A thin-skin direct-attach processing technology

Abstract

This invention belongs to the field of board processing technology, specifically relating to a thin-veneer direct-lamination processing technology. The process includes the following steps: veneer cutting and selection; veneer pretreatment; gluing the board; veneer application; hot pressing; unloading and edge trimming to obtain veneered boards. This invention uses a thin-veneer direct-lamination method, simplifying the process and reducing costs through direct hot pressing. By optimizing process parameters and adhesive formulation, the veneered products exhibit good aesthetics, improved adhesion strength between the veneer and the board, and also possess high-temperature resistance, oxidation resistance, and good stability. They do not oxidize and blacken after hot pressing, effectively overcoming the shortcomings of existing technologies.

Description

Technical Field

[0001] This invention belongs to the field of board processing technology, specifically relating to a thin veneer direct bonding process, and more specifically to a thin wood veneer direct bonding process for boards. Background Technology

[0002] The wood veneer used on the surface of furniture panels has always been a crucial part of production costs. Whether it's raw wood veneer or engineered veneer, the price is calculated based on thickness; the thicker the veneer, the more expensive it is, but also the easier it is to apply. Currently, there are two common application methods: One is the thick veneer application method, generally 0.3 mm or thicker. This involves cutting and sewing the veneer, applying glue to the board surface, placing the sewn veneer on the glued surface, and then hot-pressing and curing it. The other is the thin veneer application method, generally 0.1 to 0.25 mm thick. This involves applying glue to the board surface, spraying water on the veneer, overlapping it by 0.1 to 0.5 mm, and then pressing it into a cold press. After the surface moisture is absorbed by the board or air and it becomes surface dry (one to two days), the overlapping parts are manually removed, and any chipped or missing veneer areas are repaired. Then, it is hot-pressed, cured, and finished. Thick veneer is more expensive, with a utilization rate of around 60%. Thin veneer, because it's too thin, will shrink and wrinkle when dry, requiring wet veneer application, which is more time-consuming and labor-intensive. Therefore, it is necessary to find a veneer process that can not only save costs, but also simplify the process and improve efficiency. Summary of the Invention

[0003] To simplify the process and reduce costs, the early inventors applied ordinary glue to the surface of the board, then directly glued the thin veneer onto the glued surface, and then directly hot-pressed it to complete the veneer application. Although this process simplified the process and saved energy, materials, and labor costs, other problems arose during processing: for example, applying the thin veneer directly to the hot press without cold pressing caused the glue-covered board surface to turn black when it entered the UV roller coating stage, affecting the appearance and requiring more UV paint; using thin veneer that was not properly sewn onto the glued surface resulted in the glued surface hardening before hot pressing due to prolonged use, making it impossible for the wood veneer to adhere.

[0004] In view of the shortcomings of the prior art and the above-mentioned shortcomings, the purpose of this invention is to provide a thin-veneer direct bonding process. This process adopts a thin-veneer direct bonding method, which simplifies the process and reduces costs by directly hot pressing. By optimizing process parameters and adhesive formula, the veneer products have good aesthetics, improved adhesion strength between the veneer and the board, and also have characteristics such as high temperature resistance, oxidation resistance, and good stability. They will not oxidize and turn black after hot pressing, effectively solving the shortcomings of the prior art.

[0005] To achieve the above objectives, the present invention provides a thin-skin direct-attachment processing technology, which specifically includes the following process flow:

[0006] S1. Bark cutting and selection: Select logs with no cracks on the surface, use a sander to sand the surface smooth, and then use an electric saw to cut them to obtain veneer. Then cut the veneer into equal widths and discard veneers that are translucent or of varying thickness in advance.

[0007] S2. Wood veneer pretreatment: Place the selected wood veneer in the steaming tank and steam it in water. Gradually increase the steaming temperature from room temperature to 80℃ and maintain it for 0.5-1 hour. Then cool down and repeat the heating process once. After cooling down, transfer the wood veneer to a low-temperature drying oven for drying and use.

[0008] S3. Applying glue to the board: Place the solid wood board to be veneered onto the gluing machine, and use the glue roller to apply glue to the side of the board to be veneered. The glue thickness is 0.1±0.02mm.

[0009] S4. Veneer: The pre-treated wood veneer is laid tightly on the side of the board to be veneered that is coated with glue. The distance between adjacent veneers is less than 0.1mm and they do not overlap. The edges extend 1-2cm beyond the board.

[0010] S5. Hot press: The boards with wood veneer applied in S4 are sent into the hot press for two hot presses;

[0011] S6. Unloading and trimming: Remove the board that has been hot-pressed in S5 from the hot press and use a utility knife to remove the veneer protruding from the edges of the board to obtain a veneered board.

[0012] This invention improves the efficiency of subsequent veneer application by cutting and selecting veneers, removing damaged or unevenly thick veneers; steaming the veneers enhances their toughness and effectively prevents cracking and shrinkage during the subsequent hot-pressing process; and directly hot-pressing the veneered boards simplifies the veneer process and significantly reduces various costs.

[0013] Furthermore, in the above technical solution, the thickness of the wood veneer is 0.2±0.02mm. The wood veneer of this invention has a thickness between 0.18-0.22mm, which is a thin veneer. The veneer application process is difficult, and direct hot pressing easily leads to shrinkage and wrinkling. Combining the process of this invention can effectively prevent this problem from occurring.

[0014] Furthermore, in the above technical solution S2, 5-10% of a traditional Chinese medicine extract is added to the boiling water. The traditional Chinese medicine extract is obtained by soaking 10-20 parts of mugwort, 10-20 parts of garlic leaves, 10-20 parts of tea leaves, 5-10 parts of dandelion, 5-10 parts of honeysuckle, and 4-8 parts of rose petals in 3-4 times the volume of hot water for 4-6 hours and then filtering.

[0015] In this technical solution, herbal extracts with bactericidal and antioxidant effects are added to the cooking water. This not only kills pests and diseases in the wood veneer during the cooking process, but also allows the effective components of the herbal extracts to penetrate the wood veneer through the cooking process, giving it certain bactericidal and antioxidant functions, thus improving its service life. It can also improve the antioxidant properties of the glue during subsequent processing to a certain extent.

[0016] Furthermore, in the above technical solution S2, the temperature of the low-temperature drying oven is 40-50℃, and the moisture content of the wood veneer after drying is 9-10%. In this technical solution, the use of a low-temperature drying process can effectively prevent the wood veneer from losing water rapidly and deforming.

[0017] Furthermore, in the aforementioned technical solution S3, the raw materials for the adhesive used for coating include: 40-50 parts modified polyurethane, 5-10 parts epoxy resin, 5-8 parts flour, 2-4 parts calcium silicate, 3-5 parts diammonium hydrogen phosphate, and 20-30 parts water. This technical solution optimizes the adhesive formulation, using silicone-modified polyurethane as the main raw material. This not only provides good adhesion but also exhibits properties such as aging resistance, oxidation resistance, and resistance to low and high temperatures. The addition of epoxy resin further enhances the adhesive's bonding strength, water resistance, and solvent resistance. Flour, with its high starch content, expands into a transparent paste when mixed with hot water, serving as an adhesive component with good adhesion, high transparency, and low cost. Calcium silicate, formed by calcining and melting calcium oxide and silicon dioxide at high temperatures, has good heat resistance. Adding it to the adhesive further improves its water resistance and thermal stability. It also acts as an anti-caking agent, extending the adhesive's curing time to some extent. Diammonium hydrogen phosphate, as a flame retardant, improves the flame retardant properties of the board.

[0018] Furthermore, in the above technical solution, the modified polyurethane is an organosilicon-modified polyurethane emulsion. The modification method is as follows: neopentyl glycol, dimethylolbutyric acid, and hydroxyl silicone oil are added to a stirrer, stirred, and heated to 55-60°C. Polyisocyanate is added, and stirring continues for 1-2 hours. Diethylene glycol is added and reacted for 1-2 hours. Sodium hydroxide is then added and stirring continues for 0.5-1 hour. Finally, water is added under high-speed stirring, and stirring continues for 0.5 hours to obtain the organosilicon-modified polyurethane emulsion. This technical solution uses hydroxyl silicone oil to modify the polyurethane, resulting in good adhesion and water resistance, while significantly improving stain resistance and yellowing resistance.

[0019] Furthermore, in the above technical solution, the raw material components of the organosilicon-modified polyurethane emulsion, by weight, include 30-45 parts of neopentyl glycol, 1-2 parts of dimethylolbutyric acid, 2-5 parts of hydroxyl silicone oil, 15-20 parts of polyisocyanate, 0.5-1 part of diethylene glycol, 0.5-1.5 parts of sodium hydroxide, and 60-80 parts of water.

[0020] Furthermore, in the above technical solution, the initial stirring speed is 300-500 r / min, and the stirring speed when water is added is 1500-2000 r / min.

[0021] Furthermore, in the above technical solution, the preparation method of the adhesive is as follows: flour and water are mixed, heated to 45-55℃, diammonium hydrogen phosphate is added and stirred to obtain a first premix; modified polyurethane is mixed with epoxy resin and calcium silicate to obtain a second premix; finally, the second premix is ​​added to the first premix and stirred to obtain the adhesive. In this technical solution, flour and water are first mixed to form a transparent paste, and then diammonium hydrogen phosphate is added, resulting in good dispersibility; the modified polyurethane is premixed with epoxy resin for blending, which can further improve the bonding strength, mechanical properties, and water and solvent resistance; calcium silicate is added to improve its dispersibility; finally, the two premixes are mixed, resulting in high mixing degree and good stability.

[0022] Furthermore, in the aforementioned technical solution S5, the two hot pressing processes are divided into primary and secondary hot pressing. After the veneer board is fed into the hot press, primary hot pressing is performed at a pressure of 5-8 MPa and a temperature of 60-80℃ for 5-10 minutes. After the primary hot pressing, the pressure is adjusted to 10-14 MPa and the temperature to 90-120℃ for 3-5 minutes. In this technical solution, the hot pressing is carried out in two procedures. First, the veneer, glue, and board are pressed together under relatively low temperature and low pressure conditions, and then pressed together under relatively high temperature and high pressure conditions. This effectively prevents the glue from curing too quickly due to excessively high temperature at the beginning, or the glue from being squeezed directly from the sides or veneer gaps due to excessive pressure, which would affect the veneer effect. The resulting veneer product has a smooth and uniform surface, without any yellowing or blackening of the glue.

[0023] The beneficial effects of this invention are:

[0024] This invention improves the thin-veneer veneer process by optimizing the veneer application process. It involves pre-selecting and pre-treating the wood veneer to improve veneer application efficiency and toughness. The veneered boards are directly fed into the hot press, and the hot pressing process parameters are adjusted. This not only simplifies the process and reduces costs, but also improves the success rate of veneer application and the aesthetics of the product.

[0025] This invention optimizes the adhesive formulation, using silicone-modified polyurethane as the main raw material. This results in adhesive with excellent adhesion, as well as resistance to aging, oxidation, and low and high temperatures. The addition of epoxy resin further enhances the adhesive's bonding strength, water resistance, and solvent resistance. The addition of flour, when mixed with hot water, expands into a transparent paste, providing not only good adhesion and high transparency but also reducing costs. The addition of calcium silicate improves the adhesive's water resistance and thermal stability, and it also acts as an anti-caking agent, extending the curing time to some extent. The addition of diammonium hydrogen phosphate improves the adhesive's flame retardant properties.

[0026] This invention improves the efficiency, effectiveness, and lifespan of veneer products by adding antibacterial and antioxidant herbal extracts to the pre-treated veneer boiling water and adding anti-caking and flame-retardant ingredients to the adhesive formula. Detailed Implementation

[0027] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the raw materials used in the following examples are all commercially available products and can be purchased from the market.

[0028] The present invention will be further described in detail below with reference to embodiments:

[0029] Example 1

[0030] The method for preparing the adhesive includes the following steps:

[0031] According to the formula, first mix flour and water, heat to 45°C, add diammonium hydrogen phosphate and stir at 500 r / min to obtain the first premix; then stir the modified polyurethane, epoxy resin and calcium silicate at 500 r / min to obtain the second premix; finally add the second premix to the first premix and continue stirring to obtain the glue.

[0032] The raw material ratio is as follows: 40 parts modified polyurethane, 10 parts epoxy resin, 5 parts flour, 2 parts calcium silicate, 3 parts diammonium hydrogen phosphate, and 20 parts water.

[0033] The modified polyurethane is an organosilicon-modified polyurethane emulsion. The modification method is as follows: 30 parts by weight of neopentyl glycol, 1 part of dimethylolbutyric acid, and 2 parts of hydroxyl silicone oil are added to a stirrer, stirred at 300 r / min and heated to 60°C, 15 parts of polyisocyanate are added, and stirring is continued for 1 h, 1 part of diethylene glycol is added and reacted for 1 h, then 0.5 parts of sodium hydroxide are added and stirring is continued for 0.5 h, and finally water is added at a stirring speed of 2000 r / min and stirring is continued for 0.5 h to obtain the organosilicon-modified polyurethane emulsion.

[0034] Example 2

[0035] The method for preparing the adhesive includes the following steps:

[0036] According to the formula, first mix flour and water, heat to 50°C, add diammonium hydrogen phosphate and stir at 500 r / min to obtain the first premix; then stir the modified polyurethane, epoxy resin and calcium silicate at 500 r / min to obtain the second premix; finally add the second premix to the first premix and continue stirring to obtain the glue.

[0037] The raw material ratio is as follows: 45 parts modified polyurethane, 8 parts epoxy resin, 6 parts flour, 3 parts calcium silicate, 4 parts diammonium hydrogen phosphate, and 25 parts water.

[0038] The modified polyurethane is an organosilicon-modified polyurethane emulsion. The modification method is as follows: 40 parts by weight of neopentyl glycol, 1.5 parts by weight of dimethylolbutyric acid, and 4 parts by weight of hydroxyl silicone oil are added to a stirrer, stirred at 400 r / min and heated to 60°C, 18 parts by weight of polyisocyanate are added, and stirring is continued for 1.5 h, 1.5 parts by weight of diethylene glycol are added and reacted for 1.5 h, then 0.8 parts by weight of sodium hydroxide are added and stirring is continued for 1 h, and finally water is added at a stirring speed of 1800 r / min and stirring is continued for 0.5 h to obtain the organosilicon-modified polyurethane emulsion.

[0039] Example 3

[0040] The method for preparing the adhesive includes the following steps:

[0041] According to the formula, first mix flour and water, heat to 55℃, add diammonium hydrogen phosphate and stir at 500 r / min to obtain the first premix; then stir the modified polyurethane, epoxy resin and calcium silicate at 500 r / min to obtain the second premix; finally add the second premix to the first premix and continue stirring to obtain the glue.

[0042] The raw material ratio is as follows: 50 parts modified polyurethane, 5 parts epoxy resin, 8 parts flour, 4 parts calcium silicate, 5 parts diammonium hydrogen phosphate, and 30 parts water.

[0043] The modified polyurethane is an organosilicon-modified polyurethane emulsion. The modification method is as follows: by weight, 45 parts of neopentyl glycol, 2 parts of dimethylolbutyric acid, and 5 parts of hydroxyl silicone oil are added to a stirrer, stirred at 500 r / min and heated to 55°C, 20 parts of polyisocyanate are added, and stirring is continued for 2 h, 2 parts of diethylene glycol are added and reacted for 2 h, then 1 part of sodium hydroxide is added and stirring is continued for 1 h, and finally water is added at a stirring speed of 1500 r / min and stirring is continued for 0.5 h to obtain the organosilicon-modified polyurethane emulsion.

[0044] Example 4

[0045] A thin-skin direct-attach processing technology specifically includes the following process flow:

[0046] S1. Bark cutting and selection: Select logs with no cracks on the surface, use a sander to sand the surface smooth, and then use an electric saw to cut them to obtain thin veneers with a thickness of 0.2±0.02mm. Then cut the veneers into equal widths and discard those that are translucent or of varying thickness.

[0047] S2. Wood Veneer Pretreatment: The selected wood veneer from S1 is placed in a steaming tank and steamed in a water bath. The steaming temperature is gradually increased from room temperature to 80℃ and maintained for 1 hour. Then, it is cooled to room temperature, and the temperature is repeatedly increased to 80℃ and maintained for 1 hour. After cooling, the wood veneer is transferred to a low-temperature drying oven at 50℃ and dried until the moisture content is 9-10% for later use. 5% of a traditional Chinese medicine extract is added to the steaming water. The traditional Chinese medicine extract is obtained by soaking 15 parts of mugwort, 15 parts of garlic leaves, 10 parts of tea leaves, 8 parts of dandelion, 5 parts of honeysuckle, and 8 parts of rose in 3 times the volume of hot water for 4 hours and then filtering.

[0048] S3. Applying glue to the board: Place the solid wood board to be veneered onto the gluing machine, and apply glue to the side of the board to be veneered using a glue roller. Use the glue prepared in Example 1, and the glue thickness is 0.1±0.02mm.

[0049] S4. Veneer: The pre-treated wood veneer is laid tightly on the side of the board to be veneered that is coated with glue. The distance between adjacent veneers is less than 0.1mm and they do not overlap. The edges extend 1-2cm beyond the board.

[0050] S5. Hot Pressing: The veneered boards from S4 are fed into the hot press for two hot presses. The two hot presses consist of a first hot press and a second hot press. After the veneered boards are fed into the hot press, the first hot press is performed at a pressure of 5 MPa and a temperature of 80°C for 10 minutes. After the first hot press, the pressure is adjusted to 10 MPa and the temperature to 120°C for a second hot press for 5 minutes.

[0051] S6. Unloading and trimming: Remove the board that has been hot-pressed in S5 from the hot press and use a utility knife to remove the veneer protruding from the edges of the board to obtain a veneered board.

[0052] Example 5

[0053] A thin-skin direct-attach processing technology specifically includes the following process flow:

[0054] S1. Bark cutting and selection: Select logs with no cracks on the surface, use a sander to sand the surface smooth, and then use an electric saw to cut them to obtain thin veneers with a thickness of 0.2±0.02mm. Then cut the veneers into equal widths and discard those that are translucent or of varying thickness.

[0055] S2. Wood Veneer Pretreatment: The selected wood veneer from S1 is placed in a steaming tank and steamed in a water bath. The steaming temperature is gradually increased from room temperature to 80℃ and maintained for 0.5 hours. Then, it is cooled to room temperature, and the temperature is repeatedly increased to 80℃ and maintained for 0.5 hours. After cooling, the wood veneer is transferred to a low-temperature drying oven at 40℃ and dried until the moisture content is 9-10% for later use. 10% of a traditional Chinese medicine extract is added to the steaming water. The traditional Chinese medicine extract is obtained by soaking 20 parts of mugwort, 20 parts of garlic leaves, 15 parts of tea leaves, 8 parts of dandelion, 5 parts of honeysuckle, and 6 parts of rose in 4 times the volume of hot water for 5 hours and then filtering.

[0056] S3. Applying glue to the board: Place the solid wood board to be veneered onto the gluing machine, and apply glue to the side of the board to be veneered using a glue roller. Use the glue prepared in Example 2, and the glue thickness is 0.1±0.02mm.

[0057] S4. Veneer: The pre-treated wood veneer is laid tightly on the side of the board to be veneered that is coated with glue. The distance between adjacent veneers is less than 0.1mm and they do not overlap. The edges extend 1-2cm beyond the board.

[0058] S5. Hot Pressing: The veneered boards from S4 are fed into the hot press for two hot presses. The two hot presses consist of a first hot press and a second hot press. After the veneered boards are fed into the hot press, the first hot press is performed at a pressure of 6 MPa and a temperature of 70°C for 8 minutes. After the first hot press, the pressure is adjusted to 12 MPa and the temperature to 100°C for a second hot press for 4 minutes.

[0059] S6. Unloading and trimming: Remove the board that has been hot-pressed in S5 from the hot press and use a utility knife to remove the veneer protruding from the edges of the board to obtain a veneered board.

[0060] Example 6

[0061] A thin-skin direct-attach processing technology specifically includes the following process flow:

[0062] S1. Bark cutting and selection: Select logs with no cracks on the surface, use a sander to sand the surface smooth, and then use an electric saw to cut them to obtain thin veneers with a thickness of 0.2±0.02mm. Then cut the veneers into equal widths and discard those that are translucent or of varying thickness.

[0063] S2. Wood Veneer Pretreatment: The selected wood veneer from S1 is placed in a steaming tank and steamed in a water bath. The steaming temperature is gradually increased from room temperature to 80℃ and maintained for 1 hour. Then, it is cooled to room temperature, and the temperature is repeatedly increased to 80℃ and maintained for 1 hour. After cooling, the wood veneer is transferred to a low-temperature drying oven at 45℃ and dried until the moisture content is 9-10% for later use. 7% of a traditional Chinese medicine extract is added to the steaming water. The traditional Chinese medicine extract is obtained by soaking 10 parts of mugwort, 10 parts of garlic leaves, 20 parts of tea leaves, 5 parts of dandelion, 10 parts of honeysuckle, and 4 parts of rose petals in 4 times the volume of hot water for 6 hours and then filtering.

[0064] S3. Applying glue to the board: Place the solid wood board to be veneered onto the gluing machine, and apply glue to the side of the board to be veneered using a glue roller. Use the glue prepared in Example 3, and the glue thickness is 0.1±0.02mm.

[0065] S4. Veneer: The pre-treated wood veneer is laid tightly on the side of the board to be veneered that is coated with glue. The distance between adjacent veneers is less than 0.1mm and they do not overlap. The edges extend 1-2cm beyond the board.

[0066] S5. Hot Pressing: The veneered boards from S4 are fed into the hot press for two hot presses. The two hot presses consist of a first hot press and a second hot press. After the veneered boards are fed into the hot press, the first hot press is performed at a pressure of 8MPa and a temperature of 60℃ for 5 minutes. After the first hot press, the pressure is adjusted to 14MPa and the temperature to 90℃ for a second hot press for 3 minutes.

[0067] S6. Unloading and trimming: Remove the board that has been hot-pressed in S5 from the hot press and use a utility knife to remove the veneer protruding from the edges of the board to obtain a veneered board.

[0068] Comparative Example 1

[0069] The preparation method of the adhesive differs from that of Example 1 in that the polyurethane used is not modified; otherwise, it is the same as that of Example 1.

[0070] Comparative Example 2

[0071] The preparation method of the adhesive differs from that of Example 1 in that epoxy resin is not added; otherwise, it is the same as that of Example 1.

[0072] Comparative Example 3

[0073] The preparation method of the adhesive differs from that of Example 1 in that calcium silicate is not added; otherwise, it is the same as that of Example 1.

[0074] Comparative Example 4

[0075] A thin-veneer direct-attachment processing method differs from Example 4 in that no pretreatment of the veneer is performed.

[0076] Comparative Example 5

[0077] A thin-skin direct-attachment processing method differs from Example 4 in that no Chinese herbal medicines are added to the boiling water during the pretreatment of the wood veneer.

[0078] Comparative Example 6

[0079] A thin-skin direct-attachment processing method differs from Example 4 in that only one hot pressing is performed, and the parameters are set according to the two-stage hot pressing in Example 4.

[0080] Comparative Example 7

[0081] A thin-skin direct-attachment processing method differs from Example 4 in that the adhesive used is prepared by the method of Comparative Example 1.

[0082] Comparative Example 8

[0083] A thin-skin direct-attachment processing method differs from Example 4 in that the adhesive used is prepared by the method of Comparative Example 2.

[0084] Comparative Example 9

[0085] A thin-skin direct-attachment processing method differs from Example 4 in that the adhesive used is prepared by the method of Comparative Example 3.

[0086] Experimental Example 1

[0087] The properties of the adhesives prepared in Examples 1-3 and Comparative Examples 1-3 were tested, and the results are shown in Table 1. The adhesive properties were determined according to the relevant methods in JB / T 10900-2016, GB / T 2794-2013, and GB / T7124-2008.

[0088] Table 1

[0089]

[0090]

[0091] As can be seen from the results in Table 1, the adhesive obtained by the adhesive formulation of the present invention is in paste form, has a moderate curing time, good viscosity, and good water resistance and aging resistance.

[0092] Compared with Comparative Example 1 and Comparative Examples 1-3, Comparative Example 1 did not modify the polyurethane, and its adhesion, water resistance and other properties were poor; Comparative Example 2 did not add epoxy resin, and its adhesion was also poor; Comparative Example 3 did not add calcium silicate, and although it had little effect on viscosity, it had a certain impact on other properties, especially the curing speed was faster, which was not conducive to the subsequent skin-applying process.

[0093] Experimental Example 2

[0094] The appearance, adhesive strength, and thermal cycling tests of the veneer panels of Examples 4-5 and Comparative Examples 4-9 were tested, and the results are shown in Table 2. The surface adhesive strength and thermal cycling tests were conducted in accordance with the relevant standards in GB / T 15104-006.

[0095] Table 2 Appearance and Product Effect

[0096]

[0097]

[0098] As can be seen from the results in Table 2, the veneer panels obtained by the thin-skin direct bonding process of the present invention have a good appearance, are flat, without cracks or glue discoloration, have high bonding strength, good adhesion, good resistance to low and high temperatures, good weather resistance, and long service life.

[0099] Compared with Comparative Example 4 and Comparative Examples 4-5, if no pretreatment is performed on the wood veneer or no Chinese herbal medicine is used during the pretreatment process, although the bonding strength is hardly affected, the appearance and effect are affected to a certain extent. This is likely because the wood veneer is not steamed or boiled in advance, resulting in poor toughness and making it prone to cracking, glue leakage, and warping during subsequent processing. In addition, the pests in the logs are not killed, which can easily cause damage.

[0100] Compared with Example 4 and Comparative Example 6, the hot pressing process only involves one high-pressure and high-temperature treatment, which can easily affect the performance of the glue and cause the wood veneer to crack and warp under sudden high temperature and high pressure, thus affecting the veneer effect and bonding strength.

[0101] Compared with Comparative Examples 4 and 7-9, in Comparative Example 7, the adhesive's aging resistance and resistance to low and high temperatures were relatively poor because the polyurethane was not modified; in Comparative Example 8, no epoxy resin was added, which affected the bonding strength; in Comparative Example 9, the overall impact was not significant, but the thermal stability was relatively poor.

[0102] Finally, it should be emphasized that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A thin-skin direct-attach processing technology, characterized in that, The thin-skin direct-attach process is adopted, which specifically includes the following process flow: S1. Bark cutting and selection: Select logs with no cracks on the surface, use a sander to smooth the surface, and then use an electric saw to cut them to obtain veneer. Then cut the veneer into equal widths, and discard veneers that are translucent or of varying thickness in advance; the thickness of the veneer is 0.2±0.02mm. S2. Wood Veneer Pretreatment: Place the selected wood veneer from S1 into a steaming tank and steam it over water. Gradually increase the steaming temperature from room temperature to 80℃ and maintain it for 0.5-1 hour. Then lower the temperature and repeat the heating process once. After cooling, transfer the wood veneer to a low-temperature drying oven for drying and use. Add 5-10% of a traditional Chinese medicine extract to the steaming water. The traditional Chinese medicine extract is obtained by soaking 10-20 parts of mugwort, 10-20 parts of garlic leaves, 10-20 parts of tea leaves, 5-10 parts of dandelion, 5-10 parts of honeysuckle, and 4-8 parts of rose in 3-4 times the volume of hot water for 4-6 hours and then filtering. S3. Gluing the Board: Place the solid wood board to be veneered onto the gluing machine, and use the gluing roller to apply glue to the side of the board to be veneered, with a glue thickness of 0.1±0.02mm; the raw materials of the glue used for gluing include: 40-50 parts modified polyurethane, 5-10 parts epoxy resin, 5-8 parts flour, 2-4 parts calcium silicate, 3-5 parts diammonium hydrogen phosphate, and 20-30 parts water; the modified polyurethane is an organosilicon modified polyurethane emulsion; the modification method of the organosilicon modified polyurethane emulsion is as follows: add neopentyl glycol, dimethylolbutyric acid, and hydroxyl silicone oil to a mixer, stir, and add... Heat to 55-60℃, add polyisocyanate, continue stirring for 1-2 hours, add diethylene glycol and react for 1-2 hours, then add sodium hydroxide and continue stirring for 0.5-1 hour. Finally, add water under high-speed stirring and continue stirring for 0.5 hours to obtain a silicone-modified polyurethane emulsion. The raw material components of the silicone-modified polyurethane emulsion, by weight, include 30-45 parts neopentyl glycol, 1-2 parts dimethylolbutyric acid, 2-5 parts hydroxyl silicone oil, 15-20 parts polyisocyanate, 0.5-1 part diethylene glycol, 0.5-1.5 parts sodium hydroxide, and 60-80 parts water. S4. Veneer: The pre-treated wood veneer is laid tightly on the side of the board to be veneered that is coated with glue. The distance between adjacent veneers is less than 0.1mm and they do not overlap. The edges extend 1-2cm beyond the board. S5. Hot Pressing: The veneered boards from S4 are fed into the hot press for two hot presses. The two hot presses consist of a first hot press and a second hot press. After the veneered boards are fed into the hot press, the first hot press is performed at a pressure of 5-8 MPa and a temperature of 60-80℃ for 5-10 minutes. After the first hot press, the pressure is adjusted to 10-14 MPa and the temperature to 90-120℃ for a second hot press for 3-5 minutes. S6. Unloading and trimming: Remove the board that has been hot-pressed in S5 from the hot press and use a utility knife to remove the veneer protruding from the edges of the board to obtain a veneered board.

2. The thin-skin direct-attach processing technology according to claim 1, characterized in that, In S2, the temperature of the low-temperature drying oven is 40-50℃, and the moisture content of the wood veneer after drying is 9-10%.

3. The thin-skin direct-attach processing technology according to claim 1, characterized in that, The method for preparing the adhesive is as follows: mix flour and water, heat to 45-55℃, add diammonium hydrogen phosphate and stir to obtain a first premix; mix modified polyurethane with epoxy resin and calcium silicate to obtain a second premix; finally add the second premix to the first premix and continue stirring to obtain the adhesive.

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