Large-size composite board based on coffee grounds and preparation method of large-size composite board

Abstract

The invention discloses a large-size composite board based on coffee grounds and a preparation method of the large-size composite board. The method comprises the following steps: firstly, degreasing coffee grounds through a supercritical or near-supercritical carbon dioxide extraction process to obtain low-grease and high-stability coffee grounds powder; and fully mixing the degreased coffee residue powder with high-density polyethylene powder in a dry state. And finally, carrying out long-time hot press molding (such as 1 hour) under the conditions of high temperature of 160-200 DEG C and high pressure of 1000-3000 tons, so as to stably prepare a large-size plate (1500 * 3000 mm). According to the method, the filling proportion of the coffee grounds can be remarkably increased, the peculiar smell and the mildew risk are reduced, and the excellent performance of the plate in the aspects of mechanical property, flatness and durability can be guaranteed. Meanwhile, the coffee oil obtained through extraction can be applied to the fields of cosmetics or fragrances and the like, and the resource utilization value is improved. The method is simple in process, environment-friendly, feasible, suitable for industrial production of large composite boards of various specifications and wide in application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of environmentally friendly materials, and in particular to a large-size composite plate based on coffee grounds and a preparation method thereof. Background Art

[0002] In today's increasingly environmentally conscious world, waste recycling has become a hot topic in the materials science field. The rapidly growing global coffee industry generates significant quantities of coffee grounds, which, if simply discarded or landfilled, waste resources and burden the environment. Therefore, the rational utilization of coffee grounds holds significant economic and environmental significance. Incorporating coffee grounds into composite panel manufacturing effectively addresses the disposal issue while also partially replacing raw materials in traditional panel manufacturing, achieving resource recycling.

[0003] There has been some research and development into coffee ground composite panels. However, existing coffee ground composite panels often suffer from numerous issues. First, to maintain the basic mechanical properties of the panels, the coffee ground content is often low. This low content not only fails to fully utilize the advantages of coffee ground waste recycling, but also makes it difficult to achieve significant cost competitiveness.

[0004] Secondly, from a mechanical performance perspective, the tensile strength, flexural strength, and other mechanical properties of existing sheet materials are insufficient to meet the requirements of some practical applications. For example, in architectural decoration, sheet materials used as wall decorations or lightweight partitions require a certain level of strength to withstand daily collisions and minor pressure, but existing coffee ground-based composite panels perform poorly in this regard. This is primarily due to the physical properties of coffee grounds differing from those of traditional sheet reinforcements, making it difficult to form an effective reinforcement structure during the composite process.

[0005] Furthermore, durability is a concern. Existing panels of this type are susceptible to deformation and cracking over long periods of use due to environmental factors such as humidity and temperature fluctuations. For example, in humid environments, the panels easily absorb water and expand, resulting in poor dimensional stability and affecting their normal use.

[0006] Furthermore, these issues are exacerbated when manufacturing large-scale coffee ground-based composite panels. The increased size complicates the stress distribution within the panels, placing even higher demands on mechanical properties and durability. However, current technology struggles to achieve both excellent mechanical properties and durability in large-scale panels while maintaining a high coffee ground content.

[0007] In summary, how to make large-sized composite panels based on coffee grounds have high coffee grounds content, excellent mechanical properties and good durability has become a technical problem that needs to be solved urgently in this field. Summary of the Invention

[0008] The technical problem to be solved by the present invention is: how to make a large-sized composite board based on coffee grounds have a high coffee grounds content, excellent mechanical properties and good durability.

[0009] In order to solve the above technical problems, the first aspect of the present invention provides a large-sized composite board based on coffee grounds, comprising:

[0010] Defatted coffee grounds, accounting for 30% to 80% of the total weight of the composite board;

[0011] High-density polyethylene, accounting for 20% to 70% of the total weight of the composite board;

[0012] The side length of the composite board is greater than 1.5 meters.

[0013] In some embodiments, the defatted coffee grounds account for 40% to 70% of the total weight of the composite sheet, and the high-density polyethylene accounts for 30% to 60% of the total weight of the composite sheet.

[0014] In some embodiments, the composite board further includes one or any combination of a compatibilizer, an antioxidant, and a mildewproofing agent, and the total amount of the above additives does not exceed 5% of the total weight of the composite board.

[0015] In some embodiments, the additive is a compatibilizer or a mildew inhibitor, which accounts for 1% of the total weight of the composite board.

[0016] A second aspect of the present invention provides a method for preparing the large-sized composite board based on coffee grounds, comprising the following steps:

[0017] Step 1: coffee grounds are dried, crushed, and degreased to obtain coffee grounds powder;

[0018] Step 2: coffee grounds powder and high-density polyethylene powder are placed in a mixing device according to a proportion and dry-mixed to obtain a mixed powder;

[0019] Step 3: placing the mixed powder in a mold of a flat-plate hot press, setting the hot pressing temperature to 160-200° C., and pressing under a pressure of 1000-3000 tons for not less than 1 hour;

[0020] Step 4: Continue to maintain the same pressure, and demould after natural cooling to obtain a large-sized composite board product.

[0021] In some embodiments, step 1 includes the following sub-steps:

[0022] Step 1.1, drying the coffee grounds at 40-80° C. until the moisture content is less than 5%;

[0023] Step 1.2, grind the coffee grounds and sieve them, taking 20-200 mesh coffee grounds for extraction;

[0024] In step 1.3, the coffee grounds are placed in a CO2 extraction device to extract the oil.

[0025] In some embodiments, a supercritical or near-supercritical CO2 extraction device is used to remove oil from coffee grounds, with specific parameters as follows: CO2 flow rate of 25 kg / h, separation kettle pressure of 8 MPa, temperature of 25°C, and extraction time of 30 to 60 minutes.

[0026] In some embodiments, a supercritical or near-supercritical CO2 extraction device is used to remove oil from coffee grounds, with specific parameters as follows: CO2 flow rate of 25 kg / h, separation kettle pressure of 25-35 MPa, temperature of 40-60°C, and extraction time of 60-120 minutes.

[0027] In some embodiments, the particle size of the coffee grounds powder in step 2 is 20-200 mesh, and the particle size of the high-density polyethylene powder is 20-200 mesh.

[0028] In some embodiments, the hot pressing temperature in step 3 is 180° C., and the pressing time is 1 hour.

[0029] The beneficial effects of the present invention are as follows: by using supercritical / near-supercritical CO2 to extract oil from coffee grounds and combining it with a new concept of dry mixing + long-term hot pressing, a high coffee ground filling volume can be achieved, while reducing odor and mildew, ensuring the stability and uniformity of the mechanical properties and durability of large-size boards, and improving the comprehensive utilization value of coffee grounds. DETAILED DESCRIPTION

[0030] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0031] The present invention provides a large-sized composite board based on coffee grounds and a method for preparing the same. The hot-pressed board is typically rectangular, and the large-sized board in the present invention refers to a board with a short side length of no less than 1500 mm, for example, 1500 x 3000 mm.

[0032] Coffee grounds are degreased using supercritical or near-supercritical carbon dioxide extraction, then dry-mixed with HDPE powder. The mixture is then formed under high temperature, high pressure, and prolonged hot pressing to create a large-scale composite sheet with excellent mechanical properties, durability, and environmental friendliness. The specific steps are as follows.

[0033] In the first step, the coffee grounds are degreased using supercritical or near-supercritical carbon dioxide extraction technology.

[0034] Coffee grounds contain a certain amount of oil, which will affect the bonding strength between the coffee grounds and other materials during the preparation of composite boards. Traditional degreasing methods may not be able to completely remove the oil, or may damage the structure of the coffee grounds during the degreasing process. Supercritical or near-supercritical carbon dioxide extraction technology has unique advantages. In the supercritical or near-supercritical state, carbon dioxide has the dual properties of gas and liquid, with a large diffusion coefficient, low viscosity, and low surface tension. It can quickly penetrate into the coffee grounds and efficiently dissolve and remove the oil components therein. This degreasing method not only has a good degreasing effect, but also causes minimal damage to the physical structure of the coffee grounds, which is conducive to the subsequent coffee grounds playing their reinforcing role in the composite board and lays the foundation for increasing the content of coffee grounds in the board.

[0035] First, we select coffee grounds from a suitable source to ensure their basic properties are relatively stable. The collected grounds are initially screened to remove any impurities, such as coffee husk fragments and foreign matter. The grounds are then dried at 40-80°C to remove moisture to a moisture content of less than 5%. The dried grounds are then crushed and sieved to a mesh size of 20-200.

[0036] The 20-200 mesh coffee grounds are then degreased using supercritical or near-supercritical carbon dioxide extraction technology. In the extraction equipment, the coffee grounds are placed in an extraction vessel, and carbon dioxide gas is introduced. The temperature and pressure are adjusted to a supercritical or near-supercritical state. Generally, the temperature of supercritical carbon dioxide is controlled above 31.1°C and the pressure is controlled above 7.38 MPa. The near-supercritical state can be fine-tuned around the critical value based on actual needs, for example, a temperature of 30-32°C and a pressure of 7-8 MPa.

[0037] Preferably, a supercritical or near-supercritical CO2 extraction device is used to remove oil from coffee grounds. The specific parameters are: CO2 flow rate 25 kg / h, separation kettle pressure 8 MPa, temperature 25°C, and extraction time 30 to 120 minutes. The pressure (e.g., 25 to 35 MPa) or temperature (e.g., 40 to 60°C) can also be appropriately adjusted according to the actual equipment and coffee grounds batch to obtain the ideal degreasing effect.

[0038] Carbon dioxide efficiently penetrates the coffee grounds, dissolving and extracting the oily components. Extraction time varies depending on the amount of coffee grounds and equipment specifications, typically ranging from 1 to 3 hours to ensure sufficient oil removal. After extraction, the carbon dioxide is separated from the coffee grounds by reducing the pressure, and the recovered carbon dioxide can be recycled to produce defatted coffee grounds. The coffee oil extracted in this process can be used in cosmetics or fragrances, increasing the added value of the by-product.

[0039] In the second step, dry-blend the defatted coffee grounds with high-density polyethylene (HDPE) powder. If necessary, add a compatibilizer, mildew inhibitor, or antioxidant and stir until evenly dispersed.

[0040] Mix the defatted coffee grounds with high-density polyethylene (HDPE) powder in a suitable proportion in a dry state. The defatted coffee grounds powder accounts for 30% to 80% of the total weight of the composite board, preferably 40% to 70%, which can be selected according to the target mechanical and appearance effects. The high-density polyethylene (HDPE) powder accounts for 20% to 70% of the total weight of the composite board, preferably 30% to 60%. The high-density polyethylene can be derived from recycled cosmetic bottles or other HDPE products, and is crushed or ground into a certain particle size (such as 20 to 200 mesh). High-density polyethylene molecules are tightly arranged and it is the highest density polyethylene, with a density of 0.942 to 0.950 g / cm 3 In order to improve the performance, additives such as maleic anhydride grafted polyethylene (MAH-g-PE) can be added to the mixed powder as a compatibilizer, antioxidant, mildew inhibitor, etc., with the addition amount being 0-5%.

[0041] The mixing process uses mechanical stirring and other methods to ensure uniform mixing of the raw materials. The mixing equipment can be a high-speed mixer with a stirring speed of 500-1000 rpm and a stirring time of 15-30 minutes to ensure that the coffee grounds and HDPE powder are fully and evenly dispersed, laying a good foundation for subsequent hot pressing.

[0042] Dry mixing ensures a uniform distribution of coffee grounds and HDPE powder, preventing the adverse effects of moisture introduced during wet mixing on board performance. During wet mixing, moisture can hydrolyze the HDPE, reducing its molecular weight and weakening the board's mechanical properties. Dry mixing also helps form a better interface between the coffee grounds and HDPE during the subsequent hot pressing process, further improving the board's overall performance.

[0043] The third step is to use a long-term hot pressing process under high temperature and high pressure conditions to prepare large-sized plates.

[0044] The evenly mixed raw materials are transferred to the hot pressing mold. The mold size is customized according to the target large-size plate specifications. For example, if a 1500×3000mm plate is prepared, the mold is designed to this size accordingly. Close the mold, apply high temperature and high pressure to it and maintain it for a certain time for hot pressing. The hot pressing temperature is set above the melting point of HDPE, generally 160-200°C, preferably 180°C. The pressure is controlled between 10 and 30 MPa, that is, a pressure of 1000 to 3000 tons. The hot pressing time is relatively long, usually 30 to 60 minutes, preferably 60 minutes, to ensure uniform temperature and density inside and outside the large-size plate (such as 1500×3000mm).

[0045] During the hot pressing process, temperature, pressure, and time parameters are closely monitored to ensure a stable hot pressing process. After the hot pressing is completed, the pressure is slowly released, and after the mold cools to a certain temperature (such as 50-60°C), the formed large-sized composite sheet is removed.

[0046] High temperatures fully melt the HDPE powder, increasing its fluidity and enabling it to better wrap around the coffee grounds particles. High pressure forces the coffee grounds to tightly bond with the HDPE, reducing voids within the sheet and increasing its density. The prolonged hot pressing process helps form a more stable and uniform structure, which is crucial for large-sized sheets (such as 1500×3000mm). This stable and uniform structure effectively improves stress distribution within the sheet, avoiding stress concentration associated with increased size, thereby enhancing the sheet's mechanical properties and durability.

[0047] Example 1

[0048] 1. Raw material formula

[0049] Defatted coffee grounds powder: 60wt%

[0050] HDPE powder: 40wt%

[0051] No additives

[0052] 2. Preparation Process

[0053] Coffee grounds pretreatment

[0054] The coffee grounds were dried at 60°C for 2 hours to reduce the moisture content to below 5%; they were crushed to about 80 mesh; they were extracted for 1 hour in a separation kettle at a pressure of 8 MPa, a temperature of 25°C, and a CO2 flow rate of 25 kg / h, and the coffee grounds were dried after removing the oil.

[0055] Powder mixing

[0056] 60 wt% of defatted coffee grounds powder and 40 wt% of HDPE powder were dry-mixed in a mixer for 5 minutes.

[0057] Hot Press Forming

[0058] The mixed powder was placed in a flat-plate hot press with a slab size of 1500 x 3000 mm. The press temperature was set at 180°C and the pressure was 2000 tons (20 MPa). The hot press was maintained for one hour to ensure uniform melting and compaction across the large surface area. Under the same pressure, the slab was slowly cooled to 50-60°C before demolding to obtain the high-coffee grounds composite sheet.

[0059] Performance and Observation

[0060] The board's appearance is smooth, with no visible bubbles or delamination. Flexural strength, impact strength, and water absorption all meet expectations. There's no noticeable grease seepage or odor, and even after prolonged use and exposure to high humidity, no mold or mildew is evident.

[0061] Example 2

[0062] Based on Example 1, 1 wt% of maleic anhydride-grafted polyethylene (MAH-g-PE) was added as a compatibilizer, and the coffee grounds extraction time was extended to 1.5 hours to improve interfacial bonding and reduce residual oil. Other procedures were similar, and the resulting sheet, sized 1500 x 3000 mm, still exhibited higher flexural strength and toughness.

[0063] Example 3

[0064] Based on Example 1, the coffee grounds powder content was adjusted to 50 wt%, and 1 wt% of a mildew inhibitor was added. The hot pressing time remained at 1 hour, with all other parameters unchanged. Testing in a high-humidity environment revealed no mildew or significant strength loss.

[0065] Compared with the prior art, the present invention has the following advantages:

[0066] High coffee grounds ratio and low odor risk: Supercritical CO2 extraction fully removes oil, reduces odor and mildew, and improves the durability of the material. It can maintain stable mechanical properties at high filling content (50% to 70%).

[0067] Suitable for large board sizes (1500×3000mm): By extending the hot pressing time to 1 hour and setting a sufficiently high pressing force, the coffee grounds-HDPE powder is ensured to be melted and compacted uniformly in large-area boards.

[0068] Resource recycling and environmental protection: The coordinated utilization of coffee grounds and recycled HDPE, while recycling high-value coffee oil, achieves multiple environmental and economic benefits.

[0069] Process simplification and adaptability: It adopts dry mixing and hot pressing molding in one step, without the need for traditional extrusion and granulation, and is suitable for large-scale production of various specifications of boards.

[0070] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A large-sized composite board based on coffee grounds, characterized in that: include: Defatted coffee grounds, accounting for 30% to 80% of the total weight of the composite board; High-density polyethylene, accounting for 20% to 70% of the total weight of the composite board; The side length of the composite board is greater than 1.5 meters.

2. The large-sized composite board based on coffee grounds according to claim 1, characterized in that: The defatted coffee grounds account for 40% to 70% of the total weight of the composite board, and the high-density polyethylene accounts for 30% to 60% of the total weight of the composite board.

3. The large-sized composite board based on coffee grounds according to claim 1, characterized in that: The composite board further comprises one or any combination of a compatibilizer, an antioxidant, and a mildewproofing agent, and the total amount of the above additives does not exceed 5% of the total weight of the composite board.

4. The large-sized composite board based on coffee grounds according to claim 3, characterized in that: The additives are compatibilizers or mildew inhibitors, which account for 1% of the total weight of the composite board.

5. The method for preparing a large-sized composite board based on coffee grounds according to claim 1, characterized in that: The steps include: Step 1: coffee grounds are dried, crushed, and degreased to obtain coffee grounds powder; Step 2: The coffee grounds powder and high-density polyethylene powder are placed in a mixing device according to a proportion, and dry-mixed to obtain a mixed powder; Step 3: placing the mixed powder in a mold of a flat-plate hot press, setting the hot pressing temperature to 160-200° C., and pressing under a pressure of 1000-3000 tons for not less than 1 hour; Step 4: Continue to maintain the same pressure, and demould after natural cooling to obtain a large-sized composite board product.

6. The method for preparing a large-sized composite board based on coffee grounds according to claim 5, characterized in that: Step 1 includes the following sub-steps: Step 1.1, drying the coffee grounds at 40-80° C. until the moisture content is less than 5%; Step 1.2, grind the coffee grounds and sieve them, taking 20-200 mesh coffee grounds for extraction; In step 1.3, the coffee grounds are placed in a CO2 extraction device to extract the oil.

7. The method for preparing a large-sized composite board based on coffee grounds according to claim 6, characterized in that: Use a supercritical or near-supercritical CO2 extraction device to remove oil from coffee grounds. The specific parameters are as follows: CO2 flow rate 25kg / h, separation kettle pressure 8MPa, temperature 25℃, and extraction time 30-60 minutes.

8. The method for preparing a large-sized composite board based on coffee grounds according to claim 6, characterized in that: Use a supercritical or near-supercritical CO2 extraction device to remove oil from coffee grounds. The specific parameters are as follows: CO2 flow rate 25kg / h, separation kettle pressure 25-35MPa, temperature 40-60℃, and extraction time 60-120 minutes.

9. The method for preparing a large-sized composite board based on coffee grounds according to claim 5, characterized in that: The particle size of the coffee grounds powder in step 2 is 20-200 mesh, and the particle size of the high-density polyethylene powder is 20-200 mesh.

10. The method for preparing a large-sized composite board based on coffee grounds according to claim 5, characterized in that: The hot pressing temperature in step 3 is 180° C., and the pressing time is 1 hour.