In-Mold Indicia Printing Plastisol Parts
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Plastisol products do not readily accept conventional adhesive labels or printing, lacking permanent bonding and precision in indicia application, which is a challenge for decoration and labeling in applications like rotational molding of buoys and watercraft components.
Innovation Solution
A method involving a plastisol graphic transfer is prepared by casting a base layer, printing indicia, and applying a top layer, which is then cured and applied to a rotational mold using a high solvent content adhesive, allowing the transfer to dry and fuse into the molded part, enabling precise and permanent indicia application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional adhesive labels or printing inks are applied to plastisol products, then decoration and labeling can be attempted, but permanent bonding is not achieved and indicia placement precision is poor
Solution Approach 1:
The patent combines the indicia application process with the rotational molding process by incorporating pre-printed plastisol sheets into the mold before adding liquid plastisol. The indicia-bearing sheet and the molding process are merged into a single integrated operation, allowing the indicia to become permanently bonded as the plastisol cures in-mold.
Solution Approach 2:
The indicia are pre-printed onto the plastisol sheet before the molding process begins. This preliminary action of printing allows for high-resolution indicia placement with precise positioning, eliminating the need for post-molding labeling or painting operations.
2Ease of manufacture
If design pieces are cut from preformed plastisol sheets and applied to the mold interior surface, then large object decoration is achieved, but precision and resolution of indicia images are insufficient
Solution Approach 1:
The patent changes the physical state and application method of the indicia material. Instead of cutting and manually placing design pieces, the invention uses pre-printed plastisol sheets that are applied as continuous sheets to the mold interior. This parameter change in application method enables both ease of manufacture and high precision indicia placement.
3Reliability
If the mold is heated before applying design pieces, then adhesion of design pieces to mold surface is improved, but the process complexity increases
Solution Approach 1:
The patent merges the adhesion preparation step with the standard molding process by applying liquid plastisol over the indicia-bearing sheet during the normal charging sequence. The heating step is combined with the curing phase of rotational molding, eliminating separate adhesion-promoting heating steps and reducing overall process complexity.
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 method allows for the permanent and precise application of high-resolution indicia images onto plastisol products, ensuring durable and accurate decoration during the rotational molding process.
Implementation Method 1
applying a high solvent content adhesive to the mold surface
Implementation Method 2
permitting the applied transfer to dry over a short interval
Implementation Method 3
curing the final transfer
Data Source
AI summary
This invention is a method for the precise placement of indicia with high resolution into the wall of a hollow-form, molded plastisol part. The method includes the steps of preparing a plastisol graphic transfer by casting a base layer of plastisol onto a carrier sheet, printing indicia with pigmented plastisols onto the base layer of plastisol to form a graphic transfer, and over printing the graphic transfer with a body layer of plastisol. After each layer of plastisol is deposit, the layer cured by heating before depositing the next layer and the transfer is heated to cure the final, body layer. The transfer is applied to a selected inside surface of a conventional rotational mold by applying a high-solvent-content adhesive to the mold surface, stripping the plastisol transfer from the carrier sheet and applying it against the adhesive coated mold surface, and pressing the transfer against the adhesive-coated surface of the mold, permitting the applied transfer to dry over a short interval and then continuing with an otherwise conventional rotomolding or slush molding process to obtain a molded hollow form part having the indicia permanently fused into the wall of the part.