CN113771182B - Low smoke toxicity flame-retardant fiber board and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of artificial boards, and in particular relates to a fiberboard and a preparation method thereof. One of the low-smoke flame-retardant fiberboards includes: wood fibers and flame-retardant adhesives; the flame-retardant adhesives include: resin adhesives; and low-smoke-toxic composite flame retardants. The present invention can be widely used in high-rise buildings, interior decoration for public places, and furniture manufacturing, and can effectively solve the problems of high fire risk, large smoke production, and low toxicity of smoke produced by fiberboards used in places such as singing and dancing entertainment places and high-rise buildings. Qualified, the fiberboard is prone to mildew and discoloration during storage and use.

Description

Low smoke toxicity flame retardant fiberboard and preparation method thereof

Technical Field

The invention belongs to the technical field of artificial boards, and in particular relates to a fiberboard and a preparation method thereof.

Background Art

Fiberboard has good physical and mechanical properties, is green and environmentally friendly, and its products have the advantages of light weight, high strength, good insulation, easy processing and pleasant appearance. It has been widely used in furniture manufacturing, partitions, false walls, vehicle and ship manufacturing, household appliances and other fields. It is one of the most in-demand raw materials in my country's furniture and interior decoration industry. However, since ordinary fiberboards are made of combustible materials, once open flames or overload electricity are used during decoration, it is very easy to cause a fire and spread quickly, and a large amount of toxic smoke is generated when a fire occurs. The threat to human life from these smoke is even greater than the fire itself.

The patent CN101961879A has been published, which is a method for preparing a composite flame retardant for fiberboard. The main problems of this patent are that the flame retardant effect is not ideal, the combustion performance cannot reach B1 level, the flame retardant is easy to precipitate and absorb moisture, and the prepared fiberboard produces a large amount of smoke, the smoke cannot reach ZA3 level, and cannot meet the toxicity standard requirements. On the other hand, this patent belongs to a flame retardant aqueous solution. In the actual application process, it is necessary to spray the flame retardant aqueous solution on the fiber surface for flame retardancy, which increases the drying load and causes high energy consumption.

Patent CN02153877.8 has been published, a medium-density flame-retardant fiberboard and its manufacturing method. The process of preparing medium-density fiberboard in this patent is complicated, and the original medium-density fiberboard production process parameters need to be greatly changed, resulting in low production efficiency. On the other hand, the flame retardant components of this patent, sodium chloride and sodium bicarbonate, are easy to absorb water, moisture, loss, mildew, produce large smoke, and the flammability cannot reach B1 level. The smoke toxicity of the prepared flame-retardant medium-density fiberboard cannot reach ZA3 level, and cannot meet the toxicity requirements of medium-density fiberboard.

The patent CN102950632A discloses a highly efficient and environmentally friendly flame retardant for fiberboard and its preparation method. The problem with this patent is that the production process of the liquid flame retardant is complicated, which increases the drying load, and the liquid flame retardant will volatilize with the water vapor during the drying process, reducing the effective components of the flame retardant. On the other hand, the flame retardant in this patent also has the problem of high smoke toxicity, and the smoke toxicity of the prepared flame-retardant medium-density fiberboard cannot reach ZA3 level, and cannot meet the standard toxicity requirements.

It can be seen that the existing flame-retardant fiberboards generally have problems such as unsatisfactory flame retardant effect, large smoke production, smoke toxicity that cannot meet the ZA3 level requirements, easy moisture absorption, easy mildew, and easy discoloration. There is an urgent need to study the flame retardant technology and flame retardants of low-smoke toxicity fiberboards.

Summary of the invention

The present invention aims to provide a low-smoke toxicity flame-retardant fiberboard and a preparation method thereof in view of the above-mentioned technical problems commonly existing in existing flame-retardant fiberboards.

A low smoke toxicity flame retardant fiberboard, comprising: wood fiber and flame retardant adhesive;

The flame retardant adhesive comprises:

Resin adhesive;

Low smoke toxicity composite flame retardant.

The moisture content of the wood fiber is less than 7%.

The resin adhesive aqueous solution accounts for 25% to 60% of the weight of the wood fiber, preferably 30% to 55%.

The resin adhesive aqueous solution is at least one of a urea-formaldehyde resin adhesive aqueous solution or a melamine-modified urea-formaldehyde resin adhesive aqueous solution.

The low smoke toxicity composite flame retardant accounts for 3% to 30% of the weight of the wood fiber, preferably 5% to 25%.

The low smoke toxicity composite flame retardant comprises the following raw materials:

Ammonium phosphates, boric acid, borates, flame retardant synergists and smoke suppressants;

The smoke suppressant is at least one of a smoke suppressant synergist or a smoke suppressant adsorbent.

Based on 100 parts by weight of the low-smoke toxicity composite flame retardant, the raw materials are used in the following parts by weight:

10 to 50 parts, preferably 15 to 40 parts, of ammonium phosphate;

10 to 55 parts of boric acid, preferably 15 to 45 parts;

10 to 55 parts of borate, preferably 15 to 45 parts;

5 to 30 parts of flame retardant synergist, preferably 10 to 28 parts;

At least one of 2 to 30 parts, preferably 5 to 25 parts, of a smoke suppression synergist, or 1 to 15 parts, preferably 3 to 10 parts, of a smoke suppression adsorbent.

The ammonium phosphate salt is at least one of ammonium polyphosphate, ammonium monohydrogen phosphate or ammonium dihydrogen phosphate;

The borate is at least one of borax, zinc borate, calcium borate or copper borate;

The flame retardant synergist is at least one of organic sodium montmorillonite, organosilicon flame retardant, melamine, melamine cyanurate, melamine phosphate, melamine pyrophosphate, dipentaerythritol triphosphate melamine salt, dipentaerythritol phosphate melamine salt or dipentaerythritol dihydrogen phosphate melamine salt;

The smoke suppression synergist is at least one of copper hydroxide, copper oxide, cuprous oxide, malachite, azurite, ammonium molybdate, zinc molybdate, molybdenum oxide, ferrocene, iron oxide, cadmium oxide or zinc oxide;

The smoke suppression adsorbent is at least one of molecular sieve, graphene or aerogel.

The surface of the raw material of the low-smoke toxicity composite flame retardant is also subjected to surface modification treatment using a surface modifier.

The weight of the surface modifier is 0.1% to 1.5%, preferably 0.2% to 1.2% of the weight of the low-smoke toxicity composite flame retardant.

The surface modifier is prepared at a concentration of 0.8% to 2.0%, preferably a surface modifier solution at a concentration of 1.0% to 1.5%.

The surface modifier is at least one of a silane coupling agent, a titanate coupling agent, an aluminate coupling agent or an organosilicon.

A method for preparing a low-smoke flame-retardant fiberboard comprises the following steps:

1) Weighing a resin adhesive aqueous solution, adding a low-smoke toxicity composite flame retardant under stirring to prepare a flame retardant adhesive solution;

2) Mixing the dried and weighed wood fibers, spraying the flame retardant adhesive solution into the mixture while stirring, and taking out and drying the wood fibers after continuing to stir;

3) Laying and shaping the dried wood fibers;

4) The laid and shaped wood fibers are hot-pressed into shapes, and then trimmed and polished to obtain low-smoke and flame-retardant fiberboards.

In step 1), the low smoke toxicity composite flame retardant is prepared by the following method:

101) mixing the raw materials;

102) subjecting the raw materials to surface modification treatment in a mixed state;

103) Drying the surface-modified raw material to obtain a low-smoke toxicity composite flame retardant.

In step 101), the raw materials are mixed in a high-speed mixer at a speed of 200 r/min to 450 r/min, preferably 250 r/min to 400 r/min, for 3 min to 15 min, preferably 5 min to 12 min;

In step 102), the surface of the raw material is modified by using a surface modifier, the weight of the surface modifier is 0.1% to 1.5% of the weight of the low-smoke toxicity composite flame retardant, preferably 0.2% to 1.2%, and the surface modifier is prepared into a surface modifier solution with a concentration of 0.8% to 2.0%, preferably 1.0% to 1.5%. During the mixing process of the raw materials, the prepared surface modifier solution is sprayed onto the surface of the raw material to achieve surface modification of the raw material;

In step 103), the surface-modified raw material is dried in an oven at a temperature of 80° C. to 95° C. for 20 min to 50 min, preferably 25 to 45 min, to obtain a low-smoke toxicity composite flame retardant.

Also includes:

104) The low-smoke toxicity composite flame retardant is crushed to control the particle size of the low-smoke toxicity composite flame retardant to be above 150 mesh, preferably above 200 mesh.

In step 104), the low-smoke composite flame retardant is crushed in a ball mill at a rotation speed of 200 r/min to 450 r/min, preferably 250 r/min to 400 r/min, for 20 min to 40 min, preferably 25 min to 35 min, so that the particle size is controlled to be above 150 mesh, preferably above 200 mesh.

In step 1), the resin adhesive aqueous solution is at least one of a urea-formaldehyde resin adhesive aqueous solution with a solid content of 30% to 60% (preferably a solid content of 50%) or a melamine-modified urea-formaldehyde resin adhesive aqueous solution.

In step 2), the moisture content of the wood fiber is less than 7%. The wood fiber is placed in a high-speed mixer, and the flame retardant adhesive solution is sprayed into the mixer at a speed of 200 r/min to 450 r/min, preferably 250 r/min to 400 r/min. After stirring for 5 min to 20 min, preferably 8 min to 15 min, the wood fiber is taken out and placed in an oven at 70° C. to 100° C., preferably 80° C. to 95° C., for drying for 20 min to 45 min, preferably 25 min to 40 min.

In step 4), the laid and shaped wood fibers are transported to a hot pressing molding machine;

Control the temperature of zones Ⅰ to Ⅴ of the hot pressing machine: zone Ⅰ is 235±10℃, zone Ⅱ is 230±10℃, zone Ⅲ is 225±10℃, zone Ⅳ is 215±10℃, and zone Ⅴ is 190±10℃;

The pressures at the five points in zone I are controlled to be 7.5±2MPa, 13±2MPa, 23±2MPa, 23±2MPa, and 20±2MPa; the time for each pressure point is 0.5 to 5 seconds, preferably 1 to 3 seconds;

The pressures at the five points in zone II are controlled to be 14.5±2MPa, 13.5±2MPa, 9.5±2MPa, 5.5±2MPa, and 3.7±2MPa, respectively; the time for each pressure point is 0.5 to 5 seconds, preferably 1 to 3 seconds;

The 15 pressure points of the subsequent zones III, IV and V are controlled to be 1.9±1MPa; the time for each pressure point is 0.5 to 5 seconds, preferably 1 to 3 seconds;

Finally, the hot-pressed board is trimmed and polished to obtain a low-smoke flame-retardant fiberboard.

The positive progressive effects of the present invention are: the present invention adopts a low-smoke flame-retardant fiberboard and a preparation method thereof, the performance of which reaches B1 level of GB8624-2012 "Classification of Combustion Performance of Building Materials", the smoke density level SDR is less than 10, the smoke toxicity reaches ZA3 level or above of GB20285-2006 "Material Smoke Toxicity Hazard Classification", the formaldehyde emission meets the E1 level requirement of GB18580-2017 "Limits of Formaldehyde Emission in Artificial Boards and Their Products for Indoor Decoration and Renovation Materials", the physical and chemical properties meet the requirements of GB/T11718-2009 "Medium Density Fiberboard", and the mildew and discoloration resistance properties meet the level 0 requirement of GB/T18261-2013 "Test Method for the Effectiveness of Mildew Inhibitors on Wood Mildew and Discoloration Fungi".

The low-smoke flame-retardant fiberboard used in the present invention can be widely used in interior decoration and furniture manufacturing of high-rise buildings and public places, and can effectively solve the technical problems of high fire risk, large smoke production, unqualified smoke toxicity, and easy mildew and discoloration of fiberboard in the current singing and dancing entertainment places, high-rise buildings and other places.

DETAILED DESCRIPTION

In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below.

A low-smoke flame-retardant fiberboard comprises wood fibers and a flame-retardant adhesive.

The moisture content of wood fiber is below 7%.

Flame retardant adhesives include resin adhesives and low-smoke composite flame retardants.

The resin adhesive aqueous solution is 25% to 60% (preferably 30% to 55%) of the wood fiber weight. The resin adhesive aqueous solution uses at least one of urea-formaldehyde resin adhesive aqueous solution or melamine-modified urea-formaldehyde resin adhesive aqueous solution, and the solid content of the resin adhesive aqueous solution is 30% to 60% (preferably 50%).

The low smoke toxicity composite flame retardant is 3% to 30% (preferably 5% to 25%) of the weight of the wood fiber. The low smoke toxicity composite flame retardant, calculated as 100 parts, includes the following raw materials:

10-50 parts (preferably 15-40 parts) of ammonium phosphate salt, which is at least one of ammonium polyphosphate, monoammonium phosphate or diammonium phosphate. The ammonium phosphate salt contains phosphorus and nitrogen elements, and can decompose and release non-combustible gases such as ammonia and water vapor during combustion, which can further reduce the calorific value of the fiberboard.

10-55 parts of boric acid (preferably 15-45 parts). 10-55 parts of borate (preferably 15-45 parts), the borate is at least one of borax, zinc borate, calcium borate or copper borate. Boric acid and borate in the components form a glassy inorganic expansion coating during the fiber pyrolysis process, which can promote carbonization, hinder the escape of combustibles, dehydrate at high temperatures, and have the effects of reducing calorific value, foaming and diluting combustibles. In addition, boric acid and borate have antiseptic and antibacterial effects, which can effectively solve the problem of fiberboard being easy to mildew and discolor.

5 to 30 parts (preferably 10 to 28 parts) of a flame retardant synergist, wherein the flame retardant synergist is at least one of organic sodium montmorillonite, silicone flame retardant, melamine, melamine cyanurate (MCA), melamine phosphate, melamine pyrophosphate, dipentaerythritol triphosphate melamine salt, dipentaerythritol phosphate melamine salt or dipentaerythritol dihydrogen phosphate melamine salt. The addition of the flame retardant synergist can further reduce the calorific value, further increase the compactness of the carbon layer, and prevent the release of smoke particles and toxic gases.

The smoke suppressant contains 2 to 30 parts (preferably 5 to 25 parts) of a smoke suppressant synergist, which is at least one of copper hydroxide, copper oxide, cuprous oxide, malachite, azurite, ammonium molybdate, zinc molybdate, molybdenum oxide, ferrocene, iron oxide, cadmium oxide or zinc oxide. The smoke suppressant synergist has a low-temperature catalytic carbonization effect on wood fiber, which can reduce the initial thermal decomposition temperature of wood fiber, increase the amount of coke generated by dehydration and carbonization at low temperature, and the coke covers the surface of the fiber board, which isolates the external air and inhibits the further thermal decomposition of the fiber, and at the same time prevents the release of particulate smoke inside the fiber, thereby playing a smoke suppressant role.

The smoke suppressant contains 1 to 15 parts (preferably 3 to 10 parts) of a smoke suppressant adsorbent, which is at least one of a molecular sieve, graphene or aerogel. The smoke suppressant adsorbent is a porous material with a very high specific area, which can absorb smoke particles and harmful gases generated during combustion, further reducing smoke production.

The surface of the raw material of the low-smoke toxic composite flame retardant is surface-modified by a surface modifier. The weight of the surface modifier is 0.1% to 1.5% of the weight of the low-smoke toxic composite flame retardant, preferably 0.2% to 1.2%, and is prepared into a surface modifier solution with a concentration of 0.8% to 2.0% (preferably 1.0% to 1.5%). The surface modifier is at least one of a silane coupling agent, a titanate coupling agent, an aluminate coupling agent or an organosilicon. Through the surface treatment of the surface modifier, the problems of precipitation, moisture absorption and mildew of the flame retardant in the fiberboard are solved.

A method for preparing a low-smoke flame-retardant fiberboard comprises the following steps:

1) Preparation of flame retardant adhesive:

The resin adhesive aqueous solution was weighed, and a low-smoke toxicity composite flame retardant was added under stirring to prepare a flame retardant adhesive solution.

In this step, at least one of urea-formaldehyde resin adhesive aqueous solution or melamine-modified urea-formaldehyde resin adhesive aqueous solution is weighed at 25% to 60% (preferably 30% to 55%) of the weight of the wood fiber, and the solid content of the resin adhesive aqueous solution is 30% to 60% (preferably 50%). Under stirring, 3% to 30% (preferably 5% to 25%) of the weight of the wood fiber is added with a low-smoke toxicity composite flame retardant to prepare a flame retardant adhesive solution.

In this step, the resin adhesive aqueous solution is placed in a container for preparation, and the low-smoke toxicity composite flame retardant is added into the container and stirred evenly to prepare a flame retardant adhesive solution.

In this step, the low smoke toxicity composite flame retardant is prepared by the following method:

101) Mix the raw materials.

The raw materials in this step are the raw materials of the low smoke toxicity composite flame retardant of the present invention. When the raw materials are mixed, they are mixed in a high-speed mixer at a speed of 200 r/min to 450 r/min (preferably 250 r/min to 400 r/min) for 3 min to 15 min (preferably 5 min to 12 min).

102) The raw materials are subjected to surface modification treatment in a mixed state.

In this step, the surface of the raw material is modified by using a surface modifier, the weight of the surface modifier is 0.1% to 1.5% of the weight of the low smoke toxicity composite flame retardant, preferably 0.2% to 1.2%, and the surface modifier solution is prepared with a concentration of 0.8% to 2.0%, preferably 1.0% to 1.5%. During the mixing of the raw materials, the surface modifier solution is sprayed onto the surface of the raw material to achieve surface modification of the raw material. The surface modifier is at least one of a silane coupling agent, a titanate coupling agent, an aluminate coupling agent or an organosilicon.

103) Drying the surface-modified raw material to obtain a low-smoke toxicity composite flame retardant.

In this step, the surface-modified raw material is dried in an oven at a temperature of 80° C. to 95° C. for 20 min to 50 min (preferably 25 to 45 min) to obtain a low-smoke toxicity composite flame retardant.

104) The low-smoke toxicity composite flame retardant is crushed to control the particle size of the low-smoke toxicity composite flame retardant to be above 150 mesh (preferably above 200 mesh).

In this step, the composite flame retardant is crushed in a ball mill at a speed of 200 r/min to 450 r/min (preferably 250 r/min to 400 r/min) for 20 min to 40 min (preferably 25 min to 35 min) to control the particle size to be above 150 mesh (preferably above 200 mesh).

2) Flame retardant treatment of wood fiber:

The dried and weighed wood fibers are mixed, and the prepared flame retardant adhesive solution is sprayed into the mixed materials while stirring. After continuing to stir, the wood fibers are taken out and dried.

In this step, the moisture content of the wood fiber is below 7%. The wood fiber is placed in a high-speed mixer, and the flame retardant adhesive solution is sprayed into the high-speed mixer while stirring at a speed of 200 r/min to 450 r/min (preferably 250 r/min to 400 r/min). After stirring for 5 min to 20 min (preferably 8 min to 15 min), the wood fiber is taken out and placed in an oven at 70°C to 100°C (preferably 80°C to 95°C) for drying for 20 min to 45 min (preferably 25 min to 40 min).

3) Pavement shaping:

The dried wood fibers are laid out and shaped.

In this step, the dried wood fiber can be placed in a mold frame for laying and shaping.

4) Hot pressing and shaping:

The laid and shaped wood fibers are hot-pressed into shape, and after trimming and grinding, low-smoke and flame-retardant fiberboard is obtained.

In this step, the laid and shaped wood fiber is transported to a hot press molding machine; the temperature of zones I to V of the hot press molding machine is controlled: zone I is 235±10°C, zone II is 230±10°C, zone III is 225±10°C, zone IV is 215±10°C, and zone V is 190±10°C; the pressures at the five points in zone I are controlled to be 7.5±2MPa, 13±2MPa, 23±2MPa, 23±2MPa, and 20±2MPa, and the time for each pressure point is 0.5 seconds to 5 seconds (preferably 1 second to 3 seconds); control the pressures of 5 points in zone II to be: 14.5±2MPa, 13.5±2MPa, 9.5±2MPa, 5.5±2MPa, 3.7±2MPa, each pressure point time is 0.5 second to 5 seconds (preferably 1 second to 3 seconds); control the 15 pressure points in subsequent zones III, IV, and V to be: 1.9±1MPa, each pressure point time is 0.5 second to 5 seconds (preferably 1 second to 3 seconds); finally, trim and polish the hot-pressed sheet to obtain a low-smoke flame-retardant fiberboard.

Embodiment 1:

According to the raw material formulas of Examples 1 to 4 and Comparative Examples 1 to 3 in Table 1, a low smoke toxicity composite flame retardant was prepared by the following preparation method:

1. Weigh the raw materials according to the formula and mix them in a high-speed mixer at 250 rpm for 5 minutes.

2. Prepare the surfactant solution according to the formula requirements, stir the weighed raw materials in a high-speed mixer at 250 rpm, spray the surfactant solution during the stirring process, and then dry the raw materials with surface spray modification in an oven at 90°C for 25 minutes.

3. The dried composite flame retardant was crushed in a ball mill at a speed of 400 rpm for 25 min to control the particle size to 200 meshes, thereby obtaining the prepared low smoke toxicity composite flame retardants of Examples 1 to 4 and Comparative Examples 1 to 3.

According to Example 5 in Table 1, a low smoke toxicity composite flame retardant was prepared by the following preparation method:

1. Weigh the raw materials according to the formula and mix them in a high-speed mixer at 200 rpm for 3 minutes.

2. Prepare the surfactant solution according to the formula requirements, stir the weighed raw materials in a high-speed mixer at 200 rpm, spray the surfactant solution during the stirring process, and then dry the raw materials with surface spray modification in an oven at 80°C for 20 minutes.

3. The dried composite flame retardant was crushed in a ball mill at a speed of 200 rpm for 20 min to control the particle size to 150 mesh, thereby obtaining the prepared low smoke toxicity composite flame retardant of Example 5.

According to Example 6 in Table 1, a low smoke toxicity composite flame retardant was prepared by the following preparation method:

1. Weigh the raw materials according to the formula and mix them in a high-speed mixer at 450 rpm for 15 minutes.

2. Prepare the surfactant solution according to the formula requirements, stir the weighed raw materials in a high-speed mixer at 450 rpm, spray the surfactant solution during the stirring process, and then dry the raw materials with surface spray modification in an oven at 95°C for 50 minutes.

3. The dried composite flame retardant was crushed in a ball mill at a speed of 450 rpm for 40 min to control the particle size to 200 meshes, thereby obtaining the prepared low smoke toxicity composite flame retardant of Example 6.

Table 1: Raw material formula of low smoke toxicity composite flame retardant

The low smoke toxicity composite flame retardants prepared in Examples 1 to 4 and Comparative Examples 1 to 3 in Table 1 were applied to the preparation of low smoke toxicity flame retardant fiberboards. According to the preparation formula in Table 2, the low smoke toxicity flame retardant fiberboards were prepared by the following preparation method:

1. Dry the wood fiber to a moisture content of less than 7%, and weigh a preset weight of the wood fiber.

2. According to the preparation formula, weigh 25% to 60% of the weight of the wood fiber resin adhesive aqueous solution, the solid content of the resin adhesive aqueous solution is 50%, and add 5% to 30% of the weight of the wood fiber low-smoke toxicity composite flame retardant under stirring to prepare a flame retardant adhesive solution.

3. Put the dried and weighed wood fiber into a high-speed mixer, spray the prepared flame retardant adhesive solution into the mixer while stirring at 250 rpm, continue stirring at high speed for 8 minutes, then take out the sprayed wood fiber and put it into an 80°C oven to dry for 25 minutes.

4. Place the surface treated wood fiber into the mold frame and lay it out to shape.

5. The paved and shaped wood fibers are transported to the hot pressing machine, and the temperature of zones I to V of the hot pressing machine is controlled: zone I is 235°C, zone II is 230°C, zone III is 225°C, zone IV is 215°C, and zone V is 190°C. The pressures of the five points in zone I are controlled to be 7.5MPa, 13MPa, 23MPa, 23MPa, and 20MPa respectively; the pressures of the five points in zone II are controlled to be 14.5MPa, 13.5MPa, 9.5MPa, 5.5MPa, and 3.7MPa respectively, and the pressures of the 15 subsequent zones III, IV, and V are all 1.9MPa. The hot pressing time of each pressure point is controlled to be 1 second. Finally, the hot pressing-formed board is trimmed and polished to obtain the low-smoke flame-retardant fiberboards of Examples 1 to 4 and Comparative Examples 1 to 3.

The prepared low smoke toxicity composite flame retardant of Example 5 was used in the preparation process of the low smoke toxicity flame retardant fiberboard. According to the preparation formula of Example 4 in Table 2, the low smoke toxicity flame retardant fiberboard of Example 4-1 was prepared by the following preparation method:

1. Dry the wood fiber to a moisture content of less than 7%, and weigh a preset weight of the wood fiber.

2. According to the preparation formula, weigh 25% to 60% of the weight of the wood fiber resin adhesive aqueous solution, the solid content of the resin adhesive aqueous solution is 30%, and add 5% to 30% of the weight of the wood fiber low-smoke toxicity composite flame retardant under stirring to prepare a flame retardant adhesive solution.

3. Put the dried and weighed wood fiber into a high-speed mixer, spray the prepared flame retardant adhesive solution into the mixer while stirring at 200 rpm, continue stirring at high speed for 5 minutes, then take out the sprayed wood fiber and put it in a 70°C oven to dry for 20 minutes.

4. Place the surface treated wood fiber into the mold frame and lay it out to shape.

5. The paved and shaped wood fibers are transported to the hot pressing machine, and the temperature of zones I to V of the hot pressing machine is controlled: zone I is 225°C, zone II is 220°C, zone III is 215°C, zone IV is 205°C, and zone V is 180°C. The pressures of the five points in zone I are controlled to be 5.5MPa, 11MPa, 21MPa, 21MPa, and 18MPa respectively; the pressures of the five points in zone II are controlled to be 13.5MPa, 11.5MPa, 7.5MPa, 3.5MPa, and 1.7MPa respectively, and the pressures of the 15 subsequent zones III, IV, and V are all 0.9MPa. The hot pressing time of each pressure point is controlled to be 0.5 seconds. Finally, the hot-pressed sheet is trimmed and polished to obtain the low-smoke flame-retardant fiberboard of Example 5.

The prepared low smoke toxicity composite flame retardant of Example 6 is used in the preparation process of the low smoke toxicity flame retardant fiberboard. According to the preparation formula of Example 4 in Table 2, the low smoke toxicity flame retardant fiberboard of Example 6 is prepared by the following preparation method:

1. Dry the wood fiber to a moisture content of less than 7%, and weigh a preset weight of the wood fiber.

2. According to the preparation formula, weigh 25% to 60% of the weight of the wood fiber resin adhesive aqueous solution, the solid content of the resin adhesive aqueous solution is 60%, and add 5% to 30% of the weight of the wood fiber low-smoke toxicity composite flame retardant under stirring to prepare a flame retardant adhesive solution.

3. Put the dried and weighed wood fiber into a high-speed mixer, spray the prepared flame retardant adhesive solution into the mixer while stirring at 450 rpm, continue stirring at high speed for 20 minutes, then take out the sprayed wood fiber and put it into a 100°C oven to dry for 45 minutes.

4. Place the surface treated wood fiber into the mold frame and lay it out to shape.

5. The paved and shaped wood fibers are transported to the hot pressing machine, and the temperature of zones I to V of the hot pressing machine is controlled: zone I is 245°C, zone II is 240°C, zone III is 235°C, zone IV is 225°C, and zone V is 200°C. The pressures of the five points in zone I are controlled to be 9.5MPa, 15MPa, 25MPa, 25MPa, and 22MPa respectively; the pressures of the five points in zone II are controlled to be 16.5MPa, 15.5MPa, 11.5MPa, 7.5MPa, and 5.7MPa respectively, and the pressures of the 15 subsequent zones III, IV, and V are all 2.9MPa. The hot pressing time of each pressure point is controlled to be 5 seconds. Finally, the hot-pressed sheet is trimmed and polished to obtain the low-smoke flame-retardant fiberboard of Example 6.

Table 2: Preparation formula of low smoke flame retardant fiberboard

The low smoke toxicity composite flame retardants obtained in the above Examples 1 to 6 and Comparative Examples 1 to 3 were applied to the preparation of low smoke toxicity flame retardant fiberboards. The obtained low smoke toxicity flame retardant fiberboards were tested for performance. The results are shown in Table 3 below:

Table 3: Performance parameters of low smoke flame retardant fiberboard

It can be seen from Table 3 that the low-smoke flame-retardant fiberboards of Examples 1 to 6 prepared by the low-smoke composite flame retardants of Examples 1 to 6 of the present invention have a smoke density grade SDR lower than 10 due to the smoke suppression and synergistic effect of multiple flame retardant elements, and their flammability can reach B1 (C) or above, the smoke toxicity can reach ZA3 or above, and the antibacterial, anti-mildew and discoloration properties meet the requirements of the damage value level 0.

Since the smoke suppression synergist and smoke suppression adsorbent of the present invention are not used in Comparative Example 1, the smoke density level SDR of the board is greater than 75, and the smoke toxicity is at a dangerous level, which cannot meet the use requirements. In addition, since the surface modifier is not used for surface modification in Comparative Example 1, the antibacterial, anti-mildew and discoloration properties can only reach the damage value level 2.

Since no flame retardant synergist and smoke suppressant adsorbent were added to Comparative Example 2, the combustion performance could only reach Class C, and the smoke toxicity was Class ZA3.

Since the flame retardant synergist of the present invention is not used in Comparative Example 3, the combustion performance of the board can only reach Class C.

In summary, it is shown that under the condition of the same amount of flame retardant added, the flame retardant synergist is beneficial to improve the combustion performance of the board, thereby upgrading the combustion performance of the board from Class C to Class B1; by adding the smoke suppression synergist or smoke suppression adsorbent of the present invention, the smoke toxicity level SDR of the board is reduced to below 10, and the smoke toxicity is also upgraded from the dangerous level to above ZA3, meeting the toxicity standard requirements of fiberboard. In addition, through the surface modification treatment of the flame retardant of the present invention, the antibacterial, mildew-proof and discoloration properties are upgraded from the harmful value level 2 to level 0, solving the problems of flame retardant precipitation, moisture absorption and mildew.

The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims (8)

1. A low smoke toxicity flame retardant fiberboard, comprising: wood fiber and a flame retardant adhesive; characterized in that the flame retardant adhesive comprises: Resin adhesive aqueous solution; Low smoke toxicity composite flame retardant; The low smoke toxicity composite flame retardant comprises the following raw materials: Ammonium phosphates, boric acid, borates, flame retardant synergists and smoke suppressants; The smoke suppressant is a smoke suppressant synergist and a smoke suppressant adsorbent; The smoke suppression synergist is at least one of copper hydroxide, copper oxide, cuprous oxide, malachite, azurite, ammonium molybdate, zinc molybdate, molybdenum oxide, ferrocene, iron oxide, cadmium oxide and zinc oxide; The smoke suppression adsorbent is at least one of molecular sieve, graphene and aerogel; The resin adhesive aqueous solution is 25% to 60% of the weight of the wood fiber; The low smoke toxicity composite flame retardant is 3% to 30% of the weight of the wood fiber; The resin adhesive aqueous solution is at least one of a urea-formaldehyde resin adhesive aqueous solution and a melamine-modified urea-formaldehyde resin adhesive aqueous solution; Based on 100 parts by weight of the low-smoke toxicity composite flame retardant, the raw materials are used in the following parts by weight: 10-50 parts of ammonium phosphate; 10-55 parts of boric acid; 10-55 parts of borate; 5-30 parts of flame retardant synergist; 2 to 30 parts of smoke suppression synergist and 1 to 15 parts of smoke suppression adsorbent; The ammonium phosphate salt is at least one of ammonium polyphosphate, ammonium monohydrogen phosphate and ammonium dihydrogen phosphate; The borate is at least one of borax, zinc borate, calcium borate and copper borate; The flame retardant synergist is at least one of organic nano-montmorillonite, organosilicon flame retardant, melamine, melamine cyanurate, melamine phosphate, melamine pyrophosphate, dipentaerythritol triphosphate melamine salt, dipentaerythritol phosphate melamine salt and dipentaerythritol dihydrogen phosphate melamine salt. 2. The low smoke toxicity flame retardant fiberboard according to claim 1, characterized in that the moisture content of the wood fiber is less than 7%; The resin adhesive aqueous solution is 30% to 55% of the weight of the wood fiber; The low smoke toxicity composite flame retardant accounts for 5% to 25% of the weight of the wood fiber. 3. The low-smoke toxicity flame-retardant fiberboard according to claim 1, characterized in that, based on 100 parts by weight of the low-smoke toxicity composite flame retardant, the raw materials are used in the following parts by weight: 15-40 parts of ammonium phosphate; 15-45 parts of boric acid; 15-45 parts of borate; 10-28 parts of flame retardant synergist; 5 to 25 parts of smoke suppression synergist and 3 to 10 parts of smoke suppression adsorbent. 4. The low-smoke toxicity flame-retardant fiberboard according to claim 1, characterized in that the surface of the raw material of the low-smoke toxicity composite flame retardant is also subjected to surface modification treatment using a surface modifier; The surface modifier is in a concentration of 0.8% to 2.0%; The surface modifier is at least one of a silane coupling agent, a titanate coupling agent, an aluminate coupling agent and an organosilicon; The weight of the surface modifier is 0.1% to 1.5% of the weight of the low-smoke toxicity composite flame retardant. 5. The low-smoke toxicity flame-retardant fiberboard according to claim 4, characterized in that the surface of the raw material of the low-smoke toxicity composite flame retardant is also subjected to surface modification treatment using a surface modifier; The surface modifier is a surface modifier solution with a concentration of 1.0% to 1.5%; The surface modifier is at least one of a silane coupling agent, a titanate coupling agent, an aluminate coupling agent and an organosilicon; The weight of the surface modifier is 0.2% to 1.2% of the weight of the low-smoke toxicity composite flame retardant. 6. A method for preparing the low smoke toxicity flame retardant fiberboard according to any one of claims 1 to 5, characterized in that it comprises the following steps: 1) Weighing a resin adhesive aqueous solution, adding a low-smoke toxicity composite flame retardant under stirring to prepare a flame retardant adhesive solution; 2) Mixing the dried and weighed wood fibers, spraying the flame retardant adhesive solution into the mixture while stirring, and taking out and drying the wood fibers after continuing to stir; 3) Laying and shaping the dried wood fibers; 4) hot pressing the laid and shaped wood fibers, trimming and grinding them to obtain low-smoke and flame-retardant fiberboard; In step 1), the low smoke toxicity composite flame retardant is prepared by the following method: 101) mixing the raw materials; 102) subjecting the raw materials to surface modification treatment in a mixed state; 103) Drying the surface-modified raw material to obtain a low-smoke toxicity composite flame retardant. 7. The low smoke toxicity flame retardant fiberboard and the preparation method thereof according to claim 6, characterized in that: In step 101), the raw materials are added into a high-speed mixer, and mixed for 3 min to 15 min at a speed of 200 r/min to 450 r/min of the high-speed mixer; In step 102), the surface of the raw material is modified by using a surface modifier, the weight of the surface modifier is 0.1% to 1.5% of the weight of the low-smoke toxicity composite flame retardant, the surface modifier is prepared into a surface modifier solution with a concentration of 0.8% to 2.0%, and during the mixing process of the raw materials, the prepared surface modifier solution is sprayed onto the surface of the raw material to achieve surface modification of the raw material; In step 103), the surface-modified raw material is dried in an oven at a temperature of 80° C. to 95° C. for 20 min to 50 min to obtain a low-smoke composite flame retardant; Also includes: 104) crushing the low-smoke toxicity composite flame retardant to control the particle size of the low-smoke toxicity composite flame retardant to be above 150 mesh; In step 104), the low-smoke composite flame retardant is crushed in a ball mill at a rotation speed of 200 r/min to 450 r/min for 20 min to 40 min to control the particle size to be above 150 mesh. 8. The method for preparing the low smoke toxicity flame retardant fiberboard according to claim 6, characterized in that: In step 1), the resin adhesive aqueous solution is at least one of a urea-formaldehyde resin adhesive aqueous solution and a melamine-modified urea-formaldehyde resin adhesive aqueous solution, and the resin adhesive aqueous solution has a solid content of 30% to 60%; In step 2), the moisture content of the wood fiber is less than 7%, the wood fiber is placed in a high-speed mixer, and the flame retardant adhesive solution is sprayed into the high-speed mixer while stirring at a speed of 200 r/min to 450 r/min. After stirring for 5 min to 20 min, the wood fiber is taken out and placed in an oven at 70° C. to 100° C. to dry for 20 min to 45 min. In step 4), the laid and shaped wood fibers are transported to a hot pressing molding machine; Control the temperature of zones Ⅰ to Ⅴ of the hot pressing machine: zone Ⅰ is 235±10℃, zone Ⅱ is 230±10℃, zone Ⅲ is 225±10℃, zone Ⅳ is 215±10℃, and zone Ⅴ is 190±10℃; The pressures at the five control points in zone I are: 7.5±2MPa, 13±2MPa, 23±2MPa, 23±2MPa, 20±2MPa, and the time for each pressure point is 0.5s to 5s; The pressures at the five points in the control zone II are: 14.5±2MPa, 13.5±2MPa, 9.5±2MPa, 5.5±2MPa, 3.7±2MPa, and the time for each pressure point is 0.5s to 5s; The 15 pressure points in the subsequent zones III, IV and V are controlled to be 1.9±1MPa, and the time for each pressure point is 0.5 to 5 seconds; Finally, the hot-pressed board is trimmed and polished to obtain a low-smoke flame-retardant fiberboard.