Radiation-sterilizable polyethylene nonwoven material and method of making same

Abstract

The application provides a radiation-sterilizable polyethylene nonwoven material and a preparation method thereof. The radiation-sterilizable polyethylene nonwoven material is formed by melt-blowing spinning of high melt index polyethylene and polybutadiene epoxide, and the melt index of the high melt index polyethylene is greater than or equal to 200 g / 10 min. The polybutadiene epoxide is used as a plasticizer, which can improve the flowability of the high melt index polyethylene melt, and is beneficial to polyethylene melt-blowing processing. In addition, the polybutadiene epoxide can promote the occurrence of trace chemical cross-linking reaction in the process of micro-fiber heat treatment and radiation sterilization, and improve the structural stability of the micro-fiber.

Description

Technical Field

[0001] This invention relates to the field of nonwoven materials, specifically to a radiation-sterilizable polyethylene nonwoven material and its preparation method. Background Technology

[0002] Currently, most medical protective materials, such as masks and protective suits, utilize meltblown polypropylene nonwoven materials. Whether the polypropylene is prepared using metallocene or high melt index polypropylene prepared via degradation methods, the resulting meltblown nonwoven materials require ethylene oxide sterilization. Therefore, a 7-14 day desorption period is needed after sterilization to remove residual ethylene oxide. Thus, exploring and establishing a method for preparing medical protective materials that can be rapidly sterilized is of paramount importance.

[0003] High-density polyethylene (HDPE) nonwoven fabric exhibits good radiation resistance and high long-term storage stability after radiation sterilization, leading DuPont to select it as the polymer matrix material for the production of limited-end protective clothing. However, polyethylene has a low melt index, high melt viscosity, and is not easily soluble in solvents at room temperature and pressure, thus conventional spinning methods cannot process it into microfiber nonwoven materials. Compared to traditional nonwoven fabric technology, flash evaporation technology for polyethylene nonwoven fabrics, invented by DuPont, has been used for the industrial development of HDPE nonwoven fabrics. Its product, Tyvek, is used in advanced medical protective products and has been selected as a special protective textile for Ebola virus protection in Africa. Flash evaporation technology involves spraying a saturated HDPE solution under high temperature and pressure into the atmosphere to obtain nonwoven fabric. However, flash evaporation presents environmental pollution problems, hindering industrial application. Summary of the Invention

[0004] The main objective of this invention is to provide a radiation-sterilizable polyethylene nonwoven material and its preparation method, so as to overcome the problems of meltblown polypropylene fibers being unable to withstand rapid radiation sterilization and the insufficient mechanical strength of meltblown polyethylene microfibers in the prior art.

[0005] To achieve the above objectives, the present invention provides a radiation-sterilizable polyethylene nonwoven material, which is formed by melt-blown spinning of high melt index polyethylene and polybutadiene epoxide, wherein the melt index of the high melt index polyethylene is greater than or equal to 200 g / 10 min.

[0006] The radiation-sterilizable polyethylene nonwoven material of the present invention comprises a high melt index polyethylene with a melt index of 200-1500 g / 10 min and a polybutadiene epoxide with an epoxy molar content of 5%-8%.

[0007] The radiation-sterilizable polyethylene nonwoven material of the present invention comprises a high melt index polyethylene to polybutadiene epoxide mass ratio of 90-99:10-1; the polybutadiene epoxide has a number average molecular weight of 4000-5000 and a viscosity of 2500-3000.

[0008] The radiation-sterilizable polyethylene nonwoven material of the present invention further includes an antioxidant, namely 4,4'-thiobis(6-tert-butyl-3-methylphenol), and the amount of antioxidant added is 0.1 to 0.3% of the sum of the mass of the high melt index polyethylene and the polybutadiene epoxide.

[0009] To achieve the above objectives, the present invention also provides a method for preparing a radiation-sterilizable polyethylene nonwoven material, comprising the following steps:

[0010] Step 1: Mix and granulate high melt index polyethylene and polybutadiene epoxide;

[0011] Step 2: The resin obtained in Step 1 is melt-blown spun to form an initial polyethylene nonwoven material;

[0012] Step 3: Heat-treat the initial polyethylene nonwoven material to obtain a radiation-sterilizable polyethylene nonwoven material.

[0013] The melt index of the high melt index polyethylene is greater than or equal to 200 g / 10 min.

[0014] The method for preparing radiation-sterilizable polyethylene nonwoven material according to the present invention, wherein the melt index of the high melt index polyethylene is 200-1500 g / 10 min; and the epoxy content of the polybutadiene epoxide is 5%-8%.

[0015] The method for preparing radiation-sterilizable polyethylene nonwoven material according to the present invention, wherein the mass ratio of high melt index polyethylene to polybutadiene epoxide is 90-99:10-1.

[0016] The method for preparing radiation-sterilizable polyethylene nonwoven material according to the present invention includes step 2, which is carried out in a meltblown spinning machine with a screw temperature of 200-240°C, a hot air temperature of 230-260°C, a hot air frequency of 40-50Hz, and a receiving distance of 20-35cm.

[0017] The method for preparing radiation-sterilizable polyethylene nonwoven material according to the present invention includes step 1, in which an antioxidant is added during the mixing and granulation process of high melt index polyethylene and polybutadiene epoxide. The antioxidant is 4,4'-thiobis(6-tert-butyl-3-methylphenol), and the amount of antioxidant added is 0.1-0.3% of the sum of the mass of the high melt index polyethylene and the polybutadiene epoxide.

[0018] The method for preparing radiation-sterilizable polyethylene nonwoven material according to the present invention includes a heat treatment temperature of 90–110°C.

[0019] The beneficial effects of this invention are:

[0020] This invention utilizes polybutadiene epoxide as a plasticizer, which on the one hand improves the fluidity of high melt index polyethylene melt, facilitating polyethylene meltblown processing; on the other hand, it promotes the occurrence of trace chemical crosslinking reactions during the heat treatment and radiation sterilization of microfibers, thereby improving the structural stability of microfibers. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the processing of polyethylene nonwoven material according to one embodiment of the present invention;

[0022] Figure 2 This is a SEM image of the polyethylene nonwoven material from Example 1 of the present invention;

[0023] Figure 3 This is a SEM diameter statistics table of polyethylene nonwoven material in Example 1 of the present invention.

[0024] In the attached figures, the following labels are used:

[0025] 1 Feeding device

[0026] 2. Screw extruder

[0027] 3 Metering pump

[0028] 4. Web forming device

[0029] 5. Meltblown die head

[0030] 6. Heat treatment equipment

[0031] 7. Winding device Detailed Implementation

[0032] The technical solution of the present invention will be described in detail below. The following embodiments are implemented under the premise of the technical solution of the present invention and a detailed implementation process is given. However, the protection scope of the present invention is not limited to the following embodiments. Structures or experimental methods that do not specify specific conditions in the following embodiments are generally performed under conventional conditions.

[0033] This invention provides a radiation-sterilizable polyethylene nonwoven material, which is formed by melt-blown spinning of high melt index polyethylene and polybutadiene epoxide. The melt index of the high melt index polyethylene is greater than or equal to 200 g / 10 min (wherein, the melt index refers to the melt index tested at a load of 2.16 kg and a temperature of 190 °C).

[0034] This invention utilizes polybutadiene epoxide as a plasticizer, which on the one hand improves the fluidity of high melt index polyethylene melt, facilitating polyethylene meltblown processing; on the other hand, it promotes the occurrence of trace chemical crosslinking reactions during the heat treatment and radiation sterilization of microfibers, thereby improving the structural stability of microfibers.

[0035] In one embodiment, the melt index of the high melt index polyethylene is 200–1500 g / 10 min; the epoxy content of the polybutadiene epoxide is 5%–8%. In another embodiment, the molecular weight of the polybutadiene epoxide is approximately 4000–5000, and the viscosity is 2500–3000. In yet another embodiment, the mass ratio of high melt index polyethylene to polybutadiene epoxide is 90–99:10–1.

[0036] In one embodiment, an antioxidant is also added to the radiation-sterilizable polyethylene nonwoven material, such as 4,4'-thiobis(6-tert-butyl-3-methylphenol), and the amount of antioxidant added is 0.1 to 0.3% of the sum of the mass of the high melt index polyethylene and the polybutadiene epoxide.

[0037] In one embodiment, the proportions of each substance in the radiation-sterilizable polyethylene nonwoven material of the present invention are as follows: 90 kg of high melt index polyethylene, 0.91-10 kg of polybutadiene epoxide, and 0.09-0.3 kg of antioxidant.

[0038] This invention also provides a method for preparing a radiation-sterilizable polyethylene nonwoven material, comprising the following steps:

[0039] Step 1: Mix and granulate high melt index polyethylene and polybutadiene epoxide;

[0040] Step 2: The resin obtained in Step 1 is melt-blown spun to form an initial polyethylene nonwoven material;

[0041] Step 3: Heat-treat the initial polyethylene nonwoven material to obtain a radiation-sterilizable polyethylene nonwoven material.

[0042] The melt index of the high melt index polyethylene is greater than or equal to 200 g / 10 min.

[0043] In one embodiment, the melt index of the high melt index polyethylene is 200–1500 g / 10 min (2.16 kg, 190 °C); the epoxy molar content of the polybutadiene epoxide is 5%–8%. In another embodiment, the mass ratio of high melt index polyethylene to polybutadiene epoxide is 90–99:10–1.

[0044] The present invention does not specifically limit the specific method of mixing and granulating high melt index polyethylene and polybutadiene epoxide, such as granulation in a screw extruder, or kneading and granulation in a kneader, with a kneading and granulation temperature of, for example, 100-120°C and a kneading and granulation time of, for example, 10-30 min.

[0045] In one embodiment, an antioxidant is added during the mixing and granulation process of high melt index polyethylene and polybutadiene epoxide. The antioxidant is 4,4'-thiobis(6-tert-butyl-3-methylphenol), and the amount of antioxidant added is 0.1 to 0.3% of the sum of the mass of the high melt index polyethylene and the polybutadiene epoxide.

[0046] Then, the kneaded and granulated resin is meltblown spun into fibers, for example, by a meltblown spinning machine, with a screw temperature of 200-240°C, a hot air temperature of 230-260°C, a hot air frequency of 40-50Hz, and a receiving distance of 20-35cm. The meltblown fibers fall onto a web-forming device to form the initial polyethylene nonwoven material.

[0047] Finally, the initial polyethylene nonwoven material is heat-treated to obtain a radiation-sterilizable polyethylene nonwoven material. In one embodiment, the heat treatment temperature is 90–110°C; in another embodiment, the initial polyethylene nonwoven material is heat-treated during the conveying process after meltblown spinning, at a conveying speed of 50–110 m / min.

[0048] In one embodiment, the processing procedure for the polyethylene nonwoven material of the present invention is as follows: Figure 1 As shown, but the present invention is not limited thereto. High melt index polyethylene and polybutadiene epoxide are fed into screw extruder 2 through feeding device 1. After the composite resin is extruded and granulated, it passes through metering pump 3 and meltblown die 5 and settles on web forming device 4 to obtain initial polyethylene nonwoven material. Then, the initial polyethylene nonwoven material is heat-treated by heat treatment device 6 to obtain polyethylene nonwoven material. The polyethylene nonwoven material is wound up by winding device 7.

[0049] The radiation sterilization method for the radiation-sterilizable polyethylene nonwoven material of this invention can be either electron beam radiation sterilization or X-ray sterilization, with a metering control of 16-27 kGy.

[0050] This invention uses high melt index polyethylene as the polymer matrix. Polyethylene is more flexible than polypropylene, which greatly improves the drape and softness of the material, resulting in nonwoven fabrics with better comfort. Polyethylene fibers have a much higher thermal conductivity than polypropylene, which is beneficial for the heat dissipation of nonwoven fabrics.

[0051] The polyethylene nonwoven material obtained by the method of this invention has a transverse and longitudinal tensile strength greater than 3N, a filtration efficiency ≥95%, and a resistance <200Pa.

[0052] The technical solution of the present invention will be further described in detail below through specific embodiments.

[0053] Source of raw materials or equipment:

[0054] (1) Raw materials:

[0055] High melt index polyethylene was provided by the Daqing Chemical Research Center of China National Petroleum Corporation.

[0056] Polybutadiene epoxide, using 62000 epoxy resin, produced by Guangzhou Kafen Biotechnology Co., Ltd.;

[0057] The antioxidant 4,4'-thiobis(6-tert-butyl-3-methylphenol) is produced by Wuhan Smike Biotechnology Co., Ltd.

[0058] (2) Equipment:

[0059] The kneading and mixing equipment was designed and manufactured by Donghua University.

[0060] Meltblown spinning machines are manufactured by Tuoren Group;

[0061] The X-ray irradiation equipment was manufactured by Bruker GmbH in Germany.

[0062] Example 1

[0063] 1) Preparation of high melt index polyethylene, polybutadiene epoxide, and antioxidant 4,4'-thiobis(6-tert-butyl-3-methylphenol) composite resin:

[0064] Using a kneading and mixing equipment, 90 kg of polyethylene powder with a melt index of 300, 1 kg of polybutadiene epoxide (epoxy molar content of 5%) and 0.095 kg of 4,4'-thiobis(6-tert-butyl-3-methylphenol) were stirred and added to the kneader at a temperature of 110℃ and kneaded rapidly for 15 minutes. No agglomeration of the powder was observed. The powder was then kneaded into granular resin through an injection molding assembly.

[0065] 2) Meltblown microfiber nonwoven materials:

[0066] Polyethylene microfibers were prepared by meltblowing the above-mentioned resin using a meltblown spinning machine from Tuoren Group. During the preparation process, the screw compression and homogenization sections were set to temperatures of 120–240°C, the meltblown assembly temperature was 240°C, the hot air temperature was 260°C, the hot air frequency was 45Hz, and the receiving distance was 35cm, resulting in meltblown polyethylene microfiber nonwoven material.

[0067] Figure 2 This is a SEM image of the polyethylene nonwoven material from Embodiment 1 of the present invention, obtained through dimensional measurements. Figure 3 Example 1 of this invention: SEM diameter statistics table of polyethylene nonwoven material. (From...) Figure 2 and Figure 3 As shown, the diameter of polyethylene microfibers is mainly 2-5 μm, with a small amount of 6-8 μm. This fiber diameter distribution helps to form a spatial structure that is conducive to mechanical reinforcement.

[0068] The transverse and longitudinal tensile strengths of the microfiber nonwoven material reach 4±0.23N and 3.5±0.14N, respectively. The filtration efficiency of the mask filter material prepared by using it in disposable mask equipment is ≥95%, and the resistance is <200Pa.

[0069] 3) Post-treatment and sterilization of nonwoven materials:

[0070] The nonwoven material obtained from meltblown processing is conveyed to a heat treatment unit at a speed of 50 m / min and the temperature is set at 100℃ to obtain a shaped meltblown nonwoven material. After being irradiated with 27 kGy X-rays, the nonwoven material is tested and found to be free of E. coli colonies, bacterial colonies, and fungal colonies.

[0071] Example 2

[0072] 1) Preparation of high melt index polyethylene, polybutadiene epoxide, and antioxidant 4,4'-thiobis(6-tert-butyl-3-methylphenol) composite resin:

[0073] Using a kneading and mixing equipment, 90 kg of high melt index polyethylene (700 g / 10 min) powder, 10 kg of polybutadiene epoxide (epoxy molar content 8%) and 0.2 kg of 4,4'-thiobis(6-tert-butyl-3-methylphenol) were stirred and added to the kneader at a temperature of 110°C and kneaded rapidly for 15 min. No agglomeration of the powder was observed. The powder was then kneaded into granular resin through an injection molding assembly.

[0074] 2) Meltblown microfiber nonwoven materials:

[0075] Polyethylene microfibers were prepared by meltblowing the above-mentioned resin using a meltblown spinning machine from Tuoren Group. The screw compression and homogenization sections were set to temperatures of 120–240°C, the meltblown assembly temperature to 220°C, the hot air temperature to 250°C, the hot air frequency to 50Hz, and the receiving distance to 20cm, resulting in meltblown polyethylene microfiber nonwoven material. The transverse and longitudinal tensile strengths of the microfiber nonwoven material reached 3.5±0.21N and 3.2±0.22N, respectively. The filter material prepared from it achieved a filtration efficiency ≥95% and a resistance <200Pa.

[0076] 3) Post-treatment and sterilization of nonwoven materials:

[0077] The nonwoven material obtained from meltblown processing is conveyed to a heat treatment unit at a speed of 110 m / min and the temperature is set at 90℃ to obtain a shaped meltblown nonwoven material. After being irradiated with a 16 kGy electron beam, the nonwoven material is tested and found to be free of E. coli colonies, bacterial colonies, and fungal colonies.

[0078] Example 3

[0079] 1) Preparation of high melt index polyethylene, polybutadiene epoxide, and antioxidant 4,4'-thiobis(6-tert-butyl-3-methylphenol) composite resin:

[0080] Using a kneading and mixing equipment, 95 kg of high melt index polyethylene (200 g / 10 min) powder, 5 kg of polybutadiene epoxide (epoxy value 6%) and 0.3 kg of 4,4'-thiobis(6-tert-butyl-3-methylphenol) were stirred and added to the kneader at 110°C and kneaded rapidly for 15 min. No agglomeration of the powder was observed. The powder was then kneaded into granular resin through an injection molding assembly.

[0081] 2) Meltblown microfiber nonwoven materials:

[0082] Polyethylene microfibers were prepared by meltblowing the above-mentioned resin using a meltblown spinning machine from Tuoren Group. The screw compression and homogenization sections were set to temperatures of 120–240°C, the meltblown assembly temperature to 240°C, the hot air temperature to 260°C, the hot air frequency to 45Hz, and the receiving distance to 25cm, resulting in meltblown polyethylene microfiber nonwoven material. The transverse and longitudinal tensile strengths of the microfiber nonwoven material reached 5.3±0.27N and 4.5±0.24N, respectively. The filter material prepared from it achieved a filtration efficiency ≥95% and a resistance <200Pa.

[0083] 3) Post-treatment and sterilization of nonwoven materials:

[0084] The nonwoven material obtained from meltblown processing is conveyed to a heat treatment unit at a speed of 75 m / min and the temperature is set at 100℃ to obtain a shaped meltblown nonwoven material. After being irradiated with 25 kGy X-rays, the nonwoven material is tested and found to be free of E. coli colonies, bacterial colonies, and fungal colonies.

[0085] Example 4

[0086] 1) Preparation of high melt index polyethylene, polybutadiene epoxide, and antioxidant 4,4'-thiobis(6-tert-butyl-3-methylphenol) composite resin:

[0087] Using a kneading and mixing equipment, 95 kg of high melt index (1500 g / 10 min) polyethylene powder, 5 kg of polybutadiene epoxide (epoxy value 6%), and 0.1 kg of 4,4'-thiobis(6-tert-butyl-3-methylphenol) were stirred and added to the kneader at 110°C and kneaded rapidly for 15 min. No agglomeration of the powder was observed. The powder was then kneaded into granular resin through an injection molding assembly.

[0088] 2) Meltblown microfiber nonwoven materials:

[0089] Polyethylene microfibers were prepared by meltblowing the above-mentioned resin using a meltblown spinning machine from Tuoren Group. The screw compression and homogenization sections were set to temperatures of 120–240°C, the meltblown assembly temperature to 200°C, the hot air temperature to 230°C, the hot air frequency to 40Hz, and the receiving distance to 20cm, resulting in meltblown polyethylene microfiber nonwoven material. The transverse and longitudinal tensile strengths of the microfiber nonwoven material reached 5.3±0.15N and 4.5±0.21N, respectively. The filter material prepared from it achieved a filtration efficiency ≥95% and a resistance <200Pa.

[0090] 3) Post-treatment and sterilization of nonwoven materials:

[0091] The nonwoven material obtained from meltblown processing is conveyed to a heat treatment unit at a speed of 60 m / min and the temperature is set at 110℃ to obtain a shaped meltblown nonwoven material. After being irradiated with 25 kGy X-rays, the nonwoven material is tested and found to be free of E. coli colonies, bacterial colonies, and fungal colonies.

[0092] 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 radiation-sterilizable polyethylene nonwoven material, characterized in that, It is formed by melt-blown spinning of high melt index polyethylene, polybutadiene epoxide and antioxidant, wherein the melt index of the high melt index polyethylene is greater than or equal to 200 g / 10min and the antioxidant is 4,4'-thiobis(6-tert-butyl-3-methylphenol).

2. The radiation-sterilizable polyethylene nonwoven material according to claim 1, characterized in that, The high melt index polyethylene has a melt index of 200~1500 g / 10min; the epoxy molar content of the polybutadiene epoxide is 5%~8%.

3. The radiation-sterilizable polyethylene nonwoven material according to claim 1, characterized in that, The mass ratio of the high melt index polyethylene to the polybutadiene epoxide is 90~99:10~1; the number average molecular weight of the polybutadiene epoxide is 4000~5000, and the viscosity is 2500~3000.

4. The radiation-sterilizable polyethylene nonwoven material according to claim 1, characterized in that, The amount of antioxidant added is 0.1 to 0.3% of the sum of the mass of the high melt index polyethylene and the polybutadiene epoxide.

5. A method for preparing a radiation-sterilizable polyethylene nonwoven material, characterized in that, Includes the following steps: Step 1: Mix and granulate high melt index polyethylene, polybutadiene epoxide and antioxidant; Step 2: The resin obtained in Step 1 is melt-blown spun to form an initial polyethylene nonwoven material; Step 3: Heat-treat the initial polyethylene nonwoven material to obtain a radiation-sterilizable polyethylene nonwoven material. Wherein, the melt index of the high melt index polyethylene is greater than or equal to 200 g / 10min, and the antioxidant is 4,4'-thiobis(6-tert-butyl-3-methylphenol).

6. The method for preparing the radiation-sterilizable polyethylene nonwoven material according to claim 5, characterized in that, The high melt index polyethylene has a melt index of 200~1500 g / 10min; the epoxy content of the polybutadiene epoxide is 5%~8%.

7. The method for preparing the radiation-sterilizable polyethylene nonwoven material according to claim 5, characterized in that, The mass ratio of the high melt index polyethylene to the polybutadiene epoxide is 90~99:10~1.

8. The method for preparing the radiation-sterilizable polyethylene nonwoven material according to claim 5, characterized in that, Step 2 is performed in a meltblown spinning machine with a screw temperature of 200~240°C. o C, Hot air temperature is 230~260 o C, hot air frequency is 40-50Hz, receiving distance is 20~35 cm.

9. The method for preparing the radiation-sterilizable polyethylene nonwoven material according to claim 5, characterized in that, The amount of antioxidant added is 0.1 to 0.3% of the sum of the mass of the high melt index polyethylene and the polybutadiene epoxide.

10. The method for preparing the radiation-sterilizable polyethylene nonwoven material according to claim 5, characterized in that, The heat treatment temperature is 90~110℃ o C.

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