Hot Melt Labeling of Plastic Bottles via Segmented Adhesive Strips
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Solution Overview
Problem
Hot melt labeling of large empty plastic bottles often results in unsightly wrinkling, bulging, or deformation due to the bottles' expansion during filling, which existing methods fail to prevent effectively.
Innovation Solution
The method involves applying first glue strips for initial attachment and second glue strips for final attachment on labels, with the first strips not covering the entire label height and the second strips positioned between overlapping label layers, allowing for longitudinal movement of the bottle and preventing deformation by allowing the label to slide over the bottle wall.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the first glue strips cover the entire label height for secure initial attachment, then the label attachment stability is improved, but the label deformation (wrinkling, bulging) worsens due to bottle expansion during filling
Solution Approach 1:
The first glue strip is segmented to cover only a portion of the label height, specifically excluding the top region. This segmentation allows the lower part of the label to be securely attached while the upper part remains free to move and accommodate bottle expansion, thus resolving the contradiction between attachment stability and deformation prevention
Solution Approach 2:
Different regions of the label are given different qualities: the lower region has strong adhesive bonding for stability, while the upper region has no adhesive coverage allowing movement. This local differentiation of properties enables simultaneous achievement of secure attachment and deformation avoidance
2Manufacturing precision
If the label is tightly fixed to the bottle for proper positioning, then the label positioning accuracy is improved, but the label deformation during filling worsens
Solution Approach 1:
The adhesive coverage is segmented vertically, with the first glue strip covering only the lower portion of the label. This ensures proper positioning accuracy in the glued region while allowing the unglued upper region to move freely during filling, preventing deformation
Solution Approach 2:
The label attachment system transitions from a static fully-fixed state to a dynamic partially-fixed state. The first glue strip provides fixed positioning where needed, while the uncovered regions provide dynamic movement capability to accommodate dimensional changes during filling
3Strength
If the second glue strip is applied directly on the bottle surface for final attachment, then the label fixation strength is improved, but the label sliding capability worsens
Solution Approach 1:
The second glue strip is positioned in the overlapping region between label layers, utilizing the third dimension (depth/layering) rather than applying glue directly on the bottle surface. This allows the glue to bond label layers to each other while leaving the outer label surface free to slide over the bottle during filling
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
This approach ensures that only the label areas directly glued to the bottle wall follow its expansion, preventing undesirable creases and bulges, while maintaining a stable attachment and sliding properties, thus preventing deformation during product filling.
Implementation Method 1
sheet-shaped labels are first separated from an endless label strip provided by the roll in a cutting unit, sucked onto a continuously rotating vacuum transfer cylinder
Implementation Method 2
hot melt labeling of empty bottles made of plastic... labels being provided with first glue strips for initial attachment and second glue strips for final attachment, in particular by the glue strips on the labels being produced by selective application of hot glue
Data Source
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AI summary
This document describes a method for labeling, and in particular hot melt labeling, empty plastic bottles, as well as a corresponding labeling machine. Labels with adhesive strips for initial and final application are provided, and the labels are wound onto the empty bottles in a self-overlapping manner, starting from the initial application point. Because the adhesive strips for initial application do not extend over the entire height of the label, but rather leave gaps above and/or below them for sliding towards the empty bottles, and because the adhesive strips for final application are positioned between overlapping layers of the labels and without contact with the empty bottles, relative movement of the label with respect to the empty bottle in the longitudinal direction is possible. This prevents undesirable deformation of the label after a filling process.