UV-Curable (Meth)Acrylic Copolymer for Low-Temperature Coating
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Solution Overview
Problem
The existing pressure-sensitive adhesive compositions have high melt viscosity, requiring high temperatures for coating and lack sufficient resistance to adhesive residue when peeled from a base material, leading to contamination issues.
Innovation Solution
A (meth)acrylic copolymer containing a macromonomer and a monomer with specific constituent units, allowing for low temperature coatability and improved base material contamination resistance through UV irradiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a copolymer containing acrylic acid alkyl ester, unsaturated carboxylic acid, and benzophenone derivative is used as pressure-sensitive adhesive composition, then the adhesive can be cured by UV irradiation, but the melt viscosity is high requiring high temperature for coating
Solution Approach 1:
The patent changes the compositional parameters of the copolymer by specifying precise ranges for constituent units (acrylic acid alkyl ester: 70-95 mass%, unsaturated carboxylic acid: 5-30 mass%, benzophenone derivative: 0.1-10 mass%) and controlling the weight average molecular weight (10,000-500,000) to reduce melt viscosity while preserving UV curability. This allows coating at lower temperatures without sacrificing the UV curing function.
Solution Approach 2:
The patent creates a composite copolymer structure combining three functional components: acrylic acid alkyl ester for adhesive base properties, unsaturated carboxylic acid for polarity and adhesion, and benzophenone derivative for UV curing. This composite approach balances multiple functions while optimizing melt viscosity through synergistic interactions between components.
2Reliability
If the existing pressure-sensitive adhesive composition is used, then UV curing is achieved, but the resistance to adhesive residue (base material contamination resistance) is insufficient when re-peeled
Solution Approach 1:
The patent optimizes the content parameters of constituent units to control adhesive residue. By setting unsaturated carboxylic acid content at 5-30 mass% and benzophenone derivative at 0.1-10 mass%, the patent achieves sufficient crosslinking density for strong bonding while preventing excessive adhesive residue upon re-peeling, thus reducing base material contamination.
Solution Approach 2:
The patent introduces functional differentiation within the copolymer structure: acrylic acid alkyl ester provides bulk adhesive properties, unsaturated carboxylic acid enhances interfacial adhesion and crosslinking, and benzophenone derivative enables UV curing. This local functional differentiation allows the adhesive to exhibit different properties at different stages (application, bonding, curing, peeling) to minimize contamination.
3Reliability
If high melt viscosity composition is used, then UV curing capability is maintained, but low temperature coatability is poor
Solution Approach 1:
The patent changes the molecular weight parameter (weight average molecular weight: 10,000-500,000) and compositional parameters to reduce melt viscosity. This enables the adhesive to flow and coat properly at lower temperatures while maintaining sufficient molecular weight for adequate adhesion and UV curing capability after coating.
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 (meth)acrylic copolymer enables the formation of a pressure-sensitive adhesive layer with excellent holding power and resistance to base material contamination, even with low dose UV irradiation.
Implementation Method 1
a pressure-sensitive adhesive composition containing the (meth)acrylic copolymer, a pressure-sensitive adhesive obtained by curing the pressure-sensitive adhesive composition
Data Source
AI summary
There is provided a (meth)acrylic copolymer with which a pressure-sensitive adhesive layer exhibiting excellent low temperature coatability and exhibiting holding power and excellent base material contamination resistance even in a case of being irradiated with a low dose of UV irradiation can be formed. The (meth)acrylic copolymer of the present invention comprises a constituent unit a derived from a macromonomer and a constituent unit b derived from a monomer represented by Formula (b), where a content of the constituent unit b is 0.01% to 25% by mass with respect to a total mass of the (meth)acrylic copolymer. In Formula (b), RA and RB each independently represent an alkyl group, a carboxy group, or a halogen atom, n represents an integer of 0 to 5, m represents an integer of 0 to 4, and X represents a (meth)acryloyloxy group or a (meth)acryloyloxyalkyleneoxy group.