Biodegradable Polyester with Long Chain Branches for Paper Lamination

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Solution Overview

Problem

Conventional paper laminates with polyethylene polymers are difficult to recycle or dispose of due to the challenge of separating the polymer layer from the paper, leading to issues at the end of their life cycle.

Innovation Solution

A biodegradable polyester with long chain branches, produced through a reactive extrusion process using a polyester precursor with terminal functional groups, offering higher melt strength, adhesion to paper, and processability suitable for extrusion coating, allowing for the creation of a laminate product that can be composted and recycled.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional polyethylene is used for paper lamination, then good adhesion and processability are achieved, but recycling and disposal become extremely difficult

Engineering Contradiction:

ImproveprocessabilityVSAvoidrecycling difficulty

Core Design Contradiction:

Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The patent changes the chemical composition parameters of the polymer from conventional polyethylene to biodegradable polyester (PBAT/PBS) with specific molecular weight (200,000-500,000 g/mol) and viscosity characteristics, enabling both good processability and biodegradability for easy disposal/recycling

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite polyester formulations (PBAT/PBS blends) that combine the biodegradability of polyester with optimized rheological properties, creating a material that processes like polyethylene but degrades environmentally

Inventive Principle:

Principle #40Composite materials

2Strength

If biodegradable polyester with long chain branches is used, then melt strength and adhesion are improved, but viscosity control becomes more challenging

Engineering Contradiction:

Improvemelt strengthVSAvoidviscosity control

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The patent precisely controls molecular parameters including viscosity (800-1600 Pas at 180°C), molecular weight (200,000-500,000 g/mol), and branch concentration (0.1-5 mol%) to achieve optimal melt strength while maintaining processability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces a controlled amount of long chain branches (0.1-5 mol%) rather than full branching, providing sufficient melt strength enhancement while avoiding excessive viscosity increase that would compromise processing

Inventive Principle:

Principle #16Partial or excessive action

3Productivity

If high processing temperatures are used to maintain processing speeds, then productivity is maintained, but polymer degradation may occur

Engineering Contradiction:

Improveprocessing speedVSAvoidpolymer stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent optimizes the viscosity-temperature relationship by controlling molecular weight and branching, allowing processing at moderate temperatures (180-220°C) that maintain both high productivity and polymer stability without degradation

Inventive Principle:

Principle #35Parameter changes

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 biodegradable polyester exhibits improved melt strength, adhesion, and processability, enabling the production of laminates with reduced neck-in and high web stability, facilitating recycling and composting, and maintaining high processing speeds and temperatures, thus addressing the recycling challenges of conventional polyethylene-based laminates.

Implementation Method 1

specific reagents capable of reacting with these reactive sites, allow transformation of a few chains of the polyester precursor into isometric branches

Methodology Applied

Scientific EffectChemical reaction: Chemical Bonding

Implementation Method 2

Said reactive extrusion process is performed through the addition of a compound selected from peroxides, epoxides and carbodiimides

Methodology Applied

Scientific EffectFree radical reaction: Oxidation

Data Source

PatentEP2268698B1Biodegradable polyester, preparation process thereof and products comprising said polyester

Publication Date: 2019.04.24 NOVAMONT SPA

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Figure 2B~3A
Figure 3B~4A

AI summary

The invention relates to a biodegradable polyester, particularly suitable for extrusion coating, comprising units deriving from at least a diacid and at least a diol, with long chain branches (isometric with respect to the main chains of the polyester) and essentially gel-free, characterized by optimum adhesion to paper, excellent sealability and processability in extrusion coating systems. Said biodegradable polyester is obtainable through a reactive extrusion process starting from a substantially linear polyester precursor with defined viscosity and concentration of reactive sites which allow transformation of a few chains of the polyester precursor into isometric branches of this polyester. A further object of the present invention is a laminate product composed of at least a backing, preferably paper, and of at least a first layer composed of polyester according to the invention.