Diaphragm composite material and preparation method thereof

1. A method for preparing a diaphragm composite material, comprising the following steps of:

step S 1 : preparing a polyethylene naphthalate film layer, comprising:

step S 1 . 1 : weighing materials comprising the following components in parts by mass: 70-80 parts of polyethylene naphthalate, 10-15 parts of nylon 6, 10-15 parts of fibrous filler, 1-2 parts of silane coupling agent and 0.5-1 parts of lubricant; and adding the weighed materials to a mixer for mixing under stirring to form a mixture;

step S 1 . 2 : adding ethanol to the mixture under stirring, then adding the mixture to an extruder, melt-blending, and granulating by extrusion; wherein a mass ratio of the ethanol to the mixture is 1: (4-6); and

step S 1 . 3 : drying particles extruded in the step S 1 . 2 and then adding the dried particles to an injection molding machine for injection molding to obtain a long-chain branched polyethylene naphthalate film layer;

step S 2 : preparing an aerogel layer material, comprising: adding the following materials in parts by mass to a micro-powder stirrer: 20-30 parts of propylene oxide, 80-130 parts of acetic acid, 50-70 parts of polyethylene glycol 600, and 10-30 parts of formamide, stirring for 5-10 min to provide a solution, and adjusting a temperature of the solution to 5-8° C.; then adding 5-20 parts of silicon oxide-silicon nitride composite aerogel, 20-30 parts of toluene diisocyanate trimer, and 10-15 parts of isophorone diisocyanate trimer, and continuing stirring for 5-10 min; and then performing air classification and collecting aerogel layer material powder passing through a 8000-mesh filter screen to provide the aerogel layer material; wherein a rotating speed of the micro-powder stirrer is 800-1000 r/min;

step S 3 : delivering the aerogel layer material powder collected in the step S 2 by compressed air, filtering and drying, and then entering a 800-1000° C. high-temperature vaporizing chamber, forming an ultrasonic airflow through a nozzle to inject into a surface of a side of an aluminum-plated film layer where aluminum is plated, and continuously irradiating the surface of the side with a plasma beam to form the aluminum-plated film layer with an aerogel layer attached to one side; and

step S 4 : uniformly coating a surface of the polyethylene naphthalate film layer with an elastic adhesive, and then bonding and pressing the surface of the aluminum-plated film layer at one side where the aerogel layer is not attached, the bonding having a temperature of 60-80° C., and a pressure of 120-160 MPa, and then curing at 35-50° C. for 60-75 h after completion of the bonding, to obtain the diaphragm composite material.

2. The method for preparing the diaphragm composite material according to claim 1 , wherein in the step S 3 , a plasma beam voltage of the plasma beam is 1200-1450 kV, and an irradiation time is 2-5 s.

3. The method for preparing the diaphragm composite material according to claim 1 , wherein preparing the silicon oxide-silicon nitride composite aerogel in the step S 2 comprises:

step S 2 . 1 : fully mixing the following materials in parts by mass: 1 part of tetraethoxysilane, 2.5-4 parts of anhydrous ethanol and 2.5-4 parts of water under stirring, adjusting a pH value to 4 through diluted hydrochloric acid, and reacting to form a sol A;

step S 2 . 2 : adjusting the pH value of the sol A to 7 through ammonia water, adding 1-1.5 parts by mass of silicon nitride under stirring, and standing at room temperature to form a gel B;

step S 2 . 3 : aging the gel B at room temperature for 24 h, then immersing the gel B in anhydrous ethanol at room temperature, and continuing aging for 48 h;

step 2 . 4 : soaking the aged gel B in an n-hexane solution containing 10% of trimethylsilane for 6 h, and performing hydrophobization treatment; and

step 2 . 5 : drying the gel B treated in the step S 2 . 4 at 80-100° C. under normal pressure; treating the dried gel B in a muffle furnace at 450-500° C. for 4-6 h, and crushing to obtain the silicon oxide-silicon nitride composite aerogel.

4. The method for preparing the diaphragm composite material according to claim 3 , wherein the silicon nitride in the step S 2 . 2 has an average particle size of 30-50 nm.