A method of obtaining a non-woven material to absorb electromagnetic radiation in the microwave range

 

The invention relates to the creation of a nonwoven material intended for the manufacture of protective clothing and screens from exposure to microwave radiation. The technical result is to increase the absorption ability of the material in the microwave range and simplify the process. The invention consists in the preparation of the blend of fibers in three stages: first put the carbon fiber on the dielectric manually Klochkov weight of 0.5 to 1.0 g, the second conducting rough ploughing with weight control bits to reduce their average weight less than 0.01 g, the third conducting thin loosening and brushing blend, and the fixing structure of the canvas and duplication takes place simultaneously by piercing needles. 4 C.p. f-crystals, 4 Il.

The invention relates to the creation of a nonwoven material from a blend of dielectric and electrically conductive fibers, absorbing microwave radiation in a wide frequency range. Material intended for the manufacture of protective clothing items and screens from exposure to microwave radiation, and can also be used as the material for anechoic chambers.

A method of obtaining absorber AMY comprising mating hollow greeu change of proportions between the dielectric and conductive fibers in the mixture. The disadvantages of this method - a multi-stage, the complexity and high cost of the produced materials with limited protective properties [1].

The closest analogue of the known method is a technology for producing non-woven material to absorb electromagnetic radiation in the microwave range, including the dosage of the dielectric fibers and carbon fibers, preparation blend dielectric fibers and carbon fiber, molded double-layer fabric of the blend [2]. The method allows to obtain a material with a reflectivity of radiation to 19.2 dB.

The disadvantage of this method is the complexity of technology and the low absorption capacity of the material in the microwave range of electromagnetic waves.

The technical problem on which this invention is directed, is to simplify the process and increase the absorption ability of the material in the microwave range of electromagnetic waves.

The problem is solved in that in a method of producing a nonwoven material to absorb electromagnetic radiation in the microwave range, comprising the bulk dielectric and carbon fibers, preparation of a blend of fibers forming the nonwoven x the ri stage, on the ground lay the carbon fiber on the dielectric manually scraps of 0.5 to 1.0 g, the second conducting rough ploughing with weight control bits of carbon fiber in the dielectric volume and decrease their mass to 0.01 g, the third conducting thin loosening and brushing blend, the fixation structure of the canvas and duplication takes place simultaneously by piercing needles.

Piercing duplicated canvases needles produce through in the direction perpendicular to the plane of the canvas towards each other with a density of 10-100 punctures on 1 cm2. Duplicated canvases sequentially stacked on one side of the first canvas. When applying each subsequent layer package bonded canvases pierce for all thickness.

Technical essence, inventive step and novelty of the proposed Increase range of health involves the use of materials with a significant dispersion of dielectric properties. The dispersion occurs either at the level of conductive filler or material in General. In the General case it is determined by the source of electromagnetic heterogeneity, the size of which is comparable with the radiation wavelength. In the first case, senecaut as a consequence of the structure or technological features of manufacture of the material.

Non-woven material, transparent to the wavelengths of microwave radiation, works as interferention-absorbing material. A significant amount of frequency dispersion of n1and n2(Fig.1, 2) allows to implement such options manufacture of nonwovens, in which the sample material will function as a quarter-wave absorbing layer in a higher frequency band than conventional absorbing materials, ie, increase the range of operability of the material.

Fig. 1. The dependence of n1samples of nonwoven material to absorb electromagnetic radiation in the microwave range of frequency.

Fig. 2. The dependence of n2samples of nonwoven material to absorb electromagnetic radiation in the microwave range of frequency.

Absorbing properties are amplified and frequency response of the material is significantly improved (aligned) with the duplication of non-woven sheets with evenly distributed in the volume of carbon fiber.

In the multilayer nonwoven fabric due to the sequential stacking of paintings and multiple punching needles in a certain way increases the concentration of carbon fibre, resulting electromagnetic oscillations and wave length as it approaches the surface to be protected.

The process of manufacturing non-woven material includes the following process steps: the weight of fibers in order to obtain the required concentrations before mixing different fibers, preparation of the multilayered structure of dielectric and electrically conductive fibers, loosening of the fibers in the rough Ripper, loosening of the fibers in a thin Ripper, itching fibers, aerodynamic haloorange, hardening of woven canvas poprobyval, the formation of the multilayered structure of the canvases with different content of electrically conductive fibers, duplication canvases poprobyvat.

The invention is illustrated by the following examples.

Examples 1-2. Get an absorber of electromagnetic radiation from a blend of polyester and carbon fibers. Pre-hung components in the ratio, providing the concentration of the carbon fibers in the mixture 3 and 4 wt.% respectively. Applied polyester fiber 0.33 Tex diameter of 10-15 μm and a length of 60-65 mm; carbon fiber brand "Avlon-2" with a diameter of 7-10 μm and a length of 60-65 mm conveyor unload polyester fiber and hand-laid carbon fiber for polyester in the form of pieces of a mass of 0.5-1.0, Spend gross loosening of the CSOs. To control take samples from 15-20 bits and determine their total and average mass. The average weight of one piece should not be more than 0.01, In the case of non-compliance with this parameter gross loosening repeat again. The coarse loosening 20 minutes.

For further separation of pieces of the fibrous mass into smaller structural elements and mixing them together spend loosening of the fibers in a thin Ripper. The mixture of fibers thin after loosening served on veloceprod in the drive before carding unit. From the drive fibrous mass is fed into the carding machine for its separation into individual fibers and ensure uniform and uninterrupted supply in the disconnected state at the stage of formation of the canvas. The degree of separation (tangle free) and bias fibers regulate by changing the speed of rotation of the working bodies of the carding machine (replacement removable sprockets and pulleys) and the wiring between the main and removable-chechoseme rolls.

In the process of forming non-woven canvas carry out removal of fibers from the removable-kasumiga shaft, transported in suspension in the air stream in the chamber of the wind consoles for the formation and deposition of fibers in the material weighing 150 g/m2.

The surface density change by regulating the speed of movement of the conveyor blade at a constant performance carding machines. After the formation of the canvas provide a fixing structure of bilateral perforation needles. Density punching above 7 cm-2bottom 22 cm-2. The absorber of electromagnetic radiation as in example 1 placed on a conductive surface and measure the reflection coefficient of electromagnetic radiation from a frequency in the range from 2.5 to 37.5 GHz. The dependence of the reflection coefficient of electromagnetic radiation of frequency is shown in Fig.3.

Example 3. From canvases nonwoven fabrics obtained in examples 1-2, form a two-layer construction and duplicate their poprobyvat.

The dependence of the reflection coefficient AMY frequency shown in Fig.4.

Absorbing properties of the composite material containing carbon fiber is higher than that of the material obtained according to the method in all the investigated wavelength range from 2.5 to 37.5 GHz.

Sources of information 1. Pat. RF 2119216, CL H 01 Q 17/00, 1998

2. Pat. The USSR 1790795, CL H 01 Q 17/00, 1990

Claims

1. A method of obtaining a non-woven IU blend of fibers, the formation of non-woven canvas, the fixation structure of the canvas and duplication, characterized in that the preparation of the blend fibers are in three stages: first put the carbon fiber on the dielectric in the form of scraps of mass 0.5-1.0 g, on the second conducting rough ploughing with weight control bits, the third conducting thin loosening and brushing blend, the fixation structure of the canvas and duplication takes place simultaneously poprobyvat.

2. A method of obtaining a non-woven material to absorb electromagnetic radiation in the microwave range under item 1, characterized in that the coarse loosening spend with weight control bits of carbon fiber in a period of time sufficient to reduce the average weight of the pieces to less than 0.01,

3. A method of obtaining a non-woven material to absorb electromagnetic radiation in the microwave range under item 1, characterized in that for the preparation of blend fibers using 0.5-15 wt. % carbon fiber.

4. A method of obtaining a non-woven material to absorb electromagnetic radiation in the microwave range under item 1, characterized in that the formed non-woven canvas weighing 100-150 g/m2.

5. A method of obtaining a non-woven material to absorb elec carry out bilateral poprobyvat.

 

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FIELD: textile industry.

SUBSTANCE: three-dimensional nonwoven fibrous textile material is composed of netted woven carcass and layers of fibrous cloths arranged at both sides of carcass and mechanically attached thereto. Carcass is produced from thermoplastic weft threads with linear density of 29-72 tex and thermoplastic warp threads with linear density of 14-20 tex and surface density of 80-220 g/m2. Said threads are preliminarily subjected to shrinkage. Method involves applying onto melted netted woven carcass layers of fibrous materials and mechanically attaching said layer in alternation to each side; applying onto each side of carcass at least one layer of fibrous cloth and attaching it by needle stitching; subjecting nonwoven material to thermal processing at temperature of 80-1580C under pressure of 0.3-0.6 MPa for 40-120 min.

EFFECT: improved organoliptical properties and improved appearance of material.

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