Partially saponified rice bran wax oxidates

Abstract

The invention relates to partially saponified rice bran wax oxidates, to a process for the production of these products and to their use for agriculture or forestry purposes, as an additive in plastics processing, in care products, in printing inks and/or in paints.

Claims

1. A process for producing a partly saponified rice bran wax oxidate (V), comprising the steps of: i) providing a rice bran wax (R) containing less than 20% 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 at a temperature of 90 to 150 C., in order to obtain a reaction mixture containing rice bran wax oxidate (O); iv) ending the reaction and leaving the reaction mixture obtained in step iii) to stand until an organic phase has separated from an 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; vii) optionally repeating the sequence of steps ii) to vi) using the rice wax oxidate (O), optionally in purified form, rather than the rice bran wax (R); and viii) saponifying the rice bran wax oxidate (O), optionally in purified form, by reacting it with a basic salt, wherein no alcohol component is added to the reaction mixture in step iii) to step viii).

2. The process according to claim 1, wherein the oxidation in step iii) is performed over a period of 2 to 9 hours.

3. The process according to claim 1, wherein the sequence of steps ii) to vi) is repeated one to four times, and wherein the rice bran wax oxidate (O) obtained in step vii) or optionally viii), optionally in purified form, is added in place of the rice bran wax (R).

4. The process according to claim 1, wherein a weight ratio of the total amount of chromium trioxide used to rice bran wax (R) used is from 1:1 to 3:1.

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

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

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

8. The process according to claim 1, wherein chromium trioxide is present in the mixture (M) at a concentration of from 50 to 200 g/L.

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

10. The process according to claim 1, wherein the saponifying in step viii) is performed over a period of 0.5 to 10 h at a temperature of 90 to 150 C.

11. The process according to claim 1, wherein no additional oxidation promoters are added to the reaction mixture in any of the steps.

12. A partly saponified rice bran wax oxidate (V) comprising the following components: a) 30% to 85% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of genuine esters having 42 to 64 carbon atoms; b) 0% to 70% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of salts of aliphatic carboxylic acids having 8 to 36 carbon atoms; and c) 0% to 5% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of polyesters formed from polyhydric alcohols and aliphatic carboxylic acids having 22 to 36 carbon atoms.

13. The partly saponified rice bran wax oxidate (V) of claim 12 further comprising: d) 5% to 40% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of free aliphatic monocarboxylic acids having 8 to 36 carbon atoms, of which not more than 10% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), is lignoceric acid; e) 0% to 10% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of free aliphatic alcohols having 24 to 36 carbon atoms; and f) 0% to 5% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of free aliphatic dicarboxylic acids having 10 to 30 carbon atoms; and g) 0% to 15% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of natural constituents of rice bran wax other than a) to f).

14. The partly saponified rice bran wax oxidate (V) of claim 12 comprising: a) 40% to 85% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of genuine esters having 42 to 64 carbon atoms; b) 10% to 30% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of salts of aliphatic carboxylic acids having 8 to 36 carbon atoms; c) 0% to 3% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of polyesters formed from polyhydric alcohols and aliphatic carboxylic acids having 22 to 36 carbon atoms; d) 5% to 35% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of free aliphatic monocarboxylic acids having 8 to 36 carbon atoms, of which not more than 10% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), is lignoceric acid; e) 0% to 7% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of free aliphatic alcohols having 24 to 36 carbon atoms; and f) 0% to 4% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of free aliphatic dicarboxylic acids having 10 to 30 carbon atoms; and g) 0% to 15% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of natural constituents of rice bran wax other than a) to f).

15. The partly saponified rice bran wax oxidate (V) of claim 12 comprising: a) 50% to 85% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of genuine esters having 42 to 64 carbon atoms; b) 10% to 20% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of salts of aliphatic carboxylic acids having 8 to 36 carbon atoms; c) 0% to 1% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of polyesters formed from polyhydric alcohols and aliphatic carboxylic acids having 22 to 36 carbon atoms; d) 5% to 30% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of free aliphatic monocarboxylic acids having 8 to 36 carbon atoms, of which not more than 10% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), is lignoceric acid; e) 0% to 5% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of free aliphatic alcohols having 24 to 36 carbon atoms; and f) 0% to 3% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of free aliphatic dicarboxylic acids having 10 to 30 carbon atoms; and g) 0% to 15% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of natural constituents of rice bran wax other than a) to f).

16. The partly saponified rice bran wax oxidate (V) according to claim 12, wherein the partly saponified rice bran wax oxidate has a saponification number of no more than 79.

17. The partly saponified rice bran wax oxidate (V) according to claim 12, wherein the partly saponified rice bran wax oxidate has a mass loss of less than 10%, upon heating to 300 C. at a rate of 5 C./min, as measured according to DIN 51006 (2005).

18. The partly saponified rice bran wax oxidate (V) according to claim 12, wherein the partly saponified rice bran wax oxidate (V) is prepared by a process comprising the steps of i) providing a rice bran wax (R) containing less than 20% 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 at a temperature of 90 to 150 C., in order to obtain a reaction mixture containing rice bran wax oxidate (O); iv) ending the reaction and leaving the reaction mixture obtained in step iii) to stand until an organic phase has separated from an 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; vii) optionally repeating the sequence of steps ii) to vi) using the rice wax oxidate (O), optionally in purified form, rather than the rice bran wax (R); and viii) saponifying the rice bran wax oxidate (O), optionally in purified form, by reacting it with a basic salt, wherein no alcohol component is added to the reaction mixture in step iii) to step viii).

19. A plastic composition, a care product, a printing ink, a paint, or an agricultural composition comprising the partially saponified rice bran wax oxidate of claim 12.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The FIGURE depicts the chain length distributions of the constituents of rice bran wax oxidates prepared according to the process described herein.

(2) The invention therefore provides a process for producing a partly saponified rice bran wax oxidate (V), comprising the steps of: i) providing a rice bran wax (R) containing less than 20% 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 while stirring at a temperature of 90 to 150 C., in order to obtain a rice bran wax oxidate (O); iv) ending 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, 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), viii) saponifying the rice bran wax oxidate (O), optionally in purified form, by reacting it with a basic salt, preferably a basic metal salt, especially selected from alkali metal hydroxides and alkaline earth metal hydroxides, wherein no alcohol component is added to the reaction mixture in step iii) to step viii), preferably in all steps of the entire process.

(3) The rice bran wax (R) provided in step i) may be any rice bran wax, provided that it has a proportion of polyesters formed from polyhydric alcohols and aliphatic carboxylic acids having 8 to 20 carbon atoms of less than 20% by weight, preferably less than 5% by weight, more preferably 0.1% to 2% by weight, based on the total weight of the rice bran wax (R).

(4) The desired proportion of polyesters formed from polyhydric alcohols and aliphatic carboxylic acids having 8 to 20 carbon atoms may already be present in the rice bran wax in the raw state, but may also be adjusted by a pretreatment of the rice bran wax. Preferably, the proportion is already present in the rice bran wax (R) in the raw state. In this case, it is preferable that the rice bran wax (R) is not pretreated.

(5) If, by contrast, proportions of polyesters formed from polyhydric alcohols and aliphatic carboxylic acids having 8 to 20 carbon atoms are 20% by weight or higher, the rice bran wax (R) has to be pretreated before it is provided in step i). In this case, it is advantageous when the pretreatment does not include a saponification of the esters present in the rice bran wax (R).

(6) Instead, preference is given to an extraction of the polyesters formed from polyhydric alcohols and aliphatic carboxylic acids having 8 to 20 carbon atoms with one or more organic solvents, wherein the extraction is performed until the desired proportion of polyesters formed from polyhydric alcohols and aliphatic carboxylic acids having 8 to 20 carbon atoms of less than 20% by weight is attained. Any organic solvents that can dissolve oils and fats are suitable, for example ethyl acetate or acetone, preferably ethyl acetate.

(7) The polyesters formed from polyhydric alcohols and aliphatic carboxylic acids having 8 to 20 carbon atoms are preferably di- and triglycerides of aliphatic carboxylic acids having 8 to 20 carbon atoms, especially oils naturally present in rice bran, in particular rice bran oil. Correspondingly, the extraction with an organic solvent may be a deoiling. In this case, the proportion of polyesters formed from polyhydric alcohols and aliphatic carboxylic acids having 8 to 20 carbon atoms of less than 20% by weight may also be referred to as the oil content of the rice bran wax.

(8) It is preferable that the rice bran wax (R), irrespective of the proportion of polyesters formed from polyhydric alcohols and aliphatic carboxylic acids having 8 to 20 carbon atoms in the raw state, is not pretreated by saponification at any time prior to the oxidation.

(9) The mixture (M) of chromium trioxide and sulfuric acid provided in step ii) may be any mixture, provided that it is capable of oxidizing oxidizable constituents of rice bran wax. Frequently, such mixtures of chromium trioxide and sulfuric acid are also referred to as chromosulfuric acid. The sulfuric acid is concentrated sulfuric acid having a proportion of sulfuric acid of at least 90% by weight, preferably at least 96% by weight, more preferably at least 99% by weight. This may optionally be fuming sulfuric acid, i.e. additionally contain sulfur trioxide. The concentration of chromium trioxide in the mixture (M) is preferably 50 to 200 g/l, more preferably 70 to 150 g/l, most preferably 80 to 120 g/l.

(10) In step iii) of the process according to the invention, the oxidation of the rice bran wax (R) is performed by reacting the rice bran wax (R) with the mixture (M) while stirring and at a temperature of 80 to 150 C., preferably of 90 to 140 C., more preferably of 105 to 130 C., in order to obtain a rice bran wax oxidate (O).

(11) The weight ratio of the total amount of chromium trioxide used to rice bran wax (R) used is preferably from 1:1 to 3:1, especially from 1.1:1 to 3:1, more preferably from 1.2:1 to 2.5:1.

(12) This step may optionally be divided into two or more steps. For example, step iii) may comprise the initial charging of the mixture (M) and subsequently adding the rice bran wax (R). Alternatively, step iii) may comprise the initial charging of the rice bran wax (R) and subsequently adding the mixture (M). In these cases, the addition of the respective second component (R) or (M) can be effected, for example, in portions, continuously or in one batch, preferably in portions or continuously, more preferably in portions.

(13) Optionally, the temperature of the rice bran wax (R) and/or of the mixture (M) during the addition may deviate from the reaction temperature, and may be adjusted only after addition of the second component to the required value of 80 to 150 C., preferably of 90 to 140 C., more preferably of 105 to 130 C. For example, the temperature on addition may have a value of 70 to 130 C., preferably of 80 to 110 C. Preferably, the rice bran wax (R) is in molten form during the addition.

(14) In one embodiment, the mixture (M) of chromium trioxide and sulfuric acid provided is initially charged and heated to a temperature of 70 to 130 C., and the rice bran wax (R) is added in portions in the solid state. On completion of addition, the temperature is adjusted to 80 to 150 C. and the oxidation is performed.

(15) In another embodiment, the mixture (M) of chromium trioxide and sulfuric acid provided is initially charged and heated to a temperature of 70 to 130 C., and the rice bran wax (R) is added in portions in the molten state, preferably at a temperature of 70 to 130 C. On completion of addition, the temperature is adjusted to 80 to 150 C. and the oxidation is performed.

(16) In a further embodiment, the rice bran wax (R) is initially charged and melted at a temperature of 70 to 130 C., and the mixture (M) of chromium trioxide and sulfuric acid is added in portions while cold. On completion of addition, the temperature is adjusted to 80 to 150 C. and the oxidation is performed.

(17) In a further embodiment, the rice bran wax (R) is initially charged and melted at a temperature of 70 to 130 C., and the mixture (M) of chromium trioxide and sulfuric acid is added in portions while hot, preferably at a temperature of 70 to 130 C. On completion of addition, the temperature is adjusted to 80 to 150 C. and the oxidation is performed.

(18) In a further embodiment, rice bran wax (R) and the mixture (M) of chromium trioxide and sulfuric acid are initially charged together at room temperature and heated gradually to a temperature of 80 to 150 C., and the oxidation is performed at that temperature.

(19) At least the oxidation at 80 to 150 C., preferably also the addition of the rice bran wax (R) and/or of the mixture (M) takes place with stirring. The stirring can be effected here in any desired manner, for example with a mechanically driven stirrer, or a magnetically driven stirrer. The stirring is preferably effected with a mechanically driven stirrer, more preferably with a mechanically driven stirrer comprising a precision glass stirrer.

(20) The stirrer speed in step iii) is preferably within a range of 100 and 500 rpm (revolutions 30 per minute), more preferably from 120 to 300 rpm, most preferably from 170 to 250 rpm, since the mixing required for efficient oxidation is absent at a stirrer speed below 100 rpm and there is an elevated risk of an emulsion forming that cannot be separated again at a stirrer speed above 500 rpm.

(21) The oxidation of the rice bran wax in step iii) at the temperature of 90 to 150 C. is effected over a period of 1 to 12 hours, preferably of 6 to 10 hours, more preferably of 7 to 9 hours.

(22) It is also advantageous when no oxidation promoters are added to the reaction mixture of rice bran wax (R) and the mixture (M), since these can frequently lead to cleavage of the ester bonds, and the acid number in the rice bran wax oxidate (O) can therefore increase. Preference is therefore given to using no oxidation promoters, especially no oxidation promoters such as, for example, emulsifiers (e.g. alkanesulfonates, fluorinated alkanesulfonates), surfactants, polymeric surfactants, nitrogen-containing cationic surfactants, phase transfer catalysts, Fenton reagents, metal salts, hydrochloric acid or the like, in the oxidation.

(23) On attainment of the desired reaction time, in step iv), the reaction is ended and the reaction mixture is left to stand until the organic phase separates from the aqueous phase. Ending of the reaction is understood to mean that the stirring is stopped and the heating is ended. When this is done, the floating organic phase containing the rice bran wax oxidate (O) begins to separate from the falling aqueous phase containing sulfuric acid and chromium compounds. Before it is left to stand, it is optionally possible to transfer the reaction mixture into an apparatus which, after the separation of the organic phase from the aqueous phase, facilitates separating-off of the organic phase. One example of such an apparatus is a separating funnel. Other apparatuses for this purpose are known to the person skilled in the art and are employable here.

(24) In step v), the organic phase containing the rice bran wax oxidate mis separated off. This can be effected, for example, by means of a separating funnel. Alternatively, the floating organic phase can be skimmed off by suitable technical means. It is likewise possible to pour off the organic phase over an edge of the vessel. Methods of separating organic phases from aqueous phases after a phase separation are known in principle to the person skilled in the art and are employable here.

(25) In addition, it is optionally possible, in step vi), to subject the organic phase containing the rice bran wax oxidate that has been separated off to further workup in order to remove residues containing chromium compounds from the organic phase and hence to obtain the rice bran wax oxidate in purified form.

(26) The workup can be effected in any desired manner suitable for the separation of polar and/or water-soluble substances from organic substances. For example, the organic phase can be purified by chromatography or filtered through silica gel.

(27) Preference is given to the removing of residues containing chromium compounds by washing the organic phase with an aqueous solution of oxalic acid and/or sulfuric acid. Alternatively, residues containing chromium compounds can preferably be removed by washing the organic phase with water. Alternatively, residues containing chromium compounds can preferably be removed by centrifuging the organic phase. Washing is understood here in each case to mean the mixing of the organic phase with the respective washing medium, followed by phase separation according to steps iv) and v).

(28) In a preferred embodiment, residues containing chromium compounds are removed by washing the organic phase once or more than once with an aqueous solution of oxalic acid and sulfuric acid, followed by washing the organic phase once or more than once with water.

(29) In a further preferred embodiment, residues containing chromium compounds are removed by washing the organic phase once or more than once with an aqueous solution of oxalic acid and sulfuric acid, followed by centrifuging the organic phase.

(30) In a further preferred embodiment, residues containing chromium compounds are removed by washing the organic phase once or more than once with water, followed by centrifuging the organic phase.

(31) In a particularly preferred embodiment, residues containing chromium compounds are removed by washing the organic phase once or more than once with an aqueous solution of oxalic acid and sulfuric acid, followed by washing the organic phase once or more than once with water, followed by centrifuging the organic phase.

(32) Optionally, the sequence of steps ii) to vi) can be repeated up to four times, using the rice bran wax oxidate (O), optionally in purified form, rather than the rice bran wax (R). Preferably, in step vii), the sequence of steps ii) to vi) is repeated up to twice. More preferably, in step vii), the sequence of steps ii) to vi) is repeated not more than once. Most preferably, the sequence of steps ii) to vi) is not repeated. If the sequence of steps ii) to vi) is repeated, it is advantageous when, in each repetition, the oxidation of the rice bran wax in step iii) is effected at the temperature of 90 to 150 C. over a period of 1 to 12 hours, preferably of 6 to 10 hours, more preferably of 7 to 9 hours.

(33) In addition, it is advantageous in this case when, in the first performance of the sequence of steps ii) to vi), the weight ratio of chromium trioxide used to rice bran wax (R) used is at least 0.8:1, preferably at least 1:1, and, in every further repetition of the sequence of steps ii) to vi), the weight ratio of chromium trioxide used to rice bran wax (R) used is at least 0.4:1, preferably at least 0.5:1.

(34) The rice bran wax oxidate (O) obtained as intermediate by the process of the invention typically has an acid number (measured to DIN ISO 2114 of 2002) of greater than 45 mg KOH/g and less than 180 mg KOH/g, often of greater than 50 mg KOH/g and less than 150 mg KOH/g, and in one embodiment of greater than 70 mg KOH/g to less than 130 mg KOH/g.

(35) The rice bran wax oxidate (O) is saponified in step viii) by reaction with a basic metal salt in order to obtain a partly saponified rice bran wax oxidate (V).

(36) The basic metal salt is preferably selected from the group consisting of metal hydroxides (e.g. NaOH, KOH, Ca(OH).sub.2 and Zn(OH).sub.2, etc.), metal oxides (e.g. CaO, etc.), metal carbonates (e.g. Na.sub.2CO.sub.3, CaCO.sub.3, etc.) and aqueous alkalis (e.g. NaOH, KOH, etc.). Preference is given to alkali metal hydroxides and/or alkaline earth metal hydroxides, especially NaOH, KOH and/or Ca(OH).sub.2.

(37) The saponification in step viii) is preferably performed over a period of 0.5 to 10 hours, more preferably over a period of 1 to 8 hours, most preferably over a period of 2 to 6 hours. Typical reaction temperatures here are in the range from 90 to 150 C., preferably from 100 to 140 C., more preferably from 115 to 135 C.

(38) The invention further provides a partly saponified rice bran wax oxidate (V) comprising the following components: a) 30% to 85% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of genuine esters having 42 to 64 carbon atoms; b) 0% to 70% by weight, preferably 10% to 70% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of salts of aliphatic carboxylic acids having 8 to 36 carbon atoms; and c) 0% to 5% by weight, especially 0% to 3% by weight, most preferably 0% to 1% d) by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of polyesters formed from polyhydric alcohols and aliphatic carboxylic acids having 22 to 36 carbon atoms.

(39) The partly saponified rice bran wax oxidate (V) of the invention preferably comprises the following components: a) 30% to 85% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of genuine esters having 42 to 64 carbon atoms; b) 10% to 40% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of salts of aliphatic carboxylic acids having 8 to 36 carbon atoms; c) 0% to 5% by weight, especially 0% to 3% by weight, most preferably 0% to 1% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of polyesters formed from polyhydric alcohols and aliphatic carboxylic acids having 22 to 36 carbon atoms; d) 5% to 40% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of free aliphatic monocarboxylic acids having 8 to 36 carbon atoms, of which preferably not more than 10% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), is lignoceric acid; e) 0% to 10% by weight, preferably 0.1% to 5% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of free aliphatic alcohols having 24 to 36 carbon atoms; f) 0% to 5% by weight, preferably 0.1% to 5% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of free aliphatic dicarboxylic acids having 10 to 30 carbon atoms; g) 0% to 15% by weight, especially 0.1% to 10% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of natural constituents of rice bran wax other than a) to f).

(40) In a preferred embodiment, the partly saponified rice bran wax oxidate (V) of the invention comprises the following components: a) 40% to 85% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of genuine esters having 42 to 64 carbon atoms; b) 10% to 30% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of salts of aliphatic carboxylic acids having 8 to 36 carbon atoms; c) 0% to 3% by weight, especially 0% to 1% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of polyesters formed from polyhydric alcohols and aliphatic carboxylic acids having 22 to 36 carbon atoms; d) 5% to 35% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of free aliphatic monocarboxylic acids having 8 to 36 carbon atoms, of which preferably not more than 10% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), is lignoceric acid; e) 0% to 7% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of free aliphatic alcohols having 24 to 36 carbon atoms; f) 0% to 4% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of free aliphatic dicarboxylic acids having 10 to 30 carbon atoms; g) 0% to 15% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of natural constituents of rice bran wax other than a) to f).

(41) In a particularly preferred embodiment, the partly saponified rice bran wax oxidate (V) of the invention comprises the following components: a) 50% to 85% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of genuine esters having 42 to 64 carbon atoms; b) 10% to 20% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of salts of aliphatic carboxylic acids having 8 to 36 carbon atoms; c) 0% to 1% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of polyesters formed from polyhydric alcohols and aliphatic carboxylic acids having 22 to 36 carbon atoms; d) 5% to 30% by weight, based on the total weight of the partly saponified rice bran e) wax oxidate (V), of free aliphatic monocarboxylic acids having 8 to 36 carbon atoms, of which preferably not more than 10% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), is lignoceric acid; f) 0% to 5% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of free aliphatic alcohols having 24 to 36 carbon atoms; g) 0% to 3% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of free aliphatic dicarboxylic acids having 10 to 30 carbon atoms; h) 0% to 15% by weight, especially 0.1% to 10% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V), of natural constituents of rice bran wax other than a) to f). Preferably, lignoceric acid is present here in the partly saponified rice bran wax oxidate (V) to an extent of not more than 5% by weight, more preferably not more than 3% by weight, based on the total weight of the partly saponified rice bran wax oxidate (V).

(42) The proportions by weight and chain length distributions can be measured, for example, by means of gas chromatography.

(43) Particular preference is given to partly saponified rice bran wax oxidates (V) prepared by the process according to the invention.

(44) The rice bran wax oxidates according to the invention preferably have a needle penetration index (NPI) measured to DIN 51579 (2010) of less than 10 mm-1, preferably less than 5 mm-.sup.1, more preferably less than 3 mm.sup.1.

(45) The rice bran wax oxidates according to the invention preferably have a needle penetration index (NPI) measured to DIN 51579 of less than 10 mm-1, preferably less than 5 mm-1, more preferably less than 3 mm.sup.1.

(46) The partially saponified rice bran wax oxidates (V) according to the invention typically feature a dropping point (measured to DIN ISO 2176 (1997)) between 80 C. and 160 C., preferably between 90 C. and 150 C., more preferably between 100 C. and 140 C.

(47) In addition, the partly saponified rice bran wax oxidates (V) typically have a particularly light to white colour. This can be determined in accordance with APCS Cc 13e 92 (for example with Lovibond colorimeters). The partly saponified rice bran wax oxidates (V) according to the invention preferably have L* values in the CIE L*a*b* colour space of between 70 and 100, and a* values of less than 1.5 and b* values of less than 20.

(48) The partly saponified rice bran wax oxidates (V) according to the invention more preferably have L* values in the CIE L*a*b* colour space of between 80 and 100, and a* values of less than 1.2 and b* values of less than 16.

(49) In addition, the partly saponified rice bran wax oxidates (V) according to the invention have high thermal stabilities. Typically, the loss of mass of the partly saponified rice bran wax oxidates, measured to DIN 51006 (2005), on attainment of a temperature of 300 C. (heating rate of 5 C./min), is less than 10%, preferably less than 5%.

(50) The invention likewise provides for the use of the partly saponified rice bran wax oxidates (V) according to the invention for agricultural or forestry purposes, as additive in plastics processing, in care products, in printing inks and/or in paints. The invention is elucidated in detail by the examples and claims which follow.

(51) Substance Characterization

(52) The standard methods detailed in table 1, which are also employed in the characterization of montan waxes and montan wax derivatives, serve for determination of the indices of rice bran waxes, rice bran wax oxidates and further derivatives of the rice bran waxes.

(53) TABLE-US-00001 TABLE 1 Method Acid number (AN) Saponification number (SN) Dropping point (DP) [ C.] ISO 2176 Melting point (MP) [ C.] DIN EN ISO 11357-1 Enthalpy of fusion (EF) [J/g] DIN EN ISO 11357-1 Oil content (OC) [% by wt.] AOCS Ja 4-46 Thermogravimetric analysis (TGA) DIN 51006 [% by wt.] from 25 to 300 C. at 5 K/min, then 30 min at 300 C. Measurement of loss of mass on attainment of 300 C. and after 30 min at 300 C. CIEL*a*b* colour indices AOCS Cc 13e92 (with Lovibond colorimeter) Ca content [% by wt.] (CaC) DGF M-IV 4 Needle penetration index [mm.sup.1] (NPI) DIN 51579
Chain Length Distributions

(54) The chain length distributions of the constituents of the rice bran wax oxidates were determined by means of gas chromatography. The comparative substances used were wax acids and wax alcohols having carbon chain lengths between C6 and C36. Wax esters with C44 to C58 were prepared by combination of the model substances. In order to identify the peaks of the gas chromatograms of the rice bran waxes, a defined amount of the individual components in each case was added to a wax sample and a distinct increase in the area of the corresponding peak was observed. The measurement conditions are shown in table 2.

(55) TABLE-US-00002 TABLE 2 Column ZB-1 HT Phenomenex, length 15 m I.D. 0.25 mm, film 0.1 m Detector 380 C. FID Injector 300 C. split 1:100 Carrier gas helium Solvent toluene Concentration 30 mg/ml Injection 1 l volume Temperature 40 to 380 C. at 5 K/min; hold at program 380 C. for 10 min

(56) The proportion of metal salts of aliphatic carboxylic acids was calculated by the following formula:
Salts[% by wt.]=(m(acids in the rice bran wax oxidate)m(acids in the saponified s rice bran wax oxidate)+m(metal))/m(mixture)) where m(acids in the rice bran wax oxidate) and m(acids in the saponified rice bran wax oxidate) were ascertained by means of gas chromatography, m(metal) was ascertained in accordance with DGF M-IV 4 and m(mixture) corresponds to the mass of the overall mixture.

(57) The raw material used was a rice bran wax in the raw state (RBW 1). The properties of the rice bran wax in the raw state are shown in Table 3.

(58) TABLE-US-00003 TABLE 3 (methods, abbreviations and units in Table 1) Raw Viscosity material AN SN DP MP EF [mPa*s] at 120 C. OC TGA RBW 1 1.3 83 77 79 192 8 1.9 1.2/6.4

EXAMPLES 1 TO 9

(59) A 3 l 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/l) specified in Table 4, and heated to 100 C.

(60) 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 8 h. The heating and stirring were switched off. As soon as the phases had separated, the aqueous phase was separated off.

(61) This operation was repeated once in Examples 5 to 7 and twice in Example 8 (with the amounts of chromium trioxide in sulfuric acid specified in each case), using the rice bran wax oxidate from the previous operation in each case rather than the rice bran wax.

(62) 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.

(63) In a 1 l reaction vessel equipped with stirrer, temperature sensor, dropping funnel and reflux condenser, the appropriate rice bran wax oxidate was melted under a nitrogen atmosphere and admixed with the appropriate amount of Ca(OH).sub.2 (Examples 1 to 8) or aqueous NaOH (Example 9; 9 g of NaOH in 100 ml of water).

(64) The reaction mixture was stirred until the desired acid number had been attained and then the reaction mixture was pressure-filtered in the hot state. In Example 9, the reaction mixture is additionally dried to constant mass in a vacuum drying cabinet (Example 9).

(65) The chain length distribution measured for Example 2 is shown in the FIGURE.

(66) TABLE-US-00004 TABLE 4 (methods, abbreviations and units in Table 1) Example 1 2 3 4 5 6 7 8 9 RBW 1 100 g 100 g 100 g 100 g 100 g 100 g 100 g 100 g 100 g Oxidation CrO.sub.3/ 1.2 | 1.5 | 1.5 | 1.5 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | H.sub.2SO.sub.4 0.6 | 0.6 | 1.0 | 0.8 | 0.8 | 0.6 | 0.6 | Reaction 8 8 8 8 8 8 8 8 8 time [h] 8 8 8 8 8 8 8 Reaction 110 110 110 110 110 110 110 110 110 temperature [ C.] AN 45.7 51.2 51.2 51.2 71.1 71.1 89.6 123.9 123.9 (oxidate) Saponification Ca(OH).sub.2 5.1 g 3.1 g 3.7 g 5.0 g 5.0 g 6.1 g 8.9 g 8.6 g NaOH 9.0 g Reaction 2 2 2 4 3 4 6 1 1 time [h] Reaction 130 130 130 130 130 130 130 130 110 temperature [ C.] AN 4.1 14.9 8.1 5.6 19.0 12.0 13.7 8.6 2.0 SN 65 79 72 52 70 68 49 47 23 DP 103 108 111 120 106 140 135 133 MP 79.6 82.3 81.9 81.7 81.4 81.8 80.9 106.8 81.0 EF 162 209 208 200 197 194 186 173 186 TGA 2.30/ 4.37/ 1.66/ 1.45/ 2.31/ 3.39/ 6.86/ 3.01/ 2.54/ 7.76 7.98 5.09 4.88 5.34 12.55 19.23 8.45 7.31 Viscosity 42 48 880 1,160 333 5,447 [mPas] at 120 C. CIE L* 89.24 93.50 91.68 86.60 91.18 90.94 86.20 83.1 94.55 CIE a* 0.95 0.68 0.64 0.75 0.48 0.32 1.08 0.90 0.46 CIE b* 9.37 4.20 4.39 12.24 6.83 4.98 11.47 15.40 12.16 NPI 1 1 1 1 1 1 1 1 1