Process for preparing methylhydroxyalkylcellulose having a small number of coloured particles

• US 8,197,699 B2
• Filed: 09/15/2006
• Issued: 06/12/2012
• Est. Priority Date: 09/17/2005
• Status: Expired due to Fees

• Current Assignee: Dow Global Technologies LLC (Dow, Inc.)
• Original Assignee: Dow Global Technologies LLC (Dow, Inc.)
• Inventors: Kowollik, Martin, Dannhorn, Wolfgang, Klohr, Erik-Andreas, Schlesiger, Hartwig, Kranz, Bernhard, Holste, Helmut, Sonnenberg, Gerd
• Primary Examiner(s): POPOVICS, ROBERT J
• Application Number:
  US11/522,218
• Publication Number:
  US 20070210014A1
• Time in Patent Office: 2,097 Days
• Field of Search: None
• US Class Current: 210/784
• CPC Class Codes: B01D 33/06 with rotary cylindrical filtering surfaces, e.g. hollow drums B01D33/044 takes precedence ; rotating drums for paper-making D21B
• CPC Class Codes: B01D 33/073 arranged for inward flow filtration
• CPC Class Codes: C08B 11/193 Mixed ethers, i.e. ethers with two or more different etherifying groups
• CPC Class Codes: C08B 11/20 Post-etherification treatments of chemical or physical type, e.g. mixed etherification in two steps, including purification
• CPC Class Codes: C08B 11/22 Isolation

Abstract

The present invention describes a process for preparing methylhydroxyalkylcellulose having a small number of colored particles by separation of methylhydroxyalkylcellulose from aqueous suspension with subsequent washing of the methylhydroxyalkylcellulose using a specially equipped rotary pressure filter.

Claims

1. A process for preparing methyl hydroxyalkylcellulose comprising the steps of:

providing a rotary pressure filter including at least one drying zone, said filter comprising;

at least one heat-resistant, abrasion-resistant plastic separation plate sealing the drying zone(s), said separation plate being made of polyether ether ketone; and

at least one additional separation plate which seals off zones other than the drying zone(s) is made of polyvinylidene fluoride;

introducing an aqueous suspension containing methylhydroxyalkylcellulose into said rotary pressure filter; and

separating said methylhydroxyalkylcellulose from said aqueous suspension using said rotary pressure filter to obtain a concentrated methylhydroxyalkylcellulose stream.

2. The process according to claim 1, wherein the methylhydroxyalkylcellulose is a methylhydroxyethylcellulose (MHEC) or a methylhydroxypropylcellulose (MHPC).

3. The process according to claim 1, wherein the methylhydroxyalkylcellulose is a methylhydroxypropylcellulose (MHPC) which has a proportion by mass of hydroxypropoxy groups of from 3.0 to 35.0% and a proportion by mass of methoxyl groups of from 15.0 to 35.0.

4. The process according to claim 1, wherein the methylhydroxyalkylcellulose is a methylhydroxypropylcellulose (MHPC) which has a proportion by mass of hydroxypropoxy groups of from 4.0 to 32.0% and a proportion by mass of methoxyl groups of from 16.5 to 30.0%.

5. The process according to claim 1, wherein the methylhydroxyalkylcellulose is a methylhydroxyethylcellulose (MHEC) which has a degree of substitution MS (HE) of from 0.10 to 1.00 and a degree of substitution DS (M) of from 1.25 to 2.20.

6. The process according to claim 1, wherein the methylhydroxyalkylcellulose is a methylhydroxyethylcellulose (MHEC) which has a degree of substitution MS (HE) of from 0.15 to 0.80, and a degree of substitution DS (M) of from 1.40 to 2.00.