Moisture-Absorbing Sheet With Calcium Oxide Particles
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Solution Overview
Problem
Conventional hygroscopic materials for electronic devices are either powdery, making them difficult to handle, or have high hygroscopicity that leads to immediate moisture absorption, causing issues when attached at normal temperatures and humidity, and they are not suitable for long-term applications.
Innovation Solution
A moisture-absorbing sheet with a hygroscopic molded body containing calcium oxide-based particles and fibrillated fluororesin, designed to have a controlled weight increase ratio over time, allowing for effective moisture absorption at normal temperatures and humidity levels while maintaining hygroscopicity for an extended period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a hygroscopic molded article with high hygroscopicity is used, then moisture absorption capability is improved, but the article reaches saturation quickly and is not suitable for long-term applications
Solution Approach 1:
The invention changes the particle size parameter of the hygroscopic agent from fine powder to granular form with specific surface area of 0.03 to 0.3 m²/g. This parameter change reduces the initial hygroscopic reaction speed while maintaining total moisture absorption capacity, enabling both rapid initial absorption and sustained long-term performance without quick saturation
Solution Approach 2:
The invention creates a composite molded article combining hygroscopic agent particles with a binder material forming a matrix structure. This composite structure prevents particle detachment while controlling moisture absorption kinetics, achieving both handling ease and sustained hygroscopic function over time
2Ease of operation
If a hygroscopic molded article with high hygroscopicity is attached at normal temperature and humidity, then ease of operation is improved, but moisture absorption occurs immediately and reaches saturation
Solution Approach 1:
By changing the specific surface area parameter to 0.03-0.3 m²/g and controlling particle size distribution, the invention moderates the initial moisture absorption rate. This allows the article to be handled and attached under normal temperature and humidity conditions without immediate saturation, while still maintaining effective moisture absorption capability for long-term use
3Productivity
If a powdery hygroscopic agent is used, then hygroscopicity is improved, but it is difficult to place in electronic device and particles may fall off
Solution Approach 1:
The invention forms a composite molded article where hygroscopic agent particles are embedded in a binder material matrix. This structure maintains the high surface area and hygroscopic activity of the particles while preventing detachment and making the article easy to handle and install in electronic devices
Solution Approach 2:
The molded article forms a cohesive structure that can be designed as a sheet or molded component, providing mechanical integrity while maintaining hygroscopic function. This structure prevents particle fall-off and facilitates easy placement in device housings
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 sheet effectively demonstrates moisture absorbability with controlled initial low hygroscopicity, preventing immediate saturation and ensuring long-term performance, reducing the risk of solvent adsorption and device malfunction.
Implementation Method 1
a hygroscopic molded body containing a resin component and a hygroscopic agent, wherein (1) calcium oxide-based particles having a specific surface area of 0.03 m2/g to 0.3 m2/g are contained in the hygroscopic molded body
Implementation Method 2
particles having a specific surface area of 0.03 m2/g to 0.3 m2/g are contained in the hygroscopic molded body
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3(a)~3(b)
AI summary
[Problem] To provide a moisture-absorbing sheet which can effectively exhibit hygroscopicity even when a hygroscopic molded article is attached at a normal temperature and under a normal humidity, and also can maintain hygroscopicity for a long period of time. [Solution] A moisture-absorbing sheet including a hygroscopic molded article containing a resin component and a hygroscopic agent, wherein (1) calcium oxide-based particles having a specific surface area of 0.5 m2/g to 20 m2/g and an average particle diameter of 0.5 µm to 50 µm are included as the hygroscopic agent; (2) a fibrillated fluororesin is included as the resin component; and (3) the sheet has: (a) a weight increase ratio of 1% or less after being allowed to stand for 2 hours in an atmosphere at a temperature of 20°C and a relative humidity of 65%; and (b) a weight increase ratio of 5% or more after being allowed to further stand for 36 hours after being allowed to stand for 36 hours in an atmosphere at a temperature of 20°C and a relative humidity of 65%.