Regenerated fibers

Abstract

A regenerated fiber is prepared from a material comprising virgin polyester particles and regenerated polyester particles. The ratio of the intrinsic viscosity of the regenerated polyester particles to the intrinsic viscosity of the virgin polyester particles is between 0.89 and 1.13. A regenerated textile made from the regenerated fiber of the present disclosure is free from horizontal bar problems after dyeing.

Description

Technical Field

[0001] This disclosure relates to an environmentally friendly textile material, specifically a recycled fiber. Background Technology

[0002] In recent years, with the gradual increase in textile consumption, the amount of waste textiles has also increased significantly. In response, industry players have begun to recycle and reuse waste textiles to develop fibers with high added value and environmental friendliness. However, recycled fibers made from waste textiles often suffer from severely impaired spinnability due to the presence of dyes, impurities, and other substances, leading to quality or appearance defects in the subsequently produced recycled textiles (e.g., horizontal stripes). Therefore, how to provide a recycled fiber that combines high environmental friendliness with good spinnability has become an important research topic for the textile industry. Summary of the Invention

[0003] This disclosure provides a recycled fiber from which recycled textiles can be made without developing horizontal stripes after dyeing.

[0004] According to some embodiments disclosed herein, a recycled fiber is prepared from a material comprising virgin polyester granules and recycled polyester granules. The ratio of the intrinsic viscosity of the recycled polyester granules to that of the virgin polyester granules is between 0.89 and 1.13.

[0005] In some embodiments disclosed herein, the weight ratio of the content of virgin polyester pellets to the content of recycled polyester pellets is between 1:1 and 8:2.

[0006] In some embodiments disclosed herein, the weight average molecular weight of the polyester in the virgin polyester pellets is between 30,000 g / mol and 40,000 g / mol, and the weight average molecular weight of the polyester in the recycled polyester pellets is between 30,000 g / mol and 48,000 g / mol.

[0007] In some embodiments disclosed herein, the weight average molecular weight of the polyester in the virgin polyester pellets is between 30,000 g / mol and 40,000 g / mol, and the weight average molecular weight of the polyester in the recycled polyester pellets is between 47,000 g / mol and 48,000 g / mol.

[0008] In some embodiments disclosed herein, recycled polyester pellets are prepared from materials comprising recycled polyester and chain-extended polyester. The chain-extended polyester comprises 90 to 98 parts by weight of virgin polyester and 2 to 10 parts by weight of a chain-extending agent.

[0009] In some embodiments disclosed herein, the content of recycled polyester is between 98 and 99 parts by weight, and the content of extended chain polyester is between 1 and 2 parts by weight.

[0010] In some embodiments disclosed herein, the chain extender comprises a structure as shown in formula (1): Where n is a positive integer between 1 and 3, and m is a positive integer between 1 and 3.

[0011] In some embodiments disclosed herein, the content of the chain extender is between 1000 ppm and 2000 ppm based on the total weight of the recycled polyester pellets.

[0012] In some embodiments disclosed herein, the chain extender comprises a structure as shown in formula (2):

[0013]

[0014] In some embodiments disclosed herein, the content of the chain extender is between 150 ppm and 500 ppm based on the total weight of the recycled polyester pellets.

[0015] According to the embodiments disclosed above, the recycled fiber disclosed is prepared from a material comprising virgin polyester granules and recycled polyester granules. By controlling the ratio (proportion) of the intrinsic viscosity of the virgin polyester granules to the intrinsic viscosity of the recycled polyester granules, the recycled textiles made from the recycled fiber can be free from the problem of horizontal stripes after dyeing. Detailed Implementation

[0016] Several embodiments of this disclosure will be described in detail below. For clarity, many practical details will be described in the following description. However, it should be understood that these practical details should not be used to limit this disclosure. That is, in some embodiments of this disclosure, these practical details are not essential and therefore should not be used to limit this disclosure.

[0017] In this disclosure, the structure of polymers or groups is sometimes represented by a skeleton formula. This representation may omit carbon atoms, hydrogen atoms, and carbon-hydrogen bonds. Of course, if the structural formula explicitly shows atoms or atomic groups, the representation shown by the author shall prevail.

[0018] This disclosure provides a recycled fiber prepared from a material comprising virgin polyester granules and recycled polyester granules. By controlling the ratio (proportion) of the intrinsic viscosity of the virgin polyester granules to that of the recycled polyester granules, recycled textiles made from the recycled fiber can be free from horizontal stripe problems after dyeing.

[0019] The regenerated fiber disclosed herein is prepared from a material comprising virgin polyester granules and regenerated polyester granules, wherein the intrinsic viscosity ratio of the regenerated polyester granules to the virgin polyester granules is between 0.89 and 1.13. When the ratio of the intrinsic viscosity of the regenerated polyester granules to the virgin polyester granules falls within the above range, the regenerated polyester granules and the virgin polyester granules can have similar physical properties (e.g., heat resistance, spun properties, etc.), thereby giving the regenerated polyester granules and the virgin polyester granules similar melt spinning stability. In this way, the regenerated fiber spun from both regenerated and virgin polyester granules can avoid the formation of horizontal streaks after being made into regenerated textiles and dyed. In some embodiments, the intrinsic viscosity of the virgin polyester granules may be, for example, 0.64, and the intrinsic viscosity of the regenerated polyester granules may be, for example, between 0.57 and 0.72.

[0020] Further details are provided regarding the method for measuring the intrinsic viscosity of the polyester granules disclosed herein. The method for measuring the intrinsic viscosity of the polyester granules includes steps S10 to S40. In step S10, 0.125 g of polyester granules is placed in 25 ml of a phenol-tetrachloroethane mixed solvent and heated at 120°C for approximately two hours until the polyester granules are completely dissolved. After cooling, a test solution is formed. In step S20, the test solution is poured into a viscometer (model: SCHOTTCT52 kinematic viscometer) and allowed to stand in a constant temperature water bath at 25 ± 0.05°C for 20 minutes. The time (T1) required for the solution to change from the upper scale to the lower scale in the viscometer is then measured. In step S30, another 25 ml of phenol-tetrachloroethane mixed solvent is poured into a viscometer (model: SCHOTT CT52 kinematic viscometer) and left to stand in a constant temperature water bath at 25 ± 0.05 °C for 20 minutes. The time (T2) required for the viscosity to drop from the upper scale to the lower scale in the viscometer is then measured. In step S40, the ratio of time T1 to time T2 is calculated to obtain the relative viscosity of the polyester particle, and the intrinsic viscosity of the polyester particle is calculated using relevant formulas.

[0021] In some embodiments, the weight ratio of virgin polyester granules to recycled polyester granules can be between 1:1 and 8:2 to help give the recycled fibers high environmental friendliness (e.g., high recycling rate) and high spinning stability of the material used to form the recycled fibers. Specifically, when the weight ratio of virgin polyester granules to recycled polyester granules is less than 1:1 (e.g., 4:6), the material used to form the recycled fibers has a greater chance of breakage during false twisting; when the weight ratio is greater than 8:2 (e.g., 9:1), it indicates a low content of recycled raw materials in the recycled fibers, which may make it difficult to meet market expectations and requirements for environmentally friendly textiles. In a preferred embodiment, the weight ratio of virgin polyester granules to recycled polyester granules can be, for example, 7:3, to better balance the environmental friendliness of the recycled fibers and the spinning stability of the material used to form the recycled fibers.

[0022] In some embodiments, the intrinsic viscosity of the recycled polyester granules and the virgin polyester granules can be made similar by adjusting the weight-average molecular weight of the polyester in the virgin polyester granules and the weight-average molecular weight of the polyester in the recycled polyester granules. In some embodiments, the weight-average molecular weight of the polyester in the virgin polyester granules can be between 30,000 g / mol and 40,000 g / mol, and the weight-average molecular weight of the polyester in the recycled polyester granules can be between 30,000 g / mol and 48,000 g / mol. Specifically, when the weight-average molecular weight of the polyester in the virgin polyester granules and the weight-average molecular weight of the polyester in the recycled polyester granules each fall within the above ranges, it helps to make the ratio of the intrinsic viscosity of the recycled polyester granules to the intrinsic viscosity of the virgin polyester granules close to 0.89 to 1.13, thereby giving the recycled polyester granules and virgin polyester granules similar melt spinning stability. In other embodiments, the recycled polyester granules can be prepared by low-cost solid-state polymerization, and in these embodiments, the weight-average molecular weight of the polyester in the recycled polyester granules can be between 47,000 g / mol and 48,000 g / mol. It is worth noting that, compared to the implementation method without solid-state polymerization, although the weight average molecular weight of polyester in the recycled polyester pellets formed by solid-state polymerization is larger and differs significantly from that in the virgin polyester pellets, the ratio of the intrinsic viscosity of the recycled polyester pellets to that of the virgin polyester pellets can still fall within the range of 0.89 to 1.13. Furthermore, since solid-state polymerization has a lower process temperature and can increase the molecular weight of recycled polyester compared to conventional polymerization, it can effectively save costs and has advantages in mass production.

[0023] In some embodiments, the solid-state polymerization temperature can be between 200°C and 240°C, the solid-state polymerization time can be between 6 hours and 10 hours, the vacuum degree of solid-state polymerization can be between 0.1 Torr and 1 Torr, and the stirring speed of solid-state polymerization can be between 50 rpm and 70 rpm. In some embodiments, the polyester in the virgin polyester granules can be, for example, polyethylene terephthalate, and the polyester in the recycled polyester granules can be, for example, polyethylene terephthalate, polybutylene terephthalate, or a combination thereof.

[0024] Further explanation is provided regarding recycled polyester granules. In some embodiments, recycled polyester granules can be prepared from materials comprising recycled polyester and extended-chain polyester. Specifically, recycled polyester and extended-chain polyester can be subjected to a mixing and granulation process to form recycled polyester granules, wherein the mixing and granulation temperature can be between 260°C and 280°C, and the rotational speed of the twin-screw used for mixing and granulation can be between 200 rpm and 260 rpm. In some embodiments, the recycled polyester and extended-chain polyester can each be prepared by the aforementioned solid-state polymerization. The recycled polyester can be configured to increase the weight proportion of recycled raw materials in the recycled polyester granules, thereby giving the recycled fibers prepared from the recycled polyester granules high environmental friendliness, while the extended-chain polyester can be configured to increase the intrinsic viscosity of the recycled polyester granules, so that the recycled polyester granules have melt spinning stability similar to that of virgin polyester granules. Overall, the content of recycled polyester in recycled polyester granules can be between 98 and 99 parts by weight, and the content of extended chain polyester can be between 1 and 2 parts by weight, thus balancing the environmental friendliness of recycled fibers made from recycled polyester granules and the melt spinning stability of recycled polyester granules.

[0025] Further explanation is given regarding the recycled polyester in the recycled polyester pellets. In some embodiments, the recycled polyester may be, for example, polyethylene terephthalate. In some embodiments, the recycled polyester may be, for example, in the form of polyester pellets, thereby improving storage convenience. Specifically, the recycled polyester may be prepared, for example, by screening, purifying, crushing, melting, mixing, modifying, and granulating waste fabrics or fibers. Further explanation is given regarding the chain-extended polyester in the recycled polyester pellets. In some embodiments, the chain-extended polyester may be prepared by a material comprising 90 to 98 parts by weight of virgin polyester and 2 to 10 parts by weight of a chain-extending agent, wherein the chain-extending agent may be configured to increase the degree of crosslinking of the virgin polyester, thereby giving the recycled polyester pellets a suitable intrinsic viscosity to facilitate melt spinning. The virgin polyester and chain-extending agent falling within the above-mentioned content range can help give the recycled polyester pellets high melt spinning stability and reduce the possibility of fiber breakage during false twisting of the material used to form the recycled fibers. In some embodiments, the virgin polyester may be, for example, polyethylene terephthalate, polybutylene terephthalate, or a combination thereof. In some embodiments, the chain-extended polyester may be, for example, in the form of polyester granules, thereby improving storage convenience. Specifically, the virgin polyester and the chain extender may be subjected to a compounding and granulation process to form chain-extended polyester granules.

[0026] In some embodiments, the chain extender comprises a structure as shown in formula (1):

[0027] Where n is a positive integer between 1 and 3, and m is a positive integer between 1 and 3. When the chain extender includes the structure shown in formula (1) above, the content of the chain extender, based on the total weight of the recycled polyester granules, can be between 1000 ppm and 2000 ppm. Specifically, if the content is less than 1000 ppm, the chain extender may have limited ability to improve the crosslinking degree of the virgin polyester; if the content is greater than 2000 ppm, the material used to form the recycled fiber may have a greater chance of breaking during false twisting. In other embodiments, the chain extender includes the structure shown in formula (2):

[0028] When the chain extender includes the structure shown in formula (2) above, the content of the chain extender, based on the total weight of the recycled polyester granules, can be between 150 ppm and 500 ppm. Specifically, if the content is less than 150 ppm, the ability of the chain extender polyester to improve the crosslinking degree of the virgin polyester may be limited; if the content is greater than 500 ppm, the material used to form the recycled fiber may have a greater chance of breaking during false twisting. It is worth noting that, compared to the chain extender containing the structure shown in formula (1), the chain extender containing the structure shown in formula (2) has more functional groups that can react with the virgin polyester. Therefore, when using the chain extender containing the structure shown in formula (2) to prepare recycled polyester granules, a small amount of chain extender can achieve a significant chain extension effect, which helps to facilitate the process and save costs.

[0029] Furthermore, the recycled polyester granules disclosed herein exhibit excellent color performance, thus avoiding adverse effects on the dyeing process of fibers or fabrics formed from the recycled polyester granules, thereby providing broad applicability. In some embodiments, the recycled polyester granules have an L value greater than 80 and a b value less than 10 in the L*a*b* color space, indicating high whiteness and low yellowness. Based on this, the recycled fibers disclosed herein have an L value greater than 93 and a b value less than 3 in the L*a*b* color space, indicating color controllability similar to that of virgin fibers. Moreover, when the recycled polyester granules disclosed herein are subjected to a pressure rise test using a filter with a pore size of 40 μm, the recycled polyester granules disclosed herein exhibit a pressure rise value less than or equal to 10 bar / kg, indicating good spinnability. Additionally, the recycled fibers disclosed herein exhibit a fiber strength greater than or equal to 3 g / d, meeting industry standards.

[0030] In the following description, various evaluations will be conducted regarding the recycled polyester granules and recycled fibers disclosed herein. It should be understood that the materials used, their quantities and proportions, processing details, and processing procedures can be appropriately varied without departing from the scope of this disclosure. Therefore, this disclosure should not be interpreted as limiting based on the embodiments described below.

[0031] <Experimental Example 1: Evaluation of the intrinsic viscosity, color, and filter quality of polyester granules>

[0032] In this experimental example, intrinsic viscosity, color, and filter quality were evaluated for the virgin polyester pellets of the comparative examples and the recycled polyester pellets of each embodiment. The descriptions and evaluation results of the comparative examples and each embodiment are shown in Table 1. The polyester in the virgin polyester pellets of Comparative Example 1 is polyethylene terephthalate (PET), the polyester in the recycled polyester pellets of Examples 1-3 is PET, and the polyester in the recycled polyester pellets of Example 4 includes PET and polybutylene terephthalate (the content of polybutylene terephthalate is 1 wt% based on the total weight of the recycled polyester pellets, and the source of polybutylene terephthalate is the virgin polyester in the extended chain polyester).

[0033] Table 1

[0034]

[0035] Note 1: The content of chain extender is based on the total weight of recycled polyester granules.

[0036] Note 2: The filter evaluation represents a pressure rise of less than or equal to 10 bar / kg when polyester particles are subjected to a pressure rise test using a filter with a pore size of 40 μm.

[0037] Note 3: The recycled polyester granules of Examples 1 to 4 were formed by non-solid polymerization, while the recycled polyester granules of Example 12 were formed by solid polymerization.

[0038] As shown in Table 1, increasing the chain extender content increases the intrinsic viscosity of recycled polyester granules, bringing it closer to that of virgin polyester granules. Furthermore, the L-values ​​of the recycled polyester granules in all embodiments are greater than 80, and the b-values ​​are less than 10, indicating good color performance and preventing adverse effects on subsequent dyeing processes of the resulting recycled fibers or fabrics. Additionally, the recycled polyester granules in all embodiments can pass through a filter, demonstrating good spinnability.

[0039] <Experimental Example 2: Evaluation of the weight-average molecular weight of polyester in polyester granules>

[0040] In this experimental example, the weight-average molecular weight of the polyester in the virgin polyester pellets of Comparative Example 1 and the polyester in the recycled polyester pellets of Examples 1-2 and 12 was evaluated. The evaluation results are shown in Table 2.

[0041] Table 2

[0042]

[0043] As shown in Table 2, the weight-average molecular weight of polyester in the recycled polyester granules of Examples 1-2 is very close to that of polyester in the virgin polyester granules of Comparative Example 1. This indicates that the addition of the chain extender has a certain influence on the weight-average molecular weight of polyester in the polyester granules. On the other hand, the weight-average molecular weight of polyester in the recycled polyester granules of Example 12 is similar to that of polyester in the recycled polyester granules of Example 2. This shows that the weight-average molecular weight of polyester in recycled polyester granules formed using solid-state polymerization can still be very close to that of polyester in recycled polyester granules formed without solid-state polymerization. This helps to keep the ratio of the intrinsic viscosity of recycled polyester granules to that of virgin polyester granules within the range of 0.89 to 1.13 while saving costs. <Experimental Example 3: Evaluation of Spinning Properties, False Twist Processing Properties, and Elongation Variation of Regenerated Fibers>

[0044] In this experimental example, the virgin polyester pellets of Comparative Example 1 were spun to form the virgin fibers of Comparative Example 2, and the recycled polyester pellets of Examples 1-4 and 12 were spun together with the virgin polyester pellets of Comparative Example 1 to form the recycled fibers of Examples 5-9 and 13. Next, the spinnability, false twist processability, and elongation variability of the virgin fibers of Comparative Example 2 and the recycled fibers of Examples 5-9 and 13 were evaluated. The descriptions and evaluation results of the comparative examples and each example are shown in Table 3.

[0045] Table 3

[0046]

[0047] As shown in Table 3, when using the recycled polyester granules of Example 3 to prepare recycled fibers, partially oriented yarn (POY) can be successfully obtained. However, subsequent false twisting of the POY may result in yarn breakage, making it impossible to successfully form drawn textured yarn (DTY). Furthermore, the recycled fibers of each example all exhibit less than 7% elongation variability, indicating that each recycled fiber provides fairly consistent elongation, thus preventing horizontal stripe problems in recycled textiles made from the recycled fibers after dyeing. Therefore, although the recycled fibers prepared using the recycled polyester granules of Example 3 are more difficult to process into drawn textured yarn, they still have a relatively small elongation variability, thus preventing horizontal stripe problems in the subsequently formed recycled textiles after dyeing.

[0048] <Experiment Example 4: Color and Stripe Evaluation of Recycled Textiles>

[0049] In this experimental example, recycled textiles of Examples 10, 11, and 14 were prepared using the recycled fibers from Examples 6, 9, and 13, respectively, and the color of the recycled textiles of Examples 10, 11, and 14 was evaluated. Subsequently, the recycled textiles of Examples 10, 11, and 14 were dyed, and the stripe evaluation was performed on the recycled textiles after dyeing. The evaluation results are shown in Table 4.

[0050] Table 4

[0051]

[0052] As shown in Table 4, the recycled textiles in Examples 10, 11, and 14 do not have horizontal stripe problems. Furthermore, before dyeing, the L value of the recycled textiles in the L*a*b* color space can be greater than 93, and the b value can be less than 3, indicating high whiteness and low yellowness, thus providing a wide range of dyeing applications.

[0053] According to the embodiments disclosed above, the recycled fiber disclosed is prepared from a material comprising virgin polyester granules and recycled polyester granules. By controlling the ratio (proportion) of the intrinsic viscosity of the virgin polyester granules to the intrinsic viscosity of the recycled polyester granules, the recycled textiles made from the recycled fiber can be free from the problem of horizontal stripes after dyeing.

[0054] Although the present disclosure has been described above with reference to embodiments, it is not intended to limit the present disclosure. Anyone skilled in the art may make various modifications and alterations without departing from the spirit and scope of the present disclosure. Therefore, the scope of protection of the present disclosure shall be determined by the appended claims.

Claims

1. A regenerated fiber, characterized by, It is made from materials containing the following components: Virgin polyester pellets; and The recycled polyester granules have an intrinsic viscosity ratio between 0.89 and 1.13 to that of the virgin polyester granules, wherein the weight ratio of the content of the virgin polyester granules to the content of the recycled polyester granules is between 1:1 and 7:

3.

2. The regenerated fiber as claimed in claim 1, wherein the weight average molecular weight of the polyester in the virgin polyester pellets is between 30,000 g / mol and 40,000 g / mol, and the weight average molecular weight of the polyester in the regenerated polyester pellets is between 30,000 g / mol and 48,000 g / mol.

3. The regenerated fiber as claimed in claim 1, wherein the weight average molecular weight of the polyester in the virgin polyester pellets is between 30,000 g / mol and 40,000 g / mol, and the weight average molecular weight of the polyester in the regenerated polyester pellets is between 47,000 g / mol and 48,000 g / mol.

4. The recycled fiber of claim 1, wherein the recycled polyester pellets are prepared by means of a material comprising the following components: Recycled polyester; and The chain-extended polyester comprises 90 to 98 parts by weight of virgin polyester and 2 to 10 parts by weight of chain extender.

5. The recycled fiber of claim 4, wherein the content of the recycled polyester is between 98 parts by weight and 99 parts by weight, and the content of the extended chain polyester is between 1 part by weight and 2 parts by weight.

6. The regenerated fiber of claim 4, wherein the chain extender comprises a structure as shown in formula (1): wherein n is a positive integer between 1 and 3, and m is a positive integer between 1 and 3.

7. The recycled fiber of claim 6, wherein the content of the chain extender is between 1000 ppm and 2000 ppm based on the total weight of the recycled polyester pellets.

8. The regenerated fiber of claim 4, wherein the chain extender comprises a structure as shown in formula (2):

9. The recycled fiber of claim 8, wherein the content of the chain extender is between 150 ppm and 500 ppm based on the total weight of the recycled polyester pellets.

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