Temperature-resistant oil-resistant degradable lunch box film, lunch box and preparation method

Abstract

The invention relates to the technical field of composite films, and provides a temperature-resistant oil-resistant degradable lunch box film, a lunch box and a preparation method of the temperature-resistant oil-resistant degradable lunch box film. The preparation raw materials of the three layers in the degradable lunch box film are strictly controlled, so that the obtained lunch box film has good temperature resistance and oil resistance, high mechanical property and low haze; meanwhile, the degradable master batches are added into the outer layer, the middle layer and the inner layer, traditional plastic polypropylene and ethylene-vinyl acetate copolymer can be converted into new-generation biodegradable plastic which is non-toxic and harmless to the nature, the obtained degradable lunch box film can be completely degraded into carbon dioxide and water, micro-plastic cannot be generated, and the degradable lunch box film is environmentally friendly. Meanwhile, the performance of a plastic film is not changed, the lunch box film is applied to a degradable lunch box, the lunch box and the film do not need to be separated after use, and integrated synchronous degradation can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of composite films, and in particular to a heat-resistant and oil-resistant degradable lunch box film, a lunch box and a preparation method thereof. Background Art

[0002] Traditional lunch boxes are made of plastic and are non-degradable. They can only be discarded after use, resulting in the generation of a large amount of plastic waste. At present, with the increase in global plastic usage, the pressure of plastic waste generation is getting heavier. Environmental protection and social responsibility require the world to shift to sustainable development. At present, the plastic industry has three major development directions: one is weight reduction and thinning, the second is recyclability, and the third is degradability.

[0003] Environmentally friendly lunch boxes are also called plant fiber lunch boxes and environmentally friendly pulp lunch boxes. They are generally made of plant fibers, with the main ingredients being bagasse and straw. They are a natural, biodegradable and safe food packaging material. However, such lunch boxes are water-permeable and oil-resistant, and cannot hold food with soup. They can only be covered with a film.

[0004] At present, the traditional degradable film has a low softening point, is not heat-resistant, oil-resistant, and impact-resistant, and cannot meet the requirements of lunch boxes. Therefore, the current technology can only be used to compound traditional non-degradable plastics on degradable lunch boxes. After use, the film needs to be separated from the lunch box, and the lunch box needs to be degraded and the film needs to be recycled. However, the consumer group is relatively scattered, and this approach is difficult to operate, resulting in incineration and landfill, which pollutes the environment. Summary of the invention

[0005] In view of this, the present invention provides a heat-resistant and oil-resistant degradable lunch box film, a lunch box and a preparation method. The degradable lunch box film provided by the present invention has good heat resistance and oil resistance and is degradable. When applied to the degradable lunch box, the lunch box and the film do not need to be separated after use, and can be degraded synchronously as a whole.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] A heat-resistant and oil-resistant degradable lunch box film, which is made of a three-layer co-extruded blown film of an outer layer, a middle layer and an inner layer;

[0008] In terms of weight, the raw materials for preparing the outer layer include: 10 to 40 parts of a first ethylene-vinyl acetate copolymer, 30 to 85 parts of a second ethylene-vinyl acetate copolymer, 1.5 to 2.5 parts of a degradation masterbatch, and 0.3 to 1.5 parts of a processing aid; the melt index of the first ethylene-vinyl acetate copolymer is 0.2 to 1.0 g / 10 min, and the density is 0.925 to 0.940 g / cm 3 The melt index of the second ethylene-vinyl acetate copolymer is 1.2 to 2.5 g / 10 min and the density is 0.930 to 0.945 g / cm 3 ;

[0009] The raw materials for preparing the middle layer include, by weight: 15 to 45 parts of block copolymer polypropylene, 25 to 85 parts of random copolymer polypropylene, 10 to 20 parts of modified toughening material, 1.5 to 2.5 parts of degradation masterbatch, and 0.3 to 1.5 parts of processing aid;

[0010] Calculated by weight, the raw materials for preparing the inner layer include: 15 to 40 parts of random copolymer polypropylene, 30 to 85 parts of block copolymer polypropylene, 1.5 to 2.5 parts of degradation masterbatch, and 0.3 to 1.5 parts of processing aid.

[0011] Preferably, the block copolymer polypropylene used in the middle layer has a melt index of 1.8 to 3.0 g / 10 min and a density of 0.898 to 0.910 g / cm 3 The random copolymer polypropylene used in the middle layer has a melt index of 7.0 to 9.0 g / 10 min and a density of 0.895 to 0.910 g / cm 3 The modified toughening material used in the middle layer has a melt index of 3.0 to 4.0 g / 10 min and a density of 0.870 to 0.90 g / cm 3 ;

[0012] The random copolymer polypropylene used in the inner layer has a melt index of 1.0-2.0 g / 10 min and a density of 0.890-0.910 g / cm 3 The block copolymer polypropylene used in the inner layer has a melt index of 4 to 8 g / 10 min and a density of 0.90 to 0.920 g / cm 3 .

[0013] Preferably, the degradation masterbatch used in the outer layer has a melt index of 46-55 g / 10 min and a density of 0.920-0.940 g / cm 3 The processing aid used in the outer layer has a melt index of 1 to 8 g / 10 min and a density of 0.910 to 0.925 g / cm 3 ;

[0014] The degradation masterbatch used in the middle layer and the inner layer has a melt index of 85-95 g / 10 min and a density of 0.885-0.910 g / cm 3 The processing aid used in the middle and inner layers has a melt index of 5 to 8 g / 10 min and a density of 0.890 to 0.910 g / cm 3 .

[0015] Preferably, the model of the first ethylene-vinyl acetate copolymer is FL00112; the model of the second ethylene-vinyl acetate copolymer is 7350F and / or 18F3; the model of the degradation masterbatch used in the outer layer is TRF-57, and the model of the additive used in the outer layer is PA0895LD and / or PPA-3.

[0016] Preferably, the model of the block copolymer polypropylene used in the middle layer is J351F; the model of the random copolymer polypropylene used in the middle layer is RP271M; the model of the modified toughening material used in the middle layer is A4085S;

[0017] The random copolymer polypropylene used in the inner layer is of model R301; the block copolymer polypropylene used in the inner layer is of model CF309 and / or PPR-F08E;

[0018] The model of the degradation masterbatch used in the middle layer and the inner layer is PLMV3.3; the model of the processing aid used in the middle layer and the inner layer is PA0833PPR and / or PPA-3.

[0019] Preferably, taking the total mass of the outer layer, the middle layer and the inner layer as 100%, the mass fraction of the outer layer is 12.5-25%, the mass fraction of the middle layer is 40-75%, and the mass fraction of the inner layer is 12.5-40%; the thickness of the high-strength degradable express bag film is 50-100 μm.

[0020] The present invention also provides a method for preparing the heat-resistant and oil-resistant degradable lunch box film described in the above scheme, comprising the following steps:

[0021] The raw materials for the outer layer, the middle layer and the inner layer are subjected to three-layer co-extrusion blown film to obtain the heat-resistant and oil-resistant degradable lunch box film.

[0022] Preferably, the three-layer co-extrusion blown film process specifically includes: feeding the raw materials for the outer layer, middle layer and inner layer into the outer layer, middle layer and inner layer extruders respectively for melting and plasticizing, conveying the obtained glue solution to the die head, extruding and blowing the film to obtain a film bubble, and after the film bubble is cooled, drying, corona treatment, edge trimming, downward pulling and winding are performed in sequence to obtain the heat-resistant and oil-resistant degradable lunch box film.

[0023] Preferably, the outer layer extruder, the middle layer extruder and the inner layer extruder are all provided with 5 heating zones, which are recorded as zones 1 to 5 in the order in which the raw materials pass; the temperature of zone 1 of the outer layer extruder is 140±5°C, the temperature of zone 2 is 150±5°C, the temperature of zone 3 is 158±5°C, the temperature of zone 4 is 165±5°C, and the temperature of zone 5 is 160±5°C; the temperature of zone 1 of the middle layer extruder is 180±5°C, the temperature of zone 2 is 188±5°C, the temperature of zone 3 is 192±5°C, the temperature of zone 4 is 186±5°C, and the temperature of zone 5 is 180±5°C; the temperature of zone 1 of the inner layer extruder is 190±5°C, the temperature of zone 2 is 195±5°C, the temperature of zone 3 is 200±5°C, the temperature of zone 4 is 200±5°C, and the temperature of zone 5 is 190±5°C;

[0024] The die head is divided into 4 heating zones, which are respectively recorded as zones 1 to 4 in the order in which the glue passes through. The temperature of zone 1 of the die head is 200±5°C, the temperature of zone 2 is 203±5°C, the temperature of zone 3 is 210±5°C, and the temperature of zone 4 is 200±5°C.

[0025] The present invention also provides a heat-resistant and oil-resistant degradable lunch box, comprising a degradable lunch box and a lunch box film arranged on the surface of the degradable lunch box; the lunch box film is the heat-resistant and oil-resistant degradable lunch box film described in the above scheme or the heat-resistant and oil-resistant degradable lunch box film prepared by the preparation method described in the above scheme.

[0026] The invention provides a heat-resistant and oil-resistant degradable lunch box film, which is made of a three-layer co-extruded blown film of an outer layer, a middle layer and an inner layer; the raw materials for preparing the outer layer include, by weight: 10 to 40 parts of a first ethylene-vinyl acetate copolymer, 30 to 85 parts of a second ethylene-vinyl acetate copolymer, 1.5 to 2.5 parts of a degradation masterbatch, and 0.3 to 1.5 parts of a processing aid; the melt index of the first ethylene-vinyl acetate copolymer is 0.2 to 1.0 g / 10 min, and the density is 0.925 to 0.940 g / cm 3 The melt index of the second ethylene-vinyl acetate copolymer is 1.2 to 2.5 g / 10 min and the density is 0.930 to 0.945 g / cm 3; In terms of mass fractions, the raw materials for preparing the middle layer include: 15-45 parts of block copolymer polypropylene, 25-85 parts of random copolymer polypropylene, 10-20 parts of modified toughening materials, 1.5-2.5 parts of degradation masterbatch, and 0.3-1.5 parts of processing aids; In terms of mass fractions, the raw materials for preparing the inner layer include: 15-40 parts of random copolymer polypropylene, 30-85 parts of block copolymer polypropylene, 1.5-2.5 parts of degradation masterbatch, and 0.3-1.5 parts of processing aids. The present invention strictly controls the raw materials for preparing the three layers of the degradable lunch box film, which can ensure that the obtained lunch box film has good heat and oil resistance, high mechanical properties and low haze; at the same time, the present invention adds degradable masterbatch to the outer layer, middle layer and inner layer, which can convert traditional plastic polypropylene and ethylene-vinyl acetate copolymer into a new generation of biodegradable plastics that are non-toxic and harmless to nature. The obtained degradable lunch box film can be completely degraded into carbon dioxide and water, and will not produce microplastics, and will not change the performance of the plastic film. The results of the embodiments show that the degradable lunch box film provided by the present invention is treated with 100°C hot oil for 30 minutes without the phenomenon of stratification and bubbles, and can be effectively degraded under light, thermal oxygen and composting conditions; the lunch box film of the present invention is applied to the degradable lunch box, and there is no need to separate the lunch box and the film after use, and they can be degraded synchronously as a whole. DETAILED DESCRIPTION

[0027] The present invention provides a heat-resistant and oil-resistant degradable lunch box film, which is made of a three-layer co-extruded blown film of an outer layer, a middle layer and an inner layer;

[0028] In terms of weight, the raw materials for preparing the outer layer include: 10 to 40 parts of a first ethylene-vinyl acetate copolymer, 30 to 85 parts of a second ethylene-vinyl acetate copolymer, 1.5 to 2.5 parts of a degradation masterbatch, and 0.3 to 1.5 parts of a processing aid; the melt index of the first ethylene-vinyl acetate copolymer is 0.2 to 1.0 g / 10 min, and the density is 0.925 to 0.940 g / cm 3 The melt index of the second ethylene-vinyl acetate copolymer is 1.2 to 2.5 g / 10 min and the density is 0.930 to 0.945 g / cm 3 ;

[0029] The raw materials for preparing the middle layer include, by weight: 15 to 45 parts of block copolymer polypropylene, 25 to 85 parts of random copolymer polypropylene, 10 to 20 parts of modified toughening material, 1.5 to 2.5 parts of degradation masterbatch, and 0.3 to 1.5 parts of processing aid;

[0030] Calculated by weight, the raw materials for preparing the inner layer include: 15 to 40 parts of random copolymer polypropylene, 30 to 85 parts of block copolymer polypropylene, 1.5 to 2.5 parts of degradation masterbatch, and 0.3 to 1.5 parts of processing aid.

[0031] In the present invention, unless otherwise specified, the raw materials used in the present invention are preferably commercially available products.

[0032] In terms of mass fractions, the raw materials for preparing the outer layer include 10 to 40 parts of a first ethylene-vinyl acetate copolymer (EVA), preferably 20 to 30 parts; the melt index of the first ethylene-vinyl acetate copolymer is 0.2 to 1.0 g / 10 min, preferably 0.5 to 0.8 g / 10 min, and the density is 0.925 to 0.940 g / cm 3 , preferably 0.930 to 0.934 g / cm 3 In a specific embodiment of the present invention, the first ethylene-vinyl acetate copolymer is preferably FL00112, manufactured by Exxon, having a melt index of 0.5 g / 10 min and a density of 0.934 g / cm 3 It has the characteristics of high polarity, good hot viscosity, good compatibility with polypropylene and easy processing.

[0033] Based on the mass fraction of the first ethylene-vinyl acetate copolymer used in the outer layer, the raw material for preparing the outer layer includes 30 to 85 parts of the second ethylene-vinyl acetate copolymer, preferably 40 to 70 parts; the melt index of the second ethylene-vinyl acetate copolymer is 1.2 to 2.5 g / 10 min, preferably 1.8 to 2.5 g / 10 min, and the density is 0.930 to 0.945 g / cm 3 , preferably 0.938 to 0.94 g / cm 3 In a specific embodiment of the present invention, the model of the second ethylene-vinyl acetate copolymer is preferably 7350F and / or 18F3, wherein the manufacturer of the second ethylene-vinyl acetate copolymer with model 7350F is China Taiwan Plastics Industry Co., Ltd., and its melt index is 1.8g / 10min and density is 0.938g / cm 3 The manufacturer of the second ethylene-vinyl acetate copolymer with model 18F3 is Yanshan Petrochemical, with a melt index of 2.5g / 10min and a density of 0.94g / cm 3 The second ethylene-vinyl acetate copolymer used in the present invention has the characteristics of high polarity, good hot viscosity, good compatibility with polypropylene, and easy processing.

[0034] Based on the mass fraction of the first ethylene-vinyl acetate copolymer used in the outer layer, the raw material for preparing the outer layer includes 1.5 to 2.5 parts of the degradation masterbatch, preferably 1.8 to 2.2 parts; the melt index of the degradation masterbatch used in the outer layer is preferably 46 to 55 g / 10min, more preferably 48 to 51.6 g / 10min, and the density is preferably 0.920 to 0.940 g / cm 3 , more preferably 0.925 to 0.930 g / cm 3In a specific embodiment of the present invention, the degradation masterbatch used in the outer layer is TRF-57, produced by British Polymateria Company, with a melt index of 51.6 g / min and a density of 0.930 g / cm 3 ; The degradation masterbatch used in the outer layer of the present invention has the following advantages: the advanced catalytic system can convert ethylene, propylene and copolymer materials into bioavailable wax, which can be easily assimilated by naturally existing microorganisms without the need for a specific environment; the degradation masterbatch can adjust the degradation time according to different usage conditions and usage cycles, and the degradation time is controllable; no microplastics or toxic substances will be left in the post-degradation stage, and it is harmless to nature; after adding the degradation masterbatch, the physical properties of the film are no different from those of traditional plastics, and the physical properties of the product will not be reduced. Compared with other degradable films, it has a wider range of applications and lower costs; adding the degradation masterbatch does not require changing the original process equipment, saving upgrade costs and meeting the requirements of green and sustainable development; it can be recycled and granulated together with general plastics without affecting the physical properties. Under the catalytic action of the degradation masterbatch, the plastic will undergo the following three chemical reactions: 1. Free radical initiation: when exposed to energy such as light and heat, the carbon structure chain of the polyethylene molecular bond breaks to generate highly active free radicals; 2. Free radical growth: highly active free radicals react rapidly under aerobic conditions to generate intermediates such as peroxyl radicals or hydroperoxyl radicals; 3. Chain termination: compounds containing unstable peroxyl radicals or hydroperoxyl radicals undergo molecular bond rupture and a series of chemical reactions to generate small molecular compounds with carbon, hydrogen and oxygen structures, which eventually turn into carbon dioxide, water and wax, which are non-toxic and harmless to nature. The wax is biotransformed through naturally existing bacteria and fungi in the soil and mineralization under open ambient temperature adjustment; the resulting heat-resistant and oil-resistant degradable lunch box film meets the degradation requirements of ASTM6954, GB / T20197 and BSI PAS 9017.

[0035] Based on the mass fraction of the first ethylene-vinyl acetate copolymer used in the outer layer, the raw material for preparing the outer layer includes 0.3 to 1.5 parts of a processing aid, preferably 0.5 to 1 part; the melt index of the processing aid used in the outer layer is preferably 1 to 8 g / 10 min, more preferably 2.1 to 8 g / 10 min, and the density is preferably 0.910 to 0.925 g / cm 3 , more preferably 0.915 to 0.920 g / cm 3 The processing aid is preferably a functional masterbatch prepared from a fluoropolymer and a polyolefin resin; in a specific embodiment of the present invention, the processing aid is preferably PA0895LD and / or PPA-3, wherein the processing aid model PA0895LD has a melt index of 2.1 g / min and a density of 0.915 g / cm 3The manufacturer is Suzhou Constant Engineering Plastics Co., Ltd. The processing aid model PPA-3 has a melt index of 8g / min and a density of 0.92g / cm 3 , the manufacturer is Huayi Technology Development Co., Ltd.; in the specific embodiment of the present invention, when the processing aid model PA0895LD is used, the mass fraction of the processing aid in the outer layer is preferably 0.3 to 1.5 parts, and when the processing aid model PPA-3 is used, the mass fraction of the processing aid in the outer layer is preferably 0.5 to 1 part. The processing aid used in the present invention can effectively reduce die buildup, reduce crystal point, reduce extrusion pressure, and improve production efficiency.

[0036] In terms of mass fraction, the raw materials for preparing the middle layer include 15 to 45 parts of block copolymer polypropylene, preferably 20 to 40 parts; the melt index of the block copolymer polypropylene used in the middle layer is preferably 1.8 to 3.0 g / 10min, more preferably 2.5 to 2.8 g / 10min, and the density is preferably 0.898 to 0.910 g / cm 3 , more preferably 0.90 to 0.905 g / cm 3 In a specific embodiment of the present invention, the block copolymer polypropylene used in the middle layer is preferably of the type J351F and / or R520F, wherein the block copolymer polypropylene of type J351F is manufactured by Korea Hyosung, and has a melt index of 2.5 g / 10 min and a density of 0.90 g / cm 3 The manufacturer of block copolymer polypropylene model R520F is SK Chemical, with a melt index of 1.8g / 10min and a density of 0.90g / cm 3 The block copolymer polypropylene used in the present invention has the characteristics of high stiffness, high transparency, easy processing and the like.

[0037] Based on the mass fraction of the block copolymer polypropylene used in the middle layer, the raw material for preparing the middle layer includes 25 to 85 parts of random copolymer polypropylene, preferably 30 to 80 parts, and more preferably 40 to 60 parts; the melt index of the random copolymer polypropylene used in the middle layer is preferably 7.0 to 9.0 g / 10 min, more preferably 7.0 to 9.0 g / 10 min, and the density is preferably 0.895 to 0.910 g / cm 3 , more preferably 0.90 to 0.905 g / cm 3 In a specific embodiment of the present invention, the block copolymer polypropylene is preferably RP271M, manufactured by LyondellBasell, with a melt index of 8.0 g / 10 min and a density of 0.90 g / cm 3 , with the characteristics of high stiffness, high transparency and easy processing.

[0038] Based on the mass fraction of block copolymer polypropylene used in the middle layer, the raw materials for preparing the middle layer include 10 to 20 parts of modified toughening material, preferably 13 to 18 parts; the melt index of the modified toughening material is preferably 3.0 to 4.0 g / 10 min, more preferably 3.2 to 3.6 g / 10 min, and the density is preferably 0.870 to 0.90 g / cm 3 , more preferably 0.875 to 0.885 g / cm 3 In a specific embodiment of the present invention, the modified toughening material is preferably A4085S, produced by Mitsui Chemicals, with a melt index of 3.6 g / 10 min and a density of 0.885 g / cm 3 , with the characteristics of high toughness, impact resistance and easy processing.

[0039] Based on the mass fraction of block copolymer polypropylene used in the middle layer, the raw material for preparing the middle layer includes 1.5 to 2.5 parts of degradation masterbatch, preferably 1.8 to 2.2 parts; the melt index of the degradation masterbatch used in the middle layer is preferably 85 to 95 g / 10 min, more preferably 90 to 92 g / 10 min, and the density is preferably 0.885 to 0.910 g / cm 3 , more preferably 0.890 to 0.900 g / cm 3 In a specific embodiment of the present invention, the model of the degradable masterbatch used in the middle layer is preferably PLMV3.3, produced by the British Polymateria Company, with a melt index of 90g / min and a density of 0.900g / cm 3; In the present invention, the degradable masterbatch used in the middle layer has the following advantages: the advanced catalytic system of the masterbatch can convert polypropylene material into bioavailable wax, which can be easily assimilated by naturally existing microorganisms without the need for a specific environment; the degradation time can be adjusted according to different usage conditions and usage cycles, and the degradation time is controllable; no microplastics or toxic substances will be left in the post-degradation stage, and it is harmless to nature; after adding the degradation masterbatch, the physical properties of the film are no different from those of traditional plastics, and the physical properties of the product will not be reduced. Compared with other degradable films, it has a wider range of applications and lower costs; adding the degradation masterbatch does not require changing the original process equipment, saving upgrade costs and meeting the requirements of green and sustainable development; it can be recycled and granulated together with general plastics without affecting the physical properties. Under the catalytic action of the degradation masterbatch, the plastic will undergo the following three chemical reactions: 1. Free radical initiation: When subjected to energy such as light and heat, the carbon structure chain of the polyethylene molecular bond is broken to generate highly active free radicals; 2. Free radical growth: Under aerobic conditions, highly active free radicals react rapidly to generate intermediate products such as peroxyl radicals or hydroperoxyl radicals; 3. Chain termination: Compounds containing unstable peroxyl radicals or hydroperoxyl radicals undergo molecular bond breaking and a series of chemical reactions to generate small molecular compounds with carbon, hydrogen and oxygen structures, which eventually become carbon dioxide, water and wax, which are non-toxic and harmless to nature. The wax is biotransformed through naturally existing bacteria and fungi in the soil and mineralization under open ambient temperature adjustment; the resulting heat-resistant and oil-resistant degradable lunch box film meets the degradation requirements of ASTM6954, GB / T20197 and BSIPAS 9017.

[0040] Based on the mass fraction of the block copolymer polypropylene used in the middle layer, the raw material for preparing the middle layer includes 0.3 to 1.5 parts of processing aid, preferably 0.5 to 1 parts; the melt index of the processing aid used in the middle layer is preferably 5.0 to 8.0 g / 10 min, more preferably 6.0 to 7.5 g / 10 min, and the density is preferably 0.890 to 0.910 g / cm 3 , more preferably 0.895 to 0.90 g / cm 3 In a specific embodiment of the present invention, the block copolymer polypropylene used in the middle layer is preferably PA0833PPR and / or PPA-3, wherein the model PA0833PPR is manufactured by Suzhou Constant Engineering Plastics Co., Ltd., and its melt index is 6.0g / min and its density is 0.90g / cm 3 The processing aid model PPA-3 has a melt index of 8g / min and a density of 0.92g / cm 3, the manufacturer is Huayi Technology Development Co., Ltd.; in the specific embodiment of the present invention, when the processing aid model PA0833PPR is used, the mass fraction of the processing aid in the middle layer is preferably 0.3 to 1.5 parts, and when the processing aid model PPA-3 is used, the mass fraction of the processing aid in the middle layer is preferably 0.5 to 1 part. The processing aid used in the present invention has good high temperature resistance, can effectively reduce die mouth material accumulation, reduce crystal point and reduce extrusion pressure, and improve production efficiency.

[0041] In terms of mass fraction, the raw material for preparing the inner layer includes 15 to 40 parts of random copolymer polypropylene, preferably 20 to 35 parts; the melt index of the random copolymer polypropylene used in the inner layer is preferably 1.0 to 2.0 g / 10 min, more preferably 1.5 to 1.8 g / 10 min, and the density is preferably 0.890 to 0.910 g / cm 3 , more preferably 0.895 to 0.900 g / cm 3 In a specific embodiment of the present invention, the random copolymer polypropylene used in the inner layer is preferably R301, produced by Hyosung of South Korea, with a melt index of 1.5g / 10min and a density of 0.900g / cm 3 , with high transparency, high strength, high temperature resistance and easy processing properties.

[0042] Based on the mass fraction of random copolymer polypropylene used in the inner layer, the raw material for preparing the inner layer includes 30 to 85 parts of block copolymer polypropylene, preferably 40 to 80 parts; the melt index of the block copolymer polypropylene used in the inner layer is preferably 4 to 8 g / 10 min, more preferably 5 to 8 g / 10 min, and the density is preferably 0.90 to 0.920 g / cm 3 , more preferably 0.910 to 0.915 g / cm 3 In a specific embodiment of the present invention, the block copolymer polypropylene used in the inner layer is preferably CF309 and / or PPR-F08E, wherein the block copolymer polypropylene model CF309 is produced by Samsung Total, has a melt index of 5.0 g / 10 min, and a density of 0.910 g / cm 3 The manufacturer of block copolymer polypropylene model PPR-F08E is Zhongke Refining and Chemical, with a melt index of 8g / 10min and a density of 0.9g / cm 3 The block copolymer polypropylene used in the present invention has the properties of high transparency, high gloss, high temperature resistance, high impact strength, stress whitening resistance and the like.

[0043] Based on the mass fraction of 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 2.0 parts; the melt index, density and specific brand of the degradation masterbatch used in the inner layer are preferably consistent with those of the degradation masterbatch used in the middle layer, which will not be repeated here.

[0044] Based on the mass fraction of random copolymer polypropylene used in the inner layer, the raw materials for preparing the inner layer include 0.3 to 1.5 parts of processing aid, preferably 0.5 to 1 part; the melt index, density and specific brand of the processing aid used in the inner layer are preferably consistent with the processing aid used in the middle layer, which will not be repeated here. In a specific embodiment of the present invention, when a processing aid model PA0833PPR is used, the mass fraction of the processing aid in the inner layer is preferably 0.3 to 1.5 parts, and when a processing aid model PPA-3 is used, the mass fraction of the processing aid in the inner layer is preferably 0.5 to 1 part.

[0045] In the present invention, taking the total mass of the outer layer, the middle layer and the inner layer as 100%, the mass fraction of the outer layer is preferably 12.5-25%, more preferably 15%, 20% or 25%, the mass fraction of the middle layer is preferably 40-75%, more preferably 40%, 50% or 60%, the mass fraction of the inner layer is preferably 12.5-40%, more preferably 15%, 25% or 40%; the thickness of the high-strength degradable express bag film is preferably 50-100 μm, more preferably 60-80 μm.

[0046] In the present invention, the longitudinal tensile strength of the heat-resistant and oil-resistant degradable lunch box film is preferably 42.9-44.2 MPa, the transverse tensile strength is preferably 37.2-40.1 MPa, the longitudinal elongation at break is preferably 610%-625%, the transverse elongation at break is preferably 715%-730%, the wetting tension is preferably 40-45 mN / 15mm, the haze is preferably less than 10%, more preferably 9.1%-9.8%; the heat-resistant and oil-resistant degradable lunch box film is treated with 100°C hot oil for 30 minutes, without stratification or bubbling, and can be effectively degraded under natural environment, photodegradation, thermal oxidation degradation and composting conditions.

[0047] The present invention also provides a method for preparing the heat-resistant and oil-resistant degradable lunch box film described in the above scheme, comprising the following steps:

[0048] The raw materials for the outer layer, the middle layer and the inner layer are subjected to three-layer co-extrusion blown film to obtain the heat-resistant and oil-resistant degradable lunch box film.

[0049] In the present invention, the process of three-layer co-extrusion blown film specifically includes: feeding the raw materials for the outer layer, the middle layer and the inner layer into the outer layer, the middle layer and the inner layer extruders respectively for melting and plasticizing, conveying the obtained glue solution to the die head, extruding and blowing the film to obtain a film bubble, and after the film bubble is cooled, drying, corona treatment, edge trimming, downward pulling and winding are performed in sequence to obtain the heat-resistant and oil-resistant degradable lunch box film.

[0050] In the present invention, the outer layer extruder, the middle layer extruder and the inner layer extruder are preferably provided with 5 heating zones, which are sequentially recorded as zones 1 to 5 according to the order in which the raw materials pass; the temperature of zone 1 of the outer layer extruder is preferably 140±5°C, the temperature of zone 2 is preferably 150±5°C, the temperature of zone 3 is preferably 158±5°C, the temperature of zone 4 is preferably 165±5°C, and the temperature of zone 5 is preferably 160±5°C; the temperature of zone 1 of the middle layer extruder is preferably 180±5°C, the temperature of zone 2 is preferably 188±5°C, the temperature of zone 3 is preferably 192±5°C, the temperature of zone 4 is preferably 186±5°C, and the temperature of zone 5 is preferably 180±5°C; the temperature of zone 1 of the inner layer extruder is preferably 190±5°C, the temperature of zone 2 is preferably 195±5°C, the temperature of zone 3 is preferably 200±5°C, the temperature of zone 4 is preferably 200±5°C, and the temperature of zone 5 is preferably 190±5°C.

[0051] In the present invention, the extrusion pressure of the outer layer extruder is preferably 175 to 230 bar, the extrusion pressure of the middle layer extruder is preferably 195 to 215 bar, and the extrusion pressure of the inner layer extruder is preferably 185 to 235 bar.

[0052] In the present invention, the die is preferably divided into four heating zones, which are respectively recorded as zones 1 to 4 in the order in which the glue passes through. The temperature of zone 1 of the die is preferably 200±5°C, the temperature of zone 2 is preferably 203±5°C, the temperature of zone 3 is preferably 210±5°C, and the temperature of zone 4 is preferably 200±5°C.

[0053] In the present invention, the cooling temperature is preferably 15-20°C, and the cooling device is preferably a cooling water ring; the cooled film bubbles enter the dryer for drying through a herringbone arrangement, and the drying temperature is preferably 45±5°C.

[0054] The present invention also provides a heat-resistant and oil-resistant degradable lunch box, comprising a degradable lunch box and a lunch box film arranged on the surface of the degradable lunch box; the lunch box film is the heat-resistant and oil-resistant degradable lunch box film described in the above scheme or the heat-resistant and oil-resistant degradable lunch box film prepared by the preparation method described in the above scheme; the present invention has no special requirements for the degradable lunch box, and can adopt those well known to those skilled in the art, such as a degradable lunch box made of plant fibers, and the plant fibers preferably include bagasse or straw. The heat-resistant and oil-resistant degradable lunch box of the present invention does not need to separate the film and the lunch box after use, and can be integrated and degraded synchronously, which is convenient to use.

[0055] The present invention has no special requirements for the preparation method of the heat-resistant and oil-resistant degradable lunch box, and can be prepared by methods familiar to those skilled in the art. In a specific embodiment of the present invention, conventional laminating equipment is used to coat the heat-resistant and oil-resistant degradable lunch box film on the degradable lunch box.

[0056] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within 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 1.

[0058] Table 1 Raw material sources and performance parameters

[0059]

[0060] Example 1

[0061] The heat-resistant and oil-resistant biodegradable lunch box film of this embodiment is made of a co-extruded blown film of an outer layer, a middle layer and an inner layer, and the weight percentages of the materials of each layer among the three layers are respectively: 20% for the outer layer, 40% for the middle layer, and 40% for the inner layer.

[0062] The amount of raw materials for each layer is shown in Table 2. The total thickness of the heat-resistant and oil-resistant degradable lunch box film is 80 μm. The preparation method is as follows:

[0063] The raw materials for the outer layer, middle layer and inner layer are mixed in proportion through an automatic batching system and then sent to the outer layer, middle layer and inner layer extruder. The raw materials for the outer layer, middle layer and inner layer are melted and plasticized and then sent to the die head for extrusion and downward blowing. They are cooled by a cooling water ring with the cooling temperature controlled at 15-20°C. They are dried in a herringbone dryer with a drying temperature of 45°C±5 degrees. They are then sent to a corona treatment device through a guide roller for corona treatment. The trimmed edges are then sent to the front and rear winding device through the lower traction roller for front and rear winding to obtain a heat-resistant, oil-resistant and degradable lunch box film with a thickness of 80μm.

[0064] The temperatures of each zone of the outer layer, middle layer, inner layer extruder and die head, as well as the pressure of the outer layer, middle layer, inner layer extruder are shown in Table 3.

[0065] Table 2 Amount of raw materials used in Examples 1 to 3 and Comparative Example 2 (by mass)

[0066]

[0067]

[0068] Table 3 Temperature and pressure of extruder and die head

[0069] temperature Zone 1 / ℃ Zone 2 / ℃ Zone 3 / ℃ Zone 4 / ℃ Zone 5 / ℃ Pressure / bar Outer Layer 140 150 158 165 160 210 Middle level 180 188 192 186 180 205 Inner Layer 190 195 200 200 190 215 Die head 200 203 210 200 / /

[0070] The heat-resistant and oil-resistant degradable lunch box film is coated on the degradable lunch box made of bagasse by using a laminating device to obtain the heat-resistant and oil-resistant degradable lunch box.

[0071] Example 2

[0072] The heat-resistant and oil-resistant degradable lunch box film of this embodiment is made of a three-layer co-extruded blown film of an outer layer, a middle layer and an inner layer. The weight percentages of the materials of each layer between the three layers are: 15% for the outer layer, 60% for the middle layer, and 25% for the inner layer. The amount of raw materials used for each layer is shown in Table 2. The preparation method is the same as that of Example 1, and the film thickness is 80 μm.

[0073] The obtained heat-resistant and oil-resistant degradable lunch box film is coated on a degradable lunch box made of bagasse by using a coating device to obtain a heat-resistant and oil-resistant degradable lunch box.

[0074] Example 3

[0075] The heat-resistant and oil-resistant degradable lunch box film of this embodiment is made of a three-layer co-extruded blown film of an outer layer, a middle layer and an inner layer. The weight percentages of the materials of each layer between the three layers are: 25% for the outer layer, 50% for the middle layer, and 25% for the inner layer. The amount of raw materials used for each layer is shown in Table 2. The preparation method is the same as that of Example 1, and the film thickness is 80 μm.

[0076] The obtained heat-resistant and oil-resistant degradable lunch box film is coated on a degradable lunch box made of bagasse by using a coating device to obtain a heat-resistant and oil-resistant degradable lunch box.

[0077] Example 4

[0078] The heat-resistant and oil-resistant degradable lunch box film of this embodiment is made of a three-layer co-extruded blown film of an outer layer, a middle layer and an inner layer. The weight percentages of the materials of each layer between the three layers are: 17% for the outer layer, 50% for the middle layer, and 33% for the inner layer. The amount of raw materials used for each layer is shown in Table 2. The preparation method is the same as that of Example 1, and the film thickness is 80 μm.

[0079] The obtained heat-resistant and oil-resistant degradable lunch box film is coated on a degradable lunch box made of bagasse by using a coating device to obtain a heat-resistant and oil-resistant degradable lunch box.

[0080] Example 5

[0081] The heat-resistant and oil-resistant degradable lunch box film of this embodiment is made of a three-layer co-extruded blown film of an outer layer, a middle layer and an inner layer. The weight percentages of the materials of each layer between the three layers are: 15% for the outer layer, 55% for the middle layer, and 30% for the inner layer. The amount of raw materials used for each layer is shown in Table 2. The preparation method is the same as that of Example 1, and the film thickness is 80 μm.

[0082] The obtained heat-resistant and oil-resistant degradable lunch box film is coated on a degradable lunch box made of bagasse by using a coating device to obtain a heat-resistant and oil-resistant degradable lunch box.

[0083] Example 6

[0084] The heat-resistant and oil-resistant degradable lunch box film of this embodiment is made of a three-layer co-extruded blown film of an outer layer, a middle layer and an inner layer. The weight percentages of the materials of each layer between the three layers are: 20% for the outer layer, 55% for the middle layer, and 25% for the inner layer. The amount of raw materials used for each layer is shown in Table 2. The preparation method is the same as that of Example 1, and the film thickness is 80 μm.

[0085] The obtained heat-resistant and oil-resistant degradable lunch box film is coated on a degradable lunch box made of bagasse by using a coating device to obtain a heat-resistant and oil-resistant degradable lunch box.

[0086] Comparative Example 1

[0087] The heat-resistant and oil-resistant biodegradable lunch box film of this comparative example is made of a three-layer co-extruded blown film of an outer layer, a middle layer and an inner layer, and the weight percentages of the materials of each layer among the three layers are respectively: 20% for the outer layer, 50% for the middle layer, and 30% for the inner layer.

[0088] The EVA used in the outer layer is FL00112 from Exxon, the processing aid is PA0895LD from Suzhou Constant Engineering Plastics Co., Ltd., the copolymer polypropylene used in the middle layer is RB707CF from Borouge, the block copolymer polypropylene used in the inner layer is J310F from Hyosung of South Korea, and the processing aids used in the middle and inner layers are PA0833PPR from Suzhou Constant. The properties and amounts of the raw materials are shown in Table 4.

[0089] Table 4 Comparative Example 1 Raw material dosage (by mass fraction)

[0090]

[0091] The preparation method is the same as that in Example 1, and the film thickness is 80 μm.

[0092] Comparative Example 2

[0093] The heat-resistant and oil-resistant degradable lunch box film of this comparative example is made of a three-layer co-extruded blown film of an outer layer, a middle layer and an inner layer, and the weight percentages of the materials of each layer between the three layers are: 20% for the outer layer, 40% for the middle layer, and 40% for the inner layer. The amount of raw materials used for each layer is shown in Table 2, the preparation method is the same as that of Example 1, and the film thickness is 80 μm.

[0094] Performance Test:

[0095] The mechanical properties, wetting tension, haze, hot oil resistance and degradation properties of the films prepared in Examples 1 to 6 and Comparative Examples 1 to 2 were tested. The standards based on the tests and the test results are shown in Table 5.

[0096] Table 5 Performance test results

[0097]

[0098] According to the data in Table 5, it can be seen that the heat-resistant and oil-resistant degradable lunch box film has good mechanical properties, high wetting tension, low haze, good transparency, and can be effectively degraded under light, thermal oxygen and composting conditions. In Comparative Example 1, the raw material formula of the three layers was changed, and in Comparative Example 2, the amount of degradation masterbatch in the outer layer, middle layer and inner layer was reduced. The degradation performance of the resulting film under light, thermal oxygen and composting conditions was unqualified.

[0099] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A heat-resistant and oil-resistant degradable lunch box film, characterized in that: Made of three layers of co-extruded blown film: outer layer, middle layer and inner layer; In terms of weight, the raw materials for preparing the outer layer include: 10 to 40 parts of a first ethylene-vinyl acetate copolymer, 30 to 85 parts of a second ethylene-vinyl acetate copolymer, 1.5 to 2.5 parts of a degradation masterbatch, and 0.3 to 1.5 parts of a processing aid; the melt index of the first ethylene-vinyl acetate copolymer is 0.2 to 1.0 g / 10 min, and the density is 0.925 to 0.940 g / cm 3 The melt index of the second ethylene-vinyl acetate copolymer is 1.2 to 2.5 g / 10 min and the density is 0.930 to 0.945 g / cm 3 ; The raw materials for preparing the middle layer include, by weight: 15 to 45 parts of block copolymer polypropylene, 25 to 85 parts of random copolymer polypropylene, 10 to 20 parts of modified toughening material, 1.5 to 2.5 parts of degradation masterbatch, and 0.3 to 1.5 parts of processing aid; Calculated by weight, the raw materials for preparing the inner layer include: 15 to 40 parts of random copolymer polypropylene, 30 to 85 parts of block copolymer polypropylene, 1.5 to 2.5 parts of degradation masterbatch, and 0.3 to 1.5 parts of processing aid.

2. The heat-resistant and oil-resistant degradable lunch box film according to claim 1, characterized in that: The block copolymer polypropylene used in the middle layer has a melt index of 1.8 to 3.0 g / 10 min and a density of 0.898 to 0.910 g / cm 3 The random copolymer polypropylene used in the middle layer has a melt index of 7.0 to 9.0 g / 10 min and a density of 0.895 to 0.910 g / cm 3 The modified toughening material used in the middle layer has a melt index of 3.0 to 4.0 g / 10 min and a density of 0.870 to 0.90 g / cm 3 ; The random copolymer polypropylene used in the inner layer has a melt index of 1.0-2.0 g / 10 min and a density of 0.890-0.910 g / cm 3 The block copolymer polypropylene used in the inner layer has a melt index of 4 to 8 g / 10 min and a density of 0.90 to 0.920 g / cm 3 .

3. The heat-resistant and oil-resistant degradable lunch box film according to claim 1, characterized in that: The degradation masterbatch used in the outer layer has a melt index of 46-55 g / 10 min and a density of 0.920-0.940 g / cm 3 The processing aid used in the outer layer has a melt index of 1.0 to 8.0 g / 10 min and a density of 0.910 to 0.925 g / cm 3 ; The degradation masterbatch used in the middle layer and the inner layer has a melt index of 85-95 g / 10 min and a density of 0.885-0.910 g / cm 3 The processing aid used in the middle and inner layers has a melt index of 5 to 8 g / 10 min and a density of 0.890 to 0.910 g / cm 3 .

4. The heat-resistant and oil-resistant degradable lunch box film according to claim 1, characterized in that: The model of the first ethylene-vinyl acetate copolymer is FL00112; the model of the second ethylene-vinyl acetate copolymer is 7350F and / or 18F3; the model of the degradation masterbatch used in the outer layer is TRF-57, and the model of the additive used in the outer layer is PA0895LD and / or PPA-3.

5. The heat-resistant and oil-resistant degradable lunch box film according to any one of claims 1 to 3, characterized in that: The block copolymer polypropylene used in the middle layer is of model J351F and / or R520F; the random copolymer polypropylene used in the middle layer is of model RP271M; the modified toughening material used in the middle layer is of model A4085S; The random copolymer polypropylene used in the inner layer is of model R301; the block copolymer polypropylene used in the inner layer is of model CF309 and / or PPR-F08E; The model of the degradation masterbatch used in the middle layer and the inner layer is PLMV3.3; the model of the processing aid used in the middle layer and the inner layer is PA0833PPR and / or PPA-3.

6. The heat-resistant and oil-resistant degradable lunch box film according to claim 1, characterized in that: Taking the total mass of the outer layer, the middle layer and the inner layer as 100%, the mass fraction of the outer layer is 12.5-25%, the mass fraction of the middle layer is 40-75%, and the mass fraction of the inner layer is 12.5-40%; the thickness of the high-strength degradable express bag film is 50-100 μm.

7. The method for preparing the heat-resistant and oil-resistant degradable lunch box film according to any one of claims 1 to 6, characterized in that: The following steps are involved: The raw materials for the outer layer, the middle layer and the inner layer are subjected to three-layer co-extrusion blown film to obtain the heat-resistant and oil-resistant degradable lunch box film.

8. The preparation method according to claim 7, characterized in that: The three-layer co-extrusion blown film process specifically includes: feeding the prepared raw materials of the outer layer, the middle layer and the inner layer into the outer layer, the middle layer and the inner layer extruders respectively for melting and plasticizing, conveying the obtained glue solution to the die head, extruding and blowing the film to obtain a film bubble, and after the film bubble is cooled, drying, corona treatment, edge trimming, lower traction and winding are performed in sequence to obtain the heat-resistant and oil-resistant degradable lunch box film.

9. The preparation method according to claim 8, characterized in that: The outer layer extruder, the middle layer extruder and the inner layer extruder are all provided with 5 heating zones, which are recorded as zones 1 to 5 in the order in which the raw materials pass; the temperature of zone 1 of the outer layer extruder is 140±5°C, the temperature of zone 2 is 150±5°C, the temperature of zone 3 is 158±5°C, the temperature of zone 4 is 165±5°C, and the temperature of zone 5 is 160±5°C; the temperature of zone 1 of the middle layer extruder is 180±5°C, the temperature of zone 2 is 188±5°C, the temperature of zone 3 is 192±5°C, the temperature of zone 4 is 186±5°C, and the temperature of zone 5 is 180±5°C; the temperature of zone 1 of the inner layer extruder is 190±5°C, the temperature of zone 2 is 195±5°C, the temperature of zone 3 is 200±5°C, the temperature of zone 4 is 200±5°C, and the temperature of zone 5 is 190±5°C; The die head is divided into 4 heating zones, which are respectively recorded as zones 1 to 4 in the order in which the glue passes through. The temperature of zone 1 of the die head is 200±5°C, the temperature of zone 2 is 203±5°C, the temperature of zone 3 is 210±5°C, and the temperature of zone 4 is 200±5°C.

10. A heat-resistant and oil-resistant degradable lunch box, characterized in that: It comprises a degradable lunch box and a lunch box film arranged on the surface of the degradable lunch box; the lunch box film is the heat-resistant and oil-resistant degradable lunch box film described in any one of claims 1 to 6 or the heat-resistant and oil-resistant degradable lunch box film prepared by the preparation method described in any one of claims 7 to 9.

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