Polyurethane Pad Pore Uniformity via Catalyst Hydrolysis
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Solution Overview
Problem
Existing polyurethane mounting pads lack uniform pore formation and exhibit insufficient compressibility and compression recovery rates, making them inadequate for precise polishing applications, such as glass substrates for displays, which require uniform thickness and pressure distribution.
Innovation Solution
A method involving the wet-solidification of a polyurethane resin composition with DMF solvent followed by immersion in an aqueous solution containing an acid or base catalyst to decrease the molecular weight of the polyurethane resin, resulting in a pad with uniformly distributed long oval-shaped pores, lower density, and enhanced compressibility and elasticity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional mounting pads are used, then manufacturing is simpler, but pore uniformity and compressibility are insufficient
Solution Approach 1:
The patent applies parameter changes by controlling the molecular weight of polyurethane resin within a specific range (200,000 to 400,000) and adjusting the water content (5-20 wt%) to achieve uniform pore formation. By optimizing these parameters, the invention resolves the contradiction between manufacturing precision and ease of manufacture, as the specific parameter ranges provide clear manufacturing guidelines while achieving the desired pore uniformity.
Solution Approach 2:
The patent employs preliminary action by pre-mixing the polyurethane resin with a specific amount of water before the foaming process. This preliminary preparation ensures that water is uniformly distributed throughout the resin matrix, which then facilitates uniform pore formation during the foaming process, thereby achieving consistent pore structure without requiring complex post-processing.
2Ease of operation
If higher compressibility is achieved through pore formation, then polishing uniformity improves, but compression recovery rate decreases
Solution Approach 1:
The patent resolves this contradiction by changing the molecular weight parameter of polyurethane resin to a specific range (200,000 to 400,000). This parameter optimization allows the material to achieve both high compressibility (through uniform pore structure) and good compression recovery rate (through appropriate molecular weight), eliminating the trade-off between these two properties.
Solution Approach 2:
The invention effectively creates a composite structure by combining polyurethane resin with controlled water content (5-20 wt%), where the water acts as a pore-forming agent. This composite approach during manufacturing results in a material that possesses both the compressibility needed for polishing uniformity and the elastic recovery properties needed for maintaining pad shape and pressure distribution.
3Ease of operation
If pore size is increased to improve compressibility, then compression recovery rate deteriorates
Solution Approach 1:
The patent resolves this contradiction by precisely controlling the water content parameter within 5-20 wt% of the total composition. This parameter control ensures the formation of uniformly distributed pores of appropriate size, achieving sufficient compressibility while maintaining the structural integrity needed for good compression recovery rate, thus eliminating the trade-off between these properties.
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 method enables the creation of a polyurethane mounting pad with improved compressibility and compression recovery rates, ensuring uniform pressure distribution and high-efficiency polishing by maintaining the shape of pores and reducing hardness, thus overcoming the limitations of previous pads.
Implementation Method 1
immersing the wet-solidified product in an aqueous solution comprising an acid catalyst or a base catalyst
Data Source
Figure 1~2
AI summary
This disclosure relates to a method for preparing a polyurethane mounting pad comprising the steps of: wet-solidifying a resin composition comprising polyurethane resin and a DMF solvent; and immersing the wet-solidified product in an aqueous solution comprising an acid catalyst or a base catalyst. According to the present invention, long and large pores may be uniformly formed inside of the prepared pad, thus affording low hardness, excellent compressibility, and the like, and more uniform thickness, pressure distribution or tension distribution and the like may be exhibited over the whole area of the pad, thus providing a polyurethane mounting pad that can realize more uniform and high efficiency polishing.