KR950009257B1 - A manufacturing method of radarware camouflage fabric - Google Patents

Abstract

The camouflage fabric against a superwide band rader wave is manufactured by (a) weaving a nylon multifilament of 70 deniers to be 30 strands/cm weft and warp density, respectively, (b) coating a thermoplastic synthetic resinous adhesive emulsion on the woven fabric, (c) cutting a polyacrylonitrile carbon fiber having 6.8 micrometer diameter, 1.8g/cm3 density, 350kg/mm2 tension strength and 1.5 x 10-3 ohmcm volume intrinsic resistance, and a pitch carbon fiber having 13 micrometer diameter, 1.66g/cm3 density, 80kg/mm2 tension strength and 1 x 10-2 ohmcm volume intrinsic resistance to be 3-8 m/m ave. fiber length, and (d) spraying the mixed fiber on the coated fabric by 5-15g/m2 spraying amount.

Description

Method of manufacturing camouflage fabrics for ultra-wideband radar waves

1 is a manufacturing process schematic diagram of the present invention.

Figure 2 (a) is an enlarged plan view of the camouflage fabric produced by the present invention, (b) is an enlarged plan view showing another embodiment of the camouflage fabric produced by the present invention.

* Explanation of symbols for main parts of the drawings

a: synthetic fiber fabric b: carbon fiber

1: Doctor Knife 2: Rotating Brush

3: suction device 4: vibration device

5: conveyor 6: dryer

7: Calendering roller

The present invention relates to a method of manufacturing a phase fabric that can phase an object from an ultra-wideband radar wave.

The ultra-wideband radar wave above is the centimeter of the wavelength, and the second one is the radar wave scattering camouflage network in the centimeter wave region currently operating in many countries of the world. Conductive elements such as yarns are irregularly arranged or mixed in a woven or nonwoven fabric to attenuate the radar signal by dipole polarization scattering by these elements to impart a camouflage effect.

This scattering results in gastrointestinal effects by causing the radar beam to be irregularly diffused over a wide range so that the radar cross section of the target is deformed.

There is also a negative aspect that this requires installation considerations in terms of actual operation and is a barrier to other precision electromagnetic equipment in the installation network.

Thirdly, it absorbs radiative wave and imparts gastrointestinal performance.

This is because the radiated radar wave energy of the fabric scattered with a special material such as carbon is converted into heat energy and then extinguished. Therefore, if the above principle is applied to the camouflage network fabric with a certain opening, the radiation radar wave is attenuated. Since radar echo is the same, it can give gastrointestinal performance very effectively.

It is an object of the present invention to provide a method for producing a fabric for a camouflage network that imparts camouflage performance by absorption to ultra-wideband radar waves for military detection or target tracking.

In general, the _precursor metal has a positive positive temperature coefficient (α _0-1000 ). Specifically, aluminum is 4.2, iron is 6.6, copper is 4.3, and nickel is 6.7. Although the resistance increases and the conductivity decreases, certain materials such as carbon and selenium have a negative temperature coefficient, so the conductivity increases as the temperature increases.

Therefore, it can be seen that carbon is more advantageous than other materials in converting radiated radar waves into thermal energy.

The present invention is to apply a radar wave absorption mechanism by the carbon fiber scattering method in the production of a radar wave attenuation network that the need is gradually increasing in the military.

The gastrointestinal effect on the radar of the gastrointestinal network was measured by one way transmission according to the attenuation rate test procedure of the U.S. Army's test evaluation command gastrointestinal network and the U.S. military radar scattering type gastrointestinal standard (MIC-C-53003B, May 20, 1989). In this case, it is specified that there should be a decay effect of 10-20% (7-10dB) in gastrointestinal state.

In general, carbon fiber is made by fiberization of the isotropic pitch system by the glass flow spinning method, and carbonization of the fiber obtained by spinning polyacrylonitrile, followed by sizing with epoxy resin. have.

Most of such carbon fibers are produced in Korea with a filament diameter of 5.4 μm to 18 μm and a volume resistivity of 1.5 × 10 ⁻³ to 1 × 10 ⁻¹ μm cm.

The characteristics of the present invention are to cut the carbon fibers to a certain length and make them into short fibers, and then spread them on the synthetic fiber fabric so that they are not oriented so that the camouflage effect having an excellent absorbing power of 10 to 20% against ultra-wideband radar wave radiation The present invention relates to a method for producing a wave absorbing camouflage network fabric.

Hereinafter, the present invention will be described in detail.

The radar wave absorption rate of the short carbon fiber scattered fabric at a certain frequency is absolutely affected by the length, spread amount, and scatter pattern of the scattered carbon fiber.

In the present invention, in order to derive the optimum conditions for each of these influence factors, the fiber length was 0.7 to 10 mm, the dispersion amount was 5 to 20 g / m 2, and the sample size was prepared to be 2 m × 2 m.

The apparatus for producing these samples used a well-known electrostatic locking machine as shown in FIG.

While moving the synthetic fiber fabric (a) to the grounded conveyor (5), coating the synthetic resin adhesive on the surface with the doctor knife (1), and then rotating the carbon fiber (b) with a rotating brush (2) high pressure electrode Through the sieve (8) of the synthetic fiber fabric (a) is dropped to the surface.

At this time, the synthetic fiber fabric (a) is vibrated by the vibrator (4) so that the dropped carbon fibers (b) are evenly fixed to the synthetic resin coating layer and at the same time the excess carbon fibers (b) are easily discharged from the suction device (3) Be sure to

Subsequently, after drying by passing through the dryer 6, in order to eliminate the floating phenomenon of the scattered carbon fibers, it is calendered and wound by the calendering roller 7.

In the present invention, the polarization voltage of the bonded carbon fiber (b) is lost only when the carbon fiber (b) is naturally dropped so that the interpolar voltage is much lower than that of the conventional hair-growing products. Or co-polarization).

As for the fiber length of the carbon fiber used for this invention, 1-20 mm was suitable.

If the fiber length is shorter than 1 mm, the damping effect is less. If the fiber length exceeds 20 mm, the water absorption is too high, which is not preferable.

The most suitable fiber length was 3-8 mm.

In addition, in the present invention, the dispersion amount of carbon fiber was 5 to 20 g / m 2.

If the amount of dispersion is less than 5g / ㎡, the absorption rate is not satisfactory. If it exceeds 20g / ㎡, the excessive production cost of the product due to the use of carbon fiber increases and the weight is heavy. It was.

The most suitable coating amount was 10-15 g / m <2>.

The attenuation rate test on the radar wave of the prepared sample was carried out using the radar measuring equipment shown in Table 1, and the measurement condition was 90 ° with respect to the direction of the radar beam, and the distance between the transmitting and receiving antennas was Farfield region (RF = 2D2 / λ, where RF is the distance between the transmitting and receiving antennas, D is the maximum opening size of the antenna, and λ is the wavelength).

TABLE 1

Decay Rate Measurement Equipment Specification Table

Example 1

After weaving 70 denier nylon multifilament yarn into a plain weave with a weft density of 120 yarns per 5cm, apply a thermoplastic resin adhesive emulsion to it, and then diameter 6.8㎛, density 1.8g / ㎠, tensile strength 350㎏ Carbon fiber (PAN-based carbon fiber) carbonized with polyacrylonitrile having a volume specific resistance of 1.5 × 10 ⁻³ Ω㎝, 13 μm in diameter, density of 1.66 g / cm 3, tensile strength of 80 kg / mm 2, Isotropic pitch-based carbon fibers having a volume specific resistance of 1 × 10 ⁻² Ωm were cut into average fiber lengths of 3, 5, and 8 mm to obtain 10, 12, 15 g / m3 of dispersion by the electric method.

Table 2 shows the results of measuring the radar wave attenuation rate by general transmission in each frequency domain.

Example 2

The same fabrics and carbon fibers as in Example 1 were used, but the PAN-based carbon fibers had an average fiber length of 3 mm, and the pitch-based carbon fibers had an average fiber length of 5 mm. The results of the attenuation rate measurement test with 12 g / m2 dispersion are shown in Table 2.

TABLE 2

Radar attenuation rate according to fiber length and dispersion of carbon fiber

Claims (2)

In the case of dispersing carbon fibers having a volume specific resistance of 1.5 × 10 ^{−3 to} 1 × 10 ⁻¹ Ω㎝ on a synthetic fiber fabric coated with an adhesive by a conventional electrical method, a fiber length of 3 to 8 m / m is used. A method for producing a camouflage fabric for ultra-wideband radar waves, characterized in that it is produced so that the dispersion amount of 5 ~ 15g / ㎡. The polyacrylonitrile-based carbon fiber having a volume specific resistance of 1.5 × 10 ⁻³ cm ³ and a fiber length of 3 m / m and a pitch carbon fiber having a volume specific resistance of 1 × 10 ⁻² cm 3. Method for producing a camouflage fabric for ultra-wideband radar wave, characterized in that the fiber length is 5m / m mixed to be used in a weight ratio of 1: 1, the dispersion amount is 12g / ㎡.