One-Piece HDPE Closure Device Eliminating Inner Liner
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Solution Overview
Problem
Current closure devices, such as soda bottle caps, require a two-part construction with a soft inner liner to balance strength and sealing properties, which is costly and inconvenient, and existing polymer blends do not adequately address the need for improved shrinkage and environmental stress crack resistance without a liner.
Innovation Solution
A high-density polyethylene composition comprising a high molecular weight ethylene alpha-olefin copolymer and a low molecular weight ethylene polymer, with specific density and melt index ranges, and the addition of 10% Octylphenoxy Poly (Ethyleneoxy) Ethanol, to create a one-piece closure device with improved shrinkage and environmental stress crack resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a two-part construction with a soft inner liner is used, then sealing properties are improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges the functions of the closure device body and the sealing liner into a single integrated polyethylene structure. The sealing ribs and soft sealing surfaces are formed as integral parts of the closure device, eliminating the need for separate liner components and their associated assembly operations.
Solution Approach 2:
The single-piece polyethylene closure device performs multiple functions simultaneously: it provides structural strength, creates sealing surfaces through integrated ribs, and offers shock absorption through its elastomeric properties. This multi-functional design replaces the need for separate specialized components.
2Reliability
If a two-part construction with a soft inner liner is used, then sealing properties are improved, but manufacturing cost increases
Solution Approach 1:
The patent merges the functions of the closure device body and the sealing liner into a single integrated polyethylene structure. The sealing ribs and soft sealing surfaces are formed as integral parts of the closure device, eliminating the need for separate liner components and their associated assembly operations.
3Device complexity
If a one-piece closure device without liner is used, then device complexity is reduced, but environmental stress crack resistance deteriorates
Solution Approach 1:
The patent modifies the polyethylene material parameters by selecting specific resin types (linear low-density polyethylene or metallocene polyethylene) with controlled density and molecular weight distributions. These parameter changes enable the single-piece construction to achieve both simplicity and environmental stress crack resistance.
Solution Approach 2:
The closure device utilizes the elastomeric properties of certain polyethylene compositions to create a effectively composite-like structure within a single material. The elastomeric characteristics provide shock absorption and stress distribution similar to multi-material constructions, achieving both simplicity and durability.
4Ease of operation
If a one-piece closure device without liner is used, then ease of operation is improved, but shrinkage properties deteriorate
Solution Approach 1:
The patent modifies the polyethylene material parameters by selecting specific resin types (linear low-density polyethylene or metallocene polyethylene) with controlled density and molecular weight distributions. These parameter changes enable the single-piece construction to achieve both simplicity and environmental stress crack resistance.
Data Source
AI summary
The instant invention is a high-density polyethylene composition, method of producing the same, closure devices made therefrom, and method of making such closure devices. The high-density polyethylene composition according to the present invention comprises (a) a first component comprising a high molecular weight ethylene alpha-olefin copolymer having a density in the range of 0.927 to 0.938 g/cm3, and a melt flow rate (I21) in the range of 4 to 10 g/10 minutes, and (b) a second component comprising a low molecular weight ethylene polymer having a density in the range of 0.960 to 0.975 g/cm3, and a melt index (I2) in the range of 100 to 1200 g/10 minutes; and wherein the high-density polyethylene composition has a melt index (I2) in the range of from 2 to 10 g/10 minutes, a density in the range of from 0.950 to 0.960 g/cm3, and a flow direction shrinkage to cross flow direction shrinkage ratio in the range of from 2 to 3.2, and an environmental stress crack resistance (ESCR) (F50) according to ASTM D-1693, condition B at 50 °C., and using 10 percent Branched Octylphenoxy Poly (Ethyleneoxy) Ethanol, in the range of equal to or greater than 50 hours.