Chemistry: molecular biology and microbiology – Micro-organism – tissue cell culture or enzyme using process... – Preparing alpha or beta amino acid or substituted amino acid...
Reexamination Certificate
1999-07-23
2001-10-09
Naff, David M. (Department: 1651)
Chemistry: molecular biology and microbiology
Micro-organism, tissue cell culture or enzyme using process...
Preparing alpha or beta amino acid or substituted amino acid...
C435S106000, C435S128000, C435S178000, C435S180000, C435S849000, C435S876000, C528S328000
Reexamination Certificate
active
06300105
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method for the production of a succinimide type polymer and an aspartic acid type polymer.
2. Description of the Related Art:
A succinimide type polymer, when hydrolyzed, gives rise to a corresponding succinimide type polymers which are useful as detergent additives, dispersion stabilizers, scale preventing agents, humectants, and fertilizers.
As means to obtain polysuccinimide by thermal polymerization of aspartic acid as the raw material, various methods have been heretofore proposed.
German Patent publication DE4429108 A1 discloses a method for effecting polymerization of aspartic acid by vacuum concentrating the ammonium salt solution of aspartic acid and further heating the resultant concentrate.
According to this method, the yield of polysuccinimide is 30% when the polymerization temperature is 180° C. and the polymerization time is 4 hours. To heighten the polymer yield, this method requires the polymerization temperature to rise to 220° C. Further, the polyaspartic acid that has been obtained by this method has the problem of deficiency in biodegradability.
EP 0 705 794 A2 discloses a method for polymerizing aspartic acid in the presence of an acid catalyst. This method uses an acid form aspartic acid as the raw material. Since aspartic acid is generally produced in the form of a solution, the method requires separating the acid form aspartic acid in advance from the solution prior to the actual use of the aspartic acid. This extra treatment of separation has formed a cause for heightening the cost of production.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an efficient method for the production of a succinimide type polymer excelling in biodegradability.
Another object of the present invention is to provide an efficient method for the production of an aspartic acid type polymer by the use of a succinimide type polymer.
According to the present invention, it can provide a method for the production of a succinimide type polymer, which comprises thermally polymerizing an ammonium salt of amino acids having aspartic acid as an essential component thereof in the presence of an acid catalyst.
According to the present invention, it can provide a method for the production of an aspartic acid type polymer, which comprises hydrolysing the produced succinimide type polymer by causing the polymer to contact a basic substance.
According to the present invention, it can provide a method for the production of a succinimide type polymer by the polymerization treatment of a solution of an ammonium salt of amino acid containing aspartic acid as an essential component thereof, which method comprises reclaiming the ammonia liberated during the polymerization as the raw material for L-aspartic acid.
This invention further concerns a method for the production of an aspartic acid type polymer, which comprises hydrolysing the produced succinimide type polymer by causing the polymer to contact a basic substance.
Since this method uses an acid catalyst, it can lower the polymerization temperature and shortens the polymerization time. It, therefore, offers the advantage that the polyaspartic acid type polymer derived from the resultant polysuccinimide type polymer has high biodegradability. Further, the ammonia liberated during the process of polymerization can be recovered and reclaimed as the raw material for L-aspartic acid. Particularly, when this liberated ammonia is collected with a suspension of fumaric acid, i.e. the raw material for the L-aspartic acid, the ammonia so collected can be advantageously used as the raw material for the L-aspartic acid.
When the acid catalyst is added to the ammonium salt solution of L-aspartic acid, the effect as acid of this catalyst is ceases to exist because counter ions are generally linked to an acid of high acid strength. Ammonium sulfate is formed as by sulfuric acid and it is not decomposed unless the temperature is higher than 280° C. Thus, the sulfuric acid catalyst ceases to function as an acid catalyst. It has been unexpectedly found that, when a comparatively weak acid such as phosphoric acid or boric acid is used, the resultant ammonium salt of the acid exhibits a comparatively low decomposition temperature, as evinced by the fact that ammonium phosphate decomposes at 190° C. to form free phosphoric acid and consequently enables the decomposed phosphoric acid to retain the catalytic function. Boric acid can be similarly utilized as a catalyst. By the addition of acid catalyst to the ammonium salt solution of aspartic acid, the polysuccinimide of a high molecular weight can be efficiently produced even at a low application rate of the acid catalyst because this addition enables the acid catalyst to be dissolved and dispersed homogeneously throughout the entire volume of the solution.
REFERENCES:
patent: 5541090 (1996-07-01), Sakano et al.
patent: 5688904 (1997-11-01), Wood et al.
patent: 44 29 108 A1 (1996-02-01), None
patent: 0 705 794 A2 (1996-04-01), None
patent: 0 902 010 A1 (1999-03-01), None
patent: 08-302009 (1996-11-01), None
patent: WO 98/30712 (1998-07-01), None
Mukouyama Masaharu
Yasuda Shinzo
Fish & Richardson P.C.
Naff David M.
Nippon Shokubai Co. , Ltd.
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