CN111673866A - Formaldehyde-free medium-density hemp straw particle board and manufacturing method thereof - Google Patents

Formaldehyde-free medium-density hemp straw particle board and manufacturing method thereof Download PDF

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Publication number
CN111673866A
CN111673866A CN202010551022.2A CN202010551022A CN111673866A CN 111673866 A CN111673866 A CN 111673866A CN 202010551022 A CN202010551022 A CN 202010551022A CN 111673866 A CN111673866 A CN 111673866A
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Prior art keywords
formaldehyde
particles
hemp
fine
density
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Chinese (zh)
Inventor
王步宁
宛俊生
陈福新
崔雄
张玟籍
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Shanghai Compak Environmental Protection Equipment Co ltd
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Shanghai Compak Environmental Protection Equipment Co ltd
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Priority to CN202010551022.2A priority Critical patent/CN111673866A/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
    • B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
    • B27N3/00—Manufacture of substantially flat articles, e.g. boards, from particles or fibres
    • B27N3/02—Manufacture of substantially flat articles, e.g. boards, from particles or fibres from particles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
    • B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
    • B27N1/00—Pretreatment of moulding material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
    • B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
    • B27N3/00—Manufacture of substantially flat articles, e.g. boards, from particles or fibres
    • B27N3/002—Manufacture of substantially flat articles, e.g. boards, from particles or fibres characterised by the type of binder
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
    • B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
    • B27N3/00—Manufacture of substantially flat articles, e.g. boards, from particles or fibres
    • B27N3/08—Moulding or pressing
    • B27N3/10—Moulding of mats
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
    • B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
    • B27N3/00—Manufacture of substantially flat articles, e.g. boards, from particles or fibres
    • B27N3/08—Moulding or pressing
    • B27N3/18—Auxiliary operations, e.g. preheating, humidifying, cutting-off
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J175/00—Adhesives based on polyureas or polyurethanes; Adhesives based on derivatives of such polymers

Abstract

The invention discloses a formaldehyde-free medium-density hemp straw particle board and a manufacturing method thereof, wherein the manufacturing method comprises the following steps: crushing, drying, spraying glue and stirring, laying a raw material plate blank, prepressing, hot-pressing and cutting to prepare the formaldehyde-free medium-density hemp straw particle board. The formaldehyde-free medium-density hemp straw particle board is completely made of hemp straws and has a multilayer structure of fine particles, coarse particles and fine particles. The invention has the advantages that the particle board is made of the hemp straws completely, the hemp straws are effectively utilized, the wood is saved, the environment and natural resources are protected, and the economic income of farmers is increased. And the lower content of diphenylmethane diisocyanate is used as an adhesive to replace a formaldehyde-containing adhesive, so that the manufacturing cost of the particle board is reduced, and the particle board is safe and non-toxic and is beneficial to human health.

Description

Formaldehyde-free medium-density hemp straw particle board and manufacturing method thereof
Technical Field
The invention relates to the field of artificial boards, in particular to a formaldehyde-free medium-density hemp straw particle board and a manufacturing method thereof.
Background
The particle board is an artificial board made up by cutting various branch buds, small-diameter wood, fast-growing wood, wood dust, etc. into pieces with a certain specification, drying, mixing with adhesive, hardening agent, water-proofing agent, etc. and pressing at a certain temp. and pressure. The product can be widely applied to the building material industry, and can be used for manufacturing various furniture, door panel wallboards, decorative boards, floors and packaging materials.
At present, the manufacturing materials of particle boards in the market are mainly derived from wood, and a large amount of forest resources are required to be occupied. The hemp straw which is a waste of non-grain crops is a valuable renewable resource, and most of the hemp straw is discarded or burnt for a long time and is not reasonably developed and utilized. And all indexes of the particle board manufactured by the prior art can not completely reach the standard, and the adhesive containing formaldehyde is generally used, so that the particle board is not beneficial to human health.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a formaldehyde-free medium-density hemp straw particle board and a manufacturing method thereof.
The technical scheme provided by the invention is as follows:
according to one aspect of the present invention, there is provided a method for manufacturing a formaldehyde-free medium density hemp straw particle board, comprising the steps of:
s1, crushing: crushing hemp straws into two forms of coarse particles with the diameter less than or equal to 5.3 millimeters and fine particles with the diameter less than or equal to 2.1 millimeters;
s2, drying: keeping the water content of the crushed hemp straws below 13%;
s3, glue spraying and stirring: spraying formaldehyde-free adhesive, and stirring coarse and fine particles;
s4, laying of a raw material plate blank: paving the particles after glue spraying and stirring into a raw material plate blank according to a multilayer structure with a fine upper part, a medium coarse part and a fine lower part;
s5, prepressing: pre-pressing the raw material plate blank at the linear pressure of 180-;
s6, hot pressing: under the condition of the temperature of 130-210 ℃, the raw material plate blank is hot-pressed by applying the pressure of 2-12 MPa according to the time period to prepare a rough plate;
s7, cutting: and sawing edges of the hot-pressed rough boards to prepare the formaldehyde-free medium-density hemp straw particle boards.
Further, in step S1, the fine particles having a diameter of 2.1 mm or less account for 50% by weight of the total weight of the pulverized particles.
Further, in step S4, the multi-layer structure with fine top, medium thickness and fine bottom is preferably divided into fine material and coarse material in the ratio of 1:2:1, and the total density is up to 500-3The raw material plate blank amount is weighed in batch and taken, and the density uniformity is less than or equal to 6%.
Further, in step S3, the formaldehyde-free adhesive is diphenylmethane diisocyanate (MDI).
Further, in step S3, the formaldehyde-free adhesive is diphenylmethane diisocyanate (MDI) in an amount of 1.8-4.0% by dry weight of the hemp straw particles, and is sprayed in the form of particles having a diameter of less than 4.8 μm.
Further, in step S3, the formaldehyde-free adhesive is diphenylmethane diisocyanate (MDI), which is preferably sprayed in a form of particles with a diameter of less than 4.8 μm in an amount of 2.1-3.5% of the dry weight of the hemp straw particles; the formaldehyde-free adhesive is diphenylmethane diisocyanate (MDI), and the amount of the formaldehyde-free adhesive is most preferably 2.5-3.4% of the dry weight of the hemp straw particles.
Further, in step S5, the line pressure is preferably 195-; the line pressure is most preferably 200 kg/cm.
Further, in step S6, the hot pressing temperature is preferably 140-.
Furthermore, the steps further comprise a curing and maintaining step: and (3) cooling the hot-pressed particle boards, stacking for 3-5 days under normal temperature and normal humidity conditions, curing, and selling after the curing.
According to another aspect of the invention, the formaldehyde-free medium-density hemp straw particle board is prepared by any one of the above manufacturing methods. The formaldehyde-free medium-density hemp straw particle board comprises a fine-coarse-fine multilayer structure: the fine particle layer comprises hemp straw fine particles and diphenylmethane diisocyanate (MDI); the coarse particle layer comprises hemp straw fine particles and diphenylmethane diisocyanate (MDI); and a fine particle layer comprising hemp straw fine particles and diphenylmethane diisocyanate (MDI).
Compared with the prior art, the invention has at least one of the following beneficial effects:
1. the particle board is made of the hemp straws, wastes are utilized, farmers do not need to burn the hemp straws, the environment is protected, and the economic income of the farmers is increased;
2. hemp straws are used for completely replacing wood as a raw material for manufacturing the particle board, so that the wood is saved, and natural resources are protected;
3. diphenylmethane diisocyanate (MDI) is used as an adhesive to replace a formaldehyde-containing adhesive, so that the adhesive is safe and non-toxic and is beneficial to human health;
4. the usage amount of the diphenylmethane diisocyanate (MDI) is low, and the manufacturing cost of the particle board is reduced.
Drawings
FIG. 1 is a flow chart of an exemplary embodiment of the present invention.
Detailed Description
The present invention will be described in detail with reference to examples.
According to an exemplary embodiment of the present invention, there is provided a method for manufacturing a formaldehyde-free medium density hemp straw particle board, the method comprising the steps of:
s1, crushing: crushing hemp straws into two forms of coarse particles with the diameter less than or equal to 5.3 millimeters (mm) and fine particles with the diameter less than or equal to 2.1 millimeters (mm);
s2, drying: keeping the water content of the crushed hemp straws below 13%;
s3, glue spraying and stirring: spraying formaldehyde-free adhesive, and stirring coarse and fine particles;
s4, laying of a raw material plate blank: paving the particles after glue spraying and stirring into a raw material plate blank according to a multilayer structure with a fine upper part, a medium coarse part and a fine lower part;
s5, prepressing: pre-pressing the raw material plate blank by linear pressure of 180-220kg/cm or 180-220 kg/cm;
s6, hot pressing: under the condition of the temperature of 130-210 ℃, the raw material plate blank is hot-pressed by applying the pressure of 2-12 MPa according to the time period to prepare a rough plate;
s7, cutting: and sawing edges of the hot-pressed rough boards to prepare the formaldehyde-free medium-density hemp straw particle boards.
The hemp straws are crushed into two forms of coarse particles with the diameter less than or equal to 5.3 millimeters (mm) and fine particles with the diameter less than or equal to 2.1 millimeters (mm), dried, sprayed with formaldehyde-free adhesive, stirred with the coarse particles and the fine particles, then paving the particles after glue spraying and stirring into a raw material plate blank according to a fine-coarse-fine multilayer structure with a fine upper part, a medium coarse part and a fine lower part, pre-pressing the raw material slab by the line pressure of 180-220kg/cm or 180-220kg/cm, under the condition of temperature of 130-. Simultaneously solves the problems of waste and environmental pollution caused by the abandonment or incineration of the hemp straws. And by using the adhesive without formaldehyde, the particle board prepared by the invention does not release formaldehyde completely, is safe and non-toxic, and is beneficial to human health.
Preferably, in step S1, the fine particles having a diameter of 2.1 millimeters (mm) or less account for 50% of the total weight of the pulverized particles.
Preferably, in step S4, the multi-layer structure with fine top, medium thickness and fine bottom is divided into fine and coarse materials with a ratio of 1:2:1, and the total density is 500-3Or 500 plus 800 kg/cubic meter of raw material plate blanks are weighed in batches and taken, the weight error is less than and/or equal to 2 percent, and the density uniformity is less than or equal to 6 percent.
Preferably, in step S3, the formaldehyde-free adhesive is diphenylmethane diisocyanate (MDI).
Preferably, in step S3, the formaldehyde-free adhesive is diphenylmethane diisocyanate (MDI) in an amount of 1.8-4.0% by dry weight of the hemp straw particles, and is sprayed in the form of particles having a diameter of less than 4.8 μm.
Preferably, in step S3, the formaldehyde-free adhesive is diphenylmethane diisocyanate (MDI), which is preferably sprayed in an amount of 2.1-3.5% by dry weight of the hemp straw particles in the form of particles having a diameter of less than 4.8 μm; the formaldehyde-free adhesive is diphenylmethane diisocyanate (MDI), and the amount of the formaldehyde-free adhesive is most preferably 2.5-3.4% of the dry weight of the hemp straw particles, and the formaldehyde-free adhesive is sprayed in the form of particles with the diameter of less than 4.8 microns.
In the above examples, the formaldehyde-free binder is diphenylmethane diisocyanate (MDI) in an amount of only 1.8-4.0%, preferably 2.1-3.5%, and most preferably 2.5-3.4% of the dry weight of the hemp straw particles. The lower the usage amount of the diphenylmethane diisocyanate used as an adhesive, the more beneficial the reduction of the manufacturing cost. The embodiment of the invention can use the content which is lower than the dry weight of the hemp straw particles, so that the manufactured particle board can meet the national particle board quality standard.
Preferably, in step S5, the line pressure is preferably 195-; the line pressure is most preferably 200kg/cm or 200kg/cm with a tolerance of not more than 1.5%.
Preferably, in step S6, the hot pressing temperature is preferably 140-.
In the above embodiment, the raw material slab laid according to the fine-coarse-fine multi-layer structure with the upper fine, the middle coarse and the lower fine is pre-pressed, and the line pressure is preferably 195-; the line pressure is most preferably 200kg/cm or 200kg/cm, and then a pressure of from 2 to 12 MPa is applied at a temperature of 140 ℃ and 200 ℃ for a time period, wherein both the temperature and the pressure are varied with time as required for the moisture content of the raw material and the strength of the sheet material, and the thermal pressure error is + -5%.
Preferably, the steps further comprise a curing step: and (3) cooling the hot-pressed particle boards, stacking for 3-5 days under normal temperature and normal humidity conditions, curing, and selling after the curing.
According to an exemplary embodiment of the present invention, there is also provided a formaldehyde-free medium density hemp straw particle board, which is manufactured according to any one of the above-mentioned embodiments of the manufacturing method. The formaldehyde-free medium-density hemp straw particle board comprises a fine-coarse-fine multilayer structure: the fine particle layer comprises hemp straw fine particles and diphenylmethane diisocyanate (MDI); the coarse particle layer comprises hemp straw fine particles and diphenylmethane diisocyanate (MDI); and a fine particle layer comprising hemp straw fine particles and diphenylmethane diisocyanate (MDI), wherein the content of the diphenylmethane diisocyanate (MDI) is 1.8-4.0% of the dry weight of the hemp straw particles, preferably 2.1-3.5%, most preferably 2.5-3.4% of the dry weight of the hemp straw particles, and the hemp straw fine particles are characterized in that the hemp straw is completely used for preparing the hemp straw, the waste of wood is reduced, no formaldehyde adhesive is contained, and the hemp straw fine particles are safe and non-toxic.
The present invention will be further described with reference to the following examples.
Example 1
1. Method for manufacturing formaldehyde-free medium-density hemp straw particle board
FIG. 1 is a flow chart of a method of manufacturing an embodiment of the present invention. As shown in figure 1, the manufacturing method of the formaldehyde-free medium-density hemp straw particle board comprises the following steps:
s1, crushing: crushing hemp straws into two forms of coarse particles with the diameter less than or equal to 5.3 millimeters (mm) and fine particles with the diameter less than or equal to 2.1 millimeters (mm);
s2, drying: keeping the water content of the crushed hemp straws below 13%;
s3, glue spraying and stirring: spraying diphenylmethane diisocyanate (MDI) respectively, and stirring coarse and fine particles, wherein the content of the diphenylmethane diisocyanate (MDI) is 1.8% of the dry weight of the hemp straw particles, and spraying the MDI in the form of particles with the diameter less than 4.8 microns to stir the coarse and fine particles respectively;
s4, laying of a raw material plate blank: according to the multilayer structure with the upper fine, the middle coarse and the lower fine, the fine particles are matched according to the proportion of 1:2: 1: coarse particles: fine particles with a total density of 500-800kg/m3Or weighing and taking the raw material plate blank in batches with the weight of 500 plus 800 kg/cubic meter, and paving the particles after glue spraying and stirring into the raw material plate blank;
s5, prepressing: pre-pressing the raw material plate blank with the linear pressure of 180kg/cm or 180 kg/cm;
s6, hot pressing: then, under the condition that the temperature is changed at 130-220 ℃, applying pressure from 2 to 12 MPa according to time period, and hot-pressing the raw material plate blank to prepare a rough plate, wherein the temperature and the pressure are changed along with time according to the water content of the raw material and the strength of the plate, and the error of the hot pressure is +/-5 percent;
s7, cutting: sawing edges of the hot-pressed rough boards into formaldehyde-free medium-density hemp straw particle boards;
and finally, cooling the hot-pressed particle boards, stacking for 5 days under normal temperature and normal humidity conditions, curing, and selling after the curing.
2. Formaldehyde-free medium-density hemp straw particle board
The formaldehyde-free medium-density hemp straw particle board manufactured by the method comprises a fine-coarse-fine multilayer structure: the fine particle layer comprises hemp straw fine particles and diphenylmethane diisocyanate (MDI); the coarse particle layer comprises hemp straw fine particles and diphenylmethane diisocyanate (MDI); and a fine particle layer comprising hemp straw fine particles and diphenylmethane diisocyanate (MDI), wherein the content of the diphenylmethane diisocyanate (MDI) is 1.8% by dry weight of the hemp straw particles.
Example 2
1. The manufacturing method of the formaldehyde-free medium-density hemp straw particle board comprises the following steps:
s1, crushing: crushing hemp straws twice to form coarse particles with the diameter less than or equal to 5.0 millimeters (mm) and fine particles with the diameter less than or equal to 2.0 millimeters (mm), wherein the fine particles with the diameter less than or equal to 2.1 millimeters (mm) account for 50 percent of the total weight of the particles;
s2, drying: keeping the water content of the crushed hemp straws below 12 percent;
s3, glue spraying and stirring: spraying formaldehyde-free adhesive, and stirring coarse and fine diphenylmethane diisocyanate (MDI), wherein the content of the MDI is 3.1% of the dry weight of the hemp straw particles, and spraying the MDI in the form of particles with a diameter of less than 4.5 μm, and stirring the coarse and fine particles respectively;
s4, laying of a raw material plate blank: according to the multilayer structure with the upper fine, the middle coarse and the lower fine, the fine particles are matched according to the proportion of 1:2: 1: coarse particles: fine particles with a total density of 800kg/m3Or weighing and taking the raw material plate blank amount of 800 kg/cubic meter in batches, and paving the particles after glue spraying and stirring into the raw material plate blank;
s5, prepressing: prepressing a raw material plate blank at a linear pressure of 220 kg/cm;
s6, hot pressing: then, under the condition that the temperature is 140-;
s7, cutting: sawing edges of the hot-pressed rough boards into formaldehyde-free medium-density hemp straw particle boards;
and finally, cooling the hot-pressed particle boards, stacking for 3 days under normal temperature and normal humidity conditions, curing, and selling after the curing.
2. Formaldehyde-free medium-density hemp straw particle board
The formaldehyde-free medium-density hemp straw particle board manufactured by the method comprises a fine-coarse-fine multilayer structure: the fine particle layer comprises hemp straw fine particles and diphenylmethane diisocyanate (MDI); the coarse particle layer comprises hemp straw fine particles and diphenylmethane diisocyanate (MDI); and a fine particle layer comprising hemp straw fine particles and diphenylmethane diisocyanate (MDI), wherein the content of the diphenylmethane diisocyanate (MDI) is 3.1% by dry weight of the hemp straw particles.
Example 3
1. The manufacturing method of the formaldehyde-free medium-density hemp straw particle board comprises the following steps:
s1, crushing: crushing hemp straws twice to form coarse particles with the diameter of less than or equal to 4.5 millimeters (mm) and fine particles with the diameter of less than or equal to 1.8 millimeters (mm), wherein the fine particles with the diameter of less than or equal to 2.1 millimeters (mm) account for 50 percent of the total weight of the particles;
s2, drying: keeping the water content of the crushed hemp straws below 1%;
s3, glue spraying and stirring: spraying formaldehyde-free diphenylmethane diisocyanate (MDI) as coarse and fine diphenylmethane diisocyanate (MDI), wherein the content of the diphenylmethane diisocyanate (MDI) is 3.9% of the dry weight of hemp straw particles, spraying the mixture in the form of particles with a diameter of less than 4 μm, and stirring the coarse and fine particles respectively;
s4, laying of a raw material plate blank: according to the multilayer structure with the upper fine, the middle coarse and the lower fine, the fine particles are matched according to the proportion of 1:2: 1: coarse particles: fine particles with a total density of up to 500kg/m3Or weighing and taking materials in batches according to the quantity of the raw material plate blanks of 500 kilograms per cubic meter, and paving the particles after glue spraying and stirring into the raw material plate blanks;
s5, prepressing: prepressing the raw material plate blank at a linear pressure of 200 kg/cm;
s6, hot pressing: then, under the condition that the temperature is 140-;
s7, cutting: sawing edges of the hot-pressed rough boards into formaldehyde-free medium-density hemp straw particle boards;
and finally, cooling the hot-pressed particle boards, stacking for 5 days under normal temperature and normal humidity conditions, curing, and selling after the curing.
2. Formaldehyde-free medium-density hemp straw particle board
The formaldehyde-free medium-density hemp straw particle board manufactured by the method comprises a fine-coarse-fine multilayer structure: the fine particle layer comprises hemp straw fine particles and diphenylmethane diisocyanate (MDI); the coarse particle layer comprises hemp straw fine particles and diphenylmethane diisocyanate (MDI); and a fine particle layer comprising hemp straw fine particles and diphenylmethane diisocyanate (MDI), wherein the content of the diphenylmethane diisocyanate (MDI) is 3.9% by dry weight of the hemp straw particles.
Example 4
1. A manufacturing method of a formaldehyde-free medium-density hemp straw particle board comprises the following steps:
s1, crushing: crushing hemp straws twice to form coarse particles with the diameter of less than or equal to 4.0 millimeters (mm) and fine particles with the diameter of less than or equal to 1.5 millimeters (mm), wherein the fine particles with the diameter of less than or equal to 2.1 millimeters (mm) account for 50 percent of the total weight of the particles;
s2, drying: keeping the water content of the crushed hemp straws below 5 percent;
s3, glue spraying and stirring: spraying formaldehyde-free diphenylmethane diisocyanate (MDI) serving as an adhesive, and stirring coarse and fine particles of diphenylmethane diisocyanate (MDI), wherein the content of the diphenylmethane diisocyanate (MDI) is 3.4% of the dry weight of the hemp straw particles, and spraying the mixture in the form of particles with the diameter of less than 3.8 microns, and stirring the coarse and fine particles respectively;
s4, laying of a raw material plate blank: according to the multilayer structure with the upper fine, the middle coarse and the lower fine, the fine particles are matched according to the proportion of 1:2: 1: coarse particles: fine particles with a total density of 700kg/m3Or weighing the raw material plate blank amount of 700 kg/cubic meter in batches, taking materials, and paving the particles after glue spraying and stirring into the raw material plate blank;
s5, prepressing: prepressing a raw material plate blank at a linear pressure of 195 kg/cm;
s6, hot pressing: then, under the condition of the temperature of 130-;
s7. cutting: sawing edges of the hot-pressed rough boards into formaldehyde-free medium-density hemp straw particle boards;
and finally, cooling the hot-pressed particle boards, stacking for 3 days under normal temperature and normal humidity conditions, curing, and selling after the curing.
2. Formaldehyde-free medium-density hemp straw particle board
The formaldehyde-free medium-density hemp straw particle board manufactured by the method comprises a fine-coarse-fine multilayer structure: the fine particle layer comprises hemp straw fine particles and diphenylmethane diisocyanate (MDI); the coarse particle layer comprises hemp straw fine particles and diphenylmethane diisocyanate (MI) I); and a fine particle layer comprising hemp straw fine particles and diphenylmethane diisocyanate (MDI), wherein the content of the diphenylmethane diisocyanate (MDI) is 3.4% by dry weight of the hemp straw particles.
Example 5
1. A manufacturing method of a formaldehyde-free medium-density hemp straw particle board comprises the following steps:
s1, crushing: crushing hemp straws twice to form coarse particles with the diameter of less than or equal to 4.8 millimeters (mm) and fine particles with the diameter of less than or equal to 1.2 millimeters (mm), wherein the fine particles with the diameter of less than or equal to 2.1 millimeters (mm) account for 50 percent of the total weight of the particles;
s2, drying: keeping the water content of the crushed hemp straws below 10 percent;
s3, glue spraying and stirring: spraying formaldehyde-free diphenylmethane diisocyanate (MDI) as the coarse and fine diphenylmethane diisocyanate (MDI) particles, wherein the content of the diphenylmethane diisocyanate (MI) I) is 2.5% of the dry weight of the hemp straw particles, spraying the mixture in the form of particles with the diameter less than 3.5 microns, and stirring the coarse and fine particles respectively;
s4, laying of a raw material plate blank: according to the multilayer structure with the upper fine, the middle coarse and the lower fine, the fine particles are matched according to the proportion of 1:2: 1: coarse particles: fine particles in total densityUp to 600kg/m3Or weighing raw material plate blanks of 600 kg/cubic meter in batches, taking materials, and paving the particles subjected to glue spraying and stirring into the raw material plate blanks;
s5, prepressing: prepressing a raw material plate blank at a linear pressure of 205 kg/cm;
s6, hot pressing: then, under the condition that the temperature is changed at 135-215 ℃, applying pressure from 2 to 12 MPa according to the time period, and hot-pressing the raw material plate blank to prepare a rough plate, wherein the temperature and the pressure are changed along with the time according to the water content of the raw material and the strength of the plate, and the error of the hot pressure is +/-5 percent;
s7, cutting: sawing edges of the hot-pressed rough boards into formaldehyde-free medium-density hemp straw particle boards;
and finally, cooling the hot-pressed particle boards, stacking for 4 days under normal temperature and normal humidity conditions, curing, and selling after the curing.
2. Formaldehyde-free medium-density hemp straw particle board
The formaldehyde-free medium-density hemp straw particle board manufactured by the method comprises a fine-coarse-fine multilayer structure: the fine particle layer comprises hemp straw fine particles and diphenylmethane diisocyanate (MI) I); the coarse particle layer comprises hemp straw fine particles and diphenylmethane diisocyanate (MI) I); and a fine particle layer comprising hemp straw fine particles and diphenylmethane diisocyanate (MDI), wherein the content of the diphenylmethane diisocyanate (MDI) is 2.5% by dry weight of the hemp straw particles.
Example 6
1. A manufacturing method of a formaldehyde-free medium-density hemp straw particle board comprises the following steps:
s1, crushing: crushing hemp straws into two forms of coarse particles with the diameter less than or equal to 3.8 millimeters (mm) and fine particles with the diameter less than or equal to 0.8 mm (mm);
s2, drying: keeping the water content of the crushed hemp straws below 8 percent;
s3, glue spraying and stirring: spraying formaldehyde-free diphenylmethane diisocyanate (MDI) as coarse and fine particles, wherein the content of the diphenylmethane diisocyanate (MDI) is 2.1% of the dry weight of the hemp straw particles, spraying the mixture in the form of particles with the diameter less than 3.0 microns, and stirring the coarse and fine particles respectively;
s4, laying of a raw material plate blank: according to the multilayer structure with the upper fine, the middle coarse and the lower fine, the fine particles are matched according to the proportion of 1:2: 1: coarse particles: fine particles with a total density of 750kg/m3Or weighing the raw material plate blank amount of 750 kg/cubic meter in batches, taking materials, and paving the particles after glue spraying and stirring into the raw material plate blank;
s5, prepressing: pre-pressing the raw material plate blank at the linear pressure of 190 kg/cm;
s6, hot pressing: then, under the condition that the temperature is 150-195 ℃, applying pressure from 2 to 12 MPa according to time period, and hot-pressing the raw material plate blank to prepare a rough plate, wherein the temperature and the pressure are changed along with time according to the water content of the raw material and the strength of the plate, and the error of the hot pressure is +/-5 percent;
s7, cutting: sawing edges of the hot-pressed rough boards into formaldehyde-free medium-density hemp straw particle boards;
and finally, cooling the hot-pressed particle boards, stacking for 5 days under normal temperature and normal humidity conditions, curing, and selling after the curing.
2. Formaldehyde-free medium-density hemp straw particle board
The formaldehyde-free medium-density hemp straw particle board manufactured by the method comprises a fine-coarse-fine multilayer structure: the fine particle layer comprises hemp straw fine particles and diphenylmethane diisocyanate (MDI); the coarse particle layer comprises hemp straw fine particles and diphenylmethane diisocyanate (MDI); and a fine particle layer comprising hemp straw fine particles and diphenylmethane diisocyanate (MDI), wherein the content of the diphenylmethane diisocyanate (MDI) is 2.1% by dry weight of the hemp straw particles.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and it will be apparent to those skilled in the art that the embodiments of the present invention and features of the embodiments may be combined with each other to obtain a new embodiment without conflict, and various modifications and changes may be made in the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A manufacturing method of a formaldehyde-free medium-density hemp straw particle board is characterized by comprising the following steps:
s1, crushing: crushing hemp straws into two forms of coarse particles with the diameter less than or equal to 5.3 millimeters and fine particles with the diameter less than or equal to 2.1 millimeters;
s2, drying: keeping the water content of the crushed hemp straws below 13%;
s3, glue spraying and stirring: spraying formaldehyde-free adhesive, and stirring coarse and fine particles;
s4, laying of a raw material plate blank: paving the particles after glue spraying and stirring into a raw material plate blank according to a multilayer structure with a fine upper part, a medium coarse part and a fine lower part;
s5, prepressing: pre-pressing the raw material plate blank at the linear pressure of 180-;
s6, hot pressing: under the condition of the temperature of 130-210 ℃, the raw material plate blank is hot-pressed by applying the pressure of 2-12 MPa according to the time period to prepare a rough plate;
s7, cutting: and sawing edges of the hot-pressed rough boards to prepare the formaldehyde-free medium-density hemp straw particle boards.
2. The method of claim 1, wherein in step S1, the fine particles with a diameter less than or equal to 2.1 mm account for 50% of the total weight of the pulverized particles.
3. The method as claimed in claim 1, wherein in step S4, the multi-layer structure with fine top, medium coarse bottom and fine bottom is divided into fine and coarse materials at a ratio of 1:2:1, and the total density is 500-800kg/m3The raw material plate blank amount is weighed in batch and taken, and the density uniformity is less than or equal to 6%.
4. The method of claim 1, wherein in step S3, the formaldehyde-free binder is preferably diphenylmethane diisocyanate (MDI).
5. The method of claim 1, wherein in step S3, the formaldehyde-free binder is diphenylmethane diisocyanate (MDI) in an amount of 1.8-4.0% by dry weight of the hemp straw particles, and is sprayed in the form of particles having a diameter of less than 4.8 μm.
6. The method of claim 1, wherein in step S3, the formaldehyde-free adhesive is diphenylmethane diisocyanate (MDI) in an amount of preferably 2.1-3.5% by dry weight of the hemp straw particles, and is sprayed in a form of particles having a diameter of less than 4.8 μm;
the formaldehyde-free adhesive is diphenylmethane diisocyanate (MDI), and the amount of the formaldehyde-free adhesive is most preferably 2.5-3.4% of the dry weight of the hemp straw particles.
7. The method as claimed in claim 1, wherein in step S5, the line pressure is preferably 195-205 kg/cm; the line pressure is most preferably 200 kg/cm.
8. The method as claimed in claim 1, wherein the hot pressing temperature is preferably 140-200 ℃ in the step S6.
9. The method for manufacturing the formaldehyde-free medium-density hemp straw particle board as claimed in any one of claims 1 to 8, further comprising the curing step of: and (3) cooling the hot-pressed particle boards, stacking for 3-5 days under normal temperature and normal humidity conditions, curing, and selling after the curing.
10. A formaldehyde-free medium density hemp straw particle board, characterized in that the formaldehyde-free medium density hemp straw particle board manufactured by the manufacturing method according to any one of the above claims 1 to 9.
CN202010551022.2A 2020-06-16 2020-06-16 Formaldehyde-free medium-density hemp straw particle board and manufacturing method thereof Pending CN111673866A (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5945138A (en) * 1982-09-07 1984-03-13 Jujo Paper Co Ltd Fibrous board for molding
US6280667B1 (en) * 1999-04-19 2001-08-28 Andersen Corporation Process for making thermoplastic-biofiber composite materials and articles including a poly(vinylchloride) component
CN101323130A (en) * 2008-07-11 2008-12-17 东北林业大学 Heat pressing production method of polyethylene fiber-plant fibre compound material
CN101642925A (en) * 2009-09-08 2010-02-10 苏州伍得人造板设备有限公司 Urea formaldehyde resin adhesive medium density fiber board utilizing castor bean stalk as raw material
CN109483686A (en) * 2018-10-18 2019-03-19 上海景新信息科技有限公司 A kind of manufacturing method of anesthesia stem Formaldehyde Free Wood-based Panel

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5945138A (en) * 1982-09-07 1984-03-13 Jujo Paper Co Ltd Fibrous board for molding
US6280667B1 (en) * 1999-04-19 2001-08-28 Andersen Corporation Process for making thermoplastic-biofiber composite materials and articles including a poly(vinylchloride) component
CN101323130A (en) * 2008-07-11 2008-12-17 东北林业大学 Heat pressing production method of polyethylene fiber-plant fibre compound material
CN101642925A (en) * 2009-09-08 2010-02-10 苏州伍得人造板设备有限公司 Urea formaldehyde resin adhesive medium density fiber board utilizing castor bean stalk as raw material
CN109483686A (en) * 2018-10-18 2019-03-19 上海景新信息科技有限公司 A kind of manufacturing method of anesthesia stem Formaldehyde Free Wood-based Panel

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