RU2473576C1 - Epoxy binder for composite materials - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to epoxy binder for articles made from composite materials produced primarily by wet (thread, bundle) winding. The epoxy binder for composite materials contains triglycidyl derivative of para-aminophenol, a diluent - epoxy-aniline resin, a technical mixture of polysulphides based on o-tertbutyl phenol, an amine curing agent - mixture of 2- and 4-aminobenzyl anilines, 4,4'-diaminodipheny methane and higher polyaminobenzyl anilines.

EFFECT: high strength of unidirectional organoplastics at temperature of 150-200°C.

2 tbl, 7 ex

Description

The invention relates to epoxy binders for products from composite materials, manufactured mainly by the method of "wet" (filament, tow) winding.

Known epoxy binder (author certificate. No. 1346646), including a mixture of epoxy-diane and epoxyaniline resins, a modifier is low molecular weight rubber SKN-30 KTPA, a hardener is isomethyl tetrahydrophthalic anhydride and a curing accelerator is 2,4,6-trisomethylphenol.

The binder has a low viscosity, the temperature of its processing by "wet" winding is 25-35 ° C. The main disadvantage of this binder is the low deformation heat resistance of the epoxy polymer (glass transition temperature of only 50-60 ° C) and, therefore, the low level of strength retention of composite materials at a temperature of 150 ° C and above.

Known epoxy binder based on epoxy-diane oligomer ED-20 (100 parts by weight) and amine hardener of catalytic type - complex BF ₃ · monoethanolamine - 3.0 parts by weight (see N.V. Aleksandrov, R.S. Kholodovskaya, L.S. Zabarskaya "Electrical insulating impregnating compositions based on epoxy resins used by foreign companies". Informelektro, M., 1970, p. 38).

This composition has a low viscosity and long viability during storage and processing by "wet" winding.

The epoxy polymer (in the form of cast unfilled samples) has rather high physical and mechanical characteristics at 20 ° C.

The disadvantage of this epoxypolymer is insufficient deformation heat resistance.

We selected this epoxy binder as an analogue.

The closest technical solution, selected as a prototype, in terms of the combination of the main essential features and the achieved technical result is an epoxy binder for composite materials according to patent RU No. 2395536 C2, 2010.

The disadvantages of the epoxy binder included in the composite material (prototype) are: toxicity of the hardener UP-0638, consisting of a mixture of metaphenylenediamine and 4,4 ¹ -diaminodiphenylmethane, limited viability during processing by wet winding and insufficient level of preservation of the strength of unidirectional organoplastics at 150 -200 ° C.

The patent contains only two indicators characterizing the initial (at 20 ° C) strength of unidirectional organoplastics based on Armos tow (strength and tensile modulus).

It is known that the initial level of strength characteristics of unidirectional organoplastics depends mainly on the breaking load of the bundle used for the manufacture of samples and the breaking stress of the bundle under tension in microplastics (based on the selected binder). Given that there are no such data in the patent, for comparative analysis, samples of unidirectional organoplastics (in the form of rings ⌀ 146 mm) were made by “wet” winding on the claimed binder, analog, prototype and aramid rope Rusar-S (TU 2272-006-18059169-2007 ) with a linear density of 600 tex, grade A.

The main objective of the invention is the creation of an epoxy binder for composite materials manufactured by "wet" winding, with high heat resistance characteristics.

The technical result from the use of the invention is to increase the level of preservation of the strength of unidirectional organoplastics at 150-200 ° C.

The main task is solved and the technical result is achieved by introducing new ingredients indicating a new quantitative and qualitative ratio of components.

For this purpose, an technical mixture of polysulfides based on o-tert-butylphenol is added to the epoxy binder for composite materials containing a triglycidyl derivative of para-aminophenol, a diluent and an amine hardener, an epoxy aniline resin is used as a diluent, and a mixture of 2- and 4 is used as an amine hardener -amino-benzylanilines, 4,4 ¹ -diaminodiphenylmethane and higher polyaminobenzylanilines, in the following ratio of the components of the binder, mass.h:

Triglycidyl Derivative para-aminophenol 70-90 Epoxy aniline resin 10-30 Technical mixture of polysulfides based on o-tert-butylphenol 1-5 A mixture of 2- and 4-aminobenzylanilines, 4.4 ¹ -diaminodiphenylmethane and higher polyaminobenzylanilines 35-45

The distinctive features of the proposed epoxy binder for composite materials are the following features:

- the introduction of an epoxy binder modifier - a technical mixture of polysulfides based on o-tert-butylphenol;

- use as a diluent epoxy aniline resin;

- the content as a hardener of an aromatic amine, which is a mixture of 2- and 4-aminobenzylanilines, 4,4 ^1- diaminodiphenylmethane and higher polyaminobenzylanilines;

- the ratio of all components of the epoxy binder in the specified mass parts with limit values.

These distinguishing features of an epoxy binder are significant, since each of them is separately and jointly aimed at solving the problem and achieving a new technical result.

Triglycidyl derivative of n-aminophenol - resin - UP-610 (TU 2225-546-00203521-98 or TU 2225-606-11131395-2003) or EAF resin (TU 6-22-04872688-367-95) - manufacturer of NIIKHIMPOLIMER OJSC "

Characteristics of these resins: mass fraction of epoxy groups,%, not less than 33, dynamic viscosity at 40 ° С, Pa · s, not more than 2.5.

Compared with other polyfunctional epoxy resins, for example, ECD, ETF and UP-643, this resin has the lowest viscosity at 25 ° C, which makes it more preferable for use in epoxy compositions intended for processing by "wet" winding.

Epoxyaniline resin (EA) - TU 2225-606-11131395-2003 with a mass fraction of epoxy groups of at least 31.2% and a dynamic viscosity at 25 ° C of not more than 0.35 Pa · s.

When used in the inventive binder as a diluent, the necessary viscosity is provided at the processing temperature, and most importantly, the high heat resistance of the epoxy polymer and organoplastics.

Technical mixture of polysulfides based on o-tert-butylphenol (TAB) of the general formula

where n = 1 ÷ 4.

The average molecular weight is 362. Mass fraction of sulfides of o-tert-butylphenol, not less than 90%.

Developed by the NIOKh SB RAS, produced by domestic industry.

In the inventive composition, it plays the role of a modifier that allows you to create a more ordered and less defective structure of the epoxy polymer and organoplastics, which, in turn, provides high physical and mechanical characteristics both in the initial state and at elevated temperatures.

Hardener is a mixture of 2- and 4-aminobenzylanilines, 4,4 ^1- diaminodiphenylmethane and higher polyaminobenzylanilines (Benzam ABA) - TU 2225-415-04872688-99.

A viscous resinous product with a mass fraction of diamines of not less than 65%, and 4,4 ¹ -diaminodiphenylmethane - not more than 10%.

In the composition of the inventive binder, this hardener allows you to provide at the processing temperature (60 ± 5) ° C the required viscosity, and most importantly - the necessary viability.

The initial dynamic viscosity of the binders at (60 ± 1) ° C and after 3 hours (at the same temperature) was determined on a Reotest instrument.

The glass transition temperature was estimated by the dynamic mechanical method (torsion pendulum on the device) by changing the stiffness of unidirectional microplastics (organoplastics) during heating from room temperature to 200 ° C at a constant speed of 1 ° C / min.

G _rel = T ₀ : T ₁ (rel. Units),

where T ₀ is the oscillation period, that is, the time of unwinding of the disk, rigidly fixed to the lower end of the microplastic, at room temperature, s;

T _t - period of oscillations at a temperature of t ° C, s.

Microplastics were made by impregnating the Armos (Rusar) ~ 58 tex yarns with various binder formulations followed by their curing according to the optimal (for each binder) mode given below.

Binders were prepared in containers with vigorous stirring using mechanical devices (mixers), binders (examples 1-5, 7) are shown in table 1.

Table 1 Name of components The number of) components, parts by weight The inventive recipe Prototype one 2 3 four 5 7 Triglycidyl derivative of para-aminophenol (resins UP-610, EAF) 70 80 90 60 95 85 Aliphatic epoxy resin DEG-1 - - - - - fifteen Epoxyaniline Resin (EA) thirty twenty 10 40 5 - Technical mixture of o-tert-butylphenol polysulfides (TAB) one 3 5 0.5 6 - A mixture of 2- and 4-aminobenzylanilines, 4,4 ¹ -diaminodiphenylmethane and higher polyaminobenzylanilines (Benzam-ABA) 35 40 45 thirty fifty - A mixture of aromatic amines -4,4 ¹ -diaminodiphenylmethane and metaphenylenediamine (UP-0638) - - - - - 25

The composition of the binder (example 6 is an analogue), parts by weight:

Epoxy Dianne Resin ED-20 (GOST 10587-84) one hundred Hardener complex BF ₃ with benzylamine (UP-605/3) 3

Hardener UP-605/3 (TU 2494-664-111331395-2010) is a white or light-colored crystalline powder with a melting range of 110-139 ° C.

For the convenience of preparing and processing the binder, 50% of the hardener melt in diethylene glycol was used.

The technological properties of the claimed binder, analogue and prototype, thermophysical properties of epoxy polymers (microplastics) and physico-mechanical properties of unidirectional organoplastics (at 20 and 150 ° C) are shown in table 2.

table 2 No. type INDICATORS Examples of formulations of binders and organoplastics based on them declared famous one 2 3 four 5 6-analog 7 prototype one Initial dynamic viscosity at 60 ° C, cP 450 500 600 400 700 500 700 2 Dynamic viscosity at 60 ° C after 3 hours, cP 5000 6000 7000 4500 9000 500 50,000 3 Heat resistance of epoxy polymer according to Martens (T _m ), ° С 145 155 150 130 140 130 110 four Glass transition temperature (in contact with aramid fiber), ° С 115 125 120 one hundred 110 80 one hundred 5 The ultimate tensile stress of unidirectional organoplastics, kgf / mm ² at 20 ° C 250 260 255 230 240 247 245 at 150 ° C 212 (85%) 234 (90%) 230 (90%) 184 (80%) 197
(82%) 203 (82%) 196 (80%) 6 Tensile modulus, kgf / mm ² at 20 ° C 9500 9550 9600 9300 9400 9800 9450 at 150 ° C 7125 (75%) 7640 (80%) 7680 (80%) 6510 (70%) 6770 (72%) 7840 (80%) 6615 (70%) 7 Breaking stress in bending, kgf / mm ² at 20 ° С 58 62 60 55 fifty 75 fifty at 150 ° C 26 (45%) 31 (50%) 30 (50%) 22 (40%) 17.5 (35%) eleven
(fifteen%) eighteen
(eighteen%)

Table 2 shows the average values of tensile strength, bending and tensile modulus according to the results of tests of unidirectional organoplastics in an amount of at least 5 samples.

In parentheses, the level of preservation of strength and elastic modulus at a temperature of 150 ° C.

Unidirectional organoplastics were made on a winder from Rusar-S tow (with a linear density of 600 tex) and the above-mentioned binders. The temperature of the binders in the impregnation bath for all binder formulations was (60 ± 5) ° C. Winding rings ⌀ 146 mm was carried out with a tension of 4 kgf per tourniquet. With this tension, the greatest realization of the fiber strength in unidirectional organoplastics (microplastics) was ensured.

Breaking stress and tensile modulus of elasticity (in the direction of the fibers) at 20 and 150 ° C were determined on ring samples ⌀ 146 mm, width 10 ± 0.2 mm and thickness 2.3 ± 0.1 mm according to GOST 25.603-82.

The bending breaking stress (in the direction of the fibers) was determined (at 20 and 150 ° C) on the samples in the form of sectors cut from rings 7 mm thick. Sector size: 50 × 10 × 7 mm. The tests were carried out in accordance with OST 92-1472-78.

In examples 1-5, all components are first heated in a heating cabinet to a temperature of 55-65 ° C, and then poured into the container in the quantity and sequence according to table 1 and mixed thoroughly until homogeneous.

The mode of curing cast samples on the formulations (examples 1-5) to determine the Martens heat resistance, microplastics - to determine the glass transition temperature, as well as unidirectional organoplastics (in the form of rings ⌀ 146 mm):

- rise to (100 ± 5) ° C - 1.0-1.5 hours;

- exposure at (100 ± 5) ° C - 2.0-2.5 hours;

- rise to (130 ± 5) ° C - 1.0-1.5 hours;

- exposure at (130 ± 5) ° C - 2.0-2.5 hours;

- rise to (170 ± 5) ° C - 1.0-1.5 hours;

- exposure at (170 ± 5) ° C - 5-6 hours;

- natural cooling to a temperature not exceeding 60 ° C.

In example 7 (prototype), the solid hardener is first melted in a heating cabinet, and then it is poured (at a temperature of ~ 60 ° C) into a mixture of UP-610 and DEG-1 resins heated to this temperature (in the calculated amount according to the recipe).

The curing mode of cast samples, microplastics and unidirectional organoplastics corresponded to that indicated in the patent, that is:

- rise to 85 ° C - free;

- exposure at 85 ° C - 6 hours;

- rise to 100 ° C - free;

- exposure at 100 ° C - 2 hours;

- rise to 140 ° C - free;

- exposure at 140 ° C - 2 hours;

- rise to 160 ° C - free;

- exposure at 160 ° C - 6 hours;

- cooling to room temperature - free.

According to example 6 (analogue), 6 parts by weight are introduced into the ED-20 epoxy resin Diane, heated to ~ 40-50 ° C. 50% melt of hardener UP-605/3 in diethylene glycol (with a temperature of 40-50 ° C) and mix thoroughly until smooth.

Curing mode of cast samples of microplastics and unidirectional rings:

- rise to (100 ± 5) ° C - 0.5-1 hour;

- exposure at (100 ± 5) ° C - 1.5-2 hours;

- rise to (125 ± 5) ° C - 0.5-1 hour;

- exposure at (125 ± 5) ° C - 1.5-2 hours;

- rise to (160-170) ° C - 0.5-1 hour;

- exposure at (160-170) ° C - 5-6 hours;

- cooling to room temperature - free.

The test results shown in table 2 show that the claimed epoxy binder surpasses the known (analog and prototype) in deformation heat resistance (Martens) in the form of solidified cast samples, in glass transition temperature (in the form of a composite material - microplastic) and in the level of preservation of the strength of unidirectional organoplastics at 150 ° C (especially when bending).

For the claimed composition, the level of bending strength is 45-50%, while for the analogue - only 15%, and for the prototype - 36%.

In terms of tensile strength and tensile modulus, both in the initial state (at 20 ° C) and at 150 ° C, the difference is small, since in this type of test the reinforcing filler is loaded, and the role of the matrix is negligible.

As for such types of tests as bending, shear and compression, the physicomechanical properties of the epoxy polymer itself play an important role, and at temperature its deformation heat resistance, evaluated in contact with the reinforcing filler (glass transition temperature).

An important advantage of the claimed epoxy binder in comparison with the prototype is a lower rate of increase in viscosity during processing. For 3 hours of processing, the viscosity of the epoxy binder according to example 7 (prototype) increases to 50,000 cP, while the claimed binder ~ 10 times less.

The optimization of the amounts introduced into the claimed epoxy binder components was carried out on the basis of the following requirements.

- the maximum possible deformation heat resistance (T _m , T _st ) of the epoxy polymer and the level of preservation of the strength of unidirectional organoplastics at temperatures of 150 ° C and above, especially under conditions of bending and shear stresses;

- a high level of initial (at 20 ° C) physical and mechanical properties of unidirectional organoplastics;

- satisfactory technological properties (viscosity, viability) during processing by the method of "wet" (tow) winding.

When the content in the binder of the components in a smaller or larger amount than within the stated limits, it is not possible to fulfill the specified requirements.

Thus, the new technical solution on the totality of the proposed essential features when implemented in an epoxy binder for composite materials and products based on them gives a new positive effect and meets the criterion of "industrial applicability", that is, the level of the invention.

There may be various embodiments of the epoxy binder with respect to the composition and quantitative ratio of the components, if this does not go beyond the scope of the technical solution set forth in the claims.

Claims (1)

An epoxy binder for composite materials containing a triglycidyl derivative of para-aminophenol, a diluent and an amine hardener, characterized in that it additionally contains a technical mixture of polysulfides based on o-tert-butylphenol, an epoxy aniline resin as a diluent and a mixture of 2- as an amine hardener and 4-aminobenzylanilines, 4,4′-diaminodiphenyl methane and higher polyaminobenzylanilines, in the following ratio of the components of the binder, parts by weight:
Triglycidyl Derivative para-aminophenol 70-90 Epoxy aniline resin 10-30 Technical mixture of polysulfides based on o-tert-butylphenol 1-5 A mixture of 2- and 4-aminobenzylanilines, 4,4′-diaminodiphenylmethane and higher polyaminobenzylanilines 35-45