Walnut shell powder glue-free artificial board, preparation method thereof, automotive trim and automobile

Abstract

The invention discloses a walnut shell powder glue-free artificial board and a preparation method thereof, an automotive trim and an automobile, and relates to the technical field of artificial boards. The preparation method of the walnut shell powder glue-free artificial board comprises the following steps that walnut shell powder is subjected to hot pressing treatment, and the walnut shell powder glue-free artificial board is prepared. According to the technical scheme, material selection and forming process optimization are carried out, natural and degradable walnut shell powder is used as a raw material, and under the condition that a resin material, an adhesive or a forming auxiliary agent is not added, the non-adhesive plate is obtained by using a biological base material. The preparation method has the advantages that the raw materials are green and environment-friendly, the possibility that toxic and harmful organic volatile matters such as aldehydes are generated in the subsequent use of the product is reduced, excellent VOCs friendliness is achieved, and the static bending intensity and the internal bonding strength of the prepared walnut shell powder glue-free artificial board meet the regulatory requirements of using a common board under the dry condition; the method can be used for solving the problem that resin materials, adhesives or forming auxiliaries are needed in the forming process of existing bio-based materials.

Description

Technical Field

[0001] The present invention relates to the technical field of artificial boards, and particularly relates to a glue-free artificial board made of walnut shell powder, a preparation method thereof, automotive interiors, and automobiles. Background Art

[0002] Plastics and artificial boards are widely used in automotive interior decorative materials. With the market's increasingly high requirements for vehicle interior environmental protection, various manufacturers have introduced materials such as spray-free plastics, bio-based composites, bioplastics, nanocomposites, and modified resins to control the emission of VOCs (volatile organic compounds) in the vehicle.

[0003] Using bio-based composites or bioplastics is considered one of the effective measures to control the emission of VOCs in the vehicle. Currently, there are mainly two ways to apply bio-based composites and bioplastics in vehicle interior parts: (1) based on pretreated plant leaf and stem fibers, and then combined with high polymers such as ABS (acrylonitrile-butadiene-styrene copolymer) and PP (polypropylene) to prepare composites; (2) prepared by adding adhesives to bio-based materials through a molding process. In the preparation process of these two methods, due to the use of resin materials, adhesives, or molding aids, small molecules generated by chain breakage and degradation, remaining plasticizers, flame retardants, and formaldehyde overflowing from adhesives may exist during the processing, and these will still increase the content of VOCs in the vehicle.

[0004] Therefore, controlling the generation and release of VOCs in automotive interior materials from the source and developing fully bio-based glue-free materials are the key research points for those skilled in the art. Summary of the Invention

[0005] The main object of the present invention is to propose a glue-free artificial board made of walnut shell powder, a preparation method thereof, automotive interiors, and automobiles, aiming to solve the problem that existing bio-based materials need to use resin materials, adhesives, or molding aids during the molding process.

[0006] To achieve the above object, the present invention proposes a preparation method for a glue-free artificial board made of walnut shell powder, comprising the following steps:

[0007] Perform hot pressing treatment on the walnut shell powder to obtain the glue-free artificial board made of walnut shell powder.

[0008] In one embodiment, the step of performing hot pressing treatment on the walnut shell powder to obtain the glue-free artificial board made of walnut shell powder comprises:

[0009] Mix the walnut shell powder with an alkaline solution for pretreatment to obtain a mixture;

[0010] Filter the mixture to obtain a filter residue, dry the filter residue to obtain a solid, and perform hot pressing on the solid to prepare the walnut shell powder non - adhesive artificial board.

[0011] In one embodiment, the paving density of the hot pressing is 1.25 - 1.65 g / cm 3 ; and / or,

[0012] the temperature of the hot pressing is 150 - 190 °C; and / or,

[0013] the time of the hot pressing is 120 - 180 s; and / or,

[0014] the pressure of the hot pressing is 3 - 5 MPa.

[0015] In one embodiment, the alkaline solution includes a sodium hydroxide solution with a mass concentration of 1% - 2%.

[0016] In one embodiment, the temperature of the pretreatment is 10 - 30 °C; and / or,

[0017] the time of the pretreatment is 60 - 70 s.

[0018] In one embodiment, the temperature of the drying treatment is 40 - 50 °C.

[0019] In one embodiment, after the step of performing hot pressing on the walnut shell powder to prepare the walnut shell powder non - adhesive artificial board, it further includes:

[0020] Coat a water - based polyester coating on the surface of the walnut shell powder non - adhesive artificial board to form a protective layer.

[0021] In one embodiment, the step of coating a water - based polyester coating on the surface of the walnut shell powder non - adhesive artificial board to form a protective layer includes:

[0022] Coat a water - based polyester coating on the surface of the walnut shell powder non - adhesive artificial board, and perform drying treatment to form a first protective layer;

[0023] Coat a water - based polyester coating on the surface of the first protective layer, and perform drying treatment to form a second protective layer.

[0024] The present invention provides a walnut shell powder non - adhesive artificial board, which is prepared according to the preparation method of the walnut shell powder non - adhesive artificial board described above.

[0025] The present invention provides an automobile interior trim, which includes the walnut shell powder non - adhesive artificial board described above.

[0026] The present invention provides an automobile, which includes the automobile interior trim described above.

[0027] Through the optimization of material selection and forming process, the technical solution of the present invention uses walnut shell powder as raw material to prepare a glue-free artificial board. During the forming process, the sticky polycondensed furan resin, lignin with a relatively large molecular weight, and the increased cellulose crystallinity generated by the material itself are used for bonding and forming, realizing the production of a glue-free board using a biological base material without adding adhesives or forming aids. The preparation method provided by the present invention uses natural and degradable green environmental protection materials as raw materials, reducing the possibility of generating toxic and harmful organic volatiles such as aldehydes during the subsequent use of the product, realizing the production of formaldehyde-free artificial boards, having excellent VOCs friendliness and environmental friendliness. Moreover, the static bending strength and internal bonding strength of the prepared walnut shell powder glue-free artificial board meet the regulatory requirements for ordinary boards used under dry conditions. In addition, compared with the preparation methods of conventional bio-based artificial boards, the preparation method of the present invention has no complex pretreatment process, has the advantage of simple process, is conducive to cost savings and large-scale application, and has a high utilization rate of walnut shell powder, contributing to the high-value utilization of walnut shell powder. Specific Embodiments

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0029] It should be noted that if there are directional indications (such as up, down, left, right, front, back,...) involved in the embodiments of the present invention, the directional indications are only used to explain the relative position relationship and movement conditions between components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0030] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, if "and / or" or "and / or" appears throughout the text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or the solution where A and B are satisfied simultaneously. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions conflicts or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0031] Lignocellulosic biomass is the most abundant renewable resource on Earth. In the urgent situation of global resource shortage and energy crisis, biomass resources have attracted more and more attention due to their regenerativeness and environmental friendliness. How to convert the three major components of lignocellulose, namely cellulose, hemicellulose, and lignin, into high-value-added products has drawn people's attention in recent years. Walnut shell powder contains components such as low-molecular-weight sugars, cellulose, and lignin, and as a natural resource, it shows broad application prospects in multiple industrial fields.

[0032] Using bio-based composites or bioplastics is considered one of the useful measures to control the volatile amount of VOCs in vehicles. Currently, there are mainly two ways to apply bio-based composites and bioplastics in vehicle interior parts: (1) Based on pre-treated plant leaf and stem fibers, and then combined with high polymers such as ABS (acrylonitrile-butadiene-styrene copolymer) and PP (polypropylene) to prepare composites; (2) Prepared by adding adhesives to bio-based materials through a molding process. In these two ways, due to the use of resin materials, adhesives, or molding aids during the preparation process, there may be small molecules generated by chain breakage and degradation, remaining plasticizers, flame retardants, and formaldehyde overflowing from adhesives during the processing, which will still increase the content of VOCs in the vehicle. Therefore, controlling the generation and release of VOCs from automotive interior materials at the source and developing fully bio-based non-adhesive materials are the key research points for those skilled in the art.

[0033] In view of this, the present invention proposes a method for preparing a walnut shell powder non-adhesive artificial board, which includes the following steps:

[0034] Perform hot pressing treatment on the walnut shell powder to obtain the walnut shell powder non-adhesive artificial board.

[0035] The walnut shell powder contains components such as hemicellulose, cellulose, and lignin, which is a better choice to replace traditional adhesives. Among them, the hydrolysis product furfural of hemicellulose will further undergo a polycondensation reaction during the hot pressing process to form a viscous polycondensed furan resin, and the polycondensed furan resin plays a role similar to an adhesive to provide support for the bonding of powders; lignin can undergo a dehydration condensation reaction with active groups and lignin itself to play a role similar to an adhesive. In addition, lignin with a larger molecular weight has a longer molecular chain and more potential cross-linking points, which helps to enhance the cohesion and durability of the material; high temperature and high pressure will lead to an increase in the crystallinity of cellulose and the melting of some amorphous regions, which is beneficial to improving the mechanical properties of the board.

[0036] Through the optimization of material selection and forming process, the technical solution of the present invention uses natural walnut shell powder as raw material to press a non - adhesive artificial board. During the pretreatment and forming process, no adhesives or forming aids are required. It is only through the sticky polycondensed furan resin generated by the material itself during the forming process, lignin with a relatively large molecular weight, and the improvement of cellulose crystallinity for cementing and forming. Without adding adhesives or forming aids, a non - adhesive board is obtained using biological substrates. The raw materials are green and environmentally friendly, reducing the possibility of generating toxic and harmful organic volatiles such as aldehydes during the subsequent use of the product, realizing the production of formaldehyde - free artificial boards, with excellent VOCs - friendliness and environmental friendliness. Moreover, the static bending strength and internal bonding strength of the prepared walnut shell powder non - adhesive artificial board meet the regulatory requirements for ordinary boards used under dry conditions.

[0037] In addition, in actual production applications, common biomass raw materials for preparing bio - based artificial boards include fiber - rich materials such as straw and bamboo. Walnut shell powder is usually used as a biomass - based filler to enhance the strength of the board, and the usage amount is relatively small. When using fiber - rich materials such as straw and bamboo to prepare bio - based artificial boards, the process is relatively cumbersome. Usually, a pretreatment process is required before use, and a long - time alkaline solution soaking treatment is needed. The technical solution of the present invention does not require steps such as baking the biomass raw materials, and does not require a complex pretreatment process and can be directly used. Therefore, compared with the conventional preparation methods of bio - based artificial boards, the preparation method provided by the present invention has the advantages of fewer processing links and simple process, which is conducive to cost savings and large - batch applications. Moreover, the utilization rate of walnut shell powder is high, which helps to utilize walnut shell powder with high added value.

[0038] It should be noted that the technical solution of the present invention does not limit the source of the walnut shell powder. It can be purchased from ordinary industrialized merchants, or the walnut shells can be ball - milled or ultra - micro - pulverized. In some embodiments of the present invention, the walnut shell powder is purchased from Lingshou Detong Mineral Products Processing Company. Before pressing the walnut shell powder into a board, the walnut shell powder can also be sieved through a 200 - mesh sieve and then used. Sieving can effectively remove larger particles, foreign substances, etc. in the walnut shell powder, making the walnut shell powder reach a suitable particle size range. Uniform particle size helps to improve the consistency and stability of the prepared non - adhesive board.

[0039] In the embodiments of the present invention, the steps of hot - pressing the walnut shell powder to obtain the walnut shell powder non - adhesive artificial board include:

[0040] Mix the walnut shell powder and an alkaline solution for pretreatment to obtain a mixture;

[0041] Filter the mixture to obtain a filter residue, dry the filter residue to obtain a solid, and perform hot - pressing on the solid to obtain the walnut shell powder non - adhesive artificial board.

[0042] To improve the comprehensive properties of the walnut shell powder-based binderless wood-based panel, the technical solution of the present invention pre-treats the walnut shell powder with an alkaline solution before hot pressing. Through the pre-treatment with the alkaline solution, more hemicellulose undergoes hydrolysis, and furfural in the hydrolysis products of hemicellulose undergoes a polycondensation reaction during hot pressing to generate a viscous furan resin, providing support for the binding of powder particles; in addition, the hydrolysis of hemicellulose is beneficial to improving the crystallinity of cellulose, thereby enhancing the mechanical properties of the board. The pre-treatment with the alkaline solution also helps the powder material to generate more lignin with large molecular weights during hot pressing. On the other hand, in terms of the micro-structure of the board, the product pre-treated with the alkaline solution is denser, flatter, and has fewer voids, so its mechanical properties are better.

[0043] In the embodiments of the present invention, the mat density of the hot pressing treatment is 1.25 - 1.65 g / cm 3 . The mat density is closely related to the properties of the binderless wood-based panel such as water resistance, strength, and machining performance. If the mat density is too high or too low, it may lead to inconsistent properties of each part of the board, affecting its strength, hardness, and flatness. Generally, the greater the density of the board, the higher the strength, the more difficult the processing, and the higher the cost; conversely, the lower the density of the board, the lower the cost, but the worse the strength. Setting the mat density of the hot pressing treatment at 1.25 - 1.65 g / cm 3 is beneficial to obtaining a walnut shell powder-based binderless wood-based panel with good mechanical properties and water resistance. Within this range, the mat density can be 1.25 g / cm 3 , 1.45 g / cm 3 and 1.65 g / cm 3 . Preferably, the mat density is 1.45 g / cm 3 .

[0044] In the embodiments of the present invention, the temperature of the hot pressing treatment is 150 - 190 °C. If the hot pressing treatment temperature is too high, the substances in the binderless board will undergo excessive degradation, thus affecting the mechanical properties of the binderless board. And as the hot pressing temperature increases, more water vapor and volatile small molecules will be generated during hot pressing, and it is easy to move outwards along with the water vapor and these volatile small molecules when opening the mold, resulting in the uniformity and denseness of the binderless board being affected, thereby reducing the water resistance of the binderless board. Considering the comprehensive properties of the binderless board, the temperature of the hot pressing treatment is set at 150 - 190 °C. Within this range, the temperature of the hot pressing treatment can be 150 °C, 160 °C, 170 °C, 180 °C, 190 °C. Preferably, the temperature of the hot pressing treatment is 170 °C.

[0045] In an embodiment of the present invention, the time of the hot pressing treatment is 120 - 180 s. If the hot pressing treatment time is too long, various substances in the slab will be excessively degraded, and the already formed adhesive substances will show coking and brittle fracture phenomena, resulting in a reduction in the better mechanical properties that the glue - free board has obtained in the early stage of hot pressing. The technical solution of this application sets the hot pressing treatment time to 120 - 180 s, which can make the "self - adhesion" reaction in the walnut shell powder more sufficient. At the same time, the lignin contained in the walnut shell itself increases with the extension of time and is more evenly distributed in the glue - free board, which is beneficial to improving the mechanical properties of the prepared glue - free board. Within this range, the time of the hot pressing treatment can be 120 s, 130 s, 140 s, 150 s, 160 s, 170 s, 180 s. Preferably, the time of the hot pressing treatment is 150 s.

[0046] In an embodiment of the present invention, the pressure of the hot pressing treatment is 3 - 5 MPa. The static bending strength, internal bonding strength, and water absorption thickness swelling rate of the glue - free board show an increasing trend with the increase of the hot pressing treatment pressure. And with the increase of the hot pressing treatment pressure, the water resistance of the glue - free board will be significantly weakened. Considering the comprehensive performance of the glue - free board, the pressure of the hot pressing treatment is set to 3 - 5 MPa. Within this range, the pressure of the hot pressing treatment can be 3 MPa, 4 MPa, 5 MPa. Preferably, the pressure of the hot pressing treatment is 3 MPa.

[0047] In an embodiment of the present invention, the alkaline solution includes a sodium hydroxide solution with a mass concentration of 1% - 2%.

[0048] The technical solution of the present invention uses a low - concentration sodium hydroxide solution to pretreat the walnut shell powder. If the amount of the alkaline solution is insufficient, the hemicellulose hydrolysis is not sufficient, and it cannot provide sufficient small - molecule raw material furfural for forming. If the amount of the alkaline solution is too much, it may damage the original crystal structure of the walnut shell powder and affect the mechanical properties of the material. In one embodiment, the mass concentration of the sodium hydroxide solution is 1%. In the specific pretreatment process, the amount of the alkaline solution can be such that the powder material is fully immersed in the solution.

[0049] In an embodiment of the present invention, the temperature of the pretreatment is 10 - 30 °C. The technical solution of the present invention soaks the walnut shell powder in the alkaline solution at room temperature. The treatment conditions are relatively mild and easy to control.

[0050] In an embodiment of the present invention, the time of the pretreatment is 60 - 70 s. If the pretreatment time is too long, it may damage the original crystal structure of the walnut shell powder and affect the mechanical properties of the material.

[0051] In an embodiment of the present invention, the temperature of the drying treatment is 40 - 50 °C. The moisture is removed through the drying treatment, which is convenient for the subsequent hot pressing treatment.

[0052] In an embodiment of the present invention, after the step of subjecting the walnut shell powder to hot pressing to obtain the walnut shell powder glue-free artificial board, the following steps are further included:

[0053] Coat the surface of the walnut shell powder glue-free artificial board with a waterborne polyester coating to form a protective layer.

[0054] Waterborne coatings have the advantages of low VOCs and environmental protection. Waterborne polyester coatings can form a strong adhesion with a variety of substrates (including metals, wood, concrete, plastics, etc.), and the waterborne polyester coatings have excellent weather resistance and water repellency. To ensure the long-term stability and reliability of the coating, in some embodiments of the present invention, a waterborne polyester coating is selected to prepare the protective layer, which can form a protective film on the obtained walnut shell powder artificial board to block moisture, pollutants and other harmful substances in the air from directly contacting the board, thereby extending the service life of the board. After being treated with the waterborne polyester coating, the water resistance of the board can be improved, which helps the 2h water absorption thickness swelling rate of the obtained board to meet the use requirements.

[0055] In an embodiment of the present invention, the step of coating the surface of the walnut shell powder glue-free artificial board with a waterborne polyester coating to form a protective layer includes:

[0056] Coat the surface of the walnut shell powder glue-free artificial board with a waterborne polyester coating using a brush, and leave it standing at room temperature for 1h and then put it into a drying oven at 70°C for drying for 10min.

[0057] It should be noted that a multi-layer protective layer can be formed through multiple coating and drying treatments. When the surface coating of the walnut shell powder glue-free artificial board is two layers, the step of coating the surface of the walnut shell powder glue-free artificial board with a waterborne polyester coating to form a protective layer includes:

[0058] A1. Coat the surface of the walnut shell powder glue-free artificial board with a waterborne polyester coating, leave it standing at room temperature for 1h and then put it into a drying oven at 70°C for drying for 10min to form the first layer of coating;

[0059] A2. Uniformly coat a waterborne polyester coating on the surface of the first layer of coating, leave it standing at room temperature for 1h and then put it into a drying oven at 70°C for drying for 10min to form the second layer of coating.

[0060] Similarly, when the surface coating of the walnut shell powder glue-free artificial board is three layers, the step of coating the surface of the walnut shell powder glue-free artificial board with a waterborne polyester coating to form a protective layer includes:

[0061] B1. Coat the surface of the walnut shell powder glue-free artificial board with a waterborne polyester coating, leave it standing at room temperature for 1h and then put it into a drying oven at 70°C for drying for 10min to form the first layer of coating;

[0062] B2. Uniformly coat the waterborne polyester coating on the surface of the first-layer coating, let it stand at room temperature for 1 h, and then put it into a drying oven at 70 °C for drying for 10 min to form the second-layer coating;

[0063] B3. Uniformly coat the waterborne polyester coating on the surface of the second-layer coating, let it stand at room temperature for 1 h, and then put it into a drying oven at 70 °C for drying for 10 min to form the third-layer coating.

[0064] To screen out the waterborne polyester coatings with better improvement effects on the water resistance of the prepared boards, the inventors coated a protective layer on the prepared boards with various models of waterborne polyester coatings, and tested the 2h water absorption thickness swelling rate and contact angle of the prepared glue-free boards. The test results showed that the contact angle was larger, and the corresponding 2h water absorption thickness swelling rate test results of the waterborne polyester coatings were also better. This may be because the waterborne polyester coatings with larger contact angles contain more hydrophobic groups, and the surface of the formed coating has better hydrophobicity, so the 2h water absorption thickness swelling rate test results are smaller. In some embodiments of the present invention, the waterborne polyester coating is purchased from Covestro Polymer (China) Co., Ltd., and the model is UV XP 2775. By selecting this model of waterborne polyester coating, the prepared glue-free board has better water resistance.

[0065] Furthermore, to confirm the appropriate number of layers of the anti-coating, the inventors compared the 2h water absorption thickness swelling rate and surface morphology when the number of protective layers was set to one layer, two layers, and three layers, and observed the surface micro-morphology of the glue-free board without a protective layer and with different numbers of protective layers after testing by using a scanning electron microscope. The inventors found that compared with the glue-free board without a protective layer, although there were obvious traces of plasticization on the surface of the walnut shell powder glue-free artificial board without a protective layer, there were still pores and lamellae. The pores and lamellae may provide channels for water infiltration, while the surface of the glue-free board treated with a protective layer was dense, smooth, flat and without pores. And the inventors found that the effect was the best when the number of protective layers was set to two layers, which could make the 2h water absorption thickness swelling rate of the prepared walnut shell powder glue-free artificial board meet the requirement of ≤8.0% for ordinary boards in GB / T4897.2-2003. The reason for this phenomenon may be that the selected waterborne polyester coating is a liquid with a certain viscosity. When only one layer is coated, it is difficult to completely cover the surface of the glue-free board due to uneven flow and spreading, so the effect of preventing water from entering is poor; while there are fine cracks on the surface of the glue-free board coated with three layers, which may be because the coating is thicker, the surface of the coating dries faster than the inside, the dried surface shrinks and tensions, and the undried inside breaks the tensioned surface, resulting in small cracks, providing channels for water to enter, and leading to an increase in the 2h water absorption thickness swelling rate test results. Therefore, in some embodiments of the present invention, to obtain better water resistance, the number of the protective layers is set to two layers.

[0066] The present invention provides a glue - free wood - based panel made of walnut shell powder, and the glue - free wood - based panel made of walnut shell powder is prepared according to the preparation method of the glue - free wood - based panel made of walnut shell powder.

[0067] The present invention provides an automobile interior trim, and the automobile interior trim includes the above - mentioned glue - free wood - based panel made of walnut shell powder. The automobile interior trim includes all the technical solutions of the glue - free wood - based panel made of walnut shell powder, and thus has all the beneficial effects of the glue - free wood - based panel made of walnut shell powder. The beneficial effects of the present invention will not be elaborated one by one here.

[0068] The present invention provides an automobile, and the automobile includes the above - mentioned automobile interior trim. The automobile includes all the technical solutions of the automobile interior trim, and thus has all the beneficial effects of the automobile interior trim. The beneficial effects of the present invention will not be elaborated one by one here.

[0069] The technical solutions of the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.

[0070] Example 1

[0071] A preparation method of a glue - free wood - based panel made of walnut shell powder includes the following steps:

[0072] The walnut shell powder is paved in a 25 cm×25 cm mold at a paving density of 1.45 g / cm 3 for hot - pressing treatment. The hot - pressing temperature is 170 °C, the hot - pressing time is 150 s, and the hot - pressing intensity is 3 MPa as process parameters. A wood - based panel is pressed to obtain a glue - free wood - based panel made of walnut shell powder.

[0073] Example 2

[0074] A preparation method of a glue - free wood - based panel made of walnut shell powder includes the following steps:

[0075] (1) The walnut shell powder is completely immersed in a NaOH solution with a mass concentration of 1%, and left standing at room temperature for 1 min for pretreatment to obtain a mixture.

[0076] (2) The above - mentioned mixture is filtered to remove the solution, dried at 45 °C for 48 h to obtain a solid, and the solid is subjected to hot - pressing treatment. It is paved in a 25 cm×25 cm mold at a paving density of 1.45 g / cm 3 . The hot - pressing temperature is 170 °C, the hot - pressing time is 150 s, and the hot - pressing intensity is 3 MPa as process parameters. A wood - based panel is pressed to obtain a glue - free wood - based panel made of walnut shell powder.

[0077] Example 3

[0078] Compared with Example 2, the difference is that the paving density is 1.25 g / cm 3 .

[0079] Example 4

[0080] Compared with Example 2, the difference is that the paving density is 1.65 g / cm 3 .

[0081] Example 5

[0082] Compared with Example 2, the difference is that the hot pressing temperature is 150 °C and the hot pressing time is 120 s.

[0083] Example 6

[0084] Compared with Example 2, the difference is that the hot pressing time is 150 s and the hot pressing strength is 5 MPa.

[0085] Example 7

[0086] Compared with Example 2, the difference is that the hot pressing temperature is 190 °C, the hot pressing time is 180 s, and the hot pressing strength is 4 MPa.

[0087] Example 8

[0088] A method for preparing a walnut shell powder non - adhesive artificial board, comprising the following steps:

[0089] (1) Immerse the walnut shell powder completely in a NaOH solution with a mass concentration of 1%, and let it stand at room temperature for 1 min for pretreatment to obtain a mixture.

[0090] (2) Filter the solution from the above - mentioned mixture, dry it at 45 °C for 48 h to obtain a solid. Perform hot pressing on the solid, using a paving density of 1.45 g / cm 3 Pave it in a 25 cm × 25 cm mold, with a hot pressing temperature of 170 °C, a hot pressing time of 150 s, and a hot pressing strength of 3 MPa as process parameters, and press it into a board to obtain a walnut shell powder non - adhesive artificial board;

[0091] (3) Coat the surface of the walnut shell powder non - adhesive artificial board obtained in step (2) with a water - borne polyester coating using a brush. Let it stand at room temperature for 1 h and then put it into a drying oven at 70 °C for 10 min to form a first - layer coating; uniformly coat the water - borne polyester coating on the surface of the first - layer coating, let it stand at room temperature for 1 h and then put it into a drying oven at 70 °C for 10 min to form a second - layer coating.

[0092] Example 9

[0093] Compared with Example 8, the difference is that the number of layers of the protective layer in step (3) is 1 layer, and the specific operation steps of step (3) are:

[0094] Apply waterborne polyester coating on the surface of the walnut shell powder glue-free artificial board obtained in step (2) with a brush, let it stand at room temperature for 1 h, and then put it into a drying oven at 70 °C for drying for 10 min to form a coating layer.

[0095] Example 10

[0096] Compared with Example 2, the difference lies in that the number of layers of the protective layer in step (3) is 3 layers, and the specific operation steps of step (3) are as follows:

[0097] Apply waterborne polyester coating on the surface of the walnut shell powder glue-free artificial board obtained in step (2) with a brush, let it stand at room temperature for 1 h, and then put it into a drying oven at 70 °C for drying for 10 min to form the first coating layer; evenly apply waterborne polyester coating on the surface of the first coating layer, let it stand at room temperature for 1 h, and then put it into a drying oven at 70 °C for drying for 10 min to form the second coating layer; evenly apply waterborne polyester coating on the surface of the second coating layer, let it stand at room temperature for 1 h, and then put it into a drying oven at 70 °C for drying for 10 min to form the third coating layer.

[0098] Performance test

[0099] Test the modulus of rupture (MOR), internal bond strength (IB) and 2-h thickness swelling rate after water absorption (2-h TS) of the walnut shell powder glue-free artificial boards of Examples 1-10 in accordance with GB / T - 4897.2 - 2003. When testing, the size of the walnut shell powder glue-free artificial board is 250 mm × 250 mm, and the thickness is 4 mm. The test results are shown in Table 1.

[0100] Table 1 Performance test results of the walnut shell powder glue-free artificial boards of Examples 1-10

[0101]

[0102]

[0103] In Table 1, " / " indicates that this item was not carried out.

[0104] As can be seen from Table 1, the test results of the modulus of rupture of the walnut shell powder glue-free artificial boards of Examples 1-10 are all greater than 14 MPa, and the test results of the internal bond strength are all greater than 0.31 MPa, which all meet the requirements of GB / T4897.2 - 2003 for ordinary boards used in the dry state (for hot press boards with a thickness of 3 - 6 mm, the requirements for the modulus of rupture ≥ 14 MPa and the internal bond strength ≥ 0.31 MPa). From the test data of Examples 2-4, it can be seen that with the increase of the paving density, the 2-h thickness swelling rate after water absorption first increases and then decreases, and the effect is the best when the paving density is 1.45 g / cm 3 at this time.

[0105] It can also be seen from Table 1 that the test results of the modulus of rupture, internal bond strength, and 2h thickness swelling rate after water absorption of Example 2 are all better than those of Example 1, indicating that treatment with 1% NaOH solution can improve the comprehensive performance of the walnut shell powder-based non-glued wood-based panel.

[0106] It can also be seen from Table 1 that there is little difference in the test results of the modulus of rupture and internal bond strength between Example 8 and Example 2. However, the test result of the 2h thickness swelling rate after water absorption of Example 8 is better than that of Example 2 and meets the requirement of ≤8.0% for general-purpose boards in GB / T4897.2-2003, indicating that treatment of the walnut shell powder-based non-glued wood-based panel with waterborne polyester coating can improve the 2h thickness swelling rate after water absorption. Moreover, from the test results of Examples 8-10, it can be known that the test result of the 2h thickness swelling rate after water absorption corresponding to 2 layers of the protective layer of the walnut shell powder-based non-glued wood-based panel is the best.

[0107] In summary, through the pretreatment with an alkaline solution and the coating of a protective layer on the surface of the walnut shell powder-based non-glued wood-based panel, the indexes such as the modulus of rupture, internal bond strength, and 2h thickness swelling rate after water absorption of the prepared walnut shell powder-based non-glued wood-based panel can meet the requirements for general-purpose boards used in the dry state in GB / T4897.2-2003. The prepared walnut shell powder-based non-glued wood-based panel can be considered as the core material for automotive interiors, furniture panels, shells, etc.

[0108] The above description is only an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformation made using the content of the specification of the present invention under the technical concept of the present invention, or any direct / indirect application in other related technical fields is included in the patent protection scope of the present invention.

Claims

1. A method for preparing a walnut shell powder glue-free artificial board, characterized in that: The following steps are involved: The walnut shell powder is subjected to hot pressing treatment to obtain the walnut shell powder glue-free artificial board.

2. The method for preparing the walnut shell powder glue-free artificial board according to claim 1, characterized in that: The step of subjecting the walnut shell powder to hot pressing to obtain the walnut shell powder glue-free artificial board comprises: The walnut shell powder and the alkaline solution are mixed and pre-treated to obtain a mixture; The mixture is filtered to obtain filter residue, the filter residue is dried to obtain solid matter, and the solid matter is hot-pressed to obtain the walnut shell powder glue-free artificial board.

3. The method for preparing the walnut shell powder glue-free artificial board according to claim 1 or 2, characterized in that: The paving density of the hot pressing treatment is 1.25-1.65 g / cm 3 and / or, The temperature of the hot pressing treatment is 150-190° C.; and / or, The heat pressing treatment time is 120 to 180 seconds; and / or, The pressure of the hot pressing treatment is 3-5 MPa.

4. The method for preparing the walnut shell powder glue-free artificial board according to claim 2, characterized in that: The alkaline solution comprises a sodium hydroxide solution with a mass concentration of 1% to 2%.

5. The method for preparing the walnut shell powder glue-free artificial board according to claim 2, characterized in that: The pretreatment temperature is 10-30°C; and / or, The pretreatment time is 60 to 70 seconds; and / or, The temperature of the drying process is 40-50°C.

6. The method for preparing the walnut shell powder glue-free artificial board according to claim 2, characterized in that: After the step of subjecting the walnut shell powder to hot pressing to obtain the walnut shell powder glue-free artificial board, the following steps are further included: A water-based polyester coating is coated on the surface of the walnut shell powder glue-free artificial board to form a protective layer.

7. The method for preparing the walnut shell powder glue-free artificial board according to claim 6, characterized in that: The step of coating the surface of the walnut shell powder glue-free artificial board with water-based polyester coating to form a protective layer comprises: Coating a water-based polyester coating on the surface of the walnut shell powder glue-free artificial board, and drying it to form a first protective layer; A water-based polyester coating is coated on the surface of the first protective layer, and dried to form a second protective layer.

8. A walnut shell powder glue-free artificial board, characterized in that: The walnut shell powder glue-free artificial board is prepared according to the preparation method of the walnut shell powder glue-free artificial board according to any one of claims 1 to 7.

9. An automobile interior, characterized in that: The automobile interior comprises the walnut shell powder glue-free artificial board according to claim 8.

10. An automobile, characterized in that: The automobile comprises the automobile interior according to claim 9.

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