JP5233067B2 - Method for separating water-soluble cellulose ether - Google Patents

Description

  The present invention relates to a water-soluble cellulose ether suspended in water, particularly a water-soluble cellulose ether having excellent plasticity and a high dissolution temperature, as a filter cake by pressure filtration. It is related with the method of separating.

  Here, the water-soluble cellulose ether is usually dispersed in hot water, and as it is cooled, the water-soluble cellulose ether gradually dissolves in water, and the viscosity of the water-soluble cellulose ether solution increases proportionally. However, at a certain temperature, the rate of increase in viscosity becomes moderate. In this case, when 1% by mass of water-soluble cellulose ether is dispersed in hot water at 95 ° C. or higher, and the expression of viscosity is measured while cooling. (The temperature at which the increase in viscosity gradually changes) is referred to as the melting temperature.

  Methyl cellulose is obtained by etherifying alkali cellulose with methyl chloride at a temperature of about 50 to 90 ° C., for example, as described in Examples of Patent Document 1: Japanese Patent Publication No. 7-119241. In this case, after the etherification reaction, the resulting reaction mixture is transferred to a stirring vessel containing water of about 95 ° C., and the salt generated during the reaction is dissolved in the stirring vessel, and then the desired purified cellulose ether is obtained. The suspension coming out of the stirring vessel is subjected to a separation operation.

  In this separation operation, the use of a pressure rotary filter has been studied. However, a normal fiber product filter membrane for a pressure rotary filter has a product in the filter even in a product having a high dissolution temperature. It enters and clogs, and it cannot be used in a short filtration time. When this clogging is to be washed with high-pressure steam or heated water, there is a problem that the mesh is spread or damaged in a normal mesh filter. Therefore, Patent Document 2: Japanese Patent No. 2895084 proposes to increase the strength of the filter as a multilayered sintered structure of metal. However, because of the multilayer structure, there is a problem that once the product is clogged in the filter, it is difficult to remove the clogged product easily by washing.

Japanese Patent Publication No.7-119241 Japanese Patent No. 2895084

  The present invention has been made in view of the above circumstances, and avoids clogging during the separation of water-soluble cellulose ether from a water-soluble cellulose ether suspension, and makes the separation device effective for a long time. It is an object of the present invention to provide a method for separating water-soluble cellulose ether which can be performed.

  As a result of intensive studies to achieve the above-mentioned object, the present inventor uses a perforated metal or ceramic as a filter medium, and after filtration, the filter medium is substantially washed with steam, compressed air, or pressurized water. Water-soluble cellulose ether can be separated without any problems, and not only the high useful life of the separation device is maintained, but also the filter medium is not clogged by washing the filter medium after filtration and remains in the filter medium. Since the water-soluble cellulose ether is washed out, it has been found that the loss of the water-soluble cellulose ether is eliminated, and the present invention has been made.

Accordingly, the present invention provides the following water-soluble cellulose ether separation method.
[Claim 1]
The suspension of water-soluble cellulose ether is filtered with a pressure filter using a metal or ceramic plate-shaped single-layer filter medium perforated by an electron beam, and after removing the water-soluble cellulose ether filter cake, the filter medium is vaporized. A method for separating water-soluble cellulose ether from a suspension of water-soluble cellulose ether, characterized by washing with either compressed air or pressurized water.
[Claim 2]
The method for separating a water-soluble cellulose ether according to claim 1, wherein a filter medium whose perforation size substantially corresponds to the average particle diameter of the suspended particles is used.
[Claim 3]
The method for separating a water-soluble cellulose ether according to claim 1 or 2, wherein a perforated filter medium made of special steel having nickel of 8 mass% or more and chromium of 18 mass% or more is used.
[Claim 4]
The concentration ratio of water-soluble cellulose ether / water is a suspension of water-soluble cellulose ether having a mass ratio of 10/100 to 50/100, according to any one of claims 1 to 3. A method for separating water-soluble cellulose ether.
[Claim 5]
After filtration, the filter cake is washed with hot water and / or steam, and then removed from the filter medium by reverse injection of steam, compressed air, or pressurized water from the perforated filter medium before removing the filter cake. The method for separating a water-soluble cellulose ether according to any one of claims 1 to 4.
[Claim 6]
6. The method for separating water-soluble cellulose ether according to claim 5, wherein after the filter cake is separated and removed from the filter medium, the filter medium is rinsed with pressurized water from a spray nozzle, and the generated wash water is returned to the filter cake wash water. .
[Claim 7]
The method for separating a water-soluble cellulose ether according to any one of claims 1 to 6, wherein the water-soluble cellulose ether is alkyl cellulose, hydroxyalkyl alkyl cellulose, or hydroxyalkyl cellulose.
[Claim 8]
The water-soluble cellulose according to any one of claims 1 to 7, wherein an average particle diameter of the water-soluble cellulose ether suspended particles in the suspension is 0.1 to 2,000 µm in a measurement method by a sieving method. Separation method of ether.
[Claim 9]
The method for separating a water-soluble cellulose ether according to any one of claims 1 to 8, wherein the temperature of the suspension is 20 to 160 ° C.
[Claim 10]
The method for separating a water-soluble cellulose ether according to any one of claims 1 to 9, wherein the filter medium has a thickness of 0.2 to 20 mm.

  According to the present invention, a water-soluble cellulose ether, particularly a water-soluble cellulose ether having a high dissolution temperature, is separated from the suspension of the water-soluble cellulose ether, and at this time, the clogging of the filtering device is avoided and the filtering device is used. It becomes possible to have effectiveness for a long time.

  The filter medium in the method for separating a water-soluble cellulose ether of the present invention is a perforated metal or ceramic.

  It is preferable to use a filter medium whose perforation size of the filter medium of the present invention substantially corresponds to the average particle diameter of suspended particles of water-soluble cellulose ether. That is, such a filter medium can reliably capture even fine particles having a particle size smaller than the perforation size of the filter medium.

  In this case, as the metal material, a special steel having high corrosion resistance, particularly a special steel containing 5% by mass or more of nonferrous metal can be used to prevent corrosion. For example, those which are resistant to the salt contained in the water-soluble cellulose ether suspension and the washing liquid of the filter cake are preferable. Particularly, special steel having nickel of 8% by mass or more and chromium of 18% by mass or more is used as a perforated filter medium. It is preferable to use it. By using these materials, the occurrence of stress cracking corrosion due to the high salt content of the hot suspension is prevented.

  These drilling materials are: Takao Terabayashi, Kenichiro Hagio; Research on electron beam processing, Journal of Precision Engineering, Vol. 53, No. 5 (1987), p789-794, Kenichiro Hagio; 37, No. 8, p47-52 and the like.

  As the ceramic material, an oxide or non-oxide type ceramic material is preferable as a material exhibiting salt resistance, and ceramic materials such as alumina, magnesia, zirconia, and ferrite, as well as silicon carbide and silicon nitride are used. Is particularly preferred.

  The thickness of the filter medium is preferably 0.2 to 20 mm, particularly 2 to 10 mm.

Examples of the water-soluble cellulose ether of the present invention include alkyl cellulose, hydroxyalkyl cellulose, and hydroxyalkylalkyl cellulose having a dissolution temperature of 20 ° C. or higher.
Examples of the alkyl cellulose include methyl cellulose having a methoxyl group (DS) of 1.0 to 2.2, ethyl cellulose having an ethoxyl group (DS) of 2.0 to 2.6, and the like.
Examples of the hydroxyalkyl cellulose include hydroxypropyl cellulose having a hydroxy propoxyl group (MS) of 0.05 to 3.3.
Examples of the hydroxyalkylalkyl cellulose include hydroxyethyl methylcellulose having a methoxyl group (DS) of 1.0 to 2.2 and a hydroxyethoxyl group (MS) of 0.1 to 0.6, and a methoxyl group (DS) of 1. 0 to 2.2, hydroxypropylmethylcellulose having a hydroxypropoxyl group (MS) of 0.1 to 0.6, ethoxyl group (DS) of 1.0 to 2.2, and hydroxyethoxyl group (MS) of 0.1 -0.6 hydroxyethyl ethyl cellulose is mentioned, Hydroxy ethyl methyl cellulose and hydroxypropyl methyl cellulose having a particularly high dissolution temperature (30 to 60 ° C.) are preferred.

  In order to achieve a high yield of water-soluble cellulose ether after filtration, a high-concentration water-soluble cellulose ether suspension with a water-soluble cellulose ether / water concentration ratio of 10/100 to 50/100 is used. It is preferable to do this. In doing so, the suspension used must be pumpable.

  In this case, the average particle diameter of the water-soluble cellulose ether suspended particles in the suspension is preferably 0.1 to 2,000 μm in the measuring method by the sieving method.

  In the present invention, when a suspension of water-soluble cellulose ether is filtered with a pressure filter using a perforated metal or ceramic as a filter medium, the temperature of the suspension to be filtered is 20 to 160 ° C., particularly 70 to 140. C. is preferably from the viewpoints of economy, material protection, and cellulose ether dissolution prevention. This suspension is usually sodium chloride or other salt in the reaction mixture (water-soluble cellulose ether, water, sodium chloride or other salt, organic matter) after the etherification reaction in the production of water-soluble cellulose ether. What contains about 30 mass% can be used for filtration.

  Furthermore, when pressure filtration is performed, the degree of pressurization is appropriately selected, but a pressure of usually about 0.001 to 1 MPa, particularly about 0.01 to 0.5 MPa is preferable.

  In the present invention, after the filtration, the filter cake of the water-soluble cellulose ether is removed, and then the filter medium is washed with steam, compressed air, pressurized water, or hot water.

  Here, in the present invention, it is preferable to use steam having a temperature of 100 to 185 ° C., particularly 100 to 160 ° C., and a pressure of 0.001 to 1 MPa, particularly 0.01 to 0.5 MPa. Moreover, it is preferable to use compressed air having a pressure of 0.001 to 1 MPa, particularly 0.01 to 0.5 MPa, and a temperature of 10 to 160 ° C., particularly 20 to 140 ° C. The pressurized water is preferably 10 to 160 ° C., more preferably 20 to 140 ° C., and a pressure of 0.001 to 15 MPa. The hot water is preferably 50 to 160 ° C., particularly 70 to 140 ° C., and the pressure is 0.001 to 3 MPa.

  In this case, according to the present invention, the filter cake is washed with hot water and / or steam after filtration, and then removed by reverse injection of steam, compressed air, or pressurized water from the perforated filter medium side before removing the filter cake. Is removed from the filter medium. As a result, foreign matters such as salts are washed out from the filter cake, and therefore the filter cake is configured in a form in which foreign matters such as salts are substantially removed from the water-soluble cellulose ether.

  As a particularly advantageous embodiment of the invention, after removing the filter cake from the filter media, using a flat spray nozzle, at least 1 MPa, preferably 1.5-2 MPa, with 90-212 ° C. pressurized water in the filtrate direction. Rinse the perforated filter media. At this time, when the generated rinse water is returned to the filter cake washing water (that is, the above-mentioned pressurized water or water vapor used for washing the cake), it becomes an aqueous solution containing salts to lower the dissolution temperature of the product having a high dissolution temperature. It is possible to prevent clogging due to dissolution during cleaning. Further, at the same time that the filter medium is washed by this method, valuable products still remaining in the filter medium can be recovered and returned to this process again, which is very effective in improving the yield.

  In the present invention, a suspension of water-soluble cellulose ether is filtered with a pressure filter using a metal or ceramic perforated filter medium. The pressure filter is shown in FIG. 1 of Japanese Patent No. 2895084. The filtration operation can be performed by the same process as shown in FIG. 3 except that the filter medium is different using the pressure rotating filter as described.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the following examples. Note that a rotary pressure filter manufactured by BHS, Germany, as described in Japanese Patent No. 2895084 was used as the pressure rotation type filter.

[Example 1]
Mixing hydroxyethylmethylcellulose (methoxyl group (DS) 1.46, hydroxyethyl group (MS) 0.32, dissolution temperature 55 ° C.), which is a reaction mixture after the etherification reaction, with a considerable amount of 95 ° C. boiling water. Thus, a suspension of 12 parts by mass of hydroxyethyl methylcellulose (HEMC) / 100 parts by mass of water was obtained. The concentration of salt (mainly sodium chloride) in this suspension was 6% by mass.

This suspension (95 ° C.) was added to a pressure rotating filter (filter area 1 m ² , drum rotation 1 minute per minute) preheated to 100 ° C. with a pump pressure of 0.2 MPa.
The filter used was a filter with holes made by Taiheiyo Special Casting Co., Ltd. (hole diameter: 0.07 mm diameter, plate thickness: 0.3 mm, distance between holes in the same direction as the filter rotation (hole pitch): 0) .30 mm, spacing between holes perpendicular to the filter rotation (row pitch): 0.26 mm, material: SUS304).

A filter cake with a thickness of 20 mm solidified on the surface of the filter was formed, and steam of 134 ° C. and 0.2 MPa was strongly blown onto it.
Before separating the filter cake, wash with hot water at 95 ° C and 0.2 MPa in the filtrate direction, blow with compressed air at 20 ° C and 0.5 MPa in the reverse direction, loosen (unravel) the filter cake, and then scrape The filter cake was removed from the filter surface with a take-off machine.
After removing the filter cake, the laminate adhering to the perforated filter medium was sufficiently washed by spraying pressurized water of at least 90 ° C. and 1 MPa, preferably 1.5 to 2 MPa, with a flat spray nozzle.
After drying the filter cake at 100 ° C. for 3 hours, the residual salt content in the filter cake was measured according to the measurement method of the ignition residue described in the 14th revised Japanese pharmacopoeia hydroxypropylmethylcellulose, It was 0.1 mass% with respect to dry hydroxypropyl methylcellulose.

  Using pressurized water at 90 ° C. used for washing the laminate adhering to the perforated filter medium obtained by the above operation as a washing liquid for the filter cake, the efficiency was repeated in the same manner as much as possible. No decrease in the flow rate through the filter was observed.

[Example 2]
Hydroxypropyl methylcellulose (methoxyl group (DS) 1.50, hydroxypropoxyl group (MS) 0.20, dissolution temperature 40 ° C.), which is a reaction mixture after the ether reaction, is mixed with a considerable amount of 95 ° C. boiling water. Thus, a suspension of 50 parts by mass of hydroxypropyl methylcellulose (HPMC) / 100 parts by mass of water was obtained. The salt concentration in this suspension was 25% by mass.

  Except for the filter perforated with zirconia ceramic to the same thickness, the same treatment as in Example 1 was performed. After removing the filter cake, the filter adhered to the perforated filter medium by spraying pressurized water at 90 ° C. and 10 MPa from a flat spray nozzle. The laminated laminate was washed.

After the filter cake was dried at 100 ° C. for 3 hours, the ignition residue was measured by the method described in the 14th revised Japanese pharmacopoeia hydroxypropylmethylcellulose. %Met. No long-term decrease in the flow rate through the filter was observed.
The viscosity of a 2% by mass aqueous solution at 20 ° C. according to the method for measuring the viscosity of HPMC2208 described in the US Pharmacopoeia of the obtained hydroxypropylmethylcellulose was 4,000 mPa · s.

In addition, this operation process can be similarly implemented in a pressure filtration nutse that operates discontinuously.

Claims (10)

The suspension of water-soluble cellulose ether is filtered with a pressure filter using a metal or ceramic plate-shaped single-layer filter medium perforated by an electron beam, and after removing the water-soluble cellulose ether filter cake, the filter medium is vaporized. A method for separating water-soluble cellulose ether from a suspension of water-soluble cellulose ether, characterized by washing with either compressed air or pressurized water.   The method for separating a water-soluble cellulose ether according to claim 1, wherein a filter medium whose perforation size substantially corresponds to the average particle diameter of the suspended particles is used.   The method for separating a water-soluble cellulose ether according to claim 1 or 2, wherein a perforated filter medium made of special steel having nickel of 8 mass% or more and chromium of 18 mass% or more is used.   The concentration ratio of water-soluble cellulose ether / water is a suspension of water-soluble cellulose ether having a mass ratio of 10/100 to 50/100, according to any one of claims 1 to 3. A method for separating water-soluble cellulose ether.   After filtration, wash the filter cake with hot water and / or steam, and then remove the filter cake from the filter medium by reverse injection of steam, compressed air, or pressurized water from the perforated filter medium side before removing the filter cake. The method for separating a water-soluble cellulose ether according to any one of claims 1 to 4.   6. The method for separating water-soluble cellulose ether according to claim 5, wherein after the filter cake is separated and removed from the filter medium, the filter medium is rinsed with pressurized water from a spray nozzle, and the generated wash water is returned to the filter cake wash water. .   The method for separating a water-soluble cellulose ether according to any one of claims 1 to 6, wherein the water-soluble cellulose ether is alkyl cellulose, hydroxyalkyl alkyl cellulose, or hydroxyalkyl cellulose. The water-soluble cellulose according to any one of claims 1 to 7, wherein an average particle diameter of the water-soluble cellulose ether suspended particles in the suspension is 0.1 to 2,000 µm in a measurement method by a sieving method. Separation method of ether. The method for separating a water-soluble cellulose ether according to any one of claims 1 to 8, wherein the temperature of the suspension is 20 to 160 ° C. The method for separating a water-soluble cellulose ether according to any one of claims 1 to 9, wherein the filter medium has a thickness of 0.2 to 20 mm.