阅读说明：本技术 基于瞬时释压纺丝法制备聚丙烯纤维集合体的方法及应用 (Method for preparing polypropylene fiber aggregate based on instantaneous pressure-release spinning method and application ) 是由 相恒学 朱美芳 王倩倩 潘伟楠 周家良 胡泽旭 杨利军 于 2020-06-10 设计创作，主要内容包括：本发明属于聚丙烯非织造布制备领域,公开了一种基于瞬时释压纺丝法制备聚丙烯纤维集合体的方法,将聚丙烯和增塑剂加入超临界釜中,搅拌注入超临界二氧化碳,得到超临界流体；将超临界流体瞬时释放到纺丝环境中,由超临界状态发生气液分离,增塑剂和二氧化碳以气体形式置换到空气中,超临界流体中的聚丙烯冷却后得到固化聚丙烯,并在气压流动作用下发生牵伸形成聚丙烯微纳纤维集合体。本发明还公开了上述聚丙烯微纳纤维集合体的应用,经过静电开纤和热轧后形成聚丙烯非织造布。本发明用于制备聚丙烯微纳纤维集合体,其直径达到0.5~5μm,制备的聚丙烯非织造布性能远胜于熔喷或纺粘制备的聚丙烯非织造布材料,在防护服领域具有巨大的应用前景。(The invention belongs to the field of preparation of polypropylene non-woven fabrics, and discloses a method for preparing a polypropylene fiber aggregate based on an instantaneous pressure-release spinning method, which comprises the steps of adding polypropylene and a plasticizer into a supercritical kettle, stirring and injecting supercritical carbon dioxide to obtain a supercritical fluid; releasing the supercritical fluid into a spinning environment instantly, performing gas-liquid separation in a supercritical state, replacing a plasticizer and carbon dioxide into air in a gas form, cooling polypropylene in the supercritical fluid to obtain solidified polypropylene, and drafting under the action of air pressure flow to form a polypropylene micro-nano fiber aggregate. The invention also discloses application of the polypropylene micro-nano fiber aggregate, and polypropylene non-woven fabric is formed after electrostatic fiber opening and hot rolling. The invention is used for preparing the polypropylene micro-nano fiber aggregate, the diameter of the polypropylene micro-nano fiber aggregate reaches 0.5-5 mu m, the performance of the prepared polypropylene non-woven fabric is far better than that of a polypropylene non-woven fabric material prepared by melt-blowing or spun-bonding, and the polypropylene non-woven fabric has great application prospect in the field of protective clothing.)

1. A method for preparing a polypropylene fiber aggregate based on an instant pressure-release spinning method is characterized by comprising the following steps:

s1, adding polypropylene and a plasticizer into a supercritical kettle, and injecting supercritical carbon dioxide under stirring to obtain a stable supercritical fluid;

and S2, releasing the supercritical fluid into the atmospheric environment instantly, performing gas-liquid separation on the supercritical fluid from a supercritical state, replacing the plasticizer and the carbon dioxide into the air in a gas form, cooling the polypropylene in the supercritical fluid to obtain solidified polypropylene, and drafting the solidified polypropylene under the action of air pressure flow to form the polypropylene micro-nano fiber aggregate.

2. The method for preparing the polypropylene fiber assembly based on the instant pressure-release spinning method as claimed in claim 1, wherein the polypropylene is isotactic polypropylene or metallocene polypropylene, and the melt index is 20-60 g/10 min; the plasticizer is one of dioxane, cyclohexane, dichloromethane, xylene and ethylene glycol monomethyl ether.

3. The method for preparing the polypropylene fiber assembly based on the instant pressure-release spinning method as claimed in claim 1, wherein the mass ratio of the polypropylene to the plasticizer is 70-95: 30-5.

4. The method for preparing a polypropylene fiber assembly according to claim 1, wherein the processing temperature of the supercritical kettle is 130 to 190 ℃, the pressure after injecting the supercritical carbon dioxide is 8 to 18MPa, and the stirring time is 1 to 3 hours in step S1.

5. The method for preparing a polypropylene fiber assembly according to claim 1, wherein the supercritical fluid is instantaneously released to the atmosphere at 200 to 300 m/S in step S2.

6. The method for preparing the polypropylene fiber assembly based on the instant pressure-release spinning method as claimed in claim 1, wherein the diameter of the polypropylene micro-nano fiber assembly is 0.5-5 μm.

7. The application of the polypropylene fiber assembly prepared based on the instant pressure-release spinning method according to any one of claims 1-6, wherein the polypropylene fiber assembly is used for forming polypropylene non-woven fabric after electrostatic fiber opening and hot rolling.

8. The application of the instant pressure-release spinning method for preparing the polypropylene fiber assembly as claimed in claim 7, wherein the longitudinal tensile breaking strength of the polypropylene nonwoven fabric is 190-220N, and the transverse tensile breaking strength is 110-137N.

Technical Field

The invention belongs to the field of preparation of polypropylene non-woven fabrics, and particularly relates to a method for preparing a polypropylene fiber aggregate based on an instantaneous pressure release spinning method and application thereof.

Background

In 2020, a novel coronavirus pneumonia epidemic situation (COVID-19) is developed all over the world, medical protective products such as masks and protective clothing are always in a state of shortage under the situation of epidemic situation, and the main reason is the shortage of key filtering materials in protective textiles. In order to realize high barrier property of the medical protective material, electret melt-blown non-woven fabric, electrostatic-spun non-woven fabric, porous membrane material and the like are generally selected. The electret melt-blown non-woven fabric technology is mature, and is a technology used for producing N95 masks in a large scale by international companies such as 3M company, Honeyville and the like; although the material produced by the electrostatic spinning non-woven fabric technology has good filtering effect, the material is limited by electrostatic spinning capacity and is difficult to meet the large-scale requirement of epidemic situation protection; in addition, the porous membrane is used as a protective material, the preparation technology of the porous membrane is still not mature enough, and great contradiction exists among the filtration efficiency, the air resistance and the cost.

Currently, the basic condition for achieving uniform fine diameters of electret melt-blown nonwoven fibers is the use of high melt index polypropylene (PP) resins with very excellent processing flow properties. Generally speaking, the high-melt-index PP resin has a melt index of 1500-2000 g/10min, which is much higher than that of ordinary PP resin (2-60 g/10 min). The existing high-melting-point PP resin preparation route mainly adopts a peroxide degradation method and a metallocene catalytic polymerization method, and relatively speaking, the PP resin prepared by the peroxide degradation method has the defects of long preparation process, high production energy consumption, poor product flow property stability and insufficient content of high Volatile Organic Compounds (VOC); the metallocene catalysis for preparing PP resin has the advantages of stable fluidity, low VOC and low production cost, but the preparation core technology is only mastered by the industrial company Liandedsel in the Netherlands for a long time. Therefore, in order to better deal with the COVID-19 epidemic situation prevention and the important public health emergencies which may happen in the future, the exploration and establishment of a new technology which is not limited by the high-melt-index PP resin base raw material and can produce the micro-fiber assembly (including yarn, fabric and non-woven fabric) in a large scale has extremely important strategic significance.

The flash evaporation method is a method for preparing the non-woven fabric by dissolving polyethylene in an organic solvent (such as toluene, xylene and the like) at high temperature and high pressure and adopting a solution spinning dry process, has the problems of large solvent pollution and difficult controllability of fiber morphology in the preparation process, has strict and confidential technical process of DuPont company, and only has a few colleges and universities and enterprises to make exploratory research. The 'instantaneous pressure relief' (FPR) spinning method is based on the control of a high-solubility solution phase diagram under a supercritical condition and the vector finite element analysis of the temperature, the speed and the pressure of a spinning channel, so that the engineering production of the fine polymer fibers and the aggregates thereof is realized, and the production process and fiber products can be calculated and simulated. Therefore, aiming at the problems of shortage of key filtering raw materials and low use efficiency of the current medical protective materials, the preparation of the conventional polypropylene (PP) non-woven fabric by using the instantaneous pressure release spinning has important scientific significance and application value.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a method for preparing a polypropylene fiber aggregate based on an instantaneous pressure-release spinning method, which takes supercritical fluid as spinning solution, and generates a polypropylene micro-fiber aggregate through gas-liquid separation in the jetting process of a spinning assembly;

another object of the present invention is to provide an application of the polypropylene fiber assembly prepared by the above-mentioned instant pressure-release spinning method, which can be used for preparing polypropylene nonwoven fabrics with high filtration efficiency, water permeability resistance and synthetic blood penetration resistance.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for preparing a polypropylene fiber aggregate based on an instant pressure-release spinning method comprises the following steps:

s1, adding polypropylene and a plasticizer into a supercritical kettle, and injecting supercritical carbon dioxide under stirring to obtain a stable supercritical fluid;

and S2, releasing the supercritical fluid into the atmospheric environment instantly, performing gas-liquid separation on the supercritical fluid from a supercritical state, replacing the plasticizer and the carbon dioxide into the air in a gas form, cooling the polypropylene in the supercritical fluid to obtain solidified polypropylene, and drafting the solidified polypropylene under the action of air pressure flow to form the polypropylene micro-nano fiber aggregate.

As a limitation, the polypropylene is isotactic polypropylene or metallocene polypropylene, and the melt index is 20-60 g/10 min; the plasticizer is one of dioxane, cyclohexane, dichloromethane, xylene and ethylene glycol monomethyl ether.

The second limitation is that the mass ratio of the polypropylene to the plasticizer is 70-95: 30-5.

As a third limitation, in step S1, the processing temperature of the supercritical reactor is 130 to 190 ℃, the pressure after injecting the supercritical carbon dioxide is 8 to 18MPa, and the stirring time is 1 to 3 hours.

As a fourth limitation, in step S2, the supercritical fluid is instantaneously released into the atmosphere at 200-300 m/S.

The fifth limitation is that the diameter of the polypropylene micro-nano fiber aggregate is 0.5-5 μm.

The invention also provides an application of the polypropylene fiber assembly prepared based on the instantaneous pressure release spinning method, and the polypropylene micro-nano fiber assembly is used for forming polypropylene non-woven fabric after electrostatic fiber opening and hot rolling.

The polypropylene non-woven fabric has a longitudinal tensile breaking strength of 190-220N and a transverse tensile breaking strength of 110-137N.

Due to the adoption of the technical scheme, compared with the prior art, the invention has the technical progress that:

(1) the instantaneous pressure-release spinning method in the invention takes supercritical fluid as spinning solution, compared with a flash evaporation method, the spinning pressure difference and the spinning spraying speed are higher, and the recovery and the treatment of an organic solvent can be effectively avoided;

(2) the invention solves the problems of large solvent pollution and difficult controllability of fiber appearance in the production process of the non-woven fabric by the flash evaporation method through the instantaneous pressure-releasing spinning method;

(3) in the invention, the supercritical fluid is subjected to gas-liquid separation in the instantaneous release process to generate a polypropylene micro-nano fiber aggregate, and the polypropylene non-woven fabric formed by electrostatic fiber opening and hot rolling has higher filtering efficiency, water permeability resistance and synthetic blood penetrability resistance;

(4) the diameter of the polypropylene micro-nano fiber aggregate prepared by the invention can reach 0.5-5 mu m.

The invention belongs to the technical field of polypropylene non-woven fabrics, and is used for preparing a polypropylene micro-nano fiber aggregate.

Drawings

FIG. 1 is a scanning electron microscope image of a polypropylene micro-nano fiber aggregate prepared in example 1 of the invention;

fig. 2 is a polypropylene nonwoven fabric prepared by a polypropylene micro-nano fiber assembly in example 1 of the present invention.

Detailed Description

For a better understanding of the present invention, reference will now be made in detail to the present invention by way of specific embodiments thereof.