Compositions: coating or plastic – Coating or plastic compositions – Molds and mold coating compositions
Patent
1996-08-16
1998-01-20
Marcheschi, Michael
Compositions: coating or plastic
Coating or plastic compositions
Molds and mold coating compositions
106 2, 106 384, 106 387, 106243, 264213, 264333, 264338, 427133, B28B 736, B28B 738
Patent
active
057097399
DESCRIPTION:
BRIEF SUMMARY
RELATED APPLICATION
This application is a 371 of International Application Number PCT/EP94/04324, filed Dec. 27, 1994.
FIELD OF THE INVENTION
This invention is concerned with release agents for hydraulic binders, more especially for concrete formwork and molds, and relates to compositions for this purpose containing water-immiscible monohydric alcohols liquid at temperatures of 5.degree. to 15.degree. C. and emulsifiers in quantities of 0.5 to 5% by weight.
PRIOR ART
Release agents for concrete formwork and molds are known, for example, from the corresponding directive of the Main Committee "Betontechologie (Concrete Technology)" of the Deutches Beton-Verein e.V., Wiesbaden, 1980, or from H. Reul, Handbuch Bauchemie, Verlag fur chem. Industrie, Ziolkowsky AG, Augsburg, 1991, pages 319 et seq. They are applied to the formwork before introduction of the fresh concrete. When the formwork is removed, the release agents are intended to reduce adhesion between concrete and formwork and to prevent damage to the surface of the concrete and to the formwork. The number of times the formwork material can be reused is supposed to be increased in this way.
The release agents generally contain an oil component and various additives, for example rustproofing agents, antioxidants, antipore agents, preservatives, wetting agents, adhesion promoters, and emulsifiers. Various classes of substances and mixtures thereof, for example mineral oils or white oils, waxes, triglycerides based on vegetable or animal oils or fats or fat derivatives, are used as the oil component.
For hydraulic binders, the release agents are used with particular advantage in the form of an aqueous emulsion. For this particular application, the release agents generally contain emulsifiers, such as soaps, ethoxylated fatty acids and ethoxylated alkylphenols or petroleum sulfonates in quantities of around 10 to 30% by weight, based on the oil component. The release agents are not normally delivered to the point of use as an emulsion, but instead in the form of a concentrate which is diluted immediately before use.
The release agents in use today have various disadvantages. Mineral oils or white oils are not sufficiently biodegradable as the oil component. Although triglycerides based on native raw materials, for example rapeseed oil, are readily biodegradable, they have relatively high viscosities which are unfavorable for practical application. In addition, saponification of the oil by alkaline constituents of the concrete can result in the precipitation of Ca soaps, a phenomenon known as dust formation, which can cause adhesion problems during subsequent processing of the concrete. Fatty acid esters show similar behavior. It has already been proposed to remedy the situation by using fatty alcohol distillation residues. Unfortunately, it has been found that these compounds can only be partly used as the oil component, as described for example in DD-A5 290 439. According to this document, the oil component consists of 80 to 90% by weight of mineral oil to which 4 to 10% by weight of a mixture of saturated and unsaturated wax esters containing 32 to 36 carbon atoms, saturated and unsaturated fatty alcohols containing 24 to 32 carbon atoms and hydrocarbons of the type obtained as residue in the distillation of fatty alcohols are added. In addition, the wax esters present in the mixture can saponify, thus giving rise to the adhesion problems described above.
GB 1,294,038 describes release agents based on aliphatic, saturated or unsaturated alcohols and a cationic emulsifier. The quantities disclosed in the Examples are well above 10% by weight, based on the fatty alcohol.
EP-A 561 465 proposes emulsifiable release agents for hydraulic binders based on fatty acid esters of polyols which do not contain any H atoms in the .beta.-position to the OH group. Higher aliphatic monohydric alcohols may also be added to the esters. The esters or mixtures thereof with the alcohols are emulsified by addition of an emulsifier. The quantities disclosed in the Example
REFERENCES:
patent: 3354180 (1967-11-01), Ekiss et al.
patent: 5100697 (1992-03-01), Nielsen
patent: 5374303 (1994-12-01), Hoorn
Beton-technologie (Concrete Technology) of the Deutches Beton-Verein e.V., Wiesbaden, 1980 (no month).
Handbuch Bauchemie, Verlag fur chem. Industrie, Ziolkowsky AG, Augsburg, 1991, pp. 319 et seq. (no month).
RAL UZ 64 "Biolobisch schnell abbaubare Schmierstoffe und Schalole (Rapidly Biodegradable Lubricants and Stripping Oils", Jun. 1991.
Prof. Dr. Jurgen Falbe Prof. Dr. Manfred Regitz, Rompp Chemie Lexikon, Georg Thieme Verlag Stuttgart-New York, 1990, p. 1667 (no month).
Demmering Guenther
Friesenhagen Lothar
Heck Stephan
Koehler Michael
Komp Horst-Dieter
Henkel Kommanditgesellschaft auf Aktien
Jaeschke Wayne C.
Marcheschi Michael
Ortiz Daniel S.
Wood John Daniel
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