Nylon powder composition for 3d printing, and preparation method and application thereof

A method for preparing the high-viscosity nylon powder for 3D printing, wherein said method comprises the following steps of:

• (1) after homogeneously mixing 100 parts by weight of moderately low-viscosity nylon powder and 30-300 parts by weight of inorganic solid particles, adding the mixture into a reactor together;
• (2) purging the reactor with N2 gas;
• uniformly raising the reactor temperature up to 180-250° C. in 90-120 minutes, and keeping the temperature constant for 0.5-10 hours;
• (3) opening the discharge valve of the reactor to discharge into a container, cooling to a temperature of 25° C., and then separating nylon powder through a separator, i.e. giving high-viscosity nylon powder with a relative viscosity of 4-20.

A method for preparing the high molecular weight nylon powder composition for 3D printing, wherein said method comprises the following steps of:

• (1) based on the weight parts of lactam monomers, adding 100 parts by weight of lactam monomers into a container, and dehydrating under vacuum;
• (2) adding 0.005-1 parts by weight of an alkaline catalyst, and 0.1-1 parts by weight of an antioxidant, continuing to vacuum, raising the temperature up to 130-140° C., and keeping the reaction temperature constant for 10-30 minutes;
• (3) then, adding 0.01-2 parts by weight of an activator, stirring until mixing homogeneously, pouring into a container containing solid particles preheated to 150-170° C., after vigorously stirring and keeping the temperature constant for a while, cooling to room temperature;
• (4) by a separation method, obtaining a nylon powder composition with molecular weights in the range of 0.05-1.2 million and the particle sizes in the range of 20-100 micrometers.

A method for preparing the high molecular weight nylon powder composition for 3D printing, wherein said method comprises the following steps of:

• (1) adding 100-600 parts by weight of a high temperature inert solvent into a reactor, during stirring, adding 100 parts by weight of amide and 5-30 parts by weight of a molecular weight control agent, stirring until mixing homogeneously, adding 0.01-1 parts by weight of a molecular chain stabilizer, 0.02-0.8 parts by weight of a catalyst and 0.1-1 part by weight of an antioxidant, stirring until mixing homogeneously;
• (2) raising the reactor temperature in at least two steps, firstly uniformly raising the temperature from room temperature to 180-220° C. within a period of time, while maintaining the reactor pressure between 1.5-2 MPa;
• after that, heating the reactor, raising the temperature from 180-220° C. to 280-285° C. within a period of time, and reducing the reactor pressure to 1.01 MPa;
• after keeping the temperature between 270-285° C. for 30-60 minutes, vacuuming, reducing the reactor pressure to 0.3 Pa, and maintaining the pressure for 1-4 hours;
• (3) opening the discharge valve of the reactor to discharge into the container, vigorously stirring for 10-100 minutes, centrifugally separating, drying, obtaining a nylon powder composition with a relative viscosity of 4-20 and the particle sizes in the range of 20-100 micrometers.
• Preferably, in the step (1) in the above-mentioned method, 1-50 parts by weight of graphite is added simultaneously with amide.