Preparation method for electromagnetic wave shield composite material using copper- and nickel-plated carbon fiber prepared by electroless and electrolytic continuous processes, and electromagnetic wave shield composite material
The present invention relates to a preparation method for an electromagnetic wave shield composite material and the electromagnetic wave shield composite material prepared by the method. The present invention uses a highly conductive carbon fiber prepared by electroless and electrolytic continuous processes, and thus is suitable for an EMI shield due to having an excellent conductivity and low surface resistance, and is capable of providing the electromagnetic wave shield composite material having an excellent productivity and economic value. Furthermore, the electromagnetic wave shield composite material of the present invention can be used for blocking electromagnetic waves by being inserted into a cell phone cover and a cell phone pouch, and can also be applied to a bracket for protecting an LCD of a portable display product.
1. A method for preparing an electromagnetic shielding composite comprising:
(a) copper plating a carbon fiber by passing the carbon fiber through an electroless plating liquid,
wherein the electroless plating liquid contains 2.5-5.5 g/L Cu ions, 20-55 g/L EDTA, 2.5-4.5 g/L formalin, 2-6 g/L triethanolamine (TEA), 25% NaOH 8-12 mL/L and 0.008-0.15 g/L 2,2′-bipyridine on the basis of the volume of pure water,
wherein the electroless plating liquid has pH 12-13 and a temperature of 36-45° C.;
(b) nickel plating the copper-plated carbon fiber by passing the copper-plated carbon fiber through an electrolytic plating liquid,
wherein the electrolytic plating liquid contains 280-320 g/L Ni(NH 2 SO 3 ) 2 , 15-25 g/L NiCl 2 and 35-45 g/L H 3 BO 3 , and
wherein the electrolytic plating liquid has pH 4.0-4.2 and a temperature of 50-60° C.;
(c) mixing 50-90 wt % of a thermosetting resin and 10-50 wt % of the copper- and nickel-plated carbon fibers; and
(d) performing discharge molding on the product in step (c) to obtain an electromagnetic shielding composite,
wherein the copper- and nickel-plated carbon fiber in step (c) has a chopped shape with a length of 3 mm to 500 mm.
2. The method of claim 1 , wherein the thermosetting resin in step (a) is at least one thermosetting resin selected from the group consisting of polyurethane-based resins, epoxy-based resins, phenol-based resins, urea resins, melamine resins and unsaturated polyester-based resins.
3. The method of claim 1 , wherein the discharge molding in step (d) further comprises:
(d-1) discharging the product in step into a mold or a conveyor;
(d-2) setting the discharged product in step (d-1); and
(d-3) releasing the set product in step (d-2).
4. The method of claim 3 , wherein the setting in step (d-2) is performed by applying heat, pressure or UV.
5. The method of claim 1 , wherein the product in step (c) further comprises a conductive material selected from the group consisting of ferrite, graphite and metal-plated graphite.
6. The method of claim 5 , wherein the product in step (c) comprises 40-89.5 wt % of the thermosetting resin, 10-50 wt % of the copper- and nickel-plated carbon fibers and 0.5-10 wt % of the conductive material.
7. The method of claim 5 , wherein a metal of the metal-plated graphite is at least one metal selected from the group consisting of aluminum, iron, chromium, stainless, copper, nickel, black nickel, silver, gold, platinum, palladium, tin, cobalt, and an alloy of two or more thereof.
8. The method of claim 1 , wherein the mixing in step (c) is performed by mixing the thermosetting resin and the copper- and nickel-plated carbon fibers with at least one additive selected from the group consisting of a carbon filler, a flame retardant, a plasticizer, a coupling agent, a heat stabilizer, a light stabilizer, an inorganic filler, a releasing agent, a dispersing agent, an anti-dropping agent and a weathering stabilizer.