阅读说明：本技术 一种可降解聚酯/聚醚嵌段共聚物、聚乳酸可降解复合纤维及其制备方法 (Degradable polyester/polyether block copolymer, polylactic acid degradable composite fiber and preparation method thereof ) 是由 兰建武 林绍建 尚娇娇 于 2021-09-10 设计创作，主要内容包括：本发明公开了一种可降解聚酯/聚醚嵌段共聚物、聚乳酸可降解复合纤维及其制备方法,属于纺织纤维技术领域,本发明中聚乳酸可降解复合纤维具有皮芯结构,皮芯结构的皮层材料为聚乳酸,皮芯结构的芯层材料为可降解聚酯/聚醚嵌段共聚物；不仅提高了PLA纤维的性能,而且可以降低其成本；相较于纯PLA纤维,本发明中具有皮芯结构的聚乳酸可降解复合纤维具有更好的力学性能,有效地解决了PLA纤维的手感、弹性、韧性差等问题。(The invention discloses a degradable polyester/polyether block copolymer, a polylactic acid degradable composite fiber and a preparation method thereof, belonging to the technical field of textile fibers, wherein the polylactic acid degradable composite fiber has a skin-core structure, the skin layer material of the skin-core structure is polylactic acid, and the core layer material of the skin-core structure is the degradable polyester/polyether block copolymer; not only the performance of the PLA fiber is improved, but also the cost can be reduced; compared with pure PLA fiber, the polylactic acid degradable composite fiber with the sheath-core structure has better mechanical property, and effectively solves the problems of poor hand feeling, elasticity, toughness and the like of the PLA fiber.)

1. A preparation method of a degradable polyester/polyether block copolymer is characterized by comprising the following steps: preparing a degradable polyester/polyether block copolymer alternately formed by a hard segment molecular compound and a soft segment molecular compound by a direct melt esterification method; wherein the hard segment molecular compound is a polyester compound, and the soft segment molecular compound is a polyether ester compound.

2. The method of claim 1, wherein the hard segment molecular compound of the degradable polyester/polyether block copolymer is polybutylene terephthalate formed from terephthalic acid and butanediol.

3. The method of claim 2, wherein the soft segment molecular compound of the degradable polyester/polyether block copolymer is composed of a polyether ester formed by reacting polytetrahydrofuran ether glycol with terephthalic acid, a polyether ester formed by reacting polyethylene oxide glycol with terephthalic acid, or a polyether ester compound formed by reacting polypropylene oxide glycol with terephthalic acid.

4. The method for preparing the degradable polyester/polyether block copolymer according to claim 3, wherein the mass ratio of the polybutylene terephthalate to the polyether ester compound is 50-80: 20 to 50.

5. The method for preparing the degradable polyester/polyether block copolymer according to claim 4, comprising the following steps:

adding terephthalic acid, 1, 4-butanediol, polyether ester compound and catalyst into a reaction vessel, directly carrying out esterification reaction for 2-4 hours at 230 ℃ under 200-100 Pa, and carrying out polycondensation reaction at 250 ℃ under 235-100 Pa under vacuum for 4-6 hours after the esterification is finished, thus obtaining the degradable polyester/polyether block copolymer.

6. The method of claim 5, wherein the catalyst is a titanate compound and is added in an amount of 0.3 to 2% by mass based on the total mass of the reactants.

7. The degradable polyester/polyether block copolymer obtained by the method for preparing the degradable polyester/polyether block copolymer according to any one of claims 1 to 6.

8. A polylactic acid degradable composite fiber, which is characterized in that the polylactic acid degradable composite fiber has a skin-core structure, wherein the skin layer material of the skin-core structure is polylactic acid, and the core layer material of the skin-core structure is the degradable polyester/polyether block copolymer of claim 7.

9. The method for preparing polylactic acid degradable composite fiber according to claim 8, comprising the steps of: and carrying out melt composite spinning on the skin layer material and the core layer material to obtain the polylactic acid degradable composite fiber.

10. The method for preparing polylactic acid degradable composite fiber according to claim 9, comprising the following steps:

step (1): slicing the skin layer material and the core layer material, and drying;

step (2): respectively carrying out melt extrusion on the skin layer material and the core layer material obtained in the step (1) through a screw extruder, and carrying out spinning, side-blowing cooling, oiling, winding, drafting and heat setting through a skin-core composite assembly to obtain polylactic acid degradable composite fibers; wherein the composite ratio of the skin layer material to the core layer material is 20-50: 50-80.

Technical Field

The invention relates to the technical field of textile fibers, in particular to a degradable polyester/polyether block copolymer, a polylactic acid degradable composite fiber and a preparation method thereof.

Background

The composite fiber is compounded by more than two polymers or the same polymers with different properties according to a certain mode. The composite fiber can be divided into sheath-core type, side-by-side type, sea-island type and other composite fibers according to the cross section and longitudinal arrangement conditions. The core-sheath composite fiber is formed by two components which are continuously arranged along the axial direction of the fiber in the form of a core-sheath structure. As one kind of composite fiber, the sheath-core structure fiber has the respective unique properties of two components, and can make up for the defect of a single component; further, the special sheath-core structure can produce certain combined effect, thereby endowing the special performance which is not possessed by single fiber.

Polylactic acid (PLA) is a high-strength biodegradable polymer material derived from renewable resources, and can be prepared by fermenting crops such as corn, wheat, cassava, beet and organic waste materials into lactic acid and polymerizing the lactic acid. PLA can be made into PLA fibers after melt spinning formation, but due to some drawbacks of polylactic acid: poor toughness, poor elastic hand feel, poor heat resistance, low impact resistance and the like, which severely limits the application of the fiber as textile fiber. In addition to the performance defects of polylactic acid, at present, the preparation of polylactic acid usually requires that lactide is synthesized from lactic acid monomers first and then the polylactic acid is prepared by ring-opening polymerization of the lactide, which results in complex polymerization process and high cost. Therefore, polylactic acid is expensive, which limits the popularization and application of this environmentally friendly material.

Disclosure of Invention

Aiming at the defects, the invention aims to provide a degradable polyester/polyether block copolymer, a polylactic acid degradable composite fiber and a preparation method thereof, which can effectively solve the problems of poor toughness, poor heat resistance, low impact resistance, high cost and the like in the existing polylactic acid composite fiber.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a preparation method of a degradable polyester/polyether block copolymer, which comprises the following steps: preparing a degradable polyester/polyether block copolymer alternately formed by a hard segment molecular compound and a soft segment molecular compound by a direct melt esterification method; wherein the hard segment molecular compound is a polyester compound, and the soft segment molecular compound is a polyether ester compound.

Further, the hard segment molecular compound is a polyester compound having a high melting point crystal type, such as polybutylene terephthalate (PBT) or the like.

The crystalline polyester compound having a high melting point in the present invention is a polyester compound having a melting point of 200 to 260 ℃ or higher.

Further, the soft segment molecular compound is a polyether ester compound having a low glass transition temperature, such as a polyether ester compound formed by polytetrahydrofuran ether glycol (PTMG), polyethylene oxide glycol (PEG), or polypropylene oxide glycol (PPG) with terephthalic acid, respectively, and the like.

The polyether ester compound having a low glass transition temperature in the present invention means a polyether ester compound having a glass transition temperature of-70 ℃ or lower.

Further, the hard segment molecular compound of the degradable polyester/polyether block copolymer is composed of polybutylene terephthalate (PBT) formed by terephthalic acid and butanediol.

Further, the soft segment molecular compound of the degradable polyester/polyether block copolymer is composed of polyether ester formed by reacting polytetrahydrofuran ether glycol (PTMG) with terephthalic acid, polyether ester formed by reacting polyethylene oxide glycol (PEG) with terephthalic acid, or polyether ester compound formed by reacting polypropylene oxide glycol (PPG) with terephthalic acid.

Further, the mass ratio of polybutylene terephthalate (PBT) to the polyether ester compound is 50-80: 20-50; preferably, the mass ratio of PBT to polyetherester compound is 70: 30.

Further, the molecular weights of polytetrahydrofuran ether glycol (PTMG), polyethylene oxide glycol (PEG) and polypropylene oxide glycol (PPG) were all 500-2500 g/mol.

Further, the soft segment of the degradable polyester/polyether block copolymer is preferably composed of a polyether ester formed by reacting polyethylene oxide glycol (PEG) having a molecular weight of 1000g/mol with terephthalic acid.

Further, the preparation method of the degradable polyester/polyether block copolymer specifically comprises the following steps:

adding terephthalic acid (TPA), 1, 4-Butanediol (BD), a polyether ester compound and a catalyst into a reaction vessel, directly carrying out esterification reaction for 2-4 hours at 230 ℃ under 200-100 Pa, and carrying out polycondensation reaction at 250 ℃ under 10-100Pa vacuum after the esterification is finished, wherein the reaction time is 4-6 hours, so as to obtain the degradable polyester/polyether block copolymer.

Further, the catalyst is titanate compound, such as butyl titanate, tetraisopropyl titanate, etc., preferably butyl titanate; the addition amount of the catalyst is 0.3-2% of the total mass of the reactants.

The invention also provides the degradable polyester/polyether block copolymer prepared by the preparation method of the degradable polyester/polyether block copolymer.

The invention provides a polylactic acid degradable composite fiber, which has a skin-core structure, wherein the skin layer material of the skin-core structure is polylactic acid, and the core layer material of the skin-core structure is the degradable polyester/polyether block copolymer.

The invention also provides a preparation method of the polylactic acid degradable composite fiber, which comprises the following steps: and carrying out melt composite spinning on the skin layer material and the core layer material to obtain the polylactic acid degradable composite fiber.

The skin layer material in the present invention is polylactic acid (PLA), and a commercially available product can be used, but is not particularly limited.

Further, the preparation method of the polylactic acid degradable composite fiber specifically comprises the following steps:

step (1): slicing the skin layer material and the core layer material, and drying;

step (2): and (2) respectively carrying out melt extrusion on the skin layer material and the core layer material obtained in the step (1) through a screw extruder, and carrying out spinning, side-blowing cooling, oiling, winding, drafting and heat setting through a skin-core composite assembly to obtain the polylactic acid degradable composite fiber.

Further, the composite ratio of the skin layer material to the core layer material is 20-50: 50-80 (mass ratio), and preferably 30-35: 60-65.

Further, the drying temperature in the step (1) is 60-100 ℃.

Further, the melt extrusion temperature of the skin layer material in the step (2) is 190-.

In summary, the invention has the following advantages:

1. the invention firstly prepares a degradable polyester/polyether block copolymer (B-TPEE), and then prepares the composite fiber with a PLA/B-TPEE skin-core structure by taking the degradable polyester/polyether block copolymer as a core layer and polylactic acid as a skin layer. The prepared PLA/B-TPEE sheath-core composite fiber has high mechanical property, good toughness and elasticity, good hand feeling, low cost and biodegradability, and can be used as a textile fabric. Meanwhile, the polyester/polyether block copolymer is also called as a polyester elastomer, and the conventional polyester/polyether block copolymer needs to be added with an antioxidant during polymerization so that the polyester/polyether block copolymer has good aging resistance and can be used as plastic or elastomer; in the invention, no antioxidant is added during polymerization, so that the prepared polyester/polyether block copolymer has degradation performance, and if the polyester/polyether block copolymer without the antioxidant is directly used as a polymer to be made into a product, the polyester/polyether block copolymer can be degraded quickly and loses mechanical properties. Therefore, the polyester/polyether block copolymer without the antioxidant can not be directly used, but the polyester/polyether block copolymer is used as a core layer and is positioned in the composite fiber, so that the polyester/polyether block copolymer is not directly contacted with air, and the degradability and the mechanical property of the polyester/polyether block copolymer are skillfully utilized.

2. The invention provides a polylactic acid degradable composite fiber, which has a skin-core structure, wherein the skin layer material of the skin-core structure is polylactic acid, and the core layer material of the skin-core structure is a block copolymer (a degradable polyester/polyether block copolymer, B-TPEE for short) formed by alternately forming a hard chain segment molecular compound and a soft chain segment molecular compound; wherein the hard segment molecular compound is a polyester compound with high melting point crystallization type, such as polybutylene terephthalate (PBT), and the soft segment molecular compound is a polyether ester compound with low glass transition temperature, such as a polyether ester compound formed by polytetrahydrofuran ether glycol (PTMG), polyethylene oxide glycol (PEG) or polypropylene oxide glycol (PPG) and terephthalic acid respectively. According to the invention, polylactic acid is used as a skin layer, and another low-cost degradable polyester/polyether block copolymer (B-TPEE for short) is used as a core layer to prepare the polylactic acid degradable composite fiber with a bi-component skin-core structure, so that the performance of the PLA fiber can be improved, and the cost of the PLA fiber can be reduced; compared with pure PLA fiber, the polylactic acid degradable composite fiber with the sheath-core structure has better mechanical property, and effectively solves the problems of poor hand feeling, elasticity, toughness and the like of the PLA fiber.

3. The invention provides a preparation method of polylactic acid degradable composite fiber, which carries out composite spinning on degradable polyester/polyether block copolymer material with lower cost and PLA, and the obtained composite fiber not only meets good biodegradability, but also effectively reduces the preparation cost. The invention effectively solves the problem that the pure PLA fiber material is limited in wide application due to complex preparation process, high slicing cost and high price.

4. The polyester/polyether block copolymer component synthesized by the method can be biodegradable, but as the material is in contact with air during storage, the molecular weight is rapidly reduced within several months, so that the mechanical property of the material is rapidly lost, and the use value of the material is rapidly lost, therefore, if the synthesized polyester/polyether block copolymer is directly used as a single component to be made into a product, the polyester/polyether block copolymer needs to be subjected to antioxidant modification to improve the weather resistance and stability of the product so as to meet the use and storage requirements of the product, but the degradation property of the product cannot be reserved. The sheath-core fiber is prepared from the polyester/polyether block copolymer and the PLA, so that the polyester/polyether block copolymer is used as the core layer of the composite fiber and does not directly contact with air, and therefore, the mechanical property and the degradation property of the composite fiber can be reserved.

Drawings

Fig. 1 is a schematic cross-sectional view of a polylactic acid degradable composite fiber with a sheath-core structure prepared by the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

Thus, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

In the example, 1mol of terephthalic acid (TPA), 1.5mol of 1,4 Butanediol (BD) and 150g of 1000 molecular weight PEG polyether are used as reaction raw materials, 0.142g of butyl titanate is added as a catalyst, esterification reaction is directly carried out for 3 hours at 210 ℃, after the esterification reaction is finished, polycondensation reaction is carried out at 245 ℃ in a 50Pa vacuum state, and the reaction time is 6 hours, so as to obtain the degradable polyester/polyether block copolymer, wherein the mass ratio of hard chain segment PBT/soft chain segment is 52.4: 47.6.

fully drying the slices of the degradable polyester/polyether block copolymer (core layer material) obtained by polymerization and the PLA (skin layer material) sold in the market at 100 ℃; then respectively melting and extruding the dried PLA and the degradable polyester/polyether block copolymer raw materials through a screw extruder, and spinning, cooling by side blowing, oiling, winding, drafting and heat setting through a sheath-core composite component to prepare the polylactic acid degradable composite fiber (PLA/B-TPEE for short) with a sheath-core structure; wherein the composite ratio of the skin layer material to the core layer material is 20:80, the melt extrusion temperature of the skin layer material is 190 ℃, and the melt extrusion temperature of the core layer material is 220 ℃.

The cross-sectional view of the polylactic acid degradable composite fiber with the sheath-core structure prepared by the embodiment is shown in fig. 1; wherein, A represents a skin layer material-PLA, and B represents a core layer material-degradable polyester/polyether block copolymer.

Example 2

In this example, 1mol of terephthalic acid (TPA), 1.5mol of 1, 4-Butanediol (BD) and 81g of 2500 m polytetrahydrofuran ether glycol (PTMG) were used as reaction raw materials, 0.192g of butyl titanate was added as a catalyst, esterification reaction was directly performed at 200 ℃ for 4 hours, and after the esterification reaction was completed, polycondensation reaction was performed at 250 ℃ in a vacuum state of 100Pa for 4 hours to obtain a degradable polyester/polyether block copolymer in which the mass ratio of hard segment PBT/soft segment was 71.4: 28.6.

fully drying the slices of the degradable polyester/polyether block copolymer (core layer material) obtained by polymerization and the PLA (skin layer material) sold in the market at 60 ℃; then respectively melting and extruding the dried PLA and the degradable polyester/polyether block copolymer raw materials through a screw extruder, and spinning, cooling by side blowing, oiling, winding, drafting and heat setting through a sheath-core composite component to prepare the polylactic acid degradable composite fiber (PLA/B-TPEE for short) with a sheath-core structure; wherein the composite ratio of the skin layer material to the core layer material is 50:50, the melt extrusion temperature of the skin layer material is 205 ℃, and the melt extrusion temperature of the core layer material is 240 ℃.

Example 3

In this example, 1mol of terephthalic acid (TPA), 1.5mol of 1, 4-Butanediol (BD) and 61g of 500 molecular weight propylene oxide glycol (PPG) were used as reaction raw materials, 0.362g of butyl titanate was used as a catalyst, and esterification was directly performed at 230 ℃ for 2 hours, after the esterification, polycondensation was performed at 235 ℃ in a vacuum state of 10Pa for 4 hours to obtain a degradable polyester/polyether block copolymer in which the mass ratio of hard segment PBT/soft segment was 71.4: 28.6.

fully drying the slices of the degradable polyester/polyether block copolymer (core layer material) obtained by polymerization and the PLA (skin layer material) sold in the market at 60 ℃; then respectively melting and extruding the dried PLA and the degradable polyester/polyether block copolymer raw materials through a screw extruder, and spinning, cooling by side blowing, oiling, winding, drafting and heat setting through a sheath-core composite component to prepare the polylactic acid degradable composite fiber (PLA/B-TPEE for short) with a sheath-core structure; wherein the composite ratio of the skin layer material to the core layer material is 45:55, the melt extrusion temperature of the skin layer material is 190 ℃, and the melt extrusion temperature of the core layer material is 220 ℃.

Example 4

In the example, 1mol of terephthalic acid (TPA), 1.5mol of 1,4 Butanediol (BD) and 150g of 1000 molecular weight PEG polyether are used as reaction raw materials, 0.42g of butyl titanate is added as a catalyst, esterification reaction is directly carried out for 3 hours at 210 ℃, after the esterification reaction is finished, polycondensation reaction is carried out at 245 ℃ in a 50Pa vacuum state, and the reaction time is 6 hours, so as to obtain the degradable polyester/polyether block copolymer, wherein the mass ratio of hard chain segment PBT/soft chain segment is 52.4: 47.6.

fully drying the slices of the degradable polyester/polyether block copolymer (core layer material) obtained by polymerization and the PLA (skin layer material) sold in the market at 100 ℃; then respectively melting and extruding the dried PLA and the degradable polyester/polyether block copolymer raw materials through a screw extruder, and spinning, cooling by side blowing, oiling, winding, drafting and heat setting through a sheath-core composite component to prepare the polylactic acid degradable composite fiber (PLA/B-TPEE for short) with a sheath-core structure; wherein the composite ratio of the skin layer material to the core layer material is 30:70, the melt extrusion temperature of the skin layer material is 190 ℃, and the melt extrusion temperature of the core layer material is 220 ℃.

Example 5

In the example, 1mol of terephthalic acid (TPA), 1.5mol of 1,4 Butanediol (BD) and 150g of 1000 molecular weight PEG polyether are used as reaction raw materials, 0.42g of butyl titanate is added as a catalyst, esterification reaction is directly carried out for 3 hours at 210 ℃, after the esterification reaction is finished, polycondensation reaction is carried out at 245 ℃ in a 50Pa vacuum state, and the reaction time is 6 hours, so as to obtain the degradable polyester/polyether block copolymer, wherein the mass ratio of hard chain segment PBT/soft chain segment is 52.4: 47.6.

fully drying the slices of the degradable polyester/polyether block copolymer (core layer material) obtained by polymerization and the PLA (skin layer material) sold in the market at 100 ℃; then respectively melting and extruding the dried PLA and the degradable polyester/polyether block copolymer raw materials through a screw extruder, and spinning, cooling by side blowing, oiling, winding, drafting and heat setting through a sheath-core composite component to prepare the polylactic acid degradable composite fiber (PLA/B-TPEE for short) with a sheath-core structure; wherein the composite ratio of the skin layer material to the core layer material is 40:60, the melt extrusion temperature of the skin layer material is 190 ℃, and the melt extrusion temperature of the core layer material is 220 ℃.

Example 6

In the example, 1mol of terephthalic acid (TPA), 1.5mol of 1,4 Butanediol (BD) and 150g of 1000 molecular weight PEG polyether are used as reaction raw materials, 0.42g of butyl titanate is added as a catalyst, esterification reaction is directly carried out for 3 hours at 210 ℃, after the esterification reaction is finished, polycondensation reaction is carried out at 245 ℃ in a 50Pa vacuum state, and the reaction time is 6 hours, so as to obtain the degradable polyester/polyether block copolymer, wherein the mass ratio of hard chain segment PBT/soft chain segment is 52.4: 47.6.

fully drying the slices of the degradable polyester/polyether block copolymer (core layer material) obtained by polymerization and the PLA (skin layer material) sold in the market at 100 ℃; then respectively melting and extruding the dried PLA and the degradable polyester/polyether block copolymer raw materials through a screw extruder, and spinning, cooling by side blowing, oiling, winding, drafting and heat setting through a sheath-core composite component to prepare the polylactic acid degradable composite fiber (PLA/B-TPEE for short) with a sheath-core structure; wherein the composite ratio of the skin layer material to the core layer material is 45:55, the melt extrusion temperature of the skin layer material is 190 ℃, and the melt extrusion temperature of the core layer material is 220 ℃.

Comparative example 1

This example provides a polylactic acid conjugate fiber which differs from example 1 only in that: poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is used as a core material, and the rest steps and parameters are the same.

Comparative example 2

This example provides a polylactic acid conjugate fiber which differs from example 1 only in that: taking the degradable polyester/polyether block copolymer obtained by polymerization as a skin layer material, and taking the PLA sold in the market as a core layer material; the rest steps and parameters are the same.

In the embodiment, the prepared degradable polyester/polyether block copolymer can be degraded quickly when contacting air, and loses mechanical property, so that the performance of the polylactic acid composite fiber is greatly reduced, and the practical application value is lost.

Examples of the experiments

In the example, the performance of examples 1-6, comparative example 1 and pure PLA fiber were tested, the test method is as shown in GB/T32366, and the specific test results are shown in Table 1.

TABLE 1

According to the invention, the polylactic acid is used as the skin layer, and the other low-cost degradable polyester/polyether block copolymer (B-TPEE for short) is used as the core layer to prepare the polylactic acid degradable composite fiber with the bi-component skin-core structure, so that the performance of the PLA fiber can be improved, and the cost of the PLA fiber can be reduced; compared with pure PLA fiber, the polylactic acid degradable composite fiber with the sheath-core structure has better mechanical property, and effectively solves the problems of poor hand feeling, elasticity and toughness, high cost and the like of the PLA fiber.

The foregoing is illustrative and explanatory only and is not intended to be exhaustive or to supplement or replace the specific embodiments described by those skilled in the art without inventive faculty.