Several problems in the design of container bags

With the increasing demand for container bags in the international market, the export of container bags in China is further increasing. At the same time, the quality requirements of container bags in the international market are becoming more and more strict. Therefore, how to improve the strength of container bags, reasonable material selection, reasonable process ratio, and how to design high-quality container bags in combination with the actual situation of enterprises under the premise of implementing national standards, It is an important subject for container bag manufacturers. Therefore, this paper puts forward some problems that should be paid attention to in container bag design

The design of container bags should strictly comply with GB / t10454-2000 to ensure that the packaged export goods are intact during loading, unloading, transportation and storage. The following four key points should be considered in the design of container bags, namely safety, storage, usability and sealing.

Safety mainly refers to the strength of bagging. In the design, we should consider the packaging volume, the weight of the contents, the number of packaging units, the distance of transportation, the number of handling times, the means of transportation and the method of transportation. In GB / t10454-2000, the technical index requirements of container bag base cloth and sling are strictly stipulated. From the safety point of view, it is clear that the container bag structure of the factory is the bottom lifting structure, and the safety factor must reach 1:6.

Storage should be based on the user's make / h conditions, reasonable selection of materials, reasonable process ratio. For example, the ageing resistance of plastic materials under sunlight exposure is a major indicator of the quality of container bags. It is also a common problem encountered in the actual use of container bags. Therefore, the use of UV resistant agents and the selection of UV resistant materials should be paid attention in the production process.

Usability in the design of container bags, the specific ways and methods of using container bags by customers should be fully considered, such as lifting, transportation mode and the performance of loaded materials. In addition, we should also consider whether the packaged goods are food, and ensure that there is no adverse effect on the packaged food.

Different packaging materials have different sealing requirements. For example, powder or toxic materials, and materials that are afraid of pollution have very strict requirements on sealing performance. Special materials that are easily affected by damp or mildew also have special requirements on air tightness. Therefore, when designing container bags, attention should be paid to the influence of base cloth laminating process and sewing process on sealing performance.

In the design of container bags, first of all, the weight of the loaded goods should be determined, and the volume of container bags should be determined according to the specific gravity of the materials. It also depends on whether the loading material is sharp and hard block material. If so, when designing container bags, the base material should be thicker. On the contrary, it can be thinner. In practical design, the base cloth of 500 kg container bag is (150-170) g / m2, the longitudinal and transverse tensile strength of the base cloth is (1470-1700) n / 5cm, and the elongation is 20% - 35%; the base cloth of 1000 kg container bag is (170-210) g / m2, the longitudinal and transverse tensile strength of the base cloth is (1700-2000) n / 5cm, and the elongation is 20% - 35%.

To improve the strength of monofilament, the tensile strength of monofilament must be increased to ensure the strength of base cloth. The relative strength of the flat yarn should be above 0.4n/tex and the elongation should be 15% - 30%. In the actual processing process, it is necessary to strictly control the amount of filling masterbatch, generally about 2%. If too much masterbatch is added or recycled material is added, the strength of base cloth will be reduced. Therefore, the quality of raw materials should be strictly controlled, and the raw materials produced by regular manufacturers with melt index up to the national standard should be selected.

In the design of container bag, it is very important to select suitable sling materials. The safety factor of 1:6 is specified in the national standard. In the actual design, one should consider the loss of sling strength in the sewing process; the other should consider the lifting method. For example, for a 500kg container bag, the sling is generally (50-60) g / m with a pull force of (1300-1800) n / M; for a 1000kg container bag, the sling is generally (60-75) g / m with a pull force of (1800-2000) n / m, which requires that the sling must meet the weaving density requirements. In addition, two or four rings can be used to increase the tensile strength.

Adding auxiliaries and prolonging the service life, in order to improve the aging resistance of feed bags in sunlight, a certain amount of anti violet agents and stabilizers should be added to the flat wire drawing process. According to the service life of the container bag (half a year or one year), the filling amount is generally between (0.1-3)%. Some enterprises add anti aging masterbatch mixed with stabilizer, anti violet agent and other auxiliaries, and the effect is very good.

When designing the container bag structure, the national standard stipulates that the strength of the waist hoop is more than twice that of the base cloth, but the actual design effect is not good. Because the strength of the base cloth and the waist hoop is not consistent, the base cloth cracks first. In the design, the same strength base material is used for waist hoop and base cloth to avoid this problem.

In addition to the sewing requirements specified in the national standard, the aging resistance of the suture and the influence of the needle on the tensile strength of the base cloth should also be considered in the sewing process design. When packaging powder, toxic and contaminated materials, the first thing to do is to solve the sealing problem. Therefore, in the actual design, thick thread and fine needle or non-woven fabric are used to sew together with the base cloth to improve the sealing performance. In addition, when sewing the container bag, polyester thread with the strength of more than 18ks is required to ensure that the sewing strength meets the requirements of the national standard.

According to the national standard for the design of import and export materials, the longitudinal and transverse tensile strength of the base cloth at the import and export materials is greater than or equal to 828n / 50mm. However, in practice, due to the greater pressure on the discharge outlet, it can be higher and the strength of the feed outlet can be lower. Generally, the composite film base cloth (90-100) m2 is selected.

Other factors in the actual design process, the container bag without outlet structure can generally meet the safety factor requirements of national standards. However, the strength of the container bag with discharge port can not meet the standard requirements, so it is necessary to consider increasing the strength of the bottom opening in the design, such as increasing the thickness of the base cloth at the bottom of the bag and increasing the reinforcement cloth at the discharge port, which can solve this problem.

In the actual design process, it is necessary to comprehensively consider various indicators, constantly improve the process design, strengthen technological innovation, adopt new materials, new processes and new methods, and seek a better scheme in the design to ensure the design quality.

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