RU2279452C2 - Partially crystalline fusible polyimide binder and a composition for preparation thereof - Google Patents

Abstract

FIELD: polymer materials.

SUBSTANCE: invention, in particular, relates to partially crystalline fusible polyimide binder for heat-resistant materials used in aviation, automobile and ship construction, and construction. Composition of this binder contains 12-23% poly[4,4'-bis(4"-N-phenoxy)diphenyl]amido acid, 0.01-8% aromatic bisphthalamide or mixture of aromatic bisphthalamides, and amide solvent, said poly[4,4'-bis(4"-N-phenoxy)diphenyl]amido acid being based on aromatic tetracarboxylic acid selected from 3,3',4,4'-diphenyl oxide-tetracarboxylic acid, 3,3',4,4'-diphenyltetracarboxylic acid, and 1,3-bis(3',4-dicarboxyphenoxy)benzene and soluble in amide solvents for aromatic bisphthalamides. Partially crystalline fusible polyimide binder contains 60-99.9% poly[4,4'-bis(4"-N-phenoxy)diphenyl]imide and 0.1-40% bisphthalamide or mixture of aromatic bisphthalamides.

EFFECT: enabled preparation of polyimide binder capable of being recrystallized with reproducible degree of crystallinity and uniform distribution of crystalline structures, and increased heat and crack growth resistance of composite material.

Description

The invention relates to the chemistry of macromolecular compounds, specifically to a composition of a partially crystalline fusible polyimide binder for heat-resistant composite materials and a binder based on it.

The invention can find wide application in the manufacture of heat-resistant materials for aviation, automobile and shipbuilding, construction.

Composite materials based on partially crystalline fusible polyimide binders have several advantages over composites based on thermoplastic polyimide binders. Partially crystalline polyimides are characterized by excellent thermal and thermo-oxidative stability, high mechanical and adhesive characteristics, and increased resistance to aggressive media (Sroog C.E. Polyimides // Prog. Polym. Sci. 1991. V.16. P.561). The use of partially crystalline polyimide as a binder can significantly increase the heat resistance of the composite material, since in this case it is determined not by the glass transition temperature, but by the melting temperature of the polyimide. A distinctive feature of these binders is the ability to recrystallize, that is, to crystallize after melting in the finished composite material. However, a known problem in creating composite materials, including those based on polyimide binders, is to overcome the objectively existing contradiction between high heat resistance and crack resistance. The higher the heat resistance of the binder, the more brittle, and therefore, the composite material becomes susceptible to cracking. An urgent task is to search for chemical structures that can reach a compromise option that reduces the severity of this contradiction.

One of the first known partially crystalline fusible binders was obtained on the basis of LARC-TPI polyimide. Known binder has a significant drawback. In the manufacture of a composite material after melting of LARC-TPI at 270-290 ° С and impregnation of the filler (carbon fibers or fabric) obtained with the melt during subsequent cooling of the preform — prepreg — it becomes amorphous. Subsequently, the binder is practically incapable of transitioning to the crystalline state as a result of thermal annealing of the prepreg, unless additionally treated with an amide solvent (Hergenrother PM, Havens SJ Adhesive properties of LARC-CPI, a new semi-crystalline polyimide // SAMPE J. 1988. V 24. No. 4. P.13).

Binders based on partially crystalline fusible polyimides of the brand LARC-CPI, LARC CPI-2, PI-2 are known, which are capable of being processed in the melt and for further recrystallization in the composite material (Brandom D.K., Wilkes GL Study of the multiple melting behavior of the aromatic polyimide LARC CPI-2 // Polymer. 1994. V.35. No. 26. P.5672-5677). However, the slow rate of recrystallization of these binders, an insignificant proportion and uneven distribution of re-emerging crystalline structures in the volume of the binder indicate that they should be classified as thermoplastic rather than partially crystalline binders.

A polyimide binder is known for the manufacture of moldings and a composition for its preparation, which is a suspension formed by introducing insoluble additives — aromatic imide oligomers, bisimides and inorganic additives, for example titanium oxide (US 4906730, publ. 06.03.1990) into a solution of an aromatic polyester amide in an amide solvent. . The specified composition is impregnated with a carbon filler, the resulting prepregs are dried and pressed at a temperature of at least 300 ° C. The result is a composite material based on partially crystalline aromatic polyetherimide. The introduction of insoluble additives helps to accelerate the recrystallization of the binder in the composite after the final heat treatment. A disadvantage of the known binder is the uneven distribution of insoluble additives and, as a consequence, a different degree of crystallinity in the volume of the binder. Known composite materials are therefore susceptible to cracking.

Research Muellerleile J.T., Risch B.G., Rodriges D.E. (Crystallization behavior and morphological features of LARC-CPI // Polymer. 1993. V.34. No. 4. P.789-806) showed that the preparation of LARC-CPI compositions with insoluble bisimides also results in an uneven distribution of bisimide particles in the polymer matrix.

Previously, the inventors of the claimed invention obtained a polyimide binder for carbon plastics based on a partially crystalline fusible poly - {[4,4'-bis (4 '' - N-phenoxy) diphenyl] imide 1,3-bis (3 ', 4-dicarboxyphenoxy) benzene} and insoluble bisimides (Yudin V.E., Svetlichny V.M., Gubanova G.N. et al. Partially crystalline polyimides as binders for carbon plastics // Vysokomolek. Comp. 2002. T. A44, No. 2. S.257-267). A known analogue is a prototype of the claimed invention. The composition for preparing a binder is a suspension formed by introducing insoluble bisimides in an amount of up to 4 wt.% Into the solution of the corresponding polyamido acid (PAA) in an amide solvent, simulating the structure of an elementary unit or one of the fragments of the indicated polyimide - diamine or dianhydride. Despite the similarity of the structure of the polymer and bisimides, the same tendency is observed as that of the above known analogues, that is, there is an uneven distribution of bisimides in the prepreg. During subsequent imidization, this leads to a different degree of crystallinity in the binder volume in the composite material and to the manifestation of microdefects (brittle deformations) during its operation.

All currently known and the above technological approaches have not allowed to obtain composite materials using binders based on partially crystalline fusible polyimides, which simultaneously have a high level of heat resistance and crack resistance.

Thus, the problem of improving the quality of binders based on partially crystalline polyimides remains relevant.

The objective of the invention is the creation of a polyimide binder capable of recrystallization with a reproducible degree of crystallinity and with a uniform distribution of crystalline structures, and composite materials based on it with a high level of heat resistance and crack resistance. This problem is solved by the claimed group of two inventions - the composition of a partially crystalline fusible polyimide binder for a composite material and a partially crystalline fusible polyimide binder based on it, combined by a single inventive concept.

The inventive composition of a partially crystalline fusible polyimide binder for a composite material is characterized by the following set of essential features. The composition is a solution in an amide solvent of a poly- [4,4'-bis (4 '' - N-phenoxy) diphenyl] amido acid (PAA) based on an aromatic tetracarboxylic acid selected from the range: 3.3 ', 4.4' β-diphenyl oxide tetracarboxylic acid (DFO-TKA), 3,3 ', 4,4'-diphenyltetracarboxylic acid (DF-TKA), 1,3-bis (3', 4-dicarboxyphenoxy) benzene (P), and soluble in amide solvents aromatic bisphthalimide or a mixture of arbitrary composition soluble in amide solvents of aromatic bisphthalimides in the following ratio of components (wt.%):

poly- [4,4'-bis (4 '' - N-phenoxy) diphenyl] amido acid (PAA) - 12-23,

aromatic bisphthalimide or a mixture of aromatic bisphthalimides - 0.01-8;

amide solvent - up to 100.

The inventive composition includes as an aromatic bisphthalimide compound from the series:

4,4'-bis (phthalimido-4``-N-phenoxy) diphenylsulfone (X = SO ₂ ),

4,4'-bis (phthalimido-4 '' - N-phenoxy) diphenylpropane [X = C (CH ₃ ) ₂ ],

bis (phthalimido-4-N-phenyloxydiphenylsulfone) [bis (4'-hydroxy, 4 '' - N-phenylimide)

1,3-bis (3 ', 4-dicarboxyphenoxy) benzene] (X = SO ₂ ),

bis (phthalimido-4-N-phenyloxydiphenylpropane) [bis (4'-hydroxy, 4 '' - N-phenylimide)

1,3-bis (3 ', 4-dicarboxyphenoxy) benzene] (X = C (CH ₃ ) ₂ .

The inventive composition includes, as an amide solvent, a solvent from the series: N-methyl-2-pyrrolidone, N, N'-dimethylacetamide, N, N'-dimethylformamide.

The set of essential features of the claimed composition provides a technical result - improving the quality of the composition (uniform distribution of bisphthalimide in solution, its unexpected “affinity” for PAA), which subsequently provides thermal bonding to obtain a binder with reproducible (controlled) and uniform recrystallization.

The inventive composition differs from the known a number of essential features. Firstly, the claimed composition is a solution (varnish) (in the prototype - a suspension). Secondly, the composition of the claimed composition includes soluble in amide solvents bisimides, similar in structure but not identical to PAA units (the prototype method used bisimides insoluble in amide solvents, identical in structure to PAA units). In the claimed composition used a variety of PAA.

Analysis of the known scientific and technical level did not allow to find a solution that completely coincides in the aggregate of essential features with the claimed invention. This indicates the novelty of the claimed composition.

Only the combination of essential features of the claimed invention allows to achieve the above technical result. In the claimed invention used, in contrast to analogues, bisimides soluble in amide solvents having chemical fragments similar but not identical to the structure of polyimide. As indicated above, identical bisimides in structure are insoluble. Therefore, if the preparation of the claimed composition in the form of a solution could be expected, it was not obvious that bisimides that are not identical in structure to PAA units are combined at the molecular level with the polymer matrix in such a way that a binder is formed that is capable of uniform recrystallization. This allows us to claim compliance of the claimed invention with the eligibility condition "inventive step" ("non-obviousness").

The inventive binder has the following set of essential features. The partially crystalline fusible polyimide binder includes an aromatic tetracarboxylic acid poly- [4,4'-bis (4 '' - N-phenoxy) diphenyl] imide selected from the series; 3,3 ', 4,4'-diphenyl oxide tetracarboxylic acid (DFO-TKK), 3,3', 4,4'-diphenyltetracarboxylic acid (DF-TKK), 1,3-bis (3 ', 4-dicarboxyphenoxy) benzene (P) and aromatic bisphthalimide soluble in amide solvents homogeneously distributed therein, or a mixture of an arbitrary composition of aromatic bisphthalimide soluble in amide solvents, in the following ratio of components (wt.%):

poly- [4,4'-bis (4 '' - N-phenoxy) diphenyl] imide - 60-99.9;

aromatic bisphthalimide or a mixture of aromatic bisphthalimides - 0.1-40.

The inventive binder includes, as an aromatic bisphthalimide, a compound from the range: 4,4'-bis (phthalimido-4 '' - N-phenoxy) diphenylsulfone; 4,4'-bis (phthalimido-4``-N-phenoxy) diphenylpropane; bis (phthalimido-4-N-phenyl-oxydiphenylsulfone) [bis (4'-hydroxy, 4 '' - N-phenylimide) 1,3-bis (3 ', 4-dicarboxy-phenoxy) benzene]; bis (phthalimido-4-N-phenyloxydiphenylpropane) [bis (4'-hydroxy, 4 '' - N-phenylimide) 1,3-bis (3 ', 4-dicarboxyphenoxy) benzene].

The inventive binder can be obtained and used in solid form - powder, film - or in the form of a melt.

The set of essential features of the claimed binder provides a technical result - improving the quality of a partially crystalline polyimide binder, or rather achieving its reproducible (controlled) and uniform recrystallization. In turn, this technical result leads to an increase in heat resistance and at the same time elimination of defects and improvement of crack resistance of heat-resistant composite materials based on the claimed binders.

The inventive binder differs from the known bisphthalimides included in its composition and a large variety of polyimides used.

Analysis of the known scientific and technical level did not allow to find a solution that completely coincides in the aggregate of essential features with the claimed invention. This indicates the novelty of the claimed binder.

Only the combination of essential features of the claimed invention allows to achieve the above technical result. In the claimed invention used bisimides having chemical structure fragments similar, but not identical to the structure of polyimide. It turned out to be completely unobvious that these bisimides are combined at the molecular level with the polymer matrix and, as a whole, a composition is formed - a binder that is not only capable of recrystallization, but also reproducible and uniform recrystallization. Moreover, it is unexpected that the process of recrystallization occurs as quickly as when using peculiar crystallization “seeds” of insoluble bisimides in known analogues. Unexpected is the possibility of expanding the range of polyimides used, since it is known that the ability to recrystallize sensitively reacts to changes in the chemical structure of the polymer. This allows us to claim compliance of the claimed invention with the eligibility condition "inventive step" ("non-obviousness").

Thus, the group of claimed inventions as a whole has novelty and non-obviousness.

The proposed group of inventions allows to solve the problem of obtaining a polyimide binder capable of recrystallization with a reproducible degree of crystallinity and with a uniform distribution of crystal structures, and thereby improve the quality of the binder and composite material based on it.

To confirm the compliance of the claimed group of inventions with the requirement of "industrial applicability" we give examples of specific implementations.

Methods and devices:

DSC curves of the polyimide binder were recorded on a DSM-2M microcalorimeter in a scanning mode of 10 deg / min.

TGA curves were obtained on a modified MOM derivatograph in the air at a temperature rise rate of 10 deg / min.

The IR spectra of the samples were recorded on a Specord M-80 spectrophotometer; films on KBr were used.

XRD measurements were performed on diffractometer DRON-2 using CuK _α radiation filtered Ni. The samples were films or tablets pressed from a polyimide binder powder at room temperature and a pressure of 2 atm.

Dynamic mechanical analysis of the obtained carbon plastics was carried out in the temperature range of 20-400 ° C on a torsion pendulum (Yudin V.U., Leksovsky AM, Sukhanova T.E. et al. // Mechanics of composite materials. 1991. No. 3. P. 542 -546).

The interlayer fracture toughness G _IC (the start of the delamination crack) of carbon plastics with a thickness of about 3 mm was determined by the double cantilever method (Friedrich K., Walter R., Carisson LA at all // J. Mater. Sci., 1989. V.29. .3387-3398).

Electron microscopy was carried out using a MINI-SEM-V scanning electron microscope from AKASHI (Japan) in the secondary emission mode.

Components of the composition:

1. Synthesis of polyamic acid (PAA)

As monomers used selling

(a) acid dianhydride: 1,3-bis (3 ', 4-dicarboxyphenoxy) benzene (Tech.Chem.Prom. LLC, Yaroslavl) with a _mp = 163-164 ° C, recrystallized from dry acetic anhydride , 3,3 ', 4,4'-diphenyltetracarboxylic acid dianhydride (NIPIM, Tula) with T _pl = 224-226 ° C, recrystallized from dry acetic anhydride, 3,3', 4,4'-diphenyltetracarboxylic acid dianhydride (NIPIM, Tula) with T _pl = 286 ° C, recrystallized from dry acetic anhydride,

(b) diamine - 4,4'-bis (4``-aminophenoxy) diphenyl (CHRISKEV Co, LTd, US) with a _mp = 193-194 ° C, recrystallized from isopropyl alcohol. These monomers are purified by the method (Monomers for polycondensation. M: Mir. 1976. S.362).

Polyamic acid (PAA) was obtained in accordance with a two-stage standard method for the synthesis of polyimides (Bessonov M.I., Koton M.M., Kudryavtsev V.V., Laius L.A. Polyimides - thermally stable polymers // Consultant Bureau. New York. 1987). PAA was synthesized by introducing a stoichiometric amount of dianhydride into a solution of diamine in an amide solvent, N-methylpyrrolidone (or N, N'-dimethylacetamide, N, N'-dimethylformamide) with stirring at room temperature for 4 hours. The resulting PAA solution was used to prepare the composition .

2. Synthesis of bisphthalimides

Bisphthalimides were obtained by thermal imidization of bis-phthalamido acids formed in the medium of an amide solvent by reaction

a) 4,4'-bis (4``-aminophenoxy) diphenyl sulfone with phthalic anhydride;

b) 4,4'-bis (4``-aminophenoxy) diphenylpropane with phthalic anhydride;

c) 4,4'-bis (4``-aminophenoxy) diphenylsulfone with 1,3-bis (3 ', 4-dicarboxyphenoxy) benzene and phthalic anhydride;

d) 4,4'-bis (4``-aminophenoxy) diphenylpropane with 1,3-bis (3 ', 4-dicarboxyphenoxy) benzene and phthalic anhydride.

In the IR spectra of the products obtained after imidization, there are intense bands of 1720 and 1780 cm ^-1 , characteristic of the five-membered imide cycle.

Preparation of composition:

In the PAA solution obtained by the above method, bisphthalimides were added with stirring in the amount indicated in the claimed composition. The resulting solution was used to obtain prepregs for carbon plastics.

Obtaining composite materials:

Unidirectional carbon fabric (fiber) ELUR, or T-15 (P) -76 grade fiberglass, or CBM aramid fabric was impregnated with the claimed composition, and then the following drying mode was used to remove the solvent and carry out the imidization process:

80 ° C, 10 hours;

100 ° C, 1 h;

200 ° C, 1 h;

280 ° C, 1 h.

The prepregs thus obtained were packaged — stacked in a stack of 25 layers. The prepregs were pressed at a pressure of no more than 0.5 MPa and a temperature of 330 ° C for 10 min. The finished composite material was cooled to room temperature.

The inventive composition was also used to prepare a partially crystalline polyimide binder in its pure form. For this, the prepared varnish was imidized in the above mode and a binder was obtained in the form of a film or powder. To prepare carbon fiber, the ELUR carbon fabric was laid with the obtained binder film, followed by pressing prepregs at a pressure of not more than 0.5 MPa and a temperature of 330 ° C for 10 min. Or the claimed binder was melted and impregnated with a filler for carbon fiber. The finished carbon fiber was cooled to room temperature.

Example 1

6.45 g (0.0175 mol) of diamine-4,4'-bis (4``-aminophenoxy) diphenyl in 52.7 ml of N-methylpyrrolidone were charged into a 250 ml round bottom flask equipped with a stirrer and an argon feed tube. After complete dissolution of the diamine, 7.05 g (0.0175 mol) of 1,3-bis (3 ', 4-dicarboxyphenoxy) benzene dianhydride (P) was added to the reaction mixture in an argon stream, the solution was stirred until the dianhydride was completely dissolved. 1.5 g (0.0022 mol) of bisphthalimide - 4,4'-bis (phthalimido-4 '' - N-phenoxy) diphenyl sulfone was added to the solution of the resulting polyamido acid (PAA). The obtained 20% (wt.) Solution (varnish) with a PAA: bisphthalimide ratio = 90:10 contained 19.5% (wt.) PAA and 2.2% (wt.) Bisphthalimide and was used to prepare prepregs. The carbon fabric (fiber) ELUR was impregnated with varnish, dried at 80 ° C, 10 hours, then imidized in the following mode:

100 ° C, 1 h;

200 ° C, 1 h;

280 ° C, 1 h.

A prepreg was obtained on the basis of carbon fabric (fiber) and a partially crystalline polyimide binder with a polyimide: bisphthalimide ratio of 90 and 10% (wt.), Respectively, and a degree of crystallinity of 25%. The uniformity of the distribution of bisimide in the polymer system is confirmed by X-ray diffraction analysis.

The prepregs thus obtained were packaged in a stack of 25 layers. The prepregs were pressed at a pressure of 0.5 MPa and a temperature of 330 ° C for 10 min. After gradual cooling of the finished carbon fiber, binder recrystallization is observed, while the degree of crystallinity is maintained at 25%. The uniformity of the distribution of bisimide in the polymer system is confirmed by X-ray diffraction analysis.

The obtained carbon fiber has a heat resistance greater than 300 ° C (T _PL = 317 ° C), crack resistance G _IC = 650 J / m ² with a mechanical strength of the binder of 100 MPa and an elastic modulus of 4 GPa.

Structural characteristics, crystallinity, uniformity of the distribution of crystalline structures were monitored by x-ray and electron microscopy.

With repeated repetition of example 1, good reproducibility of the structural characteristics and properties of carbon fiber was observed.

Example 2

Conducted under the conditions of example 1, except for the concentration of the solution. A composition was prepared that contained 23% (wt.) PAA and 0.01% (wt.) Bisphthalimide.

The obtained carbon fiber has a heat resistance exceeding 300 ° C (T _PL = 310 ° C), crack resistance G _IC = 650 J / m ² with a mechanical strength of the binder of 120 MPa and an elastic modulus of 3.2 GPa. The degree of crystallinity is 15%, and the ratio of polyimide: bisphthalimide in a partially crystalline polyimide binder is 90 and 10% (wt.), Respectively.

Structural characteristics, crystallinity, uniformity of the distribution of crystalline structures were monitored by x-ray and electron microscopy.

With repeated repetition of example 2, good reproducibility of the structural characteristics and properties of carbon fiber was observed.

Example 3

Conducted under the conditions of example 1, except for the concentration of the solution.

A composition was prepared that contained 20% (wt.) PAA and 4% (wt.) Bisphthalimide.

Structural characteristics, crystallinity, uniformity of the distribution of crystalline structures were monitored by x-ray and electron microscopy.

The resulting carbon fiber has a heat resistance greater than 300 ° C (T _PL = 315 ° C), crack resistance G _IC = 630 J / m ² with a mechanical strength of the binder of 110 MPa and an elastic modulus of 3.9 GPa. Moreover, the degree of crystallinity is 25%.

With repeated repetition of example 3, good reproducibility of the structural characteristics and properties of carbon fiber was observed.

Example 4

Conducted according to the method of example 1. The ratio of polyimide: bisimide is 99 and 1% (wt.), Respectively.

The resulting carbon fiber has a heat resistance greater than 290-300 ° C (T _PL = 310 ° C), crack resistance G _IC = 660 J / m ² with a mechanical binder strength of 100 MPa and an elastic modulus of 3.8 GPa. Moreover, the degree of crystallinity is 20%.

Structural characteristics, crystallinity, uniformity of the distribution of crystalline structures were monitored by x-ray and electron microscopy.

With repeated repetition of example 4, good reproducibility of the structural characteristics and properties of carbon fiber was observed.

Example 5

Performed by the method of example 1.

Used 6.51 g (0.0177 mol) of diamine - 4,4'-bis (4``-aminophenoxy) diphenyl, 5.49 g (0,0177 mol) of dianhydride 3,3 ', 4,4'-diphenyl oxide tetracarboxylic acids, 52.7 ml of N-methylpyrrolidone; 3 g (0.0043 mol) of 4,4'-bis (phthalimido-4``-N-phenoxy) diphenyl sulfone.

A solution was prepared (varnish), which contained 17.4% (wt.) PAA and 4.4% (wt.) Bisphthalimide and was used to obtain a binder.

The ratio of polyimide: bisphthalimide in the obtained binder is 80 and 20% (wt.), Respectively.

The obtained carbon fiber has a heat resistance greater than 300 ° C (T _PL = 317 ° C), crack resistance G _IC = 550 J / m ² with a mechanical strength of the binder of 120 MPa and an elastic modulus of 4.3 GPa. Moreover, the degree of crystallinity is 30%.

Structural characteristics, crystallinity, uniformity of the distribution of crystalline structures were monitored by x-ray and electron microscopy.

With repeated repetition of example 5, good reproducibility of the structural characteristics and properties of carbon fiber was observed.

Example 6

Made according to example 5, N, N'-dimethylacetamide was used as a solvent. Received carbon fiber with characteristics similar to carbon fiber obtained in example 5.

Example 7

Made according to example 5, N, N'-dimethylformamide was used as a solvent. Received carbon fiber with characteristics similar to carbon fiber obtained in example 5.

Example 8

Performed by the method of example 5.

4.89 g (0.0136 mol) of diamine-4,4'-bis (4``-aminophenoxy) diphenyl, 4.12 g (0,0136 mol) of 3,3 ', 4,4'-diphenyl oxide tetracarboxylic dianhydride were used acids, 58.6 ml of N-methylpyrrolidone; 6 g (0.0204 mol) of 4,4'-bis (phthalimido-4``-N-phenoxy) diphenyl sulfone.

Prepared (varnish), which contained 12% (wt.) PAA and 8% (wt.) Bisphthalimide.

The ratio of polyimide: bisphthalimide in the obtained binder is 60 to 40% (wt.).

The obtained carbon fiber has a heat resistance exceeding 300 ° C (T _PL = 317 ° C), crack resistance G _IC = 560 J / m ² with a mechanical strength of the binder of 140 MPa and an elastic modulus of 4.4 GPa. Moreover, the degree of crystallinity is 35%.

Structural characteristics, crystallinity, uniformity of the distribution of crystalline structures were monitored by x-ray and electron microscopy.

With repeated repetition of example 8, good reproducibility of the structural characteristics and properties of carbon fiber was observed.

Example 9

Performed by the method of example 1.

Used 6.81 g (0.0185 mol) of diamine - 4,4'-bis (4``-aminophenoxy) diphenyl, 7.44 g (0,0185 mol) of dianhydride 1,3-bis (3 ', 4- dicarboxyphenoxy) benzene, 52.7 ml of N-methylpyrrolidone; 0.75 g (0.0005 mol) bis (phthalimido-4-N-phenyloxyphenylsulfone) - [bis (4'-hydroxy, 4 '' - N-phenylimide) 1,3-bis (3 ', 4-dicarboxyphenoxy) benzene].

A solution was prepared (varnish), which contained 20.7% (wt.) PAA and 1.1% (wt.) Bisphthalimide and was used to obtain a binder.

The ratio of polyimide: bisphthalimide in the resulting binder is 95: 5.

The obtained carbon fiber has a heat resistance greater than 300 ° C (T _PL = 315 ° C), crack resistance G _IC = 610 J / m ² with a mechanical strength of the binder of 110 MPa and an elastic modulus of 4 GPa. Moreover, the degree of crystallinity is 25%.

Structural characteristics, crystallinity, uniformity of the distribution of crystalline structures were monitored by x-ray and electron microscopy.

With repeated repetition of example 9, good reproducibility of the structural characteristics and properties of carbon fiber was observed.

Example 10

Performed by the method of example 1.

Used 6.45 g (0.0175 mol) of diamine - 4,4'-bis (4``-aminophenoxy) diphenyl, 7.05 g (0,0175 mol) of dianhydride 1,3-bis (3 ', 4- dicarboxyphenoxy) benzene, 52.7 ml of N-methylpyrrolidone; a mixture of bisphthalimides at a ratio of 70:30 - 0.525 g (0.00035 mol) bis (phthalimido-4-N-phenyloxyphenylsulfone) - [bis (4'-hydroxy, 4 '' - N-phenylimide) 1,3-bis (3 ', 4-dicarboxyphenoxy) benzene] and 0.225 g (0.00035 mol) of 4,4'-bis (phthalimido-4' '-N-phenoxy) diphenylpropane.

A solution was prepared (varnish), which contained 19.6% (wt.) PAA and 2.2% (wt.) Bisphthalimide and was used to obtain a binder.

The ratio of polyimide: bisphthalimide in the resulting binder is 95: 5.

The obtained carbon fiber has a heat resistance greater than 300 ° C (T _PL = 315 ° C), crack resistance G _IC = 600 J / m ² with a mechanical strength of the binder of 110 MPa and an elastic modulus of 4 GPa. Moreover, the degree of crystallinity is 25%.

Structural characteristics, crystallinity, uniformity of the distribution of crystalline structures were monitored by x-ray and electron microscopy.

With repeated repetition of example 10, good reproducibility of the structural characteristics and properties of carbon fiber was observed.

Example 11

Conducted according to example 1. Used bisphthalimide - 4,4'-bis (phthalimido-4 '' - N-phenoxy) diphenylpropane in an amount of 1.5 g (0.0022 mol).

The obtained carbon fiber has a heat resistance greater than 300 ° C (T _PL = 318 ° C), crack resistance G _IC = 600 J / m ² with a mechanical strength of the binder of 100 MPa and an elastic modulus of 4 GPa. Moreover, the degree of crystallinity is 25%.

Structural characteristics, crystallinity, uniformity of the distribution of crystalline structures were monitored by x-ray and electron microscopy.

With repeated repetition of example 11, good reproducibility of the structural characteristics and properties of carbon fiber was observed.

Example 12

Conducted according to example 1. Used bisphthalimide - bis (phthalimido-4-N-phenyloxyphenylpropane) [bis (4'-hydroxy, 4 '' - N-phenylimide) 1,3-bis (3 ', 4-dicarboxyphenoxy) benzene] in the amount of 1.5 g (0.001 mol).

The obtained carbon fiber has a heat resistance exceeding 300 ° C (T _PL = 317 ° C), crack resistance G _IC = 600 J / m ² with a mechanical strength of the binder of 110 MPa and an elastic modulus of 4 GPa. Moreover, the degree of crystallinity is 25%.

Structural characteristics, crystallinity, uniformity of the distribution of crystalline structures were monitored by x-ray and electron microscopy.

With repeated repetition of example 12, good reproducibility of the structural characteristics and properties of carbon fiber was observed.

Example 13

Conducted in the conditions of the known analogue of the prototype. According to x-ray studies, the resulting binder is characterized by a more defective structure. The value of G _IC (crack resistance) = 400 J / m ² .

Example 14

By the method of example 1, the claimed composition is obtained. The obtained varnish is not used to prepare the prepreg, but is applied to glass and subjected to heat treatment in the following mode:

drying - 80 ° C, 10 hours;

imidization:

100 ° C, 1 h;

200 ° C, 1 h;

280 ° C, 1 h.

After imidization and cooling to room temperature, the obtained partially crystalline polyimide binder in the form of a film was removed from the glasses. A partially crystalline polyimide binder is characterized by a ratio of polyimide: bisphthalimide = 90:10 and a crystallinity of 39.9%. Mechanical properties of the obtained binder: tensile strength at break - 100 MPa, elongation at break - 5%, elastic modulus - 3 GPa. The ability of the binder to recrystallize was tested. For this, the sample was heated to 330-340 ° C. Then it was gradually cooled to room temperature. The degree of crystallinity of the binder was 20-25%. The uniformity of the distribution of bisimide in the polymer system is confirmed by optical and electron microscopy. Preparation of carbon fiber: ELUR carbon fabric was laid with the obtained binder film, followed by pressing of the prepregs at a pressure of not more than 0.5 MPa and a temperature of 330 ° C for 10 min. Or, the claimed binder was melted at 330-340 ° C and soaked with a filler for carbon fiber. After cooling the finished carbon fiber, binder recrystallization is observed, while the degree of crystallinity is maintained at 25%. The uniformity of the distribution of bisimide in the polymer system is confirmed by optical microscopy. The obtained carbon fiber has a heat resistance greater than 300 ° C (T _PL = 317 ° C), crack resistance G _IC = 600 J / m ² with a mechanical strength of the binder of 100 MPa and an elastic modulus of 4 GPa.

Structural characteristics, crystallinity, uniformity of the distribution of crystalline structures were monitored by x-ray and electron microscopy.

With repeated repetition of example 14, good reproducibility of the structural characteristics and properties of carbon fiber was observed.

Example 15

Made in the conditions of example 1. As a filler for the composite material used fiberglass brand T-15 (P) -76.

The obtained fiberglass has a heat resistance greater than 300 ° C (T _PL = 315 ° C), crack resistance G _IC = 550 J / m ² with a mechanical strength of the binder of 110 MPa, an elastic modulus of 4 GPa. Moreover, the degree of crystallinity is 25%.

Structural characteristics, crystallinity, uniformity of the distribution of crystalline structures were monitored by x-ray and electron microscopy.

With repeated repetition of example 15, good reproducibility of the structural characteristics and properties of fiberglass was observed.

Example 16

Performed under the conditions of example 1. As the filler for the composite material used aramid fabric CBM.

The resulting organoplastic has a heat resistance greater than 300 ° C (T _PL = 315 ° C), crack resistance G _IC = 650 J / m ² with a mechanical strength of the binder of 110 MPa, an elastic modulus of 4 GPa. Moreover, the degree of crystallinity is 25%.

Structural characteristics, crystallinity, uniformity of the distribution of crystalline structures were monitored by x-ray and electron microscopy.

With repeated repetition of example 16, good reproducibility of the structural characteristics and properties of organoplastics was observed.

The implementation of the claimed invention is not limited to the above examples.

The data given in examples 1-12, 14-16, indicate that the inventive binder is capable of recrystallization. Crystal structures are homogeneously distributed in the composite material (carbon, glass, organoplastics) in the volume occupied by the binder. All the composite materials obtained have a heat resistance exceeding 300 ° C (T _pl = 310-317 ° C), crack resistance G _IC = 500-660 J / m ² (for the known analogue - 400 J / m ² ) with a mechanical strength of the binder of 100- 120 MPa, elastic modulus - 3.8-4.4 GPa. Moreover, the degree of crystallinity is 20-30%. Thus, it is possible to realize a set of properties that provide an increased level of heat resistance and crack resistance of the composite material.

Going beyond the stated interval parameters makes it impossible to implement the claimed invention.

Claims (5)

1. The composition of a partially crystalline fusible polyimide binder for a composite material, which is a solution in an amide solvent of a poly [4,4'-bis (4 '' - N-phenoxy) diphenyl] amide acid based on an aromatic tetracarboxylic acid selected from the range: 3 , 3 ', 4,4'-diphenyltetracarboxylic acid, 3,3', 4,4'-diphenyltetracarboxylic acid, 1,3-bis (3 ', 4-dicarboxyphenoxy) benzene, and aromatic bisphthalimide soluble in amide solvents or a mixture of any composition soluble in amide solvents aromatically x bisphthalimides, in the following ratio, wt.%: Poly- [4,4'-bis (4 '' - N-phenoxy) diphenyl] amido acid 12-23 Aromatic Bisphthalimide or a mixture of aromatic bisphthalimides 0.01-8 Amide solvent Up to 100 2. The composition according to claim 1, characterized in that, as an aromatic bisphthalimide, it comprises a compound selected from the series: 4,4'-bis (phthalimido-4 '' - N-phenoxy) diphenylsulfone; 4,4'-bis (phthalimido-4``-N-phenoxy) diphenylpropane; bis (phthalimido-4-N-phenyloxydiphenylsulfone) [bis (4'-hydroxy, 4 '' -N-phenylimide) 1,3-bis (3 ', 4-dicarboxyphenoxy) benzene], bis (phthalimido-4-N- phenyloxyphenylpropane) [bis (4'-hydroxy, 4 '' - N-phenylimide) 1,3-bis (3 ', 4-dicarboxyphenoxy) benzene]. 3. The composition according to claim 1, characterized in that as the amide solvent it comprises N-methyl-2-pyrrolidone, or N, N'-dimethylacetamide, or N, N'-dimethylformamide. 4. Partially crystalline fusible polyimide binder based on the composition according to claim 1 for the composite material, including aromatic tetracarboxylic acid poly- [4,4'-bis (4 '' - N-phenoxy) diphenyl] imide selected from the range: 3,3 ', 4,4'-diphenyltetracarboxylic acid, 3,3', 4,4'-diphenyltetracarboxylic acid, 1,3-bis (3 ', 4-dicarboxyphenoxy) benzene, and aromatic bisphthalimide homogenously distributed therein, soluble in amide solvents, or a mixture of an arbitrary composition of aromatic bisphthalimides soluble in amide solutions rer, with the following component ratio, wt.%: Poly- [4,4'-bis (4 '' - N-phenoxy) diphenyl] amide 60-99.9 Aromatic Bisphthalimide or a mixture of aromatic bisphthalimides 0.1-40 5. The binder according to claim 4, characterized in that, as an aromatic bisphthalimide, it includes a compound selected from the series: 4,4'-bis (phthalimido-4 '' - N-phenoxy) diphenyl sulfone; 4,4'-bis (phthalimido-4``-N-phenoxy) diphenylpropane; bis (phthalimido-4 ″ -N-phenyloxydiphenylsulfone) [bis (4′-hydroxy, 4 ″ -N-phenylimide) 1,3-bis (3 ', 4-dicarboxyphenoxy) benzene]; bis- (phthalimido-4-N-phenyloxydiphenylpropane) [bis (4'-hydroxy, 4 '' - N-phenylimide) 1,3-bis (3 ', 4-dicarboxyphenoxy) benzene].