A micro-atmosphere fresh-keeping packaging cover film applied to cold fresh meat packaging and a preparation method thereof
By optimizing the multi-layer co-extruded film structure and materials, the problems of high heat shrinkage rate, poor anti-fogging effect and interlayer delamination in chilled meat packaging film have been solved, achieving high transparency and low friction coefficient anti-fogging effect, improving display effect and heat sealing strength.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SUNRISE PACKAGING MATERIAL (JIANGYIN) CO LTD
- Filing Date
- 2023-12-19
- Publication Date
- 2026-05-26
Smart Images
Figure BDA0004614918530000121 
Figure BDA0004614918530000131
Abstract
Description
Technical Field
[0001] This invention relates to the field of food packaging technology, and in particular to a micro-modified atmosphere packaging cap film for use in chilled fresh meat packaging and its preparation method. Background Technology
[0002] There are two main types of modified atmosphere packaging for chilled meat: one is an adhesive composite modified atmosphere cap film, and the other is a multi-layer co-extruded multifunctional micro-modified atmosphere film.
[0003] Traditional adhesive-laminated modified atmosphere film has the following drawbacks: ① After the composite substrate film is removed from the machine, it needs to undergo another adhesive lamination process. After passing through multiple rollers in the laminating machine, the anti-fogging agent will be consumed and the anti-fogging layer is easily contaminated, affecting the effectiveness of the anti-fogging agent; ② There is a risk of excessive solvent residue; ③ After sealing, the film cannot shrink and is in a loose state, resulting in relatively poor transparency and poor display effect on the container.
[0004] With the development of random technology, many multi-layer co-extruded multifunctional micro-modified atmosphere films have appeared on the market, but they all have more or less problems. For example, patent CN 108263062 A discloses a multi-layer shrink anti-fog cover film, including a surface layer and a heat-sealing layer. At least one first barrier layer and at least one second barrier layer are provided between the surface layer and the heat-sealing layer. An adhesive layer is provided between the first barrier layer and the heat-sealing layer and the surface layer. Through the improvement of the raw materials of each layer, the cover film has achieved certain properties such as barrier properties, mechanical strength and heat-sealing strength. However, the problems it solves and the technical effects it achieves are limited. Like other existing technologies, it still has the following problems: high heat shrinkage rate, which leads to deformation of the pre-made box; poor anti-fog effect, easy fogging, making it impossible to see the contents directly, resulting in poor display effect; low peel strength between layers, which easily leads to delamination, leaving another layer of film after peeling off the packaging; severe curling, making it difficult to move on the machine; and inability to achieve surface printing, etc. Summary of the Invention
[0005] To address the shortcomings of existing technologies, this invention provides a micro-modified atmosphere packaging cap film for chilled meat packaging. It is a multi-layer co-extruded film made from the following materials, with each layer composed of the following thickness ratios: a heat-resistant layer (printing layer) with a thickness of 5-20%, a support layer with a thickness of 5-15%, an isolation layer with a thickness of 5-15%, an adhesive layer with a thickness of 5-10%, a protective layer with a thickness of 5-20%, a barrier layer with a thickness of 5-10%, a protective layer with a thickness of 5-20%, an adhesive layer with a thickness of 5-10%, an isolation layer with a thickness of 5-15%, a secondary heat-sealing layer with a thickness of 10-20%, and a heat-sealed anti-fog layer with a thickness of 10-30%.
[0006] A further preferred embodiment of the above-described technical solution is the micro-modified atmosphere packaging cap film, which is a multi-layer co-extruded film made of the following materials, wherein each layer is composed of the following layer thickness ratio: a heat-resistant layer (printing layer) with a thickness of 12-15%, a support layer with a thickness of 8-12%, an isolation layer with a thickness of 3-6%, an adhesive layer with a thickness of 3-6%, a protective layer with a thickness of 12-15%, a barrier layer with a thickness of 3-6%, a protective layer with a thickness of 12-15%, an adhesive layer with a thickness of 3-6%, an isolation layer with a thickness of 3-6%, a secondary heat-sealing layer with a thickness of 8-12%, and a heat-sealed anti-fog layer with a thickness of 13-17%.
[0007] For the technical solution described above, a further preferred embodiment is that the micro-modified atmosphere packaging cap film is a multi-layer co-extruded film made of the following materials, with each layer composed of the following layer thickness ratio: heat-resistant layer (printing layer) 14%, support layer 10%, isolation layer 5%, adhesive layer 5%, protective layer 13%, barrier layer 5%, protective layer 13%, adhesive layer 5%, isolation layer 5%, secondary heat-sealing layer 10%, and heat-sealing anti-freezing layer 15%. Preferably, the heat-resistant layer is made of LLDPE; the support layer is made of LDPE; the isolation layer is made of LLDPE; the adhesive layer is made of MAH-g-EVA; the barrier layer is made of EVOH. Preferably, the grafting rate of the MAH-g-EVA is 1.1-1.4%.
[0008] For the technical solution described above, a further preferred embodiment is that the protective layer of the micro-modified atmosphere packaging cap film is made of COPA and amorphous PA, with COPA comprising 75-85 wt% and amorphous PA comprising 15-25 wt%.
[0009] For the technical solution described above, a further preferred embodiment is that the protective layer of the micro-modified atmosphere packaging cap film is made of COPA and amorphous PA, with COPA comprising 80 wt% and amorphous PA comprising 20 wt%.
[0010] For the technical solution described above, a further preferred embodiment is that the material of the secondary heat-sealing anti-fog layer of the micro-modified atmosphere packaging cap film is LDPE and an anti-fog agent, wherein the LDPE is 80-90wt% and the anti-fog agent is 10-20wt%.
[0011] For the technical solution described above, a further preferred embodiment is that the material of the secondary heat-sealing anti-fog layer of the micro-modified atmosphere packaging cap film is LDPE and an anti-fog agent, wherein the LDPE is 85wt% and the anti-fog agent is 15wt%.
[0012] In a further preferred embodiment of the above-described technical solution, the heat-sealing anti-fog layer of the micro-modified atmosphere packaging cap film is made of EPE, an anti-fog agent, and an opening agent, wherein the EPE content is 70-80 wt%, the anti-fog agent content is 15-25 wt%, and the opening agent content is 3-8 wt%.
[0013] In a further preferred embodiment of the above-described technical solution, the heat-sealing anti-fog layer of the micro-modified atmosphere packaging cap film is made of EPE, an anti-fog agent, and an opening agent, wherein the EPE content is 75 wt%, the anti-fog agent content is 20 wt%, and the opening agent content is 5 wt%.
[0014] Another aspect of the present invention protects the method for preparing the micro-modified atmosphere packaging cap film, comprising the following steps:
[0015] The first layer involves adding the LLDPE material for the heat-resistant layer into the hopper of the extruder, melting it at a temperature of 190-220℃, and then feeding it into the die.
[0016] For the second layer, the raw material LDPE for the support layer is added to the hopper of the extruder, melted at a temperature of 190-220℃, and then enters the die.
[0017] In the third layer, the raw material LLDPE for the isolation layer is added to the hopper of the extruder, melted at a temperature of 190-220℃, and then enters the die.
[0018] For the fourth layer, the raw material MAH-g-EVA for the adhesive layer is added to the hopper of the extruder, melted at a temperature of 190-220℃, and then enters the die.
[0019] For the fifth layer, the raw materials for the protective layer, 80wt% COPA and 20wt% amorphous PA, are added to the hopper of the extruder and melted at a temperature of 220-250℃ before entering the die.
[0020] For the sixth layer, the raw material EVOH for the barrier layer is added to the hopper of the extruder, melted at a temperature of 190-210℃, and then enters the die.
[0021] For the 7th layer, the raw materials for the protective layer, consisting of 80wt% COPA and 20wt% amorphous PA, are added to the hopper of the extruder and melted at a temperature of 220-250℃ before entering the die.
[0022] For the 8th layer, the raw material MAH-g-EVA for the adhesive layer is added to the hopper of the extruder, melted at a temperature of 190-220℃, and then enters the die.
[0023] For the 9th layer, the raw material LLDPE for the isolation layer is added to the hopper of the extruder, melted at a temperature of 190-220℃, and then enters the die.
[0024] For the 10th layer, 85wt% LDPE and 15wt% antifogging agent, the raw materials for the secondary heat-sealing antifogging layer, are added to the hopper of the extruder and melted at a temperature of 190-220℃ before entering the die.
[0025] For the 11th layer, the raw materials for the heat-sealing anti-fog layer, namely 75wt% EPE, 20wt% anti-fog agent, and 5wt% opening agent, are added to the hopper of the extruder and melted at a temperature of 180-220℃ before entering the die.
[0026] Compared with the prior art, the present invention has the following beneficial effects:
[0027] ① To regulate the aggregated structure of PA materials, study the crystallinity, orientation and intermolecular forces of different aggregated structures, and control the thermal shrinkage rate of the film;
[0028] ② By designing and controlling the interface between the adhesive layer and the PA layer under a high blow-up ratio, the problem of interlayer delamination that is easy to occur in existing products on the market has been solved;
[0029] ③ By studying the interaction between the anti-fogging system and the lubrication system, the film can simultaneously possess multiple advantages such as high transparency, low coefficient of friction, and excellent anti-fogging effect;
[0030] ④ By studying the layer structure distribution and the combination of inner and outer layer materials, the problem of easy curling of asymmetric structure products on the market has been solved. Detailed Implementation
[0031] The present invention will be further described below with reference to the embodiments, but it should be understood that the scope of protection of the present invention is not limited to the embodiments.
[0032] In this invention, unless otherwise explicitly stated, percentages and contents are all by mass. Unless otherwise specified, the experimental methods used are conventional methods, and the materials and reagents used are commercially available.
[0033] By studying the aggregated structure of PA, we selected combinations of homopolymer PA, copolymer PA, and amorphous PA, and studied their blow-up properties under different heating conditions, as well as their heat shrinkage rate under heat setting process.
[0034] By selecting adhesive resins with low melting points and high draw ratios, the interfacial compatibility and adhesion with PA are increased under high blow-up ratio conditions, thereby improving peel strength and other physical properties.
[0035] By mixing an inorganic opening agent with an anti-fogging agent, a film with high transparency, low coefficient of friction, and excellent anti-fogging effect can be obtained.
[0036] By selecting the surface material and creating a certain temperature difference with the heat-sealing layer material, and taking into account the crystallization behavior of different materials, different layer thickness ratios are designed to achieve symmetrical structure products that do not curl.
[0037] This invention primarily addresses the shortcomings of existing multi-layer co-extruded multifunctional micro-modified atmosphere films on the market, producing products that meet market demands and have wider equipment adaptability.
[0038] This invention can be produced on blown film machines with 11 or 13 layers and higher, and consists of the following layers from top to bottom: a heat-resistant layer (printing layer) with a thickness of 5-20%, a support layer with a thickness of 5-15%, an isolation layer with a thickness of 5-15%, an adhesive layer with a thickness of 5-10%, a protective layer with a thickness of 5-20%, a barrier layer with a thickness of 5-10%, a protective layer with a thickness of 5-20%, an adhesive layer with a thickness of 5-10%, an isolation layer with a thickness of 5-15%, a secondary heat-sealing layer with a thickness of 10-20%, and a heat-sealed anti-fog layer with a thickness of 10-30%.
[0039] Heat-resistant layer (printed layer) 5-20%, support layer 5-15%, isolation layer 5-15%, adhesive layer 5-10%, protective layer 5-20%, barrier layer 5-10%, protective layer 5-20%, adhesive layer 5-10%, isolation layer 5-15%, secondary heat-sealing anti-fog layer 10-20%, heat-sealing anti-fog layer 10-30%.
[0040] Example 1
[0041] The micro-modified atmosphere packaging cap film for chilled meat packaging of the present invention is a multi-layer co-extruded film made of the following materials, with each layer composed of the following layer thickness ratios: heat-resistant layer (printing layer) 10%, support layer 10%, isolation layer 5%, adhesive layer 7%, protective layer 10%, barrier layer 5%, protective layer 10%, adhesive layer 7%, isolation layer 5%, secondary heat-sealing layer 11%, and heat-sealing anti-fog layer 20%. The heat-sealing anti-fog layer is made of EPE + anti-fog agent + opening slip agent, with EPE 77wt% + anti-fog agent 20wt% + opening slip agent 3wt%. The opening slip agent contains both an opening agent and a slip agent.
[0042] Specific models for each material:
[0043] The heat-resistant layer material is HOPA, specifically BASF's B36L.
[0044] The support layer is made of LDPE, specifically QAPCO's FD0474.
[0045] The insulating layer is made of LLDPE, specifically DOW's 2047G.
[0046] The adhesive layer is made of TIE, specifically Polyram's TL4110.
[0047] The protective layer is made of COPA, specifically BASF's C40LX.
[0048] The barrier layer material is EVOH, specifically NIPPON GOHSEI's SG986.
[0049] The secondary heat-sealing layer is LDPE, specifically Lyondellbasell 2420K.
[0050] The heat-sealing anti-fog layer is made of EPE + anti-fog agent + opening slip agent. The EPE used is DOW 5500G, the anti-fog agent is Sojitz 302HC, and the opening slip agent is A. Schulman FSU105E.
[0051] The blown film includes the following steps:
[0052] The first layer involves adding the heat-resistant layer material HOPA into the hopper of the extruder, melting it at a temperature of 220-250℃, and then feeding it into the die.
[0053] For the second layer, the raw material LDPE for the support layer is added to the hopper of the extruder, melted at a temperature of 190-220℃, and then enters the die.
[0054] In the third layer, the raw material LLDPE for the isolation layer is added to the hopper of the extruder, melted at a temperature of 190-220℃, and then enters the die.
[0055] For the fourth layer, the raw material TIE for the adhesive layer is added to the hopper of the extruder, melted at a temperature of 190-220℃, and then enters the die.
[0056] For the fifth layer, the raw material COPA for the protective layer is added to the hopper of the extruder, melted at a temperature of 220-250℃, and then enters the die.
[0057] For the sixth layer, the raw material EVOH for the barrier layer is added to the hopper of the extruder, melted at a temperature of 190-210℃, and then enters the die.
[0058] For the 7th layer, the raw material COPA for the protective layer is added to the hopper of the extruder, melted at a temperature of 220-250℃, and then enters the die.
[0059] For the 8th layer, the raw material TIE for the adhesive layer is added to the hopper of the extruder, melted at a temperature of 190-220℃, and then enters the die.
[0060] For the 9th layer, the raw material LLDPE for the isolation layer is added to the hopper of the extruder, melted at a temperature of 190-220℃, and then enters the die.
[0061] For the 10th layer, the secondary heat-sealing layer material LDPE is added to the hopper of the extruder, melted at a temperature of 190-220℃, and then enters the die.
[0062] For the 11th layer, the raw materials for the heat-sealing anti-fog layer, EPE 77wt%, anti-fog agent 20wt%, and opening slip agent 3wt%, are added to the hopper of the extruder and melted at a temperature of 180-220℃ before entering the die.
[0063] As mentioned above:
[0064] The third and ninth isolation layers have the same thickness;
[0065] The adhesive layer of layer 4 and layer 8 have the same thickness;
[0066] The fifth protective layer and the seventh protective layer are of the same thickness;
[0067] Then, the preform of the multi-layer co-extruded film is extruded through the die. The preform is fixed in size by a vacuum sizing ring below the die and cooled by a water ring (cooling temperature 10℃) to reduce the crystallinity of the preform. The preform is then passed through a secondary heating device (water bath or infrared heating) by traction rollers to fully preheat the preform (heating temperature 1:80℃) to facilitate secondary blow-blowing into film. The sizing cage on the outside of the film bubble above the secondary blow-blowing die is cooled and stabilized by an air ring to give the film bubble a certain structural strength and determine its fixed diameter and thickness. The film thickness distribution is then controlled by two devices: a rotary traction device and a herringbone clamp. The film is then transported to a three-bubble oven by traction rollers for heating and three-stage blow-blowing (heating temperature 2:60℃) to fix the size and reduce the film's thermal shrinkage rate. Finally, the film bubble is sizing and cooled by natural air cooling, then cut into sheet films, and wound up to obtain the film product.
[0068] The film produced by the product of Example 1 according to the above-described preparation and process has a thickness of 25 μm. The physical properties and anti-fogging effect data are shown in Table 1.
[0069] Example 2
[0070] The micro-modified atmosphere packaging cap film for chilled meat packaging of the present invention is a multi-layer co-extruded film made of the following materials, with each layer composed of the following layer thickness ratio: heat-resistant layer (printing layer) 5%, support layer 7%, isolation layer 5%, adhesive layer 7%, protective layer 10%, barrier layer 5%, protective layer 10%, adhesive layer 7%, isolation layer 5%, secondary heat-sealing layer 19%, and heat-sealing anti-fog layer 20%. The heat-sealing anti-fog layer is made of EPE + anti-fog agent + opening slip agent, with EPE 72wt% + anti-fog agent 25wt% + opening slip agent 3wt%.
[0071] Specific models for each material:
[0072] The heat-resistant layer material is HOPA, specifically BASF's B36L.
[0073] The support layer is made of LDPE, specifically QAPCO's FD0474.
[0074] The insulating layer is made of LLDPE, specifically DOW's 2047G.
[0075] The adhesive layer is made of MAH-g-EVA with a grafting rate of 1.1-1.4%, and MPB's EV0350 is selected.
[0076] The protective layer is made of COPA, specifically BASF's C40LX.
[0077] The barrier layer material is EVOH, specifically NIPPON GOHSEI's SG986.
[0078] The secondary heat-sealing layer is made of LDPE, specifically Lyondellbasell 2420K.
[0079] The heat-sealing anti-fog layer is made of EPE + anti-fog agent + opening slip agent, wherein the EPE is DOW 5500G, the anti-fog agent is Sojitz 302HC, and the opening slip agent is A. Schulman FSU105E.
[0080] The blown film includes the following steps:
[0081] The first layer involves adding the heat-resistant layer material HOPA into the hopper of the extruder, melting it at a temperature of 220-250℃, and then feeding it into the die.
[0082] For the second layer, the raw material LDPE for the support layer is added to the hopper of the extruder, melted at a temperature of 190-220℃, and then enters the die.
[0083] In the third layer, the raw material LLDPE for the isolation layer is added to the hopper of the extruder, melted at a temperature of 190-220℃, and then enters the die.
[0084] For the fourth layer, the raw material MAH-g-EVA for the adhesive layer is added to the hopper of the extruder, melted at a temperature of 190-220℃, and then enters the die.
[0085] For the fifth layer, the raw material COPA for the protective layer is added to the hopper of the extruder, melted at a temperature of 220-250℃, and then enters the die.
[0086] For the sixth layer, the raw material EVOH for the barrier layer is added to the hopper of the extruder, melted at a temperature of 190-210℃, and then enters the die.
[0087] For the 7th layer, the raw material COPA for the protective layer is added to the hopper of the extruder, melted at a temperature of 220-250℃, and then enters the die.
[0088] For the 8th layer, the raw material MAH-g-EVA for the adhesive layer is added to the hopper of the extruder, melted at a temperature of 190-220℃, and then enters the die.
[0089] For the 9th layer, the raw material LLDPE for the isolation layer is added to the hopper of the extruder, melted at a temperature of 190-220℃, and then enters the die.
[0090] For the 10th layer, the raw material LDPE for the secondary heat seal layer is added to the hopper of the extruder, melted at a temperature of 190-220℃, and then enters the die.
[0091] For the 11th layer, the raw materials for the heat-sealing anti-fog layer, namely 72wt% EPE, 25wt% anti-fog agent, and 3wt% opening slip agent, are added to the hopper of the extruder and melted at a temperature of 180-220℃ before entering the die.
[0092] As mentioned above:
[0093] The third and ninth isolation layers have the same thickness;
[0094] The adhesive layer of layer 4 and layer 8 have the same thickness;
[0095] The fifth protective layer and the seventh protective layer are of the same thickness;
[0096] Then, the preform of the multi-layer co-extruded film is extruded through the die. The preform is fixed in size by a vacuum sizing ring below the die and cooled by a water ring (cooling temperature 10℃) to reduce the crystallinity of the preform. The preform is then passed through a secondary heating device (water bath or infrared heating) by traction rollers to fully preheat the preform (heating temperature 1:80℃) to facilitate secondary blow-blowing into film. The sizing cage on the outside of the film bubble above the secondary blow-blowing die is cooled and stabilized by an air ring to give the film bubble a certain structural strength and determine its fixed diameter and thickness. The film thickness distribution is then controlled by two devices: a rotary traction device and a herringbone clamp. The film is then transported to a three-bubble oven by traction rollers for heating and three-stage blow-blowing (heating temperature 2:60℃) to fix the size and reduce the film's thermal shrinkage rate. Finally, the film bubble is sizing and cooled by natural air cooling, then cut into sheet films, and wound up to obtain the film product.
[0097] Compared to Example 1, the adhesive using EVA as the matrix, during the second bubble blowing process, leverages its advantages of low melting point and high blow-up ratio to prevent interface separation between the adhesive layer and the PA layer at a high blow-up ratio, thus solving the problem of interlayer delamination that is common in existing products on the market.
[0098] The film produced by Example 2 according to the above-described distribution and process has a thickness of 25 μm. The physical properties and anti-fogging effect data are shown in Table 1.
[0099] Example 3
[0100] The micro-modified atmosphere packaging cap film for chilled meat packaging described in this invention is a multi-layer co-extruded film made of the following materials, with each layer composed of the following layer thickness ratios: heat-resistant layer (printing layer) 12%, support layer 10%, isolation layer 5%, adhesive layer 7%, protective layer 13%, barrier layer 5%, protective layer 13%, adhesive layer 7%, isolation layer 5%, secondary heat-sealing layer 10%, and heat-sealing anti-fog layer 13%.
[0101] The heat-sealed anti-fog layer is composed of 85wt% LDPE + 15wt% anti-fog agent;
[0102] The heat-sealing anti-fog layer is made of EPE + anti-fog agent + opening slip agent, wherein EPE is 77wt% + anti-fog agent is 20wt% + opening slip agent is 3wt%.
[0103] Specific models for each material:
[0104] The heat-resistant layer is made of LLDPE, specifically SABIC's 318BJ.
[0105] The support layer is made of LDPE, specifically QAPCO's FD0474.
[0106] The insulating layer is made of LLDPE, specifically DOW's 2047G.
[0107] The adhesive layer material is high grafting rate MAH-g-EVA, with a grafting rate of 1.1-1.4%, and MPB's EV0350 is selected.
[0108] The protective layer is made of COPA, specifically BASF's C40LX.
[0109] The barrier layer material is EVOH, specifically NIPPON GOHSEI's SG986.
[0110] The secondary heat-sealing anti-fog layer is made of LDPE + anti-fog agent, wherein the LDPE is Lyondellbasell 2420K and the anti-fog agent is Sojitz 302HC.
[0111] The heat-sealed anti-fog layer uses DOW's 5500G EPE, Sojitz's 302HC anti-fog agent, and A. Schulman's FSU105E opening slip agent.
[0112] The blown film includes the following steps:
[0113] The first layer involves adding the LLDPE material for the heat-resistant layer into the hopper of the extruder, melting it at a temperature of 190-220℃, and then feeding it into the die.
[0114] For the second layer, the raw material LDPE for the support layer is added to the hopper of the extruder, melted at a temperature of 190-220℃, and then enters the die.
[0115] In the third layer, the raw material LLDPE for the isolation layer is added to the hopper of the extruder, melted at a temperature of 190-220℃, and then enters the die.
[0116] For the fourth layer, the raw material MAH-g-EVA for the adhesive layer is added to the hopper of the extruder, melted at a temperature of 190-220℃, and then enters the die.
[0117] For the fifth layer, the raw material COPA for the protective layer is added to the hopper of the extruder, melted at a temperature of 220-250℃, and then enters the die.
[0118] For the sixth layer, the raw material EVOH for the barrier layer is added to the hopper of the extruder, melted at a temperature of 190-210℃, and then enters the die.
[0119] For the 7th layer, the raw material COPA for the protective layer is added to the hopper of the extruder, melted at a temperature of 220-250℃, and then enters the die.
[0120] For the 8th layer, the raw material MAH-g-EVA for the adhesive layer is added to the hopper of the extruder, melted at a temperature of 190-220℃, and then enters the die.
[0121] For the 9th layer, the raw material LLDPE for the isolation layer is added to the hopper of the extruder, melted at a temperature of 190-220℃, and then enters the die.
[0122] For the 10th layer, 85wt% LDPE and 15wt% antifogging agent, the raw materials for the secondary heat-sealing antifogging layer, are added to the hopper of the extruder and melted at a temperature of 190-220℃ before entering the die.
[0123] For the 11th layer, the raw materials for the heat-sealing anti-fog layer, EPE 77wt%, anti-fog agent 20wt%, and opening slip agent 3wt%, are added to the hopper of the extruder and melted at a temperature of 180-220℃ before entering the die.
[0124] As mentioned above:
[0125] The third and ninth isolation layers have the same thickness;
[0126] The adhesive layer of layer 4 and layer 8 have the same thickness;
[0127] The fifth protective layer and the seventh protective layer are of the same thickness;
[0128] Then, the preform of the multi-layer co-extruded film is extruded through the die. The preform is fixed in size by a vacuum sizing ring below the die and cooled by a water ring (cooling temperature 10℃) to reduce the crystallinity of the preform. The preform is then passed through a secondary heating device (water bath or infrared heating) by traction rollers to fully preheat the preform (heating temperature 1:80℃) to facilitate secondary blow-blowing into film. The sizing cage on the outside of the film bubble above the secondary blow-blowing die is cooled and stabilized by an air ring to give the film bubble a certain structural strength and determine its fixed diameter and thickness. The film thickness distribution is then controlled by two devices: a rotary traction device and a herringbone clamp. The film is then transported to a three-bubble oven by traction rollers for heating and three-stage blow-blowing (heating temperature 2:60℃) to fix the size and reduce the film's thermal shrinkage rate. Finally, the film bubble is sizing and cooled by natural air cooling, then cut into sheet films, and wound up to obtain the film product.
[0129] Compared to Example 2, by studying the layer structure distribution and the combination of inner and outer layer materials, and by changing the surface material, the impact of differences in crystallization temperature, water absorption rate, and post-crystallization on the flatness of the outer PA and inner PE layers was reduced. This solved the problem of easy curling in asymmetric structure products on the market.
[0130] The film produced by Example 3 according to the above-described preparation and process has a thickness of 25 μm. The physical properties and anti-fogging effect data are shown in Table 1.
[0131] Example 4
[0132] The micro-modified atmosphere packaging cap film for chilled meat packaging described in this invention is a multi-layer co-extruded film made of the following materials, with each layer composed of the following layer thickness ratios: heat-resistant layer (printing layer) 14%, support layer 10%, isolation layer 5%, adhesive layer 5%, protective layer 13%, barrier layer 5%, protective layer 13%, adhesive layer 5%, isolation layer 5%, secondary heat-sealing layer 10%, and heat-sealing anti-freezing layer 15%.
[0133] The protective layer is made of COPA + amorphous PA, with COPA 80wt% + amorphous PA 20wt%.
[0134] The secondary heat-sealed anti-fog layer is made of LDPE + anti-fog agent, with LDPE 85wt% + anti-fog agent 15wt%.
[0135] The heat-sealing anti-fog layer is made of EPE + anti-fog agent + opening agent, with EPE 75wt% + anti-fog agent 20wt% + opening agent 5wt%.
[0136] Specific models for each material:
[0137] The heat-resistant layer is made of LLDPE, specifically SABIC's 318BJ.
[0138] The support layer is made of LDPE, specifically QAPCO's FD0474.
[0139] The insulating layer is made of LLDPE, specifically DOW's 2047G.
[0140] The adhesive layer material is high grafting rate MAH-g-EVA, specifically MPB's EV0350.
[0141] The protective layer material is COPA + amorphous PA (80wt% COPA + 20wt% amorphous PA), wherein the COPA is BASF C40LX and the amorphous PA is EMS G21.
[0142] The barrier layer material is EVOH, specifically NIPPON GOHSEI's SG986.
[0143] The secondary heat-sealed anti-fogging layer is made of LDPE + anti-fogging agent (LDPE 85wt% + anti-fogging agent 15wt%), wherein the LDPE is Lyondellbasell 2420K and the anti-fogging agent is Sojitz 302HC.
[0144] The heat-sealing anti-fog layer is made of EPE + anti-fog agent + opening agent; wherein the EPE is DOW 5500G, the anti-fog agent is Sojitz 302HC, and the opening agent is Ampacet 100001-K.
[0145] The amorphous PA mentioned above belongs to amorphous polymers. Its molecular chains are irregular and arbitrarily entangled. Reducing the crystallinity of COPA and increasing its amorphous region is beneficial for two-bubble inflation.
[0146] The blown film includes the following steps:
[0147] The first layer involves adding the LLDPE material for the heat-resistant layer into the hopper of the extruder, melting it at a temperature of 190-220℃, and then feeding it into the die.
[0148] For the second layer, the raw material LDPE for the support layer is added to the hopper of the extruder, melted at a temperature of 190-220℃, and then enters the die.
[0149] In the third layer, the raw material LLDPE for the isolation layer is added to the hopper of the extruder, melted at a temperature of 190-220℃, and then enters the die.
[0150] For the fourth layer, the raw material MAH-g-EVA for the adhesive layer is added to the hopper of the extruder, melted at a temperature of 190-220℃, and then enters the die.
[0151] For the fifth layer, the raw materials for the protective layer, 80wt% COPA and 20wt% amorphous PA, are added to the hopper of the extruder and melted at a temperature of 220-250℃ before entering the die.
[0152] For the sixth layer, the raw material EVOH for the barrier layer is added to the hopper of the extruder, melted at a temperature of 190-210℃, and then enters the die.
[0153] For the 7th layer, the raw materials for the protective layer, consisting of 80wt% COPA and 20wt% amorphous PA, are added to the hopper of the extruder and melted at a temperature of 220-250℃ before entering the die.
[0154] For the 8th layer, the raw material MAH-g-EVA for the adhesive layer is added to the hopper of the extruder, melted at a temperature of 190-220℃, and then enters the die.
[0155] For the 9th layer, the raw material LLDPE for the isolation layer is added to the hopper of the extruder, melted at a temperature of 190-220℃, and then enters the die.
[0156] For the 10th layer, 85wt% LDPE and 15wt% antifogging agent, the raw materials for the secondary heat-sealing antifogging layer, are added to the hopper of the extruder and melted at a temperature of 190-220℃ before entering the die.
[0157] For the 11th layer, the raw materials for the heat-sealing anti-fog layer, EPE 75wt%, anti-fog agent 20wt%, and opening agent 5wt%, are added to the hopper of the extruder and melted at a temperature of 180-220℃ before entering the die.
[0158] As mentioned above:
[0159] The third and ninth isolation layers have the same thickness;
[0160] The adhesive layer of layer 4 and layer 8 have the same thickness;
[0161] The fifth protective layer and the seventh protective layer are of the same thickness;
[0162] Then, the preform of the multi-layer co-extruded film is extruded through the die. The preform is fixed in size by a vacuum sizing ring below the die and cooled by a water ring (cooling temperature 10℃) to reduce the crystallinity of the preform. The preform is then passed through a secondary heating device (water bath or infrared heating) by traction rollers to fully preheat the preform (heating temperature 1:90℃) to facilitate secondary blow-blowing into film. The sizing cage on the outside of the film bubble above the secondary blow-blowing die is cooled and stabilized by an air ring to give the film bubble a certain structural strength and determine its fixed diameter and thickness. The film thickness distribution is then controlled by two devices: a rotary traction device and a herringbone clamp. The film is then transported to a three-bubble oven by traction rollers for heating and three-stage blow-blowing (heating temperature 2:66℃) to fix the size and reduce the film's thermal shrinkage rate. Finally, the film bubble is sizing and cooled by natural air cooling, then cut into sheet films, and finally wound up to obtain the film product.
[0163] Compared to Example 3, by adding amorphous PA to the protective layer, the aggregated structure of the PA material is controlled, reducing intermolecular forces and facilitating double-bubble inflation, which can reduce the thermal shrinkage rate of the final product. Removing the slip agent and increasing the amount of opening agent in the heat-sealed anti-fog layer reduces the impact of slip agent migration on the anti-fog effect and also lowers the coefficient of friction through the surface micro-protrusion effect.
[0164] The film produced by Example 4 according to the above-described formula and process has a thickness of 25μm. Its physical properties and anti-fogging effect are superior to those of other examples. Specific data are shown in Table 1. This solves the problem of the shortcomings of multi-layer co-extruded multifunctional micro-shrink modified atmosphere films on the market.
[0165] The physical performance test data for Examples 1-4 are shown in the table below:
[0166] Table 1: Comparison of Physical Properties of Examples 1-4
[0167]
[0168]
[0169] Data comparison shows that all physical indicators of Example 4 meet the target standards, achieving a combination of high transparency, high smoothness, and excellent anti-fog effect, solving the problem of customers having to choose between appearance and anti-fog effect; the layers are difficult to delaminate, improving heat sealing strength and peel force, solving the problem of delamination when opened by end consumers; the heat shrinkage rate is reduced, solving the problem of easy box deformation and poor product appearance; the film has high flatness, solving the problem of difficult printing and customer machine operation in the later stage, and can reduce the film width and save costs.
[0170] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.
Claims
1. A micro-modified atmosphere packaging cap film for chilled meat packaging, characterized in that, It is a multilayer co-extruded film made of the following materials, with each layer composed of the following thickness ratio: heat-resistant layer 14%, support layer 10%, isolation layer 5%, adhesive layer 5%, protective layer 13%, barrier layer 5%, protective layer 13%, adhesive layer 5%, isolation layer 5%, secondary heat-sealing anti-fog layer 10%, and heat-sealing anti-fog layer 15%. The heat-resistant layer material is LLDPE; The support layer material is LDPE; All isolation layers are made of LLDPE. Each adhesive layer material is MAH-g-EVA with a grafting rate of 1.1-1.4%; The barrier layer material is EVOH; The materials of each protective layer are COPA and amorphous PA, with COPA accounting for 75-85 wt% and amorphous PA accounting for 15-25 wt%. The secondary heat-sealed anti-fogging layer is made of LDPE and an anti-fogging agent, with LDPE comprising 80-90 wt% and the anti-fogging agent comprising 10-20 wt%. The heat-sealing anti-fog layer is made of EPE, an anti-fog agent, and an opening agent, with EPE comprising 70-80 wt%, the anti-fog agent comprising 15-25 wt%, and the opening agent comprising 3-8 wt%.
2. The micro-modified atmosphere packaging cap film according to claim 1, characterized in that, The COPA in each protective layer is 80wt%, and the amorphous PA is 20wt%.
3. The micro-modified atmosphere packaging cap film according to claim 1, characterized in that, The secondary heat-sealed anti-fog layer contains 85 wt% LDPE and 15 wt% anti-fog agent.
4. The micro-modified atmosphere packaging cap film according to claim 1, characterized in that, The heat-sealed anti-fog layer contains 75 wt% EPE, 20 wt% anti-fog agent, and 5 wt% opening agent.
5. The method for preparing the micro-modified atmosphere packaging cap film for chilled meat packaging as described in claim 1, characterized in that, Includes the following steps: The first layer involves adding the LLDPE material for the heat-resistant layer into the hopper of the extruder, melting it at a temperature of 190-220℃, and then feeding it into the die. For the second layer, the raw material LDPE for the support layer is added to the hopper of the extruder, melted at a temperature of 190-220℃, and then enters the die. In the third layer, the raw material LLDPE for the isolation layer is added to the hopper of the extruder, melted at a temperature of 190-220℃, and then enters the die. For the fourth layer, the raw material MAH-g-EVA for the adhesive layer is added to the hopper of the extruder, melted at a temperature of 190-220℃, and then enters the die. For the fifth layer, the raw materials COPA and amorphous PA for the protective layer are added to the hopper of the extruder, melted at a temperature of 220-250℃, and then fed into the die. For the sixth layer, the raw material EVOH for the barrier layer is added to the hopper of the extruder, melted at a temperature of 190-210℃, and then enters the die. For the 7th layer, the raw materials COPA and amorphous PA for the protective layer are added to the hopper of the extruder, melted at a temperature of 220-250℃, and then enter the die. For the 8th layer, the raw material MAH-g-EVA for the adhesive layer is added to the hopper of the extruder, melted at a temperature of 190-220℃, and then enters the die. For the 9th layer, the raw material LLDPE for the isolation layer is added to the hopper of the extruder, melted at a temperature of 190-220℃, and then enters the die. For the 10th layer, the raw materials LDPE and anti-fogging agent for the secondary heat-sealing anti-fogging layer are added to the hopper of the extruder, melted at a temperature of 190-220℃, and then enter the die. For the 11th layer, the raw materials EPE, anti-fogging agent and opening agent of the heat-sealing anti-fogging layer are added to the hopper of the extruder, melted at a temperature of 180-220℃, and then enter the die.