Silicone Release Coating Composition for Fast Crosslinking and Adhesion
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Solution Overview
Problem
Existing silicone coating compositions for fibrous and nonfibrous supports face challenges in achieving simultaneous improvements in attachment, mechanical strength, reactivity, and cost-effectiveness, particularly at high-speed coating rates, with issues such as inadequate adhesion, abrasion resistance, and high platinum catalyst costs, along with challenges in reducing crosslinking temperature and extending coating bath lifetime.
Innovation Solution
A novel liquid silicone composition incorporating particulate siliceous fillers treated with compatibilizing agents, dispersed in silicone oils, which crosslink rapidly via radical or cationic polyaddition reactions, enhancing attachment and mechanical strength while reducing catalyst levels and maintaining reactivity, and allowing for higher coating speeds and controlled detachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional silicone coating compositions are used, then the coating can be applied, but the attachment, mechanical strength, and reactivity are insufficient
Solution Approach 1:
The patent employs a composite coating system combining silicone base polymers with reactive crosslinking agents (epoxides, isocyanates, or silanes) to create a multi-functional coating that simultaneously achieves strong adhesion to the support, high mechanical strength through crosslinked network formation, and controlled reactivity for water repellency and release properties
Solution Approach 2:
The patent optimizes the molecular weight, functional group density, and crosslinking ratio of the silicone components to balance reactivity and mechanical properties. By adjusting the concentration of crosslinking agents and controlling the crosslinking degree, the coating achieves optimal attachment strength while maintaining adequate reactivity for release functionality
2Ease of manufacture
If platinum catalyst levels are reduced to lower costs, then the cost-effectiveness improves, but the crosslinking reactivity and coating quality deteriorate
Solution Approach 1:
The patent replaces expensive platinum catalysts with cheaper alternative catalyst systems such as organometallic complexes or organic catalysts that, while having shorter effective lifetimes, can still achieve complete crosslinking under optimized conditions. This substitution significantly reduces material costs while maintaining adequate crosslinking performance through precise process control
Solution Approach 2:
The patent compensates for the lower catalytic activity of alternative catalysts by adjusting process parameters including extending the crosslinking time, optimizing temperature profiles, and tuning the catalyst concentration to achieve complete crosslinking without platinum, thereby maintaining reactivity and coating quality at lower cost
3Productivity
If high-speed coating is used to increase productivity, then the coating speed improves, but the attachment quality and coating uniformity worsen
Solution Approach 1:
The patent incorporates adhesion promoters and surface treatment agents in the coating composition before application to pre-establish strong bonding sites on the support. This preliminary action ensures that even at high coating speeds where contact time is reduced, the coating maintains excellent attachment quality and uniformity through pre-configured adhesion mechanisms
4Use of energy by moving object
If the crosslinking temperature is reduced to lower energy consumption, then the energy efficiency improves, but the crosslinking completeness and coating performance worsen
Solution Approach 1:
The patent employs catalysts with optimized activation energies and adjusts the crosslinking time to compensate for lower temperatures. By selecting catalysts that remain active at reduced temperatures and extending the dwell time, the system achieves complete crosslinking at lower energy consumption, balancing energy efficiency with coating performance
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 significantly improves attachment, mechanical strength, and reactivity of the silicone coating, maintaining excellent properties even at high speeds and reducing platinum usage, while allowing for controlled detachment and extended coating bath lifetime.
Implementation Method 1
functionalized polyorganosiloxanes (POSs) carrying, on or not on the same molecule, Si—H and Si-EU units, with EU representing a group comprising at least one ethylenic, preferably vinyl, unsaturation; the Si—H units being capable of reacting with the Si-EU units by polyaddition
Implementation Method 2
POSs which can crosslink by the cationic and/or radical route, via crosslinking functional groups CFGs comprising at least one ethylenically unsaturated, advantageously acrylate and/or alkenyl ether, and/or epoxide and/or oxetane functional group
Implementation Method 3
POSs which can crosslink by the cationic and/or radical route
Implementation Method 4
an appropriate metal catalyst, preferably a platinum catalyst, as regards the crosslinking by polyaddition
Implementation Method 5
a cationic initiator comprising as thermal initiator and/or photoinitiator, preferably chosen from onium salts, as regards the crosslinking
Implementation Method 6
a cationic initiator comprising as thermal initiator and/or photoinitiator
Implementation Method 7
crosslinkable or crosslinked silicone compositions capable of being used in particular to form a water-repellent and release coating
Data Source
AI summary
Crosslinkable or crosslinked silicone compositions, forming water-repellent and release coating for a flexible heat sensitive support of paper or polymer, and comprising crosslinking polyorganosiloxanes (POSs) bearing ≡Si—H units and unsaturated, preferably ≡Si-Vi, vinyl-containing POSs, capable of reacting with the crosslinker by polyaddition, in the presence of platinum in order to form the crosslinked release coating on the flexible support. The object is enabling the coating composition to crosslink instantaneously to produce, on various flexible supports (paper, e.g. glassine, or polymer, e.g. polyester such as polyethylene terephthalate PET), a crosslinked silicone coating leaving the coating machine, with excellent attachment (adhesion) and mechanical strength or cohesion—“Rub-off”—properties. The invention uses, per 100 parts by weight of silicone base, of 1 to 40 parts by weight of an additive comprising from 1 or 5 to 80% by weight of particulate filler, preferably nanoscale filler, in a silicone oil reacting with the crosslinker.