Acylation process

Abstract

The invention concerns a process for the manufacture of an acylated polymer composition comprising amylose and/or amylopectin, comprising a pre-treatment step in the presence of an acid, a salt and a polycarboxylic acid, subsequent acylation and, preferably, a post-treatment step with an acid. The products obtained are useful as additives in inks, varnishes, lacquers, coatings, thickeners, adhesives or binders.

Claims

1. An acylated polymer composition comprising acylated amylose and/or acylated amylopectin, which is made by a process comprising the following steps: (a) pre-treating a polymer composition comprising amylose and/or amylopectin with an aqueous phase, the aqueous phase comprising at least one salt, at least one polycarboxylic acid, and one additive selected from the group consisting of at least one acid A having a pKa of equal to or less than 4.8 at 25 C. and an enzyme; (b) reacting the pre-treated polymer composition with an acylating agent to provide an acylated polymer composition comprising acylated amylose and/or acylated amylopectin; and (c) reacting the acylated polymer composition obtained in step (b) with at least one acid A with a pKa of equal to or less than 4.8 at 25 C., in the presence of water.

2. The acylated polymer composition of claim 1, the acylated polymer composition having a degree of substitution (DS) in the range of from 2.1 to 2.9, and wherein the acylating agent is acetic acid anhydride.

3. An acylated polymer composition comprising acylated amylose and/or acylated amylopectin, which is made by a process comprising the following steps: (a) pre-treating a polymer composition comprising amylose and/or amylopectin with an aqueous phase comprising at least one salt, at least one polycarboxylic acid, and one additive selected from the group consisting of at least one acid A having a pKa of equal to or less than 4.8 at 25 C. and an enzyme; (b) reacting the pre-treated polymer composition with an acylating agent to provide an acylated polymer composition comprising acylated amylose and/or acylated amylopectin; and (c) reacting the acylated polymer composition obtained in step (b) with at least one acid A with a pKa of equal to or less than 4.8 at 25 C., in the presence of water, wherein the viscosity of polymer composition is equal to or greater than 77 mPas (10 w % in Triacetin at 30 C.).

4. A process for manufacturing an acylated polymer composition comprising acylated amylose and/or acylated amylopectin, having a viscosity of equal to or greater than 77 mPas (10 w % in Triacetin at 30 C.), which comprises: (a) pre-treating a polymer composition comprising amylose and/or amylopectin with an aqueous phase, the aqueous phase comprising at least one salt, at least one polycarboxylic acid, and one additive selected from the group consisting of at least one acid A having a pKa of equal to or less than 4.8 at 25 C. and an enzyme; and (b) reacting the pre-treated polymer composition with an acylating agent to provide an acylated polymer composition comprising acylated amylose and/or acylated amylopectin.

5. The process according to claim 4 further comprising: (c) reacting the acylated polymer composition obtained in step (b) with at least one acid A with a pKa of equal to or less than 4.8 at 25 C., in the presence of water.

6. The process according claim 5, wherein the at least one acid A used in step (a) and the at least one acid A used in step (c) can be the same or different and are selected from the group consisting of mineral acids, sulfonic acids, and carboxylic acids, all of which are either monoprotic or polyprotic.

7. The process according to claim 6, wherein the at least one acid A and the at least one acid A are the same or different, and are sulfuric acid, amidosulfonic acid, benzene sulfonic acid, or phosphoric acid.

8. The process according to claim 5, wherein the additive is an enzyme, and wherein acid A in step (c) is selected from the group consisting of mineral acids, sulfonic acids and carboxylic acids, all of which are either monoprotic or polyprotic.

9. The process according to claim 8, wherein the enzyme is an amylase.

10. The process according to claim 5, wherein the reaction time and reaction temperature of step (c) is selected such that the degree of substitution (DS) of the acylated polymer composition comprising amylose and/or amylopectin is from between 2.0 to 2.9.

11. The process of claim 4, wherein in step (a) the polymer composition comprising amylose and/or amylopectin is pre-treated at a temperature in a range of from 20 C. to 85 C. during a pre-treatment time in a range of from 1 minutes to 30 minutes.

12. The process according to claim 4, wherein the at least one polycarboxylic acid has from 2 to 12 carbon atoms, and at least two carboxylic acid groups COOH.

13. The process according to claim 12, wherein the polycarboxylic acid is at least one dicarboxylic acid and is selected from the group consisting of oxalic acid, malonic acid and succinic acid, glutaric acid, and adipic acid.

14. The process according to claim 4, wherein the salt consists of a metal cation species and an inorganic or organic anion species.

15. The process according to claim 14, wherein the metal cation species is selected from the group consisting of Mg.sup.2+, K.sup.+, Na.sup.2+, Li.sup.+, Cu.sup.2+, and Ca.sup.2+, and the anion is selected from the group consisting of sulfate, nitrate, chloride, carbonate, acetate, and malonate.

16. The process according to claim 4, wherein the acylating agent is selected from the group consisting of carboxylic acids, symmetrical or unsymmetrical carboxylic acid anhydrides, carboxylic acid halides, and carboxylic acid carbonylimidazoles.

17. The process according to claim 16, the acylated polymer composition having a degree of substitution (DS) in the range of from 2.1 to 2.9, and wherein the carboxylic acid anhydride is acetic acid anhydride.

18. The process according to claim 4, wherein step (a) is carried out in the presence of a monocarboxylic acid, wherein the monocarboxylic acid corresponds to the carboxylic acid obtained by hydrolysis of the acylating agent.

19. The process according to claim 4, wherein the polymer composition comprising amylose and/or amylopectin provided in step (a) is selected from the group consisting of chemically modified starches, unmodified starches, and a mixture of chemically modified starches and unmodified starches, and wherein the chemically unmodified starch is selected from the group consisting of maize starch, wheat starch, potato starch, rice starch, pea starch, rye starch, millet starch, and manioc starch, and wherein the chemically modified starch is selected from the group consisting of chemically modified maize starch, chemically modified wheat starch, chemically modified potato starch, chemically modified rice starch, chemically modified pea, chemically modified rye starch, chemically modified millet starch, and chemically modified manioc starch.

20. The process according to claim 19, wherein the chemically modified starch is selected from the group consisting of crosslinked starches, acylated starches, hydroxyethylated starches, hydroxypropylated starches, methylated starches, oxidized starches, and cationic or anionic starches.

21. The process according to claim 4, wherein the time and temperature of the pre-treatment are selected such that the viscosity of the final acylated polymer composition comprising amylose and/or amylopectin is equal to or greater than 77 mPas (10 w % in Triacetin at 30 C.).

22. A process of manufacturing inks, varnishes, lacquers, coatings, thickeners, adhesives, or binders comprising the acylated polymer composition according to claim 1 as an ingredient in the process.

Description

EXAMPLES

Example 1

(1) 20 kg of waxy maize with a moisture content of 12.1 weight was reacted with 17 l of glacial acetic acid, 40 g of sulphuric acid and a mixture of 40 g of a malonic acid (50 weight % solution in water) and 15 g of MgCO3 (30 weight % suspension in water during 1.5 h at a temperature of 75 C.

(2) 58 l of acetic anhydride (91.2% w/w, T=8 C.) were added in portions (approx. 2-5 l) during 1.2 h. The reaction temperature was kept between 75 and 90 C. After 3 h the starch acetate was completely dissolved. The reaction mixture was cooled down to 50 C. 7 l of 56.5% w/w acetic acid in water were added. Afterwards 5-25 l portions of the reaction mixture were poured in approx. 100 l of cooled water to precipitate the product.

(3) The precipitated powder was washed until no acetic acid was detectable.

(4) The starch acetate powder was pressed of to a solid content of approx. 20 weight % and dried to a moisture content of approx. 0.5-3 weight %.

(5) The characteristics of the starch acetate obtained were as following: DS=2.98 Viscosity (10 weight % in triacetine, 30 C.) 100 mPas Soluble in ethylacetate, triacetine, chloroform

Example 2

(6) In example 1, after the acetylation reaction is stopped by addition of 56.5% w/w acetic acetic acid in water, a water content of 10-12 weight % was adjusted in the reaction mixture, the reaction mixture was heated up until a temp. between approx. 70-95 C. and 0.002 weight % of concentrated sulphuric acid (95-98% w/w) was added. In 1-10 h a series of different DS (substitution degree 2.9-1.6) was obtained.

Example 3

(7) 10 kg of waxy maize with a moisture content of 12.4 weight was reacted with 12 l of glacial acetic acid and 70 g of benzene sulfonic acid (75 weight % in water) during 1.5 h at a temperature of 75 C.

(8) 67 l of acetic anhydride (91.2% w/w, T=8 C.) were added in portions (approx. 2-5 l) during 1.2 h. The reaction temperature was kept between 75 and 90 C. After 3 h the starch acetate was completely dissolved. The reaction mixture was cooled down to 50 C. 10 l of 56.5% w/w acetic acid in water were added.

(9) Afterwards, a water content of 8-12 weight % was adjusted in the reaction mixture, the reaction mixture was heated up until a temp. between approx. 70-95 C. and 0.2 weight % of concentrated sulphuric acid (95-98% w/w) was added. Afterwards 5-25 l portions of the reaction mixture were poured in approx. 100 l of cooled water to precipitate the product.

(10) The precipitated powder was washed until no acetic acid was detectable.

(11) The starch acetate powder was pressed of to a solid content of approx. 20 weight % and dried to a moisture content of approx. 0.5-3 weight %.

(12) In 1-10 h a series of different DS (substitution degree 2.9-1.6) was obtained. Viscosity (35 weight % in ethylacetate, 25 C.) 379 mPas, DS=2.7; Soluble in ethylacetate, triacetine, chloroform.