JPS6349212A - Adsorptive filter sheet - Google Patents

Abstract

PURPOSE:To highly efficiently obtain an adsorptive filter capable of clean clarifying filter and sterilizing filter by using cellulose fiber, diatomaceous earth and/or pearlite, and chitosan. CONSTITUTION:Cellulose fiber purified to >=90% alpha-cellulose content is used. One or two kinds of either diatomaceous earth or pearlite are blended with cellulose fiber in a range within 0.25-4 as the weight proportion therefore. The soln. obtained by dissolving about 10wt% chitosan in a dilute acid soln. is added into aq. dispersion liquid of the granular mixed sheet substance of cellulose fiber and diatomaceous earth, etc., while stirring it, or a substance wherein a mixture of cellulose fiber and diatomaceous earth or the like is previously made sheet-like by a method for making sheet is immersed into the chitosan soln. to add chitosan. The amount of chitosan to be added is regulated to about 1-10wt%.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an adsorbent filter sheet used for liquid particle removal, filtration sterilization, etc. The present invention relates to a filter sheet that has adsorption performance by adding chitosan to the mixture.

The filter sheet according to the present invention can be used to remove protein colloid substances that inhibit the stabilization of brewed liquors such as beer, wine, and sake, to remove yeast, to remove particulates from injections and infusions, to sterilize filtration, to remove pyrogen substances, and to food products. It can be advantageously used for filtration in the beverage and pharmaceutical fields.

(Prior Art) As a filter sheet for liquid clarification and sterilization filtration made of a fibrous filter medium, an asbestos-mixed filter sheet having a thickness of about 2 to 5 layers is well known. However, in recent years, since the effects of asbestos on the human body have become a problem, new filter media that are safe for human health as an alternative to asbestos filter media have been disclosed, for example, in Japanese Patent Application Laid-open No. 50-15162 and Japanese Patent Publication No. 55-24928. A filter sheet made by treating a mixture of cellulose fiber, diatomaceous earth, perlite, etc. with a cationic polymer compound to modify the surface charge of the diatomaceous earth, perlite, etc., and giving it adsorption performance for microorganisms such as Orchid orchid. has been put into practical use.

However, the cationic polymer compounds used for these surface modification treatments are chemically synthesized resins such as melamine formalin resin, urea formalin resin, and polyamide shrimp chlorohydrin resin, and are completely polymerized. Although these resins are highly safe for the human body, they must be washed and filtered before use due to problems such as the elution of unreacted oligomers, and there are many unknowns about the effects of these resins on the human body. Ta.

(Problems to be Solved by the Invention) The present invention completely eliminates the drawbacks of the conventional filter sheets as described above, and provides an adsorbent filter sheet that is highly safe for human health and has excellent filtration efficiency. The purpose is to

(Means for Solving the Problems) The gist of the present invention is to provide a liquid clarification and sterile filtration system characterized by comprising at least one or two of cellulose fibers, diatomaceous earth, or perlite, and chitosan. Adsorptive filter sheet for use.

The present invention will be explained in detail below.

Chitosan, which is one of the components constituting the filter sheet of the present invention, is a deacetylated product of naturally obtained chitin, and is a base consisting of glucosamine (2-amino-D-glucose) with a structure similar to cellulose. Polysexual [I
There is no concern about toxicity to the human body, and it biodegrades very quickly, so it is expected to have potential as a medical material.

It is also approved as a natural food additive, and its oral safety has been confirmed.

Furthermore, due to the nature of the intended use, the cellulose fibers that are the constituent components of the filter sheet of the present invention may be made of 990% α-cellulose, such as purified linter pulp or purified bleached wood pulp.
Those purified above are recommended. These cellulose fibers may be used alone or in combination of two or more to adjust the degree of beating, fiber length, and degree of fibrillation.

Diatomaceous earth and perlite, which are mixed as constituent components of the filter sheet of the present invention, are available in various types depending on particle size, but they may be used alone or in combination depending on the required performance of the filter sheet (filtration speed, filtration efficiency, total filtration amount). used. If the degree of pulp adjustment is the same, using a grade of diatomaceous earth or perlite with a finer particle size will narrow the spacing between particles and improve adsorption and trapping performance. In addition, increasing the ratio of diatomaceous earth or perlite to cellulose fibers naturally improves the adsorption capacity of the filter sheet, but when the ratio of cellulose fibers decreases, the mechanical strength of the filter sheet decreases, resulting in lower pressure and pulsation pressure during filtration. It becomes difficult to endure. This is thought to be because the cellulose fibers form the skeleton of granular materials such as diatomaceous earth that are mixed into the paper.

On the other hand, if the blending ratio of granular adsorbent such as diatomaceous earth decreases, the desired adsorption performance cannot be obtained and the performance as an adsorbent filter sheet will not be satisfied. Therefore, the blending ratio of diatomaceous earth and perlite to cellulose fibers should be determined by taking adsorption performance, mechanical strength, etc. into consideration.

Cellulose fiber and either diatomaceous earth or perlite
It is preferable that the weight ratio of the species or two species is within the range of 4=1 to 1:4, but the present invention is not limited to this.

Addition of fuchitosan to cellulose fibers, diatomaceous earth and/or perlite can be achieved by adding chitosan to an aqueous solution of acetic acid, hydrochloric acid, sulfamic acid, or other dilute acids, e.g.
% dissolved solution is added to an aqueous dispersion of prepared mixed granular materials such as cellulose fibers and diatomaceous earth with stirring, or a mixture of cellulose fibers, diatomaceous earth, and/or perlite is added in advance to an appropriate method such as paper making. This can be carried out by impregnating a sheet made into a sheet by the method described above in a chitosan solution.

In the case of the addition method, the aqueous chitosan solution is a cationic electrolyte solution of polymers, so it adsorbs electrically to diatomaceous earth and pearlite, which have anionic charges in the aqueous solution, coating their surfaces and modifying their surface charges. questioned.

The amount of chitosan added is not particularly limited, but
The solid content of chitosan is preferably about 1 to 10% of the total weight of cellulose fibers, diatomaceous earth, and the like.

(Example) The present invention will be specifically explained below using Examples.

Example-1 20 parts of purified cotton linter pulp and 20 parts of purified bleached wood valve were beaten with water using a beater to obtain a beating degree of 5R45.
Adjust to °. To this, 40 parts of diatomaceous earth Celite 577 (manufactured by Manville) and 20 parts of perlite Na34 (manufactured by Tokyo Kogyo Boeki Shokin) were added and mixed well with the pulp.
A solution of 10 w/w % chitosan dissolved in v/v % acetic acid is added as a chitosan solid content of 5 parts to the total weight of pulp, diatomaceous earth, and perlite to prepare a mixed acid papermaking raw material.

Using this papermaking raw material, a 3.5-thick fin,
A filter sheet with a dry weight of 1.200 g/rrf was prepared and dried at 120° C. for 30 minutes to obtain Sample A.

Example-2 Perlite! 1m34 Diatomaceous earth instead of 20 parts,
A filter sheet was prepared in the same manner as in Example 1, except that 20 parts of Standard Super Cell (manpil) was used, and the thickness was 3.51 m and the dry weight was 1240 g.
/nr sample B was obtained.

Example-3 A filter sheet was prepared in the same manner as in Example-1 except that 40 parts of perlite Nn31 (manufactured by Tokyo Kogyo Boeki Shokin) was used instead of 577.40 parts of diatomaceous earth and celite. Sample C with 3.5 cranes and a dry weight of 1150 g/cd was obtained.

Example-4 A filter sheet was prepared in the same manner as in Example-1 except that 12 parts of chitosan was added instead of 5 parts as a solid component, and the thickness was 3.5 nm, dry type 11, 28
A sample of 0 g/rrr was obtained.

Comparative Example-1 A filter sheet was prepared in the same manner as in Example-1 except that 5 parts of chitosan was added instead of not added as a solid content, and the thickness was 3.5 **, dry weight was 1185.
Sample E of g/m was obtained.

The results of the filtration sterilization test for the sample filter sheets A to E are shown in Table 1.

Filtration conditions Effective filtration area (EFA): 113 cIItFlow rate: 0.25 kll/cm2-hr.

Bacterial species: 5errotria marcesce
ns bacteria concentration: 4.3 x 10”cel
ls/m 7! Measurement: Measure the filtrate every 11 fractions up to the 51st papermaking condition: Paper density: 0.5% Degree of vacuum during dehydration: 4QflHg (Effects of the invention) As explained above, according to the present invention, there is no problem in terms of human health. It is possible to obtain a highly efficient and clean adsorbent filter sheet for clarifying filtration and sterilizing filtration without causing any problems.

Claims (2)

[Claims] (1) An adsorbent filter sheet comprising at least one or two of cellulose fibers, diatomaceous earth, or perlite, and chitosan. (2) The adsorptive filter sheet according to claim 1, wherein the weight ratio of cellulose fibers to one or both of diatomaceous earth and perlite is within the range of 4:1 to 1:4.