Pistacia weinmannifolia mosquito-preventing incense containing coffee grounds

Abstract

The invention provides Pistacia weinmannifolia mosquito-preventing incense containing coffee grounds, and relates to the technical field of aromatic products, the Pistacia weinmannifolia mosquito-preventing incense comprises an inner core serving as an aroma and functional core, the inner core takes porous coffee grounds activated by an alkaline solution as a carrier, pistacia weinmannifolia volatile essential oil which is extracted by a steam distillation method and has mosquito-repelling activity is fully adsorbed and carried in the mosquito-repelling essential oil. The inner core is made of pistacia weinmannifolia essential oil, the protective outer layer wraps the inner core, and the protective outer layer is made of beewax and plays a role in preventing moisture and preventing the essential oil from volatilizing too early before ignition. The incense aims at solving the technical problems that due to the fact that traditional incense is single in structure, active ingredients are prone to volatilization and damp, and the effect is not lasting, and the incense product is remarkable in mosquito repelling effect, even and lasting in fragrance release and excellent in storage performance.

Description

Technical Field

[0001] This invention belongs to the field of aromatic products technology, specifically relating to a fragrant wood incense containing coffee grounds to repel mosquitoes and insects. Background Technology

[0002] Pistacia chinensis (a type of wood used in coffee grounds for mosquito and fly repellent) is a natural aromatic plant. Its leaves and bark are rich in volatile essential oils, which have been used as medicinal ingredients and natural fragrances. Research and traditional applications have shown that the aroma emitted by Pistacia chinensis repels mosquitoes and flies, derived from the highly volatile compounds such as terpenes and esters in its essential oils, including α-pinene, limonene, caryophyllene, and (E)-methyl cinnamate. However, it is precisely the high volatility of these components that constitutes the main technical obstacle to developing stable and long-lasting Pistacia chinensis incense products. The loose and open matrix structure of traditional incense makes it difficult to effectively lock in the highly volatile aromatic wood essential oils. As a result, during product storage and transportation, the key mosquito-repelling active ingredients continue to evaporate into the environment prematurely, significantly reducing the mosquito-repelling effect by the time the product reaches the end user. Furthermore, after being lit, traditional incense tends to release a large amount of essential oil rapidly and concentratedly in the initial stage, forming a brief "flash fire," after which the concentration drops rapidly, failing to provide stable and long-lasting mosquito-repelling protection and greatly reducing the product's practical value. Summary of the Invention

[0003] This invention develops a fragrant wood mosquito repellent incense containing coffee grounds and its preparation method, in order to overcome the inherent defects of traditional fragrant wood incense in terms of easy loss and uncontrollable release of effective ingredients, thereby providing a fragrant wood mosquito repellent incense product containing coffee grounds with stable efficacy and excellent user experience.

[0004] To achieve the above objectives, the present invention is implemented through the following technical solution: A fragrant wood mosquito repellent incense containing coffee grounds includes an inner core and an outer layer. The inner core is a solid composition comprising activated coffee grounds impregnated with fragrant wood volatile essential oils and a nanmu powder binder. The outer layer is a solid coating made of beeswax, which covers the inner core.

[0005] Furthermore, the core also contains coffee husk powder.

[0006] Furthermore, the inner core contains 10-30 parts of fragrant wood essential oil, 30-50 parts of activated coffee grounds, 5-15 parts of coffee fruit peel powder, and 20-40 parts of nanmu powder.

[0007] Furthermore, the activated coffee grounds are prepared by treating raw coffee grounds with an alkaline solution.

[0008] Furthermore, the incense is incense sticks or cones.

[0009] A method for preparing a fragrant wood incense containing coffee grounds to repel mosquitoes, characterized by comprising the following steps: S1. Pretreatment: Collect fresh coffee grounds, rinse with deionized water to remove residual sugar and soluble impurities, and dry in a forced-air drying oven to a moisture content of less than 5%. Crush the dried coffee grounds with a grinder and sieve them to collect particles with a size of 80-120 mesh. S2, Chemical Activation: Immerse the coffee grounds powder from S1 in an alkaline solution and stir in a constant temperature water bath for 1-3 hours to remove cellulose and hemicellulose, increase the porosity and specific surface area of ​​the coffee grounds, and enhance their surface hydrophobicity. S3. Post-processing: Filter and rinse the coffee grounds after S2 activation treatment until the pH of the filtrate is 6.5-7.5. Place the washed activated coffee grounds in the oven again to dry them thoroughly to obtain the final porous activated coffee grounds carrier. S4. Impregnation and adsorption: The volatile essential oil extracted from the fragrant wood is adsorbed into the activated coffee grounds to obtain oil-loaded coffee grounds. S5. Preparation of fragrant clay: Place the oil-loaded coffee grounds, coffee fruit peel powder and camphor wood powder into a mixer according to the weight proportions and mix for 10-15 minutes. While continuously stirring, slowly spray water into the mixed powder. The amount of water should be enough to knead the powder into a ball without sticking to the hands, until the mixture reaches a clay consistency suitable for extrusion molding to obtain fragrant clay. S6. Inner core molding: The S5 incense clay is loaded into the screw extruder, and the incense core is extruded through the die and cut into the required length. The molded inner core is dried until the moisture content of the incense core is less than 10%. S7. Outer coating: Quickly immerse the dry inner core into molten beeswax for 1-3 seconds and then immediately remove it to coat the surface with a layer of wax. Then let it cool naturally. After the beeswax solidifies, it forms a smooth, dense solid outer layer. S8. Aging: Seal the S7 finished product and age it in a cool, dry place for 7-15 days.

[0010] Furthermore, the alkaline solution for chemical activation treatment in S2 is a sodium hydroxide or potassium hydroxide alkaline solution with a concentration of 0.5-2.0 mol / L in an alkaline solution containing coffee grounds and fragrant wood mosquito repellent incense, and the treatment is carried out at 60-90°C.

[0011] Furthermore, the volatile essential oil in S4 is extracted by steam distillation and the adsorption method is vacuum impregnation.

[0012] Furthermore, the vacuum degree of the vacuum impregnation method is -0.08 to -0.095 MPa for the coffee grounds-containing fragrant wood mosquito repellent incense.

[0013] Furthermore, the temperature of the molten coating material in S7 is 65-75°C, and the outer layer thickness is 0.1-0.5 mm.

[0014] The beneficial effects of this invention are: 1. Long-lasting efficacy and stable storage: The outer layer forms a dense physical barrier that effectively isolates external moisture and greatly slows down the volatilization of the fragrant wood essential oil in the core. This allows the mosquito-repelling effect and fragrance of the incense to remain stable after long-term storage, significantly extending the product's shelf life. 2. Uniform and controllable release: After ignition, the outer layer of beeswax melts first, but it does not simply burn away. Instead, it flows downwards under the influence of heat, forming a liquid wax film in the area immediately below the burning end. This liquid wax film covers the inner core, forming a temporary airtight barrier. This prevents the unburned part of the inner core from being heated too early, which would cause the essential oils inside to evaporate prematurely and unnecessarily. The release of essential oils is limited to the section that is burning, thus achieving uniform and gradual evaporation as the inner core burns steadily. This avoids the flash burning and rapid decline in efficacy problems of traditional incense, providing a long-lasting and consistent mosquito repellent and aromatherapy experience. 3. By chemically activating coffee grounds, a common waste product, into a high-performance essential oil carrier, the high-value reuse of resources is achieved, which aligns with the concept of sustainable development.

[0015] 4. The aroma is rich and layered, with a blend of fresh woody notes, slightly roasted coffee grounds, and sweet fruity notes from coffee fruit skins, creating a unique and complex aroma with distinct top, middle, and base notes, resulting in a pleasant user experience. Detailed Implementation

[0016] To make the objectives, technical solutions, and beneficial effects of the present invention clearer, the preferred embodiments of the present invention will be described in detail below to facilitate understanding by those skilled in the art.

[0017] The present invention provides a fragrant wood incense containing coffee grounds to repel mosquitoes and insects. It is in the form of incense sticks and includes an inner core as the main functional part and an outer layer that completely covers the inner core.

[0018] Example 1 A fragrant wood incense containing coffee grounds to repel mosquitoes, wherein the inner core is a solid composition comprising 20 parts fragrant wood essential oil, 40 parts activated coffee grounds, 10 parts coffee fruit peel powder, and 30 parts nanmu powder; and the outer layer is a solid coating composed of beeswax, prepared through the following steps: S1. Pretreatment: Collect fresh coffee grounds and rinse them three times with deionized water to remove residual sugar and soluble impurities; then, dry the washed coffee grounds in a forced-air drying oven at 70°C for 5 hours until their moisture content is less than 5%; then, crush the dried coffee grounds with a grinder and sieve them to collect fine powder with a particle size of 100 mesh. S2, Chemical Activation: The coffee grounds powder obtained in S1 is immersed in a 1 mol / L alkaline sodium hydroxide solution at a material-to-liquid ratio of 1:10 (w / v); and mechanically stirred at 150 rpm for 2 hours in a constant temperature water bath at 70°C. This step aims to remove cellulose and hemicellulose, increase the porosity and specific surface area of ​​the coffee grounds, and enhance their surface hydrophobicity. S3. Post-processing: Filter the coffee grounds after S2 activation treatment and rinse them repeatedly with deionized water until the pH of the filtrate is 7; place the washed activated coffee grounds in an oven at 70°C to dry them thoroughly to obtain the final porous activated coffee grounds carrier. S4. Essential Oil Extraction and Carrier: The dried leaves of *Pterocarya stenoptera* were crushed and steam distilled for 4 hours under normal pressure to collect the volatile essential oil. The oil was then dried with anhydrous sodium sulfate to remove water. The activated coffee grounds carrier obtained in S3 was then placed in a vacuum impregnation tank. The vacuum level inside the tank was evacuated to -0.09 MPa and maintained for 20 minutes to remove air. Subsequently, the extracted *Pterocarya stenoptera* essential oil was slowly dripped onto the coffee grounds using a dripping device. After restoring normal pressure, the coffee grounds were allowed to stand and impregnate for another 3 hours under sealed conditions to obtain oil-loaded coffee grounds. S5. Preparation of the fragrant clay: According to the weight proportions, place the oil-loaded coffee grounds obtained in S4, 100-mesh coffee husk powder, and nanmu powder into a planetary mixer and dry mix for 12 minutes. While continuously stirring, slowly spray pure water into the mixed powder until the mixture reaches a clay-like consistency suitable for extrusion molding to obtain the fragrant clay.

[0019] S6. Incense core molding and drying: The incense mud obtained in S5 is loaded into a screw extruder and extruded through a die with a diameter of 2.0 mm to form the incense core, which is then cut into 15 cm lengths. The molded cores are evenly placed on a grid drying rack and placed in a constant temperature and humidity drying room at 35°C and 45% relative humidity for 36 hours until the moisture content of the incense core is less than 10%. S7. Coating of Outer Layer 2: Place natural beeswax in a temperature-controlled heating kettle and heat to 70°C to melt. Using a rapid impregnation method, immerse the dry inner core 1 in the molten beeswax for 1-3 seconds and immediately remove it, so that a layer of wax is evenly coated on its surface; then allow it to cool naturally on a conveyor belt. After the beeswax solidifies, a smooth, dense solid outer layer with a thickness of about 0.6 mm will be formed on the surface of the inner core. S8. Aging: Seal the finished product obtained in S7 and age it in a cool, dry place for 10 days before it is ready to be shipped.

[0020] Example 2 A fragrant wood incense containing coffee grounds to repel mosquitoes, wherein the inner core is a solid composition comprising 10 parts fragrant wood essential oil, 30 parts activated coffee grounds, 5 parts coffee fruit peel powder, and 20 parts nanmu powder; and the outer layer is a solid coating composed of beeswax, prepared through the following steps: S1. Pretreatment: Collect fresh coffee grounds and rinse them three times with deionized water to remove residual sugar and soluble impurities; then, dry the washed coffee grounds in a forced-air drying oven at 60°C for 4 hours until their moisture content is less than 5%; pulverize the dried coffee grounds with a grinder and sieve them to collect fine powder with a particle size of 80-120 mesh. S2, Chemical Activation: The coffee grounds powder obtained in S1 is immersed in an alkaline sodium hydroxide solution with a concentration of 0.5-2 mol / L, at a material-to-liquid ratio of 1:10 (w / v); and mechanically stirred at 100 rpm for 1-3 hours in a constant temperature water bath at 60°C. This step aims to remove cellulose and hemicellulose, increase the porosity and specific surface area of ​​the coffee grounds, and enhance their surface hydrophobicity. S3. Post-processing: Filter the coffee grounds after S2 activation treatment and rinse them repeatedly with deionized water until the pH of the filtrate is 6.5; place the washed activated coffee grounds in an oven at 60°C to dry them thoroughly to obtain the final porous activated coffee grounds carrier. S4. Essential Oil Extraction and Carrier: The dried leaves of *Pterocarya stenoptera* were pulverized and steam distilled for 3 hours under normal pressure to collect the volatile essential oil. The oil was then dried with anhydrous sodium sulfate to remove water. The activated coffee grounds carrier obtained in S3 was then placed in a vacuum impregnation tank, and the vacuum level inside the tank was evacuated to -0.08 MPa and maintained for 15 minutes to remove air. Subsequently, the extracted *Pterocarya stenoptera* essential oil was slowly dripped onto the coffee grounds using a dripping device. After restoring to normal pressure, the coffee grounds were allowed to stand and impregnate for another 2 hours under sealed conditions to obtain oil-loaded coffee grounds. S5. Preparation of the fragrant clay: According to the weight proportions, place the oil-loaded coffee grounds obtained in S4, 80-mesh coffee husk powder, and camphor wood powder into a planetary mixer and dry mix for 10 minutes. While continuously stirring, slowly spray pure water into the mixed powder until the mixture reaches a clay-like consistency suitable for extrusion molding, thus obtaining the fragrant clay; S6. Incense core forming and drying: The incense mud obtained in S5 is loaded into a screw extruder and extruded through a die with a diameter of 2.0 mm to form the incense core, which is then cut into 15 cm lengths. The formed cores are evenly placed on a grid drying rack and placed in a constant temperature and humidity drying room at 30°C and 40% relative humidity for 24 hours until the moisture content of the incense core is less than 10%. S7. Outer Coating: Place natural beeswax in a temperature-controlled heating kettle and heat to 65°C to melt. Using a rapid immersion method, immerse the dry inner core in the molten beeswax for 1-3 seconds and immediately remove it, so that a layer of wax is evenly coated on its surface. Then, allow it to cool naturally on a conveyor belt. After the beeswax solidifies, a smooth, dense solid outer layer with a thickness of about 0.2 mm will be formed on the surface of the inner core. S8. Aging: Seal the finished product obtained from S7 and age it in a cool, dry place for 7 days before it is ready to be shipped.

[0021] Example 3 A fragrant wood incense containing coffee grounds to repel mosquitoes, wherein the inner core is a solid composition comprising 30 parts fragrant wood essential oil, 50 parts activated coffee grounds, 15 parts coffee fruit peel powder, and 40 parts nanmu powder; and the outer layer is a solid coating composed of beeswax, prepared through the following steps: S1. Pretreatment: Collect fresh coffee grounds and rinse them three times with deionized water to remove residual sugar and soluble impurities. Then, dry the washed coffee grounds in a forced-air drying oven at 80°C for 6 hours until the moisture content is below 5%. Crush the dried coffee grounds with a grinder and sieve them to collect fine powder with a particle size of 120 mesh. S2, Chemical Activation: The coffee grounds powder obtained in S1 is immersed in a 2.0 mol / L alkaline sodium hydroxide solution at a material-to-liquid ratio of 1:10 (w / v); and mechanically stirred at 200 rpm for 1-3 hours in a constant temperature water bath at 90°C. This step aims to remove cellulose and hemicellulose, increase the porosity and specific surface area of ​​the coffee grounds, and enhance their surface hydrophobicity. S3. Post-processing: Filter the coffee grounds after S2 activation treatment and rinse them repeatedly with deionized water until the pH of the filtrate is 7.5; place the washed activated coffee grounds in an 80°C oven to dry them thoroughly to obtain the final porous activated coffee grounds carrier. S4. Essential Oil Extraction and Carrier: The dried leaves of *Pterocarya stenoptera* were pulverized and steam distilled for 5 hours under normal pressure to collect the volatile essential oil. The oil was then dried with anhydrous sodium sulfate to remove water. The activated coffee grounds carrier obtained in S3 was then placed in a vacuum impregnation tank, and the vacuum level inside the tank was evacuated to -0.095 MPa and maintained for 15-30 minutes to remove air. Subsequently, the extracted *Pterocarya stenoptera* essential oil was slowly dripped onto the coffee grounds using a dripping device. After restoring to normal pressure, the coffee grounds were allowed to stand and impregnate for another 4 hours under sealed conditions to obtain oil-loaded coffee grounds. S5. Preparation of the fragrant clay: According to the weight proportions, place the oil-loaded coffee grounds obtained in S4, 120-mesh coffee husk powder, and camphor wood powder into a planetary mixer and dry mix for 10-15 minutes; while continuously stirring, slowly spray pure water into the mixed powder until the mixture reaches a clay consistency suitable for extrusion molding to obtain the fragrant clay. S6. Incense core forming and drying: The incense paste obtained in S5 is loaded into a screw extruder and extruded through a die with a diameter of 2.0 mm to form the incense core, which is then cut into 15 cm lengths. The formed cores are evenly placed on a grid drying rack and placed in a constant temperature and humidity drying room at 40°C and 50% relative humidity for 48 hours until the moisture content of the incense core is less than 10%. S7. Outer Coating: Place natural beeswax in a temperature-controlled heating kettle and heat to 80°C to melt. Using a rapid immersion method, immerse the dry inner core 1 in the molten beeswax for 1-3 seconds and immediately remove it, so that a layer of wax is evenly coated on its surface; then allow it to cool naturally on a conveyor belt. After the beeswax solidifies, a smooth, dense solid outer layer with a thickness of about 0.8 mm will be formed on the surface of the inner core. S8. Aging: Seal the finished product obtained from S7 and age it in a cool, dry place for 15 days before it is ready to be shipped.

[0022] Example 4 Performance Comparison 1. Sample preparation (1) Control sample: a traditional incense stick, the same as the sample in Example 1 (15 cm in length and 2.0 mm in diameter), using the same aromatic load, 20% fragrant wood essential oil, but adopting a single integral structure, that is, unactivated coffee grounds, nanmu powder, essential oil and coffee fruit peel powder are mixed together, without an outer coating; (2) Test samples: Incense sticks prepared in Examples 1-3 were used; 2. Test Plan: Physical properties The two groups of samples were stored under the same environmental conditions (25°C, 60% relative humidity) for 30 days. The aroma intensity, burning time and weight were measured on day 1 and day 30, respectively.

[0023] Table 1. Performance comparison of Examples 1-3 of the present invention with control samples 3. Data Analysis: After 30 days of storage, the aroma intensity and mosquito-repellent effect of the control sample both significantly decreased, and the weight increased significantly and the burning time shortened due to moisture absorption. In contrast, the performance indicators of Examples 1-3 of the present invention remained highly stable due to the protection of the beeswax outer layer, demonstrating its superior shelf life and long-lasting efficacy. As can be seen from the aroma characteristic description, the design of the present invention achieves a gradual and layered release of aroma, providing a better user experience. Since the highly volatile compounds such as terpenes and esters that have a mosquito-repellent effect are related to the aroma, the mosquito-repellent effect of the present invention also follows the gradual and layered release of aroma, while the control sample exhibits the typical characteristic of rapid decay after flash burning, with the mosquito-repellent effect gradually weakening.

[0024] Example 5: Comparison of the effects of outer layer thickness on combustion 1. Sample preparation (1) Core preparation In this comparative experiment, to ensure the uniqueness of the variable, namely the outer layer thickness, the inner cores used in all sample groups (control samples A, B, F and test samples C, D, E) were all from the same batch of incense mud prepared according to the formula of Example 1, so as to ensure that their composition and internal structure were completely consistent.

[0025] The dried inner core is 15 cm long, 2.0 mm in diameter, and has a density of approximately 0.8 g / cm³. The average content of volatile essential oil of fragrant wood in each dried inner core is 75 mg (±2 mg). This is used as the standard amount of effective ingredient for all samples in this experiment.

[0026] (2) Outer coating Test sample C, the inner core of the formulation in Example 1, was subjected to standard impregnation to form a coating with an average thickness of 0.2 mm; Test sample D, the inner core of the formulation in Example 1, was subjected to standard impregnation to form a coating with an average thickness of 0.6 mm; Test sample E, the inner core of the formulation in Example 1, was subjected to standard impregnation to form a coating with an average thickness of 0.8 mm; Control sample A (no outer layer): No outer layer coating was applied; Control sample B (outer layer too thin): Take the inner core of the formulation in Example 1 and perform a rapid immersion (<0.5 seconds) to form a coating with an average thickness of 0.1 mm; Control sample F: Take the inner core of the formulation in Example 1 and slowly impregnate it multiple times to form a coating with an average thickness of 1.0 mm; Five samples were prepared for each group, and all samples were aged under the same conditions for 7 days before testing.

[0027] 2. Testing Methods (1) Physical properties Each sample was precisely weighed before combustion, and its initial mass (m0) was recorded. Each group of samples was then fixed in a windless environment (wind speed <0.1 m / s), at a temperature of 25°C and a relative humidity of 60%. The top of the sample was ignited, and the entire combustion process was recorded using a high-resolution camera. Every 5 minutes, the incense was extinguished from the flame and quickly placed on an electronic balance to weigh its remaining mass (mt). The data was recorded, and the incense was immediately relit and returned to its original position (extinguishing and weighing time was controlled within 15 seconds and included in the total combustion time). The following indicators were observed and measured: Melt flow: Qualitative observation of whether there is a stable, downward-moving liquid wax film below the combustion end.

[0028] Combustion stability: Record whether the combustion process results in mid-combustion failure.

[0029] Wax dripping phenomenon: Record whether molten wax drips from the fragrance.

[0030] Each group of samples was tested three times, and the average value was taken.

[0031] Table 2 Comparison of the effects of different outer layer thicknesses on combustion characteristics 3. Data Analysis The comparison between control B (0.1 mm) and sample C (0.2 mm) shows that when the outer layer thickness is less than 0.2 mm, the beeswax layer is insufficient to accumulate into a liquid film that can flow steadily downwards. Most of it is directly consumed by the flame and cannot form an effective dynamic liquid seal. The comparison between sample E (0.8 mm) and control F (1.0 mm) shows that when the outer layer thickness exceeds 0.8 mm, the heat generated by the burning of the inner core is insufficient to maintain the ideal melting and consumption rate of excess beeswax, causing the molten wax to accumulate and drip. At the same time, excessive liquid wax will soak in and extinguish the flame. The experimental results of test samples C, D, and E all showed stable melt flow phenomena.

[0032] Example 6: Mosquito Repellent Effect 1. Sample preparation The control sample A and test sample D of Example 5 were selected, and the two groups of samples were placed under the same environmental conditions (25°C, 60% relative humidity) and samples were taken on day 1 and day 30 for testing.

[0033] 2. Testing Methods A 10m³ (4m long x 1.5m wide x 1.67m high) sealed glass test space, two identical standardized mosquito traps (trap A and trap B), capable of continuously releasing the same dose of CO2, heat and biomimetic mosquito attractant; Traps A and B were placed at opposite ends of the test space, approximately 3.5 meters apart. A burning incense burner is placed 50 centimeters in front of the trap B; The mosquito release port is located in the very center of the test space.

[0034] (1) Testing process: Benchmark Calibration: Simultaneously activate traps A and B without burning any incense. Release 100 female Aedes albopictus mosquitoes from the central release port. After 15 minutes, record the number of mosquitoes captured by traps A and B respectively. Repeat three times to ensure that the attraction of the two traps to mosquitoes is essentially the same (the difference in the number of mosquitoes captured should be less than 10%), to ensure the fairness of the experiment.

[0035] (2) Sample testing: After lighting a sample to be tested (control sample A or test sample D), place it on the incense burner in front of the trap B.

[0036] At the 5th minute of burning, traps A and B are activated simultaneously, and 100 new female Aedes albopictus mosquitoes are released from the central release port.

[0037] After running for another 10 minutes, stop the trapping process and remove and record the number of mosquitoes captured by trap A (denoted as N_far) and the number of mosquitoes captured by trap B (denoted as N_near).

[0038] (3) Repeat test: For the same incense stick, at the 15th and 35th minute of burning, use a new batch of mosquitoes and a cleaned trap to repeat the above test procedure.

[0039] For samples stored for 30 days, perform all of the above testing steps.

[0040] 4. Data Processing and Based on the recorded data, the spatial protection rate formed by the incense near the trap B was calculated. The higher the protection rate, the stronger its repellent effect, and the more likely mosquitoes are to choose the trap A, which is far away from the incense.

[0041] Protection rate (%) = (N distant - N near) / (N distant + N near) × 100% Table 3. Spatial preservation rate (%) of incense at different storage and burning times 5. Data Analysis: (1) The uniformity and persistence of efficacy In the tests conducted on day 1 and day 30, the space protection rate of the sample of this invention (test sample D) remained stable at over 90% in the early, middle, and late stages of burning (5, 15, and 35 minutes), with minimal fluctuations. The active ingredient was released uniformly, gradually, and at a constant rate, providing a long-lasting and consistent mosquito repellent experience. Control sample A exhibited flashover decay characteristics; its protection rate was acceptable in the early stages of combustion on the first day, but decreased by more than 50% by 35 minutes. This demonstrates that its release was extremely uneven. (2) Storage stability of efficacy Comparing the data from day 1 and day 30, the protection rate of the sample of the present invention hardly decreased after one month of storage, and all values ​​remained above 90%; while the protection rate of control sample A dropped to less than 50% even in the initial stage of combustion (5 minutes) after 30 days of storage.

[0042] This invention solves the technical problems of poor storage stability, efficacy decay over time, uneven release, and efficacy decay during combustion in existing incense products by using an inner core and outer layer composite structure and melt flow controlled release.

[0043] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention.

Claims

1. A fragrant wood incense containing coffee grounds to repel mosquitoes, characterized in that, It includes an inner core and an outer layer, wherein the inner core is a solid composition comprising activated coffee grounds impregnated with volatile essential oils of fragrant wood and a nanmu powder binder; The outer layer is a solid coating made of beeswax, which covers the inner core.

2. The fragrant wood incense containing coffee grounds as described in claim 1, characterized in that, The core also contains coffee husk powder.

3. The fragrant wood incense containing coffee grounds as described in claim 2, characterized in that, The inner core contains 10-30 parts of fragrant wood essential oil, 30-50 parts of activated coffee grounds, 5-15 parts of coffee fruit peel powder, and 20-40 parts of nanmu powder.

4. The fragrant wood incense containing coffee grounds as described in claim 1, characterized in that, The activated coffee grounds are prepared by treating raw coffee grounds with an alkaline solution.

5. The fragrant wood incense containing coffee grounds as described in claim 1, characterized in that, The incense is incense sticks or cones.

6. A method for preparing a fragrant wood incense containing coffee grounds to repel mosquitoes, characterized in that, Includes the following steps: S1. Pre-treatment: Collect fresh coffee grounds, rinse with deionized water to remove residual sugar and soluble impurities, and dry in a forced-air drying oven to a moisture content of less than 5%; The dried coffee grounds are crushed using a grinder and then sieved through a screen to collect particles with a size of 80-120 mesh. S2, Chemical Activation: Immerse the coffee grounds powder from S1 in an alkaline solution and stir in a constant temperature water bath for 1-3 hours to remove cellulose and hemicellulose, increase the porosity and specific surface area of ​​the coffee grounds, and enhance their surface hydrophobicity. S3. Post-processing: Filter and rinse the coffee grounds after S2 activation treatment until the pH of the filtrate is 6.5-7.

5. Place the washed activated coffee grounds in the oven again to dry them thoroughly to obtain the final porous activated coffee grounds carrier. S4. Impregnation and adsorption: The volatile essential oil extracted from the fragrant wood is adsorbed into the activated coffee grounds to obtain oil-loaded coffee grounds. S5. Preparation of fragrant clay: Place the oil-loaded coffee grounds, coffee fruit peel powder and camphor wood powder into a mixer according to the weight proportions and mix for 10-15 minutes. While continuously stirring, slowly spray water into the mixed powder. The amount of water should be enough to knead the powder into a ball without sticking to the hands, until the mixture reaches a clay consistency suitable for extrusion molding to obtain fragrant clay. S6. Inner core molding: The S5 incense clay is loaded into the screw extruder, and the incense core is extruded through the die and cut into the required length. The molded inner core is dried until the moisture content of the incense core is less than 10%. S7. Outer coating: Quickly immerse the dry inner core into molten beeswax for 1-3 seconds and then immediately remove it to coat the surface with a layer of wax. Then let it cool naturally. After the beeswax solidifies, it forms a smooth, dense solid outer layer. S8. Aging: Seal the S7 finished product and age it in a cool, dry place for 7-15 days.

7. The method for preparing the fragrant wood mosquito-repellent incense containing coffee grounds according to claim 6, characterized in that, The chemical activation treatment in S2 is performed in an alkaline solution containing sodium hydroxide or potassium hydroxide at a concentration of 0.5-2.0 mol / L, specifically in an alkaline solution containing coffee grounds and fragrant wood mosquito repellent incense, at a temperature of 60-90°C.

8. The method for preparing the fragrant wood mosquito-repellent incense containing coffee grounds according to claim 6, characterized in that, The volatile essential oil in S4 is extracted by steam distillation and adsorbed by vacuum impregnation.

9. The method for preparing the fragrant wood mosquito-repellent incense containing coffee grounds according to claim 8, characterized in that, The vacuum impregnation method described herein has a vacuum level of -0.08 to -0.095 MPa for the coffee grounds-containing fragrant wood mosquito repellent incense.

10. The method for preparing the fragrant wood mosquito-repellent incense containing coffee grounds according to claim 6, characterized in that, The melting point temperature of the molten coating material in S7 is 65-80°C, and the outer layer thickness is 0.2-0.8 mm.

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