Polyurethane Sheet Vacuum Processing to Reduce Bubble Formation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional polyurethane sheets/laminates produced via two-component systems often contain large, unevenly distributed air bubbles due to physical blending air or chemical reaction with water, leading to defects such as reduced transmittance and mechanical properties in applications like synthetic leather.
Innovation Solution
The process involves keeping the isocyanate component (A) and polyol composition component (B) separately in tanks under vacuum and applying them at a relative humidity of 65% or below, followed by mixing and curing to form a polyurethane layer, which is then separated from a release layer to reduce bubbles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If components (A) and (B) are mixed and applied under conventional conditions, then the polyurethane system can be easily manufactured and applied, but large air bubbles are formed due to physical blending air or chemical reaction with water
Solution Approach 1:
The patent applies vacuum treatment to components (A) and (B) separately before mixing to remove air and moisture in advance. This preliminary action prevents bubble formation during mixing and application, resolving the contradiction by preparing materials in advance under controlled conditions rather than dealing with bubbles during the manufacturing process.
Solution Approach 2:
The patent creates a low-humidity environment (relative humidity 65% or below) during application and uses vacuum conditions to establish an inert-like atmosphere that prevents water from reacting with isocyanates. This controlled environment approach eliminates bubble formation while maintaining process simplicity.
2Reliability
If conventional mixing and application methods are used, then the process is simple and fast, but the polyurethane sheet/laminate contains bubbles with average diameter of 50 μm or higher, reducing transmittance and mechanical properties
Solution Approach 1:
The patent implements vacuum treatment of components (A) and (B) before mixing to remove air and moisture in advance. This preliminary preparation ensures high transmittance and mechanical properties by preventing bubble formation, while the vacuum process itself is efficiently integrated into the existing manufacturing workflow, minimizing impact on production efficiency.
Solution Approach 2:
The patent changes the physical parameters of the application environment by controlling relative humidity to 65% or below and applying vacuum conditions. These parameter changes prevent water-isocyanate reactions and air entrapment, ensuring high product reliability without requiring complex additional processing steps that would reduce productivity.
3Manufacturing precision
If components are kept separately under vacuum and applied at controlled humidity, then bubble area is reduced to less than 1.5%, but the process complexity and equipment requirements increase
Solution Approach 1:
The patent applies vacuum treatment to components (A) and (B) separately before mixing to remove air and moisture in advance. This preliminary action achieves less than 1.5% bubble area in the final product. The process integrates vacuum tanks and humidity control into the manufacturing line, making the additional complexity manageable while achieving superior manufacturing precision.
Solution Approach 2:
The patent creates a controlled low-humidity environment (65% or below) and uses vacuum conditions to establish an inert-like atmosphere during component storage and application. This approach minimizes bubble formation to less than 1.5% area while using standard industrial vacuum and humidity control equipment, maintaining reasonable ease of manufacture.
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 method results in a polyurethane sheet/laminate with less than 1.5% bubble area, average bubble diameters of less than 30 µm, and improved mechanical properties, suitable for applications requiring high transmittance and transparency.
Implementation Method 1
the components (A) and (B) are kept separately in tanks under vacuum before mixing
Implementation Method 2
the application of the polyurethane system is implemented under relative humidity of 65% or below
Data Source
Figure 1
Figure 2(a)
Figure 2(b)
AI summary
The present invention relates to a process for preparing polyurethane sheet/laminate with reduced bubbles, comprising the steps of applying a polyurethane system obtained by mixing an isocyanate component (A) and a polyol composition component (B) to form a base coat layer, wherein the components (A) and (B) are kept saperately in tanks under vacuum before mixing and the application of the polyurethane system is implemented via knife coating under relative humidity of 65% or below. The present invention further relates to a polyurethane sheet/laminate prepared by the described process and synthetic leather made from the polyurethane sheet/laminate.