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MX2007004632A - Method for shaping cellulose ethers - Google Patents

Method for shaping cellulose ethers

Info

Publication number
MX2007004632A
MX2007004632A MX/A/2007/004632A MX2007004632A MX2007004632A MX 2007004632 A MX2007004632 A MX 2007004632A MX 2007004632 A MX2007004632 A MX 2007004632A MX 2007004632 A MX2007004632 A MX 2007004632A
Authority
MX
Mexico
Prior art keywords
cellulose
process according
cellulose ethers
perforations
hydroxyethyl
Prior art date
Application number
MX/A/2007/004632A
Other languages
Spanish (es)
Inventor
Thielking Heiko
Oliver Schmidt Marc
Hild Alexandra
Altmann Axel
Langer Benedikt
Oppermann Wilhelm
Schriewer Bernd
Original Assignee
Wolff Cellulosics Gmbh & Co Kg
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Wolff Cellulosics Gmbh & Co Kg filed Critical Wolff Cellulosics Gmbh & Co Kg
Publication of MX2007004632A publication Critical patent/MX2007004632A/en

Links

Abstract

The invention relates to a method for producing cellulose ethers which have, compared to know cellulose ethers, a higher bulk density and a more even particle size distribution. Said method consists of pressing the cellulose ethers through a perforated plate.

Description

PROCESS TO CONFORM CELLULOSE ETERES Description of the Invention The present invention relates to a process for the manufacture of cellulose ethers having a higher bulk density and a narrower particle size distribution than known cellulose ethers, when pressed through a disk Perforated. In the production of cellulose ethers, the forming step represents an important step in the process to influence the properties of the product. In particular, inventive properties such as the classification curve and bulk density are influenced in this step. This step of the process is usually done after washing the product and before drying it and classifying it. According to the state of the art, the shaping is carried out by cumulative agglomeration in horizontal vibrating mixers, by means of which the wet product agglomerates, compacts and compresses (cf., for example, DE 20 28 310, DE 33 08 420 Al). The particular disadvantages of this technology are the dependence of cumulative agglomeration on residence time in the mixer, which necessarily is related to the dimensions of the granulator, and the limited possibility of introducing energy. Dividing the REF. §181307 residence time originates a non-uniform product. The agglomerates are only united freely, thus the disintegration quickly occurs. This gives a substantial increase in the proportions of the very fine powder, which is undesirable for certain grades. The capacity of the intensive properties of mass density and the classification curve to be influenced are limited by this. Therefore the objective is to provide a process by which the fibrous product after washing is formed into highly compressed compact particles (pellets) so that the bulk density increases and only a few granules, if any, with A classification curve below the desired particle size will be formed in the subsequent grinding process. In addition, the granules formed should be as uniform as possible. In addition, other properties of the products must remain unaffected. It has now been found, surprisingly, that this objective is achieved by means of a process comprising pressing the cellulose ethers through a perforated disc. In one embodiment of the invention, the cellulose ether is fed into a device comprising a vertical axis. Attached to the shaft is a disk having perforations with a defined diameter-to-length ratio.
Rotating on this disc are rollers (crusher, wheel, roller), which press the cellulose ether into the perforations and force it through them. Below the disk the cellulose ether is separated by rotary separators and divided into small compact particles. In another embodiment of the invention, the cellulose ether is pressed through the perforations in a die of a flat die press (also called mill wheel), where the rotary mills (wheels) run on a perforated die ( disco). Below this the shearing device cuts the compacted particles to the desired length. At least one shredder runs in the grinding mill. It is conventional to have two shredders, but it can also be more than two. This depends on the size of the unit and the diameter of the shredders. However, another possibility is that, in a perforated, straight die, a wheel (roller, shredder) presses the cellulose ether through the die while moving from one side to the other, by means of this it presses it. The cellulose ether is compressed as it passes through the perforations. The degree of compression can be adjusted via the geometry of the perforations. This regulates the energy needed for the compression process. The shape of the cross section of the shaped bodies is determined by the shape of the cross section of the perforation.
In the case of circular perforations, the consistency of the compressed cellulose ether depends on the compression ratio P. P is defined as the ratio of the length of the perforation to the diameter of the perforation in the die. The compression ratio P must be between 0. 5 and 5 0, preferably between 2 and 4. 0 The perforations can also have a cross-section of square, rectangular, oval or irregular shape. The number of perforations per unit area of the disc depends on the stability of the disc. Examples of suitable cellulose ethers for carrying out the process according to the invention are ionic and nonionic cellulose ethers. Examples of ionic cellulose ethers which may be mentioned are carboxymethyl cellulose, hydroxyethyl carboxymethyl cellulose, carboxymethyl sulfoethyl cellulose and sulfoethyl cellulose, preferably carboxymethyl cellulose. Examples of nonionic cellulose ethers which may be mentioned are hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, ethyl hydroxyethyl cellulose and methyl cellulose, preferably hydroxyethyl methyl cellulose and hydroxypropyl methyl cellulose. The cellulose ethers compressed by the process according to the invention have a high bulk density and form more stable granules than the cellulose esters treated according to the state of the art, other properties are the same. Also, the particle size distribution is more uniform, characterized by a correlation coefficient K between the sieve size [mm] and the distribution function [%] of approximately 1.0 (ie, a practically linear relationship). Mass densities for the commercially valuable cellulose ethers compressed by the process according to the invention are from 400 g / 1 to 800 g / 1. The typical particle size distributions of cellulose esters are from 125 μ? at 1000 um with an average particle size of 500 μp. The non-compressed material is introduced into a grinding mill via a measuring device (eg, screw, tape). It is also possible to provide the grinding mill with an inert, e.g., with nitrogen or carbon dioxide. The following examples describe the process according to the invention, but without imposing a limitation.
EXAMPLES Comparative example (preparation according to the state of the art): The product CMC CRT 40000 (substitution degree (DS) of 0.9, moisture content of the product 42%, viscosity of a 2% aqueous solution 40,000 mP.s ) is introduced as the fibrous raw material, free of alcohol into a horizontal mixer and continuously granulated. The obtained granules were dried in a batch device and then milled to the required fineness in an impact basket screen sprayer. The product is screened above 1 mm. Bulk density 621 g / 1; proportion below 0.125 mm: 18% by weight; K = 0.979.
Example 1 (according to the invention): Instead of using a horizontal mixer, the product CMC CRT 40000 (moisture content of the product 42%) was granulated by compression by the process according to the invention (6 mm perforation; P = 4) and dried and ground as described above. Bulk density 711 g / 1; proportion below 0.125 mm: 14% by weight; K = 0.995.
Example 2 (according to the invention): Instead of using a horizontal mixer, the product CMC CRT 10000 (moisture content of the product 40%, viscosity of a 2% aqueous solution of 10,000 mP.s) was granulated by compression by the process according to the invention (6 mm perforation; P = 3) and dried and milled as described above.
Bulk density 680 g / 1; proportion below 0.125 mm: 12% by weight; K = 0.999. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (9)

  1. Claims Having described the invention as above, the content of the following claims is claimed as property. Process for the production of cellulose ethers, characterized in that it comprises pressing them through a perforated disc.
  2. 2. Process according to claim 1, characterized in that the compression ratio P is 0.5 to 5.0.
  3. 3. Process according to claim 1, characterized in that the compression ratio P is 2.0 to 4.0.
  4. Process according to claims 1 to 3, characterized in that the cellulose ether is pressed through the perforations by means of one or more rotary mills.
  5. Process according to claims 1 to 3, characterized in that the cellulose ether is pressed through the perforations by means of one or more oscillating wheels.
  6. 6. Process according to claims 1 to 3, characterized in that the cellulose ether is pressed through the perforations by means of rollers.
  7. Process according to claims 1 to 6, characterized in that the cellulose ether is separated below the disk in pieces of the desired length.
  8. Process according to claims 1 to 6, characterized in that the compressed cellulose ether is selected from carboxymethylcellulose, hydroxyethyl carboxymethylcellulose, carboxymethyl sulfoethyl cellulose, sulfoethyl cellulose, hydroxyethyl methylcellulose, hydroxypropyl methylcellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, ethyl hydroxyethyl cellulose and methyl cellulose
  9. 9. Products, characterized in that they are obtainable by means of the process according to one of claims 1 to 8.
MX/A/2007/004632A 2005-02-03 2007-04-18 Method for shaping cellulose ethers MX2007004632A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE102005004893.5 2005-02-03

Publications (1)

Publication Number Publication Date
MX2007004632A true MX2007004632A (en) 2008-10-03

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