Preparation method of low melt index polylactic acid nanofiber melt-blown cloth

Abstract

The application discloses a kind of preparation methods of low melt index polylactic acid nanofiber melt-blown cloth, belong to material technical field.The method uses as follows using polymeric rosin as modifier, increase melt flowability, with polylactic acid mixed preparation melt-blown cloth, induce polylactic acid nanofiber, after petroleum ether is extracted agent and removes polymeric rosin, preparation obtains lactic acid nanofiber melt-blown cloth.Compared with prior art, the process does not need to be chemically modified, process flow is simple, does not need special equipment;Preparation process is efficient and clean, energy consumption is low, green environmental protection, greatly saves production cost, has certain popularization property;Developed low melt index polylactic acid new application;Prepared melt-blown cloth has wide application prospect in fluid drag reduction, oil-water separation, daily use textile and other fields.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method of low-melt-index polylactic acid nanofiber melt-blown cloth, and belongs to the technical field of materials. BACKGROUND

[0002] Generally, it takes at least 200 years for petrochemical plastics to completely degrade. More dangerously, microplastics generated by incomplete degradation of plastics can accumulate in air, soil and seawater, causing serious environmental pollution worldwide. In order to cope with this crisis, renewable and biodegradable polylactic acid (PLA) has attracted great attention.

[0003] Limited to the fact that high-melt-index PLA raw materials have not been industrialized, the current research on melt-blown PLA non-woven materials is mostly in the laboratory stage. Due to the particularity of the melt-blown process itself, polylactic acid used for melt-blown non-woven materials must have a certain melt index (>=20-30 g / 10 min). Conventional melt-spun polylactic acid cannot be applied to the melt-blown process, which also reflects the high requirements of the melt-blown process on polylactic acid raw materials. Raw materials with lower melt index will increase the melt strength, so more extruder pressure is needed to successfully extrude the melt into the spinneret hole, which further increases the energy consumption. At the same time, the melt extruded under this condition cannot be effectively stretched, resulting in fiber thickening. Using low-viscosity raw material polymer with high melt index helps to make melt stretching easier, thereby reducing air speed and air volume, extending the life of the die, increasing production, reducing energy consumption, and improving the quality of the melt-blown cloth.

[0004] The fiber diameter distribution of melt-blown cloth is generally before 1 mu m-7 mu m, and the fiber diameter of good-quality polypropylene melt-blown cloth can reach before 0.5 mu m-5 mu m, but it is very difficult to achieve this for polylactic acid melt-blown cloth. Therefore, a method for preparing melt-blown cloth using low-melt-index polylactic acid as raw material needs to be researched. SUMMARY

[0005] TECHNICAL PROBLEM

[0006] Using polylactic acid as the raw material for preparing melt-blown cloth can have problems such as too low melt index and too thick cloth fiber, so a new preparation method of polylactic acid melt-blown cloth needs to be provided to solve the problems of too thick cloth fiber and too low melt index of polylactic acid melt-blown cloth.

[0007] TECHNICAL SCHEME

[0008] In order to achieve the above-mentioned purpose, the technical scheme of the present application is: low-melting-point raw material polylactic acid and polymerized rosin particles are dried in a vacuum oven. After manual preliminary mixing, the polylactic acid / polymerized rosin mixed particles are prepared by feeding into a double-screw granulator. The mixed particles are fed into a melt-blowing machine to prepare polylactic acid / polymerized rosin melt-blown cloth. The prepared melt-blown cloth is washed with a solvent (petroleum ether) by a Soxhlet extractor to remove the polymerized rosin, and polylactic acid nanofiber melt-blown cloth is obtained.

[0009] In the technical scheme, the introduction of polymerized rosin improves the melt index of the system, and the function of inducing fiber formation of low-melting-point polylactic acid by polymerized rosin is utilized. The process parameters of the melt-blowing machine are reasonably set, a large number of polylactic acid nanofiber fiber bundles are formed in the melt-blowing process, and the polylactic acid nanofiber fiber bundles are uniformly distributed with the polymerized rosin. After washing away the polymerized rosin, pure polylactic acid nanofiber melt-blown cloth is obtained. The solvent used in the scheme is petroleum ether, which can be reused after dissolving the polymerized rosin, and the polymerized rosin can be filtered and recycled for spinning. The polylactic acid melt-blown cloth after removing the polymerized rosin contains a large number of nanoscale fibers, which can increase the specific surface area. Combined with the characteristics of polylactic acid, the prepared melt-blown cloth can be applied to oil-water separation and other aspects. Therefore, the technical scheme has the advantages of convenient and fast preparation operation, environmentally friendly materials, and strong economic benefits.

[0010] The first object of the present application is to provide a preparation method of polylactic acid nanofiber melt-blown cloth, comprising the following steps:

[0011] (1) polylactic acid and polymerized rosin are weighed and dried, and then mixed and granulated in a granulator to prepare polylactic acid / polymerized rosin mixed particles;

[0012] (2) the polylactic acid / polymerized rosin mixed particles prepared in step (1) are fed into a melt-blowing machine to prepare polylactic acid / polymerized rosin melt-blown cloth;

[0013] (3) the polylactic acid / polymerized rosin melt-blown cloth prepared in step (2) is washed with petroleum ether as a solvent by a Soxhlet extractor to remove the polymerized rosin, and polylactic acid nanofiber melt-blown cloth is obtained.

[0014] Further, the polymerized rosin in step (1) includes rosin dimers and part of rosin derivatives.

[0015] Preferably, the polymerized rosin in step (1) is a mixture of rosin dimers and rosin.

[0016] Further, the mass ratio of polylactic acid to rosin in step (1) is 10-7:0-3.

[0017] Preferably, the mass ratio of polylactic acid to rosin in step (1) is 7:3.

[0018] Further, the operation parameters of the granulator mixing granulation are: the temperature of each section is 175-180 DEG C in the first section, 180-185 DEG C in the second section, 180-185 DEG C in the third section, 175-180 DEG C in the fourth section, 170-175 DEG C in the fifth section, and 165-170 DEG C in the sixth section, and the rotating speed is 65-75 r / min.

[0019] Further, the parameters of the melt blowing machine in step (2) are set as follows: the temperature of the third section is 210-220 DEG C, the temperature of the second section is 210-225 DEG C, the temperature of the first section is 210-230 DEG C, the temperature of the conversion box is 220-240 DEG C, the temperature of the head is 220-245 DEG C, the temperature of the hot air is 250-270 DEG C, the rotating speed of the metering pump is 500-600 r / min, and the rotating speed of the screw is 500-600 r / min.

[0020] Further, the solvent in step (3) is petroleum ether.

[0021] Further, the operation temperature in step (3) is 100-110 DEG C, and the extraction time is 1.5-3 h.

[0022] The second object of the present application is to provide a polylactic acid nanofiber melt-blown cloth prepared by the above method.

[0023] The third object of the present application is to provide the application of the prepared polylactic acid nanofiber melt-blown cloth in the fields of medical health and oil-water separation.

[0024] Beneficial effects

[0025] 1. The polylactic acid nanofiber melt-blown cloth with low melt index can be obtained by melting and mixing the raw material polylactic acid and the polymerized rosin in the granulator, then washing with the organic solvent after melt blowing. The method of the present application simplifies the preparation process compared with the prior art, does not perform any chemical modification, and the polymerized rosin and the organic solvent can be recycled and utilized, which is efficient, clean, low in energy consumption, greatly saves the production cost, and has certain popularization.

[0026] 2. The main material used in the present application is the renewable and degradable synthetic polymer polylactic acid, which has sufficient raw material source and good biodegradability, and can be completely degraded into water and carbon dioxide. The modified component polymerized rosin is natural, has good compatibility, durability and oxidation resistance, and the use of the two natural materials will not pollute the environment.

[0027] 3. The polylactic acid nanofiber melt-blown cloth with low melt index prepared by the present application has great application potential in oil-water separation, seawater filtration and composite materials. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The melt index of the mixed particles prepared in Examples 1, 2, 3 and 4 of the present application.

[0029] Figure 2 SEM photos and diameter distribution of low melt index polylactic acid nanofiber melt-blown fabric prepared in the present application embodiment 1, 2, 3, 4, figure a is the ratio of polylactic acid / polymerized rosin is 10:0; Figure b is the ratio of polylactic acid / polymerized rosin is 9:1; Figure c is the ratio of polylactic acid / polymerized rosin is 8:2; Figure d is the ratio of polylactic acid / polymerized rosin is 7:3.

[0030] Figure 3 SEM photos of low melt index polylactic acid nanofiber melt-blown fabric prepared in the present application embodiment 4, figure a is the sem photo of melt-blown fabric; Figure b is the single nanofiber of melt-blown fabric; Figure c is the fiber fibrillation photo of melt-blown fabric; Figure d is the nanofiber photo of melt-blown fabric.

[0031] Figure 4 The actual picture of low melt index polylactic acid nanofiber melt-blown fabric prepared in the present application embodiment 4 is not washed.

[0032] Figure 5 The actual picture of low melt index polylactic acid nanofiber melt-blown fabric prepared in the present application embodiment 4 is washed.

[0033] Figure 6 Contact angle test of low melt index polylactic acid nanofiber melt-blown fabric prepared in the present application embodiment 1, 2, 3, 4.

[0034] Figure 7 Oil absorption performance test of low melt index polylactic acid nanofiber melt-blown fabric prepared in the present application embodiment 1, 2, 3, 4.

[0035] Figure 8 Oil / water separation test of low melt index polylactic acid nanofiber melt-blown fabric prepared in the present application embodiment 4, water is dyed blue and oily substance is dyed red, figure a is silicone oil / water separation adsorption test, figure b is n-hexane / water adsorption test. DETAILED DESCRIPTION

[0036] The preferred embodiments of the present application are described below, it should be understood that the embodiments are used to better explain the present application, not to limit the present application.

[0037] Raw material source

[0038] Polylactic acid: Fengyuan FY801, melting point 170℃, density 1.24g / cm3, glass transition temperature 60℃, melt index 4g / 10min(190℃ / 2.16kg)

[0039] Polymerized rosin: Yoshida Chemical Industry 140, softening point 135-145℃.

[0040] Example 1

[0041] 1. 3000 g of polylactic acid particles were weighed and dried in a vacuum oven for 12 h. After the end of the drying process, the particles were mixed and granulated in a granulator to prepare polylactic acid / polymerized rosin 10:0 mixed particles. The process parameters of the granulator were set as follows: the temperature of each section of the extruder was 180°C for section 1, 185°C for section 2, 185°C for section 3, 180°C for section 4, 175°C for section 5, and 170°C for section 6, and the rotation speed was 75 r / min.

[0042] 2. The mixed particles prepared in step 1 were put into a melt-blowing machine with the parameters set, and a polylactic acid / polymerized rosin melt-blown fabric was prepared by melt-blowing. The parameters of the melt-blowing machine were set as follows: the temperature of section 3 was 220°C, the temperature of section 2 was 225°C, the temperature of section 1 was 230°C, the temperature of the conversion box was 240°C, the temperature of the head was 245°C, the temperature of the hot air was 270°C, the rotation speed of the metering pump was 600 r / min, and the rotation speed of the screw was 600 r / min.

[0043] 3. The polylactic acid / polymerized rosin melt-blown fabric prepared in step 2 was placed in a Soxhlet extractor, and the polymerized rosin was washed away by petroleum ether. The temperature was set to 100°C, and the extraction time was 2 h to obtain a low-melt-index polylactic acid nanofiber melt-blown fabric.

[0044] Example 2

[0045] This example was performed according to Example 1, except that the mixed particles in step (1) were replaced by polylactic acid / polymerized rosin 9:1 mixed particles, i.e., 2700 g of polylactic acid particles and 300 g of polymerized rosin particles were mixed. The other parameters and operations were unchanged, and a low-melt-index polylactic acid nanofiber melt-blown fabric was finally prepared.

[0046] Example 3

[0047] This example was performed according to Example 1, except that the mixed particles in step (1) were replaced by polylactic acid / polymerized rosin 8:2 mixed particles, i.e., 2400 g of polylactic acid particles and 600 g of polymerized rosin particles were mixed. The other parameters and operations were unchanged, and a low-melt-index polylactic acid nanofiber melt-blown fabric was finally prepared.

[0048] Example 4

[0049] This example was performed according to Example 1, except that the mixed particles in step (1) were replaced by polylactic acid / polymerized rosin 7:3 mixed particles, i.e., 2100 g of polylactic acid particles and 900 g of polymerized rosin particles were mixed. The other parameters and operations were unchanged, and a low-melt-index polylactic acid nanofiber melt-blown fabric was finally prepared.

[0050] The low-melt-index polylactic acid nanofiber melt-blown fabric prepared in Examples 1-4 above was subjected to property detection.

[0051] Melt index test: The melt index of different ratio of PLA / PR was tested by melt index tester (XNR-400C MI4 melt index tester of Goettfert company in Germany), the test temperature was 190℃, and the test load was 2.16kg.

[0052] Contact angle test: The different ratio of melt blown nonwoven material was adhered on a glass slide, and 5ul water droplet was taken by a microsyringe for testing the contact angle, the instrument used was contact angle measuring instrument (JC2000C1).

[0053] Oil absorption performance test: The same weight of PLA / PR melt blown nonwoven material which was dried sufficiently was placed in oil red dyed oily solvent (n-hexane, silicone oil, edible oil) for 30s, and was taken out and suspended for 90s, after the liquid no longer fell, the weight was weighed and recorded.

[0054] Oil-water separation test: n-hexane (density is smaller than water), silicone oil (density is larger than water) were dyed with oil red, and a small amount of them were dropped into methyl blue blue deionized water, and the 1cm×1cm cloth sample was used for absorption test.

[0055] The results of the test are shown in the attached drawings and Table 1.

[0056] Table 1 The surface density and porosity of the low melt index polylactic acid nanofiber melt blown cloth prepared in the embodiments of the present application

[0057]

[0058] The above provided examples are not intended to limit the scope covered by the present application, and the described steps are not intended to limit the execution order. The improvements of the present application made by those skilled in the art in combination with the existing common knowledge are also within the protection scope defined by the claims of the present application.

Claims

1. A method for preparing a polylactic acid nanofiber melt-blown fabric, characterized by, The method comprises the following steps: (1) weighing polylactic acid and polymerized rosin, drying, mixing and granulating to prepare polylactic acid / polymerized rosin mixed particles; The mass ratio of polylactic acid to polymerized rosin is 8:1.5-2.5; the process parameters for mixing and granulating in the granulator are as follows: the temperature of each section is 175-180℃ for the first section, 180-185℃ for the second section, 180-185℃ for the third section, 175-180℃ for the fourth section, 170-175℃ for the fifth section and 165-170℃ for the sixth section, and the rotating speed is 65-75 r / min; (2) putting the polylactic acid / polymerized rosin mixed particles prepared in step (1) into a melt blowing machine to prepare polylactic acid / polymerized rosin melt blown cloth by melt blowing; the parameters of the melt blowing machine are set as follows: the temperature of the third section is 210-220℃, the temperature of the second section is 210-225℃, the temperature of the first section is 210-230℃, the temperature of the conversion box is 220-240℃, the temperature of the head is 220-245℃, the temperature of the hot air is 250-270℃, the rotating speed of the metering pump is 500-600 r / min, and the rotating speed of the screw is 500-600 r / min; (3) removing the polymerized rosin from the polylactic acid / polymerized rosin melt blown cloth prepared in step (2) by solvent treatment to obtain polylactic acid nanofiber melt blown cloth.

2. The method of claim 1, wherein, In step (1), the mass ratio of polylactic acid to polymerized rosin is 8:

2.

3. The method of claim 1, wherein, In step (3), the solvent for extraction is petroleum ether.

4. The method as claimed in claim 1, characterized in that In step (3), the extraction temperature is 100-110℃, and the extraction time is 1.5-3 h.

5. Polylactic acid nanofiber melt blown cloth prepared by the method according to any one of claims 1-4.

6. Application of the polylactic acid nanofiber melt blown cloth according to claim 5 in the fields of medical health and water-oil separation.

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