Rain Resistant Paper Sack With Hydrophobic Ply And Plastic Film Barrier
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Solution Overview
Problem
Paper sacks used for storing powdery materials like cement face challenges in maintaining strength, preventing moisture contamination, and ensuring efficient deaeration while being cost-effective and rain-resistant.
Innovation Solution
A multi-ply sack design featuring a hydrophobic outer paper ply, a highly porous inner paper ply, and a non-perforated, impermeable plastic film between the two, allowing air to escape through the top end during filling, which enhances strength, protects against moisture, and maintains filling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a free film is provided with slits or perforations to facilitate deaeration, then air venting capability is improved, but moisture barrier performance deteriorates
Solution Approach 1:
The patent extracts the deaeration function from the free film by providing a separate deaeration element (eyelet) that is permeable to air but impermeable to moisture. This allows the free film to remain intact and impermeable while air can escape through the dedicated deaeration element during filling.
Solution Approach 2:
The deaeration element acts as an intermediary component between the free film and the interior space. It provides a controlled pathway for air to escape while maintaining the moisture barrier integrity of the free film, thus mediating between the conflicting requirements of deaeration and moisture protection.
2Productivity
If Kraft paper of high porosity is used to achieve air permeability, then deaeration capability is improved, but sack strength deteriorates
Solution Approach 1:
The patent extracts the deaeration function from the sack wall material (Kraft paper) and assigns it to a separate deaeration element. This allows the Kraft paper to maintain high strength without requiring high porosity, while the deaeration element provides the necessary air permeability.
Solution Approach 2:
The patent applies local quality by making the deaeration element selectively permeable - permeable to air but impermeable to moisture. This localized property allows deaeration to occur at specific points without compromising the overall strength and moisture barrier of the sack structure.
3Reliability
If a plastic film is used as moisture barrier, then moisture protection is improved, but air venting capability deteriorates
Solution Approach 1:
The patent extracts the air venting function from the plastic film by providing a separate deaeration element. This allows the plastic film to remain impermeable to both air and moisture, while the deaeration element provides the necessary air venting capability during filling.
Solution Approach 2:
The deaeration element serves as an intermediary that allows air to pass through the otherwise impermeable plastic film structure. It provides a controlled pathway for air escape while maintaining the moisture barrier function of the plastic film.
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 design provides improved strength and moisture protection, enabling high filling rates and maintaining sack integrity under rain exposure, with the non-perforated film contributing to overall strength and preventing water and moisture ingress.
Implementation Method 1
the outer paper ply is sized with at least one hydrophobic size
Implementation Method 2
the Gurley porosity according to ISO 5636-5 of the inner paper ply is less than 10 s
Implementation Method 3
the plastic film provides an substantially uninterrupted barrier for liquid water, moisture and air between the inner paper ply and the outer paper ply
Data Source
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AI summary
The present disclosure provides a multi-ply sack (100) comprising an inner paper ply (101), an outer paper ply (102) and plastic film arranged between the inner paper ply (101) and the outer paper ply (102), wherein the outer paper ply (102) is sized with at least one hydrophobic size, the Gurley porosity according to ISO 5636-5 of the inner paper ply (101) is less than 10 s, the plastic film provides an substantially uninterrupted barrier between the inner paper ply (101) and the outer paper ply (102) and the sack (100) is configured to allow air (103) to escape from an interspace between the inner paper ply (101) and the plastic film through a top end (111) of the sack (100) during filling of the sack (100).