Low-melting-point FDY polyester multifilament as well as preparation method and application thereof

Abstract

The invention relates to a low-melting-point FDY polyester multifilament and a preparation method and application thereof.The preparation method comprises the following steps that polyester chips A and polyester chips B are subjected to pre-crystallization, drying, mixing and melt blending spinning, and the low-melting-point FDY polyester multifilament is obtained; the total mass of the polyester chip A and the polyester chip B is 100%, the mass percent of the polyester chip A is 1%-4%, the melting point of the polyester chip A is lower than that of the polyester chip B, and the difference value of the melting point of the polyester chip A and the melting point of the polyester chip B is-60 DEG C to-10 DEG C. The preparation method of the low-melting-point FDY polyester multifilament is good in spinning stability, the prepared low-melting-point FDY polyester multifilament is small in melting point fluctuation and good in mechanical property, and when the low-melting-point FDY polyester multifilament is heated at the high temperature of 100-160 DEG C, the low-melting-point FDY polyester multifilament is softened, has certain adhesiveness and can still have the characteristics of the multifilament without being completely molten.

Description

Technical Field

[0001] This invention relates to the field of polyester fiber technology, and in particular to a low-melting-point FDY polyester multifilament, its preparation method, and its application. Background Technology

[0002] FDY is an abbreviation for Fully Drawn Yarn, which is usually translated into Chinese as fully drawn yarn or fully stretched yarn. Low-melting-point FDY polyester multifilament is prepared from low-melting-point polyester chips (also known as low-melting-point polyester) through a spinning and drawing process. Due to its low-temperature melt bonding characteristics, it has important application value in textile, nonwoven and other industries. Its core advantage is that no additional adhesive is needed. The low-melting-point FDY polyester multifilament can be bonded to the substrate simply by heating, which simplifies the production process and reduces environmental pressure.

[0003] However, existing low-melting-point FDY polyester multifilaments suffer from poor production stability, low efficiency in the spinning process, poor mechanical properties, and are prone to breakage during subsequent processing, which limits their application in high-strength demand scenarios.

[0004] Therefore, it is necessary to develop a low-melting-point FDY polyester multifilament with excellent mechanical properties and high spinning stability. Summary of the Invention

[0005] To solve the above-mentioned technical problems, the present invention provides a low-melting-point FDY polyester multifilament, its preparation method and application. The preparation method has good spinning stability, and the obtained low-melting-point FDY polyester multifilament has small melting point fluctuation and good mechanical properties.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing low-melting-point FDY polyester multifilament, the method comprising the following steps: pre-crystallizing and drying polyester chips A and B, mixing, melt-blending and spinning to obtain the low-melting-point FDY polyester multifilament; based on the total mass of polyester chips A and B as 100%, the mass percentage of polyester chip A is 1% to 4% (e.g., 1.5%, 2%, 2.5%, 3% or 3.5%, etc.); the melting point of polyester chip A is lower than that of polyester chip B, and the difference between the melting points of polyester chip A and polyester chip B is -60℃ to -10℃ (e.g., -55℃, -50℃, -45℃, -40℃, -35℃, -30℃, -25℃, -20℃ or -15℃, etc.).

[0008] In this invention, "low melting point" means a melting point in the range of 185℃ to 210℃, such as 188℃, 191℃, 194℃, 197℃, 200℃, 203℃, 206℃, or 209℃.

[0009] In this invention, the preparation method exhibits good spinning stability, resulting in low-melting-point FDY polyester multifilament with minimal melting point fluctuations, good mechanical properties, and elasticity. The melting point of polyester chip A is lower than that of polyester chip B. Polyester chip A provides better softening and adhesion, while polyester chip B provides better mechanical properties. This allows the low-melting-point FDY polyester multifilament to soften and exhibit some adhesion when heated at high temperatures (100~160℃) during subsequent weaving and finishing processes. However, the low-melting-point FDY polyester multifilament is not completely melted and retains its multifilament characteristics, maintaining a good hand feel.

[0010] Preferably, the melting point of the polyester chip A is 170~190℃, such as 172℃, 174℃, 176℃, 178℃, 180℃, 182℃, 184℃, 186℃ or 188℃.

[0011] Preferably, the melting point of the polyester chip B is 200~230℃, such as 203℃, 206℃, 209℃, 212℃, 215℃, 218℃, 221℃, 224℃ or 227℃.

[0012] In this invention, the melting point of the polyester chip B is preferably 200~230℃. If the melting point of the polyester chip B is too high, the temperature required during the melt blending spinning process will be too high, which will easily lead to the degradation of the polyester chip A during the melt blending spinning process, and the anti-yellowing performance of the low melting point FDY polyester multifilament will decrease.

[0013] Preferably, the pre-crystallization is carried out under vacuum conditions.

[0014] Preferably, the pre-crystallization temperature is 75~85℃, such as 76℃, 77℃, 78℃, 79℃, 80℃, 81℃, 82℃, 83℃ or 84℃.

[0015] Preferably, the pre-crystallization time is ≥24 h, such as 25 h, 30 h, 35 h, 40 h, 45 h or 50 h.

[0016] In this invention, the pre-crystallization time is preferably ≥24 h. If the pre-crystallization time is too short, there will be abnormal screw feeding during melt blending spinning, the screw will not be able to stabilize the production pressure, resulting in yarn breakage or abnormal yarn fineness and inability to produce.

[0017] Preferably, the drying temperature is 130~145℃, such as 132℃, 134℃, 136℃, 138℃, 140℃, 142℃ or 144℃.

[0018] Preferably, the drying time is ≥10 h, such as 15 h, 20 h, 25 h, 30 h, 35 h or 40 h.

[0019] Preferably, the moisture content of the dried polyester chips A and B is independently ≤30 ppm, for example, 5 ppm, 10 ppm, 15 ppm, 20 ppm or 25 ppm.

[0020] Preferably, the mixing includes stirring.

[0021] Preferably, the melt blend spinning includes the steps of melt extrusion, spinning, air cooling, and drawing.

[0022] Preferably, the equipment used for melt extrusion is a spinning screw extruder.

[0023] Preferably, the temperature of the first screw zone of the spinning screw extruder is 170~210℃ (e.g., 175℃, 180℃, 185℃, 190℃, 195℃, 200℃, or 205℃, etc.), the temperature of the second screw zone is 190~225℃ (e.g., 195℃, 200℃, 205℃, 210℃, 215℃, or 220℃, etc.), and the temperature of the third screw zone is 210~230℃ (e.g., 213℃, 216℃, 219℃, 222℃, 22...). The screw zone temperature is 220~240℃ (e.g., 223℃, 226℃, 229℃, 232℃, 235℃ or 238℃, etc.), the screw zone temperature is 220~240℃ (e.g., 223℃, 226℃, 229℃, 232℃, 235℃ or 238℃, etc.), and the extruder head temperature is 220~240℃ (e.g., 223℃, 226℃, 229℃, 232℃, 235℃ or 238℃, etc.).

[0024] Preferably, the screw pressure of the spinning screw extruder is 10~12 MPa (e.g., 10.2 MPa, 10.4 MPa, 10.6 MPa, 10.8 MPa, 11 MPa, 11.2 MPa, 11.4 MPa, 11.6 MPa or 11.8 MPa, etc.).

[0025] Preferably, the air cooling includes side-blowing cooling.

[0026] Preferably, the air velocity of the air cooling system is set to 0.50~0.75 m / s (e.g., 0.58 m / s, 0.61 m / s, 0.64 m / s, 0.67 m / s, 0.70 m / s or 0.73 m / s, etc.), and the air temperature is 20~28℃ (e.g., 21℃, 22℃, 23℃, 24℃, 25℃, 26℃ or 27℃, etc.).

[0027] Preferably, the stretching ratio is 3.5 to 4.2 times, such as 3.6 times, 3.7 times, 3.8 times, 3.9 times, 4 times or 4.1 times.

[0028] In this invention, the preferred draft ratio is 3.5 to 4.2 times. If the draft ratio is too large, the melt blending spinning process will result in severe yarn breakage or even make production impossible. If the draft ratio is too small, the low melting point FDY polyester multifilament prepared will have low breaking strength.

[0029] Preferably, the stretching includes stretching using a first pair of hot rollers and a second pair of hot rollers.

[0030] Preferably, the temperature of the first pair of hot rollers is 60~75℃ (e.g., 62℃, 64℃, 66℃, 68℃, 70℃, 72℃ or 74℃, etc.), and the temperature of the second pair of hot rollers is 70~90℃ (e.g., 72℃, 74℃, 76℃, 78℃, 80℃, 82℃, 84℃, 86℃ or 88℃, etc.).

[0031] Preferably, the stretching further includes stretching using a third pair of hot rollers.

[0032] Preferably, the temperature of the third pair of hot rollers is 70~90℃ (e.g., 72℃, 74℃, 76℃, 78℃, 80℃, 82℃, 84℃, 86℃ or 88℃, etc.).

[0033] In this invention, the temperature of the first pair of hot rollers in the drawing process is preferably 60~75℃, and the temperature of the second pair of hot rollers is preferably 70~90℃, so as to achieve low-temperature setting. Combined with the preferred drawing ratio of 3.5~4.2 times, it helps to improve the mechanical properties of low melting point FDY polyester multifilament.

[0034] Preferably, the spinning speed of the melt blend spinning is 3900~4400 m / min, such as 3950 m / min, 4000 m / min, 4050 m / min, 4100 m / min, 4150 m / min, 4200 m / min, 4250 m / min, 4300 m / min or 4350 m / min, etc.

[0035] Preferably, the F number of the low melting point FDY polyester multifilament is ≥24F, such as 30F, 36F, 42F, 48F or 52F.

[0036] In this invention, when the linear density of low-melting-point FDY polyester multifilament is the same, the increase in the F number of the low-melting-point FDY polyester multifilament results in increased softness.

[0037] In a second aspect, the present invention provides a low-melting-point FDY polyester multifilament, wherein the low-melting-point FDY polyester multifilament is prepared by the preparation method described in the first aspect.

[0038] Preferably, the breaking strength of the low melting point FDY polyester multifilament is ≥2.8 cN / dtex, such as 3 cN / dtex, 3.2 cN / dtex, 3.4 cN / dtex, 3.6 cN / dtex, 3.8 cN / dtex or 4.0 cN / dtex.

[0039] Preferably, the low-melting-point FDY polyester multifilament has a breaking elongation of 40% to 60%, such as 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, or 58%.

[0040] Preferably, the melting point of the low-melting-point FDY polyester multifilament is 185℃~210℃, such as 188℃, 191℃, 194℃, 197℃, 200℃, 203℃, 206℃ or 209℃.

[0041] In this invention, the melting point of the low-melting-point FDY polyester multifilament refers to the temperature at which the low-melting-point FDY polyester multifilament is completely melted at any three selected locations, and the average value is taken to obtain the melting point.

[0042] Thirdly, the present invention provides a fabric comprising low-melting-point FDY polyester multifilament as described in the second aspect.

[0043] Compared with the prior art, the present invention has at least the following beneficial effects:

[0044] The method for preparing low-melting-point FDY polyester multifilament provided by this invention exhibits good spinning stability, resulting in low-melting-point FDY polyester multifilament with excellent mechanical properties, elasticity, and the ability to be spun normally without easily experiencing breakage. Its good spinning stability makes it suitable for continuous industrial production, with production costs comparable to traditional processes. The resulting low-melting-point FDY polyester multifilament has a melting point of 185℃~210℃, a breaking strength ≥2.4 cN / dtex, and a breaking elongation ≥42.16%. Preferably, the breaking strength is ≥2.8 cN / dtex. During subsequent weaving and finishing processes, the low-melting-point FDY polyester multifilament softens and exhibits a certain degree of adhesion when heated at high temperatures (100~160℃), but remains partially fused, retaining the characteristics of multifilament, resulting in a fabric with a good hand feel. Detailed Implementation

[0045] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0046] Some of the raw materials used in the following examples and comparative examples are as follows.

[0047] (1) Polyester chips A: melting point is 180℃, model is low melting point bright polyester chips (III), manufacturer is Shanghai Zhongju Chemical Co., Ltd.

[0048] (2) Polyester chips B:

[0049] Polyester chips B-1: melting point 220℃, model RH300, manufacturer is Yangzhou Qirui Chemical Co., Ltd.

[0050] Polyester chips B-2: melting point 220℃, model Y-20, manufacturer is Tianjin Huaxinying Polyester Materials Technology Co., Ltd.

[0051] Example 1

[0052] This embodiment provides a low-melting-point FDY polyester multifilament and its preparation method. The preparation method of the low-melting-point FDY polyester multifilament includes the following steps: Polyester chips A and B-1 are pre-crystallized and dried in a rotary drum vacuum drying oven, respectively. The pre-crystallization is carried out under vacuum conditions at a temperature of 80°C for 24 hours, and the drying temperature is 130°C for 10 hours. After drying, the moisture content of polyester chip A and polyester chip B-1 is 20 ppm. Then, the dried polyester chips A and B-1 are stirred and mixed. Based on the total mass of polyester chips A and B-1 being 100%, the mass percentage of polyester chip A is 4%. The mixture is then added to a spinning screw extruder for melt extrusion, spun through a spinneret, and cooled by side blowing and drawn to complete the melt blend spinning. The spinning speed of the melt blend spinning is 4000. The low melting point FDY polyester multifilament was obtained by moving m / min, with an F number of 24F and a fineness of 95 dtex.

[0053] The temperature of the screw in the above-mentioned spinning screw extruder is 180℃ in zone 1, 200℃ in zone 2, 220℃ in zone 3, 230℃ in zone 4, 230℃ in zone 5, 230℃ in the extrusion head, and 11 MPa in screw pressure.

[0054] The air speed for the above-mentioned air cooling is set at 0.6 m / s, and the air temperature is 25℃.

[0055] In the above-mentioned drawing process, the temperature of the first pair of hot rollers is 65°C and the temperature of the second pair of hot rollers is 80°C for low-temperature setting, and the drawing ratio is 4 times.

[0056] Example 2

[0057] This embodiment provides a low-melting-point FDY polyester multifilament and its preparation method. The preparation method of the low-melting-point FDY polyester multifilament includes the following steps: Polyester chips A and B-2 are pre-crystallized and dried in a rotary drum vacuum drying oven, respectively. The pre-crystallization is carried out under vacuum conditions at a temperature of 80°C for 24 hours, and the drying temperature is 130°C for 10 hours. After drying, the moisture content of polyester chip A and polyester chip B-2 is 20 ppm. Then, the dried polyester chips A and B-2 are stirred and mixed. Based on the total mass of polyester chips A and B-2 being 100%, the mass percentage of polyester chip A is 4%. The mixture is then added to a spinning screw extruder for melt extrusion, spun through a spinneret, and cooled by side blowing and drawn to complete the melt blend spinning. The spinning speed of the melt blend spinning is 3900. The low melting point FDY polyester multifilament was obtained by moving m / min, with an F number of 24F and a fineness of 95 dtex.

[0058] The temperature of the screw in the above-mentioned spinning screw extruder is 175℃ in zone 1, 195℃ in zone 2, 215℃ in zone 3, 225℃ in zone 4, 225℃ in zone 5, 225℃ in the extrusion head, and 12 MPa in screw pressure.

[0059] The air speed for the above-mentioned air cooling is set at 0.5 m / s, and the air temperature is 20℃.

[0060] In the above-mentioned drawing process, the temperature of the first pair of hot rollers is 75°C and the temperature of the second pair of hot rollers is 90°C for low-temperature setting, and the drawing ratio is 3.5 times.

[0061] Example 3

[0062] This embodiment provides a low-melting-point FDY polyester multifilament and its preparation method. The preparation method of the low-melting-point FDY polyester multifilament includes the following steps: Polyester chips A and B-1 are pre-crystallized and dried in a rotary drum vacuum drying oven, respectively. The pre-crystallization is carried out under vacuum conditions at a temperature of 80°C for 24 hours, and the drying temperature is 130°C for 10 hours. After drying, the moisture content of polyester chip A and polyester chip B-1 is 20 ppm. Then, the dried polyester chips A and B-1 are stirred and mixed. Taking the total mass of polyester chips A and B-1 as 100%, the mass percentage of polyester chip A is 4%. The mixture is added to a spinning screw extruder for melt extrusion, spun through a spinneret, and cooled by side blowing and drawn to complete the melt blend spinning. The spinning speed of the melt blend spinning is 4400. The low melting point FDY polyester multifilament has a melting point of m / min, an F number of 24F, and a fineness of 90 dtex.

[0063] The temperature of the screw in the above-mentioned spinning screw extruder is 210℃ in zone 1, 225℃ in zone 2, 230℃ in zone 3, 240℃ in zone 4, 240℃ in zone 5, 240℃ in the extrusion head, and 10 MPa in screw pressure.

[0064] The air speed for the above-mentioned air cooling is set at 0.75 m / s, and the air temperature is 28℃.

[0065] In the above-mentioned drawing process, the temperature of the first pair of hot rollers is 60°C and the temperature of the second pair of hot rollers is 70°C for low-temperature setting, and the drawing ratio is 4.2 times.

[0066] Example 4

[0067] This embodiment provides a low-melting-point FDY polyester multifilament and its preparation method. The difference between this embodiment and Embodiment 1 is that the draw ratio is adjusted to 3 times, while other conditions are the same as in Embodiment 1.

[0068] Example 5

[0069] This embodiment provides a low-melting-point FDY polyester multifilament and its preparation method. The difference between this embodiment and Embodiment 1 is that, with the total mass of polyester slice A and polyester slice B-1 being 100%, the mass percentage of polyester slice A is 1%, and other conditions are the same as in Embodiment 1.

[0070] Example 6

[0071] This embodiment provides a low-melting-point FDY polyester multifilament and its preparation method. The difference between this embodiment and Embodiment 1 is that, based on the total mass of polyester slice A and polyester slice B-1 being 100%, the mass percentage of polyester slice A is 3%, and other conditions are the same as in Embodiment 1.

[0072] Comparative Example 1

[0073] This comparative example provides an FDY polyester multifilament and its preparation method. The difference between this example and Example 1 is that, with the total mass of polyester chip A and polyester chip B-1 being 100%, the mass percentage of polyester chip A is 0.5%, and other conditions are the same as in Example 1.

[0074] Comparative Example 2

[0075] This comparative example provides an FDY polyester multifilament and its preparation method. The difference between this example and Example 1 is that the total mass of polyester chip A and polyester chip B-1 is taken as 100%, and the mass percentage of polyester chip A is 5%. Other conditions are the same as in Example 1.

[0076] The following performance tests were conducted on the low melting point FDY polyester multifilaments provided in Examples 1-6 and the FDY polyester multifilaments provided in Comparative Examples 1-2.

[0077] (1) Spinning stability: The stability was judged by observing whether there were any yarn breakage or yarn fuzz during the spinning process using the preparation methods of low melting point FDY polyester multifilament provided in Examples 1 to 6 and the preparation methods of FDY polyester multifilament provided in Comparative Examples 1 to 2. If there were no breakage or yarn fuzz, the spinning was considered to be normal and the spinning stability was good.

[0078] (2) Melting point: When testing the low melting point FDY polyester multifilament provided in Examples 1 to 6 and the FDY polyester multifilament provided in Comparative Examples 1 to 2, samples of the same mass were randomly selected at 3 locations and placed in glass slides and coverslips respectively. They were then placed on a melting point apparatus and electrically heated at the same heating rate. The temperature at which the sample was completely melted was recorded by observation under a microscope, and the average value was taken as the melting point.

[0079] (3) Breaking strength and elongation at break: Tested in accordance with GB / T 14344-2022 "Test Method for Breaking Strength and Elongation at Break of Synthetic Fiber Filaments and Textured Yarns".

[0080] The test results are shown in Table 1 below.

[0081] Table 1

[0082]

[0083] As shown in Table 1, the low-melting-point FDY polyester multifilaments prepared by the methods provided in Examples 1-6 have good spinning stability. The low-melting-point FDY polyester multifilaments obtained have a melting point of 189.7-194.7℃, a breaking strength ≥2.46cN / dtex, a breaking elongation ≥42.16%, and good mechanical properties.

[0084] Compared with Example 1, if the draw ratio is too small (Example 4), the low melting point FDY polyester multifilament prepared has a large breaking elongation, low breaking strength, and a lower melting point. Therefore, it can be seen that the present invention obtains a low melting point FDY polyester multifilament with better performance by controlling the draw ratio within a specific range.

[0085] Compared with Example 1, if the mass percentage of polyester chip A is too small (Comparative Example 1), the FDY polyester multifilament prepared has a high melting point, cannot form an adhesive effect during heat setting, and has a low elongation at break; if the mass percentage of polyester chip A is too large (Comparative Example 2), the FDY polyester multifilament prepared has a low melting point, is prone to melt formation during heat setting, and has a significantly reduced breaking strength. Therefore, it can be seen that the present invention can achieve good mechanical properties by controlling the mass percentage of polyester chip A within a specific range.

[0086] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing low-melting-point FDY polyester multifilament, characterized in that, The preparation method includes the following steps: pre-crystallizing and drying polyester chips A and B, mixing, melt blending and spinning to obtain the low melting point FDY polyester multifilament; With the total mass of polyester chip A and polyester chip B being 100%, the mass percentage of polyester chip A is 1% to 4%. The melting point of polyester chip A is lower than that of polyester chip B, and the difference between the melting points of polyester chip A and polyester chip B is -60℃ to -10℃.

2. The preparation method according to claim 1, characterized in that, The melting point of the polyester chip A is 170~190℃; Preferably, the melting point of the polyester chip B is 200~230℃; Preferably, the pre-crystallization is carried out under vacuum conditions; Preferably, the pre-crystallization temperature is 75~85℃; Preferably, the pre-crystallization time is ≥24 h.

3. The preparation method according to claim 1 or 2, characterized in that, The drying temperature is 130~145℃; Preferably, the drying time is ≥10 h; Preferably, the moisture content of the dried polyester chips A and B is independently ≤30 ppm.

4. The preparation method according to any one of claims 1 to 3, characterized in that, The mixing includes stirring and mixing; Preferably, the melt blend spinning includes the steps of melt extrusion, spinning, air cooling, and drawing.

5. The preparation method according to claim 4, characterized in that, The equipment used for melt extrusion is a spinning screw extruder; Preferably, the temperature of the screw in the first zone of the spinning screw extruder is 170~210℃, the temperature of the second zone is 190~225℃, the temperature of the third zone is 210~230℃, the temperature of the fourth zone is 220~240℃, the temperature of the fifth zone is 220~240℃, and the temperature of the extrusion head is 220~240℃. Preferably, the screw pressure of the spinning screw extruder is 10~12 MPa.

6. The preparation method according to claim 4 or 5, characterized in that, The air cooling includes side-blowing cooling; Preferably, the air velocity of the air cooling system is set to 0.50~0.75m / s, and the air temperature is 20~28℃; Preferably, the draw ratio is 3.5 to 4.2 times; Preferably, the drawing process includes drawing using a first pair of hot rollers and a second pair of hot rollers; Preferably, the temperature of the first pair of hot rollers is 60~75°C, and the temperature of the second pair of hot rollers is 70~90°C; Preferably, the drawing further includes drawing using a third pair of hot rollers; Preferably, the temperature of the third pair of hot rollers is 70~90°C.

7. The preparation method according to any one of claims 1 to 6, characterized in that, The spinning speed of the melt blend spinning is 3900~4400 m / min; Preferably, the F number of the low melting point FDY polyester multifilament is ≥24F.

8. A low-melting-point FDY polyester multifilament, characterized in that, The low-melting-point FDY polyester multifilament is prepared by the preparation method described in any one of claims 1 to 7.

9. The low-melting-point FDY polyester multifilament according to claim 8, characterized in that, The low-melting-point FDY polyester multifilament has a breaking strength ≥2.8 cN / dtex; Preferably, the low-melting-point FDY polyester multifilament has a breaking elongation of 40% to 60%. Preferably, the melting point of the low-melting-point FDY polyester multifilament is 185℃~210℃.

10. A fabric, characterized in that, The fabric comprises low-melting-point FDY polyester multifilament as described in claim 8 or 9.

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