A mineral oil emulsion, its preparation method and application

Abstract

This invention provides a mineral oil emulsion formulation, wherein mineral oil within a specific kinematic viscosity and pour point range is prepared into an oil emulsion formulation, which can improve the control efficacy of mineral oil emulsions against crop pests and diseases. When used in the field, the mineral oil emulsion formulation of this invention has good control efficacy against mites on crops such as citrus, tea, and eggplant, especially against citrus psyllids, and also shows good control efficacy against citrus canker. In citrus orchards, it can simultaneously control citrus psyllids and citrus canker, avoiding the long-term use of copper-based pesticides that can induce mite outbreaks, reducing the use of conventional pesticides, lowering pest and disease control costs, and is environmentally friendly.

Description

Technical Field

[0001] This invention relates to the field of pesticide formulations, specifically to a mineral oil emulsion, its preparation method, and its application. Background Technology

[0002] Red spider mites belong to the order Acari, family Tetranychidae ( Tetranychus Spider mites (spp.) are common species including the carmine spider mite, the truncated spider mite, and the citrus spider mite. Spider mites reproduce rapidly, with 10-30 generations per year, overlapping generations, and outbreaks occurring even faster in dry years. They primarily damage vegetable crops such as those in the Solanaceae (eggplant, tomato), Cucurbitaceae (cucumber, melon), Fabaceae (cowpea, kidney bean), and Liliaceae families. Among fruits, citrus, apple, and jujube trees are most severely affected. In severe infestations, solanaceous vegetables (such as eggplant and melon) can suffer yield losses of 20%-40%, and citrus yields can decrease by an average of 30%-50% annually, with some high-incidence areas experiencing total crop failure. In citrus orchards, pesticide costs for spider mite control account for 40%-60% of total production costs, requiring 4-6 applications per year. Resistance to pesticides leads to decreased efficacy, necessitating frequent pesticide changes, resulting in high control costs.

[0003] Citrus canker is caused by Xanthomonas carpetii (… Xanthomonas campestris pv. citri Citrus canker is a bacterial disease caused by bacteria and is subject to plant quarantine both domestically and internationally. It can directly destroy leaves and shoots, reducing the marketability of fruit. Affected orchards typically experience a 10-20% yield reduction, which can reach 30-50% in severe cases. While copper-based fungicides are commonly used to control the disease in citrus orchards, they are not a cure and long-term use can easily induce mite outbreaks, increasing pest and disease control costs.

[0004] Mineral oil is a nonpolar hydrocarbon compound extracted from petroleum. Different mineral oils vary significantly in their hydrocarbon composition and physical properties (viscosity, boiling point, pour point, density, volatility, biodegradability, etc.). In pesticides, mineral oil can be used as a solvent, carrier, or directly as an active ingredient to control pests and diseases, exerting its effect through physical asphyxiation and osmotic interference. The hydrocarbon compounds in agricultural mineral oils typically have a C60-200°C content. 16 -C 30 Within the range, and the non-iodide content is ≥92%, C 21 -C 25 Mineral oils achieve an optimal balance between pesticide activity and crop safety. Products with a narrower carbon chain distribution exhibit more stable performance. Compared to chemical pesticides, mineral oils offer advantages such as safety, environmental friendliness, broad spectrum efficacy, and reduced likelihood of inducing resistance.

[0005] However, mineral oil has a high interfacial tension with water, making spontaneous emulsification difficult. Even when an emulsion forms, it is prone to stratification, flocculation, or demulsification, especially in hard water or under conditions of significant temperature fluctuations, where instability is more pronounced. Furthermore, mineral oil tends to thicken or even solidify at low temperatures, leading to crystallization, precipitation, and loss of fluidity in formulations, rendering them unusable. These problems significantly limit the application of mineral oil in pesticide formulations.

[0006] Chinese patent application CN115281187A discloses a pesticide synergist used as a tank mixing adjuvant. It is mainly composed of refined mineral oil and contains emulsifiers and regulators. It is used to improve the efficacy of insecticides such as abamectin, but is not used directly as a pesticide itself. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a mineral oil emulsion, its preparation method, and its application.

[0008] Generally, agricultural mineral oils meet the requirements of a carbon equivalent (nCy) between nC18 and nC24 and a non-iodide content ≥92%. However, due to different refining processes, different agricultural mineral oil products have complex and varied hydrocarbon compositions, resulting in significant differences in performance. Therefore, it is difficult to characterize their performance and effectiveness using only indicators such as carbon equivalent and non-iodide content. Consequently, different agricultural mineral oil products, as active ingredients, exhibit considerable differences in their effectiveness in controlling pests and diseases.

[0009] Unbound by any theoretical constraints, the inventors believe that kinematic viscosity and pour point reflect the carbon chain structure characteristics of hydrocarbons in mineral oils, including carbon chain length, branched structure, or cyclic structure. Regarding viscosity, the higher the content of straight-chain alkanes in mineral oils, the higher the viscosity due to their regular molecular structure, tight intermolecular arrangement, and strong interactions. Branched molecular structures are irregular, loosely arranged, and have weaker intermolecular forces, resulting in relatively lower viscosity. Cyclic structures significantly increase viscosity; the more rings in the molecule, the higher the viscosity value. Regarding pour point, straight-chain alkanes have the highest melting point; the higher the content of straight-chain alkane components in mineral oils, the higher the pour point. Cyclic and branched structures hinder regular crystal arrangement, thus lowering the pour point.

[0010] Through research, the inventors have discovered that mineral oils with specific kinematic viscosity and pour point ranges can be prepared into oil emulsion formulations. When applied, these formulations can improve the uniformity of the pesticide coverage, enhance adhesion and erosion resistance, maintain sufficient fluidity at low temperatures, and ensure normal application and coverage during cold seasons. This can improve the pest and disease control effect of mineral oil emulsion formulations.

[0011] Based on the above findings, this invention uses refined paraffin-based mineral oil with a carbon equivalent (nCy) in the range of nC18-nC24 and a non-iodide content ≥92% as the base oil, and is implemented using the following technical solution: On the one hand, the present invention provides a mineral oil emulsion, which, by mass percentage, contains 80.0-90.0% mineral oil, 4.0-6.0% emulsifier, 1.0-3.0% antifreeze, and deionized water to make up 100%.

[0012] The kinematic viscosity of mineral oil at 40℃ is 15-20 mm² / s, as determined by GB / T 265-2023 "Determination of Kinematic Viscosity and Calculation of Dynamic Viscosity of Petroleum Products"; and the pour point is -10℃ to -15℃, as determined by GB / T 3535—2006 "Determination of Pour Point of Petroleum Products".

[0013] Preferably, the emulsifier is one or more of the following: phenethylphenol polyoxyethylene ether (e.g., agricultural emulsion 600#), alkylphenol polyoxyethylene ether (e.g., agricultural emulsion 100#, NP series), phenethylphenol polyoxyethylene polyoxypropylene ether (e.g., agricultural emulsion 1601#), alkylphenol polyoxyethylene ether formaldehyde condensate (e.g., agricultural emulsion 700#), castor oil polyoxyethylene ether (e.g., EL-40), fatty alcohol polyoxyethylene ether (e.g., Pingpingjia O series, O-15, O-25), sorbitan fatty acid ester (e.g., Span-40, Nanjing Taihua), dodecylbenzene sulfonate (e.g., calcium or sodium salt), fatty alcohol polyoxyethylene ether sulfate salt, alkylphenol polyoxyethylene ether sulfate salt, fatty alcohol polyoxyethylene ether phosphate, polyoxyethylene sorbitan monostearate (e.g., Tween-60, Nanjing Taihua), and alkylphenol polyoxyethylene ether phosphate.

[0014] Preferably, the antifreeze is one or more of urea, ethylene glycol, propylene glycol, glycerol, diethylene glycol, propylene glycol methyl ether, and sorbitol.

[0015] On the other hand, the present invention provides a method for preparing a mineral oil emulsion, comprising the following steps: (1) Weigh each ingredient according to the formula amount, add mineral oil to the mixing tank, and start stirring; (2) Add emulsifier and stir to mix evenly; (3) Add the antifreeze to deionized water and stir to dissolve it. Then add it to the preparation vessel, shear and mix it evenly. After passing the test, filter, settle, and dispense.

[0016] In winter, if the temperature is low, it will affect the fluidity of the additives. Before use, they can be heated to above 50°C to improve their fluidity and reduce their viscosity, so that they can be added and mixed better.

[0017] The preparation method of the present invention strictly follows the order of material addition, with the oil phase and water phase prepared separately, then mixed, and finally sheared to make the materials uniform.

[0018] On the other hand, the present invention provides the application of using the mineral oil emulsion to control crop diseases and pests.

[0019] Preferably, the crops include citrus, tea trees, eggplant, green peppers, kidney beans, tomatoes, etc.

[0020] Preferably, the pests include citrus spider mite, carmine spider mite, truncated spider mite, two-spotted spider mite, tea tree gall mite, etc.

[0021] Preferably, the diseases include citrus canker, cucumber powdery mildew, etc.

[0022] By adopting the above technical solution, the present invention has the following beneficial effects: (1) The inventors unexpectedly discovered that mineral oils with specific kinematic viscosity and pour point ranges can be prepared into oil emulsion formulations, which can improve the control effect of mineral oil emulsions on crop diseases and pests.

[0023] (2) When used in the field, the mineral oil emulsion formulation of the present invention has good control efficacy against mites on crops such as citrus, tea, and eggplant, especially against citrus parsnipus and eggplant spider mites, and also has good control efficacy against citrus canker. In citrus orchards, it can simultaneously control citrus parsnipus and citrus canker, avoid the long-term use of copper-based formulations that induce spider mite outbreaks, reduce the use of conventional pesticides, lower the cost of pest and disease control, and is environmentally friendly. Attached Figure Description

[0024] Figure 1 This is a production process flow diagram for Example 1. Detailed Implementation

[0025] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] I. Indoor Toxicity Testing The commercially available agricultural mineral oil products purchased all meet the following requirements: carbon equivalent (nCy) in the range of nC18-nC24 and non-iodide content ≥92%.

[0027] The kinematic viscosity of agricultural mineral oil at 40°C was determined according to GB / T 265-2023 "Determination of Kinematic Viscosity and Calculation of Dynamic Viscosity of Petroleum Products", and the pour point of agricultural mineral oil was determined according to GB / T 3535—2006 "Determination of Pour Point of Petroleum Products". Sample MO-1 was purchased from Brent Corporation, USA.

[0028] Table 1 Sample Parameters

[0029] Test insect: Citrus pseudomorphus ( Panonychus citri Sensitive strain female adult mites were raised for multiple generations using fresh citrus tender leaves in an artificial climate chamber with a temperature of 25±1℃, relative humidity of 70±5%, and photoperiod of 16L:8D.

[0030] Formulation preparation: Dilute the two mineral oils to the required concentrations using 0.1% Triton X-100 deionized water. Set up five equal concentration gradients for each mineral oil sample, namely 1200×, 2000×, 2800×, 3600×, and 4000×.

[0031] The spray method was used: Approximately 10 mL of sterilized 1.5% agar was poured into the bottom of the petri dish, allowing it to solidify into a smooth surface. Citrus leaves were laid flat on the agar, back side up, and gently pressed to secure them. On the back of each treated leaf, 30 uniformly sized, highly active adult female mites were attached using a soft brush. The petri dish was placed on the sample stage of the spray tower, with the nozzle adjusted to approximately 20-30 cm from the leaf. Approximately 5 mL of the solution was sprayed evenly using the spray tower at a working pressure of 10 psi, ensuring the leaf surface was completely wetted but without dripping. After spraying, the petri dishes were transferred to an artificial climate chamber, and the lids were opened for ventilation and drying for 30 minutes to allow the solution to form a uniform coating on the leaf surface. The petri dishes were sealed with perforated plastic wrap to prevent mites from escaping. The treated petri dishes were then incubated under the aforementioned climatic conditions. Mite mortality was examined under a stereomicroscope at 24 hours and 48 hours after treatment (death was defined as no reaction when a fine needle was lightly touched to the mite's legs). Each concentration treatment was repeated four times, and the samples were randomly arranged to eliminate positional errors.

[0032] Table 2. Indoor toxicity of different mineral oils to *Pachycerium citrinum* (48 h after treatment)

[0033] II. Low-Temperature Fluidity Test The two mineral oils were diluted 200 times with 0.1% Triton X-100 deionized water and placed in a constant temperature environment of 5℃ for 2 hours to equilibrate. The fluidity of the solution and whether turbidity or oil phase precipitation occurred were observed and recorded. The static contact angle of the solution on the surface of citrus leaves was measured at 5℃ using a contact angle meter to evaluate its low-temperature wetting and spreading ability.

[0034] Table 3 Physical properties of the drug solution at low temperature (5℃)

[0035] The toxicity and low-temperature fluidity test data above show that the kinematic viscosity and pour point of sample MO-1 are within the range required by this invention. The optimized combination of these two key performance parameters ensures that the drug solution can form a uniform, stable, and highly adhesive oil film at both room temperature and low temperature, exhibiting higher toxicity against *Pachycarpus citrinum*. Sample MO-2 has a lower pour point and can maintain fluidity at lower temperatures, but its higher viscosity may lead to poor atomization and coverage uniformity, insufficient effective deposition per unit area, and affect the efficacy of the drug.

[0036] II. Formulation Examples 1. Formulation Table 4 Formulations for each embodiment

[0037] The preparation was carried out according to the above formula and the preparation method given in the invention description section. The production process flow diagram for Example 1 is attached. Figure 1 .

[0038] 2. Testing of formulation quality indicators The relevant quality indicators of the sample in Example 1 were tested.

[0039] Table 5. Sample quality test data for Example 1

[0040] The samples from Examples 2 and 3 were also found to meet the above quality indicators when tested using the same method.

[0041] Surface tension and contact angle of samples in Examples 1-3 were measured: The samples were diluted 200 times with distilled water, and the static surface tension of the drug solution was measured using a surface tension meter. The static contact angle of the drug solution and the change of contact angle over time were measured on a standard hydrophobic surface (paraffin sheet) using a contact angle meter.

[0042] Table 6 Surface tension and contact angle of samples from each embodiment

[0043] The quality test data above show that all embodiments of the present invention meet the requirements of general oil emulsion formulations. The sample in Example 1 maintained a uniform and transparent appearance, had a small contact angle, good spreadability, a rapid decrease in contact angle, and strong penetration.

[0044] III. Field Trials 1. Experiment on the control of citrus pseudomitus Test subject: Citrus fruit (Gonggan variety) Target pests: Citrus pseudomitus ( Panonychus citri ) Test orchard: Liandu Town, Fengkai County, Guangdong Province. Citrus row spacing: 3m × 3.5m. Drainage and irrigation are convenient. The soil is sandy loam dry slope with a deep topsoil, moderate soil organic matter content and fertility, and a pH value of 6.5. The surface is mainly covered with good patchouli. The citrus trees are 5 years old and growing well. The citrus trees are in the fruit coloring stage when the pesticide is applied.

[0045] Test reagent: Sample from Example 1; 20% etoxazole EC (product of Suzhou Jia Hui Chemical Co., Ltd.) Experimental treatment: 1: Sample 1, 350x magnification 2: Sample 1, 500x 3: 20% etoxazole EC3000 times Each treatment consists of 3 fruit trees, with 3 replicates, and the intervals are arranged in a randomized block design.

[0046] Application method: Use a Weishi brand electric sprayer to spray evenly (the spray should penetrate the canopy and cover all leaves at the top and bottom), using 130 liters of solution per acre. The pesticide should be diluted using a two-stage dilution method.

[0047] Efficacy investigation time and method: The population density of *Paecilomyces citrus* in each treatment area was investigated before application and at 2 hours, 1 day, 7 days, 15 days, and 25 days after application. The population reduction rate and control efficacy were calculated. Three trees were investigated for each treatment, and five points were selected on each tree according to the cardinal directions (east, south, west, north, and center). The number of live spider mites on five leaves was investigated at each point. At the same time, any phytotoxicity was observed in each treatment.

[0048] Insect population reduction rate (%) = ×100 Prevention and control effect (%) = ×100 Table 6 Results of the test for controlling citrus pseudomitus

[0049] During the experiment, no phytotoxicity was observed on the leaves and fruits of the fruit trees in all treated areas, and no adverse effects of the pesticide on the natural enemies of the pests were found.

[0050] The experimental results show that the mineral oil emulsion of the present invention has a significant preventive effect within 2 hours after application, while etoxazole has not yet shown any effect. One day after application, the preventive efficacy of the mineral oil emulsion is already over 90%, and reaches 100% on days 7 and 15; etoxazole's efficacy is 50-70%. At 25 days after application, the preventive efficacy of all treatments is above 95%, with no significant difference. This indicates that the agent of the present invention exhibits good rapid action and a long-lasting effect.

[0051] 2. Field efficacy trial for controlling citrus canker The experiment was conducted in the orchard of Taohuayuan Ecological Agriculture Co., Ltd., Baqiao Village, Shuangqiao Town, Wuming District, Nanning. The orchard covers a total area of ​​300 mu (approximately 20 hectares), with good irrigation and drainage conditions and good management. However, 100 mu (approximately 6.7 hectares) of Wogan tangerines have been suffering from citrus canker for many years, with severe infection on young fruit and spring shoots. The experimental fruit trees were growing well, planted at a size of 2.0 meters × 4.0 meters. The soil type was loam, with good irrigation and drainage and a pH of 6.7. Fertilizer and water management were carried out according to local standards, with each tree receiving 5 kg of organic fertilizer + 0.2 kg of urea + 0.2 kg of compound fertilizer (N:P:K = 16:16:16) during the spring shoot stage. No fungicides were applied to the orchard 20 days prior to and during the experiment.

[0052] Experimental target: Citrus canker ( Xanthomonas Campestris (pv. citri), which belongs to the order Pseudomonas, family Xanthomonaceae, and genus Xanthomonas. At the time of the experiment, citrus canker had not yet occurred, indicating a pre-disease stage.

[0053] Table 7 Experimental Design of Test Reagents

[0054] The plots were arranged using a randomized block design, and the distribution map of the field plots is shown below:

[0055] Two citrus trees per plot; three replicates per treatment.

[0056] This experiment involved three applications of the pesticide. Applications were made on June 24, July 6, and July 17, 2020, during the shoot emergence period of the Wogan mandarin orange. The pesticide was applied using a spraying method, with the pesticide solution diluted with water and sprayed evenly onto the plants until they were thoroughly moistened but not dripping. The dilution rate was 1250 liters per hectare. 2 The water consumption of the community is 2.0 liters, and the water consumption of each plant is 1.0 liter.

[0057] This experiment was conducted in two phases. The first phase was conducted on June 24, before the first application of the pesticide. The second phase was conducted on August 8, 22 days after the last application, to assess the efficacy of the pesticide.

[0058] Survey method: Based on the severity of damage symptoms on the leaf sheaths and leaves of citrus trees, two trees were surveyed in each plot. Samples were taken from five points on each tree, covering the east, west, south, north, and center. All leaves on two shoots were surveyed at each point.

[0059] Leaf (fruit) grading standards: Level 0: No disease; Grade 1: 1-5 lesions per leaf (fruit); Grade 3: 6-10 lesions per leaf (fruit); Grade 5: 11-15 lesions per leaf (fruit); Grade 7: 16-20 lesions per leaf (fruit); Grade 9: More than 21 disease spots on each leaf (fruit).

[0060] Disease index = ×100 Control efficacy (without baseline before application) (%) = ×100 In the formula: CK1 -- disease index after drug application in the blank control area; PT1 -- disease index after drug application in the drug-treated area.

[0061] Table 8 Results of the trial for the control of citrus canker

[0062] Field observations showed that during the trial, the citrus trees in each treatment area grew normally, without any obvious symptoms of pesticide damage such as chlorosis, deformity, or poor growth. No significant harmful effects of the pesticide on other organisms were also found.

[0063] The above experimental data show that both the mineral oil emulsion of this invention and the commonly used copper-zinc formulation for controlling citrus canker have good control effects on citrus canker within the tested dosage range. They are safe for citrus trees and have no significant adverse effects on other organisms, and can be used for the control of citrus canker. Using the mineral oil emulsion formulation can replace or reduce the dosage of the copper-zinc formulation, avoiding the outbreak of mite pests induced by long-term use of copper formulations and reducing the cost of pest and disease control.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A mineral oil emulsion, characterized in that, By weight percentage, it contains 80.0-90.0% mineral oil, 4.0-6.0% emulsifier, 1.0-3.0% antifreeze, and deionized water to make up to 100%. Among them, the kinematic viscosity of mineral oil at 40℃ is 15-20 mm² / s, and the pour point is -10℃ to -15℃.

2. The mineral oil emulsion according to claim 1, characterized in that, The emulsifier is one or more of the following: phenethylphenol polyoxyethylene ether, alkylphenol polyoxyethylene ether, phenethylphenol polyoxyethylene polyoxypropylene ether, alkylphenol polyoxyethylene ether formaldehyde condensate, castor oil polyoxyethylene ether, fatty alcohol polyoxyethylene ether, sorbitan fatty acid ester, dodecylbenzene sulfonate, fatty alcohol polyoxyethylene ether sulfate salt, alkylphenol polyoxyethylene ether sulfate salt, fatty alcohol polyoxyethylene ether phosphate, polyoxyethylene sorbitan monostearate, and alkylphenol polyoxyethylene ether phosphate.

3. The mineral oil emulsion according to claim 1, characterized in that, The antifreeze is one or more of urea, ethylene glycol, propylene glycol, glycerol, diethylene glycol, propylene glycol methyl ether, and sorbitol.

4. The mineral oil emulsion according to claim 1, characterized in that, By weight percentage, it contains 80.0% mineral oil, 3.9% dehydrated sorbitan fatty acid ester, 1.1% polyoxyethylene sorbitan monostearate, 2.0% urea, and deionized water to make up 100%.

5. A method for preparing a mineral oil emulsion according to any one of claims 1-4, characterized in that, Includes the following steps: (1) Weigh each ingredient according to the formula amount, add mineral oil to the mixing tank, and start stirring; (2) Add emulsifier and stir to mix evenly; (3) Add the antifreeze to deionized water and stir to dissolve it. Then add it to the preparation vessel, shear and mix it evenly. After passing the test, filter, settle, and package it.

6. The application of a mineral oil emulsion for the prevention and control of crop diseases and pests according to any one of claims 1-4.

7. The application of the mineral oil emulsion for controlling crop diseases and pests according to claim 6, characterized in that, The crops include citrus, tea trees, eggplant, green peppers, kidney beans, and tomatoes.

8. The application of the mineral oil emulsion for controlling crop diseases and pests according to claim 7, characterized in that, The pests include the citrus spider mite, the carmine spider mite, the truncated spider mite, the two-spotted spider mite, and the tea tree gall mite; the diseases include citrus canker and cucumber powdery mildew.

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