Polyethylene Caps With UV Stabilizer and Erucamide
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Solution Overview
Problem
High density polyethylene caps and closures face challenges in achieving a balance between slip properties and organoleptic properties, with existing solutions either compromising on slip performance or stability when exposed to UV and sun light.
Innovation Solution
A resin composition comprising polyethylene with a density of at least 0.940 g/cm3, erucamide, and an ultraviolet absorber from the hydroxyphenylbenzotriazole class, specifically blended and processed through extrusion followed by injection moulding or compression moulding to enhance both slip and organoleptic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If erucamide is added to improve slip properties, then removal torque is reduced, but organoleptic properties deteriorate due to degradation and volatile generation under UV exposure
Solution Approach 1:
A hindered amine light stabilizer (HALS) is introduced as an intermediary substance to protect erucamide from UV degradation. The HALS acts as a mediator that absorbs harmful UV energy and prevents it from decomposing the erucamide, thereby maintaining both the slip properties (low removal torque) and organoleptic properties of the cap closure.
Solution Approach 2:
The hindered amine light stabilizer is added in advance to the polyethylene composition to provide preemptive protection against UV-induced degradation of erucamide. This prior cushioning approach prevents the formation of volatile compounds that would otherwise compromise organoleptic properties, allowing erucamide to maintain its slip-enhancing function without degradation.
2Productivity
If high density polyethylene is used to reduce cap weight, then productivity and cost are improved, but stress crack resistance and organoleptic properties are compromised
Solution Approach 1:
The density parameter of the polyethylene is optimized to at least 0.940 g/cm³, which provides an optimal balance between weight reduction and mechanical performance. This specific density threshold ensures sufficient stress crack resistance while achieving the desired weight reduction for improved productivity and cost efficiency.
Solution Approach 2:
The invention creates a composite material system consisting of high density polyethylene, erucamide, and hindered amine light stabilizer. This composite approach combines materials with complementary properties: the HDPE provides structural integrity and stress crack resistance, while erucamide provides slip properties and the HALS provides UV stabilization, achieving overall performance superior to individual components.
3Ease of operation
If erucamide is used for slip properties, then application and removal torques are improved, but stability under UV exposure deteriorates
Solution Approach 1:
The hindered amine light stabilizer serves as an intermediary protective layer between UV radiation and erucamide molecules. It absorbs and dissipates UV energy through hydrogen bonding and radical scavenging mechanisms, preventing direct UV-induced decomposition of erucamide and maintaining its molecular stability and slip-enhancing properties.
Solution Approach 2:
The invention converts the potentially harmful UV exposure into a beneficial protective mechanism. The hindered amine light stabilizer is specifically designed to absorb UV energy and transform it into harmless forms through hydrogen bonding with incoming UV photons and radical scavenging, thereby protecting the erucamide from degradation while maintaining its functional benefits.
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 solution provides caps and closures with improved application/removal torques and acceptable organoleptic properties, maintaining environmental stress crack resistance and stability under UV and sun light exposure.
Implementation Method 1
at least 700 ppm based on the total weight of the resin composition of at least one ultraviolet absorber selected from the hydroxyphenylbenzotriazole class
Data Source
AI summary
Described herein are caps or closures made from a resin composition having at least one polyethylene having a density of at least 0.940 g/cm3 when measured following the ISO 1183-2 method at 23° C.; erucamide; and at least 700 ppm based on the total weight of the resin composition of at least one ultraviolet absorber selected from the hydroxyphenylbenzotriazole class. A process for the production of such caps or closures is also described herein.