KR100795468B1 - The making method of filter media material by different properties polymers in melt-blown - Google Patents

Abstract

A filtering medium and a method for manufacturing the same are provided to improve the air permeability and the filtering efficiency of the filtering medium, by increasing the bulky property of a web obtained by complex-spinning two kinds of polymers having different melting points. A first thermoplastic polymer, which has a fiber forming performance, and a second thermoplastic polymer, which has a fiber forming performance and a lower melting point than the first thermoplastic polymer, are melt-blown through a spinning nozzle for melt-blown type complex spinning, thereby obtaining a melt-blown complex spinning fiber. The melt-blown complex spinning fiber is hardened by air having a temperature lower than a glass transition temperature of the second thermoplastic polymer before reaching a collector. The hardened complex spinning fiber is collected by the collector, thereby forming a web. The web is thermally treated at a temperature between the melting point of the second thermoplastic polymer and the glass transition temperature to induce a shrinkage difference between the first thermoplastic polymer and the second thermoplastic polymer, thereby increasing the bulky property of the web.

Description

The manufacturing method of filter media using melt blown composite spinning and the filter media by the same {The making method of filter media material by different properties polymers in melt-blown}

1 is a flow chart of the method of the present invention,

2 is a schematic diagram of an apparatus for explaining the method of the present invention.

The present invention relates to a method for manufacturing a filter medium for filtration, and more particularly, to manufacture a nonwoven fabric by melt spinning a composite of two-component polymers having different melting points, and then performing heat shrink treatment to improve filtration efficiency and improve differential pressure. The present invention relates to a method for manufacturing a filter medium using cloud composite spinning and a filter medium thereby.

 Many fine dust and other contaminants are scattered in the environment such as air and water, which not only pollutes the environment but also adversely affects the human body, and has been researching and developing technologies that can effectively filter out such harmful substances. One of them is a filter, and the filter material is various kinds of inorganic materials such as various polymers and glass fibers from general paper materials.

However, unlike the general home environment, in the display industry such as semiconductors and LCDs, which require precise and fine work, a very clean work environment is required. Therefore, it is urgent to develop a filter medium that meets such needs.

In particular, the development of high-efficiency filter media that can filter particles of 0.1um (100nm) or less at the point where nanoscale technology is developed has unlimited possibilities not only in development but also in marketability.

The standard of high efficiency filter generally refers to the filter of HEPA level or higher. In the case of HEPA level, it has the ability to filter particles of 0.3um size 99.97%. However, industrial high-efficiency filters require a filter with a ULPA-grade capability that can filter up to 99.999% of 0.1um particles.

The method of manufacturing the filter media for filtration can be used for all methods of manufacturing nonwoven fabrics such as spunbond, needle punching, melt blown and airlaid. It is possible to manufacture only when various factors such as pore distribution and type of polymer are applied in combination. Currently, high-efficiency media use glass fibers with morphological stability and price competitiveness. However, existing glass fibers can obtain high-efficiency media, but there are environmental problems and material changes over time. to be. In addition, it is difficult to obtain more than 95% of filtration efficiency in other nonwoven fabrics, and it is difficult to obtain high-efficiency media because it has various potential efficiencies such as fiber particle size, web uniformity, and uniformity of porosity.

According to Korean Patent No. 2002-0038801 (Method and Apparatus for Manufacturing Fibrous Electret Web Using Wet Liquid and Aqueous Polar Liquid), a high-pressure water stream pressed against a nonwoven fibrous web impinges on a nonwoven fabric containing nonconductive microfine fibers. The method for improving the filtering performance by generating a charge is disclosed, and Patent Publication Nos. 2002-0041452 and 2002-0093039 and the like also propose a method for improving the filtering performance in a similar manner.

Japanese Patent Application No. 63-51725 discloses a technique for producing a filter medium by adding a spunbond nonwoven fabric to both surfaces of a single component melt nonwoven web.

Since the web manufactured by the above method has a fiber diameter of 3 microns or more and a large diameter variation, the web cannot be used as a high efficiency filter for air conditioning, and above all, has a disadvantage that it cannot be used in a clean room due to electrostatic property. In addition, the method of applying high-pressure water flow is difficult to verify the efficiency of the equipment or the deviation of the efficiency of application, and it is also not applicable to the clean room air conditioning filter due to the electrostatic problem. It is a technique suitable for the manufacture of filter media.

The present invention has been made in view of the above point, and an object of the present invention is to improve the air permeability and filtration efficiency of media by increasing the bulkiness of a web formed by complex spinning two organic polymers having different melting points. It is to provide a method of manufacturing the filter medium.

According to the present invention, a filter medium having a filtration efficiency of at least 99.95% or more and a pressure loss of 10 mmHg or less can be produced.

In order to achieve the above object, the method for preparing a filter medium using the meltblown composite spinning according to the present invention is (S1) a fiber forming ability having a melting point lower than the melting point of the first thermoplastic polymer having a fiber forming ability and the first thermoplastic polymer. Melt-blowing the second thermoplastic polymer having a conventional melt blown composite spinning yarn through a spinning nozzle; and (S2) the glass of the second thermoplastic polymer before the melt-blown composite fiber reaches the collector. Curing the melt-blown composite yarn with air at a temperature lower than the transition temperature: (S3) collecting the cold-solidified composite yarn in a collector and forming a web: (S4) the formed web Heat treatment at a temperature between the melting point of the second thermoplastic polymer and the glass transition temperature of the first thermoplastic polymer and the second thermoplastic polymer It is characterized by increasing the bulkiness in the web by generating a shrinkage difference.

The method of the present invention melt blown two-component polymers having different melting points, and heat shrinkage treatment after the formation of a web, thereby minimizing the size of pores of the fibrous web, and uniformizing the dispersibility. By making it bulky, it not only increases the filtration efficiency of the filter but also lowers the differential pressure. In particular, the meltblown composite ginseng fiber, which has passed through spinneret before forming the web, is cured with cooling air to improve the shape stability of the fibrous web. The long lasting effect can be obtained.

Since single-component polymers control the porosity or surface filtration environment by simple lamination method by itself, there is a limit in performance. Therefore, it is difficult to make highly efficient filter material when it is not very thin fiber such as glass fiber. Although there is a limit to the method for improving efficiency due to the limitation of the present invention, the present invention overcomes this by performing a composite radiation heat shrink treatment of two-component polymer having different melting points.

According to the present invention, it is possible to manufacture a hepa-grade or wool-based filter medium.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

1 is a flowchart of the method of the present invention, and FIG. 2 is a schematic diagram of an apparatus for explaining the method of the present invention. This is described with reference to the drawings.

2-component  Preparation and Complex Spinning of Polymers

The present invention utilizes two-component polymers having different melting points, which can be made into a fibrous web by melt-blown composite spinning. That is, the first step of the present invention is the conventional melt blown composite spinning of the first thermoplastic polymer (1A) having a fiber forming ability and the second thermoplastic polymer (1B) having a melting point lower than the melting point of the first thermoplastic polymer (1B) (S1) The reason for using the two-component polymer having different melting points is to express the bulkiness due to the shrinkage difference of the two-component polymer during heat shrinkage treatment after web formation. The polymer that can be manufactured into a fibrous web by cloud spinning is not particularly limited, but the first thermoplastic polymer and the second thermoplastic polymer should be in combination with different melting points. For example, if the first thermoplastic polymer is polypropylene, the second thermoplastic polymer is a lower melting point polyethylene, polyester, polyamide, polybutylene terephthalate (PBT) or thermoplastic polyurethane (TPU).

Of course, the polymer of the present invention may be added with inorganic and organic additives in order to control the spin viscosity, improve the filtration efficiency and durability of the filter. The kind and effects of such additives are well known and thus are not described here.

Melt-Blown composite spinning can produce 1 micro level of nano-grade fine fibers through fine nozzles such as 35 holes, 50 holes, and 100 holes per inch according to the adjustment of spinning conditions.

The cross section of the composite spun fiber by melt blown composite spun is not particularly limited, and both inner and outer shapes and side byside types can be used. Melt-blown composite spinning is also well known. (E.g., Korean Patent Laid-Open Publication No. 1993-0013311) The method of the present invention is a conventional melt blown composite spinning equipment in which a cooling airflow supply device, a heat shrink treatment device, and an electrostatic treatment device are added. This is schematically illustrated in FIG. 2 as a configuration.

Melt-Brown  Of composite fiber Cooling hardening  And Web formation

According to the method of the present invention, the melt-blown composite spun fiber 3 is melted by air having a temperature lower than the glass transition temperature of the second thermoplastic polymer by the cold air supply device 2 before reaching the collector 4. It comprises the step (S2) of curing the blown composite spun fiber (3). As a result, the composite spun fiber 3 is cooled and cured to improve form stability. Here, although the low-temperature airflow is in contact with the spinning fiber, since the melt blown composite spinning fiber falls downward at a high speed, the curing here is not complete curing, and approximately 10 to 20% of the fiber is cured as it is melted. Collected fibers are collected in the lower collector together and the entire composite fiber evolves into a fibrous web (S3). The temperature of the cooling airflow is approximately 5 to 25 ° C., depending on the type of polymer used and the discharge rate.

Heat shrink treatment

The method of the present invention finally includes performing a heat treatment on the formed web at a temperature between a melting point of the second thermoplastic polymer and a glass transition temperature. (S4) Thus, the first thermoplastic polymer and the second thermoplastic polymer Shrinkage differences occur that increase the bulkiness of the web. The heat treatment temperature depends on the moving speed of the web or the type of polymer used, but should be a temperature between the melting point of the second thermoplastic polymer having a low melting point and the glass transition degree. In the case of the general fiber-forming polymer, the heat treatment temperature is 90 ~ 130 ℃.

blackout( Electro charging )process

The method of the present invention may optionally also perform an electrocharging process on the formed fibrous web (S5). The web is formed by using the electrostatic device 8 supplying the charges (+) and (-), and the electric charges are charged on the surface of the web before being wound on the winder 9. It has a function of adsorbing dust and improves efficiency. At this time, the voltage used is (+) 20-40KV, (-) 15-35KV level. In addition to this method, most filters, except for clean rooms in the semiconductor and electronics industries, also add high dielectric constant additives to the polymer to increase electrostaticity. Filters used in clean rooms in the semiconductor and electronics industries are not electrostatically processed due to electrical problems in semiconductor equipment.

Example 1

According to the process diagram schematically illustrated in FIG. 2, a side-byside type composite spun fiber was obtained using a high density nozzle having 100 holes / inch. As the first thermoplastic polymer, a polypropylene polymer (PMC) of MI (Melt Index) 1500 was used, and polyethylene was used as the second thermoplastic polymer. In order to prevent deterioration of each polymer, a certain amount of thermal stability additives and anti-oxidant additives were added to induce stable spinning, and low-temperature cooling air was given for the shape stability of the fiber spun from the nozzle tip. A thread was obtained.

The formed nonwoven web was formed using a high temperature hot air installation (8) of 100 degrees Celsius or more to induce thermal contraction between two polymers to form a nonwoven fabric. In addition, the formed web was subjected to electrostatic treatment.

The conditions of spinning and heat shrinkage treatment are as follows.

245 ℃

Air pressure 5.3psi,

DCD 15 cm,

Cooling air temperature 10 ℃

Heat Shrinkage Temperature and Speed: 110 ℃, 20m / m

      Electrostatic Treatment: (+) 35KV, (-) 25KV

The formed web was partially or entirely separated by the melting point difference of the two-component polymer by heat shrinkage treatment, and thus, a nano-class fiber of 1 μm or less was prepared as a highly efficient nonwoven fabric.

Example 2

The second thermoplastic polymer of Example 1 was changed to polyester to prepare a web under the same conditions.

Example Foreclosure efficiency Fiber diameter (㎛) One 16.5 99.999 0.8 2 17.5 99.980 0.9

The differential pressure and efficiency in the above are ASTM D-2986 and MIL. According to STD-282 standard, the dioctyl phthalate (DOP) solution was vaporized by TSI-8130 to make very fine particles of 0.12 micron. Measure area is 100cm ² )

Dust collection rate (efficiency) was calculated by the following equation.

100 * (Upstream Light Scattering Amount (Q1)-Downstream Light Scattering Amount (Q2)) / Upstream Light Scattering Amount (Q1)

In the case of diameter, by using SEM (Scanning Electron Microscope) facility that can measure up to 500,000 times, 25 diameters of nonwoven fabrics in each 0.5cm sample plate were randomly selected and measured at random and enlarged by 1000 times. Was obtained.

According to the present invention described above, unlike the non-woven fabric of the polymer material produced in the past, it is composed of nano-grade fibers of 1 μm or less and has a large surface area capable of filtering fine dust, thereby making it possible to manufacture 99.999% high efficiency Ulpa filter. In addition, it is possible to produce differentiated products according to the spinning conditions such as water treatment, air cleaning, automobile cabin filter, etc. by applying various isomer polymers, and it is also possible to apply to fuel cell separators that are actively developed recently. Development is possible.

In addition, the web produced by the present invention, unlike the conventional glass fiber material, there is no risk of environmental problems or human health, and there is no problem of generation of dust (Particles) over time even during long use.

Claims (4)

(S1) Melt-blowing the first thermoplastic polymer having a fiber-forming ability and the second thermoplastic polymer having a fiber-forming ability having a lower melting point than the melting point of the first thermoplastic polymer through a conventional melt blown composite spinning yarn; ; (S2) curing the meltblown composite yarn with air at a temperature lower than the glass transition temperature of the second thermoplastic polymer before the meltblown composite yarn has reached the collector; (S3) the step of collecting the cooling solidified conjugated fiber in a collector to form a web: And (S4) heat-treating the formed web at a temperature between a melting point of the second thermoplastic polymer and a glass transition temperature to generate a shrinkage difference between the first thermoplastic polymer and the second thermoplastic polymer to increase bulkiness in the web. Method for producing a filter medium using a melt-blowing composite spinning characterized in that. The method of claim 1, wherein the first thermoplastic polymer is polypropylene, the second thermoplastic polymer is a melt blown, characterized in that one selected from the group consisting of polyethylene, polyester, polyamide, polybutylene terephthalate, polyurethane Method for manufacturing filter media using cloud composite spinning. The method of claim 1 or 2, further comprising the step (S5) of performing electrostatic treatment on the web after the step S4. A hepa- or wool filter medium produced by the method according to claim 1 or 2.

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