Process for preparing biodegradable master batch in cooperation with biological residue

Abstract

The application relates to the technical field of biodegradable materials, and discloses a process for preparing biodegradable master batches in cooperation with biological residues, which comprises micronized detoxification biomass base material, solid-phase eutectic crosslinking precursors, beeswax and soybean lecithin; the precursors are composed of sorbitol crystal powder and anhydrous citric acid powder; the base material is premixed with the precursors at normal temperature, the beeswax and the lecithin are added, mechanical friction is generated by using a high-speed mixer to make the material self-heat to the melting point of the beeswax, and the beeswax is coated on the surface of the powder; then the material is continuously fed into a ring die granulator, local transient friction heat generated by extrusion and passing through the die is used to promote in-situ esterification crosslinking reaction of the precursors and the base material, and the material is air-cooled and solidified after being cut off from the die. The scheme uses a transient heating mechanism to complete internal crosslinking and external hydrophobic coating of the base material, improves the tensile bearing capacity and water resistance of the material, and reduces the thermal degradation of natural macromolecules.

Description

Technical Field

[0001] This invention relates to the field of biodegradable materials technology, specifically a process for the co-preparation of biodegradable masterbatch from biological residues. Background Technology

[0002] Currently, biodegradable materials based on natural biomass such as starch and plant pulp residues are gradually being used in disposable tableware and packaging. However, unmodified natural biomass materials have weak intermolecular forces after molding, resulting in insufficient mechanical load-bearing capacity. Furthermore, natural biomass materials contain numerous hydrophilic groups, making them susceptible to water penetration when exposed to hot water or high humidity, causing swelling, softening, and structural disintegration, leading to poor resistance to hot water hydrolysis.

[0003] To improve the mechanical strength and water resistance of the aforementioned materials, conventional modification methods typically involve the introduction of external crosslinking agents for blending. However, traditional crosslinking modification processes often involve complex chemical reactions under relatively harsh conditions, and unreacted small chemical molecules are easily left in the matrix. This alters the original natural properties of the material as a pure biomass to some extent and increases the uncertainty in the complete degradation process.

[0004] In the molding and processing stage, existing technologies tend to employ continuous high-temperature, high-shear thermal melting and mixing processes. Natural biomass polymers are highly sensitive to heat accumulation and intense mechanical shearing. Under continuous high-temperature, high-shear processing conditions, the main chain of biomass macromolecules is prone to breakage and thermal degradation. This thermodynamic degradation during processing not only weakens the basic skeletal strength of the material itself but also easily leads to yellowing and charring, making it difficult to achieve a balance between cross-linking reactions and granulation under mild and controllable physical conditions. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a process for the co-preparation of biodegradable masterbatches from bio-based residues. This process solves the problems of low mechanical load-bearing capacity and poor resistance to hot water hydrolysis in existing pure biomass biodegradable material molded parts, as well as the tendency for conventional long-term high-temperature and high-shear processing to cause thermal degradation of the natural macromolecular backbone.

[0006] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a method for the co-preparation of biodegradable masterbatch from biological residue, employing the following technical solution: A biodegradable masterbatch co-prepared from bio-residue is made from raw materials comprising the following parts by weight: 100.0 parts of micronized detoxified biomass substrate; 8.0-14.5 parts of solid-phase eutectic crosslinking precursor; 3.0-5.0 parts beeswax; Soy lecithin 1.0-1.5 parts; The solid-phase eutectic crosslinking precursor is composed of sorbitol crystalline powder and anhydrous citric acid powder.

[0007] By adopting the above technical solution, this scheme selects sorbitol and anhydrous citric acid to form a solid-phase eutectic crosslinking precursor, wherein sorbitol serves as a polyol and anhydrous citric acid provides a multi-carboxyl structure. When these two powders are physically mixed and heated, they tend to form a deep eutectic system, thereby lowering the phase transition temperature of the original components. In the subsequent pressurized and heated processing environment, the free carboxyl groups in anhydrous citric acid, together with the free hydroxyl groups on the molecular chains of the micronized detoxified biomass matrix and the hydroxyl groups of sorbitol itself, undergo an in-situ esterification reaction.

[0008] During esterification and crosslinking, the free hydroxyl groups of the matrix and the free carboxyl groups of citric acid lose water molecules under heat and dehydration, generating polymer macromolecules linked by ester bonds. This constructs a crosslinked structure with three-dimensional network characteristics within the biomass matrix, which helps to improve the tensile strength and load-bearing capacity of the overall system. When the added beeswax is heated and melted, it penetrates and adheres to the surface and internal pores of the crosslinked biomass particles through the emulsification and dispersion of soybean lecithin.

[0009] The cross-linked structure itself reduces the water penetration channels inside the matrix. Combined with the hydrophobic layer formed by beeswax, it slows down the process of external water intrusion into the matrix, maintains the morphological stability of the final molded part in a hot water environment, and improves its anti-disintegration performance.

[0010] Preferably, the raw materials are present in the following proportions by weight: 100.0 parts of micronized detoxified biomass substrate; 11.0 parts of solid-phase eutectic crosslinking precursor; 4.0 parts beeswax; 1.2 parts soybean lecithin.

[0011] By adopting the above technical solution and using this composition ratio, the solid-phase eutectic crosslinking precursor can provide a more suitable crosslinking site density, avoiding material embrittlement caused by excessive crosslinking agent or insufficient crosslinking causing substandard mechanical strength. The combination of beeswax and soybean lecithin in this ratio helps maintain the uniformity of the hydrophobic coating thickness and reduces the tendency of precipitation during service life.

[0012] Preferably, in the solid-phase eutectic crosslinking precursor, the sorbitol crystalline powder comprises 6.0-10.0 parts by weight, and the anhydrous citric acid powder comprises 2.0-4.5 parts by weight.

[0013] By adopting the above technical solution, the ratio of sorbitol to anhydrous citric acid makes the composition of the mixture closer to the deep eutectic point, which helps to reduce the temperature at which the system undergoes a phase transition. This allows the system to be transformed into a eutectic liquid phase with certain fluidity and reactivity within a lower heat processing temperature range, thus expanding the homogeneous contact area for subsequent in-situ esterification reactions.

[0014] Preferably, the micronized detoxified biomass base material is a powder obtained by dehydrating and pulverizing fresh potato pulp and then subjecting it to combined microwave and ozone sterilization treatment; The free moisture content of the micronized detoxified biomass matrix is ​​8-15 wt%, and the particle size is 600-1000 mesh.

[0015] By adopting the above technical solution, 8-15 wt% of free water is retained, which can act as a natural plasticizing component and heat conduction medium during the hot processing stage, helping the eutectic precursor to melt and disperse. Subsequently, some of it is heated and vaporized during granulation and extrusion. Using powder with a fineness of 600-1000 mesh increases the specific surface area of ​​the material, correspondingly shortens the diffusion distance of the reactants, and is conducive to improving the cross-linking reaction and transformation of the solid-phase interface.

[0016] Secondly, the present invention provides a process for preparing biodegradable masterbatch by co-preparing bio-residue, which adopts the following technical solution: A process for preparing biodegradable masterbatch from bio-residue includes the following steps: Micronized detoxified biomass matrix and solid-phase eutectic crosslinking precursor are added to a high-speed mixer and mechanically mixed at a spindle speed of 200-400 rpm for 3-8 minutes at room temperature to obtain a preliminary mixture. Add beeswax and soybean lecithin to the high-speed mixer and mix them with the initial mixture. Adjust the high-speed mixer to high-speed shear mode and increase the speed to 1200-2000 rpm. The mixture heats up to 65-75°C by frictional work. After running at a constant temperature for 3-5 minutes, the mixture is discharged to obtain premixed powder. The premixed powder is continuously fed into a ring die granulator, and the friction temperature of the material during extrusion is controlled at 85-100°C. After compression molding, the material is cut off and cooled to 25°C to obtain the biodegradable masterbatch.

[0017] By adopting the above technical solution, a biodegradable masterbatch with uniform material dispersion and in-situ cross-linked structure is obtained through a stepped temperature control response mechanism and a ring die physical granulation method relying on local friction. During process execution, the reaction precursor and biomass matrix are initially mechanically mixed at room temperature. This operation does not involve external heat input, keeping the material in a relatively dry powder dispersion state to prevent premature phase change and adhesion of the solid-phase eutectic cross-linking precursor upon heating, thus facilitating the precursor's penetration into the interparticle gaps of the biomass powder.

[0018] Subsequently, the speed of the mixer spindle is increased, and the friction between the blades and the material, as well as between the materials themselves, causes the internal temperature of the system to rise to 65-75°C. This heated environment causes the beeswax to melt and, with the emulsification assistance of soybean lecithin, wets and adheres to the surface of the biomass particles. At the same time, the eutectic precursor softens at this temperature and initially adheres to the surface of the matrix powder, resulting in a thermodynamic physical response, but not yet triggering a large amount of deep chemical cross-linking.

[0019] After the premixed material enters the ring die pellet mill, the forced mechanical extrusion between the pressure roller and the die hole generates localized transient frictional heat, causing the material temperature to jump to 85-100℃ at the moment of passing through the die. Under this instantaneous temperature and pressure field, most of the eutectic precursor is transformed into a liquid phase with high reactivity, penetrating deep into the pores of the biomass powder and initiating a substantial esterification and cross-linking reaction.

[0020] By relying on the mechanism of cross-linking triggered by local transient heating, the risk of thermodynamic degradation of natural biomass macromolecules due to prolonged exposure to overall high temperature environment is reduced, and the backbone structure of the cross-linked matrix is ​​better maintained.

[0021] Preferably, the preparation of the micronized detoxified biomass base material includes the following steps: Freshly peeled and washed potatoes are cut into chunks and dried at 60–80°C until the free moisture content drops to 8–15 wt%, resulting in dried block material. The dried block material is crushed into fragments with an average particle size of 3-8 mm using a mechanical crusher; The fragments are fed into an airflow micronizer for grinding and classification, and fine powder with a particle size of 600-1000 mesh is collected. The fine powder is sent into a microwave and ozone combined disinfection chamber for 15-30 minutes for detoxification and sterilization to obtain the micronized detoxified biomass matrix.

[0022] By employing the above technical solutions, biomass raw materials are dehydrated to a specific moisture content, and a two-stage pulverization process combining mechanical coarse crushing and airflow micro-pulverization ensures the concentration of powder particle size distribution. The combined microwave and ozone disinfection method can deeply inactivate and oxidize harmful free metabolites remaining in the matrix, helping to improve the safety of the product in application.

[0023] Preferably, the pretreatment of the solid-phase eutectic crosslinking precursor before it is added to the high-speed mixer includes the following steps: Weigh out sorbitol crystalline powder and anhydrous citric acid powder and put them into a three-dimensional motion mixer. Mix and stir at 30 rpm for 15-20 minutes at room temperature. Seal and store in the dark for later use.

[0024] By adopting the above technical solution, a three-dimensional motion mixer is used to perform physical interleaving mixing in an environment with low speed and weak mechanical shear, which reduces the local heating effect of powder caused by friction work, prevents the eutectic components from softening or agglomerating too early, and maintains the dry powder morphology of the precursor dispersed distribution.

[0025] Preferably, beeswax and soybean lecithin are added to the high-speed mixer, the high-speed mixer is adjusted to high-speed shear mode, the external heat source is cut off, and self-heating is achieved by mechanical friction.

[0026] By adopting the above technical solution, compared with the external jacket heating method, the self-heating achieved by mechanical friction is mainly provided by the heat source generated by the collision and friction between material particles. This heating method makes the temperature distribution in the system more uniform and reduces the risk of coking or performance degradation of the material surface caused by excessively high local temperature on the external contact surface.

[0027] Preferably, the premixed powder is continuously fed into the feeding mechanism of the ring die granulator. Under the mechanical extrusion and shearing action of the pressure roller and the ring die, the powder is heated by friction and passes through the die. After being cut by a rotary cutter, it enters the air-cooled screening system for cooling.

[0028] By adopting the above technical solution, the transient high temperature and high pressure facilitated esterification crosslinking and molding solidification. The subsequent air-cooled screening system cooled the material after it was demolded. The rapid cooling process could inhibit the continuous occurrence of crosslinking reaction and prevent the material from becoming brittle due to excessive crosslinking. At the same time, it quickly cured the outer beeswax coating layer and maintained the stability of the matrix's internal structure.

[0029] Preferably, a vacuum weighing feeder or a closed metering system is used to transport the micronized detoxified biomass substrate into the high-speed mixer.

[0030] By adopting the above technical solution, the closed feeding method reduces dust dispersion and material loss during the transportation of ultrafine biomass powder, prevents external environmental moisture from invading the dried and detoxified base material, and helps maintain the stability and accuracy of the mixing ratio of each processing batch.

[0031] This invention provides a process for the co-preparation of biodegradable masterbatch from bio-based residues. It has the following beneficial effects: 1. This invention modifies biomass matrix by using a solid-phase eutectic crosslinking precursor composed of sorbitol and anhydrous citric acid. The solid-phase eutectic crosslinking precursor is easy to form a deep eutectic system under physical mixing conditions, so it can be transformed into a reactive eutectic liquid phase at a lower processing temperature and undergo in-situ esterification crosslinking with free hydroxyl groups on the biomass matrix. The crosslinking reaction under mild conditions constructs a network structure connected by ester bonds inside the matrix, which improves the tensile load-bearing capacity and structural density of the final molded part.

[0032] 2. In this invention, the material generates localized instantaneous high temperature by being forced between the pressure roller and the die hole during the molding process, thereby triggering the internal esterification and cross-linking reaction. The transient heating method avoids the main chain breakage and charring of biomass polymer chains due to prolonged exposure to high temperature and strong shear environment, thus better maintaining the integrity of the polymer skeleton of the material itself and slowing down the tendency of thermal degradation.

[0033] 3. The present invention combines the rapid cooling of the air-cooling system after demolding, so that the molten beeswax can be quickly solidified on the surface and in the pores of the biomass particles to form a uniform water-blocking layer. This layer works in conjunction with the cross-linked network inside the matrix to limit the rapid penetration of external moisture and improve the anti-swelling and anti-disintegration ability of the molded parts when in contact with hot water or high humidity environments. Attached Figure Description

[0034] Figure 1 This is a differential scanning calorimetry (DSC) full spectrum of the premixed powder and single-component precursor of Example 1 of the present invention; Figure 2 Fourier transform infrared spectra of intermediate materials and molded parts in Embodiment 1 of the present invention; Figure 3 The tensile stress-strain curves of Embodiment 1 and some comparative molded parts of the present invention are shown. Figure 4 The graph shows the dynamic change in mass retention rate of the molded parts of Embodiment 1 and some comparative examples of the present invention during the constant temperature water bath immersion process. Detailed Implementation

[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] It should be noted that in the following embodiments, the weight proportions of each raw material are converted proportionally using kilograms (kg) as the basic unit of measurement in actual production.

[0037] Preparation Example 1: This preparation example provides a method for preparing micronized detoxified biomass-based material, including the following steps: Freshly peeled and washed potatoes were cut into chunks and placed in a hot air circulating drying system to dry and dehydrate at 70°C until the free moisture content of the material dropped to 12 wt%. Dry lumpy materials are crushed into fragments with an average particle size of 5mm using a mechanical crusher; The above-mentioned fragments are fed into an airflow micronizer for grinding and classification, and fine powder with a particle size of 800 mesh is collected. The collected fine powder is sent into a microwave and ozone combined disinfection chamber for 20 minutes to detoxify and sterilize aflatoxin, solanine, etc., and then transported by airflow to a sealed silo for storage and future use.

[0038] Preparation Example 2: This preparation example provides a method for preparing micronized detoxified biomass-based material, including the following steps: Freshly peeled and washed potatoes were cut into chunks and placed in a hot air circulating drying system to dry and dehydrate at 60°C until the free moisture content of the material dropped to 15 wt%. Dry lumpy materials are crushed into fragments with an average particle size of 8mm using a mechanical crusher; The above-mentioned fragments are fed into an airflow micronizer for grinding and classification, and fine powder with a particle size of 600 mesh is collected. The collected fine powder is sent into a microwave and ozone combined disinfection chamber for 15 minutes to detoxify and sterilize aflatoxin, solanine, etc., and then transported by airflow to a sealed silo for storage and future use.

[0039] Preparation Example 3: This preparation example provides a method for preparing micronized detoxified biomass-based material, including the following steps: Freshly peeled and washed potatoes were cut into chunks and placed in a hot air circulating drying system to dry and dehydrate at 80°C until the free moisture content of the material dropped to 8 wt%. Dry lumpy materials are crushed into fragments with an average particle size of 3mm using a mechanical crusher; The above-mentioned fragments are fed into an airflow micronizer for grinding and classification, and fine powder with a particle size of 1000 mesh is collected. The collected fine powder is sent into a microwave and ozone combined disinfection chamber for 30 minutes to detoxify and sterilize aflatoxin, solanine, etc., and then transported by airflow to a sealed silo for storage and future use.

[0040] Preparation Example 4: This preparation example provides a method for preparing a solid-phase eutectic crosslinking precursor, including the following steps: Weigh 8.0 kg of sorbitol crystalline powder and 3.0 kg of anhydrous citric acid powder, and put the two components into a three-dimensional motion mixer. Mix and stir at 30 rpm for 15 minutes at room temperature. After discharge, seal and store in a vacuum aluminum foil bag in the dark for later use.

[0041] Preparation Example 5: This preparation example provides a method for preparing a solid-phase eutectic crosslinking precursor, including the following steps: Weigh 6.0 kg of sorbitol crystalline powder and 4.5 kg of anhydrous citric acid powder, and put the two components into a three-dimensional motion mixer. Mix and stir at 30 rpm for 20 minutes at room temperature. After discharge, seal and store in a vacuum aluminum foil bag in the dark for later use.

[0042] Example 1: This embodiment provides a process for co-preparing biodegradable masterbatch from bio-based residues, including the following steps: S1, 100.0 kg of the micronized detoxified biomass base material prepared in Preparation Example 1 was transported to the high-speed mixer by a vacuum weighing feeder, and 11.0 kg of the solid-phase eutectic crosslinking precursor prepared in Preparation Example 4 was added simultaneously. The spindle speed was set to 300 rpm, and the mixture was mechanically mixed at room temperature for 5 min to achieve uniform dispersion of the reaction precursor in the gaps between the powder particles, thus obtaining the initial mixture. S2, add 4.0kg beeswax and 1.2kg soybean lecithin to the high-speed mixer and mix with the initial mixture. Adjust the equipment to high-speed shear mode, increase the speed to 1500rpm, cut off the external heat source, and rely on the extremely high shear friction of the powder to achieve the self-heating of the system. When the material temperature reaches 70℃, run at a constant temperature for 4 minutes and then discharge the material. S3. The premixed powder obtained in S2 is continuously fed into the feeding mechanism of the ring die granulator. Under the mechanical extrusion and shearing action of the pressure roller and the ring die, the local friction temperature of the material through the die hole jumps to 95°C. The material is compressed and formed under this temperature and pressure field, cut by the rotary cutter, and enters the air-cooled screening system to be cooled to 25°C, thus obtaining fully degradable bio-masterbatch.

[0043] Furthermore, the biodegradable masterbatch obtained in S3 is applied to the molding process of disposable tableware. The specific application steps are as follows: S4. The prepared biodegradable masterbatch is quantitatively injected into the mold cavity of the servo hot press molding equipment. The mold closing heating temperature is set to 140℃, the molding pressure is constant at 10MPa, and the holding time is controlled at 90s. During this process, the masterbatch completes eutectic rheology and in-situ cross-linking and curing. After molding, the fully biodegradable tableware is obtained by demolding.

[0044] Example 2: This embodiment provides a process for co-preparing biodegradable masterbatch from bio-based residues, including the following steps: S1, 100.0 kg of the micronized detoxified biomass base material prepared in Preparation Example 1 was conveyed to the high-speed mixer through a vacuum weighing feeder, and 6.0 kg of sorbitol crystal powder and 2.0 kg of anhydrous citric acid powder were added simultaneously. The spindle speed was set to 300 rpm, and the mixture was mechanically mixed at room temperature for 5 min to obtain the initial mixture. S2, add 3.0kg beeswax and 1.0kg soybean lecithin to the high-speed mixer and mix with the initial mixture. Adjust the equipment to high-speed shear mode and increase the speed to 1500rpm. Rely on mechanical friction to self-heat. When the material temperature reaches 70℃, run at a constant temperature for 4 minutes and then discharge the material. S3. The premixed powder obtained in S2 is continuously fed into a ring die granulator. The extrusion die temperature is controlled at 95°C. After compression molding, it is cut off and cooled to 25°C to obtain biodegradable masterbatch.

[0045] Furthermore, the masterbatch obtained in S3 is applied to tableware processing: S4. The masterbatch is quantitatively injected into the mold cavity of the servo hot press equipment. The mold temperature is set to 140℃, the pressure is applied to 10MPa, the pressure is held for 90s, and the mold is opened to remove the fully degradable tableware.

[0046] Example 3: This embodiment provides a process for co-preparing biodegradable masterbatch from bio-based residues, including the following steps: S1, 100.0 kg of the micronized detoxified biomass base material prepared in Preparation Example 1 was conveyed to the high-speed mixer through a vacuum weighing feeder. Simultaneously, 10.5 kg of the solid-phase eutectic crosslinking precursor prepared in Preparation Example 5, which contains 6.0 kg of sorbitol and 4.5 kg of anhydrous citric acid, was added, and an additional 4.0 kg of sorbitol crystalline powder was added. The spindle speed was set to 300 rpm, and the mixture was mixed at room temperature for 5 min to obtain the initial mixture. S2, add 5.0 kg beeswax and 1.5 kg soybean lecithin to the high-speed mixer, mix with the initial mixture, adjust the equipment to 1500 rpm high-speed shearing, friction heating to 70℃, and discharge after constant temperature operation for 4 minutes; S3. The premixed powder is fed into a ring die granulator, and the extrusion temperature is controlled at 95°C. The temperature is then reduced to 25°C by cutting off the die, thus obtaining the biodegradable masterbatch.

[0047] Furthermore, the masterbatch obtained in S3 is applied to tableware processing: S4. Inject the masterbatch into the mold cavity, set the molding temperature to 140℃, apply a pressure of 10MPa, hold the pressure for 90s, and then open the mold to remove the fully biodegradable tableware.

[0048] Example 4: This embodiment provides a process for co-preparing biodegradable masterbatch from bio-based residues, including the following steps: S1, 100.0 kg of the micronized detoxified biomass base material prepared in Preparation Example 2 was transported to a high-speed mixer through a closed metering system, and 11.0 kg of the solid-phase eutectic crosslinking precursor prepared in Preparation Example 4 was added simultaneously. The spindle speed was set to 200 rpm, and the mixture was mixed at room temperature for 8 min to obtain the initial mixture. S2, add 4.0kg beeswax and 1.2kg soybean lecithin, mix with the initial mixture, start high-speed shearing at 1200rpm, rely on friction to heat up, when the material temperature reaches 65℃, keep the temperature constant for 5 minutes and then discharge the material; S3. The premixed powder is fed into the ring die granulator. The gap between the pressure rollers is adjusted to control the transient temperature of the die friction to 85°C. The powder is then cut off and cooled to 25°C to obtain the biodegradable masterbatch.

[0049] Furthermore, the masterbatch obtained in S3 is applied to tableware processing: S4. Inject the masterbatch into the mold cavity, set the molding temperature to 130℃, apply a pressure of 5MPa, hold the pressure for 120s, and then open the mold to remove the fully biodegradable tableware.

[0050] Example 5: This embodiment provides a process for co-preparing biodegradable masterbatch from bio-based residues, including the following steps: S1, 100.0 kg of the micronized detoxified biomass base material prepared in Preparation Example 3 was transported to a high-speed mixer through a closed metering system, and 11.0 kg of the solid-phase eutectic crosslinking precursor prepared in Preparation Example 4 was added simultaneously. The spindle speed was set to 400 rpm, and the mixture was mixed at room temperature for 3 min to obtain the initial mixture. S2, add 4.0kg beeswax and 1.2kg soybean lecithin, mix with the initial mixture, turn on the 2000rpm ultra-high shear mode, friction heat up to 75℃, run at a constant temperature for 3 minutes and then discharge; S3. The premixed powder is fed into a ring die granulator to increase the mechanical compaction strength so that the transient temperature of the die friction reaches 100°C. The powder is then cut off and cooled to 25°C to obtain the biodegradable masterbatch.

[0051] Furthermore, the masterbatch obtained in S3 is applied to tableware processing: S4. Inject the masterbatch into the mold cavity, set the molding temperature to 160℃, apply a pressure of 15MPa, hold the pressure for 60s, and then open the mold to remove the fully biodegradable tableware.

[0052] Comparative Example 1: The difference from Example 1 is that sorbitol was not added to the formula, but everything else is the same.

[0053] Comparative Example 2: The difference from Example 1 is that anhydrous citric acid was not added to the formulation, but everything else is the same.

[0054] Comparative Example 3: The difference from Example 1 is that beeswax and soy lecithin were not added to the formula, but everything else is the same.

[0055] Comparative Example 4: Compared to Example 1, the difference lies in that the stepped temperature control response mechanism of the process is disrupted. After mixing all raw materials at room temperature, the high-speed mixer at 70°C for self-heating coating and the ring die granulator at 95°C for extrusion and degassing granulation in Example 1 are skipped, and the mixture is directly fed into a mold cavity at 140°C for pressing and molding. All other aspects are the same.

[0056] Comparative Example 5: Compared with Example 1, the difference is that the solid-phase eutectic crosslinking precursor provided in Preparation Example 4 was replaced with an equal mass of pure water, that is, 11.0 kg of pure water was used to replace sorbitol and anhydrous citric acid, and the rest were the same.

[0057] Test Example 1: Sorbitol crystalline powder (pure), anhydrous citric acid (pure), and the premixed powder prepared in step S2 of Example 1 were taken as test samples and placed in a desiccator for equilibration for 24 hours before use.

[0058] Differential scanning calorimetry was used for testing. 5.2 mg to 8.5 mg of each of the above-mentioned balanced samples were weighed, placed in a standard aluminum crucible, pressed and sealed, with an empty aluminum crucible as a reference.

[0059] The test environment was set to a high-purity nitrogen atmosphere, and the gas purging flow rate was 50 mL / min.

[0060] The test program was set to heat from 25°C to 200°C at a heating rate of 10°C / min, and the corresponding heat flux change curves were recorded.

[0061] Table 1. Characteristic parameters of DSC thermal analysis of intermediate materials and pure components in Example 1

[0062] in conclusion: According to Table 1 and Figure 1 The test results Figure 1 The three heat flow curves, from top to bottom, correspond to pure sorbitol, pure anhydrous citric acid, and the premixed powder collected after discharge in step S2 of Example 1, respectively. The single-component pure sorbitol and pure anhydrous citric acid show endothermic melting characteristic peaks near 95.42℃ and 155.81℃, respectively.

[0063] In the heat flow curve of the premixed powder in Example 1, the original high-temperature melting peak of anhydrous citric acid showed a weakening trend, and the system exhibited a broadened eutectic endothermic response around 91.18℃. The endothermic peak appearing in the premixed powder around 64.35℃ corresponds to the melting range of the beeswax component. Within the test range of room temperature to 70℃, the baseline was relatively flat, and no deep eutectic phase transition endothermic phenomenon was observed.

[0064] The test data above indicate that, under ambient temperature mixing and 70°C shearing conditions, the mixture of sorbitol and anhydrous citric acid tends to maintain a relatively stable physical state within this temperature range. When the test temperature exceeds 80°C, the system exhibits deep eutectic thermodynamic characteristics with a phase transition temperature shift. The relevant thermal response provides some data support for the material formulation's adaptation to the step-by-step temperature rise rheological and crosslinking operations set in subsequent processes.

[0065] Test Example 2: The unmolded biodegradable masterbatch obtained in step S3 of Example 1 and the molded tableware obtained in step S4 were taken as test samples respectively.

[0066] The two groups of samples were placed in a liquid nitrogen environment for cryogenic grinding, and the corresponding powders were collected after being sieved through a 200-mesh standard sieve.

[0067] The collected powder samples were placed in a vacuum drying oven and dried continuously at an ambient temperature of 60°C for 24 hours.

[0068] Take 1.5 mg of dried powder sample and mix it with 150 mg of spectroscopically pure potassium bromide powder, grind it, and prepare test samples by tableting.

[0069] The sample was tested using a Fourier transform infrared spectrometer, with the scanning wavenumber range set to 4000 cm⁻¹. -1 Up to 400cm -1 Spectral resolution of 4 cm -1 The scan was performed 32 times, and the corresponding infrared transmission spectra were recorded.

[0070] Table 2. Infrared Spectral Characteristic Absorption Peak Data of Intermediate Materials and Molded Parts in Example 1

[0071] in conclusion: According to Table 2 and Figure 2 The test data is at 3300cm -1 Up to 3400cm -1 Within the specified range, the masterbatch obtained in step S3 of Example 1 exhibits a relatively wide absorption band, with a band at 3346.82 cm⁻¹. -1 The transmittance at this point is 24.15%, and this absorption range typically corresponds to the stretching vibration of hydroxyl groups in the molecular structure; simultaneously, at 1712.43 cm⁻¹... -1 An absorption peak was detected at a wavenumber that corresponds to the characteristic absorption frequency of the carboxylic acid component.

[0072] After the molding process, the tableware obtained in step S4 of Example 1 showed an increase in transmittance in the hydroxyl absorption range, reaching 3358.17 cm⁻¹. -1The transmittance measured at this point was 45.39%, indicating a certain degree of consumption of hydroxyl groups in the system. Furthermore, in the test spectrum of the tableware, at 1714.66 cm⁻¹... -1 The absorption peak of the nearby carboxyl group showed a weakening characteristic, and at 1738.54 cm⁻¹ -1 An absorption peak with a transmittance of 33.45% appeared at the point, and this newly added absorption band is attributed to the stretching vibration of the carbonyl group in the ester structure.

[0073] The above data on the position of the spectral absorption peaks and the changes in transmittance indicate that, under the set molding temperature and pressure conditions, the polycarboxylic acid components in the material system interacted with the hydroxyl groups present in the biomass, and a network structure composed of ester bonds was generated inside the system. The test results provide a spectroscopic reference for the in-situ crosslinking reaction mechanism described in the process scheme.

[0074] Test Example 3: The molded parts obtained in Examples 1 to 5 and Comparative Examples 2, 4 and 5 were used as samples for mechanical property testing.

[0075] The samples were processed into Type 1B test strips conforming to GB / T1040.2 using cutting equipment, and strips with macroscopically visible defects on the edges were removed.

[0076] All test specimens were placed in an environmental test chamber with a temperature of 23±2℃ and a relative humidity of 50±5% for 24 hours.

[0077] Tensile tests were performed using a microcomputer-controlled universal testing machine. The clamp movement speed was set to 5 mm / min, and continuous data of tensile force and gauge length elongation were recorded during the test.

[0078] Five valid parallel specimens were tested for each group of samples, and the arithmetic mean of tensile strength and elongation at break was calculated.

[0079] Table 3. Test data of mechanical properties of molded parts in the examples and comparative examples

[0080] in conclusion: According to Table 3 and Figure 3 The mechanical property test results showed that the test specimen of Example 1 exhibited obvious yielding characteristics and elongation deformation stages during the tensile process, with a tensile strength of 28.34 MPa and an elongation at break of 6.12%. Comparative Example 2, due to the absence of anhydrous citric acid in its formulation, had a tensile strength of 9.87 MPa, and fractured at a relatively low stress level.

[0081] The data discrepancies indicate that the absence of esterification and cross-linking reactions involving polycarboxylic acids means that the material structure mainly relies on intermolecular physical hydrogen bonds and mechanical stacking, failing to form an effective three-dimensional network framework, resulting in a decreased ability to withstand external loads. Comparative Example 4 skipped the stepped temperature-controlled mixing process and adopted direct mixing and hot pressing molding. Its test curve showed a high initial modulus but rapid brittle fracture at a strain of 1.68%. If the precursor does not undergo prior solid-phase dispersion and granulation homogenization, it will cause uneven cross-linking density within the system during the molding stage, generating a large number of micro-stress concentration points, thus exhibiting macroscopic high brittleness defects.

[0082] Comparative Example 5 used pure water instead of the eutectic crosslinking precursor, and its tensile strength was only 6.53 MPa, with a low overall slope in the curve. This is related to the violent boiling and vaporization of free water in the system during high-temperature molding. The micropores left by the vaporized water inside the molded part disrupt the continuity of the matrix, leading to an overall deterioration in mechanical properties.

[0083] Test Example 4: The molded parts obtained in Examples 1 to 3 and Comparative Examples 2, 3 and 5 were used as test samples.

[0084] Each group of samples was cut into 50mm×50mm square test pieces. The initial thickness of the test pieces was measured, and the initial mass of the test pieces was weighed and recorded.

[0085] Set the temperature of the constant temperature water bath to 95±1℃, immerse the test piece in deionized water, and start timing.

[0086] Record the ultimate disintegration time of the test specimen during the immersion process when it softens and collapses or its structure disintegrates.

[0087] For test pieces that did not completely disintegrate after soaking for 30 minutes, they were removed and the surface moisture was dried. The thickness after soaking was measured, and the thickness expansion rate was calculated.

[0088] After soaking for 30 minutes, the test pieces were placed in a forced-air drying oven and dried at 105℃ to constant weight. The remaining mass after drying was weighed, and the mass loss rate was calculated.

[0089] Table 4. Test data on the hot water hydrolysis resistance of molded parts from the examples and comparative examples.

[0090] Note: In Table 4, "-" indicates that the sample had disintegrated before the 30-minute test time point, making it impossible to effectively measure the thickness expansion rate.

[0091] in conclusion: According to Table 4 and Figure 4The test results showed that the molded part of Example 1 had a maximum disintegration time of 246 minutes in a 95°C water bath environment, a thickness expansion rate of 4.13% after immersion for 30 minutes, and a mass loss rate of 1.87%. Its mass retention rate curve showed a relatively gentle decreasing trend over time. The sample of Comparative Example 2 experienced structural disintegration after immersion for 8 minutes, and a mass loss rate of 86.41% after 30 minutes.

[0092] The above differences indicate that in the system without anhydrous citric acid, the matrix is ​​mainly bound by physical interactions. Water penetration easily leads to the loss of matrix structure, demonstrating the correlation between the polycarboxylic acid-based crosslinking network and the maintenance of morphological stability under hot water conditions. The thickness expansion rate of Comparative Example 3 sample after immersion for 30 minutes was measured to be 37.82%, corresponding to a mass loss rate of 22.15%, and its dynamic curve showed a continuous downward trend. This reflects that when hydrophobic components are absent in the system, the resistance to external water penetration into the matrix is ​​relatively reduced. The ultimate disintegration time recorded for Comparative Example 5 was 16 minutes, indicating a decrease in structural stability compared to Example 1.

[0093] The relevant test results correspond to the micropores left by the vaporization of free water during the heat treatment stage, indicating that the increase in the internal pore structure expands the contact surface for water molecule intrusion. The test data comprehensively reflect the synergistic effect of the cross-linked framework and hydrophobic coating in improving the hydrolysis resistance of molded parts.

Claims

1. A method for co-preparing biodegradable masterbatch from biological residue, characterized in that, Made from the following ingredients in parts by weight: Micronized detoxified biomass substrate: 100.0 parts; Solid-phase eutectic crosslinking precursor: 8.0-14.5 parts; Beeswax: 3.0-5.0 parts; Soy lecithin: 1.0-1.5 parts; The solid-phase eutectic crosslinking precursor is composed of sorbitol crystalline powder and anhydrous citric acid powder.

2. The method for co-preparing biodegradable masterbatch from biological residue according to claim 1, characterized in that, The weight parts of the raw materials are: Micronized detoxified biomass substrate: 100.0 parts; Solid-phase eutectic crosslinking precursor: 11.0 parts; Beeswax: 4.0 parts; Soy lecithin: 1.2 parts.

3. The method for co-preparing biodegradable masterbatch from biological residue according to claim 1, characterized in that, In the solid-phase eutectic crosslinking precursor, the sorbitol crystalline powder comprises 6.0-10.0 parts by weight, and the anhydrous citric acid powder comprises 2.0-4.5 parts by weight.

4. The method for co-preparing biodegradable masterbatch from biological residue according to claim 1, characterized in that, The micronized detoxified biomass base material is a powder obtained by dehydrating and crushing fresh potato pulp and then subjecting it to combined microwave and ozone sterilization treatment. The free moisture content of the micronized detoxified biomass matrix is ​​8-15 wt%, and the particle size is 600-1000 mesh.

5. A process for preparing biodegradable masterbatch from bio-residue as described in any one of claims 1-4, characterized in that, Includes the following steps: Micronized detoxified biomass matrix and solid-phase eutectic crosslinking precursor are added to a high-speed mixer and mechanically mixed at a spindle speed of 200-400 rpm for 3-8 minutes at room temperature to obtain a preliminary mixture. Add beeswax and soybean lecithin to the high-speed mixer and mix them with the initial mixture. Adjust the high-speed mixer to high-speed shear mode and increase the speed to 1200-2000 rpm. The mixture heats up to 65-75°C by frictional work. After running at a constant temperature for 3-5 minutes, the mixture is discharged to obtain premixed powder. The premixed powder is continuously fed into a ring die granulator, and the friction temperature of the material during extrusion is controlled at 85-100°C. After compression molding, the material is cut off and cooled to 25°C to obtain the biodegradable masterbatch.

6. The process according to claim 5, characterized in that, The preparation of the micronized detoxified biomass base material includes the following steps: Freshly peeled and washed potatoes are cut into chunks and dried at 60–80°C until the free moisture content drops to 8–15 wt%, resulting in dried block material. The dried block material is crushed into fragments with an average particle size of 3-8 mm using a mechanical crusher; The fragments are fed into an airflow micronizer for grinding and classification, and fine powder with a particle size of 600-1000 mesh is collected. The fine powder is sent into a microwave and ozone combined disinfection chamber for 15-30 minutes for detoxification and sterilization to obtain the micronized detoxified biomass matrix.

7. The process according to claim 5, characterized in that, The pretreatment of the solid-phase eutectic crosslinking precursor before it is added to the high-speed mixer includes the following steps: Weigh out sorbitol crystalline powder and anhydrous citric acid powder and put them into a three-dimensional motion mixer. Mix and stir at 30 rpm for 15-20 minutes at room temperature. Seal and store in the dark for later use.

8. The process according to claim 5, characterized in that, Beeswax and soybean lecithin are added to the high-speed mixer. After the high-speed mixer is set to high-speed shear mode, the external heat source is cut off, and the self-heating is achieved by mechanical friction.

9. The process according to claim 5, characterized in that, The premixed powder is continuously fed into the feeding mechanism of the ring die granulator. Under the mechanical extrusion and shearing action of the pressure roller and the ring die, the powder is heated by friction and passes through the die. After being cut by a rotating cutter, it enters the air-cooled screening system for cooling.

10. The process according to claim 5, characterized in that, The micronized detoxified biomass substrate is transported to the high-speed mixer using a vacuum weighing feeder or a closed metering system.

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