Method for preparing building material plate by combining agriculture and forestry solid waste fibers with inorganic adhesive material

Abstract

The invention relates to the technical field of recycling of agriculture and forestry solid waste resources, and particularly discloses a preparation method for preparing a building material plate by combining agriculture and forestry solid waste fibers with an inorganic adhesive material. Comprising the following steps: 1, drying the surfaces of agriculture and forestry solid waste fibers; 2, a coupling agent is sprayed on the surfaces of the agriculture and forestry solid waste fibers, and the surfaces of the agriculture and forestry solid waste fibers are dried again; 3, weighing the gluing powder A, and uniformly mixing the gluing powder A with the agriculture and forestry solid waste fibers in the step 2; step 4, spraying a gluing reaction solution B on the material mixed in the step 3; 5, the materials treated in the step 4 are guided into a mold to be subjected to compression molding, and a building slab is obtained; and 6, standing, maintaining and forming under the conditions of constant temperature and constant humidity to obtain the building material plate. The technical problems that in the prior art, admixture distribution of artificial building materials produced from agriculture and forestry solid waste fibers is not uniform, straw and adhesive materials are not tightly combined, and the strength of produced building boards is not ideal enough are solved.

Description

Technical Field

[0001] The present application relates to the technical field of recycling and utilizing agricultural and forestry solid waste resources, and specifically discloses a method for preparing building material boards by combining agricultural and forestry solid waste fibers with inorganic adhesives. Background Art

[0002] Agricultural and forestry solid waste fibers refer to fibrous materials such as straw fibers and sawdust fibers obtained through processing waste generated during agricultural and forestry production. my country is a major agricultural country, with abundant agricultural and forestry crop straw resources and a huge output, but the utilization rate has remained low. At the same time, my country also has a booming market for building materials, with significant demand for decorative panels, lightweight panels for prefabricated buildings, and exterior wall panels. However, the raw materials used are relatively expensive. Incorporating agricultural and forestry solid waste fibers into building material production would not only address the high cost of building panel raw materials, but also promote the recycling of agricultural and forestry solid waste, achieving two goals at once.

[0003] At present, in the process of producing artificial building materials from agricultural and forestry solid waste fibers in the industry, adhesives are directly mixed with agricultural and forestry solid waste fibers, and then hot-pressed to obtain artificial building materials. For example, the patent document with application number: CN202210368440.7 discloses a straw composite board and its production method, which first soaks straw powder and magnesium sulfate solution, and then directly blends with raw materials such as magnesium oxide and auxiliary gelling agent. After mixing evenly, pre-pressing and hot-pressing are performed to obtain straw composite boards. Another example is a magnesium oxysulfate cement-based straw lightweight composite material and its preparation method disclosed in the patent document with application number: CN201811556541.7, which also first uses magnesium sulfate heptahydrate and a composite modifier to prepare solution A, pours solution A into light-burned magnesium powder and mixes evenly; directly adds straw fibers to make a mixture, and pours it into a mold to form.

[0004] Although the above two processes can complete the production of artificial building materials prepared from agricultural and forestry solid waste fibers, this simple mixing of adhesives and agricultural and forestry fibers directly often causes problems such as uneven distribution of agricultural and forestry fibers and insufficient bonding between straw and adhesives. This ultimately leads to the technical problem that the strength of the produced building materials or building panels is often not ideal. Summary of the Invention

[0005] The purpose of the present invention is to provide a treatment method for reducing the moisture content of sludge, so as to solve the technical problem that in the process of producing artificial building materials from agricultural and forestry solid waste fibers in the existing technology mentioned above, the adhesive is simply mixed with the agricultural and forestry fibers, the admixture often has uneven distribution of agricultural and forestry fibers, and the straw and the adhesive are not tightly combined, resulting in the produced building board having less than ideal strength.

[0006] In order to solve the above problems, the technical solution adopted by the present invention is as follows: a treatment method for reducing the moisture content of sludge, comprising the following steps: Step 1: Drying the surface of agricultural and forestry solid waste fibers to remove surface moisture from the fibers; Step 2: Spray the coupling agent solution on the surface of the agricultural and forestry solid waste fibers, controlling the moisture content after spraying to 10%-15%, and drying the surface of the agricultural and forestry solid waste fibers again after spraying; Step 3: Weigh the adhesive powder A and mix it evenly with the agricultural and forestry solid waste fibers whose surfaces have been dried again in step 2, ensuring that the adhesive powder A adheres to the surfaces of the fibers to obtain a mixture; Step 4: Spray the mixed material in step 3 with the bonding reaction liquid B, and control the moisture content of the material after spraying to be 5-6%; Step 5: Apply release oil to the mold, introduce the material processed in step 4 into the mold for compression molding to obtain a building slab; Step 6: After demoulding the building slab, the building slab is placed under constant temperature and humidity conditions for curing to obtain a building material board; The bonding powder A and the bonding reaction liquid B come into contact with each other to generate a gelling reaction to produce a gelled adhesive.

[0007] The beneficial effects of this embodiment are:

[0008] 1、The prior art mixes glue material with agricultural and forestry fibers directly in the process of producing artificial building materials from agricultural and forestry solid waste fibers, but the mixed material after simple mixing often has uneven distribution of agricultural and forestry fibers, and the straw and glue material are not combined closely enough, resulting in that the strength of the produced building board is not ideal; and the present application first optimizes the treatment of the agricultural and forestry solid waste fibers with a coupling agent before gluing the fibers and the glue material, and the coupling agent is added in the form of a solution, which can make the coupling agent evenly distributed on the surface of the agricultural and forestry solid waste fibers; and since the agricultural and forestry solid waste fibers are dried in advance, the surface of the dried fibers is easy to absorb water, which makes the coupling agent in the form of a solution well absorbed and attached to the surface of the agricultural and forestry solid waste fibers, and after drying again, the water gradually evaporates, and the distance between the fibers and the coupling agent is reduced. When the distance is less than 0.28 nm (the range of hydrogen bond action), the hydroxyl groups (-OH) on the surface of the adjacent fibers and the silanol groups in the coupling agent molecules enter the range of action, and the silanol groups in the coupling agent molecules can form hydrogen bonds or covalent bonds with the hydroxyl groups on the surface of the agricultural and forestry solid waste fibers. Therefore, the way of drying first, spraying the coupling agent solution, and drying again makes the coupling agent and the agricultural and forestry solid waste fibers combine more closely. Therefore, when the powder is added later, the glue powder A can be firmly attached to the surface of the agricultural and forestry solid waste fibers due to the action of the coupling agent formed by the hydrogen bonds. And after the agricultural and forestry solid waste fibers are dried again, the powder is not disturbed by water during mixing, and the glue powder A is evenly dispersed on the agricultural and forestry solid waste fibers. When the mixed material is in contact with the glue reaction liquid B to occur gelation reaction, the mixed material is evenly distributed on the agricultural and forestry fibers, and the straw and glue material are combined closely. Therefore, the strength of the building material prepared by the present application is more ideal.

[0009] Further, the glue powder A in step 3 is light-burned magnesium oxide powder, and the glue reaction liquid B in step 4 is a magnesium chloride solution with a Baume degree of 26 or a magnesium sulfate solution with a Baume degree of 24 Further, the coupling agent in step 2 is a silane coupling agent, and the mass concentration of the coupling agent solution is 5%, and the water content after spraying on the surface of the agricultural and forestry solid waste fibers is controlled to be 10%.

[0010] Further, the glue reaction liquid B is sprayed on the mixed material in step 4, and the water content after spraying is controlled to be 5%.

[0011] Further, the silane coupling agent is gamma-aminopropyl triethoxysilane.

[0012] Further, the glue powder A is cement, and the glue reaction liquid is water.

[0013] Further, the cement is sulphoaluminate cement.

[0014] Furthermore, when applying pressure for pressing in step 5, when the applied pressure is 0-0.5 MPa, adhesive grouting is also required. The grouting adhesive slurry will flow inside the test piece and fill the gaps inside the building slab.

[0015] Furthermore, the curing process in step 6 is to continuously apply pressure, demould after 1 day, and then stand for 3 days at a temperature of 20±5°C and a humidity of 65±5%. After curing and forming, the finished building material is obtained.

[0016] Furthermore, the curing process in step 6 is to continuously apply pressure and high temperature, the high temperature being 40-60°C; demolding after 2h-4h, and then standing for 1d at a temperature of 20±5°C and a humidity of 65±5%. After curing and forming, the finished building material is obtained.

[0017] Description of the accompanying drawings.

[0018] Figure 1 It is a process flow chart of the present invention.

[0019] Specific implementation method.

[0020] The following is further explained in detail through specific implementation methods:

[0021] Implementation example Figure 1 shown.

[0022] Method Overview: Step 1: Drying the surface of agricultural and forestry solid waste fibers to remove surface moisture from the fibers; Surface dryness is assessed using sensory methods, specifically: Visual inspection: Surface-dry plant fibers typically become lighter in color (e.g., from dark brown to light yellow), become dull, or develop tiny cracks. Dry surfaces should be free of moisture and gloss. Tactile testing: The inspector gently touches the fiber surface with their finger. If the surface is dry and non-sticky, and the fibers are non-sticky and brittle, the surface is dry.

[0023] Step 2: Spray a 5% coupling agent solution on the surface of the agricultural and forestry solid waste fibers, controlling the moisture content after spraying to 10%-15%, and drying the surface of the agricultural and forestry solid waste fibers again after spraying; Step 3: Evenly mix the bonding powder A with the agricultural and forestry solid waste fibers whose surfaces have been dried again in Step 2, ensuring that the powder adheres to the surfaces of the fibers to obtain a mixture; Step 4: spray the mixed material dried again in step 3 with the bonding reaction liquid B; control the moisture content of the material after spraying to be 5-6%; Step 5: Apply release oil to the mold, introduce the material processed in step 4 into the mold, and apply pressure to press and form the building slab; Step 6, after the building board is demolded, it is placed and cured under constant temperature and humidity conditions to form a building material board.

[0024] Wherein, the agricultural and forestry solid waste fiber refers to a fiber-like substance obtained by processing and treating the waste generated in the agricultural and forestry production, such as straw fiber, wood fiber, etc.

[0025] Wherein, the coupling agent is selected from silane coupling agents, specifically one of KH-560 (γ-glycidoxypropyltrimethoxysilane), KH-550 (γ-aminopropyltriethoxysilane), and KH-570 (γ-methacryloyloxypropyltrimethoxysilane); used to improve the interfacial bonding performance between the agricultural and forestry solid waste fiber and the inorganic glue material.

[0026] Wherein, the cement or light-burned magnesium oxide powder can be selected as the cementing powder A, which is a component of the inorganic glue material and can be cemented with the cementing reaction liquid B to form a cementing body.

[0027] Wherein, when the cementing powder A is selected as the light-burned magnesium oxide powder, the cementing reaction liquid B can be selected as a magnesium chloride solution with a Baume degree of 26 or a magnesium sulfate solution with a Baume degree of 24: used to occur a cementing reaction with the light-burned magnesium oxide powder to form a cementing body. When the cementing powder A is selected as the cement, the cementing reaction liquid B is selected as water.

[0028] Demolding oil or demolding paper: used for mold demolding to prevent material adhesion to the mold.

[0029] Example 1 1. Agricultural and forestry solid waste fiber pretreatment: dry the agricultural and forestry solid waste fiber to dry the surface and remove excess water in the fiber, which is convenient for subsequent processing. The agricultural and forestry solid waste fiber is selected as straw fiber.

[0030] 2. Coupling agent solution preparation: prepare a 5% mass fraction coupling agent aqueous solution, continuously stir before use to ensure that the coupling agent is dissolved in water. The coupling agent is a silane coupling agent, specifically selected as KH-550 (γ-aminopropyltriethoxysilane).

[0031] 3. Preparation of cementing B solution: prepare a magnesium chloride solution with a Baume degree of 26, continuously stir before use to ensure that the solute is dissolved in water.

[0032] 4. Agricultural and forestry solid waste fiber metering: use a 3L container that can measure the volume, fill the agricultural and forestry solid waste fiber, and add the agricultural and forestry solid waste fiber in batches during filling. Each time, the agricultural and forestry solid waste fiber needs to be shaken for 10s to make it compact. Confirm that the volume of the measured agricultural and forestry solid waste fiber is 3L. Weigh and determine the weight of this part of the agricultural and forestry solid waste fiber as m1. The subsequent agricultural and forestry solid waste fiber with a mass of m1 can be directly used to estimate its volume as 3L.

[0033] 5. Measurement of light-burned magnesium oxide powder: Use light-burned magnesium oxide powder as bonding powder A, and weigh 1L of light-burned magnesium oxide powder into a container.

[0034] 6. Surface Treatment of Agricultural and Forestry Solid Waste Fibers: Spray the weighed agricultural and forestry solid waste fibers from step 4 with the coupling agent solution prepared in step 2, stirring while spraying and controlling the moisture content to 10%. After spraying, dry or air-dry again until the surface is dry. Treatment with the coupling agent improves the interfacial bonding between the agricultural and forestry solid waste fibers and the inorganic adhesive. This step should precede the addition of adhesive powder A to ensure that the coupling agent acts first on the straw surface, drying and maintaining the modified groups on the straw surface. Furthermore, drying should prevent excess moisture from affecting the subsequent mixing of the powder and the addition of adhesive solution B.

[0035] 7. Material Mixing: Place the light-burned magnesium oxide weighed in step 5 and the treated agricultural and forestry solid waste fibers from step 6 in a blender and stir until the powder adheres to the fiber surfaces. Unlike conventional methods where the adhesive is first mixed with water and then mixed with the agricultural and forestry solid waste fiber admixture, this method first mixes the powder with the agricultural and forestry solid waste. A coupling agent can be used to ensure that the powder adheres fully to the surface of the agricultural and forestry solid waste fibers. The subsequent addition of water increases the bonding nodes between the agricultural and forestry solid waste fibers, resulting in a tighter bond.

[0036] 8. Adjust the moisture content: Spray the mixed material in step 7 with the adhesive solution B prepared in step 3, stirring while spraying, and control the moisture content to 5% to prepare for subsequent molding. Controlling the moisture content is the key to the high straw fiber addition in this application. With low moisture content, the material is in a semi-dry state, and after being compressed in the later stage, it can be ensured that there is only a thin layer of adhesive between the straws. However, due to the coupling agent, the adhesive powder B is not only evenly dispersed on the agricultural and forestry solid waste fibers, but also well combined, so it can bond the materials. If the pressure is low, it is easy to form gaps and reduce the weight of the board; if the pressure is high, it is easy to increase the straw addition and improve the strength of the material.

[0037] 9. Material Loading: Use an iron or aluminum plate as the base mold and a circular or polygonal frame with cutouts at a defined height as the side molds. Apply release oil or paper to the base mold. Fill the cavity formed by the base and side molds with the mixed material. Add the material in multiple layers and spread it layer by layer. Depending on the height of the side molds, remove excess material by touch to ensure uniform loading. Ensure that the material volume in each part is similar before and after the forward pressure is applied, so that the performance of each part is uniform after the material is formed.

[0038] 10. Pressurized molding: Select a top mold that matches the size of the side molds and control the material height by applying pressure. The height change actually changes the internal voids of the material. There are three types of pressure applied, as follows: When the applied pressure is 0-0.5MPa, the building material product contains excessive and continuous voids. Grouting is used to pour the adhesive slurry into the specimen, which eventually fills the voids. The resulting specimen has a network-like distribution of agricultural and forestry fibers and few voids. This molding method provides the highest compressive strength and heaviest weight.

[0039] When the applied pressure is 2-3 MPa, a certain amount of non-through voids exist within the building material, eliminating the need for grouting. This results in a relatively lightweight specimen with average mechanical properties. This molding method offers the lightest weight and average performance.

[0040] When the applied pressure is 6-10 MPa, there are essentially no visible voids within the building material, resulting in a product with high gravimetric mechanical properties and the highest straw addition ratio per unit volume. This molding method also offers the highest flexural strength and the highest amount of agricultural and forestry solid waste.

[0041] 11. Curing and molding: There are two curing methods, as follows: Curing method 1: After continuously applying pressure, demould after 1 day, and then let it stand for 3 days at a temperature of 20±5℃ and a humidity of 65±5%. After curing and forming, the finished building material is obtained.

[0042] Curing Method 2: After applying continuous pressure and high temperature (40-60°C), demold after 2-4 hours. Then, let it stand for 1 day at a temperature of 20±5°C and a humidity of 65±5% to cure and form the finished building material. (High temperature accelerates the reaction rate).

[0043] Example 2 The difference between Example 2 and Example 1 is that the volume ratio of bonding powder to agricultural and forestry solid waste fiber is 1:2, the bonding reaction liquid B is a magnesium sulfate solution with a Baume degree of 24, and the agricultural and forestry solid waste fiber is sawdust fiber; when the agricultural and forestry solid waste fiber is sprayed with the coupling agent solution, the moisture content is controlled at 12.5%, and when the bonding solution B is sprayed, the moisture content is controlled at 6%.

[0044] Example 3 The difference between Example 3 and Example 1 is that sulphoaluminate cement is used as the bonding powder, and water is used as the bonding liquid, with a volume ratio of 1:4. When the agricultural and forestry solid waste fibers are sprayed with the coupling agent solution, the moisture content is controlled at 15%, and when the bonding solution B is sprayed, the moisture content is controlled at 6%.

[0045] The above is only an embodiment of the present invention, and the common knowledge such as the specific structure and characteristics of the scheme is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several variations and improvements can be made, which should also be regarded as the scope of protection of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A method for preparing building material boards by combining agricultural and forestry solid waste fibers with inorganic adhesives, characterized by: The following steps are involved: Step 1: Drying the surface of agricultural and forestry solid waste fibers to remove surface moisture from the fibers; Step 2: Spray the coupling agent solution on the surface of the agricultural and forestry solid waste fibers, controlling the moisture content after spraying to 10%-15%, and drying the surface of the agricultural and forestry solid waste fibers again after spraying; Step 3: Weigh the adhesive powder A and mix it evenly with the agricultural and forestry solid waste fibers whose surfaces have been dried again in step 2, ensuring that the adhesive powder A adheres to the surfaces of the fibers to obtain a mixture, wherein the volume ratio of the adhesive powder A to the agricultural and forestry solid waste fibers is 1:2-4; Step 4: spray the mixed material in step 3 with the bonding reaction liquid B that can react with the bonding powder A to produce a gelling reaction; control the moisture content of the material after spraying to be 5-6%; Step 5: Apply release oil to the mold, introduce the material processed in step 4 into the mold, apply a pressure of 0-10 MPa to press, and form a building slab; Step 6: After demoulding the building slab, the building slab is allowed to stand and cure for 1-3 days under constant temperature and humidity conditions to obtain a building material board.

2. The method for preparing a building material board using agricultural and forestry solid waste fibers combined with an inorganic adhesive according to claim 1, characterized in that: The bonding powder A in step 3 is light-burned magnesium oxide powder, and the bonding reaction solution B in step 4 is a magnesium chloride solution with a Baume degree of 26 or a magnesium sulfate solution with a Baume degree of 24.

3. The method for preparing a building material board from agricultural and forestry solid waste fibers combined with an inorganic adhesive according to claim 2, characterized in that: In step 2, the coupling agent is a silane coupling agent, and the mass concentration of the coupling agent solution is 5%, and the moisture content after spraying on the surface of the agricultural and forestry solid waste fiber is controlled to be 10%.

4. The method for preparing a building material board using agricultural and forestry solid waste fibers combined with an inorganic adhesive according to claim 3, characterized in that: In step 4, the bonding reaction liquid B is sprayed onto the mixture, and the moisture content of the material after spraying is controlled to be 5%.

5. The method for preparing a building material board using agricultural and forestry solid waste fibers combined with an inorganic adhesive according to claim 3, characterized in that: The silane coupling agent is γ-aminopropyltriethoxysilane.

6. The method for preparing a building material board using agricultural and forestry solid waste fibers combined with an inorganic adhesive according to claim 1, characterized in that: The bonding powder A is cement, and the bonding reaction liquid is water.

7. The method for preparing a building material board using agricultural and forestry solid waste fibers combined with an inorganic adhesive according to claim 6, characterized in that: The cement is sulphoaluminate cement.

8. The method for preparing a building material board using agricultural and forestry solid waste fibers combined with an inorganic adhesive according to claim 1, characterized in that: When applying pressure for pressing in step 5, when the applied pressure is 0-0.5 MPa, adhesive grouting is also required. The grouting adhesive slurry will flow inside the test piece and fill the gaps inside the building slab.

9. The method for preparing a building material board using agricultural and forestry solid waste fibers combined with an inorganic adhesive according to claim 1, characterized in that: The curing process in step 6 is to continuously apply pressure, demould after 1 day, and then stand for 3 days at a temperature of 20±5°C and a humidity of 65±5%. After curing and forming, the finished building material is obtained.

10. The method for preparing a building material board using agricultural and forestry solid waste fibers combined with an inorganic adhesive according to claim 1, characterized in that: The curing process in step 6 is to continuously apply pressure and high temperature, the high temperature being 40-60°C; demoulding after 2h-4h, and then standing for 1d at a temperature of 20±5°C and a humidity of 65±5%. After curing and forming, the finished building material is obtained.

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