Medical dialysis paper and preparation method thereof

Abstract

A high-toughness sheath-core fiber, medical dialysis paper, and a preparation method thereof are provided. According to the present disclosure, a certain proportion of cellulose nanofibers are added to the polyethylene sheath layer and the polypropylene core layer respectively for melt blending to obtain a sheath component and a core component, then coaxial melt electrospinning is performed to obtain the high-toughness sheath-core fiber. The high-toughness sheath-core fiber is added to the raw materials of the medical dialysis paper at a mass ratio of 2-20%. After wet papermaking, the sheath layer of the fiber is melt-bonded using a hot-pressing method, which allows the substances between the sheath layers to melt and mix, improving the paper strength. The prepared medical dialysis paper exhibits excellent antibacterial property.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The application claims priority to Chinese patent application No. 2024105505434, filed on May 6, 2024, the entire contents of which are incorporated herein by reference.TECHNICAL FIELD

[0002] The present disclosure relates to the field of composite fiber materials technology, and in particular to a high-toughness sheath-core fiber, medical dialysis paper, and a preparation method thereof.BACKGROUND

[0003] Sheath-core fibers with polyethylene (PE)-polypropylene (PP) as the main components have few surface active groups. When such fibers are used as raw materials for preparing medical dialysis paper, the resulting paper has a loose structure and poor physical strength. Hot-pressing treatment is therefore required to improve the density, thereby forming dense bonding and endowing the paper with high physical strength. However, due to the great difference in thermal shrinkage between the sheath layer and the core layer, gap-type interfaces appear in some areas between the PE sheath layer and the PP core layer inside a single fiber. This increases the porosity of the paper sheet and impairs its antibacterial property.SUMMARY

[0004] It is an object of the present disclosure to overcome the shortcomings of the prior art and provide a high-toughness sheath-core fiber, medical dialysis paper and a preparation method thereof.

[0005] The present disclosure provides the following technical solutions:

[0006] The present disclosure provides a high-toughness sheath-core fiber, including a sheath layer and a core layer, wherein the sheath layer accounts for 20-30% of the mass of the sheath-core fiber, and the core layer accounts for 70-80% of the mass of the sheath-core fiber. The sheath layer is composed of 80-95% polyethylene and 5-20% cellulose nanofibers in percentage by mass, and the core layer is composed of 80-95% polypropylene and 5-20% cellulose nanofibers in percentage by mass.

[0007] The present disclosure further provides a method for preparing the high-toughness sheath-core fiber, including the following steps:

[0008] S1, melt-blending cellulose nanofibers with polyethylene at a mass ratio of (5-20):(80-95) to obtain a sheath component;

[0009] S2, melt-blending cellulose nanofibers with polypropylene at a mass ratio of (5-20):(80-95) to obtain a core component;

[0010] S3, adding the sheath component to melting channel A, adding the core component to melting channel B, performing coaxial melt electrospinning to obtain the high-toughness sheath-core fiber.

[0011] Since the components of the PE-PP sheath-core fiber are inert fibers, there is no connection between the sheath and the core inside a single fiber. In addition, the great difference in their thermal shrinkage leads to poor physical properties of the fiber. After adding cellulose nanofibers to the sheath layer and the core layer respectively, the cellulose in the sheath layer and the core layer will form hydrogen bond connections through hydroxyl groups, resulting in a tighter connection and improved toughness of the fibers. In the present disclosure, the addition of 5-20% cellulose nanofibers will not affect the melting property of the sheath layer or the supporting property of the core layer. When 20% cellulose nanofibers are added, the elongation at break of the sheath-core fiber is doubled, achieving high toughness.

[0012] Further, the length of the cellulose nanofibers is 5-20 nm.

[0013] Further, in the step S1, cellulose nanofibers are melt-blended with polyethylene in an internal mixer at 130° C. and 50 r / min for 5-10 minutes.

[0014] Further, in the step S2, cellulose nanofibers are melt-blended with polypropylene in an internal mixer at 170° C. and 50 r / min for 5-10 minutes.

[0015] Further, the temperature of the melting channel A is 140° C., and the temperature of the melting channel B is 180° C., coaxial needles with an inner diameter of 22 G and an outer diameter of 16 G are used as spinning needles.

[0016] Further, the melt electrospinning process conditions are as follows: voltage: 25-40 kV, spinning distance: 25-30 cm, roller speed: 200-800 r / min, propulsion speed: 0.4-0.8 mL / h.

[0017] Based on the same inventive concept, the present disclosure further provides a method for preparing medical dialysis paper. The method includes adding the aforementioned prepared high-toughness sheath-core fiber to plant fiber raw materials at 2-20% of the total mass, after fiber dispersion, inclined wire forming, pressing, and drying, conducting hot pressing and cold air treatment at 135-140° C. to obtain the medical dialysis paper.

[0018] When sheath-core fibers without cellulose nanofibers are used to make paper through hot pressing, the sheath layer melts. Since both the sheath layer and the core layer are composed of inert fibers, there is no connection between them inside a single fiber, and their thermal shrinkage differs greatly. This causes gaps between the sheath layer and the core layer of a single fiber, further increasing the porosity of the paper sheet and affecting its antibacterial property. During the hot-press forming of the paper sheet, by adding cellulose nanofibers to the sheath-core fiber, the cellulose in the sheath layer and the core layer forms hydrogen bond connections through hydroxyl groups, which enhances the connection tightness, avoids the formation of gaps, optimizes the pore structure of the paper sheet, and improves the antibacterial property of the paper sheet.

[0019] The present disclosure has the following beneficial effects:

[0020] 1. By mixing cellulose nanofibers (CNF) into molten PE and PP, the present disclosure enables the PE fibers of sheath layers to achieve good melting during the hot pressing of the sheath-core fibers. Meanwhile, the CNF between the fibers of sheath layers forms hydrogen bond connections, thereby improving the bonding strength.

[0021] 2. During the hot pressing, hydrogen bond connections are also formed at the interface between the PE sheath layer and the PP core layer inside a single fiber. This reduces the interface gap between the sheath and the core, improves the strength of the formed paper, and optimizes the porosity of the paper sheet, thereby enhancing its antibacterial property. A mutually interlaced transition zone interface is formed between the PE sheath layer and the PP core layer, which allows uniform stress transfer inside the fiber, prevents crack propagation and mitigates stress concentration.BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to illustrate the technical solutions in the embodiments of the present disclosure or the prior art more clearly, the accompanying drawings used in the description of the embodiments or the prior art will be described briefly below. Apparently, the drawings described below are only a part of embodiments of the present disclosure, and other drawings can be obtained by persons of ordinary skill in the art based on these drawings without creative effort.

[0023] FIG. 1 is a scanning electron microscope (SEM) image of the sheath-core fiber prepared in Example 1 of the present disclosure; and

[0024] FIG. 2 is a microscopic morphology diagram of the medical dialysis paper prepared in Example 5 of the present disclosure.DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The technical solutions in the embodiments of the present disclosure are clearly and completely described with reference to the accompanying drawings of the embodiments of the present disclosure. Apparently, the described embodiments are only a part of embodiments of the present disclosure, and are not all of embodiments thereof. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments of the present disclosure without creative efforts shall fall within the protection scope of the present disclosure.

[0026] The present disclosure provides a high-toughness sheath-core fiber, including a sheath layer and a core layer, wherein the sheath layer accounts for 20-30% of the mass of the sheath-core fiber, and the core layer accounts for 70-80% of the mass of the sheath-core fiber. The sheath layer is composed of 80-95% polyethylene and 5-20% cellulose nanofibers in percentage by mass, and the core layer is composed of 80-95% polypropylene and 5-20% cellulose nanofibers in percentage by mass.

[0027] Based on the same inventive concept, embodiments of the present disclosure provide a method for preparing the high-toughness sheath-core fiber, including the following steps:

[0028] S1, melt-blending cellulose nanofibers with polyethylene at a mass ratio of (5-20):(80-95) to obtain a sheath component;

[0029] S2, melt-blending cellulose nanofibers with polypropylene at a mass ratio of (5-20):(80-95) to obtain a core component;

[0030] S3, adding the sheath component to melting channel A, adding the core component to melting channel B, performing coaxial melt electrospinning to obtain the high-toughness sheath-core fiber.

[0031] The mass ratio of the sheath component to the core component is (20-30):(70-80), and the total mass of the two components is 100 wt %. Preferably, the mixing percentage of cellulose nanofibers in the sheath component and the core component is the same.

[0032] In a specific embodiment, the length of the cellulose nanofibers is 5-20 nm.

[0033] In a specific embodiment, in the step S1, cellulose nanofibers are melt-blended with polyethylene in an internal mixer at 130° C. and 50 r / min for 5-10 minutes.

[0034] In a specific embodiment, in the step S2, cellulose nanofibers are melt-blended with polypropylene in an internal mixer at 170° C. and 50 r / min for 5-10 minutes.

[0035] In a specific embodiment, the temperature of the melting channel Ais 140° C., and the temperature of the melting channel B is 180° C., coaxial needles with an inner diameter of 22 G and an outer diameter of 16 G are used as spinning needles.

[0036] In a specific embodiment, the melt electrospinning process conditions are as follows: voltage: 25-40 kV, spinning distance: 25-30 cm, roller speed: 200-800 r / min, propulsion speed: 0.4-0.8 mL / h.

[0037] Based on the same inventive concept, embodiments of the present disclosure further provide use of the high-toughness sheath-core fiber, i.e., a method for preparing medical dialysis paper. The method includes adding the aforementioned prepared high-toughness sheath-core fiber to plant fiber raw materials at 5-20% of the total mass, after fiber dispersion, inclined wire forming, pressing, and drying, conducting hot pressing and cold air treatment at 135-140° C. to obtain the medical dialysis paper.

[0038] The present disclosure will be further illustrated below with specific embodiments.

[0039] All materials used in the following embodiments were commercially available. Cellulose nanofibers were purchased from Shanghai Macklin Biochemical Technology Co., Ltd., and polyethylene and polypropylene were purchased from Zhejiang Sunrise Basic Chemical Co., Ltd.Example 1

[0040] A method for preparing a high-toughness sheath-core fiber was provided, including the following steps:

[0041] 1, cellulose nanofibers (CNF) were melt-blended with polyethylene in a HAAKE mixer in a mass ratio of 1:4 at 130° C. and 50 r / min for 5-10 minutes to obtain a sheath component;

[0042] 2, cellulose nanofibers (CNF) were melt-blended with polypropylene in a HAAKE mixer in a mass ratio of 1:4 at 170° C. and 50 r / min for 5-10 minutes to obtain a core component;

[0043] 3, 25 wt % of the sheath component was added to the melting channel A, and 75 wt % of the core component was added to the melting channel B, and coaxial melt electrospinning was performed. The temperature of the melting channel A was set to 140° C., and the temperature of the melting channel B was set to 180° C. Coaxial needles with an inner diameter of 22 G and an outer diameter of 16 G were used as spinning needles. The melt electrospinning process conditions were as follows: voltage: 25-40 kV, spinning distance: 25-30 cm, roller speed: 200-800 r / min, propulsion speed: 0.4-0.8 mL / h.Example 2

[0044] The mixing percentage of cellulose nanofibers in both the sheath component and the core component was 15%; other steps were the same as those in Example 1.Example 3

[0045] The mixing percentage of cellulose nanofibers in both the sheath component and the core component was 10%; other steps were the same as those in Example 1.Example 4

[0046] The mixing percentage of cellulose nanofibers in both the sheath component and the core component was 5%; other steps were the same as those in Example 1.Comparative Example 1

[0047] In this comparative example, 25 wt % of polyethylene as the sheath component was added to the melting channel A, and 75 wt % of polypropylene as the core component was added to the melting channel B, and coaxial melt electrospinning was performed to obtain a PE-PP sheath-core fiber. The temperature of the melting channel A was set to 140° C., and the temperature of the melting channel B was set to 180° C. Coaxial needles with an inner diameter of 22 G and an outer diameter of 16 G were used as spinning needles. The melt electrospinning process conditions were as follows: voltage: 25-40 kV, spinning distance: 25-30 cm, roller speed: 200-800 r / min, propulsion speed: 0.4-0.8 mL / h.Comparative Example 2

[0048] The mixing percentage of cellulose nanofibers in both the sheath component and the core component was 2%; other steps were the same as those in Example 1.Example 5

[0049] Medical dialysis paper was prepared in the example, including the following steps:

[0050] The high-toughness sheath-core fibers prepared in Example 1 were added to plant fiber raw materials (softwood pulp, hardwood pulp) at 5% of the total mass, and after wet papermaking (fiber dispersion, inclined wire forming, pressing, and drying), hot pressing and cold air treatment were conducted at 135-140° C. to obtain the medical dialysis paper.Example 6

[0051] The high-toughness sheath-core fibers prepared in Example 1 were added to the papermaking fiber raw materials at 10% of the total mass. After wet papermaking, hot pressing and cold air treatment were conducted at 135-140° C. to obtain the medical dialysis paper.Example 7

[0052] The high-toughness sheath-core fibers prepared in Example 1 were added to the papermaking fiber raw materials at 15% of the total mass. After wet papermaking, hot pressing and cold air treatment were conducted at 135-140° C. to obtain the medical dialysis paper.Example 8

[0053] The high-toughness sheath-core fibers prepared in Example 1 were added to the papermaking fiber raw materials at 20% of the total mass. After wet papermaking, hot pressing and cold air treatment were conducted at 135-140° C. to obtain the medical dialysis paper.Example 9

[0054] The high-toughness sheath-core fibers prepared in Example 1 were added to the papermaking fiber raw materials at 2% of the total mass. After wet papermaking, hot pressing and cold air treatment were conducted at 135-140° C. to obtain the medical dialysis paper.Test Example

[0055] 1) The breaking elongation test of the sheath-core fibers obtained in Examples 1-4 and Comparative Examples 1-2 was conducted according to GB / T 19975-2005 Test method of tensile properties for high tenacity filament yarn. The results are shown in Table 1.TABLE 1Data of elongation at break of sheath-corefibers prepared in various examplesAdded amountElongationof CNF, %at break, %Comparative Example 102.8%Comparative Example 223.1%Example 153.5%Example 2104.2%Example 3155.3%Example 4205.6%

[0056] In the present disclosure, adding 5-20% cellulose nanofibers did not affect the melting of the sheath and the supporting performance of the core. As shown in FIG. 1, the sheath and core of the sheath-core fibers prepared in Example 1 were tightly connected. After adding 20% cellulose nanofibers, the elongation at break of the sheath-core fiber was doubled, with a high toughness.

[0057] 2) Performance analysis and testing of medical dialysis paper prepared without added core and sheath fibers in Examples 5-9:

[0058] Air permeability: The air permeability of the paper was measured using an air permeability meter (Beijing Libero Technology Co., Ltd., model TEXTEST FX3300-IV). The test area was 20 cm2, and the test pressure was 200 Pa.

[0059] Antibacterial property: The agar contact attack method was used for testing according to standard DIN 58953-6-2010.

[0060] Burning strength index: The bursting strength index of the paper was measured using a computer-controlled paper bursting strength tester (Hangzhou PNSHAR Co., Ltd., model PN-BSM160) according to GB / T 454-2002.

[0061] Average pore size: The paper sample was cut into pieces approximately 3 cm×3 cm in size, then soaked in ethanol for 10 minutes. The pore size was measured using a porous material pore size analyzer (PSDA-20, Nanjing GaoQ Functional Materials Co., Ltd.).

[0062] Tensile index and wet tensile index: According to GB / T 12914-2018 and GB / T 465.2-2008, the dry and wet tensile strengths of paper were determined using a horizontal computerized tensile tester (Hangzhou Qingtong Boke Automation Technology Co., Ltd., model WZL-300B).

[0063] The test results are shown in Table 2.TABLE 2Performance data of medical dialysis paper prepared in various examplesAddedLongitudinalamount ofAirBurstingAverageLongitudinalwet tensilesheath-corepermeabilityAntibacterialindexpore sizetensile indexindexfiber (%)(μm / Pa · s)property (%)(kPa · m2 / g)(μm)(N · m / g)(N · m / g)05.099.95.016.0901924.899.95.715.4982254.999.96.315.810925104.899.97.915.212529154.699.98.614.614332204.599.98.914.213230

[0064] The interfacial bonding between fibers directly affected the strength properties of medical dialysis materials, especially their impact resistance, lateral tensile strength, and fracture toughness. The interfacial bonding mainly depended on the fiber surface condition and the degree of fiber softening and melting upon heating. As shown in Table 2 and FIG. 2, there were abundant connections between individual fibers, which greatly improved the paper's strength properties.

[0065] According to the present disclosure, cellulose nanofibers (CNF) were incorporated into molten PE and PP, enabling the PE fibers of sheath layers to achieve good melting during the hot pressing of the sheath-core fibers. Meanwhile, the CNF between the fibers of sheath layers forms hydrogen bond connections, thereby improving the bonding strength. During hot-press bonding, hydrogen bond connections are also formed at the interface between the PE sheath layer and the PP core layer inside a single fiber. This reduces the interface gap between the sheath and the core, improves the strength of the formed paper, and optimizes the porosity of the paper sheet, thereby enhancing its antibacterial property. A mutually interlaced transition zone interface is formed between the PE sheath layer and the PP core layer, which allows uniform stress transfer inside the fiber, prevents crack propagation and mitigates stress concentration.

[0066] The foregoing description only describes preferred embodiments of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements made without departing from the spirit and principles of the present disclosure shall fall within the scope of protection of the present disclosure.

Examples

example 1

[0040]A method for preparing a high-toughness sheath-core fiber was provided, including the following steps:[0041]1, cellulose nanofibers (CNF) were melt-blended with polyethylene in a HAAKE mixer in a mass ratio of 1:4 at 130° C. and 50 r / min for 5-10 minutes to obtain a sheath component;[0042]2, cellulose nanofibers (CNF) were melt-blended with polypropylene in a HAAKE mixer in a mass ratio of 1:4 at 170° C. and 50 r / min for 5-10 minutes to obtain a core component;[0043]3, 25 wt % of the sheath component was added to the melting channel A, and 75 wt % of the core component was added to the melting channel B, and coaxial melt electrospinning was performed. The temperature of the melting channel A was set to 140° C., and the temperature of the melting channel B was set to 180° C. Coaxial needles with an inner diameter of 22 G and an outer diameter of 16 G were used as spinning needles. The melt electrospinning process conditions were as follows: voltage: 25-40 kV, spinning distance:...

example 2

[0044]The mixing percentage of cellulose nanofibers in both the sheath component and the core component was 15%; other steps were the same as those in Example 1.

example 3

[0045]The mixing percentage of cellulose nanofibers in both the sheath component and the core component was 10%; other steps were the same as those in Example 1.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The application claims priority to Chinese patent application No. 2024105505434, filed on May 6, 2024, the entire contents of which are incorporated herein by reference.TECHNICAL FIELD

[0002] The present disclosure relates to the field of composite fiber materials technology, and in particular to a high-toughness sheath-core fiber, medical dialysis paper, and a preparation method thereof.BACKGROUND

[0003] Sheath-core fibers with polyethylene (PE)-polypropylene (PP) as the main components have few surface active groups. When such fibers are used as raw materials for preparing medical dialysis paper, the resulting paper has a loose structure and poor physical strength. Hot-pressing treatment is therefore required to improve the density, thereby forming dense bonding and endowing the paper with high physical strength. However, due to the great difference in thermal shrinkage between the sheath layer and the core layer, gap-type interfaces appear in some areas between the PE sheath layer and the PP core layer inside a single fiber. This increases the porosity of the paper sheet and impairs its antibacterial property.SUMMARY

[0004] It is an object of the present disclosure to overcome the shortcomings of the prior art and provide a high-toughness sheath-core fiber, medical dialysis paper and a preparation method thereof.

[0005] The present disclosure provides the following technical solutions:

[0006] The present disclosure provides a high-toughness sheath-core fiber, including a sheath layer and a core layer, wherein the sheath layer accounts for 20-30% of the mass of the sheath-core fiber, and the core layer accounts for 70-80% of the mass of the sheath-core fiber. The sheath layer is composed of 80-95% polyethylene and 5-20% cellulose nanofibers in percentage by mass, and the core layer is composed of 80-95% polypropylene and 5-20% cellulose nanofibers in percentage by mass.

[0007] The present disclosure further provides a method for preparing the high-toughness sheath-core fiber, including the following steps:

[0008] S1, melt-blending cellulose nanofibers with polyethylene at a mass ratio of (5-20):(80-95) to obtain a sheath component;

[0009] S2, melt-blending cellulose nanofibers with polypropylene at a mass ratio of (5-20):(80-95) to obtain a core component;

[0010] S3, adding the sheath component to melting channel A, adding the core component to melting channel B, performing coaxial melt electrospinning to obtain the high-toughness sheath-core fiber.

[0011] Since the components of the PE-PP sheath-core fiber are inert fibers, there is no connection between the sheath and the core inside a single fiber. In addition, the great difference in their thermal shrinkage leads to poor physical properties of the fiber. After adding cellulose nanofibers to the sheath layer and the core layer respectively, the cellulose in the sheath layer and the core layer will form hydrogen bond connections through hydroxyl groups, resulting in a tighter connection and improved toughness of the fibers. In the present disclosure, the addition of 5-20% cellulose nanofibers will not affect the melting property of the sheath layer or the supporting property of the core layer. When 20% cellulose nanofibers are added, the elongation at break of the sheath-core fiber is doubled, achieving high toughness.

[0012] Further, the length of the cellulose nanofibers is 5-20 nm.

[0013] Further, in the step S1, cellulose nanofibers are melt-blended with polyethylene in an internal mixer at 130° C. and 50 r / min for 5-10 minutes.

[0014] Further, in the step S2, cellulose nanofibers are melt-blended with polypropylene in an internal mixer at 170° C. and 50 r / min for 5-10 minutes.

[0015] Further, the temperature of the melting channel A is 140° C., and the temperature of the melting channel B is 180° C., coaxial needles with an inner diameter of 22 G and an outer diameter of 16 G are used as spinning needles.

[0016] Further, the melt electrospinning process conditions are as follows: voltage: 25-40 kV, spinning distance: 25-30 cm, roller speed: 200-800 r / min, propulsion speed: 0.4-0.8 mL / h.

[0017] Based on the same inventive concept, the present disclosure further provides a method for preparing medical dialysis paper. The method includes adding the aforementioned prepared high-toughness sheath-core fiber to plant fiber raw materials at 2-20% of the total mass, after fiber dispersion, inclined wire forming, pressing, and drying, conducting hot pressing and cold air treatment at 135-140° C. to obtain the medical dialysis paper.

[0018] When sheath-core fibers without cellulose nanofibers are used to make paper through hot pressing, the sheath layer melts. Since both the sheath layer and the core layer are composed of inert fibers, there is no connection between them inside a single fiber, and their thermal shrinkage differs greatly. This causes gaps between the sheath layer and the core layer of a single fiber, further increasing the porosity of the paper sheet and affecting its antibacterial property. During the hot-press forming of the paper sheet, by adding cellulose nanofibers to the sheath-core fiber, the cellulose in the sheath layer and the core layer forms hydrogen bond connections through hydroxyl groups, which enhances the connection tightness, avoids the formation of gaps, optimizes the pore structure of the paper sheet, and improves the antibacterial property of the paper sheet.

[0019] The present disclosure has the following beneficial effects:

[0020] 1. By mixing cellulose nanofibers (CNF) into molten PE and PP, the present disclosure enables the PE fibers of sheath layers to achieve good melting during the hot pressing of the sheath-core fibers. Meanwhile, the CNF between the fibers of sheath layers forms hydrogen bond connections, thereby improving the bonding strength.

[0021] 2. During the hot pressing, hydrogen bond connections are also formed at the interface between the PE sheath layer and the PP core layer inside a single fiber. This reduces the interface gap between the sheath and the core, improves the strength of the formed paper, and optimizes the porosity of the paper sheet, thereby enhancing its antibacterial property. A mutually interlaced transition zone interface is formed between the PE sheath layer and the PP core layer, which allows uniform stress transfer inside the fiber, prevents crack propagation and mitigates stress concentration.BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to illustrate the technical solutions in the embodiments of the present disclosure or the prior art more clearly, the accompanying drawings used in the description of the embodiments or the prior art will be described briefly below. Apparently, the drawings described below are only a part of embodiments of the present disclosure, and other drawings can be obtained by persons of ordinary skill in the art based on these drawings without creative effort.

[0023] FIG. 1 is a scanning electron microscope (SEM) image of the sheath-core fiber prepared in Example 1 of the present disclosure; and

[0024] FIG. 2 is a microscopic morphology diagram of the medical dialysis paper prepared in Example 5 of the present disclosure.DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The technical solutions in the embodiments of the present disclosure are clearly and completely described with reference to the accompanying drawings of the embodiments of the present disclosure. Apparently, the described embodiments are only a part of embodiments of the present disclosure, and are not all of embodiments thereof. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments of the present disclosure without creative efforts shall fall within the protection scope of the present disclosure.

[0026] The present disclosure provides a high-toughness sheath-core fiber, including a sheath layer and a core layer, wherein the sheath layer accounts for 20-30% of the mass of the sheath-core fiber, and the core layer accounts for 70-80% of the mass of the sheath-core fiber. The sheath layer is composed of 80-95% polyethylene and 5-20% cellulose nanofibers in percentage by mass, and the core layer is composed of 80-95% polypropylene and 5-20% cellulose nanofibers in percentage by mass.

[0027] Based on the same inventive concept, embodiments of the present disclosure provide a method for preparing the high-toughness sheath-core fiber, including the following steps:

[0028] S1, melt-blending cellulose nanofibers with polyethylene at a mass ratio of (5-20):(80-95) to obtain a sheath component;

[0029] S2, melt-blending cellulose nanofibers with polypropylene at a mass ratio of (5-20):(80-95) to obtain a core component;

[0030] S3, adding the sheath component to melting channel A, adding the core component to melting channel B, performing coaxial melt electrospinning to obtain the high-toughness sheath-core fiber.

[0031] The mass ratio of the sheath component to the core component is (20-30):(70-80), and the total mass of the two components is 100 wt %. Preferably, the mixing percentage of cellulose nanofibers in the sheath component and the core component is the same.

[0032] In a specific embodiment, the length of the cellulose nanofibers is 5-20 nm.

[0033] In a specific embodiment, in the step S1, cellulose nanofibers are melt-blended with polyethylene in an internal mixer at 130° C. and 50 r / min for 5-10 minutes.

[0034] In a specific embodiment, in the step S2, cellulose nanofibers are melt-blended with polypropylene in an internal mixer at 170° C. and 50 r / min for 5-10 minutes.

[0035] In a specific embodiment, the temperature of the melting channel Ais 140° C., and the temperature of the melting channel B is 180° C., coaxial needles with an inner diameter of 22 G and an outer diameter of 16 G are used as spinning needles.

[0036] In a specific embodiment, the melt electrospinning process conditions are as follows: voltage: 25-40 kV, spinning distance: 25-30 cm, roller speed: 200-800 r / min, propulsion speed: 0.4-0.8 mL / h.

[0037] Based on the same inventive concept, embodiments of the present disclosure further provide use of the high-toughness sheath-core fiber, i.e., a method for preparing medical dialysis paper. The method includes adding the aforementioned prepared high-toughness sheath-core fiber to plant fiber raw materials at 5-20% of the total mass, after fiber dispersion, inclined wire forming, pressing, and drying, conducting hot pressing and cold air treatment at 135-140° C. to obtain the medical dialysis paper.

[0038] The present disclosure will be further illustrated below with specific embodiments.

[0039] All materials used in the following embodiments were commercially available. Cellulose nanofibers were purchased from Shanghai Macklin Biochemical Technology Co., Ltd., and polyethylene and polypropylene were purchased from Zhejiang Sunrise Basic Chemical Co., Ltd.Example 1

[0040] A method for preparing a high-toughness sheath-core fiber was provided, including the following steps:

[0041] 1, cellulose nanofibers (CNF) were melt-blended with polyethylene in a HAAKE mixer in a mass ratio of 1:4 at 130° C. and 50 r / min for 5-10 minutes to obtain a sheath component;

[0042] 2, cellulose nanofibers (CNF) were melt-blended with polypropylene in a HAAKE mixer in a mass ratio of 1:4 at 170° C. and 50 r / min for 5-10 minutes to obtain a core component;

[0043] 3, 25 wt % of the sheath component was added to the melting channel A, and 75 wt % of the core component was added to the melting channel B, and coaxial melt electrospinning was performed. The temperature of the melting channel A was set to 140° C., and the temperature of the melting channel B was set to 180° C. Coaxial needles with an inner diameter of 22 G and an outer diameter of 16 G were used as spinning needles. The melt electrospinning process conditions were as follows: voltage: 25-40 kV, spinning distance: 25-30 cm, roller speed: 200-800 r / min, propulsion speed: 0.4-0.8 mL / h.Example 2

[0044] The mixing percentage of cellulose nanofibers in both the sheath component and the core component was 15%; other steps were the same as those in Example 1.Example 3

[0045] The mixing percentage of cellulose nanofibers in both the sheath component and the core component was 10%; other steps were the same as those in Example 1.Example 4

[0046] The mixing percentage of cellulose nanofibers in both the sheath component and the core component was 5%; other steps were the same as those in Example 1.Comparative Example 1

[0047] In this comparative example, 25 wt % of polyethylene as the sheath component was added to the melting channel A, and 75 wt % of polypropylene as the core component was added to the melting channel B, and coaxial melt electrospinning was performed to obtain a PE-PP sheath-core fiber. The temperature of the melting channel A was set to 140° C., and the temperature of the melting channel B was set to 180° C. Coaxial needles with an inner diameter of 22 G and an outer diameter of 16 G were used as spinning needles. The melt electrospinning process conditions were as follows: voltage: 25-40 kV, spinning distance: 25-30 cm, roller speed: 200-800 r / min, propulsion speed: 0.4-0.8 mL / h.Comparative Example 2

[0048] The mixing percentage of cellulose nanofibers in both the sheath component and the core component was 2%; other steps were the same as those in Example 1.Example 5

[0049] Medical dialysis paper was prepared in the example, including the following steps:

[0050] The high-toughness sheath-core fibers prepared in Example 1 were added to plant fiber raw materials (softwood pulp, hardwood pulp) at 5% of the total mass, and after wet papermaking (fiber dispersion, inclined wire forming, pressing, and drying), hot pressing and cold air treatment were conducted at 135-140° C. to obtain the medical dialysis paper.Example 6

[0051] The high-toughness sheath-core fibers prepared in Example 1 were added to the papermaking fiber raw materials at 10% of the total mass. After wet papermaking, hot pressing and cold air treatment were conducted at 135-140° C. to obtain the medical dialysis paper.Example 7

[0052] The high-toughness sheath-core fibers prepared in Example 1 were added to the papermaking fiber raw materials at 15% of the total mass. After wet papermaking, hot pressing and cold air treatment were conducted at 135-140° C. to obtain the medical dialysis paper.Example 8

[0053] The high-toughness sheath-core fibers prepared in Example 1 were added to the papermaking fiber raw materials at 20% of the total mass. After wet papermaking, hot pressing and cold air treatment were conducted at 135-140° C. to obtain the medical dialysis paper.Example 9

[0054] The high-toughness sheath-core fibers prepared in Example 1 were added to the papermaking fiber raw materials at 2% of the total mass. After wet papermaking, hot pressing and cold air treatment were conducted at 135-140° C. to obtain the medical dialysis paper.Test Example

[0055] 1) The breaking elongation test of the sheath-core fibers obtained in Examples 1-4 and Comparative Examples 1-2 was conducted according to GB / T 19975-2005 Test method of tensile properties for high tenacity filament yarn. The results are shown in Table 1.TABLE 1Data of elongation at break of sheath-corefibers prepared in various examplesAdded amountElongationof CNF, %at break, %Comparative Example 102.8%Comparative Example 223.1%Example 153.5%Example 2104.2%Example 3155.3%Example 4205.6%

[0056] In the present disclosure, adding 5-20% cellulose nanofibers did not affect the melting of the sheath and the supporting performance of the core. As shown in FIG. 1, the sheath and core of the sheath-core fibers prepared in Example 1 were tightly connected. After adding 20% cellulose nanofibers, the elongation at break of the sheath-core fiber was doubled, with a high toughness.

[0057] 2) Performance analysis and testing of medical dialysis paper prepared without added core and sheath fibers in Examples 5-9:

[0058] Air permeability: The air permeability of the paper was measured using an air permeability meter (Beijing Libero Technology Co., Ltd., model TEXTEST FX3300-IV). The test area was 20 cm2, and the test pressure was 200 Pa.

[0059] Antibacterial property: The agar contact attack method was used for testing according to standard DIN 58953-6-2010.

[0060] Burning strength index: The bursting strength index of the paper was measured using a computer-controlled paper bursting strength tester (Hangzhou PNSHAR Co., Ltd., model PN-BSM160) according to GB / T 454-2002.

[0061] Average pore size: The paper sample was cut into pieces approximately 3 cm×3 cm in size, then soaked in ethanol for 10 minutes. The pore size was measured using a porous material pore size analyzer (PSDA-20, Nanjing GaoQ Functional Materials Co., Ltd.).

[0062] Tensile index and wet tensile index: According to GB / T 12914-2018 and GB / T 465.2-2008, the dry and wet tensile strengths of paper were determined using a horizontal computerized tensile tester (Hangzhou Qingtong Boke Automation Technology Co., Ltd., model WZL-300B).

[0063] The test results are shown in Table 2.TABLE 2Performance data of medical dialysis paper prepared in various examplesAddedLongitudinalamount ofAirBurstingAverageLongitudinalwet tensilesheath-corepermeabilityAntibacterialindexpore sizetensile indexindexfiber (%)(μm / Pa · s)property (%)(kPa · m2 / g)(μm)(N · m / g)(N · m / g)05.099.95.016.0901924.899.95.715.4982254.999.96.315.810925104.899.97.915.212529154.699.98.614.614332204.599.98.914.213230

[0064] The interfacial bonding between fibers directly affected the strength properties of medical dialysis materials, especially their impact resistance, lateral tensile strength, and fracture toughness. The interfacial bonding mainly depended on the fiber surface condition and the degree of fiber softening and melting upon heating. As shown in Table 2 and FIG. 2, there were abundant connections between individual fibers, which greatly improved the paper's strength properties.

[0065] According to the present disclosure, cellulose nanofibers (CNF) were incorporated into molten PE and PP, enabling the PE fibers of sheath layers to achieve good melting during the hot pressing of the sheath-core fibers. Meanwhile, the CNF between the fibers of sheath layers forms hydrogen bond connections, thereby improving the bonding strength. During hot-press bonding, hydrogen bond connections are also formed at the interface between the PE sheath layer and the PP core layer inside a single fiber. This reduces the interface gap between the sheath and the core, improves the strength of the formed paper, and optimizes the porosity of the paper sheet, thereby enhancing its antibacterial property. A mutually interlaced transition zone interface is formed between the PE sheath layer and the PP core layer, which allows uniform stress transfer inside the fiber, prevents crack propagation and mitigates stress concentration.

[0066] The foregoing description only describes preferred embodiments of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements made without departing from the spirit and principles of the present disclosure shall fall within the scope of protection of the present disclosure.

Examples

example 1

[0040]A method for preparing a high-toughness sheath-core fiber was provided, including the following steps:[0041]1, cellulose nanofibers (CNF) were melt-blended with polyethylene in a HAAKE mixer in a mass ratio of 1:4 at 130° C. and 50 r / min for 5-10 minutes to obtain a sheath component;[0042]2, cellulose nanofibers (CNF) were melt-blended with polypropylene in a HAAKE mixer in a mass ratio of 1:4 at 170° C. and 50 r / min for 5-10 minutes to obtain a core component;[0043]3, 25 wt % of the sheath component was added to the melting channel A, and 75 wt % of the core component was added to the melting channel B, and coaxial melt electrospinning was performed. The temperature of the melting channel A was set to 140° C., and the temperature of the melting channel B was set to 180° C. Coaxial needles with an inner diameter of 22 G and an outer diameter of 16 G were used as spinning needles. The melt electrospinning process conditions were as follows: voltage: 25-40 kV, spinning distance:...

example 2

[0044]The mixing percentage of cellulose nanofibers in both the sheath component and the core component was 15%; other steps were the same as those in Example 1.

example 3

[0045]The mixing percentage of cellulose nanofibers in both the sheath component and the core component was 10%; other steps were the same as those in Example 1.

Claims

1. A method for preparing medical dialysis paper, wherein high-toughness sheath-core fibers are added to plant fiber raw materials at 15-20% of the total mass, and after fiber dispersion, inclined wire forming, pressing, and drying, hot pressing and cold air treatment are conducted at 135-140° C. to obtain the medical dialysis paper;a method for preparing the high-toughness sheath-core fibers comprises the following steps:S1, melt-blending cellulose nanofibers with polyethylene at a mass ratio of 1:4 to obtain a sheath component;S2, melt-blending cellulose nanofibers with polypropylene at a mass ratio of 1:4 to obtain a core component;S3, adding the sheath component to melting channel A, adding the core component to melting channel B, performing coaxial melt electrospinning to obtain the high-toughness sheath-core fiber;in the step S1, the cellulose nanofibers are melt-blended with polyethylene in an internal mixer at 130° C. and 50 r / min for 5-10 minutes;in the step S2, the cellulose nanofibers are melt-blended with polypropylene in an internal mixer at 170° C. and 50 r / min for 5-10 minutes;in the step S3, 25 wt % of the sheath component is added to the melting channel A, and 75 wt % of the core component is added to the melting channel B, and coaxial melt electrospinning is performed, wherein, the temperature of the melting channel A is set to 140° C., and the temperature of the melting channel B is set to 180° C., coaxial needles with an inner diameter of 22 G and an outer diameter of 16 G are used as spinning needles;the melt electrospinning process conditions are as follows: voltage: 25-40 kV, spinning distance: 25-30 cm, roller speed: 200-800 r / min, propulsion speed: 0.4-0.8 mL / h.

2. The method for preparing medical dialysis paper according to claim 1, wherein the length of the cellulose nanofibers is 5-20 nm.

3. Medical dialysis paper prepared by the preparation method of claim 1.

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