CN116373063A - Low-formaldehyde ultrathin fiber board and preparation method thereof - Google Patents

Abstract

Provides a low-aldehyde ultrathin fiber board and a preparation method thereof, which can obtain the fiber board with good performance, the thickness is as thin as 0.8mm, and the density is as high as 0.9g/m ³ The ultrathin high-density fiberboard. The preparation method comprises the following steps: steaming the qualified wood chips, wherein the steaming pressure is 7.5 bar-8.0 bar, the steaming temperature is 160-165 ℃, and the steaming time is 3.5-4.0 min; adding melted 58# fully refined paraffin into the steamed wood chips and carrying out hot grinding to obtain 50-100 mesh wood fibers; uniformly applying urea-formaldehyde resin adhesive and an auxiliary agent on the surface of the wood fiber in a drying pipeline; drying the glued wood fiber to obtain the wood fiber with the water content of 6.0-6.5%Paving materials; paving the paving material into a continuous slab band, setting the thickness of the target plate to be 0.8mm and the density of the fiber plate to be 1050Kg/m ³ The method comprises the steps of carrying out a first treatment on the surface of the And conveying the slab band to a hot press for hot pressing, wherein the hot press is provided with four continuous pressure sections, the hot pressing temperature of the four pressure sections is gradually reduced according to the advancing direction of the slab band, and the hot pressing pressure of at least three later pressure sections is gradually increased.

Description

Low-aldehyde ultra-thin fiberboard and its preparation method

technical field

The invention relates to the field of manufacturing ultra-thin fiberboards, in particular to a low-aldehyde ultra-thin fiberboard and a preparation method thereof.

Background technique

On the one hand, ultra-thin fiberboard can be used as a decorative material to replace the existing high-tech wood and poplar decorative veneer to produce high-end furniture such as super-flat, skin-feeling, and high-gloss, and solve the problems of carbonization, unevenness, and cracking on the surface of furniture after decoration; On the other hand, it can be used as a balanced finish for high-end solid wood composite flooring, with the characteristics of high strength, deformation resistance, and strong dimensional stability; Paper materials are more environmentally friendly. At present, there is little research on ultra-thin fiberboard in other countries. China has entered the forefront of the world in the field of ultra-thin fiberboard production technology and equipment, and now has the production capacity of ultra-thin fiberboard with a minimum thickness of 1.0mm, but less than 1mm such as 0.8mm There is no relevant technology disclosure for ultra-thin fiberboard, and there is a huge industrial demand for 0.8mm ultra-thin fiberboard in terms of product application and new field expansion.

Contents of the invention

The present invention is developed in view of the above technical problems, and its purpose is to provide an ultra-thin high-density fiberboard with a thickness of 0.8mm and a density of more than 0.9g/ ^m3 and its preparation method, thereby obtaining a low-aldehyde ultra-thin fiberboard with good performance.

The invention provides the following technical solutions:

1. A preparation method for low-aldehyde ultra-thin fiberboard, which comprises steps:

Cooking treatment: Cook the qualified wood chips, the cooking pressure is 7.5bar~8.0bar, the cooking temperature is 160℃~165℃, and the cooking time is 3.5min~4.0min;

Thermal grinding treatment: add melted 58# fully refined paraffin wax to the cooked wood chips and perform thermal grinding to obtain 50-100 mesh wood fibers;

Glue sizing treatment: uniformly apply urea-formaldehyde resin glue and additives to the surface of wood fiber in the drying pipeline;

Drying treatment: dry the wood fiber after sizing to obtain a paving material with a moisture content of 6.0% to 6.5%;

Pavement treatment: Pave the pavement material into a continuous slab strip, set the target plate thickness to 0.8mm, and the fiberboard density to 1050Kg/m ³ ;

Hot-pressing treatment: Send the slab belt to a hot-pressing machine for hot-pressing. The hot-pressing machine arranges four continuous pressure zones. According to the advancing direction of the slab belt, the hot-pressing temperature in the four pressure zones is set to gradually decrease, and at least The hot pressing pressure in the three pressure ranges increases gradually,

Among them, the slab entrance is set to 6.8mm, and is set according to the advancing direction of the slab belt: the hot-pressing temperature in the first section is 175°C, the hot-pressing temperature in the second section is 165°C, and the hot-pressing temperature in the third section is 140°C, the hot-pressing temperature in the fourth section is 130°C; the hot-pressing pressure in the first section is 35bar-50bar, the hot-pressing pressure in the second section is 25bar-55bar, the hot-pressing pressure in the third section is 55bar-80bar, The hot pressing pressure in the fourth section is 120bar-150bar; the hot pressing speed is 105m/min.

Wherein, the qualified wood chips are wood chips with a length of 5 cm to 8 cm, a width of 5 cm to 8 cm, a thickness of 1 cm to 2 cm, and a moisture content of 55% to 65%.

Wherein, the preparation of the qualified wood chips includes washing treatment: washing and dehydrating planed chips with a length of 5 cm to 8 cm, a width of 5 cm to 8 cm, and a thickness of 1 cm to 2 cm, and controlling the moisture content of the wood chips to 55% to 65%;

Wherein, the preparation of the qualified wood chips further includes preheating: preheating the washed wood chips, and controlling the preheating temperature at 90°C to 98°C.

Wherein, the preparation of the qualified wood chips also includes pressing treatment: the preheated wood chips are extruded by a variable-diameter screw to form a cork.

Among them, the amount of 58# fully refined paraffin relative to the volume of the finished fiberboard is 8kg/m ³ -10kg/m ³ .

Among them, the solid content of the urea-formaldehyde resin glue is 49%-53%, and its application amount is 11%-13% relative to the dry fiber weight.

Wherein, the auxiliary agent includes a curing agent and paraffin, the curing agent is ammonium chloride, and its addition amount is 0.40% to 0.50% relative to the weight of the dry fiber; the solid content of the paraffin is 100%, and its addition amount is 0.7% to 0.9%.

Wherein, the pre-pressing treatment is also included before the hot-pressing treatment: pre-pressing the paved slab belt, and the pre-pressing pressure is 95bar-130bar.

2. A low-aldehyde ultra-thin fiberboard prepared by the above-mentioned preparation method.

The main factors affecting the preparation of 0.8mm ultra-thin fiberboard are the quality of fiber thermal grinding, drying moisture content and hot pressing parameters. The size and thickness of hot-milled fibers and hot-pressing parameters affect the strength of ultra-thin fiberboard, and the dry moisture content affects whether the ultra-thin fiberboard will burst. layered. The performance tests of the 0.8mm ultra-thin fiberboard prepared by this process all meet the China Forestry Products Industry Association T/CNFPIA3007-2019 "ultra-thin high-density fiberboard".

Detailed ways

If there is no special statement in the implementation, the numerical range "A~B" refers to above A (greater than or equal to A) and below B (less than or equal to B). , According to different processes, it sometimes refers to between 20 and 28 °C. Some processes are generally considered to be carried out at the normal temperature or room temperature when the temperature is limited.

Different fields in the actual industry have different understandings of normal temperature or room temperature, but from the perspective of the implementation and application of the patent law, the specific scope of application should be treated on the basis of the realization of the purpose of the invention, not limited to the narrow experience of a certain field. Those skilled in the art should also understand that when referring to a certain temperature, the actual meaning is that the control of the temperature is not an absolute constant temperature, and there will often be a certain degree of fluctuation, which may exceed one degree in certain scenarios, or even More, as long as the purpose of the experiment can be achieved, it should be regarded as being at this temperature.

The defined temperature can be the temperature control input on the equipment used. In practice, the temperature at a certain point depends on the particularity of the equipment and the situation at that time. The defined temperature can also be the target of personnel instructions. The actual control may involve a period of temperature change, even including a process of repeated fluctuations. For example, when the temperature is detected to be lower than the defined temperature, the reactor is heated. At the defined temperature, the reactor is cooled to maintain the commanded temperature overall. In addition to temperature, there will also be processes related to thickness, density or pressure, process change rate, etc. in the embodiment. For the understanding of its essence, refer to the above-mentioned definition principle of temperature.

This embodiment provides a preparation process for ultra-thin fiberboards. The ultra-thin fiberboards refer to fiberboards with a thickness of <1.5mm, especially high-density fiberboards with a thickness of <1.5mm. m ³ . According to this process, it is especially used for preparing ultra-thin high-density fiberboards as thin as 0.8mm and with a density of more than 0.9g/m ³ .

In some studies, there have been proposals for formaldehyde-free ultra-thin fiberboards, but formaldehyde-free glue suffers from high costs. On the other hand, adding urea-formaldehyde resin glue in the preparation of fiberboards often faces the impact on the performance of fiberboards. In contrast, the present invention adopts a scheme for preparing ultra-thin fiberboards with low aldehyde release rate. According to this preparation scheme, not only the goal of thinner and higher density fiberboard can be achieved, but also the mechanical performance requirements can be met, especially in line with the requirements of multiple standards in China Forest Products Industry Association T/CNFPIA3007-2019 "Ultra Thin High Density Fiberboard".

This implementation mode will introduce the preparation process of the low-aldehyde ultra-thin fiberboard provided by the invention in detail, and the corresponding limitations may be included in the claimed technical solution according to the understanding of those skilled in the art. The invention also requires the protection of the low-aldehyde ultra-thin fiberboard products prepared according to the process.

Planer:

Plane the log material, the technical requirements are that the length and width of the wood chips are both 5cm-8cm, and the thickness is 1cm-2cm. A flaking machine can be used to plan the log material, but the present invention does not limit the raw material and the flaking machine. In the embodiment, the New Zealand radiata pine log material will be used for verification. The planing method is not limited to direct planing of wood, and can also be used in conjunction with chippers and chippers. Wood shavings with required craftsmanship can also be purchased from the market.

Washing:

The shavings are sent to the washing machine, and directly enter the screw dehydrator after coming out of the washing machine, and the water from the screw dehydrator can be returned to the washing section. Washing the wood chips can remove the silt, dirt and non-metallic impurities attached to the wood chips, and to a certain extent, it can replace the magnetic separation process to reduce pollutants and sediments.

On the other hand, washing wood chips can also improve or control the moisture content of wood chips. If the moisture content of wood chips is too high, it is easy to obtain longer fibers before thermal grinding. Long fibers are easy to warp, and they are easy to heat aggregate and agglomerate during molding, which is not conducive to interweaving and complexing between fibers, and affects the laying of wet slabs. Install quality. If the moisture content of wood chips is too low, it is easy to soften and impervious to wood chips, and it is difficult to separate fibers, and the probability of fiber cutting is high, resulting in an increase in thick, short, and ultra-fine fibers, which reduces the quality of fiber separation.

Through the water washing and dehydration process, the moisture content of the wood chips can be controlled at a moisture content of 55%-65%, preferably 53%-62%, more preferably about 50%. The water washing process is beneficial to adjust the washing parameters, and the moisture content of wood chips can be effectively controlled. In addition, the friction between fibers plays a dominant role during thermal grinding, and the contact with the grinding disc becomes a secondary factor. By controlling the moisture content of washed wood chips at about 50%, excessive crushing and cutting of fibers can be avoided, and the quality of fiber separation can be guaranteed.

Preprocessing:

As a preferred or optional implementation, the qualified wood chips after washing and dehydration can be preheated. Specifically, the qualified wood chips are temporarily stored in the preheated buffer bin before the heat refiner through the closed conveyor belt, and the preheating temperature is controlled at 90°C to 98°C. The qualified wood chips refer to cleaned wood chips, especially wood chips with a length and width of 5 cm to 8 cm, a thickness of 1 cm to 2 cm, and a moisture content of 55% to 65%.

According to the requirement, before the wood chip is sent to the digester for softening treatment, it can also be extruded by a variable diameter screw to form a cork. It is worth mentioning that if the moisture content of the wood chips is too high, the friction between the wood chips and the feeding screw will be reduced, and when the wood is compressed, water will be squeezed out. The water is equivalent to a lubricant, causing slippage between the wood chips and the screw , is not conducive to the formation of cork. The moisture content of the wood chips is too low, which increases the axial force of the feeding screw and accelerates the wear of the bearing, and the cork is not dense and may cause back spraying.

Cooking:

Qualified wood chips after pretreatment or washing are sent to the vertical digester for cooking and softening treatment. When preparing the fibers required for 0.8mm ultra-thin fiberboard, the cooking pressure is 7.5bar to 8.0bar, the temperature is 160°C to 165°C, and the cooking time is 3.5min to 4.0min.

After cooking and softening the wood, water can be used to swell the amorphous region of cellulose, hemicellulose and lignin, providing free volume space for the violent movement of molecules. After the wood is hydrothermally treated, part of the hemicellulose is easily decomposed and dissolved into a liquid state. , The free hydroxyl groups on the molecular chains of the cellulose amorphous region absorb water, which thickens the water film in the cellulose gap, increases the distance between molecules, and reduces the attractive force, which is convenient for relative slippage under the action of external force.

Hot grinding:

The cooked wood chips are put into a heat refiner, and the melted 58# fully refined paraffin wax is added thereto, and the amount of addition is controlled according to the volume of the finished fiberboard, which is controlled at 8-10kg/m ³ in the examples provided by this application. The fibrous raw material after cooking is under the pressure and rotation of the heat mill to obtain 50-100 mesh wood fibers. Generally, the heat grinding time does not need to be strictly limited, but it is preferably controlled at 2.8 minutes to 3 minutes. Qualified fibers are sent into the drying pipeline.

Through thermal grinding treatment, the moisture content of wood chips is homogenized, and the fiber separation efficiency and fiber separation uniformity suitable for the subsequent process are obtained. It is known that separating fibers is a very complicated physical, mechanical and chemical transformation process. Due to its complex theory, coupled with difficulties in observation and simulation, it is difficult to quantify the research on the mechanism of separating fibers, but good thermal grinding quality considerations are important factor.

Adjust glue:

Adhesives and additives are sprayed through their respective metering pipes to form an impact mixing state with the fiber flow in the drying pipe to ensure that the materials are evenly distributed on the fiber surface. The adhesive of the present invention adopts urea-formaldehyde resin glue, with a solid content of 49-53%, preferably 51%, and an applied amount of 11-13%, preferably 12.5%, relative to the dry fiber specific gravity. The auxiliary agent includes curing agent and paraffin.

The type of curing agent is not limited, and can be appropriately selected within the scope of the understanding of the present invention by those skilled in the art. Specifically, a single-component curing agent can be selected, a multi-component curing agent, or a composite curing agent can be selected. The added amount of dry fiber specific gravity is 0.40%-0.50%, preferably 0.45%, and ammonium chloride is preferably used in the examples provided by the present invention. In addition, the paraffin wax has a solid content of 100%, and its added amount is 0.7-0.9%, preferably 0.8%, relative to the dry fiber specific gravity.

dry:

The fiber is ground by heat grinding and sizing to make the moisture content of the fiber reach 58% to 62%. The moisture in the fiber needs to be transformed from liquid phase to gas phase through the drying system and evaporated. , control the temperature of the outlet pipeline at 55°C to 68°C, and control the moisture content of the final fiber to 6.0% to 6.5%. The dry moisture content affects whether the ultra-thin fiberboard will burst. If the moisture content is too high, the surface of the ultra-thin fiberboard is prone to bubbling, and if the moisture content is too low, the upper and lower surfaces of the ultra-thin fiberboard are prone to delamination.

Paving:

Lay the fiber into a continuous slab belt by a paving forming machine, and control the paving process with a target board thickness of 0.8mm, a fiberboard density of 1050Kg/m ³ , and a slab belt width of 1250mm. According to the density requirement, the paving machine unloads through the screw unloading device, and the pavement height deviation is ±3mm.

Preload:

The paved slab belt is transported to the pre-pressing machine through the conveyor belt, and the pre-pressing pressure is set at 95bar to 130bar.

Hot pressing:

The pre-pressed slab belt is transported to the hot press machine. The slab entrance is set to 6.8mm. The hot press machine is divided into 4 continuous pressure zones. According to the direction of the slab belt, set the hot pressing temperature in Zone 1 to 175°C , The hot-pressing temperature in Zone 2 is 165°C, the hot-pressing temperature in Zone 3 is 140°C, and the hot-pressing temperature in Zone 4 is 130°C. The hot pressing speed is 105m/min. The pressure in zone 1 is 35bar-50bar, the pressure in zone 2 is 25bar-55bar, the pressure in zone 3 is 55bar-80bar, and the pressure in zone 4 is 120bar-150bar. Performance

Post-processing:

According to needs, the hot-pressed plates are transferred to the turnover frame through the conveyor belt, cooled, and then stacked and packed.

The following examples are provided in accordance with the inventive concept. For the processes not mentioned separately in each embodiment, the preferred methods described in the above-mentioned sections were adopted. The performance index of each embodiment is tested according to the following test methods.

Density measurement: according to GB/T 17657-2013 in 4.2 Density measurement method. Determination of moisture content: according to the determination method of moisture content specified in 4.3 of GB/T17657-2013. Determination of static bending strength and elastic modulus: according to the determination method of static bending strength and elastic modulus specified in 4.7 of GB/T 17657-2013. Determination of internal bonding strength: according to the determination method of internal bonding strength specified in 4.11 of GB/T 17657-2013. Determination of water absorption: according to the 24h water absorption determination method specified in 4.6 of GB/T17657-2013. Formaldehyde release: According to the determination of formaldehyde release in GB18580-2017.

Example 1

The New Zealand radiata pine log material is planed with a planer. After planing, the length and width of the wood chips range from 5 cm to 8 cm, and the thickness is 1 cm to 2 cm. After the planed wood chips are washed and dehydrated, they enter the preheated buffer silo in front of the thermal mill through a closed conveyor belt for temporary storage, and are extruded by a variable diameter screw to form a cork and sent to a vertical digester for cooking and softening treatment. The cooking pressure is 7.5bar, the cooking temperature is 162°C, and the cooking time is 3.5min. The cooked wood chips are sent to a thermal grinder for thermal grinding, and the melted 58# fully refined paraffin wax is added therein in an amount of 8kg/ ^m3 to obtain 50-100 mesh pine fibers, and qualified fibers enter the drying pipeline. The urea-formaldehyde resin glue, ammonium chloride and paraffin are sprayed through their respective metering pipelines to form an impact mixing state with the fiber flow in the pipeline, and the materials are evenly distributed on the fiber surface. The solid content of the urea-formaldehyde resin glue is 51%, The application amount is 12.5%, the ammonium chloride solid content is 20%, the addition ratio is 0.4%, the paraffin wax solid content is 100%, and the addition amount is 0.8%. The fiber is ground by heat grinding and sizing is used to make the fiber dry through the drying system. The temperature of the inlet pipe of the drying system is controlled at 100°C, the temperature of the outlet pipe is controlled at 60°C, and the moisture content of the fiber is 7%. For the slab belt, set the density of the target 0.8mm ultra-thin fiberboard to 1050Kg/m ³ , and the width of the slab belt to 1250mm. According to the density requirements, the paving machine will be unloaded through the screw feeding device, and the paving height deviation will be ±3mm . The paved slab belt is transported to the pre-pressing machine through the conveyor belt, and the pre-pressing pressure is 100bar. The pre-pressed slab belt is transported to the hot press machine. The slab entrance is set at 6.8mm. The hot press machine is divided into 4 continuous pressure zones. According to the direction of the slab belt, set the hot pressing temperature in zone 1 to 175°C and 2 The hot-pressing temperature in zone 165°C, the hot-pressing temperature in zone 3 is 140°C, the hot-pressing temperature in zone 4 is 130°C, the hot-pressing speed is 105m/min, the pressure in zone 1 is 50bar, the pressure in zone 2 is 55bar, the pressure in zone 3 is 80bar, and the pressure in zone 4 is 105m/min. The zone pressure is 150 bar. The hot-pressed plates are transferred to the turnover frame through the conveyor belt, cooled, and then stacked and packed.

Example 2

The New Zealand radiata pine log material is planed with a planer. After planing, the length and width of the wood chips range from 5 cm to 8 cm, and the thickness is 1 cm to 2 cm. After the planed wood chips are washed and dehydrated, they enter the preheated buffer silo in front of the thermal mill through a closed conveyor belt for temporary storage, and are extruded by a variable diameter screw to form a cork and sent to a vertical digester for cooking and softening treatment. The cooking pressure is 8.0bar, the cooking temperature is 160°C, and the cooking time is 4.0min. The cooked wood chips are sent to the thermal grinder for thermal grinding, and the melted 58# fully refined paraffin wax is added to it, and the addition amount is 10kg/ ^m3 to obtain 50-100 mesh pine fibers, and the qualified fibers enter the drying pipeline . The urea-formaldehyde resin glue, ammonium chloride and paraffin are sprayed through their respective metering pipelines to form an impact mixing state with the fiber flow in the pipeline, and the materials are evenly distributed on the fiber surface. The solid content of the urea-formaldehyde resin glue is 51%, The application amount is 12.5%, the ammonium chloride solid content is 20%, the addition ratio is 0.45%, the paraffin wax solid content is 100%, and the addition amount is 0.8%. The fibers produced by heat grinding are dried through the drying system. The temperature of the inlet pipe of the drying system is controlled at 110°C, the temperature of the outlet pipe is controlled at 55°C, and the moisture content of the fiber is 6.7%. Lay the fiber into a continuous slab belt through the paving forming machine, set the density of the target 0.8mm ultra-thin fiberboard to 1050Kg/m ³ , and set the width of the slab belt to 1250mm. For blanking, the pavement height deviation is ±3mm. The paved slab belt is transported to the pre-pressing machine through the conveyor belt, and the pre-pressing pressure is 95bar. The pre-pressed slab belt is transported to the hot press machine. The slab entrance is set at 6.8mm. The hot press machine is divided into 4 continuous pressure zones. According to the direction of the slab belt, set the hot pressing temperature in zone 1 to 175°C and 2 The hot-pressing temperature in zone 165°C, the hot-pressing temperature in zone 3 is 140°C, the hot-pressing temperature in zone 4 is 130°C, the hot-pressing speed is 105m/min, the pressure in zone 1 is 35bar, the pressure in zone 2 is 40bar, the pressure in zone 3 is 55bar, and the pressure in zone 4 is 105m/min. The zone pressure is 130 bar. The hot-pressed plates are transferred to the turnover frame through the conveyor belt, cooled, and then stacked and packed.

Example 3

The New Zealand radiata pine log material is planed with a planer. After planing, the length and width of the wood chips range from 5 cm to 8 cm, and the thickness is 1 cm to 2 cm. After the planed wood chips are washed and dehydrated, they enter the preheated buffer silo in front of the thermal mill through a closed conveyor belt for temporary storage, and are extruded by a variable diameter screw to form a cork and sent to a vertical digester for cooking and softening treatment. The cooking pressure is 7.5bar, the heat grinding temperature is 165°C, and the cooking time is 4.0min. The cooked wood chips are sent to the thermal grinder for thermal grinding, and the melted 58# fully refined paraffin wax is added to it, and the addition amount is 9kg/ ^m3 to obtain 50-100 mesh pine fibers, and the qualified fibers enter the drying pipeline . The urea-formaldehyde resin glue, ammonium chloride and paraffin are sprayed through their respective metering pipelines to form an impact mixing state with the fiber flow in the pipeline, and the materials are evenly distributed on the fiber surface. The solid content of the urea-formaldehyde resin glue is 51%, The application amount is 12.5%, the ammonium chloride solid content is 20%, the addition ratio is 0.5%, the paraffin wax solid content is 100%, and the addition amount is 0.8%. Drying is carried out through the drying system, and the temperature of the inlet pipe of the drying system is controlled at 110°C; the temperature of the outlet pipe is controlled at 68°C, and the moisture content of the fiber is 6.5%. Lay the fiber into a continuous slab belt through the paving forming machine, set the density of the target 0.8mm ultra-thin fiberboard to 1050Kg/m ³ , and set the width of the slab belt to 1250mm. For blanking, the pavement height deviation is ±3mm. The paved slab belt is transported to the pre-pressing machine through the conveyor belt, and the pre-pressing pressure is 130bar. The pre-pressed slab belt is transported to the hot press machine. The slab entrance is set at 6.8mm. The hot press machine is divided into 4 continuous pressure zones. According to the direction of the slab belt, set the hot pressing temperature in zone 1 to 175°C and 2 The hot-pressing temperature in zone 165°C, the hot-pressing temperature in zone 3 is 140°C, the hot-pressing temperature in zone 4 is 130°C, the hot-pressing speed is 105m/min, the pressure in zone 1 is 40bar, the pressure in zone 2 is 25bar, the pressure in zone 3 is 60bar, and the pressure in zone 4 is 105m/min. The zone pressure is 120 bar. The hot-pressed plates are transferred to the turnover frame through the conveyor belt, cooled, and then stacked and packed.

The fiberboards prepared according to Examples 1-3 were tested according to the above test standards, and the results are shown in the following table.

Table 1

It should be understood that the specific embodiments described here are only used to explain related inventions, not to limit the invention. Various modifications can be made to the present invention within the scope defined by the claims. Different implementations or examples, and new deformations obtained by combining common technical means should also be considered to be included within the scope of the present invention.

Claims (10)

1. A preparation method of low-aldehyde ultra-thin fiberboard, It is characterized in that, comprising steps: Cooking treatment: Cook the qualified wood chips, the cooking pressure is 7.5bar~8.0bar, the cooking temperature is 160℃~165℃, and the cooking time is 3.5min~4.0min; Thermal grinding treatment: add melted 58# fully refined paraffin wax to the cooked wood chips and perform thermal grinding to obtain 50-100 mesh wood fibers; Glue sizing treatment: uniformly apply urea-formaldehyde resin glue and additives to the surface of wood fiber in the drying pipeline; Drying treatment: dry the wood fiber after sizing to obtain a paving material with a moisture content of 6.0% to 6.5%; Pavement treatment: Pave the pavement material into a continuous slab strip, set the target plate thickness to 0.8mm, and the fiberboard density to 1050Kg/m ³ ; Hot-pressing treatment: Send the slab belt to a hot-pressing machine for hot-pressing. The hot-pressing machine arranges four continuous pressure zones. According to the advancing direction of the slab belt, the hot-pressing temperature in the four pressure zones is set to gradually decrease, and at least The hot pressing pressure in the three pressure ranges increases gradually, Among them, the slab entrance is set to 6.8mm, and is set according to the advancing direction of the slab belt: the hot-pressing temperature in the first section is 175°C, the hot-pressing temperature in the second section is 165°C, and the hot-pressing temperature in the third section is 140°C, the hot-pressing temperature in the fourth section is 130°C; the hot-pressing pressure in the first section is 35bar-50bar, the hot-pressing pressure in the second section is 25bar-55bar, the hot-pressing pressure in the third section is 55bar-80bar, The hot pressing pressure in the fourth section is 120bar-150bar; the hot pressing speed is 105m/min. 2. preparation method as claimed in claim 1, wherein, The qualified wood chips are wood chips with a length of 5 cm to 8 cm, a width of 5 cm to 8 cm, a thickness of 1 cm to 2 cm, and a moisture content of 55% to 65%. 3. preparation method as claimed in claim 2, wherein, The preparation of the qualified wood chips includes water washing: washing and dehydrating planed chips with a length of 5 cm to 8 cm, a width of 5 cm to 8 cm, and a thickness of 1 cm to 2 cm, and controlling the moisture content of the wood chips to 55% to 65%. 4. preparation method as claimed in claim 3, wherein, The preparation of the qualified wood chips also includes preheating: preheating the washed wood chips, and controlling the preheating temperature at 90°C to 98°C. 5. preparation method as claimed in claim 4, wherein, The preparation of the qualified wood chips also includes pressing treatment: the preheated wood chips are extruded by a variable-diameter screw to form a cork. 6. preparation method as claimed in claim 1, wherein, The amount of 58# fully refined paraffin relative to the volume of the finished fiberboard is 8kg/m ³ -10kg/m ³ . 7. preparation method as claimed in claim 1, wherein, The solid content of the urea-formaldehyde resin glue is 49%-53%, and its application amount is 11%-13% relative to the dry fiber weight. 8. preparation method as claimed in claim 1, wherein, Described auxiliary agent comprises solidifying agent and paraffin, The curing agent is ammonium chloride, and its addition amount is 0.40% to 0.50% relative to the dry fiber weight; The solid content of the paraffin wax is 100%, and its addition amount is 0.7% to 0.9% relative to the dry fiber weight. 9. preparation method as claimed in claim 1, wherein, Before the hot-pressing treatment, pre-pressing treatment is also included: pre-pressing the paved slab belt, and the pre-pressing pressure is 95bar-130bar. 10. A low-aldehyde ultra-thin fiberboard prepared by the preparation method described in any one of claims 1-9.