RU2804285C1 - Composite protective material - Google Patents

Abstract

FIELD: polymers.

SUBSTANCE: composite protective material refers to polymeric materials based on siloxane rubber and can serve to protect products from ionizing, electromagnetic and radio emission. The composite protective material contains a polymer, a filler is a finely dispersed graphite powder of a uniform shape with a particle size of 0.004 mm to 0.05 mm, and a hardener is a cold curing catalyst K-68, in the following ratio, wt.%: Stirosil polymer brand A - 67.2; fine graphite powder - 30.8; cold curing catalyst K-68 - 2.0; total content of components without diluent - 100; Toluene thinner for 100 wt.% components - 67 wt.%.

EFFECT: creating a protective material having an increased attenuation coefficient.

1 cl, 3 dwg, 2 tbl

Description

The invention relates to polymer materials based on silicone rubber and can be used to protect aircraft, rocketry, mechanical engineering and other equipment from ionizing, electromagnetic and radio radiation, and can also be used to protect electronic components and devices from radiation from the Earth’s natural radiation belts, radiation Sun and outer space.

When creating means of protecting a spacecraft from radiation from the natural radiation belts of the Earth, radiation from the Sun and outer space, it is necessary to take into account that such radiation leads to irreversible changes in the structure, as well as the physical and chemical properties of protective materials.

From the existing level of technology, a protective material for electronic devices from the effects of radiation from the space environment is known (RU 2619455, class G21F 1/12, published on May 16, 2017 “Composition for protecting electronic devices from the effects of radiation from the space environment”). This composition is made in the form of layers, each of which is a matrix of radiation-resistant polymer material with filler. The filler contains one or more chemical elements or their compounds. Boron compounds were used as a matrix filler facing the source of primary radiation. The fillers of each subsequent layer are selected from the condition of increasing the effective atomic number of the chemical element of the filler substance. The β-radiation attenuation coefficient of each layer is 0.2÷0.6.

The disadvantages of this material are the impossibility of its use in large-sized structures in the form of shells, on surfaces of variable curvature, on spherical and conical surfaces, on units of complex geometric shapes, as well as the low attenuation coefficient of β-radiation of the material.

The closest to the stated technical solution adopted as a prototype is a heat-insulating polymer material (RU 2558103, class C09D 183/04, published 07.27.2015), which contains:

- polymer matrix - siloxane block copolymer Lestosil-SM of the general formula: HO{[C ₆ H ₅ SiO1.5]n[Si(CH ₃ )2O]m}H, where n=30÷60, m=80÷130 , dissolved in butyl acetate in a ratio of 100:70;

- inorganic filler - glass microspheres;

- crosslinking agent 119-54 grade A;

- fire retardant nanosilicate montmorillonite mixed with butyl acetate in a ratio of 0.6:30.

The method of manufacturing this material involves mixing a siloxane block copolymer dissolved in butyl acetate with a filler, a fire retardant dissolved in butyl acetate, and a cross-linking agent, curing and thermal stabilization. The siloxane block copolymer Lestosil-SM of the general formula is used as a polymer matrix: HO{[C ₆ H ₅ SiO1.5]n[Si(CH ₃ )2O]m}H, where n=30÷60, m=80÷ 130. When mixing components, ultrasonic treatment is used at a frequency of 40-50 kHz and an effective power of 250-360 W. When preparing the elastomeric matrix, Lestosil-SM block copolymer granules are dissolved in butyl acetate in a ratio of 100:70 for 3 hours with periodic stirring after 2-3 minutes for 1 minute. Next, the prepared material is pneumatically sprayed in several layers onto the metal surface. The number of layers depends on the required coating thickness. In one operation, a layer approximately 1 mm thick is applied. The gap between operations is from 30 to 60 minutes. After applying the coating, it is dried at room temperature for 48 hours and thermostabilized at a temperature of 120°C for 1 hour in a thermostat.

The advantages of this polymer material include high thermal insulation properties and a high attenuation coefficient of β-radiation.

The disadvantage of this protective material is that it has a low density, as a result of which its strength characteristics decrease. This is due to the fact that it contains a large number of microglass spheres (up to 40-50 parts by weight). In addition, the protective material has a low γ-particle attenuation coefficient.

The objective of the invention is to create a protective material with an increased attenuation coefficient and reduced weight and size characteristics, as well as the possibility of use in products of complex spatial and geometric shapes.

The problem is solved by the fact that in a composite protective material containing a polymer, filler and hardener, according to the invention, low-molecular polymer "Stirosil" grade A is used as the polymer, the filler is finely dispersed graphite powder of a uniform shape with particle sizes from 0.004 mm to 0.05 mm, and the hardener - cold curing catalyst K-68 TU 38.303-04-05-90 with the following ratio of components, parts by weight. %:

Polymer "Stirosil" grade A 67.2 Fine graphite powder of uniform shape 30.8 Cold curing catalyst K-68 2.0 Total content of components Without thinner 100 Thinner Toluene GOST 14710-78 per 100 parts by weight % of components - 67 parts by weight. %

The use of low molecular weight polymer "Stirosil" grade A TU38.103.453-99 as a binder ensures high heat resistance of the protective material.

The use of finely dispersed graphite powder of uniform shape with a particle size from 0.004 mm to 0.05 mm, obtained by electrolysis from graphite grade MPG-6, ensures high strength and rigidity in the protective material, the possibility of reducing the thickness and number of applied layers due to a higher particle density graphite powder. Such graphite powder has particles of an almost regular cubic shape without damage to the crystal lattice, as a result, the surface of the applied layers of protective material becomes more even.

The use of cold-curing catalyst K-68 TU 38.303-04-05-90 in the proposed protective material determines the process of curing (polymerization) of the material at room temperature and leads to an increase in the elasticity of the protective material.

The purpose of the solvent Toluene GOST 14710-78 is to give the polymer composition the consistency and shape necessary for application.

An increase or decrease in the amount of introduced catalyst - hardener K-68 per 100 grams of components leads to the production of low-quality material and does not provide the specified thermophysical and absorption characteristics.

The invention is illustrated with photographs.

In fig. Figure 1 shows a snapshot of the microstructure of a graphite particle of uniform shape with particle sizes from 0.004 mm to 0.05 mm.

In fig. Figure 2 shows the process of removing the composite protective material from the substrate.

In fig. Figure 3 shows a finished sheet of the inventive composite protective material.

The invention is implemented as follows.

To obtain the protective material, the components are fed into a paddle mixer in the following sequence: first, Stirosil grade A polymer is loaded, then finely dispersed graphite powder of a uniform shape, having particle sizes from 0.004 mm to 0.05 mm, is added and mixed until a homogeneous composition is obtained. Next, a solvent, Toluene, and a hardener, cold curing catalyst K-68, are added to this mass with continuous stirring.

Particles of graphite powder obtained by mechanical grinding have different shapes - from balls to plates with sharp edges and external damage, and there is also damage to the crystal lattice (chips, cracks, cracks). The use of mechanically crushed powder as a filler is unacceptable. Particles of graphite powder obtained by electrolysis from MPG-6 graphite have a homogeneous shape (see patent RU 2771846).

The mixed components of the protective material are applied to a substrate, which is used as sheets of dense aluminum foil for technical purposes GOST 618-2014 with a thickness of at least 0.08 mm, or fluoroplastic sheets with a thickness of at least 1 mm, manufactured in accordance with TU 6-05-810-88 . Before applying the mixed components to the surface of the substrate, it is covered with a layer of primer AK-070 GOST 25718-83 and dried according to the instructions for use. Applying a primer helps to obtain a uniform and even layer of protective material. The protective material is applied to the primed surface of the substrate by pneumatic spraying, brush, or layer-by-layer dipping to obtain a monolayer thickness of 0.4÷0.6 mm. The number of layers is set based on the material thickness specified in the design documentation, technical specifications or technical specifications. We applied 6 layers with a total thickness of 2.5 mm.

After applying each layer, exposure is carried out at a temperature of 20 to 30 ° C for 10-15 minutes. After applying the required number of layers, the final exposure is carried out at a temperature of 50°C for 25-26 hours.

Then the applied protective material is mechanically removed from the substrate.

The advantage of this protective material is the possibility of obtaining the material in the form of sheets of various shapes, glued to the surface of the protected product, depending on the design features and operating conditions. Elad K-19-3 or K-24-30 glue TU 2513-006-17742007-2004 can be used as a binder for the claimed polymer protective material when connecting it to the metal surfaces of the product. To attach protective material to the surfaces of a product made of various organic materials (plastic, resin, organotextolite, etc.), glue 88-SA TU 075 06004-122-98 can be used.

Experimental work carried out when testing protective material compositions with component ratios that go beyond the ratios limited by the present invention, both downward and upward, showed that their functional and physicochemical characteristics deteriorate.

Table 1 presents the physical and mechanical characteristics of the proposed protective material.

An important characteristic of a protective material is its mass. As can be seen from Table 1, the proposed material has a high density value, necessary for the implementation of high-quality functional characteristics, and low thickness, therefore this material has a better mass thickness value in comparison with the prototype (0.302 g/cm ² ).

Table 2 presents comparative indicators characterizing the protective properties of the proposed material and the prototype.

The main absorption properties were determined using an absorption method based on attenuation of the intensity of a quantum beam using filters placed between the source and the quantum detector. Material samples were exposed to a flux of Co ⁶⁰ gamma quanta with decay energy E = 1.333 MeV. The gamma quanta detector is a RadiaCode - 101 dosimeter with a spectrometer function. The samples were also exposed to a source of beta radiation (St ⁹⁰ -Y ⁹⁰ isotope) with decay energy E = 0.546 MeV.

The inventive protective material has the necessary radiation-protective and absorbing properties to protect various equipment from electromagnetic, radiation and ion radiation, as well as to protect the electronic component base of a spacecraft. This will eliminate breakdowns and failures of radio-electronic equipment due to the high values of the attenuation coefficients of β-radiation - 0.41, γ-radiation - 0.92 and small values of the particle accumulation factor β - 5.84, γ - 1.62.

The protective material has a density of 1.05÷1.17 g/cm ³ , which makes it possible to reduce weight due to its small thickness while ensuring the operational properties of the protective material.

Protective material can be placed on surfaces of complex spatial and geometric shapes using special adhesive compounds.

The proposed method is simpler, since it does not require the use of complex and expensive equipment.

Claims (2)

A composite protective material comprising a polymer, a filler and a hardener, characterized in that the polymer is a low-molecular polymer "Stirosil" grade A, the filler is finely dispersed graphite powder of a uniform shape with particle sizes from 0.004 mm to 0.05 mm, and the hardener is a cold-curing catalyst K-68, with the following ratio of components, parts by weight. %: Polymer "Stirosil" grade A 67.2 Fine graphite powder 30.8 Cold curing catalyst K-68 2.0 Total content of components Without thinner 100 Thinner Toluene per 100 parts by weight % of components - 67 parts by weight. %