JPS6051388B2 - Filtration media and filtration method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a filter material and a filtering method useful in the food industry, brewing industry, etc.

In the sake brewing industry, a method is used in which organic amino acids, which are responsible for the color, taste, odor, etc. of sake, are adsorbed onto fine activated carbon particles, and this is then filtered in the final finishing step.

For such applications, activated carbon containing at least % by weight of fine particles with a particle size of approximately 40μ or less is used, taking into account the adsorption effect and processing time, etc. Conventionally, asbestos has been used to filter out this fine activated carbon. was. The filtration method in this case is a pressure filtration method, in which a filter cloth is attached to each filter leaf in the filtration machine and assembled, and then the filtration machine is filled with water or filtration stock solution, and asbestos is further dispersed in this to circulate the liquid. Accordingly, a method has been adopted in which asbestos is precoated on the surface of the filter cloth stretched over each filter leaf to form an asbestos layer, and fine activated carbon particles and other fine particles in the filtration stock solution are filtered out using this asbestos layer.
In such filtration methods, asbestos, which is a filter aid, has been used for many years because it has excellent filtration effects such as transparency of the filtrate and performance such as operability (stability of the filtration layer). However, in recent years, asbestos has been designated as a specified chemical substance, and its production and handling are strictly regulated under the Industrial Safety and Health Act.Moreover, due to its nonflammability, it is no longer possible to dispose of used asbestos as industrial waste. , are being forced to ban the use of asbestos.

Therefore, as alternatives to this asbestos, filtration methods using filter paper and filtration methods that use valves and silica earth together are being considered, but these methods have drawbacks in filtration effectiveness and operability. However, since it cannot be incinerated, there remains a problem in terms of waste disposal.

In view of the current situation, the present inventors have developed a filter aid that has the same filtration effect and operability as when using asbestos, can be easily incinerated after filtration, and is safe for the human body. As a result of intensive research, we found that if PVA-based synthetic fibers and PVA fine powder, which have been used as filter bags in the food industry and other industries, are used, the PVA will swell to some extent in the solution and form an excellent filter material. The present invention has been completed based on the discovery that the filtration effect, operability, and waste incineration are extremely good if the filtration material is used to filter an alcohol stock solution such as sake.

That is, in the present invention, a layer consisting of a fiber pulverized product obtained by pulverizing PVA synthetic fibers of 1.0 to 20 deniers into tens to hundreds of microns is filled with insolubilized PVA fine powder mainly having a particle size of several microns to several tens of microns. A filtration material made of a filtration material and a filter material that can be used to remove fine particles in a solution. This is a filtration method characterized by separating components by filtration. The filter material of the present invention is produced by pulverizing PVA-based synthetic fibers into tens to hundreds of microns, dispersing this in water or a filtration stock solution, circulating it in a filter, and first applying it to a filter leaf. A fiber powder layer is formed by uniformly precoating fiber powder on the surface of a filter cloth, and then water in which insolubilized PVA is dispersed or a filtered stock solution is circulated to fill the powder layer with PVA fine powder. .

When forming such a filter medium, the pulverized fibers are required to be highly dispersible in water or the filtration stock solution in order to form a uniform powder layer on the filter/cloth surface, and at the same time, the formed filter medium must be stable. In addition, it is required that the filtration effect is excellent.

There are various methods for pulverizing PVA-based synthetic fibers, but when pulverizing them into lengths of several tens to hundreds of microns, fibrillation of the fibers occurs at the same time. The dispersibility of this pulverized material is better as the fiber denier increases, but the filtration effect decreases, so for PVA-based synthetic fibers, it is appropriate to use pulverized fibers with a denier of 1.0 to 20. .5
Fibers of ~10 denier pulverized into tens to hundreds of microns have excellent dispersibility in water or filtration stock solution, and the powder layer formed is also stable. Since the PVA synthetic fiber has a double cross-sectional structure, when it is crushed into micron units, the skin layer part is torn and the inner core layer is exposed.

During filtration, this core layer may elute into the filtrate and cause foaming of the filtrate. To prevent this, it is desirable to perform further heat treatment after pulverization or insolubilization treatment such as acetalization. If a fiber with a uniform cross section such as alkali bath spun and acetalized PVA synthetic fiber is used, no post-treatment after crushing is required. Although it is possible to filter out fine particles of a certain size only by using a coating layer formed from such pulverized PVA-based synthetic fibers, fine particles with a particle size of 40p or less account for 5% or more by volume, as in the case of filtration of sake stock solution. When activated carbon is separated by filtration, even if the activated carbon itself acts as a filter aid and is filled with a powder layer, a sufficient filtration effect cannot be achieved.

Therefore, insoluble PVA fine powder with a particle size of several microns to several tens of microns is precoated and filled in the same manner as in the powder layer forming method. The PVA fine powder used at this time has a polymerization degree of 500.
As mentioned above, it is desirable that the PVA has a saponification degree of 99 mol % or more and has a particle size of about 80 microns or less that accounts for 5 mol % or more. However, since PVA is normally water-soluble, it must be made insolubilized by heat treatment or acetalization treatment before being applied to the present invention. In particular, the insolubilization treatment by heat treatment of PVA is such that the weight loss after immersion in a 20% ethyl alcohol aqueous solution at 60 °C for 3 hours is less than 5% by heat treatment at about 200 °C, and the swelling in the 20% ethyl alcohol aqueous solution is reduced by less than 5%. It is a very effective treatment method because it has a viscosity of 1.0 to 2.0 and hardly impairs its dispersibility in water. In particular, when filtering sake stock solution, the weight loss after immersion in 20% ethyl alcohol aqueous solution at 60℃ for 3 hours is 5.
% or more of PVA is not preferable because foaming occurs. Since the PVA constituting the filter medium of the present invention is all hydrophilic organic material, it swells to some extent during pre-coating or even after being pre-coated, making the filtration layer more dense and improving the filtration effect, and the filtration layer itself. Stabilize.

The quantitative ratio of the pulverized PVA-based synthetic fibers and the fine PVA powder constituting the filter medium of the present invention varies depending on the particle size and amount of fine particles such as activated carbon contained in the solution to be filtered.

In other words, the activated carbon fine particles contained in the solution to be filtered also act as a filter aid in the same way as the PVA fine powder used in the present invention, so the quantitative ratio of the pulverized fibers and PVA fine powder is not constant. It is desirable that the mixing ratio be such that the PVA fine powder is buried in the layer of the pulverized fibers. For example, when used for filtration of sake stock solution, if the weight ratio of pulverized fibers: PVA fine powder is about 1:2, both the filtration effect and operability are sufficiently satisfied. In particular, in order to maintain operability, that is, the stability of the filtration layer, it is necessary to combine fiber powder and PVA fine particles so that the deposited layer of activated carbon fine particles etc. deposited on the filter medium of the present invention is not destroyed by pressure fluctuations etc. during filtration. It may be necessary to adjust the amount, but this adjustment can be determined empirically. Next, the filtration method of the present invention will be explained with reference to an experimental example in which final filtration of a refined sake stock solution was performed using the filter medium of the present invention and a comparative filter medium.

Glauber's salt bath spinning - acetalized vinylon fiber pulverized product CA),
Power soda bath spinning - acetalized vinylon fiber pulverized product (
B), 20% each of untreated PVA fine powder (C) and 200'C x 1 heat-treated PVA fine powder (D)
Disperse in ethyl alcohol aqueous solution and circulate this through a filter to form individual layers of A, B, C and D on the surface of the filter cloth, and separately add D to layer B (B:D=1:2 (weight ratio ) A filter material was formed.

Table 1 shows the results of final filtration of sake stock solution mixed with activated carbon fine particles using these five types of filter media. Table 1 shows that with the filter medium A alone, the filtrate foamed during filtration, it took a long time to completely remove the activated carbon particles, and elution of PVA was observed.

Foaming of this filtrate and elution of PVA are caused by alkaline spinning-
In the case of the pulverized product (B) of acetalized fibers, there were no problems, but the filtration effect was insufficient. On the other hand, all filter media made of PVA fine powder alone have unstable precoat layers and easily crack due to pressure fluctuations, especially in the case of C alone.
VA was eluted and could not be applied. However, the results of filtration using the filter material of the present invention composed of B+D showed that both the filtration effect and the stability of the filtration layer were good.
The weight loss was less than 1.0%, and almost no elution of PVA was observed. Since the filter material of the present invention is composed of pulverized fibers and fine powder mainly composed of PVA, the stability of the filter layer a is excellent, and the filtering effect is also close to that of a conventional asbestos layer.

Moreover, since PVA is easy to incinerate, it is easy to dispose of waste unlike conventional asbestos, and since it does not cause any harm to the human body, it can be used for food and drink, especially alcoholic solutions for beverages.
It is very useful for filtration. Next, the present invention will be explained in more detail with reference to Examples.

Example 1 After spinning in a Na0H bath, it was dried and heat-treated by a conventional method to obtain a vinylon fiber with a degree of glyoxalation of 20n101% and a fineness of 3.5 denier, which was thoroughly washed and purified with warm water to a size of 30 to 5 denier.
It was ground to 0.00 microns.

Next, the pulverized fibers were dispersed in a 20% ethyl alcohol solution, which was circulated and pre-coated on a filter cloth in a filter to form a powder layer. In addition, PVA fine powder with 80% by weight or less of 200 mesh or less was added.
One powder was heat-treated at 00° C., dispersed in a 20% ethyl alcohol solution, and precoated on the previously formed precoat layer of the crushed vinylon material to form a filtration layer.
Next, activated carbon containing about 5% of fine particles with a particle size of 40μ or less is dispersed in a 20% ethyl alcohol solution to sufficiently adsorb organic amino acids, and then this alcohol solution is filtered through the filtration layer formed earlier. A sample was taken for each amount of filtrate flowing out, and the absorbance of activated carbon flowing into the filtrate was measured using a spectrophotometer to determine the filtration effect.

The results are shown in Table 2. It is clear from Table 2 that an excellent filtration effect can be obtained when an aqueous ethyl alcohol solution is filtered using the filter material of the present invention. Example 2 After spinning in a Na0H bath, it was dried and heat-treated by a conventional method to obtain a vinylon fiber having a degree of formalization of 30rT101% and a fineness of 3.0 denier, which was purified and ground in the same manner as in Example 1.

This pulverized product (20 to 300p) was pre-coated under the same*8 conditions as in Example 1, and the filtration effect was evaluated using the same PVA fine powder treated at 200°C as in Example 1. The results are shown in Table 2.

It is clear from Table 2 that similar to Example 1, excellent filtration effects were exhibited. Fiber pulverized product and PVA used here
The fine powder had good dispersibility in a 20% ethyl alcohol solution and was easy to form the filter medium of the present invention.
When pulverized fibers of 1200 microns were used, the pulverized fibers formed blocks at the time of dispersion, and uniform dispersion could not be obtained, so that the fibers could not be used in the present invention.

Example 3 After Na0H bath spinning, drying and heat treatment were carried out by a conventional method,
Vinylon fibers having a degree of formalization of 33m01% and a fineness of 5.0 denier were purified and crushed in the same manner as in Example 1.

Further, a heat-treated product of PVA fine powder as a fine particle component was also pre-coated using the same PVA as in Example 1, and the filtration effect was evaluated in the same manner as in Example 1. The results showed an excellent filtration effect as shown in Table 2. Table 2 shows similarly compared values for conventionally used asbestos.

Claims (1)

[Scope of Claims] 1 A layer consisting of pulverized fibers obtained by pulverizing polyvinyl alcohol (hereinafter abbreviated as PVA) synthetic fibers of 1.0 to 20 deniers into particles of several tens to hundreds of microns. A filter material filled with insolubilized PVA fine powder of ~ several tens of microns. 2 P
The filter material according to claim 1, wherein the VA-based synthetic fiber is an alkali-spun fiber. 3. The filtration material according to claim 1, wherein the pulverized fibers have been subjected to an insolubilization treatment after being pulverized. 4. The filter material according to claim 1, 2, or 3, wherein the insolubilized PVA fine powder is heat-treated. 5 Dozens of PVA synthetic fibers of 1.0 to 20 denier
It is characterized by filtering out fine particulate components in a solution using a filter material made of a layer made of pulverized fibers pulverized to several hundred microns and filled with insolubilized PVA fine powder with a particle size of several microns to several tens of microns. filtration method. 6. The filtration method according to claim 5, wherein the filtration material is obtained by precoating the surface of the filter cloth with PVA-based synthetic fiber powder and then precoating the insolubilized PVA fine powder. 7. The filtration method according to claim 5 or 6, wherein the PVA-based synthetic fiber is an alkali-spun fiber. 8. The filtration method according to claim 5, 6 or 7, wherein the insolubilized PVA fine powder is heat-treated. 9. Claims 5 and 6, wherein the solution is an alcoholic solution for drinking, and the particulate component is mainly activated carbon particulates.
The filtration method according to item 7, item 8, or item 8.