RU2373246C2 - Method of producing heat-resistant material for protective coating - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method of producing heat-resistant material for protective coating involves dissolving a polymeric binder in a solevent, where the binder is in form of poly(o-hydroxyamide), which is a product of polycondensation of dichloride of isophthalic acid with 3,3'-dihydroxy-4,4'-diaminodiphenylmethane in a solvent in molar ratio of reagents ranging from 1:1:7 to 1.05:1:15, and mixing with carbon nanofibres or carbon nanoclusters, obtained through hydrolysis of methane on a Ni/MgO catalyst with length of fibres from 50 to 100 mcm and diametre from 20 to 60 nm until obtaining a homogeneous composition.

EFFECT: obtained finished material is heat-resistant, is highly adhesive and has protective properties when deposited on surfaces of varying chemical nature.

3 cl, 5 ex

Description

The invention relates to a technology for producing materials for applying protective coatings to the surface of various natural and artificial substrates.

A known method of obtaining a material for a protective coating, comprising dissolving a polymeric binder in a solvent and introducing into this solution a carbon filler in the form of nanoparticles [RU 2219212, 12.20.2003].

The resulting material has high adhesive ability and protective properties when applied to metal, polymer, wooden surfaces.

The specified method is the closest in technical, physico-chemical nature and a positive result.

Having certain advantages over analogues (RU 2129106, 04/20/1999; Gul V.E., Shenfil LZ Electrically conductive polymer compositions. - M .: Chemistry, 1984, p.240), this method has a significant disadvantage, which is unreliable the work of the resulting protective coating under fluctuations in the temperature of the medium and the surface of the product to be protected, especially when the temperature of a stationary or incident gas flow rises above 150-200 ° C, accompanied by shrinkage, fracturing and intensive ablation of the protective coating layer.

An object of the invention and a positive result of the invention is to obtain a material with higher physicochemical characteristics of adhesion during temperature fluctuations of the environment and the substrate (coating) with increasing temperatures (higher than hazardous and critical indicators for analogues), the absence of shrinkage process and the prevention of mesh development cracking on the surface of the protected product from materials of various kinds, both homogenous and heterogeneous materials from heterogeneous components.

The specified result in the invention is achieved by the original sequence of operations of the method and the use of new materials for its implementation.

The main distinguishing features of the claimed invention are the use of a new highly heat-resistant polymer binder - poly (o-hydroxyamide) - the polycondensation product of isophthalic acid dichloride with 3,3'-dihydroxy-4,4'-diaminodiphenylmethane. Polycondensation is carried out in amide solvents, moreover, the molar ratio of the reagents when obtaining poly (o-hydroxyamide) is chosen in the range: isophthalic acid dichloride: 3,3'-dihydroxy-4,4'-diaminodiphenylmethane: solvent - from 1: 1: 7 to 1.05: 1: 15. Poly (o-hydroxyamide) after completion of polycondensation is precipitated from the reaction solution into a mixture of organic solvents, and the protective material is obtained in the following ratio of components, wt.%: Polymer binder - 20-30, carbon nanofiber, carbon nanoclusters - 2-10 received pi by methane roll on a Ni / MgO catalyst with a fiber length of 50-100 μm and a diameter of 20-60 nm, the rest is a solvent, their subsequent mixing is carried out until a homogeneous composition is obtained. Films formed from poly (o-hydroxyamide) and thermally suppressed at 350 ° С can withstand heating up to 400 ° С in air and 450 ° С in an inert atmosphere for up to 1 h, weight loss does not exceed 5%, since poly (o-hydroxyamide) after heat treatment at 350 ° C it turns into a highly heat-resistant polybenzoxazole.

The proposed polymer binder is well combined with carbon nanofibers and carbon nanoclusters having, as indicated, a fiber length of 50-100 μm and a diameter of 20-60 nm. When carrying out the polycondensation reaction by varying the ratio of the starting reagents, the viscosity of the solution can be varied, and therefore the molecular weight of the polymer, and the use of precipitated polymer in the composition makes it possible to obtain polymer solutions of a given viscosity. High heat resistance allows you to expand the scope of the finished protective coating.

Example 1. Obtaining heat-resistant protective material according to the proposed method.

a) Obtaining poly (o-hydroxyamide) from isophthalic acid dichloride and 3,3'-dihydroxy-4,4'-diaminodiphenylmethane is carried out as follows: 1 g-mol of 3,3'-dihydroxy-4,4'-diaminodiphenylmethane is dissolved in 11.2 g-mol of dimethylacetamide containing not more than 0.035% moisture at room temperature. The solution is cooled to 0 - (- 5 ° C) and 1.0 g mol of carefully ground isophthalic acid (II) dichloride is added to the cooled solution with stirring over 5-7 minutes, so that the temperature of the reaction mass does not rise above 40 ° FROM. Upon completion of the addition, the mixture is stirred for 90-120 minutes at room temperature. Then the reaction mass is again cooled to

0 - (- 5 ° С) and 2 g-mol of freshly distilled epichlorohydrin are added dropwise over 15-20 minutes, after which the solution is stirred at room temperature for 60 minutes. The resulting viscous polymer solution is diluted with a twice volume of dimethylacetamide, dimethylformamide or N-methyl-α-pyrrolidone and pinned to a mixture of solvents: chloroform-isopropanol, taken in a volume ratio of 5: 1, cooled to 0 - (- 5 ° C). The precipitated precipitate of poly (o-hydroxyamide) is filtered off, dried at 70 ° C for 5 hours, then at 40 ° C in a vacuum oven for 3 hours. Quantitative yield, reduced viscosity of a 0.5% solution in concentrated sulfuric acid 1.2 dl / g.

b) Obtaining heat-resistant protective material.

20 hours the resulting poly (o-hydroxyamide) is mixed with 20 parts by weight N-methyl-α-pyrrolidone, the mixture is left to swell for 12 hours, after which 10 parts by weight of added to the solution. carbon nanofibers and carbon (l = 50-100 microns, d = 20-60 nm) nanoclusters are stirred for 2 hours. The resulting suspension is applied to glass. The obtained layers were dried at 130 ° C for 1 h; the average film thickness was 200 μm. It should be noted that carbon nanoclusters were evenly distributed over the surface and held well. The films dried at 130 ° С were subjected to stepwise thermal suppression in air (150 ° С 15 min, 200 ° С 15 min, 250 ° С 15 min, 300 ° С 15 min, 350 ° С 30 min). After heat treatment, the films did not crack, and the integrity of the layer was not violated. Films have high chemical resistance. They do not dissolve in any of the organic solvents, are stable with respect to strong acids and alkalis, various types of plasma, and are removed only with 98% nitric acid and oxygen plasma. The films can withstand heating up to 400 ° C in air and 450 ° C in an inert atmosphere for up to 1 h, mass loss does not exceed 5%. A study of the absorption of microwave radiation by films formed on glass from a protective material based on poly (o-hydroxyamide) and carbon nanoclusters showed that, compared with the material described in application No. 2006145803/04, the absorption coefficient of undecided films based on poly (o- hydroxyamide) exceeds it by an order of magnitude, and in thermally suppressed by 2-3 orders of magnitude.

Example 2. Obtaining a heat-resistant material for a protective coating is carried out analogously to example 1, but the ratio of the reactants in the production of poly (o-hydroxyamide) is 1.2: 1: 7. A polymer with a low molecular weight is obtained, the films have a small thickness and, as a result, the uneven distribution of carbon nanoclusters over the film surface. Protective properties are reduced.

Example 3. Obtaining a heat-resistant material for a protective coating is carried out analogously to example 1, but the ratio of the reactants in the preparation of poly (o-hydroxyamide) is 1: 1.2: 7. Get a polymer with a low molecular weight, which significantly impairs the protective properties of the material.

Example 4. Obtaining a heat-resistant material for a protective coating is carried out analogously to example 1, but in the manufacture of a composition with carbon nanoclusters used a reaction solution of poly (o-hydroxyamide). The protective properties of the film are reduced.

Example 5. Obtaining a heat-resistant material for a protective coating is carried out analogously to example 1, but the protective material is prepared in the following ratio of components, wt.%: Polymer binder poly (o-hydroxyamide) - 20, carbon nanoclusters - 1. The protective properties of the film are reduced, since there are spaces that do not contain carbon nanoclusters.

Thus, the use of highly heat-resistant poly (o-hydroxyamide) as a polymer binder in the material for protective coatings provides high adhesive ability and reliable protective properties when applied to surfaces of various chemical nature.

Claims (3)

1. A method of obtaining a heat-resistant material for a protective coating, comprising dissolving a polymer binder in a solvent, which is used as poly (o-hydroxyamide) - the product of polycondensation of isophthalic acid dichloride with 3,3'-dihydroxy-4,4'-diaminodiphenylmethane in a solvent at the molar ratio of reagents, respectively, from 1: 1: 7 to 1.05: 1: 15, filling the solution with carbon nanofibers, carbon nanoclusters obtained by methane pyrolysis on a Ni / MgO catalyst with a fiber length of 50-100 microns and a diameter of 20-60 nm, followed by mixing them to obtain a homogeneous composition containing, wt.%:
polymer binder 20-30 carbon nanofiber, carbon nanoclusters 2-10 solvent rest 2. The method according to claim 1, characterized in that the polycondensation is carried out in amide solvents. 3. The method according to claim 1, characterized in that the poly (o-hydroxyamide) is planted from the reaction solution into a mixture of organic solvents.