Polyamide Resin Composition Gel Prevention
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Solution Overview
Problem
Current methods for producing polyamide resin compositions are inadequate in preventing the formation of gels and burnt deposits during mold processing, leading to defects and reduced productivity, especially in polyamides with a diamine component like xylylenediamine, where gel production is more severe.
Innovation Solution
A polyamide resin composition comprising a diamine unit with 70 mol% or more of metaxylylenediamine and a dicarboxylic acid unit, combined with an alkali compound as a carboxylate of an alkali metal or alkaline earth metal, within specific concentration ranges, to inhibit gel and burnt deposit formation, along with a production process that includes polycondensation under the presence of a phosphorus atom-containing compound and subsequent addition of the alkali compound.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyamide is produced using conventional methods with heat stabilizers or antioxidants, then thermal degradation is reduced, but gels are produced due to excessive polymerization reaction
Solution Approach 1:
An alkali compound (such as sodium acetate, potassium acetate, sodium carbonate, or potassium carbonate) is introduced as a mediator to control the polymerization reaction. This compound regulates the reaction between carboxyl groups and amino groups, preventing excessive polymerization that leads to gel formation while maintaining thermal stability during processing
Solution Approach 2:
The invention changes the chemical parameter by adding a specific amount of alkali compound (0.01-5 wt% based on polyamide weight) to alter the reaction dynamics. This parameter adjustment controls the polymerization rate and end-group balance, preventing gel formation without sacrificing thermal stability
2Productivity
If polyamide resin stays in molding machine for long time during bottle molding, then production efficiency is maintained, but burnt deposits are generated and clog flow channels
Solution Approach 1:
The alkali compound is added in advance to the polyamide resin before molding, creating a protective chemical environment. This preliminary action prevents thermal degradation and burnt deposit formation during extended residence time in the molding machine, allowing continuous production without frequent cleaning interruptions
3Object-generated harmful factors
If gel removal equipment is used to remove gels from polyamide pellets, then gel content is reduced, but production cost and process complexity increase
Solution Approach 1:
Instead of removing gels after formation, the invention converts the approach by preventing gel formation in the first place through the addition of alkali compound. This transforms a post-processing removal problem into a preventive formulation solution, eliminating the need for complex gel removal equipment while achieving low gel content
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces gel and burnt deposit formation, resulting in a polyamide resin with improved color tone and reduced defects, enabling the production of high-quality multilayer molded articles with enhanced industrial value.
Implementation Method 1
a step in which diamine containing 70 mol% or more of metaxylylenediamine and dicarboxylic acid are subjected to polycondensation under the presence of a phosphorus atom-containing compound (B)
Implementation Method 2
an alkali compound (A) which is a carboxylate of an alkali metal or an alkaline earth metal... a step in which an alkali compound (A) is added to the polyamide (X)
Data Source
AI summary
The present invention relates to a polyamide resin composition comprising polyamide (X) comprising a diamine unit containing 70 mol% or more of a metaxylylenediamine unit and a dicarboxylic acid unit and an alkali compound (A), wherein the following equations (1) to (4) are satisfied: 10≤COOH-NH2≤80 0.32≤P<6.46 0.50≤M<17.00 2≤M/P≤3 wherein [COOH] represents a concentration (µeq/g) of a terminal carboxyl group in the polyamide (X); [NH2] represents a concentration (µeq/g) of a terminal amino group in the polyamide (X); P represents a mole concentration (µmol/g) of a phosphorus atom contained per g of the polyamide resin composition; and M represents a sum (µmol/g) of values obtained by multiplying a mole concentration of an alkali metal atom and a mole concentration of an alkaline earth metal atom each contained per g of the polyamide resin composition by valencies thereof respectively.