aromatic residue is not limited to a benzene ring, but an aromatic compound in which two or more benzene rings are condensed. It may be a ring,
It may also be one in which two or more benzene rings are bonded together, such as biphenyl. Further, the positional relationship between the amino group and the hydroxyl group on both sides may be bilaterally symmetrical or point symmetrical with respect to the aromatic residue. Examples of such aromatic diaminodihydroxy compounds include:

[Chemical formula 1] etc.

[0015] Note that among the above-mentioned aromatic diaminodihydroxy compounds, those having a substituent such as Cl on the aromatic residue may be used. These aromatic diaminodihydroxy compounds are preferably used in the form of a salt such as a hydrochloride to prevent deterioration.

As the aromatic diaminodihydroxy compound, 4,6-diamino-1,3-dihydroxybenzene (or a salt thereof) is particularly preferably used.

The dicarboxylic acid derivatives used in the present invention include those in which each carboxyl group is substituted as shown below.

embedded image Further, the residue of the dicarboxylic acid derivative described above is preferably an aromatic group, and for example, the following aromatic groups can be used.

embedded image Note that a halogen and/or a substituent such as a lower alkyl group, a lower alkoxyl group, or a phenyl group may be added to the aromatic residue. By introducing such a substituent, reactivity and solubility in a solvent can be improved.

Among such aromatic dicarboxylic acid derivatives, terephthalic acid dichloride or its halogen-substituted derivatives are particularly preferred, and specifically terephthalic acid dichloride, 2-chloroterephthalic acid dichloride, and 2,5-dichloroterephthalic acid dichloride are preferred. Dichloride and the like can be suitably used. Note that these aromatic dicarboxylic acid derivatives may be used alone or in combination of two or more.

In order to synthesize a polybenzobisoxazole precursor using the above-mentioned aromatic diaminodihydroxy compound and dicarboxylic acid derivative, first, the amino group and hydroxy group of the aromatic diaminodihydroxy compound are silylated, and then this It is preferable to react the silylated aromatic diaminodihydroxy compound and the dicarboxylic acid derivative. When a precursor is produced by silylating an aromatic diaminodihydroxy compound in this manner, a high molecular weight compound can be obtained in high yield.

In order to silylate the amino group and hydroxyl group of the aromatic diaminodihydroxy compound, the aromatic diaminodihydroxy compound or its salt, especially the hydrochloride, is
Treat with a nitrogen-containing silylating agent in an organic solvent or without a solvent at 80-140°C for 6-72 hours.

Nitrogen-containing silylating agents effective for such silylation reactions include hexamethyldisilazane, N,N
-diethylaminotrimethylsilane, N,N-diethylaminotrimethylsilane, N,O-bis(trimethylsilyl)carbamate, N-trimethylsilylimidazole, and the like.

[0022] Also, as an organic solvent for carrying out the silylation reaction,
Tetrahydrofuran, carbon tetrachloride, N,N-dimethylacetamide, etc. can be used, but the organic solvent can also be omitted. If the silylation temperature is lower than 80°C, the reactivity will not be sufficient, and if it is higher than 140°C, decomposition of the amine hydrochloride will occur, which is not preferable.

Once the silylated aromatic diaminodihydroxy compound is produced under the above conditions, the silylated aromatic diaminodihydroxy compound is then reacted with a dicarboxylic acid derivative to produce an aromatic polyoxazole precursor. . The reaction between the silylated aromatic diaminodihydroxy compound and the dicarboxylic acid derivative is carried out in an organic solvent under substantially anhydrous and oxygen-free conditions under dry N2 or argon gas, depending on the solvent used, but between -15 and 85
It may be carried out at ℃ for 2 to 20 hours. If the reaction temperature is less than -15°C, the reactivity is insufficient, and if it exceeds 85°C, oxidation of the above-mentioned reactants may occur. Preferably, the reaction temperature is -10 to 30°C.

[0024] By blending the silylated aromatic diaminodihydroxy compound and the dicarboxylic acid derivative in equimolar amounts, a high molecular weight polybenzobisoxazole precursor can be easily obtained.

Examples of the organic solvent used here include amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone, aromatic amine solvents such as pyridine, dimethyl Sulfur-based solvents such as sulfoxide and tetramethylsulfone, benzene, toluene, anisole, diphenyl ether,
Benzene solvents such as nitrobenzene and benzonitrile,
Ether solvents such as tetrahydrofuran and 1,4-dioxane; neutral solvents such as halogenated hydrocarbons such as chloroform, trichloroethane, and carbon tetrachloride;
c solvent).

Through this reaction, the silylated aromatic diaminodihydroxy compound and the dicarboxylic acid derivative undergo polycondensation as shown in the following reaction formula. In the reaction formula below, the silylated aromatic diaminodihydroxy compound is a silylated diaminodihydroxybenzene.

[Image Omitted] (In the formula, Ar is an aromatic residue, X is a halogen, Me
represents a methyl group. )

Next, the condensation polymer obtained in the above reaction is stirred in an alcohol such as methyl alcohol for several hours, and washing with alcohol is repeated to perform a desilylation treatment as illustrated in the reaction formula below. .

embedded image In this way, an aromatic polyoxazole precursor is obtained.

The aromatic polyoxazole precursor obtained can be washed and dried by known methods.

Matrix polymer Matrix polymers used in the present invention include aramid resins, polyether sulfones, polyetherimides, thermoplastic polyimides, thermosetting polyimides, polyamideimides, etc., but in particular aramid resins, polyamideimides, etc. It is preferable to use These resins have good compatibility with aromatic polyoxazole precursors and can provide molecular composites with excellent mechanical strength.

Next, the method for producing the molecular composite material of the present invention will be explained.

First, the aromatic polyoxazole precursor obtained above and the matrix polymer are dissolved in an organic solvent in which both can be well dissolved.

[0032] Examples of such organic solvents include N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), N,N-dimethylacetamide, etc., but they may be used as appropriate depending on the matrix polymer used. select. For example, when using an aramid resin as the matrix polymer, it is preferable to use DMSO as the solvent. Moreover, when using polyamideimide as a matrix polymer, it is preferable to use NMP.

[0033] The blending of the aromatic polyoxazole precursor and the matrix polymer has a reinforcing effect even if the blended amount of the aromatic polyoxazole is extremely small, but in the end, the weight ratio of the aromatic polyoxazole and the matrix polymer is It is preferable to set it within the range of 1:99 to 20:80. If the blending ratio of aromatic polyoxazole, which is a reinforcing polymer, becomes too large, its presence becomes too dense, and the aromatic polyoxazole aggregates with each other, resulting in poor dispersion at the molecular level. Such conditions are thought to reduce the mechanical strength of the molecular composite. A more preferable blending ratio is 1:99 to 10:90.

[0034] The aromatic polyoxazole precursor and the matrix polymer may be dissolved by any method as long as a homogeneous solution is obtained. For example, solutions of an aromatic polyoxazole precursor and a matrix polymer may be prepared, and then mixed to form a homogeneous solution, or a matrix polymer may be added to a solution in which the precursor is dissolved to form a homogeneous solution. Alternatively, both may be dissolved in one type of solvent at a time. The concentration of the final solution is preferably such that the total of the aromatic polyoxazole precursor and matrix polymer is 1 to 30% by weight.

The mixing time varies somewhat depending on the type of matrix polymer and solvent used, but is preferably about 6 hours to 30 days. Further, the temperature during mixing is preferably -15 to 150°C. Preparation and mixing of the aromatic polyoxazole precursor and matrix polymer solutions is performed using nitrogen gas,
It is preferable to carry out under an inert gas atmosphere such as argon gas or in vacuum.

[0036] After preparing a homogeneous solution, the solvent is evaporated to dry it, but in reality, it is better to dry it after forming it into a film by casting or spinning it. The composite of the aromatic polyoxazole precursor and the matrix polymer can be dried by a known method. Specifically, under an inert gas atmosphere or in vacuum, 4
Dry at 0-150°C, preferably 60-90°C.

Next, the composite of the aromatic polyoxazole precursor and matrix polymer obtained above is heated to cause an oxazole ring closure reaction in the precursor to obtain a molecular composite. The oxazole ring closure reaction at this time is, for example, as follows.

[C6]

[0038] A product in which the aromatic residue Ar is a phenylene group (poly-p-phenylenebenzobisoxazole) exhibits particularly good rigidity, and a molecular composite material using this as a rigid polymer has poor mechanical strength. Excellent.

[0039] The heating temperature of the homogeneous mixture of the precursor and the matrix polymer varies depending on the type of matrix polymer used, but is generally between 250°C and 400°C.
shall be. No formation of oxazole rings is observed when heated below 250°C. Further, heating above 450°C is not preferable because the polyoxazole and matrix polymer start to thermally decompose, and it is desirable to set the upper limit to 450°C.

Heating may be performed not only by a constant heating temperature but also by a heating program that changes the temperature in steps. For example, after heating at 120 °C for 30 minutes, increase the temperature to 350 °C in 30 minutes, and then heat at 350 °C for 30 minutes.
A heating program that holds the temperature for 0 minutes may also be used.

According to the method described above, the aromatic polyoxazole precursor uniformly dispersed at the molecular level in the matrix polymer becomes the aromatic polyoxazole as it is, so the aromatic polyoxazole and the matrix polymer are extremely close to each other at the molecular level. They will be well compatible. Therefore, the problem of reduced mechanical strength due to insufficient adhesion at the interface between aromatic polyoxazole molecules and matrix polymer molecules does not occur, resulting in a molecular composite material having good mechanical properties.

[0042]

[Operation] According to the present invention, the aromatic polyoxazole precursor and the matrix polymer are uniformly dissolved in an organic solvent, and then the organic solvent is removed, so that the aromatic polyoxazole precursor is dissolved in the matrix polymer. The dispersion becomes uniform. Therefore, the molecular composite material obtained by heating it becomes homogeneous and has excellent mechanical strength. Further, due to its homogeneity, various physical properties such as heat resistance are also improved.

[0043]

EXAMPLES The present invention will be explained in detail with reference to the following specific examples.

Example 1 (1) Synthesis of silylated aromatic diaminodihydroxy compound 4,6-diamino-1,3-dihydroxybenzene 12
1.1 g was put into a 200 ml eggplant-shaped flask with 150 g of hexamethyldisilazane, and the mixture was refluxed for about 12 hours, followed by atmospheric distillation followed by vacuum distillation.
g of N,N',O,O'-tetramethylsilyl-4,6
-Diamino-1,3-benzenediol (boiling point 147~
148°C (0.9mmHg), melting point 67.5-68.0
°C) was obtained.

(2) Synthesis of poly-p-phenylenebenzobisoxazole precursor N,N',O,O'-tetramethylsilyl-4,6-diamino-1,3- obtained in (1) above Thoroughly dry 2.1443 g of benzenediol, place it in a 100 ml four-neck flask that has been purged with argon, and add 10 ml.
of NMP (purity 99.1%, moisture 0.0099%) was added and dissolved at -5°C over about 1 hour.

Next, 1.1% of 2-chloroterephthalic acid dichloride (purity 99.1%, moisture 0.086%) was added to this.
87 g was added thereto, and the mixture was reacted at 0° C. under an argon atmosphere for about 6 hours with stirring.

About 50% of the resulting viscous red wine-colored transparent liquid
Pour into 00ml of methyl alcohol and stir for several hours.
Washing with methyl alcohol was repeated, followed by washing with ethyl alcohol, and the sample was dried under vacuum.

Infrared absorption spectrum analysis of the product and
1H-NMR was measured. Elemental analysis was also performed. Through the above analysis, it was confirmed that the obtained compound was as shown below.

[C7]

(3) Production of molecular composite material The polybenzoxazole precursor obtained above (intrinsic viscosity (ηinh
) is 2.0: In NMP, the concentration of polymer is 0.5 g.
/dl by the Ubbelohde method at 30°C) and an aramid resin (TX-
1. (manufactured by Toray Industries, Inc.), a plurality of molecular composite materials in which the amount of polybenzoxazole is 10% by weight or less based on the total polymer (total of polybenzoxazole and matrix polymer) are prepared in the following manner. Manufactured by.

First, in preparing a homogeneous solution of the precursor and the aramid resin, a total of 0.25 g of the polybenzobisoxazole precursor and the aramid resin was added to 10 ml of DMSO.
D to a total polymer concentration of 2.5% by weight.
An MSO solution was prepared. This operation was performed in an inert gas atmosphere. Mixing was carried out for one week at 40-60° C. with occasional stirring.

[0051] Next, the film was cast onto a glass plate by the doctor blast method to obtain a film with a thickness of 0.5 mm.

After drying the above film, it was heated at 350°C for 3
The mixture was heated under vacuum for 0 minutes to obtain a molecular composite.

(4) Physical property test Regarding the film-like molecular composite material obtained above, JI
Tensile modulus and tensile strength were measured according to S K7127. The results are shown in FIGS. 1 and 2, respectively.

Comparative Example 1 A film was produced in the same manner as in Example 1 using only the matrix polymer (aramid resin: TX-1, manufactured by Toray Industries, Inc.) used in Example 1. The tensile modulus and tensile strength were measured in the same manner as in Example 1. The results are shown in FIGS. 1 and 2, respectively.

Example 2 (1) Synthesis of thermosetting polyimide (matrix polymer) 4.3256 g (40 mmol) of p-phenylenediamine
) was dissolved in 80 ml of NMP at room temperature.

Next, 11.7689 g of 3,3'-4,4'-biphenyltetracarboxylic dianhydride was added, and 25
A polymerization reaction was carried out at ℃ for 3 hours to obtain polyamic acid.

(2) Production of molecular composite material (1) above
The polyamic acid obtained was diluted with NMP to give a concentration of 7.07% by weight.

Next, the polybenzobisoxazole precursor obtained in (2) of Example 1 was dissolved in a DMSO solution to prepare a DMSO solution having a precursor concentration of 2.22% by weight.

[0059] The above two types of solutions were mixed and heated at -15°C to prevent hydrolysis of the polyamic acid.
The mixture was mixed for one week with occasional stirring under an argon gas atmosphere to obtain a homogeneous solution.

The obtained solution was cast onto a glass plate by the doctor blade method to obtain a film with a thickness of 0.5 mm.

The above film was heat treated under vacuum according to the heat treatment program shown in FIG. 3 to obtain a film-like molecular composite material.

The tensile modulus of this molecular composite material was measured in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 2 A film was produced in the same manner as in Example 2 using only the matrix polymer (thermosetting polyimide) used in Example 2, and the tensile modulus was measured in the same manner as in Example 2. did. The results are also shown in Table 1.

Table 1 Example No. Amount of rigid polymer (
Weight%) Tensile modulus (Kgf/mm2)
Example 2 1.9
1531 Comparative example 2 0
1018

Example 3 A molecular composite material was produced using the polyoxazole precursor obtained in Example 1 (2) and polyamideimide powder (TORLON 4000T, manufactured by Amoco Corporation) as a matrix polymer. At this time, four types of molecular composite materials in which the amount of polybenzobisoxazole in the total polymer was in the range of 20% by weight or less were manufactured in the following manner.

First, in preparing a homogeneous solution of the precursor and polyamideimide, DMSO was used as a solvent and mixed in an argon gas atmosphere. This mixing was carried out for one week at 40-60° C. with occasional stirring. Next, Example 1
Similarly, it is formed into a film by casting, and after drying,
This was post-cured in vacuum at 260°C for 12 hours, and then heated at 300°C for 30 minutes.

The tensile modulus and tensile strength of the obtained film were measured in the same manner as in Example 1. The results are shown in FIGS. 4 and 5, respectively. Comparative Example 3 A film was produced in the same manner as in Example 3 using only the matrix polymer (polyamideimide) used in Example 3, and the tensile modulus and tensile strength were measured in the same manner as in Example 3. The results are shown in FIGS. 4 and 5, respectively.

[0068]

As detailed above, in the method of the present invention, the aromatic polyoxazole precursor can be well dispersed in the matrix polymer, so that the mechanical strength of the molecular composite material is improved. Moreover, heat resistance, solvent resistance, etc. are also improved. Furthermore, the coefficient of thermal expansion (coefficient of linear expansion) is reduced, and dimensional stability can also be improved.

The molecular composite material obtained by the method of the present invention has various properties such as good mechanical strength, heat resistance, and solvent resistance, so it is widely used in automobile parts, aircraft parts, space equipment, etc. can do.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the measurement results of the tensile modulus of the molecular composite material obtained in Example 1 and the sample of Comparative Example 1.

FIG. 2 is a graph showing the results of measuring the tensile strength of the molecular composite material obtained in Example 1 and the sample of Comparative Example 1.

FIG. 3 is a graph showing a heat treatment program for the film in Example 1.

4 is a graph showing the measurement results of the tensile modulus of the molecular composite material obtained in Example 3 and the sample of Comparative Example 3. FIG.

5 is a graph showing the results of measuring the tensile strength of the molecular composite material obtained in Example 3 and the sample of Comparative Example 3. FIG.

Claims (4)

[Claims] 1. A method for producing a molecular composite of a rigid polymer comprising an aromatic polyoxazole and a matrix polymer, comprising: (a) preparing a homogeneous solution of an aromatic polyoxazole precursor and a matrix polymer in an organic solvent; (b) A method characterized by causing an oxazole ring-closing reaction of the precursor by heating after removing the organic solvent. 2. The method according to claim 1, wherein the precursor is synthesized by reacting an aromatic diamino dihydroxy compound obtained by silylating the amino group and hydroxyl group with a dicarboxylic acid derivative. How to do it. 3. The method according to claim 1, wherein the matrix polymer is an aramid resin or a polyamideimide resin. 4. The method according to claim 1, wherein the aromatic polyoxazole is a poly-p-phenylenebenzobisoxazole having a substituted or unsubstituted phenylene group. Method.