Radiation-Curable Organopolysiloxane Coating for Durable Release Sheets
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Solution Overview
Problem
Existing radiation-curable organopolysiloxane compositions for release sheets suffer from inadequate adhesion to substrates like PET film and poor long-term adhesion under wet and heat conditions due to high hydroxyl group content, leading to reduced strength and releasability.
Innovation Solution
A radiation-curable organopolysiloxane composition is formulated with limited hydroxyl group content, incorporating a (meth)acryloyl group-containing organopolysiloxane, a polyfunctional acrylic compound, and a radical polymerization initiator, ensuring a ratio of hydroxyl groups to (meth)acryloyl groups is 0.4 or less, enhancing adhesion and releasability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a (meth)acryloyl group-containing radical-polymerizable organopolysiloxane with high hydroxyl group content is used, then adhesion to substrate is improved, but releasability from adhesive substance deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the hydroxyl group content in the organopolysiloxane composition. Specifically, it sets the hydroxyl group content to 0.1-10 mmol/g (optimally 0.5-5 mmol/g) and the (meth)acryloyl group content to 0.5-50 mmol/g, maintaining a specific ratio relationship. This parameter optimization resolves the contradiction by finding the balance point where both adhesion and releasability are satisfied.
Solution Approach 2:
The patent uses composite materials by combining multiple components: (meth)acryloyl group-containing organopolysiloxane, silane crosslinking agent, and optionally hydroxyl group-containing organic compounds. This composite approach allows the composition to achieve both strong adhesion (through silane crosslinking) and good releasability (through controlled hydroxyl content), resolving the contradiction between these two properties.
2Reliability
If conventional curing methods (condensation reaction, sulfurization, hydrosilylation) are used, then curing can be achieved, but heating is required which reduces productivity and increases energy consumption
Solution Approach 1:
The patent replaces thermal energy (heating) with radiation energy (ultraviolet or electron beam) to initiate curing. The radiation-curable organopolysiloxane composition contains (meth)acryloyl groups that undergo radical polymerization when exposed to radiation, eliminating the need for heating and enabling rapid curing at room temperature, thus dramatically improving productivity and reducing energy consumption.
3Productivity
If radiation-curing method is used, then curing at lower temperature is achieved improving productivity, but oxygen interferes with curing reducing effectiveness
Solution Approach 1:
The patent addresses oxygen interference by applying the inert atmosphere principle. It recommends conducting the curing process in an oxygen-depleted environment (oxygen concentration of 1 vol% or less, preferably 0.1 vol% or less) to prevent oxygen from interfering with the radical polymerization. This ensures that the radiation-curing process achieves both high productivity and reliable curing effectiveness.
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 improved adhesion to substrates and maintains releasability even under wet and heat conditions, providing a release sheet with enhanced long-term adhesion and reduced force required for separation.
Implementation Method 1
the radical polymerization of a (meth)acrylic-modified polysiloxane has an advantage such that it achieves very good curability
Implementation Method 2
a radiation-curing method is attracting attention as a manner of generating curing energy without heating
Data Source
AI summary
A radiation-curable organopolysiloxane composition comprising the components (A), (B) and (C): (A) organopolysiloxane represented by the formula (1), wherein at least one of R1 is a (meth)acryloyl group-containing organic group, a is an integer of 2 or more, a, b, c and d satisfy an equation, 2≤a+b+c+d≤1,000, and a ratio of the total number of the hydroxyl group and the hydroxyl group-containing organic group to the total number of the (meth)acryloyl group-containing organic group, the hydroxyl group and the hydroxyl group-containing organic group is 0.4 or less; (B) compound having two or more acrylic groups in one molecule in an amount of 0.1 to 50 parts by mass, relative to 100 parts by mass of component (A); and (C) radical polymerization initiator in an amount of 0.1 to 15 parts by mass, relative to 100 parts by mass of component (A).