Long-acting fragrance essential oil microcapsule veneer artificial board and preparation method thereof

Abstract

The application discloses a long-acting fragrance essential oil microcapsule veneer artificial board and a preparation method thereof, and comprises a core board, both sides of the core board are provided with surface layer single boards with holes, the surface of the surface layer single boards with holes is sequentially provided with a surface layer thin single board and an impregnated glue film paper; a plurality of waist-shaped through holes are arranged on the surface layer single boards with holes, and the waist-shaped through holes are filled with essential oil microcapsule composite fillers; the essential oil microcapsule composite fillers comprise essential oil microcapsules, putty powder, wood fibers and melamine urea-formaldehyde resin glue; and the essential oil microcapsules comprise single-layer coated microcapsules and double-layer coated microcapsules. The essential oil microcapsules are carried by means of the waist-shaped holes arranged on the surface layer single boards, so that the problem that the adding amount of the microcapsules cannot be improved is solved; and the single-layer and multi-layer microcapsules are simultaneously added, so that the damage of the temperature and pressure in the hot-pressing forming process to the microcapsules is avoided, the long-acting and slow-releasing effect of the fragrance can be realized, and the doped odor generated by the VOC release of the board itself is inhibited.

Description

Technical Field

[0001] This invention relates to the field of decorative panel technology, and in particular to a long-lasting fragrance essential oil microcapsule decorative artificial board and its preparation method. Background Technology

[0002] Essential oils are extracted from the petals, leaves, and roots of plants containing resin glands. They contain many different components, primarily composed of very small molecules. For example, rose essential oil contains over 250 different molecular components. Essential oil molecules are typically short, volatile, and lipophilic, easily penetrating the skin and entering the body through the rich capillaries under the subcutaneous fat. These highly volatile substances can also be absorbed through the nasal mucosa, sending signals directly to the brain and regulating emotions and physiological functions via the limbic system. To overcome the challenge of high volatility and difficulty in long-term preservation in air, microencapsulation technology is used to encapsulate essential oils, enabling slow release of fragrance. This allows for widespread application in daily chemical and textile products. Applying these essential oil microcapsules to decorative engineered wood panels can create a comfortable living environment by slowly releasing fragrance, while also improving and suppressing the inherent odors of the panels themselves, enhancing the product's comfort and friendliness.

[0003] Currently, the technology for fragrance-encapsulated engineered wood panels typically involves adding nano-encapsulated fragrance essential oils to the adhesive used to impregnate decorative paper. After drying, this forms fragrance-impregnated paper, which is then laminated onto the engineered wood panel substrate using a hot-pressing process. The disadvantages of this method are that the fragrance load is too small, and adding too many essential oil microcapsules can affect the adhesive performance, surface color, and texture. During the hot-pressing process of laminating the impregnated paper, some microcapsules are destroyed by mechanical pressure and high temperature, thus reducing the original number of fragrance capsules, resulting in insufficient release concentration and short release time. In addition, some microcapsules are affected by the sealing effect of the adhesive layer in the impregnated paper, which hinders the volatilization of the fragrance essential oils.

[0004] Another method involves soaking the veneer in an emulsion containing fragrance essential oil microcapsules during the plywood manufacturing process. The porosity of the wood is used to hold the fragrance microcapsules. This process is more complex, increasing energy consumption during veneer drying and production losses. At the same time, it also faces the problem of temperature and pressure damaging the microcapsules. Summary of the Invention

[0005] This invention aims to overcome the aforementioned problems of existing fragrance-enhanced engineered wood panels by providing a long-lasting fragrance essential oil microcapsule-coated engineered wood panel and its preparation method. By creating waist-shaped holes in the surface veneer to carry the microcapsules, the problem of not being able to increase the amount of microcapsules added is solved. Furthermore, by simultaneously adding single-layer and multi-layer microcapsules, the damage to the microcapsules caused by temperature and pressure during hot pressing is greatly avoided, while achieving a long-lasting and slow-release effect of fragrance and suppressing the off-odors caused by the release of VOCs from the board itself.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A long-lasting fragrance essential oil microcapsule-faced artificial board includes a core board, with perforated surface veneers on both sides of the core board, and a thin surface veneer and impregnated film paper sequentially disposed on the surface of the perforated surface veneer.

[0008] The perforated surface layer has several waist-shaped through holes, which are filled with essential oil microcapsule composite filler. The essential oil microcapsule composite filler includes essential oil microcapsules, putty powder, wood fiber, and melamine urea-formaldehyde resin. The essential oil microcapsules include single-layer coated microcapsules and double-layer coated microcapsules with a mass ratio of 1:2 to 3. The core material of the single-layer coated microcapsules and double-layer coated microcapsules is plant essential oil. The particle size of the single-layer coated microcapsules is 9 to 25 μm, and the particle size of the double-layer coated microcapsules is 0.5 to 1 μm.

[0009] This invention creates waist-shaped through-holes in the surface of a perforated veneer, using these through-holes as a carrier space for plant essential oil microcapsules. Compared to the impregnated paper coating method, this significantly increases the number and volume fraction of microcapsules. Furthermore, filling the through-holes with microcapsules reduces the damage caused by temperature and pressure during hot pressing, and surface wear of the veneer does not lead to microcapsule damage or shortened lifespan, thus extending the aroma release time of the veneer. In addition, this invention mixes essential oil microcapsules with putty powder and wood fiber as a composite filler. The putty powder and wood fiber in the composite filler construct the internal microporous environment, providing a carrier for the microcapsules. The wood fiber component helps to create fine internal voids, allowing the microcapsules to remain stably within the filler, avoiding loss due to high temperature and pressure, and enabling long-term sustained release. Simultaneously, compared to simple microcapsule filling, the composite filler has sufficient structural strength, facilitating the formation of a complete adhesive layer on the veneer surface, forming a unified whole and avoiding localized looseness; it also maintains the flatness of the veneer surface, preventing bulges, bubbles, and pinhole defects during the finishing process.

[0010] Simultaneously, this invention adds both single-layer and double-layer coated microcapsules with different particle sizes. Compared to single-layer coated microcapsules, the encapsulation effect of the double-layer coated microcapsule core material is significantly improved, which can slow down the evaporation rate of plant essential oils and prolong their evaporation time. Furthermore, the wall material is more flexible and its mechanical strength is improved, which can reduce the breakage rate of microcapsules, enhance their thermal stability and sustained-release performance, thereby achieving the goal of long-lasting fragrance release from the board. However, the double-layer coated microcapsules have a smaller particle size. If used alone, the microcapsules easily agglomerate into clumps when mixed with melamine-urea-formaldehyde resin. Due to the sealing effect of the surface adhesive layer, the plant essential oils inside the clumps are difficult to evaporate, affecting the fragrance release effect of the board. Moreover, the larger pores formed between the larger-particle-size putty powder and wood fibers make it difficult for the smaller-particle-size double-layer coated microcapsules to effectively fill them. The melamine-urea-formaldehyde resin will penetrate into the pores, blocking them and encapsulating the double-layer coated microcapsules, affecting the release of plant essential oils from the microcapsules. Therefore, this invention mixes single-layer coated microcapsules with larger particle sizes with double-layer coated microcapsules. By grading microcapsules of different particle sizes, on the one hand, microcapsule agglomeration in the composite filler can be reduced; on the other hand, the graded microcapsules can more thoroughly fill the pores constructed by the putty powder and wood fibers, making it difficult for melamine-urea-formaldehyde resin to penetrate into the densely filled microcapsule pores and coat the microcapsule surface, further enhancing the fragrance release effect of the board. Furthermore, the dense filling of pores by the graded microcapsules can also improve the strength of the composite filler and reduce the breakage of single-layer coated microcapsules during hot pressing.

[0011] Preferably, each 1000g of essential oil microcapsule composite filler includes 600-700g of putty powder, 80-100g of wood fiber, 130-180g of melamine-urea-formaldehyde resin adhesive, and the remainder is essential oil microcapsules; the length of the wood fiber is 0.2-2mm, and the particle size of the putty powder is 60-80μm; the wall material of the single-layer coated microcapsule is urea-formaldehyde resin; the inner wall material of the double-layer coated microcapsule is polyurethane, and the outer wall material is chitosan.

[0012] Preferably, the length of the waist-shaped through-holes on the perforated surface veneer is 6–9 mm, and the width is 1.5–2 mm; the length direction of the waist-shaped through-holes is consistent with the length direction of the perforated surface veneer. In the prior art, the length direction of the veneer used to manufacture decorative engineered wood panels is the direction of the fibers. This invention sets the waist-shaped through-holes along the fiber direction, which minimizes the proportion of the long fiber cut-off portion of the veneer while ensuring the perforated area; furthermore, this invention sets the waist-shaped through-holes only on the veneers located on the upper and lower surfaces, ensuring the overall static bending strength of the engineered wood panel.

[0013] Preferably, the core board is made of several layers of core veneer glued together; the thickness of the perforated surface veneer is 1.5-2 mm, the thickness of the thin surface veneer is 0.5-0.8 mm, and the basis weight of the impregnated paper is 80-120 g / m². 2 .

[0014] Preferably, the surface of the long-lasting fragrance essential oil microcapsule-coated engineered wood panel is provided with a plurality of laser-drilled micropores. The diameter of the laser-drilled micropores is 0.01–0.05 mm, the spacing is 40–60 mm, and the depth is 1.5–2.5 mm. This invention creates laser-drilled micropores on the surface of the engineered wood panel, forming fragrance release channels. In the event of water contact, due to the surface tension of the water droplets near the micropores, the water will not penetrate into the interior of the panel through the micropores. Furthermore, the micropore size is within the range of this invention, satisfying the normal physical properties of the product surface while being negligible relative to the printed wood grain. Therefore, the micropore processing in this invention does not alter the appearance, color, or texture of the product.

[0015] This invention also discloses a method for preparing the above-mentioned long-lasting fragrance essential oil microcapsule-coated artificial board, comprising the following steps:

[0016] (1) Preparation of single-layer coated microcapsules and double-layer coated microcapsules;

[0017] (2) Mix single-layer coated microcapsules and double-layer coated microcapsules with putty powder, wood fiber and melamine urea-formaldehyde resin to obtain essential oil microcapsule composite filler;

[0018] (3) Punch waist-shaped through holes on the single board, and fill and smooth the waist-shaped through holes with essential oil microcapsule composite filler to obtain a perforated single board on the surface.

[0019] (4) Prepare the core board and glue the core board, the perforated surface veneer, and the thin surface veneer together in sequence with adhesive. After aging, cold press is performed first, followed by hot press, and then ventilation aging is performed after hot press.

[0020] (5) The impregnated paper is glued to the surface of the surface thin veneer and then hot-pressed to obtain a long-lasting fragrance essential oil microcapsule decorative artificial board.

[0021] (6) Laser micropores are processed on long-lasting fragrance essential oil microcapsule-coated artificial boards.

[0022] As a preferred embodiment, the preparation method of the monolayer coated microcapsules in step (1) is as follows: formaldehyde and urea are mixed in a molar ratio of 1.3 to 1.5:1 for prepolymerization to obtain urea-formaldehyde prepolymer; plant essential oil, gum arabic and hydrochloric acid are added to deionized water, stirred and emulsified evenly to obtain an emulsion; the urea-formaldehyde prepolymer is added dropwise to the emulsion, polymerized in situ, and the polymer slurry is spray-dried to obtain monolayer coated microcapsules; the mass ratio of the added plant essential oil to the urea-formaldehyde prepolymer is 1:1.6 to 2.2; the amount of gum arabic added is 5 to 7% of the mass of the plant essential oil, and the concentration of hydrochloric acid in the emulsion is 0.1 to 0.15 mol / L.

[0023] The single-layer coated microcapsules prepared by the method of the present invention have a larger particle size and a wider particle size distribution. When used in combination with double-layer coated microcapsules, they can achieve a better gradation effect.

[0024] As a preferred embodiment, the preparation method of the double-layer coated microcapsules in step (1) is as follows: MDI and plant essential oil are mixed evenly to obtain an oil phase; nonylphenol polyoxyethylene ether is dissolved in water to obtain an aqueous phase; the oil phase and aqueous phase are mixed and dispersed evenly to obtain a suspension, wherein the mass ratio of MDI, plant essential oil and nonylphenol polyoxyethylene ether is 1:1.5~2.5:0.8~1.2; polyethylene glycol and stannous octoate are added sequentially to the suspension, and the mixture is stirred at 30~35℃ for 25~35 min, then 1,3-butanediol is added, the temperature is raised to 75~85℃, and the mixture is stirred for 1~2 h to obtain polyurethane single-layer microcapsules; the mass ratio of polyethylene glycol, stannous octoate, 1,3-butanediol and MDI is 2~2.5:0.7~0.8:0.5~1:1;

[0025] Chitosan was dissolved in hydrochloric acid aqueous solution to obtain a chitosan solution; Tween 80 was dispersed evenly in water, and then polyurethane monolayer microcapsules were added and stirred evenly to obtain a dispersion; the dispersion and chitosan solution were mixed and added to liquid paraffin at 50-55°C, and Tween 80 was added. After stirring evenly, the mixture was cooled to 4-10°C, and glutaraldehyde aqueous solution was added. After stirring and reacting, the product was washed and dried to obtain the double-layer coated microcapsules; the mass ratio of polyurethane monolayer microcapsules, chitosan and glutaraldehyde added was 1.5-2.5:1:0.5-1; the volume fraction of Tween 80 in liquid paraffin was 5-8%.

[0026] The double-layer coated microcapsules prepared by the method of this invention have small particle size and narrow particle size distribution range, which has a good encapsulation effect on plant essential oils. The wall material is flexible, has high mechanical strength, good compressive stability and thermal stability, which can effectively improve the sustained release performance of the core material and prolong the fragrance release time of the board.

[0027] Preferably, the adhesive used in steps (4) and (5) for bonding comprises melamine-modified urea-formaldehyde resin, flour, and a curing agent. The mass of flour is 20-25% of the melamine-modified urea-formaldehyde resin; the mass of the curing agent is 1-3% of the melamine-modified urea-formaldehyde resin; the pH value of the adhesive is 5-6.5; and the coating amount is 180-250 g / m² on one side. 2 .

[0028] Preferably, the temperature during hot pressing in step (4) is 120±5℃ and the pressure is 1~1.6MPa; the temperature during hot pressing in step (5) is 120±5℃ and the pressure is 0.5~1MPa.

[0029] Therefore, the present invention has the following beneficial effects:

[0030] (1) A waist-shaped through hole is opened on the perforated single plate on the surface. The waist-shaped through hole is used as the carrying space for plant essential oil microcapsules. Compared with the impregnation film paper coating method, the number and volume fraction of loaded microcapsules are greatly increased.

[0031] (2) The essential oil microcapsules are mixed with putty powder and wood fiber as a composite filler. The putty powder and wood fiber are used to construct the internal microporous environment, which provides a carrier for the microcapsules, so that the microcapsules are stably kept in the filler, avoiding loss due to high temperature and pressure, and providing the possibility for long-term sustained release.

[0032] (3) Adding single-layer and double-layer coated microcapsules with different particle sizes to the composite filler can improve the long-lasting fragrance release effect of the board. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of the long-lasting fragrance essential oil microcapsule decorative artificial board of the present invention.

[0034] Figure 2 This is a top view of the perforated surface panel of the present invention.

[0035] In the diagram: 1-Essential oil microcapsule composite filler, 2-Perforated surface veneer, 2-1 Waist-shaped through hole, 3-Core board, 4-Thin surface veneer, 5-Impregnated film paper. Detailed Implementation

[0036] The present invention will now be further described with reference to the accompanying drawings and specific embodiments.

[0037] In this invention, unless otherwise specified, all equipment and raw materials are available from the market or commonly used in the industry. The methods in the following embodiments are conventional methods in the field unless otherwise specified.

[0038] General Implementation Examples:

[0039] A long-lasting fragrance essential oil microcapsule-coated engineered wood panel, such as Figure 1 As shown, it includes a core board 3, with perforated surface veneers 2 on both sides of the core board, and a thin surface veneer 4 and an impregnated film paper 5 sequentially disposed on the surface of the perforated surface veneer.

[0040] like Figure 2 As shown, the perforated single-layer board 2 has several layers of uniformly arranged waist-shaped through holes 2-1. The waist-shaped through holes are filled with essential oil microcapsule composite filler 1. The essential oil microcapsule composite filler includes essential oil microcapsules, putty powder, wood fiber and melamine urea-formaldehyde resin glue. The putty powder has a particle size of 60-80μm. The essential oil microcapsules include single-layer coated microcapsules and double-layer coated microcapsules with a mass ratio of 1:2-3. The core material of the single-layer coated microcapsules and double-layer coated microcapsules is plant essential oil. The wall material of the single-layer coated microcapsules is urea-formaldehyde resin with a particle size of 9-25μm. The inner wall material of the double-layer coated microcapsules is polyurethane, and the outer wall material is chitosan with a particle size of 0.5-1μm.

[0041] The surface of the long-lasting fragrance essential oil microcapsule-coated artificial board has several laser micropores.

[0042] In one specific implementation, each 1000g of essential oil microcapsule composite filler includes 600-700g of putty powder, 80-100g of wood fiber, 130-180g of melamine urea-formaldehyde resin glue, and the remainder is essential oil microcapsules; the length of the wood fiber is 0.2-2mm.

[0043] In one specific implementation, the length of the waist-shaped through holes on the perforated surface layer is 6-9 mm and the width is 1.5-2 mm; the length direction of the waist-shaped through holes is consistent with the length direction of the perforated surface layer, and the waist-shaped through holes in adjacent layers are staggered.

[0044] In one specific embodiment, the core board is made of several layers of core veneer glued together; the thickness of the perforated surface veneer is 1.5–2 mm, the thickness of the thin surface veneer is 0.5–0.8 mm, and the basis weight of the impregnated paper is 80–120 g / m². 2 .

[0045] In one specific implementation, the perforated surface veneer and the core veneer are made of Okoume veneer or eucalyptus veneer.

[0046] As one specific implementation method, the laser micropores on the surface of the long-lasting fragrance essential oil microcapsule-coated artificial board have a pore diameter of 0.01-0.05 mm, a spacing of 40-60 mm, and a pore depth of 1.5-2.5 mm.

[0047] The preparation method of the above-mentioned long-lasting fragrance essential oil microcapsule-faced artificial board includes the following steps:

[0048] (1) Preparation of single-layer coated microcapsules and double-layer coated microcapsules;

[0049] (2) Mix single-layer coated microcapsules and double-layer coated microcapsules with putty powder, wood fiber and melamine urea-formaldehyde resin to obtain essential oil microcapsule composite filler;

[0050] (3) Punch waist-shaped through holes on the single board, and fill and smooth the waist-shaped through holes with essential oil microcapsule composite filler to obtain a perforated single board on the surface.

[0051] (4) Prepare the core board and glue the core board, the perforated surface veneer, and the thin surface veneer together in sequence with adhesive. After aging, cold press is performed first, followed by hot press, and then ventilation aging is performed after hot press.

[0052] (5) The impregnated paper is glued to the surface of the thin veneer and then hot-pressed to obtain a long-lasting fragrance essential oil microcapsule decorative artificial board.

[0053] (6) Laser micropores are processed on artificial boards with long-lasting fragrance essential oil microcapsule finish.

[0054] As a specific implementation method, the preparation method of the monolayer coated microcapsules in step (1) is as follows: formaldehyde and urea are mixed in a molar ratio of 1.3 to 1.5:1 for prepolymerization to obtain urea-formaldehyde prepolymer; plant essential oil, gum arabic and hydrochloric acid are added to deionized water, stirred and emulsified evenly to obtain an emulsion; the urea-formaldehyde prepolymer is added dropwise to the emulsion, polymerized in situ, and the polymer slurry is spray-dried to obtain monolayer coated microcapsules; the mass ratio of the added plant essential oil to the urea-formaldehyde prepolymer is 1:1.6 to 2.2; the amount of gum arabic added is 5 to 7% of the mass of the plant essential oil, and the concentration of hydrochloric acid in the emulsion is 0.1 to 0.15 mol / L.

[0055] As one specific implementation method, the prepolymerization reaction of formaldehyde and urea is carried out at a pH of 8-9, a reaction temperature of 60-70°C, and a reaction time of 1-2 hours.

[0056] As a specific implementation method, the preparation method of the double-layer coated microcapsules in step (1) is as follows: MDI and plant essential oil are mixed evenly to obtain an oil phase; nonylphenol polyoxyethylene ether is dissolved in water to obtain an aqueous phase; the oil phase and aqueous phase are mixed and dispersed evenly to obtain a suspension, the mass ratio of MDI, plant essential oil and nonylphenol polyoxyethylene ether is 1:1.5~2.5:0.8~1.2; polyethylene glycol and stannous octoate are added to the suspension in sequence, and the mixture is stirred and reacted at 30~35℃ for 25~35 min, then 1,3-butanediol is added, the temperature is raised to 75~85℃, and the mixture is stirred and reacted for 1~2 h to obtain polyurethane single-layer microcapsules; the mass ratio of polyethylene glycol, stannous octoate, 1,3-butanediol and MDI is 2~2.5:0.7~0.8:0.5~1:1;

[0057] Chitosan was dissolved in hydrochloric acid aqueous solution to obtain a chitosan solution; Tween 80 was dispersed evenly in water, and then polyurethane monolayer microcapsules were added and stirred evenly to obtain a dispersion; the dispersion and chitosan solution were mixed and added to liquid paraffin at 50-55°C, and Tween 80 was added. After stirring evenly, the mixture was cooled to 4-10°C, and glutaraldehyde aqueous solution was added. After stirring and reacting, the product was washed and dried to obtain the double-layer coated microcapsules; the mass ratio of polyurethane monolayer microcapsules, chitosan and glutaraldehyde added was 1.5-2.5:1:0.5-1; the volume fraction of Tween 80 in liquid paraffin was 5-8%.

[0058] As one specific implementation method, when preparing the core board, each core layer veneer is first dried to a moisture content of 5-12 wt% to ensure that the moisture content is not too high and will affect the hot pressing quality; then, each core layer veneer is glued together with an adhesive to obtain the core board; preferably, the number of core layer veneers is odd, the texture direction of the central layer is longitudinal, and the texture directions of adjacent two layers are interwoven.

[0059] In one specific embodiment, the adhesive used in steps (4) and (5) for bonding comprises melamine-modified urea-formaldehyde resin, flour, and a curing agent. The mass of flour is 20-25% of the melamine-modified urea-formaldehyde resin; the mass of the curing agent is 1-3% of the melamine-modified urea-formaldehyde resin; the pH value of the adhesive is 5-6.5; and the coating amount is 180-250 g / m² on one side. 2 .

[0060] As a specific implementation method, the aging time before cold pressing in step (4) is 30 to 60 minutes; after hot pressing, the aging is carried out for 3 to 5 days to ensure that the moisture content tends to be balanced.

[0061] In one specific implementation, the temperature during hot pressing in step (4) is 120±5℃ and the pressure is 1~1.6MPa; the temperature during hot pressing in step (5) is 120±5℃ and the pressure is 0.5~1MPa.

[0062] In one specific implementation, the hot pressing time in step (4) is accumulated at 1 minute per layer of single board; the hot pressing time in step (5) is 4 to 6 minutes.

[0063] Example 1:

[0064] A method for preparing a long-lasting fragrance essential oil microcapsule-coated engineered wood panel, comprising the following steps:

[0065] (1) Preparation of monolayer coated microcapsules: 37wt% formaldehyde solution and urea were mixed at a molar ratio of formaldehyde to urea of ​​1.4:1 and added to deionized water. Triethanolamine was added to adjust the pH of the system to 8.5. The reaction was carried out at 65℃ for 1h to obtain a urea-formaldehyde prepolymer with a solid content of 20wt%. Lavender essential oil, gum arabic and hydrochloric acid were added to deionized water and stirred to emulsify evenly to obtain an emulsion. The urea-formaldehyde prepolymer was added dropwise to the emulsion at a drop rate of 5mL / min. The reaction was carried out at 60℃ for 5h. The polymer slurry was spray-dried to obtain monolayer coated microcapsules with a particle size of 9-20μm. The mass ratio of lavender essential oil to urea-formaldehyde prepolymer was 1:2. The amount of gum arabic added was 6% of the mass of lavender essential oil. The concentration of hydrochloric acid in the emulsion was 0.12mol / L.

[0066] (2) Preparation of double-layer coated microcapsules: MDI and lavender essential oil were mixed evenly to obtain an oil phase; nonylphenol polyoxyethylene ether was dissolved in deionized water to obtain an aqueous phase, with a mass-volume ratio of nonylphenol polyoxyethylene ether to deionized water of 2 g: 100 mL; the oil phase and aqueous phase were mixed and dispersed evenly to obtain a suspension, with a mass ratio of MDI, lavender essential oil and nonylphenol polyoxyethylene ether of 1:2:1; polyethylene glycol and stannous octoate were added to the suspension in sequence, and the mixture was stirred at 30 °C for 30 min, then 1,3-butanediol was added, the temperature was raised to 80 °C, and the mixture was stirred for 1 h to obtain polyurethane single-layer microcapsules; the mass ratio of polyethylene glycol, stannous octoate, 1,3-butanediol and MDI was 2.3:0.75:0.5:1;

[0067] Chitosan was dissolved in hydrochloric acid aqueous solution to obtain a chitosan solution with a concentration of 1.5 wt%. Tween 80 was dispersed evenly in deionized water, and then polyurethane monolayer microcapsules were added. After stirring evenly, a dispersion with a polyurethane monolayer microcapsule concentration of 0.025 g / mL was obtained. The dispersion and chitosan solution were mixed and added to liquid paraffin at 50°C, and Tween 80 was added. After stirring evenly, the mixture was cooled to 5°C, and glutaraldehyde aqueous solution was added. After stirring and reacting for 2 hours, the product was washed and dried to obtain bilayer coated microcapsules with a particle size of 0.5–0.8 μm. The mass ratio of polyurethane monolayer microcapsules, chitosan, and glutaraldehyde added was 2:1:0.7. The volume fraction of Tween 80 in liquid paraffin was 7%.

[0068] By weight, 20 parts of single-layer coated microcapsules, 40 parts of double-layer coated microcapsules, 660 parts of putty powder (240 mesh), 100 parts of wood fiber (1 mm in length) and 180 parts of melamine urea-formaldehyde resin adhesive (Zhonghe Chemical (Shandong) Co., Ltd., brand ZH-258963, content 99%) were mixed evenly to obtain essential oil microcapsule composite filler;

[0069] (4) Dry two layers of Okoume veneer with a thickness of 2mm to a moisture content of 10wt%, and then punch waist-shaped through holes on them. The holes are 8mm long and 2mm wide, and the length direction of the holes is consistent with the length direction of the veneer.

[0070] (5) After punching, the veneer is laid flat on a platform with microporous negative pressure adsorption. After adsorption and flattening, the waist-shaped through holes on the veneer are sealed and smoothed with essential oil microcapsule composite filler to fill the waist-shaped through holes of the veneer and obtain a perforated veneer on the surface.

[0071] (6) Dry three layers of Okoume veneer with a thickness of 2mm to a moisture content of 10wt%; mix melamine-modified urea-formaldehyde resin (Zhonghe Chemical (Shandong) Co., Ltd., brand ZH-258963, content 99%) and flour evenly, then add ammonium chloride curing agent to obtain adhesive. Control the pH value of the adhesive to 6.1. The mass of flour is 23% of the melamine-modified urea-formaldehyde resin; the mass of curing agent is 2% of the melamine-modified urea-formaldehyde resin; use a roller coating method to glue the three layers of dried veneer together with adhesive to obtain a core board. Then glue the perforated veneer to both sides of the core board with adhesive, and then glue the thin veneer (thickness 0.5mm) to the surface of the perforated veneer. The amount of adhesive applied is 200g / m² per side. 2 After the glued boards have been aged for 45 minutes, they are placed in a cold press for pre-pressing, and then hot-pressed for 7 minutes at a temperature of 120℃ and a pressure of 1.2MPa.

[0072] (7) After hot pressing, the boards are trimmed and sanded, then ventilated and left to stand for 3 days. Finally, the weight is 100g / m². 2 Impregnated paper is glued to the surface of a thin veneer, and then hot-pressed at 125℃ and 0.65MPa for 5 minutes to obtain a long-lasting fragrance essential oil microcapsule decorative artificial board.

[0073] (8) Laser micropores with a diameter of 0.02 mm, a spacing of 50 mm, and a depth of 2 mm are processed on the surface of the long-lasting fragrance essential oil microcapsule-coated artificial board.

[0074] Example 2:

[0075] A method for preparing a long-lasting fragrance essential oil microcapsule-coated engineered wood panel, comprising the following steps:

[0076] (1) Preparation of monolayer coated microcapsules: 37wt% formaldehyde solution and urea were mixed at a molar ratio of formaldehyde to urea of ​​1.3:1 and added to deionized water. Triethanolamine was added to adjust the pH of the system to 8. The reaction was carried out at 65℃ for 1h to obtain a urea-formaldehyde prepolymer with a solid content of 20wt%. Lavender essential oil, gum arabic and hydrochloric acid were added to deionized water and stirred to emulsify evenly to obtain an emulsion. The urea-formaldehyde prepolymer was added dropwise to the emulsion at a drop rate of 5mL / min. The reaction was carried out at 60℃ for 5h. The polymer slurry was spray-dried to obtain monolayer coated microcapsules with a particle size of 10-23μm. The mass ratio of lavender essential oil to urea-formaldehyde prepolymer was 1:1.6. The amount of gum arabic added was 5% of the mass of lavender essential oil. The concentration of hydrochloric acid in the emulsion was 0.1mol / L.

[0077] (2) Preparation of double-layer coated microcapsules: MDI and lavender essential oil were mixed evenly to obtain an oil phase; nonylphenol polyoxyethylene ether was dissolved in deionized water to obtain an aqueous phase, with a mass-volume ratio of nonylphenol polyoxyethylene ether to deionized water of 2 g: 100 mL; the oil phase and aqueous phase were mixed and dispersed evenly to obtain a suspension, with a mass ratio of MDI, lavender essential oil and nonylphenol polyoxyethylene ether of 1:1.5:0.8; polyethylene glycol and stannous octoate were added to the suspension in sequence, and the mixture was stirred at 30 °C for 30 min. Then, 1,3-butanediol was added, the temperature was raised to 80 °C, and the mixture was stirred for 1 h to obtain polyurethane single-layer microcapsules; the mass ratio of polyethylene glycol, stannous octoate, 1,3-butanediol and MDI was 2:0.7:1:1;

[0078] Chitosan was dissolved in hydrochloric acid aqueous solution to obtain a chitosan solution with a concentration of 1.5 wt%. Tween 80 was dispersed evenly in deionized water, and then polyurethane monolayer microcapsules were added. After stirring evenly, a dispersion with a polyurethane monolayer microcapsule concentration of 0.025 g / mL was obtained. The dispersion and chitosan solution were mixed and added to liquid paraffin at 50°C, and Tween 80 was added. After stirring evenly, the mixture was cooled to 5°C, and glutaraldehyde aqueous solution was added. After stirring and reacting for 2 hours, the product was washed and dried to obtain bilayer coated microcapsules with a particle size of 0.7–1 μm. The mass ratio of polyurethane monolayer microcapsules, chitosan, and glutaraldehyde added was 1.5:1:1; the volume fraction of Tween 80 in liquid paraffin was 5%.

[0079] (3) By weight, 20 parts of single-layer coated microcapsules, 50 parts of double-layer coated microcapsules, 650 parts of putty powder (240 mesh), 100g of wood fiber (1mm in length) and 180 parts of melamine urea-formaldehyde resin glue (same as in Example 1) are mixed evenly to obtain essential oil microcapsule composite filler.

[0080] (4) Dry two layers of Okoume veneer with a thickness of 2mm to a moisture content of 10wt%, and then punch waist-shaped through holes on them. The holes are 8mm long and 2mm wide, and the length direction of the holes is consistent with the length direction of the veneer.

[0081] (5) After punching, the veneer is laid flat on a platform with microporous negative pressure adsorption. After adsorption and flattening, the waist-shaped through holes on the veneer are sealed and smoothed with essential oil microcapsule composite filler to fill the waist-shaped through holes of the veneer and obtain a perforated veneer on the surface.

[0082] (6) Dry three layers of Okoume veneer with a thickness of 2 mm to a moisture content of 10 wt%; mix melamine-modified urea-formaldehyde resin (same as in Example 1) and flour evenly, then add ammonium chloride as a curing agent to obtain an adhesive. Control the pH value of the adhesive to 5.6. The mass of flour is 20% of the melamine-modified urea-formaldehyde resin; the mass of the curing agent is 3% of the melamine-modified urea-formaldehyde resin. Using a roller coating method, glue the three dried veneers together with the adhesive to obtain a core board. Then, glue the perforated veneer to both sides of the core board with the adhesive. Finally, glue the thin veneer (0.5 mm thick) to the surface of the perforated veneer. The amount of adhesive applied is 200 g / m² on one side. 2 After the glued boards have been aged for 45 minutes, they are placed in a cold press for pre-pressing, and then hot-pressed for 7 minutes at a temperature of 120℃ and a pressure of 1.2MPa.

[0083] (7) After hot pressing, the boards are trimmed and sanded, then ventilated and left to stand for 3 days. Finally, the weight is 100g / m². 2 Impregnated paper is glued to the surface of a thin veneer, and then hot-pressed at 125℃ and 0.65MPa for 5 minutes to obtain a long-lasting fragrance essential oil microcapsule decorative artificial board.

[0084] (8) Laser micropores with a diameter of 0.02 mm, a spacing of 50 mm, and a depth of 2 mm are processed on the surface of the long-lasting fragrance essential oil microcapsule-coated artificial board.

[0085] Example 3:

[0086] A method for preparing a long-lasting fragrance essential oil microcapsule-coated engineered wood panel, comprising the following steps:

[0087] (1) Preparation of monolayer coated microcapsules: 37wt% formaldehyde solution and urea were mixed at a molar ratio of formaldehyde to urea of ​​1.5:1 and added to deionized water. Triethanolamine was added to adjust the pH of the system to 8. The reaction was carried out at 65℃ for 1h to obtain a urea-formaldehyde prepolymer with a solid content of 20wt%. Lavender essential oil, gum arabic and hydrochloric acid were added to deionized water and stirred to emulsify evenly to obtain an emulsion. The urea-formaldehyde prepolymer was added dropwise to the emulsion at a drop rate of 5mL / min. The reaction was carried out at 60℃ for 5h. The polymer slurry was spray-dried to obtain monolayer coated microcapsules with a particle size of 11-25μm. The mass ratio of lavender essential oil to urea-formaldehyde prepolymer was 1:2.2. The amount of gum arabic added was 7% of the mass of lavender essential oil. The concentration of hydrochloric acid in the emulsion was 0.15mol / L.

[0088] (2) Preparation of double-layer coated microcapsules: MDI and lavender essential oil were mixed evenly to obtain an oil phase; nonylphenol polyoxyethylene ether was dissolved in deionized water to obtain an aqueous phase, with a mass-volume ratio of nonylphenol polyoxyethylene ether to deionized water of 2 g: 100 mL; the oil phase and aqueous phase were mixed and dispersed evenly to obtain a suspension, with a mass ratio of MDI, lavender essential oil and nonylphenol polyoxyethylene ether of 1:2.5:1.2; polyethylene glycol and stannous octoate were added to the suspension in sequence, and the mixture was stirred at 30 °C for 30 min, then 1,3-butanediol was added, the temperature was raised to 80 °C, and the mixture was stirred for 1 h to obtain polyurethane single-layer microcapsules; the mass ratio of polyethylene glycol, stannous octoate, 1,3-butanediol and MDI was 2.5:0.8:0.5:1;

[0089] Chitosan was dissolved in hydrochloric acid aqueous solution to obtain a chitosan solution with a concentration of 1.5 wt%. Tween 80 was dispersed evenly in deionized water, and then polyurethane monolayer microcapsules were added. After stirring evenly, a dispersion with a polyurethane monolayer microcapsule concentration of 0.025 g / mL was obtained. The dispersion and chitosan solution were mixed and added to liquid paraffin at 50°C, and Tween 80 was added. After stirring evenly, the mixture was cooled to 5°C, and glutaraldehyde aqueous solution was added. After stirring and reacting for 2 hours, the product was washed and dried to obtain bilayer coated microcapsules with a particle size of 0.6–0.9 μm. The mass ratio of polyurethane monolayer microcapsules, chitosan, and glutaraldehyde added was 2.5:1:0.5. The volume fraction of Tween 80 in liquid paraffin was 9%.

[0090] (3) By weight, 20 parts of single-layer coated microcapsules, 60 parts of double-layer coated microcapsules, 640 parts of putty powder (240 mesh), 100g of wood fiber (1mm in length) and 180 parts of melamine urea-formaldehyde resin glue (same as in Example 1) are mixed evenly to obtain essential oil microcapsule composite filler.

[0091] (4) Dry two layers of Okoume veneer with a thickness of 2mm to a moisture content of 10wt%, and then punch waist-shaped through holes on them. The holes are 8mm long and 2mm wide, and the length direction of the holes is consistent with the length direction of the veneer.

[0092] (5) After punching, the veneer is laid flat on a platform with microporous negative pressure adsorption. After adsorption and flattening, the waist-shaped through holes on the veneer are sealed and smoothed with essential oil microcapsule composite filler to fill the waist-shaped through holes of the veneer and obtain a perforated veneer on the surface.

[0093] (6) Dry three layers of Okoume veneer with a thickness of 2 mm to a moisture content of 10 wt%; mix melamine-modified urea-formaldehyde resin (same as in Example 1) and flour evenly, then add ammonium chloride as a curing agent to obtain an adhesive. Control the pH value of the adhesive to 6.4. The mass of flour is 25% of the melamine-modified urea-formaldehyde resin; the mass of the curing agent is 1% of the melamine-modified urea-formaldehyde resin. Using a roller coating method, glue the three dried veneers together with the adhesive to obtain a core board. Then, glue the perforated surface veneer to both sides of the core board with the adhesive. Finally, glue the thin surface veneer (0.5 mm thick) to the surface of the perforated surface veneer. The amount of adhesive applied is 200 g / m² on one side. 2 After the glued boards have been aged for 45 minutes, they are placed in a cold press for pre-pressing, and then hot-pressed for 7 minutes at a temperature of 120℃ and a pressure of 1.2MPa.

[0094] (7) After hot pressing, the boards are trimmed and sanded, then ventilated and left to stand for 3 days. Finally, the weight is 100g / m². 2 Impregnated paper is glued to the surface of a thin veneer, and then hot-pressed at 125℃ and 0.65MPa for 5 minutes to obtain a long-lasting fragrance essential oil microcapsule decorative artificial board.

[0095] (8) Laser micropores with a diameter of 0.02 mm, a spacing of 50 mm, and a depth of 2 mm are processed on the surface of the long-lasting fragrance essential oil microcapsule-coated artificial board.

[0096] Comparative Example 1:

[0097] The difference between Comparative Example 1 and Example 1 is that in step (3), 60 parts by weight of single-layer coated microcapsules are mixed evenly with 660 parts of putty powder, 100g of wood fiber and 180 parts of melamine urea-formaldehyde resin to obtain essential oil microcapsule composite filler; the rest are the same as in Example 1.

[0098] Comparative Example 2:

[0099] The difference between Comparative Example 2 and Example 1 is that in step (3), 60 parts by weight of double-layer coated microcapsules are mixed evenly with 660 parts of putty powder, 100g of wood fiber and 180 parts of melamine urea-formaldehyde resin to obtain essential oil microcapsule composite filler; the rest are the same as in Example 1.

[0100] Comparative Example 3:

[0101] The difference between Comparative Example 3 and Example 1 is that in step (3), 275 parts by weight of single-layer coated microcapsules, 550 parts by weight of double-layer coated microcapsules and 175 parts by weight of melamine urea-formaldehyde resin are mixed evenly to obtain essential oil microcapsule composite filler; the rest are the same as in Example 1.

[0102] Comparative Example 4:

[0103] The difference between Comparative Example 4 and Example 1 is that in step (3), 50 parts by weight of single-layer coated microcapsules, 100 parts by weight of double-layer coated microcapsules, 660 parts by weight of putty powder and 190 parts by weight of melamine urea-formaldehyde resin glue are mixed evenly to obtain essential oil microcapsule composite filler; the rest are the same as in Example 1.

[0104] Comparative Example 5:

[0105] The difference between Comparative Example 5 and Example 1 is that the three-layer core layer single plate also has the same waist-shaped through holes as the surface perforated single plate, and is filled with the same essential oil microcapsule composite filler as in Example 1. The rest are the same as in Example 1.

[0106] The long-lasting fragrance essential oil microcapsule-coated artificial boards prepared in the above embodiments and comparative examples were sawn into 500mm×500mm samples, and their mechanical properties and fragrance sustained-release properties were tested. The results are shown in Table 1.

[0107] The test methods for mechanical properties refer to GB17657-2022;

[0108] The test method for aroma sustained-release performance is as follows: Samples are ventilated and left to stand for 48 hours for equilibration, then subjected to accelerated release at 60℃ and 100℃ for 30 days respectively. The equilibrated and accelerated-release samples are then placed in a 1m... 3 The aroma released was evaluated after 1 hour inside a glass box with two 20mm diameter holes on each side.

[0109] Table 1: Performance test results of decorative engineered wood panels.

[0110]

[0111] As can be seen from Table 1, the decorative artificial boards prepared by the method of this invention in Examples 1-3 have excellent mechanical properties and can achieve long-term sustained release of fragrance. Even after 30 days of accelerated release at 100°C, the fragrance is still noticeable. In contrast, Comparative Example 1 only added single-layer coated microcapsules to the filler, without adding double-layer coated microcapsules. The single-layer coated microcapsules are easily damaged during hot pressing, resulting in a faster fragrance release rate. After 30 days of accelerated release at 60°C, the fragrance has become significantly weaker, and after 30 days of accelerated release at 100°C, the fragrance is almost gone, failing to achieve long-term fragrance release. Furthermore, the lack of double-layer coated microcapsules also leads to a decrease in the mechanical properties of the board. In Comparative Example 2, only double-layer coated microcapsules were added to the filler, without adding single-layer coated microcapsules. The lack of the grading effect of the larger-particle-size single-layer coated microcapsules resulted in a decrease in the mechanical properties of the board compared to Example 1. Furthermore, the absence of gradation made the double-layer coated microcapsules prone to agglomeration and surface encapsulation by the adhesive in the composite filler, affecting the release of plant essential oils. The released fragrance was less pronounced compared to the examples, and after 30 days of accelerated release at 100°C, no noticeable fragrance was detected. In Comparative Example 3, no putty powder or wood fiber was added to the essential oil microcapsule composite filler. In Comparative Example 4, putty powder was added but no wood fiber was added. The mechanical properties of the boards were significantly reduced compared to Example 1. The lack of the microporous structure constructed by putty powder and wood fiber made the microcapsules more susceptible to damage during hot pressing. Therefore, the long-lasting sustained-release performance of the fragrance in Comparative Examples 3 and 4 was also reduced, and after 30 days of accelerated release at 100°C, no noticeable fragrance was detected. In Comparative Example 5, waist-shaped through holes were also made in the core board to fill the composite filler of essential oil microcapsules. Although the aroma slow-release performance of the board was improved, the static bending strength of the board was significantly reduced and could not meet the needs of use.

Claims

1. A method for preparing a long-acting fragrance oil microcapsule coated artificial board, characterized by the steps of The method comprises the following steps: (1) mixing MDI and plant essential oil to obtain an oil phase, and dissolving nonylphenol polyoxyethylene ether in water to obtain an aqueous phase; After the oil phase and the aqueous phase are mixed and dispersed, polyethylene glycol and stannous octoate are added in sequence, and then 1,3-butanediol is added after stirring and reaction to obtain polyurethane single-layer microcapsules; Chitosan is dissolved in an aqueous HCl solution to obtain a chitosan solution; Tween 80 is dispersed in water, and then the polyurethane single-layer microcapsules are added, stirred, and then mixed with the chitosan solution; the obtained dispersion is added to liquid paraffin, and then Tween 80 is added, stirred and cooled, and then an aqueous glutaraldehyde solution is added, stirred and reacted, and then the product is washed and dried to obtain double-layer coated microcapsules; (2) mixing the single-layer coated microcapsules, the double-layer coated microcapsules, putty powder, wood fibers and melamine urea-formaldehyde resin glue to obtain essential oil microcapsule composite fillers; (3) punching waist-shaped through holes on a single board, filling and smoothing the waist-shaped through holes with the essential oil microcapsule composite fillers to obtain a surface layer single board with holes; (4) preparing a core board, and sequentially gluing the core board, the surface layer single board with holes and a surface layer thin single board by using a glue, and then performing cold pressing, hot pressing and air seasoning; (5) gluing impregnated glue film paper on the surface of the surface layer thin single board, and then performing hot pressing and laser micro-hole processing.

2. The method for producing a long-lasting, fragranced, microencapsulated oil-based decorative panel according to claim 1, characterized in that, In step (2), the single-layer coated microcapsules are prepared by the following method: mixing formaldehyde and urea at a molar ratio of 1.3-1.5:1 to obtain a urea-formaldehyde prepolymer; adding plant essential oil, gum arabic and hydrochloric acid into deionized water, stirring and uniformly emulsifying to obtain an emulsion; adding the urea-formaldehyde prepolymer into the emulsion, in-situ polymerizing, and then spray drying the polymer slurry to obtain single-layer coated microcapsules; the mass ratio of the added plant essential oil to the urea-formaldehyde prepolymer is 1:1.6-2.2; the gum arabic is added in an amount of 5-7% of the mass of the plant essential oil; and the concentration of hydrochloric acid in the emulsion is 0.1-0.15 mol / L.

3. The method for preparing long-lasting fragranced microencapsulated oil-based wood-based panels according to claim 1, characterized in that, The adhesive used in the gluing in steps (4) and (5) comprises melamine modified urea-formaldehyde resin, flour and curing agent, the mass of the flour is 20-25% of the melamine modified urea-formaldehyde resin; the mass of the curing agent is 1-3% of the melamine modified urea-formaldehyde resin, the pH value of the adhesive is 5-6.5; the glue coating amount is 180-250 g / m 2 .

4. The method for preparing the long-lasting fragrance essential oil microcapsule-coated artificial board according to claim 1, characterized in that, In step (4), the temperature during hot pressing is 120±5°C, and the pressure is 1-1.6 MPa; in step (5), the temperature during hot pressing is 120±5°C, and the pressure is 0.5-1 MPa.

5. A long-lasting fragranced oil microcapsule coated artificial board prepared by the method according to any one of claims 1 to 4, characterized in that, The core board is provided with surface layer single boards with holes on both sides, and the surface of each surface layer single board with holes is sequentially provided with a surface layer thin single board and impregnated glue film paper; The surface layer single board with holes is provided with a plurality of waist-shaped through holes, and the waist-shaped through holes are filled with essential oil microcapsule composite fillers; the essential oil microcapsule composite fillers comprise essential oil microcapsules, putty powder, wood fibers and melamine urea-formaldehyde resin glue; the essential oil microcapsules comprise single-layer coated microcapsules and double-layer coated microcapsules at a mass ratio of 1:2-3, and the core material of the single-layer coated microcapsules and the double-layer coated microcapsules is plant essential oil; The particle size of the single-layer coated microcapsules is 9-25 µm; and the particle size of the double-layer coated microcapsules is 0.5-1 µm.

6. The long-lasting, microencapsulated, fragranced oil-finished wood-based panel according to claim 5, characterized in that, Each 1000g of the microcapsule composite filler of essential oil comprises putty 600-700g, wood fiber 80-100g, melamine urea-formaldehyde resin glue 130-180g, and the rest is microcapsule of essential oil; the length of the wood fiber is 0.2-2mm, and the particle size of the putty is 60-80µm; the wall material of the single-layer coated microcapsule is urea-formaldehyde resin; the inner wall material of the double-layer coated microcapsule is polyurethane, and the outer wall material is chitosan.

7. The long-lasting, microencapsulated, fragranced-oil finished wood-based panel according to claim 5, characterized in that, The length of the waist-shaped through hole on the surface layer single board with holes is 6-9mm, and the width is 1.5-2mm; the length direction of the waist-shaped through hole is consistent with the length direction of the surface layer single board with holes.

8. The long-lasting, microencapsulated, fragranced-oil finished wood-based panel according to claim 5, characterized in that, The core plate is made of several layers of core layer single boards; the thickness of the surface layer single board with holes is 1.5-2 mm, the thickness of the surface layer thin single board is 0.5-0.8 mm, and the gram weight of the impregnated glue film paper is 80-120 g / m 2 .

9. The long-lasting, microencapsulated fragrant essential oil finished wood-based panel according to claim 5 or 8, characterized in that, The surface of the long-acting fragrance essential oil microcapsule decorative artificial board is provided with a plurality of laser micro-holes, the pore size of the laser micro-holes is 0.01-0.05mm, the pitch is 40-60mm, and the hole depth is 1.5-2.5mm.

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