CN1304674C - Superfine non-woven fabric from fiber of poly lactic acid and fabricating method - Google Patents

Abstract

The present invention belongs to the field of a textile material, and discloses a superfine polylactic acid fiber non-woven fabric which is formed by sticking superfine polylactic acid fibres together. The average thickness of each superfine polylactic acid fiber is from 2.7 mu m to 9.07 mu m, and the superfine polylactic acid fibers are distributed at random in a single fiber way. A fabricating method is realized by process steps of slice dryness, fusing extrusion, fiber formation, fiber cooling and net forming strengthening and the technology improvement of each process step. Compared with the existing polylactic acid fiber non-woven fabric, the present invention has the advantages of high filtration efficiency and favorable environment protection.

Description

Ultrafine polylactic acid fiber nonwoven fabric and its manufacturing method

Technical field:

The invention belongs to the field of textile materials, and relates to an ultrafine polylactic acid fiber nonwoven fabric and a manufacturing method thereof.

Background technique:

Environment and development are the themes of the 21st century. In response to global environmental problems, people are eager to develop a polymer material that can decompose in the natural environment. After continuous research, development and practical attempts, people are paying more and more attention to biodegradable polymer materials.

The raw materials for traditional polymers such as polypropylene are based on petroleum, which is increasingly depleted and non-renewable. In addition, massive consumption of petroleum will also contribute to the increase of global warming.

Considering the above two points, biodegradable polymers derived from renewable resources have become the focus of attention. Polylactic acid is just such a polymer. It uses annual renewable corn as raw material to make polylactic acid products, which is of great significance to comprehensive utilization of resources, reduction of environmental pollution and sustainable development.

At present, polylactic acid has been reported to be used in the manufacture of fibers and fiber products. The invention patent "polylactic acid resin and fiber products made of it and method for manufacturing fiber products" (application number 00809110.2) describes fiber products made of polylactic acid, and the average fiber fineness of long-fiber non-woven products is 1~15dtex (11μm~42μm). Due to its coarse fiber fineness, its application as a filter material is limited.

In addition, although the existing ultra-fine polypropylene fiber nonwoven fabric has good filtration performance, it cannot be degraded in nature, which is not conducive to environmental protection.

Invention content:

The object of the present invention is to provide an ultrafine polylactic acid fiber nonwoven fabric with excellent filtration performance and biodegradability and a manufacturing method thereof in view of the deficiencies of the prior art.

The technical scheme that the present invention solves technical problem is as follows:

An ultrafine polylactic acid fiber nonwoven fabric is characterized in that it is composed of ultrafine polylactic acid fibers with an average fiber fineness of 2.7 μm to 9.07 μm and randomly distributed single fibers bonded together. The mass is 44-123.7g/m ² , the thickness is 0.645-1.399mm, the average pore size of the fiber web is 11.3865μm-24.9693μm, the longitudinal specific strength is 21.10-35N·m ² /100g, and the transverse specific strength is 10.91-22.64N· ^m2 /100g;

A method for manufacturing ultrafine polylactic acid fiber nonwoven fabrics, which includes slice drying step 1, melt extrusion step 2, fiber forming step 3, fiber cooling step 4, and web forming reinforcement step 5, characterized in that the The improved process condition of the slice drying step 1 is that the temperature of the dehumidification dryer is 80-100°C, and the slice drying time is 6-8 hours; the improved process condition of the melt extrusion step 2 is that the screw extruder The screw speed is 30-41rpm, the temperature of the first zone, the second zone, and the third zone of the screw is 123-153°C, 193-242°C, 196-276°C respectively, and the temperature of the filter, elbow, and melt-blown die head are respectively 300～320°C, 200～270°C, 148～230°C; the improved process condition of the fiber forming step 3 is that the pressure of the stretching air is 0.2～0.46Mpa, the temperature of the air distribution chamber is 283～330°C, the air The temperature of the heater is 594-712°C; the improved process condition of the fiber cooling step 4 is that the acceptance distance between the melt-blown die head and the receiving drum is 8-18 cm; the improved process condition of the web-forming reinforcement step 5 The traverse speed of the receiving drum is 35-45 cm/min, and the reciprocating times are 2-10 times.

Compared with the prior art, the present invention has the following advantages:

1. The ultrafine polylactic acid fiber nonwoven fabric of the present invention obviously improves the filtration efficiency than the existing polylactic acid fiber nonwoven fabric because the fiber fineness obviously reduces;

2. The ultrafine polylactic acid fiber nonwoven fabric of the present invention has regeneration and biodegradability, and compared with the existing ultrafine polypropylene nonwoven fabric, it is beneficial to environmental protection and sustainable development.

Description of drawings:

Fig. 1 is the electron micrograph of ultrafine polylactic acid fiber nonwoven fabric structure of the present invention

In Fig. 1, A-ultrafine polylactic acid fiber nonwoven fabric, B-ultrafine polylactic acid fiber;

Fig. 2 is the processing equipment schematic diagram that the present invention adopts

In Figure 2, 1- dehumidification dryer, 2-feeder, 3-feeding hopper, 4-insulation hopper,

  5-storage barrel, 6-filter, 7-elbow, 8-meltblown die,

    9-receiving drum, 10-air distribution chamber, 11-screw extruder,

    12-air heater, 13-pressure reducing valve, 14-air filter,

                                                                                 

Detailed ways:

The present invention is realized by polylactic acid chipping and melt-blowing technology, which is characterized by linear chain L-isomer accounting for more than 95 mol%, glass transition temperature of 58.49-60.20°C, and melting temperature of 160.95-175°C.

As shown in Figure 1, the ultra-fine polylactic acid fiber nonwoven fabric is made of polylactic acid slices that are melted and extruded by a screw extruder and then extruded from the spinneret hole of the melt-blown die High-speed hot air flow stretches to form ultra-fine fibers with an average fiber fineness of 2.7 μm to 9.07 μm, which are in a state of random distribution of single fibers, and then gathered on the receiving drum and bonded together by ultra-fine polylactic acid fibers to form ultra-fine fibers. Polylactic acid fiber nonwoven fabric, ultrafine polylactic acid fiber nonwoven fabric has a mass per unit area of 44-123.7g/m ² , a thickness of 0.645-1.399mm, an average pore diameter of the fiber web of 11.3865μm-24.9693μm, and a longitudinal specific strength of 21.10～35N·m ² /100g, the transverse specific strength is 10.91～22.64N·m ² /100g.

As shown in Figure 2, utilize the manufacturing method that the processing equipment that makes ultrafine polylactic acid fiber nonwoven fabric of the present invention adopts comprises the following steps:

Slice drying step 1:

The polylactic acid slices are stored in the storage barrel 5, and the polylactic acid slices enter the feeding hopper 3 through the suction of the feeder 2, and then fall to the heat preservation hopper 4. The hot air passes into the insulation hopper 4 to dry the polylactic acid slices, and the drying time of the slices is 6-8 hours. Polylactic acid slices must be dried before being used in the melt-blown process for three reasons: 1. Remove the moisture in the polylactic acid slices to avoid the hydrolysis of the ester bonds of the polylactic acid macromolecules, resulting in difficulties in melt extrusion and reduced quality of the finished product; 2. Increase the water content of the slices Uniformity to ensure uniform fiber quality; 3. Improve the crystallinity and softening point of polylactic acid;

Melt extrusion step 2:

The dried polylactic acid slices are fed into the screw extruder 11 by the heat preservation hopper 4, heated and extruded to become a melt, the screw pitch of the screw extruder 11 is 3 cm, the ratio of the screw length to the screw diameter is 30, and the screw speed is 30 ～41rpm, the temperature of the first zone, the second zone and the third zone of the screw is respectively 123～153°C, 193～242°C, 196～276°C, the polylactic acid melt output by the screw extruder 11 is filtered by the filter 6 and then bent The head 7 is sent to the melt-blown die head 8, and the temperature of the filter 6, the elbow 7, and the melt-blown die head 8 are respectively 300-320°C, 200-270°C, and 148-230°C;

Fiber forming step 3:

The molten polylactic acid filaments extruded from the 8 spinneret holes of the melt blown die head are rapidly thinned and elongated under the stretching action of the high-speed hot air flow on both sides to form polylactic acid ultrafine fibers, and the compression produced by the air compressor 17 The air enters the air storage tank 15 through the steam-water separator 16, then enters the air heater 12 through the air filter 14 and the pressure reducing valve 13, and the heated air enters the air distribution chamber 10 and enters the melt-blown die head 8 in two ways, and from Spray from both sides of the spinneret hole to stretch the molten polylactic acid filaments extruded from the spinneret hole. The pressure of the stretching air is adjusted between 0.2 and 0.46MPa, and the temperature of the air distribution chamber 10 is adjusted between 283 and 330°C. Air heater 12 temperature is adjusted between 594～712 ℃. The width of the meltblown die head 8 is 200mm, the diameter of the spinneret holes of the meltblown die head 8 is 0.2mm, the center distance of the spinneret holes of the meltblown die head 8 is 0.9mm, and the number of spinneret holes of the meltblown die head 8 is 166 , the airflow angle on both sides of the spinneret hole of the melt-blown die head 8 is 60°;

Fiber Cooling Step 4:

While the stretching air is stretching the molten polylactic acid filaments extruded from the spinneret hole, a large amount of room temperature air on both sides of the outlet of the spinneret hole of the melt-blown die head 8 is sucked, and it is mixed with the ultrafine polylactic acid fiber. The hot air flow is mixed to cool it down, and the ultrafine polylactic acid fiber in the molten state is cooled and solidified. The receiving distance between the meltblown die head 8 and the receiving drum 9 is adjusted between 8 and 18 cm, and the ultrafine polylactic acid fiber is cooled. Solidification, generally starts at 6-7 mm away from the spinneret hole of the melt-blown die head 8;

Network reinforcement step 5:

The receiving drum 9 has both rotation and traverse, the constant rotation speed is generally 25 revolutions/min, the traverse speed is adjusted between 35-45 cm/min, and the reciprocating times are adjusted between 2-10 times. Within the receiving distance, the superfine polylactic acid fibers are horizontally sprayed to the receiving drum 9, and repeatedly piled up to form a web of polylactic acid superfine fibers, and at the same time, the superfine polylactic acid fibers are brought to the receiving drum 9 by the mixed airflow of room temperature air and stretched hot air. The lactic acid fibers are coagulated on the receiving drum 9 in a random distribution state, and still have residual temperature, so the superfine polylactic acid fibers can be bonded to each other, and the fiber web is strengthened, thus making the ultrafine polylactic acid fiber non-woven cloth.

The present invention is further described below through specific examples, but the examples are only for illustration, and cannot limit the scope of the present invention.

Example 1:

Slice drying step 1, melt extrusion step 2, fiber forming step 3, fiber cooling step 4, web forming reinforcement step 5, each processing step included in the manufacturing method of the ultrafine polylactic acid fiber nonwoven fabric of the present invention as described above and Adopt the following improvement process conditions to each processing step:

①The polylactic acid slices were dried at 100°C for 8 hours, and then fed into the screw extruder at a screw speed of 30rpm;

② The temperature of the screw zone 1, zone 2 and zone 3 is 127°C, 225°C, 227°C respectively, and the temperature of the filter, elbow and meltblown die is 316°C, 264°C, 150°C respectively;

③The pressure of the stretching air is 0.44Mpa, the temperature of the air distribution chamber is 312°C, and the temperature of the air heater is 652°C;

④ The receiving distance is 9cm, the traverse speed of the receiving drum is 40cm/min, and the reciprocating times are 4;

The performance test results of the obtained ultrafine polylactic acid fiber nonwoven fabric are:

The average fiber fineness is 9.07μm, the mass per unit area is 44g/m ² , the thickness is 0.645mm, the average pore diameter of the fiber web is 24.9693μm, the longitudinal specific strength is 35N·m ² /100g, and the transverse specific strength is 22.64N·m ² /100g, the blood filtration effect: the white blood cell removal rate is 74.0386%;

Example 2:

Slice drying step 1, melt extrusion step 2, fiber forming step 3, fiber cooling step 4, web forming reinforcement step 5, each processing step included in the manufacturing method of the ultrafine polylactic acid fiber nonwoven fabric of the present invention as described above and Adopt the following improvement process conditions to each processing step:

①The polylactic acid slices were dried at 100°C for 8 hours, and then fed into the screw extruder at a screw speed of 41rpm;

②The temperature of the screw zone 1, zone 2, and zone 3 is 146°C, 241°C, and 268°C respectively; the temperature of the filter, elbow, and melt blown die is 316°C, 200°C, and 216°C;

③The pressure of the stretching air is 0.44Mpa, the temperature of the air distribution chamber is 317°C, and the temperature of the air heater is 701°C;

④ The receiving distance is 8.5cm, the traverse speed of the receiving drum is 41.7cm/min, and the reciprocating times are 6;

The performance test results of the obtained ultrafine polylactic acid fiber nonwoven fabric are:

The average fiber fineness is 3.2μm, the mass per unit area is 99.6g/m ² , the thickness is 0.959mm, the average pore diameter of the fiber web is 16.8558μm, the longitudinal specific strength is 30.52N·m ² /100g, and the transverse specific strength is 13.45N· m ² /100g, its blood filtration effect: leukocyte removal rate is 87.2561%;

Example 3:

Slice drying step 1, melt extrusion step 2, fiber forming step 3, fiber cooling step 4, web forming reinforcement step 5, each processing step included in the manufacturing method of the ultrafine polylactic acid fiber nonwoven fabric of the present invention as described above and Adopt the following improvement process conditions to each processing step:

①The polylactic acid slices were dried at 100°C for 8 hours, and then fed into the screw extruder at a screw speed of 41rpm;

②The temperature of the screw zone 1, zone 2 and zone 3 is 149°C, 237°C, 274°C respectively, and the temperature of the filter, elbow and melt blown die is 316°C, 200°C, 222°C respectively;

③The pressure of the stretching air is 0.44Mpa, the temperature of the air distribution chamber is 317°C, and the temperature of the air heater is 673°C;

④ The receiving distance is 11cm, the traverse speed of the receiving drum is 41.7cm/min, and the reciprocating times are 8;

The performance test results of the obtained ultrafine polylactic acid fiber nonwoven fabric are:

The average fiber fineness is 2.7μm, the mass per unit area is 123.7g/m ² , the thickness is 1.399mm, the average pore diameter of the fiber web is 11.3865μm, the longitudinal specific strength is 21.10N·m ² /100g, and the transverse specific strength is 10.91N· m ² /100g, the blood filtration test results: the white blood cell removal rate is 99.9340%.

The comparative description of above-mentioned embodiment 1, embodiment 2, embodiment 3 filtration performance is as follows:

The polylactic acid fiber fineness that the obtained ultrafine polylactic acid fiber nonwoven fabric of embodiment 1 adopts is thicker, and the average pore diameter of the ultrafine polylactic acid fiber nonwoven fabric web that it forms is larger, so white blood cell is removed when filtering blood The polylactic acid fiber fineness that the obtained ultrafine polylactic acid fiber nonwoven fabric of embodiment 2 adopts is less, and the average pore diameter of the ultrafine polylactic acid fiber nonwoven fabric web that it forms is also smaller, and its filtration The leukocyte removal rate in blood is better than that of Example 1; the polylactic acid fiber fineness that the ultrafine polylactic acid fiber nonwoven fabric that embodiment 3 makes adopts is minimum, and the ultrafine polylactic acid fiber nonwoven fabric fiber web that it forms is average The pore size is also the smallest, so the white blood cell removal rate is higher when filtering blood. It can be seen that if the fineness of ultrafine polylactic acid fibers is reduced when manufacturing ultrafine polylactic acid fiber nonwovens, it will improve the efficiency of ultrafine polylactic acid fiber nonwovens. Cloth is beneficial to the filtering effect of white blood cells in the blood.

Claims (2)

1. An ultrafine polylactic acid fiber nonwoven fabric, characterized in that it is 2.7 μm to 9.07 μm in average fiber fineness, and the ultrafine polylactic acid fibers in the random distribution of single fibers are bonded together and constituted. The mass per unit area is 44-123.7g/m ² , the thickness is 0.645-1.399mm, the average pore size of the fiber web is 11.3865μm-24.9693μm, the longitudinal specific strength is 21.10-35N·m ² /100g, and the transverse specific strength is 10.91-22.64 N·m ² /100g. 2. a method for manufacturing the ultrafine polylactic acid fiber nonwoven fabric according to claim 1, it comprises slice drying step (1), melt extruding step (2), fiber forming step (3), fiber cooling step (4), web forming and strengthening step (5), is characterized in that the improved process condition of the described section drying step (1) is that the temperature of the dehumidification dryer is 80-100°C, and the section drying time is 6-8 hours; the improved process condition of the melt extruding step (2) is that the screw speed of the screw extruder adopts 30～41rpm, the screw rod one zone, two zones, and the temperature of the three zones respectively adopt 123～153 ℃, 193～242 ℃, 196～276 ℃, its filter, elbow, the temperature of melt-blown die adopts respectively 300～320 ℃, 200～270 ℃, 148～230 ℃; The improved process condition of described fiber forming step (3) The pressure of the stretched air is 0.2-0.46Mpa, the temperature of the air distribution chamber is 283-330°C, and the temperature of the air heater is 594-712°C; the improved process condition of the fiber cooling step (4) is that it is melt-blown The acceptance distance between the die head and the receiving drum is 8-18 cm; the improved process condition of the web forming reinforcement step (5) is that the traverse speed of the receiving drum is 35-45 cm/min, and the reciprocating times are 2-10 times .