RU2847840C1 - Method for obtaining carbon plastic with a gradient composition of modified powder phthalocyanine-benzoxazine binder (variants) - Google Patents

Abstract

FIELD: industrial chemistry.

SUBSTANCE: group of inventions relates to methods for producing reinforced carbon fibre composite with a gradient composition of a powder phthalonitrile-benzoxazine binder. Reinforced carbon fibre composite can be used in the manufacture of products from polymer composite materials used in instrument engineering, automotive, aviation, aerospace, electrical engineering, construction and other industries. Methods for producing reinforced carbon fibre composite with a composition gradient are carried out in two stages. In the first stage, a modified powder phthalonitrile-benzoxazine binder is obtained, for which 10-80 wt.% of solid phthalonitrile resin selected from FNI350 or VSN-31, 10-80 wt.% of bifunctional benzoxazine selected from compounds based on bisphenol A and aniline and based on diaminodiphenylmethane and phenol, and 8.4-9.8 wt.% of a solid epoxy resin selected from D.E.R.671 and ED-8, pre-blended with 0.2-1.6 wt.% of thermoplastic polymer powder selected from polyetherimide and polyethersulfone, are mixed and ground to obtain a homogeneous powder; the resulting mixture is extruded in a twin-screw mixer at a temperature of 70°C in zones I and II and 100°C in zone III; the resulting pre-extruded granules are ground to particles no larger than 100 μm. Methods for obtaining reinforced carbon fibre reinforced plastic include a second stage, in which carbon fibre reinforced plastic is obtained with a composition gradient of the modified powder phthalonitrile-benzoxazine binder obtained in the first stage. In one case, the specified binder is applied in an electrostatic field on both sides to carbon fabric fixed on a conductive frame, while the composition of the specified binder applied to each fabric is smoothly changed from the fabrics laid out on the surface layers to the central ones in such a way so that on the surface of the carbon plastic, the binder contains the maximum amount of solid phthalocyanine resin and the minimum amount of bifunctional benzothiazine, and the inner layers contain the maximum amount of bifunctional benzothiazine and the minimum amount of solid phthalocyanine resin. After spraying, the carbon fabric is heated to a temperature of 100°C, the powder binder melts and impregnates the carbon fabric due to the low surface tension of the powder binder melt with an electrostatic charge on the charged surface. The resulting impregnated sheets of carbon fabric with different binder compositions are assembled into a symmetrical technological package with a smooth change in the composition of the powder binder from the surface layers to the central ones, placed in a vacuum bag and consolidated, for which a vacuum pump is used to create a vacuum with a residual pressure of 50 mbar in the technological package, and then the temperature is raised to 120°C. The process package is then cooled, a consolidated plate is obtained, removed and used to produce a product by thermoforming between a die and a punch of a mould heated to a temperature of 250°C. In another case, the modified powder phthalocyanine-benzoxazine binder obtained in the first stage of one composition is applied in an electrostatic field on one side to carbon fabric laid out on a metal fixture, melted using an IR lamp, then subsequent layers of the specified binder of different composition are laid out and sprayed with melting on each layer, while the composition of the specified binder is smoothly changed from the surface layers to the central ones so that that on the surface of the carbon fibre reinforced plastic, the specified binder contains the maximum amount of solid phthalocyanine resin and the minimum amount of bifunctional benzene oxazine, and the inner layers contain the maximum amount of bifunctional benzene oxazine and the minimum amount of solid phthalocyanine resin. Then, a vacuum bag is assembled and a vacuum pump is used to create a vacuum with a residual pressure of 50 mbar in the process package, and then a stepwise temperature increase to 200°C is started and held for 1 hour. The process bag is then cooled, the carbon fibre composite with a gradient composition of modified powder phthalonitrile-benzoxazine binder is removed and placed in an oven for heat treatment at 250°C for at least 1 hour.

EFFECT: elimination of the use of solvents and prolonged high-temperature heating of the binder in the production of carbon plastic, production of carbon plastic with a gradient composition of the binder across the cross-section by changing the content of solid phthalonitrile resin, bifunctional benzoxazine and high-temperature thermoplastic polymer, obtaining carbon plastic with high mechanical properties, increased impact strength and heat resistance.

2 cl, 6 tbl, 20 ex

Description

The invention relates to a phthalonitrile-benzoxazine powder binder and a method for producing carbon fiber-reinforced plastic based on it, including one with a binder composition gradient. The invention can be used as a binder in the production of polymer composite materials for applications in instrument making, automotive, aviation, aerospace, electrical engineering, construction, and other industries.

Despite the many advantages of phthalonitrile and benzoxazine resins, one of their drawbacks is their crystalline or glassy state at room temperature and high viscosity at elevated temperatures. Therefore, the development of powder composites and the use of powder technologies is a pressing issue. An advantage of powder technology is the ability to precisely control the binder composition in different layers of the composite material. Layer-by-layer control of the binder composition is possible by mixing its components in different proportions, which allows for the creation of a binder composition gradient and, consequently, the desired properties of the composite material.

Surface and core layers of products have different requirements for technological (temperature and gelation time) and operational (thermophysical and mechanical) properties. Materials with a compositional gradient and, consequently, property ranges allow for the satisfaction of various operational and technological requirements.

A composite material of benzoxazine and epoxy resin modified with phthalonitrile, its preparation and use are known according to patent CN 105255109 B. The essence is: 1. A method for producing a composite material of benzoxazine and epoxy resin modified with phthalonitrile, which is characterized in that it includes the following stages: curing with a phthalonitrile-modified benzoxazine monomer and epoxy resin and obtaining a modified composite material based on phthalonitrile, benzoxazine and epoxy resin; The structural formula of the described benzoxazine monomer modified with phthalonitrile is shown in equation 1:

2. A method for producing a phthalonitrile-modified benzoxazine according to claim 1 and an epoxy resin-based composite material, characterized in that it comprises the following specific steps: (1) Obtaining a bisphenol-type benzoxazine compound: Bisphenol-A, paraformaldehyde and 4,4'-diaminodiphenylmethane are in a solvent. During the reaction, a compound of formula 2 is obtained;

(2) the compound of formula 2 obtained in step (1) is reacted with 4-nitrophthalonitriles obtained in the presence of an alkaline reagent and a solvent to obtain a compound of formula 1; (3) the compound of formula 1 obtained in step (2) is well mixed in the presence of a solvent with an epoxy resin, curing is gradually increased and a composite material of phthalonitrile-modified benzoxazine and an epoxy resin is obtained. 3. The method for producing phthalonitrile-modified benzoxazine according to claim 2 and a composite material based on an epoxy resin. It is characterized in that the molar ratio of 4,4'-diaminodiphenylmethanes, paraformaldehyde and bisphenol-A described in step (1) is 1:(4 ~ 5):2. 4. The method for producing phthalonitrile-modified benzoxazine according to claim 2 and a composite material based on an epoxy resin. It is characterized in that the molar ratio of the compound of formula 2 and 4-nitrophthalonitriles described in step (2) is 1:2. 5. A method for producing a phthalonitrile-modified benzoxazine according to claim 2 and an epoxy resin-based composite material. It is characterized in that the solvent described in step (1) is chloroform, dioxane, toluene, dimethylbenzene, dimethyl sulfoxide (DMSO), N,N. - At least one of dimethylformamide, DMAC N,N'-dimethylacetamide and 1-methylpyrrolidone; The alkaline reagent described in step (2) should consist of sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide and tripotassium phosphate, very little of one kind; The solvent described in step (2) is dimethyl sulfoxide (DMSO), N,N-dimethylformamide, DMAC N,N'-dimethylacetamide and N-methyl. At least one of pyrrolidones; The solvent described in step (3) is dichloromethane, chloroform, tetrahydrofuran, dioxane, toluene, dimethylbenzene, diformazane. At least one of base sulfoxide, N,N-dimethylformamide, DMAC N,N'-dimethylacetamide and 1-methylpyrrolidone. 6. The method for producing phthalonitrile-modified benzoxazine according to claim 2 and an epoxy resin-based composite material. It is characterized in that the reaction conditions described in step (1) are 60°C~120°C, the reaction time is 6~12 hours; The reaction conditions described in step (2) are 20-60°C and proceed for 6-24 hours. 7. The method for producing phthalonitrile-modified benzoxazine according to claim 2 and a composite material based on epoxy resin. It is characterized in that: the epoxy resin described in step (3) is a bisphenol type A epoxy resin, a bisphenol type f epoxy resin, a bisphenol type S ring. Oxygen tree fat, epoxy resins with a high amount of tetraglycidyl phenolic ethers, an epoxy resin based on an aliphatic glycidyl ether, an epoxy resin of the glycidyl ether type. At least one of the epoxy resins with a glycidyl amine type. 8. The method for producing phthalonitrile-modified benzoxazine according to claim 2 and an epoxy resin-based composite material. It is characterized in that the weight ratio of the compound of formula 1 and the epoxy resin described in step (3) is 1:10~10:1°C. The curing conditions described in step (3) are 60-300°C and the curing time is 12-60 hours. 9. A type of phthalonitrile-modified benzoxazine and epoxy resin composite material, characterized in that it is obtained according to any one of claims 1 to 8. 10. The phthalonitrile-modified benzoxazine described in claim 9 is an epoxy resin-based composite material and finds application in the electronics industry or aerospace technology.

The disadvantage of the known invention is the complexity of the technology, the use of solvents, and, in addition, the possibility of using the composition as a binder for carbon fiber reinforced plastics has not been shown.

Mixtures of benzoxazine and phthalonitrile resins are known according to patent US10556991B2. The essence is: 1. A resin mixture containing a mixture of benzoxazine resin and phthalonitrile resin, wherein the benzoxazine resin has Formula I or Formula II:

in which each R ¹ is H or an alkyl group and is an aliphatic aldehyde residue, R ² is a covalent bond or a polyvalent (hetero)hydrocarbyl group; R ³ and R ⁴ are independently selected from (hetero)hydrocarbyl residues of a primary amino compound; and z is at least 1; provided that neither R ³ nor R ⁴ belongs to formula III:

where R is selected from a covalent bond, a C4-C20 alkyl chain, -NH, phenol, biphenol, bisphenol, polyvalent phenol, imide, ether, thioether, amide, ester, or polyvalent (hetero)hydrocarbyl moiety;

in which each R ¹ is H or an alkyl group and is an aliphatic aldehyde residue, R ² is H, a covalent bond, phenol, or a polyvalent (hetero)hydrocarbyl group; R ⁴ is a (hetero)hydrocarbyl residue of a primary amino compound, R ⁴ (NH ₂ ) _m , with the proviso that R ⁴ is not a compound of Formula III above; wherein, when R ⁴ is an aryl group, m is 1-4; and x is at least 1; and wherein the phthalonitrile resin has Formula IV:

where R' is selected from H, a covalent bond, -C( _CH3 ) ₃ , a C4-C20 alkyl chain, _{-NO2, -NH2 ,} phenol, biphenol, bisphenol, polyvalent phenol, imide, ether, thioether, amide, ester, polyvalent (hetero)hydrocarbon residue; and y is at least 1; provided that R' does not refer to formula V or formula VI:

in which each R ¹ is H or an alkyl group and is an aliphatic aldehyde residue, R ² is a covalent bond or a polyvalent (hetero)hydrocarbyl group; R ³ and R ⁴ are independently selected from (hetero)hydrocarbyl residues of a primary amino compound; and

in which each R ¹ is H or an alkyl group and is an aliphatic aldehyde residue, R ² is H, a covalent bond, phenol, or a polyvalent (hetero)hydrocarbyl group; R ⁴ is a (hetero)hydrocarbyl residue of a primary amino compound, R ⁴ (NH ₂ ) _m , wherein when R ⁴ is an aryl group, m is 1-4; and x is not less than 1. 2. The resin mixture of claim 1, wherein the weight ratio of the phthalonitrile resin to the benzoxazine resin is from 2:98 to 99:1, inclusive. 3. The resin mixture of claim 1, wherein the weight ratio of the phthalonitrile resin to the benzoxazine resin is from 15:85 to 85:15, inclusive. 4. The resin mixture of claim 1, wherein the benzoxazine resin has Formula I and wherein R ² is a covalent bond or a divalent alkyl group. 5. The resin mixture of claim 1, wherein the benzoxazine resin has Formula II and wherein R 2 is H, a covalent bond, or a divalent alkyl group. 6. The resin mixture of claim 1, wherein the phthalonitrile resin comprises a multifunctional phthalonitrile. 7. The resin mixture of claim 1, wherein in Formula IV R' is phenol. 8. The resin mixture of claim 1, wherein the phthalonitrile resin has a melting point of 220°C or less. 9. The resin mixture of claim 1, further comprising at least one additive selected from a catalyst, a hardener, a thickener, a filler, and combinations thereof. 10. The resin mixture of claim 9, wherein the hardener comprises a thiol or an amine. 11. The resin mixture of claim 9, wherein the hardener comprises N-cyanoguanidine. 12. The resin mixture of claim 1, further comprising a second benzoxazine resin. 13. The resin mixture of claim 1, further comprising a second phthalonitrile resin.

A disadvantage of the known invention is that the areas of application for the obtained mixtures of benzoxazines and phthalonitriles are not shown, including the possibility of their use as binders for carbon fiber reinforced plastics, which does not make it possible to adequately and accurately identify their shortcomings.

Curable compositions of benzoxazine and phthalonitrile resins are known according to patent AU 2020372934 A1. The essence is 1. A polymerizable thermosetting composition containing (i) one or more acetylene-containing benzoxazine compounds and (ii) a phthalonitrile monomer. 2. A polymerizable thermosetting composition according to claim 1, in which one or more acetylene-containing benzoxazine compounds have the following structure:

In this case: each of R ₁ , R ₂ , R ₃ , R ₄ and R ₅ is independently selected from a hydrogen atom, a substituted or unsubstituted C ₁ -C ₂₀ alkyl group, a substituted or unsubstituted C ₂ -C ₂₀ alkenyl group, a substituted or unsubstituted C ₆ -C ₂₀ aryl group, a substituted or unsubstituted C ₂ -C ₂₀ heteroaryl group, a substituted or unsubstituted C ₄ -C ₂₀ carbocyclic group, a substituted or unsubstituted C ₂ -C ₂₀ heterocyclic group or a C ₃ -C ₈ cycloalkyl group; b is an integer ranging from 1 to 4, wherein: when b is 1, Z is a hydrogen atom, a substituted or unsubstituted C1- _C20 alkyl group, a substituted or unsubstituted _C2 - _C20 alkenyl group, a substituted or unsubstituted C6 _{-C20 aryl} group, a substituted or unsubstituted _C2 - _C20 heteroaryl group, a substituted or unsubstituted _C4 - _C20 carbocyclic group, a substituted or unsubstituted _C2 - _C20 heterocyclic group, or a _C3 - _C8 cycloalkyl group; each R ₁ is an alkynyl-substituted C ₁ -C ₂₀ alkyl group, an alkynyl-substituted C ₈ -C ₂₀ aryl group, an alkynyl-substituted C ₂ -C ₂₀ heteroaryl group, an alkynyl-substituted C ₄ -C ₂₀ carbocyclic group, an alkynyl-substituted C ₂ -C ₂₀ heterocyclic group, or an alkynyl-substituted C ₃ -C ₈ cycloalkyl group; when b is 2, Z represents a direct bond or a substituted or unsubstituted _C1 - _C20 alkyl group, a substituted or unsubstituted _C2 - _C20 alkyl group with an aryl or heteroaryl bridge, a substituted or unsubstituted _C2 - _C20 alkenyl group, a substituted or unsubstituted _C2 - _C20 alkynyl group, a substituted or unsubstituted _C6 - _C20 aryl group, a substituted or unsubstituted _C2 - _C20 heteroaryl group, O, S, S=0, 0=S=0, C=0 or C= _CC12 ; and when b is 3 or 4, Z is a substituted or unsubstituted _C1 - _C20 alkyl group, a substituted or unsubstituted _C2 - _C20 alkyl group with an aryl or heteroaryl bridge, a substituted or unsubstituted _C2 - _C20 alkenyl group, a substituted or unsubstituted _C2 - _C20 alkynyl group, a substituted or unsubstituted _C6 - _C20 aryl group, a substituted or unsubstituted _C2 - _C20 heteroaryl group; and each R 6 is an alkynyl-substituted C ₁ -C ₂₀ alkyl group, an alkynyl-substituted C ₈ -C ₂₀ aryl group, an alkynyl-substituted C ₂ -C ₂₀ heteroaryl group, an alkynyl-substituted C ₄ -C ₂₀ carbocyclic group, an alkynyl-substituted C ₂ -C ₂₀ heterocyclic group, or an alkynyl-substituted C ₃ -C ₈ cycloalkyl group. 3. The polymerizable thermosetting composition according to claim 1, wherein the phthalonitrile monomer is one or more compounds of the formula

In this case, each of R ₁ -R ₁₄ is independently selected from a hydrogen atom, a substituted or unsubstituted C ₁ -C ₂₀ alkyl group, a substituted or unsubstituted C ₂ -C ₂₀ alkenyl group, a substituted or unsubstituted C ₂ -C ₂₀ alkynyl group, a substituted or unsubstituted C ₆ -C ₂₀ aryl group, a substituted or unsubstituted C ₂ -C ₂₀ heteroaryl group; and Z is selected from a direct bond, a substituted or unsubstituted _C1 - _C20 alkyl group, a substituted or unsubstituted _C2 - _C20 alkyl group with an aryl or heteroaryl bridge, a substituted or unsubstituted _C2 - _C20 alkenyl group, a substituted or unsubstituted _C2 - _C20 alkynyl group, a substituted or unsubstituted _C6 - _C20 aryl group, a substituted or unsubstituted _C2 - _C20 heteroaryl group, O, S, S=0, 0=S=0, C=0, C(=0)0 or C= _CCl2 , or a polymer chain containing oxygen in each repeating unit of the polymer chain. 4. The polymerizable thermosetting composition according to claim 1, further comprising at least one of a monofunctional benzoxazine, a multifunctional benzoxazine and a mixture thereof. 5. A thermosetting polymer obtained by curing a thermosetting composition according to any one of claims 1 to 4. 6. A method of manufacturing a composite article, comprising contacting a layer of reinforcing fibers with a polymerizable thermosetting composition according to any one of claims 1 to 4 to coat and/or impregnate the reinforcing fibers; and curing the coated and/or impregnated reinforcing fibers to produce a composite article. 7. A method of manufacturing a composite article in an RTM system, comprising the steps of: a) introducing a fibrous preform containing reinforcing fibers into a mold; b) injecting the polymerizable thermosetting composition according to any one of claims 1 to 4 into the mold, c) allowing the thermosetting composition to impregnate the fibrous preform; d) heating the resin-impregnated preform for a certain period of time to produce at least a partially cured solid article; and optionally d) subjecting the partially cured solid article to additional heating. 8. A method for producing a composite article in a VaRTM system, comprising the steps of: a) introducing a fiber preform containing reinforcing fibers into a mold; b) injecting a thermosetting composition according to any one of claims 1-4 into the mold; c) reducing the pressure inside the mold; d) maintaining the shape at approximately the reduced pressure; e) allowing the thermosetting composition to impregnate the fiber preform; f) heating the resin-impregnated preform to obtain an at least partially cured solid article; and optionally g) subjecting the at least partially cured solid article to additional heating.

The disadvantage of the known invention is the complexity and duration of the process of mixing the components, as well as high temperatures of mixing the components (80-150°C); in addition, the known binder is designed for liquid-phase mixing and does not allow for the production of composites with a binder distribution gradient.

A method for producing carbon fiber reinforced plastics based on a heat-resistant binder is known according to patent RU 2572139 “Method for producing carbon fiber reinforced plastics based on a heat-resistant binder”. The essence is a method for producing carbon fiber reinforced plastic based on a heat-resistant binder, in which a binder in the form of a powder is placed on the surface of a fibrous carbon filler, the binder is melted, the filler is impregnated with it, and carbon fiber reinforced plastic is formed from the filler impregnated with the binder in a mold, characterized in that a phthalonitrile binder is used as a binder, and an equal-strength or unidirectional carbon fabric is used as a filler, a preform is formed (a preform is a blank made of dry reinforcing material (carbon, glass, organofiber or fabric) or vacuum infusion. The result is an article made of a composite material by superimposing layers of filler on top of each other with their mutual fixation using a solution of cyanogen ether in acetone in an amount of 3-10 wt. % of cyanogen ether to the weight of the said filler, placing the preform in the mold, placing a binder in the form of a powder on the surface of the preform or between the filler layers and vacuum impregnation of the preform with the molten binder is carried out at a binder temperature of 185-205°C for 30-60 minutes, then carbon fiber reinforced plastic is formed from the preform in a press mold in a stepwise heating mode, followed by heat treatment of the carbon fiber reinforced plastic in an inert atmosphere. 2. The method for producing carbon fiber reinforced plastic according to claim 1, characterized in that the binder is placed in the form of a powder on the surface of the preform or between its layers in a ratio of 1.0-1.3 to the weight of the filler. 3. The method for producing carbon fiber reinforced plastic according to claim 1, characterized in that a phthalonitrile binder is used as a binder, and the carbon fiber reinforced plastic is formed in a press mold in a stepwise heating mode to a temperature of 300°C, followed by heat treatment in an inert atmosphere at a temperature of 350-400°C.

The disadvantage of the known invention is the high impregnation temperatures (185-205°C), the use of a solvent in the process, and the high porosity of the composite, which accordingly leads to a wide range of mechanical properties of the composite and, as a consequence, to low, difficult to repeat consumer properties.

A phthalonitrile resin and a method for producing the same are known from patent CN113388106A "Phthalonitrile resin suitable for melt pre-soaking and a method for producing the same." The essence is a phthalonitrile resin suitable for processing prepregs from the melt, characterized in that it contains the following starting materials: a phthalonitrile resin monomer, a hardener and a modifier containing a benzoxazine ring. 2. A phthalonitrile resin suitable for producing a hot-melt prepreg according to claim 1, wherein the phthalonitrile resin is any of a bisphenol phthalonitrile resin, a biphenylphthalonitrile monomer and phenolphthalephthalonitrile. 3. A phthalonitrile-based resin suitable for processing the melt prepreg according to claim 1, characterized in that the method for producing a modifier containing a benzoxazine ring comprises the following steps: mixing dodecylphenol, p-hydroxybenzonitrile, paraformaldehyde and 4,4-diaminodiphenylmethane, adding to a xylene solvent, reacting at a temperature of 81-89°C for 3-6 hours and removing the solvent to obtain a low-melting modifier containing benzoxazine rings. 4. A phthalonitrile-based resin suitable for processing the melt prepreg according to claim 3, wherein the molar ratio of dodecylphenol to p-hydroxybenzonitrile is 0.5-0.8:0.2-0.5. 5. A phthalonitrile-based resin suitable for producing a prepreg melt according to claim 3, wherein the molar ratio of paraformaldehyde to 4,4-diaminodiphenylmethane is 4:0.9:1. 6. The phthalonitrile resin according to claim 3, characterized in that the molar ratio of the sum of the moles of dodecylphenol and p-hydroxybenzonitrile to 4,4-diaminodiphenylmethane is 2:0.9:1. 7. A phthalonitrile resin suitable for producing a prepreg melt according to claim 3, wherein the mass volume ratio of 4,4-diaminodiphenylmethane to xylene is 1 g: 1.3-1.6 ml. 8. The phthalonitrile resin of claim 1, wherein the hardener is ZnCl 2 and 4,4-diaminodiphenylsulfone in a molar ratio of 1:3-6, wherein the molar ratio of 4,4-diaminodiphenylsulfone to the phthalonitrile resin monomer is 2-4:100. 9. A method for producing a phthalonitrile resin suitable for melt processing of prepregs, characterized in that it includes the following steps: (1) a method for producing a phthalonitrile prepolymer includes the following steps: melting a bisphenol A type phthalonitrile resin monomer, adding a ZnCl 2 and 4,4-diaminodiphenylsulfone hardener, stirring at a constant temperature, stopping heating after completion of the reaction and cooling to obtain a phthalonitrile resin prepolymer; (2) a phthalonitrile resin was prepared by the following procedure: (3) mixing and stirring a low-melting modifier containing a benzoxazine ring and a phthalonitrile resin prepolymer, and cooling to obtain a phthalonitrile resin after completion of the reaction. 10. A method for producing a phthalonitrile resin suitable for processing a hot-melt prepreg according to claim 9, characterized in that the weight ratio of the modifier to the prepolymer is 0.3-0.5:0.5-0.7, and the mixing and stirring conditions in step (2) are as follows: stirring for 20-40 minutes at 80-110°C.

The disadvantage of this invention is the use of a solvent in the process, as well as the fact that the composition cannot be used as a powder binder, since the resulting binder is in a pasty state at room temperature.

A device and method for producing reactive polymer prepregs are known according to patent US 20100040857 A1 "Device and Method for Producing Reactive Polymer Prepregs". The essence is: 1. A method for producing a reinforcing material pre-impregnated with a reactive polymer, including: obtaining a substantially non-volatile composition containing substantially completely solid particles of at least one thermosetting thermosetting resin, wherein the only volatile components of the composition are residual water or residual solvent: applying a layer of the substantially non-volatile composition to a fabric or set of reinforcing fibers to be impregnated, wherein the particles of the substantially non-volatile composition are solid at ambient temperature and are applied to the fabric or set of reinforcing fibers to be impregnated at ambient temperature; and forming a prepreg by heating substantially all-solid particles of the substantially non-volatile composition such that the substantially all-solid particles partially melt, wherein the fabric or assembly is impregnated with the partially melted composition, and the partially melted solid particles of the substantially non-volatile composition adhere to the fabric or the plurality of reinforcing fibers. 2. The method of claim 1, comprising: applying heat and pressure or vacuum to the prepreg; substantially completely melting the partially melted particles of the composition; and substantially completely impregnating the fabric or the plurality of reinforcing fibers with the molten composition. 3. The method of claim 1, wherein the substantially all-solid particles of the composition are selected from the group consisting of epoxy resins, unsaturated polyester resins, vinyl ester resins, thermosetting polyurethane resins, phenol-formaldehyde resins (phenolic resins), polyimide resins, silicone resins, crosslinkable thermosetting resins. and combinations thereof. 4. The method of claim 1, wherein the substantially all-solid particles of the composition are pre-catalyzed, and the particles of the composition are substantially all-solid at room temperature. 5. The method of claim 1, wherein the fabric or aggregate of reinforcing fibers is selected from the group consisting of carbon fiber, glass fiber, basalt fiber, polymer fiber, aramid fiber, steel fiber, natural fiber and combinations thereof. 6. The method of claim 5, wherein the fabric or aggregate of reinforcing fibers is selected from the group consisting of roving, tape, web, weave, bi- or multiaxial fabrics, knitwear, braid, random mat, fleece and combinations thereof. 7. The method of claim 1, wherein the substantially all-solid particles of the composition are dried to remove moisture or solvent before applying the substantially all-solid particles of the composition to the fabric or aggregate of reinforcing fibers to avoid voids in the formed prepreg. 8. The method of claim 1, wherein the layer of substantially all-solid particles of the non-volatile composition is formed by depositing substantially all-solid particles of the non-volatile composition using a particle deposition device. 9. The method of claim 8, wherein the particle deposition unit is a powder spray device, and the deposition field of the spray device is from about 0 to about 4.0 m in width. 10. The method of claim 2, wherein applying heat and pressure or vacuum to the prepreg comprises curing in a low pressure two belt press. 11. The method of claim 2, wherein applying heat and pressure or vacuum to the prepreg comprises curing in a vacuum packaging process. 12. A drapeable, polymer-preimpregnated reinforcing material comprising: a porous substrate having at least one layer; and randomly disposed particles of a substantially non-volatile composition comprising at least one reactive thermosetting resin, wherein the only volatile components of the composition are residual water or solvent, wherein a portion of each of the randomly disposed particles is impregnated into the interstices of at least one layer of the porous substrate, and wherein the space therebetween separates adjacent randomly disposed particles. 13. The drapeable reinforcing material pre-impregnated with the polymer of claim 12, wherein the porous substrate having at least one layer comprises fiber-reinforced sheets impregnated with at least one reactive thermosetting resin(s) that can be subsequently cured to form the thermosetting composite sheet. 14. The drapeable reinforcing material pre-impregnated with a polymer according to claim 13, wherein the fibers of the fiber-reinforced sheets are selected from the group consisting of carbon fiber, glass fiber, basalt fiber, polymer fiber, aramid fiber, steel fiber, natural fiber and combinations thereof. 15. The drapeable reinforcing material pre-impregnated with a polymer according to claim 12, wherein the composition is selected from the group consisting of epoxy resins, unsaturated polyester resins, vinyl ester resins, thermosetting polyurethane resins, phenol-formaldehyde resins (phenolic resins), polyimide resins, silicone resins, crosslinkable thermosetting resins and combinations thereof. 16. The drapeable reinforcing material pre-impregnated with a polymer according to claim 15, wherein the crosslinkable thermoplastic resins are selected from the group consisting of crosslinkable polyethylene resins, crosslinkable polypropylene resins, crosslinkable polyvinyl chloride resins, crosslinkable polymers and combinations thereof. 17. The drapeable reinforcing material pre-impregnated with a polymer according to claim 12, wherein the composition is epoxy resin based or unsaturated polyester based, and wherein the epoxy resin based or unsaturated polyester based thermosetting resin(s) are solid at room temperature. 18. A method of forming a drapeable reinforcing material pre-impregnated with a polymer, comprising: providing a porous substrate having at least one layer; and forming an array of substantially non-volatile composition comprising substantially uniformly spaced and substantially completely solid reactive thermosetting particles, and coating thereon a portion of at least one layer, wherein the only volatile components of the composition are residual water or solvent: partially melting the array of substantially completely solid reactive thermosetting particles; and fixing the partially melted array by impregnating the melt into interstices of a portion of the at least one layer of a porous substrate, wherein the remaining portion of the at least one layer remains uncovered by the array. 19. The method of claim 18, wherein the substantially solid reactive thermosetting particles of the array have a melt viscosity of from about 5 cP to about 5000 cP. 20. The method of claim 18, wherein the porous substrate having at least one layer comprises fiber-reinforced sheets impregnated with at least one reactive thermosetting resin(s) that can be subsequently cured to form a thermosetting composite sheet. 21. The method of claim 18, wherein the substantially solid reactive thermosetting particles of the array are selected from the group consisting of epoxy resins, unsaturated polyester resins, vinyl ester resins, thermosetting polyurethane resins, phenol-formaldehyde resins (phenolic resins), polyimide resins, silicone resins, crosslinkable thermosetting resins, resins, and combinations thereof. 22. The method of claim 21, wherein the substantially solid reactive thermosetting particles of the array are pre-catalyzed, and the reactive thermosetting resin particles are solid at room temperature. 23. The method of claim 18, wherein the fibers of the porous substrate having at least one layer are selected from the group consisting of carbon fiber, glass fiber, basalt fiber, polymer fiber, aramid fiber, steel fiber, natural fiber, and combinations thereof. 24. The method of claim 18, wherein the fibers of the porous substrate having at least one layer are selected from the group consisting of roving, tape, web, weave, bi- or multiaxial fabrics, knitwear, braid, random mat, non-woven material, and combinations thereof. 25. The method of claim 18, wherein the substantially solid reactive thermosetting particles of the array are dried to remove moisture or solvent to avoid voids in the formed prepreg or in the composite sheet formed from the prepreg. 26. The method of claim 18, wherein the array of substantially uniformly spaced and substantially completely solid reactive thermosetting particles is formed by depositing substantially completely solid particles of at least one thermosetting thermosetting resin using a particle deposition apparatus. 27. The method of claim 26, wherein the powder application unit is a powder spraying device, and the application field of the powder device has a width of at least 4.0 m. 37. A method for producing a reinforcing material pre-impregnated with a reactive polymer, comprising: providing a substantially non-volatile mixture comprising substantially all-solid particles of a thermosetting thermosetting resin and substantially all-solid particles of a thermosetting thermoplastic resin, wherein the only volatile components of the substantially non-volatile mixture are residual water or solvent; applying a layer of the mixture to a fabric or assembly of reinforcing fibers to be impregnated, wherein the particles of the substantially non-volatile mixture are solid at ambient temperature and deposit on the fabric or assembly of reinforcing fibers to be impregnated at ambient temperature; and forming a prepreg by heating the particles of the substantially non-volatile mixture so that the solid particles partially melt, wherein the fabric or assembly is impregnated with the partially melted thermosetting resin, and the partially melted solid particles adhere to the fabric or assembly of reinforcing fibers. 38. The method of claim 35, wherein the thermoplastic resin comprises from about 0% to about 40% by weight of the composition and is insoluble in the molten composition. 39. The method of claim 36, wherein the substantially fully solid thermoplastic resin particles have a color different from the substantially fully solid thermosetting resin particles. 40. The method of claim 39, wherein the substantially fully solid thermoplastic resin particles have a viscosity different from the viscosity of the substantially fully solid thermosetting resin particles.

A disadvantage of the known invention is the lack of a composition of the curable composition and a description of only the general principles of prepreg production, which prevents the identification of its shortcomings when used for its intended purpose.

A method for producing a high-temperature composite material is known according to patent RU 2784939 “Method for producing a high-temperature composite material”. The essence is a method for producing a high-temperature composite material, characterized in that a binder is placed on the surface of a fibrous filler made of carbon reinforcing materials, the filler is impregnated layer by layer, the material is cured, while a reinforced silica filler is used as a filler, which is a silica thread woven into a knitted fabric, and in order to maintain its woven state, an arselon yarn is integrated into the latter, removed by heating to 400-600 ° C for 2-12 hours in an air atmosphere, the filler is impregnated with a powdered phthalonitrile binder, laying out the calculated amount of binder between the layers of the filler so that the lower and upper layers of the binder account for half the mass of the binder necessary for impregnation of the inner layers, sintering the powder at 50 ° C for 10 minutes after laying out each layer, and the total content of the binder in the composite mixture was 55% of its mass, the material is cured in an autoclave by heating to a temperature of 190°C at a rate of 0.5-2°C/min with a holding time of 4 hours under a pressure of 8 bar, after which the resulting composite material is post-cured at a temperature of 330°C for 8 hours and atmospheric pressure. 2. A high-temperature composite material obtained by the method according to claim 1, characterized in that it retains its structure at a temperature of 1450°C for 15 minutes, has a porosity of 1.2%, a density of 1564 kg/m3, a compressive strength of 204 MPa, a flexural strength of 102 MPa and a tensile modulus of elasticity of 9.5 GPa.

A disadvantage of the known invention is the high porosity of the composite, which accordingly leads to a large spread of the mechanical properties of the composite and, as a consequence, to low, difficult to repeat consumer properties.

A benzoxazine resin with terminal groups, a composite material based on bisphthalonitrile containing a benzoxazine resin with terminal groups and a composite curable resin according to patent CN115490824A are known. The essence is: 1. The blocked benzoxazine resin is a polymer with a main chain, and the molecular chain of the polymer with a main chain contains at least one of the repeating units represented by formulas (I-1) - (I-3):

1-1 1-2 1-3

the end of the molecular chain of the main chain type polymer has a structure shown in one of the formulas (I-4) to (I-9):

1-4 1-5 1-6 1-7 1-8 1-9

in formulas (I-1)-(I-9), each R is independently selected from an aliphatic group and its derivatives, an alicyclic group and its derivatives, an aromatic group and its derivatives, or one of the derivatives; and/or in formulas (I-4)-(I-6), R' is selected from one of an aliphatic group and its derivatives, an alicyclic group and its derivatives, or an aromatic group and its derivatives; and/or in formulas (I-7)-(I-9), each of R ₁ ″-R ₄ "is independently selected from hydrogen, an aliphatic group and its derivatives, an alicyclic group and its derivatives, an aromatic group and its derivatives. 2. 2. The capped benzoxazine resin with terminal groups according to claim 1, characterized in that in formulas (I-1)-(I-9), each R is independently selected from C2 to C20 alkyl groups and their derivatives, from C6 to C20. At least one of the aryl group and their derivatives, C6-C20 alicyclic groups and their derivatives and/or, in formulas (I-4)-(I-6), R' is selected from C1-C12 alkyl groups, C6-C12 alicyclic groups, phenyl or substituted phenyl groups; and/or, in formulas (I-7)-(I-9), each of R ₁ ″-R ₄ ″ is independently selected from hydrogen, C1-C12 alkyl groups and C6-C12 alicyclic rings; a base or phenyl. 3. The blocked benzoxazine resin with terminal groups according to claim 1 or 2, characterized in that in formulas (I-1)-(I-9), each R is independently selected from alkyl groups from C2 to C10 and their derivatives, from C6 to C10, at least one of an aryl group and its derivatives, cyclohexyl groups from C6 to C10 and their derivatives and/or; in formulas (I-4)-(I-6), R' is selected from a C1-C6 alkyl group, a C6-C8 alicyclic group or a phenyl group and/or; in formulas (I-7)-(I-9), each of R1 ″-R4 ″ is independently selected from hydrogen, alkyl groups C1-C6 and alicyclic groups C6-C8 or phenyl. 4. The method for producing a capped benzoxazine resin according to any one of claims 1 to 3, comprising: and mixing a monoamine compound and/or a monophenolic compound with a bisphenolic compound, a diamine compound and an aldehyde compound containing a spiroacetal structure for a reaction and carrying out a subsequent processing to obtain an end-capped benzoxazine resin. 5. The method according to claim 4, wherein the bisphenol compound having a spiroacetal structure is at least one compound selected from the group consisting of bis-p-hydroxybenzaldehyde pentaerythritol represented by formula (II), bis-m-hydroxybenzaldehyde pentaerythritol represented by formula (III), pentaerythritol bis-o-hydroxybenzaldehyde represented by formula (IV), and derivatives thereof:

III II IV

6. The production method according to claim 4, characterized in that the diamine compound is selected from aliphatic diamines and their derivatives, aromatic diamines and their derivatives, alicyclic diamines. At least one of its derivatives, preferably C2-C20 aliphatic diamines and their derivatives, C6-C20 aryl diamines; At least one of its derivatives, C6-C20 alicyclic diamine and its derivatives and/or, the aldehyde compound is selected from an aqueous solution of paraformaldehyde and/or formaldehyde, preferably paraformaldehyde and/or; the structure of the monoamine compound is R'-NH ₂ , preferably from aniline, methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, at least one of pentylamine, dodecylamine and octadecylamine and/or; The monophenolic compound is selected from at least one of phenol and a substituted phenol. 7. The method of preparation according to claim 4, characterized in that the molar ratio of the doses of bisphenol compounds, diamine compounds and aldehyde compounds containing a spirocyclic acetal structure is 1: 1: (2~5), preferably 1: 1: (2~3) and/or, the total molar amount of the monoamine compound and the monophenolic compound is equal to the molar amount of the bisphenol compound containing a spirocyclic acetal structure. The ratio between them is (1-2): 1, preferably (1-1.2): 1 and/or; The molar ratio of the monoamine compound and the monophenolic compound is (0-10): (10-0). 8. The method of preparation according to one of claims 4-7, characterized in that it comprises the following steps: step 1, mixing an aldehyde compound, a bisphenol compound containing a spiroacetal structure, and a diamine compound with a solvent and heating to pre-react; step 2, adding a monoamine compound and/or a monophenol compound to cap the ends after completion of the reaction; and 3, performing a post-treatment after the end-sealing to obtain an end-sealed benzoxazine resin. 9. The production method according to claim 8, characterized in that, in step 1, the solvent is selected from ethanol, methanol, isopropanol, butanol, isobutanol, tetrahydrofuran, dioxane, methane. One or more of benzene, dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone and/or; in step 1, the pre-reaction temperature is 80-150°C, preferably 90-130°C and/or; In step 1, the pre-reaction time is 0.2-5 hours, preferably 0.5-2 hours and/or; In step 2, endcapping is carried out for 5 to 20 hours, preferably 10 to 12 hours and/or; In step 3, the post-treatment includes alkali washing, water washing, desolvation treatment and drying. 10. A blocked benzoxazine resin obtained by the production method according to any one of claims 4 to 9. 11. A bisphthalonitrile-based composite material that contains a blocked benzoxazine resin and a bisphthalonitrile-based compound containing a spiroacetal structure, wherein the blocked benzoxazine resin is selected from the blocked benzoxazine resin according to any one of claims 1 to 3 or the blocked benzoxazine resin obtained by the method according to any one of claims 4 to 9. 12. The bisphthalonitrile-based composite material according to claim 11, wherein the benzoxazine is present in an amount of 10-90 wt.%, preferably 10-50 wt.%, based on 100 wt.% of the total weight of the bisphthalonitrile-based composite material; the proportion of the bisphthalonitrile compound containing a spiroacetal structure is 10-90 wt.%, preferably 50-90 wt.%. 13. A bisphthalonitrile-based composite curable resin, which is a product of ring-opening curing of the bisphthalonitrile-based composite material according to claim 11 or 12, preferably the ring-opening curing is carried out at a temperature of from 120 to 220°C; Preferably, the temperature is increased from 120°C to 220°C, each temperature gradient is 10-30°C, and each temperature gradient is reacted within 1-3 hours.

The disadvantage of the known invention is that it only shows an increase in the thermal stability of phthalonitrile due to the introduction of benzoxazine with terminal groups; the invention does not disclose the possibility of using this composition as a powder binder for the production of carbon fiber reinforced plastics, which prevents its effective use for its intended purpose.

The identified analogues coincide with the declared technical solution in terms of individual matching features, therefore the prototype is not defined, and the invention formula is drawn up without a limiting part.

The technical result of the claimed technical solution is the development of a method for producing carbon fiber reinforced plastic with a gradient composition of a modified powder phthalonitrile-benzoxazine binder (variants), which makes it possible to achieve:

1 - elimination of the use of solvents in the production of carbon fiber;

2 - elimination of long-term high-temperature heating of the binder during the production of carbon fiber reinforced plastic due to the use of powder spraying;

3 - obtaining carbon fiber reinforced plastic with high mechanical properties due to the selection of binder components and carbon fiber manufacturing technology;

4 - obtaining carbon fiber reinforced plastic with a gradient of binder composition across the cross-section by changing the content of solid phthalonitrile resin, bifunctional benzoxazine and thermoplastic polymer;

5 - increasing the impact strength and heat resistance of carbon fiber reinforced plastic through the use of a thermoplastic polymer.

The essence of the claimed technical solution is a method for producing carbon fiber reinforced plastic with a gradient composition of a modified powder phthalonitrile-benzoxazine binder, which consists in the fact that in stage 1 a modified powder phthalonitrile-benzoxazine binder is obtained, for which 10-80 wt. % of a solid phthalonitrile resin selected from FNI350 or VSN-31, 10-80 wt. %. of a bifunctional benzoxazine selected from compounds based on bisphenol A and aniline and based on diaminodiphenylmethane and phenol, and 8.4-9.8 wt. % of a solid epoxy resin selected from D.E.R.671 and ED-8, preliminarily mixed with 0.2-1.6 wt. % of thermoplastic polymer powder selected from polyetherimide and polyethersulfone, they are mixed and ground until a homogeneous powder is obtained; the resulting mixture is extruded in a twin-screw mixer at a temperature of 70°C - I and II zones, 100°C - III zone; the resulting extruded granules are ground to particles no larger than 100 µm; at the 2nd stage, carbon fiber reinforced plastic with a gradient of the composition of the modified powder phthalonitrile-benzoxazine binder according to paragraph 1 is obtained, for which purpose the said binder is applied in an electrostatic field on both sides of the carbon fabric fixed on a conductive frame, wherein the composition of the said binder applied to each fabric is smoothly changed from the fabrics laid out on the surface layers to the central ones in such a way that on the surface of the carbon fiber reinforced plastic the binder contains the maximum value of solid phthalonitrile resin and the minimum value of bifunctional benzoxazine, and the inner layers contain the maximum value of bifunctional benzoxazine and the minimum value of solid phthalonitrile resin; after spraying, the carbon fabric is heated to a temperature of 100 °C, the powder binder melts and impregnates the carbon fabric due to the low surface tension of the melt of the powder binder with an electrostatic charge on the charged surface; The obtained impregnated carbon fabric sheets with different binder compositions are collected in a symmetrical process package with a smooth change in the composition of the powder binder from the surface layers to the central ones, placed in a vacuum bag and consolidation of the process package is carried out, for which a vacuum with a residual pressure of 50 mbar is created in the process package using a vacuum pump, and then the temperature is raised to 120 °C; then the process package is cooled, a consolidated plate is obtained, it is removed and used to produce a product by thermoforming between the matrix and the punch of a mold heated to a temperature of 250 °C. A method for producing carbon fiber with a gradient of the composition of a modified phthalonitrile-benzoxazine powder binder, consisting in the fact that in the 1st stage a modified phthalonitrile-benzoxazine powder binder is obtained, for which 10-80 wt. % of a solid phthalonitrile resin selected from FNI350 or VSN-31, 10-80 wt. %. of a bifunctional benzoxazine selected from compounds based on bisphenol A and aniline and based on diaminodiphenylmethane and phenol, and 8.4-9.8 wt. % of a solid epoxy resin selected from D.E.R.671 and ED-8, preliminarily mixed with 0.2-1.6 wt. % of a thermoplastic polymer powder selected from polyetherimide and polyethersulfone, they are mixed and ground to obtain a homogeneous powder; the resulting mixture is extruded in a twin-screw mixer at a temperature of 70 ° C - I and II zones, 100 ° C - III zone; the resulting extruded granules are ground to particles no more than 100 μm in size; at the 2nd stage, carbon fiber reinforced plastic with a gradient of the composition of the modified powder phthalonitrile-benzoxazine binder according to paragraph 1 is obtained, for which the modified powder phthalonitrile-benzoxazine binder according to paragraph 1 of one composition is applied in an electrostatic field on one side to carbon fabric laid out on a metal tooling, melting is carried out using an IR lamp, then subsequent layers of said binder of different compositions are laid out and sprayed with melting on each layer, wherein the composition of said binder is smoothly changed from the surface layers to the central ones in such a way that on the surface of the carbon fiber reinforced plastic, said binder contains the maximum value of solid phthalonitrile resin and the minimum value of bifunctional benzoxazine, and the inner layers contain the maximum value of bifunctional benzoxazine and the minimum value of solid phthalonitrile resin; The vacuum bag is assembled and a vacuum with a residual pressure of 50 mbar is created in the process package using a vacuum pump, and then a stepwise increase in temperature is started to 200 °C and held for 1 hour; then the process package is cooled, the carbon fiber reinforced plastic with a gradient of the modified powder phthalonitrile-benzoxazine binder composition is removed and placed in an oven for heat treatment at 250 °C for at least 1 hour.

The claimed technical solution is illustrated in Fig. 1 - Fig. 6.

Fig. 1 shows Table 1, which lists the compositions of the modified phthalonitrile-benzoxazine powder binder according to Examples 1-16.

Fig. 2 shows Table 2, which shows the composition of the modified phthalonitrile-benzoxazine powder binder in carbon fiber reinforced plastic layers with a binder composition gradient according to Example 17.

Fig. 3 shows Table 3, which shows the composition of the modified phthalonitrile-benzoxazine powder binder in carbon fiber reinforced plastic layers with a binder composition gradient according to Example 18.

Fig. 4 shows Table 4, which shows the composition of the modified phthalonitrile-benzoxazine powder binder in carbon fiber reinforced plastic layers with a binder composition gradient according to Example 19.

Fig. 5 shows Table 5, which shows the composition of the modified phthalonitrile-benzoxazine powder binder in carbon fiber reinforced plastic layers with a binder composition gradient according to Example 20.

Fig. 6 shows Table 6, which lists the characteristics of the modified phthalonitrile-benzoxazine powder binder and carbon fiber reinforced plastic, including the binder composition gradient.

The applicant then provides a description of the claimed technical solution.

The declared technical solution used the following equipment and source components, and the relevant GOSTs and/or Standards are applied.

Flexural strength was determined according to GOST R 56810-2015 "Polymer Composites. Method of Flexural Testing of Flat Specimens." The impact strength of cured binders was determined according to GOST 4647-2015 "Plastics. Method for Determining Charpy Impact Strength."

Heat resistance was determined based on the glass transition temperature of cured samples using dynamic mechanical analysis on a DMA 242 E (NETZSCH) device at a heating rate of 5 K/min.

Solid phthalonitrile resins were used to prepare the powder binder: FNI350 (ITEKMA, Moscow) TU 20.14.43-002-73047899-2020 from the manufacturer JSC INUMiT (Moscow) and VSN-31 (FSUE VIAM, Moscow) (phthalonitrile binder powder grade VSN-31, consisting of tetranitrile of aromatic tetracarboxylic acid - 1,3-bis (3,4-dicyanophenoxy) benzene and aromatic diamine)

As a bifunctional benzoxazine, bifunctional benzoxazine compounds based on: bisphenol A and aniline (BPAA), diaminodiphenylmethane and phenol (DADPMF), which are solid powder compositions, were used:

BFAA DADFMF

Bifunctional benzoxazines were synthesized according to the procedure described in patent US5543516. The method for preparing the desired benzoxazine compound involves preparing a substantially homogeneous reaction mixture that includes a phenolic compound; a primary amine; and an aldehyde, but no solvent, except for any solubility the reactants may have with respect to one another. After preparation, the reaction mixture is maintained at a temperature and for a period of time sufficient for the reactants to chemically combine to form the desired compound.

Thermoplastic polymers were used as a modifier to increase the impact strength of carbon fiber reinforced plastics: polyetherimide PEI (grade Ultem 1000, “General Electric”), polyethersulfone PESF (grade Ultrason E 2020P SR, BASF)

The following solid epoxy resins based on bisphenol A were used: D.E.R.671, ED-8.

The content of components is selected based on the combination of optimal properties of the binder (heat resistance and mechanical properties).

Plain weave carbon fabrics with a surface density of 200 g/ ^cm2 were used as reinforcing filler.

In order to achieve the stated technical result in the stated modified powder phthalonitrile-benzoxazine binder (hereinafter referred to as the stated binder), compositions have been developed that include a solid phthalonitrile resin, a solid bifunctional benzoxazine, a solid epoxy resin and a thermoplastic polymer in the following quantity, wt. %:

Solid phthalonitrile resin - 10-80

Bifunctional benzoxazine - 10-80

Solid epoxy resin - 8.4-9.8

Thermoplastic polymer - 0.2-1.6

The use of solid phthalonitrile resins, bifunctional benzoxazines and solid thermosetting epoxy resins, pre-fused with thermoplastic polymers, as the base of the claimed binder ensures that the claimed binder remains in solid form at room temperature and that high-strength and heat-resistant polymers are obtained after the curing reaction.

In products such as carbon fiber reinforced plastics (CFRP), different requirements are often placed on the surface and core layers. Powder coating technology for binder application allows for precise and smooth control of compositional changes, creating a gradient distribution of components across the part's thickness. The binder composition gradient is created by varying the ratio of solid phthalonitrile resin to bifunctional benzoxazine (within the stated ratios) across the part's thickness. The stated binder compositions are prepared so that the carbon fiber surface contains the maximum amount of solid phthalonitrile resin and the minimum amount of bifunctional benzoxazine, by mixing them in the appropriate proportions. Conversely, the core layers contain a maximum amount of bifunctional benzoxazine and a minimum amount of solid phthalonitrile resin. The surface layer of gradient carbon fiber reinforced plastic contains 80% by weight of solid phthalonitrile resin, while the core layers contain 10% by weight of solid phthalonitrile resin. The content of bifunctional benzoxazine, on the other hand, increases from the surface to the inner layers. As one moves from the outer surfaces of the carbon fiber to the core, the ratio of the components changes smoothly. The high concentration of solid phthalonitrile resin in the surface layers ensures high heat resistance of the carbon fiber.

Carbon fiber-based composite materials exhibit high stiffness but low impact strength. To effectively increase impact strength, it is advisable to ensure the maximum concentration of thermoplastic polymer in the binder in the outer layers of the carbon fiber composite. Since the inner layers must provide maximum material stiffness, they should contain a minimum amount of thermoplastic polymer. In the surface layers of the carbon fiber composite, the content of high-temperature thermoplastic polymer was maximum, amounting to 1.6 wt.%. The two central layers were sprayed with the claimed binder containing 0.2 wt.% thermoplastic polymer. Thus, the gradient distribution of thermoplastic polymer in the carbon fiber composite allowed for an overall reduction in the concentration of thermoplastic polymer in the carbon fiber composite while maintaining a high content of thermoplastic polymer in the surface layers of the carbon fiber composite.

Thus, powder technologies make it possible to easily adjust the composition and, consequently, the properties of the binder by mixing its components in various proportions. The high content of solid phthalonitrile resin in the surface layers of carbon fiber provides high heat resistance. The maximum content of thermoplastic polymer in the surface layers of carbon fiber increases its impact strength while maintaining virtually no reduction in rigidity.

The applicant then provides a description of the claimed modified phthalonitrile-benzoxazine powder binder and the claimed method for producing carbon fiber reinforced plastic using the claimed binder, including with a gradient of binder composition (variants); the applicant then provides a more detailed description of both the composition and the method for producing it, wherein the operations are carried out in three stages.

Stage 1

At the first stage, a powder binder is obtained, for which 10-80 wt. % of solid phthalonitrile resin, 10-80 wt. % of bifunctional benzoxazine and 8.4-9.8 wt. % of solid epoxy resin, preliminarily mixed with 0.2-1.6 wt. % of thermoplastic polymer powder, are taken, they are mixed and ground to obtain a homogeneous powder; the resulting mixture is extruded in a twin-screw mixer at a temperature of 70 ° C - I and II zones, 100 ° C - III zone; the resulting extruded granules are ground to particles no larger than 100 μm.

The finished powder binders are applied to the carbon fabric by electrostatic spraying using a gun, and the product is manufactured using two options for implementing the stated method for producing carbon fiber.

Stage 2

At the 2nd stage, reinforced carbon fiber is produced in four variants:

The first and second options - with a homogeneous composition of the declared binder,

The third and fourth options are with a gradient of the composition of the declared binder.

According to the first variant of the method for producing carbon fiber reinforced plastic, the claimed binder is applied in an electrostatic field on both sides of a carbon fabric fixed on a conductive frame; after spraying, the fabric is heated to a temperature of 100°C, the binder melts and impregnates the fabric due to the low surface tension of the binder melt with an electrostatic charge on the charged surface; the resulting impregnated sheets of fabric (in the required quantity depending on the thickness of the product) are collected in a symmetrical process package, placed in a vacuum bag and consolidation of the process package is carried out, for which a vacuum with a residual pressure of 50 mbar is created in the process package using a vacuum pump, and then the temperature is raised to 120°C; then the process package is cooled, a consolidated plate is obtained, it is removed and used to produce a product by thermoforming between the matrix and the punch of a press mold heated to a temperature of 250°C.

According to the second variant of the method for producing carbon fiber reinforced plastic, the powder binder is applied in an electrostatic field on one side of the carbon fabric laid out on a metal tooling and melted using an IR lamp; then, subsequent layers are laid out and sprayed with powders, melting the binder on each layer; the vacuum bag is assembled and a vacuum with a residual pressure of 50 mbar is created in the process package using a vacuum pump, and then a stepwise increase in temperature to 200 °C is started and held for 1 hour; then the process package is cooled, the carbon fiber is removed and placed in an oven for heat treatment at 250 °C for at least 1 hour.

To produce carbon fiber reinforced plastic (CFRP) with a binder composition gradient, powder binders with varying component ratios (within the stated ratios) are applied layer by layer onto the CFRP. Application is performed using electrostatic spraying with a gun, and the product is manufactured using two different implementations of the stated CFRP production method.

According to the third variant of the method for producing carbon fiber reinforced plastic with a binder composition gradient, powder binders are applied in an electrostatic field on both sides of a carbon fabric fixed on a conductive frame. The composition of the powder binder applied to each fabric is smoothly changed from the fabrics laid out on the surface layers to the central ones such that the binder on the carbon fiber reinforced plastic surface contains the maximum value of solid phthalonitrile resin and the minimum value of bifunctional benzoxazine, and the inner layers contain the maximum value of bifunctional benzoxazine and the minimum value of solid phthalonitrile resin. After spraying, the carbon fabric is heated to a temperature of 100 °C, the powder binders melt and impregnate the carbon fabric due to the low surface tension of the melt of the powder binder with an electrostatic charge on the charged surface; The resulting impregnated carbon fiber sheets with various binder compositions (in the required quantity depending on the thickness of the product) are assembled into a symmetrical process package with a smooth change in the composition of the powder binder from the surface layers to the central ones, placed in a vacuum bag and consolidation of the process package is carried out, for which a vacuum with a residual pressure of 50 mbar is created in the process package using a vacuum pump, and then the temperature is raised to 120 °C; then the process package is cooled, a consolidated plate is obtained, it is removed and used to produce the product by thermoforming between the matrix and the punch of a press mold heated to a temperature of 250 °C.

According to the fourth variant of the method for producing carbon fiber reinforced plastic with a gradient of binder composition, a powder binder of one composition is applied in an electrostatic field on one side of carbon fabric laid out on a metal tooling, and melted using an IR lamp. Then, subsequent layers are laid out and sprayed with powder binders of different compositions with melting of the powder binder on each layer, while the composition of the powder binder is smoothly changed from the surface layers to the central ones so that on the surface of the carbon fiber reinforced plastic the binder contains the maximum value of solid phthalonitrile resin and the minimum value of bifunctional benzoxazine, and the inner layers contain the maximum value of bifunctional benzoxazine and the minimum value of solid phthalonitrile resin; the vacuum bag is assembled and a vacuum with a residual pressure of 50 mbar is created in the process package using a vacuum pump, and then a stepwise increase in temperature to 200 ° C is started and held for 1 hour; then the process package is cooled, the carbon fiber with the binder composition gradient is removed and placed in an oven for heat treatment at 250 °C for at least 1 hour.

Below, the applicant provides examples of the implementation of the claimed technical solution.

Example 1. Obtaining a powder phthalonitrile-benzoxazine binder composition VSN-31 (80 wt.%), BPAA (10 wt.%), DER671 (8.4 wt.%), PESF (1.6 wt.%) and reinforced carbon fiber based on it according to the first variant.

At the first stage, a powder binder is obtained, for which 80 wt. % of solid phthalonitrile resin, 10 wt. % of bifunctional benzoxazine and 8.4 wt. % of solid epoxy resin preliminarily mixed with 1.6 wt. % of thermoplastic polymer powder are taken, they are mixed and ground to obtain a homogeneous powder; the resulting mixture is extruded in a twin-screw mixer at a temperature of 70 ° C - I and II zones, 100 ° C - III zone; the resulting extruded granules are ground to particles no larger than 100 µm.

In the second stage, the prepared powder binder was applied electrostatically on both sides of the carbon fabric, which was attached to a conductive frame, using a gun. After spraying, the fabric was heated to 100°C. The binder melted and permeated the fabric due to the low surface tension of the melted binder, which had an electrostatic charge on its surface. The resulting impregnated fabric sheets were collected in a bag and placed in a vacuum bag. A vacuum pump was used to create a residual pressure of 50 mbar in the process bag, and the temperature was then raised to 120°C. The process bag was then cooled, resulting in a consolidated sheet, which was removed and used to produce the part by thermoforming between the die and punch of a mold heated to 250°C.

The results are shown in Table 1.

Examples 2 - 8. Obtaining powdered phthalonitrile-benzoxazine binder and reinforced carbon fiber based on it according to the first variant.

The sequence of actions according to Example 1 is carried out, differing in that different brands of components and ratios of components are taken.

The results are shown in Table 1.

Example 9. Obtaining a powder phthalonitrile-benzoxazine binder composition FNI350 (80 wt.%), DADFMP (10 wt.%), ED-8 (8.4 wt.%), PEI (1.6 wt.%) and obtaining carbon fiber reinforced plastic based on it according to the second variant.

At the first stage, a powder binder is obtained, for which 80 wt. % of solid phthalonitrile resin, 10 wt. % of bifunctional benzoxazine and 8.4 wt. % of solid epoxy resin preliminarily mixed with 1.6 wt. % of thermoplastic polymer powder are taken, they are mixed and ground to obtain a homogeneous powder; the resulting mixture is extruded in a twin-screw mixer at a temperature of 70 ° C - I and II zones, 100 ° C - III zone; the resulting extruded granules are ground to particles no larger than 100 µm.

In the second stage, the prepared powder binder was applied electrostatically using a gun to one side of the carbon fiber fabric laid out on a metal fixture and melted using an IR lamp. Subsequent layers were then laid out and sprayed, melting the binder. The carbon fiber fabric was cut according to a cutting chart that ensured maximum material utilization. The vacuum bag was assembled, and a vacuum pump was used to create a residual pressure of 50 mbar in the process bag, followed by a stepwise increase in temperature to 200°C. The process bag was then cooled, the carbon fiber composite was removed, and the material was placed in a heat treatment oven at 250°C for at least 1 hour.

The results are shown in Table 1.

Examples 10-16. Production of phthalonitrile-benzoxazine binder powder and carbon fiber reinforced plastic based on it according to the second variant. The sequence of steps in Example 9 is followed, differing in that different grades of components and component ratios are used.

The results are shown in Table 1.

Example 17. Obtaining powdered phthalonitrile-benzoxazine binders and reinforced carbon fiber with a gradient binder composition based on it according to the third variant.

At the first stage, powder binders are obtained, for which 10-80 wt. % of solid phthalonitrile resin, 10-80 wt. % of bifunctional benzoxazine and 8.4-9.8 wt. % of solid epoxy resin preliminarily mixed with 0.2-1.6 wt. % of thermoplastic polymer powder are taken, they are mixed in different ratios and ground to obtain homogeneous powders; the resulting mixtures with different ratios of components are extruded in a twin-screw mixer at a temperature of 70 ° C - I and II zones, 100 ° C - III zone; the resulting extruded granules are ground to particles no larger than 100 μm.

In the second stage, the prepared powder binders with different component ratios were applied in an electrostatic field by spraying with a gun on both sides of the carbon fiber fabric, fixed on a conductive frame. The composition of the powder binder applied to each fabric was gradually changed from the fabrics laid on the surface layers to the central ones, so that the binder on the carbon fiber surface contained the maximum amount of solid phthalonitrile resin and the minimum amount of bifunctional benzoxazine, while the inner layers contained the maximum amount of bifunctional benzoxazine and the minimum amount of solid phthalonitrile resin. After spraying, the fabrics were heated to a temperature of 100 °C, the binders melted and impregnated the fabrics due to the low surface tension of the binder melt with an electrostatic charge on the surface; The resulting impregnated sheets of fabric with different binder compositions are collected in a symmetrical process package with a smooth change in binder composition from the center of the package to the surfaces and placed in a vacuum bag. The process package is consolidated by creating a vacuum with a residual pressure of 50 mbar in the process package using a vacuum pump, and then starting to raise the temperature to 120°C; then the process package is cooled, a consolidated plate is obtained, it is removed and used to produce a product by thermoforming between the matrix and punch of a press mold heated to a temperature of 250°C.

The binder compositions in layers numbered from the surface to the center are given in Table 2.

Example 18. Obtaining a powdered phthalonitrile-benzoxazine binder and reinforced carbon fiber with a gradient of binder composition based on it according to the third variant.

The sequence of actions according to Example 17 is carried out, differing in that other brands of components are taken.

The compositions of the binders in layers numbered from the surface to the center are given in Table 3.

Example 19. Obtaining a powdered phthalonitrile-benzoxazine binder and reinforced carbon fiber with a gradient of binder composition based on it according to the fourth variant.

At the first stage, powder binders are obtained, for which 10-80 wt. % of solid phthalonitrile resin, 10-80 wt. % of bifunctional benzoxazine and 8.4-9.8 wt. % of solid epoxy resin preliminarily mixed with 0.2-1.6 wt. % of thermoplastic polymer powder are taken, they are mixed in different ratios and ground to obtain homogeneous powders; the resulting mixtures with different ratios of components are extruded in a twin-screw mixer at a temperature of 70 ° C - I and II zones, 100 ° C - III zone; the resulting extruded granules are ground to particles no larger than 100 μm.

In the 2nd stage, a powder binder of one composition is applied in an electrostatic field on one side of the carbon fabric laid out on a metal fixture, and melted using an IR lamp. Then, subsequent layers are laid out and sprayed with powder binders of different compositions, melting the powder binder on each layer. In this case, the composition of the powder binder is smoothly changed from the surface layers to the central ones so that on the surface of the carbon fiber, the binder contains the maximum value of solid phthalonitrile resin and the minimum value of bifunctional benzoxazine, and the inner layers contain the maximum value of bifunctional benzoxazine and the minimum value of solid phthalonitrile resin; the vacuum bag is assembled and a vacuum with a residual pressure of 50 mbar is created in the process package using a vacuum pump, and then a stepwise increase in temperature to 200 ° C is started and held for 1 hour; then the process package is cooled, the carbon fiber with the binder composition gradient is removed and placed in an oven for heat treatment at 250 °C for at least 1 hour.

The binder compositions in layers numbered from the surface to the center are given in Table 4.

Example 20. Obtaining a powdered phthalonitrile-benzoxazine binder and reinforced carbon fiber with a gradient of binder composition based on it according to the fourth variant.

The sequence of actions according to Example 19 is carried out, differing in that other brands of components are taken.

The binder compositions in layers numbered from the surface to the center are given in Table 5.

From the data presented in Tables 1-5, it is evident that the compositions of the declared binder were obtained in the entire range of declared values of the component content.

Table 6 shows the properties of the modified phthalonitrile-benzoxazine powder compositions obtained in Examples 1–20 and carbon fiber reinforced plastics based on them, including those with a gradient binder composition.

As can be seen from Table 6, the declared binder and carbon fiber reinforced plastic based on it (Examples 1-20) have:

- high physical and mechanical properties of carbon fiber reinforced plastics: bending strength 344 MPa; bending modulus 38 MPa,

- high impact strength of 120 J/ ^m2 ;

- high heat resistance up to 240°C;

- the impregnation (processing) process is carried out at a temperature not exceeding 100°C without the use of solvents.

Thus, from the above, it can be concluded that the applicant has achieved the claimed technical result, namely, the composition of modified powder phthalonitrile-benzoxazine compositions and the method for producing carbon fiber reinforced plastic, including with a gradient of binder composition, namely:

- high strength properties of the binder due to the selection of a set of components;

- high heat resistance of the declared binder;

- it has been shown that the claimed powder binder has high technological properties;

- simplicity of the method for obtaining the declared binder due to the experimental selection of solid components.

Thus, the claimed technical result was achieved by selecting the optimal composition of the components of the claimed binder and the method for producing carbon fiber reinforced plastic based on it (options), which made it possible to obtain a binder with high technological characteristics, as well as high heat resistance and high physical and mechanical properties of carbon fiber reinforced plastic after curing.

The claimed technical solution meets the patentability requirement of “novelty” required for inventions, since, as of the date of submission of the application materials, the applicant has not identified from the studied prior art sources that possess a set of features identical to the set of features of the claimed technical solution.

The claimed technical solution meets the patentability requirement of “inventive step” required for inventions, since the combination of the claimed features ensures the achievement of technical results that are not obvious to a specialist and that exceed the technical results of analogs.

The claimed technical solution complies with the patentability requirement of “industrial applicability” required for inventions, since the claimed composition can be obtained by using known components with the use of standard equipment and known techniques.

Claims (6)

1. A method for producing carbon fiber reinforced plastic with a gradient composition of a modified powder phthalonitrile-benzoxazine binder, which consists in the fact that at the 1st stage, a modified phthalonitrile-benzoxazine powder binder is obtained, for which 10-80 wt. % of a solid phthalonitrile resin selected from FNI350 or VSN-31, 10-80 wt. % of a bifunctional benzoxazine selected from compounds based on bisphenol A and aniline and based on diaminodiphenylmethane and phenol, and 8.4-9.8 wt. % of a solid epoxy resin selected from D.E.R.671 and ED-8, pre-fused with 0.2-1.6 wt. % of a thermoplastic polymer powder selected from polyetherimide and polyethersulfone are taken, mixed and ground until a homogeneous powder is obtained; the resulting mixture is extruded in a twin-screw mixer at a temperature of 70°C - zones I and II, 100°C - zone III; the resulting extruded granules are crushed to particles no larger than 100 µm; at the 2nd stage, carbon fiber reinforced plastic with a gradient of the composition of the modified powder phthalonitrile-benzoxazine binder is obtained, for which purpose the said binder is applied in an electrostatic field on both sides of the carbon fabric fixed on conductive frames, while the composition of the said binder applied to each fabric is smoothly changed from the fabrics laid out on the surface layers to the central ones in such a way that on the surface of the carbon fiber reinforced plastic the binder contains the maximum value of solid phthalonitrile resin and the minimum value of bifunctional benzoxazine, and the inner layers contain the maximum value of bifunctional benzoxazine and the minimum value of solid phthalonitrile resin; after spraying, the carbon fabric is heated to a temperature of 100 °C, the powder binder melts and impregnates the carbon fabric due to the low surface tension of the melt of the powder binder with an electrostatic charge on the charged surface; The resulting impregnated carbon fiber sheets with different binder compositions are assembled into a symmetrical process package with a smooth change in the composition of the powder binder from the surface layers to the central ones, placed in a vacuum bag, and the process package is consolidated by creating a vacuum with a residual pressure of 50 mbar in the process package using a vacuum pump, and then starting to raise the temperature to 120°C; then the process package is cooled, a consolidated plate is obtained, it is removed and used to produce a product by thermoforming between the matrix and the punch of a press mold heated to a temperature of 250°C. 2. A method for producing carbon fiber reinforced plastic with a gradient composition of a modified powder phthalonitrile-benzoxazine binder, which consists in the fact that at the 1st stage, a modified phthalonitrile-benzoxazine powder binder is obtained, for which 10-80 wt. % of a solid phthalonitrile resin selected from FNI350 or VSN-31, 10-80 wt. % of a bifunctional benzoxazine selected from compounds based on bisphenol A and aniline and based on diaminodiphenylmethane and phenol, and 8.4-9.8 wt. % of a solid epoxy resin selected from D.E.R.671 and ED-8, pre-fused with 0.2-1.6 wt. % of a thermoplastic polymer powder selected from polyetherimide and polyethersulfone, are taken, mixed and ground to obtain a homogeneous powder; the resulting mixture is extruded in a twin-screw mixer at a temperature of 70 ° C - I and II zones, 100 ° C - III zone; the resulting extruded granules are crushed to particles no larger than 100 microns; at the 2nd stage, carbon fiber reinforced plastic with a gradient of the composition of the modified powder phthalonitrile-benzoxazine binder is obtained, for which purpose the modified powder phthalonitrile-benzoxazine binder of one composition is applied in an electrostatic field on one side of the carbon fabric laid out on a metal tooling, melting is carried out using an IR lamp, then subsequent layers of the said binder of different compositions are laid out and sprayed with melting on each layer, wherein the composition of the said binder is smoothly changed from the surface layers to the central ones in such a way that on the surface of the carbon fiber reinforced plastic the said binder contains the maximum value of solid phthalonitrile resin and the minimum value of bifunctional benzoxazine, and the inner layers contain the maximum value of bifunctional benzoxazine and the minimum value of solid phthalonitrile resin; The vacuum bag is assembled and a vacuum with a residual pressure of 50 mbar is created in the process package using a vacuum pump, and then a stepwise increase in temperature is started to 200°C and held for 1 hour; then the process package is cooled, the carbon fiber reinforced plastic with a gradient of the modified powder phthalonitrile-benzoxazine binder composition is removed and placed in an oven for heat treatment at 250°C for at least 1 hour.