RU2135530C1 - Method of preparing reinforced polymeric materials - Google Patents

Abstract

FIELD: chemistry of polymers. SUBSTANCE: method of preparing reinforced polymeric materials based on epoxy binder comprising epoxy-diane resin, hardening system, filler, namely viscous filament, or capron filament, nitrile-acrylonitrile filament, comprises impregnation of filler with resin, heat treatment and impregnation with hardening system. Capron filament treated with magnetic field is used prior to impregnation thereof with hardening system. Protective polymer, namely butadiene- styrene latex or adhesive are added to hardening system (weight ratio of components (water, hardener and protective polymer) in hardening system is 1.7-2.3: 0.5- 1.5:0:7-1.3. Treatment is carried out at 60-80 C. EFFECT: greater breaking stress at static bending and higher specific viscosity of polymeric composite materials and cheaper materials used. 8 dwg, 2 tbl

Description

The invention relates to the field of production of polymer composite materials (PCM) based on cross-linked epoxy polymers reinforced with chemical fibers. The proposed method is recommended to be used to obtain structural materials and products from PCM
A known method for producing fiber-filled PCM (traditional), comprising combining a mixture of epoxy resin and a cold curing hardener, taken in stoichiometric ratios (mixed method), with technical threads followed by molding by direct compression, with the curing of the binder in the form itself. Composite Materials Handbook / Ed. Lubin. R.E. Geller.- M.: Engineering, .- 1988, v.2. -580 s.

 The disadvantage of this method is the limited shelf life of the prepregs containing epoxy resin and hardener.

A known method of producing a reinforced polymer material, including the impregnation of threads by the method of layer deposition of components (SNK) in two stages: first, the thread is impregnated with a 75% solution of resin in acetone, then a curing system of the mass composition of water and hardener 1: 2, cutting of the fibrous filler, followed by direct processing by pressing (120 ^o C, 40 MPa for 15 min) (prototype method) / Patent 2028322 of the Russian Federation, MKI C 08 5/24 Method for producing a prepreg / V.N. Studentsov, B.A. Rosenberg, A.K. Khazizova // BI.-1995.-N4.

 The disadvantages of this method is the low strength characteristics of the resulting material.

 When creating the invention, the task was to obtain materials with improved strength characteristics, cheaper materials.

 This is achieved by the fact that in the proposed method, the filler is impregnated with an epoxy binder by the method of layer-by-layer deposition of components (SNK) in two stages: first, the thread is impregnated with an 80% resin solution in acetone, then with a curing system. To eliminate the disadvantage of the prototype method, a curing system of mass composition is used: water, a protective polymer and a hardener of 1.7-2.3: 0.5-1.5: 0.7-1.3. As an interesting polymer, CMC glue is used. To increase the breaking stress during static bending and specific toughness of the obtained material, magnetic treatment is used.

The proposed method differs from the prototype:
- the impregnation of the threads in the first stage is carried out by 80% solution of resin in acetone;
- the composition of the curing system,
- Inter-heat treatment is used,
- magnetic processing is used.

 The inventive method eliminates the disadvantages of the traditional.

The following threads were used as filler:
- artificial: viscose thread (BH) (TU 6-06-H58-79),
- synthetic: kapron thread (kapron) (TU 15V97-79), polyacrylonitrile thread (nitron) (TU 6-01-15-70-85), impregnated with epoxy resin ED-20 (GOST 10587-84).

 In the curing system, polyethylene polyamine (PEPA) (TU 6-02-594-70) was used as a hardener.

 Butadiene styrene latex (bustilate) (TU 6-15-1090-77) and CMC glue (TU 6-12-1020-75) were used as protective polymers.

 The degree of conversion (X,%) of the oligomeric binder into the net product was determined by the extraction method with acetone.

 To determine the content of the binder components, the linear density (T, g / m) of the threads was controlled at various stages of the process.

The proposed technology is based on the experimental setup scheme, which was used to obtain experimental samples. The prepreg is processed by direct compression. Then, samples of standard sizes are cut from the obtained plates and the following characteristics are determined:
- breaking stress with static bending σ _and (GOST 4648-81);
- specific impact strength a _beats (GOST 4647-80);
- water absorption W (GOST 4650-80);
- density ρ (GOST 15139-69).

Weighing was carried out on an analytical balance with an error of 10 ^-4 g. The linear dimensions of the samples were determined using a caliper with an error of 10 ^-1 mm. The results of parallel tests showed that the maximum absolute errors in determining the values of σ _and , a _beats , ρ, W are respectively ± 2.7 MPa, ± 2.6 kJ / m ² , ± 30 kg / m ³ , ± 0.6% .

 Example 1 (in the traditional way).

The kapron filament is passed through an impregnation bath containing epoxy resin (ED-20) and a cold hardener (PEPA), taken in a mass ratio of 9: 1. The mass ratio of epoxy resin and hardener 9: 1 provides a stoichiometric, quantitative ratio of epoxy groups and active groups of hardener 1: 1. The impregnated thread enters the reel with flat faces (Fig. 1). The obtained prepreg after drying for 24 hours at room temperature is processed by direct compression for 15 minutes at 100 ^o C and a pressure of 8 MPa. Next, samples of standard sizes are cut, which are tested.

 Example 2

Carried out as in example 1, however, a nylon thread is passed through an 80% by weight solution of resin (ED-20) in acetone. From the first impregnation bath, the thread enters a heated pipe (70 ^o C), which is about one minute. Under these conditions, partial evaporation of the solvent occurs. Then the thread is passed through a second impregnation bath, where a curing system of mass composition is applied to the thread: water; hardener and protective polymer 2: 1: 1 (figure 2). Further, as in example 1.

 Data on the properties of PCM obtained using a curing system of various mass ratios of water, hardener and protective polymer are given in table. 1 (note 3-14).

 Example 15

 Carried out as in example 2, however, in the curing system, CMC glue is used as a protective polymer.

 Example 16

 Carried out according to example 15, but as a filler using nitron.

 Example 17

 Carried out according to example 15, however, as a filler using a viscose thread.

 Data on the effect of heat treatment on the properties of PCM are given in table 1 (approx. 18-21).

 Data on the effect of the concentration of the resin solution on the properties of PCM are given in table 1 (approx. 22-25).

 Data on the effect of various fillers on the properties of PCM are given in table. 2 (approx. 26-29).

 Example 30

 Carried out according to example 2, but between the first impregnating bath and the heated pipe, the thread is passed through a cylindrical hole in a permanent magnet (figure 3). A magnetic field with a strength of 320-330 Oe was created in the air gap along the axis of the hole. The main part of the path in a constant magnetic field (PMF) runs in a direction parallel to the magnetic lines of force.

 Example 31

 According to the prototype method.

 Example 32

 In the traditional way.

 Example 33

 According to the prototype method.

 Example 34

 In the traditional way.

 From a comparison of the physicomechanical characteristics of the samples obtained according to examples 1,2, it follows that the increase in water absorption in the samples based on the prepreg obtained by the SNK method compared with the mixed method (traditional) indicates an increase in the heterogeneity of the system (Table 1).

Analyzing examples 3-6, it can be noted that the physicomechanical characteristics of the samples in examples 3-4 are close in value to the errors and are most optimal due to the uniform curing. When the hardener content is higher than the optimum (approx. 5), the toughness decreases due to changes in the crosslinking of the binder. Accordingly, by decreasing the content of hardener suboptimal (approx. 6) decreases _in strength σ nedootverzhdennosti changes and material ductility (X = 94%).

Based on the physicomechanical characteristics of the samples obtained according to Examples 7-10, it can be noted that an increase in the content of the protective polymer in the curing system above the norm leads to a decrease in σ _and (approx. 10).

With a decrease in the water content below the optimum (approx. 13), σ decreases significantly, _and with an increase in the water content in the curing system above the optimum (approx. 14) a _beats sharply decrease.

Based on an analysis of physico-mechanical characteristics of the samples obtained in Examples 15-17, it can be noted that when used as a protective adhesive polymer CMC-H breaking stress σ _and increases by 18%. The increase in specific impact strength slightly exceeds the error in determining this value.

Considering examples 18-21, we can explain the effect of inter-bath heat treatment on the properties of the obtained prepregs. The optimum temperature is the heated pipe in the range of 60-80 ^o C (approx. 2, 18, 20). When the temperature drops below 60 ^o C, an uncured material is obtained, which leads to a significant decrease (approx. 19)
An increase in the temperature of the heated pipe leads to faster removal of the volatile solvent from the impregnated filament. However, the application of a temperature of 90 ^o or higher is ineffective (approx. 21).

 From a comparison of the physicomechanical characteristics of the samples obtained according to Examples 22-25, it follows that the use of resin solutions with a concentration of 70-90% is optimal (approx. 2, 23, 25). An increase in the dilution of the resin with a solvent (approx. 22) leads to a decrease the content of the binder and to reduce the strength characteristics, and the use of more concentrated solutions (approx. 25) causes an excessive increase in the content of the binder in the material and "coarsening" of the material (approx. 25).

From a comparison of the physical and mechanical characteristics of the samples obtained in Examples 26 and 28, it can be concluded that the use of CPC with nitrone leads to an increase in σ _and 35%, a _ud thus reduced by 20% compared with the prior art.

In examples 27, 29, the breaking stress under static bending σ _and increases by 19%, and the specific impact strength drops by 30% when using viscose yarn.

 Therefore, the improvement of all strength characteristics occurs when capron is used as a filler (Table 2).

The use of magnetic processing of freshly impregnated yarn (example 30, Fig. 3) will increase the tensile stress at static bending σ _and 20%, and the specific impact strength by 10% compared to samples obtained by the SNK method without the use of magnetic processing (table. 2) .

 The specific impact strength by the method - analogue is increased by 58%, and the breaking stress during static bending increased by 18%.

The proposed method provides a significantly higher increase in breaking stress during static bending σ _and by 61% than when using an analog. When using kapron, the inventive method and analogue provide approximately the same increase in specific impact strength (table. 2). When using a nitrone and an increase of viscose yarn σ _and a 61% reduction and a 30% _beats as compared to the prototype. Even if a _{beats is} decreased by 30%, the absolute value of a _beats (102 kJ / m ² remains much higher than by the method - analogue (49 kJ / m ² ).

 In general, the inventive method provides higher strength characteristics than the prototype. According to the claimed method, a more economical, in comparison with the prototype, curing system with a reduced content of a relatively expensive hardener is used.

Claims (2)

1. A method of obtaining a reinforced polymeric material based on an epoxy binder containing an epoxy Dianova resin and a curing system consisting of water, polyethylene polyamine and bustilate, including pre-impregnation of a capron filament with an epoxy resin, heat treatment and subsequent impregnation with a curing system, characterized in that they use a curing system consisting of water, polyethylene polyamine, bustilate or carboxymethyl cellulose with a mass ratio of components in the curing system of 1.7-2.3: 0.5-1 5: 0.7-1.3, and the heat treatment is carried out at 60 - 80 ^o C.  2. The method according to claim 1, characterized in that the capron thread impregnated with epoxy resin is further treated with a magnetic field before being impregnated with a curing system.

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