Hotmelt Adhesive Layer for Folder Groove Folding
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Solution Overview
Problem
Existing semi-finished products for jackets, folders, or boxes made from rigid paper or cardboard become rigid and difficult to fold due to pre-glued paper and finishing layers, resulting in a messy appearance with creasing and crumpling issues.
Innovation Solution
A semi-finished product with an uncoated sheet featuring a directly applied hotmelt adhesive layer, allowing for a finishing layer to be applied directly on the adhesive without intermediate layers, which reduces material usage and prevents groove rigidity, enabling smooth folding and minimizing creasing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If pre-glued paper and finishing layers are applied on the sheet, then the sheet provides adequate adhesion for the finishing layer, but the grooves become rigid and difficult to fold
Solution Approach 1:
The patent segments the adhesive application by using hotmelt adhesive only in specific zones (grooves and margins) rather than covering the entire sheet surface. This localized segmentation maintains adhesion where needed while preserving foldability in the groove areas, resolving the contradiction between adhesion strength and folding ease.
Solution Approach 2:
The patent changes the physical state and application parameters of the adhesive by using hotmelt adhesive applied directly to the sheet surface rather than pre-glued paper. This parameter change allows the adhesive to be present only where required, maintaining bonding strength while preventing the grooves from becoming rigid, thus resolving the contradiction between adhesion and foldability.
2Ease of manufacture
If pre-glued paper is coated on the sheet, then the finishing layer can be applied, but multiple layers create a messy appearance with creasing and crumpling
Solution Approach 1:
The patent extracts and removes the intermediate pre-glued paper layer from the traditional multi-layer structure. By eliminating this unnecessary intermediate layer and applying hotmelt adhesive directly to the sheet, the invention simplifies the layer structure to only what is essential, thereby preventing the messy appearance and creasing associated with multiple layers while maintaining finishing layer application capability.
Solution Approach 2:
The patent inverts the traditional approach by applying the adhesive directly to the sheet surface rather than pre-coating the paper. This inversion eliminates the need for intermediate layers and their associated covering and uncovering operations, directly achieving clean folds while maintaining the ability to apply the finishing layer.
3Ease of manufacture
If self-adhesive glue is used instead of hotmelt adhesive, then the adhesive can be applied, but the exposed glue will damage the cardboard or groove upon folding
Solution Approach 1:
The patent changes the adhesive type from self-adhesive glue to hotmelt adhesive, which has different physical and chemical properties. Hotmelt adhesive cures to form a flexible, non-damaging bond that does not compromise the groove integrity upon folding, whereas self-adhesive glue remains tacky and can damage the substrate. This parameter change in adhesive selection resolves the contradiction between ease of manufacture and groove integrity.
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 solution allows for easy and smooth folding of the product, reducing creasing and crumpling, and providing a clean finish by eliminating the need for pre-glued paper, thus enhancing the folding process and appearance of the final product.
Implementation Method 1
an uncoated sheet which on at least one side is provided with a layer of hotmelt adhesive which is directly applied on the sheet for applying a finishing layer directly on the hotmelt adhesive
Data Source
AI summary
An element for producing a jacket, folder or box, in which the element relates to a semi-finished product comprising a sheet which on at least one side is provided with a layer of hotmelt adhesive directly applied on the sheet for applying a finishing layer directly on the layer of hotmelt adhesive.