Formaldehyde-removed EB-cured pet veneered cabinet door panel

Abstract

The present invention relates to a formaldehyde-removed EB-cured PET veneered cabinet door panel, which is prepared by means of the steps of preparing an electron-beam (EB) curable coating paint, preparing a formaldehyde-free adhesive coating paint, preparing a PET film layer, coating a cabinet door panel with said paints, and removing formaldehyde. An EB-curing enhancement modifier different from conventional cabinet door panels is added as the surface, and in cooperation with a multi-layer structure of a photocatalyst medium PET film layer, a formaldehyde-free adhesive and a plate and secondary formaldehyde removal after the panel is manufactured, a formaldehyde-removed EB-cured PET veneered cabinet door panel which is anti-fouling, wear-resistant, high-hardness, impact-resistant, yellowing-resistant, fingerprint-resistant, green ecological and environmentally friendly is obtained.

Description

Formaldehyde purification EB solidification PET veneer cabinet door plate TECHNICAL FIELD

[0001] The present application relates to the field of furniture, in particular to the field of formaldehyde purification EB solidification PET veneer cabinet door plate. BACKGROUND

[0002] Wood-based board includes natural wood-based board and a large number of wood-based artificial board (plywood, particle board, fiberboard, etc.), which is widely used in the field of furniture, building materials, etc. In the production process of wood-based board, the wood-based board without the final finishing process is called a blank, and the surface of the blank is coated and cured to form a decorative coating with colorful colors, various color tones and changing patterns, and a protective coating with high surface performance and high adhesion.

[0003] The current situation of indoor air quality is a focus of social concern, and the excessive concentration of formaldehyde, TVOC and bacteria seriously affects people's physical and mental health. At present, the main indoor decorative board materials include: joinery board, plywood, decorative panel, density board, integrated material, particle board, fireproof board, etc. In the decorative board used in indoor, such as paint, latex paint or adhesive, there are a large amount of harmful gases such as formaldehyde. Research shows that the release period of indoor formaldehyde is generally 3 to 15 years. Living in a space containing harmful gases such as formaldehyde for a long time will cause great harm to the human body.

[0004] In addition, the surface layer of the cabinet board has various coatings, and the general curing method is thermal curing or ultraviolet curing. However, in the process of curing liquid coating, a large amount of heat or electric energy is consumed by using heating curing method, and energy cannot be efficiently utilized. At the same time, the thermal curing process uses coatings containing a large amount of solvent, and the organic volatile matter (VOCs) in the solvent is released into the air when the solvent is volatilized by heat, causing serious air pollution. The microstructure of the paint cured by heat is a two-dimensional linear interlaced structure, and the curing can be improved, but it cannot bring high strength, anti-fouling and anti-scratching of the surface layer of the wood board.

[0005] UV curing process is a substitute process for thermal curing, which can generate reactive free radicals or ions by irradiation of UV light, and then initiate chain growth (polymerization / crosslinking, etc.), so that the liquid coating is quickly formed and cured. Since little or no solvent is used in UV curing coatings, UV curing can reduce VOC emissions during the curing process and reduce energy consumption. However, due to the principle of UV curing, it is difficult for UV light to penetrate the entire coating when curing thick or colored or containing metal powder or containing inorganic filler coatings, which requires multiple UV curing processes, increases the complexity of the production line and the production line footprint, and reduces the controllability of product quality; During UV curing, the high temperature of the UV lamp tube itself and the infrared section of its emission spectrum will cause the irradiated object to heat up and deform, especially when processing large area thin plates, there will be product deformation problems, quality problems and production safety hazards; And the cost of the photoinitiator used in UV curing is high, which will also bring health hazards. The structure of the UV cured material is mostly 2.5-dimensional dendritic crosslinking structure, and the curing degree is about 40-70%, which is insufficient and may affect the use efficiency of the subsequent related products. SUMMARY

[0006] The technical purpose of the present application is to solve the problems in the background art and provide a formaldehyde purification EB cured PET veneer cabinet door panel.

[0007] The above technical purpose of the present application is achieved by the following technical scheme:

[0008] A formaldehyde purification EB cured PET veneer cabinet door panel, comprising the following process steps:

[0009] Step S1, electronic beam curing coating preparation: a certain amount of EB electron beam curing enhancer fine powder is uniformly mixed and stirred in a mixed solution of 40-60 DEG C acrylic emulsion and waterborne polyurethane emulsion at a constant temperature, and the substance particles are uniformly dispersed and stored for standby;

[0010] Step S2, no formaldehyde adhesive coating preparation:

[0011] S21, lignin purification: the lignin cake is dissolved in sodium hydroxide solution and stirred uniformly, then the supernatant is extracted by centrifugation, the supernatant is adjusted to pH with dilute sulfuric acid, and then filtered, washed and dried to obtain lignin powder;

[0012] S22 Preparation of formaldehyde-free adhesive coating: The purified lignin is dissolved in sodium hydroxide solution, heated to constant temperature under stirring, and glyoxal is added. After the reaction is completed and the mixture is cooled, lignin glyoxal is obtained. The prepared lignin glyoxal is mixed with polymeric 4,4 / -diphenyl methane diisocyanate pMDI to obtain a formaldehyde-free adhesive;

[0013] Step S3 Preparation of photocatalyst medium PET film layer: PET granules, i.e. PET fine powder particles, are melted and extruded and cooled to form a PET film layer by mixing with a proper amount of nano-titanium dioxide.

[0014] Step S4 Coating of cabinet door panel: The cabinet door panel has a multi-layer structure, which includes an adhesive layer outside the panel core, a photocatalyst medium PET film layer, and an EB curing layer. The adhesive layer is prepared by using the formaldehyde-free adhesive coating prepared in step S2, and the EB curing layer is prepared by using the electron beam curing coating prepared in step S1.

[0015] Step S5 Formaldehyde purification: The door panel cured in step S3 is placed in a purifier for formaldehyde purification. Active calcium alginate gel ACA is used as a purifying agent in the purifier. After the purification is completed, the final formaldehyde-purified EB-cured PET-finished cabinet door panel is obtained.

[0016] EB represents electron beam, and EB curing means electron beam curing. In this scheme, in the environment of electron beam, nitrogen molecules are in a plasma state, and under high energy, the Si, Al, and B in the nano-silicon, aluminum oxide, and boric acid in the enhanced modifier coating on the surface of the panel react with the nitrogen molecules to form silicon nitride Si3N4, aluminum nitride AlN, and boron nitride BN. Silicon nitride, aluminum nitride, and boron nitride are all high-hardness ceramic materials with anti-fouling, wear-resistant, and anti-fingerprint properties.

[0017] As a preferred embodiment, the main components of the EB electron beam curing enhanced modifier in step S1 are nano-silicon powder, aluminum oxide, and boric acid or borax powder. In the preparation process, 1-5 parts of nano-silicon powder, 1-3 parts of aluminum oxide powder, and 1-5 parts of boric acid or borax powder are uniformly mixed and used, and the above mixed fine powder is gradually added to the acrylic acid and water-based polyurethane mixed emulsion and uniformly stirred and heated.

[0018] The present application has the advantages that a small amount of nano-silicon powder, aluminum oxide, and boric acid or borax powder is mixed into the emulsion coating, which can greatly enhance the anti-fouling, wear-resistant, impact-resistant, and yellowing-resistant properties of the panel under electron beam irradiation. Since the amount of addition is not large, only stirring is required after heating, and the process is low-cost and easy to operate.

[0019] As preferred, in the process of S21 lignin purification in step S2, the mass-volume concentration of the lignin cake and sodium hydroxide solution is 80-150 g / L, the concentration of sodium hydroxide is 1 mol / L, after mixing and stirring, centrifugation is performed at 4000-4500 rpm for 5 min to obtain a supernatant suspension, the suspension is heated to 75-90°C and kept constant for 2 h, then vacuum filtration and washing twice are performed, and finally 50°C drying for 12-30 h to obtain a purified lignin powder.

[0020] As preferred, in the process of S22 formaldehyde-free adhesive preparation in step S2, 15-40 parts of the purified lignin powder is dissolved in a stirring container containing 1M sodium hydroxide, and glyoxal is gradually added during stirring, the mass fraction of glyoxal is 60-85 parts, and after uniform mixing, a lignin glyoxal is obtained; in the preparation of the formaldehyde-free adhesive, 40-60 parts of the lignin glyoxal is used, and the rest is pMDI.

[0021] The present application has the advantage that glyoxal is the simplest dialdehyde with two adjacent carbon groups, and has been proven to be a very promising formaldehyde-free adhesive due to its significantly lower toxicity than formaldehyde. Specifically, formaldehyde is classified by ECHA (European Chemical Agency) as carcinogenic, mutagenic and re-toxic, and the LD value (500−800 mg / kg) has been measured, which is an order of magnitude lower than that of glyoxal (2960−8979 mg / kg). In addition, there are various ways to produce glyoxal from bio-based raw materials or intermediates, including sugars, ethanol and ethylene glycol. In addition, glyoxal has been proven to be a suitable substitute for formaldehyde as a non-volatile, biodegradable and low-cost monomer. Mixing lignin lignin-glyoxal resin with 40−60%pMDI, the synthesized adhesive has sufficient internal bonding strength required for wood board applications, and also avoids formaldehyde emission.

[0022] As preferred, in the process of preparing the PET film layer in step S3, the mass fraction of terephthalic acid glycol ester particles, i.e. PET fine powder particles, is 75-95 parts, and the mass fraction of nano-titanium dioxide is 5-25 parts.

[0023] The present application has the advantage that the nano-titanium dioxide is combined with the PET film, and when the light transmits through the surface layer and irradiates on the PET film layer, the PET film layer generates a radiative wave to cause a chemical reaction of decomposition of formaldehyde and other molecular structures, which can effectively degrade harmful substances in the activity place, further improving the effect of purifying formaldehyde.

[0024] As preferred, in the process of coating the cabinet door plate paint in step S4, the multi-layer structure of the cabinet door plate is that the plate core is coated with a bonding layer, a photocatalyst medium PET film layer, a bonding layer and an EB curing layer in order, and after coating the EB curing layer paint, the whole system is placed in a nitrogen environment of more than 99.9% for electron beam curing.

[0025] Preferably, the top end of the plate core connected with the glue layer is provided with a hole, and the hole is provided with porous alumina.

[0026] Preferably, the glue amount of the glue layer is 10-20 g / m 2 , the thickness of the photocatalyst medium PET film layer is 0.10-0.30 mm, and the glue amount of the EB curing layer is 10-20 g / m 2 .

[0027] The cabinet door plate obtained by the method has the advantages of being more solid and not easy to break, and the surface is resistant to sliding and fingerprints.

[0028] The cabinet door plate obtained by the method has the advantages of being more solid and not easy to break, and the surface is resistant to sliding and fingerprints.

[0029] Preferably, in the preparation of the active calcium alginate gel ACA, after the wheat seedling leaves are ground, a phosphate buffer solution is added for extraction, the solid-liquid ratio is 1:2, after extraction, twice the amount of 1% pre-cooled sodium alginate solution is added and uniformly mixed, and then the mixture is dropped into a 3% calcium chloride solution to form the active calcium alginate gel containing plant extracts.

[0030] The cabinet door plate obtained by the method has the advantages of being more solid and not easy to break, and the surface is resistant to sliding and fingerprints.

[0031] In summary, the present application has the following advantages:

[0032] 1. By adding nano silicon powder, alumina and boric acid powder in the coating formula of the reinforcing modifier, under the radiation of EB high-energy electron beam, the performance of the household cabinet door plate can be greatly improved, such as stain resistance, wear resistance, high hardness, impact resistance, yellowing resistance, fingerprint resistance, etc., and the process is green and environmentally friendly;

[0033] 2. The design of the plate core and the formaldehyde-free adhesive coating achieves internal purification of formaldehyde in the plate, and the subsequent external secondary purification step of the active calcium alginate gel ACA purifier achieves more optimal and efficient formaldehyde purification;

[0034] 3. The formaldehyde-purified EB-cured PET veneer cabinet door plate prepared by the scheme has ecological non-pollution, low production cost, simple process and can realize large-scale production. BRIEF DESCRIPTION OF DRAWINGS

[0035] Fig. 1 is a structural schematic diagram of a formaldehyde-purified EB-cured PET veneer cabinet door plate;

[0036] Fig. 2 is a schematic diagram of a plate core structure in a formaldehyde-purified EB-cured PET veneer cabinet door plate;

[0037] Fig. 3 is an enlarged schematic diagram of A in the plate core structure;

[0038] In the figure, 1 is a plate core; 11 is a hole; 12 is porous alumina; 2 is a glue layer; 3 is a photocatalyst medium PET film layer; and 4 is an EB-cured layer. DETAILED DESCRIPTION

[0039] The following specific embodiments are only an explanation of the present application and are not a limitation of the present application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the specification, and the modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

[0040] Example 1

[0041] Step S1: Preparation of an electron beam-cured coating: a certain amount of EB electron beam-cured enhancement modifier fine powder is uniformly mixed and stirred in a mixed solution of 40℃ acrylic emulsion and water-based polyurethane emulsion at a constant temperature, and the substance particles are uniformly dispersed for storage. The main components of the EB electron beam-cured enhancement modifier are nano silicon powder, alumina and boric acid or borax powder. During the preparation process, 1 part of nano silicon powder, 1 part of alumina powder and 1 part of boric acid or borax powder are uniformly mixed for standby, and the above mixed fine powder is gradually added to the acrylic and water-based polyurethane mixed emulsion and uniformly stirred.

[0042] Step S21: Lignin purification: lignin cake is dissolved in sodium hydroxide solution and uniformly mixed. During the lignin purification process, the dissolution mass volume concentration of lignin cake and sodium hydroxide solution is 80g / L, and the concentration of sodium hydroxide is 1mol / L. After mixing and stirring, centrifugation is performed at 4000rpm for 5min to obtain supernatant suspension. The supernatant is adjusted to pH with dilute sulfuric acid, and the suspension is heated to 75℃ and kept at a constant temperature for 2h, then vacuum filtered and washed twice, and finally dried at 50℃ for 12h to obtain purified lignin powder.

[0043] Step S22: Preparation of formaldehyde-free adhesive coating: The purified lignin 15 parts is dissolved in a stirred container with 1M sodium hydroxide, and heated to a constant temperature. Then, glyoxal is gradually added, and the mass fraction of glyoxal is 85 parts. After mixing and stirring, the lignin glyoxal is obtained after cooling. Then, the lignin glyoxal is mixed with polymeric 4,4 / -diphenyl methane diisocyanate (pMDI) to obtain a formaldehyde-free adhesive. After mixing, the lignin glyoxal is obtained, and the mass fraction of lignin glyoxal is 40 parts, and the remaining is pMDI.

[0044] Step S3: Preparation of photocatalyst medium PET film layer: PET fine powder particles are melted and extruded and cooled to form a PET film layer by mixing with a proper amount of nano-titanium dioxide. The mass fraction of PET fine powder particles is 75 parts, and the mass fraction of nano-titanium dioxide is 25 parts.

[0045] Step S4: Cabinet door panel coating: The cabinet door panel has a multi-layer structure, including an adhesive layer outside the panel core, a photocatalyst medium PET film layer, and an EB curing layer. The adhesive layer uses the formaldehyde-free adhesive coating prepared in step S2, and the EB curing layer uses the electron beam curing coating prepared in step S1. During the coating process of the door panel, the multi-layer structure of the cabinet door panel is as follows: the panel core 1 is coated with an adhesive layer 2, a photocatalyst medium PET film layer 3, an adhesive layer 2, and an EB curing layer 4 in order. After the EB curing layer 4 is coated, the entire system is placed in a nitrogen N2 environment with a purity of more than 99.9% for electron beam curing. The top end of the panel core 1 and the adhesive layer 2 is provided with a hole 11, and a porous aluminum oxide 12 is arranged in the hole 11. The thickness of the panel core is 10 mm. The adhesive amount of the adhesive layer is 10 g / m 2 , the thickness of the photocatalyst medium PET film layer is 0.10 mm, and the adhesive amount of the EB curing layer is 10 g / m 2 .

[0046] Step S5: Formaldehyde purification: The door panel after curing in step S3 is placed in a purifier for formaldehyde purification. The purifier uses active calcium alginate gel (ACA) as a purifying agent. After purification, the final formaldehyde-purified EB-cured PET-faced cabinet door panel is obtained.

[0047] Example 2

[0048] Step S1 electron beam curing coating preparation: a certain amount of EB electron beam curing enhancement modifier fine powder is uniformly mixed and stirred in a mixed solution of acrylic emulsion and waterborne polyurethane emulsion at 60°C, and the substance particles are uniformly dispersed and stored for standby, wherein the main components of the EB electron beam curing enhancement modifier are nano silicon powder, aluminum oxide and boric acid or borax powder; during the preparation process, 5 parts of nano silicon powder fine powder, 3 parts of aluminum oxide fine powder and 5 parts of boric acid or borax powder are uniformly mixed for standby, and the above mixed fine powder is gradually added to the acrylic and waterborne polyurethane mixed emulsion and uniformly stirred.

[0049] Step S21 lignin purification: dissolve the lignin cake in sodium hydroxide solution and mix uniformly, during the process of lignin purification, the dissolution mass concentration of lignin cake and sodium hydroxide solution is 150g / L, the concentration of sodium hydroxide is 1mol / L, after mixing and stirring, centrifuge at 4500rpm for 5min to obtain supernatant suspension, adjust the pH of supernatant with dilute sulfuric acid, take the suspension and heat to 90°C for 2h, then vacuum filter and wash twice, finally dry at 50°C for 30h to obtain purified lignin powder;

[0050] Step S22 preparation of formaldehyde-free adhesive coating: dissolve 40 parts of the above purified lignin in a stirring container containing 1M sodium hydroxide, gradually add glyoxal while stirring and heating to constant temperature, the mass fraction of glyoxal is 60 parts, after mixing and stirring reaction, cool to obtain lignin glyoxal, mix the prepared lignin glyoxal with polymer 4,4 / -diphenyl methane diisocyanate pMDI to obtain formaldehyde-free adhesive, after mixing uniformly, obtain lignin glyoxal, wherein the mass fraction of lignin glyoxal is 60 parts, and the rest is pMDI.

[0051] Step S3 photocatalyst medium PET film layer preparation: melt the polyethylene terephthalate particles, i.e. PET fine powder particles, and extrude and cool to form a PET film layer by mixing with a proper amount of nano titanium dioxide; wherein the mass fraction of PET fine powder particles is 95 parts, and the mass fraction of nano titanium dioxide is 5 parts.

[0052] Step S4 cabinet door plate paint coating: the cabinet door plate is a multi-layer structure, and the coated multi-layer structure includes a bonding layer outside the plate core, a photocatalyst medium PET film layer and an EB curing layer; the bonding layer uses the formaldehyde-free adhesive coating prepared in step S2, and the EB curing layer uses the electron beam curing coating prepared in step S1; during the coating of the door plate paint, the multi-layer structure of the cabinet door plate is that the plate core 1 is sequentially coated with a bonding layer 2, a photocatalyst medium PET film layer 3, a bonding layer 2 and an EB curing layer 4; after the coating of the EB curing layer 4, the entire system is placed in a nitrogen N2 environment with a purity of more than 99.9% for electron beam curing; a hole 11 is formed at the top end where the plate core 1 is connected to the bonding layer 2, and a porous alumina 12 is arranged in the hole 11; the thickness of the plate core is 18 mm; the amount of adhesive of the bonding layer is 20 g / m 2 ; the thickness of the photocatalyst medium PET film layer is 0.30 mm; and the amount of adhesive of the EB curing layer is 20 g / m 2 .

[0053] Step S5 formaldehyde purification: the door plate cured in step S3 is placed in a purifier for formaldehyde purification; the purifier uses active calcium alginate gel ACA as a purifying agent; and the final formaldehyde-purified EB-cured PET-finished cabinet door plate is obtained after the purification is completed.

[0054] Example 3

[0055] Step S1: preparation of an electron beam curing coating: a certain amount of EB electron beam curing enhancer fine powder is uniformly mixed and stirred in a mixed solution of an acrylic emulsion and a water-based polyurethane emulsion at 50°C, and the substance particles are uniformly dispersed for storage; the main components of the EB electron beam curing enhancer include nano silicon powder, alumina and boric acid or borax powder; during the preparation process, 4 parts of nano silicon powder, 1.5 parts of alumina powder and 3.2 parts of boric acid or borax powder are uniformly mixed for use, and the above-mentioned mixed fine powder is gradually added to the mixed emulsion of acrylic acid and water-based polyurethane and uniformly stirred.

[0056] Step S21: purification of lignin: lignin cake is dissolved in a sodium hydroxide solution and uniformly mixed by stirring; during the purification of lignin, the dissolution mass concentration of the lignin cake and the sodium hydroxide solution is 100 g / L, and the concentration of sodium hydroxide is 1 mol / L; after the mixing and stirring, centrifugation is performed at 4500 rpm for 5 min to obtain a supernatant suspension; the supernatant is adjusted to a pH value by dilute sulfuric acid; the suspension is heated to 80°C and kept at a constant temperature for 2 h, then vacuum filtered and washed twice, and finally dried at 50°C for 24 h to obtain a purified lignin powder;

[0057] Step S22: Preparation of formaldehyde-free adhesive coating: The purified lignin 30 parts is dissolved in a stirred container with 1M sodium hydroxide, and heated to a constant temperature. Then, gradually add glyoxal, the mass fraction of glyoxal is 70 parts, and mix and stir until the reaction is complete. After cooling, lignin glyoxal is obtained. Then, mix the obtained lignin glyoxal with polymeric 4,4 / -diphenyl methane diisocyanate (pMDI) to obtain a formaldehyde-free adhesive. After mixing uniformly, lignin glyoxal is obtained, wherein the mass fraction of lignin glyoxal is 48 parts, and the rest is pMDI.

[0058] Step S3: Preparation of photocatalyst medium PET film layer: melt the polyethylene terephthalate particles (PET fine powder particles) and mix with a proper amount of nano-titanium dioxide, then extrude and cool to form a PET film layer; wherein the mass fraction of PET fine powder particles is 85 parts, and the mass fraction of nano-titanium dioxide is 15 parts.

[0059] Step S4: Coating of cabinet door panel: the cabinet door panel has a multi-layer structure, including an adhesive layer outside the panel core, a photocatalyst medium PET film layer, and an EB curing layer. The adhesive layer uses the formaldehyde-free adhesive coating prepared in step S2, and the EB curing layer uses the electron beam curing coating prepared in step S1. During the coating process of the door panel, the multi-layer structure of the cabinet door panel is as follows: the panel core 1 is coated with an adhesive layer 2, a photocatalyst medium PET film layer 3, an adhesive layer 2, and an EB curing layer 4 in order. After coating the EB curing layer 4, the entire system is placed in a nitrogen N2 environment with a purity of more than 99.9% for electron beam curing. A hole 11 is provided at the top end of the panel core 1 and the adhesive layer 2, and a porous aluminum oxide 12 is arranged in the hole 11. The thickness of the panel core is 15mm. The adhesive amount of the adhesive layer is 14g / m 2 , the thickness of the photocatalyst medium PET film layer is 0.20mm, and the adhesive amount of the EB curing layer is 15g / m 2 .

[0060] Step S5: Formaldehyde purification: place the door panel cured in step S3 in a purifier to purify formaldehyde. The purifier uses active calcium alginate gel (ACA) as a purifying agent. After purification, the final formaldehyde-purified EB-cured PET-finished cabinet door panel is obtained.

[0061] Example 4

[0062] Step S1 electron beam curing coating preparation: a certain amount of EB electron beam curing enhancement modifier fine powder is uniformly mixed and stirred in a mixed solution of acrylic emulsion and waterborne polyurethane emulsion at 50°C, and the substance particles are uniformly dispersed and stored for standby, wherein the main components of the EB electron beam curing enhancement modifier are nano silicon powder, aluminum oxide and boric acid or borax powder; during the preparation process, 3 parts of nano silicon powder fine powder, 2.8 parts of aluminum oxide fine powder and 3 parts of boric acid or borax powder are uniformly mixed and standby, and the above mixed fine powder is gradually added to the acrylic and waterborne polyurethane mixed emulsion and uniformly stirred.

[0063] Step S21 lignin purification: dissolve the lignin cake in sodium hydroxide solution and mix uniformly, during the process of lignin purification, the dissolution mass concentration of lignin cake and sodium hydroxide solution is 110g / L, the concentration of sodium hydroxide is 1mol / L, after mixing and stirring, centrifuge at 4500rpm for 5min to obtain supernatant suspension, adjust the pH of supernatant with dilute sulfuric acid, take the suspension and heat to 80°C for 2h, then vacuum filter and wash twice, finally dry at 50°C for 18h to obtain purified lignin powder;

[0064] Step S22 preparation of formaldehyde-free adhesive coating: dissolve 25 parts of the above purified lignin in a stirring container containing 1M sodium hydroxide, gradually add glyoxal under stirring and heating to constant temperature, the mass fraction of glyoxal is 75 parts, after mixing and stirring reaction, cool to obtain lignin glyoxal, mix the prepared lignin glyoxal with polymer 4,4 / -diphenyl methane diisocyanate pMDI to obtain formaldehyde-free adhesive, after mixing uniformly, obtain lignin glyoxal, wherein the mass fraction of lignin glyoxal is 45 parts, and the rest is pMDI.

[0065] Step S3 photocatalyst medium PET film layer preparation: melt the polyethylene terephthalate particles, i.e. PET fine powder particles, and extrude and cool to form a PET film layer by mixing with a proper amount of nano titanium dioxide; wherein the mass fraction of PET fine powder particles is 75 parts, and the mass fraction of nano titanium dioxide is 25 parts.

[0066] Step S4 cabinet door plate paint coating: the cabinet door plate is a multi-layer structure, and the coated multi-layer structure includes a bonding layer outside the plate core, a photocatalyst medium PET film layer, and an EB curing layer; the bonding layer uses the formaldehyde-free adhesive coating prepared in step S2, and the EB curing layer uses the electron beam curing coating prepared in step S1; during the door plate paint coating process, the multi-layer structure of the cabinet door plate is that the plate core 1 is sequentially coated with a bonding layer 2, a photocatalyst medium PET film layer 3, a bonding layer 2, and an EB curing layer 4; after the EB curing layer 4 is coated, the entire system is placed in a nitrogen N2 environment with a purity of more than 99.9% for electron beam curing; a hole 11 is formed at the top end where the plate core 1 is connected to the bonding layer 2, and a porous aluminum oxide 12 is arranged in the hole 11; the thickness of the plate core is 14 mm; the amount of adhesive applied to the bonding layer is 15 g / m 2 ; the thickness of the photocatalyst medium PET film layer is 0.19 mm; and the amount of adhesive applied to the EB curing layer is 16 g / m 2 .

[0067] Step S5 formaldehyde purification: the door plate cured in step S3 is placed in a purifier for formaldehyde purification; the purifier uses active calcium alginate gel ACA as a purifying agent; and after the purification is completed, the final formaldehyde-purified EB-cured PET-finished cabinet door plate is obtained.

[0068] Example 5

[0069] Step S1: Preparation of an electron beam curing coating: a certain amount of EB electron beam curing enhancer fine powder is uniformly mixed and stirred in a mixed solution of an acrylic emulsion and a water-based polyurethane emulsion at 50°C, and the substance particles are uniformly dispersed for storage; the main components of the EB electron beam curing enhancer include nano silicon powder, aluminum oxide, and boric acid or borax powder; during the preparation process, 4 parts of nano silicon powder, 2 parts of aluminum oxide, and 2.5 parts of boric acid or borax powder are uniformly mixed and reserved, and the above-mentioned mixed fine powder is gradually added to the acrylic and water-based polyurethane mixed emulsion and uniformly stirred.

[0070] Step S21: Lignin purification: lignin cake is dissolved in a sodium hydroxide solution and uniformly mixed by stirring; during the lignin purification process, the dissolution mass concentration of the lignin cake and the sodium hydroxide solution is 120 g / L, and the concentration of the sodium hydroxide is 1 mol / L; after the mixing and stirring, centrifugation is performed at 4500 rpm for 5 min to obtain a supernatant suspension; the supernatant is adjusted to a pH value with dilute sulfuric acid, and the suspension is heated to 85°C and kept at a constant temperature for 2 h, then vacuum filtered and washed twice, and finally dried at 50°C for 22 h to obtain a purified lignin powder;

[0071] Step S22: Preparation of formaldehyde-free adhesive coating: The purified lignin 27 parts is dissolved in a stirred container with 1M sodium hydroxide, and heated to a constant temperature. Then, gradually add glyoxal, the mass fraction of glyoxal is 73 parts, and mix and stir until the reaction is complete. After cooling, lignin glyoxal is obtained. Then, mix the obtained lignin glyoxal with polymeric 4,4 / -diphenyl methane diisocyanate pMDI to obtain a formaldehyde-free adhesive. After mixing uniformly, lignin glyoxal is obtained, wherein the mass fraction of lignin glyoxal is 50 parts, and the rest is pMDI.

[0072] Step S3: Preparation of photocatalyst medium PET film layer: melt the polyethylene terephthalate particles, i.e. PET fine powder particles, and extrude and cool to form a PET film layer by mixing in an appropriate amount of nano-titanium dioxide; wherein the mass fraction of PET fine powder particles is 80 parts, and the mass fraction of nano-titanium dioxide is 20 parts.

[0073] Step S4: Coating of cabinet door panel: the cabinet door panel has a multi-layer structure, including an adhesive layer outside the core, a photocatalyst medium PET film layer, and an EB curing layer. The adhesive layer uses the formaldehyde-free adhesive coating prepared in step S2, and the EB curing layer uses the electron beam curing coating prepared in step S1. During the coating process of the door panel, the multi-layer structure of the cabinet door panel is as follows: the core 1 is sequentially coated with an adhesive layer 2, a photocatalyst medium PET film layer 3, an adhesive layer 2, and an EB curing layer 4. After coating the EB curing layer 4, the entire system is placed in a nitrogen N2 environment with a purity of 99.9% or higher for electron beam curing. A hole 11 is provided at the top end of the connection between the core 1 and the adhesive layer 2, and a porous aluminum oxide 12 is arranged in the hole 11. The thickness of the core is 14 mm. The adhesive amount of the adhesive layer is 15 g / m 2 , the thickness of the photocatalyst medium PET film layer is 0.15 mm, and the adhesive amount of the EB curing layer is 15 g / m 2 .

[0074] Step S5: Formaldehyde purification: place the door panel cured in step S3 in a purifier to purify formaldehyde. Active calcium alginate gel ACA is used as a purifying agent in the purifier. After purification, the final formaldehyde-purified EB-cured PET-finished cabinet door panel is obtained.

[0075] Comparative Example 1

[0076] Unlike the examples, the cabinet door panel of this comparative example only has one layer of adhesive layer and PET film layer, and the PET film layer does not contain nano-titanium dioxide. The specific parameters are as follows:

[0077] Step S11 Lignin purification: The lignin cake is dissolved in a sodium hydroxide solution and mixed uniformly by stirring. During the lignin purification process, the lignin cake and the sodium hydroxide solution have a dissolution mass-volume concentration of 100 g / L, and the concentration of sodium hydroxide is 1 mol / L. After mixing and stirring, centrifugation is performed at 4500 rpm for 5 min to obtain a supernatant suspension. The supernatant is adjusted to a pH value using dilute sulfuric acid. The suspension is heated to 80°C and kept at a constant temperature for 2 h, then vacuum filtered and washed twice. Finally, the lignin powder is obtained by drying at 50°C for 24 h.

[0078] Step S12 Preparation of formaldehyde-free adhesive coating: 30 parts of the purified lignin is dissolved in a stirring container containing 1M sodium hydroxide. Ethylene glycol is gradually added by heating and stirring to a constant temperature. The mass fraction of ethylene glycol is 70 parts. After the reaction is completed and the mixture is cooled, lignin ethylene glycol is obtained. The prepared lignin ethylene glycol is mixed with polymeric 4,4 / -diphenyl methane diisocyanate (pMDI) to obtain a formaldehyde-free adhesive. After mixing uniformly, lignin ethylene glycol is obtained, wherein the mass fraction of lignin ethylene glycol is 48 parts, and the remaining part is pMDI.

[0079] Step S2 Coating of the adhesive layer on the cabinet door panel: The adhesive is coated on the substrate core 1, and the amount of adhesive applied is 14 g / m 2 The structure of the panel core 1 is the same as that of the above-mentioned embodiment.

[0080] Comparative Example 2

[0081] Unlike the embodiment, the comparative example is a conventional cabinet door panel on the market, which does not have an EB curing layer and a photocatalyst medium layer. The adhesive method and materials are also different from the embodiment. After the production of the cabinet door panel, it does not undergo secondary formaldehyde purification.

[0082] The cabinet door panels obtained in the above-mentioned embodiment and comparative example are subjected to hardness testing, surface wear resistance testing, yellowing resistance testing, and formaldehyde release amount grade evaluation, respectively.

[0083] The hardness test method is to use a specified 1H Mitsubishi test pencil, shave the pencil to expose the cylindrical lead core about 3mm in length (note that the core should not be damaged), hold the pencil at a 90-degree angle to the 400-grit sandpaper, and continuously circle the sandpaper to rub the end face of the pencil core until a sharp pencil core with a flat edge is obtained. Load the pencil on a special pencil hardness tester, apply a load of 500gf to the tip of the pencil, and contact the front end of the pencil core with the surface to be tested at an angle of 45°. Push the pencil forward at a speed of 0.5mm / s to 1mm / s for about 5m (if the sample length is less than 5m, test as much as possible on the sample surface), a total of 5 strokes, and rotate the pencil about 60° after each stroke. After the test is completed, use an eraser to remove the black pencil marks on the surface of the paint coating and compare them with the sample. The judgment standard is that the outer surface is not allowed to have indentations and scratches, and the indentations that can be restored within 24 hours are not considered a problem: a small scratch at the starting position (1 / 5 of the total length) is allowed.

[0084] The abrasion resistance test method is to use a special abrasion resistance tester and a special paper tape produced by the company, apply a load of 175g, and drive the paper tape to continuously rub the surface of the sample for a specified number of times. This test must be performed in a room with a relative humidity of 40% to 60% and a room temperature. The paper tape is stored in an environment with a relative humidity of 40% ± 5% and a temperature of 24°C ± 2°C. Place the paper tape in the paper supply wheel of the abrasion resistance tester, making sure that the paper tape is not reversed; the inner surface of the paper tape is used only once for rubbing, and if it is not used within 4 hours, it must be stored in a dry box; install and fix the sample, keeping it parallel to the horizontal plane, and make sure that the tested area of the sample is not suspended and that the inside is filled with a solid object; adjust the balance bar so that the weight on the surface of the paint coating is exactly 175g, and rub it 250 times. The judgment standard is to observe with a magnifying glass, and if the substrate is not exposed, it is considered to pass.

[0085] The yellowing resistance test method is to use a UV light source to irradiate the sample for 200 hours of continuous light, and the judgment level is divided into 1-5 levels. Level 1 is that the material has almost no color change under the specified test conditions, maintains the original color, and has very high yellowing resistance; level 2 is that the material has a slight color change during the test, but the change is slight and has little effect on the overall appearance; level 3 is that the material has a more obvious color change under the test conditions, but can still maintain a certain degree of appearance; level 4 is that the material has a significant color change after the test, which has a greater impact on the appearance, but can still be used; and level 5 is that the material has a very serious color change after the test, which seriously affects the appearance and usability, and almost cannot be used.

[0086] The formaldehyde emission level evaluation method is E1, E0, E NF , where E NF is the best, and the formaldehyde emission limit is ≤0.025mg / m 3 .

[0087] In addition, the anti-fingerprint performance of the cabinet door panel is observed visually, and the finger is pressed on the surface of the sample to ensure that the fingerprint is clear and visible. The fingerprint is carefully observed, and the number, shape and depth of the fingerprint are recorded. The score is based on the number of fingerprints on the surface of the sample, and the score range is 1-10 points. The higher the score, the worse the anti-fingerprint performance.

[0088]

[0089] For formaldehyde release, the formaldehyde release of examples 1-5 is <0.015 mg / m 3 , which meets the E NF standard, and the bonding strength of the example samples is sufficient for use in cabinet door panels; the test conditions of example 3 can obtain the EB cured PET decorative cabinet door panel with the best performance, and the other example samples all have excellent scratch hardness, anti-fingerprint, anti-yellowing, anti-fouling, wear-resistant, corrosion-resistant and formaldehyde purification performance, which can well meet the performance requirements of cabinet panels in daily life and the demand of people for home health and safety.

Claims

1. A formaldehyde-purified EB-cured PET veneered cabinet door panel, characterized by It comprises the following process steps: Step S1: Preparation of electron beam curing coating: a certain amount of EB electron beam curing enhancer fine powder is uniformly mixed and stirred in a mixed solution of acrylic emulsion and waterborne polyurethane emulsion at 40-60°C, and the substance particles are uniformly dispersed and stored for use; Step S2: Preparation of formaldehyde-free adhesive coating: S21: Lignin purification: dissolve the lignin cake in sodium hydroxide solution, mix uniformly, centrifuge the supernatant, adjust the pH of the supernatant with dilute sulfuric acid, then filter, wash and dry to obtain lignin powder; S22: Preparation of formaldehyde-free adhesive coating: dissolve the purified lignin in sodium hydroxide solution, add glyoxal after heating to constant temperature, cool after reaction to obtain lignin glyoxal, and mix the obtained lignin glyoxal with polymeric 4,4 / -diphenyl methane diisocyanate pMDI to obtain formaldehyde-free adhesive; Step S3: Preparation of photocatalyst medium PET film layer: melt the polyethylene terephthalate particles, i.e. PET fine powder particles, and extrude and cool to form a PET film layer with a proper amount of nano-titanium dioxide mixed in; Step S4: Coating of cabinet door panel: the cabinet door panel has a multi-layer structure, including an adhesive layer outside the panel core, a photocatalyst medium PET film layer and an EB curing layer; the adhesive layer uses the formaldehyde-free adhesive coating prepared in step S2, and the EB curing layer uses the electron beam curing coating prepared in step S1; Step S5: Formaldehyde purification: place the door panel cured in step S3 in a purifier to purify formaldehyde, and use active calcium alginate gel ACA as a purifying agent in the purifier to obtain the final formaldehyde-purified EB-cured PET finished cabinet door panel after purification.

2. The formaldehyde-purified EB-cured PET finished cabinet door panel according to claim 1, wherein: In step S1, the main components of the EB electron beam curing enhancer are nano-silicon powder, aluminum oxide and boric acid or borax powder; during production, 1-5 parts of nano-silicon powder, 1-3 parts of aluminum oxide powder and 1-5 parts of boric acid or borax powder are uniformly mixed and reserved, and the above mixed fine powder is gradually added to the acrylic and waterborne polyurethane mixed emulsion and stirred uniformly.

3. The formaldehyde-purified EB-cured PET finished cabinet door panel according to claim 1, wherein: In step S2, during the lignin purification process in S21, the lignin cake and the sodium hydroxide solution have a solubility mass concentration of 80-150 g / L, and the concentration of sodium hydroxide is 1 mol / L. After mixing and stirring, centrifugation is performed at 4000-4500 rpm for 5 min to obtain a supernatant suspension. The suspension is heated to 75-90°C and kept at constant temperature for 2 h, then vacuum filtered and washed twice, and finally dried at 50°C for 12-30 h to obtain purified lignin powder.

4. The formaldehyde-purified EB-cured PET finished cabinet door panel according to claim 3, wherein: In the step S2, the 15-40 parts of purified lignin powder are dissolved in a stirring container with 1M sodium hydroxide, and the glyoxal is gradually added while stirring, the mass fraction of glyoxal is 60-85 parts, and the lignin glyoxal is obtained after mixing uniformly; in the preparation of the formaldehyde-free adhesive, the lignin glyoxal is 40-60 parts, and the rest is pMDI.

5. The EB-cured PET veneered cabinet door panel according to claim 1, wherein: In the preparation process of the PET film layer in step S3, the mass fraction of terephthalic acid ethylene glycol particles, i.e. PET fine powder particles, is 75-95 parts, and the mass fraction of nano-titanium dioxide is 5-25 parts.

6. The EB-cured PET veneered cabinet door panel according to claim 1, wherein: In the coating process of the cabinet door panel in step S4, the multi-layer structure of the cabinet door panel is that the board core (1) is coated with the adhesive layer (2), the photocatalyst medium PET film layer (3), the adhesive layer (2) and the EB-cured layer (4) in sequence, and after the EB-cured layer (4) is coated, the whole system is placed in a nitrogen (N2) environment with a purity of more than 99.9% for electron beam curing.

7. The EB-cured PET veneered cabinet door panel according to claim 6, wherein: The top end of the board core (1) connected with the adhesive layer (2) is provided with a hole (11), and the hole (11) is provided with a porous alumina (12), and the thickness of the board core is 10-18 mm.

8. The EB-cured PET veneered cabinet door panel according to claim 6, wherein: The glueing layer has a glueing amount of 10-20 g / m 2 The photocatalyst medium PET film layer has a thickness of 0.10-0.30 mm, and the EB curing layer has a glueing amount of 10-20 g / m 2 .

9. The EB-cured PET veneered cabinet door panel according to claim 1, wherein: In the preparation of the active calcium alginate gel ACA, the wheat seedling leaves are ground and then extracted with a phosphate buffer solution, the solid-liquid ratio is 1:2, after extraction, an equal amount of 1% pre-cooled sodium alginate solution is added and mixed uniformly, and then the mixture is dropped into a 3% calcium chloride solution to form an active calcium alginate gel containing plant extracts.

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