Chilled Mold Vacuum Process for Multilayer Electrical Articles
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Solution Overview
Problem
The off-mold, latent cure method for molding electrical articles faces challenges such as material solidification in undesired locations and air entrapment, leading to defects and unacceptable article quality due to the elastomeric nature of materials and layer deformation during injection.
Innovation Solution
A process involving a mold with deformable pre-molded polymeric sheets and a removable hollow core with vents, where the mold is chilled and a crosslinkable thermoplastic polymer is injected under high pressure, followed by vacuum application to remove trapped air, resulting in a less than fully cured multilayered article that is then removed from the mold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a chilled mold is used to cool the article inside the mold, then geometrical integrity is achieved, but material solidification in undesired locations occurs
Solution Approach 1:
The patent changes the temperature parameter of the mold from conventional high temperature to chilled (below melting temperature of the polymer), which enables geometrical integrity to be achieved during cooling while controlling where solidification occurs. This parameter change resolves the contradiction by allowing the article to maintain its geometric form without unwanted solidification defects.
Solution Approach 2:
The patent applies preliminary action by pre-chilling the mold before injection and maintaining it at controlled low temperature throughout the process. This preliminary cooling action ensures that the material solidifies in the desired locations (forming the article structure) rather than in undesired locations, resolving the contradiction between geometrical integrity and unwanted solidification.
2Reliability
If vacuum is applied to remove trapped air, then air entrapment is prevented, but process complexity increases
Solution Approach 1:
The patent applies pneumatic principles by using vacuum pressure to remove trapped air from the mold cavity during injection. The vacuum system creates negative pressure that draws air out through vents, preventing air entrapment defects. This pneumatic approach resolves the contradiction by ensuring high article quality through effective air removal, accepting the necessary increase in process complexity as a trade-off for defect prevention.
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 effectively prevents air entrapment and deformation, producing defect-free multilayered electrical articles with improved geometrical integrity and quality.
Implementation Method 1
The molding cycle is thus controlled by the efficiency of cooling the article inside the mold and achieving appropriate green strength for demolding
Implementation Method 2
Drawing a vacuum on the mold cavity through the vent in the removable, hollow core before, during and/or after the polymer has been injected into the mold
Implementation Method 3
Injecting at a pressure from 1 MPa to 300 MPa a viscous, crosslinkable, thermoplastic polymer into the mold cavity
Data Source
Figure 1A~3
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AI summary
A process for making a multilayered article, the process comprising the steps of: (A) Providing a mold comprising: (1) A mold housing comprising (a) at least one injection port, and (b) defining a mold cavity within which are positioned two deformable, pre-molded polymeric sheets; and (2) A removable, hollow core equipped with at least one vent, the removable, hollow core positioned between and space apart from the two polymeric sheets; (B) injecting under high pressure a viscous, crosslinkable, thermoplastic polymer into the mold cavity between the two polymeric sheets and around the removable core, (C) Drawing a vacuum on the mold cavity through both the vent in the mold housing and the vent in the removable, hollow core before, during and/or after the polymer has been injected into the mold; (D) Forming a less than fully cured multilayered article in the mold cavity; and (E) Removing the less than fully cured multilayer article from the mold cavity.