阅读说明：本技术 一种低收缩率氨基模塑料 (Amino molding plastic with low shrinkage ) 是由 杨小燕 杨桂明 苏建华 于 2018-06-21 设计创作，主要内容包括：本发明提供一种低收缩率氨基模塑料,包括以下重量百分比的成分：尿素：10-20％、甲醛：25-40％、三聚氰胺：5-8％、润滑剂1-2％、分散剂3-8％、乌洛托品：0.2-1％、脱模剂1-2％、固化剂：3-8％、颜料0.5-2％、填料1-2％、纤维素1-2％、低收缩剂3-5％。本发明选用水溶性异氰酸酯基弹性体为低收缩剂,适用于制备氨基模塑料液相体系以及真空捏合工艺,不影响氨基模塑料生产工艺和生产周期,其成膜物无色透明,易于掺色,富有良好的弹性形变。(The invention provides a low-shrinkage amino molding compound which comprises the following components in percentage by weight: urea: 10-20%, formaldehyde: 25-40%, melamine: 5-8%, 1-2% of lubricant, 3-8% of dispersant, and urotropine: 0.2-1%, release agent 1-2%, curing agent: 3-8 percent of pigment, 0.5-2 percent of pigment, 1-2 percent of filler, 1-2 percent of cellulose and 3-5 percent of low shrinkage agent. The invention selects the water-soluble isocyanate-based elastomer as the low shrinking agent, is suitable for preparing an amino molding material liquid phase system and a vacuum kneading process, does not influence the production process and the production period of the amino molding compound, and has colorless and transparent film-forming substances, easy color mixing and good elastic deformation.)

1. The low-shrinkage amino molding compound is characterized by comprising the following components in percentage by weight:

urea: 10-20%, formaldehyde: 25-40%, melamine: 5-8%, 1-2% of lubricant, 3-8% of dispersant, and urotropine: 0.2-1%, release agent 1-2%, curing agent: 3-8 percent of pigment, 0.5-2 percent of pigment, 1-2 percent of filler, 1-2 percent of cellulose and 3-5 percent of low shrinkage agent.

2. The low shrinkage amino molding compound as claimed in claim 1, wherein the curing agent is oxalic acid or ammonium tartrate.

3. The low shrinkage amino molding compound as claimed in claim 1, wherein the low shrinkage agent is a water-soluble isocyanate-based elastomer.

4. The low shrinkage amino molding compound of claim 3, wherein said lubricant is zinc stearate.

5. The amino molding compound with low shrinkage rate as claimed in claim 1, wherein the filler is inorganic powder selected from wood powder, carbonate, sulfate, silicate, titanate, or their mixture.

Technical Field

The invention relates to the technical field of amino molding compounds, in particular to a low-shrinkage amino molding compound.

Background

The amino molding compound is prepared by kneading amino resin, alpha-cellulose, curing agent and other assistants, and through crushing and ball milling, and has the advantages of excellent electric arc resistance, high material hardness, high scratch resistance, low cost, etc. and may be used widely in electric appliance, daily use article, tableware, etc.

The shrinkage rate of the amino molding compound has very important influence on the appearance of electrical products, the connection and matching of the products and metal screws and the like, the service life and the like. The product generates warping deformation due to large shrinkage rate, cracking is generated at the metal connection matching part, the service life is greatly shortened, and even the electric appliance shell can not be connected. The cause of the large shrinkage produced by the amino molding compound is:

(1) crosslinking curing during molding causes the polymer molecules to pack tightly and increase in density, resulting in resin shrinkage.

(2) The release of small molecule gases (such as water vapor, ammonia gas, formaldehyde gas and the like) generated in the curing and crosslinking process and the contraction of the resin or molding plastic products caused by thermal expansion and contraction.

(3) The internal stresses caused by shrinkage cause the part to become recessed geometrically from the surface towards the interior, the recesses being progressively transferred from the surface to the centre of the part to allow the internal stresses to be released to equilibrium, which results in large shrinkage and dimensional runaway, such as warpage and distortion.

At present, the mold shrinkage rate and the post shrinkage rate of the amino molding compound are 0.8-1.1%, but for products such as large-size electrical panels, shells and the like, the mold shrinkage rate of the amino molding compound is required to be less than 0.6%, and the post shrinkage rate is required to be less than 0.45%, so that the preparation of the low-shrinkage amino molding compound has great significance for widening the application range of the amino molding compound.

Disclosure of Invention

The purpose of the invention is as follows: aiming at the defects in the prior art, the invention provides the amino molding compound with low shrinkage rate, which can improve the shrinkage rate of the amino molding compound.

The technical scheme is as follows: in order to achieve the purpose, the invention adopts the following technical scheme:

the low-shrinkage amino molding compound comprises the following components in percentage by weight:

urea: 10-20%, formaldehyde: 25-40%, melamine: 5-8%, 1-2% of lubricant, 3-8% of dispersant, and urotropine: 0.2-1%, release agent 1-2%, curing agent: 3-8 percent of pigment, 0.5-2 percent of pigment, 1-2 percent of filler, 1-2 percent of cellulose and 3-5 percent of low shrinkage agent.

Preferably, the curing agent is oxalic acid or ammonium tartrate.

Preferably, the low profile agent is an isocyanate-based elastomer.

Preferably, the lubricant is zinc stearate.

Preferably, the filler is inorganic powder and is selected from one of wood powder, carbonate, sulfate, silicate and titanate or a mixture thereof.

Has the advantages that: the invention selects the water-soluble isocyanate-based elastomer as the low shrinking agent, is suitable for preparing an amino molding material liquid phase system and a vacuum kneading process, does not influence the production process and the production period of the amino molding compound, and has colorless and transparent film-forming substances, easy color mixing and good elastic deformation.

Detailed Description

The present invention will be further explained with reference to examples.

Example 1: mixing urea: 25 parts of formaldehyde: adding 50 parts of the mixture into a reaction kettle, adjusting the pH value to 8.5-9 by using NaOH, and then adding melamine: 0.3 portion, and refluxing and hydroxymethylating for 30-40min at 85-90 ℃. Then reducing the temperature to 50-70 ℃, preserving the heat for 30min, cooling to 20-30 ℃, and adjusting the pH value to 9 by NaOH. To the resin obtained above were added 0.2 part of a lubricant, 0.3 part of a dispersant, urotropin: 0.5 part, 0.5 part of release agent, and curing agent: 1.5 parts of pigment, 0.5 part of filler, 2 parts of filler, 15 parts of cellulose and 2 parts of low shrinkage agent, combining, drying, grinding into 100-mesh fine powder, and extruding and crushing into a particle sample by using an extruder.

Example 2: mixing urea: 30 parts of formaldehyde: adding 45 parts of the mixture into a reaction kettle, adjusting the pH value to 8.5-9 by using NaOH, and then adding melamine: 0.2 portion, and refluxing and hydroxymethylating for 30-40min at 85-90 ℃. Then reducing the temperature to 50-70 ℃, preserving the heat for 30min, cooling to 20-30 ℃, and adjusting the pH value to 9 by NaOH. To the resin obtained above were added 0.4 part of a lubricant, 0.2 part of a dispersant, urotropin: 0.2 part, 0.3 part of release agent, and curing agent: 1 part of pigment, 1 part of filler, 10 parts of cellulose and 2 parts of low shrinkage agent, combining, drying, grinding into fine powder of 100 meshes, and extruding and crushing into granules by an extruder.

Example 3: mixing urea: 35 parts of formaldehyde: adding 55 parts of the mixture into a reaction kettle, adjusting the pH value to 8.5-9 by using NaOH, and then adding melamine: 1 part, and refluxing and hydroxymethylating for 30-40min at 85-90 ℃. Then reducing the temperature to 50-70 ℃, preserving the heat for 30min, cooling to 20-30 ℃, and adjusting the pH value to 9 by NaOH. To the resin obtained above were added 0.5 part of a lubricant, 0.5 part of a dispersant, urotropin: 0.5 part, 0.5 part of release agent, and curing agent: 1.5 parts of pigment, 0.5 part of filler, 2 parts of filler, 15 parts of cellulose and 2 parts of low shrinkage agent, combining, drying, grinding into 100-mesh fine powder, and extruding and crushing into a particle sample by using an extruder.

The shrinkage rates of the examples 1, 2 and 3 are analyzed by a Brabender rheometer, and the bending strength and the impact strength of the amino molding compound can be improved by selecting a water-soluble isocyanate-based elastomer as a low shrinkage agent; the surface gloss of the material can be improved, and the colorability of the pigment is not influenced; can improve the fluidity of the amino molding compound.

The present invention will be better understood from the following examples. However, those skilled in the art will readily appreciate that the specific material ratios, process conditions and results thereof described in the examples are illustrative only and should not be taken as limiting the invention as detailed in the claims.