Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Adhesive outermost layer
Patent
1996-10-07
1999-08-03
Chen, Vivian
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Adhesive outermost layer
428480, 428703, 428482, 523500, 523515, 525 5, 525437, 525445, 525447, 525448, 525452, 528302, 528303, 528304, 528306, 5283086, 5283087, B32B 1312, B32B 2706, B32B 2726, B32B 2736
Patent
active
059323442
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a cement retarder (cement hardening-retarder) which is useful for retardation of hardening of the surface of a hardenable or curable composition comprising cement, a cement retardative sheet as produced using the retarder, and their use.
BACKGROUND TECHNOLOGY
A cement retarder is categorized into a cement admixture (a cement additive) which is admixed with cement for the purpose of retardation of setting and hardening of mortar or concrete by means of retarding hydration of cement. With respect to a cement retarder, Japanese Patent Application Laid-open No. 172250/1989 (JP-A-1-172250) mentions lead oxide, boron oxide, borax, zinc chloride, zinc oxide, magnesium silicofluoride and other inorganic retarders, polyhydroxy compounds (sugar, an alcohol, methyl cellulose, ethyl cellulose, poly(vinyl alcohol), dextrin, etc.), poly(sodium acrylate), a hydroxycarboxylate, a lignosulfonate, gluconic acid or its salt, pyruvic acid, .alpha.-ketoglutaric acid or other keto acids, and other organic retarders. The purpose of the use of these cement retarders is to transport a ready-mixed concrete over a long period with suppressing hardening of the concrete in summer, and to mitigate a stress due to a temperature (heat) in a large-sized concrete structure.
The surfaces of molded articles and various buildings made from concrete are practically decorated with the use of aggregate exposed finish by washing (washing finish) technology which is categorized into plastering technologies. The washing finish technology is a technology for exposing a part of aggregate by washing immediately before hardening of the concrete and hence washing out mortar of the surface layer of the concrete. According to this technology, the washing should be conducted in an extremely limited period (timing) since opportunity for washing closely relates to the hardening rate (cure rate) of the concrete. Therefore, the technology is unsuitable for commercial production or large-sized building applications.
With respect to execution of tile works to a surface of concrete, a technology using a unit tile as produced by disposing and adhering plural of tiles on a surface of a tacky adhesive layer of a tacky adhesive tape has been proposed. According to this technology using the unit tile, tiles are applied by disposing the unit tile in a form or shuttering to which concrete is placed or deposited, pouring mortar into the form and curing the same, removing the hardened product from the form and taking off the adhesive sheet to expose the tiles on the surface of the concrete, and thereafter removing the cement reached and cured on the surfaces of the tiles to conduct surface finish. In the surface finish, the cured cement adhered to the tiles may practically be scraped by hand and this is an essential step for tile application (tile work) which is characterized in a beautiful and tiny surface. The work for removing the hardened cement adhered to tiles, however, takes much time and trouble and is complicated so that the cost for tile application increases and the removing treatment for hardened cement would cause damage or defect of surfaces of the tiles.
For the purpose of solving these problems, technologies have been proposed, which technologies comprise processing a surface of a concrete product or forming a pattern on the surface by inhibition of hardening of only the surface layer but no other part of the concrete with the application of a cement retarder which is categorized into cement additives. By way of illustration, a process has been proposed, which process comprises impregnating a retarder (hardening retarder) in paper, fixing the impregnated paper on the bottom of a form by means of applying or posting, depositing mortar into the form, and after hardening of the concrete, removing the concrete molded article from the form, and washing fresh mortar on the surface of the concrete which is in contact with the impregnated paper to expose aggregate and hence to obtain a natural feeling. Japanese Patent
REFERENCES:
patent: 4050943 (1977-09-01), Sondhe
patent: 4115336 (1978-09-01), Crouzet
patent: 5236975 (1993-08-01), Sekine
Ikemoto Yoshiyuki
Ikuta Toru
Chen Vivian
Daicel-Huels Ltd.
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