Polymer Powder Coloring via Liquid Spray and Pulverization
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Solution Overview
Problem
Current methods for coloring polymeric materials for rotational molding face challenges such as uneven color distribution, time-consuming processes, and economic inefficiencies due to the use of solid pigments and liquid color formulations, which require extensive cleaning and struggle with homogenous coloring.
Innovation Solution
A method involving a pulverizer to heat polymeric material pellets into a powder and then directly feeding it into a mixer where a liquid formulation, comprising a colorant and vehicle, is sprayed onto the powder at low pressure to achieve intimate mixing, ensuring consistent color distribution without the need for re-heating or extensive cleaning between color changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If solid pigments are mixed with polymeric material powder, then coloring is achieved, but uneven color distribution and inconsistent color in final product occur
Solution Approach 1:
The patent changes the physical state of the colorant from solid to liquid form, and applies it to the polymeric material in a specific sequence (first pulverization, then liquid colorant addition, then second pulverization). This parameter change in the state of matter and process sequence enables homogeneous color distribution while maintaining manufacturing efficiency.
2Manufacturing precision
If liquid color formulations are added during pulverization, then coloring is achieved, but extensive cleaning of pulverization apparatus is required for color changes
Solution Approach 1:
The patent divides the coloring process into two separate stages: first stage involves pulverization of polymeric material without colorant, second stage involves adding liquid colorant and further pulverization. This segmentation allows the pulverization apparatus to be used for multiple color productions without extensive cleaning between color changes, as the liquid colorant is applied after the initial pulverization.
Solution Approach 2:
The polymeric material is pulverized first before the liquid colorant is added. This preliminary pulverization creates a uniform base structure that readily absorbs the liquid colorant in the second stage, achieving homogeneous color distribution without requiring the pulverization apparatus to be cleaned between color changes.
3Device complexity
If solid pigments are used for coloring, then the process is simple, but the process is time-consuming and discontinuous
Solution Approach 1:
The patent implements a continuous process where polymeric material is pulverized, liquid colorant is continuously added, and the mixture is further pulverized in sequence without interruption. This continuous operation eliminates the discontinuous nature of traditional solid pigment mixing, significantly improving productivity while keeping the apparatus relatively simple.
4Device complexity
If conventional coloring methods are used, then equipment is simple, but energy requirements are high due to re-heating needs
Solution Approach 1:
The polymeric material is pulverized to a fine powder state before the liquid colorant is added. This preliminary pulverization creates a large surface area that facilitates immediate and complete absorption of the colorant during the second pulverization stage, eliminating the need for subsequent re-heating or re-processing steps and thereby reducing energy consumption.
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 approach results in a homogenously colored powder with improved color adhesion and reduced energy requirements, enabling efficient and cost-effective production of colored polymeric powders for rotational molding, allowing for continuous processing and easy color changes without extensive cleaning.
Implementation Method 1
A pulverizer is arranged to deliver uncolored pulverized polymer powder
Implementation Method 2
a mixer receiving the pulverized polymer powder and a spray device operatively connected to the mixer and arranged to spray a liquid formulation onto the pulverized polymer powder
Implementation Method 3
The powder and liquid formulation are mixed
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The method of producing a colored powder of a polymeric material includes the steps of selecting a feedstock of said polymeric material, pulverizing said polymeric material in a pulverizer to produce a powder, moving the powder directly from the pulverizer to a mixer; spraying a liquid formulation including a colorant into the powder within the mixer, and mixing the liquid formulation and powder.