WO2022156287A1

WO2022156287A1 - Sulfo group-containing biochar flame-retardant wood-plastic board, and production method thereof

Info

Publication number: WO2022156287A1
Application number: PCT/CN2021/125580
Authority: WO
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: 湖南恒信新型建材有限公司
Priority date: 2021-01-19
Filing date: 2021-10-22
Publication date: 2022-07-28
Also published as: CN112745603B; CN112745603A

Abstract

A sulfo group-containing biochar flame-retardant wood-plastic board, and a production method thereof, relating to the technical field of wood-plastic boards and comprising the following components in parts by weight: 20-30 parts of bamboo 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 microbeads, 8-12 parts of ethylene-vinyl acetate copolymer, 5.5-7.5 parts of sulfonated carbon, 4-5 parts of a heat stabilizer, 5-6 parts of a foaming regulator, 0.6-1.2 parts of a foaming agent, 0.5-1 part of stearic acid and 0.5-1 part of PE wax. The present disclosure can improve the flame-retardant effect of the wood-plastic board and reduce the speed and amount of smoky gas released during combustion.

Description

A kind of sulfonic acid-based biochar fire-retardant wood-plastic board and production method thereof

technical field

The present disclosure relates to the technical field of wood-plastic panels, in particular to a sulfonic acid-based biochar fire-retardant wood-plastic panel and a production method thereof.

Background technique

With economic development and social progress, people's quality of life continues to improve, the demand for timber and other forest products is increasing, and the difficulty of international import of forest products is increasing, so the contradiction between supply and demand of timber continues unabated. In response to the current situation of supply and demand, scholars at home and abroad have conducted in-depth research to solve the contradiction between wood supply and demand: one is to make full and efficient use of existing wood resources to improve the utilization rate of wood; the other is to find alternative products for wood products to reduce wood consumption.

Wood-plastic composite (WPC) is a new type of green material which is composed of wood fiber or plant fiber and thermoplastic polymer or other materials. It has excellent anti-corrosion performance, waterproof performance, thermal insulation performance and easy processing performance. Different from traditional wood-based panels, WPC production process has no waste gas, waste water discharge, no free formaldehyde and other harmful gases are released during use, can be recycled, and the raw materials are cheap, which can greatly ease the supply of wood resources in my country.

The existing wood-plastic composite materials have a short service life and low high temperature resistance, so it is difficult to achieve the effect of flame retardant when used in wood-plastic panels. Not only that, because ordinary wood-plastic panels will be released quickly when burning. More smoke, which leads to a large amount of smoke and poisonous gas in the fire, becomes the main cause of casualties and hindering fire rescue.

SUMMARY OF THE INVENTION

The purpose of the present disclosure is to provide a sulfonic acid-based biochar flame-retardant wood-plastic board and a production method thereof, so as to improve the flame-retardant effect of the wood-plastic board, and reduce the release speed and release amount of smoke during combustion.

In order to solve the above-mentioned technical problems, the present disclosure adopts the following technical solutions: a sulfonic acid-based biochar fire-retardant wood-plastic board, comprising the following components in parts by weight: 20-30 parts of bamboo and wood fiber powder, 90 parts of heavy calcium carbonate -110 parts, polyvinyl chloride resin powder 70-90 parts, PBS resin 9-15 parts, hollow ceramic microbeads 8-12 parts, ethylene-vinyl acetate copolymer 8-12 parts, sulfonated carbon 5.5-7.5 parts, heat 4-5 parts of stabilizer, 5-6 parts of foaming regulator, 0.6-1.2 part 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 present disclosure also provides a method for producing the above-mentioned sulfonic acid-based biochar fire-retardant wood-plastic board, comprising the following steps:

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

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

(3) The material extruded in step (2) is shaped and cooled to room temperature.

(4) Cutting the shaped and cooled material in step (3), and then carrying out a matte filming treatment to obtain a sulfonic acid-based biochar fire-retardant wood-plastic board.

Preferably, the processing temperature in the screw extruder of step (2) is 170-180°C.

The beneficial effects of the present disclosure are as follows: sulfonated carbon, as a solid acid catalyst, can catalyze wood or polymer to rapidly form carbon in advance when encountering high temperature, form a dense carbon layer barrier, can efficiently isolate heat and oxygen, and protect the underlying substrate, So as to play the role of fire retardant.

Specifically, the sulfonated carbon and the heavy calcium and resin in the wood-plastic board constitute a new type of intumescent flame-retardant system with "acid source, gas source, and carbon source" synergistically high-efficiency flame retardant. Sulfonated carbon/wood-plastic board The excellent flame retardant and smoke suppression performance of the system is due to the chemical reaction of the components interacting during the thermal decomposition process. The sulfonated carbon can not only promote the decomposition of CaCO ₃ to release the gases CO ₂ and H ₂ O, but also rapidly promote the ethylene-vinyl acetate resin. , PBS resin is cracked to produce a product whose end group is carboxylic acid, which can react with Ca ²⁺ to form an ionic polymer. The process of forming Ca ionic polymer leads to melt crosslinking, and crosslinking leads to an increase in melt viscosity, thereby It is beneficial to stabilize the expanded porous unstable carbon layer formed in the early stage of thermal decomposition, while the sulfonic acid abstracts chlorine from PVC to generate carbocations, and the carbocations are cross-linked through the Friedel-Crafts reaction to reduce volatile hydrocarbons. The formation of stable carbon on the surface of PVC.

Therefore, the sulfonated carbon promotes the rapid carbonization of the polymer system, reduces the polymer fragments that can be combusted in the gas phase, and also reduces the heat on the surface of the polymer; the carbon layer with low thermal conductivity can make the incident polymer surface The energy is reflected out, thus protecting the underlying material, 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 performance. In order to suppress, it can effectively reduce the release speed and release amount of flue gas during combustion.

Description of drawings

Fig. 1 is the influence rule of sulfonated carbon addition on the oxygen index of bamboo and wood fiber integrated boards in the embodiment of the present disclosure;

Fig. 2 is the thermogravimetric curve diagram of the bamboo-wood fiber integrated board of different addition amounts of sulfonated carbon in the embodiment under nitrogen atmosphere;

Fig. 3 is the heat release rate curve diagram of different bamboo and wood fiber integrated boards in the embodiment;

Fig. 4 is the total heat release curve diagram of different bamboo and wood fiber integrated boards in the embodiment;

Fig. 5 is the total smoke emission curve diagram of different bamboo and wood fiber integrated boards in the embodiment;

Fig. 6 is the Mag=100X specification electron microscope photograph schematic diagram after the wood-plastic board is burned in the embodiment;

FIG. 7 is a schematic diagram of an electron microscope photograph of the Mag=1.0KX specification after the wood-plastic board is burned in the embodiment.

Detailed ways

In order to facilitate the understanding of those skilled in the art, the present disclosure will be further described below with reference to the embodiments and the accompanying drawings, and the contents mentioned in the embodiments are not intended to limit the present disclosure.

Example 1

A sulfonic acid-based biochar fire-retardant wood-plastic board, comprising the following components in parts by weight: 20 parts of bamboo and wood fiber powder processed into a dry state, 90 parts of heavy calcium carbonate, and 70 parts of polyvinyl chloride resin powder, 9 parts of PBS resin, 8 parts of hollow ceramic beads, 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 parts of foaming agent, 0.5 parts of stearic acid parts, PE wax 0.5 parts.

production method:

(1) Combine bamboo and wood fiber powder, heavy calcium carbonate, polyvinyl chloride resin powder, PBS resin, hollow ceramic microbeads, ethylene vinyl acetate copolymer, sulfonated carbon, heat stabilizer, foaming regulator, foaming agent , stearic acid and PE wax are mixed and stirred uniformly and plasticized according to the above-mentioned proportion by weight to obtain a uniform mixture. Among them, the method of slow mixing in a large volume of cold pot can be used to complete the uniform blending of 2 tons of raw materials at one time, which can save more than 2,000 kilowatts/day of electricity compared with traditional hot pot blending.

(2) adding the mixture obtained in the step (1) into a screw extruder for extrusion molding, wherein the processing temperature in the screw extruder is 170 ° C, and preferably, one die and two The co-extrusion of the base means that the main board (powder material) and the side board (granular material) are extruded at the same time. The co-extrusion mode can shorten the production cycle, and the extruded product has good integrity, high strength, easy to hold nails, and Make install.

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

(4) cutting the material after shaping and cooling in step (3), and then carrying out matte filming treatment to obtain sulfonic acid-based biochar fire-retardant wood-plastic board. The whole process not only reduces energy consumption, but also saves human resources. The produced sheet has low formaldehyde emission and excellent mechanical properties.

Example 2

A sulfonic acid-based biochar fire-retardant wood-plastic board, comprising the following components in parts by weight: 30 parts of bamboo and wood fiber powder processed into a dry state, 110 parts of heavy calcium carbonate, and 90 parts of polyvinyl chloride resin powder, 15 parts of PBS resin, 12 parts of hollow ceramic beads, 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 parts, PE wax 1 part.

production method:

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

(2) adding the mixed product obtained in step (1) into a screw extruder for extrusion molding, wherein the processing temperature in the screw extruder is 180°C.

(3) The material extruded in step (2) is shaped and cooled to room temperature.

Example 3

A sulfonic acid-based biochar fire-retardant wood-plastic board, comprising the following components in parts by weight: 25 parts of bamboo and wood fiber powder processed into a dry state, 100 parts of heavy calcium carbonate, 80 parts of polyvinyl chloride resin powder, 12 parts of PBS resin, 10 parts of hollow ceramic beads, 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 parts of foaming agent, 0.8 parts of stearic acid parts, PE wax 0.8 parts.

production method:

(2) The mixed product obtained in step (1) was added to a screw extruder for extrusion molding, wherein the processing temperature in the screw extruder was 174°C.

(3) The material extruded in step (2) is shaped and cooled to room temperature.

The mechanism of flame retardant and smoke suppression of the sulfonic acid-based biochar flame retardant wood-plastic board in the above embodiments lies in the chemical reaction of the interaction of components during the thermal decomposition process. Specifically, the addition _of sulfonated carbon can not only promote the CaCO The decomposition releases CO ₂ and H ₂ O, and can rapidly promote the cracking of ethylene-vinyl acetate resin and PBS resin to produce a product whose end group is carboxylic acid, which reacts with Ca ²⁺ to form an ionic polymer. Enter the following formulas:

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↑

One of the contributions of these reactions is that at a temperature below 300 °C, the gases CO ₂ and H ₂ O are generated for the expansion and foaming of the molten system, and these gases have the effect of self-extinguishing the flame. This means that the thermally intumescent carbon layer is formed at an earlier stage, which means that the ignition time can be effectively increased and a more heat-resistant stable carbon layer containing the Ca compound can be formed. Secondly, the formation of Ca ion polymer is a process that leads to melt cross-linking. Cross-linking leads to an increase in melt viscosity, which is beneficial to stabilize the expanded porous and dense surface carbon structure formed in the early stage of thermal decomposition. In addition, sulfonic acid abstracts chlorine from PVC to generate carbocations, and carbocations are cross-linked through Friedel-Crafts reaction, which reduces the generation of volatile hydrocarbons and forms stable carbon on the surface of PVC. Therefore, the sulfonated carbon promotes the rapid carbonization of the polymer system, reduces the polymer fragments that can be burned in the gas phase, and reduces the heat on the surface of the polymer; the carbon layer with low thermal conductivity can reflect the energy incident on the surface of the polymer. , thus protecting the underlying material, delaying the decomposition of the polymer and the volatilization of the decomposition products. The physical structure of the thick foam carbon layer has good flame retardant properties, heat release is reduced, and smoke is also suppressed.

Biomass wastes rich in cellulose, hemicellulose and lignin, control carbonization conditions to form polycyclic aromatic hydrocarbon structures, and obtain sulfonated carbon through sulfonation modification. The sulfonated carbon is black particles, the shape is not significantly different from that before sulfonation, and the density and hardness are slightly increased. Due to the successful construction of sulfonic acid groups on the carbon skeleton, the adsorption performance is better than that of charcoal, and both perform in acid-catalyzed reactions. high catalytic activity and good stability. In the process of polymer combustion, the sulfonic acid group can catalyze the dehydration of hydroxyl compounds into ester and carbon, and can also be thermally decomposed to generate SO ₂ , CO ₂ and H ₂ O to inhibit the combustion of the substrate and reduce heat release; Reduce smoke and CO emissions. It can be seen that sulfonated carbon is an environmentally friendly flame retardant or flame retardant synergist.

Performance and Testing

In the performance and test of the sulfonic acid-based biochar flame-retardant wood-plastic board (sulfonated carbon/bamboo-wood fiber wood-plastic board), the selected wood-plastic board can be from one of the ones prepared in Examples 1-3, It can also be any combination of the components in the content of the invention in the weight ratio ratio range, which is not specifically limited here.

1. Determination of Limiting Oxygen Index

The limiting oxygen index (LOI) test was carried out with reference to "Determination of Combustion Behavior by Oxygen Index Method for Plastics" (GB/T 2406.2-2009), and the sample size was 150mm×5mm×5mm.

According to the "Code for Fire Protection Design of Interior Decoration of Buildings" (GB50222-2017), the highest flame retardant grade of the residential building is B1, and its corresponding oxygen index is ≥32%. Figure 1 shows the effect of sulfonated carbon addition on the oxygen index of bamboo and wood fiber integrated boards. It can be seen that the limiting oxygen index of the bamboo-wood fiber wood-plastic board without sulfonated carbon is 31.8, which is close to 32 of the B1 level. After adding 0.5% sulfonated carbon, the limiting oxygen index of bamboo-wood fiber integrated board is 32.7, which exceeds the B1 level requirement of GB50222-2017. With the increase of the addition of sulfonated carbon, the limit oxygen index of the bamboo-wood fiber composite board increases. When the addition of sulfonated carbon increases to 2.5%, the limit oxygen index is 36.1, and continues to increase to 3.0%, the limit oxygen index is 36.0, It shows that the effect of the continuous increase of sulfonated carbon on the limiting oxygen index is no longer significant, and the reasonable addition amount of sulfonated carbon is about 2.5%. This shows that 2.5% sulfonated carbon can better match the new intumescent flame retardant system composed of calcium carbonate, ethylene-vinyl acetate resin and PBS resin, which is conducive to better forming a thermal insulation and oxygen barrier carbon layer adhered to the base The surface of the material avoids the further spread of the flame and makes the flame self-extinguishing.

Various factors in the forming process of sulfonated carbon/bamboo wood fiber wood-plastic board—the extrusion temperature of the main board, extrusion pressure, extrusion time, and the percentage of sulfonated carbon added are the orthogonal test factors, and the design is orthogonal to four factors and three levels In the test, the inspection indicators are the flexural strength and limiting oxygen index of the wood-plastic board. The factor level table is shown in Table 1-1, the orthogonal experiment results are shown in Table 1-2, and the intuitive analysis of the results is shown in Table 1-3.

Table 1-1 Factor Level Table

Table 1-2 Orthogonal experimental results of sulfonated carbon/bamboo wood fiber wood-plastic board molding

Intuitive analysis of the results in Table 1-3

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

From the experimental results, the level combination of test 2 is A ₁ B ₂ C ₂ D ₂ , the level combination of test 3 is A ₁ B ₃ C ₃ D ₃ , and the level combination of test 6 is A ₂ B ₃ C ₁ D ₂ . flexural strength and limiting oxygen index.

On the basis of the orthogonal test, the single factor optimization of the extrusion molding conditions of the wood-plastic board was further carried out. From the data in Table 1-4, the influence of the extrusion temperature of the main board on the flexural strength of the wood-plastic board increases and then decreases with the increase of the temperature. Combining its influence on the limiting oxygen index, the optimal extrusion temperature is 174 °C.

The extrusion temperature of the main plate (ie the processing temperature in the screw extruder in the above embodiment) was selected to be 174°C, and the influence of extrusion pressure on the bending strength and limiting oxygen index was investigated. It can be seen from Table 1-5 that with the increase of pressure, the flexural strength increases, but when the pressure is 8.0-8.5MPa, the limit oxygen index has a higher value. Therefore, 8.0MPa is a more suitable extrusion pressure.

The extrusion temperature of the main board was determined to be 174°C, and the extrusion pressure was determined to be 8.0 MPa. With the extension of time, the flexural strength and limiting oxygen index of the wood-plastic board increase, and it is more appropriate to choose the extrusion time of 60s (as shown in Table 1-6).

Table 1-4 Influence of extrusion temperature of main board on flexural strength and limiting oxygen index of wood-plastic board

Table 1-5 Influence of extrusion pressure of main board on flexural strength and limiting oxygen index of wood-plastic board

Table 1-6 Influence of extrusion time on flexural strength and limiting oxygen index of wood-plastic panels

2. Thermogravimetric analysis

The thermal degradation performance of sulfonated carbon/bamboo wood fiber wood-plastic board was tested by TGA-Q500 thermogravimetric analyzer. Weigh 8-12 mg of dry powder and heat it from 40°C to 800°C at a heating rate of 10°C/min. The protective gas is high-purity nitrogen with a flow rate of 20 mL/min.

The thermogravimetric curves and data of bamboo-wood fiber integrated boards with different amounts of sulfonated carbon under nitrogen atmosphere are shown in Figure 2 and Table 2, respectively. It can be seen from the curve that the addition of sulfonated carbon did not significantly change the shape of the pyrolysis curve of the bamboo-wood fiber integrated board, but with the increase of sulfonated carbon, the degradation rate of the bamboo-wood fiber integrated board slowed down and the combustion residue increased, especially the 500 In the high temperature region above ℃, the thermal stability of the residue increases significantly.

Table 2 Thermal weight loss data of different bamboo and wood fiber integrated boards

The temperature T _5% of all samples degraded by 5% is not different, but the T _{50% of the samples degraded by 50%} is significantly different. For S-0.0% without sulfonated carbon, the T _50% is 734.2 ℃, with With the increase of sulfonated carbon, T _50% increased, S-2.5% was 771.3℃, which was 37.1℃ higher than S-0.0%. From the degradation residues corresponding to 400°C, 600°C, and 800°C, it can be seen that the lowest mass percentage of S-0.0% without sulfonated carbon is 74.07%, 60.39%, and 31.46%, respectively; adding 0.5% of S-0.5% For the sample, the corresponding residual mass percentages increased by 2.21%, 3.10% and 4.11% respectively compared with S-0.0%; with the increase of sulfonated carbon, the degradation residues at high temperature became more and more, when adding 2.5%, The mass percentages of sample S-2.5% at 400 °C, 600 °C, and 800 °C are 77.30%, 68.48%, and 45.66%, respectively, which are 3.23%, 8.09%, and 14.2% higher than that of the S-0.0% sample. The experimental results It shows that the addition of sulfonated carbon rapidly improves the thermal stability of the sample in the high temperature range (400-800 °C), which is because the sulfonated carbon catalyzes the formation of better calcium carbonate, ethylene-vinyl acetate resin and PBS resin systems when heated. The carbon layer barrier can effectively isolate heat and oxygen, and protect the underlying substrate.

3. Evaluation of combustion performance

Referring to the ISO5660-1 standard, the British FTT cone calorimeter was used to measure the combustion performance of the sulfonated carbon/bamboo wood fiber wood-plastic board. The size of the test piece is 100mm×100mm×10mm (length×width×thickness). According to the ISO5660-1-2002 standard, wrap all surfaces of the CONE sample of the cone calorimeter except the heated surface with aluminum foil, put it in a stainless steel sample holder, block heat transfer at the bottom of the aluminum foil, and heat it at 50kW·m ^-2 The surface temperature of the material was about 760°C when the samples were systematically studied and tested under irradiation power.

The heat release rate HRR is the most important parameter to characterize the fire intensity, which refers to the heat release rate per unit area when the material burns under the preset radiation intensity. The larger the HRR or PHRR is, the more heat is fed back from the combustion of the material per unit area per unit time, which leads to faster pyrolysis of the material, increased production of volatile combustible gases, and faster fire spread. Therefore, the greater the HRR or PHRR, the greater the risk of the material in fire. Total Heat Release (THR) refers to the synthesis of the heat released between the ignition of the material and the extinguishment of the fire under the preset thermal radiation intensity, THR=∫HRRdt, and its unit is MJ/ m ² . The higher the THR, the more heat the material releases when it burns, and the more damage it causes. The combination of HRR and THR can objectively and comprehensively evaluate the combustion performance of materials.

The CONE experimental data of different bamboo and wood fiber integrated boards are listed in Table 3-1. Figures 3 and 4 are the heat release rate curves and total heat release curves of different bamboo and wood fiber integrated boards, respectively. For the S-0.0% sample without sulfonated carbon, the ignition time TTI (time to ignition) is 30s, the flame extinction time FET (flame extinction time) is 317s, and the flame burning time is 287s; with the addition of sulfonated carbon, The ignition time of the samples increases, and the extinction time is advanced. Among them, the TTI of the samples S-2.0% and S-2.5% is the longest, which is 35s, the FET is the earliest, which is 190s, and the flame burning time is 155s, which is shorter than that of S-0.0%. 132s of open flame burning. From the heat release data of the CONE experiment, it can be seen that the addition of sulfonated carbon can effectively reduce the heat release. The peak PHRR of the highest heat release rate of S-2.5% is 16.7% lower than that of S-0.0%, which is 168.3kW/m ² . The average heat release rate MHRR and the effective combustion EHC are 70.30kW/m ² and 11.30MJ/kg, respectively. The 95.30kW/m ² of S-0.0% is reduced by 25.00kW/m ² and 2.79MJ/kg, respectively, which are 26.2% and 19.8% ^; -0.0% THR38.13MJ/m ² decreased by 49.5%. From the heat release rate curves and total heat release curves of different bamboo-wood fiber integrated boards in Figures 3 and 4, it can be seen that the addition of sulfonated carbon significantly reduces the heat release rate and total heat release, especially for the sample S- The 2.5% curve is the most obvious and is below the curve of the other samples. The Fire Spread Index (FGI) is the ratio of the peak heat release rate (PHRR) to the time to peak (t _PHRR ). The larger the FGI, the shorter the time it takes to reach a higher peak heat release rate and the greater the fire hazard. It can be seen from Table 3-1 that the FGI of S-0.0% is 4.04kw/sm ² . With the increase of sulfonated carbon, the FGI decreases in turn. The FGI of S-2.5% is 1.02kw/sm ² , less than S-0.0 A quarter of %FGI. It shows that the addition of sulfonated carbon can effectively inhibit the heat release of bamboo and wood fiber wood-plastic panels, reduce the spread of flames, and reduce the risk of fire.

Table 3-1 Cone calorimetry data of different bamboo and wood fiber integrated boards

Smoke and poisonous gas are the main causes of casualties in fires. Toxic gas causes people to suffocate, smoke reduces visibility in the fire scene, prevents firefighters from entering the fire scene for rescue, and makes it difficult for people at the fire scene to evacuate and escape. According to statistics, 70% to 80% of fire deaths are caused by smoke and toxic gas suffocation. Therefore, smoke and toxic gases are important factors that cause casualties in fires. The CONE smoke data of different bamboo and wood fiber integrated boards are shown in Table 3-2, and the total smoke emission curve is shown in Figure 5. From Table 3-2, it can be seen that when the PVC in the raw material is burned, a large amount of smoke will be released, so the smoke release rate SPR of S-0.0% is as high as 1381.8m ² /s, and the total smoke release amount is TSP12.29m ² / m ² , the highest among all samples. The addition of sulfonated carbon can quickly reduce the rate of flue gas release and the total amount of smoke released. The addition of 1.5% has reduced the SPR to 689.2m ² /s, which is more than half of that of S-0.0%. With the increase of sulfonated carbon, SPR and TSP are further reduced, SPR of S-2.5% is reduced to 486.4m ² /s, only 35.2% of S-0.0%; TSP is 4.99m ² /m ² , which is lower than that of S-0.0 % decreased by 7.3m ² /m ² , about 59.4%. CO is the most important factor causing suffocation and poisoning in fires. The addition of sulfonated carbon can effectively reduce the production of carbon monoxide. The addition of 2.5% reduces the production of carbon monoxide from 45.5g/kg to 21.4g/kg. 53.0%. In addition to the adsorption of smog by the porous structure of the sulfonated carbon, the reduction of CO is mainly due to the catalytic carbonization of the bamboo-wood fiber system by the sulfonated carbon. The rapid carbonization rate and excellent carbonization quality make the samples under the carbon layer Being efficiently protected, the flame goes out faster and the burning time is shortened.

Table 3-2 Cone calorimetry data of different bamboo and wood fiber integrated boards

4. Morphology analysis of residues of sulfonated carbon/bamboo wood fiber wood-plastic board

Using the Quanta 450 environmental scanning electron microscope of FEI Company, the morphology of the sulfonated carbon/bamboo wood fiber wood-plastic board after combustion was observed. Before the test, the surface of the specimen was sprayed with gold.

The electron microscope photo of the bamboo-wood fiber integrated board is shown in Figure 6. It can be seen from the figure that the S-0.0% carbon residue without sulfonated carbon has many pores and different sizes, and the pores are deep, and the surface of the carbon residue is powdery and not connected. overall. After adding sulfonated carbon, the surface of the sample carbon residue changed obviously, the pores of S-0.5% decreased, but the individual pores were still deep; with the increase of sulfonated carbon, S-1.0%, S-1.5%, S-2.0 % and S-2.5% pores gradually decrease, and the uniformity of pores increases, and the integrity and compactness of the carbon layer are getting better and better. Comparing S-0.0% and S-2.5% carbon residues at 1.0KX magnification (as shown in Figure 7), it is further found that the addition of sulfonated carbon changes a large amount of brittle carbon layers in S-0.0%, which is beneficial to the test. In this way, larger pieces of carbon are formed, and the entire carbon layer stretches into a dense whole with few cracks. This solid carbon layer structure becomes a barrier to protect the underlying material, which can efficiently isolate heat and oxygen, effectively inhibit the combustion of the underlying material, and reduce the generation of heat and smoke.

The sulfonic acid-based biochar flame-retardant wood-plastic board provided by the above embodiment complies with T/CADBM3-2018 "Bamboo and Wood Fiber Integrated Wallboard", GB18580-2017 "Formaldehyde Release in Wood-based Panels of Interior Decoration Materials and Their Products", "2020" The implementation rules for quality supervision and random inspection of decorative panel products in Hunan Province (HNCCXZ131-2020) requirements; the flame retardant performance meets the requirements of the B1 level of the "Classification of Combustion Performance of Building Materials and Products" (GB 8624-2012). The sulfonated carbon/bamboo wood fiber wood-plastic board (ie, sulfonic acid-based biochar flame-retardant wood-plastic board) product and its preparation process are green and environmentally friendly, and are ideal materials for people's green homes.

Judging from the demand for wood in my country, the contradiction between supply and demand of wood is acute, and there is a huge demand for value-added development technologies for wood residues. From the perspective of the demand for building materials such as home furnishing, wood-plastic composite materials have the performance advantages of planing and sawing, nailing and drilling, water immersion, non-swelling, drying and cracking, moth-proof and corrosion-resistant, zero aldehyde, non-toxic and tasteless. It can also be recycled. It is a veritable environment-friendly green material and has great application prospects in many fields. The market demand for green WPC for green production will increase.

Sulfonated carbon/bamboo fiber wood-plastic board products have good functionality and market application prospects. Its production technology can be completely upgraded in the traditional wood-plastic board production line. Compared with traditional wood-plastic boards, its products are environmentally friendly. , flame retardant, light weight and high strength and other functional advantages.

The above-mentioned embodiment is a preferred implementation solution of the present disclosure. In addition, the present disclosure can also be implemented in other ways, and any obvious replacements are within the protection scope of the present disclosure without departing from the concept of the technical solution.

In order to make it easier for those skilled in the art to understand the improvements of the present disclosure over the prior art, some drawings and descriptions of the present disclosure have been simplified, and for the sake of clarity, some other elements are also omitted in this application document, One of ordinary skill in the art would appreciate that such omitted elements may also constitute the subject matter of the present disclosure.

Claims

A sulfonic acid-based biochar fire-retardant wood-plastic board, comprising the following components in parts by weight: 20-30 parts of bamboo and wood fiber powder, 90-110 parts of heavy calcium carbonate, and 70-90 parts of polyvinyl chloride resin powder , 9-15 parts of PBS resin, 8-12 parts of hollow ceramic beads, 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, 0.6-1.2 part of foaming agent, 0.5-1 part of stearic acid, 0.5-1 part of PE wax.
The sulfonic acid-based biochar fire-retardant wood-plastic board according to claim 1, wherein: the bamboo and wood fiber powder is processed into a dry state.
A method for producing the sulfonic acid-based biochar fire-retardant wood-plastic board as claimed in claim 2, wherein, comprising the following steps:

(1) Combine bamboo and wood fiber powder, heavy calcium carbonate, polyvinyl chloride resin powder, PBS resin, hollow ceramic microbeads, ethylene vinyl acetate copolymer, sulfonated carbon, heat stabilizer, foaming regulator, foaming agent , stearic acid and PE wax are uniformly mixed and plasticized according to the proportion by weight to obtain a mixture;

(2) adding the blend obtained in the step (1) into the screw extruder for extrusion molding;

(3) making the material extruded in step (2) stereotyped and cooled to room temperature;

(4) Cutting the shaped and cooled material in step (3), and then carrying out a matte filming treatment to obtain a sulfonic acid-based biochar fire-retardant wood-plastic board.
The method for producing a sulfonic acid-based biochar fire-retardant wood-plastic board according to claim 3, wherein: the processing temperature in the screw extruder in step (2) is 170-180°C.