Preparation process of carbon dot modified flame-retardant cedarwood plywood and plywood

Abstract

According to the preparation technology of the carbon dot modified flame-retardant cunninghamia lanceolata plywood and the plywood, a cunninghamia lanceolata veneer is combined with flame-retardant carbon dot impregnation liquid, flame-retardant carbon dots are made to evenly permeate into wood of the cunninghamia lanceolata veneer through vacuum impregnation, and the flame-retardant performance of the cunninghamia lanceolata veneer is effectively improved; meanwhile, the natural mechanical property of the cedarwood veneer is kept. In the process, the impregnation pressure and the hot pressing parameters are accurately controlled, so that tight combination of the flame-retardant carbon dots and the cedarwood veneers is ensured, and the manufactured plywood has excellent stability and mechanical strength. By optimizing the drying temperature and the water content of the impregnated veneers, the problem of wood cracking caused by traditional flame retardant treatment is effectively avoided. The flame-retardant adhesive is suitable for the field of building decoration with high requirements on fireproof performance and environmental protection, and has a remarkable market application value.

Description

Technical Field

[0001] The present invention relates to the technical field of wood-based panel processing, and particularly to a preparation process and plywood of carbon dot-modified flame-retardant Chinese fir plywood. Background Art

[0002] As a common wood, Chinese fir has the advantages of fast growth and rich resources. However, the flammability of Chinese fir poses certain safety hazards in its applications. Existing flame retardants are mostly coated on the surface of Chinese fir and then glued to form plywood. Although it can improve the flame retardant performance of Chinese fir to a certain extent, it often has a negative impact on its mechanical properties, and some flame retardants have environmental problems. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a preparation process and plywood of carbon dot-modified flame-retardant Chinese fir plywood.

[0004] In order to achieve the above technical purpose, the technical solution adopted by the present invention is as follows:

[0005] In the first aspect, the present invention provides a preparation process of carbon dot-modified flame-retardant Chinese fir plywood, including:

[0006] Select Chinese fir veneers and dry them to a moisture content of 8%-10%, and the thickness of the Chinese fir veneers is 2.0±0.2 mm;

[0007] Select raw wood materials, and perform pretreatment on the raw wood materials, and the pretreatment includes impurity removal and drying;

[0008] Grind the pretreated raw wood materials to form wood powder within a preset mesh range, and the preset mesh range is 40-60 meshes;

[0009] Prepare a mixed solution by mixing the wood powder and phosphoric acid according to a preset mass ratio, and the preset mass ratio is 1:1;

[0010] Stir and dilute the mixed solution and deionized water according to a preset volume ratio to obtain a diluted solution, and the preset volume ratio is 1:30;

[0011] Heat the diluted solution, the heating temperature is 200°C, and the heating duration is 6 hours;

[0012] Cool and filter the heated diluted solution to obtain a reaction liquid;

[0013] Centrifuge the reaction liquid to obtain a flame-retardant carbon dot impregnation liquid;

[0014] Place the dried Chinese fir veneers in a vacuum impregnation device, evacuate to -0.08 Mpa, and maintain for 30 min;

[0015] Inject the flame-retardant carbon dot impregnation solution and control the pressure of the vacuum impregnation equipment at 0.5 Mpa for 3 hours of impregnation;

[0016] Take out the impregnated Chinese fir veneer and drain it to obtain the impregnated veneer;

[0017] Place the impregnated veneer in an oven and dry it to a moisture content of 8%-10% at a drying temperature of 60°C;

[0018] Roll-coat the adhesive evenly on the surface of the dried impregnated veneer, and the single-sided coating amount of the adhesive on the impregnated veneer is 180-200 g / m 2 , to obtain a billet;

[0019] Stack the billets according to a preset quantity to form a board blank;

[0020] Place the board blank in a hot press for hot pressing to form a board. The hot pressing temperature of the hot press is 110-120°C, the hot pressing pressure is 1.0-2.0 MPa, and the hot pressing time is 0.8-1.0 min per board thickness, with the board thickness unit being mm, and the board thickness being configured as the thickness of the board blank;

[0021] Naturally cool the board to room temperature, and obtain the flame-retardant Chinese fir plywood modified with carbon dots after trimming.

[0022] In some embodiments, the raw wood is the processing residues or thinned wood of plantation coniferous wood.

[0023] In some embodiments, the adhesive is a urea-formaldehyde resin adhesive, with a solid content of 35%-45% and a viscosity of 200-300 mPa·s.

[0024] In some embodiments, the pretreatment of the raw wood includes:

[0025] Perform impurity removal treatment on the raw wood, and the impurity removal treatment includes removing the bark and rinsing with clean water;

[0026] Dry the rinsed raw wood to absolute dryness.

[0027] In some embodiments, the preset mesh number is 50 meshes.

[0028] In some embodiments, centrifuging the reaction liquid to obtain the flame-retardant carbon dot impregnation solution includes:

[0029] Place the reaction liquid in a centrifuge and perform centrifugation at 10000 r / min.

[0030] In some embodiments, stacking the billets according to a preset quantity includes:

[0031] Set the preset quantity to an odd value;

[0032] The roller coating directions of the adhesives of two adjacent billets are perpendicular to each other.

[0033] In some embodiments, the flame-retardant Chinese fir plywood modified with carbon dots after edge trimming includes:

[0034] The board is cut according to a preset size to obtain the flame-retardant Chinese fir plywood modified with carbon dots.

[0035] In a second aspect, the present invention provides a flame-retardant Chinese fir plywood modified with carbon dots, which is obtained by the preparation process described in the first aspect.

[0036] In some embodiments, the particle size of the flame-retardant carbon dots of the flame-retardant Chinese fir plywood is < 10 nm.

[0037] Adopting the above technical solution, compared with the prior art, the present invention has the following beneficial effects:

[0038] By combining Chinese fir veneers with a flame-retardant carbon dot impregnating solution and using vacuum impregnation to uniformly penetrate the flame-retardant carbon dots into the interior of the wood of the Chinese fir veneers, the flame-retardant performance of the Chinese fir veneers themselves is effectively improved, while maintaining the natural mechanical properties of the Chinese fir veneers. The flame-retardant carbon dot impregnating solution generated by the reaction of phosphoric acid and wood powder is not only environmentally friendly and non-toxic, but also can form a stable bond with wood fibers during the hot pressing process, endowing the plywood with a lasting flame-retardant effect. The precisely controlled impregnation pressure and hot pressing parameters in the process ensure the tight combination of the flame-retardant carbon dots and the Chinese fir veneers, making the resulting plywood have excellent stability and mechanical strength. By optimizing the drying temperature and moisture content of the impregnated veneers, the problem of wood cracking caused by traditional flame-retardant treatments is effectively avoided. The finally prepared flame-retardant Chinese fir plywood modified with carbon dots realizes the synergistic improvement of flame-retardant performance and bonding strength on the premise of maintaining an adhesive coating amount of 180 - 200 g / m 2 and is applicable to the building decoration field with high requirements for fire protection performance and environmental protection, having significant market application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention, and for those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0040] Figure 1 It is a schematic diagram of the billet stacking of the flame-retardant Chinese fir plywood. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0041] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be specifically noted that the following embodiments are only used to illustrate the present invention, but do not limit the scope of the present invention. Similarly, the following embodiments are only partial embodiments of the present invention rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0042] With the development of society, people have higher and higher requirements for the performance of building and furniture materials. As a common wood, Chinese fir has the advantages of fast growth and rich resources. However, the flammability of Chinese fir poses certain safety hazards in its application. Although traditional flame retardant treatment methods can improve the flame retardant performance of Chinese fir to a certain extent, they often have a negative impact on its mechanical properties, and some flame retardants have environmental problems.

[0043] As a new type of nanomaterial, carbon dots have unique optical, electrical and chemical properties and show great potential in the field of material modification. Applying carbon dots to the flame retardant modification of Chinese fir laminated veneer lumber is expected to improve the comprehensive properties of the material while enhancing its flame retardant performance, such as enhancing mechanical properties and improving weather resistance. However, there are still few relevant studies and applications at present. How to optimize the preparation process and give full play to the role of carbon dots is an urgent problem to be solved.

[0044] To solve the above problems, this embodiment aims to provide a preparation process for carbon dot-modified flame retardant Chinese fir plywood. By introducing carbon dots with flame retardant properties into Chinese fir veneers, the flame retardant performance, mechanical properties and weather resistance of Chinese fir plywood are improved to meet the requirements of material performance in the fields of construction, furniture, etc.

[0045] In a first aspect, this embodiment provides a preparation process for carbon dot-modified flame retardant Chinese fir plywood, including:

[0046] Select Chinese fir veneers and dry them to a moisture content of 8%-10%. The thickness of the Chinese fir veneers is 2.0±0.2 mm;

[0047] Select raw wood materials and perform pretreatment on the raw wood materials. The pretreatment includes impurity removal and drying;

[0048] Grind the pretreated raw wood materials to form wood powder within a preset mesh range. The preset mesh range is 40-60 meshes;

[0049] Prepare a mixed solution by mixing the wood powder and phosphoric acid according to a preset mass ratio. The preset mass ratio is 1:1;

[0050] Stir and dilute the mixed solution and deionized water according to a preset volume ratio to obtain a diluted solution. The preset volume ratio is 1:30;

[0051] Heat the diluted solution at a heating temperature of 200 °C for 6 hours;

[0052] Cool and filter the heated diluted solution to obtain a reaction liquid;

[0053] Centrifuge the reaction liquid to obtain a flame-retardant carbon dot impregnating solution;

[0054] Place the dried Chinese fir veneer in a vacuum impregnation device, evacuate to -0.08 Mpa, and maintain for 30 min;

[0055] Inject the flame-retardant carbon dot impregnating solution, and control the pressure of the vacuum impregnation device at 0.5 Mpa for 3 h of impregnation;

[0056] Take out the impregnated Chinese fir veneer and drain it to obtain an impregnated veneer;

[0057] Place the impregnated veneer in an oven and dry it to a moisture content of 8% - 10%, with a drying temperature of 60 °C;

[0058] Uniformly roll-coat an adhesive on the surface of the dried impregnated veneer. The single-sided coating amount of the adhesive on the impregnated veneer is 180 - 200 g / m 2 to obtain a billet;

[0059] Stack the billets according to a preset quantity to form a board blank;

[0060] Place the board blank in a hot press for hot pressing to form a board. The hot pressing temperature of the hot press is 110 - 120 °C, the hot pressing pressure is 1.0 - 2.0 MPa, and the hot pressing time is 0.8 - 1.0 min / board thickness. The board thickness unit is mm, and the board thickness is configured as the thickness of the board blank;

[0061] Naturally cool the board to room temperature, and obtain a carbon dot-modified flame-retardant Chinese fir plywood after trimming.

[0062] Specifically, in the raw material preparation stage, select Chinese fir veneers with a thickness of 2.0 ± 0.2 mm, and require no obvious defects. Dry it to a moisture content of 8% - 10%.

[0063] Select the processing residues or thinned wood of plantation coniferous tree species as the carbon source and phosphoric acid as the phosphorus source.

[0064] The adhesive can be a urea-formaldehyde resin adhesive, with a solid content of 35% - 45% and a viscosity of 200 - 300 mPa·s.

[0065] In the preparation of the flame-retardant carbon dot impregnation solution, the processing residues or thinned wood of plantation coniferous trees are used. After removing impurities such as bark, they are washed and dried to absolute dryness, and then ground into 50-mesh wood powder. The wood powder and phosphoric acid are made into a mixed solution according to a mass ratio of 1:1. Then, the mixed solution and deionized water are placed in a beaker according to a volume ratio of 1:30 and stirred for 20 minutes. Then, the solution is transferred to a hydrothermal reaction kettle and placed in a muffle furnace or oven. The heating temperature is 200 °C and the heating time is 6 hours. After the reaction ends and the temperature drops after cooling, the reaction solution is collected, filtered, and centrifuged with a centrifuge at 10,000 r / min to obtain the flame-retardant carbon dot impregnation solution.

[0066] After the flame-retardant carbon dot impregnation solution is prepared, the Chinese fir veneer is impregnated with the flame-retardant carbon dot impregnation solution. Specifically, the dried Chinese fir veneer is placed in a vacuum impregnation device, and the vacuum is pumped to -0.08 MPa and maintained for 30 min. The flame-retardant carbon dot impregnation solution is slowly injected and impregnated under a pressure of 0.5 MPa for 3 h to allow the impregnation solution to fully penetrate into the interior of the Chinese fir veneer. After impregnation is completed, the Chinese fir veneer is taken out and the excess impregnation solution on the surface is drained.

[0067] The impregnated Chinese fir veneer is placed in an oven and dried at a temperature of 60 °C until the moisture content is 8%-10%. During the drying process, attention should be paid to ventilation to avoid deformation or cracking of the Chinese fir veneer due to too fast drying.

[0068] After that, the blanks are made, and multiple blanks are stacked and hot-pressed to form a board. Specifically: An adhesive is evenly roller-coated on the surface of the dried Chinese fir veneer, and the single-sided coating amount is 180-200 g / m 2 . The adjacent layers are staggered in blanking. The number of Chinese fir veneer layers is an odd number, and the actual number of layers can be determined according to the target thickness. Among them, the adjacent-layer staggered blanking can be understood as follows: Taking the roller-coating direction as the main direction, the roller-coating directions of two adjacent Chinese fir veneer layers are perpendicular or cross each other, as Figure 1 shown. The assembled board blank is placed in a hot press, and the hot-pressing parameters are set. The hot-pressing temperature is 110-120 °C, the hot-pressing pressure is 1.0-1.2 MPa, and the hot-pressing time is 0.8-1.0 min / mm (board thickness).

[0069] After hot pressing is completed, the formed board is taken out and naturally cooled to room temperature. The board is trimmed to remove the uneven parts at the edges to obtain a carbon dot-modified flame-retardant Chinese fir plywood with the required dimensions.

[0070] The flame-retardant Chinese fir plywood prepared by the above preparation process has the flame-retardant performance shown in Table 1:

[0071] Table 1 Flame-retardant performance test indicators

[0072] Performance indicators Flame-retardant Chinese fir plywood (3 layers) Limiting oxygen index 40.36% (belonging to the non-combustible grade) Self-extinguishing time 20s Heat release rate 50.215 KW / m2 Ignition time 20s Total heat release 30.52 MJ / m2 Effective heat of combustion 19.87 MJ / kg

[0073] According to the requirements of GB / T 9846-2004 "Plywood", the physical and mechanical property indexes of flame-retardant Chinese fir plywood are shown in Table 2:

[0074] Table 2 Performance indexes required in national standards

[0075] Performance indicators Standard requirements Product test results (3 layers) Moisture content 6～14％ 8％ Bonding strength ≥0.80 MPa 1.2 MPa Formaldehyde emission ≤0.5 mg / L 0.2 mg / L

[0076] In this embodiment, by combining Chinese fir veneers with a flame-retardant carbon dot impregnating solution and using vacuum impregnation, the flame-retardant carbon dots are evenly penetrated into the interior of the wood of the Chinese fir veneers, effectively improving the flame-retardant performance of the Chinese fir veneers themselves while maintaining the natural mechanical properties of the Chinese fir veneers. The flame-retardant carbon dot impregnating solution generated by the reaction of phosphoric acid and wood powder is not only environmentally friendly and non-toxic, but also can form a stable bond with wood fibers during the hot pressing process, endowing the plywood with a lasting flame-retardant effect. The precisely controlled impregnation pressure and hot pressing parameters in the process ensure the tight combination of the flame-retardant carbon dots and the Chinese fir veneers, making the resulting plywood have both excellent stability and mechanical strength. By optimizing the drying temperature and moisture content of the impregnated veneers, the problem of wood cracking caused by traditional flame-retardant treatments is effectively avoided. The finally prepared carbon dot-modified flame-retardant Chinese fir plywood realizes the synergistic improvement of flame-retardant performance and bonding strength on the premise of maintaining an adhesive coating amount of 180 - 200 g / m 2 and is applicable to the building decoration field with high requirements for fire protection performance and environmental protection, having significant market application value.

[0077] In some embodiments, the raw wood is the processing residues or thinned wood of plantation coniferous wood. This can better utilize various materials and make the production process of the flame-retardant carbon dots more environmentally friendly.

[0078] In some embodiments, the adhesive is an urea-formaldehyde resin adhesive with a solid content of 35% - 45% and a viscosity of 200 - 300 mPa·s.

[0079] In some embodiments, the pretreatment of the raw wood includes:

[0080] Removing impurities from the raw wood, and the impurity removal treatment includes removing the bark and rinsing with clean water;

[0081] Drying the rinsed raw wood to absolute dryness.

[0082] In some embodiments, the preset mesh number is 50 meshes.

[0083] In some embodiments, centrifuging the reaction liquid to obtain the flame-retardant carbon dot impregnating solution includes:

[0084] Placing the reaction liquid in a centrifuge for centrifuging at 10000 r / min.

[0085] The flame-retardant carbon dots prepared by this process have a particle size < 10 nm, which can better penetrate into the Chinese fir veneer to improve the flame-retardant performance of the Chinese fir veneer.

[0086] In some embodiments, stacking the assembled blanks according to a preset quantity includes:

[0087] Setting the preset quantity to an odd value;

[0088] The roller coating directions of the adhesives of two adjacent assembled blanks are perpendicular to each other.

[0089] In this embodiment, the preset quantity is an odd value. Preferably, the thickness of the two outermost Chinese fir veneers can be slightly increased according to actual needs to ensure the mechanical structure performance of the plywood.

[0090] In some embodiments, the flame-retardant Chinese fir plywood modified with carbon dots after edge trimming includes:

[0091] Cutting the board according to a preset size to obtain the flame-retardant Chinese fir plywood modified with carbon dots.

[0092] In this embodiment, the preset size can be understood as the size required during actual use, which is specifically generated according to actual needs.

[0093] In a second aspect, this embodiment provides a flame-retardant Chinese fir plywood modified with carbon dots, which is obtained by the preparation process described in the first aspect.

[0094] In some embodiments, the particle size of the flame-retardant carbon dots of the flame-retardant Chinese fir plywood is < 10 nm.

[0095] Through the above technical solution, by combining the Chinese fir veneer with the flame-retardant carbon dot impregnation solution and using vacuum impregnation to uniformly penetrate the flame-retardant carbon dots into the wood interior of the Chinese fir veneer, the flame-retardant performance of the Chinese fir veneer itself is effectively improved, while maintaining the natural mechanical properties of the Chinese fir veneer. The flame-retardant carbon dot impregnation solution generated by the reaction of phosphoric acid and wood powder is not only environmentally friendly and non-toxic, but also can form a stable bond with wood fibers during the hot pressing process, endowing the plywood with a lasting flame-retardant effect. The precisely controlled impregnation pressure and hot pressing parameters in the process ensure the tight combination of the flame-retardant carbon dots and the Chinese fir veneer, making the prepared plywood have both excellent stability and mechanical strength. By optimizing the drying temperature and moisture content of the impregnated veneer, the problem of wood cracking caused by traditional flame-retardant treatment is effectively avoided. The finally prepared carbon dot-modified flame-retardant Chinese fir plywood realizes the synergistic improvement of the flame-retardant performance and the bonding strength while maintaining the adhesive coating amount of 180 - 200 g / m 2 It is applicable to the building decoration field with high requirements for fire protection performance and environmental protection, and has significant market application value.

[0096] The above are only some embodiments of the present invention, and thus do not limit the protection scope of the present invention. Any equivalent device or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall similarly be included in the patent protection scope of the present invention.

Claims

1. A process for preparing carbon point modified flame retardant fir plywood, characterized in that: include: Select a fir veneer and dry it to a moisture content of 8%-10%, wherein the thickness of the fir veneer is 2.0±0.2mm; Selecting raw material wood and pre-treating the raw material wood, wherein the pre-treatment includes removing impurities and drying; Grinding the pretreated raw wood material to form wood powder in a preset mesh range, wherein the preset mesh range is 40-60 mesh; The wood powder and phosphoric acid are mixed in a predetermined mass ratio to prepare a mixed solution, wherein the predetermined mass ratio is 1:1; The mixed solution and deionized water are stirred and diluted according to a preset volume ratio to obtain a diluted solution, wherein the preset volume ratio is 1:30; The diluted solution was heated at 200° C. for 6 hours; The heated diluted solution is cooled and filtered to obtain a reaction liquid; Centrifuging the reaction liquid to obtain a flame retardant carbon dot impregnation liquid; Place the dried fir veneer in a vacuum impregnation device and evacuate to -0.08Mpa for 30 minutes; Inject the flame retardant carbon dot impregnation liquid, control the pressure of the vacuum impregnation equipment at 0.5Mpa, and impregnate for 3 hours; The impregnated fir veneer is taken out and drained to obtain an impregnated veneer; Place the impregnated veneer in an oven and dry it to a moisture content of 8%-10% at a drying temperature of 60°C; Roll the adhesive evenly on the surface of the dried impregnated veneer. The adhesive coating amount on one side of the impregnated veneer is 180-200g / m 2 , and obtain the assembly; Stacking the blanks according to a preset number to form slabs; The slab is placed in a hot press for hot pressing to form a plate. The hot pressing temperature of the hot press is 110-120°C, the hot pressing pressure is 1.0-2.0MPa, the hot pressing time is 0.8-1.0min / plate thickness, the plate thickness unit is mm, and the plate thickness is configured as the thickness of the slab; The board is naturally cooled to room temperature and the edges are cut to obtain the carbon point modified flame retardant fir plywood.

2. The process for preparing the carbon point modified flame retardant fir plywood according to claim 1, characterized in that: The raw material wood materials are processing residues or thinning wood materials of artificial forest coniferous woods.

3. The preparation process of the carbon point modified flame retardant fir plywood according to claim 1, characterized in that: The adhesive is a urea-formaldehyde resin adhesive with a solid content of 35%-45% and a viscosity of 200-300 mPa·s.

4. The process for preparing the carbon point modified flame retardant fir plywood according to claim 1, characterized in that: Pre-treatment of raw wood includes: The raw wood materials are cleaned of impurities, including removing the bark and washing with clean water; The washed raw wood is dried until absolutely dry.

5. The process for preparing the carbon point modified flame retardant fir plywood according to claim 1, characterized in that: The preset mesh size is 50 meshes.

6. The process for preparing the carbon point modified flame retardant fir plywood according to claim 1, characterized in that: The reaction liquid is centrifuged to obtain a flame retardant carbon dot impregnation liquid comprising: The reaction liquid was placed in a centrifuge for centrifugal treatment at 10000 r / min.

7. The process for preparing the carbon point modified flame retardant fir plywood according to claim 1, characterized in that: Stacking the blanks according to the preset quantity includes: Set the preset quantity to an odd value; The roller coating directions of the adhesive of two adjacent blanks are perpendicular to each other.

8. The process for preparing the carbon point modified flame retardant fir plywood according to claim 1, characterized in that: The carbon point modified flame retardant fir plywood obtained after trimming includes: The board is cut into pieces according to preset sizes to obtain carbon dot-modified flame-retardant fir plywood.

9. A carbon point modified flame retardant fir plywood, characterized in that: The method is obtained by the preparation process described in any one of claims 1 to 8.

10. The carbon point modified flame retardant fir plywood according to claim 9, characterized in that: The particle size of the flame-retardant carbon dots of the flame-retardant fir plywood is less than 10 nm.

Images