Polyamide Granule Cooling to Prevent Yellowing

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Solution Overview

Problem

The existing methods for producing polyamide granules often require costly and energy-intensive drying processes in inert gas environments to achieve low water content, which can lead to degradation and yellowing of the polyamide, affecting mechanical properties and usage performance.

Innovation Solution

A process involving extrusion, cooling with a water-based coolant, rapid cutting, and subsequent cooling of polyamide granules to achieve low water content without the need for drying or heating in an inert medium, utilizing a combination of steps to minimize water absorption and prevent yellowing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If polyamide granules are produced by conventional extrusion and cooling with water, then granules are obtained efficiently, but the water content becomes too high causing molecular weight reduction and mechanical property degradation

Engineering Contradiction:

Improvegranule production efficiencyVSAvoidmechanical properties of polyamide

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The invention applies preliminary action by rapidly cooling the extruded polyamide material immediately after extrusion to reduce its temperature and water content before the granules are formed and handled. This preliminary cooling action prevents water absorption during subsequent handling and processing steps, thereby maintaining mechanical properties without requiring additional drying steps.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention implements the skipping principle by rushing through the cooling process with a maximum contact time of 10 seconds between the extruded material and cooling water, followed by rapid granulation. This quick processing sequence skips the conventional lengthy drying steps, achieving low water content granules directly without prolonged exposure to water or high-temperature drying that could degrade the polyamide.

Inventive Principle:

Principle #21Skipping (Rushing through)

2Quantity of substance

If drying is carried out at high temperature for several hours to reduce water content, then low water content granules are obtained, but energy consumption and production costs increase significantly

Engineering Contradiction:

Improvewater content in granulesVSAvoidenergy consumption for drying

Core Design Contradiction:

Quantity of substanceVSUse of energy by moving object

Solution Approach 1:

The invention applies inversion by reversing the conventional sequence: instead of producing granules first and then drying them at high temperature, the method cools the extruded material rapidly immediately after extrusion and performs granulation on the cooled material. This inverted approach achieves low water content without requiring energy-intensive high-temperature drying operations.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The invention utilizes parameter changes by controlling the temperature of the cooling water and the duration of contact between the extruded material and cooling water (maximum 10 seconds). By optimizing these parameters, the process achieves rapid cooling that reduces water content in the granules without requiring subsequent high-temperature drying, thereby significantly reducing energy consumption.

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If drying is performed in an oxygen-free inert gas environment to prevent yellowing, then granule quality is maintained, but process complexity and production costs increase

Engineering Contradiction:

Improveyellowing and oxidation of granulesVSAvoiddrying system complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The invention extracts the harmful drying step from the process by achieving low water content granules through rapid cooling and immediate granulation, eliminating the need for subsequent drying operations in inert gas environments. This removal of the drying step simplifies the equipment and eliminates the complexity associated with oxygen-free environment maintenance while still preventing yellowing and oxidation.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention applies self-service by using the cooling water itself to achieve the dual function of cooling the extruded material and reducing water content in the granules. The process relies on the inherent properties of the cooling step rather than requiring additional inert gas drying systems, thereby simplifying the overall process equipment while maintaining granule quality.

Inventive Principle:

Principle #25Self-service

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

This process efficiently produces polyamide granules with low water content and maintains mechanical properties, reducing energy expenditure and production costs while preventing yellowing and degradation.

Implementation Method 1

cooling the material obtained using a coolant containing water

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Data Source

PatentEP2771159B1Method for preparing polyamide granules

Publication Date: 2019.01.23 RHODIA OPERATIONS SAS

AI summary

The present invention relates to a method for preparing polyamide granules. This method comprises, in particular, steps of extruding the polymer, cooling and cutting the extruded material, and a step of cooling the granules. The method of the invention is simple and quick to implement.