Prefoaming Starch Mass for Uniform Blown Foam Structure
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Solution Overview
Problem
Existing methods for manufacturing products with a blown foam structure from renewable biopolymers face challenges in achieving even skin formation and internal structure distribution, leading to marbled surfaces and difficulty in controlling the foaming process, especially when using starch-based materials.
Innovation Solution
The method involves prefoaming the mass to fill the mould cavity completely and evenly, reducing the need for water as a blowing agent, and using pressurized gas bubbles to create a stable foam structure with controlled expansion, allowing for the use of low foaming starch and enhancing product strength and aesthetics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the mass is inserted into the mould cavity without prefoaming, then the mould cavity can be filled with the mass, but the skin formation becomes uneven and marbled surfaces occur
Solution Approach 1:
The mass is prefoamed before insertion into the mould cavity. This preliminary action creates a foam structure with gas bubbles distributed throughout the mass, which ensures even skin formation during subsequent heating and eliminates marbled surfaces on the final product.
2Productivity
If water is used as blowing agent in large amounts, then the foam structure can be created, but the manufacturing time increases due to longer evaporation and drying cycles
Solution Approach 1:
The patent changes the blowing agent from water to pressurized gas (such as carbon dioxide or nitrogen). This parameter change allows for much faster release of the blowing agent during heating, dramatically reducing evaporation time and enabling faster moulding cycles while maintaining the desired foam structure.
3Strength
If high foaming starch is used, then the foam structure develops well, but the product strength decreases
Solution Approach 1:
The mass is prefoamed under controlled conditions before insertion into the mould. This preliminary foaming action creates a stable foam structure with uniformly distributed gas bubbles. When using low foaming starch, the prefoaming ensures that the foam structure is already established before heating, compensating for the lower inherent foaming capability and maintaining both product strength and foam uniformity.
Solution Approach 2:
Pressurized gas serves as an intermediary that facilitates foam structure creation. The gas bubbles act as nucleation sites and provide the necessary expansion force to create a uniform foam structure even when using starch with low inherent foaming properties, thereby maintaining both strength and structural uniformity.
4Manufacturing precision
If the mass is not prefoamed, then the process is simpler, but the internal foam structure becomes non-homogeneous
Solution Approach 1:
Prefoaming the mass before insertion into the mould cavity ensures homogeneous internal foam structure. The gas bubbles are uniformly distributed throughout the mass during prefoaming, and this uniform distribution is maintained during subsequent heating and setting, achieving homogeneous foam structure without excessive process complexity.
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 homogeneous foam structure, reduced manufacturing costs, and improved product aesthetics by minimizing marbling and shininess, while enabling the use of cost-effective biopolymers like corn starch or wheat starch, with faster moulding cycles and reduced water usage.
Implementation Method 1
introducing a gas such as air, oxygen, nitrogen or carbon dioxide in a liquid mass comprising at least starch to form a prefoamed mass having a lower density than the liquid mass prior to prefoaming
Implementation Method 2
the prefoamed mass is kept under pressure until insertion in the mould
Implementation Method 3
the water in the batter functions as blowing agent and moreover, upon evaporating from the mould, provides space for the expansion of the cells of the polymers
Implementation Method 4
heating said mass in the mould in a manner such as to give rise to gelatinization and cross-linking of the natural polymers
Implementation Method 5
The granulate material can contain a blowing agent, for instance in the form of water or blowing agents simply released and/or evaporating upon heating such as bicarbonates which provide for gas evolution through decomposition at elevated temperature
Implementation Method 6
Due to the stabilization inside the mould cavity and the heat activation of the blowing agent, the mass is going to create foam, the foam creates additional volume and force to flow further into the cavity
Implementation Method 7
heating said mass in the mould in a manner such as to give rise to gelatinization and cross-linking of the natural polymers
Implementation Method 8
heating said mass in the mould in a manner such as to give rise to gelatinization and cross-linking of the natural polymers
Data Source
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AI summary
A method for manufacturing sustainable products with a blown, foam structure, wherein a mass comprising at least natural polymers such as starch is passed under pressure into a mould cavity (4) or through a mould die, and the mass is heated in the mould in a manner such as to stabilize the foamed structure to form the product, wherein the method comprises prefoaming of the mass prior to injection in the mould. Preferably, the prefoamed mass is kept under pressure until insertion in the mould. The invention further relates to an apparatus to be used in said method.