CN114350169B - Preparation method of formaldehyde-free high-strength electromagnetic shielding wood fiber composite material - Google Patents
Preparation method of formaldehyde-free high-strength electromagnetic shielding wood fiber composite material Download PDFInfo
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Abstract
The invention relates to the technical field of wood-plastic composite materials, and discloses a preparation method of an aldehyde-free high-strength electromagnetic shielding wood fiber composite material, which comprises the following steps: (1) obtaining modified wood fiber; (2) obtaining a polyvinyl alcohol solution; (3) obtaining an intermediate material; (4) obtaining a wood fiber composite material; the prepared formaldehyde-free high-strength electromagnetic shielding wood fiber composite material has no free formaldehyde in each component, and the adhesive product has no free formaldehyde release, so that the formaldehyde-free property of the fiberboard is realized.
Description
Technical Field
The invention relates to the technical field of wood-plastic composite materials, in particular to a preparation method of a wood fiber composite material without formaldehyde and high-strength electromagnetic shielding.
Background
The fiberboard is also named as a density board, which is an artificial board made of wood fiber or other plant cellulose fiber as a raw material and urea formaldehyde resin or other suitable adhesives. During the manufacturing process, adhesives and/or additives can be applied. The fiberboard 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 manufacture, and can replace 3 cubic meters of sawn timber or 5 cubic meters of log. The development of fiberboard production is an effective way for the comprehensive utilization of wood resources.
In the production of the traditional wood fiber artificial board, a large amount of free formaldehyde is released by the adhesive used for pressing the board. Along with the improvement of indoor environment requirements of people and the emergence of relevant national environmental laws and regulations, the non-hydroformylation of wood fiber artificial board products is imminent. Researchers have conducted respective studies on the binder and the production process of the fiberboard without hydroformylation. The aldehyde-free adhesive mainly comprises a natural adhesive, a modified bio-based adhesive, an aldehyde-free (modified) polymer resin adhesive and the like. The improvement on the production process mainly comprises a hot pressing process, and the microwave hot pressing overcomes the defects of the traditional hot pressing process.
In the production of the traditional wood fiber artificial board, a large amount of free formaldehyde is released by the adhesive used for pressing the board. Along with the improvement of indoor environment requirements of people and the emergence of relevant national environmental laws and regulations, the non-hydroformylation of wood fiber artificial board products is imminent. Researchers have conducted respective studies on the binder and the production process of the fiberboard without hydroformylation. The aldehyde-free adhesive mainly comprises a natural adhesive, a modified bio-based adhesive, an aldehyde-free (modified) polymer resin adhesive and the like. The improvement on the production process mainly comprises a hot pressing process, and the microwave hot pressing overcomes the defects of the traditional hot pressing process.
The performance of the existing wood fiber board composite material is general, and the performance is more limited particularly in the application of occasions needing electromagnetic shielding.
Based on the above, we propose a preparation method of a wood fiber composite material without aldehyde and with high strength electromagnetic shielding, and hopefully solve the defects in the prior art.
Disclosure of Invention
Technical problem to be solved
Aiming at the defects of the prior art, the invention provides a preparation method of a wood fiber composite material without aldehyde and high-strength electromagnetic shielding.
(II) technical scheme
In order to achieve the purpose, the invention provides the following technical scheme:
the preparation method of the wood fiber composite material without the aldehyde and high-strength electromagnetic shielding comprises the following steps:
(1) Wood fiber modification treatment: firstly dispersing wood fiber into bentonite dispersion liquid, then adjusting the pH value of the dispersion liquid to 10.0, adding maleic anhydride, adjusting the temperature to 80 ℃, keeping the temperature and stirring for 1 hour, adjusting the pH value of the dispersion liquid to be neutral, and then performing rotary evaporation drying to obtain modified wood fiber;
(2) Preparing a polyvinyl alcohol solution, adding the polyvinyl alcohol solution into deionized water, and uniformly stirring to obtain the polyvinyl alcohol solution;
(3) Mixing the modified wood fiber and the polyvinyl alcohol solution together, uniformly stirring, and standing at the temperature of 50 ℃ for 30min to obtain an intermediate material;
(4) And (3) uniformly mixing the intermediate material and the modified adhesive, paving, hot-pressing and cooling to obtain the wood fiber composite material.
As a further technical scheme: the mixing mass ratio of the wood fiber to the bentonite dispersion liquid is 1:5;
the mass fraction of the bentonite dispersion liquid is 8%;
the particle size of the bentonite in the bentonite dispersion liquid is 100 mu m;
the mass ratio of the wood fiber to the maleic anhydride is 10.
As a further technical scheme, the mass fraction of the polyvinyl alcohol solution is 15%.
According to a further technical scheme, the mixing mass ratio of the modified wood fiber to the polyvinyl alcohol solution is 12.
As a further technical scheme: the modified adhesive is prepared from the following components in parts by weight: 300-500 parts of urea-formaldehyde resin, 3-5 parts of nano wave absorbing agent, 30-50 parts of hydroxymethyl cellulose, 3-5 parts of defoaming agent, 10-15 parts of nano calcium carbonate and 100-110 parts of deionized water.
As a further technical scheme: the preparation method of the nano core-shell wave absorber comprises the following steps: mixing Co (NO) 3 ) 2 ·6H 2 Sequentially dispersing O, silicon powder, graphene and 2-methylimidazole into methanol, magnetically stirring for 30min, then performing centrifugal filtration, cleaning for 3 times by using ethanol, putting into a vacuum drying oven, adding into a ball mill, performing ball milling and mixing, and mixing for 1h; after being uniformly mixed, the mixture is moved into a resistance furnace to be calcined for 4 hours at 1400-1600 ℃ in a vacuum environment, and then the nano core-shell wave absorber is obtained;
the vacuum drying temperature in the vacuum drying oven is 50 ℃.
As a further technical solution, the Co (NO) 3 ) 2 ·6H 2 The mixing weight ratio of O, silicon powder, graphene, 2-methylimidazole and methanol is 10.
As a further technical scheme, the purity of the silicon powder is 98-99.99%, and the particle size is 235-2000 meshes.
As a further technical scheme, the defoaming agent is an organic silicon defoaming agent.
As a further technical scheme, the glue application amount of the modified adhesive in the wood fiber composite material is 100-150kg/m 3 。
The prepared modified adhesive has high bonding strength and stronger affinity than wood fiber molecules, so that the mechanical property of the prepared wood fiber composite material is obviously improved.
(III) advantageous effects
Compared with the prior art, the invention provides the preparation method of the wood fiber composite material without aldehyde and high-strength electromagnetic shielding, which has the following beneficial effects:
the prepared formaldehyde-free high-strength electromagnetic shielding wood fiber composite material has no free formaldehyde in each component, and the adhesive product has no free formaldehyde released, so that the formaldehyde-free property of the fiberboard is realized.
The introduction of the nano core-shell wave-absorbing particles enables the fiber board to have excellent electromagnetic shielding performance, can be used for encryption of important information, and can also be used for home decoration to protect human from being injured by long-term exposure to electromagnetic radiation.
According to the invention, through modification treatment on the wood fiber, the structural performance of the wood fiber can be greatly improved, bentonite particles are inserted into gaps of the wood fiber structure, and active groups are grafted on molecular chains of the wood fiber, so that the mechanical property of the wood fiber can be greatly improved, meanwhile, the bonding property between the wood fiber and an adhesive is greatly increased, and further, the mechanical property of the prepared wood fiber composite material is obviously increased.
Drawings
FIG. 1 is a diagram showing the influence of different parts by weight of nano core-shell wave absorbers on electromagnetic shielding performance.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
The preparation method of the wood fiber composite material without the aldehyde and high-strength electromagnetic shielding comprises the following steps:
(1) Wood fiber modification treatment: firstly dispersing wood fiber into bentonite dispersion liquid, then adjusting the pH value of the dispersion liquid to 10.0, adding maleic anhydride, adjusting the temperature to 80 ℃, keeping the temperature and stirring for 1 hour, adjusting the pH value of the dispersion liquid to be neutral, and then performing rotary evaporation drying to obtain modified wood fiber;
(2) Preparing a polyvinyl alcohol solution, adding the polyvinyl alcohol solution into deionized water, and uniformly stirring to obtain the polyvinyl alcohol solution;
(3) Mixing the modified wood fiber and the polyvinyl alcohol solution together, uniformly stirring, and standing at the temperature of 50 ℃ for 30min to obtain an intermediate material;
(4) And (3) uniformly mixing the intermediate material and the modified adhesive, paving, hot-pressing and cooling to obtain the wood fiber composite material.
The mixing mass ratio of the wood fiber to the bentonite dispersion liquid is 1:5;
the mass fraction of the bentonite dispersion liquid is 8%;
the particle size of the bentonite in the bentonite dispersion liquid is 100 mu m;
the mass ratio of the wood fiber to the maleic anhydride is 10.
The mass fraction of the polyvinyl alcohol solution is 15%.
The mixing mass ratio of the modified wood fiber to the polyvinyl alcohol solution is 12.
The modified adhesive is prepared from the following components in parts by weight: 300 parts of urea-formaldehyde resin, 3 parts of a nano wave absorbing agent, 30 parts of hydroxymethyl cellulose, 3 parts of a defoaming agent, 10 parts of nano calcium carbonate and 100 parts of deionized water.
The preparation method of the nano core-shell wave absorber comprises the following steps: mixing Co (NO) 3 ) 2 ·6H 2 Dispersing O, silicon powder, graphene and 2-methylimidazole in methanol in sequence, magnetically stirring for 30min, centrifuging, filtering, and washing with ethanol for 3 timesPutting the mixture into a vacuum drying oven, adding the mixture into a ball mill for ball milling and mixing for 1h; after being uniformly mixed, the mixture is moved into a resistance furnace to be calcined for 4 hours at 1400 ℃ in a vacuum environment, and then the nano core-shell wave absorbing agent is obtained;
the vacuum drying temperature in the vacuum drying oven is 50 ℃.
The Co (NO) 3 ) 2 ·6H 2 The mixing weight ratio of O, silicon powder, graphene, 2-methylimidazole and methanol is 10.
The purity of the silicon powder is 99.99%, and the granularity is 1000 meshes.
The defoaming agent is an organic silicon defoaming agent.
The glue application amount of the modified adhesive in the wood fiber composite material is 100kg/m 3 。
Example 2
The preparation method of the wood fiber composite material without the aldehyde and high-strength electromagnetic shielding comprises the following steps:
(1) Wood fiber modification treatment: firstly dispersing wood fibers into bentonite dispersion liquid, then adjusting the pH value of the dispersion liquid to 10.0, adding maleic anhydride, adjusting the temperature to 80 ℃, keeping the temperature and stirring for 1 hour, adjusting the pH value of the dispersion liquid to be neutral, and then performing rotary evaporation drying to obtain modified wood fibers;
(2) Preparing a polyvinyl alcohol solution, adding the polyvinyl alcohol solution into deionized water, and uniformly stirring to obtain the polyvinyl alcohol solution;
(3) Mixing the modified wood fiber and the polyvinyl alcohol solution together, uniformly stirring, and standing at the temperature of 50 ℃ for 30min to obtain an intermediate material;
(4) And (3) uniformly mixing the intermediate material and the modified adhesive, paving, hot-pressing and cooling to obtain the wood fiber composite material.
The mixing mass ratio of the wood fiber to the bentonite dispersion liquid is 1:5;
the mass fraction of the bentonite dispersion liquid is 8%;
the particle size of the bentonite in the bentonite dispersion liquid is 100 mu m;
the mass ratio of the wood fiber to the maleic anhydride is 10.
The mass fraction of the polyvinyl alcohol solution is 15%.
The mixing mass ratio of the modified wood fiber to the polyvinyl alcohol solution is 12.
The modified adhesive is prepared from the following components in parts by weight: urea-formaldehyde resin 350, a nano wave absorbing agent 4, hydroxymethyl cellulose 35, a defoaming agent 4, nano calcium carbonate 11 and deionized water 102.
The preparation method of the nano core-shell wave absorber comprises the following steps: mixing Co (NO) 3 ) 2 ·6H 2 Sequentially dispersing O, silicon powder, graphene and 2-methylimidazole into methanol, magnetically stirring for 30min, then performing centrifugal filtration, washing for 3 times by using ethanol, putting into a vacuum drying oven, adding into a ball mill, performing ball milling and mixing for 1h; after being uniformly mixed, the mixture is moved into a resistance furnace to be calcined for 4 hours at 1450 ℃ in a vacuum environment, and then the nano core-shell wave absorbing agent is obtained;
the vacuum drying temperature in the vacuum drying oven is 50 ℃.
The Co (NO) 3 ) 2 ·6H 2 The mixing weight ratio of O, silicon powder, graphene, 2-methylimidazole and methanol is 10.
The purity of the silicon powder is 99.99%, and the particle size is 1000 meshes.
The defoaming agent is an organic silicon defoaming agent.
The glue application amount of the modified adhesive in the wood fiber composite material is 110kg/m 3 。
Example 3
The preparation method of the wood fiber composite material without the aldehyde and high-strength electromagnetic shielding comprises the following steps:
(1) Wood fiber modification treatment: firstly dispersing wood fiber into bentonite dispersion liquid, then adjusting the pH value of the dispersion liquid to 10.0, adding maleic anhydride, adjusting the temperature to 80 ℃, keeping the temperature and stirring for 1 hour, adjusting the pH value of the dispersion liquid to be neutral, and then performing rotary evaporation drying to obtain modified wood fiber;
(2) Preparing a polyvinyl alcohol solution, adding the polyvinyl alcohol solution into deionized water, and uniformly stirring to obtain the polyvinyl alcohol solution;
(3) Mixing the modified wood fiber and the polyvinyl alcohol solution together, uniformly stirring, and standing at the temperature of 50 ℃ for 30min to obtain an intermediate material;
(4) And (3) uniformly mixing the intermediate material and the modified adhesive, paving, hot-pressing and cooling to obtain the wood fiber composite material.
The mixing mass ratio of the wood fiber to the bentonite dispersion liquid is 1:5;
the mass fraction of the bentonite dispersion liquid is 8%;
the particle size of the bentonite in the bentonite dispersion liquid is 100 mu m;
the mass ratio of the wood fiber to the maleic anhydride is 10.
The mass fraction of the polyvinyl alcohol solution is 15%.
The mixing mass ratio of the modified wood fiber to the polyvinyl alcohol solution is 12.
The modified adhesive is prepared from the following components in parts by weight: urea-formaldehyde resin 380, nano wave absorbing agent 3.5, hydroxymethyl cellulose 38, defoaming agent 3.2, nano calcium carbonate 12 and deionized water 104.
The preparation method of the nano core-shell wave absorber comprises the following steps: mixing Co (NO) 3 ) 2 ·6H 2 Sequentially dispersing O, silicon powder, graphene and 2-methylimidazole into methanol, magnetically stirring for 30min, then performing centrifugal filtration, washing for 3 times by using ethanol, putting into a vacuum drying oven, adding into a ball mill, performing ball milling and mixing for 1h; after being uniformly mixed, the mixture is moved into a resistance furnace to be calcined for 4 hours at 1500 ℃ in a vacuum environment, and then the nano core-shell wave absorber is obtained;
the vacuum drying temperature in the vacuum drying oven is 50 ℃.
The Co (NO) 3 ) 2 ·6H 2 The mixing weight ratio of O, silicon powder, graphene, 2-methylimidazole and methanol is 10.
The purity of the silicon powder is 99.99%, and the granularity is 1000 meshes.
The defoaming agent is an organic silicon defoaming agent.
The wood fiber composite materialThe glue application amount of the medium modified adhesive is 120kg/m 3 。
Example 4
The preparation method of the wood fiber composite material without the aldehyde and high-strength electromagnetic shielding comprises the following steps:
(1) Wood fiber modification treatment: firstly dispersing wood fiber into bentonite dispersion liquid, then adjusting the pH value of the dispersion liquid to 10.0, adding maleic anhydride, adjusting the temperature to 80 ℃, keeping the temperature and stirring for 1 hour, adjusting the pH value of the dispersion liquid to be neutral, and then performing rotary evaporation drying to obtain modified wood fiber;
(2) Preparing a polyvinyl alcohol solution, adding the polyvinyl alcohol solution into deionized water, and uniformly stirring to obtain the polyvinyl alcohol solution;
(3) Mixing the modified wood fiber and the polyvinyl alcohol solution together, uniformly stirring, and standing at the temperature of 50 ℃ for 30min to obtain an intermediate material;
(4) And (3) uniformly mixing the intermediate material and the modified adhesive, paving, hot-pressing and cooling to obtain the wood fiber composite material.
The mixing mass ratio of the wood fiber to the bentonite dispersion liquid is 1:5;
the mass fraction of the bentonite dispersion liquid is 8%;
the particle size of the bentonite in the bentonite dispersion liquid is 100 mu m;
the mass ratio of the wood fiber to the maleic anhydride is 10.
The mass fraction of the polyvinyl alcohol solution is 15%.
The mixing mass ratio of the modified wood fiber to the polyvinyl alcohol solution is 12.
The modified adhesive is prepared from the following components in parts by weight: urea-formaldehyde resin 400, a nano wave absorbing agent 4, hydroxymethyl cellulose 40, a defoaming agent 4, nano calcium carbonate 13 and deionized water 105.
The preparation method of the nano core-shell wave absorber comprises the following steps: mixing Co (NO) 3 ) 2 ·6H 2 Dispersing O, silicon powder, graphene and 2-methylimidazole in methanol in sequence, magnetically stirring for 30min, centrifuging, filtering, washing with ethanol for 3 times,putting into a vacuum drying oven, adding into a ball mill for ball milling and mixing for 1h; after being uniformly mixed, the mixture is moved into a resistance furnace to be calcined for 4 hours at 1500 ℃ in a vacuum environment, and then the nano core-shell wave absorber is obtained;
the vacuum drying temperature in the vacuum drying oven is 50 ℃.
The Co (NO) 3 ) 2 ·6H 2 The mixing weight ratio of O, silicon powder, graphene, 2-methylimidazole and methanol is 10.
The purity of the silicon powder is 99.99%, and the granularity is 1000 meshes.
The defoaming agent is an organic silicon defoaming agent.
The glue application amount of the modified adhesive in the wood fiber composite material is 120kg/m 3 。
Example 5
The preparation method of the wood fiber composite material without the aldehyde and high-strength electromagnetic shielding comprises the following steps:
(1) Wood fiber modification treatment: firstly dispersing wood fibers into bentonite dispersion liquid, then adjusting the pH value of the dispersion liquid to 10.0, adding maleic anhydride, adjusting the temperature to 80 ℃, keeping the temperature and stirring for 1 hour, adjusting the pH value of the dispersion liquid to be neutral, and then performing rotary evaporation drying to obtain modified wood fibers;
(2) Preparing a polyvinyl alcohol solution, adding the polyvinyl alcohol solution into deionized water, and uniformly stirring to obtain the polyvinyl alcohol solution;
(3) Mixing the modified wood fiber and the polyvinyl alcohol solution together, uniformly stirring, and standing at the temperature of 50 ℃ for 30min to obtain an intermediate material;
(4) And (3) uniformly mixing the intermediate material and the modified adhesive, paving, hot-pressing and cooling to obtain the wood fiber composite material.
The mixing mass ratio of the wood fiber to the bentonite dispersion liquid is 1:5;
the mass fraction of the bentonite dispersion liquid is 8%;
the particle size of the bentonite in the bentonite dispersion liquid is 100 mu m;
the mass ratio of the wood fiber to the maleic anhydride is 10.
The mass fraction of the polyvinyl alcohol solution is 15%.
The mixing mass ratio of the modified wood fiber to the polyvinyl alcohol solution is 12.
The modified adhesive is prepared from the following components in parts by weight: 450 parts of urea-formaldehyde resin, 4.5 parts of nano wave absorbing agent, 40 parts of hydroxymethyl cellulose, 4.5 parts of defoaming agent, 14 parts of nano calcium carbonate and 108 parts of deionized water.
The preparation method of the nano core-shell wave absorber comprises the following steps: mixing Co (NO) 3 ) 2 ·6H 2 Sequentially dispersing O, silicon powder, graphene and 2-methylimidazole into methanol, magnetically stirring for 30min, then performing centrifugal filtration, cleaning for 3 times by using ethanol, putting into a vacuum drying oven, adding into a ball mill, performing ball milling and mixing, and mixing for 1h; after being uniformly mixed, the mixture is moved into a resistance furnace to be calcined for 4 hours at 1550 ℃ in a vacuum environment, and then the nano core-shell wave absorbing agent is obtained;
the vacuum drying temperature in the vacuum drying oven is 50 ℃.
The Co (NO) 3 ) 2 ·6H 2 The mixing weight ratio of O, silicon powder, graphene, 2-methylimidazole and methanol is 10.
The purity of the silicon powder is 99.99%, and the granularity is 1000 meshes.
The defoaming agent is an organic silicon defoaming agent.
The glue application amount of the modified adhesive in the wood fiber composite material is 140kg/m 3 。
Example 6
The preparation method of the wood fiber composite material without the aldehyde and high-strength electromagnetic shielding comprises the following steps:
(1) Wood fiber modification treatment: firstly dispersing wood fiber into bentonite dispersion liquid, then adjusting the pH value of the dispersion liquid to 10.0, adding maleic anhydride, adjusting the temperature to 80 ℃, keeping the temperature and stirring for 1 hour, adjusting the pH value of the dispersion liquid to be neutral, and then performing rotary evaporation drying to obtain modified wood fiber;
(2) Preparing a polyvinyl alcohol solution, adding the polyvinyl alcohol solution into deionized water, and uniformly stirring to obtain the polyvinyl alcohol solution;
(3) Mixing the modified wood fiber and the polyvinyl alcohol solution together, uniformly stirring, and standing at the temperature of 50 ℃ for 30min to obtain an intermediate material;
(4) And (3) uniformly mixing the intermediate material and the modified adhesive, paving, hot-pressing and cooling to obtain the wood fiber composite material.
The mixing mass ratio of the wood fiber to the bentonite dispersion liquid is 1:5;
the mass fraction of the bentonite dispersion liquid is 8%;
the particle size of the bentonite in the bentonite dispersion liquid is 100 mu m;
the mass ratio of the wood fiber to the maleic anhydride is 10.
The mass fraction of the polyvinyl alcohol solution is 15%.
The mixing mass ratio of the modified wood fiber to the polyvinyl alcohol solution is 12.
The modified adhesive is prepared from the following components in parts by weight: 500 parts of urea-formaldehyde resin, 5 parts of a nano wave absorbing agent, 50 parts of hydroxymethyl cellulose, 5 parts of a defoaming agent, 15 parts of nano calcium carbonate and 110 parts of deionized water.
The preparation method of the nano core-shell wave absorber comprises the following steps: mixing Co (NO) 3 ) 2 ·6H 2 Sequentially dispersing O, silicon powder, graphene and 2-methylimidazole into methanol, magnetically stirring for 30min, then performing centrifugal filtration, washing for 3 times by using ethanol, putting into a vacuum drying oven, adding into a ball mill, performing ball milling and mixing for 1h; after being uniformly mixed, the mixture is moved into a resistance furnace to be calcined for 4 hours at 1600 ℃ in a vacuum environment, and then the nano core-shell wave absorbing agent is obtained;
the vacuum drying temperature in the vacuum drying oven is 50 ℃.
The Co (NO) 3 ) 2 ·6H 2 The mixing weight ratio of O, silicon powder, graphene, 2-methylimidazole and methanol is 10.
The purity of the silicon powder is 99.99%, and the granularity is 1000 meshes.
The defoaming agent is an organic silicon defoaming agent.
In the wood fiber composite materialThe glue application amount of the modified adhesive is 150kg/m 3 。
Test of
Electromagnetic shielding performance
The electromagnetic shielding effectiveness test is carried out on the samples of the embodiment and the comparative example by adopting a vertical flange coaxial tester, and the electromagnetic wave frequency is 1.2GHz:
TABLE 1
| Electromagnetic shield/dB | |
| Example 1 | 33.2 |
| Example 2 | 34.5 |
| Example 3 | 35.1 |
| Example 4 | 35.5 |
| Example 5 | 35.3 |
| Example 6 | 35.3 |
| Comparative example 1 | 22.6 |
| Comparative example 2 | 15.2 |
Comparative example 1: the difference from the example 1 is that Co (NO) is not added in the nano core-shell wave absorber 3 ) 2 ·6H 2 O；
Comparative example 2: the difference from the embodiment 1 is that the nano core-shell wave absorbing agent is not added;
as can be seen from Table 1, the wood fiber composite material prepared by the method has excellent electromagnetic shielding performance, and the electromagnetic shielding performance of the wood fiber composite material can be greatly improved by introducing the prepared nano core-shell wave absorber.
Further experiments were carried out on the samples of the examples in accordance with the national standard GB/T39598-2021:
TABLE 2
| Formaldehyde emission mg/m 3 | |
| Example 1 | 0.002 |
| Example 2 | 0.003 |
| Example 3 | 0.003 |
| Example 4 | 0.002 |
| Example 5 | 0.002 |
| Example 6 | 0.002 |
As can be seen from Table 2, the formaldehyde release of the wood fiber board prepared by the invention meets the national standard, the wood fiber board is green and environment-friendly, and the wood fiber board has better guarantee for the health of human body.
Further experiments, comparing the properties of the examples with those of the comparative examples according to the national standard GB/T11718-1999:
TABLE 3
Comparative example 3: the difference from the embodiment 1 is that the wood fiber is not modified;
comparative example 4: the difference from the embodiment 1 is that the modified adhesive is replaced by the conventional urea-formaldehyde resin adhesive;
as can be seen from table 3, the mechanical properties of the wood fiber board prepared by the present invention are greatly improved, the mechanical properties of the prepared wood fiber board can be improved by the modification treatment of the wood fibers, and the mechanical properties of the wood fiber board are further greatly enhanced by the use of the modified adhesive.
The electromagnetic shielding performance of the nano core-shell wave absorber is compared with that of the nano core-shell wave absorber in the embodiment 1.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (8)
1. The preparation method of the wood fiber composite material without the aldehyde and high-strength electromagnetic shielding is characterized by comprising the following steps of:
(1) Wood fiber modification treatment: firstly dispersing wood fibers into bentonite dispersion liquid, then adjusting the pH value of the dispersion liquid to 10.0, adding maleic anhydride, adjusting the temperature to 80 ℃, keeping the temperature and stirring for 1 hour, adjusting the pH value of the dispersion liquid to be neutral, and then performing rotary evaporation drying to obtain modified wood fibers;
(2) Preparing a polyvinyl alcohol solution, adding the polyvinyl alcohol solution into deionized water, and uniformly stirring to obtain the polyvinyl alcohol solution;
(3) Mixing the modified wood fiber and the polyvinyl alcohol solution together, uniformly stirring, and standing at the temperature of 50 ℃ for 30min to obtain an intermediate material;
(4) Uniformly mixing the intermediate material and the modified adhesive, paving, hot-pressing and cooling to obtain a wood fiber composite material;
the modified adhesive is prepared from the following components in parts by weight: 300-500 parts of urea-formaldehyde resin, 3-5 parts of nano core-shell wave absorbing agent, 30-50 parts of hydroxymethyl cellulose, 3-5 parts of defoaming agent, 10-15 parts of nano calcium carbonate and 100-110 parts of deionized water;
the preparation method of the nano core-shell wave absorber comprises the following steps: mixing Co (NO) 3 ) 2 •6H 2 Sequentially dispersing O, silicon powder, graphene and 2-methylimidazole into methanol, magnetically stirring for 30min, then performing centrifugal filtration, washing for 3 times by using ethanol, putting into a vacuum drying oven, adding into a ball mill, performing ball milling and mixing for 1h; after being uniformly mixed, the mixture is moved into a resistance furnace to be calcined for 4 hours at 1400-1600 ℃ in a vacuum environment, and then the nano core-shell wave absorber is obtained;
the vacuum drying temperature in the vacuum drying oven is 50 ℃.
2. The method for preparing the wood fiber composite material without aldehyde and high-strength electromagnetic shielding according to claim 1, wherein the wood fiber composite material comprises the following steps: the mixing mass ratio of the wood fiber to the bentonite dispersion liquid is 1:5;
the mass fraction of the bentonite dispersion liquid is 8%;
the particle size of the bentonite in the bentonite dispersion liquid is 100 mu m;
the mass ratio of the wood fiber to the maleic anhydride is 10.
3. The method for preparing the wood fiber composite material without formaldehyde and high strength electromagnetic shielding of claim 1, wherein the mass fraction of the polyvinyl alcohol solution is 15%.
4. The method for preparing the wood fiber composite material without the aldehyde and the high-strength electromagnetic shielding according to claim 1, wherein the mixing mass ratio of the modified wood fiber to the polyvinyl alcohol solution is 12-2.
5. The method for preparing the wood fiber composite material of the claim 1, wherein the Co (NO) is used as the material 3 ) 2 •6H 2 The mixing weight ratio of O, silicon powder, graphene, 2-methylimidazole and methanol is 10.
6. The method for preparing the wood fiber composite material without the aldehyde and the high-strength electromagnetic shielding according to claim 5, wherein the purity of the silicon powder is 98-99.99%, and the particle size is 235-2000 meshes.
7. The method for preparing the wood fiber composite material without the aldehyde and the electromagnetic shielding in high strength according to claim 1, wherein the defoaming agent is a silicone defoaming agent.
8. The method for preparing the wood fiber composite material without the aldehyde and the electromagnetic shielding, according to claim 1, wherein the glue application amount of the modified adhesive in the wood fiber composite material is 100-150kg/m 3 。
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| CN106189325A (en) * | 2016-08-04 | 2016-12-07 | 南京工业大学 | A kind of lignin enhancement mode Wood-plastic material and preparation method thereof |
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