Core Advantages: PE Square Valve Bags for Agricultural
ProductsMoisture-Proof, Fresh-Keeping and Mildew Prevention
PE material (with a density of 0.91-0.96g/cm³) itself has a water vapor transmission rate of ≤5g/(m²・24h) (at 23℃, 90% RH). Combined with the heat-sealing process, it can isolate external moisture, preventing grains such as rice and flour from mildewing due to moisture absorption.
Some products have a built-in breathable film (such as PE+EVOH composite layer). While being moisture-proof, it allows a small amount of gas exchange (with an oxygen transmission rate of ≤200cc/(m²・24h)), preventing beans and nuts from producing odors due to respiration.
Structural Strength and Stackability
PE Square Valve Bags for Agricultural Products adopts a blend modification of high-pressure low-density PE (LDPE) and linear low-density PE (LLDPE) (with LLDPE accounting for 30%-40%). The tensile strength is ≥18MPa. When 25kg of rice is stacked in 6 layers, the deformation of the bag body is <8%, which is suitable for storage and transportation.
The thickness of the square-bottom heat-sealing area reaches 120-180μm, and the bottom bearing surface is flat. The stability during automatic palletizing is 30% higher than that of round-bottom bags.
Automated Filling and Environmental Design
The valve diameter is 50-100mm, which can be connected to the screw filling machine of the grain processing line. The filling efficiency reaches 60 bags per hour (traditional gunny bags require manual sealing, with an efficiency of only 15 bags per hour).
The material can be recycled and regenerated (recycled materials are used for non-food-grade packaging). Some products add starch-based degradable masterbatches (with an addition amount of 15%-20%), and the degradation rate in the natural environment is ≥40% within 12 months, conforming to the trend of green packaging for agricultural products.
Pest Prevention and Puncture Resistance
The PE film layer blocks the invasion of insect eggs. Combined with insect repellent microcapsules (such as natural pyrethrins) printed on the bag surface, PE Square Valve Bags for Agricultural Products can inhibit storage pests (such as rice weevils and grain borers). The puncture resistance of the film surface is ≥30N, preventing sharp particles such as nuts and beans from piercing the bag body.
Visualization and Convenient Labeling
Transparent PE material allows direct observation of the color and impurity of internal agricultural products. The surface can be gravure printed (with ink adhesion ≥ grade 3), clearly marking information such as origin, net weight, and shelf life, meeting the needs of agricultural product traceability.
Standard Sizes and Load-Bearing Specifications
According to the density of agricultural products (such as wheat with a density of about 0.75g/cm³ and corn with a density of about 0.72g/cm³), common sizes are as follows.
Small packaging (retail) has dimensions of 250×180×350mm, with a load-bearing capacity of 5-10kg, suitable for miscellaneous grains (black rice, red beans) and dried goods (shiitake mushrooms, fungus).
Medium packaging (wholesale) measures 400×300×600mm, bearing 20-25kg, used for rice, flour, and corn.
Bulk packaging is 550×400×800mm in size, with a load-bearing capacity of 30-50kg, applicable to soybeans, peanuts, and rapeseeds.
Extra-large customized bags are 700×500×1000mm, bearing 50-100kg, used for feed raw materials (corn flour, soybean meal) and bulk grains.
Special Design Details for Agricultural Products
Anti-Condensation Treatment
Silica gel desiccants (2-5g per bag) or ventilation holes (2mm in diameter, 4-6 per bag) are added inside the bag to prevent condensation water generated due to temperature differences during cold chain transportation (such as refrigerated vegetable dry).
UV Aging Resistance
Bags stored outdoors are added with UV-531 antioxidants (with an addition amount of 0.3%-0.5%). After 500 hours of xenon lamp aging test, the tensile strength retention rate is ≥80%, suitable for corn and soybeans stacked in the open air.
Anti-Static Improvement (for Dust-Prone Agricultural Products)
When processing flour and starch, semi-conductive PE bags with a surface resistance of 10⁹-10¹¹Ω (added with pentaerythritol ester antistatic agent) can be selected to reduce dust adsorption, complying with the food contact material standard (GB 4806.7-2016).
Application Scenarios and Selection Suggestions
Grains
For rice and flour: choose the 25kg specification (400×300×600mm) with a heat-sealing seam width of 10mm to prevent powder leakage during transportation.
For miscellaneous grains: choose 5kg transparent bags (250×180×350mm) with a one-way exhaust valve to avoid during storage.
Dried Goods and Nuts
For shiitake mushrooms and red dates: select the 10kg specification (300×200×450mm) with a built-in moisture-proof aluminum foil layer (7μm thick) to extend the shelf life to 12 months.
For walnuts and pecans: choose puncture-resistant PE (added with 10% metallocene catalyst) with a puncture strength increased to 45N to prevent sharp shells from piercing the bag body.
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