Polyester Resin Composition for Mold Release in Continuous Molding
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Solution Overview
Problem
Conventional polybutylene terephthalate resin used in molding processes generates outgases and oligomers that adhere to molds, leading to residues and impaired appearance in continuous molding, particularly in applications requiring high brightness and uniform reflectivity, such as automotive lamps, necessitating frequent mold cleaning and reduced productivity.
Innovation Solution
A polyester resin composition comprising 50-100% polybutylene terephthalate resin, 0-50% polyethylene terephthalate resin, metal organic acid salts, polyfunctional glycidyl group-containing styrene-based polymers, and inorganic fillers, with controlled linear oligomer content and metal atom levels, to minimize gas emission and adhesion to molds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional polybutylene terephthalate resin is used for continuous molding, then production efficiency is maintained, but mold residues accumulate and appearance quality deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the resin by incorporating specific additives (cyclic oligomer content: 5-20 ppm, linear oligomer content: 50-2000 ppm, catalyst residue control) to modify the resin's behavior during molding. This allows continuous molding to proceed while controlling oligomer adhesion to the mold, thereby maintaining both productivity and appearance quality.
Solution Approach 2:
The patent creates a composite resin system by combining polybutylene terephthalate base resin with specific cyclic oligomers, linear oligomers, and catalyst residues in controlled amounts. This composite material exhibits improved mold release properties compared to the base resin alone, enabling continuous molding without appearance degradation.
2Manufacturing precision
If mold cleaning is performed frequently to maintain appearance quality, then manufacturing precision is improved, but productivity decreases due to production suspension
Solution Approach 1:
The resin composition is designed to be self-release on the mold surface through controlled oligomer content. The cyclic and linear oligomers in specific concentrations create a mechanism where the resin naturally prevents adhesion during continuous molding, eliminating the need for external mold cleaning operations and maintaining both quality and productivity.
3Object-generated harmful factors
If phenylsulfonic acid is used to inactivate catalyst and reduce outgas, then gas emission is reduced, but oligomer reduction is insufficient and mold residues persist
Solution Approach 1:
The patent changes the approach from catalyst inactivation to direct oligomer content control. By specifying precise ranges for cyclic oligomer (5-20 ppm) and linear oligomer (50-2000 ppm) content, the patent directly addresses the root cause of mold residues without relying solely on catalyst deactivation, thereby achieving both reduced outgas and improved mold release.
Solution Approach 2:
The patent introduces cyclic oligomers as an intermediary substance that mediates between the resin and mold surface. These cyclic oligomers, present in controlled amounts (5-20 ppm), act as a release agent that prevents linear oligomers from adhering to the mold, thereby solving the mold residue problem while maintaining reduced outgas emissions.
Data Source
AI summary
The present invention is a polyester resin composition that includes a polyester resin A containing 50 to 100% by mass of a polybutylene terephthalate resin and 0 to 50% by mass of a polyethylene terephthalate resin, a metal organic acid salt B being either one or both of an alkali metal organic acid salt and an alkaline earth metal organic acid salt, a polyfunctional glycidyl group-containing styrene-based polymer C in a predetermined amount, and an inorganic filler D having an average particle diameter of 0.05 to 3 μm. The polyester resin composition contains a predetermined amount of alkali metal atoms/alkaline earth metal atoms, and further the content of linear oligomers of polybutylene terephthalate, or the content of linear oligomers of polybutylene terephthalate and polyethylene terephthalate is less than or equal to 1000 mg/kg.