Hot-Melt PSA Composition for Suppressing Rapid Gelling
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Solution Overview
Problem
Conventional solvent-free hot-melt pressure-sensitive adhesive (PSA) compositions face rapid gelling during melting, leading to non-uniform film thickness and poor appearance of the PSA layer, which affects adhesive performance.
Innovation Solution
A solvent-free hot-melt PSA composition comprising a base polymer, isocyanate crosslinking agent, and a specific tackifier represented by the formula R—[(CH3)2C6H2—(CH2O)n—CH2]m—OH, with controlled m and n values, suppresses rapid gelling and ensures uniform thickness and improved adhesive performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a solvent-free hot-melt PSA composition containing a crosslinking agent is heated to a melted state, then the composition attains adequate fluidity for film formation, but rapid gelling occurs and generates gelled substances in the PSA composition
Solution Approach 1:
A specific tackifier (aromatic hydrocarbon resin or terpene resin) is introduced as an intermediary substance to control the crosslinking reaction. The tackifier interacts with the crosslinking agent to regulate gelling speed, preventing rapid gelling while maintaining composition stability during the melting and film formation process.
Solution Approach 2:
The invention changes the chemical composition parameters by specifying particular types of tackifiers (aromatic hydrocarbon resin or terpene resin) and controlling their content ratios. This parameter adjustment modifies the reaction kinetics between the crosslinking agent and other components, thereby controlling gelling speed and preventing excessive gelling during heating.
2Ease of manufacture
If the PSA composition is heated for film formation, then the composition becomes fluid enough for coating, but gelling progresses rapidly causing non-uniform thickness and poor appearance
Solution Approach 1:
The specific tackifier acts as a mediator that modulates the crosslinking reaction rate. By selecting aromatic hydrocarbon resins or terpene resins with controlled molecular structures, the gelling process is slowed down to match the film formation timescale, ensuring uniform thickness and good appearance while maintaining ease of manufacture.
Solution Approach 2:
The invention adjusts compositional parameters by defining specific tackifier types and content ranges (5-20 parts by weight per 100 parts base polymer). These parameter changes optimize the balance between fluidity for coating and controlled gelling for uniform film formation, resolving the contradiction between ease of manufacture and manufacturing precision.
3Strength
If a crosslinking agent is added to improve adhesive performance, then the adhesive strength increases, but rapid gelling occurs during heating that degrades the PSA layer quality
Solution Approach 1:
The specific tackifier (aromatic hydrocarbon resin or terpene resin) serves as a controlling intermediary that regulates the crosslinking agent's reactivity. This intermediary role allows the crosslinking agent to provide adequate adhesive strength while preventing uncontrolled rapid gelling that would degrade PSA layer quality during the heating and film formation process.
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 enables the formation of a PSA layer with favorable adhesive strength, uniform thickness, and improved appearance, while reducing environmental impact.
Implementation Method 1
by heating the PSA composition containing the crosslinking agent after being formed as a film by coating, the PSA layer may be formed by the crosslinking reaction and drying progressing simultaneously
Implementation Method 2
the hot-melt PSA composition is formed as a film in a state of being melted by heating
Data Source
AI summary
Provided is a hot-melt pressure-sensitive adhesive composition which enables to form a pressure-sensitive adhesive layer without allowing the progression of rapid gelation at the time of heating and melting. The pressure-sensitive adhesive composition provided by the present invention is a solvent-free hot-melt pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition includes a base polymer, an isocyanate crosslinking agent, and a tackifier A represented by the following general formula (1):R—[(CH3)2C6H2—(CH2O)n—CH2]m—OH (1)(in the general formula (1), R is a hydrogen atom or a hydroxyl group, m is 9 to 16, and n is 0 to 3). A content of the tackifier A with respect to 100 parts by weight of the base polymer is 1 part by weight to 10 parts by weight.