A high-transparency, high-temperature resistant, biodegradable polypropylene mushroom film, bag, and preparation method thereof.

Abstract

This invention relates to the field of composite film technology, providing a high-transparency, high-temperature resistant, and biodegradable polypropylene mushroom film and bag, as well as a preparation method. This invention strictly controls the raw materials and proportions used in the outer, middle, and inner layers of the polypropylene mushroom film. Simultaneously, it adds biodegradable masterbatch to the outer, middle, and inner layers of the polypropylene mushroom film, enabling the transformation of traditional polypropylene plastic into a new generation of biodegradable plastic that is harmless to nature, without affecting the film's performance. The resulting high-transparency, high-temperature resistant, and biodegradable polypropylene mushroom film can degrade under light, heat, oxygen, and composting conditions, and can completely degrade into carbon dioxide and water, without producing microplastics, thus exhibiting good environmental friendliness. Furthermore, the film has high transparency, high strength, is not prone to ink smudging during printing, has low leaching, good heat-sealing properties, and good high-temperature resistance, and can be sterilized at 121℃, meeting the usage requirements of mushroom films and bags.

Description

Technical Field

[0001] This invention relates to the field of composite film technology, and in particular to a high-transparency, high-temperature resistant, biodegradable polypropylene mushroom film, bag, and preparation method. Background Technology

[0002] When cultivating mushrooms, specialized mushroom bags are often used. These bags allow external oxygen to enter smoothly, promoting mushroom growth, while simultaneously blocking bacteria and fungi, thus preventing negative impacts on mushroom growth. After cultivation, these bags become waste. Currently, commonly used mushroom bags are made of polypropylene film. Polypropylene film has good stability and is not easily decomposed, making effective disposal of discarded mushroom bags difficult.

[0003] With the global increase in plastic use, the pressure of plastic waste generation is becoming increasingly heavy. Environmental protection and social responsibility require the world to shift towards sustainable development. Currently, the plastics industry has three major development directions: weight reduction and thinning, recyclability, and biodegradability.

[0004] Currently, weight reduction, thinning, and recyclability can all be achieved in the flexible packaging industry. However, when biodegradable films replace traditional plastics, they suffer from problems such as low strength, poor transparency, poor high-temperature resistance, and ink smudging during printing, making them difficult to apply widely. They can only be used in areas with low requirements, such as shopping bags and garbage bags. Furthermore, current biodegradable films can usually only degrade under composting conditions, and their degradation performance needs to be improved. Summary of the Invention

[0005] In view of this, the present invention provides a high-transparency, high-temperature resistant, and biodegradable polypropylene mushroom film, a bag, and a method for preparing it. The high-transparency, high-temperature resistant, and biodegradable polypropylene mushroom film provided by the present invention has high transparency, good high-temperature resistance, high strength, is not easy to bleed ink when printed, and has good degradability.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] A highly transparent, high-temperature resistant, and biodegradable polypropylene mushroom film is made from three layers of raw materials—outer, middle, and inner layers—through a three-layer co-extrusion blown film process.

[0008] By mass, the raw materials for preparing the outer layer include 10-50 parts of a first random copolymer polypropylene, 30-80 parts of a second random copolymer polypropylene, 1.5-2.5 parts of degradation masterbatch, and 0.5-1 parts of processing aids; the first random copolymer polypropylene has a melt index of 4.0-5.0 g / 10 min and a density of 0.895-0.910 g / cm³. 3 The second random copolymer polypropylene has a melt index of 1.2–2.5 g / 10 min and a density of 0.895–0.910 g / cm³. 3 ;

[0009] By weight, the raw materials for preparing the middle layer include 30-85 parts of block copolymer polypropylene, 10-40 parts of third random copolymer polypropylene, 5-20 parts of modified toughening material, 1.5-2.5 parts of degradation masterbatch, and 0.5-1 parts of processing aid; the third random copolymer polypropylene has a melt index of 1.2-2.5 g / 10 min and a density of 0.895-0.910 g / cm³. 3 ;

[0010] By mass, the raw materials for preparing the inner layer include 30-90 parts of fourth random copolymer polypropylene, 10-30 parts of ternary copolymer polypropylene, 1.5-2.5 parts of degradation masterbatch, and 0.5-1 part of processing aids; the fourth random copolymer polypropylene has a melt index of 1.0-2.0 g / 10 min and a density of 0.895-0.915 g / cm³. 3 ;

[0011] The outer, middle, and inner layers use degradation masterbatches with a melt index of 85–95 g / 10 min and a density of 0.885–0.910 g / cm³. 3 .

[0012] Preferably, the block copolymer polypropylene used in the middle layer has a melt index of 4.0–6.0 g / 10 min and a density of 0.895–0.910 g / cm³. 3 The modified toughening material used in the intermediate layer has a melt index of 1.5–3.0 g / 10 min and a density of 0.860–0.890 g / cm³. 3 ;

[0013] The inner layer uses a ternary copolymer polypropylene with a melt index of 6.0–8.0 g / 10 min and a density of 0.895–0.910 g / cm³. 3 ;

[0014] The processing aids used in the outer, middle, and inner layers have a melt index of 5.0–7.0 g / min and a density of 0.890–0.910 g / cm³. 3 .

[0015] Preferably, the first random copolymer polypropylene used in the outer layer is of type J410F, and the second random copolymer polypropylene is of type RP271G.

[0016] Preferably, the block copolymer polypropylene used in the middle layer is BF308, the third random copolymer polypropylene is RP271G, and the modified toughening material is 3020FL.

[0017] Preferably, the fourth random copolymer polypropylene used in the inner layer is of type RB707CF, and the ternary copolymer polypropylene is of type FL7632L.

[0018] Preferably, the outer, middle and inner layers use PLMV3.3 degradation masterbatch and PA0833PPR processing aid.

[0019] This invention also provides a method for preparing the high-transparency, high-temperature resistant, and biodegradable polypropylene mushroom film described above, comprising the following steps:

[0020] The raw materials for the outer, middle, and inner layers are co-extruded and blown into a film to obtain the high-transparency, high-temperature resistant, and biodegradable polypropylene mushroom film.

[0021] Preferably, the process of the three-layer co-extrusion blown film specifically includes: mixing the outer, middle, and inner layer raw materials in proportion through an automatic batching system, and feeding them into the outer, middle, and inner layer extruders respectively; melting and plasticizing the outer, middle, and inner layer raw materials and feeding them into the die head for extrusion and blown film; cooling them through a cooling water ring; drying them in a dryer through a herringbone pattern; corona treatment them through a guide roller; and then trimming the edges and feeding them into a front and rear winding device through a lower traction clamping roller for front and rear winding to obtain the high-transparency, high-temperature resistant, biodegradable polypropylene mushroom film.

[0022] The present invention also provides a highly transparent, high-temperature resistant, and biodegradable polypropylene mushroom bag, which is prepared from a highly transparent, high-temperature resistant, and biodegradable polypropylene mushroom film; the highly transparent, high-temperature resistant, and biodegradable polypropylene is the highly transparent, high-temperature resistant, and biodegradable polypropylene described in the above scheme or the highly transparent, high-temperature resistant, and biodegradable polypropylene prepared by the preparation method described in the above scheme.

[0023] The present invention also provides a method for preparing the high-transparency, high-temperature resistant, and biodegradable polypropylene mushroom bag described above, comprising the following steps: printing on the surface of the high-transparency, high-temperature resistant, and biodegradable polypropylene mushroom film and then making the bag to obtain the high-transparency, high-temperature resistant, and biodegradable polypropylene mushroom bag.

[0024] This invention provides a highly transparent, high-temperature resistant, and biodegradable polypropylene mushroom film, which is made by three-layer co-extrusion blown film preparation materials: an outer layer, a middle layer, and an inner layer. By weight, the outer layer preparation materials include 10-50 parts of a first random copolymer polypropylene, 30-80 parts of a second random copolymer polypropylene, 1.5-2.5 parts of degradation masterbatch, and 0.5-1 parts of processing aids. The first random copolymer polypropylene has a melt index of 4.0-5.0 g / 10 min and a density of 0.895-0.910 g / cm³. 3 The second random copolymer polypropylene has a melt index of 1.2–2.5 g / 10 min and a density of 0.895–0.910 g / cm³. 3The raw materials for preparing the middle layer, by mass parts, include 30-85 parts of block copolymer polypropylene, 10-40 parts of third random copolymer polypropylene, 5-20 parts of modified toughening material, 1.5-2.5 parts of degradation masterbatch, and 0.5-1 parts of processing aids; the melt index of the third random copolymer polypropylene is 1.2-2.5 g / 10 min, and the density is 0.895-0.910 g / cm³. 3 The inner layer is prepared from the following raw materials by mass: 30-90 parts of fourth random copolymer polypropylene, 10-30 parts of ternary copolymer polypropylene, 1.5-2.5 parts of degradation masterbatch, and 0.5-1 part of processing aids; the fourth random copolymer polypropylene has a melt index of 1.0-2.0 g / 10 min and a density of 0.895-0.915 g / cm³. 3 The outer, middle, and inner layers utilize degradation masterbatches with a melt index of 85–95 g / 10 min and a density of 0.885–0.910 g / cm³. 3 This invention strictly controls the raw materials and proportions used in the outer, middle, and inner layers of the polypropylene mushroom film. Simultaneously, by adding biodegradable masterbatch to these layers, traditional polypropylene plastic can be transformed into a new generation of biodegradable plastic that is harmless to nature, without affecting the film's performance. The resulting highly transparent, high-temperature resistant, biodegradable polypropylene mushroom film can degrade under light, heat, oxygen, and composting conditions, and can completely degrade into carbon dioxide and water without producing microplastics, thus exhibiting excellent environmental friendliness. Furthermore, the film boasts high transparency, high strength, minimal ink smudging during printing, low leaching, good heat-sealing properties, and excellent high-temperature resistance, allowing for high-temperature sterilization at 121℃, meeting the usage requirements for mushroom films and bags. Detailed Implementation

[0025] This invention provides a highly transparent, high-temperature resistant, and biodegradable polypropylene mushroom film, which is made by three-layer co-extrusion blown film preparation raw materials of outer layer, middle layer and inner layer;

[0026] By mass, the raw materials for preparing the outer layer include 10-50 parts of a first random copolymer polypropylene, 30-80 parts of a second random copolymer polypropylene, 1.5-2.5 parts of degradation masterbatch, and 0.5-1 parts of processing aids; the first random copolymer polypropylene has a melt index of 4.0-5.0 g / 10 min and a density of 0.895-0.910 g / cm³. 3 The second random copolymer polypropylene has a melt index of 1.2–2.5 g / 10 min and a density of 0.895–0.910 g / cm³. 3 ;

[0027] By weight, the raw materials for preparing the middle layer include 30-85 parts of block copolymer polypropylene, 10-40 parts of third random copolymer polypropylene, 5-20 parts of modified toughening material, 1.5-2.5 parts of degradation masterbatch, and 0.5-1 parts of processing aid; the third random copolymer polypropylene has a melt index of 1.2-2.5 g / 10 min and a density of 0.895-0.910 g / cm³. 3 ;

[0028] By mass, the raw materials for preparing the inner layer include 30-90 parts of fourth random copolymer polypropylene, 10-30 parts of ternary copolymer polypropylene, 1.5-2.5 parts of degradation masterbatch, and 0.5-1 part of processing aids; the fourth random copolymer polypropylene has a melt index of 1.0-2.0 g / 10 min and a density of 0.895-0.915 g / cm³. 3 ;

[0029] The outer, middle, and inner layers use degradation masterbatches with a melt index of 85–95 g / 10 min and a density of 0.885–0.910 g / cm³. 3 .

[0030] By weight, the raw materials for preparing the outer layer include 10-50 parts, preferably 20-40 parts, of a first random copolymer polypropylene; the first random copolymer polypropylene has a melt index of 4.0-5.0 g / 10 min and a density of 0.895-0.910 g / cm³. 3 The preferred type of the first random copolymer polypropylene is J410F, with a melt index of 4.5 g / 10 min and a density of 0.90 g / cm³. 3 The manufacturer is Hyosung of South Korea; the first random copolymer polypropylene used in this invention has characteristics such as high stiffness, high transparency, and easy processing.

[0031] Based on the mass fraction of the first random copolymer polypropylene used in the outer layer, the raw materials for preparing the outer layer include 30-80 parts of the second random copolymer polypropylene, preferably 40-70 parts; the melt index of the second random copolymer polypropylene is 1.2-2.5 g / 10 min, and the density is 0.895-0.910 g / cm³. 3 In a specific embodiment of the present invention, the second random copolymer polypropylene is preferably RP271G, with a melt index of 1.8 g / 10 min and a density of 0.90 g / cm³. 3 The manufacturer is LyondellBasell; the second random copolymer polypropylene used in this invention has characteristics such as high stiffness, high transparency, and easy processing.

[0032] Based on the mass fraction of the first random copolymer polypropylene used in the outer layer, the raw materials for preparing the outer layer include 1.5 to 2.5 parts of degradation masterbatch, preferably 2 parts. In this invention, the melt index of the degradation masterbatch is 85 to 95 g / 10 min, and the density is 0.885 to 0.910 g / cm³. 3 The preferred type of degradation masterbatch is PLMV3.3, with a melt index of 90 g / min and a density of 0.900 g / cm³. 3 The manufacturer is Polymateria, a UK company. The biodegradable masterbatch used in this invention can convert polypropylene into bioavailable wax without requiring specific environmental degradation. The degradation time can be adjusted according to different usage conditions and cycles, making the degradation time controllable. After degradation, no microplastics or toxic substances are left behind, making it harmless to nature. Furthermore, the physical properties of the film do not change after adding the biodegradable masterbatch. Compared with other biodegradable films, it has a wider range of applications and lower costs. Adding the biodegradable masterbatch does not require changing the original process equipment and can be recycled and granulated together with ordinary plastics without affecting physical properties. Specifically, under the catalytic action of the degradation masterbatch, the plastic can undergo the following three chemical reactions: 1. When exposed to energy such as light and heat, the carbon chain of the polypropylene molecular bond breaks, generating highly reactive free radicals; 2. Free radical growth: Under aerobic conditions, the highly reactive free radicals rapidly react to generate intermediate products such as peroxy free radicals or hydroperoxy free radicals; 3. Chain termination: Compounds containing unstable peroxy free radicals or hydroperoxy free radicals undergo molecular bond breakage and a series of chemical reactions to generate small molecule compounds with carbon-hydrogen-oxygen structures, ultimately becoming carbon dioxide, water, and wax, which are non-toxic and harmless to nature. The wax undergoes biotransformation through naturally occurring bacteria and fungi in the soil under open environmental temperature conditions; the resulting highly transparent, high-temperature resistant, and biodegradable polypropylene mushroom film meets the degradation requirements of ASTM6954, GB / T20197, and BSIPAS 9017.

[0033] Based on the mass fraction of the first random copolymer polypropylene used in the outer layer, the raw materials for preparing the outer layer include 0.5 to 1 part of processing aids, preferably 0.6 to 0.8 parts; the melt index of the processing aids used in the outer layer is preferably 5.0 to 7.0 g / min, and the density is preferably 0.890 to 0.910 g / cm³. 3 The processing aid is preferably a functional masterbatch prepared from fluoropolymer and polyolefin resin; in a specific embodiment of the present invention, the processing aid used in the outer layer is preferably PA0833PPR, with a melt index of 6.0 g / min and a density of 0.90 g / cm³. 3 The manufacturer is Suzhou Constance Engineering Plastics Co., Ltd. The processing aids used in this invention can effectively reduce die buildup, reduce crystal points, lower extrusion pressure, and improve production efficiency.

[0034] The raw materials for preparing the middle layer, by weight, include 30-85 parts, preferably 40-70 parts, of block copolymer polypropylene; the melt index of the block copolymer polypropylene used in the middle layer is preferably 4.0-6.0 g / 10 min, and the density is preferably 0.895-0.910 g / cm³. 3 The block copolymer polypropylene is preferably manufactured by copolymerizing ethylene and propylene. In a specific embodiment of the present invention, the block copolymer polypropylene is preferably BF308, manufactured by Samsung Total, with a melt index of 5.0 g / 10 min and a density of 0.90 g / cm³. 3 The block copolymer polypropylene used in this invention has high strength, good stiffness, and is easy to process.

[0035] Based on the mass fraction of block copolymer polypropylene used in the middle layer, the raw materials for preparing the middle layer include 10-40 parts of third random copolymer polypropylene, preferably 15-35 parts; the melt index of the third random copolymer polypropylene is 1.2-2.5 g / 10 min, and the density is 0.895-0.910 g / cm³. 3 In a specific embodiment of the present invention, the third random copolymer polypropylene is preferably RP271G, with a melt index of 1.8 g / 10 min and a density of 0.90 g / cm³. 3 The manufacturer is LyondellBasell; the third random copolymer polypropylene used in this invention has characteristics such as high stiffness, high transparency, and easy processing.

[0036] Based on the mass fraction of block copolymer polypropylene used in the middle layer, the raw materials for preparing the middle layer include 5 to 20 parts of modified toughening material, preferably 10 to 15 parts; the melt index of the modified toughening material is preferably 1.5 to 3.0 g / 10 min, and the density is preferably 0.860 to 0.890 g / cm³. 3 In a specific embodiment of the present invention, the modified toughening material is preferably Vindamil 3020FL, with a melt index of 2.2 g / 10 min and a density of 0.874 g / cm³. 3 The manufacturer is ExxonMobil; the modified toughening material used in this invention has characteristics such as high toughness, impact resistance, and easy processing.

[0037] Based on the mass fraction of block copolymer polypropylene used in the middle layer, the raw materials for preparing the middle layer include 1.5 to 2.5 parts of degradation masterbatch, preferably 1.8 to 2.2 parts; the melt index, density and specific grade of the degradation masterbatch used in the middle layer are preferably the same as those of the degradation masterbatch used in the outer layer, which will not be repeated here.

[0038] Based on the mass fraction of block copolymer polypropylene used in the middle layer, the raw materials for preparing the middle layer include 0.5 to 1 part of processing aids, preferably 0.6 to 0.8 parts; the melt index, density and specific grade of the processing aids used in the middle layer are preferably the same as those used in the outer layer, and will not be repeated here.

[0039] The inner layer is prepared from 30-90 parts by mass of a fourth random copolymer polypropylene, preferably 40-80 parts; the fourth random copolymer polypropylene has a melt index of 1.0-2.0 g / 10 min and a density of 0.895-0.915 g / cm³. 3 In a specific embodiment of the present invention, the fourth random copolymer polypropylene is preferably RB707CF, with a melt index of 1.5 g / 10 min and a density of 0.905 g / cm³. 3 The manufacturer is Bolu Chemical; the fourth random copolymer polypropylene used in this invention has the properties of high transparency, high strength, high temperature resistance and easy processing.

[0040] Based on the mass fraction of the fourth random copolymer polypropylene used in the inner layer, the raw materials for preparing the inner layer include 10 to 30 parts of ternary copolymer polypropylene, preferably 15 to 25 parts; the melt index of the ternary copolymer polypropylene is preferably 6.0 to 8.0 g / 10 min, and the density is preferably 0.895 to 0.910 g / cm³. 3 In a specific embodiment of the present invention, the preferred type of the ternary copolymer polypropylene is FL7632L, with a melt index of 7.0 g / 10 min and a density of 0.90 g / cm³. 3 The manufacturer is TPC (The Polyolefin Company); the ternary copolymer polypropylene used in this invention has the properties of low initial sealing temperature, high heat seal strength, good opening properties, and easy processing.

[0041] Based on the mass fraction of the fourth random copolymer polypropylene used in the inner layer, the raw materials for preparing the inner layer include 1.5 to 2.5 parts of degradation masterbatch, preferably 1.8 to 2.2 parts; the melt index, density and specific grade of the degradation masterbatch used in the inner layer are preferably the same as those of the degradation masterbatch used in the outer layer, which will not be repeated here.

[0042] Based on the mass fraction of the fourth random copolymer polypropylene used in the inner layer, the raw materials for preparing the inner layer include 0.5 to 1 part of processing aids, preferably 0.6 to 0.8 parts; the melt index, density and specific grade of the processing aids used in the middle layer are preferably the same as those used in the outer layer, and will not be repeated here.

[0043] In this invention, the total mass of the outer layer, middle layer, and inner layer is taken as 100%. The mass fraction of the outer layer is preferably 15-35%, more preferably 20-30%; the mass fraction of the middle layer is preferably 30-70%, more preferably 40-60%; and the mass fraction of the inner layer is preferably 15-35%, more preferably 20-30%. In this invention, the thickness of the highly transparent, high-temperature resistant, biodegradable polypropylene mushroom film is preferably 40-100 μm, more preferably 60-80 μm.

[0044] In this invention, the longitudinal tensile strength of the high-transparency, high-temperature resistant, and biodegradable polypropylene mushroom film is preferably 53-54 MPa, the transverse tensile strength is preferably 42-43 MPa, the longitudinal elongation at break is preferably 630%-635%, the transverse elongation at break is preferably 730%-735%, the wetting tension is preferably 40-45 mN / 15 mm, more preferably 42 mN / 15 mm, the haze is preferably 6%-7%, more preferably 6.1%-6.8%, and the heat-sealing strength is preferably 22.1-22.8 N / 15 mm. The high-transparency, high-temperature resistant, and biodegradable polypropylene mushroom film can be effectively degraded under natural environment, photodegradation, thermo-oxidative degradation, and composting conditions.

[0045] This invention also provides a method for preparing the high-transparency, high-temperature resistant, and biodegradable polypropylene mushroom film described above, comprising the following steps:

[0046] The raw materials for the outer, middle, and inner layers are co-extruded and blown into a film to obtain the high-transparency, high-temperature resistant, and biodegradable polypropylene mushroom film.

[0047] In this invention, the process of the three-layer co-extrusion blown film specifically includes: mixing the outer, middle, and inner layer raw materials in proportion using an automatic batching system, and then feeding them into the outer, middle, and inner layer extruders respectively; melting and plasticizing the outer, middle, and inner layer raw materials and then feeding them into the die head for extrusion and blown film; cooling through a cooling water ring; drying through a herringbone pattern in a dryer; corona treatment through guide rollers; and then trimming the edges and feeding them through a lower traction clamping roller into a front and rear winding device for front and rear winding, thereby obtaining the high-transparency, high-temperature resistant, and biodegradable polypropylene mushroom film; the cooling temperature of the cooling water ring is preferably 15-20℃, and the drying temperature of the dryer is preferably 50℃±5℃.

[0048] In this invention, the outer extruder, the middle extruder, and the inner extruder are preferably each provided with 5 heating zones, which are numbered 1 to 5 according to the order in which the raw materials pass through; the die head is provided with 4 heating zones, which are numbered 1 to 4 according to the order in which the raw materials pass through.

[0049] In this invention, the extrusion temperatures of the outer extruder, middle extruder, inner extruder, and each zone of the die are shown in Table 1:

[0050] Table 1. Extrusion temperatures of various zones in the outer, middle, and inner layer extruders and die.

[0051] temperature Zone 1 / ℃ Zone 2 / ℃ Zone 3 / ℃ Zone 4 / ℃ 5 zones / ℃ outer layer 185±5 195±5 200±5 190±5 185±5 Middle layer 180±5 188±5 195±5 190±5 182±5 Inner layer 175±5 185±5 193±5 187±5 185±5 mold head 200±5 205±5 210±5 200±5

[0052] In this invention, the extrusion pressure of the outer extruder is preferably 155-225 bar, the extrusion pressure of the middle extruder is preferably 165-215 bar, and the extrusion pressure of the inner extruder is preferably 160-235 bar.

[0053] The present invention also provides a highly transparent, high-temperature resistant, and biodegradable polypropylene mushroom bag, which is prepared from a highly transparent, high-temperature resistant, and biodegradable polypropylene mushroom film; the highly transparent, high-temperature resistant, and biodegradable polypropylene is the highly transparent, high-temperature resistant, and biodegradable polypropylene described in the above scheme or the highly transparent, high-temperature resistant, and biodegradable polypropylene prepared by the preparation method described in the above scheme.

[0054] The present invention also provides a method for preparing the high-transparency, high-temperature resistant, and biodegradable polypropylene mushroom bag described above, comprising the following steps: printing on the surface of the high-transparency, high-temperature resistant, and biodegradable polypropylene mushroom film and then making the bag to obtain the high-transparency, high-temperature resistant, and biodegradable polypropylene mushroom bag.

[0055] In this invention, the printing method is preferably gravure printing, and more preferably printing is performed on the inner layer of the highly transparent, high-temperature resistant, and biodegradable polypropylene mushroom film. This invention does not have special requirements for the bag-making process; it can be prepared using methods well known to those skilled in the art according to the required bag shape.

[0056] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments thereof, but this should not be construed as limiting the scope of protection of the present invention.

[0057] The sources of raw materials and performance parameters used in the examples are shown in Table 2.

[0058] Table 2 shows the source of raw materials and performance parameters used in the examples.

[0059]

[0060] The raw material ratios for the outer, middle, and inner layers in Examples 1-3 and Comparative Example 2 are shown in Table 3.

[0061] Table 3 shows the raw material amounts (by mass) for Examples 1-3 and Comparative Example 2.

[0062]

[0063]

[0064] Example 1

[0065] This embodiment has a three-layer structure: an outer layer, a middle layer, and an inner layer. The weight percentages of the materials in each layer are as follows: outer layer 25%, middle layer 45%, and inner layer 30%.

[0066] The raw material usage for each layer is shown in Table 3. The total thickness of the high-transparency, high-temperature resistant, and biodegradable polypropylene mushroom film is 75 μm. The preparation method is as follows:

[0067] The raw materials for the outer, middle, and inner layers are mixed in proportion by an automatic batching system and then fed into the outer, middle, and inner layer extruders. After the raw materials are melted and plasticized, they are fed into the die head, extruded and blown downwards, cooled by a cooling water ring at a temperature controlled between 15 and 20°C, and then dried in a dryer at a temperature of 50°C ± 5°C. After passing through guide rollers, they are subjected to corona treatment by a corona treatment device, and then the edges are trimmed and fed into a front and rear winding device by a lower traction clamping roller for front and rear winding. This process yields a 75μm high-transparency, high-temperature resistant, biodegradable polypropylene mushroom film.

[0068] The temperatures and pressures of the outer, middle, and inner layer extruders and dies are shown in Table 4.

[0069] Table 4 Extruder Temperature and Pressure

[0070] temperature Zone 1 / ℃ Zone 2 / ℃ Zone 3 / ℃ 4 zones / ℃ 5 zones / ℃ Pressure / bar outer layer 185 195 200 190 185 185 Middle layer 180 188 195 190 182 205 Inner layer 175 185 193 187 185 210 mold head 200 205 210 200 / /

[0071] The above-mentioned high-transparency, high-temperature resistant, and biodegradable polypropylene mushroom film is used to make bags: according to the requirements, the inner layer is printed using a gravure process. After printing, the high-transparency, high-temperature resistant, and biodegradable polypropylene mushroom film is made into bags according to the required bag shape. The bag making process parameters are: side sealing temperature is 205℃, bottom sealing temperature is 225℃, heat sealing pressure is 28N, and bag making speed is 80 bags / min.

[0072] Example 2

[0073] This embodiment has a three-layer structure: an outer layer, a middle layer, and an inner layer. The weight percentages of the materials in each layer are as follows: outer layer 30%, middle layer 40%, and inner layer 30%. The raw material usage for each layer is shown in Table 3. The total thickness of the high-transparency, high-temperature resistant, and biodegradable polypropylene mushroom film is 75 μm. The preparation method is the same as in Example 1, resulting in a high-transparency, high-temperature resistant, and biodegradable polypropylene mushroom film and bag.

[0074] Example 3

[0075] This embodiment has a three-layer structure: an outer layer, a middle layer, and an inner layer. The weight percentages of the materials in each layer are as follows: outer layer 20%, middle layer 60%, and inner layer 20%. The raw material usage and layer thickness ratio of each layer are shown in Table 3. The total thickness of the high-transparency, high-temperature resistant, and biodegradable polypropylene mushroom film is 75 μm. The preparation method is the same as in Example 1, resulting in a high-transparency, high-temperature resistant, and biodegradable polypropylene mushroom film and bag.

[0076] Comparative Example 1

[0077] This comparative example has a three-layer structure: an outer layer, a middle layer, and an inner layer. The weight percentages of the materials in each layer are as follows: 30% for the outer layer, 40% for the middle layer, and 30% for the inner layer. The total thickness of the film is 75 μm.

[0078] The outer layer is made of random copolymer polypropylene grade W725EF from China National Petroleum Corporation's Dushanzi Petrochemical Company, with a melt index of 7.9 g / 10 min and a density of 0.90 g / cm³. 3 The middle layer uses random copolymer polypropylene RP210M from Daqing Petrochemical Company of China National Petroleum Corporation, with a melt index of 7.8 g / 10 min and a density of 0.90 g / cm³. 3 The heat-sealing layer (i.e., the inner layer) is made of random copolymer polypropylene grade W0723F from China National Petroleum Corporation's Dushanzi Petrochemical Company, with a melt index of 6.4 g / 10 min and a density of 0.90 g / cm³. 3 ;

[0079] The preparation method is the same as in Example 1, yielding a highly transparent, high-temperature resistant, and biodegradable polypropylene mushroom film; the temperatures and pressures of the extruders and dies for the outer, middle, and inner layers are shown in Table 5.

[0080] Table 5 Extruder Temperature and Pressure

[0081] temperature Zone 1 / ℃ Zone 2 / ℃ Zone 3 / ℃ 4 zones / ℃ 5 zones / ℃ Pressure / bar outer layer 195 200 205 200 195 190 Middle layer 193 198 200 195 190 205 Inner layer 190 195 200 193 188 215 mold head 205 210 215 200 / /

[0082] Using the above-mentioned high-transparency, high-temperature resistant, and biodegradable polypropylene mushroom film, the bag-making process is the same as in Example 1, resulting in a high-transparency, high-temperature resistant, and biodegradable polypropylene mushroom bag.

[0083] Comparative Example 2

[0084] This embodiment has a three-layer structure: an outer layer, a middle layer, and an inner layer. The weight percentages of the materials in each layer are as follows: outer layer 25%, middle layer 45%, and inner layer 30%. The raw material usage for each layer is shown in Table 3. The total thickness of the high-transparency, high-temperature resistant, and biodegradable polypropylene mushroom film is 75 μm. The preparation method is the same as in Example 1, resulting in a high-transparency, high-temperature resistant, and biodegradable polypropylene mushroom film and bag.

[0085] Performance testing

[0086] The mechanical properties, wetting tension, haze, boiling resistance, degradation performance, ink layer adhesion strength, and heat sealing strength of the mushroom films prepared in Examples 1-3 and Comparative Examples 1-2 were tested, and the results are shown in Table 6.

[0087] Table 6 Performance Test Results

[0088]

[0089] As can be seen from the data in Table 6, the high-transparency, high-temperature resistant, and biodegradable polypropylene mushroom film prepared by this invention has good mechanical properties, low haze, strong adhesion to the ink layer, and suitable heat-sealing strength. After being boiled at 121℃ for 30 minutes, there is no air leakage when sealed, indicating that it has good high-temperature resistance. Furthermore, degradation performance tests show that the high-transparency, high-temperature resistant, and biodegradable polypropylene mushroom film of this invention can degrade under light, heat, oxygen, and composting conditions. The polypropylene film prepared in Comparative Example 1 has poor mechanical properties and high haze, and cannot degrade under light, heat, oxygen, and composting conditions. In Comparative Example 2, the addition of degradation masterbatch was omitted. Although the basic properties of the film meet the requirements, it cannot be degraded, and its degradation performance under light, heat, oxygen, and composting conditions is unqualified.

[0090] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high transparent high temperature resistant degradable polypropylene mushroom film, characterized in that, The outer layer, the middle layer and the inner layer are prepared by three-layer co-extrusion blown film from raw materials; The raw materials for preparing the outer layer are 10-50 parts of a first random copolymerized polypropylene, 30-80 parts of a second random copolymerized polypropylene, 1.5-2.5 parts of a degradation master batch, and 0.5-1 part of a processing aid, in terms of mass fraction; the first random copolymerized polypropylene has a melt index of 4.0-5.0 g / 10 min and a density of 0.895-0.910 g / cm 3 ; and the second random copolymerized polypropylene has a melt index of 1.2-2.5 g / 10 min and a density of 0.895-0.910 g / cm 3 . The preparation raw materials of the middle layer are block copolymerized polypropylene 30-85 parts by mass, third random copolymerized polypropylene 10-40 parts by mass, modified toughening agent 5-20 parts by mass, degradation master batch 1.5-2.5 parts by mass, and processing aid 0.5-1 part by mass; the melt index of the third random copolymerized polypropylene is 1.2-2.5 g / 10 min, and the density is 0.895-0.910 g / cm 3 ; The preparation raw materials of the inner layer are 30-90 parts of the fourth random copolymerized polypropylene, 10-30 parts of the terpolymerized polypropylene, 1.5-2.5 parts of the degradation master batch, and 0.5-1 part of the processing aid, in terms of mass parts; the melt index of the fourth random copolymerized polypropylene is 1.0-2.0 g / 10 min, and the density is 0.895-0.915 g / cm 3 ; The melt index of the degradation master batch used in the outer layer, the middle layer and the inner layer is 85~95g / 10min, and the density is 0.885~0.910g / cm 3 The model of the degradation master batch used in the outer layer, the middle layer and the inner layer is PLMV3.

3. 2.The high-transparent high-temperature-resistant degradable polypropylene bacterial mushroom film according to claim 1, characterized in that, The middle layer uses a block copolymerized polypropylene with a melt index of 4.0-6.0 g / 10 min and a density of 0.895-0.910 g / cm 3 ; the middle layer uses a modified toughening agent with a melt index of 1.5-3.0 g / 10 min and a density of 0.860-0.890 g / cm 3 ; The melt index of the terpolymer used in the inner layer is 6.0-8.0 g / 10 min, and the density is 0.895-0.910 g / cm 3 ; The melt index of the processing aid used in the outer layer, the middle layer and the inner layer is 5.0-7.0 g / min, and the density is 0.890-0.910 g / cm 3 . 3.The high-transparent high-temperature-resistant degradable polypropylene bacterial mushroom film according to claim 1, characterized in that, The first random copolymerized polypropylene used in the outer layer is J410F, and the second random copolymerized polypropylene is RP271G. 4.The high-transparent high-temperature-resistant degradable polypropylene bacterial mushroom film according to claim 1, characterized in that, The block copolymerized polypropylene used in the middle layer is BF308, the third random copolymerized polypropylene is RP271G, and the modified toughening material is 3020FL. 5.The high-transparent high-temperature-resistant degradable polypropylene bacterial mushroom film according to claim 1, characterized in that, The fourth random copolymerized polypropylene used in the inner layer is RB707CF, and the terpolymerized polypropylene is FL7632L. 6.The high-transparent high-temperature-resistant degradable polypropylene bacterial mushroom film according to claim 1, characterized in that, The processing aid used in the outer layer, the middle layer and the inner layer is PA0833PPR.

7. The method for preparing the high-transparent high-temperature-resistant degradable polypropylene bacterial mushroom film according to any one of claims 1-6, characterized in that, The method comprises the following steps: The outer layer, the middle layer and the inner layer are prepared by three-layer co-extrusion blown film from raw materials to obtain the high-transparency high-temperature-resistant degradable polypropylene mushroom film.

8. The preparation method according to claim 7, characterized in that, The process of the three-layer co-extrusion blown film specifically comprises the following steps: the raw materials of the outer layer, the middle layer and the inner layer are mixed by an automatic batching system according to a proportion, and then are respectively fed into the outer layer, the middle layer and the inner layer extruders; the raw materials of the outer layer, the middle layer and the inner layer are melted and plasticized, and then are fed into a die; the outer layer, the middle layer and the inner layer are extruded and blown downward, and then are cooled by a cooling water ring; the cooled outer layer, the middle layer and the inner layer are arranged in a herringbone shape, and then are dried in a dryer; the dried outer layer, the middle layer and the inner layer are guided by guide rollers, and then are treated by a corona treatment device; the treated outer layer, the middle layer and the inner layer are cut and then are pulled by a lower clamping roller; the pulled outer layer, the middle layer and the inner layer are wound in front and back by front and back winding devices to obtain the high-transparency high-temperature-resistant degradable polypropylene mushroom film.

9. A high-transparent high-temperature-resistant degradable polypropylene mushroom bag, characterized in that, The high-transparency high-temperature-resistant degradable polypropylene mushroom film is prepared from a high-transparency high-temperature-resistant degradable polypropylene mushroom film; the high-transparency high-temperature-resistant degradable polypropylene is the high-transparency high-temperature-resistant degradable polypropylene in any one of claims 1-6 or the high-transparency high-temperature-resistant degradable polypropylene prepared by the preparation method in any one of claims 7-8.

10. The method for preparing the high-transparent high-temperature-resistant degradable polypropylene mushroom bag of claim 9, characterized in that, The method comprises the following steps: The high-transparency high-temperature-resistant degradable polypropylene mushroom bag is prepared by bag-making after printing on the surface of the high-transparency high-temperature-resistant degradable polypropylene mushroom film.

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