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, and optionally one additive selected from the group of a hydroxycarboxylic acid and a salt in combination with a polycarboxylic acid. After pre-treatment, the polymer is acylated and, preferably, subjected to a post-treatment step with an acid. The products obtained are useful as additives in varnishes, lacquers, coatings, thickeners, adhesives or binders, and preferably inks.

Claims

1. A process for the manufacture of an acylated polymer composition comprising acylated amylose and/or acylated amylopectin, having a viscosity from between 10 to 200 mPas (35 w % in EtOAc at 25 C.), the method comprising: (a) pre-treating a polymer composition comprising amylose and/or amylopectin with an aqueous phase comprising one first 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 optionally one or more second additives selected from the group consisting of at least one salt in combination with at least one polycarboxylic acid and at least one hydroxycarboxylic acid, to swell the amylose and/or amylopectin forming swollen amylose and/or swollen amylopectin; (b) reacting the pre-treated polymer composition comprising the swollen amylose and/or swollen amylopectin with an acylating agent to provide an acylated polymer composition comprising amylose and/or 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 to partially hydrolyze the acylated polymer obtained in step (b), wherein the acylated polymer composition has a degree of substitution (DS) in the range of from 2.0 to 2.9.

2. The process of claim 1, wherein in step (a) the polymer composition comprising acylated amylose and/or acylated 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 60 minutes.

3. The process according to claim 1, 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.

4. The process according to claim 1, wherein the second additive is at least one salt in combination with at least one polycarboxylic acid, wherein the at least one poly carboxylic acid has from 2 to 12 carbon atoms, and at least two carboxylic acid groups COOH.

5. The process according to claim 1, wherein the second additive is at least one hydroxycarboxylic acid, wherein the least one hydroxy carboxylic acid has from 2 to 12 carbon atoms which are at least in one position substituted by at least one OH group.

6. The process according to claim 1, wherein the first additive is an enzyme.

7. The process according to claim 1, wherein the first additive is at least one acid A having a pKa of equal to or less than 4.8 at 25 C. selected from the group consisting of mineral acids, sulfonic acids, and carboxylic acids, all of which are either monoprotic or polyprotic.

8. The process according to claim 1, 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.

9. The process according to claim 1, wherein the first additive in step (a) is a monocarboxylic acid, wherein the monocarboxylic acid corresponds to the carboxylic acid obtained by hydrolysis of the acylating agent.

10. The process according to claim 1, 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.

11. The process according to claim 1, wherein the polymer composition comprising amylose and/or amylopectin provided in step (a) is a chemically modified starch, 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.

12. The process according to claim 1, 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 (measured as 35 w % solution in EtOAc at 25 C.) is in a range of from 10 to 200 mPas.

13. The process according to claim 1, 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.

14. The process according to claim 3, wherein the at least one acid A and the at least one acid A are the same or different, and are selected from the group consisting of sulfuric acid, amidosulfonic acid, benzene sulfonic acid, or phosphoric acid.

15. The process according to claim 4, wherein the at least one polycarboxylic acid is selected from the group consisting of oxalic acid, malonic acid and succinic acid, glutaric acid, and adipic acid.

16. The process according to claim 4, wherein the at least one salt consists of a metal cation species and an inorganic or organic anion species, wherein the metal cation species is selected from the group consisting of Mg.sup.2+, K.sup.+, Zn.sup.2+, Na.sup.+, Li.sup.+, Cu.sup.2+, and Ca.sup.2+, and the anion species is selected from the group consisting of sulfate, nitrate, chloride, carbonate, acetate, and malonate.

17. The process according to claim 5, wherein the at least one hydroxycarboxylic acid is selected from the group consisting of lactic acid, glycolic acid, and hydroxybutyric acid.

18. The process according to claim 6, wherein the enzyme is an amylase.

19. The process according to claim 8, wherein the carboxylic acid anhydride is acetic acid anhydride.

20. A process for the manufacture of an acylated polymer composition comprising acylated amylose and/or acylated amylopectin, having a viscosity from between 10 to 200 mPas (35 w % in EtOAc at 25 C.), which comprises: (a) pre-treating a polymer composition comprising amylose and/or amylopectin with an aqueous phase comprising at least one acid A having a pKa of equal to or less than 4.8 at 25 C., and optionally one or more additives selected from the group consistinq of at least one salt in combination with at least one polycarboxylic acid and at least one hydroxycarboxylic acid, where the at least one acid A is added in an amount of equal to or greater than 0.01 weight percent; (b) reacting the pre-treated polymer composition with an acylating agent to provide an acylated polymer composition comprising amylose and/or 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 to partially hydrolyze the acylated polymer obtained in step (b), wherein the acylated polymer composition has a degree of substitution (DS) in the range of from 2.0 to 2.9.

Description

EXAMPLES

Example 1

(1) 1000 kg of waxy maize with a moisture content of 12.6 weight % were reacted with 900 kg of glacial acetic acid, 2.2 kg of sulphuric acid (72% w/w) and 20 kg of distilled H.sub.2O for 1.5 h between 75-95 C.

(2) 3250 kg of acetic anhydride (91.2% w/w, T=8 C.) were added in portions 1.5 h.

(3) The reaction temperature was kept between 75 and 95 C.

(4) After 3.5 h the reactants and product were completely dissolved. The reaction mixture was cooled down to 50 C. and 365 kg of 40% w/w acetic acid in water were added. Afterwards the reaction mixture was precipitated in water to obtain the acetylated starch.

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

(6) 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 %.

Example 2

(7) In example 1, after the acetylation reaction was stopped by addition of 40% acetic acid w/w in water, by which the water content of 8-12 weight % was adjusted in the reaction mixture. The reaction mixture was heated up until a temperature of between approx. 70-95 C. and 03 weight % of concentrated sulphuric acid (95-98% w/w) was added.

(8) In 1-17 h at 70-95 C. a series of different DS (2.9-2.2) was obtained. The products were soluble in ethylacetate, butylacetate, cyclohexanone, acetone, triacetine, chloroform, depending of the degree of substitution.

(9) The characteristics of the starch acetate obtained after 13 h were as following:

(10) Viscosity (35 weight % in ethylacetate, 25 C.): 75 mPas;

(11) The solid composition of this particular derivative with a DS of 2.26 has an average density of 1.37 g/cm.sup.3, a surface area of 9.5 m.sup.2/g, a bulk density of 0.283, a main partical size distrubtion of 10-100 m and a glass transition offset temperature of 151.28 C.

Example 3

(12) 450 g of waxy maize with a moisture content of 13.6 weight % were reacted with 420 g of glacial acetic acid, 1.1 g of sulphuric acid (72% w/w) and 4 g of distilled H.sub.2O for 1.0 h at 75 C.

(13) 1.45 kg of acetic anhydride (91.2% w/w, T=8 C.) were added continuously through a pump within 3.5 h.

(14) The reaction temperature was kept between 75 and 95 C.

(15) After 3.5 h the reactants and product were completely dissolved. The reaction mixture was cooled down to 50 C. and 0.220 l of 56.5% w/w acetic acid in water were added. After the reaction was stopped by addition of 56.5% w/w acetic acid, a water content of 10-12 weight % was adjusted in the reaction mixture, the reaction mixture was heated up to a temperature between approx. 70-95 C. and 0.002 weight % of concentrated sulphuric acid (95-98% w/w) is added.

(16) In 1-10 h a series of different DS (substitution degree 2.9-1.6) was obtained.

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

(18) 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 %. Viscosity (35 w % in EtOAc at 25 C.)=28 mPas (after 4.5 hours of treatment according to step c))

(19) Soluble in ethylacetate, triacetine, chloroform.