Silicone-Polyoxamide Additives for Thermoplastic Clarity

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Solution Overview

Problem

Conventional process additives for thermoplastics like polypropylene and styrene-butadiene copolymer films used in food packaging suffer from melt fracture and surface haze due to their fluidic nature and refractive index differences, making them difficult to process and blend effectively, and they lack mechanical strength and handling ease.

Innovation Solution

The use of silicone-polyoxamide process additives with a refractive index close to the thermoplastic, allowing for reduced extrusion melt defects and improved haze reduction, while maintaining mechanical strength and ease of handling in pellet form, through a composition comprising a silicone-polyoxamide process additive and a thermoplastic with specific weight ratios and processing methods.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional process additives (fluoropolymer, siloxane) are used in thermoplastic extrusion, then melt fracture is reduced and surface haze is improved, but internal haze increases due to droplet formation and refractive index differences

Engineering Contradiction:

Improvesurface hazeVSAvoidinternal haze

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent changes the refractive index parameter of the process additive by selecting specific fluoropolymer types (such as polyvinylidene fluoride with refractive index 1.43-1.47) that closely match the thermoplastic substrate (polypropylene with refractive index 1.45-1.50). This parameter matching prevents light scattering at the additive-thermoplastic interface, thereby eliminating internal haze while maintaining the melt fracture reduction benefits

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies local quality by ensuring the process additive has specific local properties (refractive index, molecular weight, viscosity) that are optimized for the specific thermoplastic being processed. The additive is formulated to have comparable rheological properties to the thermoplastic, creating a homogeneous local environment that prevents phase separation and droplet formation

Inventive Principle:

Principle #3Local quality

2Reliability

If siloxane process additives are used to reduce melt fracture, then processing improvement is achieved, but handling difficulty increases due to fluidic nature and low glass transition temperature

Engineering Contradiction:

Improvemelt fracture reductionVSAvoidhandling ease

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent employs fluoropolymer process additives that are designed as stable, solid pellets at ambient conditions, eliminating the handling issues of fluidic siloxane additives. These additives maintain their physical form during storage and handling but become effective during the extrusion process, providing a practical solution that is easy to handle and dose accurately

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent changes the physical state parameter of the process additive by selecting fluoropolymers with higher glass transition temperatures and appropriate melting points, allowing the additive to be handled as a stable solid or pellet at ambient conditions while still providing melt fracture reduction during the high-temperature extrusion process

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If process additives are used to improve extrusion properties, then melt fracture is reduced, but processing pressure increases

Engineering Contradiction:

Improvemelt fracture reductionVSAvoidprocessing pressure

Core Design Contradiction:

Manufacturing precisionVSStress or pressure

Solution Approach 1:

The patent optimizes the molecular weight and viscosity parameters of the fluoropolymer process additive to match the thermoplastic substrate. This parameter matching ensures that the additive does not create excessive viscosity or resistance during extrusion, thereby reducing processing pressure while still providing effective melt fracture reduction through refractive index matching

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 silicone-polyoxamide additives effectively reduce extrusion melt defects and haze in thermoplastics, enhancing physical properties and processing conditions, achieving improved clarity and mechanical strength in extruded articles.

Implementation Method 1

PP has a refractive index ranging from 1.45 to 1.5. SBC has a refractive index ranging from 1.5 to 1.59. The refractive index difference between the silicone-polyoxamide process additive and the thermoplastic is less than about 0.07

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentEP2370521B1Silicone polyoxamide process additives for high clarity applications

Publication Date: 2016.08.17 3M INNOVATIVE PROPERTIES CO

AI summary

There is provided a silicone-polyoxamide process additive for use in high clarity applications, articles made using the silicone-polyoxamide process additive, and methods for making these articles.