Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2000-09-22
2002-09-10
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S249000, C524S247000, C524S556000, C106S505000, C106S823000
Reexamination Certificate
active
06448317
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to gelled adhesives, tile adhesives and dry-set mortars and methods for their formulation, and more particularly to a dual function gelled mastic adhesive which can be used “as is” for the installation of wall and ceiling tile, and can be mixed with a Portland cement powder to form a powerful latex-modified dry-set mortar having the added utility of a crack suppressive adhesive and functioning as a waterproofing membrane.
2. Brief Description of the Prior Art
Takahashi et al, Japan patent JP 58017157A discloses a transparent gel that is prepared by using a highly water-absorbing synthetic resin (e.g. modified polysodium acrylate) as a gelling agent and adding to the gel at least one additive selected from among ethylenediamine-tetraacetic acid (or its disodium salt), triisopropanolamine, ethanolamine, n-propyl gellate, nickel dibutyldithiocarbamate, phenyl-alpha-naphthylamine and benzophenone derivative in an amount of 5 wt % or less, to prevent lowering of viscosity caused by sunlight, etc.
Bowden, U.S. Pat. No. 4,204,876 discloses a method of using thixotrophic compositions to carry additives in the liquid portion of cementitious products as a method of attempting to gain homogeneity of the end product.
Johansen et al, U.S. Pat. No. 5,558,708 discloses a “two-component” system and method for dispensing pigment in cement based composition using a predetermined and prepackaged amount of an aqueous liquid pigment carrier component that is mixed with a predetermined and prepackaged amount of a powder cement component to obtain standardized colors. Although this system has merit it does not solve the problem of color and additive variance within batches because the pigments and additives commonly, and usually very rapidly, settle out of the liquid leaving a virtually clear liquid at the top and a concentration of additives and pigments at the bottom of the container. Vigorous stirring, shaking, or otherwise mixing of the pigment carrier component after storage and prior to combining with the powdered materials is required. Relatively large quantities of suspension enhancing agents are required that serve no other purpose. These agents mask, dilute, change, or otherwise compromise the final composition. Additionally, products with large quantities of suspending agents must be sold in small containers to facilitate shaking by the end user.
Johansen et al, U.S. Pat. No. 5,846,315 disclose a method for preparing a pigment dispersing pigment cement composition comprising water, pigment, a suspension enhancing agent and latex polymer solids. Two or more prepackaged compositions of an aqueous liquid pigment component is mixed with a prepackaged amount of a dry powder cement component to obtain cement composition with a uniform and standardized color. The suspension control agents, viscosity control agents, etc., two or more of which are required, are thoroughly mixed together prior to combining with the prepackaged dry powder cement. Agents that merely increase the viscosity of the aqueous component sufficient to carry the desired additives preclude their use in water in calciferous materials.
Johansen et al, U.S. Pat. No. 5,855,665 disclose a system and method for producing pigmented cement compositions that use significant percentages of only marginally effective suspension enhancing agents. Vigorous shaking, stirring, or otherwise mixing is still required which also limits container size to that which can be conveniently handled by workmen. Furthermore, the significant concentrations of suspension enhancing agents and dispersants required in the aqueous coloring composition can be deleterious to the makeup and strength of the end product. Additionally, the setting aids required are essential because the products also contain chemicals that compromise setting. These materials can also be detrimental to the ultimate strength of the final mix. This system also requires the mixing of additional water into the prepackaged pigmented cement compositions.
Mastics are sticky adhesives that are composed of bonding agents and carriers. The carrier may be water as in latex-based mastic adhesives or may be solvents as in petroleum based mastics. The petroleum-based mastics are now being used far less frequently because of the release of volatile organic compounds into the air and the environmental restrictions associated therewith. Mastics cure by the evaporation or absorption of the carrier which requires special considerations when installing impervious tile on backing that may limit carrier loss. The mastic adhesives can “skin over” around the margins of each tile thus preventing the loss of the carrier by evaporation and the mastic may virtually never set thereby causing weak bonds and job failures.
Dry-set mortars are Portland cement compositions that adhere by a chemical reaction between the Portland cement and water and therefore no evaporation is necessary or desired for hardening or “setting” to take place. In fact, they will “set” under water. These mortars are commonly referred to as “thinset” or “dry-set” mortars. Though somewhat accurate, the terms are commonly used interchangeably. Dry-set mortar is defined in the American National Standards Institute (ANSI) Specifications 118. 1, C-2.1 as a water-retentive Portland cement mortar, which eliminates the necessity of soaking either the tile or the backing surfaces prior to installation. Dry-set mortars have a much higher bond and compressive strength than mastic adhesives. Thus, tile installed with mortars are less likely to pop off, are more resistant to impact, and can support more weight than those installed with mastic adhesives. These are the primary reasons that mastic adhesives are reserved for wall and ceiling tile installation.
Upon the addition of water to dry Portland cement, tricalcium silicate rapidly reacts to release calcium ions, hydroxyl ions, and a large amount of heat. Heat is evolved with cement hydration. This is due to the making and breaking of chemical bonds during hydration. The reaction continues producing calcium and hydroxyl ions until the system becomes saturated. Once this occurs, the calcium hydroxide begins to crystallize. Simultaneously calcium silicate hydrate begins to form. Ions precipitate out of solution accelerating the reaction of tricalcium to calcium and hydroxide ions (Le Chatlier's principle).
The formation of the calcium hydroxide and calcium silicate hydrate crystals provide “seeds” upon which more calcium hydrate can form. The calcium silicate hydrate crystals grow thicker and interlock each other making it more difficult for water molecules to reach the tricalcium silicate not yet hydrated. The speed of the reaction is now controlled by the rate at which water molecules diffuse through the calcium silicate hydrate.
Only calcium silicates add to the strength of Portland cement. Tricalcium silicate is responsible for most of the early strength (first 7 days). Dicalcium silicate, which reacts more slowly, contributes only to the strength at later times. The other major components, tricalcium aluminate and tetracalcium aluminoferrite do not contribute significantly to the strength of the end product. The only contribution of tetracalcium aluminoferrite is to lend the gray color to cement (if it is removed, white Portland cement results).
Every component must be hydrated and the rate of hydration of any one is affected by the varying concentration of the others. The rates of hydration of the most important components of Portland cement, in the first few days, from fastest to slowest, are: (1) tricalcium aluminate, (2) tricalcium silicate, (3) tetracalcium aluminoferrite, and (4) dicalcium silicate. The importance of complete hydration of all components of Portland cement can therefore easily be seen.
Components of Portland cement that do not contribute significantly to the strength of the final product do hydrate and tie up water before the major strength components are hydrated and the strength of the
Collins James R.
Collins Jock R.
Kaiser Conard E.
Egwim Kelechi C.
Roddy Kenneth A.
Wu David W.
LandOfFree
Dual function gelled mastic adhesive and gelled mastic... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Dual function gelled mastic adhesive and gelled mastic..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Dual function gelled mastic adhesive and gelled mastic... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2901653