Production process of PBT low stretch yarn

Abstract

The application discloses a PBT low-elasticity yarn production process, which comprises the following steps: in the first step, PBT chips are sequentially subjected to drying, melt spinning, air cooling, bunching and oiling, and winding to obtain POY filaments; in the second step, the POY filaments prepared in the first step are unwound at a speed of 700-900 m / min, sequentially subjected to preheating, twisting, heating setting and cooling and oiling, and then wound to obtain the PBT low-elasticity yarn product; wherein the environmental temperature during preheating is 110-130 DEG C, the twist number during twisting is 0.5-2, and the environmental temperature during heating setting is 190-210 DEG C. Through the above manner, the elasticity of the traditional PBT high-elasticity yarn can be reduced by nearly half, the profile definition of the final fabric pattern is not deformed, the customer requirements are met, and the overall production cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of polyester fiber materials, and in particular to a production process for PBT low-elasticity yarn. Background Technology

[0002] PBT fiber is a type of polyester fiber. Compared to commonly used PET fiber, it crystallizes faster, has higher elongation, and superior elongation elastic recovery. It also boasts excellent durability and dimensional stability. Fabrics made from PBT fiber are soft to the touch, with good moisture absorption, abrasion resistance, and fiber crimp. Its tensile and compressive elasticity are exceptional, with a significantly enhanced elastic recovery rate compared to polyester. Therefore, it is particularly suitable for making high-elasticity textiles such as swimwear, tights, training clothes, gymnastics wear, bodybuilding wear, tennis wear, dance leotards, stretch denim, ski pants, stockings, and bandages used in medical applications. However, due to the high elasticity of PBT fiber, it is prone to deformation when patterns are created on the fabric, resulting in unclear outlines. Therefore, in practice, it is generally used to create low-elasticity filaments by compounding other fibers with PBT fiber, replacing single-material high-elasticity PBT filaments. The process of compounding low-elasticity filaments is more complex and costly than that of single-material high-elasticity PBT filaments. Summary of the Invention

[0003] The main technical problem solved by this invention is to provide a PBT low-elasticity yarn production process that can reduce the elasticity of PBT yarn bundles to meet the requirement of clear pattern outlines on fabrics.

[0004] To solve the above-mentioned technical problems, the present invention adopts a technical solution as follows: providing a PBT low-elasticity yarn production process, the PBT low-elasticity yarn production process including the following steps: the first step is to sequentially dry, melt spin, air cool, bundle and oil, and wind up PBT chips to obtain POY filaments; the second step is to unwind the POY filaments obtained in the first step at a speed of 700~900 meters / min, sequentially preheat, twist, heat set, and cool and oil, and then wind up to obtain the finished PBT low-elasticity yarn; wherein the ambient temperature during preheating is 110~130℃, the twist coefficient during twisting is 0.5~2, and the ambient temperature during heat set is 190~210℃.

[0005] In a preferred embodiment of the present invention, the drying temperature during the first drying step is 90~130℃ and the drying time is 8~12h.

[0006] In a preferred embodiment of the present invention, the POY filament obtained in the first step has a specification of 80 dtex / 14f or 80 dtex / 24f.

[0007] In a preferred embodiment of the present invention, the preheating in the second step is performed using a preheating copper tube, during which the POY filament passes through the center of the copper tube. The length of the preheating copper tube is 1.5~2.5m.

[0008] In a preferred embodiment of the present invention, the second step of heating and shaping is performed using a shaping copper tube. During heating and shaping, the twisted filament passes through the center of the shaping copper tube. The length of the shaping copper tube is 1.5~2.5m.

[0009] The beneficial effects of this invention are as follows: Based on existing raw materials, this invention analyzes the characteristics of PBT fiber raw materials and optimizes the existing PBT filament production process without adding other raw materials, reducing the elasticity of PBT filament from more than 50% to about 30%. Moreover, the fabric patterns produced using this product are clear and do not deform, which has been widely praised by customers. Furthermore, since a single material is used, there is no need for composite processes, simplifying the entire production line and significantly reducing the cost of the final product. Detailed Implementation

[0010] The preferred embodiments of the present invention will now be described in detail so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0011] The embodiments of this invention include: A PBT low-elasticity yarn production process, characterized in that the PBT low-elasticity yarn production process includes the following steps: The first step involves drying, melt spinning, air cooling, bundling and oiling, and winding PBT chips to obtain POY filaments. The drying temperature is 90~130℃ and the drying time is 8~12h to ensure that the moisture content in the chips after drying is less than 30PPM. The melting spinning temperature is 260℃ and the spinning speed is 2600 m / min. The second step involves unwinding the POY filaments obtained in the first step at a speed of 700-900 meters per minute, and then sequentially preheating, twisting, heat setting, cooling, and oiling before winding to obtain the finished PBT low-elasticity yarn. The ambient temperature during preheating is 110-130°C, the twist coefficient during twisting is 1-3, and the ambient temperature during heat setting is 190-210°C.

[0012] In the second step, preheating is performed using a preheating copper tube. During heating, the POY filament passes through the center of the copper tube. The length of the preheating copper tube is 1.5~2.5m.

[0013] In the second step, a shaping copper tube is used for heating and shaping. During heating and shaping, the twisted filament passes through the center of the shaping copper tube. The length of the shaping copper tube is 1.5~2.5m.

[0014] The actual test results are as follows: In Examples 1-6, the shrinkage rate was tested by cutting a 50cm section of the finished product, steaming it in a water bath for 5 minutes, and then re-measuring the length to observe the actual shrinkage. The results showed that, compared to the control, the shrinkage rate of the PBT filament was significantly reduced. This process was adopted because the preheating and setting temperatures for traditional PBT high-elasticity yarn are both 180℃. In actual heating, at an ambient temperature of 180℃, the filament body passing through the heating copper tube at high speed can generally be heated to around 100℃. This temperature falls between the Vicat softening point and the glass transition point of PBT material. The high-elasticity rubber state, meaning that after twisting in the high-elasticity state, and then reheating to the high-elasticity state, is used for secondary shaping through molecular recrystallization, results in excellent filament elasticity. In this application, in order not to change the material properties and reduce the overall elasticity, and to meet customer requirements, the preheating temperature is reduced to the limit of about 120°C. The actual filament exit temperature after preheating is near the glass transition point. Therefore, after twisting, there is elasticity but little deformation. Finally, the shaping temperature is increased to raise the temperature of the twisted filament to near the Vicat softening point, which fully reduces the intermolecular stress caused by twisting. After recooling, the overall shrinkage performance is further reduced.

[0015] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A process for producing PBT low-elasticity yarn, characterized in that, The PBT low-elasticity yarn production process includes the following steps: The first step involves drying, melt spinning, air cooling, bundling and oiling, and winding PBT chips to obtain POY filaments. The specifications of the POY filaments are 80 dtex / 14f or 80 dtex / 24f. The second step involves unwinding the POY filaments obtained in the first step at a speed of 700-900 meters per minute, and then sequentially preheating, twisting, heat setting, cooling, and oiling before winding them up to obtain the finished PBT low-elasticity yarn. The ambient temperature during preheating is 110–130℃, the twist coefficient during twisting is 0.5–2, and the ambient temperature during heat setting is 190–210℃. During preheating, a preheating copper tube is used for heating. During heating, the POY filament passes through the center of the preheating copper tube, and the length of the preheating copper tube is 1.5 to 2.5 m. During the heat setting process, a shaping copper tube is used for heating. During the heat setting process, the twisted filament passes through the center of the shaping copper tube, and the length of the shaping copper tube is 1.5 to 2.5 m.

2. The PBT low-elasticity yarn production process according to claim 1, characterized in that, The drying temperature during the first drying step is 90–130°C, and the drying time is 8–12 hours.

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