Multilayered Stretched Polyamide Film Adhesion
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Solution Overview
Problem
Conventional biaxially stretched polyamide films used for packaging have insufficient adhesive strength, particularly water-resistant laminate strength, which leads to separation when exposed to high temperatures or hydrothermal treatment, and existing solutions either increase production costs or result in defects like blocking and dot blanks during printing.
Innovation Solution
A multilayered biaxially stretched polyamide film comprising a base layer of 50-90% polyamide 6, an easily adhesive layer of 0-40% polyamide 6 copolymer, and an easily slippery layer with fine particles, laminated under specific stretching conditions to enhance tensile strength, laminate strength, and water-resistant properties without the need for coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a film surface is coated in a film manufacturing process to increase adhesive strength, then laminate strength is improved, but productivity is reduced and production cost increases
Solution Approach 1:
The polyamide 6/66 copolymer film inherently provides adhesive properties through its molecular structure and crystallization behavior during biaxial stretching, eliminating the need for external coating processes. The film serves its own adhesion function through self-organization of polymer chains and formation of adhesive bonds during the stretching process itself.
Solution Approach 2:
By controlling the copolymerization ratio of polyamide 6/66 (specifically 5-30 mass% polyamide 66 content) and adjusting biaxial stretching parameters (temperature, ratio, speed), the film achieves optimal adhesive strength without coating. The parameter optimization allows the material to exhibit enhanced adhesion through controlled crystallization and molecular orientation.
2Strength
If a film surface is coated in a film manufacturing process to increase adhesive strength, then laminate strength is improved, but production cost increases
Solution Approach 1:
The film structure itself provides the adhesive function through the polyamide 6/66 copolymer's inherent properties and biaxial stretching-induced molecular arrangement, eliminating the need for separate coating materials and processes, thereby reducing production costs while maintaining high laminate strength.
Solution Approach 2:
The invention uses a composite structure at the molecular level within the polyamide 6/66 copolymer, combining polyamide 6 and polyamide 66 segments to create a material with both mechanical strength and adhesive properties, eliminating the need for additional coating layers and reducing overall production costs.
3Strength
If a film surface is coated in a film manufacturing process to increase adhesive strength, then laminate strength is improved, but blocking and defects such as stripe and flaw occur
Solution Approach 1:
The film achieves adhesion through its own structural properties and controlled stretching process, avoiding external coating operations that introduce surface defects such as blocking, striping, and flaws. The self-organizing molecular structure during biaxial stretching creates a uniform adhesive surface without coating-related imperfections.
4Ease of operation
If polyamide 6/66 copolymer is used to improve sequential biaxial stretching property, then stretching property is improved, but heat resistance and dimensional stability at high temperatures are reduced
Solution Approach 1:
By optimizing the polyamide 66 content within the specific range of 5-30 mass% and controlling biaxial stretching parameters (temperature, stretch ratio, and speed), the film achieves both improved sequential biaxial stretching properties and maintained dimensional stability at high temperatures. The balanced composition prevents excessive softening while enabling smooth stretching.
Solution Approach 2:
The polyamide 6/66 copolymer structure creates local regions with different properties: polyamide 6 segments provide heat resistance and dimensional stability, while polyamide 66 segments enhance stretching properties. This local differentiation within the copolymer structure allows simultaneous achievement of both stretching performance and thermal stability.
5Ease of operation
If polyamide 6/66 copolymer is used to improve sequential biaxial stretching property, then stretching property is improved, but mechanical strength is reduced
Solution Approach 1:
By controlling the polyamide 66 content within 5-30 mass% and optimizing biaxial stretching parameters, the film achieves a balance where sufficient copolymer content improves stretching properties while maintaining high mechanical strength through the dominant polyamide 6 matrix structure.
Solution Approach 2:
The polyamide 6/66 copolymer acts as a composite material where polyamide 6 provides mechanical strength and polyamide 66 enhances stretching properties. The synergistic combination in specific ratios allows simultaneous achievement of both improved stretching behavior and maintained mechanical strength.
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 film achieves high water-resistant laminate strength, improved mechanical strength, and reduced coefficient of friction, preventing separation during hydrothermal treatment and enhancing printability while maintaining cost-effectiveness and defect reduction.
Implementation Method 1
a biaxially stretched polyamide film which is biaxially stretched, and comprises at least three layers composed of a polyamide resin composition
Implementation Method 2
an easily adhesive layer (layer B) on one side of the base layer (layer A)... excellent adhesiveness... excellent water-resistant laminate strength
Data Source
AI summary
A multilayered stretched polyamide film which is biaxially stretched, and comprises three layers composed of a polyamide resin composition and comprising layer B as an easily adhesive layer, layer A as a base layer, and layer C as an easily slippery layer in this order, wherein the film satisfies the following (1) to (4); (1) the layer A contains 50 to 90% by mass of polyamide 6 and 10 to 50% by mass of a polyamide 6 copolymer in which a ratio of a copolymerization component in the copolymer is 3 to 35% by mass; (2) the layer B contains 0 to 40% by mass of polyamide 6 and 60 to 100% by mass of the polyamide 6 copolymer in which a ratio of the copolymerization component in the copolymer is 3 to 35% by mass; (3) the layer C contains 70% by mass or more of polyamide 6 and 0.05 to 1% by mass of fine particles having an average diameter of 0.1 to 10 μm; (4) the film has tensile strength at break of 150 MPa or more both in MD direction and TD direction; and (5) the film has laminate strength of 3.3 N/15 mm or more.