Copolyester View Stripe Composition for Blow Molded Packaging
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Solution Overview
Problem
Existing opaque extrusion blow molded articles made from polypropylene (PP) or high-density polyethylene (HDPE) lack good aesthetics, clarity, and UV barrier properties, and are not easily recyclable, limiting their use in packaging that requires clear view stripes and dishwasher compatibility.
Innovation Solution
Developed multi-layer extrusion blow molded articles with transparent view panels using copolyester compositions comprising specific ranges of terephthalic acid, ethylene glycol, and modifying glycols like 1,4-cyclohexanedimethanol, which provide increased melt strength, good processibility, impact properties, and UV barrier, with a haze value of less than 10% and recyclability in PET streams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polypropylene or high-density polyethylene is used for extrusion blow molded articles, then the articles can be manufactured with good processibility, but the aesthetics are poor with dull surfaces and hazy clear view stripes
Solution Approach 1:
The patent uses composite polyester materials containing specific comonomers (cyclohexanedimethanol, neopentyl glycol, or 1,3-cyclobutanediol) to achieve both good processibility and aesthetics. The composite polymer structure provides enhanced melt strength for manufacturing while delivering high gloss surfaces and clear transparent view stripes, resolving the contradiction between ease of manufacture and aesthetics.
2Object-generated harmful factors
If polyesters such as PET are used for blow molded articles, then good aesthetics can be achieved, but melt strength is insufficient for extrusion blow molding processes
Solution Approach 1:
The patent modifies the polyester composition by incorporating specific comonomers (cyclohexanedimethanol, neopentyl glycol, or 1,3-cyclobutanediol) at controlled amounts (5-30 mol%, 1-20 mol%, or 1-15 mol% respectively). This parameter change in chemical composition increases melt strength to 20,000-100,000 poise at processing temperature, enabling extrusion blow molding while maintaining the aesthetic properties of polyester.
3Reliability
If conventional polyesters are used to achieve clear transparency, then UV barrier properties are insufficient for packaging applications requiring UV protection
Solution Approach 1:
The patent applies local quality by incorporating UV stabilizers and antioxidants as additives in the polyester composition. These functional additives are distributed within the polymer matrix to provide localized UV protection while maintaining the overall clear transparency and aesthetic properties of the packaging article.
4Object-affected harmful factors
If opaque materials are used for extrusion blow molded articles, then UV barrier properties are improved, but the clear view stripe functionality is lost
Solution Approach 1:
The patent uses local quality by creating multi-layer structures where opaque or translucent layers provide UV barrier protection while clear transparent layers form view stripes. The polyester base material with enhanced melt strength enables this layered configuration, allowing simultaneous achievement of UV protection and visual inspection functionality through strategic material placement.
Data Source
AI summary
Blow molded articles with transparent view stripes made from copolyester compositions which comprise residues of terephthalic acid, 1,4-cyclohexanedimethanol (CHDM), ethylene glycol (EG), neopentyl glycol (NPG), and/or 2,2,4,4-tetramethyl-1,3-cyclobutanediol (TMCD) residues, in certain compositional ranges having certain advantages and improved properties.