TPU Golf Ball Cover Catalyst Dip Cross-Linking
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Solution Overview
Problem
Existing methods for improving the shear durability of thermoplastic polyurethane (TPU) golf ball covers using polyisocyanates face challenges such as low reactivity, molecular weight loss, and processibility issues due to high reactivity, which limit the effectiveness of cross-linking and durability enhancement.
Innovation Solution
The method involves mixing an aliphatic polyisocyanate crosslinker with the base TPU cover material, followed by dipping the golf ball in a catalyst solution and heating to allow diffusion, promoting post-cure reactions that enhance intermolecular cross-linking and molecular weight extension, thereby improving groove shear durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyisocyanate crosslinker is incorporated into TPU cover layer before or during injection molding, then chemical cross-linking is imparted to improve durability, but polyisocyanate reactivity is low resulting in insufficient cross-linking conversion
Solution Approach 1:
The cross-linking process is segmented into two distinct stages: (1) mixing polyisocyanate crosslinker with TPU before injection molding, and (2) exposing to catalyst solution after molding. This separation allows the molding process to complete first while the cross-linking reaction is postponed to a later stage where it can proceed to completion without interfering with the molding operation.
Solution Approach 2:
The polyisocyanate crosslinker is prepared in advance and mixed with the TPU material before injection molding. This preliminary preparation ensures that the crosslinking agents are properly distributed in the material but remain dormant until exposed to the catalyst solution after molding, allowing full conversion to occur post-molding.
2Reliability
If high polyisocyanate reactivity is used, then cross-linking conversion is improved, but TPU molecular weight loss occurs with diisocyanates and rapid molecular weight growth with triisocyanates and higher order polyisocyanates, limiting processibility
Solution Approach 1:
The catalyst that triggers polyisocyanate reactivity is extracted from the molding process and placed in a separate post-molding exposure step. This removes the harmful effect of high reactivity during molding while preserving the beneficial cross-linking conversion in a subsequent stage.
Solution Approach 2:
A catalyst solution acts as an intermediary that is introduced after molding to trigger the polyisocyanate cross-linking reaction. This intermediary allows the reaction to occur under controlled post-molding conditions rather than during the molding process, eliminating interference with processibility.
3Reliability
If polyisocyanate cross-linking is performed during injection molding, then durability is improved, but the molding process becomes coupled with cross-linking reactions, reducing process flexibility and control
Solution Approach 1:
The manufacturing process is segmented into independent molding and cross-linking stages. The molding process can be optimized for processibility without cross-linking interference, while the cross-linking stage can be optimized for durability enhancement. This segmentation provides process flexibility and allows each stage to be independently controlled and optimized.
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 maximizes polyisocyanate conversion and durability of the golf ball cover, decoupling the molding process from cross-linking and enhancing the processibility of the TPU cover, resulting in improved resistance to scuffing, cutting, and tearing.
Implementation Method 1
dipping the golf ball in a catalyst solution and heating the golf ball to allow continued diffusion of the catalyst solution into the cover of the golf ball
Implementation Method 2
heating the golf ball to allow continued diffusion of the catalyst solution into the cover of the golf ball
Implementation Method 3
mixing a polyisocyanate crosslinker with a base TPU cover material... promoting post-cure reactions that enhance intermolecular cross-linking and molecular weight extension
Data Source
AI summary
The present invention relates to a method for forming a golf ball. The method comprises mixing a polyisocyanate crosslinker with a base TPU cover material, wherein the polyisocyanate crossliker is aliphatic, miscible with the base TPU cover material and has functionalities greater than or equal to 2. The method further comprises dipping a golf ball in a catalyst solution, wherein the catalyst solution is allowed to absorb into a cover of the golf ball and heating the golf ball to allow continued diffusion of the catalyst solution into the cover of the golf ball.