Propylene Impact Copolymer for Smooth Corrugated Board Surfaces
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Solution Overview
Problem
Corrugated boards with polymeric twin wall panels face challenges in achieving high print quality due to surface pitting, especially at high line speeds, which makes them unsuitable for printed applications, particularly when the boards have thin walls.
Innovation Solution
A polymer composition comprising a propylene impact copolymer with a melt flow range of 1.5 to 3.5 g/10 min and a dispersed phase content of 5 to 30% by weight, combined with a processing aid such as fluoropolymers, is used to produce corrugated boards with improved smoothness and reduced pitting, allowing for higher line speeds without surface imperfections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high line speeds are used in corrugated board production, then productivity is improved, but surface quality deteriorates due to increased pitting
Solution Approach 1:
The patent applies parameter changes by carefully controlling the melt flow rate of the polypropylene resin within a specific range (1.5 to 3.5 g/10 min) and the dispersed phase content (5 to 30% by weight). These parameter optimizations allow the material to maintain proper flow characteristics at high line speeds while preventing surface pitting, thus resolving the contradiction between productivity and surface quality
Solution Approach 2:
The patent uses composite materials by incorporating a dispersed phase (comprising copolymer units from ethylene and alpha-olefins) within the propylene matrix. This composite structure modifies the rheological properties of the resin, enabling it to withstand high extrusion speeds without developing surface defects, thereby allowing high productivity while maintaining surface quality
2Manufacturing precision
If resins with higher melt flow rates are used to reduce pitting, then surface quality is improved, but printability deteriorates due to ink pooling in pits
Solution Approach 1:
The patent applies parameter changes by precisely controlling the melt flow rate within the range of 1.5 to 3.5 g/10 min. This optimized parameter range achieves the right balance: the resin flows sufficiently well during extrusion to minimize pitting and achieve smooth surfaces, while not being so fluid that it causes ink pooling during printing, thus resolving the contradiction between surface smoothness and print quality
3Weight of moving object
If thin wall thickness is used to reduce material usage, then weight is reduced, but surface quality deteriorates due to increased pitting
Solution Approach 1:
The patent applies parameter changes by optimizing the melt flow rate (1.5 to 3.5 g/10 min) and dispersed phase content (5 to 30% by weight) of the resin. These parameter adjustments enable the material to be extruded at high line speeds even for thin walls (less than 0.3 mm), preventing the development of pitting that would normally occur with thin-wall extrusion, thus resolving the contradiction between weight reduction and surface quality
Data Source
AI summary
The present invention relates to polymer compositions comprising a propylene impact copolymer and a processing aid, as well as corrugated boards made from such compositions. The impact copolymer has a melt flow range of from 1.5 to 3.5 g/10 min and a dispersed phase content of from 5 to 30% by weight. The dispersed phase of the impact copolymer has an ethylene content of from 30- to 70% by weight of the dispersed phase. The matrix phase of the impact copolymer is a propylene homopolymer or a random copolymer comprising units derived from propylene and a second copolymer selected from either ethylene or 1-butene wherein the units derived from the second copolymer comprise from 0 to 5% by weight of the dispersed phase.