1. a preparation method of nano silicon-based powder for improving resin fluidity comprises the following specific steps:

(1) preparing modified nano powder: adding the nano powder into an organic solvent, performing ultrasonic dispersion, adding a silane coupling agent into a dispersion liquid for treatment, heating to 60-70 ℃, stirring for reaction for 6-12h, filtering, and drying to obtain treated nano powder;

(2) mixing the treated nano powder with polyethylene glycol, and stirring at 60-80 deg.C for 2-5h to obtain nano silicon-based powder.

2. The method of claim 1, wherein: the nano powder in the step (1) is nano silicon dioxide; the grain diameter of the nano powder is 30-100 nanometers.

3. The method of claim 1, wherein: the silane coupling agent in the step (1) is one or a mixture of KH550, KH560 and KH 570.

4. The method of claim 1, wherein: the organic solvent in the step (1) is ethanol or methanol.

5. The method of claim 1, wherein: in the step (1), the mass ratio of the nano powder to the organic solvent is 1: (5-15).

6. The method of claim 1, wherein: the adding mass of the silane coupling agent is 1-10% of the mass of the nano powder.

7. The method of claim 1, wherein: the molecular weight of the polyethylene glycol is 4000-10000.

8. The method of claim 1, wherein: the mass ratio of the treated nano powder to the polyethylene glycol in the step (2) is 1-5: 1.

Background

Resins are currently rapidly developing. However, the overall melt viscosity of the resin is higher. When large or complex articles are to be injection molded, high melt viscosities are disadvantageous and require elevated mold temperatures or back pressures to achieve, which increases energy consumption and process complexity. The above-mentioned operation means inevitably brings about the problem of degradation of the resin, and limits the application of the resin in many fields. Therefore, the development of an auxiliary agent capable of improving the fluidity of the resin is beneficial to the application and development of the resin.

Polyamide (PA) is a general name of high polymers containing amide groups in a main chain repeating unit of a macromolecule, and is a variety with the largest yield, the largest variety and the widest application in five engineering plastics. The wear-resistant self-lubricating grease has excellent mechanical strength, good wear-resistant self-lubricating property and chemical resistance, good low-temperature performance and easy processing and production, and is widely applied to the fields of household appliances, automobiles, electronics and electricians and the like. Engineering plastics, synthetic fibers, packaging materials and the like.

A simple way to improve the flowability of a polymer is to reduce the molecular mass. However, the reduction in molecular mass affects the mechanical properties and greatly limits the applications of the resin.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a method for preparing nano silicon-based powder for improving the flowability of resin.

The technical scheme of the invention is as follows: the nanometer powder is blended and doped into the resin, the fluidity of the resin can be increased, the composite material has excellent processing performance, the fluidity and the tensile strength are further improved,

the nano powder is formed by mixing nano silicon dioxide and polyethylene glycol, and the polyethylene glycol is a high molecular oligomer, has a low friction coefficient and has a good lubricating effect. The surface of the silicon dioxide is coated with a layer of polyethylene glycol and uniformly dispersed in the matrix, so that the effect of reducing the internal friction among polymer chains is achieved, and better fluidity is obtained. The resin-filled nano particles can block the movement of molecular chains and reduce the physical entanglement among the molecular chains, and on the other hand, because the resin-filled nano particles cannot radially migrate in the flowing process and the concentration of boundary layer particles is unchanged, the strong adhesion effect of a melt and a metal wall is weakened.

The specific technical scheme of the invention is as follows: a preparation method of nano silicon-based powder for improving resin fluidity comprises the following specific steps:

(1) preparing modified nano powder: adding the nano powder into an organic solvent, performing ultrasonic dispersion, adding a silane coupling agent into a dispersion liquid for treatment, heating to 60-70 ℃, stirring for reaction for 6-12h, filtering, and drying to obtain treated nano powder;

(2) mixing the treated nano powder with polyethylene glycol, and stirring at 60-80 deg.C for 2-5h to obtain nano silicon-based powder.

Preferably, the nano powder in the step (1) is nano silicon dioxide; the grain diameter of the nano powder is 30-100 nanometers.

Preferably, the silane coupling agent in the step (1) is one or a mixture of KH550, KH560 and KH 570. Preferably, the organic solvent in step (1) is ethanol or methanol.

In the step (1), the mass ratio of the nano powder to the organic solvent is 1: (5-15).

Preferably, the adding mass of the silane coupling agent is 1-10% of the mass of the nano powder. Preferably, the molecular weight of the polyethylene glycol is 4000-10000.

Preferably, the mass ratio of the treated nano powder to the polyethylene glycol in the step (2) is 1-5: 1.

Has the advantages that:

1. the preparation method of the nano powder is simple and has good application prospect.

2. The silane coupling agent is used for treating the surfaces of the nano powder particles, so that the interface bonding strength of the treated nano powder and resin is increased, the dispersibility of the particles in a resin matrix is better, and the improvement of the resin flowability is facilitated.

3. The nano powder is compounded with polyethylene glycol, so that a layer of polyethylene glycol is coated on the surface of silicon dioxide, and the silicon dioxide coating has the following effects:

(1) the polyethylene glycol has a low friction coefficient and a good lubricating effect, forms an interface in directional arrangement, reduces the friction resistance of the movement of high polymers, and accordingly forms an internal lubricating effect.

(2) Part of nano powder is easy to be separated out from the interior of the polymer to the surface in the processing process of the polymer, and a film is formed on the surface of a polymer melt and processing equipment and plays a role in external lubrication.

(3) The nano particles can block the movement of molecular chains and reduce the physical entanglement among the molecular chains.

Therefore, the nano powder prepared by the invention is added into resin, has the functions of internal lubrication and external lubrication, simultaneously has less physical entanglement, and improves the fluidity of the resin through multiple composite functions.

4. The addition of the nano powder increases the fluidity of the resin, so that the composite material has excellent processing performance, improves the mechanical property of the resin and is beneficial to high-efficiency industrial production.

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention. And (2) premixing the resin and the nano powder in a mixer, putting the mixture into a double-screw extruder, and carrying out melt extrusion and granulation to obtain the resin composition. Researches find that the prepared resin has low apparent viscosity under the melting condition, good fluidity and heat resistance, and good mechanical property, and can be used for occasions with high requirements on the size of injection molding products.

Example 1

Weighing nano silicon dioxide with the particle size of 30nm, adding the nano silicon dioxide into ethanol according to the mass ratio of 1:5, dispersing for 30min in ultrasound to obtain nano powder dispersion liquid, adding a silane coupling agent KH560 with the mass of 2% of that of the nano powder into the nano powder dispersion liquid, heating to 60 ℃, keeping the temperature, stirring, reacting for 12h, cooling to room temperature after reaction, filtering, collecting filter residues, putting the filter residues into an oven, and drying at the temperature of 80 ℃ for 10h to obtain treated nano silicon dioxide; mixing the treated nano silicon dioxide with polyethylene glycol with the molecular weight of 4000, wherein the mass ratio of the nano silicon dioxide to the polyethylene glycol is 5:1, stirring and reacting for 5 hours at the temperature of 60 ℃, and cooling to room temperature. Thus obtaining the nano powder for improving the fluidity of the resin.

Example 2

Weighing nano silicon dioxide with the particle size of 50nm, adding the nano silicon dioxide into methanol according to the mass ratio of 1:10, dispersing for 30min in ultrasound to obtain nano powder dispersion liquid, adding a silane coupling agent KH550 with the mass of 10% of that of the nano powder into the nano powder dispersion liquid, heating to 70 ℃, keeping the temperature, stirring, reacting for 6h, cooling to room temperature after the reaction, filtering, collecting filter residues, putting the filter residues into an oven, and drying for 10h at the temperature of 80 ℃ to obtain the treated nano silicon dioxide; mixing the treated nano silicon dioxide with polyethylene glycol with the molecular weight of 6000, wherein the mass ratio of the nano silicon dioxide to the polyethylene glycol is 3:1, stirring and reacting for 3 hours at 70 ℃, and cooling to room temperature. Thus obtaining the nano powder for improving the fluidity of the resin.

Example 3

Weighing nano silicon dioxide with the particle size of 100nm, adding the nano silicon dioxide into ethanol according to the mass ratio of 1:15, dispersing for 30min in ultrasound to obtain nano powder dispersion liquid, adding a silane coupling agent KH570 accounting for 5% of the mass of the nano powder into the nano powder dispersion liquid, heating to 65 ℃, keeping the temperature, stirring, reacting for 9h, cooling to room temperature after the reaction, filtering, collecting filter residues, putting the filter residues into an oven, and drying for 10h at the temperature of 80 ℃ to obtain treated nano montmorillonite; mixing the treated nano montmorillonite with polyethylene glycol with molecular weight of 10000, wherein the mass ratio of nano silicon dioxide to polyethylene glycol is 1:1, stirring and reacting for 2h at 80 ℃, and cooling to room temperature. Thus obtaining the nano powder for improving the fluidity of the resin.

Comparative formula (parts by weight): 100 parts of PA resin;

formula 1: 100 parts of PA resin, and 2 parts of nano powder for improving the fluidity of the resin prepared in example 1;

and (2) formula: 100 parts of PA resin, and 4 parts of nano powder for improving the fluidity of the resin prepared in example 2;

and (3) formula: 100 parts of PA resin, 6 parts of nano powder for improving the fluidity of the resin prepared in example 3;