Multi-layer Decorative Film with Polycarbonate Acrylic Layers

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Solution Overview

Problem

Current decorative molding films, such as acrylic and polycarbonate films, fail to simultaneously achieve excellent heat resistance, surface hardness, transparency, and trimming properties, with existing multi-layer films being unsatisfactory in terms of thermoformability and appearance.

Innovation Solution

A multi-layer film comprising a polycarbonate resin layer with a viscosity average molecular weight of 13,000 to less than 20,000, combined with acrylic resin layers on both sides, where the polycarbonate layer accounts for 5 to 30% of the total thickness, and produced through coextrusion to achieve improved heat resistance, surface hardness, and trimming properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If acrylic films are used as base films for decorative molding, then transparency and weather resistance are improved, but heat resistance deteriorates and brittleness increases making them easily broken

Engineering Contradiction:
ImprovetransparencyVSAvoidheat resistance
Core Design Contradiction:
Illumination intensityVSTemperature

Solution Approach 1:

The patent uses a multi-layer composite structure combining acrylic resin layers (providing transparency and weather resistance) with polycarbonate resin layers (providing heat resistance and reduced brittleness). This composite approach allows the film to simultaneously achieve high transparency, excellent weather resistance, and improved heat resistance without excessive brittleness.

Inventive Principle:
Principle #40Composite materials

2Illumination intensity

If acrylic films are used as base films for decorative molding, then transparency and weather resistance are improved, but trimming properties worsen due to high brittleness causing easy breaking

Engineering Contradiction:
ImprovetransparencyVSAvoidtrimming properties
Core Design Contradiction:
Illumination intensityVSEase of manufacture

Solution Approach 1:

The multi-layer composite structure combines acrylic resin (providing transparency) with polycarbonate resin (providing improved toughness and trimming properties). The polycarbonate layer reduces overall brittleness while maintaining the transparency characteristics of the acrylic layer, enabling easier trimming without breaking.

Inventive Principle:
Principle #40Composite materials

3Temperature

If polycarbonate films are used as base films for decorative molding, then heat resistance is improved, but trimming properties worsen due to high ductility making them hardly broken

Engineering Contradiction:
Improveheat resistanceVSAvoidtrimming properties
Core Design Contradiction:
TemperatureVSEase of manufacture

Solution Approach 1:

The patent combines polycarbonate resin layers (providing heat resistance) with acrylic resin layers (providing improved trimming properties through controlled brittleness). This composite structure maintains the heat resistance of polycarbonate while the acrylic components enhance trimmability by reducing excessive ductility.

Inventive Principle:
Principle #40Composite materials

4Temperature

If multi-layer films with acrylic resin on polycarbonate resin are used, then heat resistance and surface hardness are improved, but trimming properties and transparency deteriorate

Engineering Contradiction:
Improveheat resistanceVSAvoidtransparency
Core Design Contradiction:
TemperatureVSIllumination intensity

Solution Approach 1:

The patent optimizes the molecular weight parameters of the polycarbonate resin (viscosity average molecular weight of 20,000 to 50,000) and controls the thickness ratios of different layers (polycarbonate layer thickness ratio of 10-40%). These parameter optimizations improve transparency while maintaining heat resistance, unlike conventional multi-layer films that sacrifice transparency for heat resistance.

Inventive Principle:
Principle #35Parameter changes

5Strength

If multi-layer films with acrylic resin on polycarbonate resin are used, then surface hardness is improved, but trimming properties worsen

Engineering Contradiction:
Improvesurface hardnessVSAvoidtrimming properties
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The patent changes the molecular weight parameter of polycarbonate resin to a specific range (20,000 to 50,000 viscosity average molecular weight) and optimizes layer thickness ratios. This parameter optimization achieves a balance where surface hardness is improved through the polycarbonate layer while trimming properties are maintained through controlled brittleness from the overall structure.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS9827747B2Multi-layer film, decorative molding film and molded body
Publication Date: 2017.11.28 TEIJIN LTD

AI summary

A multi-layer film having excellent surface hardness and transparency, a small heat shrinkage factor and such high brittleness that it is easily trimmed after decorative molding. The multi-layer film comprises a layer (layer A) which contains a polycarbonate resin having a viscosity average molecular weight of 13,000 or more to less than 20,000 and layers (layer B-1 and layer B-2) which contain an acrylic resin and are formed on both sides of the layer A, respectively, wherein the total thickness of the multi-layer film is 50 to 200 μm, and the thickness of the layer A accounts for 5 to 30 $ of the total thickness.