A highly lightfast color-changing flame-retardant impregnated paper laminated compact wood composite board and its preparation method

Abstract

The present invention relates to the field of interior decoration materials and processing technologies, and provides a high light-fast discoloration-resistant flame-retardant impregnated paper laminated solid wood composite board and a preparation method thereof. The high light-fast discoloration-resistant flame-retardant impregnated paper laminated solid wood composite board includes a solid wood composite board substrate, a high light-fast discoloration-resistant flame-retardant melamine impregnated paper disposed on the surface of the solid wood composite board substrate, and a wear-resistant paper disposed on the side of the high light-fast discoloration-resistant flame-retardant melamine impregnated paper away from the solid wood composite board substrate. The present invention uses a high light-fast discoloration-resistant nano-additive based on fluorescent carbon quantum dots to prepare the melamine impregnated paper. Further, the high light-fast discoloration-resistant flame-retardant impregnated paper laminated solid wood composite board obtained by laminating the melamine impregnated paper with the solid wood composite board substrate has excellent light-fast discoloration resistance and flame-retardant effect, and has a simple manufacturing process, low cost, strong applicability, and is suitable for industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of interior decoration materials and processing, and more specifically, to a high light-fastness flame-retardant impregnated paper laminated compact wood composite board and a preparation method thereof. Background Art

[0002] An impregnated paper laminated compact wood composite board is a home decoration board made by using melamine impregnated paper as the surface material and laminating it on the surface of a solid wood composite artificial board substrate (such as multi-layer plywood, blockboard, etc.), and is widely used in indoor decoration fields such as homes and meeting rooms. The impregnated paper laminated compact wood composite board products mainly include a surface wear-resistant layer, a surface decorative layer (decorative paper, pattern paper), a solid wood composite board substrate and other units compounded, and has the advantages of simple structure, beautiful surface, good dimensional stability, moderate price, and easy design of surface decoration effect, and is deeply loved by the market and consumers.

[0003] Melamine impregnated paper (commonly known as impregnated paper) refers to a pre-coated adhesive paper material that uses plain base paper or printed decorative paper impregnated with amino resins (melamine formaldehyde resin and urea formaldehyde resin) and dried to a certain extent, and can be mutually glued with the contact material by hot pressing. It has the advantages of personalized color and appearance, simple production process, avoiding paint spraying, high dimensional stability, etc. In order to meet the different needs of market consumers, the composite board products made of melamine impregnated paper usually need to be personalized adjusted for the colors of impregnated paper according to the personalized needs of different consumers, and a large amount of colorful inks are often used in this process. The existing melamine impregnated papers generally have problems of poor light fastness and poor ultraviolet light discoloration resistance. Light fastness refers to the ability of the product surface to maintain its original color unchanged under the irradiation of sunlight or artificial light sources. In the use process of the existing melamine impregnated papers, affected by the environment (ultraviolet light and some high-energy visible lights), the ink colors of the impregnated papers are easily slowly oxidized by sunlight, ultraviolet light, some high-energy visible lights and other conditions, resulting in light discoloration; especially in the environmental areas close to glass windows where sunlight often shines, it is very easy to cause obvious surface discoloration (yellowing) problems of the impregnated papers that can be seen by the naked eye, which affects the decorative visual effect of the impregnated papers and also reduces their service life. In terms of the light discoloration technology of impregnated papers, the current conventional technical solution is to use nano-titanium dioxide (photocatalyst) for pretreatment to improve the light fastness performance index of impregnated papers. However, the use of titanium dioxide will also cause great side effects, such as photocatalyzing melamine impregnated paper and the contacted wood substrate, reducing the adhesion between the impregnated paper and the substrate. Secondly, nano-titanium dioxide itself is a milky white crystal material, and excessive addition will cover the surface color of melamine impregnated paper and reduce the decorative effect of the surface texture pattern. Therefore, it is of great significance to improve the light fastness performance of melamine impregnated papers.

[0004] In addition, when existing impregnated paper laminated wood composite boards are used in general household or decoration applications, they are basically no longer treated with flame retardants, relying only on the extremely small flame retardant effect of the surface melamine impregnated paper itself. Existing melamine impregnated papers are formed by pre-curing decorative base paper and melamine resin glue, with low thermal stability and unsatisfactory flame retardant effects. If it is necessary to further improve the flame retardant effect of impregnated paper laminated wood composite boards, it is often necessary to impregnate the solid wood composite board substrate (the main wood layer) with flame retardants, resulting in a large amount of flame retardant usage and a reduction in the mechanical and environmental protection indicators of the substrate.

[0005] Therefore, it is necessary to develop an impregnated paper laminated wood composite board with good light fastness and flame retardant effect to solve the problems existing in the prior art. Summary of the Invention

[0006] The purpose of the present invention is to provide a high light fastness flame retardant impregnated paper laminated wood composite board and its preparation method to solve the technical problems of insufficient light fastness and flame retardant effect of impregnated paper laminated wood composite boards in the prior art.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is:

[0008] In the first aspect, the present invention provides a high light fastness flame retardant impregnated paper laminated wood composite board, including a solid wood composite board substrate, a high light fastness flame retardant melamine impregnated paper disposed on the surface of the solid wood composite board substrate, and an abrasion resistant paper disposed on the side of the high light fastness flame retardant melamine impregnated paper away from the solid wood composite board substrate.

[0009] According to some embodiments of the present invention, the preparation method of the high light fastness flame retardant melamine impregnated paper includes: first impregnating the printed decorative paper, drying it, then impregnating it again, drying, cooling, and cutting to obtain the high light fastness flame retardant melamine impregnated paper; wherein the first impregnation uses a first mixed solution including melamine formaldehyde resin, urea formaldehyde resin, and a high light fastness flame retardant nano - additive based on fluorescent carbon quantum dots, and the second impregnation uses a second mixed solution including melamine formaldehyde resin and a high light fastness flame retardant nano - additive based on fluorescent carbon quantum dots.

[0010] The high light fastness flame retardant nano - additive based on fluorescent carbon quantum dots used in the process of preparing the high light fastness flame retardant melamine impregnated paper contains certain carbon, nitrogen, and sulfur elements, and has excellent expansion and charring and gas - phase flame retardant effects. When encountering fire, the light fastness flame retardant additive attached to the surface of the melamine impregnated paper can accelerate expansion, and at the same time produce some nitrogen - and sulfur - containing non - flammable gases, further diluting the oxygen concentration in the combustion area and improving the flame retardant effect of the melamine impregnated paper.

[0011] According to some embodiments of the present invention, the mass ratio of melamine formaldehyde resin, urea formaldehyde resin and the high light-fast discoloration type nano additive based on fluorescent carbon quantum dots in the first mixed solution is 50:50:(5 - 15).

[0012] According to some embodiments of the present invention, the mass ratio of melamine formaldehyde resin and the high light-fast discoloration type nano additive based on fluorescent carbon quantum dots in the second mixed solution is 100:(10 - 20).

[0013] According to some embodiments of the present invention, the pre-curing degree of the high light-fast discoloration type flame-retardant melamine impregnated paper is 50 - 60%.

[0014] According to some embodiments of the present invention, the total impregnation amount of the high light-fast discoloration type flame-retardant melamine impregnated paper after pre-curing is 150 - 180% of the mass of the printed decorative paper.

[0015] According to some embodiments of the present invention, the preparation method of the high light-fast discoloration type nano additive based on fluorescent carbon quantum dots includes: adding a carbon source, a sulfur source, a nitrogen source, a film-forming aid and water into a closed reactor for mixing, stirring and controlling the oxygen content in the gas in the reactor to be 4 - 8 v%, raising the temperature to carry out a carbonization reaction to obtain the high light-fast discoloration type nano additive based on fluorescent carbon quantum dots.

[0016] According to some embodiments of the present invention, based on 100 parts by mass of water, the carbon source is 1.6 - 2.2 parts by mass, the sulfur source is 0.8 - 1.2 parts by mass, the nitrogen source is 0.8 - 1.2 parts by mass, and the film-forming aid is 0.8 - 1.5 parts by mass.

[0017] According to some embodiments of the present invention, the temperature of the carbonization reaction is 180 - 200 °C and the time is 3 - 5 h.

[0018] According to some embodiments of the present invention, the carbon source includes at least one of citric acid and glucose.

[0019] According to some embodiments of the present invention, the sulfur source includes at least one of thiourea, thioamide (sulfamide), and sulfanilamide.

[0020] According to some embodiments of the present invention, the nitrogen source includes at least one of ethanolamine, polyetherimide, and ethylenediamine.

[0021] According to some embodiments of the present invention, the film-forming aid includes at least one of polyvinyl alcohol, gelatin, and carrageenan;

[0022] In the present invention, on the one hand, the film-forming auxiliary can improve the film-forming strength and uniformity of carbon quantum dots on the surface of melamine impregnated paper, and at the same time can promote the surface passivation of carbon quantum dots in a high-temperature hydrothermal environment, making the particle size distribution of carbon quantum dots more uniform, with good dispersion effect, which is beneficial to their infiltration inside the melamine impregnated paper and film formation on the surface.

[0023] According to some embodiments of the present invention, the average particle size of the high light-fast discoloration type nano auxiliary based on fluorescent carbon quantum dots is less than 6 nm.

[0024] According to some embodiments of the present invention, the maximum absorption wavelength of the high light-fast discoloration type nano auxiliary based on fluorescent carbon quantum dots is 340 - 375 nm.

[0025] According to some embodiments of the present invention, the maximum fluorescence emission wavelength of the high light-fast discoloration type nano auxiliary based on fluorescent carbon quantum dots is 455 - 520 nm.

[0026] According to some embodiments of the present invention, the wear-resistant layer is an aluminum oxide wear-resistant layer.

[0027] According to some embodiments of the present invention, the solid wood composite board substrate is selected from eucalyptus multi-layer plywood or poplar multi-layer plywood.

[0028] According to some embodiments of the present invention, the thickness of the solid wood composite board substrate is 9 - 25 mm; preferably 9 - 15 mm.

[0029] According to some embodiments of the present invention, the formaldehyde emission of the composite board is < 0.5 mg / L, the moisture content is 8.0 - 12.0%, the light fastness is ≥ grade 4 of the gray scale card, the color difference under ultraviolet irradiation is ≤ 3.2, and the flame retardant oxygen index is > 30%.

[0030] In a second aspect, the present invention provides a method for preparing the high light-fast discoloration type flame-retardant impregnated paper laminated solid wood composite board described in the first aspect, including: laminating and assembling in sequence a solid wood composite board substrate, a high light-fast discoloration type flame-retardant melamine impregnated paper, and a wear-resistant paper, and obtaining the high light-fast discoloration type flame-retardant impregnated paper laminated solid wood composite board through hot pressing treatment.

[0031] According to some embodiments of the present invention, edge leveling treatment is carried out before the hot pressing treatment.

[0032] According to some embodiments of the present invention, the temperature of the hot pressing treatment is 120 - 135 °C, the pressure is 2.0 - 3.5 MPa, and the time is 2 - 3 min.

[0033] The beneficial effects of the present invention are at least as follows:

[0034] (1) The present invention uses a highly lightfast color-changing nano-additive based on fluorescent carbon quantum dots to prepare melamine impregnated paper, which results in good film-forming effect, high tensile strength, no change or influence on its original surface color, and can significantly improve the lightfast color-changing performance. Further, the highly lightfast color-changing flame-retardant impregnated paper layer compacted wood composite board prepared by laminating the melamine impregnated paper with a solid wood composite board substrate has excellent lightfast color-changing performance, and the surface color remains the color of the melamine impregnated paper itself, with good decorative effect;

[0035] (2) The present invention uses a highly lightfast color-changing nano-additive based on fluorescent carbon quantum dots to prepare melamine impregnated paper, which greatly improves the flame-retardant effect of the melamine impregnated paper. Using the melamine impregnated paper to prepare a composite board can greatly improve the flame-retardant effect of the highly lightfast color-changing flame-retardant impregnated paper layer compacted wood composite board.

[0036] (3) The manufacturing process of the highly lightfast color-changing flame-retardant impregnated paper layer compacted wood composite board provided by the present invention is simple, low-cost, highly applicable, and suitable for industrial production. Specific Embodiments

[0037] In order to make the technical problems to be solved, technical solutions and beneficial effects of the present invention clearer and more understandable, the following specific embodiments are used to further elaborate on the present invention. It should be understood that the specific embodiments described herein are only used to elaborate on this patent in detail and do not limit the protection scope of the present invention in any way.

[0038] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which the present invention belongs. The reagents used in the following embodiments are all conventional biochemical reagents unless otherwise specified; the raw materials, instruments and equipment used in the following embodiments can all be obtained through market purchases or by existing methods; the reagent dosages are all the dosages in conventional experimental operations unless otherwise specified; the experimental methods are all conventional methods unless otherwise specified.

[0039] In the embodiments and comparative examples of the present invention, the test methods for each performance data are as follows:

[0040] (1) Average particle size: Observed by a high-power transmission electron microscope, the longitudinal and transverse dimensions of nanoparticles (≥20) are recorded, and the arithmetic mean of 40 test data is calculated.

[0041] (2) Maximum absorption wavelength, maximum fluorescence emission wavelength: Tested by a fluorescence spectrometer, and the spectral characteristics of the fluorescent carbon quantum dot liquid solution are recorded.

[0042] (3) Moisture content: Determined by the drying method. Subtract the initial mass (m0) of the material from the mass (m1) after drying in an oven at 103°C, and divide by the dried mass of the material, i.e., (m0 - m1) / (m1)×100%.

[0043] (4) Light fastness performance: Conducted in accordance with the provisions of GB / T17657-2013. Take the composite board specimen and the blue wool standard specimen and expose them together under the irradiation of a xenon arc lamp (irradiance 1.10W / m 2 , narrow width 420nm). Stop the exposure when the color difference between the exposed part and the unexposed part of the 6th grade blue wool standard specimen reaches level 4 of the grey scale. Evaluate the light fastness of the composite board sample.

[0044] The larger the light fastness value, the higher the light fastness value of the test sample, and the better its light color change resistance performance. GB / T24507-2020 "Impregnated Paper Laminated Wood Composite Flooring" requires that the light fastness index performance of the sample reaches above level 4 of the grey scale.

[0045] (5) Color difference: Conducted in accordance with the provisions of GB / T17657-2013. Use a color difference measuring instrument to measure the surface chromaticity of 5 random points of the sample, and calculate the size of the color difference value. Use a dark box ultraviolet test device to measure the change in color difference between the sample and the control group (samples stored under indoor natural light) under the irradiation of two ultraviolet lamps (power 8W, wavelengths 365nm and 302nm respectively), represented by △E.

[0046] Generally recognized in the industry is that when the color difference between the tested sample and the control group sample is higher than 5.0, the naked eye can visually distinguish the change in the surface color of the specimen at a position about 50cm away from the sample; when the color difference value is between 3.2 and 5.0, the color difference change can be faintly seen by the naked eye; when the color difference value ≤ 3.2, there is basically no change in the surface color difference, which is invisible to the naked eye, indicating that the tested sample has high light (ultraviolet light) color change resistance performance.

[0047] (6) Flame retardant performance: Determine the oxygen index (represented by LOI) according to the method of GB / T 2406.2-2009.

[0048] Use the oxygen index to indicate whether the material is flammable. > 30.0% indicates a flame-retardant material (Class B1).

[0049] (7) Formaldehyde release amount: Refer to GB / T17657-2013 "Test Methods for Physical and Chemical Properties of Wood-based Panels and Decorative Wood-based Panels" and use the desiccator method to test the formaldehyde release amount of the board.

[0050] Example 1

[0051] 1.6 g of citric acid, 0.8 g of thiourea and 0.8 g of ethanolamine were added to 100 g of water respectively, and stirred at room temperature to obtain a homogeneous solution. The homogeneous solution was transferred to a 500 mL polytetrafluoroethylene liner with a two-way airflow valve, and 4.0 g of polyvinyl alcohol (alcoholysis degree 87.0-89.0 mol%, viscosity 40.0-48.0 mPa.s, Aladdin reagent manufacturer) sol (20 wt%) was added. At the same time, a nitrogen / oxygen mixed gas flow was introduced into the polytetrafluoroethylene liner at a gas flow rate of 400-500 mL / min. The mixed solution was stirred for 30-60 min to make it fully mixed, so that the oxygen content in the polytetrafluoroethylene liner cavity was 4v%. The polytetrafluoroethylene liner containing the above solution was placed in a stainless steel bottle, and hydrothermally reacted for 5 h under low oxygen conditions at a temperature of 180°C to obtain a highly light-resistant color-changing nano-additive based on fluorescent carbon quantum dots.

[0052] The prepared highly light-resistant color-changing nano-additive based on fluorescent carbon quantum dots does not need further purification. Melamine formaldehyde resin (solid content 65%, viscosity 3500-4500 mPa·s, pH value 7.5-8, Shandong Chengshun Chemical Co., Ltd.), urea-formaldehyde resin (solid content 55%, formaldehyde / urea molar ratio of 1.3:1, homemade in the laboratory) and highly light-resistant color-changing nano-additive based on fluorescent carbon quantum dots are mixed into a first mixed solution at a mass ratio of 50:50:15, and the first mixture is used to impregnate the printed decorative paper, and then dried by an infrared drying device; melamine formaldehyde resin and highly light-resistant color-changing nano-additive based on fluorescent carbon quantum dots are mixed into a second mixed solution at a mass ratio of 100:20, and the dried impregnated printed decorative paper is impregnated with the second mixed solution, and the impregnated paper is dried by an infrared drying device, and the pre-curing degree is 50%; the total impregnation amount of the pre-cured impregnated paper is 150% of the mass of the printed decorative paper. The wear-resistant paper, impregnated paper and multi-layer eucalyptus solid wood composite board substrate (thickness 9mm) were assembled layer by layer and put into a hot press for hot pressing for 2 minutes. The hot pressing temperature was 120°C and the hot pressing pressure was 2.5MPa. After the hot pressing was completed, it was naturally cooled, cured for more than 24 hours, sanded and cut to obtain a highly light-resistant and color-changing flame-retardant impregnated paper laminated solid wood composite board.

[0053] Example 2

[0054] The preparation method of the highly light-resistant color-changing nano-additive based on fluorescent carbon quantum dots is based on Example 1, with the only difference being that the oxygen content in the cavity of the polytetrafluoroethylene liner is 8v%.

[0055] The preparation method of the highly light-resistant and color-discoloration-resistant flame-retardant impregnated paper laminated solid wood composite board is as described in Example 1.

[0056] Example 3

[0057] The preparation method of the highly light-resistant color-changing nano-additive based on fluorescent carbon quantum dots refers to Example 1, with the only difference being that the polyvinyl alcohol sol is replaced with an equal mass of gelatin solution (20 wt %, Aladdin reagent grade, prepared in the laboratory).

[0058] The preparation method of the highly light-resistant and color-discoloration-resistant flame-retardant impregnated paper laminated solid wood composite board is as described in Example 1.

[0059] Example 4

[0060] The preparation method of the highly light-resistant color-changing nano-additive based on fluorescent carbon quantum dots refers to Example 1, with the only difference being that the polyvinyl alcohol sol is replaced with an equal mass of carrageenan solution (20 wt %, Aladdin reagent grade, prepared in the laboratory).

[0061] The preparation method of the highly light-resistant and color-discoloration-resistant flame-retardant impregnated paper laminated solid wood composite board is as described in Example 1.

[0062] Example 5

[0063] The preparation method of the highly light-resistant color-changing nano-additive based on fluorescent carbon quantum dots is shown in Example 1.

[0064] The prepared highly light-resistant color-changing nano-additive based on fluorescent carbon quantum dots does not need further purification. Melamine formaldehyde resin (solid content 65%, viscosity 3500-4500 mPa·s, pH value 7.5-8, Shandong Chengshun Chemical Co., Ltd.), urea-formaldehyde resin (solid content 55%, formaldehyde / urea molar ratio of 1.3:1, homemade in the laboratory) and highly light-resistant color-changing nano-additive based on fluorescent carbon quantum dots are mixed into a first mixed solution at a mass ratio of 50:50:5, and the first mixture is used to impregnate the printed decorative paper, and then dried by an infrared drying device; melamine formaldehyde resin and highly light-resistant color-changing nano-additive based on fluorescent carbon quantum dots are mixed into a second mixed solution at a mass ratio of 100:10, and the dried impregnated printed decorative paper is impregnated with the second mixed solution, and the impregnated paper is dried by an infrared drying device, and the pre-curing degree is 60%; the total impregnation amount of the pre-cured impregnated paper is 180% of the mass of the printed decorative paper. The wear-resistant paper, impregnated paper and multi-layer eucalyptus solid wood composite board substrate (thickness 9mm) were assembled layer by layer and put into a hot press for hot pressing for 3 minutes at a temperature of 130°C and a pressure of 3MPa. After the hot pressing was completed, the laminated solid wood composite board with high light resistance and color change was obtained through natural cooling, curing for more than 24 hours, sanding and cutting.

[0065] Comparative Example 1

[0066] The preparation method of the nano-additive is similar to that of Example 1, except that the oxygen content in the cavity of the polytetrafluoroethylene liner is 2 v%.

[0067] The preparation method of the composite plate is as described in Example 1.

[0068] Comparative Example 2

[0069] The preparation method of the nano additive was referred to Example 1, with the difference being only that: the oxygen content in the polytetrafluoroethylene bladder cavity was 12 v%.

[0070] The preparation method of the composite board was referred to Example 1.

[0071] Comparative Example 3

[0072] The preparation method of the nano additive was referred to Example 1, with the difference being only that: nitrogen / oxygen mixed gas flow was not introduced, and the oxygen content in the polytetrafluoroethylene bladder cavity was 21 v% (basically equivalent to the oxygen content in the atmosphere).

[0073] The preparation method of the composite board was referred to Example 1.

[0074] Comparative Example 4

[0075] The preparation method of the nano additive was referred to Example 1, with the difference being only that: polyvinyl alcohol sol was not added.

[0076] The preparation method of the composite board was referred to Example 1.

[0077] Comparative Example 5

[0078] Melamine formaldehyde resin (solid content 65%, viscosity 3500 - 4500 mPa·s, pH value 7.5 - 8, Shandong Chengshun Chemical Co., Ltd.) and urea formaldehyde resin (solid content 55%, molar ratio of formaldehyde / urea 1.3:1, self-made in the laboratory) were mixed at a mass ratio of 1:1 and used to impregnate and treat the printed decorative paper, followed by drying with an infrared drying device; then the dried impregnated printed decorative paper was impregnated and treated with melamine formaldehyde resin and dried with an infrared drying device to obtain a melamine impregnated paper with a pre-curing degree of 50%; the total impregnation amount of the pre-cured melamine impregnated paper was 150% of the mass of the printed decorative paper. The wear-resistant paper, melamine impregnated paper, and multi-layer eucalyptus solid wood composite board substrate (thickness 9 mm) were assembled layer by layer, placed in a hot press and hot pressed for 2 min at a hot press temperature of 120°C and a hot press pressure of 2.5 MPa. After hot pressing, it was naturally cooled, cured for more than 24 h, sanded, and cut to obtain the composite board.

[0079] Performance Evaluation

[0080] (1) The average particle size, maximum absorption wavelength, maximum fluorescence emission wavelength, and solution pH of the high light-fast discoloration type nano additives based on fluorescent carbon quantum dots provided in Examples 1 - 4 and the nano additives provided in Comparative Examples 1 - 4 were tested, and the results are shown in Table 1.

[0081] Table 1 Performance Test of Nano Additives

[0082]

[0083]

[0084] Generally, light waves with a wavelength < 400 nm are called ultraviolet light, light waves with 400 nm ≤ wavelength < 450 nm are called high-energy blue light, light waves with 450 nm ≤ wavelength < 485 nm are called low-energy blue light, light waves with 485 nm ≤ wavelength < 510 nm are called blue-green light, and light waves with 510 nm ≤ wavelength < 565 nm are called green light. Among them, ultraviolet light (< 400 nm) and high-energy blue light (400 - 450 nm) will cause photochromism of the irradiated material. It can be seen from the test results in Table 1 that when the oxygen content in the autoclave system is maintained at 4 - 8 v%, the average particle size of the highly light-resistant photochromic nano-additive based on fluorescent carbon quantum dots prepared is less than 6 nm, and the maximum absorption wavelengths are 340 nm, 355 nm, 360 nm, and 370 nm respectively, which are located in the ultraviolet absorption band. At the same time, the maximum fluorescence emission wavelengths are 455 nm, 485 nm, 490 nm, and 510 nm respectively, and the corresponding exciting visible lights are low-energy blue light, blue-green light, and green light.

[0085] Although the maximum absorption wavelength of the nano-additive prepared in Comparative Example 1 (oxygen content 2 v%) is 345 nm, which is located in the ultraviolet absorption band, the maximum fluorescence emission wavelength is 441 nm, still in the category of high-energy blue light. The light conversion efficiency is low, that is, the efficiency of converting external ultraviolet light into low-energy visible light is poor. The light energy of high-energy blue light itself is higher than that of low-energy blue light and blue-green visible light. Therefore, the photochromic resistance effect is poor.

[0086] The average particle size of the nano-additives prepared in Comparative Example 2 (oxygen content 12 v%) and Comparative Example 3 (oxygen content 21 v%) begins to increase, indicating that as the oxygen content increases, the nano-additives begin to aggregate into clusters, reducing the dispersibility of the nano-materials. In addition, similar to Comparative Example 1, the maximum fluorescence emission wavelengths of the nano-materials prepared in Comparative Example 2 and Comparative Example 3 are 445 nm and 448 nm respectively, belonging to the typical category of high-energy blue light. Although the energy of high-energy blue light is lower than that of the ultraviolet light band, it is still higher than that of low-energy blue light and blue-green visible light. Therefore, the photochromic resistance effect of the high-energy blue light nano-additive is poor.

[0087] It should be noted that in the past, the oxygen concentration in the reaction system was often not regulated when preparing carbon quantum dot materials. According to this idea, the pH of the light-fast color-changing auxiliary solution prepared in Comparative Example 3 was 3.2, which was strongly acidic, and this was not conducive to the subsequent mixing with melamine resin adhesive. It is generally recognized in the industry that when an external additive is added to the melamine resin adhesive and its pH value drops to 3.0 - 4.0, it will cause a sharp increase in the viscosity of the adhesive, a sharp acceleration of the curing rate, and a certain degree of low-strength pre-curing. This is not conducive to the fluidity of the adhesive, the hardness of the adhesive layer, and the aging resistance of the adhesive. The pH values of the product solutions in Examples 1 and 2 were 5.2 - 5.6, only slightly acidic, and did not affect the subsequent mixing with melamine resin adhesive.

[0088] (2) Test the performance of the high light-fast color-changing flame-retardant impregnated paper laminated wood composite boards provided in each example and the composite boards provided in each comparative example. The results are shown in Table 2.

[0089] Table 2 Performance Test of Composite Boards

[0090]

[0091]

[0092] It can be seen from the test results in Table 2 that as the oxygen content in the reaction kettle increases, the moisture content of the prepared composite board is on the high side. This is mainly because under oxygen-rich conditions, more carboxyl groups are formed on the surface of the synthesized carbon nanodots, resulting in a relatively high hygroscopicity of the nano additives, and causing a certain degree of increase in the moisture content of the prepared composite board. When the oxygen content in the reaction kettle is equivalent to that in the air, the moisture content of the prepared composite board reaches 15.4%, which is higher than the moisture content requirement (8 - 12%) during actual home applications. Later, quality problems such as deformation, cracking, and mildew of the composite board will occur due to the moisture absorption - desorption of the wood material itself.

[0093] The oxygen content (oxygen content 2v%) in the reaction system of Comparative Example 1 was lower than 4v%. The moisture content of the composite board was 8.2%, meeting the moisture content requirement (8 - 12%) during actual home applications. The flame-retardant oxygen index was also significantly improved compared to Comparative Example 5, but it did not meet the high flame-retardant requirement of an oxygen index higher than 30%. In addition, the light-fast color fastness on the surface of the composite board met Grade 4, but the surface color difference after ultraviolet irradiation was higher than 3.2, with a relatively obvious visible color difference change to the naked eye, indicating that when the oxygen content in the system is lower than 4%, it is not conducive to the formation of high light-fast color-changing nano additives.

[0094] In Comparative Example 2 (oxygen content 12 v%) and Comparative Example 3 (oxygen content 21 v%), the light fastness of the composite board surface was <4 levels, and the surface color difference after ultraviolet irradiation was also relatively large, indicating that as the oxygen content was higher than 8 v%, the light fastness of the prepared nano-additive became worse, the ultraviolet absorption decreased, and the high-energy ultraviolet light could not be well converted into relatively low-energy visible light. In addition, the flame retardant oxygen index and formaldehyde release amount were also relatively poor.

[0095] In Comparative Example 5, no nano-additive was added, and the light fastness, surface color difference after ultraviolet irradiation, formaldehyde release amount, flame retardant oxygen index, etc. of the prepared wood composite board were significantly worse than those of each example.

[0096] It should be noted that the above-described embodiments are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described by referring to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than limiting words. Modifications can be made to the present invention within the scope of the claims of the present invention, and the present invention can be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein. On the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A highly lightfast discoloration-resistant flame-retardant impregnated paper laminated compact wood composite board, characterized in that, The surface material of the composite board includes a solid wood composite board substrate, a highly lightfast color-changing flame-retardant melamine impregnated paper disposed on the surface of the solid wood composite board substrate, and an abrasion-resistant paper disposed on the side of the highly lightfast color-changing flame-retardant melamine impregnated paper away from the solid wood composite board substrate; The preparation method of the highly lightfast color-changing flame-retardant melamine impregnated paper includes: first impregnating the printed decorative paper for the first time, drying it, then impregnating it for the second time, drying, cooling, and cutting to obtain the highly lightfast color-changing flame-retardant melamine impregnated paper; wherein the first impregnation uses a first mixed solution including melamine formaldehyde resin, urea formaldehyde resin, and a highly lightfast color-changing nano additive based on fluorescent carbon quantum dots, and the second impregnation uses a second mixed solution including melamine formaldehyde resin and a highly lightfast color-changing nano additive based on fluorescent carbon quantum dots; The preparation method of the highly lightfast color-changing nano additive based on fluorescent carbon quantum dots includes: adding a carbon source, a sulfur source, a nitrogen source, a film-forming aid, and water into a closed reactor for mixing, stirring, and controlling the oxygen content in the gas in the reactor to be 4-8 v%, raising the temperature to carry out a carbonization reaction to obtain the highly lightfast color-changing nano additive based on fluorescent carbon quantum dots.

2. The composite board according to claim 1, characterized in that, In the first mixed solution, the mass ratio of melamine formaldehyde resin, urea formaldehyde resin, and the highly lightfast color-changing nano additive based on fluorescent carbon quantum dots is 50:50:(5-15); And / or, in the second mixed solution, the mass ratio of melamine formaldehyde resin and the highly lightfast color-changing nano additive based on fluorescent carbon quantum dots is 100:(10-20); And / or, the pre-curing degree of the highly lightfast color-changing flame-retardant melamine impregnated paper is 50-60%; 3. The composite board according to claim 2, characterized in that, The total impregnation amount after pre-curing of the highly lightfast color-changing flame-retardant melamine impregnated paper is 150-180% of the mass of the printed decorative paper.

4. The composite board according to claim 1, wherein Based on 100 parts by mass of water, the carbon source is 1.6-2.2 parts by mass, the sulfur source is 0.8-1.2 parts by mass, the nitrogen source is 0.8-1.2 parts by mass, and the film-forming aid is 0.8-1.5 parts by mass; And / or, the temperature of the carbonization reaction is 180-200 °C, and the time is 3-5 h.

5. The composite board according to claim 4, characterized in that, The carbon source includes at least one of citric acid and glucose; And / or, the sulfur source includes at least one of thiourea, thioamide, and sulfanilamide; And / or, the nitrogen source includes at least one of ethanolamine, polyetherimide, and ethylenediamine; And / or, the film-forming aid includes at least one of polyvinyl alcohol, gelatin, and carrageenan.

6. The composite board according to any one of claims 1-5, characterized in that, The abrasion-resistant paper is aluminum trioxide abrasion-resistant paper; And / or, the solid wood composite board substrate is selected from eucalyptus multi-ply plywood or poplar multi-ply plywood; And / or, the thickness of the solid wood composite board substrate is 9-25 mm.

7. The composite board according to any one of claims 1-5, characterized in that The formaldehyde release amount of the composite board < 0.5 mg / L, the moisture content is 8.0-12.0%, the lightfast color fastness ≥ grade 4 of the gray scale card, the color difference under ultraviolet irradiation ≤ 3.2, and the flame retardant oxygen index > 30%.

8. The preparation method of the highly light-fast discoloration-resistant flame-retardant impregnated paper layer-compacted wood composite board according to any one of claims 1-7, characterized in that, Including: Stacking blanks layer by layer in the order of the solid wood composite board substrate, the highly lightfast color-changing flame-retardant melamine impregnated paper, and the abrasion-resistant paper, and obtaining the highly lightfast color-changing flame-retardant impregnated paper layer compacted wood composite board through hot pressing treatment.

9. The preparation method according to claim 8, characterized in that, The temperature of the hot pressing treatment is 120 to 135 °C, the pressure is 2.0 to 3.5 MPa, and the time is 2 to 3 minutes.

Images