Oxidized paraffin, preparation method thereof and application of oxidized paraffin in preparation of emulsified wax

Abstract

The invention relates to oxidized paraffin, a preparation method thereof and application of the oxidized paraffin in preparation of emulsified wax, and belongs to the technical field of paraffin modification. The specific catalyst is used for catalyzing oxidation of the paraffin, the acid value and the saponification value of the prepared oxidized paraffin are higher, the oxidized paraffin is used as a paraffin raw material, the oxidized paraffin has more oxygen-containing groups and is easier to emulsify, and the emulsified paraffin obtained after emulsification is stable in property, smaller in particle size, better in dispersing performance and excellent in physical performance; wide application prospects are realized.

Description

Technical Field

[0001] This invention relates to the field of paraffin modification technology, and more particularly to an oxidized paraffin, its preparation method, and its application in the preparation of emulsified waxes. Background Technology

[0002] Emulsified waxes are a type of wax, including petroleum waxes, uniformly dispersed in water. They are produced as a homogeneous fluid through the directional adsorption of emulsifiers under mechanical force. Based on the type of surfactant used, emulsified waxes can be classified into four types: cationic, anionic, nonionic, and amphoteric.

[0003] Currently, my country has a relatively rich array of emulsifier preparation processes. Depending on the raw material ratios, single or compound emulsifiers can be rationally selected. Under the required conditions, paraffin wax and water, or other additives, can be added, resulting in emulsified waxes that exhibit solid, liquid, or a coexisting solid-liquid fluid or semi-fluid state. Structure determines properties, and properties determine applications. Emulsified waxes are highly flexible in their application. Many emulsified waxes do not require heating, melting, or solvent dissolution; they naturally exhibit advantages such as uniform film formation, excellent coverage, smoothness, good gloss, and good water resistance. Furthermore, due to their relatively stable properties, they are easily compounded with aqueous solutions or emulsions of other substances, offering advantages such as environmental friendliness, economy, and ease of operation. Therefore, they are widely used in petrochemicals, automotive waxes, wood processing, construction, medical supplies, agriculture, papermaking, and explosives industries. Because emulsified paraffin wax is easily compounded with aqueous solutions or emulsions of other substances and eliminates the need for heating, melting, or solvent dissolution, it also offers advantages such as safety, energy saving, high efficiency, environmental friendliness, economy, and convenience in use. Examples include: reinforcing agents for wood or fiberboard, drilling fluid additives, decorative waxes for the modern automotive industry, curing agents for reinforced concrete, and medical latex products.

[0004] In the 1950s, ExxonMobil began researching emulsified waxes. By the 1960s, the use of emulsified waxes was widespread in the United States. In the 1970s, the United Kingdom, West Germany, and Japan also began researching and applying emulsified waxes. my country's emulsified wax industry has a short history, and product quality needs improvement. Therefore, developing multifunctional emulsified wax products that are widely applicable, versatile, non-toxic, and environmentally friendly has significant economic and social benefits. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide an oxidized paraffin, its preparation method, and its application in the preparation of emulsified wax.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a method for preparing oxidized paraffin, comprising the following steps: S1. After heating and dissolving paraffin, a catalyst is added to obtain a mixture; The catalyst is prepared as follows: cobalt naphthenate is dissolved in a solvent, then manganese dioxide (MnO2) is added and stirred for 1-3 hours. After standing for 3-6 hours, the reactant is obtained, the solvent is removed, and then dried to obtain the catalyst. The mass fraction of cobalt naphthenate, based on the mass of MnO2, is 20%-35%. S2. The mixture obtained in step S1 is passed through air and fully oxidized at 140~160℃. After cooling, oxidized paraffin is obtained.

[0007] This invention utilizes a specific catalyst to oxidize paraffin, resulting in oxidized paraffin with higher acid value and saponification value.

[0008] In a preferred embodiment of the preparation method described in this invention, in step S1, the paraffin wax is paraffin wax with a melting point of 50~70℃.

[0009] In a preferred embodiment of the preparation method of the present invention, in step S1, the paraffin wax includes one or more grades of 52#, 54#, 56#, 58#, 60#, 62#, 64#, 66#, 68# and 70#.

[0010] In a preferred embodiment of the preparation method of the present invention, in step S1, the mass fraction of the catalyst is 0.7% based on the mass of paraffin.

[0011] As a preferred embodiment of the preparation method of the present invention, in the preparation method of the catalyst in step S1, the drying conditions are drying at 80~100℃ for 3~10 hours.

[0012] In a preferred embodiment of the synthesis method of the present invention, in the catalyst preparation method in step S1, the solvent is petroleum ether.

[0013] In a preferred embodiment of the preparation method described in this invention, in the catalyst preparation method of step S1, the mass fraction of cobalt naphthenate is 30%~35% based on the mass of MnO2. Within this range, the oxidized paraffin prepared by catalyst oxidation has a higher acid value and saponification value.

[0014] In a preferred embodiment of the preparation method of the present invention, in the catalyst preparation method of step S1, the mass fraction of cobalt naphthenate is 35% based on the mass of MnO2.

[0015] In a preferred embodiment of the preparation method described in this invention, in step S2, the volume hourly space velocity of the air is 0.5~1.2 h⁻¹. -1 .

[0016] In a preferred embodiment of the preparation method described in this invention, in step S2, the volume hourly space velocity of the air is 0.8 h⁻¹. -1 .

[0017] In a preferred embodiment of the preparation method described in this invention, the time for complete oxidation in step S2 is 1 to 9 hours.

[0018] In a preferred embodiment of the preparation method described in this invention, the time for complete oxidation in step S2 is 3 hours.

[0019] In a preferred embodiment of the preparation method described in this invention, the temperature for complete oxidation in step S2 is 140°C. At this temperature, the oxidized paraffin wax prepared by oxidation has the highest acid value and saponification value.

[0020] Secondly, the present invention provides oxidized paraffin prepared using the above-described preparation method.

[0021] Thirdly, the present invention provides the application of the above-mentioned oxidized paraffin in the preparation of emulsified wax.

[0022] Fourthly, the present invention provides a method for preparing emulsified wax, wherein oxidized paraffin, emulsifier and water are mixed and emulsified to obtain emulsified wax; The mass ratio of oxidized paraffin to emulsifier is 10:3~7; the emulsification temperature is 90~120℃; and the emulsification time is 20~40min.

[0023] This invention utilizes oxidized paraffin wax, combined with specific emulsification conditions, to prepare an emulsified wax with better stability and smaller particle size, exhibiting excellent performance and broad application prospects.

[0024] As a preferred embodiment of the preparation method of the emulsified wax of the present invention, the emulsification method includes self-emulsification or phase transition temperature method.

[0025] In a preferred embodiment of the preparation method of the emulsified wax of the present invention, the emulsification method is a self-emulsification method or a phase transition temperature method.

[0026] In a preferred embodiment of the preparation method of the emulsified wax of the present invention, the emulsification method is the phase transition temperature method.

[0027] In a preferred embodiment of the preparation method of the emulsified wax of the present invention, the emulsifier includes one of oleic acid, Span 80, triethanolamine oleate, Pinto-P-15, Tween 80, and sodium dodecyl sulfate (K12, SDS).

[0028] In a preferred embodiment of the preparation method of the emulsified wax of the present invention, the sum of the mass of the oxidized paraffin and the emulsifier is 15% to 60% of the mass of water.

[0029] In a preferred embodiment of the preparation method of the emulsified wax of the present invention, the sum of the mass of the oxidized paraffin and the emulsifier is 30% of the mass of water.

[0030] In a preferred embodiment of the preparation method of the emulsified wax of the present invention, the mass ratio of the oxidized paraffin to the emulsifier is 10:3~4. Within this range, the prepared emulsified wax has better stability, smaller particle size, and better dispersibility.

[0031] In a preferred embodiment of the preparation method of the emulsified wax of the present invention, the mass ratio of the oxidized paraffin to the emulsifier is 10:4. At this ratio, the prepared emulsified wax exhibits optimal stability, smaller particle size, and optimal dispersibility.

[0032] In a preferred embodiment of the preparation method of the emulsified wax described in this invention, the emulsification temperature is 90~100℃. Within this range, the prepared emulsified wax exhibits better stability, smaller particle size, and better dispersibility.

[0033] In a preferred embodiment of the preparation method of the emulsified wax described in this invention, the emulsification temperature is 90°C. At this temperature, the prepared emulsified wax exhibits optimal stability, smaller particle size, and optimal dispersibility.

[0034] In a preferred embodiment of the preparation method of the emulsified wax described in this invention, the emulsification time is 30-40 minutes. Within this range, the prepared emulsified wax exhibits better stability, smaller particle size, and better dispersibility.

[0035] In a preferred embodiment of the preparation method of the emulsified wax described in this invention, the emulsification time is 30 minutes. At this ratio, the prepared emulsified wax exhibits optimal stability, smaller particle size, and optimal dispersibility.

[0036] Fifthly, the present invention provides an emulsified wax prepared using the above-described method for preparing emulsified wax.

[0037] The emulsified wax prepared by this invention has better stability, smaller particle size, and better dispersibility.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention utilizes oxidized paraffin as a paraffin raw material. Oxidized paraffin has more oxygen-containing groups and is easier to emulsify. At the same time, this invention uses a specific catalyst to catalyze the oxidation of paraffin, resulting in oxidized paraffin with higher acid value and saponification value. The emulsified wax obtained after emulsification has stable properties, smaller particle size, better dispersion performance, and excellent physical properties, and has broad application prospects. Detailed Implementation

[0039] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0040] Unless otherwise specified, all other materials and reagents used in the examples are commercially available.

[0041] The following emulsification methods are as follows: (1) Self-emulsification method: Self-emulsification method refers to the method of directly mixing oil phase and surfactant with water in a reactor to obtain emulsion. The self-emulsification mechanism is that when surfactant / oil / water reach a certain ratio, a bicontinuous microemulsion will be formed at the oil-water interface. The formation of bicontinuous microemulsion is the key to the emulsification process. When bicontinuous microemulsion breaks down, the system will spontaneously generate small droplets, thereby generating a stable emulsion.

[0042] (2) D-phase emulsification method: In the D-phase emulsification method, the nonionic surfactant and polyol solution are first dispersed into a homogeneous phase, and then the oil phase is added to the system under stirring to form an O / D gel phase. Finally, water is added to the system to dilute it and the emulsion is obtained.

[0043] (3) Phase transition temperature method: First, the mixture of nonionic surfactant, oil and water is vigorously stirred at room temperature to make it uniformly mixed; the emulsion mixture is gradually heated to about or above the phase transition temperature. At this time, the HLB value is lower than that at room temperature, and the surfactant has a stronger lipophilicity; the mixed emulsion is cooled to make it cool down rapidly. The emulsion will suddenly change from W / O to O / W at a certain temperature. This temperature is called the phase transition temperature. Therefore, this method is also called the phase transition temperature method.

[0044] (4) Phase transition concentration method: First, place the emulsifier and wax in the reactor and heat them to melt so that they are mixed evenly. Then, add a small amount of deionized water at the same temperature to the system. At this time, the water phase in the system is less than the oil phase, forming a W / O type emulsion. As the water phase increases, the spontaneous curvature of the surfactant changes, and the system is transformed into an O / W type emulsion through a bicontinuous phase transition.

[0045] Example 1 An oxidized paraffin and its prepared emulsified wax, wherein the method for preparing the oxidized paraffin includes the following steps: S1. Place 20g of 58# fully refined paraffin wax in a flask and heat and stir to dissolve. Add a catalyst with a mass fraction of 0.7% based on the mass of the paraffin wax. The catalyst is prepared as follows: cobalt naphthenate is used as the active component. After dissolving it in petroleum ether, MnO2 is added. The mass fraction of cobalt naphthenate is 35% based on the mass of MnO2. After mixing and stirring for 2 hours, the mixture is allowed to stand for 4 hours. The solvent petroleum ether is then distilled and dried in an oven at 100°C for 5 hours to obtain the catalyst. S2. Air is continuously bubbled through the flask, and oxidation is carried out at 140°C for 3 hours. The volume hourly space velocity (VHSV) of the air is 0.8 h⁻¹. -1 After the reaction is complete and cooled, oxidized paraffin is obtained. The acid value and saponification value of the oxidized paraffin are 44 and 37 mgKOH / g, respectively.

[0046] Emulsified wax is prepared using oxidized paraffin. The preparation method of the emulsified wax is as follows (self-emulsification method): oxidized paraffin, emulsifier Tween80 and deionized water are placed in a reactor and mixed. The mixture is stirred at 90°C for 30 minutes and then cooled to obtain emulsified wax. The mass ratio of the oxidized paraffin to the emulsifier is 10:4, and the sum of the masses of the oxidized paraffin and the emulsifier is 30% of the total water mass.

[0047] Example 2 An oxidized paraffin and its prepared emulsified wax, wherein the preparation of the oxidized paraffin is the same as in Example 1.

[0048] The difference between the preparation of this emulsified wax and Example 1 lies only in the emulsification method. In this example, the emulsification method of Example 1 is changed from emulsification to phase transition temperature method. Specifically, The preparation method is as follows (phase transition temperature method): at room temperature, oxidized paraffin, emulsifier Tween80 and deionized water are stirred and emulsified for 30 minutes, then heated to 90°C and then rapidly cooled to obtain emulsified wax.

[0049] Examples 3-5 Three examples of oxidized paraffin and the prepared emulsified wax are given. The preparation of the oxidized paraffin in Examples 3-5 is the same as in Example 2. The only difference between the emulsified wax and Example 2 is the proportion of raw materials used in the preparation method. Specifically, Example 3: Compared with Example 2, the mass ratio of oxidized paraffin to emulsifier in the preparation method of emulsified wax in Example 2 was adjusted from 10:4 to 10:3 to obtain emulsified wax.

[0050] Example 4: Compared with Example 2, the mass ratio of oxidized paraffin to emulsifier in the preparation method of emulsified wax in Example 2 was adjusted from 10:4 to 10:5 to obtain emulsified wax.

[0051] Example 5: Compared with Example 2, the mass ratio of oxidized paraffin to emulsifier in the preparation method of emulsified wax in Example 2 was adjusted from 10:4 to 10:7 to obtain emulsified wax.

[0052] Examples 6-8 Three examples of oxidized paraffin and the prepared emulsified wax are given. Examples 6-8 describe the preparation of oxidized paraffin as in Example 2. The only difference between the emulsified wax and Example 2 is the heating temperature used in the preparation method. Specifically, Example 6: Compared with Example 2, the heating temperature in the preparation method of emulsified wax in Example 2 was adjusted from 90°C to 100°C to obtain emulsified wax.

[0053] Example 7: Compared with Example 2, the heating temperature in the preparation method of emulsified wax in Example 2 was adjusted from 90°C to 110°C to obtain emulsified wax.

[0054] Example 8: Compared with Example 2, the heating temperature in the preparation method of emulsified wax in Example 2 was adjusted from 90°C to 120°C to obtain emulsified wax.

[0055] Examples 9-10 Two examples of oxidized paraffin and the prepared emulsified wax are given. In Examples 9-10, the preparation of the oxidized paraffin is the same as in Example 2. The only difference between the emulsified wax and Example 2 is the emulsification time in the preparation method. Specifically, Example 9: Compared with Example 2, the emulsification time in the preparation method of emulsified wax in Example 2 was adjusted from 30 min to 20 min to obtain emulsified wax.

[0056] Example 10: Compared with Example 2, the emulsification time in the preparation method of emulsified wax in Example 2 was adjusted from 30 min to 40 min to obtain emulsified wax.

[0057] Examples 11-12 Two examples of oxidized paraffin and the prepared emulsified wax are given. The preparation of the emulsified wax in Examples 11-12 is the same as in Example 2. The only difference between the preparation of the oxidized paraffin and Example 2 is the proportion of the raw materials used in the catalyst preparation method. Specifically, Example 11: Compared with Example 2, the mass fraction of cobalt naphthenate in the catalyst preparation method of Example 2 was adjusted from 35% to 20% to obtain oxidized paraffin.

[0058] Example 12: Compared with Example 2, the mass fraction of cobalt naphthenate in the catalyst preparation method of Example 2 was adjusted from 35% to 30% to obtain oxidized paraffin.

[0059] Example 13 An embodiment of oxidized paraffin and the prepared emulsified wax is described, wherein the preparation of the emulsified wax in this embodiment is the same as in Example 2. The only difference between the preparation of the oxidized paraffin and Example 2 is the oxidation temperature in the preparation method. In this embodiment, the oxidation temperature of 140°C in the preparation method of oxidized paraffin in Example 2 is adjusted to 160°C to obtain oxidized paraffin.

[0060] Comparative Example 1 An oxidized paraffin and its prepared emulsified wax, wherein the preparation of the oxidized paraffin is the same as in Example 1.

[0061] The difference between the preparation of this emulsified wax and Example 1 lies only in the emulsification method. In this comparative example, the emulsification method of Example 1 is adjusted from a simple emulsification method to a D-phase emulsification method. Specifically, The preparation method is (D-phase emulsification method): the emulsifier Tween80 and glycerol solution are dispersed into a homogeneous phase, oxidized paraffin is added under stirring, mixed at 90°C, then deionized water is added and mixed, and cooled to obtain emulsified wax.

[0062] Comparative Example 2 An oxidized paraffin and its prepared emulsified wax, wherein the preparation of the oxidized paraffin is the same as in Example 1.

[0063] The difference between the preparation of this emulsified wax and Example 1 lies only in the emulsification method. In this comparative example, the emulsification method of Example 1 has been changed from emulsification to a phase transition concentration method. Specifically, The preparation method is as follows (phase transition concentration method): oxidized paraffin and emulsifier Tween80 are placed in a reactor and heated to 90°C to melt and mix evenly. Then, a small amount of deionized water at the same temperature is added and mixed evenly. The remaining deionized water at the same temperature is added and stirred evenly. After cooling, emulsified wax is obtained.

[0064] Comparative Examples 3-4 Two comparative examples of oxidized paraffin and the prepared emulsified wax are provided. The preparation of oxidized paraffin in Comparative Examples 3 and 4 is the same as in Example 2. The only difference between Comparative Examples 3 and 4 and Example 2 is the proportion of raw materials in the preparation method.

[0065] Comparative Example 3: Compared with Example 2, the mass ratio of oxidized paraffin to emulsifier in the preparation method of emulsified wax in Example 2 was adjusted from 10:4 to 10:1 to obtain emulsified wax.

[0066] Comparative Example 4: Compared with Example 2, the mass ratio of oxidized paraffin to emulsifier in the preparation method of emulsified wax in Example 2 was adjusted from 10:4 to 10:9 to obtain emulsified wax.

[0067] Comparative Examples 5-6 Two comparative examples of oxidized paraffin and the prepared emulsified wax were provided. The preparation of oxidized paraffin in Comparative Examples 5 and 6 was the same as in Example 2. The only difference between Comparative Examples 5 and 6 and Example 2 was the heating temperature in their preparation methods.

[0068] Comparative Example 5: Compared with Example 2, the heating temperature in the preparation method of emulsified wax in Example 2 was adjusted from 90°C to 70°C to obtain emulsified wax.

[0069] Comparative Example 6: Compared with Example 2, the heating temperature in the preparation method of emulsified wax in Example 2 was adjusted from 90°C to 80°C to obtain emulsified wax.

[0070] Comparative Examples 7-9 Three comparative examples of oxidized paraffin and the prepared emulsified wax were provided. The preparation of the oxidized paraffin in Comparative Examples 7-9 was the same as in Example 2. The only difference between their emulsified waxes and those in Example 2 was the emulsification time. Specifically, Comparative Example 7: Compared with Example 2, the emulsification time in the preparation method of emulsified wax in Example 2 was adjusted from 30 min to 10 min to obtain emulsified wax.

[0071] Comparative Example 8: Compared with Example 2, the emulsification time in the preparation method of emulsified wax in Example 2 was adjusted from 30 min to 50 min to obtain emulsified wax.

[0072] Comparative Example 9: Compared with Example 2, the emulsification time in the preparation method of emulsified wax in Example 2 was adjusted from 30 min to 60 min to obtain emulsified wax.

[0073] Comparative Example 10 This comparative example of emulsified wax differs from Example 2 only in the paraffin raw material used in the preparation method. In this comparative example, the oxidized paraffin raw material used in the emulsified wax preparation method of Example 2 was adjusted to 58# fully refined paraffin (i.e., paraffin without oxidative modification), resulting in the emulsified wax.

[0074] Comparative Examples 11-13 Three comparative examples of oxidized paraffin and the prepared emulsified wax were provided. The preparation of the emulsified wax in Comparative Examples 11-13 was the same as in Example 2. The only difference between their oxidized paraffin preparation and Example 2 was the proportion of the catalyst used in the preparation method. Specifically, Comparative Example 11: Compared with Example 2, the mass fraction of cobalt naphthenate in the catalyst preparation method of Example 2 was adjusted from 35% to 10% to obtain oxidized paraffin.

[0075] Comparative Example 12: Compared with Example 2, the mass fraction of cobalt naphthenate in the catalyst preparation method of Example 2 was adjusted from 35% to 40% to obtain oxidized paraffin.

[0076] Comparative Example 13: Compared with Example 2, the mass fraction of cobalt naphthenate in the catalyst preparation method of Example 2 was adjusted from 35% to 50% to obtain oxidized paraffin.

[0077] Comparative Examples 14-15 Two comparative examples of oxidized paraffin and the prepared emulsified wax were provided. The preparation of the emulsified wax in Comparative Examples 14-15 was the same as in Example 2. The only difference between Comparative Examples 14-15 and Example 2 was the oxidation temperature in the preparation method. Specifically, Comparative Example 14: Compared with Example 2, the oxidation temperature in the preparation method of oxidized paraffin in Example 2 was adjusted from 140°C to 120°C to obtain oxidized paraffin.

[0078] Comparative Example 15: Compared with Example 2, the oxidation temperature in the preparation method of oxidized paraffin in Example 2 was adjusted from 140°C to 180°C to obtain oxidized paraffin.

[0079] Test case Using samples from examples and comparative studies, the acid value and saponification value of the oxidized paraffin and the emulsion properties of the emulsified wax were tested. Emulsion properties included emulsion appearance, emulsion stability, emulsion particle size distribution, and emulsion dispersibility.

[0080] 1. Performance testing of oxidized paraffin (1) Acid value: The determination of the acid value of oxidized paraffin usually follows the industry standard "NB / SH / T 0809 Determination of Acid Value of Natural and Synthetic Waxes", and the specific steps are as follows: Accurately weigh 1-2 grams of paraffin oxide sample (accurate to 0.001 g) and place it in a 250 mL Erlenmeyer flask. Add 40 mL of xylene to the Erlenmeyer flask and install a spherical reflux condenser. Heat the flask in a water bath or on a hot plate, shaking constantly, until the sample is completely dissolved in the solvent. Add 3-5 drops of phenolphthalein indicator to the hot solution. While still hot, titrate with a standardized potassium hydroxide ethanol standard solution (usually about 0.1 mol / L), shaking the Erlenmeyer flask continuously, until the solution turns a light pink color and remains so for at least 10 seconds; this is the titration endpoint. Record the volume of potassium hydroxide ethanol standard solution consumed. To prevent sample saponification, the titration process should be rapid, and repeated heating should be avoided. Perform a blank test (without sample) under the same conditions and record the volume of potassium hydroxide ethanol standard solution consumed in the blank titration. Calculate the acid value based on the measured data.

[0081] (2) Saponification value: The saponification value of oxidized paraffin was determined according to GB / T 8021 "Determination of Saponification Value of Petroleum Products". The specific steps are as follows: Accurately weigh 2-5 grams (accurate to 0.001 g) of the dehydrated and mechanically impurity-free paraffin wax sample and place it in a 250 mL Erlenmeyer flask. If the sample is industrial fatty acid, the weight can be reduced to approximately 2 grams. Accurately add 50 mL of 0.5 mol / L potassium hydroxide ethanol standard solution to the Erlenmeyer flask using a pipette. Connect the Erlenmeyer flask to a reflux condenser and heat under reflux in a boiling water bath for at least 30 minutes until saponification is complete (this can be determined by checking if the solution is clear or free of oil droplets). After saponification, allow it to cool slightly and add 5-10 drops of phenolphthalein indicator; the solution should turn red. Titrate with 0.5 mol / L hydrochloric acid standard solution while hot until the red color of the solution just disappears, which is the endpoint. Record the volume of hydrochloric acid consumed. Perform a blank test under identical conditions, but without adding the paraffin wax sample. Record the volume of hydrochloric acid consumed in the blank test. Calculate the saponification value based on the measured data.

[0082] 2. Determination of the emulsion properties of emulsified waxes (1) Appearance of the emulsion: Take an appropriate amount of emulsion and place it in a 50 mL beaker. First, stir it slowly and evenly with a glass rod. Observe whether there are small solid wax particles inside the emulsion and on the glass rod. Observe whether the emulsion has uniform lines as it is stirred with the glass rod. Then stir it quickly and observe whether the emulsion can form small vortices. Take a certain amount of emulsion above the mouth of the beaker and let it drip slowly. Observe whether there is solid wax residue on the glass rod and the fluidity of the emulsion. If there are no small particles and it can drip back into the beaker, it means that the emulsification effect is relatively ideal.

[0083] (2) Emulsion stability test: The ability of an emulsion to withstand external factors such as gravity and centrifugal force is called emulsion stability. Emulsion stability includes static stability and centrifugal stability. Static stability: Emulsion stability is determined according to GB11543-2008. The emulsion is placed in a glass settling tube, kept at a constant temperature for a certain period of time, and then removed to observe whether the emulsion separates into layers or breaks down. Centrifugal stability: According to GB11543-2008, an appropriate amount of emulsion is placed in a centrifuge tube to about 2 / 3 full, and the centrifuge speed is adjusted to 3000 rpm. The sample is removed after 0.5 hours, and the appearance of the sample in the centrifuge tube before and after centrifugation is compared. No obvious separation indicates that the centrifugal stability is qualified; otherwise, the centrifugal stability of the sample is poor.

[0084] (3) Determination of emulsion particle size distribution: Take 1-2 drops of emulsion and disperse them in deionized water. Place them in an ultrasonic machine for about 3 minutes. Use a Malvern MS2000 laser particle size analyzer to analyze and determine the size and distribution of emulsion particles and obtain the average particle size of the emulsion.

[0085] (4) Determination of emulsion dispersibility: The dispersibility of emulsions can be classified into the following grades based on emulsifiers used in agriculture: Level 1: Visually assess whether the wax emulsion forms a uniform, cloud-like dispersion with a bluish glow upon being added to an aqueous solution; after addition and slight stirring, it becomes a transparent solution, appearing blue or pale white.

[0086] Level 2: Visually assess whether the wax emulsion forms a cloud-like dispersion and exhibits a blue-white fluorescent state upon being dropped into an aqueous solution; after addition and slight stirring, it becomes a translucent solution with a blue color.

[0087] Level 3: By visual inspection, whether the wax emulsion can form a mist or strip-like dispersion when dropped into an aqueous solution and is white; after stirring, it becomes an opaque solution, milky white with a slight fluorescence.

[0088] Level 4: Visually inspect the wax emulsion when dropped into an aqueous solution to see if white microparticles float on the surface; however, after stirring, it becomes an opaque emulsion and appears milky white.

[0089] Level 5: Visually inspect the wax emulsion when dropped into an aqueous solution; observe whether a large number of particles float on the surface. After stirring, it will separate into layers, indicating some emulsification, but the emulsification effect is not ideal. Based on the above description of the five levels of dispersibility, the dispersibility gradually improves from level 5 to level 1.

[0090] The performance test results of the emulsified waxes in Examples 1-10 and Comparative Examples 1-10 are shown in Table 1. The performance test results of the oxidized paraffin and emulsified waxes in Examples 2, 11-13 and Comparative Examples 11-15 are shown in Table 2. Table 1 Table 2 According to the results in Tables 1 and 2, Examples 1-2 and Comparative Examples 1-2 show that the emulsified waxes prepared using the self-emulsification method and the phase transition temperature method have better stability. The emulsified wax prepared using the phase transition temperature method has better emulsion stability, the smallest average particle size (2.36 μm), and better emulsion dispersibility, achieving a secondary dispersibility level. In contrast, the emulsified waxes prepared using the D-phase emulsification method and the phase transition temperature method exhibited stratification and were therefore unqualified.

[0091] The results of Examples 2-5 and Comparative Examples 3-4 show that the stability of the emulsified wax emulsion gradually increases with the increase of emulsifier content. The average particle size first decreases and then increases. At a mass ratio of oxidized paraffin to emulsifier of 10:4, it exhibits a longer standing stability time (>500 h) and better centrifugal stability, with a smaller average particle size of 2.36 μm and a dispersibility level of grade II. The instability of emulsified wax emulsion products is mainly manifested in stratification, flocculation, maturation, aggregation, and phase separation, usually caused by the emulsifier. Insufficient emulsifier dosage cannot effectively reduce the surface tension of the emulsion, leading to unstable emulsion properties. As the emulsifier dosage increases accordingly, the surface tension of the emulsion continuously decreases, resulting in a more stable wax emulsion. Once the critical micelle concentration is reached, the stability of the wax emulsion does not change significantly. Excessive emulsifier, on the other hand, easily generates a large amount of foam, causing a decrease in emulsion quality and increasing production costs.

[0092] The results of Examples 2, 6-8, and Comparative Examples 5-6 show that as the emulsification temperature increases, the average particle size of the emulsion gradually decreases, and the stability increases. The emulsion exhibits optimal performance at an emulsification temperature of 90℃. At excessively low temperatures, the hydrophilicity of the emulsified wax emulsion is poor, failing to effectively emulsify the wax. Furthermore, during the water-added emulsification process, the wax is prone to precipitating as a solid in the liquid phase. At higher temperatures, the thermal motion of molecules in the emulsified wax emulsion intensifies, allowing wax molecules to disperse rapidly in water and easily transforming into a W / O type emulsion. However, the temperature should not be too high either, as excessively high temperatures can decrease the hydrophilicity of the emulsifier, hindering its directional adsorption and reducing the stability of the emulsion.

[0093] The results of Examples 2, 9-10, and Comparative Examples 7-9 show that the stability of the emulsion first increases and then decreases with increasing emulsification time, exhibiting the best emulsion performance at an emulsification time of 30 min. If the emulsification time is too long, the chances of collision and contact between dispersed particles in the emulsified wax emulsion increase, leading to particle aggregation and larger particle size, which in turn increases the viscosity of the emulsified wax emulsion, and in severe cases, it may become a paste. If the stirring time is insufficient, the wax will be unevenly dispersed and will not react completely with the emulsifier, resulting in a wax emulsion with poor stability.

[0094] The results of Example 2 and Comparative Example 10 show that, compared with unmodified paraffin, using oxidized paraffin as the raw material for preparing emulsified wax results in superior emulsion performance, with a standing stability time of >500h, no stratification, an average emulsion particle size of only 2.36μm, and emulsion dispersibility reaching level two.

[0095] The results of Examples 2, 11-12, and Comparative Examples 11-13 show that different mass fractions of cobalt naphthenate affect the acid value and saponification value of the oxidized paraffin. Higher acid and saponification values ​​result in superior emulsified wax performance. When the acid and saponification values ​​are 18 and 20 mgKOH / g, respectively, the emulsion formed by the emulsion contains obvious particulate matter and exhibits poor stability. Therefore, higher acid and saponification values ​​are beneficial for synthesizing emulsified waxes with better performance. When the mass fraction of cobalt naphthenate is 35%, the acid and saponification values ​​are highest, and the synthesized emulsified wax exhibits the best performance.

[0096] The results of Examples 2, 13 and Comparative Examples 14-15 show that the synthesis temperature of paraffin oxide has an impact on the acid value and saponification value of the paraffin oxide. When the synthesis temperature of paraffin oxide is 140℃, the acid value and saponification value are the highest, and the synthesized emulsified wax has the best performance.

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing oxidized paraffin, characterized in that, Includes the following steps: S1. After heating and dissolving paraffin, a catalyst is added to obtain a mixture; The catalyst is prepared as follows: cobalt naphthenate is dissolved in a solvent, manganese dioxide is added, the mixture is stirred for 1-3 hours, and then allowed to stand for 3-6 hours to obtain the reactant. The solvent is then removed, and the reactant is dried to obtain the catalyst. The mass fraction of cobalt naphthenate, based on MnO2, is 20%-35%. S2. The mixture obtained in step S1 is passed through air and fully oxidized at 140~160℃. After cooling, oxidized paraffin is obtained.

2. The preparation method according to claim 1, characterized in that, In step S1, the paraffin wax is paraffin wax with a melting point of 50~70℃; And / or, in step S1, the mass fraction of the catalyst is 0.7% based on the mass of paraffin.

3. The preparation method according to claim 1 or 2, characterized in that, In the catalyst preparation method described in step S1, the drying conditions are drying at 80~100℃ for 3~10 hours; And / or, in the catalyst preparation method described in step S1, the solvent is petroleum ether.

4. The preparation method according to claim 1, characterized in that, In step S2, the volume hourly space velocity of the air is 0.5~1.2 h⁻¹. -1 ; And / or, in step S2, the time for complete oxidation is 1 to 9 hours.

5. The oxidized paraffin obtained by the preparation method according to any one of claims 1 to 4.

6. The use of the oxidized paraffin according to claim 5 in the preparation of emulsified wax.

7. A method for preparing an emulsified wax, characterized in that, The oxidized paraffin wax, emulsifier, and water described in claim 5 are mixed and emulsified to obtain an emulsified wax; The mass ratio of oxidized paraffin to emulsifier is 10:3~7; the emulsification temperature is 90~120℃; and the emulsification time is 20~40min.

8. The preparation method according to claim 7, characterized in that, The emulsification methods include self-emulsification or phase transition temperature methods.

9. The preparation method according to claim 7, characterized in that, The emulsifier includes one of oleic acid, Span 80, triethanolamine oleate, Pintoline O-15, Tween 80, and sodium dodecyl sulfate. And / or, the sum of the mass of the oxidized paraffin and the emulsifier is 15% to 60% of the mass of water.

10. An emulsified wax prepared by the method of any one of claims 7 to 9.

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