Preparation method and application of high-temperature-resistant cooking film

Abstract

This invention relates to the field of plastic film technology, specifically to a method for preparing and applying a high-temperature resistant retort film. The high-temperature resistant retort film comprises, from left to right, an outer layer, a core layer, and an inner layer. The raw materials for preparing the outer layer include: 40-50 parts of metallocene polyethylene, 40-50 parts of PA, 10-20 parts of compatibilizer, 1-2 parts of chain extender, and 5-8 parts of adhesive. The raw materials for preparing the core layer include: 40-50 parts of LDPE, 40-50 parts of HDPE, 20-30 parts of EVA, and 5-8 parts of adhesive. The raw materials for preparing the inner layer include: 40-50 parts of metallocene polyethylene, 40-50 parts of PA, 10-20 parts of compatibilizer, 1-2 parts of chain extender, and 5-8 parts of adhesive.

Description

Technical Field

[0001] This invention relates to the field of plastic film technology, specifically to a method for preparing and applying a high-temperature resistant retort film. Background Technology

[0002] Plastic films used in the food packaging industry, such as those made of polyvinyl chloride, polyethylene, polypropylene, polystyrene, and other resins, can produce odors after being cooked at high temperatures due to the migration of small molecules in their raw materials, such as antioxidants, heat stabilizers, low-molecular-weight polymers, and slip agents. These small molecules can penetrate into the food during cooking and may pose a health hazard when consumed.

[0003] Currently, high-temperature retort PE films on the market cannot balance deformation and toughness, have poor high-temperature resistance, are not resistant to retort, cannot meet packaging requirements for low-temperature refrigeration and vacuuming, and are prone to deformation and breakage after retort. Summary of the Invention

[0004] To address the above technical problems, this invention provides a method for preparing and applying a high-temperature resistant retort film. This high-temperature resistant retort film exhibits excellent high-temperature resistance, superior toughness, puncture resistance, and resistance to high-temperature retorting, preventing deformation and bag breakage during high-temperature retorting.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a high-temperature resistant retort membrane, comprising: an outer layer, a core layer, and an inner layer from left to right; wherein, the raw materials for preparing the outer layer include: 40-50 parts of metallocene polyethylene, 40-50 parts of PA, 10-20 parts of compatibilizer, 1-2 parts of chain extender, and 5-8 parts of adhesive; the raw materials for preparing the core layer include: 40-50 parts of LDPE, 40-50 parts of HDPE, 20-30 parts of EVA, and 5-8 parts of adhesive; the raw materials for preparing the inner layer include: 40-50 parts of metallocene polyethylene, 40-50 parts of PA, 10-20 parts of compatibilizer, 1-2 parts of chain extender, and 5-8 parts of adhesive.

[0007] This invention utilizes high-density metallocene polyethylene (HDPE) and polyamide (PA) blended with compatibilizers and chain extenders to prepare a modified HDPE / PA / PA blend film. This HDPE / PA / PA blend film, serving as both the outer and inner layers, possesses high strength, high toughness, puncture resistance, abrasion resistance, and high-temperature resistance, giving the retort membrane excellent high-temperature resistance, toughness, puncture resistance, and high-temperature retortability. The core layer is composed of a blend of high-density polyethylene (HDPE), low-density polyethylene (LDPE), and ethylene-vinyl acetate copolymer (EVA), imparting high-temperature resistance, high gas barrier properties, and moisture barrier properties to the retort membrane. This prevents the permeation of small molecules such as oxygen and water molecules, thus preserving freshness, improving quality, and extending shelf life. Furthermore, the use of a high-temperature resistant adhesive prevents the release of toxic substances such as small molecules during high-temperature retort cooking. In summary, this high-temperature retort film possesses advantages such as high density, high gas and moisture barrier properties, excellent toughness, puncture resistance, and resistance to high-temperature retort. As a food packaging material, it not only extends the shelf life of food by blocking gas and moisture but can also be used for low-temperature refrigeration and preservation, meeting the packaging requirements for vacuum refrigeration. Furthermore, the film bag becomes flatter and less prone to breakage after heating and retort, solving the problems of existing high-temperature retort PE films, such as the inability to balance deformation and toughness, poor high-temperature resistance, inability to withstand retort, inability to meet packaging requirements for low-temperature refrigeration and vacuum refrigeration, and the ease with which the bag deforms and breaks after retort.

[0008] Preferably, the PA includes PA46, PA12, or PA11;

[0009] The LDPE includes DPEQ200 or LDPEQ281;

[0010] The HDPE includes HDPE7047, HDPE9455, or HDPE5500S;

[0011] The EVA includes EVA310, KA-31, or EVA150.

[0012] Preferably, the adhesive is a polyurethane adhesive, including PU5507, PU8612, or PU5215. All of the above-mentioned types of polyurethane adhesives have high-temperature resistance and will not decompose and release toxic substances at 200°C; they can also effectively bond various components and film layers, exhibiting strong adhesion, firm bonding, and no delamination.

[0013] Preferably, the metallocene polyethylene includes M8470 or 1018MA. All of the above-mentioned metallocene polyethylenes are food-grade and possess characteristics such as high density, high strength, high rigidity, low coefficient of friction, as well as good processing performance and wear resistance.

[0014] Preferably, the compatibilizer is maleic anhydride-grafted polyethylene with a grafting rate of 0.6-1%; the chain extender includes neopentyl glycol or propylene glycol.

[0015] The aforementioned compatibilizers can improve the adhesion and compatibility between metallocene polyethylene and polyamide, promote diffusion and penetration between the two phases, and ensure uniform compatibility. The aforementioned chain extenders can increase the molecular weight of metallocene polyethylene / polyamide blends, improve their processing properties, and enhance their strength and toughness.

[0016] Preferably, the raw materials for preparing the outer layer, core layer and inner layer further include additives; the additives are 1-2 parts of slip agent and 1-2 parts of brightening agent, wherein the slip agent includes ORV-MB or silica; and the brightening agent includes NA-18, NA-11 or NA-21.

[0017] The aforementioned types of slip agents can reduce friction between components, resulting in a more uniform distribution of each component. These types of clarifying agents, by providing nuclei, promote the crystallization of polymer resins, accelerate the crystallization rate, and refine the grain structure, thereby improving the rigidity, heat distortion temperature, dimensional stability, transparency, surface gloss, impact resistance, and stress relaxation resistance of the retort film.

[0018] Preferably, the total thickness of the high-temperature resistant retort membrane is 18-26 μm, the outer layer is 5-8 μm thick, the core layer is 8-10 μm thick, and the inner layer is 5-8 μm thick. Retort membranes of these thicknesses possess superior properties such as high density, high gas and moisture barrier properties, high temperature resistance, excellent toughness, puncture resistance, and resistance to high-temperature retort processes.

[0019] Secondly, the present invention also provides a method for preparing the above-mentioned high-temperature resistant retort film, comprising the following operations: weighing the raw materials for the preparation of the outer layer, core layer and inner layer and adding them into the feed port of a three-layer co-extrusion blow molding machine, and feeding them to the die head through a screen changing mechanism to form the core layer and inner and outer layers of the film respectively; then blowing in cooling air by a fan to inflate the film tube into a film bubble; after the film bubble is cooled by an external cooling air ring and an internal cooling system, it is stretched and corona treated, and then wound and cut to obtain the high-temperature resistant retort film.

[0020] Preferably, the temperature of the blow molding machine is 190-220℃; the molding temperature is 195-210℃. The above temperatures can fully melt the components into a molten state, and the above molding temperatures can uniformly extrude the high-temperature resistant retort film.

[0021] Preferably, the cooling temperature is 25-30℃, and the high-temperature resistant cooking film is obtained by cooling and molding.

[0022] Thirdly, the present invention also provides the application of the above-mentioned high-temperature resistant retort film or the high-temperature resistant retort film prepared by the above method in food packaging. Attached Figure Description

[0023] Figure 1This is a schematic diagram of the structure of the high-temperature resistant retort membrane in Embodiment 1 of the present invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0025] Example 1

[0026] This invention provides a high-temperature resistant retort membrane, which consists of an outer layer, a core layer, and an inner layer from left to right. The outer layer is prepared from the following raw materials: 40 parts metallocene polyethylene, 40 parts PA, 10 parts compatibilizer, 1 part chain extender, 5 parts adhesive, 1 part slip agent, and 1 part brightening agent. The core layer is prepared from the following raw materials: 40 parts LDPE, 50 parts HDPE, 20 parts EVA, 5 parts adhesive, 1 part slip agent, and 1 part brightening agent. The inner layer is prepared from the following raw materials: 40 parts metallocene polyethylene, 40 parts PA, 10 parts compatibilizer, 1 part chain extender, 5 parts adhesive, 1 part slip agent, and 1 part brightening agent. Among them, metallocene polyethylene is M8470; PA is PA46; compatibilizer is maleic anhydride-grafted polyethylene with a grafting rate of 1%; chain extender includes neopentyl glycol; LDPE is DPEQ200; HDPE is HDPE7047; EVA is EVA310; adhesive is PU5507; slip agent is ORV-MB; and brightening agent is NA-18.

[0027] The preparation method of the above-mentioned high-temperature resistant retort membrane includes the following steps:

[0028] The raw materials for the outer, core, and inner layers were weighed and added to the feed inlet of a three-layer co-extrusion blow molding machine. The melt was formed at 190°C and then fed to the die head via a screen changing mechanism. The forming temperature was 195°C, forming the core and inner / outer layers of the film. Cooling air was then blown in by a fan at 25°C, inflating the film tube into a bubble. After cooling by an external cooling air ring and an internal cooling system, the bubble was stretched, corona-treated, and then wound and slit to obtain a high-temperature resistant retort film. The total thickness of the obtained high-temperature resistant retort film was 18 μm, with the outer layer at 5 μm, the core layer at 8 μm, and the inner layer at 5 μm.

[0029] Example 2

[0030] This invention provides a high-temperature resistant retort membrane, which consists of an outer layer, a core layer, and an inner layer from left to right. The outer layer is prepared from the following raw materials: 48 parts metallocene polyethylene, 50 parts PA, 15 parts compatibilizer, 1 part chain extender, 7 parts adhesive, 2 parts slip agent, and 2 parts brightening agent. The core layer is prepared from the following raw materials: 45 parts LDPE, 45 parts HDPE, 25 parts EVA, 7 parts adhesive, 2 parts slip agent, and 2 parts brightening agent. The inner layer is prepared from the following raw materials: 48 parts metallocene polyethylene, 50 parts PA, 15 parts compatibilizer, 1 part chain extender, 7 parts adhesive, 2 parts slip agent, and 2 parts brightening agent. Among them, metallocene polyethylene is M8470; PA is PA12; compatibilizer is maleic anhydride-grafted polyethylene with a grafting rate of 0.8%; chain extender includes propylene glycol; LDPE is LDPEQ281; HDPE is HDPE9455; EVA is KA-31; adhesive is PU8612; slip agent is silica; and clarity enhancer is NA-11.

[0031] The preparation method of the above-mentioned high-temperature resistant retort membrane includes the following steps:

[0032] The raw materials for the outer, core, and inner layers were weighed and added to the feed inlet of a three-layer co-extrusion blow molding machine. The melt was formed at 210°C and then fed to the die head via a screen changing mechanism. The forming temperature was 205°C, forming the core and inner / outer layers of the film. Cooling air was then blown in by a fan at 28°C, inflating the film tube into a bubble. After cooling by an external cooling air ring and an internal cooling system, the bubble was stretched, corona-treated, and then wound and slit to obtain a high-temperature resistant retort film. The total thickness of the obtained high-temperature resistant retort film was 21 μm, the outer layer thickness was 6 μm, the core layer thickness was 9 μm, and the inner layer thickness was 6 μm.

[0033] Example 3

[0034] This invention provides a high-temperature resistant retort membrane, which comprises an outer layer, a core layer, and an inner layer from left to right. The outer layer is prepared from the following raw materials: 50 parts metallocene polyethylene, 50 parts PA, 20 parts compatibilizer, 2 parts chain extender, 8 parts adhesive, 2 parts slip agent, and 2 parts brightening agent. The core layer is prepared from the following raw materials: 50 parts LDPE, 50 parts HDPE, 30 parts EVA, 8 parts adhesive, 2 parts slip agent, and 2 parts brightening agent. The inner layer is prepared from the following raw materials: 50 parts metallocene polyethylene, 50 parts PA, 20 parts compatibilizer, 2 parts chain extender, 8 parts adhesive, 2 parts slip agent, and 2 parts brightening agent. Among them, metallocene polyethylene is 1018MA; PA is PA11; compatibilizer is maleic anhydride-grafted polyethylene with a grafting rate of 0.6%; chain extender includes neopentyl glycol; LDPE is LDPEQ281; HDPE is HDPE5500S; EVA is EVA15; adhesive is PU5215; slip agent is ORV-MB; and clearing agent is NA-21.

[0035] The preparation method of the above-mentioned high-temperature resistant retort membrane includes the following steps:

[0036] The raw materials for the outer, core, and inner layers were weighed and added to the feed inlet of a three-layer co-extrusion blow molding machine. The melt was formed at 220°C and then fed to the die head via a screen changing mechanism. The forming temperature was 210°C, forming the core and inner / outer layers of the film. Cooling air was then blown in by a fan at 30°C, inflating the film tube into a bubble. After cooling by an external cooling air ring and an internal cooling system, the bubble was stretched, corona-treated, and then wound and slit to obtain a high-temperature resistant retort film. The total thickness of the obtained high-temperature resistant retort film was 26 μm, with the outer layer at 8 μm, the core layer at 10 μm, and the inner layer at 8 μm.

[0037] Comparative Example 1

[0038] Compared with Example 1, the raw materials for the preparation of the outer and inner layers do not contain metallocene, the raw materials for the preparation of the core layer do not contain LDPE and EVA, and the remaining components and preparation methods are the same as in Example 1.

[0039] Verification Example 1

[0040] The high-temperature resistant retort films obtained in Examples 1-3 and Comparative Example 1 were subjected to performance tests, and the results are shown in Table 1.

[0041] Table 1 shows the performance tests of the high-temperature resistant retort films obtained in Examples 1-3 and Comparative Example 1.

[0042]

[0043] As shown in Table 1, compared with Comparative Example 1, the high-temperature retort films of Examples 1-3 have high temperature resistance, high gas barrier, high moisture barrier, and high puncture strength, indicating excellent toughness, low haze, high transparency, and low hot water recovery rate at 100°C. This indicates that the retort film is resistant to high-temperature cooking and can be used as a food packaging material. It can not only block gas and moisture and extend the shelf life of food, but also be refrigerated at low temperatures, meeting the packaging requirements for vacuum refrigeration. Moreover, the film bag is flatter and less prone to breakage after heating and cooking.

[0044] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-temperature resistant retort membrane, characterized in that, include: The high-temperature resistant retort membrane consists of an outer layer, a core layer, and an inner layer from left to right; among them... The raw materials for preparing the outer layer include: 40-50 parts of metallocene polyethylene, 40-50 parts of PA, 10-20 parts of compatibilizer, 1-2 parts of chain extender and 5-8 parts of adhesive; The raw materials for preparing the core layer include: 40-50 parts LDPE, 40-50 parts HDPE, 20-30 parts EVA, and 5-8 parts adhesive; the EVA includes EVA310, KA-31, or EVA150. The raw materials for preparing the inner layer include: 40-50 parts of metallocene polyethylene, 40-50 parts of PA, 10-20 parts of compatibilizer, 1-2 parts of chain extender and 5-8 parts of adhesive. The adhesive is a polyurethane adhesive; the polyurethane adhesive includes PU5507, PU8612 or PU5215.

2. The high-temperature resistant retort membrane according to claim 1, characterized in that, The PA includes PA46, PA12 or PA11; The LDPE includes DPEQ200 or LDPEQ281; The HDPE includes HDPE7047, HDPE9455, or HDPE5500S.

3. The high-temperature resistant retort membrane according to claim 1, characterized in that, The metallocene polyethylene includes M8470 or 1018MA; and / or The compatibilizer is maleic anhydride-grafted polyethylene with a grafting rate of 0.6% to 1%.

4. The high-temperature resistant retort membrane according to claim 1, characterized in that, The raw materials for preparing the outer layer, core layer, and inner layer also include additives; the additives are 1-2 parts of slip agent and 1-2 parts of permeability enhancer.

5. The high-temperature resistant retort membrane according to claim 4, characterized in that, The slip agent includes ORV-MB or silica; the brightening agent includes NA-18, NA-11 or NA-21.

6. The high-temperature resistant retort membrane according to claim 1, characterized in that, The total thickness of the high-temperature resistant cooking membrane is 18-26 μm, the outer layer is 5-8 μm thick, the core layer is 8-10 μm thick, and the inner layer is 5-8 μm thick.

7. The method for preparing the high-temperature resistant retort membrane according to any one of claims 1-6, characterized in that, The process includes the following steps: weighing the raw materials for the preparation of the outer layer, core layer, and inner layer and adding them to the feed inlet of the three-layer co-extrusion blow molding machine. After being fed to the die head by the screen changing mechanism, the outer layer, core layer, and inner layer of the film are formed respectively. Cooling air is then blown in by a fan to inflate the film tube into a film bubble. After the film bubble is cooled by the external cooling air ring and the internal cooling system of the film bubble, it is stretched and corona treated, then wound up and cut to obtain a high-temperature resistant retort film.

8. The method for preparing the high-temperature resistant retort membrane according to claim 7, characterized in that, The extrusion temperature of the blow molding machine is 190-220℃; the molding temperature is 195-210℃; and the cooling temperature is 25-30℃.

9. The application of the high-temperature retort film according to any one of claims 1-6 or the high-temperature retort film obtained by the preparation method according to any one of claims 7-8 in food packaging.