RICE BRAN WAX OXIDATES WITH LOW ACID VALUE

Abstract

The invention relates to rice bran wax oxidates with a low acid value, to a process for their production and to their use for agricultural or forestry purposes, as an additive in plastics processing, in care products, in printing inks and/or in paints, and to saponified rice bran wax oxidates produced by saponifying the claimed rice bran wax oxidates.

Claims

1. A process for producing rice bran wax oxidates (O) having an acid number of less than 40 mg KOH/g, comprising the steps of: i) providing a rice bran wax (R) containing less than 5% by weight, based on the total weight of the rice bran wax (R), of polyesters formed from polyhydric alcohols and aliphatic carboxylic acids having 8 to 20 carbon atoms; ii) providing a mixture (M) of chromium trioxide and sulfuric acid; iii) performing the oxidation of the rice bran wax (R) by reacting the rice bran wax (R) with the mixture (M) while stirring and at a temperature of 80 to 150? C., in order to obtain a rice bran wax oxidate (O); iv) stopping the reaction and leaving the reaction mixture obtained in step iii) to stand until the organic phase has separated from the aqueous phase; v) separating off the organic phase; vi) optionally removing residues containing chromium compounds from the organic phase in order to obtain the rice bran wax oxidate (O) in purified form; and vii) optionally repeating the sequence of steps ii) to vi) using the rice bran wax oxidate (O), optionally in purified form, rather than the rice bran wax (R), wherein the oxidation in step iii) is effected over a period of 1 to 8 hours.

2. The process according to claim 1, wherein the weight ratio of the total amount of chromium trioxide used to rice bran wax (R) used is from 1:5 to 6:5.

3. The process according to claim 1, wherein the removing of residues containing chromium compounds in step vi) is performed and comprises the washing of the organic phase with an aqueous solution of oxalic acid and/or sulfuric acid.

4. The process according to claim 1, wherein the removing of residues containing chromium compounds in step vi) is performed and comprises the washing of the organic phase with water.

5. The process according to claim 1, wherein the removing of residues containing chromium compounds in step vi) is performed and comprises centrifuging of the organic phase.

6. The process according to claim 1, wherein the concentration of chromium trioxide in the mixture (M) is from 50 to 200 g/I.

7. The process according to claim 1, wherein the oxidation in step iii) is performed over a period of 2 to 5 hours.

8. The process according to claim 1, wherein the stirrer speed in step iii) is between 100 and 500 rpm.

9. The process according to claim 1, wherein no additional oxidation promoters are added to the reaction mixture.

10. A rice bran wax oxidate (O) having an acid number of less than 40 mg KOH/g, prepared by the process according to claim 1.

11. The rice bran wax oxidate (O) according to claim 10, having a proportion of polyesters formed from polyhydric alcohols and aliphatic carboxylic acids having 22 to 36 carbon atoms of less than 5% by weight, based on the total weight of the rice bran wax oxidate (O).

12. The rice bran wax oxidate (O) according to claim 10, comprising: a) 3% to 25% by weight, based on the total weight of the rice bran wax oxidate (O), of free aliphatic carboxylic acids having 8 to 36 carbon atoms; b) 0% to 10% by weight, based on the total weight of the rice bran wax oxidate (O), of free aliphatic alcohols having 24 to 36 carbon atoms; c) 0% to 5% by weight, based on the total weight of the rice bran wax oxidate (O), of free aliphatic dicarboxylic acids having 10 to 30 carbon atoms; d) 50% to 97% by weight, based on the total weight of the rice bran wax oxidate (O), of genuine esters having 42 to 64 carbon atoms; and e) 0% to 15% by weight, based on the total weight of the rice bran wax oxidate (O), of further natural constituents present in the rice bran wax.

13. A rice bran wax oxidate (O) having an acid number of less than 40 mg KOH/g and a proportion of polyesters formed from polyhydric alcohols and aliphatic carboxylic acids having 22 to 36 carbon atoms of less than 5% by weight, based on the total weight of the rice bran wax oxidate (O), comprising: a) 3% to 25% by weight, based on the total weight of the rice bran wax oxidate (O), of free aliphatic carboxylic acids having 8 to 36 carbon atoms; b) 0% to 10% by weight, based on the total weight of the rice bran wax oxidate (O), of free aliphatic alcohols having 24 to 36 carbon atoms; c) 0% to 5% by weight, based on the total weight of the rice bran wax oxidate (O), of free aliphatic dicarboxylic acids having 10 to 30 carbon atoms; d) 50% to 97% by weight, based on the total weight of the rice bran wax oxidate (O), of genuine esters having 42 to 64 carbon atoms; and e) 0% to 15% by weight, based on the total weight of the rice bran wax oxidate (O), of further natural constituents present in the rice bran wax.

14. The rice bran wax oxidate (O) according to claim 10, containing not more than 5% by weight, based on the total weight of the rice bran wax oxidate (O), of lignoceric acid.

15. A saponified rice bran wax oxidate (V), produced by saponifying the rice bran wax oxidate (O) according to claim 10 with a basic metal salt, preferably an alkali metal hydroxide and/or alkaline earth metal hydroxide.

16. Use of the saponified rice bran wax oxidate (V) according to claim 15 for agricultural or forestry purposes, as additive in plastics processing, in care products, in printing inks and/or in paints.

17. Use of the rice bran wax oxidate (O) according to claim 10 for agricultural or forestry purposes, as additive in plastics processing, in care products, in printing inks and/or in paints.

18. The rice bran wax oxidate (O) according to claim 13, containing not more than 5% by weight, based on the total weight of the rice bran wax oxidate (O), of lignoceric acid.

19. A saponified rice bran wax oxidate (V), produced by saponifying the rice bran wax oxidate (O) according to claim 13 with a basic metal salt, preferably an alkali metal hydroxide and/or alkaline earth metal hydroxide.

Description

EXAMPLES 1 TO 9

[0100] A 3 I reaction vessel equipped with stirrer, temperature sensor, dropping funnel and reflux condenser was initially charged with the amount of chromium trioxide in sulfuric acid (concentration: 100 g CrO.sub.3/I) specified in Table 4, and heated to 100? C. Subsequently, molten (90? C.) rice bran wax was added in portions in the raw state. The temperature of the reaction mixture was adjusted to 110? C., and the reaction mixture was stirred with a precision glass stirrer at about 200 rpm for 4 h. The heating and stirring were switched off. As soon as the phases had separated, the aqueous phase was separated off.

[0101] The organic phase was freed of chromium residues by washing with an aqueous solution of oxalic acid and sulfuric acid and then by washing with water, discharged into warm centrifuge bottles and centrifuged.

[0102] In Examples 2, 3, 4 and 9 (comparative examples), no phase separation was detected after the oxidation. The conditions of the oxidations and properties of the rice bran wax oxidates are reported in Table 4.

[0103] The chain length distribution measured for Example 1 is shown in FIG. 1.

TABLE-US-00004 TABLE 4 Example 1 3* 4* 5 6 7 8* RBW 1 200 200 200 [g] RBW 2 200 [g] RBW 3 200 [g] RBW 4 200 [g] RBW 5 200 200 [g] CrO.sub.3/ 1.0 1.0 1.0 1.0 1.0 0.8 1.4 0.8 H.sub.2SO.sub.4 [I] Reaction 4 4 4 4 4 4 4 4 time [h] Reaction 110 110 110 110 110 110 110 110 temperature [? C.] Time [min] 2 300 4 1 until phase separation Properties of the oxidized products (methods, abbreviations and units in Table 1) AN 19 35 14 27 SN 89 113 89 100 DP 78 76 78 78 MP 81 80 81 81 EF ?220.0 ?206.6 ?219.3 ?220.8 TGA 6.79/ 6.17/ 4.13/ 7.55/ 17.86 15.04 17.79 25.59 ICN 1.6 17.6 9 1.4 YI 10 86 56 8 NPI 1 3 1 2 *Comparative example; no phase separation

EXAMPLES 10 AND 11

[0104] In a 11 reaction vessel equipped with stirrer, temperature sensor, dropping funnel and reflux condenser, the rice bran wax oxidate from Example 1 is melted under a nitrogen atmosphere and admixed with the amount of Ca(OH).sub.2specified in Table 5. The reaction mixture is stirred until the specified acid number has been attained and then the reaction mixture is pressure-filtered in the hot state.

TABLE-US-00005 TABLE 5 Example 10 11 Rice bran wax oxidate [g] 500 500 Ca(OH).sub.2 [g] 6.8 3.5 Reaction time [min] 30 20 Reaction temperature [? C.] 120 120 Properties of the saponified products (methods, abbreviations and units in Table 1) AN 2 11 SN 88 86 DP 95 91 MP 82 82 EF ?212.4 ?212.1 TGA 2.80/6.10 4.66/15.77 CaC 0.68 0.38