Anti-ultraviolet aging packaging bag material and production process thereof

Abstract

The invention relates to the technical field of polymer composite materials, and discloses an anti-ultraviolet aging packaging bag material and a production process thereof, the anti-ultraviolet aging packaging bag material comprises the following components by weight: 50-70 parts of HDPE resin, 8-15 parts of POE elastomer, 5-10 parts of surface modified nano calcium carbonate, 25-35 parts of an intumescent flame retardant, 1.5-4.0 parts of a synergistic stabilization composite additive, 3-8 parts of a compatilizer, and 0.1-0.3 part of a processing antioxidant; wherein the synergistic stabilization compound additive is prepared by compounding a high-molecular-weight hindered amine light stabilizer, an ultraviolet light absorber and a main antioxidant. According to the invention, through a pre-stabilization treatment process, a compounded synergistic stabilization composite auxiliary agent is anchored on the surface of intumescent flame retardant particles in advance, and a protective layer is constructed between the intumescent flame retardant and an ultraviolet aging environment; migration and loss of the intumescent flame retardant under long-term ultraviolet irradiation are inhibited from the source, so that the limit oxygen index and the vertical combustion grade of the material can still keep high stability after accelerated ultraviolet aging.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials technology, specifically to an anti-ultraviolet aging packaging bag material and its production process. Background Technology

[0002] High-density polyethylene (HDPE) is widely used in the packaging bag industry due to its excellent mechanical strength, moisture resistance, and low cost. However, pure HDPE material has poor weather resistance and is prone to photo-oxidative degradation under outdoor ultraviolet (UV) radiation, leading to film embrittlement and loss of mechanical properties, which severely limits its application in scenarios requiring long-term outdoor storage or transportation.

[0003] To improve the toughness of HDPE, the industry often introduces polyolefin elastomers (POE) for blending and toughening; simultaneously, calcium carbonate (CaCO3) is often used as a filler to reduce costs and increase rigidity. However, simple blending has significant drawbacks: the addition of a large amount of inorganic filler can cause stress concentration, offsetting the toughening effect of POE and leading to a decrease in material toughness. Furthermore, to further expand application scenarios, HDPE often needs flame retardant modification, among which intumescent flame retardants (IFR) are widely used due to their high efficiency and low smoke characteristics. However, IFR has poor compatibility with the HDPE matrix, and during processing and use, especially under ultraviolet radiation, it easily migrates to and is lost from the material surface. This migration not only directly leads to a sharp decline in flame retardant performance over time, but the migration process itself also damages the structural integrity of the material, accelerates matrix aging, and forms a vicious cycle of "aging-migration-performance degradation".

[0004] Currently, improvements addressing these issues are mostly focused on fixing single performance characteristics. For example, adding conventional UV absorbers or light stabilizers can be effective, but in complex multiphase systems (HDPE / POE / CaCO3 / IFR), these additives are unevenly dispersed, easily interact with fillers or flame retardants, and become ineffective, failing to suppress the photoaging process centered on IFR migration in a long-term and effective manner. Furthermore, imparting additional functionality to packaging materials (such as high water barrier properties) often requires complex multilayer composite structures, further increasing costs and manufacturing complexity. Summary of the Invention

[0005] The purpose of this invention is to provide an anti-ultraviolet aging packaging bag material and its manufacturing process to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: An anti-UV aging packaging bag material, composed of the following parts by weight: 50-70 parts HDPE resin, 8-15 parts POE elastomer, 5-10 parts surface-modified nano-calcium carbonate, 25-35 parts intumescent flame retardant, 1.5-4.0 parts synergistic stabilizing composite additive, 3-8 parts compatibilizer, 0.1-0.3 parts processing antioxidant; The synergistic stabilizing compound is composed of a high molecular weight hindered amine light stabilizer, an ultraviolet absorber, and a main antioxidant in a weight ratio of (1.5-2.5):1:0.5.

[0007] As a further aspect of the present invention: the amount of the intumescent flame retardant added is 30% of the total weight of the packaging bag material; and the intumescent flame retardant is a nitrogen-phosphorus compound intumescent flame retardant.

[0008] As a further embodiment of the present invention: the high molecular weight hindered amine light stabilizer is hindered amine light stabilizer HS-944, the ultraviolet absorber is ultraviolet absorber UV-531, and the main antioxidant is antioxidant 1010.

[0009] As a further embodiment of the present invention: the particle size of the surface-modified nano-calcium carbonate is 40-100 nm, and its surface is modified by aluminate coupling agent and polyethylene glycol.

[0010] As a further aspect of the present invention: the compatibilizer is maleic anhydride-grafted high-density polyethylene.

[0011] As a further aspect of the present invention: the surface of the film substrate prepared by the packaging bag material is coated with a hydrophobic polymer waterproof coating, wherein the hydrophobic polymer waterproof coating is a modified fluorocarbon coating or an organosilicon coating, and the thickness of the hydrophobic polymer waterproof coating is 1 to 5 μm.

[0012] As a further aspect of the present invention: the film substrate of the packaging bag material is a multilayer co-extruded structure, wherein at least one layer is a microporous barrier layer containing a pore-forming agent and formed by biaxial stretching, and the water vapor permeability of the microporous barrier layer is <5g / m²·24h.

[0013] A manufacturing process for an anti-UV aging packaging bag material includes the following steps: S1. Pre-stabilization treatment: The intumescent flame retardant is preheated and mixed with a portion of compatibilizer and a portion of synergistic stabilizing composite additives at 60-80°C for 10-15 minutes to obtain pre-stabilized IFR masterbatch. S2. Main mixing: HDPE resin, POE elastomer, surface-modified nano calcium carbonate, remaining compatibilizer, remaining synergistic stabilizing composite additive, processing antioxidant and pre-stabilized IFR masterbatch are mixed evenly to obtain the mixture. S3. Melt blending and granulation: The mixture is fed into a twin-screw extruder, melt-blended, extruded, cooled and granulated at an extrusion temperature of 165-200℃ to obtain functional composite masterbatch; S4. Film Forming and Functionalization: The functional composite masterbatch is blown into a film substrate by a blown film machine; then the film substrate is subjected to surface waterproof coating treatment or microporous barrier structure is formed by multi-layer co-extrusion process.

[0014] As a further embodiment of the present invention: in step S1, the amount of a portion of the compatibilizer is 30% to 40% of the total amount of the compatibilizer, and the amount of a portion of the synergistic stabilizing composite additive is 40% to 60% of its total amount; In step S3, the screw speed of the twin-screw extruder is 250–350 rpm.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention employs a pre-stabilization process to pre-anchor the compounded synergistic stabilizing additives onto the surface of intumescent flame retardant particles, constructing a protective layer between the intumescent flame retardant and the ultraviolet aging environment. This process inhibits the migration and loss of the intumescent flame retardant under long-term ultraviolet irradiation from the source, ensuring that the limiting oxygen index and vertical flammability rating of the material remain highly stable even after accelerated ultraviolet aging.

[0016] By selecting maleic anhydride-grafted polyethylene as a compatibilizer and controlling the filling amount and surface modification of nano-calcium carbonate, the interfacial adhesion between materials was significantly improved. This enabled the material to still achieve excellent initial toughness through POE elastomer and good interface, even with high flame retardant filling, thus balancing the contradiction between flame retardancy, rigidity and toughness. Detailed Implementation

[0017] Example 1: In this embodiment of the invention, an anti-UV aging packaging bag material is composed of the following parts by weight: HDPE resin: 60 parts, model HD 5502GA, melt flow rate (MFR, 190℃ / 2.16kg) is 0.8 g / 10min; POE elastomer: 10 parts, model ENGAGE 8150, octene content 28%, MFR 1.0g / 10min; Surface-modified nano-calcium carbonate: 8 parts, average particle size 80nm, surface modified by composite surface modification with aluminate coupling agent (DL-411) and polyethylene glycol (PEG-4000); Intumescent flame retardant: 30 parts, is a nitrogen-phosphorus compound IFR (APP / PER / MEL system, in which the weight ratio of ammonium polyphosphate: pentaerythritol: melamine is approximately 3:1:1). Synergistic stabilizing composite additive: 2.0 parts; its composition is: 1.2 parts of light stabilizer 944 (HALS), 0.8 parts of ultraviolet absorber UV-531 (UVA), and 0.4 parts of antioxidant 1010 (AO); Compatibilizer: 5 parts, maleic anhydride-grafted high-density polyethylene, with a grafting rate of 0.8%; Processing antioxidant: 0.2 parts, which is antioxidant 168; Waterproof coating raw material: water-based fluorocarbon resin emulsion (solid content 40%), used for subsequent coating.

[0018] A manufacturing process for an anti-UV aging packaging bag material includes the following steps: S1. IFR Pre-stabilization Treatment: Take all 30 parts of intumescent flame retardant (IFR), 2 parts of compatibilizer (accounting for 40% of the total compatibilizer), and 0.7 parts of light stabilizer 944 and 0.3 parts of antioxidant 1010 (accounting for 50% of the total amount of synergistic stabilizing composite additives, mainly HALS and AO components), and add them together to a high-speed mixer (GH-10 type); start the mixer and mix for 12 minutes under heating conditions of 70℃, so that the compatibilizer and additives melt and uniformly coat the surface of the IFR particles. After completion, discharge the material to obtain pre-stabilized IFR masterbatch, cool and set aside for later use; S2. Mixing of main raw materials: Add the remaining 60 parts HDPE, 10 parts POE, 8 parts surface-modified nano-calcium carbonate, 3 parts compatibilizer, 0.5 parts light stabilizer 944, 0.8 parts UV-531, 0.1 parts antioxidant 1010 (i.e., the remaining synergistic stabilizing composite additive components), 0.2 parts antioxidant 168, and all the pre-stabilized IFR masterbatch obtained in step S1 to a high-speed mixer; mix at room temperature (25℃) for 10 minutes to ensure that all components are mixed evenly to obtain a dry mix; S3. Melt blending and granulation: The above dry mixture is fed into the feed hopper of a co-rotating twin-screw extruder (length-to-diameter ratio 40:1); the temperatures of each section of the extruder are set as follows: Zone 1 165℃, Zone 2 175℃, Zone 3 185℃, Zone 4 190℃, and the die head 185℃; the screw speed is set to 300 rpm; after melting, shearing, and mixing, the material is extruded from the die head into strips, cooled in a water tank, and then cut into uniform particles with a length of about 3mm by a pelletizer to obtain functional composite masterbatch, which is then dried for later use; S4. Film Forming and Surface Coating: The functional composite masterbatch is fed into the hopper of a single-layer blown film machine; the die temperature of the blown film machine is set to 190°C, and top-blown blow molding is performed to obtain a film substrate with a thickness of 0.08 mm and a folded diameter of 500 mm; subsequently, the film substrate is subjected to a corona treatment device (processing power 3kW) for surface activation; the activated film is immediately passed through a precision roller coater to uniformly coat one side with the above-mentioned water-based fluorocarbon resin emulsion; the coated film enters a 6-meter-long drying tunnel and is dried and cured under hot air at 80-100°C to finally form a waterproof coating with a dry film thickness of about 2 μm, and after winding, the composite packaging film of the present invention is obtained.

[0019] Example 2: In this embodiment of the invention, an anti-UV aging packaging bag material is composed of the following parts by weight: The composition of HDPE is 62 parts, POE is 10 parts, and nano-CaCO3 is 6 parts; the total amount of synergistic stabilizing composite additives is increased to 2.5 parts, of which: light stabilizer 944 is 1.5 parts, UV-531 is 1.0 part, and antioxidant 1010 is 0.5 parts; in the pre-stabilization treatment, the amount of synergistic stabilizing composite additives used is increased accordingly; the rest is the same as in Example 1.

[0020] A manufacturing process for an anti-UV aging packaging bag material includes the following steps: Same as Example 1.

[0021] Example 3: In this embodiment of the invention, an anti-UV aging packaging bag material is composed of the following parts by weight: The total amount of HDPE is 58 parts, POE is increased to 12 parts, and nano-CaCO3 is 8 parts; the total amount of synergistic stabilizing composite additives is increased to 3.0 parts, of which: light stabilizer 944 is 1.8 parts, UV-531 is 1.2 parts, and antioxidant 1010 is 0.6 parts; the rest is the same as in Example 1.

[0022] A manufacturing process for an anti-UV aging packaging bag material includes the following steps: Same as Example 1.

[0023] Example 4: In this embodiment of the invention, an anti-UV aging packaging bag material is composed of the following parts by weight: Same as Example 1.

[0024] A manufacturing process for an anti-UV aging packaging bag material includes the following steps: In step S4, corona treatment and fluorocarbon coating are not performed; otherwise, it is the same as in Example 1.

[0025] Example 5: In this embodiment of the invention, an anti-UV aging packaging bag material is composed of the following parts by weight: The HDPE content is 55 parts, POE is increased to 15 parts, nano-CaCO3 is increased to 10 parts, and compatibilizer is increased to 8 parts; the rest is the same as in Example 1.

[0026] A manufacturing process for an anti-UV aging packaging bag material includes the following steps: In step S4, a three-layer co-extrusion blown film (A / B / A structure) is used; wherein, layer A (outer layer): composite masterbatch; layer B (middle layer): masterbatch obtained by mixing and granulating 70 parts HDPE and 30 parts calcium carbonate pore maker (particle size 1μm); after blow molding, the film is immediately subjected to biaxial stretching (the longitudinal and transverse stretching ratios are both 3:1) to form a microporous structure in layer B. No surface coating treatment is performed; otherwise, it is the same as in Example 1.

[0027] To better illustrate the technical solution of the present invention, the following comparative experiments are conducted: Comparative Example 1: An anti-UV aging packaging bag material, composed of the following parts by weight: 65 parts HDPE, 35 parts IFR, free of POE, nano CaCO3, compatibilizer, and synergistic stabilizing composite additives.

[0028] A manufacturing process for an anti-UV aging packaging bag material includes the following steps: All raw materials (HDPE, IFR, antioxidant 168) are mixed only once using conventional methods (without pre-stabilization treatment), then melt-granulated and blown into film.

[0029] Comparative Example 2: An anti-UV aging packaging bag material, composed of the following parts by weight: POE (12 parts), nano CaCO3 (8 parts), IFR (30 parts), compatibilizer (8 parts), but no synergistic stabilizing composite additives (light stabilizer 944, UV-531, antioxidant 1010) are added.

[0030] A manufacturing process for an anti-UV aging packaging bag material includes the following steps: All raw materials are mixed in a conventional single process (without pre-stabilization treatment), then melt-granulated and blown into film.

[0031] All the above samples were subjected to the same standard performance test; the key results are compared in Table 1 below.

[0032] Table 1: Comparison of key data on initial performance and performance after 28 days of UV aging

[0033] Analysis of the table above shows that: 1. Example 1 demonstrates the complete solution of the present invention: by using synergistic stabilizing composite additives and pre-stabilization treatment processes, while achieving excellent initial toughness (520%) and flame retardancy (LOI 31.0%, V-2), it also obtains excellent weather resistance (78.8% elongation retention after aging, LOI retention of 27.1%) and extremely low IFR migration (<3%), and successfully integrates surface waterproofing function (WVTR <3.0).

[0034] 2. Examples 2 and 3 show that, within the framework of this invention, adjusting the content of stabilizer or toughening agent can maintain excellent overall performance, demonstrating the flexibility and adjustability of the solution.

[0035] 3. Example 4 demonstrates that even without surface waterproofing treatment, the material itself still possesses the core weather resistance-flame retardant synergistic stability of this invention.

[0036] 4. Example 5 demonstrates that waterproofing can also be achieved through microporous membranes, and the core solution of the present invention remains effective in more challenging formulations with high filler and high toughness.

[0037] 5. Comparative Example 1 (basic flame-retardant HDPE) exhibited severe brittleness and extremely poor weather resistance, verifying the inadequacy of simply adding IFR.

[0038] 6. Comparative Example 2 (with toughening but no stabilizing system) showed acceptable initial toughness, but its weather resistance was significantly inferior to all other examples, with severe IFR migration. This directly and powerfully demonstrates that the synergistic stabilizing composite additive and pre-stabilization treatment process in this invention are indispensable and synergistically innovative in solving IFR migration and achieving long-term stability, rather than simply being additive.

[0039] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A UV-resistant packaging bag material, characterized in that, The composition by weight is as follows: 50-70 parts HDPE resin, 8-15 parts POE elastomer, 5-10 parts surface-modified nano-calcium carbonate, 25-35 parts intumescent flame retardant, 1.5-4.0 parts synergistic stabilizing composite additive, 3-8 parts compatibilizer, 0.1-0.3 parts processing antioxidant; The synergistic stabilizing compound is composed of a high molecular weight hindered amine light stabilizer, an ultraviolet absorber, and a main antioxidant in a weight ratio of (1.5-2.5):1:0.

5.

2. The UV-resistant packaging bag material according to claim 1, characterized in that, The amount of the intumescent flame retardant added is 30% of the total weight of the packaging bag material; and the intumescent flame retardant is a nitrogen-phosphorus compound intumescent flame retardant.

3. The UV-resistant packaging bag material according to claim 1, characterized in that, The high molecular weight hindered amine light stabilizer is hindered amine light stabilizer HS-944, the ultraviolet absorber is ultraviolet absorber UV-531, and the main antioxidant is antioxidant 1010.

4. The UV-resistant packaging bag material according to claim 1, characterized in that, The surface-modified nano-calcium carbonate has a particle size of 40-100 nm, and its surface is modified by a combination of aluminate coupling agent and polyethylene glycol.

5. The UV-resistant packaging bag material according to claim 1, characterized in that, The compatibilizer is maleic anhydride-grafted high-density polyethylene.

6. The UV-resistant packaging bag material according to claim 1, characterized in that, The surface of the film substrate prepared by the packaging bag material is coated with a hydrophobic polymer waterproof coating, which is a modified fluorocarbon coating or an organosilicon coating, and the thickness of the hydrophobic polymer waterproof coating is 1 to 5 μm.

7. The UV-resistant packaging bag material according to claim 1, characterized in that, The film substrate prepared by the packaging bag material is a multi-layer co-extruded structure, wherein at least one layer is a microporous barrier layer containing a pore-forming agent and formed by biaxial stretching, and the water vapor permeability of the microporous barrier layer is <5g / m²·24h.

8. A production process for an anti-UV aging packaging bag material according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Pre-stabilization treatment: The intumescent flame retardant is preheated and mixed with a portion of compatibilizer and a portion of synergistic stabilizing composite additives at 60-80°C for 10-15 minutes to obtain pre-stabilized IFR masterbatch. S2. Main mixing: HDPE resin, POE elastomer, surface-modified nano calcium carbonate, remaining compatibilizer, remaining synergistic stabilizing composite additive, processing antioxidant and pre-stabilized IFR masterbatch are mixed evenly to obtain the mixture. S3. Melt blending and granulation: The mixture is fed into a twin-screw extruder, melt-blended, extruded, cooled and granulated at an extrusion temperature of 165-200℃ to obtain functional composite masterbatch; S4. Film Forming and Functionalization: The functional composite masterbatch is blown into a film substrate by a blown film machine; then the film substrate is subjected to surface waterproof coating treatment or microporous barrier structure is formed by multi-layer co-extrusion process.

9. The production process of an anti-UV aging packaging bag material according to claim 1, characterized in that, In step S1, the amount of a portion of the compatibilizer is 30% to 40% of the total amount of the compatibilizer, and the amount of a portion of the synergistic stabilizing composite additive is 40% to 60% of its total amount; In step S3, the screw speed of the twin-screw extruder is 250–350 rpm.

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