Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
2001-02-08
2004-08-31
Hightower, P. Hampton (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C528S360000, C528S363000, C528S367000, C528S373000, C528S374000, C525S419000, C525S420000
Reexamination Certificate
active
06784280
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a novel process for the production of a polysuccinimide (co)polymer derivative and a polysuccinimide (co)polymer derivative obtained thereby.
BACKGROUND ART
A polysuccinimide (co)polymer, which has high mechanical strength because of the structure of its main chain, has been expected to be used in the applications where such characteristics are required. In addition, it also has been expected to be served as a precursor for a biodegradable material, because the aspartic main chain resulted from the ring-opening of its imide rings is biodegradable. As typical applications of the polymer, polyaspertic acid to be obtained by the hydrolysis of polysuccinimide may be used in various applications such as a chelating agent, an antiscaling agent, a builder for a cleaning agent, a humectant and an additive for a fertilizer.
The polysuccinimide (co)polymer which has been commonly available at present, however, has a low molecular weight and hence is limited in the scope of applications. There also gives a problem that it may not produce significantly high performance, even though it can be used.
Various processes, therefore, have been attempted in order to obtain a polysuccinimide (co)polymer having a higher molecular weight. For example, the following processes have been heretofore known: a process which comprises subjecting aspartic acid to the polycondensation in the presence of a polymerization catalyst such as phosphoric acid, and sulfuric acid (JP-A-8-239,468), a process which comprises grafting an amino acid onto a polysuccinimide (co)polymer to obtain a polysuccinimide (co)polymer having a high molecular weight (JP-A-9-235,372), a process which comprises using a phosphorous compound in the polycondensation system of a reactant of aspartic acid, maleamic acid, maleic acid and ammonia to obtain a polysuccinimide (co)polymer having a high molecular weight (EP-A-791616), a process which comprises adding a specific amounts of a catalyst and a polymerization promoter to the polymerization system and polymerizing the mixture in a substantially solid state to obtain a polysuccinimide (co)polymer having a high molecular weight (JP-A-9-302,088), and a process which comprises adding a compound having two or more oxazoline structures in its molecule as a chain extender to the polycondensation system of a reactant of aspartic acid, maleamic acid, maleic acid and ammonia to obtain a polysuccinimide (co)polymer having a high molecular weight and polymerizing the mixture to obtain a polysuccinimide (co)polymer having a high molecular weight (JP-A-10-147,644).
All the polymerization (polycondensation) reaction disclosed in the above publications, however, have had either complicated processes or employed expensive catalysts and thus have not been always regarded to be satisfactory as an industrial process.
As mentioned above, a simple process capable of producing a polysuccinimide (co)polymer with a high molecular weight at a low cost has long been earnestly desired but not found to the moment.
A polysuccinimide (co)polymer derivative to be produced by reacting the polysuccinimide (co)polymer obtained as described above with an amino compound has been well-known to be useful as an antiscaling agent, a chelating agent, and a builder for a detergent. One of the characteristics thereof is that it can also been converted into a biodegradable polyaspartic acid derivative as is discussed on the polysuccinimide (co)polymer derivative.
As the typical process for producing such a polysuccinimide (co)polymer derivative, a process which comprises reacting a polysuccinimide (co)polymer in a solid state or a polysuccinimide (co)polymer which has been dissolved in an organic solvent such as dimethylformamide (DMF) and N-methylpyrrolidone with an amino compound (for example, U.S. Pat. No. 5,726,280 and U.S. Pat. No. 5,726,280), and a process which comprises reacting polysuccinimide with an amino acid at a specific pH in an aqueous medium to produce a polysuccinimide (co)polymer derivative (U.S. Pat. No. 5,639,832) have been heretofore reported. According to the former process, however, there have been such a problem as that the reaction of a polysuccinimide (co)polymer in the solid phase brings about a heterogeneous reaction and can not produce a derivative having uniform properties, and that the reaction is heavily exothermic and causes safety problem to the operation. In addition to these problems, as the organic solvent used in the reaction such as dimethylformamide and N-methylpyrrolidone has similar polarity to that of the produced polysuccinimide (co)polymer derivative and has a high boiling point, the isolation and purification after the reaction are extremely difficult, which limits the scope of applications of the product.
In the latter process, a step is indispensable in which a pH value is adjusted so that at least 5% of the non-protonated amino groups of the amino acid is present in the amount equal to those protonated. In this process, an alkali such as sodium hydroxide or ammonia is used as a pH-adjusting agent. The ring-opening modification of an imide ring with the amino group competes with the base of the above- mentioned pH-adjusting agent. In general, since the basicity of an amino acid is lower, such a problem has been generated as that the reaction efficiency of the of polysuccinimide with the amino acid is low, i.e., the yield of the polysuccinimide (co)polymer derivative aimed at is not satisfactory. In addition to these problems, according to the process disclosed in JP-A-8-507,558, there has been also such a drawback as that that the reaction has to be carried out at a temperature within a relatively narrow range as of from 0° to 100° C., because the glass transition point (Tg) of the polysuccinimide (co)polymer is higher than its decomposition point and thus the polysuccinimide (co)polymer is decomposed prior to being molted when heated in order to melt the polysuccinimide (co)polymer.
As described above, there has been no processes that can conveniently and easily produce a polysuccinimide (co)polymer derivative with a high reaction efficiency, allows simple isolation and purification operations, without using an organic solvent having similar polarity and a high boiling point such as dimethylformamide and N-methylpyrrolidone and requiring any pH-adjusting step.
An object of the present invention, therefore, is to solve the above-mentioned problems and to provide, in place of conventional reaction processes, a novel process for the production of a polysuccinimide (co)polymer derivative and a polysuccinimide (co)polymer derivative produced by this process.
Another object of the present invention is to provide a process for producing a polysuccinimide (co)polymer derivative that does not necessitate a pH-adjusting step (does not use a special pH-adjusting agent) and permits the reaction of a polysuccinimide (co)polymer with a Lewis base at a temperatures within a wide range.
A further object of the present invention is to provide a process for efficiently and easily producing a polysuccinimide (co)polymer derivative that does not use an organic solvent having similar polarity and a high boiling point such as dimethylformamide or N-methylpyrrolidone and allows simple isolation and purification and a polysuccinimide (co)polymer derivative produced by this process.
DISCLOSURE OF INVENTION
It has been well known that the glass transition point (Tg) of polysuccinimide (co)polymer is higher than its decomposition point and when the polysuccinimide (co)polymer is heated for melting, it decomposes before melting. The reaction temperature, therefore, has been required to be set in a relatively narrow temperature range, for example, from 0° to 100° C.
The present inventors have made a diligent study to achieve the objects as described above, to find that a polysuccinimide (co)polymer which is insoluble at a normal temperature under a normal pressure, when heated in the presence of a solvent having a low boiling point and high relative permittivit
Mukouyama Masaharu
Yasuda Shinzo
Hampton Hightower P.
Nippon Shokubai Co. , Ltd.
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