High-tenacity sheath-core fiber, medical dialysis paper and preparation method thereof

Abstract

The invention provides a high-tenacity sheath-core fiber, a medical dialysis paper and a preparation method thereof. A certain proportion of cellulose nanofibers are added to sheath polyethylene and core polypropylene respectively for melt blending to obtain a sheath component and a core component, and then melt electrospinning is performed to obtain the high-tenacity sheath-core fiber. The high-tenacity sheath-core fiber is mixed into the raw material of the medical dialysis paper in an addition amount of 2-20% by mass. After wet papermaking, the sheath of the fiber is melted by hot pressing bonding, so that the materials between the sheaths are melted and mixed, thereby improving the strength of the finished paper. The prepared medical dialysis paper has excellent antibacterial performance.

Description

Technical Field

[0001] The invention relates to the technical field of composite fiber materials, and in particular to a high-tenacity sheath-core fiber, medical dialysis paper and a preparation method thereof. Background Art

[0002] The surface active groups of the sheath-core fiber with polyethylene (PE)-polypropylene (PP) as the main components are relatively few. When it is used as a raw material to prepare medical dialysis paper, the structure is relatively loose and the physical strength is poor. It needs to be hot-pressed to increase the tightness to form a dense bond and give it higher physical strength. However, due to the large difference in the thermal shrinkage of the sheath and core layers, some areas between the sheath PE and the core PP inside a single fiber present a "gap-type" interface, which increases the porosity of the paper and affects the antibacterial properties. Summary of the invention

[0003] The purpose of the present invention is to overcome the defects of the prior art and provide a high-tenacity sheath-core fiber, medical dialysis paper and a preparation method thereof.

[0004] The present invention provides the following technical solutions:

[0005] The invention provides a high-tenacity sheath-core fiber, comprising a sheath layer and a core layer, wherein the sheath layer accounts for 20-30% of the weight of the sheath-core fiber, and the core layer accounts for 70-80% of the weight of the sheath-core fiber. The sheath layer is composed of 80-95% by weight of polyethylene and 5-20% by weight of cellulose nanofibers, and the core layer is composed of 80-95% by weight of polypropylene and 5-20% by weight of cellulose nanofibers.

[0006] The present invention also provides a method for preparing the high-tenacity sheath-core fiber, comprising the following steps:

[0007] S1, melt-blending cellulose nanofibers and polyethylene at a mass ratio of (5-20): (80-95) to obtain a skin component;

[0008] S2, melt-blending cellulose nanofibers and polypropylene at a mass ratio of (5-20): (80-95) to obtain a core layer component;

[0009] S3, adding the skin layer component into the A melting channel, adding the core layer component into the B melting channel, and performing coaxial melt electrospinning to obtain the high-tenacity skin-core fiber.

[0010] PE-PP sheath-core fiber is composed of inert fibers, the sheath and core in a single fiber are not connected, and the difference in heat shrinkage is large, and the physical properties are poor. After adding cellulose nanofibers to the sheath layer and the core layer, the cellulose in the sheath layer and the core layer will be connected by hydrogen bonds between the hydroxyl groups, and the connection will be tighter, thereby improving its toughness. Adding 5-20% cellulose nanofibers in the present invention will not affect the melting of the sheath layer and the supporting performance of the core layer. After adding 20% ​​cellulose nanofibers, the elongation at break of the sheath-core fiber is doubled, and it has high toughness.

[0011] Furthermore, the length of the cellulose nanofibers is 5-20 nm.

[0012] Furthermore, in step S1, the cellulose nanofibers and polyethylene are melt-blended in an internal mixer at 130° C. and a rotation speed of 50 r / min for 5-10 min.

[0013] Furthermore, in step S2, the cellulose nanofibers and the polypropylene are melt-blended in an internal mixer at 170° C. and a rotation speed of 50 r / min for 5-10 min.

[0014] Furthermore, the temperature of the melting channel A is 140° C., the temperature of the melting channel B is 180° C., and the spinning needle adopts a coaxial needle with an inner diameter of 22G and an outer diameter of 16G.

[0015] Furthermore, the melt electrospinning process conditions are: voltage: 25-40 kV, spinning distance: 25-30 cm, drum speed: 200-800 r / min, and propulsion speed of 0.4-0.8 mL / h.

[0016] Based on the same inventive concept, the present invention also provides a method for preparing medical dialysis paper, wherein the high-tenacity sheath-core fiber prepared above is added to a plant fiber raw material at 2 to 20% of the total mass, and after fiber dispersion, oblique mesh forming, pressing and drying, hot pressing and cold air treatment are performed at 135-140°C to obtain the medical dialysis paper.

[0017] When the sheath-core fiber without adding cellulose nanofibers is subjected to hot pressing to prepare paper, the sheath melts. Since the components of the sheath and core are both inert fibers, the sheath and core in a single fiber are not connected, and the difference in heat shrinkage is large, resulting in a gap between the sheath and core of a single fiber, thereby increasing the porosity of the finished paper and affecting the antibacterial performance of the paper. The present invention adds cellulose nanofibers to the sheath-core fiber. When the paper is hot-pressed, the cellulose in the sheath and core layers is connected by hydrogen bonds between hydroxyl groups, and the connection is tighter, avoiding the generation of gaps, optimizing the pore structure of the paper, and improving the antibacterial performance of the paper.

[0018] The present invention has the following beneficial effects:

[0019] 1. The present invention mixes cellulose nanofibers (CNF) into hot-melt PE and PP, so that during the hot pressing process of the core-skin fibers, the skin PE fibers between the fibers are well melted, and the fiber skins are connected by hydrogen bonds with the CNF between the fiber skins, thereby improving the bonding strength.

[0020] 2. During hot pressing treatment, hydrogen bonds are formed at the interface between the cortex PE and the core PP inside a single fiber, which reduces the interfacial gap between the skin and the core, improves the paper strength, improves the porosity of the paper, and thus improves its antibacterial properties. The interface between the cortex PE and the core PP forms a mutually intersecting transition zone interface, and the stress inside the fiber is evenly transmitted, which can prevent crack propagation and alleviate stress concentration. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 This is a scanning electron microscope image of the sheath-core fiber prepared in Example 1 of the present invention;

[0023] Figure 2 This is a microscopic morphology of the medical dialysis paper prepared in Example 5 of the present invention. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] An embodiment of the present invention provides a high-tenacity sheath-core fiber, including a sheath layer and a core layer, the sheath layer accounts for 20-30% of the mass of the sheath-core fiber, 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 by mass, and the core layer is composed of 80-95% polypropylene and 5-20% cellulose nanofibers by mass.

[0026] Based on the same inventive concept, an embodiment of the present invention provides a method for preparing the high-tenacity sheath-core fiber, comprising the following steps:

[0027] S1, melt-blending cellulose nanofibers and polyethylene at a mass ratio of (5-20): (80-95) to obtain a skin component;

[0028] S2, melt-blending cellulose nanofibers and polypropylene at a mass ratio of (5-20): (80-95) to obtain a core layer component;

[0029] S3, adding the skin layer component into the A melting channel, and adding the core layer component into the B melting channel, and performing coaxial melt electrospinning to obtain high-tenacity skin-core fibers.

[0030] The mass ratio of the skin layer component to the core layer component is (20-30): (70-80), and the total mass of the two components is 100wt%. Preferably, the doping percentage of the cellulose nanofibers in the skin layer component and the core layer component is the same.

[0031] In a specific embodiment, the length of the cellulose nanofibers is 5-20 nm.

[0032] In a specific embodiment, in step S1, the cellulose nanofibers and polyethylene are melt-blended in an internal mixer at 130° C. and a rotation speed of 50 r / min for 5-10 min.

[0033] In a specific embodiment, in step S2, the cellulose nanofibers and the polypropylene are melt-blended in an internal mixer at 170° C. and a rotation speed of 50 r / min for 5-10 min.

[0034] In a specific embodiment, the temperature of melting channel A is 140° C., the temperature of melting channel B is 180° C., and the spinning needle is a coaxial needle with an inner diameter of 22G and an outer diameter of 16G.

[0035] In a specific embodiment, the melt electrospinning process conditions are: voltage: 25-40 kV, spinning distance: 25-30 cm, drum speed: 200-800 r / min, and propulsion speed of 0.4-0.8 mL / h.

[0036] Based on the same inventive concept, an embodiment of the present invention also provides an application of the high-tenacity sheath-core fiber, namely, a method for preparing medical dialysis paper, wherein the high-tenacity sheath-core fiber prepared above is added to a plant fiber raw material at 5 to 20% of the total mass, and after fiber dispersion, oblique mesh forming, pressing, and drying, hot pressing and cold air treatment are performed at 135-140°C to obtain medical dialysis paper.

[0037] The present invention will be further described below by means of specific embodiments:

[0038] The materials used in the following examples were all purchased from the market. Cellulose nanofibers were purchased from Shanghai MacLean Biochemical Technology Co., Ltd., and polyethylene and polypropylene were purchased from Zhejiang Sunrise Basic Chemical Co., Ltd.

[0039] Example 1

[0040] This embodiment prepares a high-tenacity sheath-core fiber, and the specific process is as follows:

[0041] 1. Melt and blend cellulose nanofibers (CNF) and polyethylene at a mass ratio of 1:4 in a Haake internal mixer at 130°C and a speed of 50 r / min for 5-10 min to obtain a skin component;

[0042] 2. Melt and blend cellulose nanofibers (CNF) and polypropylene at a mass ratio of 1:4 in a Haake internal mixer at 170°C and a speed of 50 r / min for 5-10 min to obtain a core layer component;

[0043] 3. Add 25wt% of the skin component to the A melt channel, and add 75wt% of the core layer component to the B melt channel for coaxial melt electrospinning, wherein the temperature of the A melt channel is set to 140°C, the temperature of the B melt channel is set to 180°C, and the spinning needle adopts a coaxial needle (inner diameter 22G, outer diameter 16G). The melt electrospinning process conditions are: voltage: 25-40kV, spinning distance: 25-30cm, drum speed: 200-800r / min, and propulsion speed is 0.4-0.8mL / h.

[0044] Example 2

[0045] The content of cellulose nanofibers in the skin layer component and the core layer component is 15%, and the other steps are the same as in Example 1.

[0046] Example 3

[0047] The content of cellulose nanofibers in the skin layer component and the core layer component is 10%, and the other steps are the same as in Example 1.

[0048] Example 4

[0049] The content of cellulose nanofibers in the skin layer component and the core layer component is 5%, and the other steps are the same as in Example 1.

[0050] Comparative Example 1

[0051] 25wt% polyethylene as the skin component was added to the A melting channel, and 75wt% polypropylene as the core component was added to the B melting channel for coaxial melt electrospinning to prepare PE-PP skin-core fiber. The temperature of the A melting channel was set to 140°C, the temperature of the B melting channel was set to 180°C, the spinning needle used a coaxial needle (inner diameter 22G, outer diameter 16G), and the melt electrospinning process conditions were: voltage: 25-40kV, spinning distance: 25-30cm, drum speed: 200-800r / min, and propulsion speed of 0.4-0.8mL / h.

[0052] Comparative Example 2

[0053] The content of cellulose nanofibers in the skin layer component and the core layer component is 2%, and the other steps are the same as in Example 1.

[0054] Example 5

[0055] This embodiment prepares a medical dialysis paper, and the specific process is as follows:

[0056] The high-tenacity core-skin fiber prepared in Example 1 is added to plant fiber raw materials (coniferous wood pulp, hardwood pulp, etc.) at 5% of the total mass, and after wet papermaking (fiber dispersion, oblique mesh forming, pressing, drying), hot pressing and cold air treatment are performed at 135-140°C to obtain medical dialysis paper.

[0057] Example 6

[0058] The high-tenacity core-skin fiber prepared in Example 1 was added to the papermaking fiber raw material at 10% of the total mass, and after wet papermaking, it was hot pressed and cold-air treated at 135-140° C. to obtain medical dialysis paper.

[0059] Example 7

[0060] The high-tenacity core-sheath fiber prepared in Example 1 was added to the papermaking fiber raw material at 15% of the total mass, and after wet papermaking, it was hot-pressed and cold-air treated at 135-140° C. to obtain medical dialysis paper.

[0061] Example 8

[0062] The high-tenacity core-skin fiber prepared in Example 1 was added to the papermaking fiber raw material at 20% of the total mass, and after wet papermaking, it was hot pressed and cold-air treated at 135-140° C. to obtain medical dialysis paper.

[0063] Example 9

[0064] The high-tenacity core-sheath fiber prepared in Example 1 was added to the papermaking fiber raw material at 2% of the total mass, and after wet papermaking, it was hot pressed and cold-air treated at 135-140° C. to obtain medical dialysis paper.

[0065] Test Case

[0066] 1) The elongation at break of the sheath-core fibers prepared in Examples 1 to 4 and Comparative Examples 1 to 2 was tested. The test method was based on GB / T 19975-2005 "Test Method for Tensile Properties of High-Reinforced Filaments". The results are shown in Table 1:

[0067] Table 1 Elongation at break data of the sheath-core fibers obtained in each example

[0068] CNF addition amount, % Elongation at break, % Comparative Example 1 0 2.8％ Comparative Example 2 2 3.1％ Example 1 5 3.5％ Example 2 10 4.2％ Example 3 15 5.3％ Example 4 20 5.6％

[0069] In the present invention, adding 5-20% cellulose nanofibers will not affect the melting performance of the skin layer and the supporting performance of the core layer. Figure 1 The sheath layer and the core layer of the sheath-core fiber prepared in Example 1 are tightly connected. After adding 20% ​​cellulose nanofibers, the elongation at break of the sheath-core fiber is doubled, and the fiber has high toughness.

[0070] 2) Performance analysis and testing of medical dialysis paper prepared without adding sheath-core fiber in Examples 5 to 9:

[0071] Air permeability: The air permeability of paper was measured using an air permeability tester (Beijing Libao Technology Co., Ltd., model TEXTEST FX3300-IV), with a test area of ​​20 cm 2 , test pressure 200Pa;

[0072] Bacteria blocking rate: Refer to standard DIN 58953-6-2010 and use agar contact attack method for detection.

[0073] Burst index: According to GB / T 454-2002, the burst index of paper was measured using a computer paper burst tester (Hangzhou Pinxiang Co., Ltd., model PN-BSM160);

[0074] Average pore size: The paper samples were cut into pieces of about 3 cm*3 cm, and then soaked in ethanol for 10 min. The pore size was measured using a porous material pore size analyzer (PSDA-20, Nanjing Gaoqian Functional Materials Technology Co., Ltd.);

[0075] Tensile and wet tensile index: According to GB / T 12914-2018 and GB / T 465.2-2008, the dry and wet tensile strength of paper was measured using a horizontal computer tensile tester (Hangzhou Qingtong Bo Ke Automation Technology Co., Ltd., model WZL-300B).

[0076] The test results are shown in Table 2:

[0077] Table 2 Performance data of medical dialysis paper prepared in each example

[0078]

[0079] The interfacial bonding between fibers directly affects the strength properties of medical dialysis materials, especially the impact resistance, transverse tensile strength, fracture toughness and other properties. The interfacial bonding mainly depends on the fiber surface condition and the degree of fiber softening and melting when heated. See Table 2 and Figure 2 It can be seen that there are abundant connections between single fibers, and the strength performance of paper is greatly improved.

[0080] The present invention mixes cellulose nanofibers (CNF) into hot-melt PE and PP, so that during the hot-pressing bonding process of the core-skin fibers, the skin PE fibers between the fibers are well melted, and the fiber skins and the CNF between the fiber skins are hydrogen-bonded, thereby improving the bonding strength. At the same time, during hot-pressing bonding, the interface between the skin PE and the core PP inside a single fiber is also hydrogen-bonded, reducing the interface gap between the skin and the core, improving the porosity of the finished paper, thereby improving its antibacterial performance, and also improving the strength of the finished paper. The interface between the skin PE and the core PP forms a mutually intersecting transition zone interface, and the stress transmission inside the fiber is uniform, which can prevent crack propagation and relieve stress concentration.

[0081] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing medical dialysis paper, characterized in that: The high-tenacity core-skin fiber is added to the plant fiber raw material at a total weight of 15-20%, and after fiber dispersion, inclined net forming, pressing, and drying, hot pressing and cold air treatment are performed at 135-140° C. to obtain the medical dialysis paper; The method for preparing the high-tenacity sheath-core fiber comprises the following steps: S1, melt-blending cellulose nanofibers and polyethylene at a mass ratio of 1:4 to obtain a cortex component; S2, melt-blending the cellulose nanofibers and polypropylene at a mass ratio of 1:4 to obtain a core layer component; S3, adding the skin layer component into the A melting channel, adding the core layer component into the B melting channel, and performing coaxial melt electrospinning to obtain the high-tenacity skin-core fiber; In step S1, cellulose nanofibers and polyethylene are melt-blended in an internal mixer at 130° C. and a rotation speed of 50 r / min for 5-10 min; In step S2, the cellulose nanofibers and the polypropylene are melt-blended in an internal mixer at 170° C. and a rotation speed of 50 r / min for 5-10 min; In step S3, 25 wt% of the skin layer component is added to the A melting channel, and 75 wt% of the core layer component is added to the B melting channel for coaxial melt electrospinning, wherein the temperature of the A melting channel is set to 140°C, the temperature of the B melting channel is set to 180°C, and the spinning needle adopts a coaxial needle with an inner diameter of 22G and an outer diameter of 16G; The melt electrospinning process conditions are: voltage: 25-40 kV, spinning distance: 25-30 cm, drum speed: 200-800 r / min, and propulsion speed of 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 according to any one of claims 1 to 2.

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