阅读说明：本技术 一种低密度芦苇刨花板及其制备方法 (Low-density reed shaving board and preparation method thereof ) 是由 张蕊 张博 田少文 王建荒 于 2019-10-18 设计创作，主要内容包括：本发明涉及生态板材技术领域,提供了一种低密度芦苇刨花板及其制备方法。本发明提供的制备方法在表层刨花和芯层刨花中加入胶黏剂和增粘剂,通过控制胶黏剂的加入量,提高芦苇刨花表面的胶钉数量(微小胶滴的个数),从而可以在保证芦苇刨花板的物理性能指标的基础上适当地减少芦苇刨花的用量,进而降低芦苇刨花板的密度,提高芦苇刨花板的机械加工使用性能；通过添加增粘剂解决胶黏剂的初粘性差的问题,同时解决胶黏剂固化后脆性大,在芦苇刨花板压贴后会出现龟裂现象,在机械加工时会出现崩边的问题；此外,本发明同时加入胶黏剂和增粘剂还能改善芦苇刨花板表面的密度偏差,提高表面的强度的稳定性。(The invention relates to the technical field of ecological boards, and provides a low-density reed shaving board and a preparation method thereof. According to the preparation method provided by the invention, the adhesive and the tackifier are added into the surface layer wood shavings and the core layer wood shavings, and the number of glue nails (the number of tiny glue drops) on the surfaces of the reed wood shavings is increased by controlling the addition amount of the adhesive, so that the using amount of the reed wood shavings can be properly reduced on the basis of ensuring the physical performance index of the reed shaving board, the density of the reed shaving board is further reduced, and the machining service performance of the reed shaving board is improved; the problem of poor initial viscosity of the adhesive is solved by adding the tackifier, and the problems that the adhesive is high in brittleness after being cured, a cracking phenomenon can occur after a reed shaving board is pressed and attached, and edges can be cracked during machining are solved; in addition, the adhesive and the tackifier are added simultaneously, so that the density deviation of the surface of the reed shaving board can be improved, and the stability of the surface strength is improved.)

1. A preparation method of a low-density reed particle board is characterized by comprising the following steps:

(1) screening dry reed shavings to obtain surface layer shavings and core layer shavings;

(2) mixing the surface layer wood shavings with an adhesive and a tackifier to obtain a surface layer wood shavings mixture; mixing the core layer wood shavings with an adhesive and a tackifier to obtain a core layer wood shavings mixture; wherein the mass ratio of the surface layer wood shavings to the adhesive to the tackifier is 1 (0.055-0.07) to (0.00018-0.00028), and the mass ratio of the core layer wood shavings to the adhesive to the tackifier is 1 (0.055-0.07) to (0.0002-0.0003);

(3) paving the surface layer shaving mixture, the core layer shaving mixture and the surface layer shaving mixture from bottom to top to form a lower surface layer, a core layer and an upper surface layer to obtain a plate blank;

(4) carrying out hot pressing on the plate blank to obtain a reed shaving rough plate; the thickness of the reed shaving wool board is 6-42 mm, and the density is 530-780 kg/m³；

(5) And (3) performing thickness setting and fine sanding on the reed shaving rough board to obtain the low-density reed shaving board.

2. The method according to claim 1, wherein the water content of the dried reed shavings in step (1) is 1.5-5%.

3. The method according to claim 1, wherein the screening method in step (1) is: sieving with 0.2 × 0.2mm mesh sieve, taking fine reed powder as undersize, sieving with 1.4 × 1.4mm mesh sieve as oversize, taking surface layer shavings as undersize, and sieving with 10 × 10mm mesh sieve as undersize, and taking core layer shavings as undersize.

4. The preparation method according to claim 1, wherein the adhesive in the step (2) is a polyphenyl polymethylene isocyanate or a derivative thereof; the viscosity of the adhesive at 20 ℃ is 150-250 mPa & s.

5. The method according to claim 1, wherein the tackifier in the step (2) is a vinyl acetate-ethylene copolymer emulsion.

6. The method according to claim 1, wherein the amount of the wood wool on the upper layer in the step (3) is 21 to 24kg/m in terms of the mass of the wood wool²The wood shaving spreading amount of the lower surface layer is 22.1-25.2 kg/m²The wood shaving laying amount of the core layer is 18.70-20.30 kg/m²。

7. According to claim 1The preparation method is characterized in that the hot pressing temperature in the step (4) is 220-240 ℃, and the pressure is 2-5N/mm²The time is 8-10 s/mm.

8. The method as claimed in claim 1, wherein the dried wood shavings of reed in step (1) are prepared by the steps of:

rolling and cutting the reed to obtain reed sections; and purifying the reed sections, then carrying out classification screening to obtain wet reed shavings with the thickness of 0.5-1.2 mm, and drying the wet reed shavings to obtain dry reed shavings.

9. A low density reed particle board prepared by the method of any one of claims 1 to 8.

Technical Field

The invention relates to the technical field of ecological boards, in particular to a low-density reed shaving board and a preparation method thereof.

Background

The reed resources in China are rich and widely distributed, the reed is an annual herbaceous plant, and statistics shows that the total amount of reed in China is about 250 ten thousand tons per year at present, and the total amount of reed accounts for about 6 percent of the total world output. At present, the reed is mainly used as a papermaking raw material in the aspect of industrial application. With the increasing shortage of wood resources, finding wood substitute raw materials is receiving more and more extensive attention. The reed has physical and chemical characteristics close to that of wood and cellulose content equivalent to that of the wood, so that the reed can be used as a substitute material of the wood to produce artificial boards.

Patent CN107243975A proposes a reed shaving board and a preparation method thereof, which uses reed shaving as a raw material and poly-polyphenyl polymethylene isocyanate or derivatives thereof as an adhesive to produce the shaving board, and the obtained shaving board can be used for furniture production, indoor and outdoor decoration, packaging materials and the like. However, the technical scheme only discloses a process for preparing a shaving board by using reeds as raw materials, the research concept is only to primarily realize effective utilization of resources, and whether various performances of the shaving board meet requirements is not deeply researched too much, the formaldehyde emission of the shaving board is only determined, and detection shows that the physical performance index (internal bonding strength) of the shaving board prepared by the method is unqualified when the density of the shaving board is low, so that the density of the shaving board is required to be improved, but the density of the shaving board is high, and the mechanical processing performance is poor.

Disclosure of Invention

In view of the above, the present invention aims to provide a low-density reed particle board and a preparation method thereof. The reed shaving board prepared by the invention has low density, good mechanical processing usability and high strength stability.

In order to achieve the above object, the present invention provides the following technical solutions:

a preparation method of a low-density reed particle board comprises the following steps:

(1) screening dry reed shavings to obtain surface layer shavings and core layer shavings;

(2) mixing the surface layer wood shavings with an adhesive and a tackifier to obtain a surface layer wood shavings mixture; mixing the core layer wood shavings with an adhesive and a tackifier to obtain a core layer wood shavings mixture; wherein the mass ratio of the surface layer wood shavings to the adhesive to the tackifier is 1 (0.055-0.07) to (0.00018-0.00028), and the mass ratio of the core layer wood shavings to the adhesive to the tackifier is 1 (0.055-0.07) to (0.0002-0.0003);

(3) paving the surface layer shaving mixture, the core layer shaving mixture and the surface layer shaving mixture from bottom to top to form a lower surface layer, a core layer and an upper surface layer to obtain a plate blank;

(4) carrying out hot pressing on the plate blank to obtain a reed shaving rough plate; the thickness of the reed shaving wool board is 6-42 mm, and the density is 530-780 kg/m³；

(5) And (3) performing thickness setting and fine sanding on the reed shaving rough board to obtain the low-density reed shaving board.

Preferably, the water content of the dry reed shavings in the step (1) is 1.5-5%.

Preferably, the screening method in step (1) is: sieving with 0.2 × 0.2mm mesh sieve, taking fine reed powder as undersize, sieving with 1.4 × 1.4mm mesh sieve as oversize, taking surface layer shavings as undersize, and sieving with 10 × 10mm mesh sieve as undersize, and taking core layer shavings as undersize.

Preferably, the adhesive in the step (2) is polyphenyl polymethylene isocyanate or a derivative thereof; the viscosity of the adhesive at 20 ℃ is 150-250 mPa & s.

Preferably, the tackifier in step (2) is a vinyl acetate-ethylene copolymer emulsion.

Preferably, the wood shaving laying amount of the upper surface layer in the step (3) is 21-24 kg/m based on the mass of the wood shavings²The wood shaving spreading amount of the lower surface layer is 22.1-25.2 kg/m²The wood shaving laying amount of the core layer is 18.70-20.30 kg/m²。

Preferably, the hot pressing temperature in the step (4) is 220-240 ℃, and the pressure is 2-5N/mm²The time is 8-10 s/mm.

Preferably, the dried reed shavings obtained in step (1) are prepared by the following steps:

rolling and cutting the reed to obtain reed sections; and purifying the reed sections, then carrying out classification screening to obtain wet reed shavings with the thickness of 0.5-1.2 mm, and drying the wet reed shavings to obtain dry reed shavings.

The invention provides a low-density reed shaving board prepared by the preparation method in the scheme.

The invention provides a preparation method of a low-density reed shaving board, which is characterized in that an adhesive and a tackifier are added into surface layer shavings and core layer shavings, and the number of adhesive nails (the number of tiny adhesive drops) on the surfaces of the reed shavings is increased by controlling the addition amount of the adhesive, so that the using amount of the reed shavings can be properly reduced on the basis of ensuring the physical performance indexes of the reed shaving board, the density of the reed shaving board is further reduced, the machining service performance of the reed shaving board is improved, the abrasion of a cutter during machining is reduced, the using amount of reeds can be reduced, the problem of raw material shortage is solved, the transportation cost is reduced, the product sale cost is reduced, and the labor intensity of carrying is reduced; the problem of poor initial viscosity of the adhesive is solved by adding the tackifier, and the problems that the adhesive is high in brittleness after being cured, a cracking phenomenon can occur after a reed shaving board is pressed and attached, and edges can be broken during machining are solved; in addition, the adhesive and the tackifier are added simultaneously, so that the density deviation of the surface of the reed shaving board can be improved, and the stability of the surface strength is improved.

Detailed Description

The invention provides a preparation method of a low-density reed particle board, which comprises the following steps:

(1) screening dry reed shavings to obtain surface layer shavings and core layer shavings;

(2) mixing the surface layer wood shavings with an adhesive and a tackifier to obtain a surface layer wood shavings mixture; mixing the core layer wood shavings with an adhesive and a tackifier to obtain a core layer wood shavings mixture; wherein the mass ratio of the surface layer wood shavings to the adhesive to the tackifier is 1 (0.055-0.07) to (0.00018-0.00028), and the mass ratio of the core layer wood shavings to the adhesive to the tackifier is 1 (0.055-0.07) to (0.0002-0.0003);

(3) paving the surface layer shaving mixture, the core layer shaving mixture and the surface layer shaving mixture from bottom to top to form a lower surface layer, a core layer and an upper surface layer to obtain a plate blank;

(4) carrying out hot pressing on the plate blank to obtain a reed shaving rough plate;

(5) and (3) carrying out thickness setting and fine sanding on the reed shaving rough board to obtain the reed shaving board.

The invention screens the dry reed shavings to obtain surface layer shavings and core layer shavings. In the present invention, the dry reed shavings are preferably prepared by the following steps: rolling and cutting the reed to obtain reed sections; purifying the reed sections, then carrying out classification screening to obtain wet reed shavings with the thickness of 0.5-1.2 mm, and drying the wet reed shavings to obtain dry reed shavings; in the present invention, the length of the reed section is about 35 mm; the invention preferably purifies the reed section by mechanical screening and air flow sorting, and removes impurities in the reed section by purification, wherein the impurities comprise reed pith, reed flower and the like, the impurity removal rate is more than 98 percent, and the removed impurities can be used as fuel to provide heat for the drying of subsequent reed wet shavings and the hot pressing of plate blanks; in the invention, the water content of the wet reed wood shavings is preferably 15-20%; according to the method, qualified reed wet wood shavings with the thickness of 0.5-1.2 mm are screened out through classified screening, and the cylindrical reed wet wood shavings which are not split or not completely split are removed and reprocessed for reuse. In the invention, the drying temperature is preferably 450-550 ℃, and more preferably 500 ℃; the water content of the dried reed shavings obtained after drying is preferably 1.5-5%, more preferably 2-3%.

After obtaining the dry reed shavings, screening the dry reed shavings to obtain surface layer shavings and core layer shavings; the screening method is preferably as follows: firstly, screening by using a screen with meshes of 0.2 multiplied by 0.2mm, wherein the undersize is fine reed powder, the rest oversize is screened by using a screen with meshes of 1.4 multiplied by 1.4mm, the undersize is surface layer wood shavings, the rest oversize is screened by using a screen with meshes of 10 multiplied by 10mm, and the undersize is core layer wood shavings; in the present invention, the screened fine reed powder is used as fuel to provide heat for drying wet reed shavings and hot pressing of slabs, and the oversize shavings not passing through the 10X 10mm screen are preferably fed into a screen ring type grinder to be ground and then the screening step is repeated.

After the surface layer wood shavings and the core layer wood shavings are obtained, mixing the surface layer wood shavings with an adhesive and a tackifier to obtain a surface layer wood shavings mixture; and mixing the core layer wood shavings with the adhesive and the tackifier to obtain a core layer wood shavings mixture. In the invention, in the surface layer wood shaving mixture, the mass ratio of the surface layer wood shavings to the adhesive to the tackifier is 1 (0.055-0.07) to (0.00018-0.00028), preferably 1:0.06 to (0.0002-0.00025), and more preferably 1:0.06 to 0.00023; in the mixture of the core layer wood shavings, the mass ratio of the core layer wood shavings to the adhesive to the tackifier is 1 (0.055-0.07) to (0.0002-0.0003), preferably 1:0.06 (0.00022-0.00028), and more preferably 1:0.06: 0.00025. In the invention, the adhesive is preferably polyphenyl polymethylene isocyanate or a derivative thereof, and the viscosity of the adhesive at 20 ℃ is preferably 150-250 mPa & s, and more preferably 180-220 mPa & s; the tackifier is preferably vinyl acetate-ethylene copolymer emulsion.

According to the invention, the adhesive and the tackifier are added into the surface layer wood shavings and the core layer wood shavings, and the number of the glue nails (the number of tiny glue drops) on the surfaces of the reed wood shavings is increased by controlling the addition amount of the adhesive and the tackifier, so that the number of the reed wood shavings can be properly reduced on the basis of ensuring the physical performance index of the reed shaving board, the density of the reed shaving board is further reduced, and the machining service performance of the reed shaving board is improved; the addition of the tackifier can solve the problem of poor initial viscosity of the adhesive, and simultaneously solve the problems that the adhesive is high in brittleness after being cured, a cracking phenomenon can occur after a reed shaving board is pressed and attached, and edges can be broken during mechanical processing; in addition, the adhesive and the tackifier are added simultaneously, so that the density deviation of the surface of the reed shaving board can be improved, and the stability of the surface strength is improved.

After the surface layer wood shaving mixture and the core layer wood shaving mixture are obtained, the surface layer wood shaving mixture, the core layer wood shaving mixture and the surface layer wood shaving mixture are paved from bottom to top to form a lower surface layer, a core layer and an upper surface layer, and the lower surface layer, the core layer and the upper surface layer are obtainedAnd (5) a slab. In the invention, the wood shaving laying amount of the upper surface layer is preferably 21-24 kg/m based on the mass of the wood shavings²More preferably 22 to 23kg/m²(ii) a The preferable wood shaving laying amount of the lower surface layer is 22.1-25.2 kg/m²More preferably 23 to 24kg/m²(ii) a The preferable wood shaving laying amount of the core layer is 18.70-20.30 kg/m²More preferably 19 to 20kg/m²(ii) a In the invention, the pavement thickness of the upper surface layer is preferably 2-5 mm, more preferably 3-4 mm, the pavement thickness of the lower surface layer is preferably 4-32 mm, more preferably 6-30 mm, and the pavement thickness of the core layer is preferably 2-5 mm, more preferably 3-4 mm.

After the board blank is obtained, the board blank is hot-pressed to obtain the reed shaving rough board. According to the invention, the upper surface and the lower surface of the plate blank are respectively sprayed with the release agent before hot pressing, and the spraying amount of the release agent is 2-10 g/m²Preferably 3 to 5g/m²(ii) a The release agent is preferably a polyether polyol.

In the invention, the hot pressing temperature is preferably 220-240 ℃, more preferably 225-230 ℃, and the pressure is preferably 2-5N/mm²More preferably 3 to 4N/mm²The time is preferably 8 to 10s/mm, and more preferably 9 s/mm. The invention controls the hot pressing temperature in the range, can improve the surface bonding strength of the shaving board and improve the curing strength at the same time.

In the invention, the thickness of the reed shaving wool board is 6-42 mm, preferably 8-36 mm, and the density is 530-780 kg/m³(ii) a Preferably 540 to 750kg/m³(ii) a The invention preferably carries out thickness measurement and weighing on the obtained hot-pressed board after hot pressing is finished, and the board with the thickness and the density meeting the requirements is the qualified reed shaving rough board. The method preferably cools the qualified reed shaving rough board to 10-50 ℃, and more preferably cools the reed shaving rough board to 20-30 ℃.

After the reed shaving rough board is obtained, the reed shaving rough board is preferably subjected to thickness setting and fine sanding to obtain the low-density reed shaving board. In the invention, the size of the fixed thickness is preferably 5-41 mm, and more preferably 7-35 mm; the density of the low-density reed particle board is slightly lower than that of the reed particlesThe density of the reed shaving rough board is preferably 520-780 kg/m³. The method for thickness fixing and fine sanding has no special requirement, and the method is well known by the technical personnel in the field, and waste materials and sanding powder generated in the production process of thickness fixing and sanding are collected and then used as fuel to burn, so that heat is provided for drying reed wet wood shavings and hot pressing of plate blanks.

The invention also provides the low-density reed particle board prepared by the preparation method in the scheme. The reed particle board provided by the invention is low in density (the density of the 18mm reed particle board prepared by the traditional method is 740-750 kg/m)³The density of the 18mm reed particle board prepared by the method is only 690-700 kg/m³) The reed shaving board has the advantages of good mechanical property, uniform strength, difficult cracking phenomenon and good machining property, can improve the production efficiency, reduce the using amount of reed shavings and solve the problem of lack of raw materials.

The embodiments of the present invention will be described in detail with reference to the following examples, but they should not be construed as limiting the scope of the present invention.