A degradable composition suitable for desert greening, a degradable seedling pot and a preparation method thereof

Abstract

The present invention relates to a degradable composition and a degradable seedling pot suitable for desert greening, and a preparation method thereof, comprising the following raw materials in parts by mass: 55-65 parts of aliphatic polyester, 20-30 parts of light calcium carbonate, 3-5 parts of fly ash, 2-5 parts of feather fiber, 0.5-1.5 parts of photosensitizer terpyridine ruthenium, 2-4 parts of core-shell structure composite photocatalyst, and 0.1-0.3 parts of coupling agent; the core-shell structure composite photocatalyst is composited with perylene diimide as core and calcium carbonate as shell, and the mass ratio of core to shell is 1: (0.15-0.25). The degradable seedling pot prepared by the degradable composition is suitable for desert greening, and is not easy to degrade quickly in the early stage of seedling transplanting to the desert, thereby preventing the rapid loss of water and nutrients irrigated into the desert soil; and after 12 months, the seedling pot is completely degraded, and the seedling survives and grows by root; that is, a balance is reached between the low degradation rate in the early stage and the high degradation rate in the late stage.

Description

Technical Field

[0001] The invention belongs to the technical field of degradable materials, and in particular relates to a degradable composition and a degradable seedling pot suitable for desert greening. Background Art

[0002] In recent years, due to the harsh desert environment, the irrigation water and nutrients are easily lost, and the survival rate of seedlings is low, so it is difficult to plant green in the desert. In order to improve the survival rate of seedlings, the prior art generally places the seedlings in a plastic greenhouse or a culture room to cultivate them into seedlings, and then transplants them into seedling pots, and finally plants the seedlings and seedling pots together in the desert; the function of the seedling pot is mainly to prevent the loss of water and nutrients irrigated into the desert soil in the early stage of seedling transplanting, and to improve the initial survival rate of seedlings. At present, conventional seedling pots are generally non-degradable plastics, which will cause environmental pollution to the environment because they are not easy to degrade. From an environmental protection perspective, degradable seedling pots are needed for desert greening; and seedling pots made of excellent performance degradable materials are not only expensive, but also often have too high an initial degradation rate, which causes the water and nutrients irrigated into the desert soil in the early stage of seedling transplanting in the special environment of the desert to be easily lost, that is, the problem of low survival rate of seedlings cannot be completely solved.

[0003] According to the special environment of desert soil and the growth cycle characteristics of seedlings, in the desert environment, the seedlings need to prevent rapid degradability within the first three months after being transplanted into the desert, so as to prevent the water and nutrients irrigated into the desert soil from being lost, thereby increasing the survival rate of the seedlings; and the seedling pots need to be completely degraded 12 months after being transplanted into the desert, so that the seedlings can take root and grow vigorously, ultimately achieving desert greening. Summary of the invention

[0004] In view of the fact that the seedling pots in the above-mentioned prior art cannot meet the requirements of greening in desert environments, the present invention provides a degradable composition and a degradable seedling pot suitable for greening in deserts, which achieve a good balance between a low degradation rate in the initial stage and a high degradation rate in the final stage, so that the water and nutrients irrigated into the desert soil in the initial three months after the seedlings are transplanted to the desert are not easily lost, and the seedling pot is completely degraded after December with basically no residue, and is a degradable green and environmentally friendly material.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A degradable composition suitable for desert greening, comprising the following raw materials in parts by weight:

[0007] Aliphatic polyester 55~65 parts,

[0008] 20~30 parts of light calcium carbonate,

[0009] 3~5 parts of fly ash,

[0010] 2~5 parts of feather fiber,

[0011] Photosensitizer terpyridine ruthenium 0.5-1.5 parts,

[0012] 2-4 parts of core-shell structure composite photocatalyst,

[0013] Coupling agent 0.1-0.3 parts;

[0014] The core-shell structure composite photocatalyst is composited with perylene diimide as the core and calcium carbonate as the shell, and the mass ratio of the core to the shell is 1:(0.15-0.25).

[0015] Furthermore, the mass ratio of the core to the shell of the core-shell structured composite photocatalyst is 1:(0.20-0.25).

[0016] Furthermore, the core-shell structure composite photocatalyst is prepared by a method comprising the following steps:

[0017] (L1) dissolving an emulsifier in a carbonate aqueous solution to form an aqueous phase solution;

[0018] (L2) adding perylene diimide to the aqueous solution and stirring and emulsifying to obtain an oil-in-water emulsion;

[0019] (L3) adding a calcium salt aqueous solution dropwise into the emulsion and performing an interfacial chemical deposition reaction under stirring;

[0020] (L4) After the reaction is completed, the core-shell structure composite photocatalyst is obtained after cooling, washing and drying.

[0021] Preferably, in step (L1), the emulsifier is at least one of sodium dodecyl sulfonate, sodium dodecyl sulfate, NP-10, and OP-10, and its usage is 3-5wt% of the aqueous solution; the carbonate is at least one of sodium carbonate and potassium carbonate, and the concentration of the carbonate aqueous solution is 5-10wt%.

[0022] Preferably, in step (L2), the emulsification temperature is 75-85°C, and the perylene diimide is 10-25 wt% of the aqueous solution.

[0023] Preferably, in step (L3), the calcium salt is one of calcium chloride, calcium hypochlorite and calcium bicarbonate, and the concentration of the calcium salt aqueous solution is 5-10 wt %; the reaction conditions are: temperature 50-60°C, stirring speed 250-350 r / min, and the calcium salt aqueous solution is added dropwise within 45-60 min.

[0024] Furthermore, the aliphatic polyester is at least one of polycaprolactone and polybutylene succinate, and its number average molecular weight is 15000 to 40000. The larger the molecular weight, the better the melting point and tensile strength, but the slower the degradation rate, so it is better to select the molecular weight within the above range.

[0025] Furthermore, the particle size of the light calcium carbonate is 300-800 mesh, and preferably the particle size distribution satisfies: 8-15wt% of 300-400 mesh particles, 25-40wt% of 400-600 mesh particles, and 45-60wt% of 600-800 mesh particles. Based on the maximum packing density theory, different particle sizes of the component raw materials are closely packed in the optimal ratio, so that the whole system is tightly wrapped to form a complete and dense matrix structure.

[0026] Furthermore, the particle size of the fly ash is 1200-2000 mesh.

[0027] Furthermore, the feather fiber is at least one of chicken feather fiber, duck feather fiber and goose feather fiber, with a diameter of 3 to 9 microns and a length of 0.5 to 1.2 mm. Feather fiber is a degradable natural raw material, the main component of which is keratin, which can provide nutrition during plant growth.

[0028] Furthermore, the coupling agent is at least one of epoxy silane coupling agent, vinyl triethoxy silane, methacrylate silane coupling agent, N-2 (aminoethyl) 3-aminopropyl trimethoxy silane, N-2 (aminoethyl) 3-aminopropyl triethoxy silane, 3-aminopropyl trimethoxy silane, and 3-aminopropyl triethoxy silane.

[0029] In a second aspect, the present invention provides a degradable seedling raising pot suitable for desert greening, which is prepared from the aforementioned composition suitable for desert greening.

[0030] The present invention also provides a method for preparing the aforementioned degradable seedling pot, comprising the following steps:

[0031] (S1) mixing aliphatic polyester, light calcium carbonate, fly ash, feather fiber, photosensitizer terpyridine ruthenium, core-shell structure composite photocatalyst and coupling agent, and simultaneously tamping and exhausting with ultrasonic vibration to obtain a mixture;

[0032] (S2) feeding the mixture into a screw injection molding machine for injection molding;

[0033] (S3) After the injection molding, cooling, mold opening, grinding and shaping are performed in sequence to obtain a degradable seedling pot.

[0034] Preferably, in step (S2), the heating temperature of each section in the screw injection molding machine is: 160-180°C in the first section, 190-200°C in the second section, 210-225°C in the third section, and the temperature of the die head is 230-240°C.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] 1) The present invention prepares a core-shell structure composite photocatalyst through interfacial chemical deposition reaction. The organic photocatalyst perylene diimide in the core layer has a slow-release effect under the protection of the calcium carbonate in the shell layer, thereby avoiding the rapid decomposition of the seedling pots and the loss of water and nutrients when the seedlings are transplanted to the desert in the early stage, thereby improving the initial survival rate of the seedlings. In the middle and late stages of transplanting the seedlings to the desert, the seedlings gradually grow more roots and have the ability to take root in the desert soil. At this time, the shell calcium carbonate of the core-shell structure composite photocatalyst gradually reacts with CO 2 , H 2 O reacts to form calcium bicarbonate Ca(HCO 3 ) 2 , thereby releasing the perylene diimide in the core layer. The released perylene diimide synergistically promotes the degradation of the main resin with the photosensitizer terpyridine ruthenium; at the same time, the light calcium carbonate in the matrix gradually reacts with CO 2 , H 2 O reacts to form calcium bicarbonate Ca(HCO 3 ) 2 , Ca(HCO 3 ) 2 Because it leaves micropores after dissolving in water and leaving the matrix, it increases the contact area between the main resin and the surrounding air and microorganisms, further promoting the degradation of the main resin; that is, in the middle and late stages of transplanting seedlings to the desert, the combined action of the core-shell structure composite photocatalyst, terpyridine ruthenium and light calcium carbonate promotes the degradation of the main resin, allowing the seedlings to take root in the desert soil and grow.

[0037] 2) The degradable composition of the present invention and the degradable seedling pot prepared therefrom are suitable for desert greening. The seedlings are not easily degraded quickly within the first three months after being transplanted to the desert, thereby preventing the rapid loss of water and nutrients irrigated into the desert soil; and after 12 months, the seedling pot is completely degraded, and the seedlings survive, take root and grow; that is, a good balance is achieved between the low degradation rate in the initial stage and the high degradation rate in the final stage.

[0038] 3) The initial bending strength of the degradable seedling pot prepared by the present invention is also good, which can meet the requirements of transplanting and unloading, that is, it can also achieve a good balance between mechanical properties and degradation rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1This is a physical photo of the seedling pot described in Example 1. DETAILED DESCRIPTION

[0040] The present invention will be further described below in conjunction with specific embodiments.

[0041] Unless otherwise specified in the following examples, the reagents and materials described can be obtained from commercial sources.

[0042] Unless otherwise specified, the “parts” in the embodiments of the present invention are parts by mass, and the “%” are percentages by mass.

[0043] Polybutylene succinate was selected from Dongguan Yuefa Plastic Raw Materials Co., Ltd., and the number average molecular weight was 25,000.

[0044] The fly ash is first-grade fly ash with a particle size of 1500 mesh.

[0045] The diameter of duck feather fibers ranges from 3 to 6 microns and the length is about 1.0 mm.

[0046] Preparation of core-shell structure composite photocatalyst:

[0047] Preparation Example 1

[0048] (L1) dissolving 4 parts of an emulsifier, sodium dodecyl sulfate, in 96 parts of an 8 wt % sodium carbonate aqueous solution to form an aqueous phase solution;

[0049] (L2) adding 20 parts of perylene diimide to the aqueous solution prepared in (L1) and stirring and emulsifying, controlling the emulsification temperature to 75°C and stirring for 20 minutes to obtain an oil-in-water emulsion;

[0050] (L3) adding 55.5 parts of 6 wt% calcium chloride aqueous solution (the mass ratio of core layer perylene diimide to shell layer calcium carbonate is 1:0.15 after conversion) to the emulsion prepared in (L2), and performing interfacial chemical deposition reaction at 55°C and a stirring speed of 250 r / min, and controlling the calcium chloride aqueous solution to be added within 60 minutes; and continuing stirring for 20 minutes after the addition is completed;

[0051] (L4) After the reaction was completed, it was cooled, washed with ether twice, and dried in a drying oven at 80°C for 24 hours to obtain a core-shell structure composite photocatalyst a with a particle size of 1.3 μm.

[0052] Preparation Example 2

[0053] The rest is the same as Preparation Example 1, except that the amount of 6wt% calcium chloride aqueous solution used in step (L3) is 74 parts (that is, the mass ratio of core layer perylene diimide to shell layer calcium carbonate in the core-shell structure photocatalyst is 1:0.2); finally, a core-shell structure composite photocatalyst b is obtained with a particle size of 1.5μm.

[0054] Preparation Example 3

[0055] The rest is the same as Preparation Example 1, except that the amount of 6wt% calcium chloride aqueous solution used in step (L3) is 92.5 parts (i.e., the mass ratio of core layer perylene diimide to shell layer calcium carbonate in the core-shell structure photocatalyst is 1:0.25); finally, a core-shell structure composite photocatalyst b is obtained with a particle size of 1.2μm.

[0056] Example 1

[0057] A degradable seedling pot suitable for desert greening, comprising the following raw materials in parts by weight:

[0058] 60 parts of polybutylene succinate,

[0059] 25 parts of 600 mesh light calcium carbonate,

[0060] 4 parts of fly ash,

[0061] 3.5 parts of duck feather fiber,

[0062] Photosensitizer terpyridine ruthenium 1 part,

[0063] 3 parts of core-shell structure composite photocatalyst a,

[0064] Coupling agent vinyl triethoxysilane 0.2 parts;

[0065] The preparation method comprises the following steps:

[0066] (S1) aliphatic polyester, light calcium carbonate, fly ash, duck feather fiber, photosensitizer terpyridine ruthenium, core-shell structure composite photocatalyst and coupling agent are stirred and mixed in a high-speed mixer at 800 r / min for 1 hour, and then compacted and exhausted by ultrasonic vibration to obtain a mixture;

[0067] (S2) feeding the mixture into a screw injection molding machine for injection molding, wherein the heating temperatures of the various sections of the screw injection molding machine are: 170° C. for the first section, 190° C. for the second section, 215° C. for the third section, and the temperature of the die head is 230° C.;

[0068] (S3) After injection molding, cooling, mold opening, grinding and shaping are performed in sequence to obtain a degradable seedling pot. The actual photo is shown in the attached Figure 1 .

[0069] Example 2

[0070] The rest is the same as Example 1, except that the core-shell structure composite photocatalyst b prepared in Preparation Example 2 is used instead of the core-shell structure composite photocatalyst a.

[0071] Example 3

[0072] The rest is the same as Example 1, except that the core-shell structure composite photocatalyst c prepared in Preparation Example 3 is used instead of the core-shell structure composite photocatalyst a.

[0073] Example 4

[0074] The rest is the same as Example 1, except that the particle gradation of light calcium carbonate satisfies: 325 mesh particles account for 10 wt%, 500 mesh particles account for 35 wt%, and 800 mesh particles account for 55 wt%.

[0075] Example 5

[0076] The rest is the same as Example 1, except that the composition of the raw materials is:

[0077] 55 parts of polybutylene succinate,

[0078] 20 parts of 600 mesh light calcium carbonate,

[0079] 3 parts of fly ash,

[0080] 2 parts duck feather fiber,

[0081] Photosensitizer terpyridine ruthenium 0.5 parts,

[0082] 2 parts of core-shell structure composite photocatalyst,

[0083] Coupling agent: 0.1 part of vinyltriethoxysilane.

[0084] Example 6

[0085] The rest is the same as Example 1, except that the composition of the raw materials is:

[0086] 65 parts of polybutylene succinate,

[0087] 30 parts of 600 mesh light calcium carbonate,

[0088] 5 parts of fly ash,

[0089] 5 parts of duck feather fiber,

[0090] Photosensitizer terpyridine ruthenium 1.5 parts,

[0091] 4 parts of core-shell structure composite photocatalyst a,

[0092] Coupling agent: 0.3 parts of vinyltriethoxysilane.

[0093] Comparative Example 1

[0094] The rest is the same as Example 1, except that bismuth-based photocatalyst Bi is used. 2 WO 6Alternative core-shell structure composite photocatalyst a.

[0095] Comparative Example 2

[0096] The rest is the same as Example 1, except that the core-shell structure composite photocatalyst a is not used.

[0097] Comparative Example 3

[0098] The rest is the same as Example 1, except that terpyridine ruthenium is not used.

[0099] Testing and analysis

[0100] The seedling pot samples prepared in the examples and comparative examples were subjected to the following performance tests:

[0101] 1) Degradation performance test: According to GB / T 20197-2006, the seedling pots were tested for outdoor degradation performance. In mid-April (mid-March to the end of May is the best time to plant trees in the desert), the seedling pot samples were directly placed at a depth of 30-40 cm in the soil of the Tengger Desert in Alxa Left Banner, Inner Mongolia. The degradation time and degradation rate of the samples were recorded. The degradation rate is reflected by the change in mass, and the calculation formula is:

[0102] Degradation rate (%) = (1-M / M 0 )×100%

[0103] Among them, M 0 is the initial mass of the seedling pot, and M is the mass after degradation for a certain period of time.

[0104] 2) Bending strength test: The initial bending strength of the seedling pot specimens was tested according to GB / T 9341-2008.

[0105] The test results are shown in Table 1.

[0106] Table 1 Degradation performance and bending strength test

[0107]

[0108] As can be seen from Table 1, the degradable seedling pot prepared by the embodiment of the present invention is not easy to degrade quickly within the initial 3 months, and the degradation rate at 3 months is less than 15%, thereby preventing the water and nutrients irrigated into the desert soil from being easily lost, thereby improving the survival rate of the seedlings; and the degradation rate of the main resin in the middle and late stages is not low, and 100% degradation is achieved at 12 months, which is conducive to the seedlings taking root in the desert soil for growth. That is, the degradable seedling pot prepared by the embodiment of the present invention achieves a good balance between the low degradation rate in the early stage and the high degradation rate in the late stage, so it is suitable for desert greening. At the same time, it can be seen from Table 1 that the initial bending strength of the degradable seedling pot prepared by the embodiment of the present invention is also relatively good, not less than 30 Mpa, which can meet the use requirements of transplanting and unloading, that is, it can also achieve a good balance between mechanical properties and degradation rate.

[0109] In Comparative Example 1, bismuth-based photocatalyst Bi 2 WO 6 The seedling pots prepared with alternative core-shell structure composite photocatalysts degraded quickly in the first three months, and the water and nutrients irrigated into the desert soil were easily lost, which was not conducive to the survival of the seedlings.

[0110] In Comparative Example 2, the seedling pots prepared without using the core-shell structure composite photocatalyst had a low degradation rate in the initial three months, but the degradation rate in December was also low, which was not conducive to the growth of seedlings.

[0111] In comparative example 3, the seedling pots prepared without terpyridine ruthenium have a low degradation rate in the initial three months, but the degradation rate in December is also low, which is not conducive to the growth of seedlings. By comparing Example 1 with comparative examples 2 and 3, it is shown that the photosensitizer terpyridine ruthenium and the core-shell structure composite photocatalyst have a synergistic effect.

[0112] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A degradable composition suitable for desert greening, characterized in that: The invention comprises the following raw materials in parts by weight: Aliphatic polyester 55~65 parts, 20~30 parts of light calcium carbonate, 3~5 parts of fly ash, 2~5 parts of feather fiber, Photosensitizer terpyridine ruthenium 0.5-1.5 parts, 2-4 parts of core-shell structure composite photocatalyst, Coupling agent 0.1-0.3 parts; The core-shell structure composite photocatalyst is composed of perylene diimide as the core and calcium carbonate as the shell, and the mass ratio of the core to the shell is 1: (0.15-0.25); The aliphatic polyester is at least one of polycaprolactone and polybutylene succinate, and has a number average molecular weight of 15,000 to 40,000.

2. The degradable composition according to claim 1, characterized in that The mass ratio of the core to the shell of the core-shell structure composite photocatalyst is 1:(0.20-0.25).

3. The degradable composition according to claim 1, characterized in that The core-shell structure composite photocatalyst is prepared by a method comprising the following steps: (L1) dissolving an emulsifier in a carbonate aqueous solution to form an aqueous phase solution; (L2) adding perylene diimide to the aqueous solution and stirring and emulsifying to obtain an oil-in-water emulsion; (L3) adding a calcium salt aqueous solution dropwise into the emulsion and performing an interfacial chemical deposition reaction under stirring; (L4) After the reaction is completed, the core-shell structure composite photocatalyst is obtained after cooling, washing and drying.

4. The degradable composition according to claim 3, characterized in that In step (L1), the emulsifier is at least one of sodium dodecyl sulfonate, sodium dodecyl sulfate, NP-10, and OP-10, and the amount thereof is 3-5wt% of the aqueous solution; the carbonate is at least one of sodium carbonate and potassium carbonate, and the concentration of the carbonate aqueous solution is 5-10wt%; and / or In step (L2), the emulsification temperature is 75-85°C, and the perylene diimide is 10-25wt% of the aqueous solution; and / or In step (L3), the calcium salt is one of calcium chloride, calcium hypochlorite, and calcium bicarbonate, and the concentration of the calcium salt aqueous solution is 5-10 wt%; the reaction conditions are: temperature 50-60°C, stirring speed 250-350r / min, and the calcium salt aqueous solution is added dropwise within 45-60min.

5. The degradable composition according to claim 1, characterized in that: The particle size of the light calcium carbonate is 300-800 meshes.

6. The degradable composition according to claim 5, characterized in that The particle size distribution of the light calcium carbonate satisfies: 8-15wt% of 300-400 mesh particles, 25-40wt% of 400-600 mesh particles, and 45-60wt% of 600-800 mesh particles.

7. The degradable composition according to claim 1, characterized in that: The particle size of the fly ash is 1200-2000 mesh; the feather fiber is at least one of chicken feather fiber, duck feather fiber and goose feather fiber, with a diameter of 3-9 microns and a length of 0.5-1.2 mm.

8. The degradable composition according to claim 1, characterized in that: The coupling agent is at least one of epoxy silane coupling agent, vinyl triethoxy silane, methacrylate silane coupling agent, N-2 (aminoethyl) 3-aminopropyl trimethoxy silane, N-2 (aminoethyl) 3-aminopropyl triethoxy silane, 3-aminopropyl trimethoxy silane, and 3-aminopropyl triethoxy silane.

9. A degradable seedling pot suitable for desert greening, prepared from the composition suitable for desert greening according to any one of claims 1 to 8.

10. The method for preparing the degradable seedling pot according to claim 9, characterized in that: The following steps are involved: (S1) mixing aliphatic polyester, light calcium carbonate, fly ash, feather fiber, photosensitizer terpyridine ruthenium, core-shell structure composite photocatalyst and coupling agent, and simultaneously tamping and exhausting with ultrasonic vibration to obtain a mixture; (S2) feeding the mixture into a screw injection molding machine for injection molding; (S3) After the injection molding, cooling, mold opening, grinding and shaping are performed in sequence to obtain a degradable seedling pot.

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