OXIDATION OF STARCH

Abstract

The invention relates to oxidized starch, to a method of preparing oxidized starch and to the use of the oxidized starch in various applications.

Claims

1. A process for the oxidation of starch comprising the steps of: providing a first root or tuber starch comprising at least 95 wt. % of amylopectin, based on dry substance of the starch; providing a second root or tuber starch comprising from 65 to 85 wt. % of amylopectin, based on dry substance of the starch; and subjecting the first and second starches to an oxidation treatment, wherein the first and second starches are blended before or after they are subjected to an oxidation treatment.

2. A process according to claim 1, wherein the oxidation treatment comprises treatment with an alkali metal hypochlorite at a pH between 6.5 and 8.5.

3. A process according to claim 2 followed by an alkaline treatment comprising keeping the product for at least 15 minutes at a temperature of 20-50 C. and a pH higher than 10.

4. A process according to claim 1, wherein the oxidation treatment comprises treatment with hydrogen peroxide in the presence of a catalyst.

5. A process according to claim 4, wherein the catalyst comprises divalent copper ions or a manganese complex.

6. A process according to claim 1 wherein the first and second starches are blended in a ratio of between 1:3 and 3:1.

7. A process according to claim 1, wherein the first and second starches are chosen from the group of potato and tapioca starches.

8. A process according to claim 1, wherein the first starch, the second starch or both the first and second starches are starch derivatives.

9. A process according to claim 8 wherein the derivatives are obtained by crosslinking, etherification, or esterification of the starch, or a combination of two or more of said modifications.

10. A blend of oxidized starches obtainable by a process according to claim 1.

11. Use of a blend of oxidized starches according to claim 10 as a binder in paper coatings or surface sizings, as an adhesive, a protective colloid for stabilizing emulsions, in warp yarn sizing, as a coating of glass fibers, as a blanket adhesive, in abrasive paper as an emulsifying agent, such as for an alkyl succinic anhydride, an alkyl ketene dimer or an alkyl isocyanate, or in food products.

12. A process according to claim 6, wherein the first and second starches are blended in a ratio of between 1:2 and 1:1.

Description

EXAMPLE 1

[0051] 1.0 kg of regular potato starch (0.82 kg dry matter, food grade potato starch from AVEBE, amylopectin content 81 wt. % based on dry substance of starch) was suspended in 1.0 kg of water. The temperature of the suspension was increased to 35 C. The pH was set at 9.0 by the addition of a 4.4 wt. % sodium hydroxide solution. 108.6 ml of a sodium hypochlorite solution containing 179.5 g/liter of active chlorine was added. During the oxidation the pH was maintained at 9.0 by the addition of a 4.4 wt. % sodium hydroxide solution. Once the reaction was complete, i.e. no chlorine was detectable with potassium iodide-starch paper, the pH was increased to 10.5 by the addition of a 4.4 wt. % sodium hydroxide solution. After one hour of alkaline post-treatment 5 ml sodium hypochlorite solution was added for decoloration. The reaction mixture was neutralized to pH 5.5 by the addition of 10 N H.sub.2SO.sub.4, whereupon the product was dewatered and washed before drying.

EXAMPLE 2

[0052] 1.0 kg of amylopectin potato starch (0.82 kg dry matter, Eliane potato starch from AVEBE; amylopectin content >98 wt. % based on dry substance of starch) was suspended in 1.0 kg of water. The temperature of the suspension was increased to 35 C. The pH was set at 9.0 by the addition of a 4.4 wt. % sodium hydroxide solution. 64.0 ml of a sodium hypochlorite solution containing 179.5 g/liter of active chlorine was added. During the oxidation the pH was maintained at 9.0 by the addition of a 4.4 wt. % sodium hydroxide solution. Once the reaction was complete, i.e. no chlorine was detectable with potassium iodide-starch paper, the pH was increased to 10.5 by the addition of a 4.4 wt. % sodium hydroxide solution. After one hour of alkaline post-treatment 5 ml sodium hypochlorite solution was added for decoloration. The reaction mixture was neutralized to pH 5.5 by the addition of 10 N H.sub.2SO.sub.4, whereupon the product was dewatered and washed before drying.

EXAMPLE 3

[0053] A blend of 0.5 kg of regular potato starch (0.41 kg dry matter, food grade potato starch from AVEBE; amylopectin content 81 wt. % based on dry substance of starch) and 0.5 kg amylopectin potato starch (0.41 kg dry matter, Eliane potato starch from AVEBE; amylopectin content >98 wt. % based on dry substance of starch) was suspended in 1.0 kg of water. The temperature of the suspension was increased to 35 C. The pH was set at 9.0 by the addition of a 4.4 wt. % sodium hydroxide solution. 84.6 ml of a sodium hypochlorite solution containing 179.5 g/liter of active chlorine was added. During the oxidation the pH was maintained at 9.0 by the addition of a 4.4 wt. % sodium hydroxide solution. Once the reaction was complete, i.e. no chlorine was detectable with potassium iodide-starch paper, the pH was increased to 10.5 by the addition of a 4.4 wt. % sodium hydroxide solution. After one hour of alkaline post-treatment 5 ml sodium hypochlorite solution was added for decoloration. The reaction mixture was neutralized to pH 5.5 by the addition of 10 N H.sub.2SO.sub.4, whereupon the product was dewatered and washed before drying.

EXAMPLE 4

[0054] 0.5 kg of product prepared according to example 1 was homogeneous mixed with 0.5 kg of product prepared according to example 2 in the dry state by intensive mixing for 10 minutes.

EXAMPLE 5

[0055] The oxidized starch derivatives from the examples 1, 2, 3 and 4 were dissolved in 25% (dry matter) on a boiling water bath with high speed stirring (600-1200 rpm). After 30 minutes the solutions were stored at 50 C. and the viscosity was measured after 0, 1, 2, and 4 hours (Brookfield LVF, 60 rpm). The results of the different oxidized starches is shown in table 1.

TABLE-US-00001 TABLE 1 Viscosity 25%; 50 C. (mPa .Math. s) Time (h) Example 1 Example 2 Example 3 Example 4 0 433 230 201 276 1 >10000 233 231 295 2 >10000 228 248 273 4 >10000 255 260 280

[0056] Both the example 3 (pre-blended) and the example 4 (post-blending) exhibit excellent viscosity stability in solution.

EXAMPLE 6

[0057] 1.0 kg of regular potato starch (0.82 kg dry matter, food grade potato starch from AVEBE; amylopectin content 81 wt. % based on dry substance of starch) was suspended in 1.0 kg of water. The temperature of the suspension was increased to 30 C. The pH was set at 11.3 by the addition of a 4.4 wt. % sodium hydroxide solution. 80 ppm (based on starch) of the Mn catalyst (Interox Cat. D350) was added followed by 25.4 ml of a hydrogen peroxide solution containing 30% hydrogen peroxide. During the oxidation the pH was maintained at 11.3 by the addition of a 4.4 wt. % sodium hydroxide solution. Once the reaction was complete, i.e. no peroxide was detectable with potassium iodide-starch paper, the reaction mixture was neutralized to pH 5.5 by the addition of 10 N H.sub.2SO.sub.4, whereupon the product was dewatered and washed before drying.

EXAMPLE 7

[0058] A blend of 0.5 kg of regular potato starch (0.41 kg dry matter, food grade potato starch from AVEBE; amylopectin content 81 wt. % based on dry substance of starch) and 0.5 kg amylopectin potato starch (0.41 kg dry matter, Eliane potato starch from AVEBE; amylopectin content >98 wt. % based on dry substance of starch) was suspended in 1.0 kg of water. The temperature of the suspension was increased to 30 C. The pH was set at 11.3 by the addition of a 4.4 wt. % sodium hydroxide solution. 80 ppm (based on starch) of the Mn catalyst (Interox Cat. D350) was added followed by 25.4 ml of a hydrogen peroxide solution containing 30% hydrogen peroxide. During the oxidation the pH was maintained at 11.3 by the addition of a 4.4 wt. % sodium hydroxide solution. Once the reaction was complete, i.e. no peroxide was detectable with potassium iodide-starch paper, the reaction mixture was neutralized to pH 5.5 by the addition of 10 N H.sub.2SO.sub.4, whereupon the product was dewatered and washed before drying.

EXAMPLE 8

[0059] The oxidized starch derivatives from the examples 6 and 7 were dissolved in 35% (dry matter) on a boiling water bath with high speed stirring (600-1200 rpm). After 30 minutes the solutions were stored at 50 C. and the viscosity was measured after 0, 1, 2, and 4 hours (Brookfield LVF, 60 rpm). The results of the different oxidized starches is shown in table 2.

TABLE-US-00002 TABLE 2 Viscosity 35%; 50 C. (mPa .Math. s) Time (h) Example 6 Example 7 0 280 220 1 1520 260 2 6500 260 4 >10000 280

[0060] The example 7 exhibits excellent viscosity stability in solution.

EXAMPLE 9

[0061] 1.0 kg of amylopectin potato starch (0.82 kg dry matter, Eliane potato starch from AVEBE; amylopectin content >98 wt. % based on dry substance of starch) was suspended in 1.0 kg of water. The temperature of the suspension was increased to 35 C. The pH was set at 9.0 by the addition of a 4.4 wt. % sodium hydroxide solution. 41.8 ml of a sodium hypochlorite solution containing 179.5 g/liter of active chlorine was added. During the oxidation the pH was maintained at 9.0 by the addition of a 4.4 wt. % sodium hydroxide solution. Once the reaction was complete, i.e. no chlorine was detectable with potassium iodide-starch paper, the pH was increased to 10.5 by the addition of a 4.4 wt. % sodium hydroxide solution. After one hour of alkaline post-treatment 5 ml sodium hypochlorite solution was added for decoloration. The reaction mixture was neutralized to pH 5.5 by the addition of 10 N H.sub.2SO.sub.4, whereupon the product was dewatered and washed before drying.

EXAMPLE 10

[0062] A blend of 0.5 kg of regular potato starch (0.41 kg dry matter, food grade potato starch from AVEBE; amylopectin content 81 wt. % based on dry substance of starch) and 0.5 kg amylopectin potato starch (0.41 kg dry matter, Eliane potato starch from AVEBE; amylopectin content >98 wt. % based on dry substance of starch) was suspended in 1.0 kg of water. The temperature of the suspension was increased to 35 C. The pH was set at 9.0 by the addition of a 4.4 wt. % sodium hydroxide solution. 47.9 ml of a sodium hypochlorite solution containing 179.5 g/liter of active chlorine was added. During the oxidation the pH was maintained at 9.0 by the addition of a 4.4 wt. % sodium hydroxide solution. Once the reaction was complete, i.e. no chlorine was detectable with potassium iodide-starch paper, the pH was increased to 10.5 by the addition of a 4.4 wt. % sodium hydroxide solution. After one hour of alkaline post-treatment 5 ml sodium hypochlorite solution was added for decoloration. The reaction mixture was neutralized to pH 5.5 by the addition of 10 N H.sub.2SO.sub.4, whereupon the product was dewatered and washed before drying.

EXAMPLE 11

[0063] The oxidized starch derivatives from the examples 9 and 10 were dissolved in 25% (dry matter) on a boiling water bath with high speed stirring (600-1200 rpm). After 30 minutes solutions were prepared with the following concentrations 2.5%, 5%, and 7.5% for both starches. The Brookfield viscosity was measured as describe in Example 5. The starch solutions were applied onto 80 gsm base paper from Burgo Ardennes using a puddle type size press from the Dixon coater at a speed of 50 m/min. The paper was dried to a moisture content of 5%. Before paper testing the papers were conditioned at 23 C. and 50% relative humidity for at least three days.

[0064] The sheet weight was measured according to NEN-EN-ISO 536. Dry pick resistance was measured according to NEN-ISO-3783, using an IGT pick tester type AIC 2-5. The test is run with 8 m oil thickness on 1 cm disks, using a middle viscous IGT oil at a speed of 5 m/s. The point where the pick resistance starts is multiplied with the viscosity of the oil (520) and expressed as VVP (viscosity velocity product). The results of the different oxidized starches is shown in table 3.

TABLE-US-00003 TABLE 3 Concentration 0% 2.5% 5% 7.5% Example 9 Viscosity 3.1 9.9 15.0 Example 10 Viscosity 2.9 9.8 16.7 Example 9 Sheet weight 86.6 87.1 87.7 88.1 Example 10 Sheet weight 86.6 86.9 87.8 88.2 Example 9 ICT pick 800 810 820 860 Example 10 ICT pick 800 930 950 950

EXAMPLE 12

[0065] A blend of 0.47 kg of regular tapioca starch (0.41 kg dry matter, lot 21204637 from Siam Quality Starch Co., Ltd.; amylopectin content 83 wt. % based on dry substance of starch) and 0.5 kg amylopectin potato starch (0.41 kg dry matter, Eliane potato starch from AVEBE; amylopectin content >98 wt. % based on dry substance of starch) was suspended in 1.0 kg of water. The temperature of the suspension was increased to 35 C. The pH was set at 9.0 by the addition of a 4.4 wt. % sodium hydroxide solution. 59.9 ml of a sodium hypochlorite solution containing 179.5 g/liter of active chlorine was added. During the oxidation the pH was maintained at 9.0 by the addition of a 4.4 wt. % sodium hydroxide solution. Once the reaction was complete, i.e. no chlorine was detectable with potassium iodide-starch paper, the pH was increased to 10.5 by the addition of a 4.4 wt. % sodium hydroxide solution. After one hour of alkaline post-treatment 5 ml sodium hypochlorite solution was added for decoloration. The reaction mixture was neutralized to pH 5.5 by the addition of 10 N H.sub.2SO.sub.4, whereupon the product was dewatered and washed before drying.

EXAMPLE 13

[0066] A blend of 0.5 kg of regular potato starch (0.41 kg dry matter, food grade potato starch from AVEBE; amylopectin content 81 wt. % based on dry substance of starch) and 0.47 kg waxy maize starch (0.41 kg dry matter, Meritena 300 from Amylum; amylopectin content >95 wt. % based on dry substance of starch) was suspended in 1.0 kg of water. The temperature of the suspension was increased to 35 C. The pH was set at 9.0 by the addition of a 4.4 wt. % sodium hydroxide solution. 100.3 ml of a sodium hypochlorite solution containing 179.5 g/liter of active chlorine was added. During the oxidation the pH was maintained at 9.0 by the addition of a 4.4 wt. % sodium hydroxide solution. Once the reaction was complete, i.e. no chlorine was detectable with potassium iodide-starch paper, the pH was increased to 10.5 by the addition of a 4.4 wt. % sodium hydroxide solution. After one hour of alkaline post-treatment 5 ml sodium hypochlorite solution was added for decoloration. The reaction mixture was neutralized to pH 5.5 by the addition of 10 N H.sub.2SO.sub.4, whereupon the product was dewatered and washed before drying.

EXAMPLE 14

[0067] The oxidized starch derivatives from the examples 12 and 13 were dissolved in 25% (dry matter) on a boiling water bath with high speed stirring (600-1200 rpm). After 30 minutes the solutions were stored at 50 C. and the viscosity was measured after 0, 1, 2, and 4 hours (Brookfield LVF, 60 rpm). The results of the different oxidized starches is shown in table 4.

TABLE-US-00004 TABLE 4 Viscosity 25%; 50 C. (mPa .Math. s) Time (h) Example 12 Example 13 0 250 310 1 420 540 2 470 1700 4 580 3750

[0068] The blend of example 13 exhibits very poor viscosity stability in solution.