Preparation method of biodegradable PBS parallel crimped elastic fiber

Abstract

The present application relates to a kind of preparation methods of biodegradable PBS parallel crimped elastic fiber, two kinds of polyester with different intrinsic viscosity are parallel composite spinning, two kinds of polyester with different intrinsic viscosity are PBS low viscosity branched modified polymer and PBS high viscosity blending polymer respectively;PBS low viscosity branched modified polymer is obtained by multi-arm branched agent, succinic acid, butanediol copolymerization;PBS high viscosity blending polymer is obtained by polyester flow modifier and PBS blending;The absolute value of the MFR difference of PBS low viscosity branched modified polymer and PBS high viscosity blending polymer at spinning temperature is less than 30g / 10min.The preparation method of the present application is simple and easy to operate, easy to industrial production, and the raw materials used in processing are environment-friendly, the fiber finally obtained is processed smoothly, and the spinnability and crimped elasticity are better, and widely used.

Description

Technical Field

[0001] This invention belongs to the field of materials and textile applications, and relates to a method for preparing biodegradable PBS side-by-side crimped elastic fibers. Background Technology

[0002] Synthetic fibers are fibers produced by melting or solvent spinning artificially synthesized polymers with suitable molecular weights. As an important branch of chemical fibers, synthetic fibers have evolved over decades to include fiber materials with diverse properties, such as polyester, nylon, acrylic, and spandex. With the continuous improvement of living standards, people have increasingly higher requirements for clothing fibers. Among the many functional and differentiated fibers, elastic fabrics with excellent human comfort are widely used in textile fields such as leisure, sports, underwear, and medical and health care.

[0003] Elastic fibers can be classified into diene elastic fibers (commonly known as rubber), polyurethane fibers, polyolefin elastic fibers, and polyester bicomponent composite elastic fibers according to their chemical structure and elasticity principle. Bicomponent composite bicomponent fibers are a new type of elastic fiber developed in recent years and occupy an important position in the market. The formation mechanism of bicomponent composite bicomponent fibers is due to the difference in thermal shrinkage properties of the two components during heat processing, resulting in a unique three-dimensional self-crimping structure similar to wool. The fabrics made from this fiber have a fluffy appearance, a soft feel, and good elasticity and resilience. Compared to traditional methods that require multiple processes such as stretching, winding, and texturing to obtain the crimped structure, the production process of bicomponent bicomponent composite elastic fibers is shorter, significantly reducing production costs, and avoiding the impact of multiple heat texturing processes on the fiber's mechanical strength. Therefore, the development of bicomponent bicomponent composite fibers has been very rapid. DuPont's T400 is currently the most widely used bicomponent composite elastic fiber, made from polyethylene terephthalate (PET) and polypropylene terephthalate (PTT). T400 is known as "ammonia-free elastic fiber" primarily because of its high elastic recovery. It can replace spandex in many applications, imparting elasticity to fabrics and avoiding numerous problems associated with adding spandex, such as dyeing difficulties, excessive elasticity, fabric dimensional instability, and easy aging. With increasing global emphasis on environmental protection in recent years, the development of bio-based and biodegradable materials holds great potential for developing low-carbon new materials and addressing the long-term environmental impact of microplastics. In recent years, researchers have also begun to explore new applications for fibers based on polymers such as polyethylene 2,5-furandicarboxylate (PEF), polylactic acid (PLA), polybutylene succinate (PBS), and polybutylene adipate terephthalate (PBAT).

[0004] Based on the preparation principle of the above-mentioned parallel composite fibers, the two components of the parallel composite are usually made of different types of fibers, such as the composite of PET and PTT in T400. New types of fibers can also be used for composites. For example, patent CN115467045A discloses a fully bio-based biodegradable composite elastic fiber and its preparation method. This patent uses PLA and PBAT as raw materials to prepare a fully bio-based biodegradable composite elastic fiber with a tensile strength ≥2.5 cN / dtex. However, when using two different polymers for parallel composites, two key problems are usually encountered: First, the two components may have poor compatibility, resulting in low interfacial bonding strength and easy fiber peeling under external force; second, due to their different structures, the two parallel components have different dyeing speeds, often leading to mismatched dyeing temperatures and uneven fiber dyeing. For example, the dyeing temperature of the PTT component in T400 fiber is lower, 20°C lower than that of PET. PTT is easier to dye and has a faster dyeing speed, but in subsequent dyeing processes, T400 fiber often faces uneven dyeing problems.

[0005] Regarding the first question, patent CN115467045A discloses a fully bio-based biodegradable composite elastic fiber and its preparation method. This patent modifies PLA polymer by blending it with aliphatic polyester PBA, and adds toluene diisocyanate (2,4-TDI) in the PLA and PBAT parallel composite fiber forming stage to connect the polymers in the form of covalent bonds. However, this method is experimentally complex and costly.

[0006] Regarding the second question, existing technologies must be improved through methods such as low-temperature dyeing, slow heating, and controlled heat preservation, while also controlling the dyeing temperature and time processes to develop dyeing technology.

[0007] To address the aforementioned issues, researchers have further considered using different specifications of the same polymer to prepare side-by-side composite fibers. For example, the literature "Preparation and Structural Properties Study of High and Low Viscosity PET Side-by-Side Composite Fibers" discloses the development of side-by-side composite fibers using two PET polyesters with different intrinsic viscosities (intrinsic viscosities of 0.5 dL / g and 0.9 dL / g, respectively) as raw materials. This literature utilizes the high viscosity difference between the two components, which causes them to curl due to their different shrinkage after being subjected to stress or heat. When the ratio of the two components is 50:50, the prepared side-by-side composite fiber exhibits high mechanical strength (breaking strength reaches 2.57 cN / dtex) and excellent curl elasticity, with a curl rate of 22.64% and a curl elasticity rate exceeding 90%, while also showing relatively uniform dyeing. The paper "Three-dimensional crimped biodegradable poly(lactic acid) fibers prepared via melt spinning and controlled structural reorganization" describes the preparation of a fully polylactic acid-based biodegradable side-by-side composite fiber using biodegradable polylactic acid (PLA) and low-melting-point polylactic acid (LM-PLA). The prepared fiber has a strength of 3.32 cN / dtex, a crimp rate of 31.9%, and a crimp elasticity of over 80%.

[0008] Polybutylene succinate (PBS) is an aliphatic bio-based biodegradable polyester that has seen rapid development in recent years. It possesses excellent comprehensive properties, and due to its good crystallinity and fiber-forming properties, PBS shows great promise in the fiber industry. However, because its melting point is only 110-120℃, its thermal properties differ significantly from conventional polyesters such as PET, PTT, PBT, and PLA. During spinning, due to differences in flowability, a "thick-on-thick" phenomenon occurs during composite spinning, making it difficult to perform parallel composite spinning with the aforementioned polyesters when developing parallel composite fibers. When using two PBS matrices with a certain viscosity difference, because its linear macromolecules are aliphatic chains, the intermolecular interactions are lower than those of PET polyester, resulting in a lower melt viscosity and a narrower processing window. When using high- and low-viscosity composite spinning, the significant difference in forming temperature makes it difficult to simply control the temperature to adjust the flowability and achieve the preparation of parallel crimped elastic fibers. Summary of the Invention

[0009] The purpose of this invention is to solve the problems existing in the prior art and provide a method for preparing biodegradable PBS side-by-side crimped elastic fibers. This invention uses branching technology to control and reduce the MFR (melt flow rate) of low-viscosity PBS, and uses flow technology to control and increase the MFR of high-viscosity PBS, so that the flow states of high-viscosity PBS and low-viscosity PBS are similar during spinning, thereby solving the problem of PBS being temperature sensitive and having a narrow processing window. The biodegradable PBS side-by-side crimped elastic fibers prepared by this invention have a better crimp shrinkage rate.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0011] A method for preparing biodegradable PBS side-by-side crimped elastic fibers involves side-by-side composite spinning of two polyesters with different intrinsic viscosities, namely a low-viscosity branched modified polymer of PBS and a high-viscosity blended polymer of PBS.

[0012] The low-viscosity branched modified polymer of PBS is obtained by copolymerization of multi-arm branching agent, succinic acid, and butanediol; the high-viscosity blended polymer of PBS is obtained by blending polyester flow modifier with PBS.

[0013] The absolute value of the difference in MFR between the low-viscosity branched modified polymer and the high-viscosity blended polymer of PBS at the spinning temperature is less than 30 g / 10 min. This can meet the requirements of parallel composite spinning and ensure that parallel composite spinning can be carried out smoothly. The absolute value of the difference in MFR between the low-viscosity branched modified polymer and the high-viscosity blended polymer of PBS at the same temperature should not be too large, otherwise phenomena such as "thin covering thick" will occur.

[0014] As a preferred technical solution:

[0015] The preparation method of biodegradable PBS side-by-side crimped elastic fibers as described above uses glycerol, pentaerythritol, diglycerol or dipentaerythritol as a multi-arm branching agent to regulate the processing flowability of the low-viscosity branched modified polymer of PBS.

[0016] The preparation process of PBS low-viscosity branched modified polymer is as follows: succinic acid, butanediol, multi-arm branching agent, and auxiliaries (antioxidant, catalyst, heat stabilizer, etc.) are mixed and first esterified at 180-200℃ and 0.1MPa for 4-6 hours. Then, the temperature is raised to 230-250℃ and vacuum polycondensation is carried out at a pressure ≤50Pa until the discharge power is reached, thus obtaining the PBS low-viscosity branched modified polymer. The molar ratio of succinic acid to butanediol is 1:1.1-1.3, and the amount of multi-arm branching agent added is 0.1%-3.0% of the molar amount of succinic acid.

[0017] The type of multi-arm branching agent and the proportion of multi-arm branching agent in the low-viscosity branched modified PBS polymer jointly determine the MFR of the low-viscosity branched modified PBS polymer. Among them, controlling the amount of multi-arm branching agent added to 0.1%-3.0% of the molar amount of succinic acid can make PBS undergo micro-crosslinking, while avoiding excessive addition and gelation.

[0018] The method for preparing biodegradable PBS side-by-side crimped elastic fibers as described above, wherein the intrinsic viscosity of the PBS low-viscosity branched modified polymer is 0.8-1.3 dL / g, and the number-average molecular weight is 2.0 × 10⁻⁶. 4 -5.0×10 4 The number-average molecular weight should not be too high, otherwise the shrinkage difference between the two polyesters with different intrinsic viscosities will not be significant, and the elasticity and crimp shrinkage rate of the prepared parallel crimped elastic fibers will not be high.

[0019] In the preparation method of biodegradable PBS side-by-side crimped elastic fiber as described above, the polyester flow modifier is a bio-based polyester flow modifier.

[0020] The preparation method of biodegradable PBS side-by-side crimped elastic fiber as described above, wherein the bio-based polyester flow modifier is isosorbide oligomer or furan dicarboxylic acid oligomer, used to regulate the processing flowability of the PBS high viscosity blend polymer, with a degree of polymerization ranging from 10 to 20.

[0021] When preparing high-viscosity PBS blends, the mass ratio of bio-based polyester flow modifier to PBS is 5-20:95-80. The intrinsic viscosity of PBS is 1.4-1.8 dL / g, and the number-average molecular weight is 7.0 × 10⁻⁶. 4 -14.0×10 4 g / mol;

[0022] The type of bio-based polyester flow modifier, the mass ratio of the bio-based polyester flow modifier to PBS, and the molecular weight of PBS together determine the MFR of the PBS high-viscosity blend polymer.

[0023] In the preparation method of biodegradable PBS side-by-side crimped elastic fibers as described above, the isosorbide oligomer is isosorbide succinate oligomer, isosorbide glutarate oligomer, or isosorbide adipate oligomer; and the furanyl dicarboxylic acid oligomer is butylene furanyl dicarboxylate oligomer, pentylene furanyl dicarboxylate oligomer, or hexylene furanyl dicarboxylate oligomer.

[0024] In the preparation method of biodegradable PBS side-by-side crimped elastic fibers as described above, the composite ratio of PBS low-viscosity branched modified polymer and PBS high-viscosity blended polymer is 3:7-7:3.

[0025] As described above, a method for preparing biodegradable PBS parallel crimped elastic fibers involves drying two polyesters with different intrinsic viscosities to a moisture content ≤50ppm before parallel composite spinning. The drying method and conditions are not limited; for example, a vacuum drum can be used for drying at a temperature of 90℃ for 12-48 hours. The reason for controlling the moisture content to ≤50ppm is that polyester polymers are prone to hydrolysis during spinning, which reduces the molecular weight and leads to a decrease in the quality of the fibers. In particular, if water vapor is trapped in the monofilament, it is easy to form "bubble fibers," causing fuzz and breakage.

[0026] The preparation method of biodegradable PBS parallel crimped elastic fiber as described above involves the following parallel composite spinning process: two polyesters with different intrinsic viscosities are fed into the spinning system, melted, filtered, and then quantitatively output into the composite spinning assembly via a metering pump, where they converge at the spinneret to form a parallel composite fiber structure; the parallel composite spinning process flow is as follows: melt spinning → side blowing cooling → oiling (the oiling agent is coated on the surface of the composite fiber bundle by a rotating oiling wheel to improve its subsequent processability) → winding → stretching → heat setting.

[0027] The preparation method of biodegradable PBS parallel crimped elastic fiber as described above includes the following process parameters for parallel composite spinning: spinning speed 600-2000 m / min, side blowing temperature 0-30℃, cooling air relative humidity 65-85%, side blowing speed 0.3-1.0 m / min, stretching ratio 1.5-3.0 times, heat setting temperature 60-90℃, and the number of spinnerets with spinnerets used for spinning is 28-144.

[0028] The preparation method of biodegradable PBS parallel-curled elastic fiber as described above shows that the interface of the biodegradable PBS parallel-curled elastic fiber is not obvious under a microscope, and no phase separation phenomenon is observed. The breaking strength of the biodegradable PBS parallel-curled elastic fiber is 2.4-3.5 cN / dtex, the breaking elongation is 25-50%, and the crimp elasticity is 70-95%. Under sufficient raw material conditions, it can be spun continuously for 12 hours without breakage.

[0029] The principle of this invention is as follows:

[0030] The MFR curves of high-viscosity PBS and low-viscosity PBS as a function of temperature are shown below. Figure 1As shown in the figure, PBS is a temperature-sensitive material. The molecular weight flow rate (MFR) of both high-viscosity and low-viscosity PBS increases with increasing temperature, meaning that the fluidity increases with temperature. Under the same test temperature conditions, the MFR of low-viscosity PBS is significantly larger than that of high-viscosity PBS, indicating that low-viscosity PBS has better fluidity than high-viscosity PBS. This is because the relative molecular mass of low-viscosity PBS is smaller than that of high-viscosity PBS, resulting in less molecular chain entanglement and making it easier for molecular chains to move. In the existing technology, PBS cannot be used to produce parallel-crimped elastic fibers through parallel composite spinning. The fundamental reason is that the fluidity difference between high-viscosity and low-viscosity PBS is too large, that is, the absolute value of the MFR difference at the same temperature is too large. The MFR of high-viscosity PBS is too small, and the MFR of low-viscosity PBS is too large. This leads to a "thickening around thinning" phenomenon when the two are combined in parallel in a two-component composite spinning process due to the difference in melt fluidity, making composite spinning impossible.

[0031] This invention improves the MFR of high-viscosity PBS while reducing the MFR of low-viscosity PBS, thereby controlling the absolute value of the MFR difference between the low-viscosity branched modified PBS polymer and the high-viscosity PBS blend polymer at the same temperature to be less than 30 g / 10 min.

[0032] To reduce the mean square radius of gyration (MFR) of low-viscosity PBS, this invention introduces a multi-arm branching agent into the molecular chain of low-viscosity PBS through copolymerization. The addition of this multi-arm branching agent alters the polymer's molecular chain structure; the MFR of the branched molecular chains is smaller than that of the linear molecular chains, resulting in a more compact molecular chain structure, increased molecular entanglement, and reduced polymer flow properties. The results are as follows: Figure 1 As shown.

[0033] To improve the flow rate (MFR) of high-viscosity PBS, this invention adds a certain amount of polyester flow modifier. This modifier, through small molecule insertion between polymer chains, weakens the intermolecular attraction, increases the distance between chains, increases the mobility of polymer chains, reduces entanglement between polymer chains, and improves the flow properties of the polymer. The results are as follows: Figure 1 As shown.

[0034] In summary, this invention, through branching and flow control techniques, can make the flow states of high-viscosity PBS and low-viscosity PBS similar during spinning, thus meeting the requirements for parallel melt spinning.

[0035] Beneficial effects:

[0036] (1) The present invention provides a method for preparing biodegradable PBS parallel crimped elastic fibers, which is simple and easy to operate, can be spun using a composite spinning device, and can be industrialized.

[0037] (2) The present invention provides a method for preparing biodegradable PBS parallel-curled elastic fibers, which uses renewable and biodegradable raw materials and is an environmentally friendly material.

[0038] (3) The present invention provides a method for preparing biodegradable PBS parallel crimped elastic fibers, which uses PBS with high and low viscosity that have thermal shrinkage differences. The melt preparation has high crimping performance. The polymer flowability is controlled by branching and flow technology, which solves the problem of PBS melt spinning and the inability to spin due to large flowability differences.

[0039] (4) The biodegradable PBS parallel-curl elastic fiber prepared by the preparation method of the present invention has a breaking strength of 2.4-3.5 cN / dtex, a breaking elongation of 25-50%, and a crimp elasticity of 70-95%, and can be used in elastic fiber application fields such as clothing and household use. Attached Figure Description

[0040] Figure 1 A diagram illustrating the effect of the strategy and method of this invention on polymer flowability;

[0041] Figure 2 This is a schematic diagram of the parallel crimped elastic fiber monofilaments of the biodegradable PBS of the present invention;

[0042] Figure 3 This is a schematic cross-sectional view of the side-by-side crimped elastic fibers of the biodegradable PBS of the present invention;

[0043] Figure 4 This is a schematic diagram of the biodegradable PBS side-by-side coiled elastic fibers of the present invention. Detailed Implementation

[0044] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0045] The following are the sources of some of the raw materials used in the examples:

[0046] Isosorbide succinate oligomer: self-made, its preparation process is as follows: it is prepared by melting isosorbide and succinic acid, the alcohol-acid ratio is 1.2:1, the reaction temperature is 180℃, and the reaction time is 4 hours;

[0047] Isosorbide glutarate oligomer: prepared in-house, the preparation process is as follows: prepared by melting isosorbide and glutaric acid, the alcohol-acid ratio is 1.2:1, the reaction temperature is 180℃, and the reaction time is 4 hours;

[0048] Isosorbide adipate oligomer: prepared in-house, the preparation process is as follows: prepared by melting isosorbide and adipic acid, the alcohol-acid ratio is 1.2:1, the reaction temperature is 180℃, and the reaction time is 4 hours;

[0049] Butylene difuranate oligomer: self-made, its preparation process is as follows: it is prepared by melting furan dicarboxylic acid and butanediol, the alcohol-acid ratio is 1.2:1, the reaction temperature is 180℃, and the reaction time is 4 hours;

[0050] Pentylene difuranate oligomer: self-made, its preparation process is as follows: it is prepared by melting furan dicarboxylic acid and pentylene glycol, the alcohol-acid ratio is 1.2:1, the reaction temperature is 180℃, and the reaction time is 4 hours;

[0051] Hexanediol furanate oligomer: self-made, its preparation process is as follows: it is prepared by melting furanate and hexanediol, the alcohol-acid ratio is 1.2:1, the reaction temperature is 180℃, and the reaction time is 4 hours.

[0052] The following are the performance testing methods described in the examples:

[0053] Intrinsic viscosity: The intrinsic viscosity of the polymer was determined using an Ubbelohde viscometer at 25 ± 0.1 °C, with the intrinsic viscosity in a mixed solvent of phenol and 1,1,2,2-tetrachloroethane (1:1 w / w) at a polymer concentration of 0.50 g·dL. -1 ;

[0054] Number-average molecular weight: The molecular weight of the polyester was determined using a 1260 Infinity II (Agilent Technologies) gel permeation chromatograph. The mobile phase was hexafluoroisopropanol, and the flow rate was 0.3 mL / min. -1 ;

[0055] Breaking strength and elongation at break: The XL-1 multifilament strength tester was used for testing. The fiber holding length was 200 mm, the stretching rate was 200 mm / min, the pre-tension was 5 cN, and each group of samples was tested 15 times. The average value was taken to obtain the breaking strength and elongation at break of the fiber.

[0056] Curvature elasticity (J) d The following tests were conducted on a portion of the composite fiber with relatively uniform crimp (randomly cut lengths). One monofilament was taken, and its length L0 was measured after 30 seconds under a light load. After removing the light load and applying a heavy load for 30 seconds, its length L1 was measured. After removing the heavy load and allowing the fiber to recover naturally for 2 minutes, its length L2 was measured again under a light load. The formula for calculating the crimp elasticity is:

[0057] MFR: The MFR of the sample was tested using a melt flow indexer according to the national standard test method GB / T 3682-2018; the standard load was selected as 2.16 kg, and the mass of 5 bubble-free sample segments was weighed at the test temperature. The MFR (g / 10min) was calculated according to the following formula.

[0058]

[0059] In the formula, T is the experimental temperature (°C), and m nom The nominal load is 600 (kg), the conversion factor is 600, the average cutting mass is 600 (g), and the cutting time interval is 600 (s).

[0060] In this invention, the parameters such as esterification temperature, esterification reaction time, polycondensation reaction temperature, polycondensation reaction pressure, and the molar ratio of succinic acid to butanediol are conventional parameters for preparing PBS, and their specific values ​​are not significantly different from those in the prior art. This invention only selects a set of optimal parameters for illustration. Specifically, the esterification temperature is 190℃, the esterification reaction time is 5h, the esterification reaction pressure is 0.1MPa, the polycondensation reaction temperature is 230℃, the polycondensation reaction pressure is ≤50Pa, and the molar ratio of succinic acid to butanediol is 1:1.2.

[0061] In this invention, the side-blowing temperature, cooling air relative humidity, side-blowing speed, stretching ratio, and heat setting temperature are conventional process parameters for preparing parallel composite spinning. The specific values ​​are not significantly different from those in the prior art. This invention only selects a set of optimal parameters for illustration. Specifically, the side-blowing temperature is 25°C, the cooling air relative humidity is 80%, the side-blowing speed is 0.53 m / min, the stretching ratio is 3.0 times, and the heat setting temperature is 80°C.

[0062] Example 1

[0063] A method for preparing biodegradable PBS side-by-side crimped elastic fibers, comprising the following steps:

[0064] (1) Preparation of raw materials;

[0065] Multi-branching agent: Glycerin;

[0066] Succinic acid;

[0067] Butylene glycol;

[0068] Additives: Composed of antioxidant (Irganox 1010), catalyst (tetrabutyl titanate), and heat stabilizer (triphenyl phosphite);

[0069] Polyester flow modifier: isosorbide succinate oligomer;

[0070] PBS: intrinsic viscosity 1.4 dL / g, number-average molecular weight 7 × 10⁻⁶ 4 g / mol;

[0071] (2) Preparation of low-viscosity branched modified polymer for PBS;

[0072] Succinic acid, butanediol, multi-arm branching agent, and additives were mixed and esterified for 5 hours at 190℃ and 0.1MPa. Then, the temperature was raised to 230℃ and vacuum polycondensation was carried out at ≤50Pa until the discharge power was reached, thus obtaining the low-viscosity branched modified polymer of PBS. The molar ratio of succinic acid to butanediol was 1:1.2, the amount of multi-arm branching agent added was 3% of the molar weight of succinic acid, the amount of catalyst added was 0.1% of the mass of succinic acid, the amount of antioxidant added was 0.5% of the mass of succinic acid, and the amount of heat stabilizer added was 0.5% of the mass of succinic acid.

[0073] The final prepared low-viscosity branched modified PBS polymer had an intrinsic viscosity of 0.8 dL / g and a number-average molecular weight of 2 × 10⁻⁶. 4 g / mol;

[0074] (3) Preparation of PBS high-viscosity blend polymer;

[0075] A high-viscosity PBS blend polymer was obtained by blending a polyester flow modifier at a mass ratio of 5:95 with PBS.

[0076] (4) Preparation of biodegradable PBS parallel-curled elastic fibers;

[0077] The low-viscosity branched modified PBS polymer obtained in step (2) and the high-viscosity blended PBS polymer obtained in step (3) are dried to a moisture content of ≤50ppm, and then parallel composite spinning is carried out to obtain biodegradable PBS parallel crimped elastic fiber; wherein, the composite ratio of the low-viscosity branched modified PBS polymer and the high-viscosity blended PBS polymer is 3:7.

[0078] The process flow of parallel composite spinning: melt spinning → side blowing cooling → oiling → winding → stretching → heat setting;

[0079] The process parameters for parallel composite spinning are as follows: the temperature of the two twin-screw spinning machines is set to 180℃, the spinning speed is 600m / min, the side blowing temperature is 25℃, the relative humidity of the cooling air is 80%, the side blowing speed is 0.53m / min, the stretching ratio is 3.0 times, the heat setting temperature is 80℃, and the number of spinnerets on the spinneret used for spinning is 28.

[0080] At the spinning temperature, the MFRs of the PBS low-viscosity branched modified polymer and the PBS high-viscosity blend polymer were 90 g / 10 min and 70 g / 10 min, respectively.

[0081] The final biodegradable PBS produced consists of side-by-side crimped elastic fibers, such as... Figure 4 As shown, its fiber monofilaments are as follows Figure 2 As shown, the cross-section of the fiber is as follows Figure 3 As shown, the fiber prepared by it has a breaking strength of 2.4 cN / dtex, a breaking elongation of 50%, and a crimp elasticity of 80%. It can be spun continuously for 12 hours without breaking when there is sufficient raw material.

[0082] Example 2

[0083] A method for preparing biodegradable PBS side-by-side crimped elastic fibers, comprising the following steps:

[0084] (1) Preparation of raw materials;

[0085] Multi-branching agent: Glycerin;

[0086] Succinic acid;

[0087] Butylene glycol;

[0088] Additives: Composed of antioxidant (Irganox 1010), catalyst (tetrabutyl titanate), and heat stabilizer (triphenyl phosphite);

[0089] Polyester flow modifier: isosorbide glutarate oligomer;

[0090] PBS: intrinsic viscosity 1.5 dL / g, number-average molecular weight 8.5 × 10⁻⁶ 4 g / mol;

[0091] (2) Preparation of low-viscosity branched modified polymer for PBS;

[0092] Succinic acid, butanediol, multi-arm branching agent, and additives were mixed and esterified for 5 hours at 190℃ and 0.1MPa. Then, the temperature was raised to 230℃ and vacuum polycondensation was carried out at ≤50Pa until the discharge power was reached, thus obtaining the low-viscosity branched modified polymer of PBS. The molar ratio of succinic acid to butanediol was 1:1.2, the amount of multi-arm branching agent added was 1% of the molar weight of succinic acid, the amount of catalyst added was 0.1% of the mass of succinic acid, the amount of antioxidant added was 0.5% of the mass of succinic acid, and the amount of heat stabilizer added was 0.5% of the mass of succinic acid.

[0093] The final prepared low-viscosity branched modified PBS polymer had an intrinsic viscosity of 0.9 dL / g and a number-average molecular weight of 3 × 10⁻⁶. 4 g / mol;

[0094] (3) Preparation of PBS high-viscosity blend polymer;

[0095] A high-viscosity PBS blend polymer was obtained by blending a polyester flow modifier at a mass ratio of 5:95 with PBS.

[0096] (4) Preparation of biodegradable PBS parallel-curled elastic fibers;

[0097] The low-viscosity branched modified PBS polymer obtained in step (2) and the high-viscosity blended PBS polymer obtained in step (3) are dried to a moisture content of ≤50ppm, and then parallel composite spinning is carried out to obtain biodegradable PBS parallel crimped elastic fiber; wherein, the composite ratio of low-viscosity branched modified PBS polymer and high-viscosity blended PBS polymer is 4:6.

[0098] The process flow of parallel composite spinning: melt spinning → side blowing cooling → oiling → winding → stretching → heat setting;

[0099] The process parameters for parallel composite spinning are as follows: the temperature of the two twin-screw spinning machines is set at 190℃, the spinning speed is 1000m / min, the side blowing temperature is 25℃, the relative humidity of the cooling air is 80%, the side blowing speed is 0.53m / min, the stretching ratio is 3.0 times, the heat setting temperature is 80℃, and the number of spinnerets on the spinneret used for spinning is 36.

[0100] At the spinning temperature, the MFRs of the PBS low-viscosity branched modified polymer and the PBS high-viscosity blend polymer were 85 g / 10 min and 65 g / 10 min, respectively.

[0101] The resulting biodegradable PBS side-by-side crimped elastic fiber has a breaking strength of 2.6 cN / dtex, a breaking elongation of 45%, and a crimp elasticity of 85%. It can be spun continuously for 12 hours without breakage when there is sufficient raw material.

[0102] Example 3

[0103] A method for preparing biodegradable PBS side-by-side crimped elastic fibers, comprising the following steps:

[0104] (1) Preparation of raw materials;

[0105] Multi-branching agent: Pentaerythritol;

[0106] Succinic acid;

[0107] Butylene glycol;

[0108] Additives: Composed of antioxidant (Irganox 1010), catalyst (tetrabutyl titanate), and heat stabilizer (triphenyl phosphite);

[0109] Polyester flow modifier: isosorbide adipate oligomer;

[0110] PBS: intrinsic viscosity 1.5 dL / g, number-average molecular weight 8.5 × 10⁻⁶ 4 g / mol;

[0111] (2) Preparation of low-viscosity branched modified polymer for PBS;

[0112] Succinic acid, butanediol, multi-arm branching agent, and additives were mixed and esterified for 5 hours at 190℃ and 0.1MPa. Then, the temperature was raised to 230℃ and vacuum polycondensation was carried out at ≤50Pa until the discharge power was reached, thus obtaining the low-viscosity branched modified polymer of PBS. The molar ratio of succinic acid to butanediol was 1:1.2, the amount of multi-arm branching agent added was 1% of the molar weight of succinic acid, the amount of catalyst added was 0.1% of the mass of succinic acid, the amount of antioxidant added was 0.5% of the mass of succinic acid, and the amount of heat stabilizer added was 0.5% of the mass of succinic acid.

[0113] The final prepared low-viscosity branched modified PBS polymer had an intrinsic viscosity of 1.0 dL / g and a number-average molecular weight of 3.5 × 10⁻⁶. 4 g / mol;

[0114] (3) Preparation of PBS high-viscosity blend polymer;

[0115] A high-viscosity PBS blend polymer was obtained by blending a polyester flow modifier at a mass ratio of 10:90 with PBS.

[0116] (4) Preparation of biodegradable PBS parallel-curled elastic fibers;

[0117] The low-viscosity branched modified PBS polymer obtained in step (2) and the high-viscosity blended PBS polymer obtained in step (3) are dried to a moisture content of ≤50ppm, and then parallel composite spinning is performed to obtain biodegradable PBS parallel crimped elastic fiber; wherein, the composite ratio of the low-viscosity branched modified PBS polymer and the high-viscosity blended PBS polymer is 5:5.

[0118] The process flow of parallel composite spinning: melt spinning → side blowing cooling → oiling → winding → stretching → heat setting;

[0119] The process parameters for parallel composite spinning are as follows: the temperature of the two twin-screw spinning machines is set to 200℃, the spinning speed is 1500m / min, the side blowing temperature is 25℃, the relative humidity of the cooling air is 80%, the side blowing speed is 0.53m / min, the stretching ratio is 3.0 times, the heat setting temperature is 80℃, and the number of spinnerets on the spinneret used for spinning is 72.

[0120] At the spinning temperature, the MFRs of the PBS low-viscosity branched modified polymer and the PBS high-viscosity blend polymer were 80 g / 10 min and 70 g / 10 min, respectively.

[0121] The final biodegradable PBS side-by-side crimped elastic fiber has a breaking strength of 2.7 cN / dtex, a breaking elongation of 40%, and a crimp elasticity of 80%. It can be spun continuously for 12 hours without breakage when there is sufficient raw material.

[0122] Example 4

[0123] A method for preparing biodegradable PBS side-by-side crimped elastic fibers, comprising the following steps:

[0124] (1) Preparation of raw materials;

[0125] Multi-branching agent: Pentaerythritol;

[0126] Succinic acid;

[0127] Butylene glycol;

[0128] Additives: Composed of antioxidant (Irganox 1010), catalyst (tetrabutyl titanate), and heat stabilizer (triphenyl phosphite);

[0129] Polyester flow modifier: Butylene difuranate oligomer;

[0130] PBS: intrinsic viscosity 1.6 dL / g, number-average molecular weight 10 × 10⁻⁶ 4 g / mol;

[0131] (2) Preparation of low-viscosity branched modified polymer for PBS;

[0132] Succinic acid, butanediol, multi-arm branching agent, and additives were mixed and esterified for 5 hours at 190℃ and 0.1 MPa. Then, the temperature was raised to 230℃ and vacuum polycondensation was carried out at ≤50 Pa until the discharge power was reached, thus obtaining the low-viscosity branched modified polymer of PBS. The molar ratio of succinic acid to butanediol was 1:1.2, the amount of multi-arm branching agent added was 0.5% of the molar weight of succinic acid, the amount of catalyst added was 0.1% of the mass of succinic acid, the amount of antioxidant added was 0.5% of the mass of succinic acid, and the amount of heat stabilizer added was 0.5% of the mass of succinic acid.

[0133] The final prepared low-viscosity branched modified PBS polymer had an intrinsic viscosity of 1.1 dL / g and a number-average molecular weight of 4 × 10⁻⁶. 4 g / mol;

[0134] (3) Preparation of PBS high-viscosity blend polymer;

[0135] A high-viscosity PBS blend polymer was obtained by blending a polyester flow modifier at a mass ratio of 10:90 with PBS.

[0136] (4) Preparation of biodegradable PBS parallel-curled elastic fibers;

[0137] The low-viscosity branched modified PBS polymer obtained in step (2) and the high-viscosity blended PBS polymer obtained in step (3) are dried to a moisture content of ≤50ppm, and then parallel composite spinning is carried out to obtain biodegradable PBS parallel crimped elastic fiber; wherein, the composite ratio of the low-viscosity branched modified PBS polymer and the high-viscosity blended PBS polymer is 6:4.

[0138] The process flow of parallel composite spinning: melt spinning → side blowing cooling → oiling → winding → stretching → heat setting;

[0139] The process parameters for parallel composite spinning are as follows: the temperature of the two twin-screw spinning machines is set at 210℃, the spinning speed is 1500m / min, the side blowing temperature is 25℃, the relative humidity of the cooling air is 80%, the side blowing speed is 0.53m / min, the stretching ratio is 3.0 times, the heat setting temperature is 80℃, and the number of spinnerets on the spinneret used for spinning is 72.

[0140] At the spinning temperature, the MFRs of the PBS low-viscosity branched modified polymer and the PBS high-viscosity blend polymer were 80 g / 10 min and 80 g / 10 min, respectively.

[0141] The final biodegradable PBS side-by-side crimped elastic fiber has a breaking strength of 3.0 cN / dtex, a breaking elongation of 35%, and a crimp elasticity of 85%. It can be spun continuously for 12 hours without breakage when there is sufficient raw material.

[0142] Example 5

[0143] A method for preparing biodegradable PBS side-by-side crimped elastic fibers, comprising the following steps:

[0144] (1) Preparation of raw materials;

[0145] Multi-branching agent: diglycerides;

[0146] Succinic acid;

[0147] Butylene glycol;

[0148] Additives: Composed of antioxidant (Irganox 1010), catalyst (tetrabutyl titanate), and heat stabilizer (triphenyl phosphite);

[0149] Polyester flow modifier: Pentylene furanate oligomer;

[0150] PBS: intrinsic viscosity 1.7 dL / g, number-average molecular weight 12 × 10⁻⁶ 4 g / mol;

[0151] (2) Preparation of low-viscosity branched modified polymer for PBS;

[0152] Succinic acid, butanediol, multi-arm branching agent, and additives were mixed and esterified for 5 hours at 190℃ and 0.1MPa. Then, the temperature was raised to 230℃ and vacuum polycondensation was carried out at ≤50Pa until the discharge power was reached, thus obtaining the low-viscosity branched modified polymer of PBS. The molar ratio of succinic acid to butanediol was 1:1.2, the amount of multi-arm branching agent added was 0.2% of the molar weight of succinic acid, the amount of catalyst added was 0.1% of the mass of succinic acid, the amount of antioxidant added was 0.5% of the mass of succinic acid, and the amount of heat stabilizer added was 0.5% of the mass of succinic acid.

[0153] The final prepared low-viscosity branched modified PBS polymer had an intrinsic viscosity of 1.2 dL / g and a number-average molecular weight of 4.5 × 10⁻⁶. 4 g / mol;

[0154] (3) Preparation of PBS high-viscosity blend polymer;

[0155] A high-viscosity PBS blend polymer was obtained by blending a polyester flow modifier at a mass ratio of 15:85 with PBS.

[0156] (4) Preparation of biodegradable PBS parallel-curled elastic fibers;

[0157] The low-viscosity branched modified PBS polymer obtained in step (2) and the high-viscosity blended PBS polymer obtained in step (3) are dried to a moisture content of ≤50ppm, and then parallel composite spinning is carried out to obtain biodegradable PBS parallel crimped elastic fiber; wherein, the composite ratio of the low-viscosity branched modified PBS polymer and the high-viscosity blended PBS polymer is 7:3.

[0158] The process flow of parallel composite spinning: melt spinning → side blowing cooling → oiling → winding → stretching → heat setting;

[0159] The process parameters for parallel composite spinning are as follows: the temperature of the two twin-screw spinning machines is set to 220℃, the spinning speed is 2000m / min, the side blowing temperature is 25℃, the relative humidity of the cooling air is 80%, the side blowing speed is 0.53m / min, the stretching ratio is 3.0 times, the heat setting temperature is 80℃, and the number of spinnerets on the spinneret used for spinning is 96.

[0160] At the spinning temperature, the MFRs of the PBS low-viscosity branched modified polymer and the PBS high-viscosity blend polymer were 85 g / 10 min and 90 g / 10 min, respectively.

[0161] The resulting biodegradable PBS side-by-side crimped elastic fiber has a breaking strength of 3.2 cN / dtex, a breaking elongation of 30%, and a crimp elasticity of 90%. It can be spun continuously for 12 hours without breakage when there is sufficient raw material.

[0162] Example 6

[0163] A method for preparing biodegradable PBS side-by-side crimped elastic fibers, comprising the following steps:

[0164] (1) Preparation of raw materials;

[0165] Multi-arm branching agent: dipentaerythritol;

[0166] Succinic acid;

[0167] Butylene glycol;

[0168] Additives: Composed of antioxidant (Irganox 1010), catalyst (tetrabutyl titanate), and heat stabilizer (triphenyl phosphite);

[0169] Polyester flow modifier: Hexylene difuranate oligomer;

[0170] PBS: intrinsic viscosity 1.8 dL / g, number-average molecular weight 14 × 10⁻⁶ 4 g / mol;

[0171] (2) Preparation of low-viscosity branched modified polymer for PBS;

[0172] Succinic acid, butanediol, multi-arm branching agent, and additives were mixed and esterified for 5 hours at 190℃ and 0.1 MPa. Then, the temperature was raised to 230℃ and vacuum polycondensation was carried out at ≤50 Pa until the discharge power was reached, thus obtaining the low-viscosity branched modified polymer of PBS. The molar ratio of succinic acid to butanediol was 1:1.2, the amount of multi-arm branching agent added was 0.1% of the molar weight of succinic acid, the amount of catalyst added was 0.1% of the mass of succinic acid, the amount of antioxidant added was 0.5% of the mass of succinic acid, and the amount of heat stabilizer added was 0.5% of the mass of succinic acid.

[0173] The final prepared low-viscosity branched modified PBS polymer had an intrinsic viscosity of 1.3 dL / g and a number-average molecular weight of 5 × 10⁻⁶. 4 g / mol;

[0174] (3) Preparation of PBS high-viscosity blend polymer;

[0175] A high-viscosity PBS blend polymer was obtained by blending a polyester flow modifier at a mass ratio of 20:80 with PBS.

[0176] (4) Preparation of biodegradable PBS parallel-curled elastic fibers;

[0177] The low-viscosity branched modified PBS polymer obtained in step (2) and the high-viscosity blended PBS polymer obtained in step (3) are dried to a moisture content of ≤50ppm, and then parallel composite spinning is performed to obtain biodegradable PBS parallel crimped elastic fiber; wherein, the composite ratio of the low-viscosity branched modified PBS polymer and the high-viscosity blended PBS polymer is 5:5.

[0178] The process flow of parallel composite spinning: melt spinning → side blowing cooling → oiling → winding → stretching → heat setting;

[0179] The process parameters for parallel composite spinning are as follows: the temperature of the two twin-screw spinning machines is set to 230℃, the spinning speed is 2000m / min, the side blowing temperature is 25℃, the relative humidity of the cooling air is 80%, the side blowing speed is 0.53m / min, the stretching ratio is 3.0 times, the heat setting temperature is 80℃, and the number of spinnerets on the spinneret used for spinning is 144.

[0180] At the spinning temperature, the MFRs of the PBS low-viscosity branched modified polymer and the PBS high-viscosity blend polymer were 80 g / 10 min and 100 g / 10 min, respectively.

[0181] The resulting biodegradable PBS side-by-side crimped elastic fiber has a breaking strength of 3.5 cN / dtex, a breaking elongation of 25%, and a crimp elasticity of 95%. It can be spun continuously for 12 hours without breakage when there is sufficient raw material.

Claims

1. A method for producing a biodegradable PBS side-by-side crimped elastic fiber, which performs side-by-side composite spinning of two polyesters having different intrinsic viscosities, characterized in that, The two polyesters with different intrinsic viscosities are PBS low-viscosity branched modified polymer and PBS high-viscosity blended polymer; The PBS low-viscosity branched modified polymer is obtained by copolymerization of multi-arm branching agent, succinic acid and butanediol; the multi-arm branching agent is glycerol, pentaerythritol, diglycerol or dipentaerythritol; The PBS high-viscosity blended polymer is obtained by blending polyester flow modifier and PBS; the polyester flow modifier is isosorbide succinate oligomer, isosorbide glutarate oligomer, isosorbide adipate oligomer, furan dimethylate succinate oligomer, furan dimethylate glutarate oligomer or furan dimethylate adipate oligomer; The absolute value of the MFR difference of the PBS low-viscosity branched modified polymer and the PBS high-viscosity blended polymer at the spinning temperature is less than 30 g / 10 min.

2. The preparation method of the biodegradable PBS side-by-side crimped elastic fiber according to claim 1, characterized in that, The preparation process of the PBS low-viscosity branched modified polymer is as follows: succinic acid, butanediol, multi-arm branching agent and additives are mixed, and then esterification reaction is carried out at a temperature of 180-200 ℃ and a pressure of 0.1 MPa for 4-6 h; then the temperature is raised to 230-250 ℃, and vacuum polycondensation reaction is carried out at a pressure of ≤50 Pa until the discharge power, to obtain the PBS low-viscosity branched modified polymer; wherein the molar ratio of succinic acid to butanediol is 1:1.1-1.3, and the addition amount of the multi-arm branching agent is 0.1%-3.0% of the molar amount of succinic acid.

3. The method for preparing biodegradable PBS side-by-side crimped elastic fibers according to claim 2, characterized in that, The PBS low-viscosity branched modified polymer has an intrinsic viscosity of 0.8-1.3 dL / g, a number average molecular weight of 2.0 x 10 4 -5.0 x 10 4 g / mol.

4. The preparation method of the biodegradable PBS side-by-side crimped elastic fiber according to claim 1, characterized in that, The polyester flow modifier has a polymerization degree ranging from 10 to 20; when the PBS high-viscosity blended polymer is prepared, the mass ratio of the polyester flow modifier to PBS is 5-20:95-80, the intrinsic viscosity of PBS is 1.4-1.8 dL / g, and the number average molecular weight of PBS is 7.0 x 10 4 -14.0 x 10 4 g / mol.

5. The preparation method of the biodegradable PBS side-by-side crimped elastic fiber according to claim 1, characterized in that, The composite ratio of the PBS low-viscosity branched modified polymer and the PBS high-viscosity blended polymer is 3:7-7:

3.

6. The preparation method of the biodegradable PBS side-by-side crimped elastic fiber according to claim 1, characterized in that, The process flow of parallel composite spinning is as follows: melt spinning→ side blowing cooling→ oiling→ winding→ stretching→ heat setting.

7. The method according to claim 6, wherein the biodegradable PBS side-by-side crimped elastic fiber is prepared by the steps of: (1) preparing a biodegradable PBS side-by-side crimped elastic fiber; and (2) heat setting the biodegradable PBS side-by-side crimped elastic fiber. The process parameters of parallel composite spinning include: spinning speed 600-2000 m / min, side blowing temperature 0-30 ℃, cooling wind relative humidity 65-85%, side blowing speed 0.3-1.0 m / min, stretching multiple 1.5-3.0 times, heat setting temperature 60-90 ℃, and the number of spinning holes on the spinning plate used for spinning is 28-144.

8. The preparation method of the biodegradable PBS side-by-side crimped elastic fiber according to any one of claims 1-7, characterized in that, The biodegradable PBS parallel crimped elastic fiber has a breaking strength of 2.4-3.5 cN / dtex, an elongation at break of 25-50%, and a crimped elasticity of 70-95%.

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