Styrenic Block Copolymer Adhesive for Flexible Packaging Lamination
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Solution Overview
Problem
Current polyurethane-based lamination processes for flexible packaging are hindered by long crosslinking times, requiring storage for several days to weeks, and pose toxicological risks due to aromatic primary amines, while offering limited productivity and unsuitability for films with printed information.
Innovation Solution
A multilayer film using a styrenic block copolymer-based adhesive composition with tackifying resins, suitable for high-speed coating and lamination processes, eliminating the need for crosslinking reactions and avoiding toxic compounds, allowing immediate cutting and ensuring cohesion comparable to polyurethane-based films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyurethane-based lamination processes are used, then good adhesion and flexibility are achieved, but long crosslinking times (several days to weeks) are required and toxicological risks arise from aromatic primary amines
Solution Approach 1:
The patent changes the chemical composition parameters of the adhesive from polyurethane-based to styrenic block copolymer-based (SBS, SIBS, SEBS, SEPS) with specific styrene content (15-40 wt%) and elastomer content (60-85 wt%). This fundamental material substitution eliminates the need for crosslinking reactions while maintaining adhesion quality, reducing processing time from days/weeks to hours, and eliminating toxic aromatic amine byproducts
Solution Approach 2:
The patent employs a short-living adhesive system (styrenic block copolymers) that does not require long-term crosslinking like polyurethane systems. The adhesive achieves sufficient bonding strength in a short time frame (hours rather than days/weeks), enabling rapid production cycles and eliminating the need for extended storage or aging periods
2Reliability
If polyurethane-based lamination processes are used, then good adhesion is achieved, but productivity is limited due to long storage requirements
Solution Approach 1:
The patent changes the adhesive chemistry from slow-crosslinking polyurethane to fast-setting styrenic block copolymers that achieve adequate bonding within hours. This parameter change in reaction kinetics and material composition enables high-speed production lines while maintaining reliable adhesion, directly improving productivity without sacrificing bond quality
Solution Approach 2:
The patent enables continuous production by eliminating the interruption caused by long crosslinking storage periods. The styrenic block copolymer adhesive allows lamination and subsequent processing to proceed continuously without waiting for crosslinking completion, maintaining productive action throughout the manufacturing process
3Loss of information
If printed elements are present on the film surface, then information display is improved, but lamination becomes problematic with polyurethane glues due to toxicological concerns
Solution Approach 1:
The patent changes the adhesive material composition to styrenic block copolymers that do not produce aromatic primary amine byproducts during bonding. This chemical parameter change eliminates the toxicological hazard while allowing lamination of films with printed surfaces, preserving both information display and consumer safety
Solution Approach 2:
The patent converts the previously harmful polyurethane crosslinking reaction (producing toxic aromatic amines) into a beneficial alternative using styrenic block copolymers that bond without harmful byproducts. The new adhesive system transforms the lamination process from a potentially hazardous operation to a safe one, especially when printing is involved
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 solution enables high-speed production of flexible packaging with improved cohesion and safety, eliminating the need for lengthy crosslinking and reducing toxicological risks, while maintaining the quality and transparency required for food packaging.
Implementation Method 1
a multilayer (or complex) film which comprises at least 2 thin layers of material linked together by a layer of an adhesive composition based on a Styrenic block copolymer
Data Source
Figure 1~2
AI summary
Multilayer film comprises at least two thin layers of material bonded together by a layer of thickness of not exceeding 10 mu m, and an adhesive composition comprising 30-70% of a mixture of styrenic block copolymers, 5-75% of a triblock copolymer having e.g. styrene-isoprene-styrene, and 25-95% of a diblock copolymer comprising e.g. styrene-isoprene, where the content of global styrenic unit of the mixture is 10-40%, and 30-70% of at least one tackifying resins. Multilayer film comprises at least two thin layers of material bonded together by a layer of thickness of not exceeding 10 mu m, and an adhesive composition comprising 30-70% of a mixture of styrenic block copolymers 5-75% of a triblock copolymer comprising styrene-isoprene-styrene, styrene isoprene butadiene, styrene butadiene styrene, styrene ethylene butylene styrene, and styrene-ethylene-propylene-styrene block copolymer, 25-95% of a diblock copolymer comprising styrene-isoprene, styrene-b-butadiene-b-isoprene, styrene isoprene butadiene, styrene butadiene, styrene-ethylene-butylene, and styrene ethylene propylene, where the content of global styrenic unit of the mixture is 10-40%, and 30-70% of at least one tackifying resins. An independent claim is included for a process for continuous preparation of multilayer film comprising a step of coating by the adhesive composition of a first thin layer of material, in which the composition, pourable by heating at a suitable temperature, is extruded by a coating device without contacting with the thin layer, in the form of a substantially continuous layer, which is then contacted with the surface of the thin layer, then a step of laminating a second thin layer, on the first coated thin layer produced in coating step.