阅读说明：本技术 一种耐溶剂性强低析出可高温蒸煮包装膜 (High-temperature-digestion packaging film with high solvent resistance and low precipitation ) 是由 黄湘晖 李全布 齐家鹏 黄文娟 陈健 赵刚 于 2020-04-22 设计创作，主要内容包括：本发明公开一种耐溶剂性强低析出可高温蒸煮包装膜,包括由内至外依次设置的外层、第一连接层、阻隔层、第二连接层和内层,外层为PET、BOPP,外层厚度为12～25μm；第一连接层为改性高密度聚乙烯或高密度茂金属聚乙烯与乙烯-甲基丙烯酸-丙烯酸酯共聚物的混合物,高密度茂金属聚乙烯与乙烯-甲基丙烯酸-丙烯酸酯共聚物的质量比＝3～5：1；第一连接层厚度为10～30μm；阻隔层为铝箔、EVOH、NY、镀硅PET膜、镀硅OPP膜、镀氧化铝PET膜和镀氧化铝OPP膜中的一种,阻隔层厚度为7～15μm；第二连接层为改性高密度聚乙烯或高密度茂金属聚乙烯与乙烯-甲基丙烯酸-丙烯酸酯共聚物的混合物；内层为环状烯烃共聚物、高密度聚乙烯、共聚PP、均聚PP中的一种或几种混合物；内层不添加助剂。(The invention discloses a high-temperature-cooking packaging film with strong solvent resistance and low precipitation, which comprises an outer layer, a first connecting layer, a blocking layer, a second connecting layer and an inner layer which are sequentially arranged from inside to outside, wherein the outer layer is made of PET (polyethylene terephthalate) and BOPP (biaxially-oriented polypropylene), and the thickness of the outer layer is 12-25 micrometers; the first connecting layer is a mixture of modified high-density polyethylene or high-density metallocene polyethylene and an ethylene-methacrylic acid-acrylate copolymer, and the mass ratio of the high-density metallocene polyethylene to the ethylene-methacrylic acid-acrylate copolymer is 3-5: 1; the thickness of the first connecting layer is 10-30 mu m; the barrier layer is one of aluminum foil, EVOH, NY, a silicon-plated PET film, a silicon-plated OPP film, an aluminum oxide-plated PET film and an aluminum oxide-plated OPP film, and the thickness of the barrier layer is 7-15 mu m; the second connecting layer is a mixture of modified high-density polyethylene or high-density metallocene polyethylene and ethylene-methacrylic acid-acrylate copolymer; the inner layer is one or a mixture of more of cyclic olefin copolymer, high-density polyethylene, copolymerized PP and homopolymerized PP; the inner layer is not added with an auxiliary agent.)

1. A high-temperature-cooking packaging film with strong solvent resistance and low precipitation comprises an outer layer, a first connecting layer, a barrier layer, a second connecting layer and an inner layer which are sequentially arranged from inside to outside, and is characterized in that the total thickness of the packaging film is 60-120 mu m,

the outer layer is a polyethylene terephthalate film or a biaxially oriented polypropylene film, and the thickness of the outer layer is 12-25 mu m;

the first connecting layer is a mixture of modified high-density polyethylene or high-density metallocene polyethylene and an ethylene-methacrylic acid-acrylate copolymer; the modified high-density polyethylene has a Vicat softening point of 125 ℃ or higher; the mass ratio of the high-density metallocene polyethylene to the ethylene-methacrylic acid-acrylate copolymer is 3-5: 1; the thickness of the first connecting layer is 10-30 μm;

the barrier layer is one of aluminum foil, ethylene-vinyl alcohol copolymer, polyamide, silicon-plated PET film, silicon-plated OPP film, aluminum oxide-plated PET film and aluminum oxide-plated OPP film, and the thickness of the barrier layer is 7-15 micrometers;

the second connecting layer is a mixture of modified high-density polyethylene or high-density metallocene polyethylene and an ethylene-methacrylic acid-acrylate copolymer; the mass ratio of the high-density metallocene polyethylene to the ethylene-methacrylic acid-acrylate copolymer is 3-5: 1; the thickness of the second connecting layer is 8-20 mu m;

the inner layer is one or a mixture of more of cyclic olefin copolymer, high-density polyethylene, co-polypropylene and homo-polypropylene; wherein the inner layer is not added with an auxiliary agent, and the thickness of the inner layer is 5-50 μm.

2. The autoclavable packaging film of claim 1, further comprising a second tie layer comprising a modified HDPE modified as follows: adding 8-10% of freeze-dried modified cellulose whiskers and 5% of maleated polyethylene in percentage by mass of the second connecting layer; the average length of the modified cellulose whisker is 300-500 nm, the average diameter is 20-30 nm, and the modified cellulose is blended and modified with N-aminoethyl-3-aminopropyl methyl dimethoxysilane and a molecular sieve and then added into high-density polyethylene.

3. The autoclavable packaging film of claim 2, wherein said inner layer is a three layer blown composite film or a three layer cast film, said inner layer comprising a cyclic olefin copolymer layer, a polypropylene copolymer layer, and a high density polyethylene layer.

4. The high-temperature-retort packaging film with strong solvent resistance and low precipitation as claimed in claim 3, wherein a thermally stable filler is added into the first connecting layer, and the adding amount of the thermally stable filler is 0.5-2% by mass of the first connecting layer; the thermal stable filler is one or a mixture of more of aluminum nitride, boron nitride, silicon nitride or carbon nano tubes.

5. The autoclavable packaging film of claim 4, further comprising an antioxidant 2, 6-di-tert-butyl in said first tie layer, wherein said antioxidant is 2- (2-hydroxy-3, 5-di-tert-butylphenyl) -5-chlorobenzotriazole or 2-hydroxy-4-n-octoxybenzophenone.

6. The autoclavable packaging film of claim 5, wherein the outer layer, the first tie layer and the barrier layer are extrusion compounded to form a base film, and the base film is extrusion compounded with the second tie layer and the inner layer.

7. The autoclavable packaging film of claim 5, wherein said outer layer, said first tie layer, said barrier layer, said second tie layer, and said inner layer are continuously extrusion laminated in series on both sides.

8. The high-temperature retort packaging film with high solvent resistance and low precipitation according to claim 5, wherein the outer layer, the first connecting layer and the barrier layer are extruded and compounded to form a base film, and the second connecting layer and the inner layer are sequentially laminated on the base film.

Technical Field

The invention relates to the technical field of packaging, in particular to a high-temperature-cooking packaging film with strong solvent resistance and low precipitation.

Background

The polymer material is widely used for flexible packaging materials of various foods and medicines, and various functional additives are often added into the packaging materials to improve or realize smoothness, openness, oxidation resistance, static resistance, antibacterial property and the like of the materials in order to facilitate the processing of the polymer material. However, the auxiliary agents, additives and other substances in the packaging material can migrate into the food during the food processing and storage process, thereby affecting the quality and safety of the food. For example, in the liquid packaging strip of cosmetics or medicines, the polyethylene surface is easier to adsorb organic active components in the cosmetics or medicines due to the lower surface energy of the inner polyethylene film, so that the loss of active ingredients in the products is caused; the aluminum foil barrier layer and the polyethylene layer of the packaging film can also cause glue migration or delamination of the packaging film due to small amounts of solvents in the contents of the hair dye, alcohol drink, mouthwash package.

Polyethylene (PE) is the largest volume and most used plastic packaging material in the world. In the composite plastic film, polyethylene is commonly used as an inner layer material due to excellent heat sealing performance, but the strength and heat resistance of polyethylene are not high, and the polyethylene is very easy to be heated and softened in a high-temperature cooking process during manufacturing of high-temperature cooking packages, so that strip packages are deformed or the appearance is poor, and cushion marks, extrusion marks or indentation marks appear.

Based on the defects and shortcomings of the packaging film, the invention provides the high-temperature-stewing packaging film with strong solvent resistance and low precipitation.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide a high-temperature-cooking-resistant packaging film which is resistant to high-temperature cooking and prevents small molecules from migrating, has strong solvent resistance and low precipitation.

In order to achieve the purpose, the technical scheme of the invention is to design a high-temperature cooking packaging film with strong solvent resistance and low precipitation, which comprises an outer layer, a first connecting layer, a barrier layer, a second connecting layer and an inner layer which are arranged from inside to outside in sequence,

the outer layer is a polyethylene terephthalate film (PET) or a biaxially oriented polypropylene film (BOPP), and the thickness of the outer layer is 12-25 mu m;

the first connecting layer is a mixture of modified high-density polyethylene or high-density metallocene polyethylene (MHDPE) and an ethylene-methacrylic acid-acrylate-maleic anhydride copolymer, or a mixture of high-density metallocene polyethylene (MHDPE) and Ethyl Methacrylate (EMA) or an ethylene acrylic acid copolymer (EAA) or an EMAA in DuPont, and the Vicat softening point of the modified high-density polyethylene is above 125 ℃; the mass ratio of the high-density metallocene polyethylene to the ethylene-methacrylic acid-acrylate copolymer is 3-5: 1; the first connecting layer is further added with 0.1-1% of antioxidant, 0.1-1% of anti-aging agent, 0.1-1% of slipping agent and 0.1-1% of toughening agent in percentage by mass of the first connecting layer; the thickness of the first connecting layer is 10-30 μm;

the barrier layer is one of aluminum foil, ethylene-vinyl alcohol copolymer (EVOH), polyamide (NY) silicon-plated PET film, silicon-plated OPP film, aluminum oxide-plated PET film and aluminum oxide-plated OPP film, and the thickness of the barrier layer is 7-15 mu m;

the second connecting layer is a mixture of modified high-density polyethylene or high-density metallocene polyethylene and an ethylene-methacrylic acid-acrylate copolymer; the molecular weight of the modified high-density polyethylene in the second connecting layer is more than 5000, the polymerization degree of the modified high-density polyethylene is more than 300, the chain number is less than 10, and the Vicat softening point of the modified high-density polyethylene is more than 125 ℃. It has been found from research that the diffusivity of additives in polyethylene is related to the free volume in polyethylene of sufficient or sufficient size. The longer the molecular chain of the polyethylene and the lower the number of chain ends, the closer the continuity between the chain ends, the fewer the cavities present and therefore the less the free volume, and therefore the slower the diffusion of the additive in the polyethylene of higher molecular weight. The diffusion of the small molecular additive can be effectively reduced by reducing the free volume, and the precipitation of the small molecular additive can be effectively reduced by increasing the molecular weight of polyethylene and the entanglement degree of polyethylene chains.

The properties of the additive also have an effect on the migration of the additive from the packaging film into the food, and the larger the molecular weight of the additive, the smaller the diffusion coefficient, and the more difficult the additive is to precipitate out of the packaging film.

The inner layer is one or a mixture of more of high-density polyethylene, cyclic olefin copolymer or copolymerized polypropylene; the inner layer is not added with an auxiliary agent, and the thickness of the inner layer is 5-50 mu m. The high-density polyethylene with high Vicat softening point meets the requirement of high-temperature cooking, and does not generate softening deformation in the high-temperature cooking process. The sequence of the three layers of films in the inner layer can be properly changed according to the requirements of products. In view of the problem of precipitation, the layer thickness ratio or formulation ratio of the inner layers needs to be suitably optimized for the properties of the product package.

Vicat Softening Temperature (VST), i.e. samples of polymers such as engineering plastics and general plastics are put in a liquid heat transfer medium and heated up under a certain load and a certain constant speed by 1mm²The pressing pin of (1) is pressed into the mold at a depth of 1 mm. The Vicat softening temperature is selected according to the cooking condition of the packaged contents, and when the cooking condition of the packaged contents is 100 ℃ water cooking, the Vicat softening temperature is higher than 105 ℃; when the cooking condition of the packing material is 125-135 ℃, the Vicat softening point is selected to be at least polyethylene or polypropylene copolymer higher than 125 ℃.

The inner layer of the packaging film adopts Cyclic Olefin Copolymer (COC), and the cyclic olefin copolymer can be independently adopted as the inner layer according to needs, or can be mixed with polyethylene and co-extruded polypropylene to be used as the inner layer. The cyclic olefin copolymer does not readily adsorb and reduce the content of the active ingredient.

Preferably, the modified high density polyethylene of the second tie layer is modified in the following manner: adding 10% of modified cellulose whiskers subjected to freeze drying and 5% of maleated polyethylene according to the mass percentage of the second connecting layer, wherein the average length of the modified cellulose whiskers is 300-500 nm, the average diameter of the modified cellulose whiskers is 20-30 nm, the modified cellulose is firstly blended and modified with N-aminoethyl-3-aminopropylmethyldimethoxysilane and a molecular sieve through the whiskers, and then the modified cellulose whiskers are added into high-density polyethylene.

As a preferable technical scheme, the first connecting layer is also added with a thermal stabilizing filler, and the addition amount of the thermal stabilizing filler is 0.5-2% in percentage by mass of the first connecting layer; the thermal stable filler is one or a mixture of more of aluminum nitride, boron nitride, silicon nitride or carbon nano tubes.

A proper amount of aluminum nitride and other heat-stable fillers are added into polyethylene, and the polyethylene nano composite material forms a barrier layer tissue of oxygen and diffusion of small molecular substances with the polyethylene at high temperature, so that a polyethylene layer is protected, the heat stability of the polyethylene material is improved, and the polyethylene nano composite material is suitable for high-temperature poaching packaging bags.

According to a preferable technical scheme, the inner layer is a three-layer blown film or three-layer cast film, and the inner layer is a combination of any three film layers of a cyclic olefin copolymer layer, a polypropylene copolymer layer, homo-polypropylene and a high-density polyethylene layer. It is preferable that the cyclic olefin copolymer layer is a layer in direct contact with the content.

Preferably, the antioxidant in the first connecting layer is 2, 6-di-tert-butyl, and the anti-aging agent is 2- (2-hydroxy-3, 5-di-tert-butyl phenyl) -5-chlorobenzotriazole or 2-hydroxy-4-n-octoxybenzophenone.

As a preferred technical scheme, the outer layer, the first connecting layer and the barrier layer are extruded and compounded to form a base film, and then the base film is extruded and compounded with the second connecting layer and the inner layer. The interlayer glass strength of the packaging film is more than 2.5N/15mm, and delamination can be avoided under the conditions of water boiling and cooking.

As a preferable technical scheme, the outer layer, the first connecting layer, the barrier layer, the second connecting layer and the inner layer are continuously extruded and compounded from two sides in series.

As a preferred technical scheme, the outer layer, the first connecting layer and the barrier layer are extruded and compounded to form a base film, and the second connecting layer and the inner layer are sequentially laminated on the base film.

The invention has the advantages and beneficial effects that: the invention provides a packaging film with strong solvent resistance and low precipitation and capable of being cooked at high temperature, which meets the requirement of high-temperature cooking by selecting a polyethylene material with high Vicat softening temperature; adopt the polyethylene that molecular weight is high, and utilize fibrous whisker to modify polyethylene, reduce the hole in the polyethylene structure, adopt the additive with large molecular weight simultaneously, effectual the precipitation of adding has been avoided, the inlayer of packaging film adopts the structure to be fine and close and the barrier layer that does not have any high density polyethylene and cyclic olefin copolymer of adding to form the additive, further effectual the precipitation of having avoided the additive, adopt the mode of extruding the complex simultaneously and drenching the membrane, avoid using glue, compatibility between the rete is still in the migration and the absorption of additive, compare in traditional compound mode more sanitary, solvent and additive precipitate still less.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a schematic structural view of the present invention;

in the figure: 1. an outer layer; 2. a first tie layer; 3. a barrier layer; 4. a second connection layer; 5. an inner layer; 51. a cyclic olefin copolymer layer; 52. a high density polyethylene layer; 53; a layer of co-polypropylene.

Detailed Description

The following description of the embodiments of the present invention will be made with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.