Gypsum boards with glass fiber reinforcements having a titanate or zirconate coupling coating

Abstract

A bond is created between a gypsum matrix and titanium or zirconium based coupling coating applied onto a glass fiber during gypsum board cure. The commercially available titanium or zirconium based coupling has a generic formula of the type [RO-}-nTi—[—OXR′Y]4-n or [RO-}-nZr—[—OXR′Y]4-n. These coupling compositions chemically bond to glass fibers by replacing the —OH groups present on the glass fibers in aqueous solutions with Ti—O or Zr—O bonds. In order to bond with calcium ions in hydrated gypsum crystals, the X functionality is selected to be a phosphate or pyrophosphato group. The bond between the glass fiber and the titanium or zirconium based coupling composition is due to the formation of a monolayer, while the bond between the hydrated gypsum crystal and the coupling composition is intermittent due the acicular structure of gypsum crystals. The titanium or zirconium based coupling composition coating on glass fibers bonded to the gypsum matrix results in load transfer between the gypsum matrix and the glass fibers, resulting in improved flexure strength and nail pullout resistance. The Titanate/Zirconate can also be used as a board mechanical properties enhancing agent without addition of glass fiber.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to glass fibers used in products for building construction; and more particularly, to a titanium or zirconium containing sizing or coupling composition and a glass fiber coupling coating process that bonds to a gypsum matrix in a gypsum board, thereby providing superior flexure strength and nail pullout resistance. [0003] 2. Description of the Prior Art [0004] Glass fibers are commonly used in the production of a wide variety of articles, notably including many building products including gypsum boards. The fibers are employed in many forms, including individual fibers, strands containing plural fibers, and rovings. These fiber products, in turn, may be used in discrete form or they may be assembled into woven and non-woven fabric or mats and incorporated into a gypsum matrix. [0005] Glass fiber filaments or strands that are to be incorporated in a gypsum matrix, either as individual fi...

AI Technical Summary

Benefits of technology

[0035] The quantity of coupling agent is selected to be in the range of 0.01 to 3 weight percent of the glass fiber weight, providing a thin layer of coating on the glass fiber's external surface, sufficient to provide a bond. Excessive amounts of coupling agents do not provide the gypsum board strength improvement since multiple layers interfere with each other. During the gypsum cure cycle, the excess water is evaporated and the coupling layer coated glass fiber comes into intimate contact with acicular gypsum crystals,...

Problems solved by technology

However, actual mat properties are generally found to be unpredictable.

As a result, formulation of sizing has generally been carried out by trial and error.

Moreover, the multiple constituents used in sizing, and their interacting roles, make it especially difficult to predict or achieve fully satisfactory properties in glass fibers dispersed into a gypsum matrix, either as fibers or as finished products like non-woven mats.

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