Addition-Curable Organopolysiloxane for Low-Catalyst Clear Films
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Solution Overview
Problem
Existing organopolysiloxane compositions require high amounts of platinum group metal-based catalysts for effective curing, leading to high costs and potential catalyst poisoning, and result in cloudy appearances and sedimentation due to high cyclic low-molecular-weight siloxane content.
Innovation Solution
A combination of organopolysiloxanes with specific ratios of silicon-bonded alkenyl and (meth)acrylic groups, along with an organohydrogenpolysiloxane and a platinum group metal-based catalyst, reduces the catalyst amount while maintaining release force and minimizing cyclic low-molecular-weight siloxanes, thus preventing sedimentation and cloudiness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a small amount of platinum group metal-based catalyst is used, then cost is reduced, but the cure reaction does not take place to full extent resulting in low cured film strength and high release force
Solution Approach 1:
The invention changes the chemical parameters of the organopolysiloxane composition by introducing specific functional groups (meth)acrylic groups and controlling the ratio of alkenyl groups to hydrogen atoms. This parameter modification enables the cure reaction to proceed to full extent with only 1-100 ppm platinum catalyst, resolving the contradiction between low cost and complete curing.
Solution Approach 2:
The invention uses a composite organopolysiloxane system combining multiple functional groups (alkenyl, (meth)acrylic, and hydrogen atoms) in specific ratios. This composite approach creates a synergistic effect that enhances cure reaction efficiency, allowing complete curing at reduced platinum catalyst levels.
2Reliability
If high amount of platinum group metal-based catalyst is used, then full cure is achieved, but cost increases and catalyst poisoning by substrate substances becomes problematic
Solution Approach 1:
By modifying the composition parameters to include specific functional groups and their ratios, the invention reduces catalyst demand from conventional levels to 1-100 ppm. This parameter change makes the system less susceptible to catalyst poisoning while maintaining complete cure, as the optimized reaction pathway requires fewer catalyst sites.
3Reliability
If conventional organopolysiloxane composition is used, then effective curing is achieved, but cloudy appearance and sedimentation occur due to high cyclic low-molecular-weight siloxane content
Solution Approach 1:
The invention changes the molecular weight distribution parameters and cyclic siloxane content parameters of the organopolysiloxane composition. By controlling these parameters, the system achieves complete curing while eliminating cloudiness and sedimentation, resulting in a uniform transparent cured film.
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 composition achieves full cure with a minor platinum content, reducing costs and preventing sedimentation and cloudiness, while maintaining release force equivalent to traditional methods.
Implementation Method 1
a platinum group metal-based catalyst in an amount to give 1 to 200 ppm of platinum group metal based on the total weight of the composition
Implementation Method 2
addition reaction between an alkenyl-containing organopolysiloxane and an organohydrogenpolysiloxane
Data Source
AI summary
An addition reaction-curable organopolysiloxane composition containing: (A) (A-1) an organopolysiloxane that has a silicon atom-bonded alkenyl group in one molecule and does not have a (meth)acrylic group and (A-2) an organopolysiloxane having an alkenyl group and a (meth)acrylic group in one molecule; (B) an organohydrogenpolysiloxane having two or more silicon atom-bonded hydrogen atoms (Si-H groups) on average in one molecule; and (C) 1-200 ppm of a platinum group metal-based catalyst in terms of platinum group metal mass based on the total amount of the composition, wherein addition reaction curing can be achieved using a small amount of the platinum group metal-based catalyst, a cured film having a peeling force equivalent to those of conventional cured films can be formed, and the composition has a reduced amount of cyclic low-molecular-weight siloxane, a less cloudy appearance, and suppressed sedimentation over time.