Opaque Polyester Preform Composition for Uniform Blow-Moulding Heating
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Solution Overview
Problem
The manufacturing of opaque polyester containers is challenging due to a narrow process window in blow moulding, exacerbated by temperature differences during NIR heating caused by traditional light absorbers like iron oxide, graphite, and aluminium powder, leading to inhomogeneous heating and process instability.
Innovation Solution
A preform composition comprising titanium dioxide and a light absorbing additive, with specific optical properties of 0.1% transmittance at 550 nm and 0.5% transmittance at 1300 nm, or 25% absorption at 550 nm and 20% absorption at 1300 nm, which maintains opacity in the UV and visible regions while minimizing NIR absorption, thereby reducing temperature differences during blow moulding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional light absorbers like iron oxide, graphite, and aluminium powder are used to create opaque containers, then opacity in the ultraviolet and visible regions is achieved, but temperature differences during NIR heating increase causing inhomogeneous heating
Solution Approach 1:
The patent changes the optical parameters of the light absorbing additive by selecting compounds with specific absorption spectra that minimize NIR absorption while maintaining UV and visible light absorption. This parameter change resolves the contradiction by decoupling the absorption properties at different wavelengths, allowing opacity without excessive NIR heating.
Solution Approach 2:
The patent uses composite light absorbing additives comprising multiple compounds (e.g., mixtures of azo dyes, anthraquinone dyes, or other organic pigments) that collectively provide broad UV and visible light absorption while maintaining low NIR absorption. This composite approach allows tuning of the absorption spectrum to achieve the desired optical properties without the harmful temperature effects.
2Object-affected harmful factors
If titanium dioxide is used as a light reflective pigment to achieve opacity, then ultraviolet and visible light reflection is improved, but additional colourants are required to absorb remaining light
Solution Approach 1:
The patent extracts or removes the need for additional black pigments by using light absorbing additives that provide sufficient opacity on their own or in combination with reduced amounts of titanium dioxide. This takes out the complexity of multi-component systems while maintaining the light barrier function.
Solution Approach 2:
The patent changes the concentration and type of titanium dioxide and light absorbing additives to optimize the balance between reflection and absorption. By adjusting these parameters, the system achieves adequate opacity with simpler compositions that do not require multiple layers or complex multi-pigment formulations.
3Object-affected harmful factors
If multilayer containers with different colourants are used to protect light sensitive contents, then light protection is improved, but temperature differences during heating become more pronounced
Solution Approach 1:
The patent applies local quality by using a single-layer construction with uniformly distributed light absorbing additives that have specific spectral absorption properties. This eliminates the need for multiple layers with different colourants, thereby avoiding the temperature differences that arise from layer-to-layer variations in optical properties while still providing comprehensive light protection.
4Manufacturing precision
If the process window for blow moulding of opaque preforms is narrowed due to inhomogeneous heating, then manufacturing precision decreases, but process sensitivity increases
Solution Approach 1:
The patent changes the thermal-optical parameters of the preform material by selecting light absorbing additives with minimal NIR absorption. This parameter change widens the process window for blow moulding by ensuring uniform heating throughout the preform, thereby improving both manufacturing precision and process stability simultaneously.
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 an improved process window for blow moulding by ensuring uniform heating and reducing temperature variations, enhancing the manufacturing efficiency and stability of opaque polyester containers.
Implementation Method 1
Application of titanium dioxide as pigment results in a material that reflects the majority of the incoming ultraviolet and visible light
Implementation Method 2
additional colourants are added, which absorb the ultraviolet and visible light that is not reflected by titanium dioxide
Implementation Method 3
during heating of the polyester-based material, large temperature differences are observed between the inside and outside of the preforms
Data Source
AI summary
The invention discloses a preform for a container comprising a polyester, titanium dioxide, and a light absorbing additive. In addition, a process for preparing a polyester-based container from such a preform is disclosed, as well as a polyester-based container obtainable by such a process. The opaque containers can for instance be used for storing light-sensitive solids and/or liquids. The optical properties of the preform result in improved properties during blow-moulding processes.