CN100436701C - Method for preparing super fine light conductive fibre - Google Patents

Abstract

The process of preparing super fine light conductive fiber includes the following steps: electrically spinning polymer to form super fine light polymer fiber; and 2. chemically plating the super fine light polymer fiber. The prepared super fine light conductive fiber has the features diameter smaller than 1 micron, length smaller than 50 microns, density smaller than 2 g/cu cm and high conductivity. It may be used as the conductive filler for conducting adhesive in circuit board and electrode in the electronic industry, and the conducting adhesive has excellent conductivity and high stability.

Description

Preparation method of ultrafine lightweight conductive fiber

technical field

The invention relates to a method for preparing ultrafine lightweight conductive fibers.

Background technique

Currently, conductive adhesives widely used in the electronics industry are usually made of conductive materials such as metal powder, metal fiber or metal sheet mixed with a polymer matrix. In order to achieve good electrical conductivity, a large amount of metal filler is usually required. Since the density of the metal is usually 3-18 times that of the polymer, not only the consumption of the metal filler is large, but also the metal is easy to settle in the polymer to make the glue Liquid is unstable. Among the commonly used conductive fillers, gold and silver have excellent electrical conductivity and corrosion resistance, but are expensive. Copper has excellent electrical conductivity but is easily oxidized. At present, there is a patented technology [CN1826665] for silver plating on copper powder, which can ensure electrical conductivity and reduce costs. In order to reduce the density of conductive fillers, thereby reducing the dosage and improving the problem of settling, there have been electroless or electroplated metal technologies on non-metallic powders [SAMPL Journal 19, 6], but metal-plated powders still need a large amount of filling to obtain better results. Good conductivity. Metal-plated fibers can have good conductivity at a small filling amount, but because of the thicker diameter (generally 1-10μm) of general-purpose polymer short fibers, when they are plated with metal and used as the conductive component of the conductive adhesive, in some requirements exceeding Smaller occasions are still restricted. Polymer electrospinning can produce ultrafine polymer fibers with diameters from several nanometers to several microns [Nanotechnology, 7, 216]. Generally, the diameters of polymer fibers collected by electrospinning are between tens of nanometers and hundreds of nanometers. Crush it into lengths of tens of microns and still have a large aspect ratio. However, since polymers are usually non-conductive insulators, to obtain conductive fibers must be coated with a metal layer on the electrospun polymer fibers.

Contents of the invention

The purpose of the present invention is to provide a preparation method of superfine light weight conductive fiber with small filling amount and good conductivity.

The object of the present invention is achieved in the following manner: a preparation method of ultrafine lightweight conductive fibers, characterized in that: (a) dissolving polyacrylonitrile into a polymer solution, electrospinning at a voltage of 20-40kV Prepare polymer fibers, and then pulverize them into ultrafine lightweight polymer fibers with a diameter of 1nm-5μm, a fiber length of 10μm-1cm, and a fiber density of 1.0-2.0g/ ^cm3 ; (b) for ultrafine lightweight polymer fibers After the fiber is sensitized and activated, it is plated with silver, nickel, copper, gold or their alloys in the chemical plating solution.

The present invention has the following beneficial effects, the ultrafine light polymer fiber has the characteristics of ultrafine (diameter < 1 μm, length < 50 μm) and light weight (density ≤ 2g/cm ³ ). It can be used as a conductive filler in conductive adhesives for circuit boards and electrodes in the electronics industry. Not only the filling amount is small, but only 10-50wt% of such conductive fibers are filled into the polymer matrix to obtain good conductivity (volume resistivity is 1×10 ^-1 -1×10 ^-4 Ω·cm), and this kind of conductive fiber is not easy to settle in the polymer matrix, and the prepared glue has good stability.

Description of drawings

Fig. 1 is a schematic diagram of the preparation process of the present invention.

Detailed ways

The present invention will be further described below in conjunction with specific embodiment:

As shown in Figure 1, the preparation process is: after 5-30% of the polymer is dissolved in the corresponding solvent, it is loaded into the syringe (3), and the ejector pin of the syringe (2) filled with water is under the action of the circulation pump (1) Press down the syringe (3) at an even speed, turn on the high-voltage power supply (4), and the polymer droplets on the syringe needle (positive pole) fly to the negative pole under the action of the high-voltage electric field to form fibers and fall into the collection cup (5). According to the length requirements of the required fiber, the fiber film is crushed in a high-speed machine and then sieved. After the fiber is sensitized (6), activated (7), it is electroless metal-plated (8), and after drying (9), the super Thin, lightweight conductive fibers (10).

Example 1:

Dissolve 15g of polyacrylonitrile (PAN) in 100g of dimethylformamide (DMF), and perform electrospinning at a high voltage of 10-30 kV to obtain ultrafine polyacrylonitrile fibers. After high-speed crushing and sieving, short fibers with a diameter of 0.01-1 μm and different lengths can be obtained. Sensitized by sensitizing solution (stannous chloride 10g/L, hydrochloric acid 50mL/L), activated by activation solution (palladium chloride 0.3g/L, hydrochloric acid 10g/L), and then in electroless copper plating solution (copper sulfate 10g/L) L, potassium sodium tartrate 40g/L, potassium hydroxide 20g/L, formaldehyde 15g/L) in copper-plated 30 minutes, through filtering and drying, promptly obtain the density and be 1.9g/ ^cm Copper-plated conductive fiber.

Example 2:

Dissolve 75g of polyacrylonitrile (PAN) in 500g of dimethylformamide (DMF), and perform electrospinning at a high voltage of 10-30 kV to obtain ultrafine polyacrylonitrile fibers. After high-speed crushing and sieving, short fibers with a diameter of 0.01-1 μm and different lengths can be obtained. Sensitized by sensitizing solution (stannous chloride 10g/L, hydrochloric acid 50mL/L), activated by activation solution (palladium chloride 0.3g/L, hydrochloric acid 10g/L), and then in electroless silver plating solution (silver nitrate 5g/L) L, potassium hydroxide 2g/L, invert sugar 0.7g/L) silver-plated 5 minutes, through filtering and drying, promptly obtain the silver-plated conductive fiber that density is 2g/ ^cm .

Claims (1)

1, a kind of preparation method of super fine light conductive fibre, it is characterized in that: comprising: (a) polyacrylonitrile is dissolved into polymer solution, prepare polymer fiber at voltage for the 10-40kV electrospinning, being ground into diameter then is 1nm-5 μ m, fibre length is at 10 μ m-1cm, and fibre density is 1.0-2.0g/cm ³The superthin light polymer fiber; (b) the superthin light polymer fiber is carried out silver-plated in the chemical plating fluid after sensitization, the activation processing, nickel, copper, gold or their alloy.

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