RU2718782C1 - Epoxy binder, prepreg based thereon and article made therefrom - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to production of melt epoxy binders for heat-resistant structural polymer composite materials (PCM), such as prepregs based on fibrous reinforcing fillers, obtained by prepreg technology and used in making high-strength structures, which can be used in aviation, space, helicopter, automobile, machine building and shipbuilding industry, railway transport and other fields of engineering. Epoxy binder contains, wt%: bisphenol F based diglycidyl ether 8.0–2.0; trifunctional epoxy resin based on aminophenols 25.5–33.5; thermoplastic 18.5–25.5; tetraglycidyl diaminodiphenylmethane tetrafunctional epoxy resin 8.0–11.0; aromatic diamine curing agent 25.5–32.0. Obtained prepreg contains said epoxy binder and fibrous filler in ratios (wt%): epoxy binder 30.0–50.0, fibrous filler 50.0–70.0.

EFFECT: technical result of inventions consists in creation of process and long-lived prepregs, formation of cured samples with high resistance to impact destruction and production of articles from PCM, resistant to heat and humidity aging, able to maintain thermomechanical properties at a high level after exposure to negative operational factors (high temperature and moisture).

6 cl, 3 tbl, 9 ex

Description

The invention relates to the field of creating melt epoxy binders for heat-resistant structural polymer composite materials (PCM) based on fiber reinforcing fillers obtained by prepreg technology used in the manufacture of high-strength structures that can be used in aviation, space, helicopter, automobile, machine and shipbuilding industry, railway transport and other areas of technology.

From the prior art it is known mortar epoxy binder for composite materials (see RU 1462773 C1, publ. 07/11/1986) containing a resin based on tetra glycidyl ether 4,4'-diamino-3,3'-dichlorodiphenylmethane brand ECD, hardener aromatic diamine 4 , 4'-diaminodiphenylsulfone and solvent are a mixture of acetone and methyl ethyl ketone. The prepreg obtained by mortar technology, includes 42 mass. % epoxy binder and 58 wt. % carbon tow brand UKN-P / 5000. From the created prepreg, by molding, PCM products are used that are used in mechanical engineering, the aircraft industry, shipbuilding and other areas of technology. The main disadvantage of this invention is the absence of modifiers in the binder composition to increase deformation resistance, impact strength and crack resistance, which does not guarantee long-term and reliable operation of PCM products based on it under the conditions of critical mechanical and shock loads.

Also known in the art other mortar binder based on epoxy resins (see RU 2184128 C2, published on 27.06.2002..) Containing para-aminophenol triglitsidilproizvodnoe brand EAV, poliglitsidilproizvodnoe low molecular weight phenol-formaldehyde novolac mark UP-643 impact modifier - the reaction product of epichlorohydrin with diphenylolpropane Diaplast brand, hardener 4,4'-diaminodiphenylsulfone and solvent - a mixture of isopropyl or ethyl alcohol and acetone. Based on the specified binder (30-42 wt.%) And fibrous reinforcing filler (58-70 wt.%), Prepregs are obtained from which PCM products are used, used in machine-building, shipbuilding, aircraft industry and other technical fields. The main drawback of this binder is the presence of volatile and toxic solvents in its composition, which not only do not allow the regulation of its constant application to the reinforcing filler, which leads to the formation of an inhomogeneous polymer structure of PCM based on it, characterized by a high coefficient of variation of strength characteristics, but also contribute to increased fire hazard of production and significant energy consumption when removing solvents present. The known binder is processed using mortar prepreg technology, which does not comply with the principles of Green Chemistry, which leads to atmospheric pollution with toxic substances, increasing the environmental load on the environment.

The closest technical solution for the combination of essential features and the technical result achieved, taken as a prototype, is the technical solution described in the patent, see US 6440257 B1 (working example 3), publ. 08/27/2002. The document discloses a melt epoxy binder, which is a mixture of epoxy resins: 23 mass. % epoxy resin based on triglycidyl para-aminophenol and 25 wt. % epoxy resin based on bisphenol F. The composition also contains thermoplastics: 7 wt. % polyetherimide and 26 wt.% compacted polyethersulfone. As a hardener, 19 masses are used. % aromatic diamine - 3,3'-diaminodiphenylsulfone (3.3 DDS). Also known from the prototype is a prepreg made by applying a rolled film containing 69 g / m ^{2 of the} specified epoxy binder onto a carbon cloth based on 3K PW fiber (manufacturer Amoco) with a surface weight of 193 g / m ² (component: binder ratio - 35 wt.%, carbon fiber filler - 65 wt.%).

The disadvantages of these prototype materials are:

- reduced technological viability of the epoxy binder and prepregs based on it at a temperature of 25 ° C (a quick set of viscosity of the binder and a significant decrease in its reactivity in the prepreg during storage);

- insufficiently high resistance to mechanical stress and shock loads, namely a low rate of crack resistance and fracture toughness of the cured binder;

- a significant decrease in thermomechanical characteristics, in particular, the glass transition temperature of the formed PCM samples from a prepreg based on a binder after prolonged exposure to negative operational factors such as elevated temperature and moisture.

The increased reactivity of 3,3'-diaminodiphenylsulfone contributes to the accelerated activation of the curing process of the prototype binder even at room temperature, which leads to a rapid increase in the viscosity of the composition, a decrease in the residual reactivity and an increase in the degree of curing. All this leads to a decrease in the viability of the prototype binder and the prepreg based on it during storage at a temperature of 25 ° C, which significantly impairs the technological properties of the prepreg: drapability is reduced, elasticity and flexibility are reduced, the necessary contact tack is absent, etc. This complicates the process assembly process. a prepreg package, which is especially problematic in the manufacture of parts of complex configuration and double curvature.

The technical problem that the group of inventions aims to solve is to create an epoxy binder and a prepreg based on it with increased technological viability at a temperature of 25 ° C and PCM products based on them with increased resistance to mechanical stress and shock loads, as well as resistant to long-term exposure to adverse operating factors such as elevated temperature and humidity.

The technical result achieved by solving the technical problem is to increase the chemical stability of the epoxy binder and the duration of maintaining the increased reactivity of the binder at a temperature of 25 ° C, which leads to the long-term preservation of such technological properties of the prepreg as good drape, high elasticity and flexibility, optimal contact tack etc., which simplifies the technological process of its processing in PCM, and the optimized composition of the epoxy binder leads increase the impact resistance of the FRP products on its basis and enhance their stability thermomechanical properties such as glass transition temperature, heat and humidity to external influences.

The technical problem is solved, and the technical result is achieved due to the fact that the epoxy binder for creating heat-resistant structural polymer materials includes a mixture of diglycidyl ether based on bisphenol F, a trifunctional epoxy resin based on aminophenols, a thermoplastic and hardener - aromatic diamine, characterized in that a trifunctional aminophenol-based epoxy resin is triglycidyl derivatives based on para-aminophenol or meta-aminophenol or a mixture thereof, in quality The thermoplastic used is a thermoplastic selected from the series: polyarylsulfone, polyethersulfone, phenoxy resin or a mixture thereof; hardener uses an aromatic diamine, which is 4, 4'-methylene-bis- (3-chloro, 2,6-diethylaniline) or 4 , 4'-diaminodiphenylsulfone or a mixture thereof, and also includes a tetrafunctional epoxy resin based on tetraglycidyl diaminodiphenylmethane, in the following ratio, wt. % .:

bisphenol-based diglycidyl ether F 8.0-12.0 aminophenol-based trifunctional epoxy 25.5-33.5 thermoplastic 18.5-25.5 tetrafuctional epoxy based tetraglycidyldiaminodiphenylmethane 8.0-11.0 hardener aromatic diamine 25.5-32.0

To achieve a technical result, a prepreg is also proposed, including the claimed epoxy binder and fibrous reinforcing filler in the following ratio, mass. %:

epoxy binder 30.0-50.0 fiberfill 50.0-70.0

As the fibrous reinforcing filler, fibrous glass or carbon fillers can be used.

The product is made by autoclave molding of a prepreg from the claimed binder.

The proposed epoxy binder and prepregs based on it are characterized by increased technological viability, as well as form cured samples with increased resistance to destruction and PCM products resistant to prolonged exposure to adverse operational factors - heat and moisture aging, capable of maintaining thermomechanical properties at a high level after exposure to negative operational factors such as fever and moisture.

To create an epoxy binder:

- epoxy resins of Araldite GY281 (manufactured by Huntsman Advanced Materials), YDF-170 or YDF-175 (manufactured by KUKDO Chemical Co., Ltd) and others; can be used as diglycidyl ether based on bisphenol F (diphenylolmethane);

- as an epoxy resin based on aminophenols, triglycidyl derivatives of para-aminophenol of the EAF grade (manufacturer of NIIKhimpolymer OJSC), UP-610 brand (manufacturer of Himex Limited CJSC), Araldite MY0510 brand (manufacturer of Huntsman Advanced Materials), Lapox brand can be used ARTF-36 (manufacturer Atul LTD), etc., as well as triglycidyl derivatives of meta-aminophenol brand Lapox ARTF-38 (manufacturer Atul LTD), brand Araldite MY0610 (manufacturer Huntsman Advanced Materials), etc. or mixtures thereof;

- as a thermoplastic, one thermoplastic can be used, selected from the series: polyarylsulfone grade PSFF-30, PSFF-70 (manufactured by JSC Institute of Plastics named after G. Petrov) or another, or polyethersulfone, brands such as PSK-1 (manufacturer of JSC “GS Petrov Institute of Plastics” JSC), PES5003P (manufacturer of Sumitomo Chemical KK) or another, or phenoxy resin brands, PKHB or PKHH (manufacturer by Gabriel Phenoxies Inc), etc. or mixtures thereof;

- as an epoxy resin based on tetraglycidyldiaminodiphenylmethane can be used epoxies of the EMDA brand (manufacturer ZAO Himex Limited), the brand Lapox ARTF-23 (manufacturer Atul LTD), the brand Araldite MY721 (manufacturer Huntsman Advanced Materials), etc .;

- as a diamine aromatic hardener, aromatic diamine 4,4′-methylene-bis- (3-chloro, 2,6-diethyl aniline) of the M-CDEA trademark (manufactured by Lonzacure) or aromatic diamine 4,4'-diaminodiphenyl sulfone can be used trademarks ARADUR 9664-1 or ARADUR 976-1 (manufacturer Huntsman Advanced Materials) and others. or a mixture thereof.

The authors found that the hardener 3,3'-diaminosubstituted sulfone (3,3'-diaminodiphenylsulfone), which is part of the prototype binder, due to the peculiarities of its chemical structure, has increased reactivity compared to the less active hardener used in the present invention 4, 4'-diaminosubstituted sulfone (4,4'-diaminodiphenylsulfone) and the low active hardener of 4,4'-methylene-bis- (3-chloro, 2,6-diethylaniline), due to its sterically hindered molecular structure, or their inactive mixtures.

The use of amino epoxy resins of various functionality and structure in the proposed epoxy binder (triglycidyl derivatives based on para-aminophenol and / or meta-aminophenol, tetraglycidyl derivatives based on diaminodiphenylmethane), in contrast to the prototype binder, the composition of which uses an amine epoxy aminophenol resin only , during curing, leads to the formation of a structural heterogeneous combined polymer network, with increased molecular mobility, reduced inter epnoy stiffness that promotes occurrence of local microplastic flows originated at the mouth of the crack, which increases the resistance to fracture of the cured binder samples, raising the value of fracture toughness and fracture toughness.

To completely crosslink epoxy resin with hardener in polycondensation curing reactions, the ratio of the number of functional groups in hardeners and epoxy groups in resins is theoretically equal to 1: 1. Thus, it is possible to obtain a uniform and completely “crosslinked” structure of a thermosetting polymer when equimolar (stoichiometric) amounts of resin and hardener enter into the reaction during curing. Even a small change in the stoichiometric ratio between the reactive groups in the composition has a significant effect on the physicomechanical and thermomechanical properties, as well as the preservation of these characteristics, under the influence of negative operating conditions of the cured epoxy composition and PCM based on it. The curing of the developed epoxy binder by the polycondensation mechanism, containing resin and hardener in a stoichiometric ratio (ratio of 100 functional groups of resin: 100 functional groups of hardener), in contrast to the prototype binder, which uses a smaller amount of hardener in comparison with stoichiometrically necessary (the ratio of functional groups is 100 resins: 80 hardeners), leads to the formation of a more uniform polymer structure with the involvement of all epoxy in the chemical interaction reactive groups and allows you to achieve a high degree of crosslinking, which contributes to the formation of a polymer binder that is resistant to heat and moisture, providing high heat resistance of moistened PCM and products from it after exposure to negative operational factors for 30 days (elevated temperature T = 70 ° C, humidity ϕ = 85%).

Examples of implementation.

Preparation of the claimed epoxy binder.

Example 1 (table. 1).

Araldite GY281 brand bisphenol F epoxy resin, Araldite MY0510 triglycidyl para-aminophenol derivative epoxy resin, 8.0 wt.%, 23.5 wt.% Epoxy resin was charged into a clean and dry reactor triglycidyl derivative of meta-aminophenol brand Araldite MY0610 and 8.0 mass. % of epoxy resin based on tetraglycidyldiaminodiphenylmethane brand EMDA and with a working stirrer was heated to a temperature of 100 ° C. The mixture was stirred at a speed of 250 rpm at a temperature of 100 ° C for a complete combination of resins. Then the temperature was raised to 150 ° C and the speed of rotation of the stirrer was increased to 300 rpm. In small portions with a working stirrer at a temperature of 150 ° C was introduced 18.5 mass. % thermoplastic polyethersulfone brand PES5003P and mixed until a homogeneous mass. The temperature of the reaction mixture was reduced to 105 ° C, loaded in small portions with a working stirrer 32.0 mass. % hardener of aromatic diamine brand M-CDEA and mixed until a homogeneous mass. The mixer was turned off and the finished hot binder was poured through the drain fitting.

Example 3 (table 1).

In a clean and dry reactor, 9.3 wt.% Epoxy resin based on bisphenol F grade YDF-175, 10.5 wt.% Epoxy resin based on triglycidyl derivative of para-aminophenol grade EAF, 20.0 wt.% Epoxy resin based on triglycidyl derivative of meta-aminophenol brand Araldite MY0610 and 9.0 mass. % of the epoxy resin based on tetraglycidyldiaminodiphenylmethane brand Lapox ARTF-23 and with a working stirrer was heated to a temperature of 100 ° C. The mixture was stirred at a speed of 250 rpm at a temperature of 100 ° C for a complete combination of resins. Then the temperature was raised to 150 ° C and the speed of rotation of the stirrer was increased to 300 rpm. In small portions while the stirrer was operating at a temperature of 150 ° C, 11.0 masses were added. % thermoplastic polyethersulfone brand PSK-1 and 9.7 wt. % thermoplastic phenoxy resin brand PKHH and mixed until a homogeneous mass. The temperature of the reaction mixture was reduced to 105 ° C, loaded in small portions with a working stirrer 26.5 mass. % hardener of aromatic diamine brand M-CDEA and mixed until a homogeneous mass. The temperature of the reaction mixture was reduced to 80 ° C, loaded in small portions with a working stirrer 4.0 mass. % hardener of aromatic diamine with ARADUR 976-1 and mixed until a homogeneous mass. The mixer was turned off and the finished hot binder was poured through the drain fitting.

The manufacturing technology of epoxy binders according to examples 2, 4, 5, 6, 7, 8 (table. 1) was used similarly to examples 1 and 3.

Obtaining the declared prepreg.

Example 1 (table. 2).

Obtaining a prepreg was carried out by applying 30 mass. % epoxy binder, prepared according to the recipe of example 1 (table. 1) through the application device of the impregnation machine at a temperature of 90 ° C on a carbon tow T800-12K in an amount of 70 mass. %

The prepregs for examples 3, 5 and 7 were made using a carbon tow T800-12K, for examples 2, 4, 6 and 8 using glass roving RVMPN 10-400,

The manufacture of the claimed product.

Example 1 (table. 3).

A prepreg based on a binder and carbon tow T800-12K, obtained by melt couting using the formulation of Example 1 (Table 2) was cut into 6.35 mm wide ribbons, which were laid out on an automated lay-up machine with adjustable rolling force (about 1.0 MPa) and temperature (about 100 ° C for a short time). The manufacture of the product was carried out by autoclaving the obtained prepreg at an excess pressure of 0.6 - 0.7 MPa, according to the temperature regime: 2 hours at a temperature of (180 ± 5) ° С, thus, structurally similar samples of the type of the fuselage frame were obtained.

Based on the prepregs made according to examples 3, 4, 5, 6, 7, 8 (Table 2) using a technology similar to example 1, structurally similar product samples were made by autoclaving: example 2 — type of spoiler, example 3 — type of rudder control, for example 4 - type air brake, for example 5 - type stabilizer, for example 6 - type aileron, for example 7 - type spar stabilizer, for example 8 - type panel tail section.

The compositions of the binders according to the invention and the prototype are shown in table 1, the compositions of the prepregs according to the invention and the prototype in table 2, the properties of the binders according to the claimed invention and the prototype, prepregs and PCM samples made on their basis in table 3.

Comparative data from table 3 show that the proposed epoxy binder provides advantages compared with the prototype:

- is more technologically advanced because it is characterized by more stable rheological characteristics and improved retention of reactivity during storage. As a result of its storage for 25 days at a temperature of 25 ° C, there is no large increase in viscosity compared to the initial value (coefficient of viscosity increase of the binder is 1.0 ÷ 1.2), and the prototype binder has a significant increase in viscosity up to 70% (coefficient of viscosity increase of the binder-prototype - 1.7). The cure degree (the degree of conversion of the monomers to polymer), which determines the residual reactivity of the created binder during storage, is also at a fairly low level - 30 ÷ 51%, compared with the prototype binder, in which the cure degree corresponds to - 75%. Such high chemical stability of the claimed epoxy binder at room temperature, the absence of a rapid increase in viscosity and the long-term preservation of increased reactivity, contributes to the long-term preservation of the necessary technological characteristics of the prepreg based on it (good drape, high elasticity and flexibility, optimal contact tack, etc.), which simplifies the technological process of its processing in PCM, and also makes it possible to manufacture prepregs with long life on its basis individuality - at least 25 days at room temperature, unlike the prior art, in which the viability at room temperature is only 15 days. Such technological characteristics of the claimed epoxy binder make it possible to create technological and long-lived prepregs based on it.

- characterized by increased resistance to mechanical stress and shock loads, since cured samples based on it have higher values of crack resistance (K _1c ) and fracture toughness (G _1c ) (K _1c = 1.15 ÷ 1.30 MPa⋅m ^{1 / 2} ; G _1c = 490h515 J / m ² ), which are the criteria for resistance to destruction of the material. The value of crack resistance of the proposed epoxy binder is 13-28% higher than that of the prototype binder, and the fracture toughness index is 9-13% higher than that of the prototype binder. The results obtained confirm that the proposed epoxy binder is capable of forming sufficiently impact resistant materials;

- there is a decrease in thermomechanical characteristics after heat and moisture exposure (T = 70 ° C, ϕ = 85%) for 30 days, both for the material based on the prototype binder and for the material based on the developed composition. However, the thermomechanical characteristics of PCM samples based on the developed polymer composition (Tgwet = 172 ÷ 189 ° C) confirm the possibility of their use for creating products suitable for long-term operation at temperatures up to 150 ° C, while the thermomechanical characteristics of materials based on the prototype composition due to their significant decrease (Tgwet = 146 ° С), they cannot guarantee the successful operation of products in conditions of high humidity at the indicated temperature.

Thus, the claimed epoxy binder and prepregs made on its basis demonstrate improved technological characteristics, which simplifies the process of obtaining products from them, form cured samples with increased resistance to destruction and provide the ability to create PCMs resistant to adverse operating factors - exposure to a humid environment at elevated temperature, capable of maintaining thermomechanical characteristics well after such loads.

table 2

The composition of the prepreg prototype and the claimed invention

Name of components Prototype
US 6440257 The composition according to examples, wt.% 1 2 3 4 5 6 7 8 Binder 35 thirty 33 36 39 42 45 48 fifty Carbon Fabric 3K PW 65 - - - - - - - - Carbon Harness Brand
T800-12K - 70 - 64 - 58 - 52 - Glass roving RVMPN 10-400 - - 67 - 61 - 55 - fifty

Table 3

Properties of the binder of the claimed invention and prototype, prepregs and RMBs made on their basis

Name No. of examples Prototype
US 6440257 1 2 3 4 5 6 7 8 The coefficient of increase in viscosity of the binder after storage at a temperature of 25 ° C for
25 days 1,0 1,2 1,0 1,0 1,0 1,1 1,1 1,2 1.7 The degree of curing of the binder (conversion) during storage at a temperature of 25 ° C for 25 days,% thirty fifty 46 47 42 48 45 51 75 The viability of the binder in the prepreg at a temperature of 25 ° C for at least 24 hours 40 25 thirty thirty 31 35 33 25 fifteen Crack resistance, K _1c , MPa⋅m ^1/2 1.15 1.19 1.18 1.20 1.19 1.24 1.27 1.30 1.01 The fracture toughness, G _1c , J / m ² 490 493 500 499 501 505 509 515 456 Glass transition temperature of dry PCM samples (Tg dry), ° С 193 199 196 197 196 198 197 200 197 The glass transition temperature of wet PCM samples, after exposure in a heat-moist chamber at 70 ° C and 85% humidity for 30 days, Tg wet, ° C 172 185 180 182 183 187 185 189 146

Claims (8)

1. Epoxy binder to create heat-resistant structural polymer materials includes a mixture of diglycidyl ether based on bisphenol F, a trifunctional epoxy resin based on aminophenols, a thermoplastic and an aromatic diamine hardener, characterized in that the trifunctional epoxy resin based on aminophenols includes triglycidyl derivatives based oncouple-aminophenol ormeta-aminophenol or their mixture, as a thermoplastic, a thermoplastic is used, selected from the series: polyarylsulfone, polyethersulfone, phenoxysmol or a mixture thereof, as a hardener, a hardener is used - aromatic diamine, which is 4,4′-methylene bis- (3-chloro, 2,6-diethylaniline) or 4,4'-diaminodiphenylsulfone or a mixture thereof, and also contains a tetrafunctional epoxy resin based on tetraglycidyl diaminodiphenylmethane, in the following ratio, wt.%: bisphenol F diglycidyl ether 8.0 - 12.0 trifunctional epoxy based aminophenols 25.5 - 33.5 thermoplastic 18.5 - 25.5 tetrafuctional epoxy based  tetraglycidyldiaminodiphenylmethane 8.0 - 11.0 hardener - aromatic diamine 25.5 - 32.0 2. A prepreg comprising an epoxy binder and a fibrous reinforcing filler, characterized in that the binder according to claim 1 is used as the epoxy binder. 3. The prepreg according to claim 2, characterized in that it contains components in the following ratio, wt.%: epoxy binder 30.0-50.0 fiberfill 50.0-70.0 4. Prepreg according to any one of paragraphs. 2, 3, characterized in that as a fibrous reinforcing filler contains a fibrous carbon filler. 5. Prepreg according to any one of paragraphs. 2, 3, characterized in that as a fibrous reinforcing filler contains a fibrous glass filler. 6. The product, characterized in that it is made by the method of autoclave molding of the prepreg according to any one of paragraphs. 2-5.