Production process of MDF low-density high-strength plate
阅读说明：本技术 一种mdf低密度高强度板材生产工艺 (Production process of MDF low-density high-strength plate ) 是由 梁殿伟 陈勇 余文彬 于 2021-09-07 设计创作，主要内容包括：本发明属于人造板生产技术领域,尤其是一种MDF低密度高强度板材生产工艺,解决了现有技术中中密度纤维板密度高,在加工、运输和使用过程中成本相对较高,而低密度纤维板性能指标又无法达到中密度纤维板国家标准的问题,所述MDF低密度高强度板材生产工艺,包括纤维制备-胶黏剂制备-纤维板制备三个步骤。本发明通过分别制备纤维、胶黏剂,最后与空心填料混合后发泡制成所需板材,本发明所用原料节能环保,制备方法简单,制备条件温和,所得的板材性能稳定,其在符合中密度纤维板国家指标(GB/T11718-2009)中干燥状态下使用的家具型中密度纤维板的性能指标要求的同时,板材密度低至0.28g/cm～(3)。(The invention belongs to the technical field of artificial board production, in particular to a production process of an MDF low-density high-strength board, which solves the problems that in the prior art, a medium-density fiberboard has high density, the cost is relatively high in the processes of processing, transportation and use, and the performance index of the low-density fiberboard cannot reach the national standard of the medium-density fiberboard. The raw materials used in the invention are energy-saving and environment-friendly, the preparation method is simple, the preparation condition is mild, the performance of the obtained board is stable, and the density of the board is as low as 0.28g/cm while the board meets the performance index requirement of a furniture type medium-density fiberboard used in a dry state in the national index (GB/T11718-2009) of the medium-density fiberboard 3 。)
1. A production process of an MDF low-density high-strength plate is characterized by comprising the following steps:
s1, preparing fibers:
s11, adding the production raw materials into a chipping machine for chipping to obtain a flaky material with the length of 20-30mm, the thickness of 2-7mm and the width of 10-20 mm;
s12, placing the flaky material in steam at the temperature of 120-140 ℃ for cooking pretreatment, adding treatment liquid with the same mass as the flaky material, stirring and mixing uniformly, grinding, separating and drying until the water content is 3-8% to obtain a treated fiber material;
s2, preparing an adhesive:
s21, adding polymethylene polyphenyl polyisocyanate and epoxy resin into a mixer together, stirring and mixing for 10-18min at the temperature of 70-90 ℃, then cooling to 50-60 ℃, adding polyethylene glycol trimethoxy silicon propyl ether, stirring and mixing uniformly, vacuumizing and removing bubbles to obtain modified epoxy resin;
s22, adding the modified epoxy resin, stearate, mono-alcohol amine, cellulose acetate butyrate and epoxy propyl trimethoxy silane into a high-speed mixer together, and stirring and mixing at the rotating speed of 700 and 900r/min for 20-30min to obtain the required adhesive;
s3, preparing a fiber board:
s31, adding the filler into the treated fiber material obtained in the step S1, fully mixing for 30-50min, uniformly mixing to obtain a mixture, adding the adhesive and azodicarbonamide obtained in the step S2 into the mixture, stirring and mixing for 20-40min at the temperature of 90-110 ℃, uniformly stirring and mixing, and then keeping the temperature, standing and foaming to obtain a foaming material;
s32, sending the foaming material into a paving machine to be paved and molded, then prepressing and hot-pressing to obtain a fiberboard primary product, drying the fiberboard primary product until the moisture content is 4-6%, and finally trimming and molding by a trimming machine to obtain the required MDF low-density high-strength board.
2. The process for producing the MDF low-density high-strength panel according to claim 1, wherein the production raw material in the step S1 is one or more of logging residues, sub-small firewood, crop stalks or bagasse.
3. The process for producing an MDF low-density high-strength panel according to claim 1, wherein the steam pressure in step S1 is 1.5-2.5MPa, and the cooking time is 3-8 min.
4. The process for producing the MDF low-density high-strength board according to claim 1, wherein the treating fluid in the step S1 is prepared by mixing the following raw materials in parts by weight: 15-23 parts of 5-12mol/L sodium hydroxide solution, 4-7 parts of sodium hexametaphosphate, 2-5 parts of zinc acetate, 1-3 parts of zirconium oxide and 2-5 parts of polyethylene wax.
5. The process for producing an MDF low-density high-strength board according to claim 1, wherein the mass ratio of the polymethylene polyphenyl polyisocyanate, the epoxy resin and the polyethylene glycol trimethoxysilylpropyl ether in the step S2 is 3-5:18-25: 1.
6. The process for producing the MDF low-density high-strength board as claimed in claim 1, wherein the mass ratio of the modified epoxy resin, the stearate, the monoalkanolamine, the cellulose acetate butyrate and the epoxypropyltrimethoxysilane in the step S2 is 55-75:3-5:2-3:4-7: 1-3.
7. The process for producing an MDF low-density high-strength board according to claim 1, wherein the filler in step S3 is one or more of hollow magnesium oxide microspheres, hollow calcium carbonate microspheres, hollow silica micropowder microspheres, hollow glass microspheres, or hollow calcium silicate microspheres.
8. The MDF low-density high-strength board production process as claimed in claim 1, wherein the mass ratio of the fiber material, the filler, the adhesive and the azodicarbonamide in the step S3 is 70-90:18-25:12-16: 1-3.
9. The process for producing an MDF low-density high-strength board according to claim 1, wherein the pre-pressing temperature in step S3 is 55 to 75 ℃, the pre-pressing pressure is 2.5 to 3.5MPa, and the pre-pressing time is 15 to 25S.
10. The process for producing an MDF low-density high-strength board as claimed in claim 1, wherein the hot pressing temperature in step S3 is 145-165 ℃, the hot pressing pressure is 6.8-8.8MPa, and the hot pressing time is 80-120S.
Technical Field
The invention relates to the technical field of artificial board production, in particular to a production process of an MDF low-density high-strength board.
Background
The Medium Density Fiberboard (MDF) is prepared by applying urea-formaldehyde resin or other synthetic resin to wood fiber or other plant fiber as raw material, and pressing under heating and pressurizing conditions to obtain a Medium Density Fiberboard (MDF) with a density of 0.50-0.88 g/cm3Other suitable additives may also be added to the board of the range to improve board properties. The medium-density fiberboard has good physical and mechanical properties and processability, can be made into boards with different thicknesses, and is widely used in furniture manufacturing industry, building industry and indoor decoration industry. The medium density fiberboard is a homogeneous porous material, has good acoustic performance, and is a good material for manufacturing sound boxes, television shells and musical instruments. In addition, the wood-plastic composite board can replace natural wood to be used for ships, vehicles, sports equipment, floors, wallboards, partition boards and the like, and has the characteristics of simple processing, high utilization rate and economy compared with the natural wood.
The density of the medium-density fiberboard produced and sold in China is 0.50-0.88 g/cm3This density range of fiberboard, due to its high density, is relatively costly to process, transport, and use. With the shortage of wood resources and the increase of the demand of artificial boards on raw materials, the production and use of low-density fiberboards gradually become a development trend. Low-density fiberboard on the market is usually prepared by using a production line of medium-density fiberboard, for example, Chinese patent CN101229649A discloses a low-density fiberboard and a preparation method thereof, the density of the fiberboard is 250-450 kg/cubic meter, and the preparation method of the low-density fiberboard comprises wood chippingThe method comprises the steps of fiber preparation, fiber sizing, fiber paving, prepressing, hot pressing, rough board treatment and the like, wherein the fiber and an adhesive are added according to the weight ratio of 1: 1.6-3 when the fiber is sized, and the low-density fiberboard produced by applying the method is mainly used as a filling material. The performance index of the low-density fiberboard can not reach the performance requirement index of the furniture type medium-density fiberboard used in a dry state in the national standard of medium-density fiberboard (GB/T11718-. Based on the statement, the invention provides a production process of the MDF low-density high-strength plate.
Disclosure of Invention
The invention aims to solve the problems that in the prior art, a medium-density fiberboard has high density and relatively high cost in the processes of processing, transportation and use, and the performance index of a low-density fiberboard cannot reach the national standard of the medium-density fiberboard, and provides a production process of an MDF low-density high-strength board.
A production process of an MDF low-density high-strength plate comprises the following steps:
s1, preparing fibers:
s11, adding the production raw materials into a chipping machine for chipping to obtain a flaky material with the length of 20-30mm, the thickness of 2-7mm and the width of 10-20 mm;
s12, placing the flaky material in steam at the temperature of 120-140 ℃ for cooking pretreatment, adding treatment liquid with the same mass as the flaky material, stirring and mixing uniformly, grinding, separating and drying until the water content is 3-8% to obtain a treated fiber material;
s2, preparing an adhesive:
s21, adding polymethylene polyphenyl polyisocyanate and epoxy resin into a mixer together, stirring and mixing for 10-18min at the temperature of 70-90 ℃, then cooling to 50-60 ℃, adding polyethylene glycol trimethoxy silicon propyl ether, stirring and mixing uniformly, vacuumizing and removing bubbles to obtain modified epoxy resin;
s22, adding the modified epoxy resin, stearate, mono-alcohol amine, cellulose acetate butyrate and epoxy propyl trimethoxy silane into a high-speed mixer together, and stirring and mixing at the rotating speed of 700 and 900r/min for 20-30min to obtain the required adhesive;
s3, preparing a fiber board:
s31, adding the filler into the treated fiber material obtained in the step S1, fully mixing for 30-50min, uniformly mixing to obtain a mixture, adding the adhesive and azodicarbonamide obtained in the step S2 into the mixture, stirring and mixing for 20-40min at the temperature of 90-110 ℃, uniformly stirring and mixing, and then keeping the temperature, standing and foaming to obtain a foaming material;
s32, sending the foaming material into a paving machine to be paved and molded, then prepressing and hot-pressing to obtain a fiberboard primary product, drying the fiberboard primary product until the moisture content is 4-6%, and finally trimming and molding by a trimming machine to obtain the required MDF low-density high-strength board.
Preferably, the production raw material in the step S1 is one or more of logging residues, minor firewood, crop straws or bagasse.
Preferably, the steam pressure in the step S1 is 1.5-2.5MPa, and the cooking time is 3-8 min.
Preferably, the treatment solution in step S1 is prepared by mixing the following raw materials in parts by weight: 15-23 parts of 5-12mol/L sodium hydroxide solution, 4-7 parts of sodium hexametaphosphate, 2-5 parts of zinc acetate, 1-3 parts of zirconium oxide and 2-5 parts of polyethylene wax.
Preferably, the mass ratio of the polymethylene polyphenyl polyisocyanate, the epoxy resin and the polyethylene glycol trimethoxy silicon propyl ether in the step S2 is 3-5:18-25: 1.
Preferably, the mass ratio of the modified epoxy resin, the stearate, the monoalkanolamine, the cellulose acetate butyrate and the epoxypropyltrimethoxysilane in the step S2 is 55-75:3-5:2-3:4-7: 1-3.
Preferably, the filler in step S3 is one or more of hollow magnesium oxide microspheres, hollow calcium carbonate microspheres, hollow silica micro powder microspheres, hollow glass microspheres, or hollow calcium silicate microspheres.
Preferably, the mass ratio of the fiber material, the filler, the adhesive and the azodicarbonamide in the step S3 is 70-90:18-25:12-16: 1-3.
Preferably, the pre-pressing temperature in the step S3 is 55-75 ℃, the pre-pressing pressure is 2.5-3.5MPa, and the pre-pressing time is 15-25S.
Preferably, the hot pressing temperature in the step S3 is 145-165 ℃, the hot pressing pressure is 6.8-8.8MPa, and the hot pressing time is 80-120S.
The production process of the MDF low-density high-strength plate provided by the invention has the following beneficial effects:
1. the required MDF low-density high-strength board is prepared by respectively preparing the fibers and the adhesive, finally mixing the fibers and the adhesive with the hollow filler and foaming the mixture, the raw materials used in the invention are energy-saving and environment-friendly, the preparation method is simple, the preparation conditions are mild, the performance of the obtained board is stable, and the density of the board is as low as 0.28g/cm while the board meets the performance index requirement of a furniture type medium-density fiberboard used in a dry state in the national index (GB/T11718-3And the cost of the plate in the processes of processing, transporting and using is greatly reduced.
2. According to the invention, after the production raw materials are subjected to cooking pretreatment, the treatment liquid is added for grinding treatment, so that the dispersibility, toughness and processability of the obtained modified fiber material are greatly improved; compared with the existing adhesive, the self-made adhesive is safer and more environment-friendly, has strong viscosity, good stability and high peel strength, is mixed with fiber materials and fillers for foaming to prepare the required plate, and greatly improves the strength of the plate.
Detailed Description
The present invention will be further illustrated with reference to the following specific examples.
Example one
The invention provides a production process of an MDF low-density high-strength plate, which comprises the following steps:
s1, preparing fibers:
s11, adding the felling residues of the production raw materials and the minor firewood into a chipping machine together for chipping to obtain a flaky material with the length of 20mm, the thickness of 2mm and the width of 10 mm;
s12, placing the flaky material in steam at the temperature of 120 ℃ and under the pressure of 1.5MPa for stewing pretreatment for 3min, adding treatment liquid with the same mass as the flaky material, stirring and mixing uniformly, grinding, separating and drying until the water content is 3% to obtain a treated fiber material;
the treatment fluid is prepared by mixing the following raw materials in parts by weight: 15 parts of 5mol/L sodium hydroxide solution, 4 parts of sodium hexametaphosphate, 2 parts of zinc acetate, 1 part of zirconium oxide and 2 parts of polyethylene wax;
s2, preparing an adhesive:
s21, adding polymethylene polyphenyl polyisocyanate and epoxy resin into a mixing machine together, stirring and mixing for 10min at the temperature of 70 ℃, then cooling to 50 ℃, adding polyethylene glycol trimethoxy silicon propyl ether, stirring and mixing uniformly, vacuumizing and removing bubbles to obtain modified epoxy resin;
the mass ratio of the polymethylene polyphenyl polyisocyanate to the epoxy resin to the polyethylene glycol trimethoxy silicon propyl ether is 3:18: 1;
s22, adding the modified epoxy resin, stearate, mono-alcohol amine, cellulose acetate butyrate and epoxy propyl trimethoxy silane into a high-speed mixer together, and stirring and mixing at the rotating speed of 700r/min for 20min to obtain the required adhesive;
the mass ratio of the modified epoxy resin to the stearate to the mono-alcohol amine to the cellulose acetate butyrate to the epoxy propyl trimethoxy silane is 55:3:2:4: 1;
s3, preparing a fiber board:
s31, fully mixing the treated fiber material prepared in the step S1 with filler hollow magnesium oxide microspheres for 30min, uniformly mixing to obtain a mixture, adding the adhesive and azodicarbonamide prepared in the step S2 into the mixture, stirring and mixing for 20min at the temperature of 90 ℃, uniformly stirring and mixing, and then keeping the temperature, standing and foaming to obtain a foaming material;
the mass ratio of the fiber material to the filler to the adhesive to the azodicarbonamide is 70:18:12: 1;
s32, sending the foaming material into a paving machine for paving and forming, then prepressing and hot-pressing to obtain a fiberboard primary product, drying the fiberboard primary product until the moisture content is 4%, and finally repairing and forming by a trimming machine to obtain the required MDF low-density high-strength board;
the prepressing temperature is 55 ℃, the prepressing pressure is 2.5MPa, and the prepressing time is 15 s; the hot pressing temperature is 145 ℃, the hot pressing pressure is 6.8MPa, and the hot pressing time is 80 s.
Example two
The invention provides a production process of an MDF low-density high-strength plate, which comprises the following steps:
s1, preparing fibers:
s11, adding crop straws and bagasse as production raw materials into a chipping machine for chipping to obtain a flaky material with the length of 22mm, the thickness of 3mm and the width of 12 mm;
s12, placing the flaky material in steam at 125 ℃ and 1.8MPa for cooking pretreatment for 4min, adding treatment liquid with the same mass as the flaky material, stirring and mixing uniformly, grinding, separating and drying until the water content is 4% to obtain a treated fiber material;
the treatment fluid is prepared by mixing the following raw materials in parts by weight: 16 parts of 6mol/L sodium hydroxide solution, 5 parts of sodium hexametaphosphate, 3 parts of zinc acetate, 1.5 parts of zirconium oxide and 3 parts of polyethylene wax;
s2, preparing an adhesive:
s21, adding polymethylene polyphenyl polyisocyanate and epoxy resin into a mixing machine together, stirring and mixing for 12min at the temperature of 75 ℃, then cooling to 52 ℃, adding polyethylene glycol trimethoxy silicon propyl ether, stirring and mixing uniformly, vacuumizing and removing bubbles to obtain modified epoxy resin;
the mass ratio of the polymethylene polyphenyl polyisocyanate to the epoxy resin to the polyethylene glycol trimethoxy silicon propyl ether is 3.5:20: 1;
s22, adding the modified epoxy resin, stearate, mono-alcohol amine, cellulose acetate butyrate and epoxy propyl trimethoxy silane into a high-speed mixer together, and stirring and mixing for 22min at the rotating speed of 750r/min to obtain the required adhesive;
the mass ratio of the modified epoxy resin to the stearate to the mono-alcohol amine to the cellulose acetate butyrate to the epoxy propyl trimethoxy silane is 60:3.5:2.2:5: 1.5;
s3, preparing a fiber board:
s31, fully mixing the treated fiber material prepared in the step S1 with filler hollow calcium carbonate microspheres for 35min, uniformly mixing to obtain a mixture, adding the adhesive and azodicarbonamide prepared in the step S2 into the mixture, stirring and mixing for 25min at the temperature of 95 ℃, uniformly stirring and mixing, and then keeping the temperature, standing and foaming to obtain a foaming material;
the mass ratio of the fiber material to the filler to the adhesive to the azodicarbonamide is 75:20:13: 1.5;
s32, sending the foaming material into a paving machine for paving and forming, then prepressing and hot-pressing to obtain a fiberboard primary product, drying the fiberboard primary product until the moisture content is 4.5%, and finally trimming and forming by a trimming machine to obtain the required MDF low-density high-strength board;
the prepressing temperature is 60 ℃, the prepressing pressure is 2.8MPa, and the prepressing time is 18 s; the hot pressing temperature is 150 ℃, the hot pressing pressure is 7.2MPa, and the hot pressing time is 90 s.
EXAMPLE III
The invention provides a production process of an MDF low-density high-strength plate, which comprises the following steps:
s1, preparing fibers:
s11, adding the felling residues of the production raw materials and the crop straws into a chipping machine for chipping to obtain a flaky material with the length of 25mm, the thickness of 4mm and the width of 15 mm;
s12, placing the flaky material in steam at the temperature of 130 ℃ and under the pressure of 2MPa for cooking pretreatment for 5min, then adding treatment liquid with the same mass as the flaky material, stirring and mixing uniformly, grinding, separating and drying until the water content is 5% to obtain a treated fiber material;
the treatment fluid is prepared by mixing the following raw materials in parts by weight: 18 parts of 8mol/L sodium hydroxide solution, 5.5 parts of sodium hexametaphosphate, 3.5 parts of zinc acetate, 2 parts of zirconium oxide and 3.5 parts of polyethylene wax;
s2, preparing an adhesive:
s21, adding polymethylene polyphenyl polyisocyanate and epoxy resin into a mixing machine together, stirring and mixing for 14min at the temperature of 80 ℃, then cooling to 55 ℃, adding polyethylene glycol trimethoxy silicon propyl ether, stirring and mixing uniformly, vacuumizing and removing bubbles to obtain modified epoxy resin;
the mass ratio of the polymethylene polyphenyl polyisocyanate to the epoxy resin to the polyethylene glycol trimethoxy silicon propyl ether is 4:22: 1;
s22, adding the modified epoxy resin, stearate, mono-alcohol amine, cellulose acetate butyrate and epoxy propyl trimethoxy silane into a high-speed mixer together, and stirring and mixing at the rotating speed of 800r/min for 25min to obtain the required adhesive;
the mass ratio of the modified epoxy resin to the stearate to the mono-alcohol amine to the cellulose acetate butyrate to the epoxy propyl trimethoxy silane is 65:4:2.5:5.5: 2;
s3, preparing a fiber board:
s31, fully mixing the treated fiber material prepared in the step S1 with filler hollow silica micro powder microspheres for 40min, uniformly mixing to obtain a mixture, adding the adhesive prepared in the step S2 and azodicarbonamide into the mixture, stirring and mixing for 30min at the temperature of 100 ℃, uniformly stirring and mixing, and then keeping the temperature, standing and foaming to obtain a foaming material;
the mass ratio of the fiber material to the filler to the adhesive to the azodicarbonamide is 40:11:7: 1;
s32, sending the foaming material into a paving machine for paving and forming, then prepressing and hot-pressing to obtain a fiberboard primary product, drying the fiberboard primary product until the moisture content is 5%, and finally repairing and forming by a trimming machine to obtain the required MDF low-density high-strength board;
the prepressing temperature is 65 ℃, the prepressing pressure is 3MPa, and the prepressing time is 20 s; the hot pressing temperature is 155 ℃, the hot pressing pressure is 7.8MPa, and the hot pressing time is 100 s.
Example four
The invention provides a production process of an MDF low-density high-strength plate, which comprises the following steps:
s1, preparing fibers:
s11, adding the production raw materials of the minor firewood and the bagasse into a chipping machine for chipping to obtain a flaky material with the length of 28mm, the thickness of 6mm and the width of 18 mm;
s12, placing the flaky material in steam at the temperature of 135 ℃ and under the pressure of 2.2MPa for stewing pretreatment for 7min, adding treatment liquid with the same mass as the flaky material, stirring and mixing uniformly, grinding, separating and drying until the water content is 7% to obtain a treated fiber material;
the treatment fluid is prepared by mixing the following raw materials in parts by weight: 22 parts of 5-12mol/L sodium hydroxide solution, 6 parts of sodium hexametaphosphate, 4 parts of zinc acetate, 2.5 parts of zirconia and 4 parts of polyethylene wax;
s2, preparing an adhesive:
s21, adding polymethylene polyphenyl polyisocyanate and epoxy resin into a mixing machine together, stirring and mixing for 16min at the temperature of 85 ℃, then cooling to 58 ℃, adding polyethylene glycol trimethoxy silicon propyl ether, stirring and mixing uniformly, vacuumizing and removing bubbles to obtain modified epoxy resin;
the mass ratio of the polymethylene polyphenyl polyisocyanate to the epoxy resin to the polyethylene glycol trimethoxy silicon propyl ether is 4.5:24: 1;
s22, adding the modified epoxy resin, stearate, mono-alcohol amine, cellulose acetate butyrate and epoxy propyl trimethoxy silane into a high-speed mixer together, and stirring and mixing for 28min at the rotating speed of 850r/min to obtain the required adhesive;
the mass ratio of the modified epoxy resin to the stearate to the mono-alcohol amine to the cellulose acetate butyrate to the epoxy propyl trimethoxy silane is 70:4.5:2.8:6: 2.5;
s3, preparing a fiber board:
s31, fully mixing the treated fiber material prepared in the step S1 with filler hollow glass beads for 45min, uniformly mixing to obtain a mixture, adding the adhesive and azodicarbonamide prepared in the step S2 into the mixture, stirring and mixing for 35min at the temperature of 105 ℃, uniformly stirring and mixing, and then preserving heat, standing and foaming to obtain a foaming material;
the mass ratio of the fiber material to the filler to the adhesive to the azodicarbonamide is 85:24:15: 2.5;
s32, sending the foaming material into a paving machine for paving and forming, then prepressing and hot-pressing to obtain a fiberboard primary product, drying the fiberboard primary product until the moisture content is 4-6%, and finally trimming and forming by a trimming machine to obtain the required MDF low-density high-strength board;
the prepressing temperature is 70 ℃, the prepressing pressure is 3.2MPa, and the prepressing time is 22 s; the hot pressing temperature is 160 ℃, the hot pressing pressure is 8.2MPa, and the hot pressing time is 110 s.
EXAMPLE five
The invention provides a production process of an MDF low-density high-strength plate, which comprises the following steps:
s1, preparing fibers:
s11, adding the felling residues and bagasse as the production raw materials into a chipping machine for chipping to obtain a flaky material with the length of 30mm, the thickness of 7mm and the width of 20 mm;
s12, placing the flaky material in steam at the temperature of 140 ℃ and under the pressure of 2.5MPa for cooking pretreatment for 8min, adding treatment liquid with the same mass as the flaky material, stirring and mixing uniformly, grinding, separating and drying until the water content is 8% to obtain a treated fiber material;
the treatment fluid is prepared by mixing the following raw materials in parts by weight: 23 parts of sodium hydroxide solution with the concentration of 12mol/L, 7 parts of sodium hexametaphosphate, 5 parts of zinc acetate, 3 parts of zirconium oxide and 5 parts of polyethylene wax;
s2, preparing an adhesive:
s21, adding polymethylene polyphenyl polyisocyanate and epoxy resin into a mixing machine together, stirring and mixing for 18min at the temperature of 90 ℃, then cooling to 60 ℃, adding polyethylene glycol trimethoxy silicon propyl ether, stirring and mixing uniformly, vacuumizing and removing bubbles to obtain modified epoxy resin;
the mass ratio of the polymethylene polyphenyl polyisocyanate to the epoxy resin to the polyethylene glycol trimethoxy silicon propyl ether is 5:25: 1;
s22, adding the modified epoxy resin, stearate, mono-alcohol amine, cellulose acetate butyrate and epoxy propyl trimethoxy silane into a high-speed mixer together, and stirring and mixing for 30min at the rotating speed of 900r/min to obtain the required adhesive;
the mass ratio of the modified epoxy resin to the stearate to the mono-alcohol amine to the cellulose acetate butyrate to the epoxy propyl trimethoxy silane is 75:5:3:7: 3;
s3, preparing a fiber board:
s31, fully mixing the treated fiber material prepared in the step S1 with filler hollow calcium silicate microspheres for 50min, uniformly mixing to obtain a mixture, adding the adhesive and azodicarbonamide prepared in the step S2 into the mixture, stirring and mixing for 40min at the temperature of 110 ℃, uniformly stirring and mixing, and then keeping the temperature, standing and foaming to obtain a foaming material;
the mass ratio of the fiber material to the filler to the adhesive to the azodicarbonamide is 90:25:16: 3;
s32, sending the foaming material into a paving machine for paving and forming, then prepressing and hot-pressing to obtain a fiberboard primary product, drying the fiberboard primary product until the moisture content is 6%, and finally repairing and forming by a trimming machine to obtain the required MDF low-density high-strength board;
the prepressing temperature is 75 ℃, the prepressing pressure is 3.5MPa, and the prepressing time is 25 s; the hot pressing temperature is 165 ℃, the hot pressing pressure is 8.8MPa, and the hot pressing time is 120 s.
Comparative example 1
The invention provides a production process of an MDF low-density high-strength plate, which comprises the following steps:
s1, preparing fibers:
s11, adding the felling residues of the production raw materials and the minor firewood into a chipping machine together for chipping to obtain a flaky material with the length of 20mm, the thickness of 2mm and the width of 10 mm;
s12, placing the flaky material in steam at the temperature of 120 ℃ and the pressure of 1.5MPa for cooking for 3min, adding water with the same mass as the flaky material, stirring and mixing uniformly, grinding, separating and drying until the water content is 3% to obtain a treated fiber material;
s2, preparing an adhesive:
s21, adding polymethylene polyphenyl polyisocyanate and epoxy resin into a mixing machine together, stirring and mixing for 10min at the temperature of 70 ℃, then cooling to 50 ℃, adding polyethylene glycol trimethoxy silicon propyl ether, stirring and mixing uniformly, vacuumizing and removing bubbles to obtain modified epoxy resin;
the mass ratio of the polymethylene polyphenyl polyisocyanate to the epoxy resin to the polyethylene glycol trimethoxy silicon propyl ether is 3:18: 1;
s22, adding the modified epoxy resin, stearate, mono-alcohol amine, cellulose acetate butyrate and epoxy propyl trimethoxy silane into a high-speed mixer together, and stirring and mixing at the rotating speed of 700r/min for 20min to obtain the required adhesive;
the mass ratio of the modified epoxy resin to the stearate to the mono-alcohol amine to the cellulose acetate butyrate to the epoxy propyl trimethoxy silane is 55:3:2:4: 1;
s3, preparing a fiber board:
s31, fully mixing the treated fiber material prepared in the step S1 with filler hollow magnesium oxide microspheres for 30min, uniformly mixing to obtain a mixture, adding the adhesive and azodicarbonamide prepared in the step S2 into the mixture, stirring and mixing for 20min at the temperature of 90 ℃, uniformly stirring and mixing, and then keeping the temperature, standing and foaming to obtain a foaming material;
the mass ratio of the fiber material to the filler to the adhesive to the azodicarbonamide is 70:18:12: 1;
s32, sending the foaming material into a paving machine for paving and forming, then prepressing and hot-pressing to obtain a fiberboard primary product, drying the fiberboard primary product until the moisture content is 4%, and finally repairing and forming by a trimming machine to obtain the required MDF low-density high-strength board;
the prepressing temperature is 55 ℃, the prepressing pressure is 2.5MPa, and the prepressing time is 15 s; the hot pressing temperature is 145 ℃, the hot pressing pressure is 6.8MPa, and the hot pressing time is 80 s.
Comparative example No. two
The invention provides a production process of an MDF low-density high-strength plate, which comprises the following steps:
s1, preparing fibers:
s11, adding the felling residues of the production raw materials and the minor firewood into a chipping machine together for chipping to obtain a flaky material with the length of 20mm, the thickness of 2mm and the width of 10 mm;
s12, placing the flaky material in steam at the temperature of 120 ℃ and under the pressure of 1.5MPa for stewing pretreatment for 3min, adding treatment liquid with the same mass as the flaky material, stirring and mixing uniformly, grinding, separating and drying until the water content is 3% to obtain a treated fiber material;
the treatment fluid is prepared by mixing the following raw materials in parts by weight: 15 parts of 5mol/L sodium hydroxide solution, 4 parts of sodium hexametaphosphate, 2 parts of zinc acetate, 1 part of zirconium oxide and 2 parts of polyethylene wax;
s2, preparing an adhesive:
adding epoxy resin, stearate, mono-alcohol amine, cellulose acetate butyrate and epoxy propyl trimethoxy silane into a high-speed mixer together, and stirring and mixing at the rotating speed of 700r/min for 20min to obtain the required adhesive;
the mass ratio of the epoxy resin to the stearate to the mono-alcohol amine to the cellulose acetate butyrate to the epoxy propyl trimethoxy silane is 55:3:2:4: 1;
s3, preparing a fiber board:
s31, fully mixing the treated fiber material prepared in the step S1 with filler hollow magnesium oxide microspheres for 30min, uniformly mixing to obtain a mixture, adding the adhesive and azodicarbonamide prepared in the step S2 into the mixture, stirring and mixing for 20min at the temperature of 90 ℃, uniformly stirring and mixing, and then keeping the temperature, standing and foaming to obtain a foaming material;
the mass ratio of the fiber material to the filler to the adhesive to the azodicarbonamide is 70:18:12: 1;
s32, sending the foaming material into a paving machine for paving and forming, then prepressing and hot-pressing to obtain a fiberboard primary product, drying the fiberboard primary product until the moisture content is 4%, and finally repairing and forming by a trimming machine to obtain the required MDF low-density high-strength board;
the prepressing temperature is 55 ℃, the prepressing pressure is 2.5MPa, and the prepressing time is 15 s; the hot pressing temperature is 145 ℃, the hot pressing pressure is 6.8MPa, and the hot pressing time is 80 s.
According to the national standard (GB/T11718-:
the above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.