JP2001149721A - Filter element and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a filter element hardly clogging and capable of adsorbing and removing a harmful material. SOLUTION: Many narrow pores are provided by applying a thermal perforation work to a sheet consisting essentially of a natural organic fiber to hardly cause clogging, and the circumference of the perforation part is converted to activated carbon at need to adsorb and remove a water dissolved harmful material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter element mainly composed of natural organic fibers and a method for producing the same.

[0002]

2. Description of the Related Art Filter elements made from natural organic fibers as main raw materials have been widely used, and such materials include cotton, cotton, kabok, hemp, flax, ramie, hemp, jute, manila hemp, Sisal, coconut fiber, seaweed, straw, wool, wool, alpaca, angora, silk, feathers, etc. are used. It's being used. Such a conventional filter element mainly uses an action of filtering out particles in gaps formed between organic fibers, and has a problem that clogging is likely to occur. Further, such a filter element has a problem that harmful substances such as organic compounds cannot be adsorbed and removed.

[0003]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to prevent a filter element using a perforated sheet mainly made of natural organic fibers from being easily clogged. And to be able to adsorb and remove harmful substances.

[0004]

SUMMARY OF THE INVENTION The object of the present invention is to provide a film-shaped perforated sheet mainly made of natural organic fibers by providing a large number of pores having a diameter corresponding to the purpose of use by hot perforation. Irradiate a laser whose power density is controlled to the periphery of the perforated portion for a predetermined time, if necessary,
This is achieved by crystallizing the peripheral portion by a dehydrogenation reaction so that harmful substances mixed in the fluid to be filtered can be adsorbed and removed.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The filter element according to the present invention is a filter element in which natural organic fibers are formed into a sheet and a large number of pores are provided by thermal perforation. In the present specification, a perforated sheet mainly composed of natural organic fibers is a woven fabric,
Any of non-woven fabrics and films may be used. The pores have extremely high energy in the sheet, for example, like an excimer laser, and
A wavelength of 300 nm or less, preferably provided by performing ablation processing by irradiating light of about 193 to 395 nm,
During this processing, perforation is performed by evaporation. After ablation processing by NC control, the position of the pores obtained by ablation processing is irradiated with light having an energy density of 10 ⁶ Joule / cm ² or less whose position is accurately controlled by NC control, and if necessary. It is recommended that the irradiation time be controlled to obtain graphite crystals having the required activity on the inner wall surface of the hole.

In some cases, the pores may be formed by irradiating a longer wavelength light beam and performing thermal processing without using an excimer laser. Such processing is generally performed in water because it does not require a special activation treatment, but may be performed in an inert gas atmosphere such as steam. By dehydrogenating the natural organic fibers by such thermal processing, the processed surface of the sheet can be carbonized and graphitized, thereby processing the slits having an adsorption action, and further, by the gaps between the graphite crystals. It is also possible to enhance the interlayer adsorption effect.
Also, various substances can be synthesized by utilizing the adsorption action. If a laser is used for this thermal processing, the material on the inner surface of the hole can be made highly crystalline and highly oriented graphite, and a filter element with a wide range of use can be obtained. In addition, utilizing the gap between graphite crystal layers,
It can also be expected to utilize the adsorption phenomenon that occurs between the intercalant guest material, the graphite host material, and the graphite having pores.

The sheet may be made of a natural organic fiber as a main material and a woven cloth. For example, a sheet of viscose rayon film may be made by integrating cotton fiber, hemp fiber, regenerated cellulose fiber or the like into a nonwoven fabric. It is fine. Further, various modifying agents, coloring agents, stabilizers, binders, and the like can be added to the fibers, and the fibers can be impregnated with phenol or the like. The nonwoven fabric sheet based on this film has pores with an average pore diameter of about 10 to 20 μm, and the porosity is about 30 to 40%. About a few pores,
The porosity is raised to 70-85%, at which time the burst strength is about 2-10 kg / cm ² . In the present invention, for example, a perforation having a dehydrogenation-crystallization-active layer is formed by thermal perforation processing in which the heating time and the heating temperature are controlled in steam, and a carbonized layer formed on the perimeter of the perforation,
The activity is high so that harmful substances can be easily adsorbed, and organic substances can be removed by interlayer adsorption.

[0008] Hereinafter, the heat drilling process will be described. When drilling by laser, if the temperature gradient of the drilled part of the workpiece is 体,

(Equation 1) Therefore, if the wavelength is changed, the temperature gradient of the perforated portion can be controlled, and if the wavelength is short, ablation will occur. By controlling the degree of dehydrogenation and graphitization by changing the temperature gradient ψ,
The perforated portion can be crystallized and activated, and excellent adsorption characteristics can be imparted to the periphery of the perforated portion. In the present invention, ψ = 10
Since it can be about ^3-6 [k / cm], by controlling the degree of dehydrogenation and the crystallization and activity (gap formation, crystal size), it is controlled to have the required adsorption characteristics of the crystallized part. it can.

Further, when controlling the diameter of the perforation, when the diameter of the perforation by the laser is r,

(Equation 2)

When E / E _m > e, the diameter of the perforation can be minimized. Since the opening angle (glance angle) of the laser beam is about 1 mrad, r is 10 to 150 μm.
It can be seen that control can be easily performed within a range of about m.

The maximum temperature at the center of the hole is the position of the center of the focal point. If the maximum temperature is T _m ,

(Equation 3) If the thermal characteristics of the workpieces are the same, the maximum temperature T
_M is

(Equation 4) Therefore, it works at a half power of the irradiation time.

Therefore, the diameter of the hole can be controlled by controlling the laser irradiation time. When the part where the perforation is provided is ablated, a carbonized layer is hardly formed there, but if irradiation is performed at another wavelength and the inner wall surface of the hole is subjected to thermal processing, the organic fibers are carbonized and the degree of carbonization is reduced. Various carbonized layers from carbon to graphite can be provided accordingly. As the material for the workpiece, natural organic fibers of polysaccharides such as cellulose (lignin) and hemicellulose (liglycellulose) can also be used.

When natural product lignin is used, a desired molecular weight can be obtained by reacting under high temperature and high pressure using Fe ₂ O ₃ , Fe ₃ O ₄ , Al ₂ O ₃ , CrCuO or the like as a catalyst. it can. On the other hand, allylated wood is converted to cellulose derivatives,
Knead with dimethyl phthalate to plasticize lignin,
A sheet formed by hot pressing or an organic film can be processed into a filter element.

FIG. 1 is a partially enlarged sectional view of the perforation, and FIG.
FIG. 2 is an enlarged sectional view of the carbonized layer shown in FIG. In the figure, h is the thickness of the sheet, L is the processing diameter, r is the hole diameter, l is the hole pitch,
u is the irradiation light radius, C is the carbonized layer, A is the activated layer, B is the graphite layer, and D is the carbon layer. This sheet is made of cellulose fiber having a thickness of 1 mm and having pores having an average diameter of about 40 to 60 μm.
About 100 to 100 μφ.

The sheet was held at a water distance of about 1 mm, and irradiated with a laser having a wavelength of 808 nm, a focal length of 40 mm, and a power density of 5 × 10 ⁸ W / cm ² . As shown in FIG. 2, the carbonized layer C includes an activation layer a, a graphite layer b, and a carbon layer d, and has different properties. When the volume ratio of each layer is an average value, when the dimensional ratio is expressed in percentage, the activation layer part a is 51.9% and the graphite layer part b
Was 44.3% and the carbon layer part d was 3.5%. When the benzene adsorption capacity of each layer is determined, the activated layer portion a is about 44
%, The graphite layer part b was about 18%, and the carbon layer part d was about 5% or less.

Generally, the adsorption is

(Equation 5) As shown in this [Equation 5], all are adsorbed to each layer and balanced. Adsorption potentialξ
² and l _n X will be plotted as a straight line, and the adsorption characteristics will be determined. Activated graphite and the graphite carbon part each have this property.

The adsorbing ability of each layer when perforated under such conditions depends on the rate and amount of dehydrogenation from natural organic fibers, the degree of crystallinity, and the crystallization rate and amount of graphite. Determined by the pores generated by CO and CO ₂ conversion. Preferably, the crystal plane spacing between the activation layer part a and the graphite layer part b is about 4 ° for the activation layer part a and about 3.5 ° for the graphite layer part b, respectively.

When measuring the pore, the radius of the pore is u
given that,

(Equation 6) Can be obtained as

The measurement results show that a pore having a diameter of 10 nm is 0.4 ml /
g, and according to the present invention, by piercing,
It can be seen that the organic material crystallizes according to the processing conditions of the laser, and the portion has different adsorption characteristics from the unprocessed portion depending on the degree of crystallization and generation of the gap.

When controlling the adsorption characteristics, the drilling process includes:
As shown in FIG. 3, two types of lasers having different power densities and different heating characteristics may be used. FIG. 4 shows a distribution diagram showing the carbon characteristics. Natural organic substances are thermosetting, for example, the binding energy of the HC bond of cellulose is 78 to 104 kcal / mol, and the binding energy of the CC bond is 50 to 230 kcal / mol; The maximum value of this value is 4.4 ev / atm for HC and 9.8 ev / atm for CC.

When the temperature corresponding to this electron volt (Lenald-Jones potential) is obtained, 1ev = 11596 K, which indicates that an organic dehydrogenation crystallization phenomenon occurs under conditions corresponding to extremely high temperatures. As shown in FIG. 2, the thermosetting organic fibers are dehydrogenated and crystallized and activated. According to this, 300 to 5 carbonization (dehydrogenation)
In the range of 00 ° C, the dehydrogenation reaction proceeds at about 500 to 1000 ° C, and the crystallization of carbon gradually narrows at 1500 to 3000 ° C.
In the range, the carbon is crystallized to become graphite, and a crystal interlayer reaction can be used.

In the meantime, when H ₂ O and / or CO reacts with graphite, fine pores are formed on the surface and the graphite is activated and the surface energy becomes high. A laser with a high power density must be used for dehydrogenation, and the degree of dehydrogenation, crystallization, and slit formation can be controlled by the supplied power density. In particular, when the energy density (considering the wavelength) is high, ablation occurs, the temperature gradient becomes extremely high, and the carbonized layer becomes small.

The adsorption characteristics of the activated graphite are shown in Table 1.

[Table 1] As described above, the adsorption characteristics of graphite vary depending on the nature of the adsorbed molecules, and in addition, organic compounds such as aldehydes, amines, glycols, ethers, and ketones are also adsorbed.

[0024]

[Example 1] A cellulose cotton sheet 1 m in length, 50 mm in width and 1 mm in thickness contains phenol 20 wt%,
Specimen 1 with a porosity of 40% and a porosity of 60
% Sample 2 was obtained. The maximum diameter of the piercing holes of these test materials 1 and 2 was 40 μm, and the minimum diameter was 20 μm. One set of test materials 1 and 2 is held in water at a depth of about 1 mm, respectively.
As described later, the wavelength is 1.06 μm in YAG, the output power is 100 W, the focal diameter is 40 mm, and the power density is 1 × 10 ⁸ W by NC control over the entire surface excluding the region 5 mm from the margin where the margin is formed when folded in 45. Using a laser of / cm ² , drill holes with a hole diameter of 80 μm and a hole pitch of 0.4 mm, fold each of them into 45 folds, form them into a cylindrical shape with an outer diameter of 6 cm and an inner diameter of 20 mm. A obtained a filter element B from sample 2.

Another set of test materials 1 and 2 was subjected to laser processing with an excimer laser (ArF) under the same conditions as those of the filter elements A and B, respectively, and folded 45 times to form a tube. Filter element C from material 1
Filter element D was obtained from sample 2. Further, a pair of still further samples 1 and 2 were subjected to the same perforation as that performed on the filter elements A and B while holding each of the filter elements in a nitrogen gas containing 60% of water vapor. . Thermal processing using a power density of 3.8 × 10 ⁸ W / cm ² , 45 folds and rounding in the same manner as above,
A filter element E was obtained from sample 1 and a filter element F was obtained from sample 2.

For each filter element, a concentration of 50 pp
gas containing sulfur dioxide at a pressure of ³ hPa and a velocity of 0.15 m ³ / s
The pressure and the amount of adsorption acting on each filter element were measured by supplying and passing through ec for 1 hour. 1 from supply
After a lapse of time, each filter element is taken out, washed with distilled water to extract the sulfide adsorbed on the filter element, and titrated with 1 / 10N NaOH to measure the amount of adsorption. Are shown in [Table 2].

[0027]

[Table 2] As a result, after perforating by ablation,
It was found that the pressure acting on the filter element which had been subjected to laser processing by a YAG laser at the perforation position was reduced, the air permeability was increased, and the sulfide adsorption amount was significantly increased. In addition, it was also found that the ventilation amount and the adsorption amount can be controlled by performing only the perforation process by ablation as needed.

[0028]

Since the present invention is configured as described above,
According to the present invention, the filter element is less likely to be clogged, and harmful substances can be removed.

[Brief description of the drawings]

FIG. 1 is a partially enlarged sectional view of a perforation provided in a filter element according to the present invention.

FIG. 2 is an enlarged sectional view of the carbonized layer shown in FIG.

FIG. 3 is an energy condition diagram.

FIG. 4 is a distribution diagram showing carbon characteristics.

[Explanation of symbols]

 h Sheet thickness L Working diameter r Drilling diameter l Drilling pitch u Ray radius c Carbonized layer a Activation layer part b Graphite layer part d Carbon layer part

Claims (4)

[Claims] 1. A filter element comprising a perforated sheet made of natural organic fibers as a main raw material and provided with a large number of pores by perforation by heat. 2. A filter element comprising a perforated sheet mainly made of natural organic fibers impregnated with a resin, cured, and then provided with a large number of pores by perforation by heat. 3. A process of forming a natural organic fiber as a main raw material into a perforated sheet in the form of a sheet, and subjecting the perforated sheet to perforation by substantially overlapping ablation processing and thermal processing at required positions. Forming a large number of pores. 4. A process of forming a natural organic fiber as a main raw material into a sheet-shaped perforated sheet, and controlling a heating temperature at the periphery of the pores formed by the perforation process to obtain a required carbon property. Forming a carbonized layer.