RU2415485C1 - X-ray protective composition - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: proposed composition comprises epoxy binder, hardener represented by polyamine-amide resin with amine number of 280-310 mg KOH/g, and shielding powder filer made up of the mix of cadmium, cerium, gadolinium, ytterbium and bismuth oxide with the following ratio of components in wt % by: epoxy binder - 14.0-17.0; polyamine-amide resin - 10.0-12.0; cadmium oxide - 31.0-32.0; cerium oxide - 31.5-33.0; gadolinium oxide - 5.0-6.0; ytterbium oxide - 0.5-1.0; bismuth oxide - 3.0-4.0.

EFFECT: higher efficiency of shielding in wide range of X-ray quantum energy.

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Description

The present invention relates to the field of composite film-forming materials intended for the creation of thin-layer polymer X-ray protective coatings and can be used in various fields of science and technology where high-performance protection against X-ray radiation is required in combination with high requirements for mass limitation, for example, in rocket and space technology when creating spacecraft.

Currently known material for protection against x-ray radiation, the composition of the shielding filler which is close to the composition of the invention (patent 2066491 with priority 02.25.1994).

However, this material as a matrix contains a mixture of rubbers, i.e. is a rubber. As a coating, rubber can be applied to the surface of the product only through an adhesive sublayer, which is very low-tech and further increases the mass of the coating.

A known X-ray protective composition containing a binder based on an oligourethane prepolymer, a hardener from the group of amino-containing compounds and a screening filler in the form of a mixture of fluorinated oxides of rare-earth elements of the light group and tungsten carbide (patent 2294030 with priority 02.10.2002). However, oligourethane prepolymers cured by amine compounds are intended for the preparation of casting compositions due to their low viability and are therefore also unsuitable for the formation of a thin-layer spray-type coating (see TU 38 103 137-78 "Urethane prepolymer SKU-PFL-100", TU 38 103 519-82 "Urethane prepolymers SKU-PFL 74 and SKU-PFL-74-65"). In addition, the shielding elements of this composition absorb x-rays in the energy range up to 80-90 keV. When exposed to x-rays with a higher quantum energy, this composition is not effective enough.

An X-ray protective composition is also known, consisting of an epoxy binder, a hardener - maleic anhydride and a shielding filler in the form of lead salts (application 95108180 with a priority of 05/19/1995).

The disadvantages of this composition are:

- high toxicity of lead compounds and maleic anhydride;

- relatively low cross-sections for the absorption of x-ray radiation in lead in the energy range of 40-80 keV.

Closest to the present invention in terms of functionality, composition and method of preparation is an X-ray protective composition consisting of an epoxy binder, a hardener from the group of cold cured amine hardeners, a screening filler - a powdery mixture of rare earth oxides, or a mixture of rare earth oxides with antimony oxide ( III), or a mixture of rare earth oxides with tungsten or its compounds, with the following ingredients, wt.%:

binder 13.3-20.8;

shielding filler 78.6-86.3;

amine hardener 0.4-0.6 (application 2003101491 with priority January 20, 2003). This composition was adopted as a prototype.

The disadvantages of the prototype are:

1. The low viability of the composition due to the use of amine hardener, which makes it difficult to use this composition for coating the most technologically advanced and productive spraying method.

2. The non-optimized composition of the shielding filler from the position of protecting the object from x-rays in a wide energy range (from 25 keV to 110 keV).

The maximum X-ray absorption cross-sections of the shielding elements included in this composition are in the energy range 30–90 keV.

In accordance with modern requirements for screen-protective materials, the upper limit of the energy of X-ray quanta is 110 keV. This X-ray protective composition is not designed to shield X-ray radiation with an energy of more than 80-90 keV.

3. Ultra-high filling of the binder with a shielding powdery filler (over 86 wt.%) Leads to a decrease in the impact strength of the cured coating.

4. Ultra-high filling also leads to a decrease in the adhesion of the coating to the surface of the protected object. As a result, it becomes necessary to apply an epoxy binder undercoat, which generally leads to an increase in the weight of the entire coating.

The objective of the invention is to develop an X-ray protective composition that would allow the formation, including by spraying, of a thin-film polymer coating on complex surfaces, which provides effective shielding of protected objects from X-rays in a wide energy range with a small coating weight.

The problem is solved in that for the epoxy binder, a polyaminoamide resin with an amine number of 280-310 mg KOH / g is used as a hardener, and a mixture of cadmium, cerium, gadolinium, ytterbium and bismuth oxides is used as a screening powder filler in the following ratio of components, wt .%:

epoxy binder 14.0-17.0; polyaminoamide resin 10.0-12.0; cadmium oxide 31.0-32.0; cerium oxide 31.5-33.0; gadolinium oxide 5.0-6.0; ytterbium oxide 0.5-1.0; bismuth oxide 3.0-4.0.

The choice of polyaminoamide resin as a hardener is connected with the fact that it provides high viability of the composition, which is a mandatory requirement for a spray type coating. In addition, it is known that coatings based on epoxy resins cured by this hardener have increased impact resistance. This property is also important for an X-ray protective coating experiencing an impact load resulting from a mechanical impulse when exposed to X-ray radiation.

To effectively absorb x-rays with a quantum energy of more than 90 keV, bismuth oxide was introduced into the composition.

In order to optimize the performance of the composition at lower X-ray quantum energies, one rare-earth metal oxide from each group was introduced into its composition: light cerium oxide, gadolinium oxide from medium, and ytterbium oxide from heavy.

To absorb the fluorescent radiation of rare earth elements, cadmium was introduced instead of antimony in the form of its oxide, which has an intense color and acts as a pigment, which gives the coating a chocolate brown color.

The introduction of cadmium oxide in the composition makes it possible to give the X-ray protective coating an additional function of the decorative coating.

To optimize the elemental composition of the composition, a program was developed for calculating, by the gradient method, the maximum absorption coefficient of x-ray radiation for a selected set of heavy elements. The calculated data were subsequently confirmed experimentally.

The quantitative ratio of the binder and the shielding filler was determined based on the maximum possible filling, which still retained the possibility of forming a cured film thin-layer coating with a high-quality glossy surface and good adhesion to the surface of the protected object.

When filling is higher than within the claimed range, a decrease in surface quality is observed: roughness appears, gloss disappears; adhesion to the surface decreases. A lower filling than within the claimed leads to a decrease in the attenuation coefficient of x-ray radiation. Optimal is the filling within the claimed, which clearly demonstrate the test results presented in Table. one.

The adhesion to the aluminum alloy substrate was determined by the method of lattice notches according to GOST 15140 (the lower the score, the higher the adhesion). The attenuation coefficients of x-ray radiation were determined experimentally by irradiation with x-ray quanta with an energy spectrum of 25-70 keV of coating samples 0.5 mm thick.

Table 1 Comparative characteristics of a coating based on an X-ray protective composition with various quantitative filling with shielding agents No. p / p The total content of the shielding filler, wt.% Adhesion to an aluminum alloy substrate, score X-ray attenuation coefficient (average) one Within the claimed limits, 71-76 one 5.42 2 Above claimed limits, 77-80 2 5.85 3 Below declared limits, 65-70 one 4.47

The technological process of preparing the composition consists in mixing the components in a ball mill.

The quality of the milling was determined visually by analyzing samples of the mixture on a glass surface.

During the experiments, the viability of the composition was determined, which amounted to:

- 10 days without hardener;

- 160-180 minutes with a hardener.

Thus prepared composition is ready for application to the surface of the object by brush method. Application of the composition by spraying requires dilution with a polar solvent, such as acetone, to a viscosity determined by the specific brand of spray. For example, for a spray gun brand СО-71А, the viscosity value of the composition should be 20-25 seconds using a VZ-246 viscometer.

In determining the curing regimes, they were guided by the following criteria: the absence of tack and the film reaching sufficient mechanical strength. Thus, the curing mode of the composition was:

- 24 hours at a temperature of 18-35 ° C or

- 2 hours at a temperature of 18-35 ° C, then at least 5 hours at a temperature of 50 ° C.

According to this technology, four variants of the claimed X-ray protective composition were prepared and investigated.

Option 1

1. Binder: epoxy-dianovy resin of the ED-20 brand GOST 10587

17 wt.%.

2. Polyaminoamide resin grade PO-300 TU 2224-092-05034239

12 wt.%.

3. Cadmium oxide GOST 11120

31 wt.%.

4. Cerium oxide TU48-4-523

31.5 wt.%.

5. Gadolinium oxide TU 48-4-524

5 wt.%.

6. Ytterbium oxide TU 48-4-524

0.5 wt.%.

7. Bismuth oxide TU 6-09-02-298

3 wt.%.

Option 2

1. Binder: epoxy-dianovy resin of the ED-22 brand GOST 10587

16 wt.%.

2. Polyaminoamide resin grade PO-300 TU 2224-092-05034239

11.5 wt.%.

3. Cadmium oxide GOST 11120

31.5 wt.%.

4. Cerium oxide TU48-4-523

32 wt.%.

5. Gadolinium oxide TU 48-4-524

5.5 wt.%.

6. Ytterbium oxide TU 48-4-524

0.5 wt.%.

7. Bismuth oxide TU 6-09-02-298

3 wt.%.

Option 3

1. Binder: epoxy resin grade UP 610

TU2225-606-11131395

15 wt.%.

2. Polyaminoamide resin grade PO-300

TU 2224-092-05034239

11 wt.%.

3. Cadmium oxide GOST 11120

32 wt.%.

4. Cerium oxide TU48-4-523

32.5 wt.%.

5. Gadolinium oxide TU 48-4-524 6 wt.%.

6. Ytterbium oxide TU 48-4-524

0.5 wt.%.

7. Bismuth oxide TU 6-09-02-298

3 wt.%.

Option 4

1. Binder: EA brand epoxy

TU 2225-606-11131395

14 wt.%.

2. Polyaminoamide resin grade PO-300

TU 2224-092-05034239

10 wt.%.

3. Cadmium oxide GOST 11120

32 wt.%.

4. Cerium oxide TU48-4-523

33 wt.%.

5. Gadolinium oxide TU 48-4-524

6 wt.%.

6. Ytterbium oxide TU 48-4-524

1 wt.%.

7. Bismuth oxide TU 6-09-02-298

4 wt.%.

The properties of the coating material formed during curing of the composition with various compositional options are presented in Table 2.

table 2 Characteristics of the coating material formed upon curing of the X-ray protective composition Option No. Density, g / cm ³ Adhesion to an aluminum alloy substrate according to GOST 15140, score Tensile Strength, MPa X-ray attenuation coefficient in the energy range 25-80 keV with a coating 0.5 mm thick X-ray attenuation coefficient in the energy range 25-110 keV with a coating 0.5 mm thick one. 3.00 one 34.0 5.18 3,50 2. 3.00 one 33.8 5.20 3,50 3. 3.00 one 33.5 5.21 3.60 four. 3.00 one 33.0 5.12 3.70 Prototype 3.15 2 25.0 5.21 2.27

As can be seen from Table. 2, a coating based on the claimed composition at a lower density and the same shielding ability in the range of x-ray energies of up to 80 keV in comparison with the prototype has increased adhesion to the surface of an aluminum alloy object, higher strength and shielding ability of x-rays with a quantum energy of up to 110 keV .

Claims (1)

An X-ray protective composition containing an epoxy binder, a hardener and a shielding powder filler, characterized in that it contains a polyaminoamide resin with an amine number of 280-310 mg KOH / g as a hardener, and a mixture of cadmium, cerium, gadolinium, ytterbium oxides and bismuth in the following ratio of components, wt.%: epoxy binder 14.0-17.0; polyaminoamide resin 10.0-12.0; cadmium oxide 31.0-32.0; cerium oxide 31.5-33.0; gadolinium oxide 5.0-6.0; ytterbium oxide 0.5-1.0; bismuth oxide 3.0-4.0.