1-1. The technical indicators of the flat yarn production process are mainly divided into four categories:
1-1-1. It is a physical and chemical modification index, mainly including blending modification, compounding ratio, functional additive ratio, and waste blending ratio.
1-1-2. It is a physical rheological index, mainly including draft ratio, inflation ratio, draft ratio, and retraction ratio.
1-1-3. It is a mechanical performance index, mainly including tensile force, relative breaking force, elongation at break, linear velocity, and linear density deviation.
1-1-4. It is the tolerance size index, mainly including flat wire thickness, flat wire width and so on.
1-1-1. Modified mixing ratio and percentage:
The flat yarn production process is divided into two types according to the film formation method. The tube film and the film are divided according to the cooling method after film formation, air cooling, water cooling and intercooling. According to the drawing heating method, there are hot plates, hot rolls, hot air, press The spindle winding is divided into two parts: concentrated pendulum winding, single spindle torque motor winding, and magnetic torque winding. Some modifiers or functional masterbatch and waste recycled materials are often added to the flat wire raw materials.
1-1-1-1. Mixing ratio, the weight ratio of an added component and the main raw material is called the weight ratio of the mixture.
1-1-1-2. Add percentage, an added group accounts for the weight percentage of each group, which is called the weight percentage.
1-1-2. Rheological traction ratio, inflation ratio, draft ratio, retraction ratio:
1-1-2-1. The traction ratio is the ratio of the extrusion speed of the extruded film to the extrusion speed from the film opening. It is used not only for the flat film but also for the tube film. By controlling the traction ratio, the film is in the traction direction. Slightly oriented. The control of the traction ratio is the only effective means to control the thickness of the extruded film after cooling. Because the die gap of an extruder is basically fixed, the adjustment amount is small. In general, the traction ratio is kept at 4. -8 is appropriate.
1-1-2-2. Inflating ratio, the ratio of the bubble diameter blown out by the tube film to the original die diameter during blow molding, called the inflation ratio. Obviously, the flat film has no blow ratio. From a theoretical point of view The larger the inflation ratio, the better the transverse stretching orientation of the film, the better the tensile strength, but in fact, the production should not be too high, so as not to cause a snake-like swing, the degree of uniformity is reduced, the film thickness is not equal, and wrinkles appear. Pleating, etc. Under normal circumstances, the inflation ratio is controlled between 2.0 and 3.5, and the maximum is not more than 8 digits.
1-1-2-3. Draft ratio, the multiple of the length of the unit length of the split yarn (filament) when the flat yarn is drawn, or described as the draft (two pull) speed and traction (one draw) speed The ratio is the draft ratio. The draft ratio is the most important process index in the production of flat yarn. The draft ratio is also called the draw ratio, the draw ratio. The draw of the flat yarn is a uniaxial stretch below the melting point. The stretching process is an orientation process in order to obtain high strength and other physical and mechanical properties of the flat yarn. In general, the draft ratio is controlled at 4-7 times, and the special requirement of the flat yarn is 11 times that of Kodak.
1-1-2-4. Retraction ratio refers to the ratio of the pulling speed of the flat yarn to the traction speed. From the perspective of the production process, the pulling speed is lower than the pulling speed, and the backing wire is heated twice. Shrinkage, the internal stress of the flat wire is eliminated, and the strong tensile force and excellent elongation are obtained. The retraction ratio, also known as the setting ratio. In general, the retraction ratio is between 0.96 and 0.99.
1-1-3. Flat wire density, relative tensile load, elongation at break:
1-1-3-1. Flat wire density is the mass that characterizes the linear length of a linear object. The greater the linear density, the greater the breaking force. In plastic knitting, the linear density of the flat yarn is a measure of the overall strength of the plastic braid. Basic elements. According to the provisions of Appendix A of GB/T8946 <Plastic woven bag>, use the frame length measuring instrument to go to 100M flat wire, and weigh to the nearest 0.1g.
1-1-3-2. Relative tensile load, also known as relative tensile force, refers to the tensile force of each tex of flat wire. For each flat wire, because of its density and thickness, it is pulled. The breaking force is different. However, the relative tensile load is basically similar. Because the relative tensile load is the physical strength index independent of the width and thickness of the flat yarn. Its size depends on the temperature of the raw material, the draft ratio, the setting, and the cooling. , crystallization and other factors. The national standard specifies the relative breaking force is greater than or equal to 0.32N / tex.
1-1-3-3. Elongation at break is the percentage of the length of the effective marking line (between the two clamps) when the flat yarn is stretched and the length of the initial effective marking line (between the two clamps). Elongation at break is a measure of the ductile toughness (elasticity). It has a large elongation at break. It is characterized by a certain degree of single-elongation when the flat yarn is impact-resistant, and it does not immediately break. Therefore, the elongation at break is large. Under the same breaking force, the number of drop tests may be more. The national standard requires the elongation at break to be 15-30%.
1-1-4. Flat and wide:
1-1-4-1. The width of the flat yarn refers to the width of the split yarn after being drawn, which determines the weaving density of the braid. For plastic woven bags and composite plastic woven bags, three commonly used weaving are recommended in the national standard. Density (diameter density * weft density), ie 36*36, 40*40, 48*48 roots/10cm. These three weaving densities are also applicable to other braids. According to these three weaving densities, the width of the flat yarn is theoretically calculated as : 2.78mm, 2.5mm, 2.08mm. In the process of producing flat yarn, the width of the flat wire should be controlled according to the knitting density required by the customer.
1-1-4-2. The thickness of the flat wire refers to the thickness of the split wire after drawing. The thickness determines the basis weight of the woven fabric. Meanwhile, if the width of the flat wire has been determined, the thickness of the flat wire is the decision of the density of the flat wire. factor.
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