WO1993002118A1

WO1993002118A1 - A process for preparing alkali metal salts of polyacrylic acid based on polysaccharide

Info

Publication number: WO1993002118A1
Application number: PCT/KR1992/000030
Authority: WO
Inventors: In Hwan Park; Tae Suk Park; Young Wun Kim
Original assignee: Taechang Moolsan Co., Ltd.
Priority date: 1991-07-16
Filing date: 1992-07-16
Publication date: 1993-02-04
Also published as: KR940000169B1; JPH089654B2; JPH06508654A; KR930002376A

Abstract

The present invention relates to a process for preparing alkali metal salts of polyacrylic acid based on polysaccharide. They are gained in high yield by graft reaction of acrylic monomers on to polysaccharide in the presence of redox catalyst in aqueous alcohol solution, followed by neutralization with sodium hydroxide-water solution. The products show good properties for both chelating ability for heavy metal ions and biodegradability by enzyme.

Description

A PROCESS FOR PREPARING ALKALI METAL SALTS OF POLYACRYLIC ACID BASED ON POLYSACCHARIDE BACKGROUND OF THE INVENTION

The present invention relates to a process for preparing alkali metal salts of polyacrylic acid based on polysaccharide as dispersing agent. In accordance with the present invention alkali metal salts of polyacrylic acid based on polysaccharide having both good chelating ability for heavy metal ions and biodegradability by microorganism are gained in high yield by graft reaction of acrylic monomers onto polysaccharide in aqueous alcohol solution, followed by neutralization with sodium hydroxide-water solution.

Generally, detergent consists of some components such as straight chained alkylbenzenesulfonate, sodium tripolyphosphonate, alkali metal salts of polyacrylic acid, sodium silicate, sodium carbonate, perfume and dyestuff, etc. Among them, sodium triphosphonate having good chelating ability accelerates the undernourishment of small stream or river, resulting in contaminated water. And alkali metal salts of polyacrylic acid as dispersing agent have low chelating ability for heavy metal ions and low biodegradability by microorganism.

For increasing the chelating ability and biodegradability of alkali metal salts of polyacrylic acid, graft copolymerizations of acrylic monomers onto polysaccharide were carried out[J. Appl. Polym. Sci., 32(1986) 4971 : Eur. Polym. J., 25(1989)423]. The results brought about low grafting yields because of low solubility of polysaccharide in aqueous solution at reaction temperatures of 25 ~ 70ºC .

For improving these problems, some methods using the highly reactive starch- thiolated [Tappi, March, 56(1973)97], irradiated[J. Appl. Polym. Sci., 26(1981)2073], acrylated[J. Polym. Sci., Part-A, 5(1965)1031] etc., - in graft reaction, and reacting at high temperature [Ger Offen., 2,436,555 (1976)] were proposed. Other methods using redox (reduction-oxidation) catalysts [J. Polym. Sci., 23(1971) 229] such as eeric ammonium salt, penton reagent and manganese sulfate were also introduced. In particular, it was difficult to carry out graft reaction of acrylic monomers onto polysaccharide by radical initiators [J. Polym. Sci., 23(1971) 229]. The methods were not desirable due to the low grafting yields at reaction temperatures of 25 ~ 70ºC .

SUMMARY OF THE INVENTION

The object of the present invention is to provide for preparing low molecular weight copolymer having high grafting yield by graft reaction of acrylic monomers onto polysaccharide in the presence of redox catalyst in aqueous alcohol solution, where alcohol is used as reaction diluent for polysaccharide.

Alkali metal salts of polyacrylic acid based on polysaccharide in this invention may be prepared by dissolving polysaccharide with aqueous alcohol solution on heating, cooling slowly, adding acrylic monomers and/or vinyl comonomers and a mixture of redox catalysts, stirring the mixture at proper temperature for several hours, and then distilling off aqueous alcohol solution under reduced pressure, and neutralizing with sodium hydroxide-water solution.

DETAILED DESCRIPTION OF THE INVENTION

According to this invention, alkali metal salts of polyacrylic acid based on polysaccharide are prepared in high yield by dissolving polysaccharide with 0.5 ~ 95% aqueous alcohol at 60 ~ 90ºC for 0.5 ~ 5 hrs, cooling slowly, adding acrylic monomers and/or vinyl comonomers and a mixture of redox catalysts under nitrogen atmosphere, stirring with the mixture at 25 ~ 70ºC for 2 ~ 40 hrs, and then distilling off aqueous alcohol solution at 60ºC under reduced pressure, neutralizing with sodium hydroxide- water solution.

Alcohols as the reaction diluents in this invention are used for good contacting of acrylic monomers onto polysaccharide in aqueous solution, and for reducing molecular weight of the product. They are normal-or iso alcohols with 3 ~ 9 atoms such as propanol, butanol, pentanol, hexanol, heptanol, octanol, isopropanol, isobutanol, isohexanol and isoheptanol, where one or a mixture of two or more is selected. Then, polysaccharide was dissolved by the alcohols in the graft copolymerization of acrylic monomers onto the polysaccharide. The yields in the graft reaction using alcohols were very high. The molecular weights of the product were properly controlled due to the chain transfer reactions caused by alcohol solvents.

Alcohols were used within 0.5 ~ 95% of aqueous solution. The reactant solution below 0.5% is not homogeneous and more viscous. The solution over 95% is less viscous and is required much energy for recovery of alcohol.

Acrylic monomers used in this invention are acrylic acid, methacrylic acid, maleic anhydride and fumalic acid.

And vinyl comonomers are methylacrylate, ethylacrylate, propylacrylate, butylacrylate, methyl methacrylate, hydroxyalkyl methacrylate, acrylonitrile, aciylamide and 4-vinyl pyridine. In this invention one or over two of these vinyl comonomers can be used.

These monomers are used for solubilizing of polysaccharide and maintaining of chelating ability, and they are used within 20 ~ 700 weight percent of the amount of used polysaccharide. The reactant solution below 20 weight percent is not homogeneous, and if over 700 weight percent, it is impossible to control the chelating ability for heavy metal ions.

Also, polysaccharides used in this invention are starch, cellulose and their derivatives. That is, they are starch of corn, potato, wheat, sweet potato and rice, and modified starch containing aldehyde, alkylether, oxyalkyl, hydroxyethylether, aminoethylether, cyanoethylether and carboxymetyl group and cellulose derivatives containing alkylether, organic acid ester, hydroxyl and carboxymethyl group.

Oxidation catalysts used in this invention are hydrogen peroxide, ascorbic acid, tert-butylhydroperoxide, di-tert-butylhydroperoxide, dicumylperoxide, cumenehydroperoxide, 2,5-dimethyl-hexyl-2,5-dihydroperoxide, diisopropylbenzeneperoxide, 2,5-dimethylhexyl-2,5-(peroxybenzoate),

di-tert-butylperoxyphthalate, tert-butylperoxyacetate, and tert-butylperoxyisopropyl carbonate, etc. They are used one or a mixture of two or more.

Reduction catalysts used in this invention are potassium persulfate, potassuim permanganate, potassium perchromate, ferric ammonium sulfate,

N-cyclohexylbenzothiazol-2-sulfoneamide, N,N'-dimethyl-p-toluidine, N,N'-diethyl-p- toluidine, N,N'-diisoproyl-p-toluidine, butylamine, N,N'-dimethylaniline,

bis(phenylsulfonemethyl) amine, bis(p-tolylsulfonemethyl) amine, N-methyl-bis(p- tolylsulfonemethyl) amine, N-ethyl-bis(p-tolylsulfonemethyl) amine, N-ethanol-bis(p- tolylsulfonemethyl) amine, N-phenyl-p-tolylsulfonemethylamine, N-phenyl-N-methyl- p-tolylsulfonemethylamine, bis(p-tolylsulfonemethyl)ethylenediamine,

N-(p-chlorophenyl)-p-tolylsulfonemethylamine, N-(iso or p-carboethoxyphenyl)-(p- tolylsulfonemethyl) amine, o-benzoic sulfamide, phthalamide, benzoic acid sulfamide, acetic acid hydrazine, thiourea, N,N'-dimethyl-p-toluidine, N,N'-dimethyl-o-toluidine, N,N'-dicyclohexyl-thiourea, acetylthiourea, tetramethylthiourea,

mercaptobenzothiazole, 2-triazole-3-diol, and mercaptobenzoimidazole, etc. They are used one or a mixture of two or more.

The catalysts used in this invention are used within 0.0005 ~ 0.5 mol percent of the amount of used acrylic- and vinyl comonomers, where one or a mixture of redox catalysts is selected. If they are used below 0.0005 mol, they are ineffective, and if over 0.5 mol, the graft yields are reduced due to the production of much homopolymers.

Alkali metal salts of polyacrylic acid based on polysaccharide prepared in this invention have viscosity of 50 ~ 10,000 cps. Even in the case of using hard water, they show good dispersing effect to prevent heavy metal ions in aqueous solution from precipitating. They also show good biodegradability by microorganism due to the high biodegradability of polysaccharide component. So, they are very useful dispersing agents having both chelating ability and biodegradability.

The following examples illustrate ways in which the principle of this invention has been applied, but are not to be construed as limiting its scope.

EXAMPLE 1 ~ 10

To a reactor having reflux condenser 2 l of aqueous isopropanol or butanol solution of 2.6 ~ 10.6% and 32.4g(0.2 mol) ~ 129.6g (0.8 mol) of com starch were added, and were heated to 7013 for homogeneous solution, then cooled slowly to 40ºC .

Subsequently, 14.4g (0.2 mol) ~ 57.6g(0.8 mol) of acrylic acid, 8.6g (0.1 mol) ~ 17.2g

(0.2 mol) of methacrylic acid, 10g (0.1 mol) ~ 20g (0.2 mol) of ethylacrylate, and a mixture of potassium persulfate [9.99g (0.037 mol)] and hydrogen peroxide [1.97g

(0.058 mol)] were added, and the mixture was stirred at 4013 for 9 hrs.

The aqueous alcohol solution was distilled off under reduced pressure and the reactant was neutralized with 8g (0.2 mol) ~ 32g (0.8 mol) of sodium hydroxide- water solution to obtain viscose liquid (40 weight percent of solid content). Physical properties of the product were shown in Table 1.

COMPARATIVE EXAMPLE 1 ~ 9

To the same reaction of above example 2 l of distilled water, 32.4g (0.2 mol) ~

129.6g (0.8 mol) of com starch, 14.4g (0.2 mol) ~ 57.6g (0.8 mol) of acrylic acid, 8.6g (0.1 mol) ~ 17.2g (0.2 mol) of methacrylic acid, lOg (0.1 mol) of ethylacrylate, and a mixture of potassium persulfate [9.99g (0.037 mol)] and hydrogen peroxide [1.97g (0.058 mol)] were added and were heated to 7013 for homogeneous solution, then cooled slowly to 4013.

The mixture was stirred at 4013 for 6 hrs. The aqueous solution was distilled off under reduced pressure and the reactant was neutralized with 8g (0.2 mol) ~ 32g (0.8 mol) of sodium hydroxide-water solution to obtain viscose liquid (40 weight percent of solid content). Physical properties of the product were shown in Table 2.

a. Treated as ^α -form at 70ºC

b. Weight percent of alcohol based on polysaccharide c. Measured after extracting with 1 ,4-dioxane

a. Treated as ^α -form at 70ºC

b. Measured after extracting with 1,4-dioxane

Claims

In Table 1, 2, chelating ability1) of product was measured by test method of Japanese Patent Kokai No. 52-4510 (1952) and 52-9005(1952). And biodegradability2) was measured by Millers test method [Anal. Chem., 31(1959)426]. That is, 3000IU/ml of α -amylase enzyme was added to 4% (w/v) of solid sample, and stayed at 4513 for 20 min and at boiling water for 5 min. Absorptivity of solution at 550nm was measured by dinitrosalicylic acid method, where it was evaluated that the higher absorptivity was, the better biodegradability by enzyme was. What is claimed is :

1. A process for preparing alkali metal salts of polyacrylic acid based on polysaccharide was characterized by dissolving polysaccharide with alcohol at a termperature range of 60 ~ 9013 for 2 ~ 40 hrs, adding acrylic monomers and/or vinyl comonomers, and a mixture of redox catalysts for the graft reaction, and then distilling off aqueous alcohol solution under reduced pressure, neutralizing with sodium hydroxide- water solution.

2. The process as defined in claim 1, wherein said alcohol is normal- or iso alcohol of 3 ~ 9 carbons and is used within 0.5 ~ 95% of aqueous solution.

3. The process as defined in claim 1, wherein said graft reaction is carried out at 25 ~ 70ºC for 2 ~ 40 hrs under nitrogen atmosphere.