Polyamide Resin Gel Control via Alkali and Phosphorus Additives
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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, particularly 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 and a phosphorus atom-containing compound, where the alkali compound is added after polymerization to inhibit gel formation and burnt deposits, and a multilayer molded article is produced using this composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If polyamide is used for transparent and thin molded products requiring high-level mold processing, then the appearance quality is improved, but foreign matters are very highly likely to damage the performances and bring about inferior appearance and increased defect rates
Solution Approach 1:
The invention removes foreign matters (gels, burnt deposits, powders, thin films) from the polyamide resin before the molding process through filtration and separation equipment. This preliminary removal prevents foreign matters from damaging the transparent thin molded products during high-level mold processing, thereby maintaining appearance quality without compromising manufacturing precision
Solution Approach 2:
The invention extracts and removes harmful foreign matters (gels, burnt deposits, powders, thin films) from the polyamide resin composition through various separation equipments including filters and optical sensor-based screening equipment. This extraction process eliminates the source of defects before molding, preventing foreign matter damage to transparent thin products
2Object-generated harmful factors
If thermal history is reduced to the utmost in the production step to obtain polyamide containing less gel, then gel production is reduced, but some additives show catalytic effect to amidation reaction and expedite excessively polymerization reaction to bring about an increase in gels
Solution Approach 1:
The invention changes the chemical parameters by adding specific additives (alkali compounds, phosphorus compounds, carboxylic acid compounds) that modify the polymerization reaction characteristics. These additives suppress excessive polymerization reaction and gel formation by controlling the reaction kinetics, allowing thermal history to be reduced while maintaining reliable polymerization control
Solution Approach 2:
The invention introduces intermediary substances (alkali compounds, phosphorus compounds, carboxylic acid compounds) that mediate the polymerization reaction. These intermediaries suppress the catalytic effect of additives on amidation reaction, preventing excessive polymerization and gel formation while maintaining controlled reaction progression
3Productivity
If polyamide resin stays in an inside of a molding machine for a long time in molding a bottle, then the stable production is maintained, but degraded matter of the resin is turned into burnt deposits, and they are mixed in the product to deteriorate a yield or clog flow channels
Solution Approach 1:
The invention applies preliminary anti-action by adding heat stabilizers and antioxidants to the polyamide resin composition before molding. These additives prevent thermal degradation and burnt deposit formation during prolonged residence time in the molding machine, allowing stable production to continue without generating harmful burnt deposits that would deteriorate yield or clog flow channels
Solution Approach 2:
The invention uses sacrificial additives (heat stabilizers, antioxidants) that consume themselves during prolonged residence time to protect the main polyamide resin from degradation. These short-living protective substances prevent burnt deposit formation, allowing stable production to continue while the additives are consumed rather than allowing resin degradation
4Object-generated harmful factors
If various separating equipments are used to remove foreign matters, then the removing effects are ensured, but the device complexity increases
Solution Approach 1:
The invention merges multiple separation functions into an integrated purification system that combines filtration for powders and thin films with optical sensor-based screening for yellowed matters and carbides. This unified approach ensures comprehensive foreign matter removal while reducing overall device complexity compared to separate independent systems
Solution Approach 2:
The invention employs a multi-functional purification system that handles different types of foreign matters (gels, burnt deposits, powders, thin films, yellowed matters, carbides) through a single integrated process. The system uses both mechanical filtration and optical detection capabilities in one unit, ensuring comprehensive removal while simplifying the overall equipment configuration
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 composition with improved color tone and reduced defects, enabling the production of high-quality multilayer molded articles with enhanced industrial value.
Implementation Method 1
the molecules are damaged (the polymer molecules are degraded by radicals generated) during polymerization and mold processing to bring about abnormal reactions
Implementation Method 2
a thermal history has to be reduced to the utmost in the production step in order to obtain polyamide containing less gel, and measurements such as setting a balance of terminal group concentrations and adding a heat stabilizer or an antioxidant are carried out
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 (3) are satisfied; 0.03≤P<0.32 2.2≤M≤26.1 5<M/P≤200 wherein 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.