Molded Painted Product Manufacturing Process
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Solution Overview
Problem
The existing manufacturing processes for molded footwear soles are complex, expensive, and result in products that are delicate and aesthetically impaired due to surface deformations and the vulnerability of painted surfaces, especially when using silk-screened sheets which do not meet market requirements for aesthetics and durability.
Innovation Solution
A manufacturing process involving a transparent plastic film painted on one side with polyurethane or acrylic paints, cut into sheets, and used in molding to ensure the painted side adheres to the molded product, covering surface imperfections and providing a protective layer, while the unpainted side adheres to the mold for vacuum compaction, resulting in a durable and aesthetically pleasing sole.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If silk-screened sheets are used to avoid painting, then manufacturing complexity is reduced, but aesthetics and durability deteriorate
Solution Approach 1:
The patent applies preliminary action by pre-painting the plastic sheet before molding. The decorative pattern and protective layer are applied in advance to a flat sheet, which is then molded into the final 3D product. This eliminates the need for post-molding painting operations while ensuring high aesthetic quality and durability, as the paint is applied to a smooth flat surface rather than a complex 3D shape.
2Productivity
If silk-screened sheets are used, then painting step is eliminated, but the product becomes extremely delicate and vulnerable to damage
Solution Approach 1:
The patent uses composite materials by combining the plastic sheet with a paint layer and optionally a protective coating layer. The paint layer serves both decorative and protective functions, while the protective coating (such as clear coat or varnish) adds additional resistance to abrasion, chemicals, and environmental factors. This composite structure significantly enhances the durability and strength of the final product compared to using plain silk-screened sheets.
3Ease of manufacture
If plastic material is molded directly, then manufacturing is simplified, but surface deformations and imperfections occur
Solution Approach 1:
The patent applies preliminary action by preparing the plastic sheet with the desired decorative pattern and protective coating before molding. The sheet is pre-painted and pre-finished while in its flat state, where surface imperfections can be easily corrected. After molding, the pre-applied paint and protective layers conform to the 3D shape, providing a high-quality surface finish without requiring post-molding surface treatment.
Solution Approach 2:
The patent applies parameter changes by controlling the timing and conditions of paint application. The paint is applied to the plastic sheet at a specific stage (before molding) when the material is in a flat, accessible state. The painting parameters (such as paint viscosity, application method, and drying conditions) are optimized for flat surfaces, ensuring uniform coverage and high aesthetic quality that would be difficult to achieve on complex 3D molded surfaces.
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 process reduces surface imperfections, enhances durability, and meets market aesthetics by ensuring the painted layer is protected and uniformly applied, making the product more practical, versatile, and cost-effective.
Implementation Method 1
a vacuum system suitable for removing the air from the mold
Implementation Method 2
a heated plunger for melting and compacting the plastic material
Data Source
Figure 1~4
Figure 2~3
Figure 5
AI summary
A manufacturing process of a molded painted product comprises the following steps: provision of a sheet (5) of transparent plastic material with a first side (50) painted by applying a layer of paint (3); arrangement of the sheet (5) in a cavity (61) of a mold (60); fixing of the sheet; extraction of the air; injection or pouring of a plastic material (8) in the cavity (61) of the mold, in such a way that the plastic material (8) adheres to the first side (50) of the sheet with the layer of paint (3); closure of the mold and polymerization of the plastic material (8); opening of the mold and extraction of a product (100) from the mold with a body of molded plastic material (8), wherein the first side (50) of the sheet with the layer of paint (3) adheres to the body of the product and the second side of the sheet is directed towards the exterior.