Vacuum pressure and heat impregnation method for preparing menthol essential oil sustained-release raw wood fragrance beads

Abstract

This invention discloses a slow-release peppermint essential oil wood scented beads and its preparation method using vacuum pressure and heating impregnation, belonging to the field of fragrance craft preparation technology. The preparation method includes: placing wood beads dried to a moisture content of 8%-12% into a pressure vessel for vacuum degassing; injecting an impregnation solution composed of 70% natural peppermint essential oil and 30% slow-release penetration aids under vacuum, ensuring the wood beads are completely submerged; subsequently, pressurizing and heating the impregnation solution at an impregnation temperature ≤45℃ and a working pressure of 0.3MPa; finally, slowly depressurizing and draining the oil, drying at a low temperature of 45-55℃, and sealing for aging to obtain the finished product. This invention, through the synergistic combination of a core formula and a specific low-temperature, low-pressure vacuum impregnation process, effectively solves the technical defects of ordinary wood scented beads, such as low fragrance loading, rapid evaporation of peppermint essential oil, and the tendency of high-concentration peppermint to cause stickiness and cracking of the wood beads, resulting in a dry surface and a fragrance retention period of 3-4 months.

Description

Technical Field

[0001] This invention belongs to the field of fragrance craft preparation technology, specifically relating to peppermint essential oil slow-release wood fragrance beads and their preparation method by vacuum pressure heating impregnation. Background Technology

[0002] As people's demands for quality of life continue to rise, scented wood products (such as scented wood beads and wood-based fragrance carriers) are increasingly favored for their unique natural texture and aroma. However, there are still many technical bottlenecks in the current market for scented wood products and conventional infusion processes, specifically in the following aspects: Firstly, commercially available scented wood products mainly fall into two categories. The first category consists of scented beads with essential oils sprayed onto their surface. These products only have fragrance applied to the surface of the wood beads, and the essential oils evaporate very quickly, typically lasting only a few days to two weeks, failing to achieve a long-lasting, sustained-release effect. The second category is blended scented beads, which are mainly made by mixing wood powder, adhesives, and fragrances and then pressing them into shape. These products do not use raw wood as the base material for fragrance infusion, and their material's pore structure differs significantly from natural raw wood. They not only lose the unique physical properties and aesthetic appeal of raw wood, but also their fragrance release method is not natural enough.

[0003] Secondly, when preparing scented wood beads using raw wood as the substrate, conventional soaking processes often employ only simple room-temperature soaking. Due to the lack of effective penetration driving forces, the essential oils cannot penetrate deep into the microscopic pores within the wood, resulting in extremely low overall fragrance load in the product. Although some existing technologies have improved the wood impregnation process, they generally lack targeted slow-release essential oil formulations and fail to utilize synergistic processing techniques involving segmented vacuum, heating, and pressurization. This not only leads to short-lasting fragrance in wood products and uneven penetration of essential oils within the wood, but also easily causes physical defects such as cracking of the wood beads during processing or use.

[0004] Finally, the limitations of existing technology are particularly evident for certain types of highly volatile essential oils (such as peppermint oil). Peppermint oil is extremely volatile; the cooling sensation of peppermint beads made using ordinary processes typically disappears completely within 3 to 7 days. At the same time, peppermint oil is highly irritating, and without an effective slow-release carrier to balance its evaporation rate, the high concentration of essential oil can easily damage the wood structure, causing the oil to leach out from the inside of the beads, resulting in a sticky surface and severely affecting the product's appearance and feel.

[0005] In summary, overcoming the problems of low fragrance loading, short fragrance retention time, uneven essential oil penetration, and easy cracking and stickiness of wood beads when adding highly volatile essential oils in existing wood products, and developing a wood infusion process with long-lasting slow-release effect and stable structure has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] The present invention aims to provide a slow-release wood fragrance beads for peppermint essential oil and its preparation method by vacuum pressure heating impregnation, which solves the technical problems of low fragrance loading, short fragrance retention time, uneven essential oil penetration, and easy cracking and stickiness of wood beads when adding highly volatile essential oils in existing wood products.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: Peppermint essential oil slow-release wood fragrance beads, wherein the micropores inside the substrate of the wood fragrance beads are impregnated with a mixture of impregnating oils; By weight percentage, the raw material components of the mixed impregnation oil include: 70% natural peppermint essential oil and 30% slow-release penetration enhancer; The sustained-release penetration enhancer consists of medium-chain triglycerides, macadamia nut oil, vitamin E, and low-temperature plant waxes.

[0008] Furthermore, by weight percentage, the specific components of the sustained-release penetration aid are: 20% medium-chain triglycerides, 7% macadamia nut oil, 2% vitamin E, and 1% low-temperature plant wax.

[0009] Furthermore, the base material of the wood incense beads is any one of poplar, lotus, or beech wood; and the base material is unpainted and unwaxed raw wood beads with a particle size of 10-14mm.

[0010] A method for preparing peppermint essential oil slow-release woody fragrance beads by vacuum pressure heating impregnation, wherein the preparation method adopts an integrated low-temperature, low-pressure vacuum heating process, specifically including the following steps: S1. Pretreatment of log beads: The log raw materials are processed into log beads, and the moisture content of the log beads is controlled at 8%-12% after drying to obtain pretreated log beads. S2. Vacuum degassing: The pre-treated log beads are placed in a container and vacuumed to degas and maintain pressure. S3. Vacuum oiling: Maintain a vacuum state inside the container and inject the prepared mixed impregnation oil to completely submerge the wood beads. S4. Heating and pressurizing impregnation: The container is heated and pressurized, and impregnation is carried out under constant temperature and pressure conditions, so that the mixed impregnation oil can penetrate deeply into the micropores of the wood beads; the impregnation temperature is controlled at 45℃ or below, and the working pressure is controlled at 0.3MPa. S5. Slowly release pressure and drain oil: Release pressure at a uniform rate to normal pressure, remove the log beads and drain the excess mixed impregnation oil from the surface; S6. Low-temperature curing and drying: The drained log beads are dried at a low temperature. S7. Sealed aging: The dried wood beads are sealed and left to age to obtain the high-content peppermint essential oil cooling and slow-release wood beads.

[0011] Furthermore, in step S1, the drying temperature is 60-70℃ and the drying time is 2-4 hours.

[0012] Furthermore, in step S2, the loading into the container specifically involves loading the pretreated log beads into a stainless steel impregnation basket and then placing it into a pressure vessel; the vacuum is then applied to -0.095 to -0.09 MPa, and the pressure holding time is 5 hours.

[0013] Furthermore, in step S4, the specific conditions for the heating and pressurizing impregnation are as follows: the impregnation temperature is 45°C, the working pressure is 0.3MPa, and the constant temperature and pressure impregnation time is 10h.

[0014] Furthermore, in step S6, the temperature for low-temperature drying is 45-55℃, and the drying time is 4-8 hours; in step S7, the time for sealed static curing is 24-72 hours.

[0015] Compared with the prior art, the beneficial effects of the present invention are: (1) Addressing the issue of the high volatility of peppermint essential oil, this invention uses 70% high-content peppermint essential oil to ensure the core refreshing aroma, and creatively combines it with 30% slow-release penetration enhancer composed of medium-chain triglycerides, macadamia nut oil, vitamin E, and low-temperature plant wax. Among them, the rich oil content of macadamia nut oil and the plant wax work synergistically to effectively lock in the volatile components of peppermint, balance the evaporation rate, and significantly extend the fragrance retention period of conventional peppermint wood beads from 3-7 days to 3-4 months (more than 100 days), achieving a long-lasting slow-release effect.

[0016] (2) To address the issues of rapid volatilization of peppermint essential oil at high temperatures and stress concentration and cracking of wood under high pressure, this invention innovatively employs specific process parameters of impregnation temperature ≤45℃ and working pressure 0.3MPa. This integrated and synergistic process ensures that the essential oil penetrates deeply into the micropores of the wood (fragrance content can reach over 40%), while avoiding the oil precipitation and stickiness caused by the strong irritation of high-concentration essential oils. This results in a dry surface for the finished product and effectively reduces the probability of drying cracks, achieving a finished product integrity rate of over 95%.

[0017] (3) The method of this invention does not require the use of artificial adhesives, abandons the traditional method of pressing wood powder into incense beads, and preserves the original physical pore structure and aesthetics of natural porous woods such as poplar, lotus, and beech. The pure wood and natural essential oil system is safe and non-irritating, meets the standards of high-quality fragrance crafts, and has extremely high industrial application value. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0019] Unless otherwise specified in the embodiments of this invention, all conditions are performed under conventional conditions or conditions recommended by the manufacturer. All raw materials used are commercially available. Example 1

[0020] A method for preparing peppermint essential oil sustained-release woody fragrance beads specifically includes the following steps: (1) Pretreatment of log beads: Select unpainted and unwaxed beech logs and process them into log beads with a particle size of 12mm; place them in a drying oven at 60℃ for 2 hours and measure the moisture content to control it at 9% to ensure that the wood pores are fully open. (2) Vacuum degassing: The pretreated beech wood beads are placed in a stainless steel impregnation basket, placed in a pressure vessel, and vacuumed to -0.09MPa. The pressure is maintained for 5 hours to fully extract the air from the pores inside the wood. (3) Vacuum oiling: Maintain a vacuum state (-0.09MPa) in the pressure vessel and inject the prepared mixed impregnation oil into the vessel to completely submerge the wood beads. The total mass of the mixed impregnation oil is 1000g, and the components and amounts are as follows: 700g (70%) of natural peppermint essential oil, 200g (20%) of medium-chain triglycerides (MCT oil), 70g (7%) of macadamia nut oil, 20g (2%) of vitamin E, and 10g (1%) of low-temperature plant wax. (4) Heating and pressurizing impregnation: The pressure vessel is heated to 45°C and pressurized to 0.3 MPa, and kept under constant temperature and pressure for 10 hours. These specific parameters allow the mixed essential oils to penetrate deeply into the micropores of the wood, while avoiding the rapid volatilization of peppermint essential oil due to high temperature. (5) Slowly depressurize and drain oil: After the soaking is completed, slowly depressurize to normal pressure, remove the wood beads and drain the excess mixed essential oil from the surface; (6) Low-temperature curing and drying: The drained log beads are transferred into the drying room and dried at 45°C for 4 hours to cure the trace amount of plant wax and lock in the essential oil inside the wood micropores. (7) Sealed aging: The dried wood beads are placed in a sealed bag and left to stand for 24 hours to allow the aroma to be uniform and stable, thus obtaining the finished product. Example 2

[0021] A method for preparing peppermint essential oil sustained-release woody fragrance beads specifically includes the following steps: (1) Pretreatment of log beads: Select unpainted and unwaxed poplar logs and process them into log beads with a particle size of 10mm; dry them at 65℃ for 3h, and control the moisture content at 10%; (2) Vacuum degassing: Put the log beads into a stainless steel impregnation basket and place it in a pressure vessel, evacuate to -0.095MPa, and maintain the pressure for 5 hours; (3) Vacuum oiling: Maintain a vacuum state and inject the mixed impregnation oil to completely submerge the wood beads. By weight percentage, the mixed impregnation oil includes: 70% natural peppermint oil, 20% medium-chain triglycerides, 7% macadamia nut oil, 2% vitamin E, and 1% low-temperature plant wax; (4) Heating and pressurizing immersion: The container is heated to 40°C and pressurized to 0.3MPa, and kept at constant temperature and pressure for 10 hours; (5) Slowly depressurize and drain the oil: Depressurize at a uniform speed to normal pressure, then remove and drain. (6) Low-temperature curing and drying: Dry at 50℃ for 6 hours; (7) Sealed maturation: Seal and stand for 48 hours to obtain the finished product. Example 3

[0022] A method for preparing peppermint essential oil slow-release wood fragrance beads differs from Example 1 only in the wood substrate used in step (1): Using sapwood logs instead of beech logs, the logs were processed into 14mm diameter round beads. The remaining steps and process parameters were completely consistent with those in Example 1.

[0023] Comparative Example 1 (Conventional room temperature immersion method) A method for preparing fragrant wood beads, the formula of which is the same as that of Example 1, the difference in process is that: beech wood logs with a moisture content of 9% are directly put into the mixed impregnation oil described in Example 1, soaked at room temperature and pressure for 48 hours, then taken out and drained, and dried at 45°C for 4 hours.

[0024] Comparative Example 2 (lacking a sustained-release excipient system) A method for preparing fragrant wood beads, the process parameters of which are exactly the same as those in Example 1, the difference being the impregnation oil formula: 100% pure natural peppermint essential oil is used for impregnation, without the addition of medium-chain triglycerides, macadamia nut oil, vitamin E and low-temperature plant wax.

[0025] Comparative Example 3 (Conventional high-temperature and high-pressure impregnation, without modifications for peppermint essential oil) A method for preparing fragrant wood beads, the formula of which is the same as that in Example 1, the difference being the impregnation parameters in step (4): The pressure vessel was heated to 60°C and pressurized to 0.8 MPa, then kept under constant temperature and pressure for 10 hours. The remaining steps were the same as in Example 1.

[0026] To verify the technical effect of the present invention, the wood incense beads prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests.

[0027] 1. Test environment: temperature 25±2℃, relative humidity 50±5%, indoor natural ventilation.

[0028] 2. Test indicators and methods: (1) Aroma content (%): = (Weight of aged wood beads after impregnation - Weight of dried wood beads after pretreatment) / Weight of dried wood beads after pretreatment × 100%; (2) Lasting power (days): 10 professional perfumers conducted a blind test, smelling the fragrance at regular intervals every day and recording the number of days from the start of the test until the cool minty scent completely dissipated and could not be detected. The average value was taken. (3) Surface dryness: Pinch the wooden beads with your fingers and observe whether there is any oil seepage or stickiness on the surface; (4) Cracking rate of finished product (%): The number of cracks in 1000 samples in each group is counted.

[0029] 3. The test results are shown in Table 1: Table 1 Performance test results of each group of samples Example 1 42.5 115 Dry and non-sticky 2.1 Example 2 45.2 108 Dry and non-sticky 1.5 Example 3 40.8 120 Dry and non-sticky 2.8 Comparative Example 1 15.3 25 Relatively dry 1.0 Comparative Example 2 41.6 12 Extremely sticky and oily 18.5 Comparative Example 3 28.4 45 Slightly sticky 12.3 Results Analysis As can be seen from the comparison between Examples 1-3 and Comparative Example 1, the "vacuum pressure heating impregnation" process of the present invention can significantly increase the fragrance carrying capacity of the wood beads (from 15.3% to more than 40%) and extend the fragrance retention period by several times.

[0030] As can be seen from the comparison between Example 1 and Comparative Example 2, under the same high-content peppermint essential oil conditions, without the slow-release excipient system of the present invention (MCT oil, macadamia nut oil, plant wax, etc.), not only does the peppermint essential oil evaporate extremely quickly (fragrance lasts only 12 days), but the strong irritation of the high-concentration essential oil will also severely damage the wood structure, resulting in a large amount of oil exudation on the surface, making it sticky, and the cracking rate will surge to 18.5%. The excipient system of the present invention successfully plays a role in locking in fragrance, balancing volatilization, and protecting the microstructure of the wood.

[0031] A comparison of Example 1 and Comparative Example 3 shows that while conventional high-temperature and high-pressure impregnation (60℃, 0.8MPa) is suitable for common essential oils, it leads to significant evaporation and loss of highly volatile peppermint essential oil during impregnation and depressurization (fragrance content drops to 28.4%). Furthermore, the high pressure can cause stress concentration within the wood, increasing the cracking rate. The specially designed low-temperature and low-pressure parameters (≤45℃, 0.3MPa) of this invention are key to achieving high fragrance content and low cracking rate in peppermint beads.

[0032] It should be noted that, in this document, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0033] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. Peppermint essential oil slow-release wood scent beads, characterized by: The substrate of the wood incense beads is impregnated with a mixture of impregnating oils in its internal micropores. By weight percentage, the raw material components of the mixed impregnation oil include: 70% natural peppermint essential oil and 30% slow-release penetration enhancer; The sustained-release penetration enhancer consists of medium-chain triglycerides, macadamia nut oil, vitamin E, and low-temperature plant waxes.

2. The peppermint essential oil slow-release woody fragrance beads according to claim 1, characterized in that: The specific components of the sustained-release penetration enhancer, by weight percentage, are: 20% medium-chain triglycerides, 7% macadamia nut oil, 2% vitamin E, and 1% low-temperature plant wax.

3. The peppermint essential oil slow-release woody fragrance beads according to claim 2, characterized in that: The base material of the wood incense beads is any one of poplar, lotus, or beech wood; and the base material is unpainted and unwaxed raw wood beads with a particle size of 10-14mm.

4. A method for preparing slow-release peppermint essential oil wood beads by vacuum pressure heating impregnation, characterized in that: The preparation method employs an integrated low-temperature, low-pressure vacuum heating process, specifically including the following steps: S1. Pretreatment of log beads: The log raw materials are processed into log beads, and the moisture content of the log beads is controlled at 8%-12% after drying to obtain pretreated log beads. S2. Vacuum degassing: The pre-treated log beads are placed in a container and vacuumed to degas and maintain pressure. S3. Vacuum oiling: Maintain a vacuum state inside the container and inject the prepared mixed impregnation oil to completely submerge the wood beads. S4. Heating and pressurizing impregnation: The container is heated and pressurized, and impregnation is carried out under constant temperature and pressure conditions, so that the mixed impregnation oil can penetrate deeply into the micropores of the wood beads; the impregnation temperature is controlled at 45℃ or below, and the working pressure is controlled at 0.3MPa. S5. Slowly release pressure and drain oil: Release pressure at a uniform rate to normal pressure, remove the log beads and drain the excess mixed impregnation oil from the surface; S6. Low-temperature curing and drying: The drained log beads are dried at a low temperature. S7. Sealed aging: The dried wood beads are sealed and left to age to obtain the high-content peppermint essential oil cooling and slow-release wood beads.

5. The method for preparing peppermint essential oil slow-release woody beads by vacuum pressure heating impregnation according to claim 4, characterized in that: In step S1, the drying temperature is 60-70℃ and the drying time is 2-4 hours.

6. The method for preparing peppermint essential oil slow-release woody fragrance beads by vacuum pressure heating impregnation according to claim 4, characterized in that: In step S2, the loading into the container specifically involves loading the pretreated log beads into a stainless steel impregnation basket and then placing it into a pressure vessel; the vacuum is then applied to -0.095 to -0.09 MPa, and the pressure holding time is 5 hours.

7. The method for preparing peppermint essential oil slow-release woody fragrance beads by vacuum pressure heating impregnation according to claim 4, characterized in that: In step S4, the specific conditions for the heating and pressurizing impregnation are: impregnation temperature of 45℃, working pressure of 0.3MPa, and constant temperature and pressure impregnation time of 10h.

8. The method for preparing peppermint essential oil slow-release woody fragrance beads by vacuum pressure heating impregnation according to claim 4, characterized in that: In step S6, the temperature for low-temperature drying is 45-55℃ and the drying time is 4-8h; in step S7, the time for sealed static curing is 24-72h.