ACYLATED STARCH DERIVATIVES AND USE THEREOF

Abstract

The present invention concerns the use of starch derivatives, wherein the starch derivative is partially acetylated and partially acylated with at least one fatty acid, as additive in coating compositions, and starch derivatives which are partially acetylated and partially acylated with at least one fatty acid at least one fatty acid, wherein the MW of the starch derivatives is from 3.000 to 50.000 g/mol.

Claims

1. A coating comprising an additive comprising: at least one starch derivative, wherein the at least one starch derivative is partially acetylated and partially acylated with at least one fatty acid.

2. The coating according to claim 1, wherein the coating is an UV-curing composition.

3. The composition according to claim 2, wherein the UV-curing composition is an UV-curing printing ink.

4. The composition according to claim 1, wherein the at least one fatty acid is chosen from C12-C18 fatty acids, wherein the at least one fatty acid is an unsaturated fatty acid or a saturated fatty acid.

5. The composition according to claim 1, wherein a degree of acetyl substitution of the at least one starch derivative, DS.sub.(acetyl), is from 1.4 to 2.85.

6. The composition according to claim 1, wherein a degree of a combined DS.sub.(fatty acid) is from 0.01 to 1.2, preferably from 0.1 to 0.3.

7. The composition according to claim 1, wherein T.sub.g of the at least one starch derivative is from 30° C. to 130° C.

8. The composition according to claim 1, wherein a molecular weight (MW) of the at least one starch derivative is from 3.000 to 50.000 g/mol.

9. A starch derivative which is partially acetylated and partially acylated with at least one fatty acid, wherein a molecular weight (MW) of the starch derivative is from 3.000 to 50.000 g/mol.

10. The starch derivative according to claim 9, wherein the at least one fatty acid is chosen from C12-C18 fatty acids, wherein the at least one fatty acid is unsaturated fatty acid or a saturated fatty acids.

11. The starch derivative according to claim 9, wherein a degree of acetyl substitution of the at least one starch derivative, DS.sub.(acetyl), is from 1.4 to 2.85.

12. The starch derivative according to claim 9, wherein a degree of a combined DS.sub.(fatty acid) is from 0.01 to 1.2, preferably from 0.1 to 0.3.

13. The starch derivative according to claim 9, wherein T.sub.g of the starch derivative is from 30° C. to 130° C.

14. A method comprising: applying a cured coating comprising at least one starch derivative which is partially acetylated and partially acylated with at least one fatty acid; and curing the coating to obtain a cured coating.

15. A product comprising a cured coating comprising at least one starch derivative which is partially acetylated and partially acylated with at least one fatty acid.

16. A UV curable coating comprising at least one starch derivative which is partially acetylated and partially acylated with at least one fatty acid.

17. (canceled)

Description

EXAMPLES

[0039] Starch acetate with a DS.sub.(acetyl) of 2,1 was prepared according to example 1 of WO2015055741, starting form waxy maize. Other starch acetates are prepared according to the similar procedure, starting from appropriate starch sources.

Example 1: 1-(1H-imidazol-1-yl)hexadecan-1-one

[0040] 15.8 g palmitic acid were solved in CH.sub.2Cl.sub.2 (290 mL). While stirring, 15 g N,N-carbonyldiimidazole (CDI, 1.1 eq) were added at room temperature and stirred for 24 h. The mixture was extracted several times with H.sub.2O, and the organic phase was dried over MgSO.sub.4. After evaporation of the solvent, 17.7 g product (93%) of product were obtained.

Example 2

[0041] The starch acetate of DS 2,1 was solved in DMSO (50% w/w), heated to 80° C. and the product of example 1 above was added in portions (0.34 eq in relation to the free hydroxyl groups of the starch acetate). The mixture was stirred for 4 hours. After cooling to room temperature, H.sub.2O was added until the product precipitated quantitatively. Approximately half the volume of DMSO was needed for this effect. The solid was filtered, washed with water, dried in vacuo and washed in hexanes. The product was dried in at 70° C. A starch derivative with a DS.sub.(acetyl)=2.1, DS.sub.(palmitic acid)=0.1, T.sub.g=85° C. and MW=13.100 g/mol was obtained.

Example 3

[0042] Similar to the process of example 2, a product starting from waxy maize starch, was obtained DS.sub.(acetyl)=2.5, DS.sub.(mixed FA)<0.2 and MW=2973 g/mol was obtained (PA1). The mixture of fatty acids FA employed contained oleic acid, stearic acid, linolenic acid, palmitoleic acid and palmitic acid.

Example 4

[0043] Similar to the process of example 2, a product starting from pea starch, was obtained DS.sub.(acetyl)=2.5, DS.sub.(palmitic acid)=0.1 and MW=7850 g/mol was obtained (PA2).

Example 5 (Formulation for UV Coating)

[0044]

TABLE-US-00001 Formulation Ref 1 Starch acetate derivative (of — 22.2 w % example PA2) LR8986 (epoxy oligomer. 67.2 w % 51.7 w % obtainable from BASF) SR306 (Tripropyleneglycol 28.8 w % 22.2 w % diacrylate monomer from Sartomer) Initiator 1   2 w %   2 w % Initiator 2   2 w %   2 w % Initiator 1: Benzophenonp. Initiator 2: 1-Hydroxycyclohexylphenylketon

[0045] Initiator 1 and initiator 2 were mixed. PA2 was solved at 50° C. in SR306 and added with stirring to the initiator mixture. LR8986 was added. The mixture was homogenized by stirring for about 5 to 15 minutes. If necessary, the mixture was left to sit unstirred to eliminate air bubbles.

[0046] The mixtures were applied by frame applicator BYK-5361 as 8 mil (0.2 mm) coatings to a steel surface and irradiated in a curing chamber (225 mW/cm.sup.2 UV-A) until full curing was achieved. Irradiation time: 4 times 45 seconds.

[0047] The coatings were submitted to a pencil test according to the procedure ISO 15184 with a Wolf Kilburn Pencil Hardness tester.

TABLE-US-00002 ref 1 Hardness H 3H Thickness mil 3.5 3.5

[0048] It was observed that the addition of the starch acetate derivative PA2 enhances the pencil hardness of the coating.

Example 6

[0049] The starch derivative obtained in example 2 (denoted as PA) was compared with a fatty acid unmodified starch acetate derivative (DS(acetyl)=2.4, MW=35.210 g/mol, denoted as SA). The formulation contained 50 w % PM acetate (1-Methoxy-2-propyl acetate), 10 w % PA or SA, 7 w % Paraloid B-66, 3 w % triethyl citrate and 30 w % MEK (methyl ethyl ketone). The formulations were applied on glass and steel test panels and air dried.

[0050] The table below summarizes the results obtained by immersing the samples into de-ionized water and NaCl solution. The sample treated with an acetyl/fatty acid starch derivative showed an improved performance, with 5 denoting excellent resistance as assessed by visual inspection of the sample (corrosion of treated surface), and 1 denoting particularly poor resistance.

TABLE-US-00003 De-ionized water 5% NaCl in water 6 h 24 h 48 h 6 h 24 h 48 h SA 5 4 2 5 4 2 PA 5 5 5 5 5 3

Example 7 (Test on Water Uptake at 21° C., 60% rH)

[0051] PA1 and PA2 were tested against a SA (waxy maize, DS 2.4, MW=8000 g/mol) without fatty acid acylation. All starch derivatives were tested as neat pulverous substances treated after synthesis in a mortar.

TABLE-US-00004 Time (h) SA PA1 PA2 0 0.2 0.34 0.22 1 2.8 1.04 1.2 2 3.48 1.78 1.26 3 3.76 1.58 1.38 19.6 4.47 1.65 1.4 92.6 4.74 1.9 1.26

[0052] Water uptake is significantly reduced in the derivatives. Coatings comprising starch derivatives according to the present invention can display a reduced water uptake tendency and can have a reduced tendency to develop haziness. Coatings comprising starch derivatives according to the present invention can protect surfaces from humidity, in particular surfaces of electronic elements.