CN102943315B - PLA (polylactic acid) conductive fiber and preparation method thereof - Google Patents

Abstract

The invention discloses a PLA conductive fiber and a preparation method thereof. The raw material ratio of the fiber is: 50-80 parts of PLA, poly(vinyl acetate-co-vinyl alcohol) (P(VAc-co-VA)) 20-50 parts, conductive filler 0.05-8 parts. The preparation method of PLA conductive fibers comprises: (1) taking dry PLA, P(VAc-co-VA) and conductive filler according to the above-mentioned proportion and premixing to obtain the conductive masterbatch of PLA; Weighing P(VAc-co-VA) and conductive fillers according to the above ratio and premixing, blending and granulating to obtain P(VAc-co-VA) conductive masterbatch, and then taking PLA to blend with it to obtain PLA conductive masterbatch; (2) Melt-spinning the conductive masterbatch of PLA——drawing to obtain PLA conductive fibers. The conductive fiber can be used as electrode, antistatic, low temperature heating, electromagnetic shielding, heat sensitive and gas sensitive materials.

Description

A kind of polylactic acid conductive fiber and preparation method thereof

technical field

The invention relates to the field of polymer materials, in particular to polylactic acid (PLA) conductive fibers and a preparation method thereof.

Background technique

China is a big country of fiber production. The output of synthetic fiber has ranked first in the world for 15 consecutive years. The total value of fiber and its textiles accounts for about 10% of China's GDP, and exports account for 1/4, which is very important in the national economy. At present, the development of synthetic fibers in China has the following problems: First, the development of synthetic fibers is restricted by the shortage of resources, and more than 90% of the raw materials of synthetic fibers depend on oil, and the total amount of proven oil and the consumption rate are calculated , 50 years later, fiber and its related industries will be in a state of "cooking without rice"; secondly, the development of synthetic fibers is restricted by environmental pollution, and petroleum-based chemical fibers cannot be degraded in nature, which will bring very serious "white pollution". Seriously affect people's quality of life. Therefore, it is very important to shift the research and development focus of the synthetic fiber industry to the research and development of renewable and biodegradable materials. Thirdly, my country's chemical fiber production is still dominated by conventional fibers, and the development of high-tech fibers lags behind. The output of synthetic fibers accounts for 2/3 of the world's total, but the proportion of functionalization is less than 10%, far below the level of more than 30% in developed countries. Therefore, realizing the functionalization and high performance of chemical fibers to increase the added value of fibers and enhance market competitiveness meets the needs of the development of chemical fibers in my country.

PLA resources are renewable, biodegradable, and biocompatible. At the same time, it is a thermoplastic polymer material that can be directly melt-spun to produce fibers. At present, the melt-spinning technology of PLA is mature, and PLA is expected to replace Petroleum-based polymer materials become the raw materials of chemical fibers to solve the problems of resource shortage and environmental pollution faced by the development of synthetic fibers. However, the research and development work on the functionalization of PLA fibers is less, and the conductive functionalization of fibers is the focus of development and research in the industry and academia. Therefore, it is necessary to realize the conductive functionalization of PLA fibers, and currently only Petra at the Institute of Polymer Research in Dresden, Germany 【 P.; Kobashi, K.; Villmow, T.; Andres, T.; Paiva, MC; Covas, JA Liquid sensing properties of melt processed polypropylene/poly(e-caprolactone blends containing multiwalled carbon nanotubes. 1451-1460.] PCL/PLA/MWNTs conductive fibers were prepared by melt spinning, but the mechanical properties of the obtained conductive fibers were poor, and the breaking strength and elongation at break of the obtained as-spun fibers were only 22MPa and 6.2%, respectively. The textile field has no practical application value.

Contents of the invention

The purpose of the present invention is to develop a PLA conductive fiber and provide a preparation method for the current situation that there are few functionalized PLA fiber products.

A kind of polylactic acid (PLA) conductive fiber, is made of the raw material of following mass parts:

PLA: 50-80 parts;

Poly(vinyl acetate-co-vinyl alcohol) (P(VAc-co-VA)): 20 to 50 parts;

Conductive filler: 0.05 to 8 parts;

The PLA conductive fiber is characterized in that the viscosity-average molecular weight of PLA is: 6.0×10 ⁴ to 3.0×10 ⁵ ;

The PLA conductive fiber is characterized in that the content of D-lactic acid units in PLA is: 0-10mol%;

The PLA conductive fiber is characterized in that the conductive filler is carbon black (CB), single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs), graphene (GN), vapor phase carbon nanofibers (VGCNFs), One of copper sulfide, cuprous sulfide and cuprous iodide;

The PLA conductive fiber is characterized in that the viscosity-average molecular weight of P(VAc-co-VA) is 5.0×10 ⁴ to 1.0×10 ⁶ ;

The PLA conductive fiber is characterized in that the proportion of vinyl alcohol structural units in P(VAc-co-VA) is 9mol% to 80mol%;

The preparation method of described PLA conductive fiber, comprises the steps:

(1) Dry PLA, P(VAc-co-VA) and conductive fillers in a vacuum oven for 8-48 hours in advance, and the drying temperatures of PLA, P(VAc-co-VA) and conductive fillers are 50-120°C, 25～55℃ and 50～120℃;

(2) Take 50-80 parts of PLA, 20-50 parts of P(VAc-co-VA) and 0.05-8 parts of conductive filler and put them into a high-speed mixer for 3-5 minutes and then blend them in a twin-screw blender Granulation to obtain PLA conductive masterbatch, the granulation temperature is 160-220°C, the rotation speed is 50-150rmp, and the melt-blending time is 3-8 minutes; or first take 20-50 parts of P(VAc-co-VA) and 0.05 ～8 parts of conductive masterbatches are put into a high-speed mixer and dry-blended for 3-5 minutes, and then blended and granulated in a twin-screw blender to obtain P(VAc-co-VA) conductive masterbatches, and the melt-blending temperature is 160 ~220°C, rotation speed 50~150rmp, melt blending time 3~6 minutes, then take 50~80 parts of PLA and blend with the obtained P(VAc-co-VA) conductive masterbatch to obtain PLA conductive masterbatch. The particle temperature is 160-220°C, the rotation speed is 50-150rmp, and the melt-blending time is 3-8 minutes;

(3) Spin the PLA conductive masterbatch on a melt spinning machine to obtain conductive PLA primary fibers, the spinning temperature is 170-220°C, and the winding speed is 1500-3000m/min;

(4) Draw the as-spun fibers to obtain PLA conductive fibers, the drawing temperature is 100-125° C., and the drawing ratio is 1-6 times.

Beneficial effect:

The invention realizes the conductive functionalization of PLA fiber by using the ordinary melt spinning method, and is convenient to operate. In addition, the percolation threshold is low, that is, the amount of conductive filler is small, the spinnability of the fiber is good, and the cost is low. The electrical conductivity of the obtained PLA conductive fiber can reach 2.5 S/m, the breaking strength is 2.0-6.0 cN/dtex, and the breaking elongation is 20%-80%.

Detailed ways

Below in conjunction with specific embodiment, further illustrate the present invention. It should be understood that these examples are only for illustrating the present invention and do not limit the scope of the present invention. In addition, it should be understood that after reading the teachings of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

Example 1

(1) First weigh 50 parts of PLA (the content of D-lactic acid unit is 2.1mol%), 50 parts of P(VAc-co-VA) and 4 parts of carbon black and dry them in a vacuum oven for 12 hours (80°C), 48 hours (40°C) and 8 hours (100°C), then put them into a high-speed mixer and dry mix for 3 minutes, and then blend and granulate in a twin-screw blender to obtain PLA conductive masterbatches. The granulation temperature was 170° C., the screw speed was 75 rpm, and the melt blending time was 8 minutes.

(2) Spin the PLA conductive masterbatch on a melt spinning machine to obtain conductive PLA primary fibers, the spinning temperature is 190°C, and the winding speed is 1500m/min;

(3) Draw the as-spun fibers to obtain PLA conductive fibers, the drawing temperature is 110° C., and the drawing ratio is 3 times. The electrical conductivity of the obtained PLA conductive fiber was 1.52 S/m, the breaking strength was 2.5 cN/dtex, and the breaking elongation was 50.5%.

Example 2

(1) First weigh 60 parts of PLA (the content of D-lactic acid unit is 0.5 mol%), 40 parts of P(VAc-co-VA) and 3 parts of MWCNTs and dry them in a vacuum oven for 15 hours (70°C), 36 hours (45°C) and 8 hours (110°C), and then they were put into a high-speed mixer and dry-blended for 4 minutes, and then blended and granulated in a twin-screw blender to obtain PLA conductive masterbatches. The granulation temperature was 180° C., the screw speed was 60 rpm, and the melt blending time was 7 minutes.

(2) Spin the PLA conductive masterbatch on a melt spinning machine to obtain conductive PLA primary fibers, the spinning temperature is 200°C, and the winding speed is 3000m/min;

(3) Draw the as-spun fibers to obtain PLA conductive fibers, the drawing temperature is 100° C., and the drawing ratio is 4 times. The electrical conductivity of the obtained PLA conductive fiber was 1.78 S/m, the breaking strength was 3.0 cN/dtex, and the breaking elongation was 30.8%.

Example 3

(1) First weigh 65 parts of PLA (the content of D-lactic acid unit is 1.0 mol%), 35 parts of P(VAc-co-VA) and 2.5 parts of SWCNTs and dry them in a vacuum oven for 12 hours (90°C), 48 parts respectively. hours (40°C) and 12 hours (100°C), put the dry P(VAc-co-VA) and conductive masterbatch into a high-speed mixer for 3 minutes, and then blend and granulate in a twin-screw blender , and then mixed and granulated in a twin-screw blender to obtain P(VAc-co-VA) conductive masterbatch, the melt blending temperature is 170 ° C, the speed is 75rmp, and the melt blending time is 6 minutes; the dry PLA Put the obtained P(VAc-co-VA) conductive masterbatch into a high-speed mixer and dry mix for 3 minutes, melt and blend to obtain PLA conductive masterbatch, the temperature is 190°C, the speed is 80rmp, and the melt blending time is 6 minutes , to get PLA conductive masterbatch.

(2) Spin the PLA conductive masterbatch on a melt spinning machine to obtain conductive PLA primary fibers, the spinning temperature is 190°C, and the winding speed is 2000m/min;

(3) Draw the as-spun fibers to obtain PLA conductive fibers, the drawing temperature is 100° C., and the drawing ratio is 2.5 times. The electrical conductivity of the obtained conductive fiber was 1.45 S/m, the breaking strength was 2.0 cN/dtex, and the breaking elongation was 80.9%.

Example 4

(1) First weigh 60 parts of PLA (the content of D-lactic acid unit is 2.5mol%), 40 parts of P(VAc-co-VA) and 6 parts of carbon black and dry them in a vacuum oven for 12 hours (90°C), After 48 hours (40°C) and 12 hours (100°C), dry P(VAc-co-VA) and conductive masterbatches were put into a high-speed mixer and mixed for 4 minutes, and then blended in a twin-screw blender to make granules, and then mixed and granulated in a twin-screw blender to obtain P(VAc-co-VA) conductive masterbatches. The melt blending temperature is 170 ° C, the rotation speed is 75 rpm, and the melt blending time is 6 minutes; the dried PLA and the obtained P(VAc-co-VA) conductive masterbatch were put into a high-speed mixer and dry mixed for 4 minutes, and the PLA conductive masterbatch was obtained by melt blending. The temperature was 190°C, the rotating speed was 80rmp, and the melt blending time was 6 Minutes to get PLA conductive masterbatch.

(2) Spin the PLA conductive masterbatch on a melt spinning machine to obtain conductive PLA primary fibers, the spinning temperature is 190°C, and the winding speed is 1500m/min;

(3) Draw the as-spun fibers to obtain PLA conductive fibers, the drawing temperature is 100° C., and the drawing ratio is 5 times. The electrical conductivity of the obtained conductive fiber was 2.01 S/m, the breaking strength was 3.8 cN/dtex, and the breaking elongation was 25.7%.

Claims (2)

1. PLA (PLA) conductive fiber, be made up of the raw material of following parts by mass:

PLA:50 ~ 80 part;

Poly-(vinylacetate-co-vinyl alcohol) (P (VAc-co-VA)): 20 ~ 50 parts;

Conductive filler: 0.05 ~ 8 part;

Wherein the viscosity average molecular weigh of PLA is: 6.0 × 10 ⁴~ 3.0 × 10 ⁵;

In PLA, the content of L-lactic acid unit is: 0 ~ 10mol%;

Conductive filler is the one in carbon black (CB), Single Walled Carbon Nanotube (SWCNTs), multi-walled carbon nano-tubes (MWCNTs), Graphene (GN), gas phase nano carbon fiber (VGCNFs), copper sulfide, cuprous sulfide and cuprous iodide;

The viscosity average molecular weigh of P (VAc-co-VA) is 5.0 × 10 ⁴~ 1.0 × 10 ⁶;

The ratio of the vinyl alcohol construction unit in P (VAc-co-VA) is 9mol% ~ 80mol%.

2. the preparation method of PLA conductive fiber according to claim 1, comprises the steps:

(1) in advance the baking temperature of PLA, P (VAc-co-VA) and conductive filler dry 8 ~ 48h, PLA, P (VAc-co-VA) and conductive filler in vacuum drying oven is respectively 50 ~ 120 DEG C, 25 ~ 55 DEG C and 50 ~ 120 DEG C;

(2) get PLA50 ~ 80 part, P (VAc-co-VA) 20 ~ 50 parts and conductive filler 0.05 ~ 8 part to put in super mixer and be dry mixed 3 ~ 5 minutes, then blended granulation in twin-screw blender, obtain PLA conductive agglomerate, prilling temperature is 160 ~ 220 DEG C, rotating speed is 50 ~ 150rmp, and the melt blending time is 3 ~ 8 minutes; Or first get 20 ~ 50 parts of P (VAc-co-VA) and 0.05 ~ 8 part of conductive agglomerate to put in super mixer and be dry mixed 3 ~ 5 minutes, then blended granulation in twin-screw blender, obtain P (VAc-co-VA) conductive agglomerate, melt blending temperature is 160 ~ 220 DEG C, rotating speed is 50 ~ 150rmp, the melt blending time is 3 ~ 6 minutes, then get P (VAc-co-VA) conductive agglomerate of 50 ~ 80 parts of PLA and gained blended PLA conductive agglomerate, prilling temperature is 160 ~ 220 DEG C, rotating speed is 50 ~ 150rmp, and the melt blending time is 3 ~ 8 minutes;

(3) by the spinning on melt spinning machine of PLA conductive agglomerate, must conduct electricity PLA as-spun fibre, spinning temperature is 170 ~ 220 DEG C, and winding speed is 1500 ~ 3000m/min;

(4) carry out drawing-off to as-spun fibre, obtain PLA conductive fiber, drawing temperature is 100 ~ 125 DEG C, and drafting multiple is 1 ~ 6 times.