FFS packaging film and preparation method thereof

Abstract

The invention discloses an FFS packaging film and a preparation method thereof. The preparation method comprises the following steps: preparing a pre-dispersed master batch from in-situ polymerization resin micro powder of LLDPE and low-entanglement UHMWPE, nano montmorillonite and a low-melting-point activated dispersion component; the low-melting-point activating component is formed by compounding any one of erucyl amide, oleamide, octadecanamide and ethylene octadecanamide with an aluminate coupling agent, the compounding ratio is 2 / 1, and the usage amount of the low-melting-point activating component after compounding accounts for 15-50 wt% of the weight of the montmorillonite; in the production of the film, the pre-dispersed master batch is added into the middle layer resin and the outer layer resin to blow the FFS packaging film, the FFS packaging film is a three-layer co-extruded film, and the basic formula is as follows: the inner layer LDPE / mLLDPE ratio is 70 / 30, the middle layer is HDPE / mLLDPE / LLDPE ratio is 60 / 20 / 20, and the outer layer is mLLDPE / LLDPE ratio is 40 / 60. The invention has the technical characteristics that the comprehensive mechanical properties of the film can be improved, and the like.

Description

Technical Field

[0001] The present invention relates to a packaging film and a preparation method thereof, and more specifically, to an FFS packaging film and a preparation method thereof, and belongs to the field of polyethylene modified materials. Background Art

[0002] FFS bag is a heavy packaging film technology that integrates bag making (Film) - loading (Fil1) - sealing (Sea1). It is mainly used in the automatic packaging line of large-scale chemical synthetic resin granule products and has developed rapidly in China in recent years. In order to save costs, the industry continues to pursue the thinning of FFS film thickness, while its strength, stiffness, puncture resistance, impact resistance and other properties meet industry standards and automatic packaging line application requirements. At present, the market demand for FFS packaging film is increasing. With the pursuit of reducing film costs, in order to meet the high requirements of thinning and increasingly faster automatic packaging as well as storage and transportation without damage, traditional resin substrates can no longer achieve the performance goals of FFS film "thin but stiff, thin but strong". Summary of the invention

[0003] In order to solve the above-mentioned problems in the prior art, the present invention provides an FFS packaging film and a preparation method thereof having technical characteristics such as being able to improve the comprehensive mechanical properties of the film.

[0004] In order to achieve the above object, the present invention is implemented by the following technical solutions:

[0005] The present invention provides a method for preparing an FFS packaging film, the preparation method comprising the following steps:

[0006] Step 1) preparing a pre-dispersed masterbatch using in-situ polymerized resin powder of LLDPE and low-entanglement UHMWPE, nano-montmorillonite and a low-melting-point activated dispersing component; the low-melting-point activated component is compounded with an aluminate coupling agent using any one of erucamide, oleamide, stearamide, and ethylene stearamide, the compounding ratio is 2 / 1, and the amount used after compounding accounts for 15-50wt% of the weight of the montmorillonite;

[0007] Step 2) In film production, the pre-dispersed masterbatch is added to the middle layer and outer layer resins to blow the FFS packaging film.

[0008] Preferably, step 1) specifically includes: firstly, placing the nano-montmorillonite and the low-melting-point activation component in a cyclohexane solvent, and stirring at high speed for 30 minutes at 50±5°C, then stopping the heating and draining the solvent while stirring; adding the in-situ polymerized resin powder and mixing at high speed, and then mixing and granulating on a honey-refining and extruding integrated machine at below 130°C to obtain a pre-dispersed masterbatch.

[0009] Preferably, the parameters of LLDPE are: MFR value 2.0-4.0 g / 10 min, density 0.918-0.920 g / cm 3 , linear low density polyethylene copolymerized with 1-hexene; parameters of low entanglement UHMWPE in-situ polymerization resin powder: Mw 1 million to 3 million, powder particle size 10 to 120 μm, nano-montmorillonite parameters: fineness 600 to 2000 mesh, preferably 800 to 1200 mesh.

[0010] Preferably, the parameters of the low entanglement UHMWPE in-situ polymerized resin powder are: Mw 1.2 to 2 million, and the powder particle size is 30 to 70 μm.

[0011] Preferably, the amount used after compounding accounts for 25-35wt% of the weight of montmorillonite.

[0012] Preferably, the amounts of the components in the pre-dispersed masterbatch are 15 wt% of LLDPE in-situ polymerized resin powder, 35 wt% of UHMWPE in-situ polymerized resin powder, and 40 wt% of nano-montmorillonite.

[0013] The invention discloses an FFS packaging film, which is a three-layer co-extruded film, and has a basic formula of 70 / 30 LDPE / mLLDPE for an inner layer, 60 / 20 / 20 HDPE / mLLDPE / LLDPE for a middle layer, and 40 / 60 mLLDPE / LLDPE for an outer layer.

[0014] Preferably, 5-7 wt% of pre-dispersed masterbatch is added to the middle layer in the basic formula, and 3-5 wt% of pre-dispersed masterbatch is added to the outer layer in the basic formula.

[0015] Beneficial effects:

[0016] 1. The FFS packaging film of the present invention increases the comprehensive mechanical properties of the film by introducing a low-entanglement UHMWPE component; the lamellar structure of the nano-montmorillonite limits the entanglement tendency of the UHMWPE molecular chain during processing, thereby avoiding the generation of crystal points in the film.

[0017] 2. The activated dispersed components and their high-speed mechanical action with nano-montmorillonite in cyclohexane solvent fully infiltrate into the nano-sheet layers, play a role in peeling off the sheets and organicizing the surface of the inorganic powder, promoting the dispersion of the inorganic powder and obtaining a better interface effect.

[0018] 3. When the thickness of FFS film is reduced by 10%, its comprehensive mechanical properties still meet the requirements of BB / T0058-2011 industry standard. DETAILED DESCRIPTION

[0019] The present invention is further described below in conjunction with the embodiments of the specification, but the present invention is not limited to the following embodiments.

[0020] As the industry continues to pursue the reduction of FFS film thickness, the stiffness and strength of the film are reduced, affecting the automatic packaging and picking effect, and damage occurs from time to time during storage and transportation. The present invention mainly provides a low-entanglement ultra-high molecular weight polyethylene (UHMWPE) modified FFS packaging film and a preparation method thereof to achieve the comprehensive mechanical performance requirements of the film under thinning conditions; the FFS film of the present invention introduces low-entanglement UHMWPE resin in the middle layer and outer layer for modification and enhancement. From the results of literature and patent retrieval, the special resins for FFS film are mainly concentrated in the selection of polyethylene raw materials such as LDPE, HDPE, LLDPE, mLLDPE and the proportion of each layer. This patent provides a special material for the middle layer and outer layer. The special material essentially improves the puncture resistance, impact strength and tensile strength of the middle layer and outer layer of the FFS film by introducing low-entanglement UHMWPE, thereby obtaining a relatively thin FFS heavy packaging film with excellent comprehensive performance. The present invention has the characteristics of improving the comprehensive mechanical properties of the film, and can achieve the enhancement and thinning of the FFS film.

[0021] The product of the present invention is tested using national standards. The specific test method is as follows:

[0022] The film thickness is in accordance with GB / T 6672-2001.

[0023] The tensile strength is tested in accordance with GB / T 1040.1-2018 standard.

[0024] The impact damage quality is carried out in accordance with the provisions of GB / T 9639.1-2008 standard.

[0025] The trouser tear strength is tested in accordance with GB / T 16578.1.

[0026] Reference example:

[0027] The thickness of the FFS film is 144 μm, the tensile strength (longitudinal / transverse) of the film is 25 MPa / 24 MPa, the impact damage mass (surface / folded edge) is 620 g / 306 g, and the trouser tear strength (longitudinal / transverse) is 105 kN·m -1 / 122kN·m -1 .

[0028] The embodiments of the present invention are not limited to the embodiments formed by taking the left endpoint value of each range value, the embodiments formed by taking the right endpoint value, and the embodiments formed by taking the middle value, but also include specific embodiments formed by taking any numerical value in each range value. The following are 5 specific embodiments.

[0029] Embodiment 1:

[0030] Pre-dispersed masterbatch was added, wherein the UHMWPE resin powder in the pre-dispersed masterbatch had an Mw of 1 million and a particle size of 10 μm, the nano-montmorillonite fineness was 600 mesh, and the activated component accounted for 15 wt% of the montmorillonite weight. The obtained FFS film had a thickness of 131 μm, a tensile strength (longitudinal / transverse) of 27 MPa / 25 MPa, an impact damage mass (surface / folded edge) of 615 g / 303 g, and a trouser tear strength (longitudinal / transverse) of 106 kN·m -1 / 120kN·m -1 .

[0031] Embodiment 2:

[0032] Pre-dispersed masterbatch was added, wherein the UHMWPE resin powder in the pre-dispersed masterbatch had an Mw of 1.2 million and a particle size of 30 μm, the nano-montmorillonite fineness was 800 mesh, and the activated component accounted for 25 wt% of the montmorillonite weight. The obtained FFS film had a thickness of 129 μm, a tensile strength (longitudinal / transverse) of 28 MPa / 26.5 MPa, an impact damage mass (surface / folded edge) of 646 g / 313 g, and a trouser tear strength (longitudinal / transverse) of 112 kN·m -1 / 131kN·m -1 .

[0033] Embodiment 3:

[0034] Pre-dispersed masterbatch was added, wherein the UHMWPE resin powder in the pre-dispersed masterbatch had an Mw of 2 million and a particle size of 70 μm, the nano-montmorillonite fineness was 1200 mesh, and the activated component accounted for 35 wt% of the montmorillonite weight. The obtained FFS film had a thickness of 132 μm, a tensile strength (longitudinal / transverse) of 28.8 MPa / 27.1 MPa, an impact damage mass (surface / folded edge) of 651 g / 317 g, and a trouser tear strength (longitudinal / transverse) of 113 kN·m -1 / 129kN·m -1 .

[0035] Embodiment 4:

[0036] Pre-dispersed masterbatch was added, wherein the UHMWPE resin powder in the pre-dispersed masterbatch had an Mw of 3 million and a particle size of 120 μm, the nano-montmorillonite fineness was 2000 mesh, and the activated component accounted for 50 wt% of the montmorillonite weight. The obtained FFS film had a thickness of 133 μm, a tensile strength (longitudinal / transverse) of 25.1 MPa / 24.6 MPa, an impact damage mass (surface / folded edge) of 614 g / 311 g, and a trouser tear strength (longitudinal / transverse) of 108 kN·m -1 / 123kN·m -1 .

[0037] Embodiment 5:

[0038] Pre-dispersed masterbatch was added, wherein the UHMWPE resin powder in the pre-dispersed masterbatch had an Mw of 1.7 million and a particle size of 50 μm, the nano-montmorillonite fineness was 1000 mesh, and the activated component accounted for 30 wt% of the montmorillonite weight. The obtained FFS film had a thickness of 128 μm, a tensile strength (longitudinal / transverse) of 28.9 MPa / 27.6 MPa, an impact damage mass (surface / folded edge) of 660 g / 318 g, and a trouser tear strength (longitudinal / transverse) of 112 kN·m -1 / 131kN·m -1 .

[0039] Through comprehensive parameter comparison, the present invention discloses an FFS packaging film and a preparation method thereof, which has the characteristics of improving the comprehensive mechanical properties of the film, can meet the performance requirements of heavy packaging bags when the film is thinned, and provides a green and environmentally friendly production plan for the majority of FFS film production companies.

[0040] Finally, it should be noted that the present invention is not limited to the above embodiments, and there are many variations. All variations that can be directly derived or associated with the content disclosed by ordinary technicians in this field should be considered as the protection scope of the present invention.

Claims

1. A method for preparing FFS packaging film, characterized in that The preparation method comprises the following steps: Step 1): using in-situ polymerized resin powder of LLDPE and low-entanglement UHMWPE, nano-montmorillonite and low-melting-point activated dispersing component to prepare pre-dispersed masterbatch; the low-melting-point activated component is compounded with any one of erucic acid amide, oleic acid amide, stearic acid amide, ethylene stearic acid amide and an aluminate coupling agent, the compounding ratio is 2 / 1, and the amount used after compounding accounts for 15-50wt% of the weight of the montmorillonite; Step 2): Add the pre-dispersed masterbatch to the middle layer and outer layer resins to blow the FFS packaging film during film production.

2. The method for preparing a FFS packaging film according to claim 1, characterized in that: Step 1) specifically includes: firstly, placing the nano-montmorillonite and the low-melting-point activation component in a cyclohexane solvent, and stirring at high speed for 30 minutes at 50±5°C, then stopping the heating and draining the solvent while stirring; adding the in-situ polymerized resin powder and mixing at high speed, and then mixing and granulating on a honey-refining and extruding integrated machine at below 130°C to obtain a pre-dispersed masterbatch.

3. The method for preparing a FFS packaging film according to claim 1 or 2, characterized in that: LLDPE is a linear low-density polyethylene copolymerized with 1-hexene. Its parameters are: MFR value 2.0-4.0 g / 10 min, density 0.918-0.920 g / cm 3 , linear low density polyethylene copolymerized with 1-hexene; parameters of low entanglement UHMWPE in-situ polymerization resin powder: Mw 1 million to 3 million, powder particle size 10 to 120 μm, nano-montmorillonite parameters: fineness 600 to 2000 mesh, preferably 800 to 1200 mesh.

4. The method for preparing a FFS packaging film according to claim 3, characterized in that: The parameters of low entanglement UHMWPE in-situ polymerization resin powder are: Mw 1.2 to 2 million, powder particle size 30 to 70 μm.

5. The method for preparing a FFS packaging film according to claim 1, characterized in that: The amount used after compounding accounts for 25-35wt% of the weight of montmorillonite.

6. The method for preparing a FFS packaging film according to claim 1, characterized in that: The proportions of the components in the pre-dispersed masterbatch are 15 wt% of LLDPE in-situ polymerized resin powder, 35 wt% of UHMWPE in-situ polymerized resin powder, and 40 wt% of nano-montmorillonite.

7. A FFS packaging film, characterized in that: The FFS packaging film is a three-layer co-extruded film, and its basic formula is that the inner layer LDPE / mLLDPE is 70 / 30, the middle layer is HDPE / mLLDPE / LLDPE is 60 / 20 / 20, and the outer layer mLLDPE / LLDPE is 40 / 60.

8. The FFS packaging film according to claim 7, characterized in that: 5-7 wt% of pre-dispersed masterbatch is added to the middle layer in the basic formula, and 3-5 wt% of pre-dispersed masterbatch is added to the outer layer in the basic formula.