CN112745603B

CN112745603B - Sulfonic biochar flame-retardant wood-plastic plate and production method thereof

Info

Publication number: CN112745603B
Application number: CN202110066550.3A
Authority: CN
Inventors: 向湘军; 袁利萍; 王杰超; 袁仕云; 范友华; 黄自知; 胡云楚; 盛灿; 汤连东; 王绿英; 刘晶; 胡德智
Original assignee: Hunan Hengxin New Building Materials Co ltd
Current assignee: Hunan Hengxin New Building Materials Co ltd
Priority date: 2021-01-19
Filing date: 2021-01-19
Publication date: 2022-09-02
Anticipated expiration: 2041-01-19
Also published as: CN112745603A; WO2022156287A1

Abstract

A sulfonic biochar flame-retardant wood-plastic plate and a production method thereof relate to the technical field of wood-plastic plates and comprise the following components in parts by weight: 20-30 parts of bamboo and wood fiber powder, 90-110 parts of heavy calcium carbonate, 70-90 parts of polyvinyl chloride resin powder, 9-15 parts of PBS resin, 8-12 parts of hollow ceramic microspheres, 8-12 parts of ethylene-vinyl acetate copolymer, 5.5-7.5 parts of sulfonated carbon, 4-5 parts of heat stabilizer, 5-6 parts of foaming regulator, 0.6-1.2 parts of foaming agent, 0.5-1 part of stearic acid and 0.5-1 part of PE wax. The invention can improve the flame-retardant effect of the wood-plastic plate and reduce the release speed and the release amount of smoke during combustion.

Description

Sulfonic biochar flame-retardant wood-plastic plate and production method thereof

Technical Field

The invention relates to the technical field of wood-plastic plates, in particular to a sulfonic biochar flame-retardant wood-plastic plate and a production method thereof.

Background

With the development of economy and social progress, the quality of life of people is continuously improved, the demands of wood and other forest products are increased day by day, the international import difficulty of the forest products is increased continuously, and the contradiction between supply and demand of wood is continuously increased. Aiming at the current situation of supply and demand, scholars at home and abroad carry out deep research, and the method for solving the contradiction between supply and demand of wood comprises the following steps: firstly, the existing wood resources are fully and efficiently utilized, and the utilization rate of the wood is improved; and secondly, substitute products of the wood products are searched, and the wood consumption is reduced.

The wood-plastic composite (WPC) is a novel green material formed by compounding wood fibers or plant fibers and thermoplastic polymers or other materials, and has excellent corrosion resistance, waterproof performance, thermal insulation performance, easy processing performance and the like. Different from the traditional artificial board, the WPC production process has no waste gas and waste water discharge, no release of harmful gases such as free formaldehyde and the like in the use process, can be recycled, has low raw material price, and can greatly relieve the supply of wood resources in China.

The existing wood-plastic composite material has the defects of short service life and poor high-temperature resistance, so that the flame-retardant effect is difficult to achieve by utilizing the wood-plastic plate, and moreover, as the common wood-plastic plate can quickly release more smoke during combustion, a large amount of smoke and toxic gas can be generated in a fire disaster, and the wood-plastic composite material becomes a main reason for causing casualties and hindering fire rescue.

Disclosure of Invention

The invention aims to provide a sulfonic biochar flame-retardant wood-plastic plate and a production method thereof, which can improve the flame-retardant effect of the wood-plastic plate and reduce the release speed and release amount of smoke during combustion.

In order to solve the technical problems, the invention adopts the following technical scheme: the sulfonic biochar flame-retardant wood-plastic plate comprises the following components in parts by weight: 20-30 parts of bamboo and wood fiber powder, 90-110 parts of heavy calcium carbonate, 70-90 parts of polyvinyl chloride resin powder, 9-15 parts of PBS resin, 8-12 parts of hollow ceramic microspheres, 8-12 parts of ethylene-vinyl acetate copolymer, 5.5-7.5 parts of sulfonated carbon, 4-5 parts of heat stabilizer, 5-6 parts of foaming regulator, 0.6-1.2 parts of foaming agent, 0.5-1 part of stearic acid and 0.5-1 part of PE wax.

Preferably, the bamboo and wood fiber powder is processed into a dry state.

In addition, the invention also provides a method for producing the sulfonic biochar flame-retardant wood-plastic plate, which comprises the following steps:

(1) the bamboo-wood fiber powder, the heavy calcium carbonate, the polyvinyl chloride resin powder, the PBS resin, the hollow ceramic microspheres, the ethylene-vinyl acetate copolymer, the sulfonated carbon, the heat stabilizer, the foaming regulator, the foaming agent, the stearic acid and the PE wax are mixed, stirred uniformly and plasticized according to the weight parts to obtain a uniformly mixed substance.

(2) And (2) adding the uniformly mixed material obtained in the step (1) into a screw extruder for extrusion molding.

(3) And (3) shaping the material extruded and molded in the step (2) and cooling to room temperature.

(4) And (4) cutting the material shaped and cooled in the step (3), and then performing matte film pasting treatment to obtain the sulfonic biochar flame-retardant wood-plastic board.

Preferably, the processing temperature in the screw extruder of step (2) is 170 to 180 ℃.

The invention has the beneficial effects that: the sulfonated carbon is used as a solid acid catalyst, and can catalyze wood or polymer to quickly form carbon in advance when encountering high temperature to form a compact carbon layer barrier, so that heat and oxygen can be efficiently isolated, a lower-layer base material is protected, and the flame-retardant and fireproof effects are achieved.

Particularly, the sulfonated carbon and the heavy calcium, resin and the like in the wood-plastic plate form a novel expansion flame-retardant system with three sources of acid source, gas source and carbon source for efficient flame retardance, and the excellent flame retardance and smoke suppression of the sulfonated carbon/wood-plastic plate system are caused by chemical reaction generated by interaction of components in the thermal decomposition process, so that the sulfonated carbon can promote CaCO ₃ CO released by decomposition ₂ And H ₂ O, and can rapidly promote the ethylene-vinyl acetate resin and the PBS resin to be cracked to generate end groupsBeing a product of a carboxylic acid, which may be reacted with Ca ²⁺ The ionic polymer is formed by reaction, the process of forming the Ca ionic polymer causes melt crosslinking, the crosslinking causes melt viscosity to increase, so that an expanded and porous unstable carbon layer formed in the initial stage of thermal decomposition is stabilized, meanwhile, the sulfonic acid abstracts chlorine from the PVC to generate carbonium ions, and the carbonium ions are crosslinked through Friedel-Crafts reaction to reduce the generation of volatile hydrocarbon, so that stable carbon is formed on the surface of the PVC.

Therefore, the sulfonated carbon promotes the polymer system to form carbon quickly, reduces high polymer fragments which can be burnt in gas phase, and reduces the heat on the surface of the high polymer; the carbon layer with low heat conduction quantity can reflect the energy incident on the surface of the high polymer, thereby protecting the lower layer material, delaying the decomposition of the high polymer and the volatilization of decomposition products, the physical structure of the thick foam carbon layer has good flame retardant property, and the smoke is inhibited while the heat release is reduced, thereby effectively reducing the release speed and the release quantity of the smoke during combustion.

Drawings

FIG. 1 is a rule of influence of sulfonated carbon addition on oxygen index of bamboo-wood fiber integrated boards in the embodiment of the invention;

FIG. 2 is a graph showing the thermogravimetric curves of bamboo and wood fiber integrated boards with different amounts of sulfonated carbon added in the examples under nitrogen atmosphere;

FIG. 3 is a graph of heat release rates of different bamboo-wood fiber integrated boards in the example;

FIG. 4 is a graph showing the total heat release of different bamboo-wood fiber integrated boards in the example;

FIG. 5 is a graph showing the total smoke release of different bamboo-wood fiber integrated boards in the example;

fig. 6 is a schematic diagram of a Mag ═ 100X standard electron micrograph of the wood-plastic panel after combustion in the example;

fig. 7 is a schematic diagram of the electron microscope photograph of the wood-plastic panel with Mag ═ 1.0KX standard after combustion in the example.

Detailed Description

In order to facilitate understanding of those skilled in the art, the present invention will be further described with reference to the following examples and drawings, which are not intended to limit the present invention.

Example 1

The sulfonic biochar flame-retardant wood-plastic plate comprises the following components in parts by weight: 20 parts of bamboo and wood fiber powder processed into a dry state, 90 parts of ground calcium carbonate, 70 parts of polyvinyl chloride resin powder, 9 parts of PBS resin, 8 parts of hollow ceramic microspheres, 8 parts of ethylene-vinyl acetate copolymer, 5.5 parts of sulfonated carbon, 4 parts of heat stabilizer, 5 parts of foaming regulator, 0.6 part of foaming agent, 0.5 part of stearic acid and 0.5 part of PE wax.

The production method comprises the following steps:

(1) mixing bamboo fiber powder, heavy calcium carbonate, polyvinyl chloride resin powder, PBS resin, hollow ceramic microspheres, ethylene-vinyl acetate copolymer, sulfonated carbon, a heat stabilizer, a foaming regulator, a foaming agent, stearic acid and PE wax according to the weight part ratio, uniformly stirring and plasticizing to obtain a uniformly mixed substance. Wherein, can adopt the slowly mode of mixing of bulky cold pot, can accomplish the even blending of 2 tons of raw materials once, can save more than 2000 kilowatts/day of electric energy than traditional hot pot blending.

(2) And (2) adding the uniformly mixed material obtained in the step (1) into a screw extruder for extrusion molding, wherein the processing temperature in the screw extruder is 170 ℃, preferably, co-extrusion of a die head and two bases can be adopted, namely, simultaneous extrusion molding of a main plate (powder material) and a side plate (particle material) is completed at one time, the co-extrusion mode can shorten the manufacturing period, and the extruded product has good integrity, high strength, is convenient for holding nails, and is easy to manufacture and install.

(3) And (3) shaping the material extruded and molded in the step (2) and cooling to room temperature, wherein vacuum suction, water circulation cooling and traction stretching shaping can be adopted, and cooling water in the shaping process is recovered and recycled.

(4) And (4) cutting the material shaped and cooled in the step (3), and then performing matte film pasting treatment to obtain the sulfonic biochar flame-retardant wood-plastic board. The whole process not only reduces energy consumption, but also saves human resources, and the produced sheet material has low formaldehyde emission and excellent mechanical property.

Example 2

The sulfonic biochar flame-retardant wood-plastic plate comprises the following components in parts by weight: 30 parts of bamboo and wood fiber powder, 110 parts of heavy calcium carbonate, 90 parts of polyvinyl chloride resin powder, 15 parts of PBS resin, 12 parts of hollow ceramic microspheres, 12 parts of ethylene-vinyl acetate copolymer, 7.5 parts of sulfonated carbon, 5 parts of heat stabilizer, 6 parts of foaming regulator, 1.2 parts of foaming agent, 1 part of stearic acid and 1 part of PE wax.

The production method comprises the following steps:

(1) mixing bamboo fiber powder, heavy calcium carbonate, polyvinyl chloride resin powder, PBS resin, hollow ceramic microspheres, ethylene-vinyl acetate copolymer, sulfonated carbon, a heat stabilizer, a foaming regulator, a foaming agent, stearic acid and PE wax according to the weight part ratio, uniformly stirring and plasticizing to obtain a uniformly mixed substance.

(2) And (2) adding the uniformly mixed material obtained in the step (1) into a screw extruder for extrusion molding, wherein the processing temperature in the screw extruder is 180 ℃.

Example 3

The sulfonic biochar flame-retardant wood-plastic plate comprises the following components in parts by weight: 25 parts of bamboo and wood fiber powder processed into a dry state, 100 parts of ground calcium carbonate, 80 parts of polyvinyl chloride resin powder, 12 parts of PBS resin, 10 parts of hollow ceramic microspheres, 10 parts of ethylene-vinyl acetate copolymer, 6.5 parts of sulfonated carbon, 4.5 parts of heat stabilizer, 5.5 parts of foaming regulator, 0.9 part of foaming agent, 0.8 part of stearic acid and 0.8 part of PE wax.

The production method comprises the following steps:

(2) And (2) adding the uniformly mixed substance obtained in the step (1) into a screw extruder for extrusion molding, wherein the processing temperature in the screw extruder is 174 ℃.

(4) And (4) cutting the material shaped and cooled in the step (3), and then performing matte film pasting treatment to obtain the sulfonic biochar flame-retardant wood-plastic plate.

The mechanism of the flame-retardant and smoke-suppressing function of the sulfonic biochar flame-retardant wood-plastic board in each embodiment is a chemical reaction generated by the interaction of components in the thermal decomposition process, and particularly, the addition of the sulfonated carbon can promote CaCO ₃ CO released by decomposition ₂ And H ₂ O, and can rapidly promote the cracking of ethylene-vinyl acetate resin and PBS resin to generate a product with a terminal group of carboxylic acid, and the product is mixed with Ca ²⁺ Reacting to form the ionic polymer. The following formulae are shown:

H ⁺ +CaCO ₃ →Ca ²⁺ +CO ₂ ↑+H ₂ O↑

PolymerCOOC ₂ H ₃ →PolymerCOOH+CH ₂ ＝CH ₂ ↑

PBS→PolymerCOOH+PolymerC ₄ H ₈ OH2 PolymerCOOH+CaCO ₃ →(PolymerCOO) ₂ Ca ²⁺ +CO ₂ ↑+H ₂ O↑

the contribution of these reactions is that at temperatures below 300 ℃, gaseous CO is produced which can be expanded and foamed by the molten system ₂ And H ₂ O, and these gases have the effect of self-extinguishing the flame. This means that the thermally insulating expanded carbon layer is formed at an earlier stage, meaning that the ignition time can be effectively increased, and a more heat-resistant stable carbon layer containing Ca compounds is formed. Secondly, the formation of Ca ionic polymer is a process which causes melt crosslinking, and the crosslinking causes melt viscosity to increase, thereby being beneficial to stabilizing the expanded porous carbon structure with compact surface layer formed at the initial stage of thermal decomposition. Furthermore, the abstraction of chlorine from PVC by sulfonic acids generates carbenium ions which crosslink by Friedel-Crafts reactions, reducing the generation of volatile hydrocarbonsTo form stable carbon on the surface of PVC. Therefore, the sulfonated carbon promotes the polymer system to form carbon quickly, reduces high polymer fragments which can be combusted in a gas phase, and simultaneously reduces the heat on the surface of the high polymer; the carbon layer with low heat conductivity can reflect the energy incident on the surface of the high polymer, thereby protecting the lower layer material and delaying the decomposition of the high polymer and the volatilization of the decomposition products. The physical structure of the thick foam carbon layer has good flame retardant property, and smoke is inhibited while heat release is reduced.

Biomass waste rich in cellulose, hemicellulose and lignin is subjected to carbonization condition control to form a polycyclic aromatic hydrocarbon structure, and sulfonated carbon is obtained through sulfonation modification. The sulfonated carbon is black particles, the shape of the sulfonated carbon is not obviously different from that before sulfonation, the density and the hardness are slightly improved, the adsorption performance is better than that of charcoal due to the successful construction of the sulfonic acid group on the carbon skeleton, and the sulfonated carbon shows high catalytic activity and good stability in acid catalytic reaction. In the combustion process of the polymer, the sulfonic acid group can catalyze hydroxyl compounds to dehydrate into ester and form carbon, and can also be heated to decompose to generate SO ₂ 、CO ₂ And H ₂ O, the burning of the base material is inhibited, and the heat release is reduced; and can effectively reduce the emission of smoke and CO. The sulfonated carbon is an environment-friendly flame retardant or flame retardant synergist.

Performance and testing

When the performance and the test of the sulfonic biochar flame-retardant wood-plastic board (sulfonated carbon/bamboo-wood fiber wood-plastic board) are carried out, the selected wood-plastic board can be one of the wood-plastic boards prepared in the embodiments 1 to 3, or any combination of the components in the invention content in the weight part ratio range, and is not limited specifically herein.

First, limiting oxygen index determination

The Limiting Oxygen Index (LOI) test was carried out in accordance with "determination of the burning behavior of plastics by oxygen index method" (GB/T2406.2-2009) and the sample size was 150 mm. times.5 mm.

According to the building interior decoration design fire protection code (GB50222-2017), the highest flame retardant grade of the house in the combustion performance grades of decoration materials of all parts in single-layer and multi-layer civil buildings is B1 grade, and the corresponding oxygen index is more than or equal to 32 percent. Fig. 1 shows the influence law of the addition of the sulfonated carbon on the oxygen index of the bamboo-wood fiber integrated board. From this, it is found that the limit oxygen index of the bamboo-wood fiber wood-plastic board without sulfonated carbon is 31.8, which is close to 32 of B1 grade. After 0.5 percent of sulfonated carbon is added, the limit oxygen index of the bamboo-wood fiber integrated board is 32.7, which exceeds the B1 grade requirement of GB 50222-2017. The limit oxygen index of the bamboo and wood fiber integrated board is increased along with the increase of the addition amount of the sulfonated carbon, when the addition amount of the sulfonated carbon is increased to 2.5%, the limit oxygen index is 36.1, the limit oxygen index is continuously increased to 3.0%, and the limit oxygen index is 36.0, which indicates that the influence of the continuous increase of the sulfonated carbon on the limit oxygen index is not obvious any more, and the reasonable addition amount of the sulfonated carbon is about 2.5%. The result shows that 2.5% of sulfonated carbon can be better matched with a novel expansion flame-retardant system formed by calcium carbonate, ethylene-vinyl acetate resin and PBS resin, and is favorable for better forming a heat-insulating and oxygen-isolating carbon layer to be adhered to the surface of the base material, thereby avoiding the further propagation of flame and leading the flame to be self-extinguished.

The method is characterized in that all factors in the process of forming the sulfonated carbon/bamboo-wood fiber wood-plastic board, namely mainboard extrusion temperature, extrusion pressure, extrusion time and sulfonated carbon addition percentage, are orthogonal test factors, a four-factor three-level orthogonal test is designed, and the investigation indexes are the bending strength and the limiting oxygen index of the wood-plastic board. The factor levels are shown in tables 1-1, the results of orthogonal experiments are shown in tables 1-2, and the visual analysis of the results is shown in tables 1-3.

TABLE 1-1 factor level table

TABLE 1-2 orthogonal experimental results for sulfonated carbon/bamboo wood fiber wood-plastic board molding

Table 1-3 visual analysis of results

As can be seen from the results of the orthogonal test of extrusion molding of the wood-plastic panel in tables 1-2, the bending strength of the wood-plastic panel is 18.8-20.9MPa, and the limiting oxygen index is 33.9-36.5%. From the results, it is understood that the influence of the addition amount of sulfonated carbon on the limiting oxygen index and the bending strength is the greatest, followed by the extrusion temperature and the extrusion pressure of the main plate, and finally the extrusion time.

From the results, the level combination of experiment 2 is A ₁ B ₂ C ₂ D ₂ Experiment 3 the horizontal combination is A ₁ B ₃ C ₃ D ₃ Test 6 horizontal combination of A ₂ B ₃ C ₁ D ₂ Has better bending strength and limited oxygen index.

And further performing single-factor optimization on the extrusion molding conditions of the wood-plastic plate on the basis of the orthogonal test. From the data in tables 1-4, the influence of the extrusion temperature of the main board on the bending strength of the wood-plastic board is reduced after being increased along with the increase of the temperature, and the optimal extrusion temperature is 174 ℃ in combination with the influence of the main board on the limiting oxygen index.

The extrusion temperature of the master plate (i.e., the processing temperature in the screw extruder in the above example) was selected to be 174 ℃, and the rule of the influence of the extrusion pressure on the buckling strength and the limiting oxygen index was examined. As can be seen from tables 1 to 5, the bending strength increases with increasing pressure, but the limiting oxygen index has a higher value when the pressure is 8.0 to 8.5 MPa. Thus 8.0MPa is a relatively suitable extrusion pressure.

The extrusion temperature of the main plate is determined to be 174 ℃, and the extrusion pressure is determined to be 8.0 MPa. While the bending strength and limiting oxygen index of the wood-plastic panel increase with time, it is appropriate to select the extrusion time of 60s (as shown in tables 1-6).

Tables 1-4 impact of mainboard extrusion temperature on flexural strength and limiting oxygen index of wood-plastic panel

Tables 1-5 Effect of mainboard extrusion pressure on Flex Strength and limiting oxygen index of Wood-Plastic Panel

Tables 1-6 impact of extrusion time on Flex Strength and limiting oxygen index of Wood-Plastic Panel

Second, thermogravimetric analysis

And testing the thermal degradation performance of the sulfonated carbon/bamboo-wood fiber wood-plastic plate by adopting a TGA-Q500 thermogravimetric analyzer. Weighing 8-12 mg of dry powder, and heating the powder from 40 ℃ to 800 ℃ at a heating rate of 10 ℃/min. The protective gas is high-purity nitrogen with the flow rate of 20 mL/min.

The thermal weight loss curves and data of the bamboo and wood fiber integrated boards with different addition amounts of sulfonated carbon under the nitrogen atmosphere are respectively shown in fig. 2 and table 2. The curve shows that the shape of the pyrolysis curve of the bamboo-wood fiber integrated board is not obviously changed by adding the sulfonated carbon, but with the increase of the sulfonated carbon, the degradation rate of the bamboo-wood fiber integrated board is slowed down, the combustion residues are improved, and particularly in an upper temperature region above 500 ℃, the thermal stability of the residues is obviously increased.

TABLE 2 thermogravimetric data of different bamboo-wood fiber integrated boards

Temperature T at which all samples degraded by 5% _5％ T at which the difference is not great but the sample degrades by 50% _50％ Is significantly different, S-0.0% without sulfonated carbon added, T _50％ Is 734.2 ℃ and T increases with sulfonated carbon _50％ The increase is 771.3 ℃ for S-2.5%, which is 37.1 ℃ higher than that for S-0.0%. As can be seen from the degradation residues corresponding to 400 ℃, 600 ℃ and 800 ℃, the mass percentages of the S-0.0 percent residues without sulfonated carbon are 74.07 percent, 60.39 percent and 31.46 percent respectively; adding 0.5% of S-0.5% of sample, respectively comparing the mass percentages of the residuesThe S-0.0% is increased by 2.21%, 3.10% and 4.11%; with the increase of sulfonated carbon, degradation residues at high temperature are more and more, when 2.5% is added, the mass percentages of the residues of the sample S-2.5% at 400 ℃, 600 ℃ and 800 ℃ are 77.30%, 68.48% and 45.66%, respectively, and are correspondingly increased by 3.23%, 8.09% and 14.2% compared with the sample S-0.0%, and experimental results show that the addition of the sulfonated carbon rapidly improves the thermal stability of the sample at the high temperature (400-800 ℃), which is that the sulfonated carbon catalyzes calcium carbonate, ethylene-vinyl acetate resin and PBS resin systems to be heated to form a better carbon layer barrier, so that the sulfonated carbon can efficiently insulate heat and oxygen and protect a lower substrate.

Third, evaluation of Combustion Performance

According to ISO5660-1 standard, the combustion performance of the sulfonated carbon/bamboo-wood fiber wood-plastic plate is measured by adopting a British FTT cone calorimeter. The test piece size is 100mm × 100mm × 10mm (length × width × thickness). According to ISO5660-1-2002 standard, all surfaces of CONE sample of CONE calorimeter except heated surface are wrapped by aluminum foil paper, and placed in stainless steel sample holder, heat transfer is blocked at bottom of aluminum foil, and the volume is 50 kW.m ^-2 When the sample is subjected to a systematic research test under the heat radiation power, the surface temperature of the material is about 760 ℃.

The heat release rate HRR is the most important parameter for representing the fire intensity, and refers to the heat release rate per unit area when the material is burnt under the preset radiation intensity. The larger the HRR or PHRR is, the more heat is fed back by the combustion of the material per unit area in unit time, which results in the accelerated pyrolysis speed of the material, the increased output of volatile combustible gas and the accelerated propagation speed of fire. Therefore, the greater the HRR or PHRR, the greater the risk of the material in fire. Total Heat Release (THR) refers to the combination of Heat released from material ignition to fire extinguishing under a preset Heat radiation intensity, where THR ═ HRRdt is ═ jhrrdt, and its unit is MJ/m ² . The greater the THR, the more heat the material burns and the greater the hazard it poses. HRR and THR are combined, so that the combustion performance of the material can be objectively and comprehensively evaluated.

CONE experimental data of different bamboo-wood fiber integrated boards are listed in the table 3-1, and the data in FIGS. 3 and 4 are respectively different bamboo-wood fibersThe heat release rate curve and the total heat release profile of the integrated plate. S-0.0% sample without sulfonated carbon, ignition time TTI (time to ignition) is 30S, flame extinction time FET (flame extinction time)317S, and flame combustion time 287S; with the addition of sulfonated carbon, the ignition time of the sample increased and the extinguishing time advanced, wherein the TTI of the sample S-2.0% and S-2.5% was longest and 35S, the FET was 190S at the earliest and the flaming combustion time was 155S, which reduced the open flame combustion by 132S compared to S-0.0%. It can be seen from the heat release data of the CONE experiment that the addition of sulfonated carbon can effectively reduce the heat release. S-2.5% of peak value PHRR of maximum heat release rate than S-0.0% of 168.3kW/m ² The reduction is 16.7 percent, the average heat release rate MHRR and the effective combustion EHC are 70.30kW/m respectively ² 11.30MJ/kg, 95.30kW/m which is greater than S-0.0% ² Respectively reduce by 25.00kW/m ² 2.79MJ/kg, 26.2%, 19.8%; s-2.5% Total Heat Release THR 19.24MJ/m ² THR38.13MJ/m at a ratio S-0.0% ² The reduction is 49.5%. As can be seen from the heat release rate curves and the total heat release curves of different bamboo-wood fiber integrated boards in fig. 3 and 4, the addition of the sulfonated carbon significantly reduces the heat release rate and the total heat release, and particularly, the curve of the sample S-2.5% is most significant and is located below the curves of the other samples. The fire spread index (FGI) is the Peak Heat Release Rate (PHRR) and time to peak (t) _PHRR ) The ratio of (a) to (b). The larger the FGI, the shorter the time it takes to reach a higher peak heat release rate, and the greater the risk of fire. As is clear from Table 3-1, FGI at S-0.0% was 4.04kw/s.m ² With increasing sulfonated carbon, FGI decreases in turn, S-2.5% FGI1.02kw/s.m ² Less than one-fourth of the S-0.0% FGI. The addition of the sulfonated carbon can effectively inhibit the heat release of the bamboo-wood fiber wood-plastic plate, reduce the flame propagation and reduce the fire hazard.

TABLE 3-1 Cone calorimetric data of different bamboo-wood fiber integrated boards

The smoke and toxic gas in fire are the cause of peopleThe main cause of casualties. The toxic gas causes suffocation of people, the smoke reduces the visibility in a fire scene, prevents fire fighters from entering the fire scene for rescue, and makes the people in the fire scene difficult to evacuate and escape. According to statistics, 70-80% of the fire death population is caused by smoke and toxic gas suffocation. Thus, smoke and toxic gases are important factors in causing casualties in a fire. The CONE smoke data of different bamboo-wood fiber integrated boards are shown in the table 3-2, and the total smoke release curve is shown in the figure 5. As can be seen from Table 3-2, the S-0.0% smoke release rate SPR was as high as 1381.8m because of the large amount of smoke released from the PVC during the combustion of the raw materials ² (s) total smoke emission TSP12.29m ² /m ² Is the highest of all samples. The addition of sulfonated carbon can rapidly reduce the smoke release rate and the total smoke release amount, and the addition of 1.5 percent reduces the SPR to 689.2m ² S, which is reduced by more than half compared with S-0.0%. The addition of the sulfonated carbon further reduces SPR and TSP, and S-2.5 percent SPR is reduced to 486.4m ² S, only 35.2% of S-0.0%; TSP of 4.99m ² /m ² Is reduced by 7.3m compared with S-0.0% ² /m ² About 59.4%. CO is the most main factor causing people suffocation and poisoning in fire, the addition of the sulfonated carbon can effectively reduce the yield of carbon monoxide, and the addition amount of 2.5 percent reduces the yield of carbon monoxide from 45.5g/kg to 21.4g/kg and reduces the yield of carbon monoxide by 53.0 percent. The reduction of CO is mainly the catalytic carbonization of the sulfonated carbon on a bamboo-wood fiber system except the adsorption of the porous structure of the sulfonated carbon on smoke, the carbonization speed and the excellent carbonization quality of the sulfonated carbon quickly ensure that a sample under a carbon layer is efficiently protected, the flame is more quickly extinguished, and the combustion time is shortened.

TABLE 3-2 Cone calorimetric data of different bamboo-wood fiber integrated boards

Shape analysis of residues of sulfonated carbon/bamboo-wood fiber wood-plastic plate

The appearance of the sulfonated carbon/bamboo-wood fiber wood-plastic plate after combustion is observed by adopting a Quanta 450 type environmental scanning electron microscope of FEI company. Before testing, the surface of the test piece is sprayed with gold.

As shown in FIG. 6, it can be seen from the electron microscope photograph of the bamboo-wood fiber integrated board that the S-0.0% carbon residue without sulfonated carbon is large in holes and varied in size, and the holes are deep, and the surface of the carbon residue is powdery and is not connected into a whole. After the sulfonated carbon is added, the surface change of the sample carbon residue is obvious, S-0.5 percent of holes are reduced, but individual holes are still deeper; with the increase of the sulfonated carbon, the holes of S-1.0%, S-1.5%, S-2.0% and S-2.5% are gradually reduced, the uniformity of the holes is increased, and the integrity and the compactness of the carbon layer are better and better. As further shown in FIG. 7, the addition of sulfonated carbon to 1.0KX magnification carbon residue (S-0.0% and S-2.5%) changed the S-0.0% of a large amount of brittle carbon layer, which facilitated the formation of larger carbon pieces in the sample and continued the entire carbon layer into a dense whole with very few cracks. The solid carbon layer structure becomes a barrier for protecting the lower layer material, can efficiently isolate heat and oxygen, effectively inhibits the lower layer material from burning, and reduces the generation of heat and smoke.

The sulfonic biochar flame-retardant wood-plastic board provided by the embodiment meets the requirements of T/CADBM3-2018 bamboo-wood fiber integrated wallboard, GB18580-2017 formaldehyde emission in artificial boards for interior decoration materials and products thereof, and HNCCXZ131-2020 thin rules for quality supervision and sampling inspection implementation of decorative boards in Hunan province; the flame retardant property reaches the requirement of the grade B1 in the classification of combustion properties of building materials and products (GB 8624 and 2012). The sulfonated carbon/bamboo-wood fiber wood-plastic plate (namely the sulfonic biochar flame-retardant wood-plastic plate) product and the preparation process thereof are green and environment-friendly, and are ideal materials for people's green home.

From the demand of wood in China, the contradiction between supply and demand of wood is sharp, and the demand of value-added development technology on wood residues is huge. From the demands of building materials such as home furnishing and the like, the wood-plastic composite material has the performance advantages of being capable of being planed, sawed, nailed, drilled, soaked, not swelled, dried, not cracked, mothproof, corrosion resistant, free of formaldehyde, non-toxic and tasteless, can be recycled, is a real environment-friendly green material, and has a huge application prospect in various fields. The market demand for green WPC for green production will be greater and greater.

The sulfonated carbon/bamboo-wood fiber wood-plastic plate product has good functionality and market application prospect, the production technology can be completely upgraded on the traditional wood-plastic plate production line, and compared with the traditional wood-plastic plate, the sulfonated carbon/bamboo-wood fiber wood-plastic plate product has the functional advantages of environmental protection, flame retardance, light weight, high strength and the like.

The above embodiments are preferred implementations of the present invention, and the present invention can be implemented in other ways without departing from the spirit of the present invention.

Some of the drawings and descriptions of the present invention have been simplified to facilitate the understanding of the improvements over the prior art by those skilled in the art, and some other elements have been omitted from this document for the sake of clarity, and it should be appreciated by those skilled in the art that such omitted elements may also constitute the subject matter of the present invention.

Claims

1. The sulfonic biochar flame-retardant wood-plastic plate is characterized by comprising the following components in parts by weight: 20-30 parts of bamboo and wood fiber powder, 90-110 parts of heavy calcium carbonate, 70-90 parts of polyvinyl chloride resin powder, 9-15 parts of PBS resin, 8-12 parts of hollow ceramic microspheres, 8-12 parts of ethylene-vinyl acetate copolymer, 5.5-7.5 parts of sulfonated carbon, 4-5 parts of heat stabilizer, 5-6 parts of foaming regulator, 0.6-1.2 parts of foaming agent, 0.5-1 part of stearic acid and 0.5-1 part of PE wax;

the method for producing the sulfonic biochar flame-retardant wood-plastic plate comprises the following steps:

(1) mixing bamboo fiber powder, heavy calcium carbonate, polyvinyl chloride resin powder, PBS resin, hollow ceramic microspheres, ethylene-vinyl acetate copolymer, sulfonated carbon, a heat stabilizer, a foaming regulator, a foaming agent, stearic acid and PE wax according to the weight part ratio, uniformly stirring and plasticizing to obtain a uniformly mixed substance;

(2) adding the uniformly mixed material obtained in the step (1) into a screw extruder for extrusion molding, wherein the processing temperature in the screw extruder is 174 ℃;

(3) shaping the material extruded and molded in the step (2) and cooling to room temperature;

2. The sulfonic biochar flame-retardant wood-plastic plate as claimed in claim 1, characterized in that: the bamboo-wood fiber powder is processed into dry bamboo-wood fiber powder.