Hot Melt Pressure Sensitive Adhesive Composition with Random Polymer
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Solution Overview
Problem
Existing hot melt pressure sensitive adhesives (HMPSAs) face challenges in label applications due to high melt viscosities, which lead to poor processability, uneven coating, and reduced coating rates, making them difficult to use in standard compounding and coating processes, while also being costly due to the use of expensive solution polymerized thermoplastic polymers.
Innovation Solution
A hot melt pressure sensitive adhesive composition comprising a combination of non-thermoplastic random polymer and thermoplastic block polymer, with specific ranges of di-block content, styrene monomer content, and optional tackifiers and plasticizers, to achieve improved processability and adhesion characteristics, including a static shear time to failure of greater than 300 minutes and viscosity in the range of 10000 cps to 30000 cps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If hot melt pressure sensitive adhesives are used for packaging applications, then adhesive strength is improved, but melt viscosity becomes too high for label applications
Solution Approach 1:
The patent changes the chemical composition parameters of the adhesive by using specific block copolymers with controlled di-block content (40-70%) and styrene monomer content (15-45%), along with random copolymers and tackifiers in defined ratios. This parameter optimization reduces melt viscosity to 10,000-30,000 cps at processing temperature while maintaining adhesive strength, enabling both easy processing and effective bonding for label applications.
2Reliability
If solution polymerized thermoplastic polymers are used, then adhesive performance is improved, but cost increases
Solution Approach 1:
The patent creates a composite adhesive system combining block copolymers (5-50 wt%), random copolymers (5-25 wt%), and tackifiers (10-40 wt%). This composite approach uses cost-effective emulsion-polymerized and solution-polymerized materials in specific proportions to achieve the desired adhesive performance without relying solely on expensive solution polymerized thermoplastic polymers, thus reducing overall manufacturing cost while maintaining reliability.
Data Source
AI summary
A hot melt pressure sensitive adhesive composition is provided comprising at least one thermoplastic block polymer, and at least one non-thermoplastic random polymer. The hot melt pressure sensitive adhesive composition of the present invention demonstrates improved processability and desirable adhesion performance for label applications. Further, the hot melt pressure sensitive adhesive composition is economical and environmentally sustainable.