A new type of artificial board and a preparation method thereof

Abstract

The application discloses a novel artificial board and a preparation method thereof. The novel artificial board comprises a core layer and two surface layers on the outer side surfaces of the core layer. The thickness of the core layer is 60-80% of the thickness of the novel artificial board. The core layer comprises the following raw materials in parts by weight: 20-40 parts of polymer glue powder, 60-80 parts of wood raw material, 1-4 parts of dispersing agent and 0.02-0.16 parts of antioxidant. The surface layer comprises the following raw materials in parts by weight: 10-20 parts of adhesive, 80-90 parts of wood raw material. According to the application, the polymer hot melt glue prepared from maleic anhydride grafted polyolefin is used as the adhesive, no organic solvent and formaldehyde are added in the whole processing process, and the environmental protection performance is improved. Meanwhile, the adhesive has strong affinity with the wood raw material, and the mechanical strength of the hot-pressed plate is improved. In addition, the polyolefin material is a non-polar hydrophobic material, can penetrate into the wood fiber under high temperature and high pressure, well wraps the wood fiber, and enhances the overall moisture-proof performance of the plate.

Description

Technical Field

[0001] This invention relates to the field of engineered wood products technology, and specifically to a novel engineered wood product and its preparation method. Background Technology

[0002] Medium-density fiberboard (MDF) and particleboard are currently the most common engineered wood products used in furniture manufacturing, interior decoration, and other fields.

[0003] Medium-density fiberboard (MDF) is made by mixing wood fibers or other plant fibers with synthetic resin adhesives and pressing them under high temperature and pressure. Particleboard is made by mixing sawdust and other wood chips with synthetic resin adhesives and pressing them together. The main advantage of particleboard is its low cost, but it is more prone to absorbing water and warping, affecting its normal use. Both of these types of boards use a lot of liquid adhesives, which releases more formaldehyde, and their nail-holding power is relatively weak, making them unsuitable for frequent disassembly. Summary of the Invention

[0004] To address the aforementioned shortcomings, the technical problem to be solved by this invention is to provide a novel type of engineered wood panel and its preparation method, in order to solve the problems that engineered wood panels manufactured by existing technologies either have relatively weak nail-holding power or are prone to water absorption and deformation.

[0005] Therefore, the first aspect of this application provides a novel engineered wood panel, comprising a core layer and two surface layers located on the outer surface of the core layer, wherein the thickness of the core layer is 60-80% of the thickness of the novel engineered wood panel.

[0006] The core layer comprises the following raw materials in parts by weight: 20-40 parts of polymer powder, 60-80 parts of wood raw material, 1-4 parts of dispersant, and 0.02-0.16 parts of antioxidant;

[0007] The surface layer comprises the following raw materials in parts by weight: 10-20 parts adhesive and 80-90 parts wood raw material.

[0008] In the above technical solution, preferably, the polymer powder is obtained by compounding polyolefin hot melt adhesive powder and polymer resin powder, in parts by weight: 5-35 parts polyolefin hot melt adhesive powder and 2-35 parts resin powder.

[0009] In the above technical solution, preferably, the polymer resin powder can be one or more of powdered low-density polyethylene, high-density polyethylene, polypropylene, and nylon 6, and the raw materials can be pulverized to 40-80 mesh using a plastic grinding mill.

[0010] In the above technical solution, preferably, the polyolefin hot melt adhesive powder can be maleic anhydride-grafted polyolefin.

[0011] In the above technical solution, preferably, the wood raw material used in the surface layer is the same as the wood raw material used in the core layer.

[0012] In the above technical solution, preferably, the adhesive is a urea-formaldehyde resin adhesive.

[0013] In the above technical solution, preferably, the adhesive is diphenylmethane diisocyanate adhesive.

[0014] In the above technical solution, preferably, the adhesive is the same as the polymer powder used in the core layer.

[0015] A second aspect of this application provides a method for preparing the aforementioned novel engineered wood panel, comprising the following steps:

[0016] The wood raw materials are dried to control the moisture content to below 3 wt%.

[0017] Prepare the raw materials according to the component ratio of the surface layer and the core layer, and disperse them evenly through a mixer to obtain the surface layer paving material and the core layer paving material;

[0018] First, lay a layer of surface paving material on the base, then lay the core paving material, and finally lay another layer of surface paving material on the core paving material.

[0019] The laid-out board material is pre-pressed to obtain a preliminary-shaped new type of artificial board blank;

[0020] The rough blank of the new type of artificial board is hot-pressed under high temperature and high pressure to completely melt and solidify the polymer powder. After cooling, the finished new type of artificial board is obtained.

[0021] In the above method, preferably, the pre-pressing process parameters are: hot pressing temperature 100~140℃, hot pressing time 10~60s, hot pressing pressure 5~12MPa; the hot pressing process parameters are: hot pressing temperature 160~240℃, hot pressing time 180~600s, hot pressing pressure 8~20MPa.

[0022] As can be seen from the above technical solution, the novel engineered wood panel and its preparation method provided by this invention solve the problems of relatively weak nail-holding power or easy water absorption and deformation in existing technologies. Compared with existing technologies, this invention has the following beneficial effects:

[0023] A polymeric hot-melt adhesive prepared by grafting maleic anhydride onto polyolefins is used as the adhesive to produce engineered wood panels via a hot-pressing process. No organic solvents or formaldehyde are added during the entire process, thus improving environmental performance. Simultaneously, the polarity of the maleic anhydride groups is similar to that of the hydroxyl groups in wood, resulting in a strong affinity between the adhesive and the wood raw materials, enhancing the mechanical strength of the hot-pressed panels. Furthermore, as a non-polar hydrophobic material, the polyolefin material can penetrate into the wood fibers under high temperature and pressure, effectively encapsulating the fibers and enhancing the overall moisture resistance of the panel. Therefore, the novel engineered wood panel prepared in this application not only possesses excellent mechanical and moisture-proof properties but also exhibits environmental friendliness and high strength advantages due to the absence of organic solvents and formaldehyde in its preparation process. Attached Figure Description

[0024] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the embodiments of the present invention or the prior art will be briefly introduced and explained below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 A cross-sectional view of the novel engineered wood panel provided in this application;

[0026] Figure 2 A flowchart illustrating the preparation method of the novel artificial board provided in this application. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] To provide a clearer explanation and description of the technical solution and implementation of the present invention, several preferred specific embodiments for implementing the technical solution of the present invention are described below.

[0029] It should be noted that the directional terms such as "inner" and "outer", "front" and "back" and "left" and "right" in this article are based on the product's usage status. Obviously, the use of these directional terms does not limit the scope of protection of this solution.

[0030] Currently, the two most common engineered wood products used in furniture manufacturing and interior decoration are medium-density fiberboard (MDF) and particleboard. MDF uses a large amount of liquid adhesive, which releases more formaldehyde, and it also has relatively weak nail-holding power. Particleboard not only has weak nail-holding power but is also more prone to absorbing water and warping, affecting its normal use.

[0031] This application utilizes a high-molecular-weight hot-melt adhesive prepared by grafting maleic anhydride onto polyolefins as the adhesive, and produces engineered wood panels through a hot-pressing process. No organic solvents or formaldehyde are added during the entire processing, thus improving environmental performance. Simultaneously, the polarity of the maleic anhydride groups is similar to that of the hydroxyl groups in wood, resulting in a strong affinity between the adhesive and the wood raw materials, thereby enhancing the mechanical strength of the hot-pressed panels. Furthermore, as a non-polar hydrophobic material, the polyolefin material can penetrate into the wood fibers under high temperature and pressure conditions, effectively encapsulating the wood fibers and enhancing the overall moisture resistance of the panels.

[0032] Specifically, such as Figure 1 As shown, the novel engineered wood panel provided in this application includes a core layer 10 and a surface layer 20 located on the outer surface of the core layer 10, wherein the thickness of the core layer 10 is 60 to 80% of the thickness of the novel engineered wood panel.

[0033] The core layer 10 comprises the following raw materials in parts by weight: 20-40 parts of polymer powder, 60-80 parts of wood raw material, 1-4 parts of dispersant and 0.02-0.16 parts of antioxidant.

[0034] The polymeric adhesive powder is obtained by compounding polyolefin hot melt adhesive powder and polymeric resin powder, in parts by weight: 5-35 parts polyolefin hot melt adhesive powder and 3-17 parts polymeric resin powder.

[0035] The polymer resin powder can be selected from one or more of the following: powdered low-density polyethylene, high-density polyethylene, polypropylene, and nylon 6. For example, it can be a blend of one or more of LDPE 7042, HDPE 8008, PP K8003, and Shijiazhuang Refining & Chemical Nylon PA 6. The blending method is not limited. One embodiment uses a blending ratio of (3-8):(2-10):(4-9) by weight, meaning one component can weigh 3-8 parts, another component can weigh 2-10 parts, and the third component can weigh 4-9 parts. The above raw materials can be pulverized to 40-80 mesh using a plastic pulverizer.

[0036] Maleic anhydride-grafted polyolefins can be used as hot melt adhesive powders, for example, the maleic anhydride-grafted polyolefins produced by the National Engineering Research Center for Engineering Plastics of China National Research Center for Advanced Engineering Plastics Co., Ltd. 2120.

[0037] Wood raw materials are wood chips or wood powder obtained by crushing natural wood, such as 60-mesh poplar wood powder and 10-mesh poplar wood chips.

[0038] Liquid paraffin was selected as the dispersant.

[0039] Antioxidants may be selected from one or more of hindered phenols, hindered amines, and thioesters, such as pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2,6-di-tert-butyl-p-cresol, or dodecyl thiodipropionate, and the mixing ratio is not limited.

[0040] The surface layer 20 comprises the following raw materials in parts by weight: 10-20 parts adhesive and 80-90 parts wood raw material.

[0041] The wood material used in the surface layer 20 is the same as that used in the core layer 10.

[0042] There are three options for the adhesive used in the surface layer 20: one is urea-formaldehyde resin adhesive; the second is isocyanate adhesive, such as diphenylmethane diisocyanate (MDI) adhesive; and the third is polymer powder, which is the same as the polymer powder used in the core layer 10, but the proportion of the polymer powder added can be less than that in the core layer.

[0043] Several typical embodiments of the core layer are shown in Table 1 below.

[0044] Table 1, Examples of Core Layer Component Composition.

[0045]

[0046]

[0047] Several typical implementations of the surface layer are shown in Table 2 below.

[0048] Table 2, Examples of surface layer component composition.

[0049]

[0050] The second aspect of this application provides a method for preparing the aforementioned novel engineered wood panel, such as... Figure 2 As shown, the method includes the following steps:

[0051] Step 110, raw material processing.

[0052] Select wood chips or wood powder after wood processing as wood raw materials and dry them to control the moisture content to below 3 wt%.

[0053] For example, poplar wood powder (60 mesh) or poplar wood chips (10 mesh) are dried at 103℃ for more than 4 hours, with the moisture content controlled below 3wt%.

[0054] Step 120: Mix the raw materials.

[0055] Prepare the raw materials according to the component ratio of the surface layer and the core layer, and disperse them evenly through a mixer to obtain the surface layer paving material and the core layer paving material.

[0056] Step 130, Install the boards.

[0057] First, lay a layer of surface paving material on the base, ensuring it is flat and uniform. Then, lay the core paving material. Finally, lay another layer of surface paving material on top of the core paving material. Ensure that each layer of paving material is tightly bonded.

[0058] Step 140, pre-compression molding.

[0059] The laid-out board material is pre-pressed to obtain a preliminary-formed new type of artificial board blank.

[0060] The pre-pressing process parameters are: hot pressing temperature 100~140℃, hot pressing time 10~60s, and hot pressing pressure 5~12MPa.

[0061] Step 150: Hot pressing molding.

[0062] The rough blank of the new type of artificial board is hot-pressed under high temperature and high pressure to completely melt and solidify the polymer powder. After cooling, the finished new type of artificial board is obtained.

[0063] The hot pressing process parameters are: hot pressing temperature 160~240℃, hot pressing time 180~600s, and hot pressing pressure 8~20MPa.

[0064] This application can produce a new type of artificial board with a thickness of 5 to 40 mm. The following is a performance comparison between the new artificial board with a thickness of 5 mm and existing products. The comparison standard 1 refers to GB / T11718~2021 "Medium-density fiberboard" and the comparison standard 2 refers to GB / T 4897~2015 "Particleboard".

[0065] The physical and chemical properties were tested in accordance with GB / T 17657~2022 "Test Methods for Physical and Chemical Properties of Wood-based Panels and Decorative Wood-based Panels", and the moisture resistance was compared with the standard values ​​under high humidity conditions.

[0066] Formaldehyde emission levels are classified according to the standard GB / T 39600~2021, "Classification of Formaldehyde Emissions from Wood-based Panels and Their Products," with an E1 limit of 0.124 mg / m³. 3 The limit for E0 grade is 0.05 mg / m³. 3 E NF The limit value is 0.025 mg / m³. 3 .

[0067] The test results are shown in the table below:

[0068]

[0069] Based on the above test results, compared with existing particleboard and medium-density fiberboard standards, the novel engineered wood product provided by this invention meets the national standards for static bending strength and water absorption swelling rate. After immersion in water at 70°C, its static bending strength loss is minimal, meeting the requirements for use under high humidity conditions. Specifically, the static bending strength of Example 2, and the static bending strength after immersion treatment, reach 300% of the standard value for particleboard, and the water absorption swelling rate under high humidity conditions is only 10% of the standard value, indicating that the embodiments of this invention exhibit excellent performance in terms of mechanical strength and moisture resistance.

[0070] Meanwhile, the formaldehyde emission levels all comply with the standards for engineered wood products, with the lowest level reaching E. NF The formaldehyde emission level meets the highest requirements of current Chinese standards for formaldehyde emission classification. Therefore, the new type of engineered wood panel prepared using the method described in this application not only possesses excellent mechanical properties and formaldehyde-free characteristics, but also exhibits relatively stable quality under high temperature and high humidity conditions, thus having broad application prospects.

[0071] Currently, the adhesives used in traditional engineered wood products mainly include urea-formaldehyde resin, phenolic resin, and melamine-formaldehyde resin and their modified products (collectively referred to as "three-aldehyde adhesives"). Most three-aldehyde adhesives use formaldehyde as a raw material, and unreacted free formaldehyde is often generated during the production process. Even after the engineered wood products undergo heat-pressing curing, this free formaldehyde is difficult to completely react, resulting in the slow release of formaldehyde during production and use, posing a long-term health hazard to the living environment. Furthermore, traditional three-aldehyde adhesives are generally thermosetting resins, and the cured adhesive layer is often brittle. The cured resin contains hydrophilic free hydroxymethyl groups, which easily combine with moisture, causing it to absorb water, swell, crack, and even deform and twist in high humidity environments. This not only affects the structural strength of the board but also leads to insufficient nail-holding power, limiting the widespread application of engineered wood products.

[0072] The novel engineered wood panel provided by this invention uses polymer powder as an adhesive, leveraging its thermoplasticity to bond the panels. No organic solvents are added during the preparation and processing, thus addressing the formaldehyde release problem at its source and achieving a green and healthy environmentally friendly engineered wood panel. Simultaneously, the polyolefin material itself, as a non-polar hydrophobic material, can penetrate into the wood fibers and effectively encapsulate them under high temperature and pressure, improving the overall moisture resistance of the panel.

[0073] The hot melt adhesive powder used in this invention is maleic anhydride-grafted polyolefin. The maleic anhydride graft contains polar aldehyde groups and non-polar olefin segments. On the one hand, it has excellent compatibility with the matrix material polyolefin; on the other hand, it can chemically bond with the ~OH groups in the wood structure, improving the bonding strength between the polyolefin and the wood structure. Simultaneously, the polarity of the maleic anhydride groups is similar to that of the hydroxyl groups in wood, giving the adhesive a strong affinity for the wood raw material. Therefore, the new type of engineered wood panel has high strength and long-term stability, effectively avoiding the decline in physical properties caused by adhesive aging, thereby extending the service life of the panel.

[0074] Based on the above description of specific embodiments, the high-strength novel environmentally friendly engineered wood panel and its preparation method provided by the present invention have the following advantages compared with the prior art:

[0075] First, this invention uses polymer powder as an adhesive, leveraging its thermoplasticity to bond the boards. The preparation process involves two steps of hot pressing, resulting in a simple workflow. After the polymer powder melts and bonds, its properties remain stable and it does not hydrolyze, thus enhancing the stability of the boards. Polyolefin materials, as non-polar hydrophobic materials, exhibit plastic properties. After hot pressing, they form a continuous hydrophobic phase within the board, thereby improving the overall moisture-proof performance. Depending on the heat resistance requirements of different boards, high-temperature resistant nylon 6 can be added to improve the thermal stability of the boards. Therefore, this new type of engineered wood panel possesses excellent mechanical properties, maintains stable quality under high temperature and humidity conditions, does not easily swell after absorbing water, and exhibits excellent moisture-proof characteristics.

[0076] Secondly, this invention utilizes maleic anhydride-grafted polyolefins as a hot melt adhesive, eliminating the need for formaldehyde in the raw materials and addressing the formaldehyde release problem at its source, thus enabling the prepared engineered wood panels to achieve a higher level of environmental friendliness. Simultaneously, the maleic anhydride groups form chemical bonds with the wood structure, improving the bonding strength between the polyolefin and the wood structure. This further enhances the strength and long-term stability of the panels while using a green and environmentally friendly adhesive, thereby extending the panel's lifespan.

[0077] Finally, it should be noted that the terms "comprising," "including," or any other variations thereof as used herein are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising a…" does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0078] This invention is not limited to the above-described preferred embodiments. Anyone should know that any structural changes made under the guidance of this invention, and any technical solutions that are the same as or similar to this invention, fall within the protection scope of this invention.

Claims

1. A novel engineered wood panel, comprising a core layer and two surface layers located on the outer surface of the core layer, wherein the thickness of the core layer is 60-80% of the thickness of the novel engineered wood panel, characterized in that: The core layer comprises the following raw materials in parts by weight: 60 parts of 60-mesh poplar wood powder, 35 parts of maleic anhydride-grafted polyolefin, 3 parts of high-density polyethylene, 0.1 parts of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate stearyl ester, 0.03 parts of 2,6-di-tert-butyl-p-cresol, 0.03 parts of thioesters, and 2 parts of dispersant. The surface layer comprises the following raw materials in parts by weight: 80 parts of 60-mesh poplar wood powder, 5 parts of maleic anhydride grafted polyolefin, 5 parts of low-density polyethylene, 5 parts of high-density polyethylene, and 5 parts of polypropylene. The method for preparing the novel engineered wood panel includes the following steps: The wood raw materials are dried to control the moisture content to below 3 wt%. Prepare the raw materials according to the component ratio of the surface layer and the core layer, and disperse them evenly through a mixer to obtain the surface layer paving material and the core layer paving material; First, lay a layer of surface paving material on the base, then lay the core paving material, and finally lay another layer of surface paving material on the core paving material. The laid-out board material is pre-pressed to obtain a preliminary-shaped new type of artificial board blank; The rough blank of the new type of artificial board is hot-pressed to completely melt and solidify the polymer powder, and then cooled to obtain the finished new type of artificial board.

2. The novel engineered wood panel according to claim 1, characterized in that, The pre-pressing process parameters are: hot pressing temperature 100~140℃, hot pressing time 10~60s, and hot pressing pressure 5~12MPa; The hot pressing process parameters are: hot pressing temperature 160~240℃, hot pressing time 180~600s, and hot pressing pressure 8~20Mpa.

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