PET-PVA Multilayer Structure Adhesion via Copolymerization
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Solution Overview
Problem
The existing multilayer structures composed of polyethylene terephthalate (PET) and polyvinyl alcohol (PVA) resins face challenges in interlayer adhesion, particularly due to differences in shrinkage percentages and crystallinity, leading to delamination issues.
Innovation Solution
A multilayer structure is developed with specific PET and PVA resin layers, where the PET resin includes a dicarboxylic acid component with terephthalic acid and non-terephthalic acid dicarboxylic acid in a copolymerization ratio of 15-40 mol%, and the PVA resin has a structural unit with 1,2-glycol bonds and optional alkali metal or earth metal salts, reducing crystallinity and enhancing interlayer adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a polyvinyl alcohol resin with low melting point is used to enable melt-forming, then the appearance quality improves, but the interlayer adhesion between PET and PVA layers deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the PVA resin by introducing specific structural units (formula 1) with controlled R1 and R2 groups, and adjusting the copolymerization ratio of non-terephthalic acid dicarboxylic acid in the PET resin to 5-30 mol%, thereby modifying thermal and adhesive properties to simultaneously achieve good appearance and interlayer adhesion
Solution Approach 2:
The patent creates a composite multilayer structure combining modified PET resin with non-terephthalic acid dicarboxylic acid units and modified PVA resin with specific structural units, where the composite composition enables both low melting point for good appearance and enhanced interlayer adhesion through chemical bonding
2Reliability
If the crystallinity of PET and PVA layers is reduced to reduce shrinkage difference, then the interlayer adhesion improves, but the dimensional stability of the multilayer structure deteriorates
Solution Approach 1:
The patent precisely controls the crystallinity reduction by limiting the copolymerization ratio of non-terephthalic acid dicarboxylic acid to 5-30 mol% and controlling the structure of PVA resin structural units, achieving the optimal balance where shrinkage difference is reduced enough for adhesion but not so much as to compromise dimensional stability
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 solution significantly improves interlayer adhesion and delamination resistance by reducing the difference in shrinkage percentages between the PET and PVA layers, resulting in a more stable and durable multilayer structure.
Implementation Method 1
a multilayer structure which includes a layer consisting primarily of a polyethylene terephthalate resin and a layer consisting primarily of a polyvinyl alcohol resin, and is excellent in interlayer adhesion between these layers
Data Source
AI summary
A multilayer structure (feature (x)) comprising: (A) a layer consisting primarily of a polyethylene terephthalate resin which comprises a dicarboxylic acid component unit including terephthalic acid and a diol component unit primarily including ethylene glycol, wherein the dicarboxylic acid component further includes a non-terephthalic-acid dicarboxylic acid in a copolymerization ratio of 15 to 40 mol% based on the overall amount of the dicarboxylic acid component; and (B) a layer provided in stacked adjacent relation to the layer (A) and consisting primarily of a polyvinyl alcohol resin having a structural unit represented by the following general formula (1): wherein R1, R2 and R3 each independently represent a hydrogen atom or an organic group; X represents a single bond or a bond chain; and R4, R5 and R6 each independently represent a hydrogen atom or an organic group. With this arrangement, the multilayer structure is improved in interlayer adhesion between the layer (A) and the layer (B), and is highly resistant to delamination.