Polyester Resin Composition for LED Reflectors

Solution Overview

Problem

Existing polyester resin compositions used in LED reflectors suffer from slow crystallization rates, poor moldability, and inadequate mechanical properties, which are exacerbated by the addition of excess additives intended to improve these traits.

Innovation Solution

A polyester resin composition incorporating a polymer of aromatic dicarboxylic acid and alicyclic diol with a trans/cis isomer ratio of 2.3 or more, combined with white pigments and inorganic fillers, to enhance crystallization rate, moldability, and mechanical properties such as flexural strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If highly heat-resistant polyester resins are used to withstand high temperatures, then heat resistance is improved, but crystallization rate becomes extremely slow

Engineering Contradiction:

Improveheat resistanceVSAvoidcrystallization rate

Core Design Contradiction:

TemperatureVSProductivity

Solution Approach 1:

The invention changes the chemical composition parameters of the polyester resin by incorporating specific cyclic diols (1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, cis-1,2-cyclohexanedimethanol) in controlled ratios to achieve both high heat resistance and improved crystallization rate. This compositional parameter adjustment allows the resin to crystallize faster while maintaining temperature withstand capability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite polyester resin system by combining multiple diol components with specific structural characteristics. The composite structure of the resin, incorporating different cyclic diols with specific trans/cis ratios, enables simultaneous achievement of fast crystallization and high heat resistance that neither component could achieve alone.

Inventive Principle:

Principle #40Composite materials

2Strength

If inorganic fillers and nucleating agents are added to improve crystallization rate and impact resistance, then mechanical properties are improved, but moldability and mechanical properties rapidly reduce when excess amount is used

Engineering Contradiction:

Improveimpact resistanceVSAvoidmoldability

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The invention extracts and eliminates the need for excessive inorganic fillers and nucleating agents by achieving the desired crystallization rate and mechanical properties through the molecular structure design of the polyester resin itself. The specific diol composition inherently provides fast crystallization without requiring large amounts of external additives.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention changes the fundamental approach from adding external additives to modifying the resin's own chemical parameters. By adjusting the diol composition ratios and trans/cis isomer ratios within specific ranges, the resin achieves improved crystallization and mechanical properties without the moldability degradation caused by excess inorganic fillers.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If additives are used to improve crystallization rate, then crystallization rate is improved, but mechanical properties deteriorate

Engineering Contradiction:

Improvecrystallization rateVSAvoidmechanical properties

Core Design Contradiction:

ProductivityVSStrength

Solution Approach 1:

The invention changes the chemical composition parameters of the polyester resin by incorporating specific cyclic diols (1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, cis-1,2-cyclohexanedimethanol) in controlled ratios to achieve both high heat resistance and improved crystallization rate. This compositional parameter adjustment allows the resin to crystallize faster while maintaining temperature withstand capability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite polyester resin system by combining multiple diol components with specific structural characteristics. The composite structure of the resin, incorporating different cyclic diols with specific trans/cis ratios, enables simultaneous achievement of fast crystallization and high heat resistance that neither component could achieve alone.

Inventive Principle:

Principle #40Composite materials

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 composition significantly reduces solidification time during injection molding, improves mechanical properties, and minimizes deformation, making it suitable for LED reflectors with enhanced stability and discoloration resistance.

Implementation Method 1

significantly reduce solidification time upon injection molding due to increased crystallization rate

Methodology Applied

Scientific EffectCrystallization: Crystallisation

Data Source

PatentUS10468568B2Polyester resin composition having improved mechanical properties and moldability

Publication Date: 2019.11.05 LOTTE CHEM CORP

AI summary

A polyester resin composition includes: (A) a polyester resin which includes a polymer of a dicarboxylic acid component including an aromatic dicarboxylic acid, for example but not limited to terephthalic acid, and a diol component including an alicyclic diol, for example but not limited to cyclohexanedimethanol, having a trans/cis isomer ratio of about 2.3 or more; (B) a white pigment; and (C) inorganic fillers. A molded article formed from the polyester resin composition can exhibit improved mechanical properties and moldability, and thus can be suitable for light emitting diode (LED) reflectors.