CN115058065A

CN115058065A - Modified filler with light-oxygen degradation agent slow release effect, preparation method and degradation rate controllable PBAT mulching film

Info

Publication number: CN115058065A
Application number: CN202210765998.9A
Authority: CN
Inventors: 曲鹏飞; 刘振伟; 麻宁; 王磊; 黎源
Original assignee: Wanhua Chemical Group Co Ltd
Current assignee: Wanhua Chemical Group Co Ltd
Priority date: 2022-06-30
Filing date: 2022-06-30
Publication date: 2022-09-16
Anticipated expiration: 2042-06-30
Also published as: CN115058065B

Abstract

The invention provides a modified filler with a slow release effect of a photo-oxygen degradation agent, a preparation method thereof and a PBAT mulching film with a controllable degradation rate. The modified filler has a core-shell structure and sequentially comprises a core layer, a first shell layer and a second shell layer from inside to outside; the core layer is a porous filler adsorbed with a degradation agent, the first shell layer is a polyol esterified substance, the second shell layer is a polylactic-co-glycolic acid (PLGA) layer, and the layers are connected through covalent bonds. The PBAT mulching film with the controllable degradation rate is obtained by carrying out melt blending on the PBAT, the anti-UV auxiliary agent, the compatibilizer and the modified filler with the slow release effect of the photo-oxygen degradation agent and blowing the film, and the PBAT mulching film has higher physical property in the use process and can be rapidly degraded after being used, so that the controllable degradation of the PBAT mulching film is finally realized.

Description

Modified filler with light-oxygen degradation agent slow-release effect, preparation method and PBAT (poly (butylene adipate-co-terephthalate)) mulching film with controllable degradation rate

Technical Field

The invention relates to the technical field of polymer processing and modification, in particular to a modified filler with a slow release effect of a photo-oxidative degradation agent, a preparation method of the modified filler and a PBAT (poly (butylene adipate-co-terephthalate)) mulching film with a controllable degradation rate.

Background

PBAT is the most popular biodegradable mulching film material at present, but because the degradation speed is too high and the degradation period is too short, PBAT is degraded frequently in the growth period of crops and is a main factor for inhibiting the popularization of mulching film products. In order to delay the degradation period and meet the growth requirement of organisms, researchers usually add some anti-UV aging aids into the PBAT biodegradable mulching film, and the anti-UV aging aids can play a role in shielding or absorbing ultraviolet rays, so that the damage of the ultraviolet rays to the PBAT mulching film can be effectively reduced, and the service life of the PBAT mulching film is remarkably prolonged. However, the continuous action of the anti-UV aging auxiliary agent can cause the degradation period of the PBAT mulching film after use to be obviously prolonged, so that the PBAT mulching film cannot be rapidly degraded in a short time, and the PBAT mulching film which cannot be rapidly degraded can affect the fertility of soil or cause soil hardening and the like after entering the soil, thereby affecting the yield of crops in the next year.

The ideal PBAT degradable mulching film can realize the controllable degradation of the mulching film, namely the mulching film can keep good soil moisture preservation and moisture preservation performance in the growth process of crops and can be rapidly degraded after the mulching film is used up, thereby avoiding the adverse effect on the soil and the growth of the crops in the next year. Chinese patent CN106674923A proposes a controllable degradation PBAT/PLA composite film, the degradation period of the composite film is regulated and controlled by controlling the proportion of PLA and calcium carbonate, but the method can only enable the mulching film to be degraded smoothly, still can not ensure the effect of rapid degradation after the mulching film reaches the service life, and still can influence the growth of crops in the next season. Therefore, a more controllable biodegradation solution is urgently needed to be searched for in this aspect.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a modified filler with a slow release effect of a photo-oxidative degradation agent and a preparation method thereof.

The invention also aims to provide a novel biodegradable PBAT mulching film with controllable degradation rate, and the modified filler with the slow release effect of the photo-oxidative degradation agent is subjected to melt blending with the PBAT, the anti-UV auxiliary agent and the compatibilizer and film blowing to obtain the PBAT mulching film with controllable degradation rate. The release time of the degradation agent can be regulated and controlled by the PLGA degradation rate of the modified filler to control the controllable degradation of the PBAT mulching film, so that the PBAT mulching film has higher physical performance in the use process, can be rapidly degraded after use, and finally realizes the controllable degradation of the PBAT mulching film.

The invention provides a modified filler with a slow release effect of a photo-oxygen degradation agent, which has a core-shell structure and sequentially comprises a core layer, a first shell layer and a second shell layer from inside to outside; the core layer is a porous filler adsorbed with a degradation agent, the first shell layer is a polyol alcoholate, the second shell layer is a polylactic-co-glycolic acid (PLGA), and the layers are connected through covalent bonds.

Preferably, the size of the nuclear layer is 2000-10000 meshes, preferably 4000-8000 meshes;

the thickness of the first shell layer is 0.05-0.25 μm, preferably 0.1-0.2 μm;

the thickness of the second shell layer is 0.1-0.5 μm, preferably 0.2-0.4 μm.

According to the modified filler with the light-oxygen degradation agent slow-release effect, the porous filler contained in the core layer is a porous filler containing carboxyl, and the carboxyl in the porous filler containing carboxyl and polyol are subjected to esterification reaction under the action of a catalyst to prepare the polyol esterified substance of the first shell layer;

the polylactic acid-glycolic acid copolymer (PLGA) of the second shell layer is prepared by taking hydroxyl in the first shell layer as an initiating group and lactide and glycolide as comonomers through ring-opening polymerization reaction.

The modified filler with the slow release effect of the photo-oxygen degradation agent comprises the following raw materials in parts by mass:

porous filler: 100 parts of (A);

a degradation agent: 20-30 parts, preferably 22-28 parts;

polyol: 10-30 parts, preferably 15-20 parts;

catalyst: 0.01 to 0.05 part, preferably 0.02 to 0.04 part;

lactide: 10-30 parts, preferably 15-20 parts;

glycolide: 10-30 parts, preferably 15-25 parts.

In the present invention, the porous filler is selected from porous fillers containing carboxyl groups; preferably, the carboxyl group content is from 0.2 to 1.5mmol/g, preferably from 0.5 to 1.0 mmol/g;

preferably, the porous filler has a particle size of 2000-10000 meshes, preferably 4000-8000 meshes, and a porosity of 60-90%, preferably 70-80%;

preferably, the porous filler is selected from any one or a combination of at least two of carboxyl group-containing diatomaceous earth, carboxyl group-containing montmorillonite, and the like; such as sendai CD201#, fenghong DK 5.

In the present invention, the degradation agent is selected from any one or a combination of at least two of transition metal compounds, benzophenone compounds, and the like, and preferably manganese stearate and/or tetramethyl-4, 4-diaminobenzophenone.

In the present invention, the polyhydric alcohol is selected from fatty alcohols having a carbon chain carbon number of 5 or less and a hydroxyl functionality of 2 to 5, preferably ethylene glycol and/or glycerol.

In the present invention, the catalyst is selected from any one or a combination of at least two of hydrous sulfates, preferably any one or a combination of at least two of nickel sulfate hexahydrate, iron sulfate monohydrate, zinc sulfate heptahydrate, and the like.

According to the modified filler with the slow release effect of the photo-oxidative degradation agent, the release of the degradation agent can be measured by infrared, and the initial release time of the photo-oxidative degradation agent can be controlled within 50-100 days.

The invention also provides a preparation method of the modified filler with the slow release effect of the photo-oxygen degradation agent, which comprises the following steps:

1) fully mixing the porous filler and the degrading agent to enable the degrading agent to be adsorbed in the porous filler to obtain a nuclear layer;

2) mixing the core layer prepared in the step 1), polyhydric alcohol and a catalyst, heating to react under the protection of nitrogen, forming a first shell layer on the surface of the core layer, and then performing vacuum dehydration to obtain an intermediate coating the first shell layer.

3) Under the protection of nitrogen, mixing the intermediate coated with the first shell layer prepared in the step 2) with lactide and glycolide for copolymerization reaction to obtain the modified filler with the slow release effect of the photo-oxygen degradation agent.

In the step 1), the mixing is carried out under normal pressure, and the mixing temperature is 5-50 ℃, preferably 20-35 ℃; the mixing time is 0.5-3h, preferably 1-2 h;

the mixing is carried out in a mixer, preferably a double-helix mixer, and the stirring speed is 500-1500r/min, preferably 800-1200 r/min.

In the step 2), the temperature of the reaction is 150-; the time is 4 to 8 hours, preferably 5 to 7 hours;

preferably, the reaction is carried out under stirring conditions at a speed of 500-.

In the step 2), the vacuum dehydration is carried out, and the vacuum degree is 0.001-0.01 MPa; the dehydration temperature is 150-200 ℃, preferably 170-180 ℃; the dehydration time is 1-3h, preferably 1.5-2.5 h.

In the step 3), the temperature of the copolymerization reaction is 150-170 ℃, preferably 155-165 ℃; the time is 8-10h, preferably 8.5-9.5 h.

The modified filler with the slow release effect of the photo-oxygen degradation agent can be used for preparing a PBAT mulching film, and preferably, the invention provides a PBAT mulching film with a controllable degradation rate, which comprises the following raw materials in parts by weight:

PBAT: 100 parts of (A);

the modified filler with the slow release effect of the photo-oxygen degradation agent comprises the following components in percentage by weight: 0.5-20 parts, preferably 5-15 parts;

anti-UV auxiliary agent: 0.1 to 5 parts, preferably 1 to 3 parts;

compatibilizer: 0.1 to 5 parts, preferably 0.5 to 3 parts.

Preferably, the PBAT melt index is between 2 and 10g/10min, preferably between 4 and 6g/10min (test conditions 190 ℃, 2.16 kg).

Preferably, the anti-UV auxiliary agent is selected from any one or a combination of at least two of o-hydroxybenzophenone, benzotriazole, salicylate and triazine, preferably any one or a combination of at least two of benzotriazole, 2-hydroxy-4-n-octyloxybenzophenone and ethylhexyl salicylate.

Preferably, the compatibilizer is selected from any one or a combination of at least two of epoxy, maleic anhydride, acrylate, silane coupling agents, phthalate esters, and the like.

The invention also provides a preparation method of the PBAT mulching film with the controllable degradation rate, which comprises the following steps:

s1, uniformly mixing PBAT, the modified filler with the photooxidative degradation agent slow-release effect, the anti-UV auxiliary agent and the compatibilizer, putting the mixture into a double-screw extruder, carrying out melt blending, and carrying out extrusion granulation to obtain master batches;

s2, feeding the master batches into a single-screw film blowing machine to blow a film, and obtaining the PBAT mulching film with controllable degradation rate.

In step S1, the melt blending temperature is between 150 ℃ and 180 ℃;

in step S2, the film blowing temperature is between 150 ℃ and 170 ℃.

The PBAT mulching film product with the controllable degradation rate has the thickness of 0.006-0.030mm and the width of 40-200 cm.

The initial degradation time of the PBAT mulching film with the controllable degradation rate can be controlled within 50-100 days, wherein the initial degradation time refers to the time required for the tensile breaking strength of the mulching film to be reduced to 90% of the initial tensile breaking strength.

The PBAT mulching film with controllable degradation rate can be widely applied to the technical field of production of various crops in various regions.

Compared with the prior art, the technical scheme of the invention has the beneficial effects that:

the invention provides a modified filler with a light-oxygen degradation agent slow-release effect, which is compounded with PBAT, an anti-UV aging auxiliary agent and a compatibilizer to prepare a mulching film material. In the normal use process of the mulching film, the UV-resistant auxiliary agent added in the PBAT can effectively reduce the photo-oxidative degradation speed of the PBAT, and at the moment, the photo-oxidative degradation agent in the modified filler is coated in the filler by the second shell layer (PLGA layer) and the first shell layer (polyalcohol ester layer) of the modified filler and cannot be released into the PBAT, so that the mulching film can be ensured to keep excellent physical properties such as mechanical strength and the like in the normal use process;

in the later stage of the use of the mulching film, the PLGA layer is gradually degraded, water vapor gradually enters the first shell layer, so that the PLGA layer is swelled to form a larger gap, and the photo-oxygen degradation agent is released, so that the PBAT mulching film is rapidly degraded. Therefore, the aim of controllable degradation of the PBAT mulching film is achieved, higher physical performance can be ensured in use, and the PBAT mulching film can be rapidly degraded after use.

Because the degradation speed of the PLA chain segment in the PLGA is slower, and the degradation speed of the PGA chain segment is faster, the degradation speed of the PLGA coating layer can be effectively regulated and controlled by controlling the proportion of the two copolymerization units, and further the release of the photo-oxygen degradation agent and the time for the rapid degradation of the PBAT mulching film can be effectively controlled, therefore, compared with the prior art, the controllable degradation of the PBAT mulching film can be really realized.

In addition, as rigid particles, the modified filler with the slow release effect of the photo-oxygen degradation agent can obviously improve the mechanical property of the PBAT mulching film.

Drawings

FIG. 1 is a schematic structural diagram of a modified filler with a slow release effect of a photo-oxidative degradation agent according to the present invention;

FIG. 2 is a graph showing the change in tensile break strength of the geomembranes prepared in examples 1-5;

FIG. 3 is a graph showing the change in tensile rupture strength of the mulching films prepared in comparative examples 1 to 6.

Detailed Description

The present invention is further illustrated by the following examples, which should be construed as limiting the scope of the invention.

The main raw materials adopted in the examples of the invention are as follows, and the other raw materials are common commercial raw materials unless otherwise specified:

diatomaceous earth containing carboxyl group: carboxyl content of 0.4mmol/g, porosity of 80%, and particle size of 8000 meshes (Senda CD201 #);

montmorillonite containing carboxyl: the carboxyl content is 0.3mmol/g, the porosity is 75 percent, and the particle size is 6000 meshes (Fenghong DK 5);

photo-oxidative degradation agent: manganese stearate (world chemical), tetramethyl-4-diaminobenzophenone (shanghai dinning industry);

polyol: ethylene glycol (Xinxiangcheng chemical industry) and glycerol (David chemical industry);

catalyst: nickel sulfate hexahydrate (Yunnan Ruikantu 19#), zinc sulfate heptahydrate (Jinhuia TaiAR grade);

lactide: dadall (R) is a compound of D;

glycolide; a good guo share;

PBAT: the melt index is 4.1g/10min, and the Xinjiang blue Shantun river 801T;

anti-UV auxiliary agent: benzotriazole (Tianjin Lianlong UV234), 2-hydroxy-4-n-octoxybenzophenone (Tianjin Lianlong UV531), and ethylhexyl salicylate (Qingdao Wanyuan mountain Biotech Co., Ltd.);

compatibilizer: epoxy compatibilizer (basf ADR4468), maleic anhydride compatibilizer (telex chemical).

The main performance of the PBAT mulching film in the embodiment of the invention is tested by the following method:

tensile breaking strength: the film and sheet in the third section were tested for tensile properties according to GB/T1040.3-2006 for plastics, with a tensile rate of 200 mm/min.

Example 1

The preparation method of the modified filler with the slow release effect of the photo-oxygen degradation agent comprises the following steps:

1) under normal pressure, 100g of carboxyl-containing diatomite and 20g of manganese stearate are added into a double-helix mixer at the temperature of 5 ℃, and are fully mixed for 0.5h at the stirring speed of 500rpm, so that a degradation agent is adsorbed in the porous filler to obtain a core layer;

2) mixing the nuclear layer prepared in the step 1) with 10g of ethylene glycol and 0.01g of zinc sulfate heptahydrate, heating to 150 ℃ under the protection of nitrogen, reacting for 4 hours at a stirring speed of 500rpm to form a first shell layer on the surface of the nuclear layer, and dehydrating for 1 hour at a vacuum degree of 0.001MPa and a temperature of 150 ℃ to obtain an intermediate coating the first shell layer;

3) under the protection of nitrogen, mixing the intermediate coated with the first shell layer prepared in the step 1) with 10g of lactide and 25g of glycolide, and reacting for 8 hours at 170 ℃ to obtain the modified filler with the slow release effect of the photo-oxygen degradation agent.

The modified filler has a three-layer core-shell structure, the core layer is a porous filler adsorbed with a degradation agent, and the size is 8000 meshes; the first shell layer is a polyol ester layer with the thickness of 0.05 mu m; the second shell layer is a polylactic-co-glycolic acid (PLGA) layer with the thickness of 0.1 μm, and the layers are connected by covalent bonds.

Preparing a PBAT mulching film with controllable degradation rate, comprising the following steps:

s1, uniformly mixing 100g of PBAT, 0.5g of the prepared modified filler with the photo-oxidative degradation agent slow-release effect, 0.1g of 2-hydroxy-4-n-octoxy benzophenone and 0.1g of maleic anhydride, putting into a double-screw extruder, melting and blending at 150 ℃, extruding and granulating to obtain master batches;

s2, feeding the master batches into a single-screw film blowing machine, and blowing the film at 150 ℃ to obtain the PBAT film with controllable degradation rate. The thickness of the mulching film product is 0.006mm, and the width of the mulching film product is 40 cm.

The degradation time test results of the mulching film are shown in table 1, and the change test results of the tensile breaking strength of the mulching film along with time are shown in fig. 2.

Example 2

1) under normal pressure, 100g of carboxyl-containing montmorillonite and 30g of tetramethyl-4, 4-diaminobenzophenone are added into a double-helix mixer at the temperature of 50 ℃, and are fully mixed for 3 hours at the stirring speed of 1500rpm, so that a degradation agent is adsorbed in the porous filler to obtain a core layer;

2) mixing the nuclear layer prepared in the step 1) with 30g of ethylene glycol and 0.05g of nickel sulfate hexahydrate, heating to 200 ℃ under the protection of nitrogen, reacting for 8 hours at a stirring speed of 1000rpm to form a first shell layer on the surface of the nuclear layer, and dehydrating for 3 hours at a vacuum degree of 0.01MPa and a temperature of 200 ℃ to obtain an intermediate coating the first shell layer;

3) under the protection of nitrogen, mixing the intermediate coated with the first shell layer prepared in the step 1) with 30g of lactide and 20g of glycolide, and reacting at 170 ℃ for 10h to obtain the modified filler with the slow release effect of the photo-oxygen degradation agent.

The modified filler has a three-layer core-shell structure, the core layer is a porous filler adsorbed with a degrading agent, and the size of the porous filler is 6000 meshes; the first shell layer is a polyol ester layer with the thickness of 0.25 mu m; the second shell layer is polylactic acid-glycolic acid copolymer (PLGA layer), the thickness is 0.5 μm, and the layers are connected by covalent bond.

s1, uniformly mixing 100g of PBAT, 20g of the prepared modified filler with the photo-oxidative degradation agent slow-release effect, 5g of benzotriazole and 5g of maleic anhydride, putting the mixture into a double-screw extruder, melting and blending at 180 ℃, and extruding and granulating to obtain master batches;

s2, feeding the master batches into a single-screw film blowing machine, and blowing the film at 170 ℃ to obtain the PBAT film with controllable degradation rate. The thickness of the mulching film product is 0.030mm, and the width of the mulching film product is 200 cm.

Example 3

1) under normal pressure, 100g of diatomite containing carboxyl and 22g of tetramethyl-4, 4-diaminobenzophenone are added into a double-helix mixer at the temperature of 15 ℃, and are fully mixed for 1.5h at the stirring speed of 800rpm, so that a degradation agent is adsorbed in the porous filler to obtain a nuclear layer;

2) mixing the nuclear layer prepared in the step 1) with 15g of ethylene glycol and 0.02g of nickel sulfate hexahydrate, heating to 160 ℃ under the protection of nitrogen, reacting for 5 hours at a stirring speed of 600rpm to form a first shell layer on the surface of the nuclear layer, and dehydrating for 1.5 hours at a vacuum degree of 0.003MPa and a temperature of 170 ℃ to obtain an intermediate for coating the first shell layer;

3) under the protection of nitrogen, mixing the intermediate coated with the first shell prepared in the step 1) with 15g of lactide and 15g of glycolide, and reacting at 155 ℃ for 8.5 hours to obtain the modified filler with the slow release effect of the photo-oxygen degradation agent.

The modified filler has a three-layer core-shell structure, the core layer is a porous filler adsorbed with a degradation agent, and the size is 8000 meshes; the first shell layer is a polyol ester layer with the thickness of 0.1 mu m; the second shell layer is polylactic acid-glycolic acid copolymer (PLGA layer), the thickness is 0.2 μm, and the layers are connected by covalent bond.

s1, uniformly mixing 100g of PBAT, 5g of the prepared modified filler with the photo-oxygen degradation agent slow-release effect, 1g of 2-hydroxy-4-n-octoxy benzophenone and 1g of ADR4468, putting into a double-screw extruder, melting and blending at 155 ℃, extruding and granulating to obtain master batches;

s2, feeding the master batches into a single-screw film blowing machine, and blowing the film at 155 ℃ to obtain the PBAT film with controllable degradation rate. The thickness of the mulching film product is 0.012mm, and the width of the mulching film product is 80 cm.

Example 4

The preparation method of the modified filler with the slow release effect of the photooxidation degradation agent comprises the following steps:

1) under normal pressure, 100g of montmorillonite containing carboxyl and 24g of manganese stearate are added into a double-helix mixer at the temperature of 25 ℃, and are fully mixed for 2 hours at the stirring speed of 1000rpm, so that a degradation agent is adsorbed in the porous filler to obtain a core layer;

2) mixing the nuclear layer prepared in the step 1) with 20g of glycerol and 0.03g of nickel zinc sulfate heptahydrate, heating to 170 ℃ under the protection of nitrogen, reacting for 6 hours at the stirring speed of 700rpm, forming a first shell layer on the surface of the nuclear layer, and dehydrating for 2 hours at the temperature of 180 ℃ under the vacuum degree of 0.005MPa to obtain an intermediate coating the first shell layer;

3) under the protection of nitrogen, mixing the intermediate coated with the first shell layer prepared in the step 1) with 20g of lactide and 10g of glycolide, and reacting for 9 hours at 160 ℃ to obtain the modified filler with the slow release effect of the photo-oxygen degradation agent.

The modified filler has a three-layer core-shell structure, the core layer is a porous filler adsorbed with a degrading agent, and the size of the porous filler is 6000 meshes; the first shell layer is a polyol ester layer with the thickness of 0.15 mu m; the second shell layer is polylactic acid-glycolic acid copolymer (PLGA layer), the thickness is 0.3 μm, and the layers are connected by covalent bond.

s1, uniformly mixing 100g of PBAT, 10g of the prepared modified filler with the photo-oxidative degradation agent slow-release effect, 2g of benzotriazole and 2g of ADR4468, putting the mixture into a double-screw extruder, carrying out melt blending at 160 ℃, and carrying out extrusion granulation to obtain master batches;

s2, feeding the master batches into a single-screw film blowing machine, and blowing the film at 160 ℃ to obtain the PBAT film with controllable degradation rate. The thickness of the mulching film product is 0.018mm, and the width of the mulching film product is 120 cm.

The initial degradation time test results of the mulching film are shown in table 1, and the change test results of the tensile breaking strength of the mulching film along with time are shown in fig. 2.

Example 5

1) under normal pressure, 100g of diatomite containing carboxyl and 28g of tetramethyl-4, 4-diaminobenzophenone are added into a double-helix mixer at the temperature of 35 ℃, and are fully mixed for 2.5 hours at the stirring speed of 1200rpm, so that a degradation agent is adsorbed in the porous filler to obtain a nuclear layer;

2) mixing the nuclear layer prepared in the step 1) with 25g of glycerol and 0.04g of nickel zinc sulfate heptahydrate, heating to 180 ℃ under the protection of nitrogen, reacting for 7 hours at a stirring speed of 800rpm, forming a first shell layer on the surface of the nuclear layer, and dehydrating for 2.5 hours at a vacuum degree of 0.007MPa and a temperature of 190 ℃ to obtain an intermediate coating the first shell layer;

3) under the protection of nitrogen, mixing the intermediate coated with the first shell prepared in the step 1) with 25g of lactide and 30g of glycolide, and reacting at 165 ℃ for 9.5 hours to obtain the modified filler with the slow release effect of the photo-oxygen degradation agent.

The modified filler has a three-layer core-shell structure, the core layer is a porous filler adsorbed with a degradation agent, and the size is 8000 meshes; the first shell layer is a polyol ester layer with the thickness of 0.2 mu m; the second shell layer is polylactic acid-glycolic acid copolymer (PLGA layer), the thickness is 0.4 μm, and the layers are connected by covalent bond.

s1, uniformly mixing 100g of PBAT, 15g of the prepared modified filler with the photo-oxidative degradation agent slow-release effect, 3g of ethylhexyl salicylate and 3g of maleic anhydride, putting into a double-screw extruder, melting and blending at 170 ℃, extruding and granulating to obtain master batches;

s2, feeding the master batches into a single-screw film blowing machine, and blowing the film at 165 ℃ to obtain the PBAT mulching film with controllable degradation rate. The thickness of the mulching film product is 0.025mm, and the width of the mulching film product is 160 cm.

Comparative example 1

The process of example 1 is referenced, except that the modified filler is used only in the core layer prepared in step 1).

The core layer replaces the modified filler with the slow release effect of the photo-oxygen degradation agent in the formula, and other raw materials and operation are unchanged, so that the PBAT mulching film is prepared.

The degradation time test results of the mulching film are shown in table 1, and the change test results of the tensile breaking strength of the mulching film along with time are shown in fig. 3.

Comparative example 2

Referring to the method of example 1, except that the modified filler employs only the core layer coated with the first shell intermediate prepared in step 2).

And replacing the modified filler with the slow release effect of the photo-oxygen degradation agent in the formula by the core layer coated with the first shell layer intermediate, and keeping other raw materials and operation unchanged to prepare the PBAT mulching film.

Comparative example 3

Referring to the method of example 1, the only difference is that when the modified filler is prepared, the first shell layer is omitted and the second shell layer intermediate is directly coated with the core layer.

And replacing the modified filler with the slow release effect of the photo-oxidative degradation agent in the formula by the core layer directly coating the second shell layer intermediate, and keeping other raw materials and operation unchanged to prepare the PBAT mulching film.

Comparative example 4

Referring to the method of example 1, except that the modified filler was prepared using only lactide for the second shell and glycolide for the second shell.

The PBAT mulching film is prepared by replacing a modified filler with a light-oxygen degradation agent slow-release effect in a formula with the filler, and keeping other raw materials and operations unchanged.

Comparative example 5

Referring to the method of example 1, except that the modified filler was prepared using glycolide only for the second shell and lactide was omitted.

Comparative example 6

The process of example 1 was followed, except that the modified filler was prepared at a second shell reaction temperature of 100 ℃.

The modified filler with the slow release effect of the photo-oxidative degradation agent in the formula is replaced by the filler prepared in the comparative example, and other raw materials and operations are unchanged, so that the PBAT mulching film is prepared.

Table 1 degradation time test results of the mulching films prepared in examples and comparative examples

Note: the degradation completion time is the time required for the mulching film to degrade into pieces with a size of less than 2mm by 2mm from the beginning of the mulching film laying.

As can be seen from the test results of the examples 1 to 5 and the comparative examples 1 to 6 in the table 1, the figure 2 and the figure 3, the PBAT mulching film with the controllable degradation rate can reasonably control the degradation period of the mulching film, namely, the mulching film can maintain good mechanical strength in the growth process of crops and can be rapidly degraded after being used up, so that the adverse effects on the soil quality and the growth of the crops in the next year can be avoided.

Claims

1. A modified filler with a light-oxygen degradation agent slow release effect is characterized in that the modified filler has a core-shell structure and sequentially comprises a core layer, a first shell layer and a second shell layer from inside to outside; the core layer is a porous filler adsorbed with a degradation agent, the first shell layer is a polyol esterified substance, the second shell layer is a polylactic acid-glycolic acid copolymer, and the layers are connected through covalent bonds.

2. The modified filler of claim 1, wherein the core layer size is 2000-10000 mesh, preferably 4000-8000 mesh; the thickness of the first shell layer is 0.05-0.25 μm, preferably 0.1-0.2 μm; the thickness of the second shell layer is 0.1-0.5 μm, preferably 0.2-0.4 μm;

the porous filler contained in the core layer is a porous filler containing carboxyl, and the carboxyl in the porous filler containing carboxyl and the polyol are subjected to esterification reaction under the action of a catalyst to prepare a polyol esterified substance of a first shell layer;

the polylactic acid-glycolic acid copolymer of the second shell layer is prepared by taking hydroxyl in the first shell layer as an initiating group and lactide and glycolide as comonomers through ring-opening polymerization reaction.

3. The modified filler according to claim 1 or 2, characterized in that the raw materials comprise, in parts by mass:

porous filler: 100 parts of (A);

a degradation agent: 20-30 parts, preferably 22-28 parts;

polyol: 10-30 parts, preferably 15-20 parts;

catalyst: 0.01 to 0.05 part, preferably 0.02 to 0.04 part;

lactide: 10-30 parts, preferably 15-20 parts;

glycolide: 10-30 parts, preferably 15-25 parts.

4. The modified filler according to any one of claims 1 to 3, characterized in that the porous filler is selected from porous fillers containing carboxyl groups; preferably, the carboxyl group content is from 0.2 to 1.5mmol/g, preferably from 0.5 to 1.0 mmol/g;

preferably, the particle size of the porous filler is 2000-10000 meshes, preferably 4000-8000 meshes, and the porosity is 60-90%, preferably 70-80%;

preferably, the porous filler is selected from any one of or a combination of at least two of carboxyl-containing diatomite, carboxyl-containing montmorillonite; and/or

The degradation agent is selected from any one or combination of at least two of transition metal compounds and benzophenone compounds, and is preferably manganese stearate and/or tetramethyl-4, 4-diaminobenzophenone; and/or

The polyalcohol is selected from fatty alcohol with carbon chain carbon number less than or equal to 5 and hydroxyl functionality of 2-5, preferably ethylene glycol and/or glycerol; and/or

The catalyst is selected from any one or combination of at least two of hydrous sulfate, preferably any one or combination of at least two of nickel sulfate hexahydrate, ferric sulfate monohydrate and zinc sulfate heptahydrate.

5. A method for preparing the modified filler with the slow release effect of the photo-oxygen degradation agent as claimed in any one of claims 1 to 4, wherein the method comprises the following steps:

6. The process according to claim 5, wherein in step 1), the mixing is carried out at a temperature of 5 to 50 ℃, preferably 20 to 35 ℃, for a time of 0.5 to 3 hours, preferably 1 to 2 hours;

the mixing is carried out in a mixer, the stirring speed is 1500 ℃ per minute, preferably 800 ℃ per minute and 1200 ℃ per minute, and a double-helix mixer is preferably adopted; and/or

In the step 2), the reaction is carried out at the temperature of 150-200 ℃, preferably 170-180 ℃ for 4-8h, preferably 5-7 h;

the reaction is carried out under the condition of stirring, and the stirring speed is 500-1000rpm, preferably 700-800 rpm; and/or

In the step 2), the vacuum dehydration is carried out, wherein the vacuum degree is 0.001-0.01 MPa; the dehydration temperature is 150-200 ℃, preferably 170-180 ℃, and the dehydration time is 1-3h, preferably 1.5-2.5 h; and/or

In the step 3), the temperature of the copolymerization reaction is 150-170 ℃, preferably 155-165 ℃, and the time is 8-10h, preferably 8.5-9.5 h.

7. A PBAT mulching film with controllable degradation rate is characterized in that the raw material comprises the modified filler with the slow release effect of the photo-oxidative degradation agent in any one of claims 1-4 or the modified filler with the slow release effect of the photo-oxidative degradation agent prepared by the method in claim 5 or 6, and the raw material comprises the following components in parts by weight:

PBAT: 100 parts of (A);

anti-UV auxiliary agent: 0.1 to 5 parts, preferably 1 to 3 parts;

compatibilizer: 0.1 to 5 parts, preferably 0.5 to 3 parts.

8. The PBAT mulching film with the controllable degradation rate according to claim 7, wherein the PBAT melt index is 2-10g/10min, preferably 4-6g/10 min;

the anti-UV auxiliary agent is selected from any one or the combination of at least two of o-hydroxybenzophenone, benzotriazole, salicylate and triazine, preferably any one or the combination of at least two of benzotriazole, 2-hydroxy-4-n-octoxybenzophenone and ethylhexyl salicylate;

the compatibilizer is one or a combination of at least two of epoxy, maleic anhydride, acrylate, silane coupling agent and phthalate ester.

9. The PBAT geomembrane of claim 7 or 8, wherein said geomembrane has a thickness of 0.006-0.030mm and a width of 40-200 cm;

the initial degradation time of the mulching film is 50-100 days.

10. The preparation method of the PBAT mulching film with the controllable degradation rate of any one of claims 7 to 9 is characterized by comprising the following steps:

s2, feeding the master batches into a single-screw film blowing machine to blow a film to prepare a PBAT (poly (butylene adipate-co-terephthalate)) mulching film with a controllable degradation rate;

preferably, the melt blending temperature in step S1 is 150-180 ℃;

preferably, the film blowing temperature in step S2 is 150-170 ℃.