Co-extruded nylon film material as well as preparation method and application thereof

Abstract

The invention relates to the field of packaging, in particular to a co-extrusion nylon film material and a preparation method and application thereof. The co-extrusion nylon film is divided into seven layers from outside to inside, the first layer is a modified functional polyethylene layer, the second layer is a bonding resin layer, the third layer is a copolymer nylon layer, the fourth layer is a barrier layer, the fifth layer is a copolymer nylon layer, the sixth layer is a bonding resin layer, and the seventh layer is a modified functional polyethylene layer. According to the nylon co-extruded film material provided by the invention, through a special functional formula design and a multi-layer co-extrusion casting processing technology, the ultrahigh barrier performance is realized, the nylon co-extruded film material can replace or partially replace an existing EVOH co-extruded film, the supply limitation of an EVOH resin raw material is avoided, and the requirement of the market on a high-barrier co-extruded packaging material is met.

Description

Technical Field

[0001] The invention relates to the field of packaging, and in particular to a co-extruded nylon film material and a preparation method and application thereof. Background Art

[0002] Multi-layer co-extruded barrier film is a film produced by multi-layer co-extrusion blow molding process or cast film process. Multi-layer co-extruded film has excellent barrier properties, mechanical properties, stretch forming properties and heat sealing properties. No additional compounding is required during the processing, and there is no problem of printing ink, adhesive and additive residue. Therefore, it is a relatively green and environmentally friendly food packaging technology with cost advantages.

[0003] Multi-layer co-extruded film generally uses more than 3 extruders to melt and extrude resin raw materials with different functions, such as polyethylene, polypropylene, nylon, ethylene-vinyl alcohol copolymer, etc., and merge them at the multi-layer co-extrusion die through their respective flow channels. After inflation molding or casting molding, they are cooled and compounded together to produce a multi-layer co-extruded film.

[0004] The currently produced multi-layer co-extruded films, if they are to have ultra-high barrier properties, generally use ethylene-vinyl alcohol copolymer (EVOH) as the barrier layer. However, there are only three suppliers of ethylene-vinyl alcohol copolymer (EVOH) resin materials in the world, with a single procurement channel. In addition, ethylene-vinyl alcohol copolymer (EVOH) is expensive, resulting in a high production cost for high barrier co-extruded films.

[0005] Therefore, providing a co-extruded film material that does not use EVOH material, which can approach or exceed the performance of EVOH co-extruded film and various physical and mechanical performance indicators, and meet the market demand for high-barrier co-extruded packaging materials, is a technical problem that still needs to be solved. Summary of the invention

[0006] In order to solve the problems in the prior art, one of the objectives of the present invention is to provide a co-extruded nylon film material.

[0007] The present invention adopts the following technical solutions:

[0008] A co-extruded nylon film material, the co-extruded nylon film is divided into seven layers from the outside to the inside:

[0009] The first layer is a modified functional polyethylene layer, which is composed of 50%wt metallocene high-density polyethylene m-HDPE and 50%wt low-density polyethylene LDPE;

[0010] The second layer is an adhesive resin layer, which is composed of 100% wt maleic anhydride grafted PE;

[0011] The third layer is a copolymer nylon layer, which is composed of 100wt% polycaprolactam;

[0012] The fourth layer is a barrier layer, which is composed of 100wt% non-crystalline nylon polyamide resin;

[0013] The fifth layer is a copolymer nylon layer, which is composed of 100wt% polycaprolactam;

[0014] The sixth layer is an adhesive resin layer, which is composed of 100% wt maleic anhydride grafted PE;

[0015] The seventh layer is a modified functional polyethylene layer, which is composed of 32.4 wt% of polyolefin elastomer POE, 32.4 wt% of linear low-density polyethylene LLDPE, 32.4 wt% of low-density polyethylene LDPE and 2.8 wt% of additives.

[0016] Preferably, the polycaprolactam is C40L09 nylon produced by BASF AG of Germany, and the non-crystalline nylon polyamide resin is PA3426 resin produced by DuPont Chemicals.

[0017] Preferably, in the first layer, the metallocene high-density polyethylene m-HDPE is Dow Chemical's brand AT6900, and the low-density polyethylene LDPE is Exxon Chemical's brand 150BW; in the second and sixth layers, the maleic anhydride grafted PE is LyondellBasell Industries' brand PX3060; in the seventh layer, the polyolefin elastomer POE is Dow Chemical's brand PL1881G, the linear low-density polyethylene LLDPE is Yangzi Petrochemical's brand 7042, and the low-density polyethylene LDPE is Exxon's brand 100AC.

[0018] Preferably, in the seventh layer, the additives include an open masterbatch, a lubricating masterbatch and a processing aid, and the open masterbatch, the lubricating masterbatch and the processing aid are composed in a mass ratio of 13:13:2.

[0019] Preferably, the open masterbatch is Mitsui Chemicals brand EAZ-10 open masterbatch, the lubricating masterbatch is An color matching brand 10090-K lubricating masterbatch, and the processing aid is An color matching brand 100991-K processing aid.

[0020] Preferably, the total thickness of the co-extruded nylon film is 110-130 μm, and the thickness ratio of the first layer to the seventh layer is (30-34):(7-9):(11-15):(11-15):(11-15):(7-9):(31-35).

[0021] Preferably, the total thickness of the co-extruded nylon film is 120 μm, and the thicknesses of the first to seventh layers are 32 μm, 8 μm, 13 μm, 13 μm, 13 μm, 8 μm, and 33 μm, respectively.

[0022] The second object of the present invention is to provide a method for producing the co-extruded nylon film material as described above, the steps are as follows:

[0023] S1. The raw materials of the first to seventh layers of the co-extruded nylon film are respectively prepared in proportion and put into a mixer for mixing, and then respectively sent to an extruder for melting;

[0024] S2. According to the arrangement order of the first layer to the seventh layer, co-extrude using an extruder and then perform blow molding, the blow-up ratio is 2.0, and the thickness of each layer is controlled according to the designed value to obtain a co-extruded nylon film.

[0025] The third object of the present invention is to provide a co-extruded nylon film material as described above for use in packaging as a substitute for EVOH barrier co-extruded film.

[0026] The beneficial effects of the present invention are:

[0027] The present invention provides a special nylon co-extruded film material, which is a seven-layer composite film structure. Through special functional formula design and multi-layer co-extrusion casting processing technology, ultra-high barrier performance is achieved, and the existing EVOH co-extruded film can be replaced or partially replaced, avoiding the supply limitation of EVOH resin raw materials and meeting the market demand for high-barrier co-extruded packaging materials.

[0028] In this nylon co-extruded film, the third and fifth layers are set as copolymer nylon layers. Nylon has the characteristics of high oxygen barrier, good moisture resistance, and good fragrance retention. At the same time, it has the advantages and characteristics of strong mechanical properties, high drop resistance, puncture resistance, and good tear resistance. The thickness of the nylon layer has a great influence on the mechanical properties and drop resistance of the packaging material. The thickness of this film is set to 11-15μm, which can achieve better performance. The fourth layer is set as a non-crystalline nylon polyamide barrier resin layer. The DuPont Chemical PA3426 used is used for soft composite packaging. It has excellent barrier properties to oxygen, carbon dioxide and moisture, so that the prepared film has excellent physical properties, high temperature resistance, and appearance performance.

[0029] The adhesive resin layer uses maleic anhydride grafted PE, which has excellent bonding properties with polyethylene and nylon. In the adhesive resin, maleic anhydride monomer forms functional side chains on the main chain of polyethylene. These side chains can quickly and efficiently react chemically with polar resins to form covalent bonds and hydrogen bonds, so that polar polymers and non-polar polymers are bonded together to improve film performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic structural diagram of the nylon co-extruded film provided by the present invention.

[0031] The meanings of the symbols in the figure are as follows:

[0032] A-modified functional polyethylene layer B-adhesive resin layer C-copolymer nylon layer D-barrier layer

[0033] E-copolymer nylon layer F-adhesive resin layer G-modified functional polyethylene layer DETAILED DESCRIPTION

[0034] The technical solution of the present invention is described below in conjunction with the accompanying drawings and embodiments for easy understanding by those skilled in the art.

[0035] like Figure 1 As shown, a co-extruded nylon film material is a seven-layer composite film.

[0036] The first layer is a modified functional polyethylene layer, which is composed of 50wt% metallocene high-density polyethylene m-HDPE and 50wt% low-density polyethylene LDPE. The metallocene high-density polyethylene m-HDPE is selected from Dow Chemical's AT6900 metallocene high-density polyethylene, which has excellent water barrier properties, heat resistance, high stiffness, and excellent processing properties. The low-density polyethylene LDPE is selected from Exxon Chemical's 150BW low-density polyethylene.

[0037] The second layer is the adhesive resin layer, which is composed of 100%wt maleic anhydride grafted PE. LyondellBasell Industries' PX3060 is selected as the adhesive layer, and PX3060 has excellent adhesive bonding properties with polyethylene and nylon. In the adhesive resin, maleic anhydride monomer forms functional side chains on the main chain of polyethylene. These side chains can quickly and efficiently react chemically with polar resins to form covalent bonds and hydrogen bonds, so that polar polymers and non-polar polymers are bonded together, improving the composite performance of the film.

[0038] The third layer is a copolymer nylon layer, which is composed of 100wt% polycaprolactam. Specifically, C40L09 produced by BASF AG of Germany is used. C40L09 nylon has the characteristics of high oxygen barrier, good moisture resistance and good fragrance retention, which can improve the mechanical properties of the film, so that the prepared composite film has the characteristics of high drop resistance, good puncture resistance and tear resistance.

[0039] The fourth layer is a barrier layer, which is composed of 100wt% non-crystalline nylon polyamide resin. The non-crystalline nylon polyamide resin is DuPont Chemical PA3426 resin, which is used for soft composite packaging and has excellent barrier properties to oxygen, carbon dioxide and moisture, so that the prepared film has excellent physical properties, high temperature resistance and appearance performance.

[0040] The fifth layer is a copolymerized nylon layer, which is composed of 100 wt% polycaprolactam, and has the same composition as the third layer. The sixth layer is an adhesive resin layer, which is composed of 100 wt% maleic anhydride grafted PE, and has the same composition as the second layer.

[0041] The seventh layer is a modified functional polyethylene layer, which is composed of 32.4wt% polyolefin elastomer POE, 32.4wt% linear low-density polyethylene LLDPE, 32.4wt% low-density polyethylene LDPE and 2.8wt% additives. Among them, the additives include 1.3wt% open masterbatch, 1.3wt% slip masterbatch and 0.2wt% processing aids. The polyolefin elastomer POE selects Dow Chemical's PL1881G polyolefin elastomer, which makes the film have a good balance of low-temperature heat sealing performance, high toughness and high impact strength; the linear low-density polyethylene LLDPE selects Yangzi Petrochemical's 7042 linear low-density polyethylene, which has good mechanical strength and excellent heat sealing strength; the low-density polyethylene LDPE selects Exxon's 100AC low-density polyethylene, which has excellent processing performance. After blending resins with different functions, it has good processing performance, so that the film has high toughness, high impact strength, and excellent anti-pollution performance and low-temperature heat sealing performance.

[0042] The production method of the above co-extruded nylon film material comprises the following steps:

[0043] S1. The raw materials of the first to seventh layers of the co-extruded nylon film are respectively prepared in proportion and put into a mixer for mixing, and then respectively sent to an extruder for melting;

[0044] S2. According to the arrangement order of the first layer to the seventh layer, co-extrude using an extruder and then perform blow molding, the blow-up ratio is 2.0, and the thickness of each layer is controlled according to the designed value to obtain a co-extruded nylon film.

[0045] experiment

[0046] The co-extruded nylon film was produced by a seven-layer co-extrusion blow molding equipment of model VAREX produced by W&H Company of Germany.

[0047] The raw materials of the first modified functional polyethylene layer, the second adhesive resin layer, the third copolymer nylon layer, the fourth non-crystalline nylon polyamide barrier resin layer, the fifth copolymer nylon layer, the sixth adhesive resin layer and the seventh modified polyethylene heat sealing layer are added to the seven barrels of the seven-layer co-extrusion blowing equipment respectively. The specific formula of the raw materials of each layer is shown in Table 1.

[0048] Table 1 Co-extruded nylon film formula

[0049]

[0050] The raw materials in the seven barrels were co-extruded and then blow-molded, with a blow-up ratio of 2.0, and the thickness of each layer was controlled. The thickness comparison parameters of each layer are shown in Table 2.

[0051] Table 2 Co-extruded nylon film formulations prepared in Examples 1-3

[0052]

[0053] The production formula of conventional nylon co-extruded film (copolymerized nylon resin as barrier layer) was used as comparative example 1, and the commonly used high and ultra-high barrier co-extruded film (EVOH-nylon co-extruded film) was used as comparative example 2, and the performance tests were compared with the co-extruded nylon films prepared in Examples 1-3.

[0054] The formulas of Comparative Example 1 and Comparative Example 2 are shown in Table 3.

[0055] Table 3 Film formulations of Comparative Example 1 and Comparative Example 2

[0056]

[0057] The test results are shown in Table 4.

[0058] Table 4 Technical indicators of Examples 1-3 and Comparative Example 1 / 2

[0059]

[0060]

[0061] It can be seen that the special nylon co-extruded film material produced by the preparation process of the present invention has a maximum tensile strength of 68.2MPa in the TD direction, which is better than the comparative example, and a MD elongation at break of 776.9%, which has a good elongation. The film of the embodiment has a puncture strength far better than that of the comparative example, up to 12.1N, and has good barrier properties, with an oxygen permeability of less than 2cc / m 2 ·24h, the performance is almost the same as EVOH co-extruded film, but the moisture permeability is less than 2gm / m 2 ·24h, slightly better than EVOH co-extruded film. The film prepared by the present invention is basically consistent with the EVOH co-extruded film in terms of physical and mechanical performance indicators, can replace EVOH co-extruded film, and meet the market demand for high barrier co-extruded packaging materials.

[0062] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A co-extruded nylon membrane material, characterized in that: The co-extruded nylon film is divided into seven layers from the outside to the inside: The first layer is a modified functional polyethylene layer, which is composed of 50%wt metallocene high-density polyethylene m-HDPE and 50%wt low-density polyethylene LDPE; The second layer is an adhesive resin layer, which is composed of 100% wt maleic anhydride grafted PE; The third layer is a copolymer nylon layer, which is composed of 100wt% polycaprolactam; The fourth layer is a barrier layer, which is composed of 100wt% non-crystalline nylon polyamide resin; The fifth layer is a copolymer nylon layer, which is composed of 100wt% polycaprolactam; The sixth layer is an adhesive resin layer, which is composed of 100% wt maleic anhydride grafted PE; The seventh layer is a modified functional polyethylene layer, which is composed of 32.4 wt% of polyolefin elastomer POE, 32.4 wt% of linear low-density polyethylene LLDPE, 32.4 wt% of low-density polyethylene LDPE and 2.8 wt% of additives.

2. A co-extruded nylon membrane material according to claim 1, characterized in that: The polycaprolactam is C40L09 nylon from BASF AG of Germany, and the non-crystalline nylon polyamide resin is PA3426 resin from DuPont Chemicals.

3. A co-extruded nylon membrane material according to claim 1, characterized in that: In the first layer, the metallocene high-density polyethylene m-HDPE is Dow Chemical's brand AT6900, and the low-density polyethylene LDPE is Exxon Chemical's brand 150BW; in the second and sixth layers, the maleic anhydride grafted PE is LyondellBasell Industries' brand PX3060; in the seventh layer, the polyolefin elastomer POE is Dow Chemical's brand PL1881G, the linear low-density polyethylene LLDPE is Yangzi Petrochemical's brand 7042, and the low-density polyethylene LDPE is Exxon's brand 100AC.

4. A co-extruded nylon membrane material according to claim 1, characterized in that: In the seventh layer, the additives include an open masterbatch, a lubricating masterbatch and a processing aid, and the open masterbatch, the lubricating masterbatch and the processing aid are composed in a mass ratio of 13:13:

2.

5. A co-extruded nylon membrane material as claimed in claim 4, characterized in that: The open masterbatch is Mitsui Chemicals brand EAZ-10 open masterbatch, the smooth masterbatch is An color matching brand 10090-K smooth masterbatch, and the processing aid is An color matching brand 100991-K processing aid.

6. A co-extruded nylon membrane material according to any one of claims 1 to 5, characterized in that: The total thickness of the co-extruded nylon film is 110-130 μm, and the thickness ratio of the first layer to the seventh layer is (30-34):(7-9):(11-15):(11-15):(11-15):(7-9):(31-35).

7. A co-extruded nylon membrane material according to claim 6, characterized in that: The total thickness of the co-extruded nylon film is 120 μm, and the thicknesses of the first to seventh layers are 32 μm, 8 μm, 13 μm, 13 μm, 13 μm, 8 μm, and 33 μm, respectively.

8. A method for preparing a co-extruded nylon membrane material as claimed in claim 6, characterized in that: Here are the steps: S1. The raw materials of the first to seventh layers of the co-extruded nylon film are respectively prepared in proportion and put into a mixer for uniform mixing, and then respectively sent to an extruder for melting; S2. According to the arrangement order of the first layer to the seventh layer, co-extrude using an extruder and then perform blow molding, the blow ratio is 2.0, and the thickness of each layer is controlled according to the designed value to obtain a co-extruded nylon film.

9. Use of the coextruded nylon film material as claimed in claim 6 as a substitute for EVOH barrier coextruded film in packaging.

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