CN113910405B

CN113910405B - Preparation method of biomass fiberboard based on spherical polymer

Info

Publication number: CN113910405B
Application number: CN202111157282.2A
Authority: CN
Inventors: 刘池伟; 陆昌余; 郭海涛; 赵红阳; 吴淳生
Original assignee: Fuyang Dake New Material Co ltd
Current assignee: Fuyang Dake New Material Co ltd
Priority date: 2021-09-30
Filing date: 2021-09-30
Publication date: 2022-06-21
Anticipated expiration: 2041-09-30
Also published as: CN113910405A

Abstract

The invention discloses a preparation method of a biomass fiberboard based on a spherical polymer, which relates to the technical field of biomass fiberboard processing, and specifically comprises the following steps: firstly, preparing a polymer into a quasi-spherical structure, then reducing the quasi-spherical polymer surface to generate nano silver, dispersing the formed composite polymer in emulsion, impregnating the emulsion into biomass fibers through vacuum pressurization, and preparing the fiber board through hot press molding. According to the preparation method of the fiberboard, the biomass fiber is treated, so that the hot pressing time and the hot pressing pressure in the hot pressing process are reduced, the purposes of improving the production efficiency of the fiberboard and reducing the energy consumption are achieved, the obtained performance data of the fiberboard is excellent, and the processing requirements on the current market are met.

Description

Preparation method of biomass fiberboard based on spherical polymer

Technical Field

The invention belongs to the technical field of biomass fiber board processing, and particularly relates to a preparation method of a biomass fiber board based on a spherical polymer.

Background

China is the first country for producing fiberboards in the world, and the fiberboards are widely applied to the fields of furniture, floor base materials and the like due to the characteristics of uniform and fine materials, excellent machining and finishing performances and the like. The fiber board is an artificial thin board made of wood fiber or other plant cellulose fiber as raw material and urea formaldehyde resin or other suitable adhesives. The novel environment-friendly material is widely applied to the fields of high-grade shoe materials, automotive interior, high-grade packaging and the like. During the manufacturing process, adhesives and/or additives may be applied. The fiber board has the advantages of uniform material, small longitudinal and transverse strength difference, difficult cracking and the like, and has wide application. The 1 cubic meter fiberboard needs 2.5 to 3 cubic meters of wood to replace 3 cubic meters of sawn timber or 5 cubic meters of log, and the development of the fiberboard production is an effective way for the comprehensive utilization of resources.

In the processing process of the fiber board, the hot pressing process is particularly important, and the time of the hot pressing process is directly related to the mechanical property of the fiber board. Because the main raw material of the fiberboard is biomass fiber which generally has excellent toughness and can generate elastic deformation under the action of external force, when the biomass fiber is subjected to hot pressing, the biomass fiber needs to generate permanent deformation by adopting larger pressure and longer hot pressing time. Therefore, when the fiberboard is prepared by processing the biomass fiber, the conditions of the hot pressing process are strict so as to enable the fiberboard to achieve the optimal mechanical property, and hot pressing treatment is generally required to be carried out for about 10min under 5-10 MPa. For example, Chinese patent CN2018112557048 discloses a medium density fiberboard prepared by using cellulosic ethanol waste residue and a preparation method thereof, in the technical process, the pressure of a hot pressing process is 8-10MPa, and the hot pressing time is 5-10 min; for another example, chinese patent CN2021100092855 discloses a method for preparing a moisture-proof and water-proof fiberboard, in which the pressure of the hot pressing process is 10MPa, and the hot pressing time is 6 min. Therefore, in the prior art, the defects of large hot-pressing pressure and time effect of the fiber board generally exist, so that the production efficiency of the fiber board is low, and the energy consumption is large.

Disclosure of Invention

The invention aims to solve the existing problems and provides a preparation method of a biomass fiberboard based on a spherical polymer, which is used for shortening the subsequent hot pressing time and reducing the hot pressing pressure by treating biomass fibers so as to achieve the aims of improving the production efficiency of the fiberboard and reducing the energy consumption.

The invention is realized by the following technical scheme:

a method for preparing a spherical polymer-based biomass fiberboard, comprising the following steps: firstly, preparing a polymer into a quasi-spherical structure, then reducing the quasi-spherical polymer surface to generate nano silver, dispersing the formed composite polymer in emulsion, impregnating the emulsion into biomass fibers through vacuum pressurization, and preparing the fiber board through hot press molding.

Specifically, the preparation method comprises the following steps:

1) taking diethylenetriamine and methyl acrylate as raw materials, and synthesizing and preparing a polyamide polymer with a quasi-spherical structure by a polycondensation method;

2) using polyamide polymer and silver nitrate aqueous solution as raw materials, and reducing the raw materials on the surface by a chemical reduction method to generate nano silver particles so as to obtain a composite polyamide polymer;

3) dispersing the composite polyamide polymer in acrylic emulsion to form a treatment solution, and drying the biomass fiber after dipping the treatment solution;

4) and spraying an adhesive on the surface of the dried biomass fiber, and carrying out hot press molding to obtain the fiberboard.

In a specific embodiment, in step 1), the mass ratio of diethylenetriamine to methyl acrylate is 51.6-82.5: 43.0-68.8.

In a specific embodiment, in step 1), the diethylenetriamine is cooled in an ice-water bath before use.

In a specific embodiment, in step 1), the solvent in the polycondensation reaction system is methanol solution.

Further, the ratio of the methanol solution to the methyl acrylate is 100-160mL:43.0-68.8 g.

In a specific embodiment, in the step 1), the polycondensation reaction system is reacted at normal temperature for 4-6h, then methanol is removed under reduced pressure, and the temperature is raised to 150-.

In one embodiment, in step 2), the polyamide polymer is dissolved in deionized water to form a mother liquor before use.

Further, the volume of the mother liquor is 50-80 mL.

In a specific embodiment, in step 2), the concentration of the aqueous silver nitrate solution is 0.1 to 0.18 mol/L.

In a specific embodiment, in the step 2), the volume ratio of the mother liquor to the silver nitrate aqueous solution is 50-80: 0.5-0.8.

In a specific embodiment, in the step 2), the silver nitrate aqueous solution is dropwise added into the mother liquor, and stirring is carried out while dropwise adding.

In a specific embodiment, in the step 2), the molar ratio of the amino groups to the silver ions in the polyamide polymer in the mixed solution formed by the aqueous silver nitrate solution and the mother liquor is 2-5: 1.

In a specific embodiment, in step 2), the mixed solution is heated to boiling on an electric furnace, and after the mixed solution becomes bright yellow, the heating is stopped and the mixed solution is cooled to room temperature.

In a specific embodiment, in step 2), the solvent is further removed by a rotary evaporator after the mixed solution is cooled.

In a specific embodiment, in step 2), the mixed solution is subjected to a freeze-drying treatment after being subjected to a rotary evaporation treatment.

Further, the freeze drying process conditions are that the freeze drying is carried out for 15-20h at the temperature of-15 ℃ to-25 ℃ and under the condition of 10-30 Pa.

In a specific embodiment, in step 3), the acrylic emulsion has a solids content of 41 to 43%.

In a specific embodiment, in step 3), the composite polyamide polymer is dispersed in the acrylic emulsion by ultrasound.

Further, the power of the ultrasonic dispersion is 300-400W, and the dispersion time is 15-25 min.

In a specific embodiment, in the step 3), the composite polyamide polymer is contained in the treatment liquid in an amount of 8 to 13% by mass.

In a particular embodiment, in step 3), the biomass fibers are selected from: any one or more of wood fiber, bamboo fiber, straw, wheat straw, corn stalk, cotton stalk, reed and awn stalk.

In a specific embodiment, in the step 3), the biomass fiber is immersed in the treatment solution by putting the biomass fiber into a reactor, vacuumizing, adding the treatment solution, and pressurizing and maintaining.

Further, putting the biomass fiber into a reactor, vacuumizing for 0.4-0.6h, injecting the treatment liquid, pressurizing to 1.0-2.5MPa, and keeping for 0.3-0.5 h.

In a specific embodiment, in the step 3), the drying temperature is 70-80 ℃, and the drying time is 3-6 h.

In a specific embodiment, in the step 4), the adhesive accounts for 11-15% of the mass of the biomass fibers.

In a specific embodiment, in the step 4), the adhesive is urea-formaldehyde resin adhesive, the solid content is 50-55%, and the free formaldehyde content is less than 0.1%.

In a specific embodiment, in the step 4), an ammonium chloride solution which accounts for 1.0-1.5% of the solid content of the adhesive and has a mass fraction of 25-28% is applied as a curing agent before the adhesive is used.

In a particular embodiment, in step 4), the sizing of the adhesive is carried out by spraying the sizing using a pressure spray gun.

In a specific embodiment, in step 4), the sized biomass fibers are dried using a hot air duct.

In a specific embodiment, in the step 4), the biomass fiber after sizing is dried until the water content is 6.5-7.5%.

In a specific embodiment, in the step 4), the hot-press molding is performed by paving and molding the dried biomass fiber, and then hot-pressing at 180-.

Compared with the prior art, the invention has the following advantages:

firstly, in the invention, diethylenetriamine and methyl acrylate are used as raw materials, a polyamide polymer with a quasi-spherical structure is synthesized by a polycondensation method, and is infiltrated into biomass fibers in a vacuum pressure impregnation mode, the polyamide polymer with the spherical structure can be enriched on the surface of the biomass fiber to form an aggregate, and when the fiber board is subjected to hot pressing, under the action of external pressure, the formed aggregate is easy to move along with the direction of pressure, and the pressure surface is enriched in a short time, so that the contact surface between the biomass fibers forms sliding and rolling friction, thereby reducing the friction force among the biomass fibers, ensuring that the biomass fibers are easy to displace, therefore, the biomass fibers are easy to slide and displace on the pressed surface, and the biomass fibers are easy to be pressed and molded in the hot pressing process, so that the hot pressing efficiency of the fiberboard is improved.

Secondly, in the invention, in order to better enrich the polyamide polymer on the surface of the biomass fiber, the chemical reduction method is utilized to deposit and form nano silver particles on the surface of the polyamide polymer, and the deposited nano silver particles increase the roughness of the surface of the polyamide polymer, so that the contact area between the polyamide polymer and the biomass fiber is increased, the bonding strength between the polyamide polymer and the biomass fiber is improved, a large amount of polyamide polymer can be better enriched on the surface of the biomass fiber, and the surface of the biomass fiber can form an aggregate of the polymer with the spherical structure conveniently.

Thirdly, in the invention, the polyamide polymer with the spherical structure is enriched on the surface of the biomass fiber, when the biomass fiber is subjected to hot pressing treatment, the biomass fiber slides and displaces, and the polyamide polymer enriched on the surface migrates into pores under the action of external force, so that the effects of filling and sealing the pore structure in the fiber board are achieved, the densification effect is generated, and the mechanical property of the fiber board is improved.

Detailed Description

Example 1

The biomass fiber is selected from wood fiber, preferably eucalyptus fiber.

A preparation method of a biomass fiberboard based on spherical polymer comprises the following steps:

1) weighing 51.6g of diethylenetriamine, placing the diethylenetriamine in a container, cooling the diethylenetriamine in an ice water bath, slowly dropwise adding a mixed solution of 43.0g of methyl acrylate and 100mL of methanol under the protection of nitrogen, reacting for 4 hours at normal temperature after dropwise adding, transferring a generated intermediate monomer into a reactor, removing the methanol under reduced pressure, heating to 150 ℃, continuing to react for 4 hours under reduced pressure, and stopping the reaction to obtain a polyamide polymer;

2) dissolving a proper amount of the polyamide polymer in deionized water to prepare 50mL of mother solution, dropwise adding 0.5mL0.1mol/L of silver nitrate aqueous solution into the mother solution while stirring to form a mixed solution, controlling the molar ratio of amino groups to silver ions in the polyamide polymer in the mixed solution to be 2:1, heating the mixed solution on an electric furnace to boil, taking down the mixed solution from the electric furnace after the mixed solution becomes bright yellow, cooling at room temperature, removing the solvent by a rotary evaporator, and freeze-drying at-15 ℃ and 10Pa for 15 hours to obtain a composite polyamide polymer;

3) adding a composite polyamide polymer into acrylic emulsion with the solid content of 41%, performing ultrasonic dispersion for 15min at 300W to obtain a treatment liquid with the composite polyamide polymer content of 8%, putting eucalyptus fibers into a reactor, performing impregnation treatment by adopting a vacuum-pressurization process, vacuumizing for 0.4h, injecting the treatment liquid again, pressurizing to 1.0MPa and keeping for 0.5h, after the treatment is finished, taking out the eucalyptus fibers, and performing drying treatment at 70 ℃ for 3h to obtain the treated eucalyptus fibers;

4) weighing a urea-formaldehyde resin adhesive accounting for 11% of the mass of the treated eucalyptus fibers, applying an ammonium chloride solution accounting for 1.0% of the solid content of the adhesive and accounting for 25% of the mass fraction of the ammonium chloride solution as a curing agent before the adhesive is used, uniformly spraying the adhesive into the treated eucalyptus fibers by using a pressure spray gun, drying the glued eucalyptus fibers by using a hot ventilation pipeline, stopping drying when the water content of the glue is 6.5%, paving and forming the dried eucalyptus fibers, and then hot-pressing for 5min at the temperature of 180 ℃ and under the pressure of 3MPa to obtain the formed fiberboard.

In the embodiment of the invention, the solid content of the urea-formaldehyde resin adhesive is 50%, and the content of free formaldehyde is less than 0.1%.

Example 2

The biomass fiber is selected from wood fiber, preferably eucalyptus fiber.

1) weighing 61.9g of diethylenetriamine, placing the diethylenetriamine in a container, cooling the diethylenetriamine in an ice water bath, slowly dropwise adding a mixed solution of 51.7g of methyl acrylate and 120mL of methanol under the protection of nitrogen, reacting for 5 hours at normal temperature after dropwise adding, transferring a generated intermediate monomer into a reactor, removing the methanol under reduced pressure, heating to 156 ℃, continuing to react for 5 hours under reduced pressure, and stopping the reaction to obtain a polyamide polymer;

2) dissolving a proper amount of the polyamide polymer in deionized water to prepare 65mL of mother solution, dropwise adding 0.65mL of 0.15mol/L silver nitrate aqueous solution into the mother solution while stirring to form a mixed solution, controlling the molar ratio of amino groups to silver ions in the polyamide polymer in the mixed solution to be 4:1, heating the mixed solution on an electric furnace to boil until the mixed solution becomes bright yellow, taking the mixed solution off the electric furnace, cooling at room temperature, removing the solvent by a rotary evaporator, and freeze-drying at-20 ℃ and 30Pa for 20 hours to obtain a composite polyamide polymer;

3) adding a composite polyamide polymer into an acrylic emulsion with the solid content of 42%, performing ultrasonic dispersion for 15min at 400W to obtain a treatment liquid with the composite polyamide polymer content of 12%, putting eucalyptus fibers into a reactor, performing impregnation treatment by adopting a vacuum-pressurization process, vacuumizing for 0.5h, injecting the treatment liquid again, pressurizing to 1.8MPa and keeping for 0.4h, after the treatment is finished, taking out the eucalyptus fibers, and performing drying treatment at 75 ℃ for 5h to obtain the treated eucalyptus fibers;

4) weighing a urea-formaldehyde resin adhesive accounting for 14% of the mass of the treated eucalyptus fibers, applying an ammonium chloride solution accounting for 1.3% of the solid content of the adhesive and 28% of the mass fraction of the ammonium chloride solution as a curing agent before the adhesive is used, uniformly spraying the adhesive into the treated eucalyptus fibers by using a pressure spray gun, drying the glued eucalyptus fibers by using a hot ventilation pipeline, stopping drying when the water content of the glue is 7.0%, paving and forming the dried eucalyptus fibers, and then carrying out hot pressing at 190 ℃ and 4MPa for 3min to obtain the formed fiberboard.

In the embodiment of the invention, the solid content of the urea-formaldehyde resin adhesive is 55%, and the content of free formaldehyde is less than 0.1%.

Example 3

The biomass fiber is selected from wood fiber, preferably eucalyptus fiber.

1) weighing 82.5g of diethylenetriamine, placing the diethylenetriamine in a container, cooling the diethylenetriamine in an ice water bath, slowly dropwise adding a mixed solution of 68.8g of methyl acrylate and 160mL of methanol under the protection of nitrogen, reacting for 6 hours at normal temperature after dropwise adding, transferring a generated intermediate monomer into a reactor, removing the methanol under reduced pressure, heating to 158 ℃, continuing to react for 6 hours under reduced pressure, and stopping the reaction to obtain a polyamide polymer;

2) dissolving a proper amount of the polyamide polymer in deionized water to prepare 80mL of mother liquor, dropwise adding 0.8mL of 0.18mol/L silver nitrate aqueous solution into the mother liquor while stirring to form a mixed solution, controlling the molar ratio of amino groups to silver ions in the polyamide polymer in the mixed solution to be 5:1, heating the mixed solution on an electric furnace to boil until the mixed solution becomes bright yellow, taking the mixed solution off the electric furnace, cooling at room temperature, removing the solvent by a rotary evaporator, and freeze-drying at-25 ℃ and 30Pa for 20 hours to obtain a composite polyamide polymer;

3) adding a composite polyamide polymer into acrylic emulsion with the solid content of 43%, performing ultrasonic dispersion for 25min at 400W to obtain a treatment liquid with the composite polyamide polymer content of 13%, putting eucalyptus fibers into a reactor, performing impregnation treatment by adopting a vacuum-pressurization process, vacuumizing for 0.6h, injecting the treatment liquid again, pressurizing to 2.5MPa and keeping for 0.3h, after the treatment is finished, taking out the eucalyptus fibers, and performing drying treatment at 80 ℃ for 6h to obtain the treated eucalyptus fibers;

4) weighing a urea-formaldehyde resin adhesive accounting for 15% of the mass of the treated eucalyptus fibers, applying an ammonium chloride solution accounting for 1.5% of the solid content of the adhesive and 28% of the mass fraction of the ammonium chloride solution as a curing agent before the adhesive is used, uniformly spraying the adhesive into the treated eucalyptus fibers by using a pressure spray gun, drying the glued eucalyptus fibers by using a hot ventilation pipeline, stopping drying when the water content of the glue is 7.5%, paving and forming the dried eucalyptus fibers, and then hot-pressing at 195 ℃ and 5MPa for 2min to obtain the formed fiberboard.

Test experiments

1.1 test specimens

Experimental groups: processing the fiberboard sample by adopting the process method provided by the embodiment 1;

control group: selecting eucalyptus fibers same as an experimental group, weighing a urea-formaldehyde resin adhesive accounting for 11% of the mass of the processed eucalyptus fibers, applying an ammonium chloride solution accounting for 1.0% of the solid content of the adhesive and accounting for 25% of the mass fraction of the adhesive as a curing agent before the adhesive is used, uniformly spraying the adhesive into the processed eucalyptus fibers by using a pressure spray gun, drying the glued eucalyptus fibers by using a hot ventilation pipeline until the water content of the glued eucalyptus fibers is 6.5%, paving and forming the dried eucalyptus fibers, and then hot-pressing for 8min at 180 ℃ and 6MPa to obtain a formed fiberboard, wherein the solid content of the urea-formaldehyde resin adhesive is 50%, and the free formaldehyde content is less than 0.1%.

1.2 fiberboard Density

The density of the fiberboard obtained in the experimental group is 752.6 +/-6.5 kg/m³Fiberboard obtained in the experimental group with density of 751.3 +/-7.2 kg/m³The densities of both are substantially the same.

1.3 mechanical Property testing of the fiberboard

According to the GB/T11718-2009 Medium Density fiberboard standard, the static bending strength, the elastic modulus, the internal bonding strength and other performance tests are respectively carried out on the fiberboards in the experimental group and the control group, and the results are as follows:

static bending strength of fiberboard: the static bending strength of the fiber board obtained in the experimental group is 41.7 MPa; the static bending strength of the fiber board obtained in the control group was 38.2 MPa.

Fiber board elastic modulus: the elastic modulus of the fiber board obtained in the experimental group is 3417 MPa; the fiber sheet obtained in the control had an elastic modulus of 3352 MPa.

Bond strength in fiberboard: the elastic modulus of the fiber board obtained in the experimental group is 0.87 MPa; the fiber sheet obtained in the control had an elastic modulus of 0.82 MPa.

According to the test results, the performance data of the fiber board obtained by the preparation method of the fiber board provided by the invention is excellent, the processing requirements on the current market are met, in the process, the hot pressing time and the hot pressing pressure are far lower than those of the prior art, and the preparation method of the fiber board has good effects of saving energy and improving the production efficiency.

The above description is only an embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that are not thought of through the inventive work should be included in the scope of the present invention.

Claims

1. A method for preparing a biomass fiberboard based on spherical polymers is characterized by comprising the following steps: firstly, preparing a polymer into a quasi-spherical structure, then reducing the quasi-spherical polymer surface to generate nano silver, dispersing the formed composite polymer in emulsion, impregnating the emulsion into biomass fibers through vacuum pressurization, and preparing the fiber board through hot press molding, wherein the preparation method comprises the following steps: 1) Taking diethylenetriamine and methyl acrylate as raw materials, and synthesizing and preparing a polyamide polymer with a quasi-spherical structure by a polycondensation method; 2) Using polyamide polymer and silver nitrate aqueous solution as raw materials, and reducing the raw materials on the surface by a chemical reduction method to generate nano silver particles so as to obtain a composite polyamide polymer; 3) Dispersing the composite polyamide polymer in acrylic emulsion to form a treatment solution, and drying the biomass fiber after soaking the treatment solution; 4) And spraying an adhesive on the surface of the dried biomass fiber, and carrying out hot press molding to obtain the fiberboard.

2. The method for preparing the biopolymer-based fiberboard of claim 1, wherein the mass ratio of diethylenetriamine to methyl acrylate is 51.6-82.5: 43.0-68.8.

3. The method for preparing the spherical polymer-based biomass fiberboard as claimed in claim 1, wherein in the polycondensation method, the reaction system is reacted at room temperature for 4-6h, then methanol is removed under reduced pressure, and then the temperature is raised to 150-.

4. The method for preparing a biopolymer-based fiberboard of claim 1, wherein the reaction system of the chemical reduction process has a molar ratio of amino groups to silver ions in the polyamide polymer of 2-5: 1.

5. The method of claim 1, wherein the composite polyamide polymer is present in the treatment fluid in an amount of 8 to 13% by weight.