Perforated Back Sheet for High-Chloride Gypsum Board Adhesion

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Solution Overview

Problem

Conventional gypsum boards face adhesion issues due to high concentrations of extraneous salts, particularly chloride salts, which reduce the bonding between the board core and cover sheets, making it difficult to use lower quality synthetic gypsum sources effectively.

Innovation Solution

Incorporating a plurality of perforations in the back cover sheet of the gypsum board to facilitate the migration of chloride salts away from the interface between the board core and the cover sheets, thereby improving adhesion and allowing the use of gypsum sources with high salt concentrations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If high concentration chloride salt gypsum is used in the board core, then the usability of lower quality gypsum sources is improved, but the adhesion between board core and cover sheets deteriorates

Engineering Contradiction:

Improveusability of gypsum sourcesVSAvoidadhesion between board core and cover sheets

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The harmful chloride salts are extracted from the interface region between the board core and cover sheets through the perforations in the back cover sheet. This allows the use of high chloride salt gypsum in the board core while removing the salts from the critical bonding interface, thereby maintaining adhesion despite using lower quality gypsum sources.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The perforations in the back cover sheet act as an intermediary mechanism that facilitates the migration of chloride salts away from the bonding interface. This intermediary structure enables the system to tolerate high chloride salt concentrations in the gypsum source while preserving the adhesion function.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If conventional gypsum board manufacturing is used without perforations, then the manufacturing process is simple, but adhesion deteriorates when high salt concentration gypsum is used

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoidadhesion performance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The back cover sheet is segmented with perforations that create multiple pathways for chloride salt migration. This segmentation approach maintains the overall integrity of the cover sheet while providing numerous exit routes for harmful salts, improving adhesion without significantly complicating the manufacturing process.

Inventive Principle:

Principle #1Segmentation

3Reliability

If chloride salts are removed from the gypsum source, then adhesion improves, but the usability of lower quality gypsum sources deteriorates

Engineering Contradiction:

ImproveadhesionVSAvoidgypsum source options

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The harmful chloride salts present in low quality gypsum sources are converted from a detrimental factor into a manageable condition. By providing migration pathways through perforations, the salts that would normally cause adhesion failure are instead channeled away from the bonding interface, allowing the use of previously unusable gypsum sources while maintaining adhesion.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 perforations enhance the adhesion between the board core and the cover sheets, even with high salt concentrations, enabling the effective use of lower quality gypsum sources that would otherwise be unsuitable, resulting in improved bonding performance and increased usability of these sources in gypsum board production.

Implementation Method 1

Incorporating a plurality of perforations in the back cover sheet of the gypsum board to facilitate the migration of chloride salts away from the interface between the board core and the cover sheets

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentUS11186066B2Gypsum board from gypsum having high level of chloride salt and a perforated sheet and methods associated therewith

Publication Date: 2021.11.30 UNITED STATES GYPSUM CO

AI summary

Gypsum boards formed from synthetic gypsum and other gypsum sources having high chloride salt concentrations. The gypsum boards may include a set gypsum board core layer between a front and back paper cover sheets. The back paper cover sheet has a plurality of perforations extending therethrough. Methods of making the gypsum boards, and a wall system for employing the gypsum boards, are also provided. The concentration of the chloride anion in aqueous gypsum slurry used to make the set gypsum board core layer and to perform the methods of the invention may range from about 500 ppm to about 3000 ppm, typically from about 500 ppm to about 2000 ppm per 1,000,000 parts by weight calcium sulfate hemihydrate, more typically from about 500 ppm to about 1500 ppm per 1,000,000 parts by weight calcium sulfate hemihydrate.