LT6597B - OBTAINING OF MULTIFUNCTIONAL MATERIALS WITH EMF INHIBITION PROPERTIES BY MODIFYING SOFT POLYMERIC MATERIALS WITH SILVER SELENIDES (Ag2Se) - Google Patents

Abstract

The present invention relates to the chemical modification of polymeric materials for the purpose of providing them with specific functional properties and is used for the modification of soft cell polymers (such as natural, synthetic and mixed raw materials and non-woven textiles, soft polymer composites, soft polymeric foams) by silver selenides (Ag2Se) receiving multifunctional materials with EMF inhibition properties. In order to achieve the purpose various types of soft polymeric materials modified are treated with a polycyclic two-stage sorbing-diffusion method. In modified various structures materials silver crystals of silver selenides (Ag2Se) are formed not only on the surface of the treated materials, but also at the microstructure level. The effectiveness of EMF radiation inhibition is determined by the structure of the modified material, the thickness and density of the Ag2Se layer formed.

Description

FIELD OF INVENTION

BACKGROUND OF THE INVENTION The present invention relates to the chemical modification of polymeric materials to give them specific functional properties and is intended for the modification of soft polymeric materials (such as woven and nonwoven textiles of natural, synthetic and mixed raw materials, soft polymer composites, soft polymer foams, soft polymer laminates). silver selenides (Ag2Se) to produce multifunctional materials with electromagnetic field (EMF) damping properties.

TECHNICAL LEVEL

Known composite materials for the suppression of EMF radiation to date are polymeric materials containing metallised particles or alloy layers, which are obtained by sophisticated technological processes and used in electronics, optics, solar energy devices and the like. Also known are materials with coatings of electrically conductive polymers, such as polyaniline (PANI), polypyrroline (PPY), polymeric composites with EMF insulating nanofillers.

US4435465 describes a composite material comprising a polymeric matrix containing metallised particles and additives having a high shielding effect against electromagnetic radiation.

CN205467631 describes composites derived from known shielding materials from EMF radiation where the damping function is performed by a layer of electrically conductive silver nanowires on a textile backing. It consists of woven fabric of organic or inorganic origin. On this substrate is poured and impregnated with a suspension, which is made of silver nanofibers and polymer, which acts as an adhesive. A solution of a particular spirit is used as a solvent in the suspension. As the solvent evaporates from the suspension, the silver nanoparticle layer adheres strongly to the carrier tissue.

CN201890978 describes a porous, flexible electromagnetic field suppressive fabric in which portions of 0.2 to 2 mm trap part of the electromagnetic field radiation while at the same time being airtight.

Known CN103114457, which discloses EMF radiation suppressive composites, wherein the suppression function is performed by layers of various metals and their alloys on a textile-based substrate by vacuum or electrochemical multi-cycle operations. Layers of copper or nickel or nickel chromium alloy on a specially prepared fabric are vacuum sprayed with a magnetic spray. The operation can then be repeated. Copper EMF radiation suppressive layers can be deposited from copper pyrophosphate by electrochemically varying the tissue which serves as a substrate. Electrochemical deposition of nickel, mixed nickel cobalt, iron nickel on the textile backing can also occur. Vacuum and electrochemical full cycle deposition of said metal layers is a series of washing, drying, deposition, blasting operations which can be repeated several times depending on the desired end result.

US8227025 describes conductive polymer coatings and methods for obtaining them. No electrically conductive additives are used to obtain these coatings. The conductive polymers may be poly (ethylene-3,4-dioxythiophene) (PEDOT), polyaniline (PAni), polypyrrole (PPy), poly (p-phenylenevinylene) (PPV), polynaphthalene and polyacetylene. These electrically conductive coatings can be used for electrostatic charges, screens, photovoltaics, chemical / biological sensors, transistors, antennas.

On the one hand, the patents found on the development of materials with electromagnetic field suppressive properties differ in their technological solutions and methods of obtaining such materials, on the other hand, our patents on silver selenides and their use for other applications (infrared sensors, photolithographic layers, electrochemical cells, microconverters used in electronics, optical filters, solar cell components).

BRIEF DESCRIPTION OF THE INVENTION

The present invention relates to the protection against electromagnetic field (EMF) radiation emitted by electrotechnical devices, computers, multi-purpose communication devices and other sources of artificial EMF radiation. By multi-cyclic sorbin diffusion of soft polymeric materials of various nature and structure, layers of silver selenide crystals are formed on the surface of the structural members of the material throughout its volume up to the microstructure level. This produces new composite materials with altered physical properties, such as electrical conductivity (the materials become semiconductors), photoconductivity, and the ability to dampen electromagnetic radiation. Materials such as soft, thin and flexible layers can be used to make a variety of accessories (like linings in cell phone cases, phone pockets for bags, handbags or work jackets, etc.), protective device cases, curtains to protect both people and people. devices for protection against EMF radiation, protective vests, constantly working equipment (research laboratories, physiotherapy rooms, etc.) and other products with special needs.

The modified method itself is simple enough and does not require exceptionally high temperatures or high pressures, lasers, plasma or otherwise. Small parts materials can be processed under normal laboratory conditions, larger parts require only bulky vessels and properly selected heating devices. With proper selection of materials and modification conditions, a strong EMF inhibition effect can be obtained.

The present invention describes a method of modifying soft polymeric materials which impart electromagnetic field (EMF) damping properties, which comprises the following two-step cycle:

(a) immobilizing the soft polymeric materials by soaking the material in a solution of potassium selenotrithionate salt and inorganic acid, washing the material 2 to 4 times and drying;

b) forming silver selenide layers on the surfaces of the spatial structure elements of the whole material by soaking in silver nitrate (AgNO3) solution and washing the material 2-4 times and drying;

The sorption-diffusion-derived EMF-inhibiting silver selenide layers were formed throughout the volume of the material at the microstructure level. The two-stage sorption-diffusion treatment cycle is repeated at least 4-6 times, depending on the nature and structure of the material being modified.

The duration of treatment of the specimens in solutions of selenium trithionate and silver nitrate and their temperature and number of cycles depend on the polymeric nature and structure of the material being modified.

In the first step of the cycle, an inorganic acid is used to prepare the solution. According to the nature of the substances being modified, hydrochloric or sulfuric acid is chosen.

In the first step of the cycle, the materials to be modified are soaked in a solution of 50 ° C - 70 ° C and kept for 90-180 minutes.

In the second stage of the cycle, the modifiers are immersed in a silver nitrate solution at 60 ° C and 90 ° C for 20 to 60 minutes.

The process parameters are selected taking into account the thickness and density of the material, and the properties of viscosity.

Soft polymeric materials are suitable for modification from natural and synthetic raw materials such as cotton, wool, linen, bamboo, nettle, silk, rayon, semi-wool, polyamide (PA6 and PA66), polyacrylonitrile (PAN), polyester (PE), polyurethane (PU) ), etc., as well as their blends, such as wool, etc.

Soft polymeric materials of different structures, such as woven and nonwoven, soft foam, soft polymer composites, are suitable for modification.

What is new is that in the composite materials obtained by the process of this patent, EML radiation is inhibited by silver selenide layers, which are formed by sorbin diffusion on the surface of all elements of the spatial structure of the material, that is, at the microstructure level.

BRIEF DESCRIPTION OF THE FIGURES The figure shows images of the internal microgrids of modified polyamide filaments obtained by scanning electron microscope (SEM): a - after 1 cycle of modification, b - after 6 cycles of modification.

Figure 6 shows SEM images of a polyamide fabric with a siliconized underside after 6 cycles of modification: a - fabric surface, b - underside of silicone material, c - microfibre surface of the fabric composite filaments.

Figure 1 gives an example of the results of the EDS method of measuring the elemental composition of the upper surface of a modified polyamide fabric (Figure 1, a).

Figure SEM images of microstructured elements of modified materials of different nature:

(a) - natural linen multifilament microfibres (6 cycles) (b) - cotton multifilament microfibres (6 cycles) (c) - wool multifilament microfibers (6 cycles) (d) - PA6 multifilament microfibres (6) treatment cycles) (e) - PA66 fiber / PU foam composite cross section (6 treatment cycles) (f) - PU foam inner pores (3 treatment cycles) gives examples of EMF inhibition studies of modified materials (measured by ASTM 4935) and material characteristics.

Figure 3 shows examples of EMF inhibition studies of modified materials (measurements performed in an absorbent - coated chamber using four - band horn antennas and a variable frequency microwave source).

More detailed measurement methodology is described in the literature below.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to the chemical modification of soft polymeric materials by providing EMF inhibitory properties. The essence of all soft polymeric materials for this purpose is the production of composites or composite materials containing components that inhibit, absorb, and / or reflect electromagnetic fields (EMFs). The most important object of the group of such inventions is the nature of EMF radiation suppressing components and methods of making composite materials with them.

The chemical modification cycle described consists of two steps, the first being the pickling of the material and the second the formation of silver selenide layers on the surface of the structural members of the material.

The substances to be modified are soaked in the first stage of the cycle in a solution of 50 ° C to 70 ° C prepared as follows: Dissolve potassium selenium trithionate salt (K2SeS2O6) in hydrochloric acid 0,1 mol / L at 50 ° C 4-70 ° C, at a concentration of 0.054-0.1 mol / L in the reconstituted solution. The duration of the soaking (gelatinization) depends on the nature and structure of the material being modified and may last from 90 to 180 minutes. Thereafter, the modified material is washed with 2-4 times (depending on material structure, density) distilled (or technically desalinated) water at 20 ° C-40 ° C to remove residual solution and further dried at room temperature for 24 h at φ = 30% - 40 % or in appropriate conditions in the drying units.

In the second step, the triturated material is immersed in a solution of silver nitrate (AgNCh) at 60-90 ° C for 20-60 minutes (depending on the structure, density and polymeric nature of the material). This solution is prepared by dissolving the crystalline silver nitrate salt in distilled (or technically desalinated) water to give a concentration of 0.05 to 0.1 mol / L in the prepared solution. Thereafter, the material is again analogously washed with water and dried as after the first step.

Changes in the color of the material after the first modification cycle (the materials acquire a darker or lighter gray color) indicate that the first silver selenide derivatives have formed on the surface of the structural elements of the material but do not completely cover the entire microstructure of the material. As the cycles of modification are repeated, the amount of silver selenide derivatives increases and gradually a continuous layer of these crystals forms on the surface of the structure-forming polymers. Figure 1 shows images obtained by internal microscopic scanning electron microscopy (SEM) of polyamide filament filaments after 1 and 6 cycles of modification.

The SEM images in Figure 6 show that the silver selenide crystal layers after 6 cycles of modification are formed on the surface of the structural members of the material throughout its volume up to the microstructure level, that is to say on the macrostructure surfaces of the modified material (in this case Fig. 2, a and b), both on the surface of the internal filaments of the filaments (Fig. 2, c). Figure 3 shows a diagram of the EDS method for measuring the elemental composition of the upper side of this material (Figure 1, a). The results of studies are presented in Table Table1

The chemical element Names of characteristic X-ray lines Abnormal concentration by weight [wt.%] Normalized concentration by weight [norm. wt.%] Normalized concentration by atomic mass [norm. at.%] Error% Coal K-series 9.856522 11.07805 36,66746 1,359159 Oxygen K-series 7.254616 8.153689 20,26035 1.125451 Silver L-series 51.61117 58,00741 21,379 1,757858 Selenium L-series 14.52139 16.32104 8,217,455 0.722256 Fluorine K-series 5,729,718 6,439808 13,47574 0.987688 Amount: 88,97342 100 100

Natural, synthetic and mixed raw materials (such as cotton, wool, linen, bamboo, nettle, silk, rayon, semi-wool, polyamide (PA6 and PA66), polyacrylonitrile (PAN), polyesters, polyurethane (PU)) and different structures can be modified (woven and non-woven textiles, soft foams, soft polymer composites) soft polymer materials. Figure 4 presents SEM images of microstructural elements of modified materials of different nature.

The effective inhibition of EMF depends both on the amount and density of silver selenide crystals formed in the material and on the structure of the material being modified. Importantly, the structure of the modified material should be such that it does not have porosity that goes through the entire volume of the material. In other words, the smaller the spacing between the structural elements of the material (filament microfibres, pore walls, etc.) coated with silicon silver selenide crystals, the less likely it is that EMF waves will absorb the crystals and pass through the material. As the area of the openings in the material structure increases, the EMF inhibition efficiency decreases. Figures 5 and 6 show EMF inhibition efficiency diagrams for materials of various polymer compositions and structures. Examples of test results are shown in Tables 2 and 3

Material A: Mixed composition non-woven fabric Material B: Wool coat: Material C: Non-woven polyester fabric fiber: Surface Density 410 g / m ² 571.8 g / m ² 342 g / m ² Bulk density 126.0 kg / m ³ 221 kg / m ³ 95.3 kg / m ³ Thickness mm (before / after) 3.23 / 3.31 2.59 / 2.45 3.59 / 3.62 Silver selenide concentration 0.2746 mmol / cm ³ 0.2311 mmol / cm ³ 0.0491 mmol / cm ³ Material Factor * 100% -99.4% - 99.6% 'Describes the coverage of a material area by structural elements (thread, pore wall, etc.) without leaving holes.

table

Material A: Mixed nonwovens Material D: Polyamide fabric with silicone bottom side: Material C: Double layer soft laminate (Cambrella type nonwoven + foam): Surface Density 410 g / m ² 355.3 g / m ² 32 g / m ² Bulk density 126.0 kg / m ³ 640 kg / m ³ 5.7 kg / m ³ Thickness, mm (before after) 3.23 / 3.31 0.56 / 0.70 5.60 / 5.01 Silver selenide concentration 0.2583 mmol / cm ³ 0.3115 mmol / cm ³ 0.0362 mmol / cm ³ Material Factor * 100% -99.7% ~ 99.9% 'Describes the area coverage of the material, etc.) without leaving holes. structure elements (thread, pore walls and

The proposed method allows additional modifications of individual product details (eg, inserts only in pockets or cases for telephones, insulating parts of the housing of electrical appliances (eg microwave oven) without substantially altering existing product manufacturing principles (sewing, shaping, gluing, etc.). , etc.), it is possible to modify a wide range of soft polymeric materials already available on the market with different polymer composition and structure (natural, synthetic and mixed raw materials woven and nonwoven, soft foam, soft polymer composites).

Literature

D. K. Ghodgaonkar, V. V. Varadan, V. K. Varadan. A free-space method for measurement of dielectric constants and loss tangents at microvave frequencies, IEEE Transactions on Instrumentation and Measurement ,, vol. 38, p. 789-793, 1989.

M. Venkatesh, G. Raghavan. An overvievv of dielectric properties measuring techniques, Canadian Biosystems Engineering, vol. 47, p. 15-30, 2005.

P. Ragulis, R. Simniškis, Ž. Chancellor. Shift and Elimination of Microvision Fabry-Perot Resonances in a Dielectric Covered with a Thin Year Layer. Journal of Applied Physics, 117, 165302, 2015.

Claims (6)

DEFINITION OF INVENTION 1. A method of modifying soft polymeric materials by providing them with electromagnetic field (EMF) damping properties, characterized in that the method comprises the following two-step cycle: (a) immersion of the soft polymeric materials by soaking the material in a solution of potassium selenium trithionate salt and inorganic acid and washing the material 2 to 4 times and drying; b) forming silver selenide layers on the surface of the spatial structure elements of the whole material by soaking in silver nitrate (AgNCh) solution and washing the material 2-4 times and drying; wherein EMF-inhibiting silver selenide layers are sorption-diffused throughout the volume of the material at the microstructure level; wherein the two-stage sorption-diffusion treatment cycle is repeated at least 4-6 times, depending on the nature and structure of the material being modified. 2. A process for the modification of soft polymeric materials according to claim 1, wherein the inorganic acid is hydrochloric acid or sulfuric acid. 3. Modification method for soft polymeric materials according to claim 1 or 2, characterized in that in the first cycle step the solution temperature is 50 ° C to 70 ° C and the first cycle step is carried out for 90-180 min, depending on the nature and structure of the materials to be modified. 4. The method of modification of soft polymeric materials according to claim 1 or 2, characterized in that in the second stage of the cycle the temperature of the solution is 60 ° C to 90 ° C and the second stage of the cycle is carried out for 20-60 minutes. 5. The method of modification of soft polymeric materials according to any of the preceding claims, characterized in that the soft polymeric materials suitable for modification are selected from natural, synthetic and mixed raw materials such as cotton, wool, linen, bamboo, nettle, silk, rayon, semi-wool. , polyamide (PA6 and PA66), polyacrylonitrile (PAN), polyester (PEP), polyurethane (PU). 6. A process for modification of soft polymeric materials according to any one of the preceding claims, characterized in that the soft polymeric materials suitable for modification are selected from different structures, such as woven and nonwoven textiles, soft foams, soft polymeric composites, soft polymeric laminates.