Compartmentalized Polymer Chips for Slower Crystallization

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Solution Overview

Problem

In injection molding, combining postconsumer recycle polyester with virgin polyester in a homogeneous blend results in a faster crystallization rate, increasing the injection molding cycle time, and there is a need for a slower crystallization rate and more even Intrinsic Viscosity (I.V.) distribution across the chip to reduce molecular weight drop and energy consumption.

Innovation Solution

A compartmentalized chip with a first compartment of a first crystallizable thermoplastic polymer and a second compartment of a second crystallizable thermoplastic polymer, where the second compartment is located between the centroid and the first compartment, with the second polymer having a higher melt viscosity and similar chemical structure, allowing for slower crystallization and reduced I.V. gradient.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If postconsumer recycle polyester and virgin polyester are combined in a homogeneous blend, then material combination is achieved, but the crystallization rate increases (crystallization half time decreases)

Engineering Contradiction:

Improvematerial combinationVSAvoidcrystallization half time

Core Design Contradiction:

Adaptability or versatilityVSDuration of action of moving object

Solution Approach 1:

The chip is divided into two distinct compartments: a first compartment containing virgin polyester and a second compartment containing postconsumer recycled polyester. This segmentation prevents the materials from mixing and crystallizing together, thereby maintaining the slower crystallization rate of the virgin polyester while still incorporating recycled material in the same chip structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the chip are assigned different material compositions with specific properties. The first compartment (virgin polyester) provides controlled crystallization behavior, while the second compartment (recycled polyester) provides material incorporation. The spatial arrangement ensures that the virgin polyester region dominates the crystallization process.

Inventive Principle:

Principle #3Local quality

2Adaptability or versatility

If materials are combined homogeneously, then material combination is achieved, but injection molding cycle time increases due to faster crystallization

Engineering Contradiction:

Improvematerial combinationVSAvoidinjection molding cycle time

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

By segmenting the chip into separate compartments, the virgin polyester in the first compartment controls the overall crystallization rate, preventing the accelerated crystallization that would occur with homogeneous mixing. This maintains shorter cycle times while still incorporating recycled polyester in the second compartment.

Inventive Principle:

Principle #1Segmentation

3Stability of the object's composition

If Intrinsic Viscosity (I.V.) distribution is more even across the chip, then molecular weight drop during extrusion is reduced, but manufacturing complexity increases

Engineering Contradiction:

ImproveI.V. distributionVSAvoidchip structure

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The chip is segmented into compartments with different I.V. values, but the overall structure remains relatively simple. The segmentation allows each compartment to maintain its own I.V. characteristics, preventing the I.V. gradient problems that occur in homogeneous blends during extrusion processing.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The chip functions as a composite structure with distinct material zones. Each compartment contains material with specific I.V. properties, and the composite structure as a whole provides improved extrusion stability compared to homogeneous blends, while maintaining manageable manufacturing complexity.

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 compartmentalized structure achieves a slower crystallization rate and reduced I.V. gradient, enabling earlier removal of parts from the mold, reducing cycle time, and lowering energy consumption in injection molding.

Implementation Method 1

the first crystallizable thermoplastic polymer and a second compartment that comprises a second crystallizable thermoplastic polymer

Methodology Applied

Scientific EffectCrystallization: Crystallisation

Implementation Method 2

the melt viscosity of the first crystallizable thermoplastic polymer is not the same as the melt viscosity of the second crystallizable thermoplastic polymer

Methodology Applied

Scientific EffectMelting: Melting

Data Source

PatentUS7981510B2Compartmentalized chips with polymers of different viscosities for improved processability

Publication Date: 2011.07.19 APG POLYTECH LLC

AI summary

Compartmentalized chips of at least two chemically similar crystallizable thermoplastic polymers each having a different intrinsic viscosity placed in separate zones are disclosed. These compartmentalized chips exhibit thermal characteristics that are different from the traditional technique of homogeneously combining the two materials into the chip. These compartmentalized chips in their amorphous, crystalline and solid phase polymerized forms exhibit a longer crystallization half time than the homogeneous mixture, thus permitting faster injection cycle times.