CN-121976323-A - Preparation method of water-soluble polyester sea-island fiber

Abstract

The invention relates to the technical field of polymer material and fiber manufacturing, discloses a preparation method of water-soluble polyester sea-island fiber, and aims to solve the problems of unstable spinning process and uneven fiber structure caused by weak bonding force of two-phase interfaces of sea and island in the existing sea-island fiber preparation. The method introduces a synergistic system consisting of a latent catalyst, an acid scavenger and a reactive compatibilizer containing electrophilic and epoxy groups into a system comprising an ionic water-soluble copolyester (sea phase) and a thermoplastic polyester (island phase). By controlling the temperature difference of sea and island phase melts, the latent catalyst is promoted to decompose at the interface of the two phases, and in-situ catalysis is carried out on the compatibilizer enriched at the interface to carry out grafting reaction, so that chemical bond connection is formed between the two phases of the sea and island. The invention remarkably improves the stability of the spinning process and improves the structural uniformity of the obtained fiber by constructing a stable chemical interface layer.

Inventors

• SHI JINHUA
• SHI GAOLIANG
• Shi Gangliang
• Zhu Hangjia
• LONG HAIJUN
• SHI GAOQI

Assignees

• 兴惠化纤集团有限公司

Dates

Publication Date

20260505

Application Date

20260317

Claims (10)

1. 1. The preparation method of the water-soluble polyester sea-island fiber is characterized by comprising the following steps of: S1, providing a sea-phase melt and an island-phase melt, wherein the sea-phase melt is prepared from a composition comprising ionic water-soluble copolyester and a latent catalyst, and the island-phase melt is prepared from a composition comprising polyethylene terephthalate, a reactive compatibilizer and an acid scavenger; S2, compounding the sea-phase melt and the island-phase melt, and extruding the mixture into filaments through a sea-island spinneret plate, wherein in the compounding process, the latent catalyst is activated and catalyzes the reactive compatibilizer to react at a sea-island two-phase interface to form a graft copolymer; And S3, cooling, oiling, drafting and winding the extruded fiber yarns.
2. 2. The method for preparing a water-soluble polyester sea-island fiber according to claim 1, wherein in the step S1, the ionic water-soluble copolyester is polymerized from a raw material comprising terephthalic acid monomer, ethylene glycol monomer and an ionic comonomer containing sulfonate groups.
3. 3. The process for preparing a water-soluble polyester sea-island fiber according to claim 1, wherein in step S1, the latent catalyst is a pyrolyzed acid catalyst precursor which is stable at the preparation temperature of the sea-phase melt and is decomposed to release the acid catalyst at the temperature of the island-phase melt.
4. 4. The method according to claim 1, wherein in step S1, the reactive compatibilizer is an asymmetric compatibilizer having a molecular structure containing a plurality of epoxy functional groups and at least one lipophilic group.
5. 5. The method for preparing a water-soluble polyester sea-island fiber according to claim 1, wherein in the step S1, the acid scavenger is hydrotalcite-like compound or phosphite-like compound.
6. 6. The method for preparing a water-soluble polyester sea-island fiber according to claim 1, wherein in step S1, the composition comprises, in parts by weight: 38-42 parts of polyethylene terephthalate; 58-62 parts of ionic water-soluble copolyester; 0.3-0.8 part of reactive compatibilizer; 0.06-0.19 part of latent catalyst; 0.02-0.04 part of acid trapping agent.
7. 7. The method for preparing a water-soluble polyester sea-island fiber according to claim 1, wherein the step S1 comprises: the composition of the ionic water-soluble copolyester and the latent catalyst is melt extruded at 235-240 ℃ to obtain the sea-phase melt; And (3) carrying out melt extrusion on the polyethylene terephthalate, the reactive compatibilizer and the acid trapping agent at the temperature of 280-285 ℃ to obtain the island phase melt.
8. 8. The method for producing a sea-island fiber of water-soluble polyester according to claim 1, wherein in step S2, the spinning pressure of the extrusion through the sea-island spinneret is 10 to 12MPa.
9. 9. The method for preparing a water-soluble polyester sea-island fiber according to claim 1, wherein in the step S3, the drawing is a multi-stage hot drawing, and the drawing process comprises: performing first-stage drafting at 70-75 ℃; Performing a second stage draft at 100-110 ℃; The third stage of drafting is carried out at 90-95 ℃.
10. 10. The method according to claim 4, wherein in step S2, the reactive compatibilizer is preferentially concentrated at the interface between the sea and island phases under the action of the electrophilic group, and is subjected to in-situ grafting reaction with the sea and island phase polymer under the action of a latent catalyst activated by the high temperature of the island phase melt.

Description

Preparation method of water-soluble polyester sea-island fiber Technical Field The invention relates to the technical field of polymer material and fiber manufacturing, in particular to a preparation method of water-soluble polyester sea-island fiber. Background The sea-island composite spinning technology is one of the main industrial production methods for preparing superfine fiber and microfine fiber. The technology uses a specific composite spinneret plate to disperse one polymer (island phase) as a disperse phase in a continuous matrix of the other polymer (sea phase) in an independent trickle form to form the composite fiber with the 'sea-island' structure. In the post-treatment process, the sea phase component is dissolved and removed by a solvent, thereby obtaining a microfiber bundle composed of the island phase component. In the preparation of water-soluble polyester sea-island fibers, polyethylene terephthalate (PET) or the like is generally used as a hydrophobic island phase component, and a modified copolyester is used as a hydrophilic sea phase component. However, these two polymers differ significantly in molecular structure and polarity, resulting in their poor thermodynamic compatibility and high interfacial tension between the melts. This inherent incompatibility presents a continuing technical challenge to the composite spinning process. In the high temperature and high shear melt extrusion and stretching process, the huge interfacial tension makes the sea and island two-phase melt difficult to form stable and uniform composite fluid, and the interfacial layer is very fragile. The method directly leads to poor stability in the spinning process, and the composite yarn is extremely easy to crack under high-speed drafting and is high in breakage rate, so that the improvement of production efficiency is limited. In addition, the unstable melt flow also causes uneven distribution of island phase components in the sea phase, the size and morphology of the island phase components fluctuate along the axial direction of the fiber, and finally the obtained fiber has high non-uniformity of physical properties, and the consistency of product quality is difficult to ensure. In order to solve the problem, although attempts are made to use a compatibilizer in the prior art, the affinity of the conventional compatibilizer to two phases is not ideal, the enrichment efficiency at the interface is low, the formed physical or chemical bond is weak, the improvement effect on the process stability and the product uniformity is limited, and the problems are not solved fundamentally. Disclosure of Invention The invention aims to solve the problems in the prior art that in the preparation process of the water-soluble polyester sea-island fiber, the interfacial bonding force of two phases is weak due to the inherent compatibility difference between the water-soluble sea-phase component and the polyester island-phase component, and the phase separation is easy to occur in the melt spinning process. This instability causes non-uniformity in the microstructure of the final fiber and also results in a high rate of breakage during spinning. In addition, in the subsequent fiber opening process, there may be a problem in that the sea-phase component is not completely dissolved or the dissolution rate is slow, affecting the dispersibility and cleanliness of the finally obtained ultra-fine island-phase fiber. It is therefore an object of the present invention to provide a process for the preparation of water-soluble polyester islands-in-the-sea fibers which aims at improving the compatibility of the two phases of the sea and island in the molten state and at improving the structural uniformity of the final fiber and the stability of the production process. In order to achieve the above object, the present invention provides a method for preparing a water-soluble polyester sea-island fiber, comprising the steps of: s1, providing a sea phase melt and an island phase melt A sea phase melt and an island phase melt are provided. The sea phase melt is prepared from a composition comprising an ionic water-soluble copolyester and a latent catalyst. Specifically, the ionic water-soluble copolyester is prepared by polymerization of raw materials comprising terephthalic acid monomers, ethylene glycol monomers and an ionic comonomer containing sulfonate groups. The latent catalyst is a pyrolyzed acid catalyst precursor. The island phase melt is prepared from a composition comprising polyethylene terephthalate, a reactive compatibilizer, and an acid scavenger. Specifically, the reactive compatibilizer is an asymmetric compatibilizer, and the molecular structure of the reactive compatibilizer simultaneously comprises a plurality of epoxy functional groups and at least one electrophilic group. The acid trapping agent is hydrotalcite-like compound or phosphite ester-like compound. In a specific embodiment, the composition for preparing th