A high-strength particleboard and its preparation method

Abstract

This invention discloses a high-strength particleboard and its preparation method, belonging to the field of particleboard production technology. The high-strength particleboard includes an upper surface layer, a core layer, and a lower surface layer. Its key feature is that the lower and upper surface layers are laid in a gradient pattern. The beneficial effects of this invention are: using two types of wood chips of different sizes, shapes, and moisture contents, mixed with adhesive to prepare the core layer, forming a homogeneous structure of core layer wood chips; employing a method of mixing adhesive first and then blending materials, separately mixing the adhesive improves the expansion rate of the wood chips after water absorption, thereby obtaining a homogeneous core layer structure with uniformly mixed wood chips of different sizes. The high-strength particleboard has high strength and good physical and mechanical properties, with high internal bond strength, static bending strength, elastic modulus, and screw holding force.

Description

Technical Field

[0001] This invention belongs to the field of particleboard production technology, and more specifically relates to a high-strength particleboard and its preparation method. Background Technology

[0002] Particleboard is the most widely used engineered wood product, effectively replacing logs and sawn timber in construction, decoration, furniture, flooring manufacturing, and other fields. It can also be used to manufacture 1m³ of particleboard. 3 Approximately 1.4m of particleboard is needed. 3 The timber (materials can be obtained from plantations, fast-growing and high-yield forests, "three wastes" and "small-sized firewood") can replace 3m 3 Sawn timber or 5m 3 Logs, in this way, not only save precious natural forest timber and improve resource utilization, but also meet the demand for timber products in economic and social development.

[0003] The engineered wood products manufacturing industry is a core industry in my country's timber industry, focusing on the comprehensive utilization and conservation of timber resources, and is an important component of my country's timber industry. With the development of the social economy and the improvement of people's living standards, the demand for engineered wood products with excellent performance, wide application, and strong adaptability is increasing day by day.

[0004] Currently, the particleboard market is developing towards diversification, including ordinary particleboard, high-strength particleboard, oriented strand board (OSB), decorative OSB, bamboo particleboard, straw particleboard, reed particleboard, and so on. Product diversification can alleviate dependence on timber resources to some extent, but from a long-term development perspective, each enterprise must also consider how to conserve timber resources.

[0005] In recent years, the downstream furniture customization industry has developed rapidly, leading to a sharp increase in the demand for high-quality, high-strength particleboard. Ordinary particleboard can hardly meet these requirements. Because the core layer of ordinary particleboard is made from a single type of small wood chips through gluing, mixing, and laying, its physical and mechanical properties are relatively poor. This is mainly manifested in its low static bending strength; when the span within a cabinet is large, the board's bending resistance decreases significantly under pressure, requiring the use of hardware or reinforcements to improve its load-bearing capacity. How to improve the static bending strength of particleboard and overcome the limitations imposed by the board material on customized furniture design is a pressing issue that the furniture market needs to address.

[0006] After years of research and development, our company has developed a high-strength particleboard product. Its key feature is the improvement in particleboard performance by increasing the length of the wood chips to alter their shape. Compared to ordinary particleboard, its physical and mechanical properties are improved. The principle is as follows: increasing the length of the wood chips changes their shape. These larger chips, under the mechanical action of mixing adhesives, are sheared into chips of varying sizes. These chips, through the action of the adhesive, form a high-strength particleboard product, resulting in improved physical and mechanical properties compared to ordinary particleboard, particularly enhanced static bending strength.

[0007] However, this method has certain drawbacks. The principle behind it is to increase the length of the wood shavings to change their shape. These larger wood shavings can be broken into different sizes by shearing force under the mechanical action of mixing the adhesive. Since the breaking of the wood shavings by increasing the length of the wood shavings is a random force under mechanical action, it is affected by the rotation speed, gravity, the arrangement of the broken wood shavings, and temperature. This results in significant differences in the size and shape of the wood shavings formed by the mechanical shearing force, which manifests as performance fluctuations in different batches of high-strength particleboard products. Summary of the Invention

[0008] To address the aforementioned problems and overcome the shortcomings of existing technologies, this invention provides a high-strength particleboard and its preparation method. This method effectively solves the problem that increasing the length of the particleboard alters the random force that causes the particleboard to break under mechanical action. This force is influenced by factors such as rotational speed, gravity, the arrangement of the broken particleboard particles, and temperature, leading to significant differences in the size and shape of the particleboard particles formed by the mechanical shearing force. This results in performance fluctuations in high-strength particleboard products from different batches.

[0009] The specific technical solution of this invention to solve the above-mentioned technical problems is as follows: a high-strength particleboard and a preparation method thereof, wherein the high-strength particleboard comprises an upper surface layer, a core layer, and a lower surface layer, characterized in that the preparation method of the high-strength particleboard includes:

[0010] (1) Laying: Lay the lower surface layer, core layer and upper surface layer in sequence according to the preset method;

[0011] (2) Pre-compression: The slab strips of the laid lower surface layer, core layer and upper surface layer are pre-compressed to give the slab a certain initial strength;

[0012] (3) Hot pressing: The pre-pressed slab strip is hot pressed at a temperature of 190~250℃.

[0013] (4) Sanding and trimming: Similar to ordinary particleboard, the pre-cured layer on the board surface and the rough edges of the product are sanded off and trimmed to obtain the finished board.

[0014] Furthermore, the paving method for the lower and upper surfaces is a gradient paving.

[0015] Furthermore, the gradient paving steps for the lower and upper surface layers include:

[0016] (1) Applying adhesive: Add the adhesive and curing agent to the surface wood shavings;

[0017] (2) Mixing adhesive: The surface wood shavings after adhesive application are mixed with adhesive using a ring mixer to obtain surface wood shavings material;

[0018] (3) Gradual paving: The surface shavings after mixing with adhesive are paved through a surface airflow paving machine or a surface diamond roller paving machine to obtain a lower or upper surface layer with a gradual structure.

[0019] Furthermore, the surface wood shavings have dimensions of 0.1-10 mm in length, 0.1-2 mm in width, and 0.1-0.7 mm in thickness, with a moisture content of 1.0-1.5%.

[0020] Furthermore, the amount of adhesive applied to the surface wood shavings is 3-12%, and the adhesive is a urea-formaldehyde resin adhesive, a modified urea-formaldehyde resin adhesive, or an MDI isocyanate ester.

[0021] Furthermore, the core layer is laid in a homogeneous manner.

[0022] Furthermore, the step of homogeneously laying the core layer includes:

[0023] (1) Apply adhesive: Add adhesive and curing agent to the large core wood shavings and the small core wood shavings respectively;

[0024] (2) Mixing the adhesive: The small core layer wood shavings after adhesive application are mixed with an ordinary ring mixer; the large core layer wood shavings after adhesive application are mixed with a flexible ring mixer.

[0025] (3) Mixing; The core layer large and small wood shavings after mixing are thoroughly mixed through a drum mixer to obtain core layer mixed wood shavings;

[0026] (4) Homogeneous paving: The core layer mixed with wood shavings is paved by a core layer cage structure paving machine to obtain a core layer with a homogeneous structure.

[0027] Furthermore, the core layer large wood shavings are 30-80mm long, 3-25mm wide, and 0.7-1.2mm thick, with a moisture content of 1.0-1.5%; the core layer small wood shavings are 10-30mm long, 1-3mm wide, and 0.7-1.2mm thick, with a moisture content of 1.0-1.5%.

[0028] Furthermore, the amount of adhesive applied to the large core layer wood shavings is generally 3-10%, and the amount of adhesive applied to the small core layer wood shavings is generally 3-10%; the adhesive is a urea-formaldehyde resin adhesive, a modified urea-formaldehyde resin adhesive, or an MDI isocyanate adhesive.

[0029] The beneficial effects of this invention are:

[0030] This invention features the use of two types of wood shavings of different sizes, shapes, and moisture contents to prepare the core layer after mixing with adhesive, forming a homogeneous structure of wood shavings in the core layer. This is different from the prior art which uses only one type of wood shavings to prepare the core layer after mixing with adhesive, thus improving the static bending strength of the particleboard.

[0031] One advantage of this invention is that, based on the core layer mixing components of two types of core layer mixing machines, it adopts a form of mixing the adhesive first and then mixing the materials. The separate mixing of adhesives improves the expansion rate of the wood chips after absorbing water, thereby obtaining a homogeneous core layer wood chip structure with uniform mixing of large and small wood chips. The high-strength particleboard has high strength, good physical and mechanical properties, and high internal bond strength, static bending strength, elastic modulus and screw holding force. Attached Figure Description

[0032] Appendix Figure 1 This is a diagram showing the external shape of the particleboard prepared according to the present invention;

[0033] Appendix Figure 2 Here is a cross-sectional view of the particleboard prepared according to the present invention: Detailed Implementation

[0034] Specific details in the description of this invention are merely to provide a thorough understanding of the embodiments thereof; however, those skilled in the art should understand that the implementation of this invention is not limited to these details. Furthermore, well-known structures and functions have not been described or shown in detail to avoid obscuring the key points of the embodiments of this invention. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0035] Specific embodiments of the present invention:

[0036] To better understand the present invention, specific embodiments are described. It is worth emphasizing that the effects of these embodiments are not substantially different from those of various embodiments within the scope of protection of the present invention, including their respective reagents and reagent content ratios. All of them can achieve the effects described in the present invention and solve the above-mentioned problems. Other combinations are not described here.

[0037] Example 1:

[0038] Step 1: Obtaining wood shavings:

[0039] (1.1) Logs or wood processing residues are cut by a chipper to produce wood chips about 60mm in length. The chips are then passed through a wood chip sieve to obtain large and small wood chips. The large wood chips are about 40-80mm in size and the small wood chips are about 5-40mm in size.

[0040] (1.2) Large wood chips are planed by a low-speed ring planer to obtain wood shavings with a length-to-thickness ratio of about 0-80. After drying, they are screened to obtain core wood shavings and surface wood shavings.

[0041] (1.3) The small wood chips are planed by a high-speed ring planer to obtain wood shavings with a length-to-thickness ratio of about 0-40. After drying, they are screened to obtain core wood shavings and surface wood shavings.

[0042] Among them, core layer shavings and surface layer shavings can be obtained either through preparation or by purchase, and the necessary attributes are:

[0043] The surface wood shavings are 0-10mm long, 0-2mm wide, and 0-0.7mm thick, with a moisture content of 1.0-1.5%.

[0044] The core layer of large wood shavings has a length of 30-80mm, a width of 3-25mm, a thickness of 0.7-1.2mm, and a moisture content of 1.0-1.5%.

[0045] The core layer shavings are 10-30mm long, 1-3mm wide, and 0.7-1.2mm thick, with a moisture content of 1.0-1.5%. Any material possessing the above properties can achieve the same or similar technical effects as this invention.

[0046] Among them, the ordinary ring-type glue mixer has a closed structure, with the shell not rotating and the middle shaft rotating; the rotating main shaft is equipped with mixing claws, and the mixing section for glue and wood shavings is generally designed with pointed claws. This type of glue mixer has a relatively fast speed, about 500 revolutions per minute.

[0047] Among them, the flexible glue mixer has a closed structure. The shell does not rotate, but the central shaft rotates. However, the internal cavity volume is relatively large. The rotating main shaft is equipped with mixing claws. The glue and wood shavings mixing section is generally designed with flat claws. This type of glue mixer has a relatively slow speed, about 350 revolutions per minute.

[0048] Step 2: Installation: Install the lower surface layer, core layer and upper surface layer in sequence according to the preset method;

[0049] (2.1) The gradient paving steps for the lower and upper surface layers include:

[0050] (2.1.1) Applying adhesive: Add the adhesive and curing agent to the surface wood shavings. If urea-formaldehyde resin adhesive or modified urea-formaldehyde resin adhesive is used, the amount of adhesive applied to the surface wood shavings is generally 9-12%. If MDI isocyanate is used as the adhesive, the amount of adhesive applied to the surface wood shavings is generally 3-4%.

[0051] (2.1.2) Mixing adhesive: The surface wood shavings after adhesive application are mixed with adhesive using a ring mixer to obtain surface wood shavings material;

[0052] (2.1.3) Gradual paving: The surface wood shavings after mixing with adhesive are paved using a surface airflow paving machine or a surface diamond roller paving machine to obtain a lower or upper surface layer with a gradual structure.

[0053] (2.2) The core layer is homogeneously laid out, including the following steps:

[0054] (2.2.1) Adhesive application: Add adhesive and curing agent to the large and small core wood chips respectively; if urea-formaldehyde resin adhesive or modified urea-formaldehyde resin adhesive is used, the adhesive application amount for the large core wood chips is generally 6-10%, and the adhesive application amount for the small core wood chips is generally 7-10%; if MDI isocyanate is used as adhesive, the adhesive application amount for the large core wood chips is generally 3-4%, and the adhesive application amount for the small core wood chips is generally 3-4%. The above adhesive application amount refers to the mass ratio of the glue solids content to the wood chip quantity;

[0055] (2.2.2) Mixing the adhesive: The small core layer shavings after adhesive application are mixed using a regular ring mixer; the large core layer shavings after adhesive application are mixed using a flexible ring mixer.

[0056] (2.2.3) Mixing; The core layer large and small wood shavings after mixing are thoroughly mixed using a drum mixer to obtain core layer mixed wood shavings;

[0057] (2.2.4) Homogeneous paving: The core layer mixed with wood shavings is paved by a core layer cage structure paving machine to obtain a core layer with a homogeneous structure.

[0058] Step 3: Pre-compression: Pre-compress the slab strips of the laid lower surface layer, core layer and upper surface layer to give the slab a certain initial strength;

[0059] Step 4: Hot pressing. The pre-pressed slab strip is hot-pressed at a temperature of 190~250℃.

[0060] Step 5: Sanding and trimming: Sanding off the pre-cured layer on the board surface and trimming the rough edges of the product to obtain the finished board.

[0061] To more intuitively demonstrate the technological advantages of this invention, a comparison is made between the high-strength particleboard preparation method of this invention and the equivalent substitution method of the same process.

[0062] Comparative Example 1:

[0063] The core layer installation process includes the following steps:

[0064] (1) Apply adhesive: Add adhesive to the core layer of extra-large wood shavings. Extra-large wood shavings also refer to OSB wood shavings, with a length of 50-150mm, a width of 8-30mm, and a thickness of 0.5-1.0mm.

[0065] (2) Mixing the adhesive: The core layer of extra-large wood shavings after adhesive application is mixed with adhesive using a drum mixer;

[0066] (3) Paving: The core layer of extra-large wood shavings is paved by a cage-type paving machine to obtain a core layer with a homogeneous structure.

[0067] Comparative Example 2:

[0068] The preparation method is the same as in Example 1, except that the core layer is homogeneously laid out. The difference is that mixing is done before applying the adhesive. Specifically, the homogeneous laying out steps for the core layer include:

[0069] (1) Mixing; the large and small core wood shavings are thoroughly mixed by a drum mixer;

[0070] (2) Apply adhesive: Add an equal amount of adhesive to the mixed wood shavings;

[0071] (3) Mixing the adhesive: The mixed wood shavings are mixed using a regular ring mixer;

[0072] (4) Homogeneous paving: The core layer mixed with wood shavings is paved by a core layer cage structure paving machine to obtain a core layer with a homogeneous structure.

[0073] Comparative Example 3:

[0074] The preparation method is the same as that of Comparative Example 2, except that a flexible ring mixer is used for mixing the adhesive.

[0075] Table 1: Performance comparison of particleboard prepared in different embodiments and comparative examples:

[0076]

[0077] Analysis of the data in Table 1 shows that:

[0078] (1) A comparison between Example 1 and Comparative Example 1 shows that:

[0079] Example 1 uses large and small core wood shavings, employing a method of applying adhesive before mixing. Compared to our previous solutions, this method involves large wood shavings being sheared into different sizes under the mechanical action of adhesive mixing. These different sized shavings, through the action of the adhesive, can form a high-strength particleboard product, all exhibiting improved static bending strength. However, after multiple experiments, it was found that Example 1 has certain defects. The principle is to increase the length of the wood shavings to change their shape. Although these large wood shavings can form different sizes under the mechanical action of adhesive mixing, the force that causes the wood shavings to break under mechanical action is random. This is affected by rotation speed, gravity, the arrangement of the broken shavings, and temperature, resulting in significant differences in the size and shape of the wood shavings formed by the mechanical shearing force. This manifests as performance fluctuations in different batches of high-strength particleboard products.

[0080] (2) A comparison of Example 1 with Comparative Examples 2 and 3 shows that:

[0081] The particleboard prepared in Example 1 has better performance than Comparative Example 2 and Comparative Example 3, while the particleboards of Comparative Example 2 and Comparative Example 3 have lower performance than Comparative Example 2.

[0082] The method of mixing large and small core wood chips before applying adhesive, even with different adhesive mixers such as the ordinary ring mixer in Example 2 and the flexible ring mixer in Example 3, cannot achieve the same or similar internal bond strength, static bending strength, and modulus of elasticity as the present invention; and may even be lower than the internal bond strength, static bending strength, and modulus of elasticity of the particleboard in Comparative Examples 2 and 3.

[0083] This is likely because the invention employs a method of applying glue first and then mixing, which greatly reduces the breakage of wood shavings. At the same time, the glue application process can fully utilize the flexibility, swelling capacity, and structural mechanical properties of wood shavings of different sizes. After applying glue separately, the wood shavings of different sizes can be thoroughly mixed using a drum mixer, resulting in a homogeneous core layer structure with uniformly mixed wood shavings of different sizes. This high-quality, high-strength particleboard has high strength, good physical and mechanical properties, high internal bond strength, static bending strength, elastic modulus, and screw holding force. It also improves the expansion rate of wood shavings after absorbing water and makes it less prone to edge chipping during secondary processing.

[0084] In summary, this invention uses two types of wood shavings of different sizes, shapes, and moisture contents to prepare the core layer after mixing with adhesive, forming a homogeneous wood shaving structure in the core layer. This is different from the prior art which uses only one type of wood shavings to prepare the core layer after mixing with adhesive, thus improving the static bending strength of the particleboard.

[0085] One advantage of this invention is that, based on the core layer mixing components of two types of core layer mixing machines, it adopts a form of mixing the adhesive first and then mixing the materials. The separate mixing of adhesives improves the expansion rate of the wood chips after absorbing water, thereby obtaining a homogeneous core layer wood chip structure with uniform mixing of large and small wood chips. The high-strength particleboard has high strength, good physical and mechanical properties, and high internal bond strength, static bending strength, elastic modulus and screw holding force.

Claims

1. A method for preparing a high-strength particleboard, wherein the high-strength particleboard comprises a lower surface layer, a core layer, and an upper surface layer, characterized in that... The method for preparing the high-strength particleboard includes: (1) Laying: Lay the lower surface layer, core layer and upper surface layer in sequence according to the preset method; The lower and upper surface layers are laid using a surface airflow paving machine or a surface diamond roller paving machine for gradual paving. The core layer is laid in a homogeneous manner, and the steps include: (1.1) Applying adhesive: Add adhesive and curing agent to the large and small core wood shavings respectively; (1.2) Mixing the adhesive: The small core layer wood shavings after adhesive application are mixed using a regular ring mixer; the large core layer wood shavings after adhesive application are mixed using a flexible ring mixer. (1.3) Mixing; The core layer large and small wood shavings after mixing are thoroughly mixed using a drum mixer to obtain core layer mixed wood shavings; (1.4) Homogeneous paving: The core layer mixed with wood shavings is paved by a core layer cage structure paving machine to obtain a core layer with a homogeneous structure; The core layer large wood shavings are 30-80mm long, 3-25mm wide, and 0.7-1.2mm thick, with a moisture content of 1.0-1.5%; the core layer small wood shavings are 10-30mm long, 1-3mm wide, and 0.7-1.2mm thick, with a moisture content of 1.0-1.5%. (2) Pre-compression: The slab strips of the laid lower surface layer, core layer and upper surface layer are pre-compressed to give the slab a certain initial strength; (3) Hot pressing: The pre-pressed slab strip is hot pressed at a temperature of 190~250℃. (4) Sanding and trimming: Sand off the pre-cured layer on the board surface and trim the rough edges of the product to obtain the finished board.

2. The method for preparing high-strength particleboard according to claim 1, characterized in that... The gradient paving steps for the lower and upper surface layers include: (1) Applying adhesive: Add adhesive to the surface wood shavings; (2) Mixing adhesive: The surface wood shavings after adhesive application are mixed with adhesive using a ring mixer to obtain surface wood shavings material; (3) Gradual paving: The surface shavings after mixing with adhesive are paved through a surface airflow paving machine or a surface diamond roller paving machine to obtain a lower or upper surface layer with a gradual structure.

3. The method for preparing high-strength particleboard according to claim 2, characterized in that... The surface wood shavings are 0.1-10mm long, 0.1-2mm wide, and 0.1-0.7mm thick, with a moisture content of 1.0-1.5%.

4. The method for preparing high-strength particleboard according to claim 2, characterized in that... The amount of adhesive applied to the surface wood shavings is 3-12%, and the adhesive is a urea-formaldehyde resin adhesive, a modified urea-formaldehyde resin adhesive, or an MDI isocyanate adhesive.

5. The method for preparing high-strength particleboard according to claim 1, characterized in that... The amount of adhesive applied to the large core wood shavings is 3-10%, and the amount of adhesive applied to the small core wood shavings is 3-10%; the adhesive is urea-formaldehyde resin adhesive, modified urea-formaldehyde resin adhesive, or MDI isocyanate adhesive.

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