1-1. Flat yarn production process technology indicators are mainly divided into four categories:
1-1-1. It is an indicator of physical and chemical modification, mainly including blending modification, compounding ratio, adding ratio of functional additive, blending ratio of used and recycled materials.
1-1-2. Is a physical rheological index, the main draft ratio, blow ratio, draw ratio, shrinkage ratio.
1-1-3. Is a mechanical performance index, the main pull-off force, relative tensile breaking force, elongation at break, linear velocity, linear density deviation.
1-1-4. Is the tolerance size index, mainly flat wire thickness, flat wire width and so on.
1-1-1. Modified Blend Ratio and Percentage:
There are two types of film production methods, film and film, film and film, according to the film cooling method, air cooling, water cooling and intercooling, according to the draft heating method has hot plate, hot roll, hot air, press Spindle winding forming divided, concentrated cycloid winding, single spindle torque motor winding, magnetic torque winding. Flat material often add some modifiers or functional masterbatch and waste recycling materials, can use two indicators.
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. Adding percentages, the percentage of weight of an added group to the total weight of each group, and adding weight percentage.
1-1-2. Rheological traction ratio, blow ratio, draw ratio, retraction ratio:
1-1-2-1. The traction ratio is the ratio of the extruding speed of the extruded film to the extruding speed from the film port. 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. Slight orientation effect. Control of 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, under normal circumstances, the traction ratio is maintained at 4 -8 is appropriate.
1-1-2-2. Blow-up ratio, the ratio of the diameter of the film bubble blown from the tube film to the diameter of the original die when it is blown, called the blow-up ratio. Obviously there is no blow-up ratio problem for the flat film. Theoretically The higher the blow-up ratio, the better the film's transverse stretching and orientation effect and the better the tensile strength, but in fact it cannot be too high in production so as not to cause the serpentine oscillation, the uniformity decreases, the film thickness varies, and wrinkling occurs. Pleat and so on. Under normal circumstances, the blow-up ratio is controlled between 2.0-3.5, the maximum is not more than 8 should.
1-1-2-3. Drafting ratio, the length multiple of the split wire (bulk) per unit length when drawn, or it can be described as draft (two pull) speed and traction (one pull) speed. The ratio is the draft ratio. The draft ratio is the most important process index in flat yarn production. The draft ratio is also called draw ratio, draw ratio. Stretching of flat yarn is one-way stretching performed below the melting point temperature. The stretching process is an orientation process so that the flat yarn obtains high strength and other physical and mechanical properties. In general, the draft ratio is controlled at 4-7 times, and the special flat yarn needs to be 11 times larger than Kodak.
1-1-2-4. Retraction ratio, refers to the ratio of pull-out speed and pull-out speed of the flat wire. From the point of view of the production process, pull-out speed is lower than the pull-in speed, and the secondary heating of the side wire is set to a back Shrinkage, so that the stress within the flat wire to eliminate, to obtain a strong tensile force and excellent elongation. Retraction ratio, also known as the setting ratio. Under normal circumstances, the retraction ratio is between 0.96-0.99
1-1-3. Flat yarn density, relative tensile load, elongation at break:
1-1-3-1. The density of flat yarns is the mass per unit length of a linear object. The greater the linear density, the greater the breaking force. In plastic weaving, the linear density of a flat yarn is a measure of the overall strength of a plastic braid. Basic elements. According to GB/T8946 <plastic woven bag> in the provisions of Appendix A, with a yarn frame length meter to 100M flat wire, weighing accurate to 0.1 grams.
1-1-3-2. Relative tensile load, also known as relative tensile breaking force, refers to the tensile breaking force per flat yarn of tex. For each flat yarn, its density and thickness are different, and therefore pulls. Breaking force is different, but the relative tensile load size tends to be similar. Because the relative tensile load is an indicator of the physical strength independent of the width and thickness of the tape. Its size depends on the temperature of the raw material, draw ratio, shaping, cooling , Crystallization and other factors. The national standard specifies the relative breaking force greater than or equal to 0.32N/tex.
1-1-3-3. Elongation at break refers to the percentage increase in the length of the active reticle portion (between the two grips) when the flat yarn is stretched and the length of the initial effective reticle portion (between the two grippers). Elongation at break is a measure of the toughness (elasticity) of a flat yarn. It has a large elongation at break, and it has a certain unisexual elongation when it is used for impact resistance. It does not immediately break. Therefore, the elongation at break is large. Under the conditions of the same breaking force, the number of drop tests may be more. The national standard requires the elongation at break of 15-30%.
1-1-4. Flat width and thickness:
1-1-4-1. Width of flat yarn refers to the width of divided yarn after drafting. It determines the braiding density of knitted fabrics. For plastic woven bags and composite plastic woven bags, three kinds of common weaving are recommended in the national standard. Density (Radial Density* Weft Density), ie 36*36, 40*40, 48*48 roots/ 10cm. These three kinds of weaving densities are also applicable to other knits. According to these three weaving densities, the width of flat yarns is theoretically calculated as : 2.78mm, 2.5mm, 2.08mm. The width of the flat yarn is controlled according to the weaving density required by the customer during the production of the flat yarn.
1-1-4-2. Flat wire thickness refers to the thickness of the split wire after drawing. The thickness determines the basis weight of the woven cloth. At the same time, if the width of the flat wire has been determined, the thickness of the flat wire is determined by the density of the flat wire. factor.
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