WO1998055283A1

WO1998055283A1 - Aqueous parting agent for concrete

Info

Publication number: WO1998055283A1
Application number: PCT/EP1998/003113
Authority: WO
Inventors: Horst-Werner Wollenweber; Hans-Georg Mainx; Hans-Jürgen SLADEK
Original assignee: Cognis Deutschland Gmbh
Priority date: 1997-06-05
Filing date: 1998-05-27
Publication date: 1998-12-10
Also published as: EP1007307A1; DE19723604A1

Abstract

The invention relates to novel aqueous parting agents for concrete, containing unsaturated fatty alcohols and ethoxylated and possibly propoxylated fatty acid esters. Said new agents are characterized in that they have high saponification stability and are present as stable, fluid emulsions even at low temperatures.

Description

"Aqueous concrete release agents"

The invention relates to aqueous concrete release agents based on selected oil bodies and emulsifiers, a process for their preparation and the use of the mixtures of selected oil bodies and emulsifiers for the production of aqueous concrete release agents.

Release agents for concrete formwork and molds are e.g. from the corresponding guideline of the main committee "Concrete Technology of the German Concrete Association eV, Wiesbaden (1980) as well as from H.Reul, Handbuch Bauchemie, Publishing House for Former Industry, Ziolkovows AG, Augsburg, 1991, pp. 319f. You are applied to the formwork before the fresh concrete is poured in and are intended to reduce the adhesion between the concrete and formwork when stripping, and to prevent damage to the concrete surface and formwork, thereby increasing the number of technically possible uses of the formwork material.

The release agents generally contain an oil component, as well as various additives, for example rust inhibitors, antioxidants, antipore agents, preservatives, wetting agents, spreading agents and emulsifiers. Various substance classes or their mixtures are used as the oil component, for example mineral oils or white oils, waxes, triglycerides based on vegetable or animal oils or fats or fat derivatives. The use of the concrete release agent in the form of an aqueous emulsion is particularly advantageous. If this application is desired, the release agents generally contain emulsifiers such as soaps, ethoxylated fatty acids and ethoxylated alkylphenols or petroleum sulfonates in amounts of about 10 to 30% by weight, based on the oil component. Usually, the release agents are supplied to the point of use not as an emulsion, but in the form of a concentrate which, B. is diluted immediately before use. The release agents used today have various disadvantages. Mineral oils or white oils are insufficiently biodegradable as an oil component. Triglycerides on a native basis, for example beet oil, are readily biodegradable, but they have relatively high viscosities which are unfavorable for use. In addition, saponification of the oil by alkaline components of the concrete can lead to the precipitation of calcium soaps, which can cause sanding, which can cause adhesion problems when the concrete is further processed. Fatty acid esters show similar behavior. It has already been proposed to remedy the situation by using distillation residues from fatty alcohol production, but it has been shown that these compounds can only be used in part as an oil component, as is described, for example, in DD-A5 290 439. The oil component used here is 80 to 90% by weight of mineral oil, to which 4 to 10% by weight of a mixture of saturated and unsaturated wax esters with 32 to 36 carbon atoms, saturated and unsaturated fatty alcohols with 24 to 32 carbon atoms and hydrocarbon is added. The wax esters present in the mixture can also saponify and thereby trigger the adhesion problems described above. European patent application EP-A 0 561 465 discloses mold release agents which contain esters of sterically hindered, polyfunctional alcohols as mandatory components. The concomitant use of mono-functional alcohols is described as a way of reducing the emulsifier content. British patent application GB-A 1 294 038 relates to a process for the production of concrete release agents in which monofunctional alcohols are used in combination with cationic surfactants.

The emulsifiers used for the production of aqueous emulsions are also not without problems in terms of application technology. Until now, relatively large amounts of emulsifier had to be used to prepare the emulsions, but this has a negative effect on the rain resistance of the release agents. In addition, if the emulsifier content is high, re-emulsification can take place at the interface with the alkaline cement, with part of the release agent penetrating into the surface of the concrete. These residues of release agent can later lead to the problems already mentioned with the adhesion of paints or plasters. There is therefore an increasing need for concrete release agents that are readily biodegradable without showing the disadvantages of previously known compounds such as high viscosity, surface defects or sanding. Another disadvantage is that the concrete release agents of the prior art have so far at best been classified in water hazard class 1. The requirements for an environmentally compatible concrete release agent are specified in the RAL UZ 64 "Rapidly biodegradable lubricants and formwork oils" from June 1991.

The object of the invention was therefore to provide concrete release agents with improved ecological compatibility, which are notable for high saponification stability and form stable, liquid emulsions even at low temperatures. The viscosity of the emulsions must also be so low that they can be sprayed without problems. Finally, uniform wetting combined with good adhesion to a wide variety of formwork materials must be guaranteed.

The invention relates to aqueous concrete release agents containing (a) unsaturated fatty alcohols and (b) ethoxylated and optionally propoxylated fatty acid esters, the fatty acid component being selected from branched or linear, saturated or unsaturated fatty acids having 5 to 30 carbon atoms and the alcohol component being selected from branched or linear, saturated or unsaturated monoalcohols with 1 to 5 carbon atoms and polyols with 2 to 6 hydroxyl groups and 2 to 12 carbon atoms.

Surprisingly, it has been found that the agents according to the invention have an improved rheology and storage stability compared to the prior art, especially in the range of low temperatures. The preparations are saponification-stable, free of shipping, show a strong network effect and also adhere to a wide variety of formwork materials. Another advantage is that the new agents are ecologically harmless and can therefore be classified in water hazard class 0 For the purposes of the invention, unsaturated fatty alcohols which preferably follow the formula (I) are used as the oil component (a),

R-OH (I)

in which R represents a completely or predominantly unsaturated hydrocarbon radical having 6 to 22, preferably 12 to 18, carbon atoms. Typical examples are palmoleyl alcohol, oleyl alcohol, elaidyl alcohol, petroselinyl alcohol, linolyl alcohol, linolenyl alcohol, gadoleyl alcohol and erucyl alcohol as well as their technical mixtures, such as those obtained in the high pressure hydrogenation of technical fatty acid methyl ester fractions to obtain the double bonds. Typical methyl ester mixtures which are suitable as starting materials for the production of the unsaturated fatty alcohols are those which are derived from beef tallow, old and new breed sunflower oil, old and new breed beet oil, linseed oil, peanut oil and the like. In addition, methyl esters based on predominantly saturated fats and oils, such as palm oil, palm kernel oil and / or coconut oil, can also be used, provided that the products are subsequently concentrated accordingly, as described, for example, in documents DE-C2 43 38 974, DE-Al 43 35 781, DE-Al 44 25 180 and DE-Cl 44 22 858 (Henkel) is described. The agents usually contain unsaturated fatty alcohols which have an iodine number in the range from 40 to 200, preferably 50 to 150 and in particular 70 to 100. The unsaturated fatty alcohols are generally present in amounts of 10 to 50, preferably 20 to 40% by weight, based on the composition.

The agents according to the invention contain alkoxylated fatty acid esters as second component (b). These fatty acid ester alkoxylates are known compounds which are described, for example, in US 2,678,935, US 3,539,518, US 4,022,808 or GB 1,050,497, the disclosure of which is also part of the present application.

The alkoxylated fatty acid esters can be prepared by all methods known to the person skilled in the art, for example by esterification of fatty acids with alkoxylated methanol, as described, for example, in US Pat. No. 3,539,518. However, this procedure is common with some Disadvantages connected, it runs in two stages, the esterification takes a very long time and the products are colored by the high reaction temperatures. In addition, fatty acid methyl ester ethoxylates produced in this way have relatively high OH numbers after the esterification, which can be problematic for some applications. Another possibility is the direct reaction of fatty acid esters with alkylene oxides in the presence of transition metal catalysts, as described in US Pat. No. 4,022,808.

However, the fatty acid alkyl ester alkoxylates are preferably prepared by heterogeneously catalyzed direct alkoxylation of fatty acid alkyl esters with ethylene oxide and / or propylene oxide on calcined or hydrophobized hydrotalcites. This synthesis method is described in detail in the laid-open publications WO 90/13533 and WO 91/15441, the disclosure of which is also part of the present application. The resulting products are characterized by a low OH number, the reaction is carried out in one step and light-colored products are obtained. The fatty acid alkyl esters used as starting materials can be obtained from natural oils and fats or produced synthetically.

The fatty acid esters contained in the agents according to the invention can contain propylene oxide groups in addition to ethylene oxide groups. They preferably contain between 2 and 30 moles of ethylene oxide per mole of ester. Mixed ethylene oxide / propylene oxide adducts can also be used. In the case of mixed ethylene oxide / propylene oxide adducts, it is possible to use both those compounds which have been reacted with a mixture of ethylene oxide and propylene oxide, and also compounds which have been reacted with ethylene oxide and propylene oxide in two separate steps. If esters containing propylene oxide are used, those compounds are preferred which contain between 1 and 10 moles of propylene oxide per mole of ester. The agents according to the invention preferably contain esters which have only been reacted with ethylene oxide.

Fatty acids with 5 to 30 carbon atoms of natural or synthetic origin are used as the fatty acid component, in particular straight-chain, saturated or unsaturated Fatty acids, including technical mixtures thereof, which are obtainable by splitting fat from animal and vegetable fats and oils, for example from coconut oil, palm kernel oil, soybean oil, soybean flower oil, rape oil, cottonseed oil, fish oil, beef tallow and lard; specific examples are cyano, caprin, lauric, laurolein, myristic, myristole, palmitic, palmitoleic, oleic, elaidic, arachin, gadoleic, behenic and erucic acid.

Straight-chain or branched, saturated or unsaturated monoalcohols with 1 to 6 carbon atoms, e.g. Suitable for methanol, ethanol, propanol, butanol, pentanol, hexanol and cyclohexanol. As polyols having 2 to 12 carbon atoms, for example ethylene glycol, 1,2-propylene glycol, 1,2-butylene glycol, glycerin, polyglycerols, trimethylolpropane, erythritol, neopentyl glycol and hexylene glycol can be used.

Alkoxylated fatty acid esters whose fatty acid component is selected from linear, unbranched C, ₄ are preferably used in the agents according to the invention. to C _lg fatty acids and their alcohol component is methanol, the esters containing between 2 and 5 moles of ethylene oxide per mole of ester. Such compounds can be obtained, for example, by the reactions of palmitic, stearic, oleic, linolinic or linolenic acid or their esters described above with ethylene oxides.

Also suitable are alkoxylated esters in which glycerol is used as the alcohol component and the fatty acid component is selected from saturated or unsaturated, branched or unbranched fatty acids with 16 to 22 carbon atoms and the esters contain between 3 and 30 moles of ethylene oxide per mole of ester. Such compounds can be obtained, for example, by reacting glycerol esters of natural fatty acids such as palm, rapeseed or castor oil with ethylene oxide. The ethoxylated and optionally propoxylated esters are contained in the agents in amounts between 0.5 and 10% by weight, preferably in amounts of 1 to 5% by weight, based on the agents.

The agents according to the invention can contain minor auxiliaries and additives such as e.g. Contain anti-corrosion agents, antioxidants, antipore agents, preservatives, wetting agents, spreading agents and the like. The proportion of these substances, based on the composition, is usually in the range from 1 to 15 and preferably 2 to 10% by weight.

The invention further relates to a process for the preparation of aqueous concrete release agents, in which an aqueous premix is first prepared from the oil body and the emulsifier with moderate stirring and then subsequently in a manner known per se, for example in an Ultraturrax, a Supraton and / or a high-pressure homogenizer, homogenized into a fine-particle emulsion.

The release agents can be applied to the formwork surfaces in pure form or in the form of their emulsion by spraying, spraying, brushing, brushing or brushing. The low-viscosity emulsions are so stable that they can be sprayed without problems. Highly viscous pastes can also be applied with a spatula. Another object of the invention therefore relates to the use of aqueous emulsions (a) unsaturated fatty alcohols and (b) ethoxylated and optionally propoxylated fatty acid esters to reduce the adhesion between concrete and formwork.

Examples

General manufacturing instructions. 700 kg of fully deionized water were heated to 40 ° C. in a 2 m ³ stirred tank and 10 kg of the emulsifier were added in each case. In each case, ethoxylated rapeseed oil (molar ratio 3: 1) was used as emulsifier in accordance with the preparation specification of WO 90/13533 (saponification number 150). 1.5 kg of the rustproofing agent Texamin® Ke 3161 (coconut fatty acid monoethanolamide) were stirred into the resulting transparent, slightly viscous solution, a pH of 10.5 being established. Thereafter, 300 kg each of the oil bodies AI and A2 were added with stirring and the premix was adjusted to a pH of 11.5 with dilute sodium hydroxide solution. The mixture was then transferred to an Ultraturrax-type disperser and processed there to form a fine-particle emulsion.

The viscosity of the emulsions was determined using the Brookfield method in an RVT viscometer (20 ° C., spindle 4, 10 rpm). The stability of the emulsions was assessed after storage for 4 weeks at 0-5 ° C. The performance properties of the emulsions are summarized in Table 1. The mixture R1 is according to the invention, the mixtures R2 to R4 are used for comparison. It can be seen that low-viscosity and cold-stable concrete release agents can only be obtained using the combination of selected oil component and emulsifier according to the invention.

Table 1

Concrete release agent (quantities as% by weight)

Claims

claims

1. Aqueous concrete release agents containing (a) unsaturated fatty alcohols and (b) ethoxylated and optionally propoxylated fatty acid esters, the fatty acid component being selected from branched or linear, saturated or unsaturated fatty acids having 5 to 30 carbon atoms and the alcohol component being selected from branched or linear, saturated or unsaturated monoalcohols with 1 to 5 carbon atoms and polyols with 2 to 6 hydroxyl groups and 2 to 12 carbon atoms.

2. Composition according to claim 1, characterized in that they contain fatty alcohols of the formula (I),

R-OH (I),

in which R represents a completely or predominantly unsaturated hydrocarbon radical having 6 to 22 carbon atoms.

3. Composition according to one of claims 1 to 2, characterized in that the ethoxylated and optionally propoxylated fatty acid esters (b) contain 2 to 30 moles of ethylene oxide per mole of ester.

4. Composition according to one of claims 1 to 3, characterized in that fatty acids are contained as C _H to C _lg fatty acids and as alcohol component methanol and the esters contain between 2 and 5 moles of ethylene oxide per mole of ester.

5. Composition according to one of claims 1 to 3, characterized in that the fatty acid component C ₁₆ to C ₂₂ fatty acids and as the alcohol component glycerol are contained and the esters contain between 3 and 30 moles of ethylene oxide per mole of ester.

6. Composition according to one of claims 1 to 5, characterized in that the fatty acid esters contain 1 to 10 moles of propylene oxide per mole of ester.

7. Composition according to claims 1 to 6, characterized in that they contain unsaturated fatty alcohols of the formula (I) which have an iodine number in the range from 40 to 200.

8. Composition according to claims 1 to 7, characterized in that they contain the unsaturated fatty alcohols in amounts of 10 to 50 wt .-% - based on the agent.

9. Composition according to claims 1 to 8, characterized in that they contain the alkoxylated fatty acid esters in a total amount of 1 to 5 wt .-% - based on the composition.

10. Composition according to claims 1 to 9, characterized in that they have an aqueous proportion of 50 to 80 wt .-%.

11. Composition according to claims 1 to 10, characterized in that they contain customary auxiliaries and additives as minor constituents in minor amounts.

12. Use of aqueous emulsions of unsaturated fatty alcohols and ethoxylated and optionally propoxylated fatty acid esters according to claim 1 to reduce the adhesion between concrete and formwork.