CN115674841A - multilayer structure film - Google Patents

Abstract

The present invention relates to a multilayer structure film comprising at least a first polyethylene layer, a second polyethylene layer, a first polyamide layer and a second polyamide layer coextruded and bonded together, wherein at least one of the first polyamide layer and the second polyamide layer is located between the first polyethylene layer and the second polyethylene layer. The invention also relates to a preparation method and application of the multilayer structure film.

Description

multilayer structure film

This application is a divisional application of a Chinese patent application with an application date of December 10, 2014, an application number of 201410758223.4, and an invention title of "multilayer structure film".

technical field

The invention relates to a multilayer structure film. In particular, the present invention relates to a multilayer structured film useful for food packaging, especially for packaging of granular substances such as rice. The invention also relates to the preparation method and application of the multilayer structure film.

Background technique

Plastic packaging films are known for their lightness and airtightness in the field of food packaging. In the packaging of granular materials such as rice, plastic packaging bags are more popular because they are superior to traditional woven bags in terms of appearance and moisture and insect resistance. Moreover, due to the airtightness of the plastic packaging film, vacuuming can be performed, thereby further compressing the volume of the contained material such as rice and prolonging its storage shelf life.

Because of its particularity, rice puts forward higher requirements for packaging films. For example, from the perspective of appearance and shape, rice grains are generally oblong or slender, and its tip can easily pierce the packaging film. A variety of multilayer structural films have been developed for rice packaging. Common structures include nylon/polyethylene (NY/PE) composite structure, nylon/chlorinated polyethylene (NY/CPE) composite structure, nylon/polyethylene (NY/PE) multilayer co-extruded structure, polyethylene/polyethylene (PE/PE) composite structure, etc. NY/PE or NY/CPE composite structure and PE/PE composite structure generally have the problems of poor puncture resistance and poor drop resistance after vacuuming. The NY/PE multilayer co-extrusion structure has relatively good puncture resistance, but usually requires a very thick PE sealing layer, for example, a PE sealing layer with a thickness of at least 110-130 μm is required.

Therefore, there is still a need for an improved multilayer structure film for the packaging of granular materials such as rice, which should especially have good puncture resistance, and can also have good strength and/or oxygen barrier properties, preferably in a more The low thickness and/or lower material costs maintain the desired packaging effect.

Contents of the invention

In a first aspect, the present invention relates to a multilayer structural film comprising at least a first polyethylene layer, a second polyethylene layer, a first polyamide layer and a second polyamide layer coextruded and bonded together layer, wherein at least one of the first polyamide layer and the second polyamide layer is located between the first polyethylene layer and the second polyethylene layer.

In a second aspect, the invention relates to a multilayer structural film comprising at least an outer polyamide layer and a first polyethylene layer, a second polyethylene layer, a first polyamide layer coextruded and bonded together. and a second polyamide layer, wherein at least one of said first polyamide layer and said second polyamide layer is located between said first polyethylene layer and said second polyethylene layer, said polyamide An outer layer is combined with at least one of the first polyethylene layer, the second polyethylene layer, the first polyamide layer, and the second polyamide layer to form a composite membrane.

In a third aspect, the present invention relates to a method of preparing a multilayer structural film comprising coextruding and bonding at least a first polyethylene layer, a second polyethylene layer, a first polyamide layer and a second polyamide layer Taken together, wherein at least one of said first polyamide layer and said second polyamide layer is located between said first polyethylene layer and said second polyethylene layer.

In a fourth aspect, the invention relates to the use of a multilayer structured film for the manufacture of packaging bags.

Description of drawings

The present invention is explained in detail through the following specific embodiments and accompanying drawings, in the hope that those skilled in the art can better understand the present invention, but it should not be construed as limiting the scope of the present invention in any way. It should be noted that the position and thickness of each layer in the multilayer structure film of the present invention can be adjusted as required, and are not necessarily consistent with or proportional to the positions and thicknesses shown in the drawings.

Figure 1 shows a cross-sectional view of a multilayer structure film comprising a first polyethylene layer, a first polyamide layer, a second polyamide layer and a second polyethylene layer according to one embodiment of the present invention.

Figure 2 shows a multilayer structure film comprising a first polyethylene layer, a first polyamide layer, a second polyamide layer and a second polyethylene layer sequentially bonded together by a tie layer according to another embodiment of the present invention cross-sectional view.

Figure 3 shows a cross-sectional view of a multilayer structure film comprising a first polyethylene layer, a first polyamide layer, a second polyamide layer and a second polyethylene layer according to yet another embodiment of the present invention, wherein the first The polyethylene layer and the second polyethylene layer each comprise two polyethylene sub-layers, the first polyethylene layer, the first polyamide layer, the second polyamide layer and the second polyethylene layer are sequentially bonded on the Together.

4 shows a cross-sectional view of a multilayer structure film comprising a first polyethylene layer, a first polyamide layer, a second polyamide layer, a second polyethylene layer and an outer polyamide layer according to yet another embodiment of the present invention, Wherein the first polyethylene layer and the second polyethylene layer each comprise two polyethylene sublayers, the first polyethylene layer, the first polyamide layer, the second polyamide layer and the second polyethylene layer are connected by The layers are bonded together in sequence, the first polyethylene layer being bonded to the polyamide outer layer by an adhesive layer.

Detailed ways

Numerical ranges herein include all values from the lower value to the upper value in increments of one unit and including said lower value and said upper value. For example, if the value range is 100 to 500, it should be considered to have listed all individual values such as 100, 101, 102... 498, 499 and all subranges such as 100 to 144 , 155 to 170, 197 to 200, 268-390, 420-500, etc.

As used herein, the term "composition" refers to a mixture of two or more materials. Included in the composition are pre-reaction, reaction and post-reaction mixtures, wherein the post-reaction mixture will include reaction products and by-products as well as unreacted components of the reaction mixture and decomposition products, if present, resulting from pre-reaction or reaction One or more components in a mixture form.

As used herein, the terms "blend", "polymer blend" refer to a composition of two or more polymers. Such blends are miscible or immiscible. Such blends may be homogeneous or heterogeneous, with or without phase separation.

multilayer structure film

The present invention provides a multilayer structure film with excellent puncture resistance by coextruding at least two polyethylene layers with at least two polyamide layers.

According to one embodiment of the present invention shown in FIG. Between the layers 108 there is a first polyamide layer 104 and a second polyamide layer 104, each layer being bonded together in turn.

Suitably, the first polyethylene layer 102 and the second polyethylene layer 108 may be independently selected from low density polyethylene (LDPE), linear low density polyethylene (LLDPE), medium density polyethylene (MDPE) , high-density polyethylene (HDPE), ultra-low-density polyethylene (VLLDPE), ultra-high molecular weight polyethylene (UHMWPE), metallocene polyethylene (mPE) (such as metallocene linear low-density polyethylene (mLLDPE)), modified Polyethylenes such as chlorinated polyethylene (CPE), cross-linked polyethylene (PEX), ethylene copolymers and any mixtures thereof. The ethylene copolymers may be selected from, for example, ethylene-olefin copolymers (such as copolymers of ethylene with propylene, butene, pentene, hexene, heptene, octene, nonene, decene, cycloolefins or any combination thereof), Ethylene-unsaturated ester copolymers (such as copolymers of ethylene with methyl methacrylate, ethyl methacrylate, vinyl acetate, methyl acrylate, ethyl acrylate, maleic anhydride or any combination thereof) and any mixture thereof .

In a preferred embodiment, the first polyethylene layer 102 and the second polyethylene layer 108 each independently comprise low density polyethylene (LDPE), linear low density polyethylene (LLDPE), medium density polyethylene ( MDPE), high density polyethylene (HDPE), very low density polyethylene (VLLDPE), ultra high molecular weight polyethylene (UHMWPE), metallocene linear low density polyethylene (mLLDPE) or any mixture thereof.

The first polyethylene layer 102 and the second polyethylene layer 108 may each independently comprise a blend of LDPE and LLDPE. In one embodiment, at least one of said first polyethylene layer and said second polyethylene layer is essentially a blend of LDPE and LLDPE. The blend of LDPE and LLDPE may comprise at least 10% LDPE, preferably at least 15%, more preferably at least 20%, even more preferably at least 25% LDPE, based on the total weight of the blend. The blend of LDPE and LLDPE may comprise up to 70% LDPE, preferably up to 60%, more preferably up to 50%, even more preferably up to 40% LDPE, based on the total weight of the blend. The blend of LDPE and LLDPE may comprise at least 30% LLDPE, preferably at least 35%, more preferably at least 40%, even more preferably at least 45% LLDPE based on the total weight of the blend. The blend of LDPE and LLDPE may comprise up to 90% LLDPE, preferably up to 80%, more preferably up to 70%, even more preferably up to 60% LDPE, based on the total weight of the blend. In a particular embodiment, said blend of LDPE and LLDPE comprises 10-30% LDPE and 70-90% LLDPE based on the total weight of the blend. In another particular embodiment, said blend of LDPE and LLDPE comprises 20-40% LDPE and 60-80% LLDPE based on the total weight of the blend.

Further, the first polyethylene layer 102 and the second polyethylene layer 108 may each independently comprise a blend of LDPE, mLLDPE and LLDPE. Preferably, at least one or both of said first polyethylene layer and said second polyethylene layer are substantially a blend of LDPE, mLLDPE and LLDPE. Blends of LDPE, mLLDPE, and LLDPE are believed to provide good puncture resistance to the multilayer structured films of the present invention while maintaining other desirable properties such as oxygen barrier, softness, toughness, and the like. The desired balance of properties can be obtained by adjusting the ratio between LDPE, mLLDPE and LLDPE. For example, the blend of LDPE, mLLDPE and LLDPE may comprise at least 20% LLDPE, preferably at least 25%, more preferably at least 30%, even more preferably at least 35% LLDPE based on the total weight of the blend. The blend of LDPE, mLLDPE and LLDPE may comprise up to 90% LLDPE, preferably up to 80%, more preferably up to 70%, even more preferably up to 60% LLDPE based on the total weight of the blend. In another aspect, the blend of LDPE, mLLDPE and LLDPE may comprise up to 50% LDPE, preferably up to 45%, more preferably up to 35%, even more preferably up to 30% LDPE based on the total weight of the blend. The blend of LDPE, mLLDPE and LLDPE may comprise at least 5% LDPE, preferably at least 10%, more preferably at least 15%, even more preferably at least 18% LDPE based on the total weight of the blend. In yet another aspect, the blend of LDPE, mLLDPE and LLDPE comprises at most 90% mLLDPE, preferably at most 80%, more preferably at most 70%, even more preferably at most 65% mLLDPE based on the total weight of the blend. The blend of LDPE, mLLDPE and LLDPE may comprise at least 10% mLLDPE, preferably at least 20%, more preferably at least 30%, even more preferably at least 35% mLLDPE based on the total weight of the blend. In a specific embodiment, the blend of LDPE, mLLDPE and LLDPE comprises 15-25% LDPE, 15-25% mLLDPE and 50-70% LLDPE based on the total weight of the blend. In another specific embodiment, said blend of LDPE, mLLDPE and LLDPE comprises 15-25% LDPE, 40-60% mLLDPE and 25-40% LLDPE based on the total weight of the blend.

Suitably, the first polyamide layer 104 and the second polyamide layer 106 can independently adopt polyamide (nylon) commonly used in the art to prepare polymer films, such as nylon 6, nylon 66, nylon 6/66, nylon 10, nylon 10/10, nylon 12, nylon MX-D6, amorphous nylon or any mixture thereof. The amorphous nylon can be a nylon copolymer or a blend of one or more nylons. In a preferred embodiment, said first polyamide layer 104 and said second polyamide layer 106 each independently comprise Nylon 6. In another preferred embodiment, said first polyamide layer 104 and said second polyamide layer 106 each independently comprise nylon 66. In yet another preferred embodiment, at least one or both of said first polyamide layer 104 and said second polyamide layer 106 consist essentially of Nylon 6.

The inventors have surprisingly found that two or more layers of polyamide provide better puncture resistance than one layer of polyamide for the same overall thickness and material composition. Preferably, at least one of said first polyamide layer and said second polyamide layer is located between said first polyethylene layer and said second polyethylene layer. In a specific embodiment, one or both of said first polyamide layer and said second polyamide layer are located between said first polyethylene layer and said second polyethylene layer. In the multilayer structure film 10 shown in FIG. 1, both the first polyamide layer 104 and the second polyamide layer 106 are located between the first polyethylene layer 102 and the second polyethylene layer 108. between. In a further embodiment, the multilayer structure film may also comprise further polyamide layers in addition to the first polyamide layer and the second polyamide layer. For example, in one embodiment, the multilayer structural film may comprise three, four, five or more polyamide layers, wherein at least one, two or three of the polyamide layers are positioned on the third between a polyethylene layer and said second polyethylene layer.

The first polyethylene layer 102, first polyamide layer 104, second polyamide layer 106 and second polyethylene layer 108 may be bonded together by any suitable means. Possibilities include surface treatment of the individual layers to allow them to bond together naturally, lamination by co-extrusion at high temperature and natural bonding after cooling, or bonding through a tie layer.

In an alternative embodiment, the positions of the first polyethylene layer 102 and the first polyamide layer 104 may be interchanged, or the positions of the second polyethylene layer 108 and the second polyamide layer 106 can be interchanged.

Figure 2 shows a multilayer structural film 20 according to another embodiment of the present invention comprising a first polyethylene layer 202, a first polyamide layer 206, a second polyamide layer 210 and a second polyethylene layer 214, the The various layers described above are sequentially bonded together by tie layers 204 , 208 and 212 .

A tie layer suitable for bonding the first polyethylene layer 202, first polyamide layer 206, second polyamide layer 210 and second polyethylene layer 214 together may comprise low density polyethylene, linear low density polyethylene, Ethylene, metallocene linear low density polyethylene, acetate acrylate copolymers or anhydride modified polyethylene copolymers and any mixtures thereof. In a preferred embodiment, the tie layer comprises at least 50%, preferably 60%, more preferably 70% linear low density polyethylene, based on the total weight of the tie layer. In a preferred embodiment, the tie layer may comprise maleic anhydride modified polyethylene copolymer or ethylene-vinyl acetate copolymer. Additionally or alternatively, the tie layer may comprise any other polymeric adhesive conventionally used in the field of multilayer structural film production, preferably the adhesive is acceptable for food packaging. The specific example of the adhesive that can be used has the extrudable adhesive of Plexar, Px3410, PX3747 produced by the U.S. Equistar Chemical Company. FDA approval for adhesives, but also limited direct food contact approval.

In a further embodiment, at least one of the first polyethylene layer and the second polyethylene layer may comprise two or more polyethylene sub-layers laminated together. In a specific embodiment, said first polyethylene layer or said second polyethylene layer independently comprises two, three or four polyethylene sub-layers laminated together.

Each polyethylene sublayer may independently comprise low density polyethylene (LDPE), linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), very low density polyethylene (VLLDPE) ), ultra-high molecular weight polyethylene (UHMWPE), metallocene linear low-density polyethylene (mLLDPE) or any mixture thereof. For example, each polyethylene sublayer may each independently be a blend of LDPE, mLLDPE and LLDPE or a blend of LDPE and LLDPE as described above.

Figure 3 shows a cross section of a multilayer structure film 30 comprising a first polyethylene layer 301, a first polyamide layer 308, a second polyamide layer 312, and a second polyethylene layer 315 according to yet another embodiment of the present invention Figure, wherein the first polyethylene layer 301 includes two polyethylene sublayers 302 and 304, the second polyethylene layer 315 includes two polyethylene sublayers 316 and 318, the first polyethylene layer 301, the first polyamide Layer 308 , second polyamide layer 312 and second polyethylene layer 315 are sequentially bonded together by tie layers 306 , 310 and 314 .

Preferably, the first polyethylene layer 301 and the second polyethylene layer 315 each independently comprise two, three, four, five or six polyethylene sub-layers laminated together. The thickness of the polyethylene sublayer can be adjusted according to the desired total thickness of the first polyethylene layer or the second polyethylene layer and the number of polyethylene sublayers, and the thickness of each polyethylene sublayer can be the same or different. In a preferred embodiment, each polyethylene sublayer has a thickness of at most 40 μm, preferably at most 30 μm, more preferably at most 20 μm, even more preferably at most 15 μm or 10 μm.

In a still further embodiment, the multilayer structural film of the present invention further comprises a polyamide outer layer, the polyamide outer layer is in contact with the first polyethylene layer, the second polyethylene layer, the first polyamide The amide layer and at least one of the second polyamide layers combine to form a composite membrane. In a preferred embodiment, said polyamide outer layer is passed through at least one of said first polyethylene layer, said second polyethylene layer, said first polyamide layer and said second polyamide layer The binders combine to form a composite film.

Figure 4 shows a multilayer structure comprising a polyamide outer layer 402, a first polyethylene layer 405, a first polyamide layer 412, a second polyamide layer 416 and a second polyethylene layer 419 according to yet another embodiment of the present invention A cross-sectional view of a film 40, wherein a first polyethylene layer 405 includes two polyethylene sublayers 406 and 408, a second polyethylene layer 419 includes two polyethylene sublayers 420 and 422, the first polyethylene layer 405, The first polyamide layer 412, the second polyamide layer 416 and the second polyethylene layer 419 are sequentially bonded together through the tie layers 410, 414 and 418, and the polyamide outer layer 402 is connected to the polyamide layer 404 through the adhesive layer 404. The polyethylene sub-layer 406 of the first polyethylene layer 405 is bonded.

The polyamide outer layer can adopt various polyamides (nylon) that can be generally used to form the outer layer of the multilayer film structure in the art, such as including nylon 6, nylon 66, nylon 6/66, nylon 10, nylon 10/10, Nylon 12, Nylon MX-D6, Amorphous Nylon or any mixture thereof. The amorphous nylon can be a nylon copolymer or a blend of one or more nylons. In a preferred embodiment, the polyamide outer layer 402 consists essentially of nylon 6. In another preferred embodiment, the polyamide outer layer 402 consists essentially of nylon 66. In yet another preferred embodiment, the polyamide outer layer 402 consists essentially of nylon MX-D6.

The polyamide outer layer 402 may be a monoaxially or biaxially oriented polyamide (nylon) film, preferably a biaxially oriented polyamide (nylon) film. Optionally, surface treatment can be carried out on the bonding surface of the polyamide outer layer 402 to enhance its adhesion, and the surface treatment can include corona treatment, plasma treatment, actinic radiation, flash lamp treatment, flame treatment, etc. one or more of .

The adhesive layer 404 suitable for combining the polyamide outer layer 402 with the first polyethylene layer 405 can use any adhesive commonly used in the art, such as vinyl acetate-ethylene copolymer adhesive, Polyacrylate adhesives, polyurethane adhesives, epoxy resin adhesives, etc. Polyurethane adhesives are especially suitable for use in the present invention to bond polyamide layers and polyethylene layers of different properties together to provide a multilayer structural film with excellent puncture resistance. Polyurethane adhesives that can be used include, but are not limited to, water-based polyurethane adhesives, hot melt polyurethane adhesives, solvent-based polyurethane adhesives, and solvent-free polyurethane adhesives. Polyurethane adhesives can be one-component adhesives or two-component adhesives. In one embodiment, the adhesive layer 404 is a two-component polyurethane adhesive. The two-component polyurethane adhesive is composed of two components, A and B. When used, the two components are weighed and mixed in different proportions according to the substrate to be bonded for bonding, and can be cured at room temperature. Component A of the two-component polyurethane adhesive can be a linear product whose terminal group is a hydroxyl group formed by the copolymerization of linear polyurethane and isocyanate, and component B can be a pre-isocyanate terminal group formed by the reaction of isocyanate and polyol. Polymer. Two-component polyurethane adhesives have good adhesion, flexibility, insulation and abrasion resistance, and can withstand weak acids, especially suitable for food packaging. In another embodiment, the adhesive layer 404 employs a two-component adhesive comprising hydroxyl-terminated polyester urethane as a main component.

The thickness of the polyamide outer layer depends on the thickness of the entire multilayer structure film, and is at most 50% of the thickness of the multilayer structure film, usually between 5-40%, preferably 10-40% of the thickness of the multilayer structure film. 30%, more preferably between 15 and 25%.

In order to impart a specific appearance to the resulting multilayer structure film, colored pigments or patterns may be included in the individual layers. For example, specific colors or patterns for identification purposes may be included in the polyamide outer layer. Optionally, UV stabilizers, antioxidants and other components that can increase the added value of the multilayer structure film can also be added to each layer as required, as long as these components will not obviously impair the desired performance, such as puncture resistance properties, strength, oxygen barrier properties, etc.

Compared with the prior art, the multilayer structure film according to the present invention can provide better puncture resistance with a thinner thickness. The thickness of the multilayer structure film according to the present invention can be adjusted as required. Typically, when used as a food packaging bag for granular substances such as rice, the multilayer structure film according to the present invention may generally have a thickness of 10-200 μm, preferably 20-180 μm, more preferably 30-150 μm, such as 50-120 μm or 60 - 100 μm or 40-80 μm or 70-110 μm thickness.

When performance testing is carried out to the multilayer structure film according to the present invention, it is found that in many tested properties, such as heat seal strength, tensile properties, coefficient of friction, etc., the multilayer structure film according to the present invention can be achieved with a smaller The thickness is comparable to the traditional multilayer structure film with a large thickness, and it is significantly better than the traditional multilayer structure film in terms of oxygen barrier properties, drop resistance and pendulum impact resistance. In addition, the peeling strength of the multilayer structure film of the present invention can meet the use requirements of ordinary packaging, and no delamination and peeling phenomenon will occur during normal use.

The preparation method of multilayer structure film

The multilayer structure film according to the present invention can be prepared by any suitable method, for example, by die coextrusion, extrusion coating and/or film extrusion lamination, adhesive lamination, blown film coextrusion, etc. .

In order to maximize the advantages of the multilayer structure film according to the present invention, the multilayer structure film of the present invention can be prepared by, but not limited to, the following method: at least the first polyethylene layer, the second polyethylene layer, the first polyethylene layer An amide layer and a second polyamide layer are coextruded and bonded together, wherein at least one of the first polyamide layer and the second polyamide layer is located between the first polyethylene layer and the second polyamide layer. between layers of polyethylene.

In a preferred embodiment, the method of the present invention provides a method for preparing a multilayer structure film, said method comprising combining at least a first polyethylene layer, a second polyethylene layer, a first polyamide layer and a second polyamide layer. amide layers are coextruded and bonded together by a tie layer, wherein at least one of said first polyamide layer and said second polyamide layer is located between said first polyethylene layer and said second polyethylene layer between.

Co-extrusion is a well-known technology in the art, and for example may include the following steps: using multi-layer co-extruded film equipment, blowing a variety of molten polymer compositions in a molten state at the die outlet, casting, Extruded and laminated together, while gradually cooling, after undergoing a complex interplay of stretching, orientation and crystallization to the crimping device.

Other multilayer structure film fabrication techniques suitable for the present invention can be found in the following documents: The Encyclopedia of Chemical Technology, Kirk-Othmer, Third Edition, John Wiley & Sons, New York, 1981, Vol. 16, pages 416-417 and 18 Vol., pp. 191-192; Wilmer A. Jenkins and James P. Harrington, Packaging Foods With Plastics, (1991), pp. 19-27; Thomas I. Butler, "Coextrusion Basics", Film Extrusion Manual: Process, Materials, Properties 31 - 80 pages (published by TAPPI Press (1992)); "Coextrusion For Barrier Packaging" by W.J. Schrenk and C.R. Finch, Society of Plastics Engineers RETEC Proceedings, June, 15-17 (1981), pp. 211-229; K.R.Osborn and W.A. Jenkins; and Plastic Films, Technology and Packaging Applications (Technomic Publishing Co., Inc. (1992)), which are hereby incorporated by reference in their entirety.

The polyamide outer layer and the multilayer co-extruded film comprising at least said first polyethylene layer, said second polyethylene layer, said first polyamide layer and said second polyamide layer can be obtained by skilled in the art Composite using a dry compounding process well known to personnel, the specific steps may include, for example, using a dry compounding machine to coat the adhesive on the surface of the polyamide outer layer and/or the multilayer coextrusion film, and attach the two surfaces Cover and heat to ripen.

The use of multilayer structure film

The multilayer structure film according to the present invention can be used in various applications, especially where puncture resistance is required. In one embodiment, the multilayer structured film of the present invention can be used to make packaging bags. The packaging bag can be used to hold liquid or solid substances. The solid matter can be selected from one or more of bulk, granular and powdery matter. Blocky substances such as stones, wood, metal, food (such as salad) and so on. Granular substances such as gravel, plant seeds (such as sunflower seeds, watermelon seeds, etc.), spices (such as star anise, pepper, etc.), rice, millet, corn, beans, etc. Powdered substances such as flour, milk powder, soybean powder, etc. In a specific embodiment, the packaging bag is used for packaging a substance selected from rice, millet, corn, salad, flour or any mixture thereof. The multilayer structure film of the present invention and the packaging bag prepared therefrom can be used for vacuum packaging or air-filled packaging. In a specific embodiment, the multi-layer structure film of the present invention is particularly suitable for vacuum packaging substances with sharp points (such as rice) due to its excellent puncture resistance.

Therefore, the present invention provides at least the following:

1. A multilayer structure film comprising at least a first polyethylene layer, a second polyethylene layer, a first polyamide layer and a second polyamide layer co-extruded and bonded together, wherein the first At least one of a polyamide layer and the second polyamide layer is located between the first polyethylene layer and the second polyethylene layer.

2. The multilayer structure film of item 1, wherein said first polyethylene layer and said second polyethylene layer are each independently selected from low density polyethylene, linear low density polyethylene, medium density polyethylene, high density polyethylene Ethylene, ultra-low-density polyethylene, ultra-high-molecular-weight polyethylene, metallocene linear low-density polyethylene, chlorinated polyethylene, cross-linked polyethylene, ethylene copolymers, and any mixtures thereof.

3. The multilayer structure film according to item 2, wherein at least one of said first polyethylene layer and said second polyethylene layer is low-density polyethylene, metallocene linear low-density polyethylene, and linear low-density polyethylene. blends.

4. The multilayer structure film of item 3, wherein the low density polyethylene, metallocene linear low density polyethylene and the blend of linear low density polyethylene comprise at least 20% linear low density polyethylene based on the total weight of the blend polyethylene.

5. The multilayer structure film of item 3, wherein said low density polyethylene, metallocene linear low density polyethylene and the blend of linear low density polyethylene comprise at least 5% of low density polyethylene based on the total weight of the blend. vinyl.

6. The multilayer structure film of item 3, wherein said low density polyethylene, metallocene linear low density polyethylene and the blend of linear low density polyethylene comprise at least 10% of metallocene linear low density polyethylene based on the total weight of the blend. Low-density polyethylene.

7. The multilayer structure film of item 3, wherein said low-density polyethylene, metallocene linear low-density polyethylene, and a blend of linear low-density polyethylene comprise 15-25% of low-density polyethylene based on the total weight of the blend. Polyethylene, 40-60% metallocene linear low density polyethylene and 25-40% linear low density polyethylene.

8. The multilayer structural film of item 1, wherein the individual layers are bonded together by a tie layer comprising at least 50% linear low density polyethylene based on the total weight of the tie layer.

9. The multilayer structural film of any one of items 1-8, wherein at least one of said first and second polyethylene layers comprises two or more polyethylene sublayers laminated together, Each of said polyethylene sublayers has a thickness of at most 30 μm.

10. The multilayer structural film of item 1, further comprising an outer polyamide layer in contact with the first polyethylene layer, the second polyethylene layer, the first polyamide layer and the At least one of the second polyamide layers is combined to form a composite membrane.

11. The multilayer structural film of item 10, wherein said outer polyamide layer is in contact with said first polyethylene layer, said second polyethylene layer, said first polyamide layer, and said second polyamide layer At least one of them is combined by an adhesive to form a composite film.

12. The multilayer structured film of item 10 or 11, wherein the polyamide outer layer consists of biaxially oriented polyamide.

13. The multilayer structure film according to item 11, wherein the adhesive is a two-component adhesive comprising hydroxyl-terminated polyester urethane as a main component.

14. The multilayer structural film according to item 10 or 11, wherein the thickness of the outer polyamide layer is between 5-40% of the total thickness of the multilayer structural film.

15. A method of preparing a multilayer structural film according to any one of items 1-14, comprising coextruding at least a first polyethylene layer, a second polyethylene layer, a first polyamide layer and a second polyamide layer and bonded together, wherein at least one of the first polyamide layer and the second polyamide layer is located between the first polyethylene layer and the second polyethylene layer.

16. The method according to item 15, comprising coextruding and bonding at least said first polyethylene layer, said second polyethylene layer, said first polyamide layer and said second polyamide layer by a tie layer. combine together.

17. Use of the multilayer structured film according to any one of items 1-14 for the production of packaging bags.

18. The use according to item 17, wherein the packaging bag is used for packaging one or more substances selected from block, granule and powder.

19. The use according to item 18, wherein the packaging bag is used for packaging a substance selected from rice, millet, corn, salad, flour or any mixture thereof.

20. The use according to any one of items 17-19, wherein the packaging bag is used for vacuum packaging or air-filled packaging.

Example

Some specific implementations of the present invention are explained below in conjunction with examples, so that those skilled in the art can more clearly understand the technical solutions and advantages of the present invention, but do not limit the present invention in any way.

1. Materials

Comparative examples and example samples of multilayer structure films were prepared using the following materials.

2. Preparation of multilayer structure film

2.1 Comparative example 1

A PE three-layer co-extrusion film with a thickness of 110 μm was prepared by ReifenHouser SW2200 multi-layer co-extrusion blown film equipment. The die temperature of each layer was 220°C. The structure of the PE three-layer co-extrusion film and the composition of each layer and the layer thickness ratio based on the total thickness of the co-extrusion film are as follows:

B40L与上述PE三层共挤膜中的第一层通过聚氨酯粘合剂XH-750E以3.6g/m²的上胶量粘合在一起，然后在55℃的温度下熟化48h。得到的多层结构膜中聚氨酯粘合剂的厚度为2μm。The outer layer of biaxially oriented polyamide with a thickness of 15 μm was processed by Taiwan Sanxia DL-S1300 dry lamination machine

B40L and the first layer of the above-mentioned PE three-layer co-extrusion film are bonded together by polyurethane adhesive XH-750E with a glue amount of 3.6g/ ^m2 , and then aged at a temperature of 55°C for 48h. The thickness of the polyurethane adhesive in the obtained multilayer structure film was 2 μm.

2.2 Comparative example 2

A PE three-layer co-extrusion film with a thickness of 100 μm was prepared by ReifenHouser SW2200 multi-layer co-extrusion blown film equipment. The die temperature of each layer was 220°C. The structure of the PE three-layer co-extrusion film and the composition of each layer and the layer thickness ratio based on the total thickness of the co-extrusion film are as follows:

B40L与上述PE三层共挤膜中的第一层通过聚氨酯粘合剂XH-750E以3.6g/m²的上胶量粘合在一起，然后在55℃的温度下熟化48h。得到的多层结构膜中聚氨酯粘合剂的厚度为2μm。The outer layer of biaxially oriented polyamide with a thickness of 15 μm was processed by Taiwan Sanxia DL-S1300 dry lamination machine

B40L and the first layer of the above-mentioned PE three-layer co-extrusion film are bonded together by polyurethane adhesive XH-750E with a glue amount of 3.6g/ ^m2 , and then aged at a temperature of 55°C for 48h. The thickness of the polyurethane adhesive in the obtained multilayer structure film was 2 μm.

2.3 Embodiment 1

A PE/PA nine-layer co-extrusion film with a thickness of 80 μm was prepared by ReifenHouser SW2200 multi-layer co-extrusion blown film equipment. The die temperature of each layer was 220°C. The structure of the PE/PA nine-layer co-extrusion film and the composition of each layer and the layer thickness ratio based on the total thickness of the co-extrusion film are as follows:

B40L与上述PE三层共挤膜中的第一层通过聚氨酯粘合剂XH-750E以3.6g/m²的上胶量粘合在一起，然后在55℃的温度下熟化48h。得到的多层结构膜中聚氨酯粘合剂的厚度为2μm。The outer layer of biaxially oriented polyamide with a thickness of 15 μm was processed by Taiwan Sanxia DL-S1300 dry lamination machine

B40L and the first layer of the above-mentioned PE three-layer co-extrusion film are bonded together by polyurethane adhesive XH-750E with a glue amount of 3.6g/ ^m2 , and then aged at a temperature of 55°C for 48h. The thickness of the polyurethane adhesive in the obtained multilayer structure film was 2 μm.

2.4 Example 2

A PE/PA nine-layer co-extrusion film with a thickness of 80 μm was prepared by ReifenHouser SW2200 multi-layer co-extrusion blown film equipment. The die temperature of each layer was 220°C. The structure of the PE/PA nine-layer co-extrusion film and the composition of each layer and the layer thickness ratio based on the total thickness of the co-extrusion film are as follows:

B40L与上述PE三层共挤膜中的第一层通过聚氨酯粘合剂XH-750E以3.6g/m的上胶量粘合在一起，然后在55℃的温度下熟化48h。得到的多层结构膜中聚氨酯粘合剂的厚度为2μm。The outer layer of biaxially oriented polyamide with a thickness of 15 μm was processed by Taiwan Sanxia DL-S1300 dry lamination machine

B40L and the first layer of the above-mentioned PE three-layer co-extrusion film are bonded together by polyurethane adhesive XH-750E with a glue amount of 3.6g/m, and then aged at a temperature of 55°C for 48h. The thickness of the polyurethane adhesive in the obtained multilayer structure film was 2 μm.

3. Performance testing

According to the requirements in GB/T 10004-2008, a number of performance tests were carried out on the multilayer structure films of Comparative Examples 1 and 2 and Examples 1 and 2 above.

3.1 Drop performance

The drop performance test was carried out on the bags made of the multilayer structure films of Comparative Examples 1 and 2 and Examples 1 and 2 above. Since vacuuming can better test the puncture resistance of the packaging bag, this test is a vacuuming test.

The test surface is cement floor. The bag is filled with 5 kg of rice and vacuumed. With the six surfaces of the package obtained after vacuuming facing the test surface (concrete floor) respectively, the package is freely dropped from a specific height (1.5m, 2.0m, 2.5m, 3.0m) and visually inspected for air leakage or pierce. The results are shown in Table 1.

Table 1 Drop performance test results

The drop performance test results show that the packaging bag prepared by the multilayer structure film (thickness is 80 μm+17 μm) according to the embodiments of the present invention 1 and 2 can be dropped from a height of 2.0 meters or even a height of 2.5 meters after vacuum packaging rice. There was no air leakage or puncture phenomenon when dropped 3 times, while comparative example 1 had a larger thickness (110 μm + 17 μm), but air leakage and puncture phenomenon occurred when it was dropped from a height of 2.0 meters, and comparative example 2 (Thickness 100μm+17μm) Even when dropped from a height of 1.5 meters, air leakage and punctures occur.

In other words, in the drop test with a height of less than 1.5 meters, the traditional multi-layer structure film has punctured and air leakage, and the rate of bag breakage is 100%, while the multi-layer structure film of the present invention is dropped three times each. In the drop test at a height of less than 2 meters, the bag break rate of the layered structure film is 0%.

3.2 Pendulum impact resistance performance

According to GB/T 8809-1988, the pendulum impact resistance test was carried out on the multilayer structure films of Comparative Examples 1 and 2 and Examples 1 and 2 above, and the results are shown in Table 2.

Table 2 Pendulum impact resistance performance test results

Pendulum impact energy resistance (J) Comparative example 1 1.73 Comparative example 2 1.78 Example 1 1.83 Example 2 1.87

Compared with Comparative Examples 1 and 2, Examples 1 and 2 according to the present invention provide a multilayer structure film with a smaller thickness and greater pendulum impact energy resistance.

3.3 Oxygen barrier properties

According to GB/T19789-2005, the oxygen barrier properties of the multilayer films of the above comparative examples 1 and 2 and examples 1 and 2 were tested by Coulomb coulometric method, and the results are shown in Table 3.

Table 3 Oxygen barrier performance test results

Oxygen transmission rate (cm³/(m²·24h)) Comparative example 1 33.60 Comparative example 2 31.36 Example 1 13.56 Example 2 16.52

From the oxygen transmission rate data in Table 3, the multilayer structure films of Examples 1 and 2 according to the present invention are only about 1/2 or less of the multilayer structure films of Comparative Examples 1 and 2. Therefore, compared with Comparative Examples 1 and 2, Examples 1 and 2 according to the present invention provided significantly more excellent oxygen barrier properties with a smaller thickness.

3.4 Heat seal strength

According to QB/T 2358-1988, the heat seal strength test was carried out on the bags made of the multilayer structure films of Comparative Examples 1 and 2 and Examples 1 and 2 above. A bag of 510 mm (length) x 310 mm (width) was formed by folding and heat-sealing a multilayer structure film of 1020 mm (length) x 310 mm (width) in the longitudinal direction. The heat seal along the length direction is called side heat seal, and the heat seal along the width direction is called top heat seal. The measured heat seal strength results are shown in Table 4 below.

Table 4 heat seal strength test results

Compared with Comparative Examples 1 and 2, the multilayer structure films of Examples 1 and 2 according to the present invention exhibit more balanced top and side edges and excellent heat-sealing strength.

3.5 Tensile properties

According to GB/T 1040.3-2006, the tensile performance test was carried out on the multilayer structure films of Comparative Examples 1 and 2 and Examples 1 and 2, and the obtained breaking force and elongation at break are shown in Table 5.

Table 5 Tensile performance test results

Note: The extrusion direction of the multi-layer co-extruded film is the longitudinal direction.

Compared with Comparative Examples 1 and 2, the multilayer structure films of Examples 1 and 2 according to the present invention have comparable tensile strength and toughness.

3.6 Friction coefficient

According to GB/T 10006-1988, the friction coefficient test was carried out on the multilayer structure films of Comparative Examples 1 and 2 and Examples 1 and 2 above, and the results are shown in Table 6.

Table 6 friction coefficient test results

Static friction coefficient dynamic friction coefficient Comparative example 1 0.11 0.10 Comparative example 2 0.15 0.11 Example 1 0.15 0.12 Example 2 0.11 0.08

Compared with Comparative Examples 1 and 2, the multilayer structure films of Examples 1 and 2 according to the present invention had comparable coefficients of friction.

Although the present invention has been described in detail with reference to specific embodiments and preferred embodiments at present, those skilled in the art of the present invention can understand that there may be various changes and/or various substitutions in the structure described above, and these changes And/or permutations are included within the spirit and scope of the invention. It is to be understood that the invention should not be limited to the specific construction and compositional arrangements described herein. Changes and improvements made on the basis of the disclosure of the present invention are also included in the scope of the present invention. It should also be understood that the invention disclosed herein extends to any combination of two or more features mentioned or evident from the text. All of these different combinations constitute various possible aspects of the invention.

Claims (20)

1. A multilayer structure film comprising at least a first polyethylene layer, a second polyethylene layer, a first polyamide layer, and a second polyamide layer coextruded and bonded together, wherein at least one of the first polyamide layer and the second polyamide layer is located between the first polyethylene layer and the second polyethylene layer.

2. The multilayer structural film of claim 1, wherein said first polyethylene layer and said second polyethylene layer are each independently selected from the group consisting of low density polyethylene, linear low density polyethylene, medium density polyethylene, high density polyethylene, ultra low density polyethylene, ultra high molecular weight polyethylene, metallocene linear low density polyethylene, chlorinated polyethylene, crosslinked polyethylene, ethylene copolymers, and any mixtures thereof.

3. The multilayer structural film of claim 2, wherein at least one of said first polyethylene layer and said second polyethylene layer is a blend of low density polyethylene, metallocene linear low density polyethylene, and linear low density polyethylene.

4. The multilayer structural film of claim 3, wherein the blend of low density polyethylene, metallocene linear low density polyethylene, and linear low density polyethylene comprises at least 20% linear low density polyethylene based on the total weight of the blend.

5. The multilayer structural film of claim 3, wherein the blend of low density polyethylene, metallocene linear low density polyethylene, and linear low density polyethylene comprises at least 5% low density polyethylene based on the total weight of the blend.

6. The multilayer structural film of claim 3, wherein the blend of low density polyethylene, metallocene linear low density polyethylene, and linear low density polyethylene comprises at least 10% metallocene linear low density polyethylene based on the total weight of the blend.

7. The multilayer structural film of claim 3, wherein the blend of low density polyethylene, metallocene linear low density polyethylene, and linear low density polyethylene comprises 15 to 25% low density polyethylene, 40 to 60% metallocene linear low density polyethylene, and 25 to 40% linear low density polyethylene, based on the total weight of the blend.

8. The multilayer structural film of claim 1, wherein the individual layers are bonded together by a tie layer comprising at least 50% linear low density polyethylene based on the total weight of the tie layer.

9. The multilayer structural film of any of claims 1-8, wherein at least one of said first and second polyethylene layers comprises two or more sub-layers of polyethylene laminated together, each of said sub-layers of polyethylene having a thickness of at most 30 μm.

10. The multilayer structural film of claim 1, further comprising an outer layer of polyamide combined with at least one of the first polyethylene layer, the second polyethylene layer, the first polyamide layer, and the second polyamide layer to form a composite film.

11. The multilayer structural film of claim 10, wherein the outer polyamide layer is bonded to at least one of the first polyethylene layer, the second polyethylene layer, the first polyamide layer, and the second polyamide layer by an adhesive to form a composite film.

12. The multilayer structural film of claim 10 or 11, wherein said polyamide outer layer is comprised of biaxially oriented polyamide.

13. The multilayer structural film of claim 11, wherein the adhesive is a two-part adhesive comprising a hydroxyl-terminated polyester urethane as a main component.

14. The multilayer structural film of claim 10 or 11, wherein the thickness of the polyamide outer layer is between 5-40% of the total thickness of the multilayer structural film.

15. A method of making a multilayer structural film according to any of claims 1-14 comprising co-extruding and bonding together at least a first polyethylene layer, a second polyethylene layer, a first polyamide layer, and a second polyamide layer, wherein at least one of the first polyamide layer and the second polyamide layer is positioned between the first polyethylene layer and the second polyethylene layer.

16. The method of claim 15, comprising coextruding and bonding together at least the first polyethylene layer, the second polyethylene layer, the first polyamide layer, and the second polyamide layer through tie layers.

17. Use of a multilayer structured film according to any one of claims 1 to 14 for the production of packaging bags.

18. Use according to claim 17, wherein the packaging bag is used for packaging one or more selected from the group consisting of block, granular and powder materials.

19. Use according to claim 18, wherein the package is for packaging a substance selected from rice, millet, corn, salad, flour or any mixture thereof.

20. Use according to any one of claims 17 to 19, wherein the packaging bag is for vacuum packaging or gas packaging.

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