CN1190544C - Normal-pressure low-temperature plasma treater for modifying fiber surface - Google Patents

Abstract

The invention relates to a device for generating normal-pressure low-temperature plasma between planar discharge electrodes by dielectric barrier discharge and performing fiber material modification treatment. It is characterized in that the processor is mainly composed of four parts: a pair of coolable planar discharge electrodes, two parallel dielectric barrier plates between the two electrodes, two reaction gas conduits, and two gas guide plates. The processor can avoid arc and spark discharge between electrodes, and generate uniform low-temperature plasma under atmospheric pressure. Fiber materials that stand still or continuously pass through the discharge area can be treated with uniform plasma at atmospheric pressure to obtain effective surface modification. The chemical fiber material that is left standing or continuously passes through the discharge gap between two parallel dielectric barrier plates of the processor, after uniform plasma treatment, the surface wettability and dyeability of the fiber are significantly improved, and arc and spark discharge can be avoided. breakdown and damage.

Description

An atmospheric pressure low temperature plasma treatment device for fiber surface modification

Technical field:

The invention relates to a low-temperature plasma treatment device at normal pressure. More precisely, the device can avoid arc and spark discharge between electrodes, and generate uniform plasma under atmospheric pressure conditions by dielectric barrier discharge, so that it can be statically or continuously passed through The fiber material in the discharge area is treated with normal-pressure uniform plasma to obtain effective surface modification, and the hydrophobic chemical fiber material is modified into a hygroscopic material, and the dyeability of the material is also significantly improved. It belongs to the field of fiber modification.

Background technique:

Dielectric barrier discharge is a method of generating low-temperature plasma under atmospheric pressure conditions. It is widely used in ozone synthesis, air and water purification, making ultraviolet light sources, and exciting gas lasers. For example: ZL99213572.9 and CN99115989.6 respectively disclose a low-temperature plasma ozone generating sheet and a dielectric barrier discharge lamp. The principle is: there is a dielectric layer between the opposite electrodes or on the surface of the electrodes, so that the discharge space between the electrodes generates plasma beams or plasma gas. In the field of material modification, plasma polymerization is carried out on the surface of the material under low pressure conditions, and the surface of the material can be modified. For example, CN1259759 and ZL99218828.8 disclose a plasma finishing device for fabrics. Low-temperature plasma is generated under the conditions to modify the fabric. The surface modification treatment methods of plasma materials under these vacuum conditions consume a lot of energy in vacuuming, and are not suitable for realizing industrial continuous production. And CN1277267 discloses a non-equilibrium plasma at normal pressure for metal surface strengthening, which utilizes ultra-high voltage pulse power supply to generate plasma at normal pressure, and improves the strength of metal through strong ion penetration. The temperature and energy of the atmospheric-pressure non-equilibrium plasma produced by this process are too high to be used for the surface modification of fiber textile materials obviously. Develop plasma devices and treatment techniques that can effectively modify the surface of fiber textile materials under normal pressure conditions, which are suitable for industrialized continuous production and treatment, and are used to improve the hygroscopicity of chemical fiber materials and improve the wearability and performance of chemical fiber materials. Dyeing performance, has a great market prospect. It is a pity that there is no report on the treatment device that uses dielectric barrier discharge to generate low-temperature plasma at atmospheric pressure and can effectively modify the surface of fiber materials.

Invention content:

The purpose of the present invention is to provide a low-temperature plasma processor at atmospheric pressure. This device uses dielectric barrier discharge to avoid arc light and spark discharge to generate uniform plasma under atmospheric pressure conditions. The fiber material placed in or continuously passed through the discharge area After uniform plasma treatment at atmospheric pressure, effective surface modification can be obtained. Hydrophobic chemical fiber materials are modified to become hygroscopic materials. At the same time, the dyeing performance of the material is significantly improved.

Another object of the present invention is to use the processor for the surface modification of fibrous materials by static or continuous passage through a discharge zone.

The normal-pressure low-temperature plasma processor provided by the present invention includes a pair of planar discharge electrodes cooled by coolant, two special dielectric barrier plates placed between the two electrodes, two reaction gas conduits and two gas guide plates. It is characterized by:

(1) The processor is composed of upper and lower parts placed in parallel, each part is a cuboid box made of polytetrafluoroethylene or other pressure-resistant insulating materials on the side, and the upper and lower parts of the processor are parallel on the opposite surface , a rectangle is dug out in the middle and sealed with a special dielectric barrier plate. The slit between the upper and lower parts of the processor and the two dielectric barrier plates is the space for plasma generation and processing. The upper part of the processor can be translated to adjust the appropriate The slit distance can allow the processed object to stand still or pass through continuously. The slit distance is generally 1-5mm;

(2) The two special dielectric barrier plates placed between the two electrodes are two ceramic dielectric material plates with polished surfaces. They are respectively welded or bonded on two parallel and opposite surfaces of the upper and lower parts of the plasma generator and the processor.

(3) The two planar discharge electrodes are respectively fixed in the upper and lower parts of the processor, are respectively attached to the two dielectric barrier plates, and are isolated from the plasma generation and processing space. This structure effectively prevents the evaporated electrode material from being deposited on the object to be treated, and avoids metal deposition pollution. The two electrodes are rectangular metal boxes made of stainless steel, copper or other metals (such as brass, aluminum). The metal box and The surface close to the dielectric barrier plate should be polished, and the metal box is connected to the coolant circulation cooling system with a delivery pipe. When discharging, the coolant flowing through the metal box is used to cool it down.

(4) The upper and lower parts of the processor are each equipped with a gas conduit parallel to the electrode. There are gas outlet grooves on the side of each conduit facing the slit. Internal transport of reaction gases (see Figure 2).

(5) The two dielectric plates are best to use surface-polished ceramic dielectric material plates such as silicon oxide, ceramic plates containing Mg, Si ₃ N ₄ , Al ₂ O _3, etc. The plate with a large dielectric constant is too thin , the ability of the dielectric plate to resist voltage will decrease; when the thickness is too thick, the discharge voltage is too high, and it is difficult to maintain the uniformity of the discharge. The electrodes and dielectric plates need to be polished, and the electrodes are cooled during discharge to avoid arc and spark discharge, and to ensure uniform discharge between the dielectric plates to generate uniform plasma.

The external equipment of the atmospheric-pressure low-temperature plasma processor provided by the present invention includes a high-frequency high-voltage power supply system, a gas supply system and a cooling circulation system.

The normal-pressure low-temperature plasma processor provided by the present invention is cooled with transformer oil or other high-voltage-resistant coolant, and the two discharge electrodes are cooled by circulating the coolant through a pump;

In the normal-pressure low-temperature plasma processor provided by the present invention, a high-frequency AC voltage is applied to the two-plane discharge electrodes through a commercially available high-frequency high-voltage power supply system, the frequency of which is 5KHz-20KHz, and the voltage is greater than 3KV. Adjust the frequency and voltage according to the thickness of the fiber material to be modified, and pass a suitable discharge gas in the discharge slit to generate a uniform plasma of the gas used in the discharge space between the two dielectric barrier layers inside the two electrodes , and can avoid arc and spark discharge.

Another object of the present invention is implemented through the following steps:

(1) Adjust the slit distance according to the properties and thickness of the modified fiber material;

(2) Continuously input the gas used to generate plasma into the slit between the upper and lower parts of the plasma processor; the reaction gas flow rate is 2L/min-5L/min, and the gas is an inert gas, an inert gas and air, or an inert gas Mixed gas with other gases such as nitrogen;

(3) Apply high-frequency AC high voltage to the two electrodes: within the properly matched frequency and voltage range, and under the appropriate gas flow rate, the uniform plasma at normal pressure can be generated by discharging in the slit space between the two dielectric barrier plates, And can avoid arc and spark discharge;

(4) The fiber or fiber product to be treated that is placed in the plasma generation and processor discharge slit or passes through the slit continuously can obtain effective surface modification after being treated for more than 10 seconds.

The improved wettability of treated fibers or fibrous products is confirmed by the following methods:

Spread the sample on the surface of the colored solution (usually 5% potassium dichromate solution), and measure the time for the material to completely wet. Alternatively, drop 0.2 cc of water onto the surface of the sample, and measure the diameter or area of the circular wet spot that the water drop spreads on the surface of the sample within 20 seconds. Apparently, the atmospheric pressure plasma processor provided by the present invention can conveniently constitute a production device for continuous industrial plasma treatment. It only needs to set several plasma processors provided by the present invention in the forward direction of the object to be treated. A certain material travel speed ensures sufficient processing time for the material to be treated, and each plasma generator and processor can use different reactive gases to obtain different treatment effects.

The advantages of the present invention are also obvious. Utilize the plasma processor and using method of planar electrode dielectric barrier discharge provided by the present invention, it is easy to treat various fiber textiles in a large area, and under the condition of good discharge, no spark or arc discharge occurs, avoiding arc discharge and overheating The ablation, perforation and thermal damage of the treated object caused by the plasma temperature, the uniform plasma temperature and energy generated by the discharge are appropriate, and the hydrophobic chemical fiber material can be permanently obtained without destroying the internal structural properties of the fiber. Hygroscopic modification, the wettability of the fiber is significantly improved. Under the same dyeing conditions, the dyeing performance of polyester (PET) fabrics has been greatly improved.

This kind of processor can form an atmospheric pressure plasma continuous processing device together with external equipment and a material transmission system, which is used in industrial production. It is a new technology for energy-saving and environmentally friendly fiber material modification.

Description of drawings:

Fig. 1 is a schematic structural view of the atmospheric pressure low temperature plasma processor provided by the present invention.

Figure a is a side view. During continuous processing, the right side is the material inlet, and the left side is the material outlet.

Figure b is the front view of the discharge port of the processor. During continuous processing, the processed fiber or fiber fabric moves from the inside to the outside.

Fig. 2 is a structural schematic diagram of the lower half of Fig. 1 . The upper half has the same structure. In the picture:

1- Plasma generation and processor lower half

2-Plasma generation and the upper part of the processor 3-The upper electrode dielectric plate

4-lower electrode dielectric plate 5-upper electrode 6-lower electrode

7-upper gas duct 8-lower gas duct 9-upper and lower gas deflector

10-material 11-electrode coolant delivery pipe 12-gas delivery pipe

13 - The upper surface of the lower half of the plasma processor

14-The lower half of the plasma processor has a rectangular opening, the fixed lower electrode is placed in the rectangular opening, and the polished surface is close to the dielectric plate of the lower electrode

15-The air outlet groove of the lower gas duct

Detailed ways:

Below through specific embodiment, further set forth substantive characteristic and remarkable progress of the present invention, but the present invention is by no means limited to embodiment.

Example 1

Continuous treatment of polyester (polyethylene terephthalate PET) woven fabrics was carried out using the atmospheric pressure low-temperature plasma processor in Figure 1. The two electrodes are brass, and the silicon oxide plate is used as the blocking medium. The upper and lower electrodes add about 10KHz AC high voltage, argon gas or argon gas mixed with air is passed into the discharge slit between the upper and lower parts of the processor as the discharge gas, and a blue-purple bright glow is produced in the discharge space, and the observation Less than arc flash and spark discharge. The larger the argon flow, the brighter the glow in the discharge space and the stronger the discharge. The distance between the slits is 3 mm.

The polyester cloth is placed statically in the discharge slit, or slowly passes through the discharge slit several times. Under the condition of stable discharge, regardless of static treatment or continuous treatment, under the same condition of ensuring the same treatment time, the final treatment effect of the polyester cloth is the same. When treated for about 2 minutes, there is no change in the appearance of the polyester cloth, and no thermal damage or ablation or perforation caused by arc and spark discharge is observed.

Before the treatment, the water drop was hemispherical on the polyester cloth and did not spread out, but immediately spread out on the cotton cloth to form a circular wet spot. After the treatment, the water droplets spread out on the polyester cloth immediately, and after 20 seconds, the diameter of the round wet spot reached about 40 mm, which is the same as that of the cotton cloth.

Dyeing with the same concentration of disperse red dye under the same dyeing conditions, the dyeing effect of the treated sample is significantly improved compared with the untreated sample. In the best case, the color brightness is increased by about 12%, and the chroma is increased by about 23%.

This increase in hygroscopicity has not changed significantly for at least one year. The color change is also washable.

When the processing conditions are not suitable, a linear discharge channel will appear in the discharge space, and the discharge glow will become dark. After the treatment, there will be ablation pores with a diameter of about 0.5mm penetrating the sample at the linear discharge channel. The number of holes varies with the degree of deterioration of the discharge uniformity, ranging from a few to dozens or hundreds of holes in an area of 100 cm ² , and the sample has been destroyed at this time.

Example 2

PBT (polybutylene terephthalate) meltblown nonwovens (meltblown nonwovens) with an areal density of 170 g/ ^m2 were subjected to static or continuous processing using the plasma generation and processor in Figure 1. Roughly the same method as Example 1 is processed, but the processing conditions are different. In the case of stable discharge, there was no change in the appearance of the sample after treatment, and no thermal damage or ablation or perforation caused by arc and spark discharge was observed.

The PBT melt-blown non-woven fabric before and after treatment takes a sample with a diameter of 5 cm. Before the treatment, the non-woven fabric sample is flat on the surface of a yellow 5% potassium dichromate solution, and the non-woven fabric floats on the water surface without wetting within 20 seconds; The treated sample was immediately wetted in less than 1 second, and the white nonwoven turned yellow.

When the processing conditions are not good, the discharge degradation phenomenon similar to that of Example 1 will also appear, and the sample will also be damaged by ablation.

After the untreated sample was placed on the surface of the solution for 2 minutes, it has been floating on the water surface and is not wet at all; the effect of the untreated sample after soaking in the potassium dichromate solution for 3 minutes, the material has poor hygroscopicity and is not wet. The color of the sample basically does not change; after uniform plasma treatment under stable discharge conditions, the sample is spread on the surface of the solution and immediately absorbs moisture and changes color evenly. After being treated for 8 minutes under the condition of uneven and weak discharge, the sample will absorb moisture and change color in some areas on the surface of the solution. Although the wetted area increases with the prolongation of the treatment time, it is still uneven, and the material will appear perforated.

Claims (8)

1. A normal-pressure low-temperature plasma treatment device for fiber modification, characterized in that: (1) The provided normal-pressure low-temperature plasma processor includes a pair of planar discharge electrodes cooled by coolant, two dielectric barrier plates placed between the two electrodes, two reaction gas conduits and two gas deflectors; The whole processor is composed of upper and lower parts placed in parallel, and each part is a cuboid box made of polytetrafluoroethylene or other pressure-resistant insulating materials on the side. It is a rectangle and sealed with a special dielectric barrier plate. The slit between the upper and lower parts of the processor and the two dielectric barrier plates is the space for plasma generation and processing. The upper part of the processor can be translated to adjust the appropriate slit distance. Allow the treated objects to stand still or pass through continuously; (2) The two dielectric barrier plates placed between the two electrodes are two polished ceramic dielectric material plates, which are respectively welded or bonded on the two parallel opposite surfaces of the plasma generation and the upper and lower parts of the processor ; (3) The two plane discharge electrodes are respectively fixed in the upper and lower parts of the processor, are respectively attached to the two dielectric barrier plates, and are isolated from the plasma generation and processing space; (4) The upper and lower parts of the processor are each equipped with a gas conduit parallel to the electrode. There are gas outlet grooves on the side of each conduit facing the slit. The reaction gas is transported inside. 2. The atmospheric-pressure low-temperature plasma treatment device for fiber modification according to claim 1, characterized in that the distance between the slit between the upper and lower parts of the processor and the two dielectric barrier plates is 1-5 mm. 3. The atmospheric-pressure low-temperature plasma treatment device for fiber modification according to claim 1, characterized in that the two electrodes are cuboid metal boxes made of stainless steel, copper, brass or aluminum, and the metal box The surface close to the dielectric barrier plate is polished, and the metal box is connected to the coolant circulation cooling system with a delivery pipe. When discharging, the coolant flowing through the metal box is used to cool it down. 4. The atmospheric-pressure low-temperature plasma treatment device for fiber modification according to claim 1 or 3, characterized in that the dielectric barrier plate is surface-polished silicon oxide, silicon-containing ceramic plate, Si ₃ N ₄ , Al ₂ O ₃ plate. 5. The atmospheric-pressure low-temperature plasma treatment device for fiber modification according to claim 1, characterized in that the external equipment of the atmospheric-pressure low-temperature plasma processor includes a high-frequency and high-voltage power supply system, a gas supply system and a cooling circuit. 6. The atmospheric-pressure low-temperature plasma treatment device for fiber modification according to claim 1, characterized in that said coolant is transformer oil. 7. The normal-pressure low-temperature plasma treatment device for fiber modification according to claim 5, characterized in that the frequency of the high frequency and high pressure is 5-20KHZ, and the voltage is greater than 3KV. 8. According to claim 1, the atmospheric-pressure low-temperature plasma treatment device for fiber modification is used to process the method for fiber modification by standing still or continuously through discharge, and it is characterized in that the specific steps are: (1) Adjust the slit distance according to the properties and thickness of the modified fiber material; (2) Continuously input the gas used to generate plasma into the slit between the upper and lower parts of the plasma processor; the flow rate of the reaction gas is 2L/min-5L/min, the gas is inert gas, inert gas and air or Mixed gas of inert gas and nitrogen; (3) Apply high-frequency AC high voltage to the two electrodes: within the properly matched frequency and voltage range, under the appropriate gas flow rate, discharge in the slit space between the two dielectric barrier plates to generate uniform plasma at normal pressure, and Avoid arcing and spark discharge; (4) The fiber or fiber product to be treated that is placed in the plasma generation and processor discharge slit or passes through the slit continuously can obtain effective surface modification after being treated for more than 10 seconds.

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