Method for manufacturing a hot-melt adhesive that is used in the production of recyclable textile products made of polypropylene
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Solution Overview
Problem
Existing textile product recycling methods face challenges in achieving sufficient dimensional stability and effective fibre anchoring due to inadequate adhesive properties, particularly in carpet products made from polypropylene, which often require pre-coating and mechanical deconstruction for recycling.
Innovation Solution
A method for manufacturing a hot-melt adhesive with a melt viscosity range of 10,000 to 120,000 mPa*s at 210°C, using comminuted polypropylene granules and peroxides to lower viscosity, applied by roller coating to bond isotactic polypropylene primary and secondary backing layers, ensuring strong fibre anchoring and recyclability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional adhesives are used to bond polypropylene backing layers, then fibre anchoring is achieved, but dimensional stability is insufficient and pre-coating is required
Solution Approach 1:
The patent modifies the adhesive composition by incorporating specific polypropylene-based polymers with controlled molecular weight and melt flow index, along with functional additives such as maleated polypropylene and polyethylene-polypropylene block copolymers. These parameter changes in composition and rheology enable the adhesive to simultaneously achieve strong fibre anchoring and maintain dimensional stability without requiring pre-coating steps.
2Ease of manufacture
If mechanical deconstruction is used for recycling, then component separation is achieved, but processing complexity and time increase
Solution Approach 1:
The patent employs a homogeneous polypropylene-based adhesive system that bonds all components (primary backing, secondary backing, fibres) using the same polymer family. This homogeneity enables direct mechanical recycling through simple shredding and melting without requiring complex separation processes, significantly reducing recycling time and processing complexity while maintaining material quality.
3Strength
If pre-coating is applied to improve fibre bonding, then additional bonding strength is achieved, but manufacturing steps and complexity increase
Solution Approach 1:
The patent combines the adhesive functions of fibre bonding, layer bonding, and dimensional stabilization into a single polypropylene-based hot-melt adhesive formulation. This merged adhesive system eliminates the need for separate pre-coating steps while achieving superior fibre bonding strength, thereby simplifying the manufacturing process and reducing overall complexity.
4Ease of operation
If aqueous dispersion is used for adhesive application, then ease of application is improved, but recyclability and material purity are compromised
Solution Approach 1:
The patent replaces aqueous dispersion adhesive systems with a polypropylene-based hot-melt adhesive system that applies adhesive properties through thermal activation rather than water-based chemistry. This substitution maintains ease of application through simple heat-activated spreading while ensuring full recyclability, as the hot-melt adhesive can be melted and separated with the polypropylene matrix during recycling processes, preserving material purity.
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 adhesive provides enhanced fibre bonding and pile anchoring with a delamination strength of at least 30N, allowing for direct mechanical recycling into high-grade products without prior processing, maintaining dimensional stability and enabling efficient recycling of polypropylene-based textile products.
Implementation Method 1
extrusion of the granules in the presence of peroxides in order to lower the viscosity to a melt viscosity from 10 000 mPa*s to 120 000 mPa*s at a temperature of 210°C
Implementation Method 2
The hot-melt adhesive obtained by the method according to the invention serves in particular as an adhesive in a textile product comprising a primary backing layer with yarns or fibres made of an isotactic polypropylene material and a secondary backing layer made of an isotactic polypropylene material, wherein the primary and secondary backing layers are firmly bonded together by said adhesive
Data Source
Figure 1
AI summary
The present invention relates to a method for manufacturing a hot-melt adhesive for textile products, wherein the method comprises the following steps: comminution of carpets made of isotactic polypropylene to polypropylene granules; extrusion of the granules in the presence of peroxides in order to lower the viscosity to a melt viscosity from 10 000 mPa*s to 120 000 mPa*s at a temperature of 210°C measured according to ISO 6721-10:2015.