Production process for preparing environment-friendly plastic by using biodegradable material

Abstract

The invention discloses a production process for preparing environment-friendly plastics by using biodegradable materials, and belongs to the field of environment-friendly plastics, the process comprises the following steps: preparing raw materials, sequentially air-drying the raw materials, and mixing PBS resin particles, a coated slow-release fertilizer, humic acid powder and a water-retaining agent to prepare nutrient slow-release particles; dividing the transplanting days of the plants into 20-35 days, 36-60 days and 60 days or more, and determining the mass parts of the raw materials according to the ranges; through precise proportioning of raw materials, adaptive design of a transplanting period and optimization of a forming process, the prepared environment-friendly plastic can be prepared into seedling pots meeting transplanting requirements of different plants, so that the seedling pots are stable in structure and controllable in degradation and can be directly used for moisture soil without advanced fertilization, slow-release supply of nutrients is realized, and the yield of the seedlings is increased. The survival rate and the growth quality of the seedlings are improved, and environmental protection and agricultural practicability are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of environment-friendly plastics, in particular to a production process for preparing environment-friendly plastics by using biodegradable materials. BACKGROUND

[0002] The demand for environment-friendly and biodegradable seedling pots in the current agricultural field is growing, but the existing biodegradable plastic production process has significant shortcomings and cannot meet the actual seedling needs. On the one hand, the existing seedling pots cannot adapt to the characteristics of the common heavy and easy to be compacted and wet soil environment in agriculture. Not only do they need to be fertilized in advance, but the nutrients are also easily lost with the compacted layer of wet soil, and the water retention capacity is insufficient, resulting in weak stress resistance and low survival rate of seedlings after transplanting, which cannot guarantee the continuous growth needs. Therefore, it is urgent to develop a biodegradable material environment-friendly plastic production process that can precisely adapt to different transplanting cycle plants, can be directly applied to wet soil without the need for pre-fertilization, and can balance the structure stability and nutrient supply, to solve the technical problems of the prior art. In view of the problems in the related art, no effective solution has been proposed so far. SUMMARY

[0003] In view of the problems in the related art, the present application proposes a production process for preparing environment-friendly plastics by using biodegradable materials to overcome the technical problem of pre-fertilization for wet soil application in the prior art.

[0004] To this end, the specific technical solutions adopted by the present application are as follows: A production process for preparing environment-friendly plastics by using biodegradable materials, the process comprising the following steps: S1, preparing raw materials and sequentially air-drying the raw materials, then mixing PBS resin particles, coated slow-release fertilizer, humic acid powder and water-retaining agent to prepare nutrient slow-release particles; S2, dividing the transplanting days of plants into 20-35 days, 36-60 days and more than 60 days, and determining the mass fraction of raw materials according to this range; S3, mixing the raw materials and nutrient slow-release particles in a mixer, then feeding the premixed material into a main twin-screw extruder, and finally extruding and granulating through heating in multiple temperature control zones and strong shearing of the screw; S4, melting the prepared masterbatch in an injection molding machine to prepare a seedling pot.

[0005] As a preferred embodiment, the preparation of raw materials and the sequential air-drying of the raw materials, and then the mixing of PBS resin particles, coated slow-release fertilizer, humic acid powder and water-retaining agent to prepare nutrient slow-release particles comprises the following steps: S11, prepare raw materials, which are composed of PLA, PBAT, plant fiber, PBS resin particles, coated slow-release fertilizer, humic acid powder, water-retaining agent, and compatibility agent; S12, put all raw materials into a forced air drying oven in turn, and dry them at 80℃ for 4-6 hours to completely remove water; All raw materials need to be completely dried to prevent hydrolytic degradation or bubbles during subsequent high-temperature processing; S13, measure the amount of PBS resin particles, coated slow-release fertilizer, humic acid, and water-retaining agent, and put them into a high-speed mixer together for 5-10 minutes of thorough mixing to achieve uniform distribution of each component powder and PBS resin particles; S14, put the pre-mixed material into a twin-screw extruder, melt blend the material at a temperature of 110-130℃ through heating and strong shearing of the screw to form a homogeneous melt; During this process, PBS is completely plasticized and uniformly wraps and disperses the functional powder, thus forming a homogeneous melt; S15, the uniform strip-shaped melt extruded from the extruder die is cooled and solidified by a cooling water tank, then steadily advances by a traction machine, and finally is cut into uniform cylindrical particles by a granulator to produce nutrient slow-release particles.

[0006] As a preferred embodiment, the transplanting days of plants are divided into 20-35 days, 36-60 days, and more than 60 days, and the mass fraction of raw materials is determined according to this range, including the following steps: S21, divide the transplanting period according to the growth law and root system development characteristics of different types of plants; for plants that grow rapidly and form roots quickly, divide them into 20-35 days of transplanting, for plants that need to cultivate seedlings, divide them into 36-60 days of transplanting, and for slow-growing woody plants, divide them into more than 60 days of transplanting; S22, establish a positive correlation framework between transplanting days and nutrient slow-release particles, set a nutrient demand starting benchmark point marked by the initial formation of seedling root system, then determine the basic nutrient constant to ensure transplanting survival, introduce the growth coefficient of quantified daily nutrient demand to reflect crop differences, build a segmented function model on this basis, and finally calibrate and optimize the model parameters through actual nutrient data of typical crops; S23, adjust the mass fraction of other raw materials according to the addition range of nutrient slow-release particles.

[0007] As a preferred embodiment, the framework of the positive correlation between the established transplanting days and the nutrient slow-release particles sets the nutrient demand starting benchmark point marked by the initial formation of seedling root system, then determines the basic nutrient constant to ensure transplanting survival, introduces the growth coefficient quantifying the daily nutrient demand to reflect the crop differences, constructs a segmented function model, and finally calibrates and optimizes the model parameters through the actual nutrient data of typical crops. S221, determine the most critical variable affecting nutrient demand as the target transplanting days G, and establish the positive correlation framework between G and the total number of nutrient intermediates T, and the longer the seedling period, the more the total amount of nutrients required, and the larger the T value. S222, set G0 as the benchmark growth days, G0 is 20 parts for 20-35 days transplanting, G0 is 35 for 36-60 days transplanting, G0 is 60 for more than 60 days transplanting, the basic constant B is 10 parts for more than 60 days transplanting, and G0 represents the critical point of seedling root system formation and starting to absorb nutrients from the outside world; when the seedling days G is shorter than G0, the nutrients required by the seedling mainly depend on the seed itself, so the minimum nutrient guarantee is required; the basic constant B is 5 parts for 20-35 days transplanting, the basic constant B is 7 parts for 36-60 days transplanting, and the basic constant B is 10 parts for more than 60 days transplanting, which is also the minimum nutrient reserve that must be provided to ensure that the seedling can immediately absorb nutrients after transplanting and resist environmental stress; S224, introduce the growth coefficient K to quantify the additional nutrients required by the plant for each additional day of growth; different growth rates of plants have different daily nutrient requirements, so different K values are set to reflect this difference, the K value is set to 0.2 for 20-35 days transplanting, the K value is set to 0.15 for 36-60 days transplanting, and the K value is set to 0.1 for more than 60 days transplanting; S225, construct a segmented function model, the specific formula is: when G≤G0, T=B; when G>G0, T=B+K×(G-G0); then select the known nutrient demand data of typical crops in each range, and substitute the model for repeated trial calculation and calibration; S226, the calculation result for 20-35 days transplanting is 5-8, i.e. the nutrient slow-release particle addition range is set to 5-8 parts for 20-35 days transplanting, the calculation result for 36-60 days transplanting is 7.15-10.75, i.e. the nutrient slow-release particle addition range is set to 8-10 parts for 36-60 days transplanting, and the calculation result for more than 60 days transplanting is 10, and the upper limit is set to 15, i.e. the nutrient slow-release particle addition range is set to 10-15 parts for more than 60 days transplanting.

[0008] As a preferred embodiment, the step of mixing raw materials with nutrient slow-release particles in a mixer, and then feeding the premixed materials into a main twin-screw extruder for heating in multiple temperature-controlled zones and strong shearing by the screw, and finally extruding and granulating includes the following steps: S31, raw materials and nutrient slow-release particles are mixed in a mixer, and the multiple temperature-controlled zones of the twin-screw extruder from the feed port to the die are pre-heated at a gradient, with the temperature range set at 160-180 degrees Celsius. Then the main motor of the twin-screw extruder is started to run at a low speed under no load, and then the premixed mixture of raw materials and nutrient slow-release particles is fed into the feed port of the extruder; S32, after the material enters the extruder, it starts to melt, and then under the action of strong shearing, extrusion and stirring of the high-speed screw, the molten resin and nutrient slow-release particles are broken; S33, the melt is extruded from the inside of the machine and introduced into a cooling water tank, where it is rapidly cooled and solidified from a viscous flow state to a glassy state; S34, the finished strand is pulled out of the cooling water tank and the surface is blown by a fan to remove water droplets. The surface-dried strand is introduced into a pelletizer to cut it into uniform cylindrical pellets, obtaining the finished masterbatch.

[0009] As a preferred embodiment, the step of melting the finished masterbatch in an injection molding machine to produce seedling pots includes the following steps: S41, the finished masterbatch is fed into the hopper of the injection molding machine, and the hopper dryer is started to continuously dry the pellets. The pellets fall into the heated barrel of the injection molding machine under the action of gravity, and are heated to a set temperature of 160-180 degrees Celsius under the combined action of the heating ring outside the barrel and the shearing heat generated by the rotation of the screw, and are melted into a uniform viscous melt; Through continuous drying, the water content can be reduced to a minimum to prevent bubbles or silver lines from appearing in the product due to water vaporization during the subsequent melting process; S42, the rotating screw retreats under the drive of the transmission device, and the mold closing mechanism of the injection molding machine drives the mold plate to move forward, so that the mold is tightly closed and locked to resist the high internal pressure in the cavity during subsequent injection; S43, the screw at the front end of the barrel is pushed by the injection cylinder to inject the molten material into the locked mold cavity; After filling, the screw still maintains a certain pressure for a short period of time to supplement the material lost due to the shrinkage of the melt, preventing the product from appearing shrink marks or depressions; S44, the cooling water circuit in the mold starts to circulate cooling water continuously, so that the melt injected into the cavity gradually cools and solidifies to form a solid seedling pot with the same shape as the mold cavity; S45, after the product is cooled to the preset strength and rigidity, the mold closing mechanism of the injection molding machine drives the mold plate to retreat, so that the mold is opened, and then the ejection device of the mold acts to stably eject the seedling pot which has been completely formed from the mold cavity.

[0010] After the seedling pot is made, the seedling pot is taken out and needs to be manually or visually inspected by a machine, whether the appearance is complete, whether there is a flash or a material defect, and the qualified product can be counted, stacked and dustproof sealed packaging.

[0011] As a preferred embodiment, the mass fraction of each component raw material of the seedling pot is: The mass fraction of each raw material of the seedling pot for transplanting in 20-35 days is: PLA, 40-50 parts, PBAT, 25-35 parts, plant fiber, 12-15 parts, and nutrient slow-release particles 5-8 parts; The mass fraction of each raw material of the seedling pot for transplanting in 36-60 days is: PLA, 40-50 parts, PBAT, 25-35 parts, plant fiber, 12-15 parts, and nutrient slow-release particles 8-10 parts; The mass fraction of each raw material of the seedling pot for transplanting in 60 days or more is: PLA, 40-50 parts, PBAT, 25-35 parts, plant fiber, 12-15 parts, and nutrient slow-release particles 10-15 parts; The mass fraction of each raw material of the nutrient slow-release particles is: PBS, 65 parts, coated slow-release fertilizer 30 parts, humic acid 3 parts, and water retaining agent 2 parts.

[0012] The beneficial effects of the present application are: 1. The seedling pot prepared by the present application can be directly planted in heavy and easy to be cemented tidal soil without additional pre-fertilization; the nutrient slow-release particles in the seedling pot use PBS as a carrier to uniformly wrap coated slow-release fertilizer, humic acid and water retaining agent, wherein the coated slow-release fertilizer can slowly release nutrients, the humic acid can improve the structure of the tidal soil and promote nutrient absorption, and the water retaining agent is adapted to the characteristics of the tidal soil to maintain water balance; the constant basic amount set according to the transplanting cycle provides the seedling with the minimum nutrient reserve to resist environmental stress after transplanting, and the additional nutrients added according to the growth coefficient can meet the continuous needs of the plant during the whole seedling period; when transplanting, only a hole needs to be dug for planting, and the seedling pot gradually degrades in the tidal soil environment, and the nutrients are released synchronously, thereby avoiding the problems of inconvenience of fertilization in the tidal soil and easy loss of nutrients, and ensuring that the seedling can immediately absorb nutrients after transplanting, and guaranteeing survival and healthy growth.

[0013] 2、The present application can perfectly adapt the seedling pot to plants with different growth characteristics by scientifically dividing the transplanting period; the process clearly divides the transplanting days into three ranges of 20-35 days, 36-60 days and more than 60 days, constructs a segmented function model to quantify the nutrient demand for fast-growing plants, strong seedling cultivation plants and slow-growing woody plants, determines the nutrient slow-release particle addition range under different periods through the setting of the basic amount constant and the growth coefficient, and verifies through typical crop experiments that the nutrient absorption law of plants in each period can be matched, at the same time, the mass fraction of main materials such as PLA, PBAT and plant fiber is fixed, and only the proportion of nutrient slow-release particles is adjusted, so that the stable structure strength and predictable degradation period of the seedling pot are ensured, and flexible customization of nutrient supply is realized without changing the overall production process to adapt to different transplanting period requirements. BRIEF DESCRIPTION OF DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description only constitute some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0015] Figure 1 is a flow chart of a production process for preparing environment-friendly plastic using biodegradable materials according to an embodiment of the present application. DETAILED DESCRIPTION

[0016] To further illustrate the embodiments, the present application provides drawings which are part of the disclosure of the present application, mainly used to illustrate the embodiments, and can explain the operating principle of the embodiments in conjunction with the related description of the specification. With reference to these contents, those skilled in the art should understand other possible embodiments and advantages of the present application. The components in the drawings are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0017] According to an embodiment of the present application, a production process for preparing environment-friendly plastic using biodegradable materials is provided.

[0018] The present application will be further described in conjunction with the drawings and specific embodiments, as shown in Figure 1 A production process for preparing environment-friendly plastic using biodegradable materials according to an embodiment of the present application, which comprises the following steps: S1, preparing raw materials and sequentially air-drying the raw materials, then mixing PBS resin particles, coated slow-release fertilizer, humic acid powder and water-retaining agent to prepare nutrient slow-release particles; Further, the raw materials are prepared and sequentially air-dried, and the PBS resin particles, the coated slow-release fertilizer, the humic acid powder and the water-retaining agent are mixed to prepare the nutrient slow-release particles, including the following steps. S11, preparing raw materials, the raw materials being composed of PLA, PBAT, plant fiber, PBS resin particles, coated slow-release fertilizer, humic acid powder, water-retaining agent and compatibility agent; S12, sequentially placing all the raw materials into a forced air drying oven, fully drying at 80°C for 4-6 hours to completely remove the contained water; S13, measuring the PBS resin particles, the coated slow-release fertilizer, the humic acid and the water-retaining agent by weight, and putting them into a high-speed mixer for 5-10 minutes of sufficient mixing to make the component powders and the PBS resin particles uniformly distributed; S14, putting the premixed material into a twin-screw extruder, melting and blending the material at a temperature of 110-130°C through heating and strong shearing of the screw to form a homogeneous melt; S15, the uniformly strip-shaped melt extruded from the extruder die is cooled and solidified through a cooling water tank, then stably advances by a traction machine, and finally is cut into uniformly sized cylindrical particles by a granulator to prepare the nutrient slow-release particles; S2, dividing the transplanting days of plants into 20-35 days, 36-60 days and more than 60 days, and determining the mass fraction of raw materials according to the range; Further, dividing the transplanting days of plants into 20-35 days, 36-60 days and more than 60 days, and determining the mass fraction of raw materials according to the range includes the following steps: S21, dividing the transplanting period according to the growth law and root system development characteristics of different types of plants; for plants with rapid growth and fast root formation, the transplanting period is divided into 20-35 days, for plants that need to cultivate seedlings, the transplanting period is divided into 36-60 days, and for slow-growing woody plants, the transplanting period is divided into more than 60 days; Further, a positive correlation framework between the transplanting days and the nutrient slow-release particles is established, a nutrient demand starting benchmark point for the initial formation of seedling root system is set, a basic nutrient constant for ensuring transplanting survival is determined, a growth coefficient for quantifying daily nutrient demand is introduced to reflect crop differences, and a segmented function model is constructed, and the specific steps for finally calibrating and optimizing the model parameters through actual nutrient data of typical crops are as follows: S221, determining that the most critical variable affecting nutrient demand is the target transplanting days G, and establishing a positive correlation framework between G and the total fraction T of nutrient intermediates, and the longer the seedling raising period, the more the total amount of nutrients required, and the T value is also correspondingly larger; S222、Set G0 as the reference growth days, 20-35 days of transplanting G0 is 20, 36-60 days of transplanting G0 is 35, 60 days or more of transplanting G0 is 60, and the base amount constant B of 60 days or more of transplanting is 10, G0 represents the critical point of root system formation of seedlings and the beginning of the need to absorb a large amount of nutrients from the outside world; when the growth days G are shorter than G0, the nutrients required by the seedlings mainly depend on the seed storage, so the minimum nutrient guarantee is required; the base amount constant B of 20-35 days of transplanting is determined to be 5, the base amount constant B of 36-60 days of transplanting is determined to be 7, and the base amount constant B of 60 days or more of transplanting is determined to be 10, which is also the minimum nutrient reserve that must be provided to ensure that the seedlings can immediately absorb nutrients after transplanting and resist environmental stress; It should be noted that G0 is the reference growth days, and B is the base amount constant, which can be obtained through the following experimental data: For the three transplanting ranges, lettuce, tomato and citrus are selected for systematic experiments: Cultivate in an artificial climate chamber, take samples every 5 days until the growth enters the stable linear period; each time at least 5 biological replicates are taken; Lettuce root development and aboveground growth dynamic data table According to the lettuce root development and aboveground growth dynamic data table in the above excerpt, it can be known that the root activity of lettuce reaches 81% of the maximum value at 20 days after sowing, and the aboveground dry weight and the days show a strong linear relationship, so the G0 of lettuce is determined to be 20 days; based on this, the representative G0 of 20-35 days of transplanting range is set to 20 days.

[0019] Tomato root development and aboveground growth dynamic data table According to the tomato root development and aboveground growth dynamic data table in the above excerpt, the G0 of tomato is determined to be 35 days, and based on this, the representative G0 of 36-60 days of transplanting range is set to 35 days.

[0020] Citrus root development dynamic data table According to the citrus root development dynamic data table in the above excerpt, the citrus seedlings reach the root function construction standard at 60 days after sowing, so the G0 of citrus is determined to be 60 days; based on this, the representative G0 of 60 days or more of transplanting range is set to 60 days.

[0021] Selecting healthy seedlings that have reached their respective G0 days, 20-day-old lettuce seedlings, 35-day-old tomato seedlings, and 60-day-old citrus seedlings, using seedling pots containing only inert substrates, setting a series of nutrient slow-release granule addition amount gradients, with 30 plants per treatment, and placing them in a uniform environment for recovery after transplanting, without supplying any additional nutrients, and evaluating survival and recovery conditions on the 7th and 14th days after transplanting; Determining transplant survival rates, new root occurrence indices, and leaf chlorophyll relative contents (SPAD values) to reflect nutritional conditions after transplanting stress, whole plant nitrogen contents 14 days after transplanting; the lowest nutrient slow-release granule addition amount corresponding to the nutrient fraction that allows the survival rate 14 days after transplanting to be stable at ≥95% and the average new root occurrence index to be ≥2.0 is determined as the B value, and the specific B values are determined as follows according to the extracted lettuce transplant survival data table, tomato transplant survival data table, and citrus transplant survival data table; Lettuce transplant survival data table Tomato transplant survival data table Citrus transplant survival data table S224、Introducing a growth coefficient K to quantify the additional nutrients required for a plant to grow one more day; plants with different growth rates have different daily nutrient requirements, so different K values are set to reflect this difference, with K values set to 0.2 for 20-35 day transplanting, 0.15 for 36-60 day transplanting, and 0.1 for 60-day or more transplanting; It should be noted that the growth coefficient K is determined through potting tests on different types of plants, based on their actual growth rates and nutrient absorption data, and through regression analysis; The specific steps for determining the growth coefficient K are as follows: Selecting lettuce as a representative of the 20-35 day range category, selecting tomato as a representative of the 36-60 day range category, and selecting citrus seedlings as a representative of the 60-day or more range category; Setting a series of sampling time points to obtain continuous growth data, and the sampling time points cover and significantly exceed the reference growth days G0 of the type of plant, with the time points for lettuce set to 15, 20, 25, 30, 35, and 40 days after sowing, the time points for tomato set to 30, 35, 40, 45, 50, 55, 60, and 65 days after transplanting, and the time points for citrus set to 50, 60, 70, 80, and 90 days after sowing; At each sampling time point, the whole plant dry weight and its total nitrogen, phosphorus and potassium content are determined, and the total absorption amount of nitrogen, phosphorus and potassium of each plant at time t is calculated, and the growth curve is drawn with the sampling day as the abscissa and the nitrogen accumulation amount as the ordinate, and the data points after G0 days are linearly regressed, and the equation Y = a (t - G0) + C is fitted, wherein Y is the growth index of the plant measured at the sampling time point, that is, the nitrogen accumulation amount, t is the specific experimental sampling day; G0 is a reference growth day set in advance according to the characteristics of the plant, a is the slope obtained by regression analysis, and its physical meaning is the daily dry matter accumulation rate or the daily nutrient absorption rate of the plant in the growth stage after G0, and C is the intercept, representing the estimated basic value of the growth index Y at time point t = G0; The slope a obtained by linear regression of the data points after G0 is the daily nitrogen absorption rate, and this slope value is defined as β; The components and mass parts of the nutrient slow-release granules are fixed as PBS 65 parts, coated slow-release fertilizer 30 parts, humic acid 3 parts, and water retaining agent 2 parts, and it is calculated that the average daily equivalent effective nitrogen amount γ released by each 1 part of the nutrient slow-release granules in the entire expected degradation period is 1.0 mg of nitrogen / day·part; A water culture experiment is performed on multiple lettuce plants, and the whole plant nitrogen accumulation amount is measured at 15, 20, 25, 30, 35 and 40 days after sowing, the slope is obtained by linear regression of the obtained data, the growth coefficient K is obtained through the conversion formula K = β / γ, the average value is calculated, and the final general K value in this range is determined as 0.2; An inert substrate cultivation experiment is performed on multiple tomato plants, and the data is linearly regressed at 30, 35, 40, 45, 50, 55, 60 and 65 days after transplanting, the slope is obtained, the growth coefficient K of the multiple tomato plants is obtained through the conversion formula K = β / γ, the average value is calculated, and the final K value is 0.15; A long-term cultivation experiment is performed on multiple citrus seedlings, and the data is linearly regressed at 50, 60, 70, 80 and 90 days after sowing, the slope is obtained, the average value is calculated, and the final K value is 0.15.

[0022] S225, a piecewise function model is constructed, and the specific formula is: when G ≤ G0, T = B; when G > G0, T = B + K × (G - G0); and the known nutrient requirement data of typical crops in each range is selected and substituted into the model for repeated trial calculation and calibration; S226, the calculation result of 20-35 days transplanting is 5-8, that is, when setting 20-35 days transplanting, the adding range of nutrient slow-release particles is 5-8 parts, the calculation result of 36-60 days transplanting is 7.15-10.75, that is, when setting 36-60 days transplanting, the adding range of nutrient slow-release particles is 8-10 parts, and the calculation result of more than 60 days transplanting is 10, and the upper limit is set to 15, that is, when setting more than 60 days transplanting, the adding range of nutrient slow-release particles is 10-15 parts.

[0023] It should be noted that the adding range of nutrient slow-release particles is also verified by experimental data, as shown in Table 1, Table 2 and Table 3. Select lettuce as the fast-growing type in the range of 20-35 days transplanting for verification experiment, test the adding amount of 4, 5, 6, 7, 8, 9, and get the best adding range of 5-8 parts; Table 1 Select tomato as the fast-growing type in the range of 36-60 days transplanting for verification experiment, test the adding amount of 7, 8, 9, 10, 11, and get the best adding range of 8-10 parts; Table 2 Select citrus as the fast-growing type in the range of more than 60 days transplanting for verification experiment, test the adding amount of 10, 11, 12, 13, 14, 15, and verify the best adding range of 10-15 parts; Table 3 It should be noted that the soil environment after transplanting is moist soil, which is heavy and easy to be compacted, and plants transplanted more than 90 days are no longer suitable for this seedling pot; S22, establish the framework of the positive correlation between transplanting days and nutrient slow-release particles, then set the nutrient demand starting benchmark point when the seedling root system is preliminarily formed, then determine the basic nutrient constant to ensure transplanting survival, then introduce the growth coefficient of quantified daily nutrient demand to reflect the difference of crops, and then build a segmented function model, and finally calibrate and optimize the model parameters through the actual nutrient data of typical crops; S23, determine the mass fraction of other raw materials according to the adding range of nutrient slow-release particles; Further, the raw materials and nutrient slow-release particles are put into a mixer for mixing, and then the premixed materials are put into a main twin-screw extruder, heated through multiple temperature control zones and strongly sheared by the screw, and finally extruded and granulated including the following steps: S31, the raw materials and nutrient slow-release particles are mixed in a mixer, and the double-screw extruder is preheated in multiple temperature control zones from the feeding port to the die head at a temperature range of 160-180 degrees Celsius, and the main motor of the double-screw extruder is started to run at a low speed under no load, and then the premixed mixture of the raw materials and the nutrient slow-release particles is fed into the feeding port of the extruder; S32, after the material enters the extruder, it starts to melt, and then under the action of the high-speed screw of the extruder, the molten resin and the nutrient slow-release particles are broken; S33, the melt is extruded from the inside of the machine and introduced into a cooling water tank, and is rapidly cooled and solidified in the circulating cooling water, and is transformed from a viscous flow state to a glass state; S34, the material strip after cooling and shaping is pulled out of the cooling water tank, and the water droplets adhering to the surface of the material strip are blown off by a fan, and the surface-dried material strip is introduced into a pelletizer to cut it into cylindrical pellets with uniform length and uniform particles, and the finished product master batch is obtained.

[0024] It should be noted that the cut pellets also need to be screened, and the pellets pass through a chute into a vibrating screen, and the qualified pellets are collected, and the unqualified products such as connected pellets and debris are screened out, so that high-quality plastic pellets with uniform composition for molding seedling pots are obtained; S3, the raw materials and nutrient slow-release particles are mixed in a mixer, and then the premixed material is fed into the main double-screw extruder, and finally extruded and granulated through heating in multiple temperature control zones and strong shearing of the screw; Further, the prepared master batch is fed into an injection molding machine to be melted, and a seedling pot is prepared including the following steps: S41, the finished master batch is fed into the hopper of the injection molding machine, and the hopper dryer is started to continuously dry the pellets, and the pellets fall into the heating cylinder of the injection molding machine under the action of gravity, and are heated to a set temperature of 160-180 degrees Celsius under the combined action of the shearing heat generated by the heating ring outside the cylinder and the rotation of the screw, and are melted into a uniform viscous melt; S42, the rotating screw retreats under the drive of the transmission device, the mold closing mechanism of the injection molding machine drives the mold plate to move forward, so that the mold is tightly closed and locked to resist the huge internal pressure of the mold cavity during subsequent injection; S43, the screw at the front end of the cylinder pushes the molten material into the locked mold cavity under the push of the injection cylinder; S44, the cooling water circuit in the mold starts to circulate cooling water continuously, so that the melt in the mold cavity is gradually cooled and solidified to form a solid seedling pot with the same shape as the mold cavity; S45, after the product is cooled to the preset strength and rigidity, the mold closing mechanism of the injection molding machine drives the mold plate to retreat, so that the mold is opened, and then the ejection device of the mold acts to stably eject the seedling pot which has been completely formed from the mold cavity; S4, the prepared master batch is put into the injection molding machine to melt and prepare the seedling pot.

[0025] Further, the quality parts of each component raw material of the seedling pot are: The quality parts of each raw material of the seedling pot for transplanting in 20-35 days are: PLA, 40-50 parts, PBAT, 25-35 parts, plant fiber, 12-15 parts, and nutrient slow-release particles 5-8 parts; The quality parts of each raw material of the seedling pot for transplanting in 36-60 days are: PLA, 40-50 parts, PBAT, 25-35 parts, plant fiber, 12-15 parts, and nutrient slow-release particles 8-10 parts; The quality parts of each raw material of the seedling pot for transplanting in more than 60 days are: PLA, 40-50 parts, PBAT, 25-35 parts, plant fiber, 12-15 parts, and nutrient slow-release particles 10-15 parts; It should be noted that the addition amount of the compatibilizer of the seedling pot for transplanting in 20-35 days, 36-60 days and more than 60 days is 0.5-2 parts, and the compatibilizer is maleic anhydride graft copolymer, i.e. PLA-g-MAH, and the mechanism is that the active groups in the molecule react with the end groups of PLA and PBAT or the hydroxyl groups on the surface of the plant fiber at the processing temperature, so as to improve the interfacial compatibility between the hydrophobic resin matrix and the hydrophilic plant fiber, thereby improving the mechanical properties and processing stability of the composite material; The quality parts of each raw material of the nutrient slow-release particles are: PBS, 65 parts, film slow-release fertilizer 30 parts, humic acid 3 parts, and water retaining agent 2 parts.

[0026] It should be noted that only the quality parts of the nutrient slow-release particles are changed, so that the flexible customization and precise control of the nutrient supply function are realized under the premise of ensuring the high stability of the basic structure strength and degradation performance of the seedling pot; by fixing the parts of the main materials such as PLA and PBAT, the reliable mechanical properties and predictable degradation period of the product are ensured; and by only adjusting the formula and amount of the nutrient slow-release intermediate, the growth days and nutrient requirements of different crops can be efficiently and low-costly optimized, so that the production process is greatly simplified, and the quality fluctuation and tedious repeated verification caused by the overall formula change are avoided.

[0027] The above is only a preferred embodiment of the present application, and is not used to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A production process for preparing environmentally friendly plastics using biodegradable materials, characterized in that, The process includes the following steps: S1. Prepare raw materials and air dry them in sequence. Then mix PBS resin granules, coated slow-release fertilizer, humic acid powder and water-retaining agent to make nutrient slow-release granules. S2. Divide the transplanting days of plants into 20-35 days, 36-60 days, and more than 60 days, and determine the mass fraction of raw materials according to this range; S3. The raw materials and nutrient slow-release granules are mixed in a mixer, and then the premixed materials are fed into the main twin-screw extruder. Through heating in multiple temperature control zones and strong shearing of the screw, the materials are finally extruded and granulated. S4. The prepared masterbatch is put into an injection molding machine to melt and make seedling pots.

2. The production process for preparing environmentally friendly plastics using biodegradable materials according to claim 1, characterized in that, The preparation of raw materials and their sequential air-drying, followed by the mixing of PBS resin granules, coated slow-release fertilizer, humic acid powder, and water-retaining agent to produce nutrient slow-release granules, includes the following steps: S11. Prepare raw materials, which consist of PLA, PBAT, plant fiber, PBS resin granules, coated slow-release fertilizer, humic acid powder, water-retaining agent, and compatibilizer. S12. Place all raw materials into a forced-air drying oven in sequence and dry them thoroughly at 80℃ for 4 to 6 hours to completely remove the moisture. S13. Weigh out the PBS resin granules, coated slow-release fertilizer, humic acid, and water-retaining agent according to the specified amounts, and put them into a high-speed mixer for 5 to 10 minutes to mix them thoroughly so that the powder of each component is evenly distributed with the PBS resin granules. S14. The premixed material is fed into a twin-screw extruder. Through heating and strong shearing of the screw, the material is melted and blended at a temperature of 110-130℃ to form a homogeneous melt. S15. The uniform strip-shaped melt extruded from the extruder die is cooled and solidified by a cooling water tank, then pulled forward steadily by a traction machine, and finally fed into a pelletizer to be cut into uniform cylindrical particles to make nutrient slow-release granules.

3. The production process for preparing environmentally friendly plastics using biodegradable materials according to claim 1, characterized in that, The process of dividing the transplanting period of plants into 20-35 days, 36-60 days, and more than 60 days, and determining the mass fraction of raw materials according to this range, includes the following steps: S21. Based on the growth patterns and root development characteristics of different types of plants, the transplanting period is divided into two categories: for plants that grow rapidly and form roots quickly, the transplanting period is 20 to 35 days; for plants that need to be cultivated into strong seedlings, the transplanting period is 36 to 60 days; and for woody plants that grow slowly, the transplanting period is more than 60 days. S22. Establish a framework for the positive correlation between transplanting days and slow-release nutrient granules, then set a starting point for the nutrient requirements of seedlings to mark the initial formation of the root system, then determine the basic nutrient constants to ensure transplant survival, and then introduce a growth coefficient to quantify the daily nutrient requirements to reflect crop differences. On this basis, construct a piecewise function model, and finally calibrate and optimize the model parameters using actual nutrient data of typical crops. S23. Determine the mass fractions of other raw materials based on the range of addition of nutrient slow-release granules.

4. The production process for preparing environmentally friendly plastics using biodegradable materials according to claim 3, characterized in that, The framework for establishing a positive correlation between transplanting days and slow-release nutrient granules, followed by setting a baseline for nutrient requirements marking the initial formation of seedling roots, determining the basic nutrient constants to ensure transplant survival, and then introducing a growth coefficient to quantify daily nutrient requirements to reflect crop variability, is then used to construct a piecewise function model. Finally, the specific steps for calibrating and optimizing the model parameters using actual nutrient data from typical crops are as follows: S221. The most critical variable affecting nutrient requirements is the target transplanting days G, and a framework for the positive correlation between G and the total number of nutrient intermediates T is established. At the same time, the longer the seedling period, the more total nutrients are required, and the larger the T value will be. S222. Set G0 as the baseline growth period. For seedlings transplanted at 20-35 days, G0 is 20 parts; for seedlings transplanted at 36-60 days, G0 is 35 parts; for seedlings transplanted after 60 days, G0 is 60 parts; and for seedlings transplanted after 60 days, the basic nutrient constant B is 10 parts. G0 represents the critical point at which the seedling root system forms and begins to absorb a large amount of nutrients from the outside. When the seedling growth period G is shorter than G0, the nutrients required by the seedling mainly rely on the seed's own storage, thus requiring a minimum nutrient guarantee. The basic nutrient constant B for seedlings transplanted at 20-35 days is determined to be 5 parts; for seedlings transplanted at 36-60 days, the basic nutrient constant B is 7 parts; and for seedlings transplanted after 60 days, the basic nutrient constant B is 10 parts. This is also the minimum nutrient reserve that must be provided to ensure that the seedlings can absorb nutrients immediately after transplanting and resist environmental stress. S224. Introduce the growth coefficient K to quantify the additional nutrients required for each additional day of plant growth; plants with different growth rates have different daily nutrient requirements, so different K values ​​are set to reflect this difference. The K value is set to 0.2 for transplanting after 20-35 days, 0.15 for transplanting after 36-60 days, and 0.1 for transplanting after more than 60 days. S225. Construct a piecewise function model with the following formula: when G≤G0, T=B; when G>G0, T=B+K×(G-G0); then select known nutrient requirement data of typical crops in each range, substitute them into the model, and perform repeated trial calculations and calibrations. S226. The calculation result for transplanting at 20-35 days is 5-8, meaning that when transplanting at 20-35 days, the range of nutrient slow-release granules added is 5-8 parts. The calculation result for transplanting at 36-60 days is 7.15-10.75, meaning that when transplanting at 36-60 days, the range of nutrient slow-release granules added is 8-10 parts. The calculation result for transplanting at more than 60 days is 10. At the same time, the upper limit is set to 15, meaning that when transplanting at more than 60 days, the range of nutrient slow-release granules added is 10-15 parts.

5. The production process for preparing environmentally friendly plastics using biodegradable materials according to claim 1, characterized in that, The process of mixing raw materials and nutrient-slow-release granules in a mixer, then feeding the premixed material into a twin-screw extruder, and finally extruding and granulating it through heating in multiple temperature-controlled zones and strong shearing by the screws includes the following steps: S31. Mix the raw materials and nutrient slow-release granules in the mixer. At the same time, preheat the multiple temperature control zones of the twin-screw extruder from the feed inlet to the die head in a gradient manner, setting the temperature range to 160-180 degrees Celsius. Then start the main motor of the twin-screw extruder and run it under no-load at the set low speed. Then feed the premixed raw materials and nutrient slow-release granules into the feed inlet of the extruder. S32. After the material enters the extruder, it begins to be heated and melted. Then, under the intense shearing, extrusion and stirring action of the high-speed screw, the molten resin and the nutrient slow-release particles are broken down. S33. The melt is extruded from inside the machine and introduced into the cooling water tank, where it is rapidly cooled and solidified in the circulating cooling water, changing from a viscous flow state to a glassy state. S34. The cooled and shaped strip is pulled out of the cooling water tank and the water droplets on its surface are blown away by the fan. The dried strip is then introduced into the pelletizer to be cut into cylindrical pellets with uniform length and uniform particle size, thus obtaining the finished masterbatch.

6. The production process for preparing environmentally friendly plastics using biodegradable materials according to claim 1, characterized in that, The process of melting the prepared masterbatch in an injection molding machine to produce seedling pots includes the following steps: S41. The finished masterbatch is fed into the hopper of the injection molding machine, and the hopper dryer is started to continuously dry the granules. The granules fall into the heating barrel of the injection molding machine under the action of gravity. Under the combined action of the heating ring outside the barrel and the shear heat generated by the screw rotation, the granules are heated to the set temperature of 160 to 180 degrees Celsius and melted into a uniform and viscous melt. S42. The rotating screw rotates and retracts under the drive of the transmission device. The mold clamping mechanism of the injection molding machine drives the mold plate to move forward, so that the mold closes tightly and applies clamping force to lock it to resist the huge cavity pressure during subsequent injection. S43. The screw at the front end of the barrel, driven by the injection cylinder, injects the molten material into the locked mold cavity; S44. The cooling water channel inside the mold starts to continuously circulate cooling water, so that the melt injected into the cavity gradually cools and solidifies, forming a solid seedling pot that is consistent with the shape of the mold cavity. S45. After the product cools to the preset strength and rigidity, the mold closing mechanism of the injection molding machine drives the template to retract, causing the mold to open. Then, the ejection device built into the mold is activated to smoothly eject the fully formed seedling pot from the mold cavity.

7. The production process for preparing environmentally friendly plastics using biodegradable materials according to claim 6, characterized in that, The mass fractions of each component raw material in the seedling pot are as follows: The mass fractions of each raw material in the seedling pot for transplanting at 20-35 days are: PLA, 40-50 parts; PBAT, 25-35 parts; plant fiber, 12-15 parts; and slow-release nutrient granules, 5-8 parts. The mass fractions of each raw material in the seedling pot for transplanting at 36-60 days are as follows: PLA, 40-50 parts; PBAT, 25-35 parts; plant fiber, 12-15 parts; and slow-release nutrient granules, 8-10 parts. The mass fractions of each raw material in the seedling pot for transplanting seedlings older than 60 days are as follows: PLA, 40-50 parts; PBAT, 25-35 parts; plant fiber, 12-15 parts; and slow-release nutrient granules, 10-15 parts. The mass fractions of each raw material in the nutrient slow-release granules are as follows: PBS, 65 parts; coated slow-release fertilizer, 30 parts; humic acid, 3 parts; and water-retaining agent, 2 parts.

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