Mold Part Tilt Angle Eliminates Scale Pattern in Fluoropolymer Injection
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Solution Overview
Problem
Existing injection molding methods for thermoplastic fluoropolymers, such as those used in semiconductor manufacturing, often result in periodic irregularities (scale patterns) on the surface of molded articles due to interactions between the resin and the mold, which are problematic for clean surfaces required in semiconductor manufacturing, especially since traditional mold release agents can contaminate the surface.
Innovation Solution
A mold part with a surface that slides parallel to the molded article during removal, featuring an average tilt angle of 1.5° or higher, and a controlled drawing speed of 20 mm/sec or lower, eliminates the generation of periodic irregularities without using a mold release agent, ensuring a smooth surface for thermoplastic fluoropolymer injection molding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a mold release agent is applied to increase mold releasability, then the molded article can be easily removed from the mold, but the mold release agent becomes an impurity factor that contaminates the surface
Solution Approach 1:
The invention extracts and eliminates the mold release agent from the molding process entirely. Instead of using a release agent that contaminates the surface, the patent employs a mold part with a specific surface state (average tilt angle of 1.5° or higher in the sliding direction) that enables easy removal without any release agent, thus removing the harmful contamination source while maintaining ease of operation
Solution Approach 2:
The invention changes the surface geometry parameter of the mold part by controlling the average tilt angle in the sliding direction to be 1.5° or higher. This parameter change creates a surface state that facilitates easy removal of the molded article without requiring a mold release agent, thereby eliminating surface contamination while maintaining ease of operation
2Object-affected harmful factors
If the surface of the mold part is made very smooth (Ra of 0.02 to 0.20 μm), then protein and foreign matter do not adsorb on the inner wall, but periodic irregularities (scale pattern) still occur in the direction orthogonal to the drawing direction
Solution Approach 1:
The invention introduces asymmetry in the surface geometry by controlling the average tilt angle in the sliding direction to be 1.5° or higher. This asymmetric surface state prevents periodic irregularities (scale patterns) from forming in the direction orthogonal to the drawing direction, while maintaining smoothness to prevent foreign matter adsorption. The asymmetric tilt angle disrupts the periodic interaction between resin and mold surface that causes scale patterns
3Ease of operation
If a mold release agent is used for high temperature molding of fluoropolymer, then mold releasability is improved, but the release agent volatilizes and becomes defective or impurity particles
Solution Approach 1:
The invention extracts and eliminates the mold release agent from the high temperature molding process. By using a mold part with a specific surface state (average tilt angle of 1.5° or higher), the patent enables easy removal of the molded article without any release agent, thereby preventing volatilization and particle generation that would occur with conventional release agents at high temperatures
Solution Approach 2:
The invention replaces the mold release agent with a permanent surface state of the mold part itself. The surface with average tilt angle of 1.5° or higher is a durable, non-volatile property of the mold that provides release functionality without the harmful volatilization and particle generation associated with chemical release agents at high temperatures
Data Source
AI summary
Provided is a mold part which does not generate periodic irregularities (scale pattern) which appear in the direction orthogonal to the drawing direction (MD) of the mold part having a surface which slides parallel to a molded article when the molded article is removed from the mold after injection molding during injection molding of a thermoplastic resin (in particular, a thermoplastic fluoropolymer), an injection molding method using the same, and a molded article in which periodic irregularities (scale pattern) (which appear in the direction orthogonal to the drawing direction (MD) of the mold part) do not appear. The mold part is used for injection molding of a thermoplastic resin, and includes a surface which slides substantially parallel to a molded article when the molded article is removed from the mold after injection molding, wherein the average tilt angle in the sliding direction (MD) is 1.5° or higher.