KR20020001178A - Filter paper for air filter and method for manufacturing the paper - Google Patents

Abstract

PURPOSE: A filter paper for air filter is provided, in which the coated filter paper expels dust and collected dust is easily rapped by compressed air thus enhancing the filter life. The filter life is also extended by the strong resistance to water, thus preventing any damage of the filter. Minute vibration endowed with air flow to folded filter paper also expel dust. CONSTITUTION: The manufacturing method includes: (i) coat mixing agent on one face of paper to a thickness of 0.01-0.1 mm to form porous film, the mixing agent being a composition consists of 5% of foam, 4% of crosslinking agent, 0.5-1% of ammonia, a pH adjusting agent, 1-2% of thickening agent, 3-5% of water repellent, 0.4% of NH4Cl, a catalyst, 10% of filler of kaoline talc and CaCO3 and base material of polyurethane; (ii) pre-dry the coated matter in a dry chamber at 100 to 120 deg.C; (iii) press the coated and dried roll at a press of 1 Kg per square centimeter; (iv) redry at 160 deg.C; and (v) cure at 120 deg.C.

Description

Filter paper for air filter and its manufacturing method {Filter paper for air filter and method for manufacturing the paper}

The present invention relates to a filter, and more particularly, to a filter paper of an air filter used in a vehicle, a gas turbine, and the like.

The filter is a means for removing or blocking harmful dusts, etc. introduced with the air in a machine, a room or a facility, and is classified into wet and dry. Filters are also used incorporating dust collectors to purify the incoming air in large quantities. The present invention relates to a dry filter and in particular provides an improved filter paper which can be applied to an air filter of an automobile.

Filtration methods used in dry filters include Depth filtration using a nonwoven fabric and Surface filtration using a paper filter paper. Depth method is to collect the contacted dust up to the collection capacity of the nonwoven fabric, and surface filtration method is to bind the dust to the filter or to stick out to the surface.

Surface filtration is a typical filtration method that has been used for passenger cars. That is, the air supplied to the engine of the vehicle is introduced through the inlet of the filter housing in which the air filter is mounted. An air filter consists of a filter paper and a frame for fixing the filter paper to a specific shape. The filter paper is usually folded in multiple layers to increase the cross-sectional area, and the frame is made of metal, plastic or rubber.

As a filter paper of a conventional vehicle air filter, a thick special paper has been used. The air filter should be periodically sprayed with compressed air to remove the dirt layer adhering to its surface, and the filter should be replaced when the filter paper reaches the end of its life. This is because even in the surface filtration method, since the filter paper is made of paper, the amount of dust particles penetrating into and fixed inside the air filter increases over time.

Paper filters are used in many places, including armored vehicles, military vehicles such as tanks, heavy equipment for construction, or gas turbines. An air filter using paper filter paper may have a pulsing system that automatically removes accumulated dust by spraying compressed air in a direction opposite to the air when the resistance of the air flowing into the apparatus is greater than or equal to a set value. .

On the other hand, air filters for dust collectors using an improved depth filtration method by applying a porous coating on the surface of the nonwoven fabric have been introduced. Such air filters are used in incinerators, cement plants, and the like, and US Pat. No. 5,528,118 illustrates a method for manufacturing the same. The filter employing the porous coating method used around the world, including the above patents, is limited only to its nonwoven fabric.

In addition, the water-soluble porous coating method, which can be referred to as their original technology, is a technique widely known as a coating method of nonwoven synthetic leather. The filtration method, which has been tried in the past, has been made only for the coating technology itself. In other words, the density of the coating film, the development of auxiliary materials added to the main material to be coated, and the like were of major interest.

On the other hand, the present invention has an object to provide a filter paper of the air filter that can extend the life of the air filter using a paper filter.

To this end, the present invention improves and applies the conventional technique of applying a porous coating on the surface of the filter medium, that is, the nonwoven fabric, and uses the same to prepare an air filter.

1 is a configuration diagram and a partially enlarged view of a vehicle air filter according to the present invention.

Figure 2 is a graph of the experimental results of the pressure loss of the filter paper and the conventional filter paper having a coating layer of the urethane base according to the present invention.

Explanation of symbols on the main parts of the drawings

2 ; Vehicle air filter 4; Filter paper

6; Frame 8; Coating layer

12; Paper layer

The above object is to filter paper of a vehicle air filter, characterized in that in the paper filter paper used in the vehicle air filter, a resin layer based on polyurethane is thinly coated (coating) so that a porous membrane is formed on one surface of the filter paper. Is achieved.

The urethane coating technology used in the present invention employs one of the methods currently widely practiced worldwide. Such a method is based on the process of relaxing the raw material wound in the form of a roll and immersing it in a liquid polyurethane emulsion resin composite. Alternatively, a method of uniformly injecting the composite onto the surface of the raw material wound in a roll shape may also be used.

The composite material is a polyurethane resin as a main material, and in addition, various auxiliary materials that have been conventionally used may be added. This will basically be chosen in consideration of the ventilation efficiency, pressure loss or collection efficiency of the filter, the manufacturing cost is also referred to in the preparation of the composite.

The following describes in more detail the improvements in the raw materials, principles and methods to be coated.

The main material of the coating material is 100% Polyuretane or 50% Polyurethane and 50% Acrylic. Acrylic has 30% hard type and 20% soft type.

Preparation of coating raw materials is 5% (foam 20%), 4% (60% solids), PH regulator (ammonia) 0.5-1%, foaming agent containing stabilizer (depending on the pH of urethane) 1 ~ 2% of PH regulator, 3 ~ 5% of water repellent (30% of solid), about 10% of crosslinking agent (100% of solid) of catalyst (NH ₄ Cl), kaoline talc, CaCO ₃ and The same filler consists of 10%. Here, a small amount of TiO ₂ may be added to the filler, which serves as an odor removing function.

The principle and method of coating are as follows. Urethane itself contains a substance that causes foam, and foam stabilizer plays an important role to stabilize and stabilize the pores of foam. The components of these products are saponified products, which are sulfonated products, a kind of surfactant.

The weight of the foam is 200-250g / L is suitable, if it is more than 300g / L is not preferable because the size of the foam (foam) to increase the size of the cell (bubble) to be used to increase the micropores after coating. To reduce foam cell size decreases according to Na ₂ SO ₃ content in foam.

On the other hand, urethane drying is sensitive to temperature unlike the general drying method. If the temperature change is severe or dried at high temperature, temperature control is very important because there is a possibility of cell sinking, no pore formation or clogging.

The drying method after coating is as follows.

Stage 1 ; Temperature drying process to gradually raise the temperature step by step (Dry Chamber) (Pre Dry (at 100-120 ℃)-> cold roll press (1kg / cm ² )-> drying (at 160 ℃).

2 step; After the first step, the aging process at 120 ℃.

After the above process, the urethane is completely hardened and aged to improve resilience and strength, and the adhesive strength between the coating layer and the paper layer is increased by 2 to 3 times or more.

The above is generally a method of membrane coating, and the mixing ratio thereof is basically provided by the urethane seller and the foam seller, and the drying method thereof is also basically provided. Based on these provisions only, the above raw material blending and drying method is obtained under appropriate empirical conditions.

1 is a configuration diagram and a partially enlarged view of the air filter 2 for a passenger car according to the present invention.

The filter paper 4 is fixed in a state of being folded in a plurality of layers by a frame 6 of plastic, rubber or metal. The air filter 2 purifies the air required for combustion of the vehicle engine, and then supplies the air to the intake port of the engine. The filter paper is fixed in pleated form as shown in order to increase its cross sectional area. The filter paper 4 is composed of a double layer of the surface layer 8 and the paper layer 12, which is a coating layer, and is installed such that the coated surface layer 8 is positioned at the air inlet.

In order to prevent a decrease in aeration efficiency which may be caused by the pleated portions of the filter paper contacting each other, the filter paper is folded and fixed after being embossed 10. That is, by the convex portions of the embossing, the folded portions of the filter paper maintain a constant distance from each other.

The urethane coating of the surface layer 8 of the filter paper is carried out so that the pore size is maintained at 0-5 mu m. According to this, dust particles having a particle size of 5 μm or more do not penetrate the filter and adhere to or bounce off the surface. According to the filter paper of the air filter of the present invention, the surface friction force of the surface is reduced to less than 1/2 by urethane, and the elasticity is reduced so that the incoming dust is less likely to penetrate the paper layer 12 of the filter paper. . This extends the life of the filter paper and the air filter using the same.

Figure 2 is a graph of the experimental results of the pressure loss of the filter paper and the conventional filter paper having a coating layer of the urethane base according to the present invention.

The horizontal axis represents time t, and the vertical axis represents pressure p. The graph is a result of checking the increase in pressure load on the blower for blowing air containing dust toward the filter paper over time.

The following table compares the properties of coated and unfiltered filter paper.

Weight (g / m ² ) Breathability (sec) 10mmΦ300cc Burst Strength (kg / cm ² ) Thickness (mm) Pore size (㎛) efficiency(%) maximum Average Early life span After coating 117 1.3 1.6 0.68 92.1 88.4 98.21 98.50 Before coating 100 1.3 1.4 0.60 98.4 88.4 97.97 97.09

In the above results, the coating was treated with about 15-25g / m ² to the coating thickness of about 0.01mm-0.1mm (more preferably 0.02mm-0.04mm), resulting in about twice the collection amount The bursting strength is increased by about 10% to facilitate bending and the deformation after processing is reduced. In addition, even if the collection amount is increased, it can be seen that the life efficiency increases.

In the case of using paper made of pulp as a filter paper, water-repellent treatment has been conventionally performed, but it basically acts as a cause of deformation or deterioration when left for a long time by moisture. However, in the present invention, since the coating treatment is performed with a polyurethane-based composite, the resistance to moisture is increased to prevent moisture from penetrating into the cellulose layer of the filter paper.

According to the filter paper for an air filter having the above configuration and properties, dust that comes into contact with the surface of the filter paper will hit the coating layer and fall off. As a result, the life of the air filter is extended. In addition, the dust attached to the surface can be easily taken off by the compressed air, which is more advantageous in extending the life. According to the air filter according to the present invention, since the resistance to moisture is strong, damage to the filter due to moisture is small. In particular, as in the air filter for passenger cars shown in Figure 1, the pleated filter paper is a fine vibration by the inlet air, thereby double the action of dropping dust.

The air filter according to the present invention is particularly advantageous for heavy equipment including a heavy duty vehicle or a heavy truck, such as a tank armored vehicle, which is generally operated in a dusty place by a strong filtering action, that is, the ability to exclude dust particles. In addition, the present invention can be applied to any kind of air filter using paper filter paper. For example, it is applicable also to the gas turbine of a thermal power plant. In addition, in the air filter having the above-mentioned pulsing system (Pulsing system), the filter paper according to the present invention generates the effect of extending the life of the air filter by maximizing the regeneration efficiency.

Claims (6)

Paper filter paper used for surface filtration air filter, characterized in that the air-based filter is coated with a polyurethane-based mixture of 0.01mm-0.1mm to form a porous membrane on one surface of the filter paper Urethane coated filter paper. The urethane-based admixture according to claim 1, wherein polyurethane is used as the subject; 5% foam with foam stabilizer, 4% crosslinker, 0.5-1% ammonia as PH regulator, 1-2% thickener, 3-5% water repellent, 0.4% NH ₄ Cl as catalyst, filler The urethane coated filter paper of the air filter, characterized in that 10% is used as a preparation. The urethane-based admixture according to claim 1, wherein a urethane (Uretane) 50%, acrylic 50% of the mixing agent is used as the subject; 5% foam with stabilizer, 4% crosslinker, 0.5-1% ammonia as PH regulator, 1-2% thickener, 3-5% water repellent, 0.4% NH ₄ Cl as catalyst, filler The urethane coated filter paper of the air filter, characterized in that 10% is used as a mixture. 4. The filter paper of claim 2 or 3, wherein the filler comprises kaoline talc and CaCO ₃ . 5. The filter paper according to claim 4, wherein the filler is added with a small amount of TiO ₂ . An air filter manufacturing method using a surface filtration method, the method comprising: coating a thin layer of a polyurethane-based mixture on one surface of a paper; Pre-drying step of drying by gradually increasing the temperature between 100-120 ℃ in the drying chamber; Pressing the coating surface by a cold roll press (1 kg / cm ² ); Redrying at a temperature of 160 ° C .; Method for producing a urethane coated filter paper of the air filter, characterized in that it comprises a aging step of aging at a temperature of 120 ℃.