Method for preparing composite material board from waste polyester fabric and discarded hemp stalks

Abstract

The present invention relates to the recycling and reuse of waste materials, particularly waste polyester fabric and discarded hemp stalks. A method for preparing composite panels from waste polyester fabric and discarded hemp stalks is disclosed. The waste polyester fabric and discarded hemp stalks are treated separately and then mixed with a prepared resin adhesive to form a viscous composite material. The viscous composite material is then injection-molded and hot-pressed twice before demolding to obtain the composite panel. The composite panel prepared by the present invention not only solves waste disposal issues and reduces environmental pollution, but can also be widely used as a substitute for wood in construction and decoration.

Description

Technical Field

[0001] The invention relates to the recycling and reuse of waste materials, and in particular to the field of recycling and reuse of waste polyester fabrics and discarded hemp stalks. Background Art

[0002] Today, the textile and apparel industry is a vital livelihood sector and one that creates new international advantages. It holds enormous potential for future growth. It is projected that by 2050, global textile fiber processing will reach 253 million tons. Meanwhile, the volume of textile waste is also increasing annually, with significant negative environmental impacts. Currently, the main methods for treating textile waste include energy recovery, physical and mechanical methods, and chemical recycling. Energy recovery offers low added value and high pollution levels; physical recycling requires high technical requirements, difficult sorting, and requires numerous pre-treatment machines and equipment, resulting in high costs and complex recycling processes; chemical recycling is also quite complex and requires the addition of numerous chemical solvents and chemicals, which increases recycling costs and makes it difficult to implement. These aforementioned methods for textile waste recycling have their shortcomings, and the efficient utilization of textile waste continues to be an area of ​​extensive research. Therefore, the recycling and reuse of textile waste is a major issue of public concern.

[0003] At present, the application of hemp is concentrated on its bast, seeds and other parts. The remaining large amount of hemp stalks are usually discarded or burned as agricultural waste, which not only wastes resources, but also produces carbon dioxide and smoke from burning hemp stalks, causing serious environmental pollution. Recycling hemp stalks not only has environmental benefits, but also can reduce the economic cost of the hemp fiber industry to a certain extent, thereby expanding the development of the hemp industry.

[0004] Composite panels currently used in construction, furniture and other industries such as flooring and wall panels are usually wood composite materials, that is, wood is combined with other materials to form a new composite material. Composite panels are widely used in construction and decoration because of their good physical and mechanical properties, simplified plywood production process and low production cost. However, most composite panels still have a large demand for wood, and the phenolic glue used in the gluing process releases harmful gases such as formaldehyde. In order to solve the above problems, the present invention adopts a green blending hot pressing method to prepare waste polyester fabric and discarded hemp stalks into a new type of environmentally friendly composite panel, which not only has good mechanical properties, but also has properties such as waterproof, corrosion-resistant and high-temperature resistant. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: how to solve the problem of environmental pollution caused by waste polyester fabrics and discarded hemp stalks, and at the same time recycle the waste polyester fabrics and discarded hemp stalks.

[0006] The technical solution adopted by the present invention is: a method for preparing a composite material board from waste polyester fabric and waste hemp stalks, which is carried out in the following steps:

[0007] Step 1: pre-treating the waste polyester fabric, sterilizing the waste polyester fabric at high temperature, processing it into polyester foam material, and then crushing it into polyester powder using a grinder after washing and drying;

[0008] Step 2: Pre-treating the discarded hemp stalks: washing the discarded hemp stalks with water, drying them, soaking them in sodium hydroxide solution, washing them with water until the filtrate is neutral, drying them, and crushing them into hemp powder using a grinder;

[0009] Step 3, preparing resin glue, mixing silane coupling agent KH550, water-based polyurethane emulsion, water-based epoxy resin emulsion, water-based epoxy curing agent and xanthan gum emulsifier at room temperature to prepare resin glue;

[0010] Step 4: Injection molding: Mix the polyester powder, hemp powder, and resin glue evenly to obtain a viscous composite material, inject the composite material into a mold, and dry it;

[0011] Step 5, double hot pressing, the dried mold filled with the composite material is hot pressed for the first time using a flat vulcanizer to obtain a first hot pressed preform, the surface of the first hot pressed preform is evenly coated with a layer of polypropylene (PP) powder, and the second hot pressing is performed using a flat vulcanizer to obtain a second hot pressed preform; polypropylene (PP) powder with low melting point and high strength mechanical properties is evenly coated on the surface of the preform after the first hot pressing, the purpose is to use the polypropylene (PP) powder as an "adhesive" and use its own high strength mechanical properties to improve the mechanical properties of the composite material such as internal bonding strength and static bending performance.

[0012] Step 6: Demolding: The second hot pressed preform is naturally cooled at room temperature and demolded to obtain a composite material plate.

[0013] In step 2, the sodium hydroxide solution has a mass percent concentration of 10% and is soaked for 3 to 5 hours. This is to remove impurities such as lignin, hemicellulose, and pectin from the hemp stalks, improve the wettability and hydrophilicity of the hemp fibers, and enhance the bonding between the fibers and the resin.

[0014] In step three, the mass ratio of silane coupling agent KH550, water-based polyurethane emulsion, water-based epoxy resin emulsion, water-based epoxy curing agent and xanthan gum emulsifier is 1:2.1:2:2:1.

[0015] In step 4, the mass ratio of polyester powder, hemp powder, and resin glue in the viscous composite material is 9-12:1:10-14. This raw material ratio can achieve optimal mechanical properties of the composite material board.

[0016] In step 4, the drying temperature is 60-80°C and the drying time is 80-100 minutes. The purpose of drying is to remove moisture from the composite preform and prevent the formation of pores on the surface of the composite board due to bubbles during hot pressing, which may affect the performance of the board.

[0017] In step five, the first hot press is performed at a temperature of 150-170°C, a time of 20-30 minutes, and a pressure of 10-13 MPa. The second hot press is performed at a temperature of 180-200°C, a time of 15-25 minutes, and a pressure of 10-13 MPa. The first hot press fully cures the adhesive in the composite board. The pressure of 10-13 MPa increases the density of the composite board in the mold, reduces the likelihood of looseness and edge collapse in the composite board preform, and improves the quality of the waste polyester fabric-waste hemp stalk composite board to a certain extent. The second hot press fully melts the PP powder and coats it on the surface of the prefabricated material board, further overcoming internal friction and rebound forces, removing air from the material board, increasing the fiber contact surface and density, and enhancing the high-strength performance of the composite board.

[0018] When the dried mold filled with composite material is hot-pressed for the first time on a flat-plate vulcanizer, pre-pressing is performed first, followed by the second hot-pressing. The pre-pressing conditions are: temperature 150-170°C, time 3-5 minutes, and pressure 7 MPa. The purpose is to melt the resin, remove volatiles, and further bond with the raw material.

[0019] The beneficial effects of the present invention are: the present invention solves the problem of environmental pollution caused by waste polyester fabrics and discarded hemp stalks, and at the same time synthesizes a new type of composite board with simple production process and economic benefits, which can be widely used to replace wood in the fields of construction and decoration.

[0020] Silane coupling agents can modify the surface of waste polyester fibers, interacting with both the hydroxyl groups in the material and the long molecular chains in the polymer, "coupling" materials of different properties while also providing waterproofing. The isocyanate groups (-NCO) in waterborne polyurethane emulsions can cross-link with the hydroxyl groups in composite materials to produce carbamates. When used in conjunction with a waterborne epoxy curing agent, the epoxy groups in the resin can react with various active hydrogen compounds to open the rings and react. Furthermore, the emulsions exhibit strong adhesion, high temperature resistance, and high cross-link density, improving the mechanical properties of the composite. Xanthan gum emulsifiers can also thicken and set the composite.

[0021] This invention produces a composite board made from waste polyester fabric and discarded hemp stalks. Due to the high-strength polypropylene powder coating on the surface, the composite board exhibits excellent tensile and bending properties, meeting the needs of various fields such as building materials, furniture, and automobiles. Compared with conventional wooden boards, this new composite board not only offers low cost and high resource utilization, but also possesses waterproof, corrosion-resistant, and high-temperature resistance properties. It also contains no harmful gases such as formaldehyde, making it suitable for both production and daily life. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic flow diagram of the present invention. DETAILED DESCRIPTION

[0023] The present invention will be further described in detail below with reference to specific implementation cases. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0024] Example 1

[0025] A method for preparing a composite material board from waste polyester fabric and discarded hemp stalks is carried out in the following steps:

[0026] Step 1: Pre-treat the waste polyester fabric, sterilize the waste polyester fabric at high temperature, process it into polyester foam material, and then grind it into polyester powder with a grinder after washing and drying.

[0027] Step 2: Pretreatment of discarded hemp stalks: wash the discarded hemp stalks with water 1-2 times, dry them, soak them in a 10% by mass sodium hydroxide solution for 4 hours (to remove impurities such as lignin, hemicellulose, pectin, etc. in the hemp stalks, improve the wettability and hydrophilicity of the hemp fibers, and improve the bonding effect between the fibers and the resin), wash them with water until the filtrate is neutral, dry them, and grind them into hemp powder using a grinder.

[0028] Step 3, preparing a resin glue solution, mixing a silane coupling agent KH550, a water-based polyurethane emulsion, a water-based epoxy resin emulsion, a water-based epoxy curing agent and a xanthan gum emulsifier at room temperature in a mass ratio of 1:2.1:2:2:1 to prepare a resin glue solution;

[0029] Step 4: Injection molding: Polyester powder, hemp powder, and resin glue are mixed uniformly in a mass ratio of 10:1:12 to obtain a viscous composite material. The composite material is then poured into an iron mold and dried at a temperature of 60-80°C for 80-100 minutes. The purpose of drying is to remove moisture from the composite preform to prevent bubbles from forming on the surface of the composite sheet during hot pressing, which could affect the sheet's performance.

[0030] Step 5, double hot pressing, the dried mold filled with the composite material is hot pressed for the first time using a flat vulcanizer to obtain a first hot pressed preform, the surface of the first hot pressed preform is evenly coated with a layer of polypropylene (PP) powder, and the second hot pressing is performed using a flat vulcanizer to obtain a second hot pressed preform; polypropylene (PP) powder with low melting point and high strength mechanical properties is evenly coated on the surface of the preform after the first hot pressing, the purpose is to use the polypropylene (PP) powder as an "adhesive" and use its own high strength mechanical properties to improve the mechanical properties of the composite material such as internal bonding strength and static bending performance.

[0031] The first hot press was performed at 170°C for 20 minutes at a pressure of 11 MPa. The second hot press was performed at 200°C for 15 minutes at a pressure of 11 MPa. The first hot press fully cures the adhesive in the composite sheet, maintaining a pressure of 10-13 MPa. This increases the density of the composite sheet in the mold, reduces the likelihood of looseness and edge collapse in the preform, and improves the quality of the waste polyester fabric-waste hemp stalk composite sheet. The second hot press fully melts the PP powder and coats it on the surface of the preform, further overcoming internal friction and rebound forces, removing air from the sheet, increasing fiber contact area and density, and enhancing the high-strength properties of the composite sheet.

[0032] When the mold filled with the dried composite material is hot-pressed for the first time using a flat-plate vulcanizer, pre-pressing is performed first, followed by the second hot-pressing. The pre-pressing conditions are: temperature 170°C, time 5 minutes, and pressure 7 MPa. The purpose is to melt the resin, remove volatiles, and further bond with the raw material.

[0033] Step 6: Demolding: The second hot pressed preform is naturally cooled at room temperature and demolded to obtain a composite material plate.

[0034] According to the density test method specified in 4.2 of GB / T17657-2013: the density of the composite material board under these conditions is 0.81g / cm3. According to the thickness expansion rate test method specified in 4.4 of GB / T17657-2013: the thickness expansion rate of the composite material board under these conditions is 10.72%.

[0035] According to the test method for static bending strength specified in 4.7 of GB / T17657-2013, under this condition, the composite material plate can meet the static bending strength standard specified in the national standard GB12626.2-90.

[0036] Example 2:

[0037] Prepare the raw materials: After high-temperature sterilization, the recycled waste polyester fabric is processed into polyester foam material through a chemical fiber foaming machine, washed and dried, and then crushed into powder using a grinder; the discarded hemp stalks are first washed with distilled water 1-2 times, dried in a blast drying oven, and then soaked in sodium hydroxide solution for 4 hours, washed with distilled water until the filtrate is neutral, dried, and crushed into powder using a grinder;

[0038] Preparation of adhesive: silane coupling agent (KH550), water-based polyurethane emulsion, water-based epoxy resin emulsion, water-based epoxy curing agent and xanthan gum emulsifier were mixed and stirred at room temperature in a mass ratio of 1:2.1:2:2:1 to prepare resin adhesive;

[0039] Injection molding: Waste polyester foam material powder, hemp stalk powder and prepared resin glue are fully stirred and mixed at a mass ratio of 12:1:14 at room temperature to obtain a viscous composite material, which is spread in an iron mold and dried.

[0040] Double hot pressing: First, the dried composite material is pre-pressed at a temperature of 170°C, a time of 5 minutes, and a pressure of 7 MPa to obtain a preform; the first hot pressing is performed at a temperature of 170°C, a time of 20 minutes, and a pressure of 11 MPa; after cooling, a layer of polypropylene (PP) powder is coated on the surface of the preform, and the second hot pressing is performed at a temperature of 200°C, a time of 15 minutes, and a pressure of 11 MPa.

[0041] Cooling and demoulding: After the second hot pressing, the preform is naturally cooled and demoulded at room temperature to produce a new type of composite material board.

[0042] According to the density test method specified in 4.2 of GB / T17657-2013: the density of the composite material board under these conditions is 0.85g / cm3. According to the thickness expansion rate test method specified in 4.4 of GB / T17657-2013: the thickness expansion rate of the composite material board under these conditions is 9.37%.

[0043] According to the test method for static bending strength specified in 4.7 of GB / T17657-2013, under this condition, the composite material plate can meet the static bending strength standard specified in the national standard GB12626.2-90.

[0044] The method for producing the waste polyester fabric-waste hemp stalk composite material board of the present invention recycles the waste polyester fabric and the waste hemp stalk at the same time, which not only reduces pollution to the environment but also produces high value-added products, realizing the possibility of "turning two wastes into one treasure".

[0045] This invention produces a composite board made from waste polyester fabric and discarded hemp stalks. Due to the high-strength polypropylene powder coating on the surface, the composite board exhibits excellent tensile and bending properties, meeting the needs of various fields such as building materials, furniture, and automobiles. Compared with conventional wooden boards, this new composite board not only offers low cost and high resource utilization, but also possesses waterproof, corrosion-resistant, and high-temperature resistance properties. It also contains no harmful gases such as formaldehyde, making it suitable for both production and daily life.

[0046] The above description is a detailed explanation of some feasible embodiments of the present invention, but the embodiments are not intended to limit the scope of the patent application of the present invention. Any equivalent changes or modifications made based on the contents described in the scope of patent protection application of the present invention should fall within the scope of the patent covered by the present invention.

Claims

1. A method for preparing a composite material board from waste polyester fabric and discarded hemp stalks, characterized by: Follow the steps below Step 1: pre-treating the waste polyester fabric, sterilizing the waste polyester fabric at high temperature, processing it into polyester foam material, and then crushing it into polyester powder using a grinder after washing and drying; Step 2: Pre-treating the discarded hemp stalks: washing the discarded hemp stalks with water, drying them, soaking them in sodium hydroxide solution, washing them with water until the filtrate is neutral, drying them, and crushing them into hemp powder using a grinder; Step 3, preparing a resin glue solution, mixing a silane coupling agent KH550, a water-based polyurethane emulsion, a water-based epoxy resin emulsion, a water-based epoxy curing agent, and a xanthan gum emulsifier at room temperature to prepare a resin glue solution; the mass ratio of the silane coupling agent KH550, the water-based polyurethane emulsion, the water-based epoxy resin emulsion, the water-based epoxy curing agent, and the xanthan gum emulsifier is 1:2.1:2:2:1; Step 4: Injection molding: Evenly mix the polyester powder, hemp powder, and resin glue to obtain a viscous composite material, inject the composite material into a mold, and dry it; in the viscous composite material, the mass ratio of polyester powder, hemp powder, and resin glue is 9-12:1:10-14; Step 5, hot pressing twice, the dried mold filled with the composite material is hot pressed for the first time using a flat vulcanizer to obtain a first hot pressed preform, the surface of the first hot pressed preform is evenly coated with a layer of polypropylene PP powder, and hot pressed for the second time using a flat vulcanizer to obtain a second hot pressed preform; Step 6: Demolding: The second hot pressed preform is naturally cooled at room temperature and demolded to obtain a composite material plate.

2. The method for preparing a composite material board from waste polyester fabric and discarded hemp stalks according to claim 1, characterized in that: In step 2, the mass percent concentration of the sodium hydroxide solution is 10%, and the soaking time is 3 to 5 hours.

3. The method for preparing a composite material board from waste polyester fabric and discarded hemp stalks according to claim 1, characterized in that: In step 4, the drying temperature is 60-80°C and the drying time is 80-100 minutes.

4. The method for preparing a composite material board from waste polyester fabric and discarded hemp stalks according to claim 1, characterized in that: In step 5, the conditions for the first hot pressing are: temperature 150~170℃, time 20~30min, pressure 10~13MPa, and the conditions for the second hot pressing are: temperature 180~200℃, time 15~25min, pressure 10~13MPa.

5. The method for preparing a composite material board from waste polyester fabric and discarded hemp stalks according to claim 1, characterized in that: When the dry mold filled with composite materials is hot-pressed for the first time using a flat vulcanizer, pre-pressing is first performed, and then the first hot pressing is performed. The pre-pressing conditions are: temperature 150~170℃, time 3~5min, and pressure 7MPa.

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