With the increasing demand for FIBC in the international market, my country’s FIBC product exports have further increased. At the same time, the international market has stricter requirements on the quality of FIBC products. Therefore, how to improve the strength of FIBC products is reasonable Material selection, reasonable process ratio, and how to design high-quality FIBCs based on the actual situation of the enterprise under the premise of implementing national standards are important issues faced by FIBC manufacturers. For this reason, this paper proposes a FIBC design Several issues that need to be paid attention to.
Basis and principles
The design of the container bag must strictly implement the GB/T10454-2000 standard to ensure that the packaged export goods are intact in the process of loading, unloading, transportation and storage. The design of FIBC should consider the following four main points, namely safety, storage, practicability, and airtightness.
safety
Mainly refers to the strength of the container bag. In the design, the packaging volume, the weight of the load and the packaging unit (number) should be considered, as well as the distance of the transportation, the number of transportations, and the means of transportation and transportation methods to be used. In GB/T10454-2000, the technical index requirements for the base fabric of the container bag and the sling are strictly stipulated. From the perspective of safety, it is clear that the factory's container bag structure is all bottom hanging structure, and the safety factor must reach 1:6.
Safekeeping
The materials should be selected reasonably according to the user's /H conditions, and the process ratio should be reasonable. For example, the anti-aging ability of plastic materials under sun exposure is a main indicator that determines the quality of FIBCs, and it is also a problem often encountered in the actual use of FIBCs. Therefore, attention should be paid to the use of anti-ultraviolet agents in the production process. And the choice of materials resistant to ultraviolet radiation.
Usability
When designing FIBCs, full consideration should be given to the specific ways and methods of customers using FIBCs, such as lifting, transportation, and the performance of the loaded materials. In addition, it is necessary to consider whether the packaged goods are food, and to ensure that there is no adverse effect on the packaged food.
Tightness
Different materials to be packaged have different sealing requirements. For example, powder materials or toxic materials, and articles that are afraid of being contaminated have very strict requirements on sealing performance; special materials that are prone to moisture or mildew also have special requirements for air tightness, so in the design of the container When bagging, pay attention to the influence of base fabric laminating process and sewing process on sealing performance.
Problems that should be paid attention to
When designing FIBC, we must first clarify the weight of the loaded goods, and determine the volume of FIBC according to the proportion of the packaged materials. It also depends on whether the loaded materials are sharp and hard block materials. If so, the base fabric should be thicker when designing the FIBC, on the contrary, it can be thinner. In the actual design, the base fabric is generally selected as (150-170)G/m2 for the bulk bag with a load of 500kg, the longitudinal and transverse tensile strength of the base fabric is (1470-1700)N/5cm, and the elongation is 20%-35%. ; For container bags with a load of more than 1000kg, the base fabric is generally selected (170-210) G/m2, the longitudinal and transverse tensile strength of the base fabric is (1700-2000) N/5cm, and the elongation is 20%-35%.
Improve monofilament strength
To ensure the strength of the base fabric, the tensile strength of the silk must be increased. The relative strength of the flat yarn should be above 0.4N/tex, and the elongation rate should be 15%-30%. In the actual processing process, the amount of filler masterbatch needs to be strictly controlled, generally around 2%. If too much masterbatch is added or recycled materials are added, the strength of the base fabric will decrease. Therefore, we must strictly control the quality of the raw materials, and select the wire drawing raw materials produced by regular manufacturers with a melt index that meets the national standard.
Check the selection of straps
In the design of FIBC, the selection of sling material is very important. The national standard clearly stipulates a safety factor of 1:6. In the actual design, one must consider the loss of the strength of the sling during the sewing process; second, the hoisting method must be considered. For example, for a container bag with a load of 500kg, the sling is generally selected (50-60) g/m, and the tensile force is (1300 to 1800) N/m; for a container bag with a load of 1000 kg, generally selected (60-75) g/m, and the tensile force is (1800-2000) N/m, the sling must meet the weaving density requirement. In addition, two loops, four loops, etc. can be used to increase the tensile strength when designing the sling.
Add additives to extend the service life
In order to improve the anti-aging ability of the feed container bag under sunlight, a certain amount of anti-purple agent and stabilizer should be added in the flat yarn stretching process. According to the length of the trial period (half a year or 1 year) of the FIBC, determine the addition amount, which is generally between (0.1-3)%. Some companies add anti-aging masterbatch made by mixing stabilizers, anti-purple agents and other additives, and the effect is also very good.
Structural design
When designing the container bag structure, the national standard stipulates that the strength of the waistband is more than twice the strength of the base fabric, but the actual design effect is not good. Due to the inconsistency of the strength of the base fabric and the waistband, the base fabric cracks first. In the design, the waistband and the base fabric should be made of the same strength base fabric material to avoid this problem.
Sewing process design
In addition to the sewing requirements specified in the national standard, the aging resistance of the suture and the effect of the sewing on the tensile strength of the base fabric should also be considered. When packing powdery materials, toxic materials, and materials that are afraid of being contaminated, the sealing problem must be solved first. Therefore, in the actual design, thick threads and thin needles or non-woven fabrics are used to sew together with the base fabric to improve the sealing performance. In addition, when sewing FIBCs, it is required that the stitching strength must be above 18ks polyester thread to ensure that the stitching strength meets the requirements of the national standard.
Inlet and outlet design
The national standard stipulates that the longitudinal and transverse tensile strength of the base fabric at the inlet and outlet is ≥828N/50mm, but in actual calculations, the pressure on the outlet is higher, which can be higher, and the strength of the inlet can be lower, so it is generally used. Laminated base cloth (90-100) m2.
Other factors
In the actual design process, the container bag without the discharge port structure can generally meet the safety factor requirements specified by the national standard. However, the strength of the container bag with a discharge port generally does not meet the standard requirements. This requires that the strength of the bottom opening should be considered in the design. For example, increasing the thickness of the bottom base cloth of the bag, increasing the reinforcing cloth of the material opening, etc. can solve this problem.
In the actual design process, it is necessary to comprehensively consider various indicators, continuously improve process design, strengthen technological innovation, adopt new materials, new processes, and new methods, and seek the best plan in design to ensure design quality.