Nanometer Latex PSA with Monomodal Distribution
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional high solid content acrylic emulsion pressure-sensitive adhesives (PSAs) face stability issues due to agglomerate formation during polymerization, leading to reduced adhesion and peeling strength, particularly when using micrometer-scale particles with bimodal or multimodal particle size distributions.
Innovation Solution
A method is developed to create a high solid content, low-viscosity acrylic emulsion PSA composition with nanometer-scale latex particles using at least three anionic emulsifiers, achieving monomodal particle size distribution and high stability, by preparing a pre-emulsion with specific monomers and emulsifiers, followed by heat polymerization with a polymerization initiator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If micrometer scale particles with bimodal or multimodal particle size distribution are used to achieve high solid content, then productivity is improved, but stability deteriorates due to agglomerate formation during polymerization
Solution Approach 1:
The patent changes the particle size parameter from micrometer scale to nanometer scale (average particle diameter of 50-400 nm), and changes the particle size distribution from bimodal/multimodal to monomodal. This parameter transformation resolves the contradiction by enabling high solid content (60-80 wt%) while maintaining latex stability and preventing agglomerate formation during polymerization.
Solution Approach 2:
The patent uses a pre-emulsion polymerization method where micrometer-scale particles are first prepared, then used as seeds for subsequent nanometer-scale particle formation. This preliminary action allows control over the final particle size distribution, achieving monomodal nanometer-scale particles that provide both high solid content and stability.
2Stability of the object's composition
If excess amount of emulsifier is added to enhance stability, then stability is improved, but adhesion deteriorates
Solution Approach 1:
The patent optimizes the emulsifier concentration parameter to a specific range (0.5-5 wt% based on total monomer weight) and changes the particle size to nanometer scale. This combination allows achieving high stability without requiring excess emulsifier, thereby preventing adhesion deterioration while maintaining peeling strength and adhesive properties.
3Strength
If nanometer scale latex particles with monomodal particle size distribution are used to maintain peeling strength and adhesive strength, then strength is improved, but manufacturing precision deteriorates due to difficulty in controlling particle size distribution
Solution Approach 1:
The patent employs a two-stage polymerization process where micrometer-scale particles are first formed as seeds, then nanometer-scale particles are grown on these seeds. This preliminary action provides a template that guides uniform particle growth, achieving monomodal nanometer-scale distribution with average diameter of 50-400 nm, thereby maintaining both strength and manufacturing precision.
Solution Approach 2:
The patent uses micrometer-scale seed particles as an intermediary between the polymerization process and the final nanometer-scale product. These seeds mediate the growth process, ensuring uniform nucleation and growth that results in monomodal particle size distribution with narrow standard deviation (10-30 nm), achieving both desired strength properties and manufacturing precision.
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 resulting PSA composition exhibits improved stability, reduced agglomerate content, and enhanced adhesive and peeling strengths, with a solid content of 60% or greater and viscosity between 500 and 1500 cps, maintaining high sustainability and loop tack.
Implementation Method 1
at least three anionic emulsifiers cover polymer particulates
Implementation Method 2
at least three anionic emulsifiers cover polymer particulates including: (A) a (meth)acrylic acid ester monomer
Implementation Method 3
heat polymerization with a polymerization initiator
Implementation Method 4
heat polymerization with a polymerization initiator
Data Source
AI summary
Disclosed are an acrylic emulsion pressure-sensitive adhesive (PSA) composition and a method of preparing the same. The acrylic emulsion PSA composition with high solid content and high stability includes latex particles in which at least three anionic emulsifiers cover polymer particulates including: a (meth)acrylic acid ester monomer having a C1-C14 alkyl group as a main monomer; at least one monomer selected from the group consisting of a monomer having an allyl ester group, a vinyl ester group, an unsaturated ester group, or a mixture thereof, a cyano group containing monomer, an amine group containing monomer, and a styrenic monomer having a vinyl group, as an auxiliary monomer; a monomer having a carboxyl group and/or a hydroxyl group as a functional monomer; and a crosslinking agent, wherein the latex particles have a nanometer scale average particle diameter and monomodal particle size distribution.