Processing Technology of Flame Retardant Polyester Stretch Textured Yarn for Automobile Decorative Fabric

Abstract: The changing rules of various physical properties of flame retardant polyester false twist textured yarn (DTY) under different false twist deformation processing routes were discussed. The results showed that the tensile strength, elongation at break, crimp shrinkage and crimp stability of flame retardant polyester DTY were lower than those of conventional polyester DTY of the same specification; The main technological parameter affecting crimp shrinkage and crimp stability is deformation temperature; The tensile strength, elongation at break, crimp shrinkage and crimp stability of flame-retardant fibers can be greatly improved by changing the process route and adopting the S+Z stranding process route to meet the requirements of different styles of automotive decorative fabrics.

Fires caused by textile fires continue to occur, causing heavy losses of life and property. For this reason, various regulations have been formulated around the world, which put forward requirements for flame retardancy of textiles [1]. Our country also pays more and more attention to public safety and health, and the use of flame retardant materials is more and more extensive, especially the application of permanent flame retardant decorative fabrics. Different fabrics with different uses and styles have different requirements on the physical properties of flame retardant fibers, such as size, strength, elongation and crimp elasticity. This test focuses on the influence of processing route and conditions of stretch textured yarn (DTY) on the physical properties of 333 dtex/96 f flame retardant polyester DTY for automotive decorative fabrics.

01

test

1.1 Raw materials

In this test, environment-friendly permanent flame-retardant polyester pre oriented yarn (POY) is used, with the fiber size of 267.6 dtex, breaking strength of 2.05 cN/dtex and elongation at break of 132.47%.

1.2 Main production equipment and testing instruments

FK6HY-1000V texturing machine, YG086 yarn length measuring machine, YG023B - Ⅱ automatic single yarn strength machine, YG368 automatic filament crimp rate tester, thermostatic water tank.

1.3 Process flow of texturing

333 dtex/96 f flame-retardant polyester DTY was produced on FK6HY-1000V texturing machine. The changing rules of various physical properties of flame-retardant polyester DTY under different false twist deformation process routes and process conditions were discussed.

1.4 Test conditions

In order to make the test results comparable, only one process parameter is adjusted for each test in turn, and other process parameters are kept unchanged. All test data are obtained through instrument test under the same conditions.

02

Results and discussion

2.1 Process route 1

2.1.1 Production speed

Table 1 shows that with the increase of production speed, the tensile strength and elongation at break of flame retardant polyester DTY decrease, the crimp shrinkage and crimp stability decrease, and the boiling water shrinkage increases. This is because with the increase of production speed, the retention time of fibers in the hot box is shortened, the heat conduction is weakened, the activation energy of molecular chains is reduced, the plastic deformation is reduced, and the crystallization rate is reduced. At the same time, due to the increase of production speed, the upper and lower tensions of the false twister become larger, and the stretching becomes larger. When the production speed reaches a certain level, because the tension is too high, the single fiber will break, producing wool, so the tensile strength and elongation at break will decrease. The production speed should be selected within a reasonable range, and the test results should be between 550 and 650 m/min.

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2.1.2 Tensile ratio

It can be seen from Table 2 that with the increase of drawing ratio, the tensile strength of flame retardant polyester DTY first increases and then decreases, the elongation at break decreases, the crimp shrinkage and crimp stability slightly increase, and the boiling water shrinkage slightly decreases. This is because with the increase of the drawing ratio, the up and down tension of the false twister becomes larger. When it reaches a certain level, it will cause some monofilaments to break and produce hairiness, resulting in a decrease in tensile strength and elongation at break. At the same time, due to the increase of drawing ratio, the molecular chain orientation degree increases, the twist transmission is more sufficient, the plastic deformation amount increases, and the crystallinity increases.

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2.1.3 D/Y ratio

It can be seen from Table 3 that with the increase of D/Y ratio, the tensile strength, crimp shrinkage and crimp stability of flame retardant DTY have little change, the elongation at break has increased, and the boiling water shrinkage has decreased. This is because with the increase of D/Y ratio, the twist applied to the silk yarn increases, the upper tension of the false twister becomes larger, and the lower tension becomes smaller, so it is not easy to produce single filament fracture; The plastic deformation of silk thread in the hot box is increased, and the crystallinity is improved.

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2.1.4 Temperature of hot box

2.1.4.1 Temperature T1 of the first hot box

It can be seen from Table 4 that with the increase of T1, the tensile strength, elongation at break, crimp shrinkage, crimp stability and boiling water shrinkage of flame retardant polyester DTY increase slightly, while the boiling water shrinkage decreases. This is because with the increase of T1, the fiber is heated more fully, the mobility of the polymer chain is enhanced, while the internal stress is reduced, the fiber plasticity is increased, and the fiber is easier to deform and more fully deformed under the twisting force.

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2.1.4.2 Temperature T2 of the second hot box

It can be seen from Table 5 that when the heating switch of the second hot box is turned off and T2 is at normal temperature and 150 ℃, the elongation at break of the flame retardant polyester DTY decreases, and the tensile strength, crimp shrinkage, crimp stability and boiling water shrinkage change little, indicating that the improvement of T2 has limited effect on the crystallinity of the fiber, so it has a slight impact on the physical properties of the flame retardant polyester DTY, but the extent of impact is small.

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The optimal process conditions selected under process route 1 are shown in Table 6.

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2.2 Process route 2

Select the best process conditions obtained under process route 1 (see Table 6). See Table 7 for the physical properties of flame retardant polyester DTY and conventional polyester DTY produced by process route 1 and process route 2.

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Table 7 shows that:

① Under the same process route, the tensile strength, crimp shrinkage and crimp stability of flame retardant polyester DTY are lower than those of conventional polyester POY, while the boiling water shrinkage is slightly higher;

② The physical properties of flame retardant polyester DTY prepared by process route 2 are better than that of process route 1, and basically reach the level of conventional polyester DTY under process route 1. Process route 2 is S and Z direction, so there is no residual torque in the yarn, which is very beneficial to improve the fluffy, springback and weaving performance of automotive decorative fabric.

From the above test results, it can be seen that the parameter that has a greater impact on the physical properties of flame retardant polyester DTY, especially the crimp shrinkage, is mainly T1, and the other parameters have a smaller impact. Compared with conventional varieties of the same specification and under the same process route and process conditions, the crimp shrinkage of flame retardant polyester DTY is much lower. This is mainly due to the presence of flame retardant in the molecules of flame retardant polyester to participate in copolymerization, forming a branched chain structure, which reduces its crystallinity and fiber structure [2]. The crimp shrinkage and crimp stability of the fiber are reduced, thus affecting the puffiness and elasticity of automotive decorative fabrics. In order to meet the requirements of automotive decorative fabric, the crimp shrinkage and crimp stability of flame retardant polyester DTY should be improved, so we adopt flame retardant process route 2.

03

epilogue

Under the same DTY processing conditions, the addition of flame retardant in the flame retardant fiber decreases the relative molecular weight of the polymer and destroys the original macromolecular structure of the polymer to a certain extent. The physical properties of the flame retardant polyester DTY produced are obviously different from those of conventional polyester DTY, with low tensile strength, crimp shrinkage and stability; The main parameter affecting the crimp shrinkage and stability is the deformation temperature (the first hot box temperature). The higher the deformation temperature, the higher the crimp shrinkage and stability. Therefore, the crimp shrinkage and stability of the flame retardant polyester DTY prepared by the process route 2 were improved greatly. However, the selection of process route 2 will reduce the output and increase the production cost. Therefore, different texturing process routes should be selected according to the quality requirements of subsequent users and the comprehensive balance of economic benefits.