Cone wax oxide and esterification product

Abstract

The present invention relates to light-coloured corn wax oxides, processes for their preparation and their use for agricultural or forestry purposes or as additives in plastics processing, care products, printing inks and / or paints, and to saponified or esterified corn wax oxides produced by saponification or esterification of said corn wax oxides.

Description

Technical Field

[0001] The present invention relates to light-colored corn wax oxides having a low acid value, a method for producing the oxides from corn wax, and their use as additives for agricultural or forestry purposes or in plastic processing, care products, printing inks and / or paints. Also provided are saponified or esterified corn wax oxides produced respectively by saponification or esterification of the corn wax oxides of the present invention.

[0002] The oxidation of fossil and non-fossil natural waxes using chromic sulfuric acid has been known since the beginning of the 20th century and is still industrially practiced in the "Gelsthofer process" which has been operating since 1927 based on fossil montan wax. These chromic acid-based methods can be used not only for the oxidation of fossil montan wax but also for renewable natural waxes such as carnauba wax and candelilla wax. The method for chromic acid oxidation of carnauba wax is described in DE-A10231886 (Patent Document 1). Natural carnauba wax (fat gray, No. 4; mid-yellow, primary yellow and fluorescent, No. 3 to No. 1) and crude montan wax (black) are clearly dark-colored. By oxidation using chromic sulfuric acid, a light-colored wax product is obtained.

[0003] However, in the oxidation of natural waxes using chromic acid, cleavage of wax esters and in-situ oxidation of the resulting wax alcohols to wax acids occur. The acid value is a measure of the content of free wax acids. A typical conversion in such an oxidation ranges from 50 to 90% based on the ester groups.

[0004] DE-A1 10 2013 007638 (Patent Document 2) discloses a method for producing an acid wax having a specified acid value by oxidizing a mixture of a natural wax ester and an α-olefin with chromic sulfuric acid. The natural wax ester is selected from the group consisting of rice bran wax, carnauba wax, sunflower wax, and sugarcane wax. DE-A1 10 2018 116113 (Patent Document 3) discloses a method for producing a natural wax oxide by a two-step oxidation method using rice bran wax or sunflower wax as a starting material.

[0005] EP-A1 3 102 292 (Patent Document 4) discloses the production of an oxide by treating rice bran wax and montan wax with chromic sulfuric acid. US-A 4 083 731 (Patent Document 5) discloses the production of montan and bark wax oxides, and the montan and bark waxes are oxidized at 110 °C with a mixture of chromium trioxide and concentrated sulfuric acid. The thus-bleached natural wax has a higher saponification value and a higher acid value than the unbleached wax in addition to the desired brightening.

[0006] When the acid value is high, phase separation between the organic phase containing the wax oxide and the aqueous phase containing the chromium salt and other water-soluble reaction products is promoted, so that there are often advantages such as the by-products can be easily separated from the natural wax oxide after oxidation. However, when the acid value is low, in most cases phase separation occurs very slowly or sometimes does not occur at all. When phase separation does not occur or occurs very slowly, it is almost impossible to isolate and purify the natural wax oxide without great effort.

[0007] To increase the acid value for efficient phase separation, a larger amount of chromic sulfuric acid is required than is necessary to obtain a low acid value, and a larger amount of chromium salt waste is discharged. Avoiding a large amount of waste is desirable from an economic and environmental perspective.

[0008] Generally, phase separation in the case of a low acid value becomes more difficult when using natural waxes containing a large amount of oil, and pretreatment such as deoiling is often required. This sometimes requires a large amount of solvent, which is inconvenient both economically and environmentally. In order to obtain a product with a low acid value from a natural wax oxide with a high acid value, the acid value of the wax oxide can be reduced after removal of by-products, for example, by esterifying the acid contained in the wax and / or wax oxide with an alcohol. This means that in order to obtain a natural wax oxide with a low acid value, further synthetic steps are required after oxidation, which is also inconvenient both economically and environmentally. In particular, when a natural wax oxide with a low acid value is required for a specific application, it is advantageous to avoid using a large amount of chromic sulfuric acid, and the subsequent reduction of the acid value by esterification, as well as the use of a large amount of solvent before oxidation.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0010] An object of the present invention is to provide a method for producing a natural wax oxide by chromic sulfuric acid oxidation of a natural wax, which enables isolation of the natural wax oxide over a wide range of acid values after oxidation.

Means for Solving the Problems

[0011] Surprisingly, it has been found that when corn wax is used as a natural wax, even if the oil content of the corn wax is relatively high, it is possible to isolate and purify the natural wax oxide after chromic sulfuric acid oxidation of the natural wax while having a low acid value.

[0012] The present invention provides a method for producing corn wax oxide (O), the method comprising the following steps: i) preparing corn wax (CW); ii) preparing a mixture (M) of chromium trioxide and sulfuric acid; iii) oxidizing the corn wax (CW) by reacting the corn wax (CW) with the mixture (M) to obtain corn wax oxide (O); iv) terminating the reaction and allowing the reaction mixture obtained in step iii) to stand until the organic phase separates from the aqueous phase; v) separating the organic phase; vi) optionally removing residues containing chromium compounds from the organic phase to obtain the corn wax oxide (O) in a purified form; vii) optionally using the corn wax oxide (O) instead of the corn wax (CW), optionally in a purified form, and repeating the series of steps from step ii) to step vi); is included.

Advantages of the Invention

[0013] According to this method, it is possible to directly obtain a light-colored natural wax oxide based on corn wax, i.e., corn wax oxide (O), having an acid value in the range of about 10 to about 170 mg KOH / g, without the need for an additional step for acid value adjustment after isolation.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0015] In the method of the present invention, when corn wax (CW) is used as a starting material, a clear phase boundary between the organic phase and the aqueous phase in step iv) is found to be formed at a low acid value of about 10 mg KOH / g. When the acid value is in the range of 20 to 50 mg KOH / g, a clear phase boundary is usually observed in less than 1 minute in step iv) of the method of the present invention. When the acid value exceeds 50 mg KOH / g, a clear phase boundary is often observed in less than 10 seconds in step iv) of the method of the present invention. The time shown here was observed under the conditions as shown in the examples. In a much larger reaction vessel, the time may also change, but it is much shorter than in the case of other natural wax oxides produced under the same conditions.

[0016] When the acid value is low to medium, the phase boundary can be clearly seen even when the oil content in the corn wax used is relatively high. In contrast, in the case of rice bran wax oxide under the same other conditions, phase separation occurs only at an acid value of about 20 mg KOH / g or more and with a low oil content of less than 5% by weight, and in many cases only with an oil content of less than 2% by weight. In the case of montan wax, phase separation often occurs only at an acid value of about 50 mg KOH / g or more.

[0017] The present invention further provides a corn wax oxide (O) which can be produced by reacting corn wax (CW) with a mixture of chromium trioxide and sulfuric acid. For example, after the production of the corn wax oxide (O), in order to further adjust its acid value and / or to change other properties, the corn wax oxide (O) of the present invention can be further modified, for example, by esterification or saponification.

[0018] Esterification is usually carried out using an alcohol, often a polyhydric alcohol such as ethylene glycol, butylene glycol, glycerol, diglycerol, trimethylolpropane, ethylene glycol, pentaerythritol, or sorbitol. The present invention therefore further provides an esterified corn wax oxide (E) obtained by reacting the corn wax oxide (O) of the present invention with an alcohol, preferably a polyhydric alcohol, more preferably ethylene glycol, butylene glycol, glycerol, or pentaerythritol.

[0019] Saponification is usually carried out using a basic metal salt, often an alkali metal hydroxide and / or an alkaline earth metal hydroxide. The present invention therefore further provides a saponified corn wax oxide (S) obtained by reacting the corn wax oxide (O) of the present invention or the esterified corn wax oxide (E) of the present invention with a basic metal salt, preferably an alkali metal hydroxide and / or an alkaline earth metal hydroxide, more preferably Ca(OH) 2 and reacting therewith.

[0020] The present invention therefore further provides the use of the corn wax oxide (O) of the present invention, the esterified corn wax oxide (E) of the present invention, or the saponified corn wax oxide (S) of the present invention as an additive for agricultural or forestry purposes or in plastic processing, care products, printing inks and / or paints.

[0021] The present invention also relates to the use of corn wax (CW) for producing natural wax oxides by oxidation using a mixture of chromium trioxide and sulfuric acid. Corn wax is usually obtained from raw corn oil through a plurality of treatment steps including basic decomposition of corn oil and a plurality of purification steps including chemical, thermal and / or mechanical separation processes. A method for removing wax as an undesirable by-product (about 60 - 90% by weight) from raw vegetable oils such as corn oil is disclosed in US4272447.

[0022] According to information from the Food and Agriculture Organization of the United Nations (FAO), corn is one of the most widely produced grains. In 2018, approximately 1.147 billion tons of corn were harvested worldwide.

[0023] When processing corn, especially when producing corn oil from corn, a large amount of corn wax is generated as a by-product. Due to its high production volume and wide geographical distribution, corn wax is an economically interesting natural wax.

[0024] Despite many analytical research investigations, the chemical composition of corn wax has not yielded consistent results and is not yet fully understood. However, it is certain that the wax body is composed of wax esters. R.L. Shriner states in "the composition of corn wax" (Journal of American Chemical Society, 1927, 49, 1290 - 1294) that at least a part of corn wax consists of 22 and 24 the myristyl alcohol ester of fatty acids. G. Henon states in "Wax analysis of vegetable oils using liquid chromatography on a double adsorption layer of silica gel and silver nitrate-impregnated silica gel" (Journal of American Oil Chemists' Society 2001, 78, 401 - 410) that corn wax from crude corn oil can have a carbon chain length with 44 to 58 carbon atoms.

[0025] Corn wax esters mainly consist of monoesters of long-chain, saturated, non-branched monocarboxylic acids and long-chain, non-branched, aliphatic monoalcohols (hereinafter also referred to as "true esters"). The acid moiety of corn wax esters is mainly dominated by arachidic acid, behenic acid, and lignoceric acid with chain lengths of C20, C22, and C24, and the alcohol moiety of corn wax esters is mainly dominated by chain lengths of C24, C26, C28, C30, and C32. Furthermore, the wax may contain additional components such as free fatty acids, squalene, phospholipids, and sterol esters.

[0026] The wax ester content in refined and deoiled corn wax generally exceeds 97% by weight. In non-deoiled corn wax, the wax ester content can be about 50% by weight depending on the corn oil content. Other variable components of corn wax that can be regarded as "trace components" are "dark substances" not specified, squalene, and what is called "gum content". These components usually cause variations in color and usability in the quality of the product, making it difficult to reproduce.

[0027] The usual technique for lightening brown corn wax is thought to be the conventional bleaching with hydrogen peroxide. Corn wax bleached with hydrogen peroxide is yellowish and is approximately equivalent to the starting wax in terms of their ester content and their acid value. Such types are mainly marketed as deoiled and refined corn wax, but similarly, there are variations in the quality of the product because trace components remain in the product.

[0028] Corn wax oxides with a lower acidity than the starting wax can be produced by passing air at a high temperature using the oxidation process described in DE 2546791 B. Therefore, they have an acid value of less than 10 mg KOH / g because the acid value of the untreated corn wax already falls below this value.

[0029] The method of the present invention can produce bright corn wax oxide (O) with a certain product quality as compared with the bleaching method using hydrogen peroxide.

[0030] The corn wax oxide (O) produced by the method of the present invention usually has an iodine color value of less than 8 and a yellowness index of less than 50 when measured according to DIN 6162 (2014) and ASTM E 313-20, respectively. However, by appropriate selection of the process parameters for the oxidation of corn wax, it has been found that it is selectively possible for the iodine color value measured according to DIN 6162 (2014) to be less than 6, often less than 5, for example less than 2, and for the yellowness index to be less than 40, often less than 30, for example less than 15 when measured according to ASTM E 313-20.

[0031] At the same time, the needle penetration index is less than 10 mm when measured according to DIN51579 (2010), -1 often less than 6 mm -1 and often less than 4 mm, for example, -1 which is particularly advantageous for applications where hard wax is required.

[0032] The method of the present invention and the corn wax-based product of the present invention will be described in more detail below.

[0033] The method for producing the corn wax oxide (O) of the present invention includes or consists of the following steps: i) preparing corn wax (CW); ii) preparing a mixture (M) of chromium trioxide and sulfuric acid; iii) oxidizing the corn wax (CW) by reacting the corn wax (CW) with the mixture (M) to obtain corn wax oxide (O); iv) terminating the reaction and allowing the reaction mixture obtained in step iii) to stand until the organic phase separates from the aqueous phase; v) separating the organic phase; vi) Optionally, removing residues containing chromium compounds from the organic phase to obtain the cone wax oxide (O) in a purified form; vii) Optionally, using the cone wax oxide (O) instead of the cone wax (CW), optionally in a purified form, and repeating the series of steps from step ii) to step vi) one or more times.

[0034] The cone wax (CW) prepared in step i) can be any cone wax. When it is desirable that the acid value of the cone wax oxide (O) is low to medium, for example, 50 mg KOH / g or less, the cone wax (CW) contains a polyester formed from a polyhydric alcohol and an aliphatic carboxylic acid having 8 to 20 carbon atoms in an amount of 25% by weight or less, preferably 15% by weight or less, more preferably 10% by weight or less, preferably 5% by weight, particularly preferably 3% by weight or less, based on the total weight of the cone wax (CW). Usually, the cone wax (CW) contains a polyester formed from a polyhydric alcohol and an aliphatic carboxylic acid having 8 to 20 carbon atoms in an amount exceeding 0.1% by weight.

[0035] In this case, the desired proportion of the polyester formed from the polyhydric alcohol and the aliphatic carboxylic acid having 8 to 20 carbon atoms may already be present in the untreated cone wax, but it can also be adjusted by pre-treating the cone wax. Preferably, the proportion is the amount already present in the untreated cone wax (CW). In this case, it is preferable that the cone wax (CW) is not pre-treated.

[0036] On the other hand, when the proportion of the polyester formed from the polyhydric alcohol and the aliphatic carboxylic acid having 8 to 20 carbon atoms significantly exceeds 25% by weight, it may be advantageous to pre-treat the cone wax (CW) before it is prepared in step i). In this case, it is advantageous if the pre-treatment does not include saponification of the esters present in the cone wax (CW).

[0037] Instead, it is preferable to extract the polyester formed from a polyhydric alcohol and an aliphatic carboxylic acid having 8 to 20 carbon atoms with one or more organic solvents, and this extraction is carried out until the desired proportion of the polyester formed from the polyhydric alcohol and the aliphatic carboxylic acid having 8 to 20 carbon atoms is achieved. Any organic solvent capable of dissolving oils and fats is suitable for this purpose, for example ethyl acetate or acetone, preferably ethyl acetate.

[0038] The polyester formed from a polyhydric alcohol and an aliphatic carboxylic acid having 8 to 20 carbon atoms is preferably diglycerides and triglycerides of aliphatic carboxylic acids having 8 to 20 carbon atoms, particularly oils naturally present in corn, particularly corn oil.

[0039] Therefore, the extraction with an organic solvent may include degreasing. In this case, the proportion of the polyester formed from the polyhydric alcohol and the aliphatic carboxylic acid having 8 to 20 carbon atoms can also be referred to as the oil content of the corn wax.

[0040] Corn wax (CW) is preferably not pretreated by saponification at any point before oxidation, regardless of the proportion of the polyester formed from the polyhydric alcohol and the aliphatic carboxylic acid having 8 to 20 carbon atoms in the raw material state.

[0041] Corn wax (CW) containing a mixture of linear esters having a number average total carbon chain length of 45 to 55 carbon atoms, preferably 47 to 53 carbon atoms, is preferred. More preferably, at least 30% by weight, preferably at least 40% by weight, more preferably at least 50% by weight is corn wax (CW) containing a mixture of linear esters having a total carbon chain length of 52 or less carbon atoms, preferably 40 to 52 carbon atoms.

[0042] Furthermore, the corn wax (CW) preferably has an acid value of less than 20 mg KOH / g, more preferably less than 15 mg KOH / g, preferably less than 10 mg KOH / g, and particularly preferably 1 to 8 mg KOH / g. The corn wax (CW) more preferably has a saponification value of less than 150 mg KOH / g, more preferably less than 120 mg KOH / g, preferably 30 to 100 mg KOH / g, and particularly preferably 60 to 95 mg KOH / g.

[0043] The mixture (M) of chromium trioxide and sulfuric acid prepared in step ii) can be any mixture as long as it can oxidize the oxidizable portion of the corn wax. Such a mixture of chromium trioxide and sulfuric acid is generally also called chromic sulfuric acid. The sulfuric acid is preferably concentrated sulfuric acid with a sulfuric acid ratio of at least 90% by weight, preferably at least 96% by weight, and more preferably 99% by weight. This may be fuming sulfuric acid in some cases, that is, it may further 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, and most preferably 80 to 120 g / L.

[0044] In step iii) of the method of the present invention, the corn wax (CW) is oxidized by reacting the corn wax (CW) with the mixture (M) to obtain a corn wax oxide (O). The reaction is preferably carried out at a temperature of 70 to 200°C, more preferably 80 to 150°C, preferably 90 to 140°C, and particularly preferably 105 to 130°C while stirring.

[0045] The weight ratio of the total chromium trioxide used to the cone wax (CW) used is preferably from 1:6 to 3:1, particularly from 1:5 to 2:1, more preferably from 2:5 to 6:5. When the weight ratio is less than 1:6, the degree of oxidation is too small to cause a significant lightening of the cone wax. When the weight ratio is greater than 3:1, cleavage of the ester bond occurs particularly highly, and depending on other conditions, it may become difficult to conform to the desired acid value of the product. When step vii) in the method of the present invention is carried out, the weight ratio of the chromium trioxide used to the cone wax (CW) used is preferably less than 6:5 each time step iii) is carried out.

[0046] This step iii) can optionally be divided into two or more steps. For example, step iii) may include a step of first preparing the mixture (M) and then adding the cone wax (CW). Alternatively, step iii) may include a step of first preparing the cone wax (CW) and then adding the mixture (M). In these cases, each second component (CW) or (M) may be added, for example, little by little at a time, continuously, or all at once, preferably little by little at a time or continuously, more preferably little by little at a time.

[0047] In an embodiment where the reaction in step iii) is carried out at a temperature of 70 to 200 °C, the temperature during the addition of the cone wax (CW) and / or the mixture (M) may optionally be different from the reaction temperature, and it can be adjusted to the required value of 70 to 200 °C, more preferably 80 to 150 °C, preferably 90 to 140 °C, particularly preferably 105 to 130 °C only after the second component is added.

[0048] For example, the temperature during the above addition may be 60 to 150 °C, preferably 70 to 130 °C, more preferably 80 to 110 °C. Preferably, the cone wax (CW) is in a molten state during the addition.

[0049] In one embodiment, first, a mixture (M) of chromium trioxide and sulfuric acid is prepared and heated to a temperature of 60 to 150°C, preferably 70 to 130°C, more preferably 80 to 110°C, and the cone wax (CW) is added little by little in a solid state. After the addition, the temperature is adjusted to 70 to 200°C, preferably 80 to 150°C, preferably 90 to 140°C, more preferably 105 to 130°C, and oxidation is carried out.

[0050] In another embodiment, first, a mixture (M) of chromium trioxide and sulfuric acid is prepared and heated to a temperature of 60 to 130°C, and the cone wax (CW) is added little by little in a molten state, preferably at a temperature of 60 to 150°C, preferably 70 to 130°C, more preferably 80 to 110°C. After the addition, the temperature is adjusted to 70 to 200°C, preferably 80 to 150°C, preferably 90 to 140°C, more preferably 105 to 130°C, and oxidation is carried out.

[0051] In a further embodiment, first, the cone wax (CW) is prepared and melted at a temperature of 60 to 150°C, preferably 70 to 130°C, more preferably 80 to 110°C, and the mixture (M) of chromium trioxide and sulfuric acid is added little by little without heating. After the addition, the temperature is adjusted to 70 to 200°C, preferably 80 to 150°C, preferably 90 to 140°C, more preferably 105 to 130°C, and oxidation is carried out.

[0052] In another embodiment, first, the cone wax (CW) is prepared and melted at a temperature of 60 to 150°C, preferably 70 to 130°C, more preferably 80 to 110°C, and the mixture (M) of chromium trioxide and sulfuric acid is added little by little at a high temperature of preferably 60 to 150°C, preferably 70 to 130°C, more preferably 80 to 110°C. After the addition, the temperature is adjusted to 70 to 200°C, preferably 80 to 150°C, preferably 90 to 140°C, more preferably 105 to 130°C, and oxidation is carried out.

[0053] In a further embodiment, first, cone wax (CW) and a mixture (M) of chromium trioxide and sulfuric acid are prepared at room temperature and gradually heated to a temperature of 70 to 200 °C, preferably 80 to 150 °C, preferably 90 to 140 °C, more preferably 105 to 130 °C, and oxidized at that temperature.

[0054] Oxidation at at least 70 to 200 °C, 80 to 150 °C, 90 to 140 °C, or 105 to 130 °C is preferably carried out with the addition of cone wax (CW) and / or mixture (M) while stirring. In this case, the stirring can be carried out by any method, for example, using a mechanically driven stirrer or a magnetically driven stirrer. Preferably, the stirring is carried out using a mechanically driven stirrer, more preferably a mechanically driven stirrer including a KPG stirrer.

[0055] The stirring speed in step iii) is preferably in the range of 100 to 500 rpm (revolutions per minute), more preferably 120 to 300 rpm, most preferably 170 to 250 rpm. At stirrer speeds below 100 rpm and above 500 rpm, the mixing required for efficient oxidation does not occur, and the risk of emulsion formation, which can no longer be separated, increases.

[0056] The oxidation of the cone wax in step iii) is preferably carried out for at least 30 minutes, more preferably 45 minutes to 12 hours, more preferably 1 to 8 hours, preferably 2 to 5 hours, particularly preferably 3 to 4.5 hours.

[0057] Also, it is preferable not to add an oxidation accelerator to the reaction mixture containing cone wax (CW) and mixture (M) because these generally cause cleavage of the ester bond and the acid value in the cone wax oxide (O) can increase accordingly. Therefore, it is preferable not to use an oxidation accelerator such as an emulsifier (e.g., alkane sulfonate, fluorinated alkane sulfonate), surfactant, polymer-type surfactant, nitrogen-containing cationic surfactant, phase transfer catalyst, Fenton reagent, metal salt, hydrochloric acid, etc. in the oxidation.

[0058] When the desired reaction time is reached, the reaction is terminated in step iv), and the reaction mixture is allowed to stand until the organic phase separates from the aqueous phase. "Terminating the reaction" is understood to mean stopping the stirring and ending the heating. When this is done, the floating organic phase containing the cone wax oxide (O) begins to separate from the sedimented aqueous phase containing sulfuric acid and chromium compounds. Before allowing it to stand, the reaction mixture can optionally be transferred to a device that allows the organic phase to be easily separated after it has separated from the aqueous phase. An example of such a device is a separating funnel. Other devices for this purpose are known to those skilled in the art and can be used in the present invention.

[0059] The time required until the phase boundary is formed depends on the acid value. Surprisingly, in the method of the present invention, a distinct phase boundary separating the aqueous phase and the organic phase was observed immediately after "terminating the reaction" in step iv). When the acid value was in the range of 20 to 50 mg KOH / g, the phase boundary was observed in less than 1 minute, and when the acid value exceeded 50 mg KOH / g, it was observed within a few seconds.

[0060] The formation of the phase boundary after "terminating the reaction" was observed even when the acid value was very low, about 10 mg KOH / g, and is rather an exception in the case of wax oxidized by chromic sulfuric acid. For example, according to the described synthesis procedure, under the same conditions, the phase boundary was observed only when the acid value was about 20 mg KOH / g or more for rice wax and only when the acid value was about 50 mg KOH / g or more for montan wax. This is a clear advantage of cone wax oxide (O) over other natural wax oxides from both economic and environmental viewpoints.

[0061] In step v), the organic phase containing the cone wax oxide is separated. This can be done, for example, using a separating funnel. Alternatively, the floating organic phase can be scooped out by appropriate technical means.

[0062] It is also possible to pour out the organic phase from the edge of the container. The method of separating the organic phase from the aqueous phase after phase separation is generally known to those skilled in the art and can be used here. Further, optionally, in step vi), the separated organic phase containing cone wax oxide can be further purified to remove the residue containing the chromium compound from the organic phase and obtain cone wax oxide in a purified form.

[0063] The purification can be carried out by any method suitable for separating polar and / or water-soluble substances from organic substances. For example, the organic phase can be purified by chromatography or filtered through silica gel.

[0064] Preferably, the residue containing the chromium compound is removed by washing the organic phase with an aqueous solution of oxalic acid and / or sulfuric acid. In another embodiment, the residue containing the chromium compound is preferably removed by organic phase washing it with water. In another embodiment, the residue containing the chromium compound is preferably removed from the organic phase by centrifugation.

[0065] Here, "washing" is understood to mean the mixing of the organic phase with each washing medium for the washing in steps iv) and v) and the subsequent phase separation.

[0066] In one preferred embodiment, the residue containing the chromium compound is removed by washing the organic phase one or more times with an aqueous solution of oxalic acid and sulfuric acid, followed by washing the organic phase one or more times with water.

[0067] A more preferred embodiment is that the residue containing the chromium compound is removed from the organic phase by washing it one or more times with an aqueous solution of oxalic acid and sulfuric acid, followed by centrifuging the organic phase.

[0068] In a more preferred embodiment, the residue containing the chromium compound is removed by washing the organic phase with water one or more times, followed by centrifuging the organic phase.

[0069] In a particularly preferred embodiment, the residue containing the chromium compound is removed by washing the organic phase one or more times with an aqueous solution of oxalic acid and sulfuric acid, followed by washing the organic phase with water one or more times, and then centrifuging the organic phase.

[0070] Optionally, in step vii), instead of cone wax (CW), cone wax oxide (O) can be used, optionally in a purified form, to repeat the series of steps of steps ii) to vi). Preferably, the series of steps of steps ii) to vi) is not repeated.

[0071] In a preferred embodiment, the method of the present invention is a method for producing cone wax oxide (O), and the method includes the following steps: i) A step of preparing cone wax (CW), preferably degreased cone wax (CW); ii) A step of preparing a mixture (M) of chromium trioxide and sulfuric acid; iii) A step of oxidizing cone wax (CW) by reacting the cone wax (CW) with the mixture (M) while stirring at a temperature of 70 to 200°C, preferably 80 to 150°C, preferably 90 to 140°C, more preferably 105 to 130°C, to obtain cone wax oxide (O); iv) A step of terminating the reaction and allowing the reaction mixture obtained in step iii) to stand until the organic phase separates from the aqueous phase; v) A step of separating the organic phase; vi) Optionally, a step of removing the residue containing the chromium compound from the organic phase to obtain the cone wax oxide (O) in a purified form; vii) Optionally, a step of repeating the series of steps from step ii) to step vi) using cone wax oxide (O), optionally in a purified form, instead of cone wax (CW); Here, the oxidation in step (iii) is carried out for at least 30 minutes, preferably 45 minutes to 12 hours, more preferably 1 to 8 hours, preferably 2 to 5 hours, and particularly preferably 3 to 4.5 hours.

[0072] In this embodiment, particularly selectively, the iodine color value is less than 6, often less than 5, for example less than 2, when measured according to DIN 6162 (2014), and / or the yellowness index can be less than 40, often less than 30, for example less than 15, when measured according to ASTM E 313 - 20.

[0073] The present invention further provides a corn wax oxide (O) obtained by reacting corn wax (CW) with a mixture (M) of chromium trioxide and sulfuric acid. The corn wax oxide (O) preferably has an acid value higher than that of the corn wax (CW) used.

[0074] The corn wax oxide (O) of the present invention preferably has an acid value of about 10 to about 170 mg KOH / g, more preferably 10 to 140 mg KOH / g, more preferably 11 to 130 mg KOH / g, more preferably 15 to 110 mg KOH / g, when measured according to ISO2114 (2002). In one embodiment, the corn wax oxide (O) of the present invention has an acid value of less than about 20 mg KOH / g and greater than or equal to about 10 mg KOH / g.

[0075] In another embodiment, the corn wax oxide (O) of the present invention has an acid value of about 20 to about 50 mg KOH / g. In yet another embodiment, the corn wax oxide (O) of the present invention has an acid value of 50 to about 170 mg KOH / g when measured according to ISO2114 (2002). In yet another embodiment, the corn wax oxide (O) of the present invention has an acid value of less than 140 mg KOH / g, preferably less than 110 mg KOH / g, more preferably less than 60 mg KOH / g, particularly preferably less than 40 mg KOH / g, and particularly preferably less than 20 mg KOH / g.

[0076] Depending on the degree of reaction of the ester, the cone wax oxide of the present invention contains true esters (C42 - C60). "True ester" is understood here to mean the residual part of the wax ester originally contained in the raw wax that is not affected by the reaction.

[0077] The present invention further provides a cone wax oxide (O) of the present invention, which has an acid value of about 10 - about 170 mgKOH / g as measured according to ISO2114 (2002), and the ratio of the weight percentage of the true ester with 46 carbon atoms to the weight percentage of the true ester with 52 carbon atoms is greater than 1. This cone wax oxide (O) can be produced by the method in claim 1.

[0078] The cone wax oxide (O) of the present invention is preferably characterized in that the acid value of the cone wax oxide (O) is greater than the acid value of the cone wax (CW).

[0079] Furthermore, the cone wax oxide (O) of the present invention, especially when produced by the method described in claim 1, has an iodine color value, measured according to DIN 6162 (2014), preferably less than 6, more preferably less than 5, even more preferably less than 3, preferably less than 2, and particularly preferably less than 1.5. Alternatively, the cone wax oxide (O) of the present invention has a yellowness index, measured according to ASTM E 313 - 20, preferably less than 50, more preferably less than 30, even more preferably less than 20, preferably less than 15, and particularly preferably less than 10.

[0080] Furthermore, the cone wax oxide (O) of the present invention preferably contains less than 5% by weight, more preferably less than 3% by weight, and most preferably less than 1% by weight of a polyester formed from a polyhydric alcohol and an aliphatic carboxylic acid having 8 - 20 carbon atoms, based on the total weight of the cone wax oxide (O).

[0081] In one embodiment, the cone wax oxide (O) is a) Free aliphatic carboxylic acids having 8 to 36 carbon atoms, based on the total weight of the cone wax oxide (O), from 3% to 40% by weight; b) Free aliphatic alcohols having 24 to 36 carbon atoms, based on the total weight of the cone wax oxide, from 0% to 10% by weight; c) Free aliphatic dicarboxylic acids having 10 to 30 carbon atoms, based on the total weight of the cone wax oxide (O), from 0 to 5% by weight; d) True esters having 40 to 66 carbon atoms, based on the total weight of the cone wax oxide (O), from 30 to 97% by weight; and e) Further natural components present in the cone wax, based on the total weight of the cone wax oxide (O), from 0% to 30% by weight, wherein the sum of a), b), c), d), and e) is 100% by weight based on the total weight of the cone wax oxide (O).

[0082] In a preferred embodiment, the cone wax oxide (O) is a) Free aliphatic carboxylic acids having 8 to 36 carbon atoms, based on the total weight of the cone wax oxide (O), from 3% to 15% by weight; b) Free aliphatic alcohols having 24 to 36 carbon atoms, based on the total weight of the cone wax oxide, from 0% to 7% by weight; c) Free aliphatic dicarboxylic acids having 10 to 30 carbon atoms, based on the total weight of the cone wax oxide (O), from 0 to 4% by weight; d) True esters having 40 to 66 carbon atoms, based on the total weight of the cone wax oxide (O), from 65 to 97% by weight; and e) Further natural components present in the cone wax, based on the total weight of the cone wax oxide (O), from 0% to 15% by weight, wherein the sum of a), b), c), d), and e) is 100% by weight based on the total weight of the cone wax oxide (O).

[0083] In a preferred embodiment, the cone wax oxide (O) is a) Free aliphatic carboxylic acids having 8 to 36 carbon atoms, based on the total weight of the cone wax oxide (O), 3% to 10% by weight; b) Free aliphatic alcohols having 24 to 36 carbon atoms, based on the total weight of the cone wax oxide, 0% to 5% by weight; c) Free aliphatic dicarboxylic acids having 10 to 30 carbon atoms, based on the total weight of the cone wax oxide (O), 0 to 3% by weight; d) True esters having 40 to 66 carbon atoms, based on the total weight of the cone wax oxide (O), 65 to 97% by weight; and e) Further natural components present in the cone wax, based on the total weight of the cone wax oxide (O), 0% to 15% by weight, containing wherein the sum of a), b), c), d), and e) is 100% by weight based on the total weight of the cone wax oxide (O).

[0084] The present invention provides a cone wax oxide having an acid value of less than 50 mg KOH / g and containing less than 5% by weight, based on the total weight of the cone wax oxide (O), of a polyester formed from a polyhydric alcohol and an aliphatic carboxylic acid having 8 to 20 carbon atoms. Here, the cone wax oxide is a) Free aliphatic carboxylic acids having 8 to 36 carbon atoms, based on the total weight of the cone wax oxide (O), 3% to 25% by weight; b) Free aliphatic alcohols having 24 to 36 carbon atoms, based on the total weight of the cone wax oxide, 0% to 10% by weight; c) Free aliphatic dicarboxylic acids having 10 to 30 carbon atoms, based on the total weight of the cone wax oxide (O), 0 to 5% by weight; d) True esters having 40 to 66 carbon atoms, based on the total weight of the cone wax oxide (O), 65 to 97% by weight; and e) Further natural components present in the cone wax, based on the total weight of the cone wax oxide (O), 0% to 15% by weight, containing Here, the sum of a), b), c), d), and e) is 100% by weight based on the total weight of the cone wax oxide (O).

[0085] In this case, the cone wax oxide (O) preferably contains lignoceric acid at a ratio of 5% by weight or less, more preferably 3% by weight or less, based on the total weight of the cone wax oxide (O).

[0086] The weight ratio and chain length distribution can be measured, for example, by gas chromatography.

[0087] Furthermore, the cone wax oxide according to the present invention typically has a dropping point of 70°C to 90°C, preferably 75°C to 80°C, as measured according to ISO 2176 (1997).

[0088] The cone wax oxide of the present invention has a needle penetration index (NPI) that, when measured according to DIN 51579 (2010), is preferably -1 less than 10 mm, preferably -1 less than 6 mm, more preferably -1 less than 4 mm, most preferably -1 less than 3 mm.

[0089] By oxidizing the cone wax, the saponification value, when measured according to DIN ISO 3681 (2019), preferably increases by a maximum of 70%, preferably a maximum of 40%, more preferably a maximum of 30%. The increase in the saponification value can be mechanistically explained by the cleavage of wax esters and subsequent oxidation of wax alcohols to acids. Additionally, some of the unsaturated carbon-carbon bonds are cleaved by the oxidizing agent and similarly oxidized to acids.

[0090] Therefore, the saponification value is also a measure of the degree of oxidation that actually occurred, in contrast to saponification where the saponification value does not change as is well known, and also in contrast to other bleaching methods that simply brighten the product. For example, the effect of bleaching corn wax with hydrogen peroxide is that only discolored impurities and secondary components are removed without changing the actual wax structure, resulting in no chemical modification of the wax in the sense of the present invention.

[0091] The corn wax oxide (O) of the present invention typically has a mass loss of less than 50%, preferably less than 20%, more preferably less than 10% when measured according to DIN 51006 (2005) until reaching a temperature of 300 °C (heating rate: 5 °C / min), and is characterized by particularly good thermal stability.

[0092] The present invention further provides an esterified corn wax oxide (E) obtained by esterification or reaction of the above corn wax oxide (O) with an alcohol. Preferred alcohols are polyhydric alcohols such as ethylene glycol, butylene glycol, glycerol, diglycerol, trimethylolpropane, pentaerythritol, or sorbitol. In the esterification, the weight ratio of the alcohol to the corn wax oxide (O) is selected to be 1:100 to 1:5, more preferably 1:50 to 1:10, and most preferably 1:20 to 1:12.

[0093] The esterification product preferably has, along with a renewable raw material base, a mass loss until reaching a temperature of 300 °C (heating rate: 5 °C / min), measured in accordance with DIN 51006 (2005), of less than 15%, preferably less than 10%, and is characterized by particularly good thermal stability. The esterification product preferably has an acid value of less than 40 mg KOH / g, more preferably less than 30 mg KOH / g, and most preferably less than 20 mg KOH / g. Similarly, the present invention provides the use of the corn wax oxide (O) according to the present invention, the saponified corn wax oxide (S) according to the present invention, or the esterified corn wax oxide (E) according to the present invention as an additive for agricultural or forestry purposes or in plastic processing, care products, printing inks, and / or paints.

[0094] Furthermore, the present invention provides a saponified corn wax oxide (S) produced by saponifying the above-mentioned corn wax oxide (O) or the above-mentioned esterified corn wax oxide (E) with a basic metal salt selected from the group consisting of metal hydroxides (for example, NaOH, KOH, Ca(OH) 2 , Zn(OH) 2 etc.), metal oxides (for example, CaO etc.), metal carbonates (for example, Na 2 CO 3 , CaCO 3 etc.), or aqueous alkaline solutions (for example, NaOH, KOH etc.). Alkali metal hydroxides and / or alkaline earth metal hydroxides, especially NaOH, KOH, and / or Ca(OH) 2 are preferred. Particularly preferred is Ca(OH) 2 .

[0095] In the saponification, the weight ratio of the basic metal salt to the corn wax oxide (O) is selected from 1:100 to 1:5, more preferably 1:50 to 1:10.

[0096] The corresponding production method can be found, for example, in DE4019167 or EP1010728. The saponification product preferably has a mass loss of less than 10%, preferably less than 5%, when measured according to DIN 51006 (2005) up to the attainment of a temperature of 300 °C (heating rate: 5 °C / min), along with a renewable raw material base, and is characterized by particularly good thermal stability. Preferably, the saponification product has an acid value of less than 40 mg KOH / g, more preferably less than 25 mg KOH / g, and most preferably less than 15 mg KOH / g.

[0097] The present invention also provides the use of corn wax (CW) for producing natural wax oxides by oxidation using a mixture (M) of chromium trioxide and sulfuric acid.

Examples

[0098] The present invention will be explained in more detail by the following examples, Figures 1 to 3, and the claims.

[0099] Characterization of substances The standard methods described in Table 1, which are also used for the characterization of montan wax and montan wax derivatives, are used for the determination of the properties of corn wax, corn wax oxides, and further other corn wax derivatives.

[0100]

Table 1

[0101] The chain length distribution of the components of corn wax oxide was measured by gas chromatography. Wax acids and wax alcohols having carbon chain lengths of C6 to C36 were used as comparative substances. Wax esters of C44 to C58 were prepared by a combination of model substances. To identify the peaks in the gas chromatogram of corn wax, a defined amount of each component was added to the wax sample, and a distinct increase in the corresponding peak area was observed. The measurement conditions are shown in Table 2.

[0102]

Table 2

[0103] The raw materials used were two different corn waxes (CW1-2) as examples, and two rice bran waxes (RBW1-2), sugarcane wax (SCW), and carnauba wax (CarW) as comparative examples, all in crude form. The characteristics of the corn waxes and the waxes of the comparative examples in the crude state are shown in Table 3.

[0104] The acid value, saponification value, and oil content of the selected rice bran waxes were within the ranges of those values of the corn waxes used. The acid values of the sugarcane wax and carnauba wax were, of course, higher than those of the corn wax or rice bran wax.

[0105]

Table 3

[0106] Examples 1-8 and Comparative Examples 9-15 Chromium trioxide in the amount shown in Table 4 was put into 96% sulfuric acid (concentration: 100 g CrO 3 / L), and heated to 100 °C in a 3 L reaction vessel equipped with a stirrer, temperature sensor, dropping funnel, and reflux condenser. Then, the crude molten natural wax (90 °C) was added little by little.

[0107] The temperature of the reaction mixture was adjusted to 110 °C, and the reaction mixture was stirred at about 200 rpm for 4 hours using a KPG stirrer. Heating and stirring were stopped. As soon as the phases separated, the aqueous phase was separated. This operation was performed 2 times in Examples 3 and 7, and 3 times in Example 8. In Examples 9, 10, 12, 14, and 15 (comparative examples), phase separation did not occur. Therefore, the characteristics of the natural wax oxide could not be investigated.

[0108] The organic phase was washed with an aqueous solution of oxalic acid and sulfuric acid, then washed with water to remove chromium residues, discharged into a warm centrifuge tube, and centrifuged. The oxidation conditions and properties of the corn wax oxide are shown in Table 4.

[0109] The measured chain length distributions for Example 2 are shown in Figure 1 and for Example 7 in Figure 2. The free acid is shown by the white bar graph and the ester by the black bar graph. The chain length distribution of the esters in the corn wax used is shown in Figure 3 (white bar graph). The average chain length was 50 carbon atoms. For comparison, Figure 3 also shows the chain length distribution of rice bran wax having a number average chain length of 53 carbon atoms (black bar graph). In both cases, the carbon chain length is on the horizontal axis and the percentage of each carbon chain length in the total chain length distribution determined from the peak area of the gas chromatogram is represented on the vertical axis in weight %.

[0110] From Examples 1 to 8, it can be seen that the corn wax oxide has a unique light color with an iodine color value of less than 5 and a yellowness index of less than 30. At the same time, the acid value ranged widely from a very low value of 11 mg KOH / g to a high value of 128 mg KOH / g.

[0111] In contrast, in Comparative Examples 9, 10, 12, 14, and 15 using rice bran wax, sugar cane wax, and carnauba wax, phase separation did not occur and the product could not be isolated. This is surprising because the acid value, saponification value, oil content, and amount used of the natural waxes used for comparison purposes are close to those of the corn wax used.

[0112] In Comparative Examples 11 and 13, phase separation occurred, but in the case of rice bran wax, it took 300 minutes (5 hours) despite the relatively low oil content (4.3 wt%) and relatively high acid value (35 mg KOH / g). At acid values close to those of the rice bran wax oxides (27 and 36 mg KOH / g), in Examples 4 and 5, the corn wax phase separated much more rapidly despite having a significantly higher oil content (9.7 wt%). In the case of sugarcane wax, it took 10 minutes for the phase to separate despite the relatively high acid value (47 mg KOH / g). In the case of carnauba wax, no phase separation occurred. At the same time, in the corn wax oxide, much better iodine color values and yellowness indices were observed.

[0113]

Table 4

[0114]

Table 4

[0115]

Table 4

[0116] From this, it can be seen that the chromic acid oxidation of corn wax (CW) can produce a wider range of natural wax oxides with higher quality than using rice bran wax, sugarcane wax, or carnauba wax.

[0117] Examples 16 - 19 In a 1 L reaction vessel equipped with a stirrer, temperature sensor, dropping funnel, and reflux condenser, the corn wax oxides from Examples 3, 5, 6, and 7 were melted under a nitrogen atmosphere and mixed with Ca(OH) in the amounts shown in Table 5. 2 The reaction mixture was stirred until the desired acid value was obtained, and then the reaction mixture was pressure - filtered while heating.

[0118]

Table 5

[0119] In Examples 16 to 19, the cone wax oxide is saponified with Ca(OH) 2 to produce a saponified product having an acid value of less than 15 mg KOH / g, which is particularly suitable for uses requiring high thermal stability.

[0120] Examples 20 to 22 In a 1 L reaction vessel equipped with a stirrer, a temperature sensor, a dropping funnel, and a reflux condenser, the cone wax oxide from Example 7 is melted under a nitrogen atmosphere and mixed with the amounts of alcohol shown in Table 6 and 0.1 g of methanesulfonic acid. The reaction mixture is stirred until the desired acid value is obtained, the generated water is distilled off, and then the reaction mixture is pressure-filtered while heating.

[0121]

Table 6

[0122] In Examples 20 to 22, the cone wax oxide is esterified with ethylene glycol, glycerol or pentaerythritol to easily produce an esterified product having an acid value of less than 20 mg KOH / g, which is particularly suitable for uses requiring high thermal stability.

Claims

1. The following steps: i) A step of preparing corn wax (CW); ii) A step of preparing a mixture (M) of chromium trioxide and sulfuric acid; iii) A step of oxidizing the corn wax (CW) by reacting the corn wax (CW) with the mixture (M) to obtain a corn wax oxide (O); iv) A step of terminating the reaction and allowing the reaction mixture obtained in step iii) to stand until the organic phase separates from the aqueous phase; v) A step of separating the organic phase; vi) Optionally, a step of removing a residue containing a chromium compound from the organic phase to obtain the corn wax oxide (O) in a purified form; vii) Optionally, repeating steps ii) to vi) using the corn wax oxide (O), optionally in a purified form, instead of the corn wax (CW); wherein the corn wax oxide (O) has an acid value higher than that of the starting material, A method for producing a corn wax oxide (O) comprising the above.

2. The method according to claim 1, wherein waxes other than corn wax are not used.

3. The method according to claim 1 or 2, wherein the weight ratio of the total chromium trioxide used to the corn wax (CW) used is 1:6 to 3:

1.

4. The step of removing the residue containing the chromium compound is carried out according to step vi), and at least one of the following steps via), vib), and vic): via) A step of washing the organic phase with an aqueous solution of oxalic acid and / or sulfuric acid; vib) A step of washing the organic phase with water; vic) A step of centrifuging the organic phase, The method according to any one of claims 1 to 3.

5. The method according to any one of claims 1 to 4, wherein the corn wax (CW) contains a polyester formed from a polyhydric alcohol and an aliphatic carboxylic acid having 8 to 20 carbon atoms in an amount of 25% by weight or less.

6. The method according to any one of claims 1 to 5, wherein the sulfuric acid is concentrated sulfuric acid having a sulfuric acid ratio of at least 90% by weight.

7. The method according to any one of claims 1 to 6, wherein the reaction in step iii) is carried out with stirring at a temperature of 70 to 200 °C.

8. The method according to any one of claims 1 to 7, wherein the concentration of chromium trioxide in the mixture (M) is 50 to 200 g / L.

9. The oxidation in step iii) is carried out for at least 30 minutes, the method according to any one of claims 1 to 8.

10. The cone wax (CM) has an acid value of less than 20 mg KOH / g as measured in accordance with ISO 2114 (2002), the method according to any one of claims 1 to 9.

11. The ratio of the weight percentage of the true ester having 46 carbon atoms to the weight percentage of the true ester having 52 carbon atoms is greater than 1, a cone wax oxide (O) having an acid value of about 10 to about 170 mg KOH / g.

12. An esterified cone wax oxide (E) obtained by reacting the cone wax oxide (O) according to claim 11 with an alcohol.

13. A saponified cone wax oxide (S) obtained by saponifying the cone wax oxide (O) according to claim 11 or the esterified cone wax oxide (E) according to claim 12 using a basic metal salt.

14. Use of the cone wax oxide (O) according to claim 11, the saponified cone wax oxide (S) according to claim 13 or the esterified cone wax oxide (E) according to claim 12 as an additive for agricultural or forestry purposes or in plastic processing, care products, printing inks and / or paints.

15. Use of cone wax (CW) for producing a natural wax oxide by oxidation using a mixture (M) of chromium trioxide and sulfuric acid.

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