Method for producing a sanitary article
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Solution Overview
Problem
Existing methods for producing polymerized plastic consumer goods in hollow molds result in surface defects and shrinkage, leading to weakened products and increased material usage, which complicates production and increases costs.
Innovation Solution
A method using a sandwich-like structure with a core region of bubbles surrounded by a fully polymerized shell, utilizing two polymerization initiators activated at different temperatures to control polymerization and compensate for shrinkage, ensuring a smooth and dimensionally accurate surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If polymerization is carried out in a hollow mold, then the plastic product takes the desired shape, but shrinkage occurs during polymerization leading to surface quality loss
Solution Approach 1:
The mold cavities are pre-heated to a first temperature before polymerization begins, and then heated to a second higher temperature during the process. This preliminary and progressive heating action compensates for shrinkage before it fully occurs, maintaining surface quality on both visible and non-visible sides.
Solution Approach 2:
The invention changes the temperature parameter dynamically during polymerization - starting at a first temperature and increasing to a second higher temperature. This parameter change compensates for the shrinkage that occurs during polymerization, preventing surface defects while maintaining shape accuracy.
2Manufacturing precision
If the mold half facing the visible side is heated more intensely, then the visible side surface quality is improved, but the reverse side shows significant shrinkage signs
Solution Approach 1:
The invention applies different heating conditions to different locations - the mold half facing the visible side is heated more intensely (second higher temperature) while the reverse side receives less intense heating (first temperature). This local quality differentiation improves visible side surface quality while accepting some shrinkage on the non-visible reverse side.
3Manufacturing precision
If additional plastic monomer is refilled to compensate for shrinkage, then surface smoothness is improved, but material requirements and production costs increase
Solution Approach 1:
Instead of refilling after shrinkage occurs, the invention performs preliminary heating of the mold cavities to compensate for shrinkage in advance. This prevents volume reduction during polymerization, eliminating the need for additional monomer refilling and reducing total material requirements.
Solution Approach 2:
The invention converts the potentially harmful shrinkage effect into a beneficial outcome by using the shrinkage-driven temperature increase to trigger further polymerization. The shrinkage that would normally cause defects instead becomes the mechanism that activates the second polymerization initiator, improving cross-linking and surface quality without needing extra material.
4Strength
If product thickness is increased to compensate for shrinkage-induced strength weakening, then product strength is maintained, but manufacturing costs increase
Solution Approach 1:
The invention changes the temperature parameter during polymerization to compensate for shrinkage effects. By heating to a second higher temperature, the polymerization continues despite volume reduction, maintaining product density and strength without increasing thickness or material usage.
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
The method effectively prevents shrinkage and surface defects, reducing material requirements and production costs while maintaining product strength and stability, allowing for efficient, single-step manufacturing and easy recyclability.
Implementation Method 1
a polymerizable plastic material is polymerized using a first polymerization initiator activated by heating the mold parts to a first temperature and a second polymerization initiator activated by further heating the mold parts to a second, higher temperature
Implementation Method 2
heating the mold parts to a first temperature to activate the at least one low-temperature initiator to initiate polymerization of the reaction mixture; further heating the mold parts to a second, higher temperature to activate the at least one high-temperature initiator
Data Source
Figure 1~2
AI summary
The invention relates to a sanitary article (10), such as a shower tray, bathtub, washbasin, toilet seat, seat ring or bathroom furniture, floor or wall panel, apron for bathtub or household item, such as a chair, table, furniture, for example a sofa, made of an at least partially polymerized plastic material, wherein the sanitary article (10) comprises a sandwich-like structure with a core area (20) having bubbles (40) arranged inside the article (10), which is surrounded by a sheath area (30) made of fully polymerized plastic material, which forms a bubble-free plastic sheath with a smooth and dimensionally accurate surface contour, and a method for manufacturing such a sanitary article (10).