Novel low-shrinkage amino moulding compound and preparation method thereof

Abstract

The invention relates to a formula and a preparation method of a novel low-shrinkage amino moulding compound. The novel low-shrinkage amino moulding compound comprises urea, formaldehyde, melamine, lubricant, dispersant, release agent, a curing agent system, dye, filler, cellulose and low shrinkage agent. The invention is characterized in that (1) the low shrinkage agent is water-soluble isocyanate elastomer; (2) the low shrinkage agent can be uniformly dispersed in a resin system and improve the surface glossiness of the moulding compound without influencing the coloring property of the dye or other performances of the moulding compound; and (3) a relatively small amount of the low shrinkage agent can meet the shrinkage requirement of the moulding compound. The preparation method of the moulding compound comprises the following steps: proportionally mixing and uniformly stirring the urea, the formaldehyde and the curing agent to prepare resin raw pulp; then transferring the raw pulp into a reaction kettle and adding the low shrinkage agent and other auxiliaries; and performing vacuum kneading and polymerization to prepare the amino moulding compound, wherein the forming shrinkage of the amino moulding compound is less than 0.6%, and the post shrinkage is less than 0.4%.

Description

technical field [0001] The invention relates to a novel low-shrinkage amino molding compound and a preparation method thereof. The shrinkage includes the mold shrinkage during the molding process and the post-shrinkage of the workpiece; the low-shrinkage amino molding compound is mainly used to prepare electrical panels and electrical housings that cooperate with metal devices, as well as high-grade sanitary ware. technical background [0002] Amino molding plastics are cheap raw materials, can be freely colored, have high surface hardness, have heat resistance, flame retardancy and excellent arc resistance characteristics, and are easy to achieve environmental protection in production, so they are widely used. Among them, 50% to 60% of amino molding plastics are used In the electrical and electronic fields, such as electrical switches, small electrical enclosures, sockets, circuit breakers and lighting appliances. [0003] The shrinkage rate of amino molding compound has a...

AI Technical Summary

Problems solved by technology

[0007] (3) The internal stress caused by shrinkage causes the workpiece to gradually sag from the surface to the interior in a geometric manner, and the depression is gradually transmitted from the surface to the center of the workpiece to release the internal stress to achieve balance. The result of this release of internal stress leads to large shrinkage, Dimensional loss of control, such as warping and deformation

However, this low-shrinkage agent is added in a large amount (at least 20wt%), so the cost is high, and only dark and specific color products can be produced, and it is not suitable for the advanced production process of amino molding compounds, that is, it is not suitable for vacuum Kneading process, because in the vacuum kneading process, the low shrinkage agent and the resin matrix cannot be mixed uniformly

[0010] In the British patent GB1438474A, the degree of methoxylation is increased, that is, the degree of polycondensation of polymethylol urea is increased to obtain an amino molding compound with a mold shrinkage rate of 0.6% and a post-shrinkage rate of 0.15%, but the performance of the amino molding compound is greatly sacrificed. Fluidity, prolonging the production cycle, and not suitable for vacuum kneading process