Pulp for pulp molding, pulp molded product and preparation method of pulp molded product

Abstract

The invention provides pulp for pulp molding, a pulp molded product and a preparation method of the pulp molded product, and relates to the technical field of pulp molding. The pulp for paper pulp molding comprises activated coffee grounds and fiber paper pulp, the activated coffee grounds are obtained by performing degreasing, pyrolysis and alkali solution activation on coffee grounds raw materials, the mass percent of the activated coffee grounds is 100%, and the activated coffee grounds comprise 5%-10% of first coffee grounds with the particle size larger than 150 micrometers, 5%-10% of second coffee grounds with the particle size larger than 150 micrometers and the balance fiber paper pulp. 80%-90% of second coffee grounds with a particle size of 75-150 [mu] m; and 5-10% of third coffee grounds with a particle size of less than 75 [ According to the pulp for paper pulp molding and the paper pulp molded product, coffee residue solid waste resource utilization is achieved, meanwhile, the product is endowed with natural color development, native texture and good buffering performance, synthetic dye does not need to be added or a complex mold does not need to be used, and the pulp for paper pulp molding and the paper pulp molded product have environment friendliness, aesthetic value and practical performance.

Description

Technical Field

[0001] This application relates to the field of pulp molding technology, and in particular to a pulp molding slurry, a pulp molding product, and a method for preparing the same. Background Technology

[0002] Pulp molded products have been widely used in the packaging industry due to their advantages such as biodegradability and environmental friendliness. However, there are still many technical problems that need to be solved in terms of appearance characteristics and material properties of pulp molded products, which limit their further promotion and application.

[0003] Currently, the color presentation of pulp molded products largely relies on synthetic dyes, especially fluorinated oil repellents and heavy metal dyes, which increase the risk of degradation and do not meet environmental protection requirements. Furthermore, the surface texture of the products generally relies on mold embossing or post-surface treatment, which not only increases mold costs and process complexity but also results in a strong mechanical feel to the molded texture, lacking a natural and original ecological texture. In addition, the cushioning and protective performance of pulp molded products mainly depends on the geometric design of the product, which not only increases mold development costs but also makes it difficult for the fiber substrate used in traditional products to meet the packaging cushioning needs of fragile and high-precision products due to its limited energy absorption efficiency. Summary of the Invention

[0004] In view of this, the main objective of this application is to provide a pulp for pulp molding, a pulp molded article and a method for preparing the same, in order to at least partially solve at least one of the aforementioned technical problems.

[0005] To achieve the above objectives, the technical solution of this application is as follows:

[0006] In one aspect of this application, a pulp for molding pulp is provided, comprising activated coffee grounds and fiber pulp, wherein the activated coffee grounds are obtained by degreasing, pyrolysis, and activation with an alkaline solution from coffee grounds raw material;

[0007] The activated coffee grounds comprise 100% by mass and include: 5% to 10% of the first type of coffee grounds with a particle size greater than 150 μm; 80% to 90% of the second type of coffee grounds with a particle size of 75 to 150 μm; and 5% to 10% of the third type of coffee grounds with a particle size less than 75 μm.

[0008] In some embodiments, the pulp for pulp molding is 100% by mass and includes: 5% to 10% activated coffee grounds; 40% to 45% first fiber pulp; and 40% to 45% second fiber pulp, wherein the fiber length of the first fiber pulp is greater than the fiber length of the second fiber pulp.

[0009] In some embodiments, the first fiber pulp includes at least one of softwood pulp and hemp pulp; the second fiber pulp includes at least one of hardwood pulp, bamboo pulp, and sugarcane pulp.

[0010] In some embodiments, the coffee grounds raw material includes: light roast coffee grounds roasted at a temperature of 150-180°C, and / or dark roast coffee grounds roasted at a temperature of 220-280°C.

[0011] In some embodiments, the pulp for molding further includes an in-situ color modifier, which is 100% by mass of the pulp for molding, and includes 1-3% calcium carbonate or 0.1-0.3% ferric sulfate.

[0012] In some embodiments, the activated coffee grounds have a porosity of 50-60% and a specific surface area of ​​500-600 m². 2 / g.

[0013] In some embodiments, the method for preparing activated coffee grounds includes:

[0014] Coffee grounds were extracted using an alcohol solution, and the coffee grounds were then degreased to obtain pretreated coffee grounds.

[0015] Pretreated coffee grounds are pyrolyzed in a vacuum environment of 290~310℃ to form microporous coffee grounds;

[0016] Microporous coffee grounds are activated using an alkaline solution at 230~260℃ to obtain activated coffee grounds, wherein the mass ratio of microporous coffee grounds to alkaline solution is 1:1~2.

[0017] In one aspect of this application, a method for preparing a pulp molded article is provided, comprising:

[0018] The above-mentioned pulp molding slurry is molded using a vacuum forming method to obtain a wet blank;

[0019] The wet preform is dried and hot-pressed to obtain a pulp molded article. In some embodiments, the drying method is gradient drying, which includes:

[0020] Dry at 30-50℃ for 20-30 minutes until the moisture content of the semi-finished product drops to 40-50%.

[0021] Dry at 60-80℃ for 10-20 minutes until the moisture content of the semi-finished product drops to 10-15%;

[0022] Dry at 30-40℃ until the semi-finished product is completely dry;

[0023] In some embodiments, the hot pressing treatment is performed at a temperature of 120~150°C, a pressure of 3~5 MPa, and a time of 3~5 min.

[0024] In one aspect of this application, a pulp molded article is provided, comprising fiber raw material and activated coffee grounds, wherein the activated coffee grounds are obtained by degreasing, pyrolysis, and alkaline activation of the coffee grounds raw material, with the activated coffee grounds accounting for 100% by mass. The coffee grounds raw material comprises: 5% to 10% of first coffee grounds with a particle size greater than 150 μm; 80% to 90% of second coffee grounds with a particle size of 75 to 150 μm; and 5% to 10% of third coffee grounds with a particle size less than 75 μm.

[0025] Compared with the prior art, the technical solution provided in this application has the following advantages: The pulp molding slurry of this application utilizes activated coffee grounds that have undergone degreasing, pyrolysis, and alkaline solution activation treatment. The mass percentage ratio of coffee grounds with different particle sizes in the raw material is controlled, realizing the resource utilization of coffee grounds solid waste. Furthermore, the different particle sizes of coffee grounds impart a natural, original texture and good structural density to the molded pulp products. Simultaneously, the porous structure formed by the pyrolyzed and activated coffee grounds provides good buffering and energy absorption performance for the products, ensuring the molding stability and performance of the products. This pulp molding slurry does not rely on artificial dyes, chemical additives, or complex molds, thus avoiding the degradation risks and environmental hazards associated with dyes and additives. It also reduces mold production costs and process complexity, enabling pulp molded products to possess both ecological aesthetic value and excellent buffering and protective capabilities. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with specific embodiments.

[0027] In the following detailed description, numerous specific details are set forth for ease of explanation to provide a thorough understanding of the embodiments of this application. However, it will be apparent that one or more embodiments may be implemented without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of this application.

[0028] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The term "comprising" as used herein indicates the presence of features, steps, or operations, but does not exclude the presence or addition of one or more other features.

[0029] When using expressions such as "at least one of A, B and C", they should generally be interpreted in accordance with the meaning that is commonly understood by those skilled in the art (e.g., "a system having at least one of A, B and C" should include, but is not limited to, a system having A alone, a system having B alone, a system having C alone, a system having A and B, a system having A and C, a system having B and C, and / or a system having A, B and C, etc.).

[0030] Existing pulp molded products have significant problems in appearance and performance: color realization relies on synthetic dyes, which increases the risk of degradation and violates environmentally friendly packaging requirements; texture construction relies on mold embossing or surface post-treatment, which has problems such as high cost, low yield, poor wear resistance, and lack of natural and friendly ecological aesthetics; cushioning performance relies on geometric structure design, which increases mold costs while limiting energy absorption efficiency and making it difficult to meet the needs of high-efficiency protection.

[0031] In realizing the concept of this application, it was discovered that the main components of coffee grounds include cellulose, hemicellulose, lignin, fatty acids, amino acids, polyphenols, caffeine, tannins, and minerals. Among these, cellulose serves as the core raw material for pulp molding products, giving coffee grounds good compatibility with pulp molding processes. The polyphenols it contains can serve as a natural coloring base, and the particle characteristics can be used to construct natural textures. If processed using specific techniques to form a rich porous structure, it can endow the material with good buffering and energy absorption capabilities.

[0032] Based on this, this application proposes a pulp for molding, molded pulp products, and a method for preparing the same. Coffee grounds are pretreated by roasting degree grading, particle size sieving, and defatting, followed by pyrolysis and activation treatment with specific parameters to construct a multi-level porous structure and enhance buffering performance. Subsequently, the treated coffee grounds are compounded with plant fibers, utilizing the chemical reaction of the coffee grounds' own components to achieve natural color development. Natural textures are formed by leveraging the differences in particle characteristics and fiber shrinkage rates, ultimately achieving an integrated pulp for molding that combines color, texture, and buffering function. The molded pulp products of this application do not rely on artificial dyes and complex mold carving, reducing production costs and aligning with environmental protection trends, providing a new path for performance upgrades and application expansion of molded pulp products.

[0033] According to one aspect of this application, a pulp molding slurry is provided, comprising activated coffee grounds and fiber pulp, wherein the activated coffee grounds are obtained by degreasing, pyrolysis, and activation with an alkaline solution from coffee grounds raw material, and the activated coffee grounds comprise 100% by mass: 5% to 10% of first coffee grounds with a particle size greater than 150 μm; 80% to 90% of second coffee grounds with a particle size of 75 to 150 μm; and 5% to 10% of third coffee grounds with a particle size less than 75 μm.

[0034] In some specific embodiments, the particle size of the first coffee grounds can be, for example, 151μm, 155μm, 160μm, 180μm, 200μm, etc., and its mass percentage can be, for example, 5%, 6%, 7%, 8%, 9%, 10%, etc. If the proportion of the first coffee grounds is too high, it will cause excessive protrusion on the surface of the pulp molded product and a loose structure, affecting the compressive strength; if the proportion is too low, it will be impossible to form a clear textured feel, making it difficult to achieve the desired textural effect.

[0035] In some specific embodiments, the particle size of the second coffee grounds can be, for example, 75μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, etc., and the mass percentage can be, for example, 80%, 82%, 85%, 88%, 90%, etc. This range of proportions ensures that the surface of the product exhibits a uniform and delicate rough texture, while ensuring the stability of the structural connection.

[0036] In some specific embodiments, the particle size of the third coffee grounds can be, for example, 74μm, 70μm, 65μm, 60μm, 50μm, 40μm, etc., and the mass percentage can be, for example, 5%, 6%, 7%, 8%, 9%, 10%, etc. An appropriate amount of small-particle-size third coffee grounds can fill the gaps between the first and second coffee grounds, preventing the formation of pores inside the pulp molded product. This enhances surface density and structural stability, while also complementing the texture of the first and second coffee grounds, thus optimizing both texture and structural strength.

[0037] In some specific embodiments, the first coffee grounds (particle size greater than 150 μm) do not require complex sieving and can be directly incorporated into the system by retaining the original particles in the coffee grounds raw material; the second coffee grounds (particle size 75~150 μm) are obtained by screening through a sieving process to ensure uniform particle size; the third coffee grounds (particle size less than 75 μm) can be obtained by separation through a hydrocyclone, utilizing the classification characteristics of the hydrocyclone to separate particles within the target particle size range.

[0038] According to an embodiment of this application, the pulp for pulp molding includes activated coffee grounds obtained by degreasing, pyrolysis, and alkaline solution activation of coffee grounds raw materials: the degreasing treatment removes oil and impurities from the coffee grounds to avoid the oil affecting the binding performance of the coffee grounds; the pyrolysis and alkaline solution activation promote the formation of a porous structure in the coffee grounds; the porous structure can dissipate energy through pore compression and deformation when subjected to impact, thereby enhancing the buffering and energy absorption performance of pulp molded products.

[0039] Further optimization of the appearance and structure of pulp molded products is achieved by synergistically utilizing three different coffee grounds of varying particle sizes. The first type of coffee grounds, with a relatively coarse particle size, naturally protrudes during molding, giving the product a clear and tangible natural texture. The second type of coffee grounds, with a relatively moderate particle size, serves as the main matrix, constructing a uniform and delicate rough surface base, ensuring the integrity and consistency of the texture. The third type of coffee grounds, with a relatively fine particle size, fills the pores between the first and second coffee grounds, preventing the formation of voids inside the pulp molded product and effectively enhancing surface density and structural stability. The specific ratio of these three types avoids problems such as loose structure and poor pulp flowability caused by a single particle size, while also being compatible with subsequent molding processes, providing a foundation for the molding and performance stability of pulp molded products.

[0040] According to an embodiment of this application, the pulp for pulp molding is 100% by mass and includes: 5% to 10% activated coffee grounds; 40% to 45% first fiber pulp; and 40% to 45% second fiber pulp, wherein the fiber length of the first fiber pulp is greater than the fiber length of the second fiber pulp.

[0041] Activated coffee grounds provide natural pigments, textured particles, and a multi-level porous structure, simultaneously endowing products with natural color, original texture, and excellent cushioning properties. Blending with pulp fibers of different lengths can adjust the tensile strength, formability, and structural integrity of the products. The three work together to make the pulp suitable for subsequent molding, drying, hot pressing, and other processes. The final products combine environmental friendliness, aesthetic value, and protective capabilities, achieving a comprehensive improvement in color, texture, cushioning properties, and structural strength.

[0042] In some specific embodiments, based on the total mass of the pulp used for pulp molding, the mass percentage of activated coffee grounds can be, for example, 5%, 6%, 7%, 8%, 9%, 10%, etc. An appropriate amount of activated coffee grounds can provide the pigment components and particle carriers required for natural color development and original texture. Within this range, the particle texture and smoothness of the prepared pulp molded products can achieve a good balance. Furthermore, the multi-level porous structure of activated coffee grounds can effectively improve buffering performance. If the proportion of activated coffee grounds is too high, it can easily lead to a decrease in fiber bonding strength, resulting in a loose structure and insufficient compressive strength in the pulp molded products, while also affecting the pulp flowability and molding stability.

[0043] Based on the total mass of the pulp used for pulp molding, the mass ratio of the first fiber pulp can be, for example, 40%, 41%, 42%, 43%, 44%, 45%, etc.; the mass ratio of the second fiber pulp can be, for example, 40%, 41%, 42%, 43%, 44%, 45%, etc. By combining the proportions of fiber pulp with different fiber lengths and activated coffee grounds, the fluidity, formability, shrinkage rate of the pulp, as well as the strength, texture, and cushioning effect of the final pulp molded products can be flexibly controlled to meet the packaging needs of different scenarios, while ensuring the biodegradability and environmental friendliness of the products.

[0044] According to embodiments of this application, the first fiber pulp includes at least one of softwood pulp and hemp pulp. The first fiber pulp has a relatively long fiber length, which can form a stable long fiber skeleton and provide tensile strength and structural integrity support for pulp molded articles.

[0045] The second fiber includes at least one of hardwood pulp, bamboo pulp, and sugarcane pulp. The second fiber pulp has a moderate fiber length, and the shrinkage rate of this type of fiber pulp can be stabilized at around 5%, which is reasonably different from the shrinkage rate of activated coffee grounds (about 8%). During the drying and hot pressing curing process, the difference in shrinkage rate will induce natural micro-cracks, further enriching the original texture of the product and making the texture more natural. At the same time, the moderately long fibers can fill the gaps between the first fiber pulp and the activated coffee grounds particles, improve the density of the pulp after molding, and prevent the formation of pores inside the pulp molded product. This ensures the surface smoothness of the product and enhances the structural stability.

[0046] According to embodiments of this application, the coffee grounds raw material includes: light roast coffee grounds roasted at a temperature of 150~180℃, and / or dark roast coffee grounds roasted at a temperature of 220~280℃.

[0047] In some specific embodiments, the roasting temperature of light roast coffee grounds can be 150℃, 160℃, 170℃, 180℃, etc.; the roasting temperature of dark roast coffee grounds can be 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, 280℃, etc.

[0048] According to embodiments of this application, the color of molded pulp products can be controlled by selecting coffee grounds of different roast levels. The natural brown hue of coffee grounds originates from the Maillard reaction and caramelization reaction that occur simultaneously during the roasting process: light-roasted coffee grounds (roasting temperature 150~180℃) can retain polyphenols in the coffee grounds to a greater extent (retention rate up to 0.39% chlorogenic acid equivalent). After subsequent hot pressing (hot pressing temperature 120~150℃), the polyphenols undergo an oxidation reaction, presenting a natural reddish-brown hue; dark-roasted coffee grounds (roasting temperature 220~280℃), on the other hand, produce a matte black hue because the sugars in the coffee grounds undergo deep carbonization to form dark brown polymers. This allows molded pulp products to obtain a uniform and long-lasting natural color without the addition of synthetic dyes.

[0049] According to embodiments of this application, the pulp for molding further includes an in-situ color-developing agent. The in-situ color-developing agent comprises, at 100% by mass of the pulp for molding, 1-3% calcium carbonate or 0.1-0.3% ferrous salt.

[0050] In some specific embodiments, ferrous sulfate can be used as the divalent ferric salt.

[0051] According to embodiments of this application, calcium carbonate can create an alkaline environment by adjusting the pH value of the slurry, providing suitable conditions for the oxidative polymerization of polyphenols. As an alkaline regulator, calcium carbonate can make the slurry system weakly alkaline (pH>8). During the subsequent hot pressing process, it can trigger the oxidative polymerization reaction of polyphenols (such as tannic acid and chlorogenic acid) in coffee grounds, generating stable brown pigments and giving the product a natural and uniform brown hue.

[0052] According to embodiments of this application, coffee grounds contain metallic components such as iron (approximately 0.12%) and magnesium (approximately 0.28%). Adjusting the water temperature to around 70°C during slurry preparation promotes the dissolution of these naturally present metal ions, which then complex with the polyphenols in the coffee grounds, forming a natural bluish-gray hue. Adding trace amounts of ferrous salts to the slurry allows the ferrous ions to complex with the polyphenols through ion diffusion, further enhancing the bluish-gray hue and creating a unique ink-wash texture, resulting in a more layered color in the finished product.

[0053] According to embodiments of this application, the porosity of the activated coffee grounds is 50%~60%, for example, it can be 50%, 52%, 55%, 58%, 60%, etc. Higher porosity allows for energy dissipation through pore compression and deformation upon impact, replacing the traditional method of relying on geometric structure design for energy absorption. This significantly improves the cushioning and energy absorption efficiency of the product, better meeting the packaging and protection needs of fragile, high-precision products. The specific surface area of ​​the activated coffee grounds is 500~600 m² / g. 2 / g, for example, can be 500 m 2 / g、520 m 2 / g、550 m 2 / g、580 m 2 / g、600 m 2 / g etc. The larger specific surface area increases the contact area between activated coffee grounds and fiber pulp, forming stronger hydrogen bonds and mechanical entanglement, thus improving the uniformity of pulp dispersion. Furthermore, the abundant porosity reduces the overall density of the material, achieving lightweighting while maintaining structural strength, reducing the amount of packaging material used, and meeting environmental protection and low-cost requirements.

[0054] According to an embodiment of this application, the method for preparing activated coffee grounds in pulp molding slurry includes the following steps: extracting coffee grounds raw material using an alcohol solution, degreasing the coffee grounds raw material to obtain pretreated coffee grounds; pyrolyzing the pretreated coffee grounds under a vacuum environment of 290~310℃ to form microporous coffee grounds; and activating the microporous coffee grounds using an alkaline solution at 230~260℃ to obtain activated coffee grounds, wherein the mass ratio of microporous coffee grounds to alkaline solution is 1:1~2.

[0055] In some specific embodiments, the alcohol solution can be, for example, an ethanol solution. The coffee grounds raw material is extracted with an alcohol solution to degrease the coffee grounds raw material, remove most of the oil components in the coffee grounds raw material, and avoid these oils from hindering the bonding of coffee grounds with coffee grounds and coffee grounds with fiber pulp in subsequent processes, thus laying the foundation for uniform pulp dispersion and stable product structure.

[0056] In some specific embodiments, the pyrolysis temperature can be, for example, 290℃, 295℃, 300℃, 305℃, 310℃, etc. Pyrolysis promotes the full evaporation of moisture and volatiles in the pretreated coffee grounds, forming coffee grounds with a microporous structure. At the same time, this temperature range can control the weight loss rate of the cellulose skeleton to be less than 15%, avoiding excessive decomposition of cellulose that could lead to structural collapse, and ensuring the structural foundation required for the bonding of coffee grounds and fiber pulp.

[0057] In some specific embodiments, the activation temperature can be, for example, 230℃, 235℃, 240℃, 245℃, 250℃, 255℃, 260℃, etc.; the mass ratio of microporous coffee grounds to alkaline solution can be, for example, 1:1, 1:1.2, 1:1.5, 1:1.8, 1:2, etc.; the alkaline solution can be, for example, potassium hydroxide (KOH) solution. Activating coffee grounds with an alkaline solution promotes the oxidation and corrosion of carbon in the coffee grounds through the alkaline environment, cleans impurities remaining from the pyrolysis process, unclogs pores, and further constructs a hierarchical pore network, ultimately increasing the porosity of the activated coffee grounds to 50%~60% and the specific surface area to 500~600 m². 2 / g provides structural support for the product's buffering and energy absorption properties.

[0058] The preparation process of activated coffee grounds controls the defatting extraction, pyrolysis and activation reaction conditions to effectively build buffer pores while maximizing the retention of polyphenols (such as tannic acid and chlorogenic acid), iron, magnesium and other natural metal ions in the coffee grounds. These components can not only serve as the material basis for natural color development in the subsequent hot pressing stage, but also work synergistically with activated coffee grounds of different particle sizes to assist in the formation of original textures, thus achieving a balance between optimizing the buffer structure and preserving the functional components of color development and texture.

[0059] In another aspect of this application, a method for preparing a pulp molded article is provided, comprising the following steps.

[0060] The above-mentioned pulp molding slurry is molded using a vacuum forming method to obtain a wet blank.

[0061] Furthermore, the wet blank is dried and hot-pressed to obtain pulp molded products.

[0062] According to embodiments of this application, the vacuum forming method utilizes vacuum suction and demolding pressure to quickly conform the pulp to the mold contour. Subsequently, through drying and dehydration, the activated coffee grounds particles in the pulp naturally bulge as moisture evaporates, forming a tactile texture. Hot pressing further evaporates residual moisture and fixes the shape of the molded pulp product, while simultaneously triggering the oxidative polymerization reaction of polyphenols in the activated coffee grounds, promoting color development. The entire preparation method is simple, requiring no synthetic dyes or chemical additives, and eliminating the need for complex mold carving or surface post-treatment processes. It can be directly adapted for industrial mass production, reducing process complexity and production costs. Furthermore, through the synergy of process and material properties, it simultaneously achieves the integrated construction of natural color development, original texture, and good cushioning performance in molded pulp products, aligning with environmentally friendly development trends.

[0063] For example, a reciprocating lifting vacuum forming machine can be used, with a suction and filtration pressure of -0.08MPa; the concentration of the pulp for pulp molding can be diluted to a 0.5~1% suspension to ensure fluidity; and the moisture content of the wet blank can be 75~80%.

[0064] In some specific embodiments, the pulp for molding comprises activated coffee grounds, a first fiber pulp, and a second fiber pulp. The activated coffee grounds, the first fiber pulp, and the second fiber pulp can be mixed in a high-speed mixer at 2000 rpm for 30 minutes to obtain the pulp for molding. This ensures that the activated coffee grounds and fiber pulp are evenly dispersed. During the subsequent drying process of the wet preform, due to the difference in shrinkage rates between the activated coffee grounds and the fiber pulp (e.g., bamboo pulp shrinkage rate 5%, activated coffee grounds shrinkage rate 8%), natural microcracks (approximately 50-100 μm wide) will form during dehydration, creating a rich, realistic, and tactile original texture.

[0065] According to embodiments of this application, the drying method is gradient drying. By controlling the temperature and time in stages, it effectively prevents the surface of the pulp molded product from forming a skin too quickly, thus hindering the drainage of internal moisture and significantly reducing the risk of defects such as cracking and deformation. Simultaneously, it ensures the formation of the product's texture and the stability of its performance. Gradient drying includes the following stages.

[0066] The first stage involves drying at 30-50℃ for 20-30 minutes until the moisture content of the wet blank drops to 40-50%. This stage uses a gentle temperature environment to allow moisture to migrate slowly, preventing the surface of the wet blank from forming a closed hard shell due to rapid water loss. This not only provides a channel for the smooth drainage of moisture but also initially fixes the structure of the product, reducing cracking problems caused by uneven internal and external shrinkage during subsequent heating.

[0067] The second stage: Dry at 60~80℃ for 10~20 minutes until the moisture content of the wet blank drops to 10~15%. At this stage, the wet blank has a certain structural stability. By moderately raising the temperature to accelerate the evaporation of the internal bound water, the dehydration efficiency is greatly improved while ensuring the integrity of the product structure, and the overall drying cycle is shortened. At the same time, this temperature range can promote the initial strengthening of the interfacial bonding force between coffee grounds and fibers.

[0068] The third stage: drying at 30~40℃ until the wet blank is completely dry. This stage uses low-temperature constant temperature treatment to ensure that the residual moisture inside the product is evenly diffused and fully discharged, avoiding structural loosening or uneven performance caused by localized moisture residue, and ultimately bringing the moisture content of the product to a stable state.

[0069] In some specific embodiments, the temperature of the first stage of drying can be, for example, 30℃, 35℃, 40℃, 45℃, 50℃, etc., and the time can be, for example, 20 minutes, 22 minutes, 25 minutes, 28 minutes, 30 minutes, etc.; the temperature of the second stage of drying can be, for example, 60℃, 65℃, 70℃, 75℃, 80℃, etc., and the time can be, for example, 10 minutes, 12 minutes, 15 minutes, 18 minutes, 20 minutes; the temperature of the third stage of drying can be, for example, 30℃, 32℃, 35℃, 38℃, 40℃, etc. During actual drying, the temperature and time parameters for each drying stage can be selected within the corresponding range according to the moisture content and thickness of the wet preform to ensure that the moisture content is steadily reduced to the target range and to ensure the stable performance of the pulp molded products.

[0070] According to the embodiments of this application, the temperature of the hot pressing treatment is 120~150℃, for example, 120℃, 130℃, 140℃, 150℃, etc.; the pressure is 3~5MPa, for example, 3 MPa, 3.5 MPa, 4 MPa, 4.5 MPa, 5 MPa, etc.; and the time is 3~5min, for example, 3 min, 4 min, 5 min, etc. The high-temperature environment during hot pressing further evaporates residual moisture in the wet preform. Simultaneously, the pressure compacts the bond between the activated coffee grounds and the fiber pulp, fixing the shape of the molded pulp product and preventing deformation during subsequent use, thus improving dimensional stability. Furthermore, the 120-150℃ temperature range triggers the oxidative polymerization of polyphenols in the activated coffee grounds, promoting the stable formation of natural pigments. It can also be used in conjunction with in-situ color-developing agents to enrich the product's color. Simultaneously, this temperature and pressure environment further enhances the product's structural density and mechanical strength, synergistically strengthening the porous structure of the activated coffee grounds and consolidating the cushioning and energy-absorbing properties of the molded pulp product. Ultimately, this achieves simultaneous optimization of product shape fixation, moisture removal, color development, and cushioning performance.

[0071] In another aspect of this application, a pulp molded article is provided, comprising fiber raw material and activated coffee grounds. Exemplarily, the aforementioned pulp molding slurry can be molded using a vacuum forming method to obtain a wet preform, which is then dried and hot-pressed to obtain the final product. The activated coffee grounds are obtained from coffee grounds raw material through degreasing, pyrolysis, and activation with an alkaline solution. The activated coffee grounds comprise 100% by mass and include: 5%–10% of first coffee grounds with a particle size greater than 150 μm; 80%–90% of second coffee grounds with a particle size of 75–150 μm; and 5%–10% of third coffee grounds with a particle size less than 75 μm.

[0072] According to embodiments of this application, the pulp molded product uses activated coffee grounds of different particle sizes, achieving functional synergy through proportioning. The first type of coffee grounds, with a particle size greater than 150 μm, naturally protrudes during the drying and dehydration process, forming a uniformly rough base with the second type of coffee grounds (75-150 μm) to create a natural tactile texture. The third type of coffee grounds, with a particle size less than 75 μm, fills the pores between the particles, enhancing the surface density and structural stability of the product, avoiding the mechanical feel of traditional mold embossing or surface post-treatment. The porous structure formed by the activated coffee grounds after degreasing, pyrolysis, and alkaline solution activation can efficiently dissipate energy through pore compression and deformation upon impact, significantly improving buffering and energy absorption performance, meeting protection requirements without relying on complex geometric designs. Furthermore, pulp molded products rely on the natural components of coffee grounds, such as polyphenols and metal ions, to achieve natural colors without the addition of synthetic dyes. By selectively using in-situ color modifiers, diverse colors and textures can be customized, combining ecological aesthetic value with environmental friendliness. Moreover, the synergistic process of vacuum forming, gradient drying, and hot pressing ensures molding precision and dimensional stability. The raw materials used are biodegradable, and the preparation process does not require complex equipment modifications, making it directly suitable for industrial mass production. While reducing process complexity and production costs, it effectively solves the problems of traditional pulp molded products, such as environmentally unfriendly appearance, mechanical texture, and insufficient cushioning performance.

[0073] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with specific embodiments. Unless otherwise specified, all methods described in the embodiments are conventional and can be performed according to the techniques or conditions described in the literature or the product manual.

[0074] Example 1

[0075] This application provides a pulp molded article. The pulp used for pulp molding comprises 8% activated coffee grounds, 46% softwood pulp, and 46% bamboo pulp, with a pulp mass percentage of 100%.

[0076] The method for preparing activated coffee grounds includes: extracting coffee grounds raw materials with ethanol solution to obtain pretreated coffee grounds; pyrolyzing the pretreated coffee grounds in a vacuum environment (vacuum degree 0.1MPa) at 300℃ for 30 min to form microporous coffee grounds; and activating the microporous coffee grounds with potassium hydroxide solution at 250℃ for 1 h to obtain activated coffee grounds, wherein the mass ratio of microporous coffee grounds to potassium hydroxide solution is 1:2.

[0077] The activated coffee grounds comprise 100% by mass, including: 10% of the first type of coffee grounds with a particle size greater than 150 μm; 80% of the second type of coffee grounds with a particle size of 75-150 μm; and 10% of the third type of coffee grounds with a particle size less than 75 μm.

[0078] The preparation method of the pulp molded product includes: using a reciprocating lifting vacuum forming machine (suction and filtration pressure -0.08MPa), the pulp molding slurry is molded by vacuum forming to obtain a wet blank with a moisture content of 75%; the wet blank is subjected to gradient drying and hot pressing treatment to obtain the pulp molded product.

[0079] The gradient drying conditions are as follows: dry at 50℃ for 30 minutes until the moisture content of the wet blank drops to 50%; dry at 80℃ for 20 minutes until the moisture content of the wet blank drops to 15%; and dry at 30~40℃ until the wet blank is completely dry.

[0080] The hot pressing conditions are: 40℃, 3MPa pressure for 5 minutes.

[0081] Comparative Example 1

[0082] This application provides a comparative example of a molded pulp article. The pulp used for molding comprises 50% softwood pulp and 50% bamboo pulp, with a pulp mass percentage of 100%. This molded pulp article is prepared using the same method as in Example 1.

[0083] The cushioning performance of the pulp molded products of Example 1 and Comparative Example 1 was tested. Dynamic impact tests were conducted to obtain the force-displacement curves of the pulp molded products. The area under the force-displacement curve was first calculated to obtain the total absorbed energy (J) of the pulp molded products. Then, the total absorbed energy was divided by the deformation volume of the sample (m³). 3 The energy absorption value of the pulp molded product was obtained. The energy absorption value of the pulp molded product in Comparative Example 1 was 2.3 kJ / m³. 3 In Example 1, the energy absorption value of the molded pulp product was 3.2 kJ / m³. 3 Compared to Comparative Example 1, which did not contain activated coffee grounds, the energy absorption value of the pulp molded product of Example 1 of this application is increased by approximately 40%. This is because the activated coffee grounds, after degreasing, pyrolysis, and alkaline solution activation, retain the cellulose skeleton of the coffee grounds raw material and ensure its interfacial bonding with pulp fibers, while constructing a porous structure with a large specific surface area. After being compounded with softwood pulp and bamboo pulp, the activated coffee grounds can synergistically form a more stable three-dimensional network structure with the fiber pulp. When subjected to external impact, this structure can more efficiently absorb and dissipate impact energy through pore compression, deformation, and the synergistic effect of the fiber network, thereby improving the buffering energy absorption performance of the pulp molded product. The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above descriptions are merely specific embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A pulp molding paste, characterized in that, The pulp for molding comprises activated coffee grounds and fiber pulp, wherein, The activated coffee grounds are obtained by degreasing, pyrolysis, and activation with an alkaline solution from coffee ground raw materials. The activated coffee grounds comprise 100% by mass, and the activated coffee grounds include: 5%~10% of the first coffee grounds have a particle size greater than 150μm; Second coffee grounds with a particle size of 75~150μm account for 80%~90%; The third type of coffee grounds, with a particle size of less than 75μm, accounts for 5% to 10%.

2. The pulp molding slurry according to claim 1, characterized in that, The pulp molding slurry comprises 100% by mass, and includes: Activated coffee grounds: 5%~10%; First fiber pulp 40%-45%; The second fiber pulp comprises 40%-45%, wherein the fiber length of the first fiber pulp is greater than the fiber length of the second fiber pulp.

3. The pulp molding slurry according to claim 2, characterized in that, The first fiber pulp includes at least one of softwood pulp and hemp pulp; The second fiber pulp includes at least one of hardwood pulp, bamboo pulp, and sugarcane pulp.

4. The pulp molding slurry according to claim 1, characterized in that, The coffee grounds raw material includes: Lightly roasted coffee grounds at a roasting temperature of 150-180℃, and / or, Dark roast coffee grounds roasted at 220~280℃.

5. The pulp molding slurry according to claim 1 or 2, characterized in that, The pulp molding slurry also includes: an in-situ color development regulator; With the pulp for molding as 100% by mass, the in-situ color-developing modifier comprises: 1-3% calcium carbonate or 0.1-0.3% ferrous sulfate.

6. The pulp molding slurry according to claim 1, characterized in that, The activated coffee grounds have a porosity of 50-60% and a specific surface area of ​​500-600 m². 2 / g.

7. The pulp molding slurry according to claim 1, characterized in that, The method for preparing the activated coffee grounds includes: The coffee grounds were extracted with an alcohol solution and then degreased to obtain pretreated coffee grounds. The pretreated coffee grounds are pyrolyzed in a vacuum environment of 290~310℃ to form microporous coffee grounds. The microporous coffee grounds are activated using an alkaline solution at 230~260℃ to obtain activated coffee grounds, wherein the mass ratio of the microporous coffee grounds to the alkaline solution is 1:1~2.

8. A method for preparing a pulp molded article, characterized in that, The preparation method includes: The pulp molding slurry described in any one of claims 1 to 7 is molded using a vacuum forming method to obtain a wet blank; The wet blank is dried and hot-pressed to obtain a pulp molded product.

9. The preparation method according to claim 8, characterized in that, The drying method is gradient drying, which includes: Dry at 30-50°C for 20-30 minutes until the moisture content of the wet blank drops to 40-50%. Dry at 60-80℃ for 10-20 minutes until the moisture content of the wet blank drops to 10-15%; Dry the wet blank at 30~40℃ until it is completely dry; The hot pressing process is performed at a temperature of 120-150°C, a pressure of 3-5 MPa, and a time of 3-5 min.

10. A pulp molded article, characterized in that, The pulp molded product comprises fiber raw material and activated coffee grounds, wherein the activated coffee grounds are obtained by degreasing, pyrolysis, and activation with an alkaline solution from the coffee grounds raw material. The activated coffee grounds comprise 100% by mass, and the activated coffee grounds include: 5%~10% of the first coffee grounds have a particle size greater than 150μm; Second coffee grounds with a particle size of 75~150μm account for 80%~90%; The third type of coffee grounds, with a particle size of less than 75μm, accounts for 5% to 10%.