Electret filter and process for producing the same

A manufacturing method and electret technology, applied in separation methods, chemical instruments and methods, filtration and separation, etc., can solve problems such as difficulty in increasing surface charge density

Inactive Publication Date: 2005-08-24
TOYOBO CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, this gazette only describes the stability of electrostatic force during high-temperature use, and there is no description about the improvement of the surface charge density and the improvement of the collection efficiency.
According to the present inventor's point of view, it is difficult to increase the surface charge density only by applying a high voltage at the above-mentioned atmospheric temperature.

Method used

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  • Electret filter and process for producing the same
  • Electret filter and process for producing the same
  • Electret filter and process for producing the same

Examples

Experimental program
Comparison scheme
Effect test

manufacture example 1～8

[0065] Production examples 1 to 7 were obtained by varying the percentages in Table 1 using L-lactide and D-lactide as polymerization raw materials. This raw material was mixed with tin octoate and dodecanol as polymerization catalysts in a reaction vessel, and the inside of the vessel was replaced with nitrogen, then heated at 130° C. for 4 hours under reduced pressure to perform ring-opening polymerization. The reaction product was dissolved in chloroform, and the chloroform solution was diluted with hexane to perform purification by recrystallization. Table 1 shows the obtained resin characteristic values. In addition, in Production Example 1, the reaction product before recrystallization was taken out as Production Example 8.

[0066] [Determination of number average molecular weight]

[0067] The number average molecular weights of the polylactic acid polymers of Production Examples 1 to 8 were determined in terms of polystyrene by the GPC column method.

[0068] [Meas...

Embodiment 1

[0082] With the resin of manufacturing example 1, according to the melt blowing method, make eye pay (weight per unit area) 41g / m 2 , a nonwoven fabric with an average fiber diameter of 2.3 μm, and then, according to the method of charging treatment 1, the electret filter material sample of Example 1 was produced. The surface charge density, filtration characteristic evaluation, and heat of fusion of crystals were measured. Immediately after the measurement of the electrification treatment, and after holding at 25°C x 50RH% x one month, the filtration characteristics were measured respectively. Table 2 shows the results.

Embodiment 2

[0084] With the resin of manufacturing example 2, according to the melt blowing method, make eye pay (weight per unit area) 39g / m 2 , a nonwoven fabric with an average fiber diameter of 2.3 μm, and then, according to the method of charging treatment 1, the electret filter material sample of Example 2 was produced. The same evaluation as in Example 1 was performed. Table 2 shows the results.

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Abstract

It is intended to provide an electret filter which has a large surface charge density, sustains stable electret properties over a long time even in a high-temperature atmosphere and yet degrades to reduce its volume when buried for disposal; and a process for producing the same. The molar ratio of an L-lactic acid monomer to a D-lactic acid monomer ranges from 100 to 85 : 0 to 15 or 0 to 15 : 85 to 100. An electret filter having a surface charge density of 1.2x10<-9> C / cm<2> or more can be obtained by crystallizing by heating at a temperature from the glass transition temperature to the melting point and then, while heating to 60 to 140 DEG C, applying a direct current corona electrical field to thereby cool to 40 DEG C or lower under.

Description

technical field [0001] The present invention relates to an electret filter material with both biodegradability and excellent electret properties and a manufacturing method thereof, in particular to a biodegradable lactic acid polymer as a main component for capturing particles in gas, and An electret filter material having high capture efficiency based on high surface charge density, and its particle capture efficiency can maintain a high value at the initial stage and after being exposed in a high-temperature atmosphere, and a manufacturing method thereof. Background technique [0002] Conventionally, a dielectric material having a relatively long-lived electrostatic charge is called an electret, and it is generally used for separation materials such as air filters, sanitary materials such as shields, and electronic materials such as microphones. The electret filter material is mainly made of polyolefin fiber non-woven fabric and subjected to high-voltage corona treatment t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01D39/16B01D46/50D04H1/42D06M10/02
CPCD06M10/025B01D46/0001D04H1/42B01D39/1623B01D46/0032D04H1/435Y10T428/2913Y10T428/2915Y10T442/60
Inventor 德田省二北川义幸
Owner TOYOBO CO LTD
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