Low-cost high-barrier pesticide packaging bottle and preparation method

Abstract

This invention relates to the field of packaging materials and their preparation, and particularly to a low-cost, high-barrier pesticide packaging bottle and its preparation method. The packaging bottle comprises, from the inside out, an inner layer, an adhesive layer I, a barrier layer, an adhesive layer II, and an outer layer bonded together. The barrier layer is formed by melt blow molding of a barrier material with specific weight components. The inner layer, adhesive layer, and outer layer also have their own constituent components. The invention also includes a method for preparing the packaging bottle, such as steps like raw material melting, co-extrusion blow molding, and finishing treatment. A detailed method for preparing the barrier material is also provided. This application achieves the technical effect of reducing the cost of pesticide packaging bottles and improving their barrier performance.

Description

Technical Field

[0001] This invention relates to the field of packaging materials and their preparation, and in particular to a low-cost, high-barrier pesticide packaging bottle and its preparation method. Background Technology

[0002] In the field of pesticide packaging container technology, the development of packaging has always been a focus of attention. Early on, liquid pesticides were mainly packaged in aluminum and glass bottles, which to some extent met the basic needs of pesticide storage and transportation. Later, with the introduction of the "plastics instead of glass" development strategy, the plastic packaging industry ushered in a period of rapid development. Multi-layer co-extruded blow-molded bottles, with their excellent impermeability and mechanical properties, have gradually become the mainstream product for pesticide packaging, bringing about new changes and driving the progress of the pesticide packaging industry.

[0003] In the manufacture of multilayer co-extruded bottles, a barrier layer is typically incorporated to achieve good barrier performance. Traditionally, ethylene-vinyl alcohol copolymer (EVOH) has been widely used as a barrier layer material due to its excellent resistance to gas and organic solvent permeation. Furthermore, to reduce costs, some technologies explore adding inorganic fillers such as calcium carbonate and talc to the barrier layer.

[0004] However, existing technologies have significant drawbacks. EVOH is expensive, keeping the cost of pesticide packaging bottle materials high. Furthermore, the EVOH molecular chain contains a large number of hydroxyl groups, making it hygroscopic and causing a significant decrease in barrier properties under high humidity. Additionally, the addition of inorganic fillers such as calcium carbonate and talc often leads to a decrease in barrier performance and a reduction in mechanical strength. Summary of the Invention

[0005] This invention solves the problems of high material costs and difficulty in high-value reuse of recycled waste caused by the extensive use of EVOH in the barrier layer of existing pesticide packaging bottles. It proposes a low-cost, high-barrier pesticide packaging bottle and its preparation method. The main method is to introduce recycled PET and EVOH into the barrier layer and add a chain extender, which achieves the effects of reducing costs, maintaining barrier properties and improving moisture resistance.

[0006] To achieve the above objectives, the following technical solution is proposed: A low-cost, high-barrier pesticide packaging bottle comprises, from the inside out, an inner layer, an adhesive layer I, a barrier layer, an adhesive layer II, and an outer layer, which are bonded together sequentially. The barrier layer is formed by melt blow molding of a barrier material, which contains the following components in parts by weight: 40-50 parts EVOH, 50-60 parts recycled PET, 0.5-1.5 parts epoxy chain extender, 2-4 parts talc, and 0.2-0.5 parts antioxidant.

[0007] By adopting the above technical solution, a reactive blend of recycled PET and EVOH is introduced into the barrier layer, and an epoxy chain extender is added to improve compatibility, forming an asymmetric morphological structure of "EVOH continuous phase + PET dispersed phase". This significantly reduces material costs, with barrier layer material costs reduced by more than 40%, and overall pesticide packaging bottle manufacturing costs reduced by 12-18%. It maintains good barrier performance, with xylene permeability controlled below 0.13% (50℃, 14 days), comparable to pure EVOH. It improves moisture resistance, making the barrier performance of pesticide packaging bottles more stable in high humidity environments. It meets mechanical performance requirements, with the tensile modulus of the blend increasing by approximately 15%, and the resulting pesticide packaging bottles do not break after a 1.5m drop after being frozen at -18℃ for 24 hours. It achieves resource recycling, with approximately 500kg of recycled PET flakes consumed per ton of barrier material, meeting green environmental protection requirements.

[0008] Preferably, the ethylene molar content in the EVOH is 32-38%.

[0009] By adopting the above technical solution, when the ethylene molar content in EVOH is controlled at 32-38%, it can retain its excellent resistance to organic solvents and oxygen barrier properties, while also moderately reducing the hydroxyl density to weaken hygroscopicity. This maintains high barrier properties while improving its long-term stability in humid environments and its processing compatibility with recycled PET.

[0010] Preferably, the intrinsic viscosity of the recycled PET is 0.72-0.80 dL / g.

[0011] By adopting the above technical solution, the intrinsic viscosity of recycled PET is controlled at 0.72-0.80 dL / g, which allows the PET melt viscosity to be within the same order of magnitude as the EVOH melt viscosity. This results in better compatibility during twin-screw co-extrusion, reducing the likelihood of incomplete encapsulation or interlayer slippage. 0.72-0.80 dL / g corresponds to a number-average molecular weight (Mn) of approximately 45,000-60,000 for PET. At this level, the PET molecular chains are long enough to effectively extend with epoxy chain extenders, forming covalent bonds at the EVOH-PET interface, significantly improving interfacial bonding strength. Recycled PET comes from diverse sources, and its molecular weight decreases after multiple thermal histories. Limiting IV to ≥0.72 dL / g means that the selected recycled material maintains a high degree of molecular chain integrity. Even after secondary melting (approximately 255-260℃) during subsequent co-extrusion with EVOH, the final intrinsic viscosity can still be maintained above 0.65 dL / g, preventing excessive degradation.

[0012] Preferably, the epoxy chain extender is a styrene-glycidyl acrylate copolymer.

[0013] By adopting the above technical solution, since the epoxy chain extender is a styrene-glycidyl acrylate copolymer, the epoxy groups it contains can undergo a ring-opening reaction with the carboxyl / hydroxyl groups at the end of the recycled PET. At the same time, the styrene segments have good compatibility with EVOH, thereby forming a "chemical bridge" at the interface between r-PET and EVOH to enhance the binding force and inhibit the aggregation of the dispersed phase. Therefore, under the premise of reducing the amount of EVOH by 50%, the xylene penetration rate can still be controlled below 0.13% and the drop pass rate can be maintained at 100%.

[0014] Preferably, the talc powder is 1250 mesh and has been surface-treated with a silane coupling agent.

[0015] By adopting the above technical solution, the surface polarity of talc powder can be reduced and its interfacial compatibility with EVOH and PET matrix can be enhanced after surface treatment with silane coupling agent. As a result, it can be uniformly dispersed in the barrier layer at a high fineness of 1250 mesh, significantly reducing agglomeration and microporous defects. This improves the barrier performance of pesticide packaging bottles against oxygen, water vapor and organic solvents, while also improving the tensile strength and drop impact resistance of the blend.

[0016] Preferably, the antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a weight ratio of 1:1.

[0017] By adopting the above technical solution, antioxidant 1010 (hindered phenolic primary antioxidant) can capture free radicals to terminate the oxidation chain reaction, while antioxidant 168 (phosphite auxiliary antioxidant) can decompose hydroperoxides to eliminate the source of oxidation. When the two are compounded in a 1:1 ratio, they produce a synergistic effect in the high-temperature processing (255–260℃) of the r-PET / EVOH blend system. Therefore, the thermal oxidative degradation of the blend can be significantly inhibited, the molecular chain integrity can be protected, and the high tensile strength and low permeability of the barrier layer can be maintained.

[0018] Preferably, the inner layer comprises HDPE and LLDPE, the adhesive layer I and adhesive layer II comprise maleic anhydride modified polyethylene, and the outer layer comprises HDPE, color masterbatch, nano zinc oxide, and polyimide emulsion.

[0019] By adopting the above technical solution, the inner layer, made of HDPE and LLDPE blend, gives the matrix excellent toughness and chemical resistance. The adhesive layer, made of maleic anhydride modified polyethylene, provides strong interfacial bonding with the polar barrier layer and the non-polar layer. The outer layer, made of HDPE, color masterbatch, nano zinc oxide and polyimide emulsion, achieves UV resistance, antibacterial and heat aging resistance. Thus, the pesticide packaging bottle, while maintaining high barrier properties, significantly improves interlayer bonding strength, environmental weather resistance and impact toughness.

[0020] A method for preparing a low-cost, high-barrier pesticide packaging bottle, comprising the following steps: S1. Raw material melting: Prepare materials according to the formula of inner layer, adhesive layer I, barrier layer, adhesive layer II and outer layer materials, and add each layer material to the corresponding extruder for melting; S2, Co-extrusion blow molding: The material tube is extruded through multiple die heads and introduced into the left and right molds that work at the same time. The material tube is stretched by inserting air to form a semi-finished preform, which is then cooled and shaped. S3. Finishing process: Trim and finish the semi-finished blank to obtain the finished product.

[0021] By adopting the above technical solution, the preparation of low-cost, high-barrier pesticide packaging bottles can be successfully completed. After melting the materials of each layer, the bottles are co-extruded, blow-molded, and finished to obtain finished pesticide packaging bottles that meet the requirements. Moreover, because the barrier layer of the packaging bottle uses a barrier material containing specific weight components, it has the effects of significantly reducing material costs, maintaining good barrier performance, improving moisture resistance, meeting mechanical performance requirements, and realizing resource recycling.

[0022] Preferably, the barrier material is prepared by the following method: (1) The recycled PET bottle flakes are washed, crushed to 3-5mm, extruded, granulated and dried to obtain r-PET granules; (2) Weigh EVOH, r-PET, epoxy chain extender, talc and antioxidant according to the ratio, and premix them in a high-speed mixer for 3-5 minutes; (3) Add the mixture to a twin-screw extruder for melt blending, extrusion and granulation. The extrusion temperature is: 230-240℃ for the feed section, 245-250℃ for the compression section, 255-260℃ for the metering section, and 250-255℃ for the die head. The screw speed is 250-300r / min, and the residence time is 2-4min. The barrier material is then obtained.

[0023] By adopting the above technical solution, recycled PET bottle flakes are washed, crushed, granulated, and dried to obtain r-PET granules, which can realize resource recycling. Weighing each component according to the formula and premixing it in a high-speed mixer can ensure that the components are fully mixed. Adding the mixture to a twin-screw extruder and melting, extruding, and granulating it under specific temperature, screw speed, and residence time can better integrate the components and form a barrier material with an asymmetric morphological structure of "EVOH continuous phase + PET dispersed phase". This ensures that pesticide packaging bottles have good barrier performance, improved moisture resistance, and meet mechanical property requirements, while significantly reducing material costs.

[0024] Preferably, the barrier layer accounts for 7-15% of the total wall thickness of the pesticide packaging bottle, and the mass ratio of EVOH to recycled PET in the barrier layer is 0.8:1 to 1:1.2.

[0025] By adopting the above technical solution, since the barrier layer accounts for 7-15% of the total wall thickness of the pesticide packaging bottle, it can ensure sufficient barrier path length to effectively delay solvent penetration. At the same time, this thickness range, combined with the mass ratio of EVOH to recycled PET in the barrier layer of 0.8:1 to 1:1.2, enables EVOH to form a continuous barrier phase and PET as a dispersed reinforcing phase. Thus, while reducing EVOH usage by about 50% and material costs by more than 44%, it maintains excellent performance of xylene penetration rate ≤0.13% and no breakage after a 1.5m drop.

[0026] The beneficial effects of this invention are: 1. Significantly reduced material costs: Replacing some EVOH with recycled PET reduces the cost of barrier layer materials by more than 40%, and the overall manufacturing cost of pesticide packaging bottles is reduced by 12-18%; 2. Excellent barrier properties: The continuous EVOH phase ensures excellent resistance to xylene and gasoline penetration, and the xylene penetration rate can be controlled below 0.13% (50℃, 14 days), which is comparable to pure EVOH; 3. Improved moisture resistance: The introduction of recycled PET reduces the polar hygroscopicity of the barrier layer, making the barrier performance of pesticide packaging bottles more stable in high humidity environments. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to the embodiments. Unless otherwise specified, the raw materials used in the following embodiments are all commercially available products.

[0028] The raw materials used and their sources are as follows: EVOH: Ethylene molar content 38%, model EV105, Kuraray Corporation, Japan.

[0029] Recycled PET (r-PET): Recycled pesticide bottles are cleaned, crushed, and granulated. The intrinsic viscosity is 0.75 dL / L. It is produced in-house.

[0030] Epoxy chain extender: ADR-4370S, BASF (China) Co., Ltd.

[0031] Talc powder: 1250 mesh, whiteness 92%, surface treated with 1% silane coupling agent KH550, Guangxi Longguang Talc Development Co., Ltd.

[0032] Antioxidant 1010, Antioxidant 168: BASF (China) Co., Ltd.

[0033] HDPE: 5502, Daelim, South Korea.

[0034] LLDPE: 1018, DSM Netherlands.

[0035] Adhesive: Maleic anhydride modified polyethylene, model 18302N, Suzhou Saiya Plastics Co., Ltd.

[0036] Color masterbatch: Type 6711-30 anti-aging white masterbatch, Zibo Dingchen Plastics Technology Co., Ltd.

[0037] Nano zinc oxide: 20nm particle size, Jiangsu Tianxing New Materials Co., Ltd.

[0038] Polyimide emulsion: PY1002 type, Suzhou Jingyu Optoelectronic Technology Co., Ltd.

[0039] All other additives are commercially available general-purpose types.

[0040] The preparation of barrier materials is as follows: Preparation Example 1 (corresponding to Example 1): (1) The recycled PET bottle flakes are washed, crushed to 3-5 mm, granulated at 260°C by a single screw extruder, and then dried at 120°C for 4 h to obtain r-PET granules with an intrinsic viscosity of 0.75 dL / L.

[0041] (2) Weigh 45kg of EVOH, 55kg of r-PET, 1.0kg of ADR-4370S, 3kg of talc, 0.2kg of antioxidant 1010 and 0.2kg of antioxidant 168, and premix them in a high-speed mixer at 800r / min for 5min.

[0042] (3) The mixture was added to a twin-screw extruder for melt blending and extrusion granulation. The temperatures of each zone of the twin-screw extruder were: zone 1 235℃, zone 2 245℃, zone 3 255℃, zone 4 260℃, zone 5 260℃, and die head 255℃. The screw speed was 280 r / min, and the residence time was 3 min. The extrudate was water-cooled, pelletized, and dried at 105℃ for 3 h to obtain barrier material-1.

[0043] Preparation Example 2 (corresponding to Example 2): The difference from Preparation Example 1 is that: EVOH 50kg, r-PET 50kg, ADR-4370S 0.8kg, talc 4kg, antioxidant 1010 0.15kg, and antioxidant 168 0.15kg. The rest are the same.

[0044] Preparation Example 3 (corresponding to Example 3): The difference from Preparation Example 1 is that: EVOH 40kg, r-PET 60kg, ADR-4370S 1.2kg, talc 2kg, antioxidant 1010 0.25kg, and antioxidant 168 0.25kg. The rest are the same.

[0045] Comparative Preparation Example 1 (Comparative Example 1): The difference from Preparation Example 1 is that: no r-PET is added, the amount of EVOH is 100 kg, no epoxy chain extender is added, and 2 kg of talc is used. That is, a pure EVOH barrier material is produced.

[0046] Comparative Preparation Example 2 (Comparative Example 2): The difference from Preparation Example 1 is that r-PET was not treated with epoxy chain extender (i.e., ADR-4370S was not added), while the other components were the same.

[0047] Comparative Preparation Example 3 (Comparative Example 3): The difference from Preparation Example 1 is that ordinary calcium carbonate (1250 mesh, untreated) is used instead of talc powder, and no epoxy chain extender is added. Example 1

[0048] A low-cost, high-barrier pesticide packaging bottle comprises an inner layer, an adhesive layer I, a barrier layer, an adhesive layer II, and an outer layer, which are bonded together sequentially from the inside out. The thickness ratio of each layer is inner layer: adhesive layer I: barrier layer: adhesive layer II: outer layer = 5:1:1:1:6, and the total wall thickness of the packaging bottle is approximately 0.8 mm.

[0049] The inner layer raw materials are as follows by weight: 80 parts HDPE, 20 parts linear low-density polyethylene (LLDPE), 5 parts toughening agent (maleic anhydride grafted POE), and 3 parts nano-calcium carbonate (activated).

[0050] The raw materials for adhesive layer I and adhesive layer II are as follows by weight: 30 parts adhesive (maleic anhydride modified polyethylene), 40 parts HDPE, and 30 parts LLDPE.

[0051] The barrier layer is made of the barrier material-1 prepared in Preparation Example 1.

[0052] The outer layer raw materials are as follows by weight: 90 parts HDPE, 5 parts color masterbatch, 3 parts nano zinc oxide, and 2 parts polyimide emulsion.

[0053] A method for preparing a low-cost, high-barrier pesticide packaging bottle, comprising the following steps: Example 1: S1. Raw material melting: The inner layer material is melted at 185°C, the adhesive layer material is melted at 165°C, the barrier layer material is melted at 195°C, and the outer layer material is melted at 185°C. S2. Co-extrusion blow molding: The inner layer, adhesive layer I, barrier layer, adhesive layer II, and outer layer materials are fed into a five-layer co-extrusion die (die temperature 205℃) through a screw extruder (screw speeds are: inner layer 60r / min, adhesive layer I 40r / min, barrier layer 30r / min, adhesive layer II 40r / min, outer layer 70r / min respectively), and extruded into a composite material tube; the material tube is then introduced into a blow molding die (die temperature 25℃), air is blown in through the insert rod (air pressure 0.7MPa), and cooled and shaped for 20s to obtain a semi-finished preform; S3. Finishing: Trim and finish the edges to obtain the finished pesticide bottle, which is recorded as Sample 1. Example 2

[0054] The difference between this embodiment and Example 1 is that the barrier layer uses the barrier material-2 prepared in Example 2. Everything else is the same, resulting in Sample 2. Example 3

[0055] The difference between this embodiment and Example 1 is that the barrier layer uses the barrier material-3 prepared in Example 3. Everything else is the same, resulting in Sample 3.

[0056] Comparative Example 1: The difference between this embodiment and Example 1 is that the barrier layer uses the pure EVOH barrier material prepared in Comparative Preparation Example 1. Everything else is the same, resulting in Comparative Sample 1.

[0057] Comparative Example 2: The difference between this embodiment and Example 1 is that the barrier layer uses the r-PET / EVOH blend material without epoxy chain extender prepared in Comparative Preparation Example 2. Everything else is the same, resulting in Comparative Sample 2.

[0058] Comparative Example 3: The difference between this embodiment and Example 1 is that the barrier layer uses the calcium carbonate-filled EVOH material prepared in Comparative Preparation Example 3. Everything else is the same, resulting in Comparative Sample 3.

[0059] The performance of samples 1-3 and control samples 1-3 was tested according to the following method.

[0060] The specific performance test items are as follows: 1. Xylene permeability: According to ASTM D2684M-2015, fill the pesticide bottle with xylene, seal it, place it at 50℃ for 14 days, weigh it and calculate the percentage of weight loss.

[0061] 2. Oxygen transmission rate: Refer to GB / T 1038-2000, 25℃, 50%RH, test the oxygen transmission rate of the bottle wall (cut sheet).

[0062] 3. Water vapor transmission rate: Refer to GB / T 1037-1988, 38℃, 90%RH.

[0063] 4. Tensile strength: According to ASTM D638-2003, samples were taken from the bottle body at a tensile rate of 50 mm / min.

[0064] 5. Drop test: Fill pesticide bottles with water, freeze them at -18℃ for 24 hours, and then drop them freely from a height of 1.5m onto a cement ground. Observe whether they break. Record the number of broken bottles in each group of 10 bottles.

[0065] 6. Unit cost estimation: The material cost reduction rate is calculated based on the barrier layer material cost (yuan / kg) and the barrier layer usage of 3g per bottle.

[0066] Results Analysis: The xylene permeability and oxygen permeability of samples 1-3 in the embodiments of this invention are comparable to or even better than those of pure EVOH in comparative sample 1. The water vapor permeability is significantly reduced, indicating that the introduction of r-PET did not impair the barrier performance; on the contrary, the reduced polarity improved moisture resistance. The tensile strength is close to that of pure EVOH, and all samples passed the drop test. In contrast, the barrier performance of comparative sample 2 (without chain extender) and comparative sample 3 (with calcium carbonate substitution) is significantly reduced, resulting in severe drop damage. In terms of cost, the barrier layer material cost of the embodiments of this invention is 44-49% lower than that of pure EVOH, achieving a balance between low cost and high performance.

[0067] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A low-cost, high-barrier pesticide packaging bottle, comprising an inner layer, an adhesive layer I, a barrier layer, an adhesive layer II, and an outer layer bonded sequentially from the inside out, characterized in that, The barrier layer is formed by melt blow molding of a barrier material, which contains the following components in parts by weight: 40-50 parts EVOH, 50-60 parts recycled PET, 0.5-1.5 parts epoxy chain extender, 2-4 parts talc, and 0.2-0.5 parts antioxidant.

2. The low-cost, high-barrier pesticide packaging bottle according to claim 1, characterized in that, The ethylene molar content in the EVOH is 32-38%.

3. The low-cost, high-barrier pesticide packaging bottle according to claim 1, characterized in that, The intrinsic viscosity of the recycled PET is 0.72-0.80 dL / g.

4. A low-cost, high-barrier pesticide packaging bottle according to claim 1, characterized in that, The epoxy chain extender is a styrene-glycidyl acrylate copolymer.

5. A low-cost, high-barrier pesticide packaging bottle according to claim 1, characterized in that, The talc powder is 1250 mesh and has been surface-treated with a silane coupling agent.

6. A low-cost, high-barrier pesticide packaging bottle according to claim 1, characterized in that, The antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a weight ratio of 1:

1.

7. A low-cost, high-barrier pesticide packaging bottle according to claim 1, characterized in that, The inner layer comprises HDPE and LLDPE, the adhesive layer I and adhesive layer II comprise maleic anhydride modified polyethylene, and the outer layer comprises HDPE, color masterbatch, nano zinc oxide and polyimide emulsion.

8. A method for preparing a low-cost, high-barrier pesticide packaging bottle, comprising preparing the low-cost, high-barrier pesticide packaging bottle according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Raw material melting: Prepare materials according to the formula of inner layer, adhesive layer I, barrier layer, adhesive layer II and outer layer materials, and add each layer material to the corresponding extruder for melting; S2, Co-extrusion blow molding: The material tube is extruded through multiple die heads and introduced into the left and right molds that work at the same time. The material tube is stretched by inserting air to form a semi-finished preform, which is then cooled and shaped. S3. Finishing process: Trim and finish the semi-finished blank to obtain the finished product.

9. A method for preparing a low-cost, high-barrier pesticide packaging bottle according to claim 8, characterized in that, The barrier material is prepared by the following method: (1) The recycled PET bottle flakes are washed, crushed to 3-5mm, extruded, granulated and dried to obtain r-PET granules; (2) Weigh EVOH, r-PET, epoxy chain extender, talc and antioxidant according to the ratio, and premix them in a high-speed mixer for 3-5 minutes; (3) Add the mixture to a twin-screw extruder for melt blending, extrusion and granulation. The extrusion temperature is: 230-240℃ for the feed section, 245-250℃ for the compression section, 255-260℃ for the metering section, and 250-255℃ for the die head. The screw speed is 250-300r / min, and the residence time is 2-4min. The barrier material is then obtained.

10. The method for preparing a low-cost, high-barrier pesticide packaging bottle according to claim 1, characterized in that, The barrier layer accounts for 7-15% of the total wall thickness of the pesticide packaging bottle, and the mass ratio of EVOH to recycled PET in the barrier layer is 0.8:1 to 1:1.2.