Multilayer Decorative Film Adhesion via Block Copolymer Substrate
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Solution Overview
Problem
Existing decorative films face challenges in adhering to various three-dimensional solid shapes due to material restrictions, high adhesive tackiness leading to contamination issues, and poor shape retention and handling properties, limiting their compatibility with different molding methods.
Innovation Solution
A multilayered film structure comprising a thermoplastic resin intermediate layer with specific properties, a thermoplastic polymer composition layer containing a block copolymer and polypropylene-based resin, and a decorative layer, allowing for high flexibility in material selection and molding methods while maintaining low-temperature adhesiveness and excellent handling properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional adhesive layer is used in the decorative film, then the film can be adhered to the molded product, but the adhesive flows due to molten resin during injection molding, reducing adhesive force
Solution Approach 1:
The patent extracts the adhesive function from a separate adhesive layer and integrates it into the substrate resin layer itself. The substrate resin layer is formed by a resin composition containing a block copolymer (polystyrene-polybutadiene-polystyrene) that provides inherent adhesive properties, eliminating the need for a distinct adhesive layer that would flow during injection molding.
Solution Approach 2:
The patent uses a composite resin composition in the substrate resin layer containing a block copolymer (polystyrene-polybutadiene-polystyrene) and optionally a polypropylene-based resin. This composite material provides both structural integrity and adhesive properties, allowing the decorative film to maintain strong bonding without requiring a separate adhesive layer that would flow during molding.
2Strength
If the adhesive layer is made more tacky to improve adhesion, then the film adheres better to the molded product, but contamination occurs due to excessive tackiness
Solution Approach 1:
The patent changes the chemical composition parameters of the substrate resin layer by incorporating a block copolymer (polystyrene-polybutadiene-polystyrene) with specific properties. This resin composition provides optimal adhesive strength through its molecular structure while maintaining surface properties that resist contamination, achieving a balance between adhesion and contamination resistance.
3Adaptability or versatility
If the decorative film is made more flexible to adhere to complex three-dimensional shapes, then it can contact various surfaces, but shape retention and handling properties deteriorate
Solution Approach 1:
The patent employs a composite resin composition in the substrate resin layer containing a block copolymer (polystyrene-polybutadiene-polystyrene) and optionally a polypropylene-based resin. This composite provides an optimal balance of flexibility for conforming to three-dimensional surfaces and structural integrity for shape retention and handling during the molding process.
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 multilayered film achieves strong adhesion and shape retention on various three-dimensional surfaces, enabling effective decorative molding across different methods with improved handling and adhesive properties, reducing contamination risks and material limitations.
Implementation Method 1
a thermoplastic polymer composition layer (Y), the adhesive strength of which is 15 N/25 mm or more, on each side thereof
Implementation Method 2
a molten resin of the same kind of the substrate resin layer is injection molded
Data Source
AI summary
The present invention relates to a multilayered film having a high degree of freedom regarding selection of a material and a decoration method, which is not only excellent in handling properties and low-temperature adhesiveness to adherends of various materials but also applicable to decorative molding of every sort in a three-dimensional solid shape, and a method for producing the same. The present invention provides a multilayered film including, as an intermediate layer (X), a thermoplastic resin layer having a bending rigidity of 60 to 30,000 kPa·mm3; a layer (Y) composed of a thermoplastic polymer composition on both surfaces of the intermediate layer (X), the thermoplastic polymer composition containing 0 to 50 parts by mass of a polypropylene-based resin (B) based on 100 parts by mass of a thermoplastic elastomer (A) that is a block copolymer containing a polymer block (a1) composed of an aromatic vinyl compound unit and a polymer block (a2) composed of a conjugated diene compound unit; and a decorative layer (Z) closely arranged on the surface of either one of the layers (Y). The present invention also provides a method for producing the multilayered film, including bringing the thermoplastic resin layer (Y) as a surface layer in a molten state into contact with a roll whose surface is made of a hydrophobic resin.