Plastic Pipe Molded Article Solar Radiation Bending

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Solution Overview

Problem

Plastic pipes made of polypropylene, when exposed to solar radiation, undergo significant longitudinal bending due to heating, making them difficult to lay flat and leading to potential stagnation and odor issues, especially when supported at ends.

Innovation Solution

Incorporating a mixed-phase oxide pigment with a rutile structure, such as chrome titanium yellow, and a dark titanium dioxide into the polymer material to reduce heat absorption and bending, along with optional additional pigments and fillers for color and mechanical properties, and strategically distributing these components within the pipe layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If conventional pigments are used to color the polypropylene pipes, then the pipes achieve the desired color appearance, but the pipes absorb excessive solar radiation and convert it to heat, causing significant longitudinal bending

Engineering Contradiction:
Improvelongitudinal bendingVSAvoidsolar radiation absorption
Core Design Contradiction:
ShapeVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical composition parameters of the pigment by using a mixed-phase oxide pigment containing both rutile and anatase phases of titanium dioxide, along with specific ratios of iron oxide and chromium oxide. This parameter change in pigment composition fundamentally alters the optical properties, reducing solar radiation absorption and the resulting heat generation that causes longitudinal bending.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite pigment system combining multiple oxide phases (rutile TiO2, anatase TiO2, Fe2O3, Cr2O3) in specific proportions. This composite material approach creates a pigment with optimized optical properties that simultaneously provides coloration and reduced solar heat absorption, directly addressing the longitudinal bending issue.

Inventive Principle:
Principle #40Composite materials

2Device complexity

If the pipes are supported only at their ends during storage, then the storage structure is simple, but the pipe weight combined with solar radiation causes even greater longitudinal bending

Engineering Contradiction:
Improvestorage structureVSAvoidlongitudinal bending
Core Design Contradiction:
Device complexityVSShape

Solution Approach 1:

The patent applies preliminary action by incorporating the specialized mixed-phase oxide pigment into the pipe material before storage. This preventive measure reduces the pipe's sensitivity to solar radiation heating, thereby mitigating thermal expansion and longitudinal bending even when stored with simple end support structures.

Inventive Principle:
Principle #10Preliminary action

3Manufacturing precision

If the pipes are laid with very small slopes, then the installation precision is high, but bottom bends occur leading to stagnant fluid and deposits

Engineering Contradiction:
Improveslope uniformityVSAvoidfluid flow
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The patent uses preliminary action by reducing longitudinal bending through specialized pigment composition before the pipe is installed. This ensures that even when laid with small slopes, the pipe maintains its intended geometry without developing bottom bends, thereby preventing stagnant fluid accumulation and ensuring reliable fluid flow.

Inventive Principle:
Principle #10Preliminary action

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 results in reduced heating and bending of the pipes under solar radiation, improving their flatness and preventing stagnation, with a 15% reduction in deflection and an 8 K lower surface temperature compared to conventional compositions.

Implementation Method 1

a molded part colored with it absorbs less radiation and converts it into heat than is the case with the pigments that are conventionally used for coloring

Methodology Applied
Scientific EffectSolar radiation absorption: Absorption (EM radiation)

Implementation Method 2

The one-sided action of solar radiation on the pipes causes a more or less pronounced longitudinal bend

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP2614113B1Plastic tube molded article
Publication Date: 2015.04.29 REHAU AG & CO
  • EP2614113B1 patent drawingFigure 1

AI summary

The invention relates to a plastic pipe molded part (1), comprising a wall, which surrounds the tubular cavity (7) of the plastic pipe molded part (1), has at least one layer (2) and contains polymer material, wherein said molded part is characterized in that same contains a mixed-phase oxide pigment having a rutile structure (3).