Light and high-resilience hollow polypropylene fiber composite warm-keeping flocculus and preparation method thereof

Abstract

The invention relates to a light high-resilience hollow polypropylene fiber composite warm-keeping flocculus and a preparation method thereof.The warm-keeping flocculus comprises hollow polypropylene fibers, superfine polyester fibers and polyethylene-polypropylene composite fibers, and the hollow polypropylene fibers are prepared through the following method that polypropylene is subjected to melt spinning; and fibers extruded from the spinning port are subjected to hot drafting and heat treatment and then are cooled. According to the composite warm-keeping flocculus, firstly, a fiber network is bonded through skin layer melting after ES fibers are heated, then the composite fiber network is reinforced through a needling method, the prepared composite flocculus is stable in structure, meanwhile, a light and thin fluffy warm-keeping layer is formed after needling reinforcement, the warm-keeping performance, the bulkiness and the comfort of the composite flocculus are guaranteed, and the composite flocculus is suitable for being used in a large scale. The whole machining process is simple in technology, short in flow and good in production efficiency.

Description

Technical Field

[0001] This invention relates to the field of thermal insulation wadding technology, specifically to a lightweight, highly resilient hollow polypropylene composite thermal insulation wadding and its preparation method. Background Technology

[0002] With the continuous improvement of people's living standards and consumption levels, various thermal insulation wadding materials have emerged in an endless stream. Wadding is an important auxiliary material in the textile industry. The raw materials of traditional wadding are mainly silk, wool, cotton, etc., and most of them are single-material waddings with obvious advantages and disadvantages. For example, silk is soft and comfortable, and the production process is pollution-free, but its durability is poor and its price is expensive; wool wadding has good elasticity and warmth, but it has serious shrinkage and is easy to deform, and the scarcity of wool fiber resources also keeps its price high; cotton fiber has good warmth retention and is non-irritating to the human body, but it is prone to clumping and mildew.

[0003] The continuous development of my country's petrochemical industry and production technology has provided abundant raw materials for the development of my country's synthetic fiber industry. Polypropylene has a very low specific gravity, making it the lightest of the current chemical fibers, thus possessing outstanding lightweight advantages when used as a textile fiber. If its loose, soft, and warm properties are further enhanced, and it is used to make thermal insulation wadding, it has extremely broad application prospects in improving winter clothing for the military and civilians, as well as in daily necessities. Hollow polypropylene, on the other hand, is a hollow fiber with a certain degree of hollowness. It is lighter than ordinary polypropylene and has permanent crimp and a larger specific volume. Because the air layer in its structure reduces the fiber's specific gravity, it can improve the thermal insulation properties of thermal insulation wadding and fabrics, thus exhibiting greater fluffiness and warmth. However, although conventional hollow polypropylene has the advantage of being lightweight, it also has the disadvantages of poor elasticity and insufficient mechanical strength, which is detrimental to its application in textile fibers and thermal insulation wadding. In addition, the bonding between the various fibers in traditional thermal insulation wadding relies on the addition of chemical adhesives, which can easily produce harmful substances during use, seriously affecting the usability and safety of the thermal insulation wadding. Summary of the Invention

[0004] The purpose of this invention is to provide a lightweight, highly resilient hollow polypropylene composite thermal insulation wadding and its preparation method.

[0005] To achieve the above objectives, the present invention provides a lightweight, high-resilience hollow polypropylene composite thermal insulation wadding, comprising hollow polypropylene fibers, ultrafine polyester (PET) fibers, and polyethylene-polypropylene (ES) composite fibers. The hollow polypropylene fibers are prepared by the following method: polypropylene is melt-spun, and the fibers extruded from the spinneret are subjected to hot stretching and heat treatment before being cooled.

[0006] The lightweight, high-resilience hollow polypropylene composite thermal insulation wadding of the present invention has a spinning temperature of 230-270℃ and a spinning speed of 500-2500m / min.

[0007] The lightweight, high-resilience hollow polypropylene composite thermal insulation wadding of the present invention has a spinning temperature of 230-250℃ and a spinning speed of 2000-2500m / min.

[0008] The lightweight, high-resilience hollow polypropylene composite thermal insulation wadding of the present invention has a thermal stretching temperature of 120-160℃ and a thermal stretching ratio of 2-6 times.

[0009] The lightweight, high-resilience hollow polypropylene composite thermal insulation wadding of the present invention has a thermal stretching ratio of 3 to 5 times.

[0010] The lightweight, high-resilience hollow polypropylene composite thermal insulation wadding of the present invention is subjected to a no-load heat treatment at a temperature of 130–150°C for 10–30 minutes.

[0011] The lightweight, highly resilient hollow polypropylene composite thermal insulation wadding of the present invention has a cooling wind speed of 0.5 to 0.9 m / min.

[0012] The lightweight, highly resilient hollow polypropylene composite thermal insulation wadding of the present invention has a cooling wind speed of 0.7 to 0.9 m / min.

[0013] The lightweight, high-resilience hollow polypropylene composite thermal insulation wadding of the present invention contains 55-95 wt% hollow polypropylene fiber and 5-45 wt% total content of fine polyester fiber and polyethylene-polypropylene composite fiber, wherein the mass ratio of fine polyester fiber to polyethylene-polypropylene composite fiber is 0.25-2.

[0014] To achieve the above objectives, the present invention also provides a method for preparing a lightweight, high-resilience hollow polypropylene composite thermal insulation wadding, which is prepared by a needle-punching nonwoven method, and the basis weight of the wadding is set to 130-150 g / m². 2 The hot air bonding temperature is 110–130℃, and the needle-punching density is 80–120 needles / cm². 2 The depth is 8-10mm.

[0015] Beneficial effects of this invention:

[0016] (1) The hot drawing process in the spinning process helps to improve the amorphous orientation and crystalline orientation of the hollow polypropylene fiber, thereby improving the crystallinity and mechanical strength of the fiber; (2) The no-load heat treatment process in the spinning process can not only help the hollow polypropylene fiber eliminate the residual internal stress in the hot drawing process, but also help to improve the crystallinity of the fiber, further improving the crystallinity of the fiber; (3) Using the lightweight and rigid hollow polypropylene fiber with high crystallinity obtained by precise spinning process control as the matrix, fine PET fiber and ES fiber are introduced to make a hollow polypropylene composite thermal insulation wadding. The composite thermal insulation wadding first uses the melting of the skin of the ES fiber after heating to bond the fiber network, and then uses the needle punching method to reinforce the composite fiber network. The resulting composite wadding has a stable structure, and after needle punching reinforcement, a thin and fluffy thermal insulation layer is formed, which ensures the thermal insulation, fluffiness and comfort of the composite wadding. The whole processing process is simple, the process is short, and it has good production efficiency. Moreover, no harmful substances are generated during the entire production process, which is more conducive to the safety and long-term stability of the composite insulation wadding. Detailed Implementation

[0017] The present invention will now be described in detail through embodiments. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description.

[0018] Example 1

[0019] Polypropylene chips, pre-dried at 80℃ for 5 hours, were fed into the hopper of a twin-screw extruder and melt-kneaded by the screws. The screw temperatures for each section were set as follows: Section 1, 190℃; Section 2, 200℃; Sections 3-8, 230℃; Sections 9-10, 240℃. The fibers were then melt-spun through a hollow spinneret at a spinning temperature of 240℃ and a spinning speed of 2000 m / min. The resulting nascent hollow fibers were then subjected to hot stretching treatment at 150℃ with a stretch ratio of 3. Afterward, the external force was removed, and the fibers were placed at 140℃ to release residual internal stress for 20 minutes. The fibers were then cooled to room temperature at a cooling air velocity of 0.8 m / min. Finally, the fibers were wound and collected to obtain hollow polypropylene fibers.

[0020] Example 2

[0021] Polypropylene chips, pre-dried at 80℃ for 5 hours, were fed into the hopper of a twin-screw extruder and melt-kneaded by the screws. The screw temperatures for each section were set as follows: Section 1, 190℃; Section 2, 200℃; Sections 3-8, 230℃; Sections 9-10, 240℃. The fibers were then melt-spun through a hollow spinneret at a spinning temperature of 240℃ and a spinning speed of 2000 m / min. The resulting nascent hollow fibers were then subjected to hot stretching at 120℃ with a stretch ratio of 5. Afterward, the external force was removed, and the fibers were placed at 140℃ to release residual internal stress for 20 minutes. The fibers were then cooled to room temperature at a cooling air velocity of 0.8 m / min. Finally, the fibers were wound and collected to obtain hollow polypropylene fibers.

[0022] Example 3

[0023] Polypropylene chips, pre-dried at 80℃ for 5 hours, were fed into the hopper of a twin-screw extruder and melt-kneaded by the screws. The screw temperatures for each section were set as follows: Section 1, 190℃; Section 2, 200℃; Sections 3-8, 230℃; Sections 9-10, 240℃. The fibers were then melt-spun through a hollow spinneret at a spinning temperature of 230℃ and a spinning speed of 1000 m / min. The resulting nascent hollow fibers were then subjected to hot stretching at 130℃ with a stretch ratio of 2. Afterward, the external force was removed, and the fibers were placed at 130℃ to release residual internal stress for 10 minutes. The fibers were then cooled to room temperature at a cooling air velocity of 0.9 m / min. Finally, the fibers were wound and collected to obtain hollow polypropylene fibers.

[0024] Example 4

[0025] Polypropylene chips, pre-dried at 80℃ for 5 hours, were fed into the hopper of a twin-screw extruder and melt-kneaded by the screws. The screw temperatures for each section were set as follows: Section 1, 190℃; Section 2, 200℃; Sections 3-8, 230℃; Sections 9-10, 240℃. The fibers were then melt-spun through a hollow spinneret at a spinning temperature of 270℃ and a spinning speed of 2500 m / min. The resulting nascent hollow fibers were then subjected to hot stretching at 140℃ with a stretch ratio of 6. Afterward, the external force was removed, and the fibers were placed at 150℃ to release residual internal stress for 30 minutes. The fibers were then cooled to room temperature at a cooling air velocity of 0.7 m / min. Finally, the fibers were wound and collected to obtain hollow polypropylene fibers.

[0026] Comparative Example 1

[0027] Polypropylene chips, pre-dried at 80℃ for 5 hours, were fed into the hopper of a twin-screw extruder and melt-kneaded by the screws. The screw temperatures for each section were set as follows: Section 1, 190℃; Section 2, 200℃; Sections 3-8, 230℃; Sections 9-10, 240℃. The fibers were then melt-spun through a hollow spinneret at a spinning temperature of 240℃ and a spinning speed of 2000 m / min. The fibers were then cooled to room temperature at a cooling air velocity of 0.8 m / min. Finally, the fibers were wound and collected to obtain hollow polypropylene fibers.

[0028] Comparative Example 2

[0029] Polypropylene chips, pre-dried at 80℃ for 5 hours, were fed into the hopper of a twin-screw extruder and melt-kneaded by the screws. The screw temperatures for each section were set as follows: Section 1, 190℃; Section 2, 200℃; Sections 3-8, 230℃; Sections 9-10, 240℃. The fibers were then melt-spun through a hollow spinneret at a spinning temperature of 240℃ and a spinning speed of 2000 m / min. The fibers were then cooled to room temperature at a cooling air velocity of 0.8 m / min. The resulting nascent hollow fibers were then subjected to hot stretching treatment at 150℃ with a stretch ratio of 3. Afterward, the external force was removed, and the fibers were placed at 140℃ to release residual internal stress for 20 minutes. Finally, the fibers were wound and collected to obtain hollow polypropylene fibers.

[0030] The hollow polypropylene fibers prepared in the examples and comparative examples were subjected to performance tests, and the results are shown in Table 1.

[0031] Crystallinity: Take a certain sample (5mg-10mg), and under nitrogen protection, heat it from 40℃ to 200℃ (with a heating rate of 10K / min), hold it at that temperature for 5min; then cool it down to 40℃ at the same rate; use a second heating cycle, and heat it to 200℃ under the same conditions. Calculate the crystallinity (Xc) of the sample using DSC curves.

[0032] Tensile strength / elongation at break: Test method for tensile properties of chemical fiber filaments (GB / T14344-2022)

[0033] Hollowness: FZ / T 50002-2013 Test method for irregular shape of chemical fibers.

[0034] Table 1

[0035]

[0036] The performance test results of the hollow polypropylene fiber monofilaments above show that the hot drawing process can effectively improve the crystallinity and mechanical strength of the obtained hollow polypropylene fibers, while having no significant impact on the hollowness. This is beneficial for preparing lightweight, high-rigidity hollow polypropylene fibers with high crystallinity. Furthermore, the crystallinity and mechanical strength of the hollow polypropylene fibers also increase with the increase of the hot drawing ratio. As a control, the crystallinity and mechanical strength of the hollow polypropylene fibers in Comparative Example 1, which did not undergo hot drawing and no-load heat treatment, were significantly reduced. Comparative Example 2, which underwent hot drawing after cooling, showed a smaller change in crystallinity and fiber mechanical strength.

[0037] Example 5

[0038] First, weigh 55% of the hollow polypropylene fiber prepared in Example 1, 22.5% of the fine PET fiber, and 22.5% of the ES fiber, and perform two opening operations using an opening machine (to ensure thorough mixing between the different fibers); then, feed the fibers evenly into a carding machine via a feeder to form a combed web, obtaining a uniform, interwoven fiber web to ensure good stretchability and resilience; finally, spread the web evenly using a web-laying machine to control its basis weight at 130 g / m². 2 Then, the fibers are bonded in a 110°C hot air channel and allowed to cool. The surface and bottom are then needled by a pre-needling machine and a lower needle-needling machine to make them smoother and flatter, with a needle-needling density of 100 needles / cm². 2 The needle-punching depth is 10mm; then it is cut by a winding and slicing machine to finally obtain composite thermal insulation wadding.

[0039] Example 6

[0040] First, weigh 75% of the hollow polypropylene fibers prepared in Example 2, 5% of the fine PET fibers, and 20% of the ES fibers, and open them twice using an opening machine (to ensure thorough mixing between the different fibers). Then, feed them evenly into a carding machine via a cotton feeder to form a finely combed web, resulting in a uniform, interwoven fiber web to ensure good stretchability and resilience. Finally, spread the web evenly using a web-laying machine to control its basis weight at 150 g / m². 2 The fibers are then bonded in a 120°C hot air channel and allowed to cool. The surface and bottom are then needled using a pre-needling machine and a lower needle-needling machine to make them smoother and flatter, with a needle-needling density of 80 needles / cm². 2 The needle-punching depth is 8mm; then it is cut by a winding and slicing machine to finally obtain composite thermal insulation wadding.

[0041] Example 7

[0042] First, weigh 95% of the hollow polypropylene fibers prepared in Example 3, 3% of fine PET fibers, and 2% of ES fibers, and perform two opening operations using an opening machine (to ensure thorough mixing between different fibers); then, feed the fibers evenly into a carding machine via a feeder to form a finely combed web, obtaining a uniform, interwoven fiber web to ensure good stretchability and resilience; finally, spread the web evenly using a web-laying machine to control its basis weight at 130 g / m². 2 The fibers are then bonded in a 130°C hot air channel and allowed to cool. The surface and bottom are then needled using a pre-needling machine and a lower needle-needling machine to make them smoother and flatter, with a needle-needling density of 120 needles / cm². 2 The needle-punching depth is 10mm; then it is cut by a winding and slicing machine to finally obtain composite thermal insulation wadding.

[0043] Example 8

[0044] First, weigh 90% of the hollow polypropylene fibers prepared in Example 4, 5% of fine PET fibers, and 5% of ES fibers, and perform two opening operations using an opening machine (to ensure thorough mixing between different fibers). Then, feed the fibers evenly into a carding machine via a feeder to form a finely combed web, resulting in a uniform, interwoven fiber web to ensure good stretchability and resilience. Finally, spread the web evenly using a web-laying machine to control its basis weight at 150 g / m². 2 The fibers are then bonded in a 120°C hot air channel and allowed to cool. The surface and bottom are then needled using a pre-needling machine and a lower needle-needling machine to make them smoother and flatter, with a needle-needling density of 100 needles / cm². 2 The needle-punching depth is 10mm; then it is cut by a winding and slicing machine to finally obtain composite thermal insulation wadding.

[0045] Comparative Example 3

[0046] First, 100% fine PET fibers are weighed and opened twice using an opening machine. Then, they are evenly fed into a carding machine via a feeder to form a finely combed web, resulting in a uniform, interwoven fiber web. Finally, the web is evenly laid out by a web-laying machine to control its weight at 130 g / m². 2 The fibers are then bonded in a 120°C hot air channel and allowed to cool. The surface and bottom are then needled using a pre-needling machine and a lower needle-needling machine to make them smoother and flatter, with a needle-needling density of 100 needles / cm². 2 The needle-punching depth is 10mm; then it is cut by a winding and slicing machine to finally obtain PET thermal insulation wadding.

[0047] Comparative Example 4

[0048] First, 100% fine PET fibers are weighed and opened twice using an opening machine. Then, they are evenly fed into a carding machine via a feeder to form a finely combed web, resulting in a uniform, interwoven fiber web. Finally, the web is evenly laid out by a web-laying machine to control its weight at 150 g / m². 2 The fibers are then bonded in a 120°C hot air channel and allowed to cool. The surface and bottom are then needled using a pre-needling machine and a lower needle-needling machine to make them smoother and flatter, with a needle-needling density of 100 needles / cm². 2 The needle-punching depth is 10mm; then it is cut by a winding and slicing machine to finally obtain PET thermal insulation wadding.

[0049] Comparative Example 5

[0050] First, weigh 55% of the hollow polypropylene fiber prepared in Comparative Example 1, 22.5% of the fine PET fiber, and 22.5% of the ES fiber, and perform two opening operations using an opening machine (to ensure thorough mixing between the different fibers). Then, feed the fibers evenly into a carding machine via a feeder to form a finely combed web, resulting in a uniform, interwoven fiber web to ensure good stretchability and resilience. Finally, spread the web evenly using a web-laying machine to control its basis weight at 130 g / m². 2 Then, the fibers are bonded in a 110°C hot air channel and allowed to cool. The surface and bottom are then needled by a pre-needling machine and a lower needle-needling machine to make them smoother and flatter, with a needle-needling density of 100 needles / cm². 2 The needle-punching depth is 10mm; then it is cut by a winding and slicing machine to finally obtain composite thermal insulation wadding.

[0051] Comparative Example 6

[0052] First, weigh 55% of the hollow polypropylene fiber prepared in Comparative Example 2, 22.5% of the fine PET fiber, and 22.5% of the ES fiber, and perform two opening operations using an opening machine (to ensure thorough mixing between the different fibers). Then, feed the fibers evenly into a carding machine via a feeder to form a finely combed web, resulting in a uniform, interwoven fiber web to ensure good stretchability and resilience. Finally, spread the web evenly using a web-laying machine to control its basis weight at 130 g / m². 2 Then, the fibers are bonded in a 110°C hot air channel and allowed to cool. The surface and bottom are then needled by a pre-needling machine and a lower needle-needling machine to make them smoother and flatter, with a needle-needling density of 100 needles / cm². 2 The needle-punching depth is 10mm; then it is cut by a winding and slicing machine to finally obtain composite thermal insulation wadding.

[0053] Table 2

[0054]

[0055] The test results above indicate that for hollow polypropylene composite wadding, an appropriate content (55%) of hollow polypropylene combined with a certain amount (45%) of fine PET and ES fibers is beneficial to the thermal insulation performance of the final composite wadding. This is because a relatively sufficient amount of fine PET and ES fibers provides excellent bulkiness and bonding for the entire composite wadding, effectively ensuring its thermal insulation, bulkiness, and comfort (see Examples 5 and 6). Conversely, an excessively high content (95%) of hollow polypropylene combined with a very small amount (5%) of fine PET and ES fibers is detrimental to the thermal insulation performance of the final composite wadding. This is because too little fine PET and ES fibers are insufficient to provide adequate bulkiness and bonding, leading to a decrease in the overall thermal insulation performance of the composite wadding system (see Examples 7 and 8). In comparison, pure PET fibers were also processed using the same process to obtain PET thermal wadding (see Comparative Examples 3 and 4), and the thermal insulation performance of the pure PET thermal wadding was slightly lower. For the polypropylene hollow fiber composite wadding that has not undergone sufficient thermal stretching (see Comparative Examples 5 and 6), its thermal insulation performance is improved compared to Comparative Examples 3 and 4. However, due to structural limitations, there are still some differences compared to Example 5. In summary, the results show that the thermal insulation performance of the prepared hollow polypropylene composite thermal insulation wadding is significantly better than that of pure PET thermal insulation wadding, and the thermal insulation performance of the fully thermally stretched hollow polypropylene composite thermal insulation wadding is also better than that of the thermally limited hollow polypropylene composite thermal insulation wadding. The method provided by this invention has excellent development and application prospects.

[0056] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A lightweight, high-resilience hollow polypropylene composite thermal insulation wadding, characterized in that, It includes hollow polypropylene fibers, ultrafine polyester fibers, and polyethylene-polypropylene composite fibers. The hollow polypropylene fibers are prepared by the following method: polypropylene is melt-spun, and the fibers extruded from the spinneret are subjected to hot stretching and heat treatment before being cooled.

2. The lightweight, high-resilience hollow polypropylene composite thermal insulation wadding according to claim 1, characterized in that, The spinning temperature is 230–270℃, and the spinning speed is 500–2500 m / min.

3. The lightweight, high-resilience hollow polypropylene composite thermal insulation wadding according to claim 2, characterized in that, The spinning temperature is 230–250℃, and the spinning speed is 2000–2500 m / min.

4. The lightweight, high-resilience hollow polypropylene composite thermal insulation wadding according to claim 1, characterized in that, The hot drawing temperature is 120–160°C, and the hot drawing ratio is 2–6 times.

5. The lightweight, high-resilience hollow polypropylene composite thermal insulation wadding according to claim 4, characterized in that, The thermal stretching ratio is 3 to 5 times.

6. The lightweight, high-resilience hollow polypropylene composite thermal insulation wadding according to claim 1, characterized in that, The heat treatment is a no-load heat treatment, with a heat treatment temperature of 130-150℃ and a time of 10-30 minutes.

7. The lightweight, high-resilience hollow polypropylene composite thermal insulation wadding according to claim 1, characterized in that, The air velocity during cooling is 0.5 to 0.9 m / min.

8. The lightweight, high-resilience hollow polypropylene composite thermal insulation wadding according to claim 1, characterized in that, The air velocity during cooling is 0.7 to 0.9 m / min.

9. The lightweight, high-resilience hollow polypropylene composite thermal insulation wadding according to claim 1, characterized in that, The composite thermal insulation wadding contains 55-95 wt% hollow polypropylene fiber and 5-45 wt% fine polyester fiber and polyethylene-polypropylene composite fiber, with the mass ratio of fine polyester fiber to polyethylene-polypropylene composite fiber being 0.25-2.

10. A method for preparing the lightweight, high-resilience hollow polypropylene composite thermal insulation wadding according to any one of claims 1 to 5, characterized in that, The wadding was prepared using a needle-punching nonwoven method, with a basis weight of 130–150 g / m². 2 The hot air bonding temperature is 110–130℃, and the needle-punching density is 80–120 needles / cm². 2 The depth is 8-10mm.

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