MXPA97004913A - Decoloration of polisuccinim - Google Patents

Abstract

A process for decolorizing polysuccinimide by contacting the polysuccinimide in the solid state with an aqueous solution of a bleach is described, typically the polysuccinimide is placed in a hydrogen peroxide solution to form a suspension with solid particles, so the color of the polysuccinimide is greatly reduced, the separation of the bleaching solution is easily carried out by means of solid and liquid separation such as by filtration, producing the acceptable polysuccinimide for use directly in detergent formulations

Description

DISCOLORATION OF POLISUCCINIMI fl This invention relates to the production of polyunsaturated and more particularly to a process in which the polymer is bleached and rendered useful and applications in which the color of the succinic important..

BACKGROUND OF THE INVENTION ip The poliaspart co acid has become every v; ' more important in recent years as a useful polymer in areas such as water treatment, detergents, cosmetics and hair treatment. In the condensation procedures At normal thermal reactions, an initial polysuccinimide is produced to create the polymer, which is subsequently hydrolyzed to produce a water-soluble salt such as a poliaspart ai or < Sodium It has been commonly noted in the literature, that the color of polysucchimide is greatly related to the ? D time / temperature ratio during its production. For example, the color of the product that comes from the procedures that employ a relatively longer reaction time at elevated temperature produces a succinimide of a color as dark as that produced with time. of shorter reaction and lower temperatures. A typical teaching of this phenomenon is found in a publication entitled "Temperature on the Molecular Ueight and the Optical Purity of" flhydropolyaspart c acid Prepared by Thermal Polycondensation "by Kokufuta et al., Bulletin of the Chemical Sooiety of .apan, Vol. 51, pp. 1555-1556, 1 7 H. Many efforts have been made to decrease the time / temperature ratio by employing various types of dryers that provide greater efficiency, Recent examples include EU patent No. 5,057,597, the patent of rUPi 5,315,010 and FUn patent 5,319,145 In all of these patents dryers are used in an attempt to convert aspartic acid into polyaspartic acid by thermal condensation, however polysuccinate produced by such processes possesses an undesirable color. color of the pol i succinirnide is transferred to the water soluble salt after the hydrolysis of the initiated product. The use of acidic catalysts such as phosphoric acid reduces the color of the resulting polysuccinimide. In another attempt to overcome the color problem, it has been found that the polyaspartate formed by thermal polymerization followed by the alkaline hydrolysis is treated with bleach in water solution. It has been reported that this treatment discolours the polyaspartate sol as mentioned in the U.S. Patent. No. 5,292,864 to Wood et al. However, in many cases the polysuccinate column becomes a disadvantage since this initial product is used without first converting it into the water-soluble polysaccharide salt as was done in the aforementioned pate to Uood et al. For example, in the patent of E.U.fl. No. 5,266,237 to Freeman et al., And in Austrian patent No. Fi-14775/9, the mucosuccinic acid is added to other ingredients to form a detergent composition. The color of the polysuccinimide, particularly in detergent applications, is desirably as colorless as possible. Thus, the method for decolorizing the water solution of the s l is not useful for preparing desirable compositions of the aforementioned patent to Freeman et al., Which incorporates succinimide. Consequently, a procedure is necessary for the discoloration of the polisucci mm da.

BRIEF DESCRIPTION OF THE INVENTION In accordance with this invention, the color of the polysuccinimide is reduced by treating the water soluble polysuccess with a bleach. Although the color of the polysuccimide produced by the usual condensation of the aspartic acid from light cinnamon to dark brown, the process of this invention reduces the color of the polychromimide to a whitish color which is advantageous to use directly on detergent compositions Briefly, polysuccinimi da is reduced in water which contains an oxygen bleach at approximately 1% concentration. The mixture is stirred briefly while reducing the color of the water-insoluble succimer particles. The solid polymer is recovered by conventional means. It has surprisingly been found that the amount of color in the hydrolysed polysaccharide salt is also reduced by indicating that the color of the surface is a surface phenomenon easily treated with bleach.

DETAILED DESCRIPTION OF THE INVENTION In accordance with this invention, a method is provided to reduce the color of the polysuccinic acid by contacting the poly succinicide with an aqueous solution of a bleach. Typical bleaches include the preferred hydrogen peroxide, also sodium hypochlorite, ozone, peroxydicarbonate, chlorine peroxides or sulfur esters as described in the patents of F.U.A. Nos. 4,824,591 and 5,004,558, both to Dyroff and others. Surprisingly, it has been found that the treatment with non-polishable bleach, which is easily recovered from the aqueous bleaching solution since it is more soluble in water before and after the bleaching treatment. In the practice of this invention, a bleaching solution is prepared by combining a water-soluble bleach in an amount of about 0.5% to about 2% by weight. Higher concentrations of bleaching material can be used. However, no further improvement in color is expected and therefore such higher concentrations would be inefficient. Sufficient solution is employed to allow the formation of an easily stirred and fluid suspension containing the poly succinimide. The polysuccinate is left in the suspension for a sufficient time to reduce the color of the particles and is then recovered. Normally, a sufficient reduction in the color of the polysuccinolide is obtained by contacting the bleaching solution for approximately 24 hours. A contact time can be used? Na < : long or shorter depending on the amount of bleach- in the solution and the temperature used. In many cases room temperature is employed, although any suitable temperature above ambient temperature such as about 25 ° C to about 100 ° C can be employed. The recovery of the polysuccinimide can be carried out by conventional means such as filtration, centrifugation or drying. It is preferred to separate polystyrene.

DESCRIPTION OF THE PREFERRED MODALITIES EXAMPLE 1 Was it produced by the thermal condensation of acid 1 -aspart? in the presence of phosphoric acid catalyst in the amount of 15% by weight of the 1-asparatic acid. The 1-ascorbic / phosphoric acid mixture was introduced into a rotary tray dryer such as that described in the U.S. Pat. No. 5,319,145 to Pai and other < -, in which air heated to 250 ° C was continuously introduced. The residence time in the rotary tray dryer was 2.5 hours. The polysuccinirnide produced in this way has a dark reddish-brown color. The polycinimide was finally ground and divided into three samples. The first sample, I4.39 g of polysuccin tni da, was hydrolyzed by combining it with 13.93 g of 50.2% sodium hydroxide in 36.83 g of water to provide a pH on the scale of 9.8-10. The aqueous solution was clear but also of a dark reddish-brown color. The second polymer sample, 14.4 g, was hydrolysed with 13.6 g of 50.2% sodium hydroxide in 36.57 g of deionized water containing 1.56 g of 30.2% hydrogen peroxide. The color of the clear solution resulting from sodium polyaspartate was light yellow. The third polysuccinimide sample, 10.01 g, was debased with 82.43 g of deionized water containing 0. 7 g of 32% by weight hydrogen peroxide. The solution was stirred for 24 hours at room temperature. The polysuccinirnide particles were recovered by filtration and exhibited a very clear tan color.

EXAMPLE 2 prepared 3 samples of polysuccinirnide as: Sample 1 - prepared in an indirectly heated patent drier as described in the US patent. No. 5,315,010. ! Sample 2 - prepared with sample 1 except 9.4% by weight of phosphoric acid catalyst present. Sample 3 - prepared as in Example 1 without catalyst present. Each sample was divided into two portions. A portion 10 was treated with hydrogen peroxide as in Example 1 and the other portion was tested without further treatment. The color of these samples was analyzed by means of a color spectrum Hunter Labscan, which measures the color of a solid in three spectra as igue: L5 White-black (called Rd), where black - 0, white 0 Green-red (called (a)), where green r o = «-B. Yellow-blue (called (b)), where yellow or - * 2 £ i, 20 blue = • -28. Sei grams of each sample of succinirnide particles were analyzed for color verification as mentioned above, using the aforementioned spectrocolo and the results were reported in the following table. 0 0 from the data in the above table, 0 shows that in all the samples increase the whiteness with the treatment according to this invention. Likewise, in all the samples the red color was significantly reduced with the treatment according to this invention. Yellow was significantly reduced in treated samples 1 and 2. > Although the invention has been described in terms of specific modalities, which are set forth in considerable detail, it should be understood that this description is by way of illustration only and that the invention is not necessarily limited thereto, since the alternative modalities and operating techniques will become apparent to those skilled in the art in view of this description. Accordingly, modifications that can be made without departing from the spirit of this described invention are contemplated.

Claims (8)

NOVELTY OF THE INVENTION CLAIMS

1. - A procedure to reduce the color of polystyrene prepared by the thermal condensation of l-aspartic acid, which comprises contacting the polystyrene with an aqueous solution of a bleach, so that the color of the poly ucc nirnida is reduced.

2. The process according to claim 1, wherein the bleach is an oxygen bleach.

3. The process according to claim 2, wherein the oxygen bleach is hydrogen peroxide.

4. The process according to claim 1, wherein the bleach is selected from the group consisting of sodium hypochlo- prate, ozone, peroxydicarbonate, chlorine dioxide and sulfone peracids.

5. The process according to claim 1, wherein the concentration of bleach in the aqueous solution is on the scale of approximately 0.5% to about 2% by weight of the solution.

6. The process according to claim 1, wherein the polisucci nirnide is contacted with an aqueous bleaching solution that is at room temperature.

7. The process according to claim 1, wherein the polysuccinimide is contacted with an aqueous bleaching solution at a temperature in l? scale of about 25 ° C to about 100 ° C,

8. The process according to claim 1, wherein the polysuccina is recovered from the aqueous bleach solution by filtration.