Continuous flat pressed surface flame retardant particle board and method of making same

Abstract

Provided are a continuous flat pressing surface layer flame-retardant particle board and a preparation method thereof, which can reduce the burning growth rate index of the flame-retardant particle board and the influence of the flame retardant on the surface bonding strength of the particle board. The method comprises: simultaneously atomizing and applying, to raw material particles, 10-15% of the mass of the particles of a melamine modified urea-formaldehyde resin adhesive and 0.5-0.8% of the mass of the particles of a sodium hydroxide aqueous solution with a concentration of 0.4-0.6 mol / L to obtain pretreated surface layer particles, and blending the surface layer particles with a surface layer flame retardant PAP-Mg-Zn at a mass ratio of 100:15-17 to obtain flame-retardant surface layer particles; and laying the flame-retardant surface layer particles and core layer particles in a manner that the surface layer particles are in the upper and lower layers and the core layer particles are in the middle layer, and then continuously flat pressing the board blank at a hot pressing speed of 220-250 mm / s to obtain the continuous flat pressing surface layer flame-retardant particle board. The structural formula of PAP-Mg-Zn is as follows.

Description

Technical Field

[0001] This invention relates to the field of flame-retardant particleboard, specifically to continuously flat-pressed flame-retardant particleboard with a surface layer and its preparation method. Background Technology

[0002] Continuous flat-press production lines operate at high speeds and hot-pressing temperatures, placing stringent demands on flame retardants and the hot-pressing process. Currently, conventional continuous flat-press flame-retardant particleboard production processes suffer from poor uniformity between the flame retardant and surface particleboard due to the large amount of flame retardant added, resulting in a mismatch between physical, mechanical, and flammability properties. Furthermore, the poor interfacial compatibility between the flame retardant, adhesive, and particleboard affects the surface quality of the board during installation, leading to product quality issues. Summary of the Invention

[0003] In view of the above-mentioned research and development issues, the purpose of this invention is to provide a continuous flat-press surface flame-retardant particleboard and its preparation method, which can reduce the combustion growth rate index of the flame-retardant particleboard and reduce the influence of flame retardants on the bonding strength of the particleboard surface.

[0004] The first aspect relates to a method for preparing a continuously flat-pressed flame-retardant particleboard, comprising:

[0005] (1) Simultaneously atomize the raw material wood shavings with 10-15% by weight of melamine-modified urea-formaldehyde resin adhesive and 0.5-0.8% by weight of 0.4-0.6 mol / L sodium hydroxide aqueous solution to obtain pretreated surface wood shavings. The pretreated surface wood shavings are then blended with surface flame retardant PAP-Mg-Zn at a mass ratio of 100:15-17 to obtain flame-retardant surface wood shavings. The structural formula of PAP-Mg-Zn is as follows.

[0006]

[0007] (2) Apply melamine-modified urea-formaldehyde resin adhesive to the raw material wood shavings to obtain the core layer wood shavings;

[0008] (3) The flame-retardant surface wood chips and core wood chips are laid in such a way that the surface wood chips are in the upper and lower layers and the core wood chips are in the middle layer. After laying, the board blank is subjected to continuous flat pressing treatment, wherein the hot pressing temperature is 220-265℃, the hot pressing pressure is 2-2.5MPa, and the hot pressing speed is 220-250mm / s, thereby producing the continuous flat pressing surface flame-retardant wood chipboard.

[0009] The preparation of PAP-Mg-Zn is as follows:

[0010] Mix 50-70 wt% PAPEMP aqueous solution, 20-30 wt% magnesium chloride aqueous solution and 20-40 wt% zinc acetate solution in a ratio of 2:1:1 to 3, and stir at 300-500 r / min for 25-30 min at room temperature to obtain a mixed solution containing the complexation primary product.

[0011] A 10-12 wt% NaOH aqueous solution is slowly added to the mixed solution at a mass ratio of 1:1-2.5 to promote the complexation reaction and the precipitation of the complex. The precipitated complex is filtered and dried to obtain PAP-Mg-Zn.

[0012] Step (2) includes applying 10-15% of the weight of melamine-modified urea-formaldehyde resin adhesive to the raw material shavings through atomization.

[0013] In steps (1) and (2), the melamine-modified urea-formaldehyde resin adhesive has a solid content of 58%, a pH value of 8.5, a molecular weight of less than 300, and a melamine content of 9.5%.

[0014] The moisture content of the raw material wood shavings is 2.5-3.5%.

[0015] In step (3), the paving quality ratio of the surface layer to the core layer is 1:3.

[0016] The second aspect relates to a continuous flat-pressed flame-retardant particleboard prepared by the above-described preparation method.

[0017] According to the present invention, the burning growth rate index of flame-retardant particleboard can be reduced, and the influence of flame retardant on the bonding strength of particleboard surface can be reduced.

[0018] PAPEMP and metal ions both exhibit flame-retardant properties, forming a flame retardant through lone pair complexation. This allows the combustion process to overcome the energy required for the complexation bonds and consume heat, thus improving the flame-retardant effect. Furthermore, during combustion, the active metal sites catalyze the dehydration of P-OH groups and wood-based materials / melamine-modified urea-formaldehyde resin under high temperatures, promoting the formation of POC cross-linked structures and increasing the char yield.

[0019] The activity of the P-OH functional group is enhanced after being catalyzed by Mg / Zn metal ions, which in turn promotes the hydroxymethyl reaction between P-OH and the adhesive. This allows P-OH to participate in the curing and crosslinking process of melamine-modified urea-formaldehyde resin from polymers with a molecular weight of less than 300, thereby increasing the degree of crosslinking of the adhesive, reducing the negative impact of the addition of flame retardants on the adhesive curing process, and thus reducing the impact on mechanical properties.

[0020] According to the present invention, the flame retardant may undergo a reverse reaction after synthesis. After synthesis, it is only filtered and not washed. Furthermore, the pretreatment process further atomizes and adds an aqueous sodium hydroxide solution to ensure that the complexed flame retardant does not undergo a reverse reaction, thereby improving the stability of the flame retardant.

[0021] Furthermore, by controlling the appropriate amount of sodium hydroxide aqueous solution to allow it to penetrate to the surface of the wood shavings, the moisture content of the shavings is increased, and the activity of hydroxyl groups in the chemical structure of the wood shavings is enhanced, making them more similar in polarity to the phosphorus hydroxyl groups in the flame retardant. This, in turn, improves the interfacial compatibility between the flame retardant and the wood shavings. Simultaneously, the hot-pressing speed is controlled to ensure that the flame retardant does not undergo large-scale water absorption from the alkaline solution within a reasonable time, thus preventing agglomeration. Detailed Implementation

[0022] raw material:

[0023] 1. Melamine-modified urea-formaldehyde resin adhesive

[0024] Solid content 58%, pH value 8.5, molecular weight less than 300, melamine content 9.5%

[0025] Purchased from: Guangzhou Yuanye Industrial Co., Ltd., Model: DY103

[0026] 2. Bimetallic organic framework flame retardant PAP-Mg-Zn

[0027] Prepared by the following steps:

[0028] A mixture of 50wt%-70wt% PAPEMP aqueous solution, 20wt%-30wt% magnesium chloride aqueous solution, and 20wt%-40wt% zinc acetate solution in a ratio of 2:1:1-3 is stirred at room temperature at a speed of 300-500 r / min for 25-30 min to obtain a mixed solution containing the initial complex product. A 10-12wt% NaOH aqueous solution is slowly added to the mixed solution, wherein the mass ratio of the alkali solution to the mixed solution is 1:1-2.5, to promote the complexation reaction and the precipitation of the complex. The precipitated complex is filtered and dried in a forced-air drying oven at 60-70℃ to obtain the bimetallic organic framework flame retardant, the structural formula of which is as follows.

[0029]

[0030] Example 1:

[0031] 1. Preparation of surface flame retardant bimetallic organic framework flame retardant:

[0032] First, 100g of PAPEMP (polyaminopolyether methylenephosphonic acid) was dissolved in 100g of deionized water to prepare a 50wt% PAP solution; 100g of MgCl2 was dissolved in 400g of deionized water to prepare a 20wt% MgCl2 metal salt solution; 100g of zinc acetate was dissolved in 400g of deionized water to prepare a 20wt% zinc acetate solution; and 100g of NaOH was dissolved in 900g of deionized water to prepare a 10wt% alkaline solution. Then, the PAP solution, MgCl2 solution, and zinc acetate solution were mixed at a mass ratio of 2:1:1 and stirred at 25°C and 300 rpm for 30 min to obtain a mixed solution containing the initial complex product. Next, the alkaline solution was slowly added to the mixed solution (the mass ratio of alkaline solution to mixed solution was 1:1) to promote the complexation reaction and the precipitation of the complex. Finally, the precipitated complex was filtered out and dried in a 60°C forced-air drying oven for 24 hours to obtain the final bimetallic organic framework flame retardant PAP-Mg-Zn.

[0033] 2. Particleboard pretreatment and preparation of flame-retardant particleboard

[0034] The moisture content of dried eucalyptus shavings (30mm*2mm*0.14mm) was reduced to 2.5%. The shavings were placed in a spray nozzle and simultaneously atomized with 10% (by weight) of melamine-modified urea-formaldehyde resin adhesive and 0.5% (by weight) of a 0.5 mol / L sodium hydroxide aqueous solution to obtain pretreated surface shavings with a moisture content of 8.5%. These shavings were then blended with a surface flame retardant, PAP-Mg-Zn, at a concentration of 15% of the pretreated surface shavings' mass, to obtain flame-retardant surface shavings.

[0035] The moisture content of dried eucalyptus wood shavings (30mm*2mm*0.14mm) is reduced to 3.0%. The shavings are placed in a spray pipe and atomized with a spray gun to apply 7.5% of the shavings' mass of melamine-modified urea-formaldehyde resin adhesive to obtain the glued core layer shavings.

[0036] Next, the flame-retardant surface and core wood chips are laid using an air-jet flooring machine. First, the lower surface wood chips are laid, followed by the lower core wood chips, upper core wood chips, and upper surface wood chips in sequence, with a surface to core wood chip mass ratio of 1:3. Immediately after completion, the board is subjected to a continuous flat-pressing process at a hot-pressing temperature of 245℃, a hot-pressing pressure of 2.5MPa, and a hot-pressing speed of 250mm / s, thus producing an 18mm thick layered flame-retardant particleboard.

[0037] performance:

[0038] 1. Peak combustion growth rate index: 1.01 kW / m³ 2 . Compared to ordinary particleboard, it reduces by 30.3%.

[0039] 2. Surface bonding strength: 1.1 MPa.

[0040] Example 2:

[0041] 1. Preparation of surface flame retardant bimetallic organic framework flame retardant:

[0042] First, 100g of PAPEMP (polyaminopolyether methylenephosphonic acid) was dissolved in 66g of deionized water to prepare a 60wt% PAP solution; 100g of MgCl2 was dissolved in 233g of deionized water to prepare a 30wt% MgCl2 metal salt solution; 100g of zinc acetate was dissolved in 150g of deionized water to prepare a 40wt% zinc acetate solution; and 100g of NaOH was dissolved in 900g of deionized water to prepare a 10wt% alkaline solution. Then, the PAP solution, MgCl2 solution, and zinc acetate solution were mixed at a mass ratio of 2:1:3 and stirred at 500 rpm for 20 min at 22°C to obtain a mixed solution containing the initial complex product. Next, the alkaline solution was slowly added to the mixed solution (the mass ratio of alkaline solution to mixed solution was 1:2.5) to promote the complexation reaction and the precipitation of the complex. Finally, the precipitated complex was filtered out and dried in a 70°C forced-air drying oven for 30 hours to obtain the final bimetallic organic framework flame retardant PAP-Mg-Zn.

[0043] 2. Particleboard pretreatment and preparation of flame-retardant particleboard

[0044] The moisture content of dried poplar wood shavings (25mm*2.5mm*0.18mm) was reduced to 3.5%. The shavings were placed in a spray nozzle and simultaneously atomized with 15% melamine-modified urea-formaldehyde resin adhesive and 0.8% 0.5mol / L sodium hydroxide aqueous solution (by weight of the shavings) to obtain pretreated surface shavings with a moisture content of 8.3%. These shavings were then blended with a surface flame retardant, PAP-Mg-Zn, at a concentration of 17% of the pretreated surface shavings' weight, to obtain flame-retardant surface shavings.

[0045] The moisture content of dried poplar wood shavings (25mm*2.5mm*0.18mm) is reduced to 3.5%. The shavings are placed in a spray pipe and atomized by a spray gun to apply 7.5% of the shavings' mass of melamine-modified urea-formaldehyde resin adhesive to obtain the core layer shavings treated with adhesive.

[0046] Next, the flame-retardant surface layer and core layer wood chips are laid using an air-jet flooring machine. First, the bottom surface layer wood chips are laid, followed by the core layer (single layer) and then the top surface layer wood chips, with a surface layer to core layer mass ratio of 1:3. Immediately after completion, the board is subjected to a continuous flat-pressing process. The hot-pressing temperature is 245℃, the hot-pressing pressure is 2MPa, and the hot-pressing speed is 220mm / s, thus producing an 18mm thick layered flame-retardant particleboard.

[0047] performance:

[0048] 1. Peak combustion growth rate index: 0.97kW / m³ 2 .s, which is 33.1% lower than that of ordinary particleboard.

[0049] 2. Surface bonding strength: 0.97 MPa.

[0050] Comparative Example 1:

[0051] Except for the atomization treatment of the surface wood shavings in step 2, which did not involve the application of NaOH aqueous solution, the other steps were the same as in Example 1.

[0052] performance:

[0053] 1. Peak combustion growth rate index: 1.23 kW / m³ 2 .s, which is 15.2% lower than that of ordinary particleboard.

[0054] 2. Surface bonding strength: 0.40 MPa.

[0055] Comparative Example 2:

[0056] Except for the complex precipitated in step 1 being filtered and washed 5 times, the other steps are the same as in Example 1.

[0057] performance:

[0058] 1. Peak combustion growth rate index: 1.16 kW / m³ 2 .s, which is 19.6% lower than that of ordinary particleboard.

[0059] 2. Surface bonding strength: 0.69 MPa.

[0060] Comparative Example 3:

[0061] Except for step 2, where the surface wood shavings are treated with a NaOH aqueous solution at a ratio of 0.3% of the wood shavings mass, the other steps are the same as in Example 1.

[0062] performance:

[0063] 1. Peak combustion growth rate index: 1.05 kW / m³ 2 .Compared to ordinary particleboard, it reduces by 27.6%.

[0064] 2. Surface bonding strength: 0.54 MPa.

[0065] Comparative Example 4:

[0066] Except for step 1, where PAPEMP is not complexed with a metal element during flame retardant preparation, the other steps are the same as in Example 1. The specific preparation of the surface flame retardant is as follows:

[0067] A surface flame retardant was obtained by blending 100g PAPEMP, 50g MgCl2 aqueous solution and 50g zinc acetate.

[0068] performance:

[0069] 1. Peak combustion growth rate index: 1.41 kW / m³ 2 . s, which is 2.8% lower than that of ordinary particleboard.

[0070] 2. Surface bonding strength: 0.47 MPa

[0071] Comparative Example 5:

[0072] Except for the hot pressing speed of 200 mm / s in step 2, the other steps are the same as in Example 1.

[0073] performance:

[0074] 1. Peak combustion growth rate index: 1.18 kW / m³ 2 . Compared to ordinary particleboard, it reduces by 18.6%.

[0075] 2. Surface bonding strength: 0.59 MPa.

Claims

1. A method for preparing a continuously flat-pressed flame-retardant particleboard surface, Its features are, include: (1) Simultaneously atomize 10-15% by weight of melamine-modified urea-formaldehyde resin adhesive and 0.5-0.8% by weight of 0.4-0.6 mol / L sodium hydroxide aqueous solution to obtain pretreated surface shavings. Then, blend the pretreated surface shavings with surface flame retardant PAP-Mg-Zn at a mass ratio of 100:15-17 to obtain flame-retardant surface shavings. The structural formula of PAP-Mg-Zn is as follows: ， (2) Apply melamine-modified urea-formaldehyde resin adhesive to the raw material wood shavings to obtain the core layer wood shavings; (3) The flame-retardant surface layer shavings and core layer shavings are laid out with the surface layer shavings on the top and bottom layers and the core layer shavings in the middle layer. After laying, the board blank is subjected to continuous flat pressing treatment, wherein the hot pressing temperature is 220-265℃, the hot pressing pressure is 2-2.5MPa, and the hot pressing speed is 220-250mm / s, thereby producing the continuously flat-pressed flame-retardant surface shaving board. The preparation of PAP-Mg-Zn is as follows: Mix 50-70 wt% PAPEMP aqueous solution, 20-30 wt% magnesium chloride aqueous solution and 20-40 wt% zinc acetate solution in a ratio of 2:1:1~3, and stir at 300-500 r / min for 25-30 min at room temperature to obtain a mixed solution containing the complexation primary product. A 10-12 wt% NaOH aqueous solution was slowly added to the mixed solution at a mass ratio of 1:1-2.5 to promote the complexation reaction and the precipitation of the complex. The precipitated complex was filtered and dried to obtain PAP-Mg-Zn. In steps (1) and (2), the melamine-modified urea-formaldehyde resin adhesive has a solid content of 58%, a pH value of 8.5, a molecular weight of less than 300, and a melamine content of 9.5%.

2. The preparation method according to claim 1, wherein, Step (2) includes: Atomize the raw material wood shavings and apply 10-15% of the weight of the wood shavings with melamine-modified urea-formaldehyde resin adhesive.

3. The preparation method according to claim 1, wherein, The moisture content of the raw material wood shavings is 2.5-3.5%.

4. The preparation method according to claim 1, wherein, In step (3), the paving quality ratio of the surface layer to the core layer is 1:

3.

5. A continuous flat-pressed flame-retardant particleboard prepared by the preparation method of claim 1.

Images