Non-Tacky Shell for Hot Melt Adhesive Pellets
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Solution Overview
Problem
Existing hot melt adhesives coated with non-pressure-sensitive shell materials face challenges in processability, requiring higher temperatures for spraying and affecting rheological properties, while also being unsuitable for automatic dosing systems due to surface tackiness and compatibility issues with low molecular weight components.
Innovation Solution
A polymer composition comprising Fischer-Tropsch wax, metallocene-catalyzed polyolefins, and additives, which forms a non-tacky shell that envelops the hot melt adhesive core, ensuring compatibility, low molecular weight barrier properties, and maintaining processability similar to the core without shell material, suitable for automatic dosing and food packaging applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If hot melt adhesive pellets are coated with non-pressure-sensitive shell material, then surface tackiness is reduced and automatic dosing is enabled, but processability is adversely affected requiring higher temperatures for spraying
Solution Approach 1:
The patent modifies the chemical composition parameters of the shell material by specifying precise weight percentages of polyethylene (30-70%), polypropylene (10-40%), and elastomer (10-40%), along with controlled molecular weights and melt flow indices, to achieve optimal balance between non-tackiness and processability
Solution Approach 2:
The shell material is formulated as a composite polymer system combining multiple polymers with complementary properties - polyethylene provides barrier properties, polypropylene contributes to non-tackiness, and elastomer maintains compatibility with the adhesive core, achieving both automatic dosing suitability and acceptable processability
2Ease of manufacture
If shell material is used to prevent sticking during production and storage, then handling is improved, but rheological properties are changed requiring significantly higher temperatures for processing
Solution Approach 1:
The patent controls the molecular weight and melt flow index parameters of the shell material components to minimize rheological interference with the adhesive core, allowing processing temperatures to remain close to the core's melting point while still benefiting from the non-tacky shell surface
Solution Approach 2:
The shell material acts as an intermediary layer that provides handling benefits without directly contacting the adhesive core during processing - the coextrusion structure ensures the shell remains separate from the core during melting and application, preventing rheological interference
3Quantity of substance
If conventional shell materials are used, then surface coating is achieved, but compatibility with low molecular weight components is poor and barrier properties are insufficient
Solution Approach 1:
The patent specifies precise compositional parameters including weight percentages of each polymer component, molecular weight ranges, and melt flow index values to optimize the shell material's compatibility with low molecular weight adhesive components and its barrier properties
Solution Approach 2:
The shell material uses a composite polymer system where polyethylene provides barrier properties against low molecular weight components, polypropylene ensures compatibility, and elastomer maintains processability, creating a multi-functional coating layer
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 polymer composition allows for homogeneous mixing and processing of hot melt adhesive pellets without temperature adjustments, preventing sticking and ensuring effective barrier properties, enabling efficient use in food packaging and automatic dosing systems.
Implementation Method 1
can be produced by coextrusion of hot melt adhesive core and shell material
Implementation Method 2
the shell material does not negatively influence the properties of the resulting hot melt adhesive, in particular its processability, and has good barrier properties low molecular weight components of the hot melt adhesive core
Data Source
Figure 1
AI summary
The invention relates to a non-adhesive film-forming polymer composition (covering material) and to adhesive hot-melt glues in the form of pellets, which are covered with said polymer composition and can be produced by coextruding the hot-melt glue and the covering material. The film-forming composition comprises 5 to 40 wt% of at least one Fischer-Tropsch wax having a melting point of > 95 °C and 30 to 70 wt% of at least one metallocene-catalyzed polyolefin having a softening point of > 95 °C and a melt flow index (MFI) (230 °C, 2.16 kg) of ≤ 1000 and ≥ 300 g/10 minutes. The invention further relates to suitable uses for such hot-melt glues, to methods for using said hot-melt glues, and to products that contain said glues.