PET / COPET island-in-sea fiber composite yarn and preparation process thereof

Abstract

The application relates to the field of polyurethane elastomers, in particular to a preparation process of PET / COPET island-in-sea type fiber composite yarn, which comprises the following steps: (1) blending polyester resin chips with a modifier, melting and mixing, and recording as a PET melt; (2) melting alkali-soluble polyester resin chips (COPET), and recording as a COPET melt; (3) forming a composite melt by means of a melt pipeline through the PET melt and the COPET melt; (4) spinning the composite melt, and after cooling, oiling and winding, forming a fiber composite yarn precursor; (5) opening the fiber texture of the fiber composite yarn precursor, and performing water washing and drying treatment, so that PET / COPET island-in-sea type fiber composite yarn is obtained. The application designs an island-in-sea type fiber composite yarn, and compared with conventional PET / COPET fibers on the market, the fiber composite yarn has higher mechanical properties, higher elasticity and better acid and alkali resistance.

Description

Technical Field

[0001] This invention relates to the field of polyurethane elastomers, specifically to a PET / COPET island-of-sea fiber composite filament and its preparation process. Background Technology

[0002] Island-island fibers are made by dispersing one polymer within another, with the dispersed phase resembling "islands" in the fiber cross-section, while the parent phase corresponds to the "sea." Viewed from the fiber's cross-section, one component is surrounded by another in a finely dispersed state, like numerous islands in a sea. Island-island composite fibers offer many superior properties that are difficult to find in natural fibers, and their application in the textile industry is increasingly significant.

[0003] Island-type composite fiber spinning involves using different types, specifications, and ratios of alkali-soluble fiber-forming polymer melt and conventional fiber-forming polymer. These are distributed through separate melt channels via an island-type composite assembly composed of multiple composite distribution plates, and then merged by a spinneret to form a composite melt flow, which is then extruded as a filament bundle from a single spinneret orifice. The conventional fiber-forming polymer is dispersed as microfibers (island phase) within the alkali-soluble fiber-forming polymer (sea phase). The island fibers are then twisted and combined with high-shrinkage yarns, woven into fabric, and subsequently treated with alkali to dissolve the sea phase polymer, resulting in a fabric composed of ultrafine fibers. High-end fabrics such as imitation velvet are made from island-type ultrafine composite fibers.

[0004] Currently, the most common island-type composite fiber on the market uses alkali-soluble polyester (COPET) as the island component. High-temperature, strong alkaline conditions (temperature ≥95℃, pH ≥13) are used to degrade the COPET into sodium terephthalate and ethylene glycol. However, polyethylene terephthalate (PET) undergoes a certain degree of degradation under high-temperature, strong alkaline conditions. If COPET is used as the island component and PET as the sea component to prepare PET / COPET type island-type fibers, the PET island component will undergo partial hydrolysis after high-temperature, strong alkaline treatment, resulting in damage to mechanical properties, reduced strength, and decreased elongation at break, making it difficult to obtain island-type fiber composite yarns with good mechanical properties. Summary of the Invention

[0005] To address the problems existing in the prior art, the purpose of this invention is to provide a PET / COPET island-type fiber composite yarn with high elasticity, good moisture absorption, and acid and alkali resistance, as well as its preparation process.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] In a first aspect, the present invention provides a process for preparing PET / COPET island-of-sea fiber composite yarn, comprising the following steps:

[0008] (1) After the polyester resin chips are subjected to crystallization treatment and drying treatment in sequence, they are mixed with the modifier, fed into the screw extruder for mixing and melting, and then fed into the spinning box after metering. This is called PET melt.

[0009] (2) After the alkali-soluble polyester resin chips (COPET) are subjected to crystallization and drying treatment in sequence, they are fed into a screw extruder for melting, and then fed into the spinning box after metering. This is called COPET melt.

[0010] (3) The PET melt and COPET melt are transported to the island composite component through melt pipelines, and then merged by the spinneret to form a composite melt;

[0011] (4) The composite melt is sprayed into a bundle shape through the spinneret hole of the spinneret, and after cooling, oiling and winding, a fiber composite filament precursor is formed;

[0012] (5) The fiber composite filament precursor is opened in an alkaline solution, and then washed and dried to obtain PET / COPET island-type fiber composite filament.

[0013] Preferably, in steps (1) and (2), the crystallization process is carried out in a fluidized bed with a crystallization residence time of 15-20 min and a temperature of 110-120℃.

[0014] Preferably, in steps (1) and (2), the drying process is carried out in a filling tower; the drying temperature in step (1) is 150-160℃ and the drying time is 6-8h; the drying temperature in step (2) is 140-150℃ and the drying time is 10-12h.

[0015] Preferably, in step (1), the mass ratio of the modifier to the polyester resin chips is 1-5:10.

[0016] Preferably, in step (1), the temperature range of the screw extruder is 280-290℃; in step (2), the temperature range of the screw extruder is 275-280℃.

[0017] Preferably, in step (1), the polyester resin chips are polyethylene terephthalate (PET) with a viscosity of 0.674±0.01dL / g and a melting point of 258-260℃.

[0018] Preferably, in step (2), the viscosity of the alkali-soluble polyester resin chips (COPET) is 0.685±0.01dL / g, and the melting point is 245-248℃.

[0019] Preferably, in step (3), the mass ratio of the PET melt to the COPET melt is 7~8:2~3.

[0020] Preferably, in step (4), the spinning temperature is 290°C and the spinning speed is 800~1200m / min.

[0021] Preferably, in step (5), the concentration of the alkali solution is 12-18 g / L, the temperature is 50-60℃, and the treatment time is 30-40 min.

[0022] Preferably, the modifier is propyltriglyceride dipeptide-polyurethane, and the preparation method includes:

[0023] S1. Aleuropein dipeptide and 1,5-pentanediol were mixed into toluene and stirred until homogeneous under magnetic stirring. Then p-toluenesulfonic acid was added and stirred until homogeneous again. The mixture was then placed in a reflux condenser and heated to 110-130°C in an oil bath. The mixture was kept at this temperature and stirred continuously for 10-15 hours. During this time, the generated water was continuously separated. After the reaction was completed, the mixture was naturally cooled to room temperature. The solid in the reaction solution was filtered out and then purified by recrystallization and dried under reduced pressure to obtain aleuropein dipeptide ester.

[0024] The mass ratio of propionyl ester dipeptide, 1,5-pentanediol, p-toluenesulfonic acid and toluene is 11-14:3.4-5.2:12-17:500.

[0025] S2. Preparation of propionylcholine dipeptide polyester urea:

[0026] Acetylated dipeptide ester and N-methylpyrrolidone were mixed in a reaction flask, heated to 50-55℃, and stirred until completely dissolved. Triethylamine was then added dropwise, and the mixture was kept warm and stirred for half an hour. The temperature was then raised to 75-80℃, and dibutyltin dilaurate was added. The mixture was stirred for half an hour, and then isophorone diisocyanate was added. After stirring for 2-3 hours, 1,4-butanediamine was added, and the temperature was raised to 80-85℃. The mixture was kept warm and stirred for 6-10 hours. After the reaction was completed, the mixture was allowed to cool naturally to room temperature and poured into dichloromethane. A precipitate gradually formed. The dichloromethane containing the precipitate was then placed at 0-4℃ for 8-12 hours. The precipitate was filtered out while cold, dried, and ground into powder to obtain the modifier acetylated dipeptide polyester urea.

[0027] The mass ratio of propionate dipeptide, isophorone diisocyanate, 1,4-butanediamine and N-methylpyrrolidone is 5.2-7.4:2.4-3.5:0.6-0.8:20-30; triethylamine is used to neutralize p-toluenesulfonate in step S1, and the amount added is 24%-48% of the mass of propionate dipeptide; dibutyltin dilaurate is used as a catalyst, and the amount added is 4%-6% of the mass of propionate dipeptide.

[0028] Secondly, the present invention provides a sea-island fiber composite yarn product prepared using the above-described PET / COPET sea-island fiber composite yarn preparation process.

[0029] Thirdly, the present invention provides an application of PET / COPET island-type fiber composite yarn in fabrics.

[0030] The beneficial effects of this invention are as follows:

[0031] 1. This invention designs an island-type composite fiber filament, which is composed of alkali-soluble polyester as the "sea" component and modified polyester as the "island" component. Compared with conventional PET / COPET fibers on the market, this fiber filament has higher mechanical properties, higher elasticity, and better acid and alkali resistance.

[0032] 2. The unique feature of the island-type fiber composite yarn designed in this invention is that the conventional island component, polyethylene terephthalate (PET), has been modified to improve its performance. The modification process uses a diol ester produced by the reaction of propionate dipeptide ester and 1,5-pentanediol as a raw material, which is then reacted with isophorone diisocyanate and 1,4-butanediamine to obtain a propionate dipeptide polyester urea. This polyester urea is then composited with polyester resin to prepare the modified polyester resin.

[0033] 3. In the synthesis of modified polyester resin, the molecular structure of the propyltriethionide polyesterurea, which acts as a modifier, contains a sufficient amount of urea groups. The urea group structure contains abundant hydrogen bond acceptors and has a strong hydrogen bond forming ability. Thus, it can cross-link with polyester resin through hydrogen bond acceptors during the bonding process, making the structure of polyester resin more stable, with better resistance to acids and alkalis, and also improving mechanical properties to a certain extent.

[0034] 4. Furthermore, the reactant used in the synthesis of the modifier propyltyrosine dipeptide polyester urea in this invention is propyltyrosine dipeptide ester. Propyltyrosine dipeptide ester is obtained by combining propyltyrosine dipeptide with straight-chain pentanediol. Propyltyrosine dipeptide, also known as alanyl-L-tyrosine, contains not only amino and carboxyl groups but also peptide bonds (imide groups) in its molecular structure. This unique structure makes it more stable than other amino acid molecules, thus possessing certain application potential. In this invention, it is combined with straight-chain 1,5-pentanediol to form diol propyltyrosine dipeptide ester, which is then combined with isophorone diisocyanate and 1,4-butanediamine. The resulting propyltyrosine dipeptide polyester urea is applied to modified polyesters. Results showed that it not only improved the acid and alkali resistance of polyester resins but also significantly improved their mechanical properties and moisture absorption properties. Detailed Implementation

[0035] To more clearly illustrate the present invention and to gain a clearer understanding of its technical features, objectives, and beneficial effects, the technical solution of the present invention will now be described in detail below, but this should not be construed as limiting the scope of the present invention.

[0036] The present invention will be further described below with reference to the following embodiments.

[0037] Example 1

[0038] A process for preparing PET / COPET island-of-sea fiber composite yarn includes the following steps:

[0039] (1) The polyester resin chips are subjected to crystallization and drying treatment. The crystallization treatment is carried out in a fluidized bed with a crystallization residence time of 15 min and a temperature of 120℃. The drying treatment is carried out in a packed tower with a drying temperature of 150℃ and a drying time of 8 h. Then, it is mixed with a modifier. The mass ratio of the modifier to the polyester resin chips is 3:10. The mixture is fed into a screw extruder for mixing and melting. The temperature range of the screw extruder is 280-290℃. After metering, it is fed into the spinning box and recorded as PET melt.

[0040] The polyester resin chips are polyethylene terephthalate (PET), with a viscosity of 0.674±0.01 dL / g and a melting point of 258-260℃.

[0041] (2) The alkali-soluble polyester resin chips (COPET) are subjected to crystallization treatment and drying treatment in sequence. The crystallization treatment is carried out in a fluidized bed with a crystallization residence time of 15 min and a temperature of 120℃. The drying treatment is carried out in a packed tower with a drying temperature of 140℃ and a drying time of 12 h. Then, it is fed into a screw extruder for melting. The temperature range of the screw extruder is 275-280℃. After metering, it is fed into the spinning box and recorded as COPET melt.

[0042] The viscosity of the alkali-soluble polyester resin chips (COPET) is 0.685±0.01dL / g, and the melting point is 245-248℃.

[0043] (3) The PET melt and COPET melt are transported to the island composite component through melt pipelines, and then merged by the spinneret to form a composite melt;

[0044] The mass ratio of PET melt to COPET melt is 7.5:2.5.

[0045] (4) The composite melt is sprayed into a filament bundle through the spinneret hole of the spinneret. The spinning temperature is 290℃ and the spinning speed is 1000m / min. After cooling, oiling and winding, a fiber composite filament precursor is formed.

[0046] (5) The fiber composite filament precursor is treated in an alkaline solution with a concentration of 15 g / L, a temperature of 55°C, and a treatment time of 35 min. After washing and drying, PET / COPET island-type fiber composite filament is obtained.

[0047] In step (1), the modifier is propyltriethionide-polyurethane, and the preparation method includes:

[0048] S1. Aleuropein dipeptide and 1,5-pentanediol were mixed into toluene and stirred until homogeneous under magnetic stirring. Then p-toluenesulfonic acid was added and stirred until homogeneous again. The mixture was then placed in a reflux condenser and heated to 120°C in an oil bath. The mixture was kept at this temperature and stirred continuously for 12 hours. During the reaction, the generated water was continuously separated. After the reaction was completed, the mixture was naturally cooled to room temperature. The solid in the reaction solution was filtered out and then purified by recrystallization and dried under reduced pressure to obtain aleuropein dipeptide ester.

[0049] The mass ratio of propionyl ester dipeptide, 1,5-pentanediol, p-toluenesulfonic acid and toluene is 13:4.6:15:500.

[0050] S2. Preparation of propionylcholine dipeptide polyester urea:

[0051] Acetylated dipeptide ester and N-methylpyrrolidone were mixed in a reaction flask, heated to 50°C, and stirred until completely dissolved. Triethylamine was then added dropwise, and the mixture was kept warm and stirred for another half hour. The temperature was then raised to 75°C, and dibutyltin dilaurate was added. The mixture was stirred for another half hour, and then isophorone diisocyanate was added. After stirring for 2.5 hours, 1,4-butanediamine was added, and the temperature was raised to 80°C. The mixture was kept warm and stirred for 8 hours. After the reaction was completed, the mixture was allowed to cool naturally to room temperature and poured into dichloromethane. A precipitate gradually formed. The dichloromethane containing the precipitate was then placed at 0-4°C for 10 hours. The precipitate was filtered out while cold, dried, and ground into powder to obtain the modifier acetylated dipeptide polyester urea.

[0052] The mass ratio of propionate dipeptide, isophorone diisocyanate, 1,4-butanediamine and N-methylpyrrolidone is 5.8:2.9:0.7:25; triethylamine is used to neutralize p-toluenesulfonate in step S1, and the amount added is 36% of the mass of propionate dipeptide; dibutyltin dilaurate is used as a catalyst and the amount added is 5% of the mass of propionate dipeptide.

[0053] Example 2

[0054] A preparation process for a PET / COPET island-of-sea fiber composite filament is the same as that in Example 1, except that:

[0055] Includes the following steps:

[0056] (1) The polyester resin chips are subjected to crystallization and drying treatment. The crystallization treatment is carried out in a fluidized bed with a crystallization residence time of 15 min and a temperature of 110℃. The drying treatment is carried out in a packed tower with a drying temperature of 150℃ and a drying time of 6 h. Then, it is mixed with a modifier. The mass ratio of the modifier to the polyester resin chips is 1:10. The mixture is fed into a screw extruder for mixing and melting. The temperature range of the screw extruder is 280-290℃. After metering, it is fed into the spinning box and recorded as PET melt.

[0057] The polyester resin chips are polyethylene terephthalate (PET), with a viscosity of 0.674±0.01 dL / g and a melting point of 258-260℃.

[0058] (2) The alkali-soluble polyester resin chips (COPET) are subjected to crystallization treatment and drying treatment in sequence. The crystallization treatment is carried out in a fluidized bed with a crystallization residence time of 15 min and a temperature of 110℃. The drying treatment is carried out in a packed tower with a drying temperature of 140℃ and a drying time of 10 h. Then, it is fed into a screw extruder for melting. The temperature range of the screw extruder is 275-280℃. After metering, it is fed into the spinning box and recorded as COPET melt.

[0059] The viscosity of the alkali-soluble polyester resin chips (COPET) is 0.685±0.01dL / g, and the melting point is 245-248℃.

[0060] (3) The PET melt and COPET melt are transported to the island composite component through melt pipelines, and then merged by the spinneret to form a composite melt;

[0061] The mass ratio of PET melt to COPET melt is 7:3.

[0062] (4) The composite melt is sprayed into a filament bundle through the spinneret hole of the spinneret. The spinning temperature is 290℃ and the spinning speed is 800m / min. After cooling, oiling and winding, a fiber composite filament precursor is formed.

[0063] (5) The fiber composite filament precursor is treated in an alkaline solution with a concentration of 12 g / L, a temperature of 50°C, and a treatment time of 30 min. After washing and drying, PET / COPET island-type fiber composite filament is obtained.

[0064] Example 3

[0065] A preparation process for a PET / COPET island-of-sea fiber composite filament is the same as that in Example 1, except that:

[0066] (1) The polyester resin chips are subjected to crystallization and drying treatment. The crystallization treatment is carried out in a fluidized bed with a crystallization residence time of 20 min and a temperature of 120℃. The drying treatment is carried out in a packed tower with a drying temperature of 160℃ and a drying time of 8 h. Then, it is mixed with a modifier. The mass ratio of the modifier to the polyester resin chips is 5:10. The mixture is fed into a screw extruder for mixing and melting. The temperature range of the screw extruder is 280-290℃. After metering, it is fed into the spinning box and recorded as PET melt.

[0067] The polyester resin chips are polyethylene terephthalate (PET), with a viscosity of 0.674±0.01 dL / g and a melting point of 258-260℃.

[0068] (2) The alkali-soluble polyester resin chips (COPET) are subjected to crystallization treatment and drying treatment in sequence. The crystallization treatment is carried out in a fluidized bed with a crystallization residence time of 20 min and a temperature of 120℃. The drying treatment is carried out in a packed tower with a drying temperature of 150℃ and a drying time of 12 h. Then, it is fed into a screw extruder for melting. The temperature range of the screw extruder is 275-280℃. After metering, it is fed into the spinning box and recorded as COPET melt.

[0069] The viscosity of the alkali-soluble polyester resin chips (COPET) is 0.685±0.01dL / g, and the melting point is 245-248℃.

[0070] (3) The PET melt and COPET melt are transported to the island composite component through melt pipelines, and then merged by the spinneret to form a composite melt;

[0071] The mass ratio of PET melt to COPET melt is 8:2.

[0072] (4) The composite melt is sprayed into a filament bundle through the spinneret hole of the spinneret. The spinning temperature is 290℃ and the spinning speed is 1200m / min. After cooling, oiling and winding, a fiber composite filament precursor is formed.

[0073] (5) The fiber composite filament precursor is treated in an alkaline solution with a concentration of 18 g / L, a temperature of 60°C, and a treatment time of 40 min. After washing and drying, PET / COPET island-type fiber composite filament is obtained.

[0074] Example 4

[0075] A preparation process for a PET / COPET island-type fiber composite yarn is the same as that in Example 1, except that the preparation method of the modifier in step (1) is different, specifically:

[0076] The modifier is propyltriglyceride dipeptide-polyurethane, and the preparation method includes:

[0077] S1. Aleuropein dipeptide and 1,5-pentanediol were mixed into toluene and stirred until homogeneous under magnetic stirring. Then, p-toluenesulfonic acid was added and stirred until homogeneous again. The mixture was then placed in a reflux condenser and heated to 110°C in an oil bath. The mixture was kept at this temperature and stirred continuously for 10 hours. During the reaction, the generated water was continuously separated. After the reaction was completed, the mixture was naturally cooled to room temperature. The solid in the reaction solution was filtered out and then purified by recrystallization and dried under reduced pressure to obtain aleuropein dipeptide ester.

[0078] The mass ratio of propionyl ester dipeptide, 1,5-pentanediol, p-toluenesulfonic acid and toluene is 11:3.4:12:500.

[0079] S2. Preparation of propionylcholine dipeptide polyester urea:

[0080] Acetylated dipeptide ester and N-methylpyrrolidone were mixed in a reaction flask, heated to 50°C, and stirred until completely dissolved. Triethylamine was then added dropwise, and the mixture was kept warm and stirred for another half hour. The temperature was then raised to 75°C, and dibutyltin dilaurate was added. The mixture was stirred for another half hour, and then isophorone diisocyanate was added. After stirring for 2 hours, 1,4-butanediamine was added, and the temperature was raised to 80°C. The mixture was kept warm and stirred for 6 hours. After the reaction was completed, the mixture was allowed to cool naturally to room temperature and poured into dichloromethane. A precipitate gradually formed. The dichloromethane containing the precipitate was then placed at 0-4°C for 8 hours. The precipitate was filtered out while cold, dried, and ground into powder to obtain the modifier acetylated dipeptide polyester urea.

[0081] The mass ratio of propionate dipeptide, isophorone diisocyanate, 1,4-butanediamine and N-methylpyrrolidone is 5.2:2.4:0.6:20; triethylamine is used to neutralize p-toluenesulfonate in step S1, and the amount added is 24% of the mass of propionate dipeptide; dibutyltin dilaurate is used as a catalyst and the amount added is 4% of the mass of propionate dipeptide.

[0082] Example 5

[0083] A preparation process for a PET / COPET island-type fiber composite yarn is the same as that in Example 1, except that the preparation method of the modifier in step (1) is different, specifically:

[0084] The modifier is propyltriglyceride dipeptide-polyurethane, and the preparation method includes:

[0085] S1. Acetylated dipeptide and 1,5-pentanediol were mixed into toluene and stirred until homogeneous under magnetic stirring. Then, p-toluenesulfonic acid was added and stirred until homogeneous again. The mixture was then placed in a reflux condenser and heated to 130°C in an oil bath. The mixture was kept at this temperature and stirred continuously for 15 hours. During the reaction, the generated water was continuously separated. After the reaction was completed, the mixture was naturally cooled to room temperature. The solid in the reaction solution was filtered out and then purified by recrystallization and dried under reduced pressure to obtain acetylated dipeptide ester.

[0086] The mass ratio of propionyl ester dipeptide, 1,5-pentanediol, p-toluenesulfonic acid and toluene is 14:5.2:17:500.

[0087] S2. Preparation of propionylcholine dipeptide polyester urea:

[0088] Acetylated dipeptide ester and N-methylpyrrolidone were mixed in a reaction flask, heated to 55°C, and stirred until completely dissolved. Triethylamine was then added dropwise, and the mixture was kept warm and stirred for another half hour. The temperature was then raised to 80°C, and dibutyltin dilaurate was added. The mixture was stirred for another half hour, and then isophorone diisocyanate was added. After stirring for 3 hours, 1,4-butanediamine was added, and the temperature was raised to 85°C. The mixture was kept warm and stirred for 10 hours. After the reaction was completed, the mixture was allowed to cool naturally to room temperature and poured into dichloromethane. A precipitate gradually formed. The dichloromethane containing the precipitate was then placed at 0-4°C for 12 hours. The precipitate was filtered out while cold, dried, and ground into powder to obtain the modifier acetylated dipeptide polyester urea.

[0089] The mass ratio of propionate dipeptide, isophorone diisocyanate, 1,4-butanediamine and N-methylpyrrolidone is 7.4:3.5:0.8:30; triethylamine is used to neutralize p-toluenesulfonate in step S1, and the amount added is 48% of the mass of propionate dipeptide; dibutyltin dilaurate is used as a catalyst and the amount added is 6% of the mass of propionate dipeptide.

[0090] Comparative Example 1

[0091] The preparation process of a PET / COPET island-type fiber composite yarn differs from that of Example 1 in that no modifier is added in step (1).

[0092] Comparative Example 2

[0093] The preparation process of a PET / COPET island-type fiber composite yarn differs from that of Example 1 in that the preparation method of the modifier in step (1) is different, specifically:

[0094] The modifier is propionyl ester, and the preparation method includes:

[0095] S1. Aleuropein dipeptide and 1,5-pentanediol were mixed into toluene and stirred until homogeneous under magnetic stirring. Then p-toluenesulfonic acid was added and stirred until homogeneous again. The mixture was then placed in a reflux condenser and heated to 120°C in an oil bath. The mixture was kept at this temperature and stirred continuously for 12 hours. During the reaction, the generated water was continuously separated. After the reaction was completed, the mixture was naturally cooled to room temperature. The solid in the reaction solution was filtered out and then purified by recrystallization and dried under reduced pressure to obtain aleuropein dipeptide ester.

[0096] The mass ratio of propionyl tyrosine dipeptide, 1,5-pentanediol, p-toluenesulfonic acid and toluene is 13:4.6:15:500.

[0097] Comparative Example 3

[0098] The preparation process of a PET / COPET island-type fiber composite yarn differs from that of Example 1 in that the preparation method of the modifier in step (1) is different, specifically:

[0099] The modifier is tryptophan polyester urea, and the preparation method includes:

[0100] S1. Tryptophan and 1,5-pentanediol were mixed into toluene and stirred evenly under magnetic stirring. Then p-toluenesulfonic acid was added and stirred evenly again. The mixture was then placed in a reflux condenser and heated to 120°C in an oil bath. The mixture was kept at this temperature and stirred continuously for 12 hours. During the reaction, the generated water was continuously separated. After the reaction was completed, the mixture was naturally cooled to room temperature. The solid in the reaction solution was filtered out and then purified by recrystallization and dried under reduced pressure to obtain tryptophan ester.

[0101] The mass ratio of tryptophan, 1,5-pentanediol, p-toluenesulfonic acid and toluene is 13:4.6:15:500.

[0102] S2. Preparation of tryptophan polyester urea:

[0103] Tryptophan ester and N-methylpyrrolidone were mixed in a reaction flask, heated to 50°C, and stirred until completely dissolved. Triethylamine was then added dropwise, and the mixture was kept warm and stirred for another half hour. The temperature was then raised to 75°C, and dibutyltin dilaurate was added. The mixture was stirred for another half hour, and then isophorone diisocyanate was added. After stirring for 2.5 hours, 1,4-butanediamine was added, and the temperature was raised to 80°C. The mixture was kept warm and stirred for 8 hours. After the reaction was completed, the mixture was allowed to cool naturally to room temperature and poured into dichloromethane. A precipitate gradually formed. The dichloromethane containing the precipitate was then placed at 0-4°C for 10 hours. The precipitate was filtered out while cold, dried, and ground into powder to obtain the modifier tryptophan polyester urea.

[0104] The mass ratio of tryptophan ester, isophorone diisocyanate, 1,4-butanediamine and N-methylpyrrolidone is 5.8:2.9:0.7:25; triethylamine is used to neutralize p-toluenesulfonate in step S1, and the amount added is 36% of the mass of tryptophan ester; dibutyltin dilaurate is used as a catalyst and the amount added is 5% of the mass of tryptophan ester.

[0105] To more clearly illustrate the content of this invention, the island-type fiber composite yarns prepared and synthesized in Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3 were tested, and the relevant test results are shown in Table 1 below:

[0106] Table 1. Detection results of fiber composites prepared by different methods

[0107] Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Monofilament fineness (dtex) 0.05 0.05 0.06 0.05 Fracture strength (cN / dtex) 5.7 2.9 2.2 4.5 Elongation at break (%) 61 52 43 58 Moisture regain (%) (20℃, 65%RH) 4.6 1.3 5.1 4.2 Change rate of fracture strength (%) after soaking in 5wt% hydrochloric acid for 2 hours -8.9 -15.4 -29.5 -12.4 Change rate of fracture strength (%) after soaking in 5wt% caustic soda for 2 hours -10.3 -27.1 -39.5 -16.3

[0108] As can be clearly seen from the table, Example 1 exhibits better strength and toughness compared to the other comparative examples; it also has a higher moisture regain rate, indicating good hygroscopicity; and after soaking in acids and alkalis, it shows the smallest change in breaking strength, indicating a significant improvement in its acid and alkali resistance. Furthermore, Comparative Example 3 is a similar fiber composite filament synthesized using other amino acids (tryptophan) according to the method of Example 1 of this invention. Although it also achieved certain effects compared to traditional island fibers, overall it still does not perform as well as Example 1. This further demonstrates that the effects achieved in Example 1 of this invention are not obtained by arbitrarily replacing other amino acids with polyesterurea.

[0109] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A process for preparing PET / COPET island-of-sea fiber composite yarn, characterized in that, Includes the following steps: (1) After the polyester resin chips are subjected to crystallization treatment and drying treatment in sequence, they are mixed with the modifier, fed into the screw extruder for mixing and melting, and then fed into the spinning box after metering. This is called PET melt. (2) After the alkali-soluble polyester resin chips (COPET) are subjected to crystallization and drying treatment in sequence, they are fed into a screw extruder for melting, and then fed into the spinning box after metering. This is called COPET melt. (3) The PET melt and COPET melt are transported to the island composite component through melt pipelines, and then merged by the spinneret to form a composite melt; (4) The composite melt is sprayed into a bundle shape through the spinneret hole of the spinneret, and after cooling, oiling and winding, a fiber composite filament precursor is formed; (5) The fiber composite yarn precursor is opened in an alkaline solution, and then washed and dried to obtain PET / COPET island-type fiber composite yarn. The modifier is propyltriglyceride dipeptide-polyurethane, and its preparation method includes: S1. Peptide-1,5-pentanediol is mixed with toluene and stirred until homogeneous under magnetic stirring. Then, p-toluenesulfonic acid is added and stirred until homogeneous again. The mixture is then placed in a reflux condenser and heated to 110-130°C in an oil bath. The mixture is kept at this temperature and stirred continuously for 10-15 hours, during which water is continuously separated. After the reaction is completed, the mixture is allowed to cool naturally to room temperature. The solid in the reaction solution is filtered out and then purified by recrystallization and dried under reduced pressure to obtain peptide-1,5-pentanediol ester. The mass ratio of propionyl ester dipeptide, 1,5-pentanediol, p-toluenesulfonic acid and toluene is 11-14:3.4-5.2:12-17:

500. S2. Preparation of propionylcholine dipeptide polyurea: Acetylated dipeptide ester and N-methylpyrrolidone were mixed in a reaction flask, heated to 50-55℃, and stirred until completely dissolved. Triethylamine was then added dropwise, and the mixture was kept warm and stirred for half an hour. The temperature was then raised to 75-80℃, and dibutyltin dilaurate was added. The mixture was stirred for half an hour, and then isophorone diisocyanate was added. After stirring for 2-3 hours, 1,4-butanediamine was added, and the temperature was raised to 80-85℃. The mixture was kept warm and stirred for 6-10 hours. After the reaction was completed, the mixture was allowed to cool naturally to room temperature and poured into dichloromethane. A precipitate gradually formed. The dichloromethane containing the precipitate was then placed at 0-4℃ for 8-12 hours. The precipitate was filtered out while cold, dried, and ground into powder to obtain the modifier acetylated dipeptide polyester urea. The mass ratio of propionate dipeptide, isophorone diisocyanate, 1,4-butanediamine and N-methylpyrrolidone is 5.2-7.4:2.4-3.5:0.6-0.8:20-30; triethylamine is used to neutralize p-toluenesulfonate in step S1, and the amount added is 24%-48% of the mass of propionate dipeptide; dibutyltin dilaurate is used as a catalyst, and the amount added is 4%-6% of the mass of propionate dipeptide.

2. The preparation process of a PET / COPET island-of-sea fiber composite filament according to claim 1, characterized in that, In steps (1) and (2), the crystallization process is carried out in a fluidized bed with a crystallization residence time of 15-20 min and a temperature of 110-120℃. In steps (1) and (2), the drying process is carried out in a packed tower. The drying temperature in step (1) is 150-160℃ and the drying time is 6-8 h. The drying temperature in step (2) is 140-150℃ and the drying time is 10-12 h.

3. The preparation process of a PET / COPET island-of-sea fiber composite filament according to claim 1, characterized in that, In step (1), the mass ratio of the modifier to the polyester resin chips is 1-5:

10.

4. The preparation process of a PET / COPET island-of-sea fiber composite filament according to claim 1, characterized in that, In step (1), the temperature range of the screw extruder is 280-290℃; in step (2), the temperature range of the screw extruder is 275-280℃.

5. The preparation process of a PET / COPET island-of-sea fiber composite filament according to claim 1, characterized in that, In step (1), the polyester resin chips are polyethylene terephthalate (PET) with a viscosity of 0.674±0.01dL / g and a melting point of 258-260℃; in step (2), the alkali-soluble polyester resin chips (COPET) have a viscosity of 0.685±0.01dL / g and a melting point of 245-248℃.

6. The preparation process of a PET / COPET island-of-sea fiber composite filament according to claim 1, characterized in that, In step (3), the mass ratio of the PET melt to the COPET melt is 7~8:2~3.

7. The preparation process of a PET / COPET island-of-sea fiber composite filament according to claim 1, characterized in that, In step (4), the spinning temperature is 290℃ and the spinning speed is 800~1200m / min.

8. The preparation process of a PET / COPET island-of-sea fiber composite filament according to claim 1, characterized in that, In step (5), the concentration of the alkali solution is 12-18 g / L, the temperature is 50-60℃, and the treatment time is 30-40 min.

9. A PET / COPET island-type fiber composite filament prepared using the preparation process described in any one of claims 1-8.