A biodegradable film for water-based ink quick and firm printing and a preparation method thereof

Abstract

The application provides a biodegradable film composition for water-based ink fast and firm printing and a preparation method thereof. The composition comprises the following components: a modified material for a biodegradable film and modified water-absorbing resin powder. The modified material comprises the following components: a graft-modified PBAT resin, a PLA resin, a mineral powder and a slip agent, wherein the graft-modified PBAT resin is a hydrophilic polyhydric alcohol graft-modified PBAT resin. The modified water-absorbing resin powder is a water-absorbing resin powder adsorbing a foaming agent and distilled water. The above composition is extruded, plasticized and blown into a film, and then a hydrophilic polyhydric alcohol chain structure is introduced into the film by the hydrophilic polyhydric alcohol graft-modified PBAT method. After the film is blown, the polyhydric alcohol chain structure is easily migrated to the surface of the material, the hydrophilic property of the surface of the material is improved, the spreading property and adhesion in the water-based ink printing process are improved, the problems of slow drying and poor adhesion in traditional water-based ink printing are avoided, and the green water-based ink is facilitated to be widely used.

Description

Technical Field

[0001] This invention belongs to the field of biodegradable plastics, and particularly relates to a biodegradable film composition for rapid and firm printing with water-based ink and its preparation method. Background Technology

[0002] Biodegradable polyester film is currently one of the important application areas for biodegradable polyester, mainly including food bags, garbage bags, shopping bags, and agricultural films. In the blow molding process of biodegradable polyester film, printing is usually required to print the desired labels and markings on the film. Traditional oil-based inks, due to their volatile organic solvents and harmful metals, have a strong odor, permeating the entire production workshop and posing significant harm to the environment and human health during production and use. Therefore, oil-based inks used for printing on film bags are gradually being replaced by water-based inks. However, because water-based inks have relatively poor adhesion compared to oil-based inks, problems such as poor printing adhesion and color fading often occur during water-based ink printing (the ink does not fully adhere to the film, or the adhesion strength is insufficient), resulting in poor printability of the film.

[0003] Chinese patents CN105585823A and CN105585826A disclose a biodegradable polyester composition with excellent printability. By adding trace amounts of tetrahydrofuran and cyclopentanone, the printing defects of the biodegradable polyester composition can be improved during the printing process. However, tetrahydrofuran and cyclopentanone are typical volatile substances and do not conform to the concept and practice of low-carbon and green environmental protection. Chinese patent CN114085498A discloses a biodegradable film bag that does not fade when printed with water-based ink and its preparation method. Through the combination of lubricants and emulsifiers in the formula, the orientation of hydrophilic and lipophilic groups on the film surface is promoted, resulting in different orientations on the front and back sides of the blown film and corona-treated film. The side with the hydrophilic groups facing is used as the side for printing water-based ink, thereby achieving sufficient contact between the water-based ink and the film surface and improving the film bag's adsorption of water-based ink.

[0004] Currently, the main solution to the problem of water-based ink fading on biodegradable film bags is to research and improve the formulation of water-based inks. The fading of water-based inks on biodegradable film bags is related to the composition, polarity, and adhesion of both the water-based ink and the biodegradable film bag. Summary of the Invention

[0005] The purpose of this invention is to provide a composite material for biodegradable films that allows for rapid and secure printing with water-based inks. This composite material solves the problem of color fading when printing with water-based inks on biodegradable film bags. The water-based inks can be printed quickly and securely, avoiding the slow drying and poor adhesion issues of traditional water-based inks, and can promote the widespread use of green water-based inks.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A composition for rapid and durable printing of biodegradable films using water-based inks, the composition comprising the following components:

[0008] 92-99 parts of modified material for biodegradable membranes, preferably 94-98 parts;

[0009] 1-8 parts of modified water-absorbing resin powder, preferably 2-6 parts;

[0010] The modified water-absorbing resin powder is a modified water-absorbing resin powder that adsorbs foaming agent and water.

[0011] In one embodiment of the present invention, the raw materials for preparing the modified water-absorbing resin powder include:

[0012] 95-99 parts of water-absorbing resin powder, preferably 96-98 parts;

[0013] 1-5 parts of foaming agent, preferably 2-4 parts;

[0014] 2-10 parts distilled water, preferably 4-8 parts.

[0015] In one embodiment of the present invention, the water-absorbing resin is a water-absorbing resin containing metal salts and / or oxygen-containing groups, preferably one or more of potassium polypropionate, sodium polypropionate, polyvinyl alcohol, polyacrylamide, and polyoxyethylene; preferably, the water-absorbing resin is ground into water-absorbing resin powder for use, with a particle size D97 of less than 20 μm, preferably a particle size D97 of less than 8 μm, and a salt water absorption ratio of ≥10 times.

[0016] In one embodiment of the present invention, the foaming agent is a foaming agent containing bicarbonate groups, preferably a water-soluble foaming agent of sodium bicarbonate and / or ammonium bicarbonate.

[0017] In one embodiment of the present invention, the modified water-absorbing resin powder is prepared by mixing water-absorbing resin powder with water-soluble foaming agent powder, adding water, and drying to obtain modified water-absorbing resin powder; preferably, the moisture content of the modified water-absorbing resin powder after drying is 0.5wt%-3wt%.

[0018] In one embodiment of the present invention, the modified material for the biodegradable membrane comprises the following components:

[0019]

[0020] In one embodiment of the present invention, the preparation method of the modified material for biodegradable membrane includes the following steps: adding grafted modified PBAT resin, PLA resin, mineral powder, and slip agent to a twin-screw extruder, extruding and pelletizing to obtain the modified material for biodegradable membrane; preferably, the twin-screw extruder has an aspect ratio of 48:1-58:1, a screw speed of 300-500 rpm, and an extrusion temperature of 150℃-170℃.

[0021] In one embodiment of the present invention, the grafted modified PBAT resin is a hydrophilic polyol grafted modified PBAT resin; preferably, the grafted modified PBAT resin is prepared by grafting polyol and PBAT resin through a chain extender.

[0022] In one embodiment of the present invention, the raw materials for preparing the grafted modified PBAT resin include:

[0023] 85-95 parts of PBAT resin, preferably 88-93 parts;

[0024] 5-15 parts of polyol, preferably 7-12 parts;

[0025] Chain extender: 0.2-0.8 parts, preferably 0.3-0.6 parts;

[0026] Preferably, the PBAT resin has a melt index of 3-25 g / 10 min, and the test conditions are 190℃ and 2.16 kg; the PLA resin has a melt index of 3-25 g / 10 min, and the test conditions are 190℃ and 2.16 kg; preferably, the polypolyol is one or more of polyglycerol, ethoxylated polyglycerol, polyethylene glycol, and polyvinyl alcohol; preferably polyethylene glycol; more preferably polyethylene glycol with an average molecular weight of 200-4000, a melting point of -15-55℃, and a relative density of 1.124-1.130; preferably, the chain extender is one or more of styrene-methyl methacrylate-glycidyl methacrylate copolymer, isocyanate, and peroxide, preferably styrene-methyl methacrylate-glycidyl methacrylate copolymer.

[0027] In one embodiment of the present invention, the mineral powder is an inorganic mineral powder containing one or more elements selected from silicon, magnesium, and aluminum, preferably one or more selected from talc, montmorillonite, kaolin, calcium carbonate, and mica.

[0028] In one embodiment of the present invention, the slip agent is a slip agent containing a long-chain organic acid structure, preferably one or more of erucamide, zinc stearate, ethylene bis-stearamide and oxidized polyethylene wax.

[0029] The composition of this invention, after extrusion plasticization and blown film preparation, introduces a hydrophilic polyol chain structure through PBAT graft modification. This chain structure easily migrates to the material surface after blown film preparation, improving the surface hydrophilicity and enhancing the spreadability and adhesion of water-based inks during printing. Simultaneously, during the blown film mixing and plasticization process, the foaming agent in the composition decomposes in situ, and the residual water vaporizes, forming a porous structure around the foaming resin powder. The resulting foaming gas and water vapor volatilization can form microporous channels during the blown film preparation process, promoting rapid penetration of the water-based ink into the substrate material during printing. This allows the solvent in the water-based ink to be quickly adsorbed by the foaming resin, resulting in rapid drying and firm printing. This avoids the problems of slow drying and poor adhesion in traditional water-based ink printing, and is conducive to promoting the widespread use of green water-based inks.

[0030] Compared with the prior art, the present invention has the following positive effects:

[0031] 1) This invention introduces a hydrophilic polyol chain structure by grafting hydrophilic polyols onto PBAT, which significantly increases the dyne value of the film from 32 to 37. Furthermore, as the proportion of grafted material increases, the dyne value further increases to 47. This technical solution can significantly improve the hydrophilicity of the material surface, thereby improving the spreadability and adhesion of the water-based ink printing process.

[0032] 2) This invention uses modified water-absorbing resin powder to enable water-based ink to penetrate rapidly into the matrix material, allowing the solvent in the water-based ink to be quickly adsorbed by the water-absorbing resin. The water-based ink peeling rate is reduced from 32% to 18%, achieving the effect of rapid drying and firm printing. Furthermore, as the content ratio increases, it can be reduced to 6%, and the peeling rate only changes by 1-3% before and after 24 hours, significantly improving the firmness of water-based ink printing.

[0033] 3) The technical solution of the present invention has a significant effect on improving the adhesion of water-based inks on biodegradable film bags, solves the problem of color fading when printing with water-based inks on biodegradable film bags, promotes the combined use of biodegradable film bags and water-based inks, promotes environmental protection in the packaging film bag field, and solves a major obstacle in the mass production application of fully biodegradable materials. Detailed Implementation

[0034] The present invention will be further illustrated below with specific embodiments. These embodiments are merely illustrative and do not limit the scope of the invention.

[0035] The main sources of raw materials in each embodiment and comparative example are shown in Table 1 below:

[0036] Table 1 Sources of Raw Materials

[0037] raw materials factory PBAT (T16), melt index 4g / 10min (190℃, 2.16kg) Wanhua Chemical Polylactic acid (PLA) (FY804) Anhui Fengyuan Futailai Polylactic Acid Co., Ltd. Water-absorbing resin (sodium polyacrylate) Wanhua Chemical (30-200 mesh) Water-absorbing resin (polyacrylamide) Wanhua Chemical (30-200 mesh) talcum powder Liaoning Aihai Talc Co., Ltd. Calcium carbonate Guangxi Kelong Powder Co., Ltd. Lubricants (erucamide, zinc stearate) British Heda Co., Ltd. Chain extender (epoxy chain extender ADR4468) BASF Chain extender (HDI isocyanate) Wanhua Chemical Polyethylene glycol (PEG400) Wanhua Chemical Polyethylene glycol (PEG600) Wanhua Chemical Polyvinyl alcohol (PVA2000) Wanhua Chemical Foaming agents (sodium bicarbonate, ammonium bicarbonate) Beijing Innocare Reagent Co., Ltd.

[0038] Unless otherwise specified, all other raw materials and reagents were obtained through commercially available channels.

[0039] The performance test parameters and corresponding test methods of the PBAT modified materials in each embodiment and comparative example are shown in Table 2 below:

[0040] Table 2 Test Methods

[0041] Test content unit Test methods Melt Flow Index g / 10min ISO 1133 Tensile strength MPa ISO 527-3 Elongation at break ％ ISO 527-3 Dyne value / Dain Pen Printing peel rate ％ GB / T38082-2019

[0042] The processing equipment used is:

[0043] Twin-screw extruder, Coperion, model ZSK 26Mc 18, length-to-diameter ratio 52, screw diameter 26cm;

[0044] Film blowing machine, Zhangjiagang Lianjiang Machinery Co., Ltd., model SCM 25, length-to-diameter ratio 30, screw diameter 25cm.

[0045] The testing equipment used is:

[0046] The test was conducted using a German Gottfert melt indexer at 190°C with a weight of 2.16 kg.

[0047] The German ZWICK universal testing machine has a tensile testing rate of 500 mm / min.

[0048] Cryogenic Grinding Mill: Ultrafine Grinding Mill, CM-500, Shanghai Kangbeili Machinery Equipment Technology Co., Ltd. It uses liquid nitrogen to cool to -100℃, with a rotation speed of 8000 rpm / min, ultimately forming a water-absorbing resin powder with a particle size (D97) of less than 15μm, or a particle size (D97) of less than 5μm.

[0049] The dyne pen, from the German brand Arcotest, has a dyne value between 28 and 60.

[0050] For the ink peel rate test, referencing GB / T38082-2019 standard, samples are cut from areas of the bag with significant ink coverage for the printing peel rate test. The printed side of the sample is facing upwards. The sample is fixed to a smooth surface with transparent tape, exposing a 100mm x 100mm test area. During the operation, do not touch the measurement area with your hands. Use adhesive tape with a peel strength of 6.5N / 15mm ± 1.0N / 15mm, 15mm wide and 175mm long, and apply it to the printed surface of the sample. Fold it 180° at 75mm and roll it back and forth once with a 1kg roller. Then, quickly peel it off by hand. After peeling, use a 0.5mm graduated steel ruler to measure the peeled area and residual area of ​​the ink, and calculate the ink peel rate according to the formula.

[0051] Calculation formula: Lc=Sb / St*100%, where Lc is the peeling rate of water-based ink after printing and standing for c hours, Sb is the peeling area, and St is the total test area.

[0052] Example 1

[0053] (1) First, weigh 86.45 kg of PBAT resin, 4.55 kg of polyethylene glycol (PEG-300, molecular weight 300) and 0.182 kg of chain extender (HDI) according to the ratio of 95:5:0.2. After mixing evenly with a MIXER stirrer, melt blending and grafting are carried out through a twin-screw extruder (300 rpm, 160℃) to obtain grafted modified PBAT resin.

[0054] (2) Add the above 91kg grafted modified PBAT resin, 3kg PLA resin, 5kg calcium carbonate and 0.2kg erucamide to the MIXER mixer and mix at a stirring speed of 600rpm / min for 4min until uniform. Then feed the mixture into a twin-screw extruder (400 rpm, 160℃) via the main feed method. After extrusion, use air-cooled strip cutting to obtain the modified material for biodegradable membrane.

[0055] (3) Mix 0.99 kg of water-absorbing resin powder (sodium polyacrylate, particle size (D97) less than 15 μm) with 0.01 kg of water-soluble foaming agent powder sodium bicarbonate. During the mixing process, add 0.02 kg of water in the form of a mist by spraying. Then freeze-dry for 24 h to obtain modified water-absorbing resin powder.

[0056] (4) Add the above 99kg of biodegradable membrane modified material and 1kg of modified water-absorbing resin powder to a high-speed mixer and stir at a stirring speed of 300rpm / min for 4min to mix evenly. The combined material is poured into a blown film machine for plasticizing extrusion blown film (temperature 150℃, capacity 20kg). Mechanical tests and water-based ink printing evaluation are performed. The results are shown in Table 3.

[0057] Example 2

[0058] (1) First, weigh 77.19 kg of PBAT resin, 5.81 kg of polyethylene glycol (PEG-300, molecular weight 300) and 0.249 kg of chain extender (epoxy chain extender ADR4468) according to the ratio of 93:7:0.3. After mixing evenly with a MIXER stirrer, melt blending and grafting are carried out through a twin-screw extruder (300 rpm, 160℃) to obtain grafted modified PBAT resin.

[0059] (2) Add the above 83kg grafted modified PBAT resin, 5kg PLA resin, 10kg talc powder and 0.3kg erucamide to the MIXER mixer and mix at a stirring speed of 600rpm / min for 4min until uniform. Then feed the mixture into a twin-screw extruder (300 rpm, 170℃) via the main feeding method. After extrusion, use air-cooled strip cutting to obtain modified material for biodegradable membrane.

[0060] (3) 1.96 kg of water-absorbing resin powder (polyacrylamide, particle size (D97) less than 15 μm) and 0.04 kg of water-soluble foaming agent powder sodium bicarbonate were stirred and mixed evenly. During the stirring process, 0.08 kg of water was added in the form of mist by spraying. Then, the mixture was freeze-dried for 24 h to obtain modified water-absorbing resin powder.

[0061] (4) Add the above 98kg of biodegradable membrane modified material and 2kg of modified water-absorbing resin powder to a high-speed mixer and stir at a stirring speed of 300rpm / min for 4min to mix evenly. The combined material is poured into a blown film machine for plasticizing extrusion blown film (temperature 150℃, capacity 20kg). Mechanical tests and water-based ink printing evaluation are performed. The results are shown in Table 3.

[0062] Example 3

[0063] (1) First, weigh 62.79 kg of PBAT resin, 6.21 kg of polyethylene glycol (PEG-600, molecular weight 600) and 0.345 kg of chain extender (HDI) according to the ratio of 91:9:0.5. After mixing evenly with a MIXER stirrer, melt blending and grafting are carried out through a twin-screw extruder (300 rpm, 160℃) to obtain grafted modified PBAT resin.

[0064] (2) Add the above 69kg grafted modified PBAT resin, 7kg PLA resin, 20kg calcium carbonate and 0.4kg erucamide to the MIXER mixer and mix them evenly at a mixing speed of 600rpm / min for 4min. Then feed the mixture into a twin-screw extruder (600 rpm, 150℃) through the main feeding method. After extrusion, use air-cooled strip cutting to obtain the modified material for biodegradable membrane.

[0065] (3) 3.88 kg of water-absorbing resin powder (sodium polyacrylate, particle size (D97) less than 15 μm) and 0.12 kg of water-soluble foaming agent powder sodium bicarbonate were stirred and mixed evenly. During the stirring process, 0.24 kg of water was added in the form of mist by spraying. Then, the mixture was freeze-dried for 24 h to obtain modified water-absorbing resin powder.

[0066] (4) Add the above 96kg of biodegradable membrane modified material and 4kg of modified water-absorbing resin powder to a high-speed mixer and stir at a stirring speed of 300rpm / min for 4min to mix evenly. The combined material is poured into a blown film machine for plasticizing, extrusion and blown film (blown film temperature 150℃, production capacity 20kg). Mechanical tests and water-based ink printing evaluation are performed. The results are shown in Table 3.

[0067] Example 4

[0068] (1) First, weigh 48.4 kg of PBAT resin, 6.6 kg of polyethylene glycol (PVA-2000, molecular weight 2000) and 0.33 kg of chain extender (HDI) according to the ratio of 88:12:0.6. After mixing evenly with a MIXER stirrer, melt blending and grafting are carried out through a twin-screw extruder (300 rpm, 160℃) to obtain grafted modified PBAT resin.

[0069] (2) Add the above 55kg grafted modified PBAT resin, 9kg PLA resin, 30kg calcium carbonate and 0.5kg erucamide to the MIXER mixer and mix at a stirring speed of 600rpm / min for 4min until uniform. Then feed the mixture into a twin-screw extruder (400 rpm, 160℃) via the main feeding method. After extrusion, use air-cooled strip cutting to obtain the modified material for biodegradable membrane.

[0070] (3) 5.76 kg of water-absorbing resin powder (sodium polyacrylate, particle size (D97) less than 15 μm) and 0.24 kg of water-soluble foaming agent powder sodium bicarbonate were stirred and mixed evenly. During the stirring process, 0.48 kg of water was added in the form of mist by spraying. Then, the mixture was freeze-dried for 24 h to obtain modified water-absorbing resin powder.

[0071] (4) Add the above 94kg of biodegradable membrane modified material and 6kg of modified water-absorbing resin powder to a high-speed mixer and stir at a stirring speed of 300rpm / min for 4min to mix evenly. The combined material is poured into a blown film machine for plasticizing, extrusion and blown film (blown film temperature 150℃, production capacity 20kg). Mechanical tests and water-based ink printing evaluation are performed. The results are shown in Table 3.

[0072] Example 5

[0073] (1) First, weigh 38.25 kg of PBAT resin, 6.75 kg of polyethylene glycol (PEG-300, molecular weight 300) and 0.36 kg of chain extender (HDI) according to the mass ratio of 85:15:0.8. After mixing evenly with a MIXER stirrer, melt blending and grafting are carried out through a twin-screw extruder (300 rpm, 160℃) to obtain grafted modified PBAT resin.

[0074] (2) Add the above 45kg grafted modified PBAT resin, 12kg PLA resin, 35kg calcium carbonate and 0.6kg zinc stearate to the MIXER mixer and mix at a stirring speed of 600rpm / min for 4min until uniform. Then feed the mixture into a twin-screw extruder (400 rpm, 160℃) via the main feeding method. After extrusion, use air-cooled strip cutting to obtain the modified material for biodegradable membrane.

[0075] (3) 7.6 kg of water-absorbing resin powder (sodium polyacrylate, particle size (D97) less than 5 μm) and 0.4 kg of water-soluble foaming agent powder ammonium bicarbonate were stirred and mixed evenly. During the stirring process, 0.8 kg of water was added in the form of mist by spraying. Then, the mixture was freeze-dried for 24 h to obtain modified water-absorbing resin powder.

[0076] (4) Add the above 92kg of biodegradable membrane modified material and 8kg of modified water-absorbing resin powder to a high-speed mixer and stir at a stirring speed of 300rpm / min for 4min to mix evenly. The combined material is poured into a blown film machine for plasticizing, extrusion and blown film (blown film temperature 150℃, production capacity 20kg). Mechanical tests and water-based ink printing evaluation are performed. The results are shown in Table 3.

[0077] Comparative Example 1

[0078] The difference between this comparative example and Example 1 is that this comparative example uses unmodified water-absorbing resin powder.

[0079] (1) First, weigh 86.45 kg of PBAT resin, 4.55 kg of polyethylene glycol (PEG-400, molecular weight 300) and 0.182 kg of chain extender (HDI) according to the ratio of 95:5:0.2. After mixing evenly with a MIXER stirrer, melt blending and grafting are carried out through a twin-screw extruder (300 rpm, 160℃) to obtain grafted modified PBAT resin.

[0080] (2) Add the above 91kg grafted modified PBAT resin, 3kg PLA resin, 5kg calcium carbonate and 0.2kg slip agent into the MIXER mixer, stir at 600rpm / min for 4min to mix evenly, and add it into the twin-screw extruder (400 rpm, 160℃) by the main feeding method. After extrusion, use air-cooled stringing and pelletizing to obtain the modified material for biodegradable membrane.

[0081] (3) Add the above 99kg of biodegradable membrane modified material and 1kg of water-absorbing resin powder (sodium polyacrylate) to a high-speed mixer and mix at a stirring speed of 300rpm / min for 4min to form a composite material. Pour the composite material into a blown film machine for plasticizing, extrusion and blown film (blown film temperature 150℃, production capacity 20kg). Mechanical tests and water-based ink printing evaluation were conducted. The results are shown in Table 3.

[0082] Comparative Example 2

[0083] This comparative example differs from Example 1 in that it does not use foaming agent powder.

[0084] (1) First, weigh 86.45 kg of PBAT resin, 4.55 kg of polyethylene glycol (PEG-400, molecular weight 300) and 0.182 kg of chain extender (HDI) according to the ratio of 95:5:0.2. After mixing evenly with a MIXER stirrer, melt blending and grafting are carried out through a twin-screw extruder (300 rpm, 160℃) to obtain grafted modified PBAT resin.

[0085] (2) Add the above 91kg grafted modified PBAT resin, 3kg PLA resin, 5kg calcium carbonate and 0.2kg slip agent into the MIXER mixer, stir at 600rpm / min for 4min to mix evenly, add to the twin screw extruder by main feeding, and after extrusion, use air cooling to granulate to obtain the modified material for biodegradable membrane.

[0086] (3) 0.99 kg of water-absorbing resin powder (sodium polyacrylate) was added to 0.02 kg of water in the form of a mist by spraying during the stirring process, and then freeze-dried for 24 h to obtain the treated water-absorbing resin powder.

[0087] (4) Add the above 99kg of biodegradable membrane modified material and 1kg of modified water-absorbing resin powder to a high-speed mixer and stir at a stirring speed of 300rpm / min for 4min to mix evenly. The combined material is poured into a blown film machine for plasticizing, extrusion and blown film (blown film temperature 150℃, production capacity 20kg). Mechanical tests and water-based ink printing evaluation are performed. The results are shown in Table 3.

[0088] Comparative Example 3

[0089] The difference between this comparative example and Example 1 is that this comparative example uses ungrafted modified PBAT resin as a comparative reference.

[0090] (1) Add 91kg PBAT resin, 3kg PLA resin, 5kg calcium carbonate and 0.2kg slip agent to the MIXER mixer and mix at a stirring speed of 600rpm / min for 4min until uniform. Then add it to the twin-screw extruder through the main feeding method. After extrusion, use air-cooled strip cutting to obtain the modified material for biodegradable membrane.

[0091] (2) Mix 0.99 kg of water-absorbing resin powder (sodium polyacrylate) with 0.01 kg of water-soluble foaming agent powder sodium bicarbonate evenly. During the mixing process, add 0.02 kg of water in the form of mist by spraying. Then freeze-dry for 24 hours to obtain modified water-absorbing resin powder.

[0092] (3) Add the above 99kg of biodegradable membrane modified material and 1kg of modified water-absorbing resin powder to a high-speed mixer and stir at a stirring speed of 300rpm / min for 4min to mix evenly. The combined material is poured into a blown film machine for plasticizing, extrusion and blown film (blown film temperature 150℃, production capacity 20kg). Mechanical tests and water-based ink printing evaluation are performed. The results are shown in Table 3.

[0093] Table 3. Performance test results of products in Examples 1-5 (S1-S5) and Comparative Examples 1-3 (D1-D3)

[0094]

[0095] Compared with Comparative Example 1, Example 1 shows that the introduction of a grafted hydrophilic polyol structure significantly improves the dyne value of the film, increasing it from 32 to 37. Furthermore, with an increase in the proportion of grafted material, the dyne value further increases to 47. This technique can significantly improve the hydrophilicity of the material surface, thereby improving the spreadability and adhesion of the water-based ink printing process. Modifying the water-absorbing resin powder allows for rapid penetration of the ink into the matrix material, enabling the solvent in the ink to be quickly adsorbed by the water-absorbing resin. The ink peeling rate decreases from 32% to 18%, achieving rapid drying and strong printing. Moreover, with increasing content, it can be reduced to 6%, and the peeling rate only changes by 1-3% after 24 hours, significantly improving the ink printing adhesion. Examples 1-5 demonstrate the significantly superior dyne value and water-based ink printing performance of the modified PBAT material.

[0096] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention.

Claims

1. A composition for biodegradable films that allow for rapid and firm printing with water-based inks, characterized in that, The compound comprises the following components: 92-99 parts of modified material for biodegradable membranes; 1-8 parts of modified water-absorbing resin powder; The modified water-absorbing resin powder is a modified water-absorbing resin powder that adsorbs foaming agent and water. The modified material for the biodegradable membrane includes: grafted modified PBAT resin, PLA resin, mineral powder, and slip agent. The grafted modified PBAT resin is a hydrophilic polyol grafted modified PBAT resin. The grafted modified PBAT resin is prepared by grafting polyol and PBAT resin with a chain extender.

2. The composite material according to claim 1, characterized in that, The compound comprises the following components: 94-98 parts of modified material for biodegradable membranes; 2-6 parts of modified water-absorbing resin powder.

3. The composite material according to claim 1, characterized in that, The raw materials for preparing the modified water-absorbing resin powder include: 95-99 parts of water-absorbing resin powder; 1-5 parts foaming agent; 2-10 parts distilled water.

4. The composite material according to claim 3, characterized in that, The raw materials for preparing the modified water-absorbing resin powder include: 96-98 parts of water-absorbing resin powder; 2-4 parts foaming agent; 4-8 parts distilled water.

5. The composite material according to claim 3, characterized in that, The water-absorbing resin is a water-absorbing resin containing metal salts and / or oxygen-containing groups; And / or, the foaming agent is a foaming agent containing bicarbonate groups.

6. The composite material according to claim 5, characterized in that, The water-absorbing resin is one or more of potassium polypropionate, sodium polypropionate, polyvinyl alcohol, polyacrylamide, and polyethylene oxide; The water-absorbing resin is ground into water-absorbing resin powder for use, with a particle size D97 of less than 20μm and a salt water absorption rate of ≥10 times. And / or, the foaming agent is a water-soluble foaming agent of sodium bicarbonate and / or ammonium bicarbonate.

7. The composite material according to claim 6, characterized in that, The particle size D97 of the water-absorbing resin is less than 8 μm.

8. The composite material according to claim 1, characterized in that, The modified water-absorbing resin powder is prepared by mixing water-absorbing resin powder with water-soluble foaming agent powder, adding water, and drying to obtain modified water-absorbing resin powder.

9. The composite material according to claim 8, characterized in that, The moisture content of the modified water-absorbing resin powder after drying is 0.5wt%-3wt%.

10. The composite material according to claim 1, characterized in that, The modified material for the biodegradable membrane comprises the following components:

11. The composite material according to claim 10, characterized in that, The modified material for the biodegradable membrane comprises the following components:

12. The composite material according to claim 10, characterized in that, The preparation method of the modified material for biodegradable membranes includes the following steps: adding grafted modified PBAT resin, PLA resin, mineral powder, and slip agent into a twin-screw extruder, extruding into strands and pelletizing to obtain the modified material for biodegradable membranes.

13. The composite material according to claim 12, characterized in that, The twin-screw extruder has a length-to-diameter ratio of 48:1-58:1, a screw speed of 300-500 rpm, and an extrusion temperature of 150℃-170℃.

14. The compound according to claim 13, characterized in that, The raw materials for preparing the grafted modified PBAT resin include: 85-95 parts of PBAT resin; 5-15 parts of polyol; Chain extender 0.2-0.8 parts.

15. The compound according to claim 14, characterized in that, The raw materials for preparing the grafted modified PBAT resin include: 88-93 parts of PBAT resin; 7-12 parts of polyol; Chain extender 0.3-0.6 parts; The PBAT resin has a melt index of 3-25 g / 10 min, and the test conditions are 190℃ and 2.16 kg; the PLA resin has a melt index of 3-25 g / 10 min, and the test conditions are 190℃ and 2.16 kg. The polyol is one or more of polyglycerol, ethoxylated polyglycerol, polyethylene glycol, and polyvinyl alcohol; The chain extender is one or more of styrene-methyl methacrylate-methyl methacrylate glycidyl ester copolymer, isocyanate, and peroxide.

16. The compound according to claim 15, characterized in that, The polyol mentioned is polyethylene glycol; The chain extender is a styrene-methyl methacrylate-methyl methacrylate glycidyl ester copolymer.

17. The composite material according to claim 16, characterized in that, The polyol mentioned is polyethylene glycol with an average molecular weight of 200-4000, a melting point of -15-55℃, and a relative density of 1.124-1.

130.

18. The compound according to claim 10, characterized in that, The mineral powder is an inorganic mineral powder containing one or more elements selected from silicon, magnesium, and aluminum.

19. The compound according to claim 18, characterized in that, The mineral powder is one or more of the following: talc, montmorillonite, kaolin, calcium carbonate, and mica.

20. The composite material according to claim 10, characterized in that, The aforementioned slip agent is a slip agent containing a long-chain organic acid structure.

21. The composite material according to claim 20, characterized in that, The slip agent is one or more of erucamide, zinc stearate, ethylene bis-stearamide, and oxidized polyethylene wax.

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