Coloured Polypropylene Beta-Nucleation Process
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Solution Overview
Problem
Existing polypropylene compositions with high β-modification content are difficult to achieve due to the dominance of α-nucleating agents, which limits the impact strength of polypropylene pipes, especially at low temperatures, as organic pigments often act as strong α-nucleating agents, making it challenging to produce colored polypropylene with enhanced β-modification.
Innovation Solution
A process involving the separate melt blending of polypropylene with inorganic pigments and β-nucleating agents, either in the form of concentrates or simultaneously, to achieve a higher content of β-modification, ensuring that the inorganic pigments do not act as strong α-nucleating agents, thereby increasing the impact strength of polypropylene pipes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If organic pigments are used to produce coloured polypropylene, then the polypropylene can be coloured, but the organic pigments act as strong α-nucleating agents which reduce the β-modification content and impact strength
Solution Approach 1:
The patent replaces organic pigments (which have harmful nucleating effects) with inorganic pigments that do not act as strong α-nucleating agents. This substitution allows achieving the desired colour without sacrificing impact strength, effectively using a different material class to avoid the harmful side effects of the original approach
Solution Approach 2:
The patent changes the chemical composition parameter by selecting specific inorganic pigments (such as iron oxides, chromium oxides, cobalt oxides) that have different nucleating properties compared to organic pigments. This parameter change allows the polypropylene to achieve both colour and high β-modification content, resolving the contradiction between colouration and impact strength
2Stability of the object's composition
If α-nucleating agents are present in polypropylene, then the polypropylene crystallises predominantly in the α-modification, but this reduces the β-modification content and impact strength
Solution Approach 1:
The patent extracts or removes α-nucleating agents from the polypropylene composition to prevent unwanted α-crystallisation. By eliminating these harmful nucleating agents and using only inorganic pigments that do not strongly promote α-modification, the patent allows β-nucleating agents to dominate the crystallisation process, achieving high β-modification content and improved impact strength
Solution Approach 2:
The patent changes the nucleating agent composition parameter by specifically selecting inorganic pigments that do not act as strong α-nucleating agents. This parameter change shifts the crystallisation balance towards β-modification when combined with β-nucleating agents, resolving the contradiction between crystalline structure stability and impact strength
3Strength
If inorganic pigments are used instead of organic pigments, then the impact strength can be improved, but additional process steps are required to achieve high β-modification content
Solution Approach 1:
The patent merges the colouration function and β-nucleation function into a single integrated process by using inorganic pigments combined with β-nucleating agents. This combination allows both colour and high β-modification content to be achieved simultaneously in one compounding step, eliminating the need for separate processing steps and reducing overall process complexity
Solution Approach 2:
The patent employs inorganic pigments that serve dual purposes: providing colouration while simultaneously not interfering with β-crystallisation. This multi-functionality approach allows a single additive system to achieve both colour and improved impact strength, simplifying the overall formulation and processing
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
This process significantly increases the β-modification content of polypropylene, resulting in pipes with enhanced impact strength, as demonstrated by the falling weight impact test at 0°C, indicating improved resistance against breakage during installation and operation.
Implementation Method 1
the inorganic pigment is intimately mixed with the β-nucleating agent and a concentrate is produced by melt blending a polyolefin with this mixture
Implementation Method 2
polypropylene which crystallises predominantly in the β-modification has an increased impact strength compared to polypropylene when it is crystallised in the α-modification
Implementation Method 3
a coloured polypropylene composition is produced by melt blending polypropylene with a first concentrate and a second concentrate
Data Source
AI summary
The invention relates to a novel process for producing coloured polypropylene compositions having a high content of β-modification, wherein polypropylene is melt blended with at least one inorganic pigment and at least one β-nucleating agent, wherein a1) polypropylene is melt blended with at least one inorganic pigment or with a first concentrate comprising the at least one inorganic pigment to obtain a coloured polypropylene and a2) the coloured polypropylene is melt blended with at least one β-nucleating agent or with a second concentrate comprising the at least one ß-nucleating agent to obtain the coloured ß-nucleated polypropylene composition or b1) polypropylene is melt blended with at least one β-nucleating agent or with a second concentrate comprising the at least one β-nucleating agent to obtain a β-nucleated polypropylene and b2) the β-nucleated polypropylene is melt blended with at least one inorganic pigment or with a first concentrate comprising the at least one inorganic pigment to obtain the coloured β-nucleated polypropylene composition or c) a third concentrate is produced by melt blending a first concentrate comprising the at least one inorganic pigment and a second concentrate comprising the at least one β-nucleating agent and the polypropylene is melt blended with the third concentrate to produce the coloured β-nucleated polypropylene composition.