A stretch film for medical supplies and a method for manufacturing the same

Abstract

The present application relates to the technical field of stretch film, and particularly relates to a stretch film for medical accessories and a preparation method thereof.The stretch film for medical accessories comprises a middle layer, an upper surface layer covering one side of the middle layer, and a lower surface layer covering the other side of the middle layer; the raw materials of the upper surface layer comprise, by mass fraction, polylactic acid 60-100, polybutylene adipate terephthalate 10-20, activated graphene 5-10, functional master batch 2-8, and a compatibilizer 1-2; the raw materials of the middle layer comprise, by mass fraction, polyhydroxybutyrate 40-60, branched starch 20-40, amino-terminated polyamide amine 1-2, and a compatibilizer 1-2; and the raw materials of the lower surface layer comprise, by mass fraction, polylactic acid 60-100, polybutylene succinate 10-20, activated graphene 5-15, functional master batch 1-10, and a compatibilizer 1-2.The present application can be degraded under natural conditions, has more excellent barrier properties, and has good mechanical properties.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of stretch film, in particular to a stretch film for medical accessories and a preparation method thereof. BACKGROUND

[0002] Plastic films play a major role in all aspects of human society, such as medical accessories. However, a large number of film products are used as medical accessories and are discarded after being used once, and the bulk film materials such as polyethylene, polypropylene, polyethylene terephthalate are difficult to degrade in the natural environment, and the long-term accumulation has caused serious "white pollution" problem, which destroys the ecological environment.

[0003] At present, using biodegradable plastics to replace traditional non-degradable plastics is an important way to solve the pollution of films. In the field of medical accessories, gas barrier property is very important, especially the prevention of water vapor and oxygen penetration, which can play a role in oxidation resistance, corrosion prevention, moisture prevention, etc. However, the gas barrier property of the biodegradable films developed at present is often poor; but the high barrier film materials commonly used in industry are difficult to biodegrade.

[0004] Two-dimensional nanosheets have high specific surface area and high length-thickness ratio, and also have good gas barrier property such as oxygen and water vapor. If two-dimensional nanosheets are introduced into the interior or surface of biodegradable film and realize ordered orientation, the gas barrier property of the film can be greatly improved.

[0005] Therefore, how to obtain a biodegradable stretch film for medical accessories which not only has good biodegradability and mechanical property, but also has good barrier property, has become a problem to be solved at present. SUMMARY

[0006] The purpose of the present application is to solve the problems existing in the prior art, and to provide a stretch film for medical accessories and a preparation method thereof.

[0007] A stretch film for medical accessories comprises an intermediate layer, an upper surface layer covering one side of the intermediate layer, and a lower surface layer covering the other side of the intermediate layer; the raw materials of the upper surface layer comprise, by mass fraction: 60-100 parts of polylactic acid, 10-20 parts of polybutylene adipate terephthalate, 5-10 parts of activated graphene, 2-8 parts of functional masterbatch, and 1-2 parts of compatibilizer; the raw materials of the intermediate layer comprise, by mass fraction: 40-60 parts of polyhydroxybutyrate, 20-40 parts of branched starch, 1-2 parts of amino-terminated polyamide amine, and 1-2 parts of compatibilizer; and the raw materials of the lower surface layer comprise, by mass fraction: 60-100 parts of polylactic acid, 10-20 parts of polybutylene succinate, 5-15 parts of activated graphene, 1-10 parts of functional masterbatch, and 1-2 parts of compatibilizer.

[0008] Preferably, the compatible agent is maleic anhydride or / and glycidyl methacrylate.

[0009] Preferably, the functional masterbatch comprises, by mass fraction: polylactic acid 80-100 parts, lubricant 1-3 parts, opening agent 4-8 parts, antioxidant 1-3 parts.

[0010] More preferably, the functional masterbatch is prepared by the following steps: mixing polylactic acid, lubricant, opening agent and antioxidant uniformly, extruding at 190-210 DEG C, cooling and drying.

[0011] More preferably, the lubricant is at least one of ethylene bis-stearamide, oleic acid amide and erucic acid amide.

[0012] More preferably, the opening agent is at least one of talc, diatomite, kaolin and calcium carbonate.

[0013] More preferably, the antioxidant comprises: antioxidant 1076 and antioxidant 626, and the mass ratio of antioxidant 1076 to antioxidant 626 is 1:1-2.

[0014] Preferably, the activated graphene is prepared by the following steps: mixing graphene, organic amine surfactant and dispersant uniformly, adding polylactic acid thereto, extruding at 190-210 DEG C and drying.

[0015] More preferably, the mass ratio of graphene, organic amine surfactant, dispersant and polylactic acid is 10-20:1-2:1-2:30-60.

[0016] More preferably, the surfactant is polyethylene imine, and the dispersant is polyvinylpyrrolidone.

[0017] The above medical auxiliary material stretch film preparation method comprises the following steps:

[0018] S1, the raw materials of the upper layer, the middle layer and the lower layer are mixed respectively, and then three-layer co-extrusion is carried out to obtain a melt;

[0019] S2, the melt is attached to a cold drum to form a thick sheet, and then synchronous bidirectional stretching is carried out, the stretching temperature is 120-140 DEG C, the bidirectional stretching ratio is 2-4x2-4, and a preformed film is obtained;

[0020] S3, the preformed film is shaped at 160-170 DEG C for 4-10 s, and then cooled and subjected to corona treatment. Advantages

[0021] The application effectively improves the biodegradability of medical auxiliary material, reduces the influence of medical material on the environment, and realizes performance complementation among the components through the compounding of the upper layer, the middle layer and the lower layer, and the layer structure design is reasonable.

[0022] The application adopts polylactic acid and activated graphene, polybutylene adipate-co-hexanoate, has excellent toughness, and adds branched starch in the middle layer, effectively reduces the cost, cooperates with the action of terminal amino polyamide, forms a three-dimensional network structure after blending, better improves the melt strength, can greatly improve the tensile properties of the material, especially the low temperature tensile properties, cooperates with the upper surface layer and the lower surface layer, the film stability is excellent, has better durability.

[0023] The film of the application adopts degradable raw materials, can be degraded under natural conditions, effectively solves the problem of white pollution, has more excellent barrier properties, and has good mechanical properties, and is suitable for medical accessories. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The tensile strength comparison chart of the tensile film obtained from example 5 and comparative examples 1-2.

[0025] Figure 2 The barrier property comparison chart of the tensile film obtained from example 5 and comparative examples 1-2. DETAILED DESCRIPTION

[0026] The application will be further described below in combination with specific examples.

[0027] Example 1

[0028] A tensile film of a medical accessory, comprising: a middle layer, an upper surface layer covering one side of the middle layer, and a lower surface layer covering the other side of the middle layer.

[0029] The raw materials of the upper surface layer include: polylactic acid 60g, polybutylene adipate-co-hexanoate 10g, activated graphene 5g, functional master batch 2g, and glycidyl methacrylate 1g.

[0030] The raw materials of the middle layer include: polyhydroxybutyrate 40g, branched starch 20g, 2.0 generation terminal amino polyamide 1g, and glycidyl methacrylate 1g.

[0031] The raw materials of the lower surface layer include: polylactic acid 60g, polybutylene succinate 10g, activated graphene 5g, functional master batch 1g, and glycidyl methacrylate 1g.

[0032] The functional master batch is prepared by the following steps: 80 g of polylactic acid, 1 g of oleic acid amide, 4 g of calcium carbonate, 0.5 g of antioxidant 1076, and 0.5 g of antioxidant 626 are uniformly mixed, and then fed into a double-screw extruder for extrusion at 190°C, and then cooled after drawing, granulated, and dried. The activated graphene is prepared by the following steps: 10 g of graphene, 1 g of polyethyleneimine, and 1 g of polyvinylpyrrolidone are uniformly mixed, and then 30 g of polylactic acid is added and fed into a double-screw extruder for extrusion at 190°C, and then cooled after drawing, granulated, and dried.

[0033] The method for preparing the stretch film of the medical accessory includes the following steps:

[0034] S1, the raw materials of the upper layer, the middle layer, and the lower layer are mixed respectively, fed into a high-speed stirrer for uniform stirring, and then a three-layer co-extrusion is performed by an extruder to obtain a melt, and the co-extrusion temperature is 180°C;

[0035] S2, the melt is attached to a cold drum with a temperature of 10°C to form a thick sheet, and then synchronous bidirectional stretching is performed, the stretching temperature is 120°C, and the bidirectional stretching ratio is 2x2, to obtain a preformed film;

[0036] S3, the preformed film is shaped at a temperature of 160°C for 4s, and then cooled and subjected to corona treatment.

[0037] Example 2

[0038] A stretch film of a medical accessory includes a middle layer, an upper layer covering one side of the middle layer, and a lower layer covering the other side of the middle layer.

[0039] The raw materials of the upper layer include 100 g of polylactic acid, 20 g of polybutylene adipate terephthalate, 10 g of activated graphene, 8 g of functional master batch, and 2 g of glycidyl methacrylate.

[0040] The raw materials of the middle layer include 60 g of polyhydroxybutyrate, 40 g of branched starch, 2.0 generation of amino-terminated polyamide amine, and 2 g of glycidyl methacrylate.

[0041] The raw materials of the lower layer include 100 g of polylactic acid, 20 g of polybutylene succinate, 15 g of activated graphene, 10 g of functional master batch, and 2 g of glycidyl methacrylate.

[0042] The functional master batch is prepared by the following steps: 100 g of polylactic acid, 3 g of erucic acid amide, 8 g of calcium carbonate, 1 g of antioxidant 1076, and 2 g of antioxidant 626 are uniformly mixed, and then fed into a twin-screw extruder for extrusion at 210°C. After drawing, the mixture is cooled, granulated, and dried. The activated graphene is prepared by the following steps: 20 g of graphene, 2 g of polyethyleneimine, and 2 g of polyvinylpyrrolidone are uniformly mixed, and then 60 g of polylactic acid is added and fed into a twin-screw extruder for extrusion at 210°C. After drawing, the mixture is cooled, granulated, and dried.

[0043] The method for preparing the stretch film of the medical accessory includes the following steps:

[0044] S1, the raw materials of the upper layer, the middle layer, and the lower layer are mixed respectively, fed into a high-speed stirrer for uniform stirring, and then extruded by an extruder to obtain a melt, and the co-extrusion temperature is 200°C;

[0045] S2, the melt is attached to a cold drum at a temperature of 16°C to form a thick sheet, and then bidirectional stretching is performed synchronously, the stretching temperature is 140°C, and the bidirectional stretching ratio is 4×4, to obtain a preformed film;

[0046] S3, the preformed film is shaped at a temperature of 170°C for 10 s, and then cooled and subjected to corona treatment.

[0047] Example 3

[0048] A stretch film of a medical accessory includes a middle layer, an upper layer covering one side of the middle layer, and a lower layer covering the other side of the middle layer.

[0049] The raw materials of the upper layer include 70 g of polylactic acid, 18 g of polybutylene adipate terephthalate, 7 g of activated graphene, 6 g of functional master batch, and 1.2 g of maleic anhydride.

[0050] The raw materials of the middle layer include 55 g of polyhydroxybutyrate, 25 g of branched starch, 1.7 g of 2.0 generation amino-terminated polyamide amine, and 1.2 g of maleic anhydride.

[0051] The raw materials of the lower layer include 90 g of polylactic acid, 13 g of polybutylene succinate, 12 g of activated graphene, 3 g of functional master batch, and 1.8 g of maleic anhydride.

[0052] The functional master batch is prepared by the following steps: 85 g of polylactic acid, 2.5 g of ethylene bis-stearamide, 5 g of talc, 0.9 g of antioxidant 1076, and 1.8 g of antioxidant 626 are uniformly mixed, and then fed into a twin-screw extruder for extrusion at 195°C, and then cooled after drawing, granulated, and dried. The activated graphene is prepared by the following steps: 17 g of graphene, 1.3 g of polyethyleneimine, and 1.8 g of polyvinylpyrrolidone are uniformly mixed, 40 g of polylactic acid is added, and then fed into a twin-screw extruder for extrusion at 205°C, and then cooled after drawing, granulated, and dried.

[0053] The method for preparing the stretch film of the medical accessory includes the following steps:

[0054] S1, the raw materials of the upper layer, the middle layer, and the lower layer are mixed respectively, fed into a high-speed stirrer for uniform stirring, and then a three-layer co-extrusion is performed through an extruder to obtain a melt, and the co-extrusion temperature is 185°C;

[0055] S2, the melt is attached to a cold drum at a temperature of 14°C to form a thick sheet, and then synchronous bidirectional stretching is performed, the stretching temperature is 125°C, the bidirectional stretching ratio is 3.5×2.5, and a preformed film is obtained;

[0056] S3, the preformed film is shaped at a temperature of 168°C for 6s, and then cooled and subjected to corona treatment.

[0057] Example 4

[0058] A stretch film of a medical accessory includes a middle layer, an upper layer covering one side of the middle layer, and a lower layer covering the other side of the middle layer.

[0059] The raw materials of the upper layer include 90 g of polylactic acid, 12 g of polybutylene adipate terephthalate, 9 g of activated graphene, 4 g of functional master batch, and 1.8 g of maleic anhydride.

[0060] The raw materials of the middle layer include 45 g of polyhydroxybutyrate, 35 g of branched starch, 1.3 g of 2.0-generation amino-terminated polyamide amine, and 1.8 g of maleic anhydride.

[0061] The raw materials of the lower layer include 70 g of polylactic acid, 17 g of polybutylene succinate, 8 g of activated graphene, 7 g of functional master batch, and 1.2 g of maleic anhydride.

[0062] The functional master batch is prepared by the following steps: 95 g of polylactic acid, 1.5 g of ethylene bis-stearamide, 7 g of kaolin, 0.7 g of antioxidant 1076, and 1 g of antioxidant 626 are uniformly mixed, and then fed into a twin-screw extruder for extrusion at 205°C, and then cooled after drawing, granulated, and dried. The activated graphene is prepared by the following steps: 13 g of graphene, 1.7 g of polyethyleneimine, and 1.2 g of polyvinylpyrrolidone are uniformly mixed, 50 g of polylactic acid is added, and then fed into a twin-screw extruder for extrusion at 195°C, and then cooled after drawing, granulated, and dried.

[0063] The method for preparing the stretch film of the medical accessory includes the following steps:

[0064] S1, the raw materials of the upper layer, the middle layer, and the lower layer are mixed respectively, fed into a high-speed stirrer for uniform stirring, and then a three-layer co-extrusion is performed through an extruder to obtain a melt, and the co-extrusion temperature is 195°C;

[0065] S2, the melt is attached to a cold drum with a temperature of 12°C to form a thick sheet, and then synchronous bidirectional stretching is performed, the stretching temperature is 135°C, the bidirectional stretching ratio is 2.5×3.5, and a preformed film is obtained;

[0066] S3, the preformed film is shaped at a temperature of 162°C for 8 s, and then cooled and subjected to corona treatment.

[0067] Example 5

[0068] A stretch film of a medical accessory includes a middle layer, an upper layer covering one side of the middle layer, and a lower layer covering the other side of the middle layer.

[0069] The raw materials of the upper layer include 80 g of polylactic acid, 15 g of polybutylene adipate terephthalate, 8 g of activated graphene, 5 g of functional master batch, and 1.5 g of maleic anhydride.

[0070] The raw materials of the middle layer include 50 g of polyhydroxybutyrate, 30 g of branched starch, 1.5 g of 2.0-generation amino-terminated polyamide amine, and 1.5 g of maleic anhydride.

[0071] The raw materials of the lower layer include 80 g of polylactic acid, 15 g of polybutylene succinate, 10 g of activated graphene, 5 g of functional master batch, and 1.5 g of maleic anhydride.

[0072] The functional master batch is prepared by the following steps: 90 g of polylactic acid, 2 g of ethylene bis-stearamide, 6 g of diatomite, 0.8 g of antioxidant 1076, and 1.6 g of antioxidant 626 are uniformly mixed, and then fed into a double-screw extruder for extrusion at 200 DEG C, and then cooled after drawing, granulated, and dried. The activated graphene is prepared by the following steps: 15 g of graphene, 1.5 g of polyethyleneimine, and 1.5 g of polyvinylpyrrolidone are uniformly mixed, and then 45 g of polylactic acid is added and fed into a double-screw extruder for extrusion at 200 DEG C, and then cooled after drawing, granulated, and dried.

[0073] The preparation method of the medical auxiliary material stretch film comprises the following steps:

[0074] S1, the raw materials of the upper layer, the middle layer and the lower layer are mixed respectively, fed into a high-speed stirrer for uniform stirring, and then a three-layer co-extrusion melt is obtained by an extruder, and the co-extrusion temperature is 190 DEG C;

[0075] S2, the melt is attached to a cold drum with a temperature of 13 DEG C to form a thick sheet, and then synchronous bidirectional stretching is performed, the stretching temperature is 130 DEG C, and the bidirectional stretching ratio is 3*3, to obtain a pre-made film;

[0076] S3, the pre-made film is shaped at a temperature of 165 DEG C for 7 s, and then cooled and subjected to corona treatment.

[0077] Comparative Example 1

[0078] A medical auxiliary material stretch film comprises a middle layer, an upper layer covering one side of the middle layer, and a lower layer covering the other side of the middle layer.

[0079] The raw materials of the upper layer comprise 80 g of polylactic acid, 15 g of polybutylene adipate terephthalate, 8 g of graphene, 5 g of functional master batch, and 1.5 g of maleic anhydride.

[0080] The raw materials of the middle layer comprise 50 g of polyhydroxybutyrate, 30 g of branched starch, 1.5 g of 2.0-generation amino-terminated polyamide amine, and 1.5 g of maleic anhydride.

[0081] The raw materials of the lower layer comprise 80 g of polylactic acid, 15 g of polybutylene succinate, 10 g of graphene, 5 g of functional master batch, and 1.5 g of maleic anhydride.

[0082] The functional master batch is prepared by the following steps: 90 g of polylactic acid, 2 g of ethylene bis-stearamide, 6 g of diatomite, 0.8 g of antioxidant 1076, and 1.6 g of antioxidant 626 are uniformly mixed, and then fed into a double-screw extruder for extrusion at 200 DEG C, and then cooled after drawing, granulated, and dried.

[0083] The preparation method of the medical auxiliary material stretch film comprises the following steps:

[0084] S1, the raw materials of the upper layer, the middle layer and the lower layer are mixed respectively, sent into a high-speed mixer for uniform stirring, and then a three-layer co-extrusion is carried out to obtain a melt, and the co-extrusion temperature is 190℃;

[0085] S2, the melt is attached to a cold drum with a temperature of 13℃ to form a thick sheet, and then synchronous biaxial stretching is carried out, the stretching temperature is 130℃, and the biaxial stretching ratio is 3x3, to obtain a preformed film;

[0086] S3, the preformed film is shaped at a temperature of 165℃ for 7s, and then cooled and subjected to corona treatment.

[0087] Comparative Example 2

[0088] A stretch film of a medical accessory, comprising: a middle layer, an upper layer covering one side of the middle layer, and a lower layer covering the other side of the middle layer.

[0089] The raw materials of the upper layer include: 80g of polylactic acid, 15g of polybutylene adipate terephthalate, 8g of activated graphene, 5g of functional masterbatch, and 1.5g of maleic anhydride.

[0090] The raw materials of the middle layer include: 50g of polyhydroxybutyrate, 30g of branched starch, and 1.5g of maleic anhydride.

[0091] The raw materials of the lower layer include: 80g of polylactic acid, 15g of polybutylene succinate, 10g of activated graphene, 5g of functional masterbatch, and 1.5g of maleic anhydride.

[0092] The above-mentioned functional masterbatch is prepared by the following steps: 90g of polylactic acid, 2g of ethylene bis-stearamide, 6g of diatomite, 0.8g of antioxidant 1076, and 1.6g of antioxidant 626 are uniformly mixed, and then sent into a double-screw extruder for extrusion at 200℃, and then cooled, granulated, and dried after drawing. The activated graphene is prepared by the following steps: 15g of graphene, 1.5g of polyethyleneimine, and 1.5g of polyvinylpyrrolidone are uniformly mixed, 45g of polylactic acid is added, and then sent into a double-screw extruder for extrusion at 200℃, and then cooled, granulated, and dried after drawing.

[0093] The preparation method of the above-mentioned stretch film of a medical accessory, comprising the following steps:

[0094] S1, the raw materials of the upper layer, the middle layer and the lower layer are mixed respectively, sent into a high-speed mixer for uniform stirring, and then a three-layer co-extrusion is carried out to obtain a melt, and the co-extrusion temperature is 190℃;

[0095] S2, the melt is attached to a cold drum with a temperature of 13℃ to form a thick sheet, and then synchronous biaxial stretching is carried out, the stretching temperature is 130℃, and the biaxial stretching ratio is 3x3, to obtain a preformed film;

[0096] S3, the pre-made film is shaped at a temperature of 165°C for 7s, and after cooling, it is treated by corona.

[0097] The thicknesses of the stretched films obtained in Example 5 and Comparative Examples 1-2 were determined according to GB / T 6672-2001 “Determination of thickness of plastic films and sheets - Mechanical method”. The thicknesses of the three were all in the range of 15.0±1.0 pm.

[0098] The stretched films obtained in Example 5 and Comparative Examples 1-2 were mixed with soil respectively, and then subjected to aerobic composting degradation for 150 days according to GB / T 19277.1-2011 “Determination of the ultimate aerobic biodegradation of materials under controlled composting conditions - Method by measuring the released carbon dioxide - Part 1: General method”. The biodegradation rates were calculated.

[0099] The biodegradation rate of the stretched film obtained in Example 5 after 150 days of aerobic composting degradation was 81.45%, and the biodegradation rates of the stretched films obtained in Comparative Examples 2 and 1 were 78.86% and 74.13% respectively.

[0100] The biodegradation rates of the three were all ≥60%, which confirmed that the biodegradation performances of the three were excellent. The biodegradation rate of the stretched film obtained in Example 5 was higher than that of Comparative Example 2, but there was no significant difference (P>0.05); and the biodegradation rates of the stretched films obtained in Example 5 and Comparative Example 2 were both higher than that of Comparative Example 1 (P<0.05), which showed more excellent biodegradation performance.

[0101] The tensile strengths of the stretched films obtained in Example 5 and Comparative Examples 1-2 were determined according to GB / T 1040.3-2006 “Determination of tensile properties of plastics - Part 3: Test conditions for films and sheets”. Three parallel groups were set for each. Figure 1 As shown in Table 2, the longitudinal / transverse tensile strengths of the stretched film obtained in Example 5 were the highest, which were better than those of Comparative Examples 1-2 (P<0.05).

[0102] The water vapor transmission amount was tested according to the weight gain method in GB / T 1037-2021 “Determination of water vapour transmission properties of plastics films and sheets - Cup method (weight gain and loss)”. The test temperature was 38°C, the humidity was 90% RH, the preheating time was 2h, the rotation interval was 10min, and three parallel groups were set for each. The oxygen transmission rate was tested according to GB / T 1038.1-2022 “Plastics - Determination of the gas transmission properties of films and sheets - Part 1: Differential pressure method”. The test temperature was 23°C, the humidity was 50% RH, and the vacuum time was 4h. The sample surface was ensured to be free of contamination and scratches, and three parallel groups were set for each.

[0103] As shown in Table 2, the longitudinal / transverse tensile strengths of the stretched film obtained in Example 5 were the highest, which were better than those of Comparative Examples 1-2 (P<0.05).Figure 2 As shown, the water vapor transmission amount and the oxygen transmission rate of the stretched film obtained in Example 5 are the lowest, which is better than those of Comparative Examples 1-2 (P<0.05).

[0104] The reason for the above results is that the polylactic acid is compounded with activated graphene and polybutylene adipate terephthalate in the application, which has excellent toughness, and branched starch is added in the middle layer, which effectively reduces the cost, cooperates with the action of terminal amino polyamide, and forms a three-dimensional network structure after blending, which better improves the melt strength, can greatly improve the tensile properties of the material, especially the low temperature tensile properties, cooperates with the action of the upper and lower surface layers, and the film stability is excellent, and has better durability.

[0105] The above is only a preferred specific embodiment of the application, but the protection scope of the application is not limited to this. Any person skilled in the art can make equivalent replacements or changes according to the technical scheme and the inventive concept of the application within the technical range disclosed by the application, which should be covered in the protection scope of the application.

Claims

1. A stretch film for medical accessories, characterized by, include: The middle layer, the upper surface layer covering one side of the middle layer, and the lower surface layer covering the other side of the middle layer; The raw materials for the upper surface layer include, by weight: 60-100 parts of polylactic acid, 10-20 parts of polybutylene terephthalate-adipate, 5-10 parts of activated graphene, 2-8 parts of functional masterbatch, and 1-2 parts of compatibilizer. The raw materials for the intermediate layer include, by mass, 40-60 parts of polyhydroxybutyrate, 20-40 parts of branched starch, 1-2 parts of amino-terminated polyamide amine, and 1-2 parts of compatibilizer. The raw materials in the lower surface layer include, by weight: 60-100 parts of polylactic acid, 10-20 parts of polybutylene succinate, 5-15 parts of activated graphene, 1-10 parts of functional masterbatch, and 1-2 parts of compatibilizer. Activated graphene is prepared by the following steps: graphene, organic amine surfactant, and dispersant are mixed evenly, polylactic acid is added, extruded at 190-210℃, and dried.

2. The stretch film of the medical accessory of claim 1, wherein, The compatibilizer is maleic anhydride and / or glycidyl methacrylate.

3. The stretch wrap film of claim 1, wherein, The functional masterbatch, by weight, includes: 80-100 parts polylactic acid, 1-3 parts lubricant, 4-8 parts opening agent, and 1-3 parts antioxidant.

4. The stretch film of claim 3, wherein the film is a medical device. The lubricant is at least one of ethylene bis-stearamide, oleamide, and erucamide.

5. The stretch wrap film of claim 3, wherein the film has a thickness of 0.5 to 2.0 mils. The opening agent is at least one of talc, diatomaceous earth, kaolin, and calcium carbonate.

6. The stretch wrap film of claim 3, wherein, The antioxidants include antioxidant 1076 and antioxidant 626, with a mass ratio of antioxidant 1076 to antioxidant 626 of 1:1-2.

7. The stretch wrap film of claim 1, wherein, The mass ratio of graphene, organic amine surfactant, dispersant, and polylactic acid is 10-20:1-2:1-2:30-60.

8. The stretch film of the medical accessory of claim 1, wherein, The surfactant is polyethyleneimine, and the dispersant is polyvinylpyrrolidone.

9. A method of making a stretch film for medical accessories as claimed in any one of claims 1 to 8, characterised in that, Includes the following steps: S1. Mix the raw materials of the upper surface layer, middle layer and lower surface layer separately, and then perform three-layer co-extrusion to obtain melt; S2. The melt is attached to the cold drum to form a thick sheet, and then simultaneously biaxially stretched at a stretching temperature of 120-140℃ and a biaxial stretching ratio of 2-4×2-4 to obtain a pre-made film. S3. Set the pre-made film at 160-170℃ for 4-10 seconds, and then treat it with corona after cooling.

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