DE3834462A1 - Process and composition for the consolidation of building material and Si-containing polycondensates for this purpose - Google Patents

Abstract

There is described a process for the consolidation of inorganic building materials by treatment of the same with hydrolysable organic silicate, which is characterised in that at least 20% by weight of the silicate present has hydrocarbon radicals bonded to Si, so that after hydrolysis and condensation are complete these radicals remain in the SiO2 network, which leads to an increase in the strength of the treated building material in comparison with the production of pure SiO2 in the pores of the same. A suitable consolidating composition for use in this process is likewise described.

Description

The present invention relates to a method for consolidation of inorganic building materials by treating them with hydrolyzable, organic silicate as well as new ones Polycondensates and consolidating agents for use in this procedure.

It has long been known to be tetraalkyl silicates, either as such or dissolved in a suitable solvent, as a binding agent or to use impregnating agents for inorganic substances, see e.g. B. DE-OS 23 18 494. The moisture leads in the Ambient air to a more or less rapid (depending from the presence of a catalyst) hydrolysis and subsequent condensation of the alkyl silicate until finally SiO₂ remains in the pores of the inorganic material and this gives the latter an improved hardness. Disadvantageous of the previously known consolidation agents is that embrittlement occurs easily, not a particularly high level of strength can be reached and very dense stones (e.g. granite, Maulbronner sandstone) consolidated with very little success can be.

The object of the present invention is therefore a method for the consolidation of inorganic building materials and a consolidating agent usable in this process to make available that the previously known method or consolidation funds with regard to the increase in Bending, tensile and compressive strength, the adhesive tensile strength, the Abrasion resistance and increasing the impact resistance of the treated building material is superior.

This object is achieved by what is defined in the above claims Process or consolidation means solved.  

Surprisingly, it was found that the above-mentioned properties of the building material compared to Improve the use of silicate that is fully hydrolyzable to SiO₂, if in the hydrolysis and condensation product (polycondensate) still a certain percentage of organic groups remains. These organic groups are according to the invention supplied by silicates that 1 to 3 directly to the silicon atom bound aliphatic, cycloaliphatic and / or aromatic Have hydrocarbon groups. The rest of the total 4 groups bound to the silicon atom then exist as in the previously used silicates from alkoxy groups and / or from Ethylene oxide and / or propylene oxide derived oxy radicals.

The following applies to the groups X and R in the general formula (I): Alkyl groups X are those with 3 to 20 carbon atoms, preferably those with 6 to 18 carbon atoms, and in particular those with 8 to 16 carbon atoms. Specific examples n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, pentyl, hexyl, heptyl, n-octyl, i-octyl, 2-ethylhexyl, Nonyl, decyl, dodecyl, tetradecyl, hexadecyl and octadecyl. As can be seen, the alkyl groups X can be straight or be branched.

Cycloalkyl groups X are those with 5 to 8 carbon atoms, especially cyclopentyl, cyclohexyl and cyclooctyl. These Cyclic groups can optionally have one or two methyl groups wear.

Aryl groups X are preferably those having 6 to 20 carbon atoms 6 to 14 carbon atoms. Particularly preferred examples for this are phenyl, naphthyl, biphenylyl and terphenylyl, especially phenyl.

The aralkyl and alkaryl groups X having 7 to 20 carbon atoms, preferably 7 to 15 carbon atoms are derived from the the above-mentioned alkyl and aryl groups. Particularly preferred examples for this are benzyl, phenethyl, tolyl, xylyl, ethylphenyl, Cumyl and phenylmethylphenyl.

The above groups X can have 1 to 3 alkoxy groups with 1 up to 4 carbon atoms. Examples of preferred Alkoxy groups are methoxy, ethoxy, i-propoxy and  sec-butoxy. The above radicals preferably have - if at all - one or two alkoxy groups.

If n in the general formula (I) is 2 or 3, the radicals X can be the same or different. Because of the easier accessibility, identical residues are preferred.

The radicals R in the general formula (I) are alkoxy groups having 2 to 18 carbon atoms, in particular 2 to 16 carbon atoms. Particularly preferred radicals are ethoxy, i-propoxy, sec-butoxy, octyloxy, decyloxy, dodecyloxy and hexadecyloxy. While ethoxy is particularly preferred as the meaning of R because the ethanol formed during the hydrolysis is non-toxic, the presence of alkoxy radicals with 8 carbon atoms and above can also be advantageous because they lead to alcohols which are difficult to volatilize and in to a certain extent increase the effect of residues X. Particularly preferred compounds of the general formula (I) with n = 1 contain either three ethoxy radicals, two ethoxy radicals and one long-chain (C _8-18 ) alkoxy radical or one ethoxy radical and two long-chain alkoxy radicals. Preferred compounds of the general formula (I) with n = 2 contain either 2 ethoxy radicals or one ethoxy radical and one long-chain alkoxy radical. Compounds of the general formula (I) with n = 3 preferably have an ethoxy radical.

Further radicals R in the general formula (I) are those which are derived from ethylene oxide and / or propylene oxide and contain up to 5 such units. examples for this are HO-CH₂-CH₂-O-, HO-CH₂-CH₂-O-CH₂-CH₂-O-, HO-CH₂-CH₂- (O-CH₂-CH₂) ₂-O- and HO-C₃H₇-O-C₃H₇-O-. If necessary, the OH groups of these residues can be replaced by CH₃O- or C₂H₅O residues can be replaced.

Of course, the compounds of the general Formula (I) simultaneously both alkoxy groups and Alkylene oxides derived radicals as groups R.

The index n in the general formula (I) is an integer from 1 to 3, preferably 1 or 2, and in particular 1.

Instead of or together with the compounds of the general formula (I) according to the invention, precondensates can also be made from the same are used by partial hydrolysis and Condensation has arisen. These precondensates can be average Have 2 to 10 silicon atoms. The upper limit for the number of silicon atoms it follows that higher molecular weight Condensates too viscous and / or in a suitable Solvents are no longer sufficiently soluble, to be applied to building materials with reasonable effort to be able to.

In the process according to the invention, the compound of the general Formula (I) or the precondensate derived therefrom in a minimum amount of 20% by weight, preferably at least 50% by weight, based on the total amount of organic, hydrolyzable Silicate.

The remaining proportion of hydrolyzable silicate (max. 80% by weight, preferably at most 50% by weight) preferably consists of a silicate of the general formula (I) with n = 0, ie with four radicals R which are defined as above (including the preferred meanings). A particularly preferred silicate in this context is tetraethyl silicate. Of course, compound mixtures and / or precondensates with up to ten Si atoms can also be used here, and of course it is also possible to use precondensates which differ both from compounds of the general formula (I) with n = 1, 2 or 3 as well derived from those with n = 0. If precondensates of this type are used exclusively, it also applies here that at least 20% by weight of monomeric silicate of the general formula (I) with n = 1, 2 or 3 should be derived. If mixtures of monomeric and oligomeric compounds are used, care should also be taken to ensure that the total of monomeric compounds and the monomeric compounds which serve as starting materials for the preparation of the precondensates contains the silicates of the general formula (I) with n = 1 up to 3 at least 20 wt .-% are included.

In the production of pre-condensates, but also in general before treating the building material with the hydrolyzable Silicates, it is preferred to add a catalyst the hydrolysis or condensation of the silicate compounds accelerates. Compounds suitable for this purpose are protons or compounds and amines which release hydroxyl ions. Specific examples are organic and inorganic Acids such as B. hydrochloric acid, sulfuric acid, phosphoric acid. Formic acid, acetic acid, and organic or inorganic Bases such as B. ammonia, alkali and alkaline earth metal hydroxides, e.g. As sodium, potassium or calcium hydroxide, and amines, e.g. B. lower alkylamines or alkanolamines.

Particularly preferred hydrolysis (condensation) catalysts however, are Lewis acids, especially hydrolyzable compounds of boron, aluminum, titanium and zirconium. Under these Compounds are again the halides (e.g. AlCl₃, BCl₃, TiCl₄ and ZrCl₄) and especially the alkoxides are particularly preferred. Examples of the latter are B (OR ′) ₃, Al (OR ′) ₃, Ti (OR ′) ₄ and Zr (OR ′) ₄, where R ′ is preferably an alkyl group with 1 to 4 carbon atoms, especially methyl, ethyl, i-propyl and sec-butyl. Such connections will preferably in an amount of 0.1 to 10% by weight, in particular 1 to 5 wt .-%, based on monomeric and / or oligomeric Silicate. Has already been used to manufacture the Pre-condensate uses such a catalyst, it is not absolutely necessary before the treatment according to the invention of the building material to add further catalyst, though this is preferred. Are only monomeric compounds used, the catalyst is preferably the silicate added just before use.

As long as the silicate to be used according to the invention (inclusive the precondensate) or the mixture thereof with a Catalyst liquid (low-viscosity) is enough to act as such to be applied to the building material is not necessary the use of a solvent. But if a pre-condensate  is used and this in the presence of a solvent This solvent does not have to be prepared separately be removed. Likewise, you can use what is to be used according to the invention Dissolve silicate in a suitable solvent, too if this from the point of view of lowering the viscosity would not be necessary.

Solvents suitable for this purpose are in principle those that provide the desired hydrolysis and condensation of the Do not noticeably affect silicates and not too heavy are volatile, but also do not have too high a viscosity. Preferred solvents are aliphatic alcohols 2 to 8 carbon atoms, especially ethanol, propanol, Butanol and hexanol, with ethanol being particularly preferred. Other suitable solvents are aliphatic and aromatic, optionally halogenated hydrocarbons with 6 to 18, preferably 6 to 12 carbon atoms, such as. B. hexane, heptane, Octane, decane, dodecane, toluene, xylene, ethylbenzene, cumene, trimethylbenzene, Chlorobenzene, cyclohexane etc. Of course other solvents can also be used, such as. B. Ketones (e.g. acetone and butanone), ethers (e.g. THF, dioxane and Di-n-butyl ether) and esters (e.g. ethyl acetate). If solvent is used, it should not be more than 50% by weight, preferably not more than 25% by weight, of the total of silicate, (optionally) catalyst and solvent turn off.

Accordingly, the consolidating agents according to the invention for inorganic building materials from the following components produced:

• (a) 20 to 100% by weight, preferably 50 to 100% by weight, of a silicate of the general formula (I) with n = 1 to 3 and / or a precondensate produced therefrom with an average of up to 10 Si atoms;
• (b) 0 to 80% by weight, preferably 20 to 40% by weight, of a silicate of the general formula (I) with n = 0 and / or a precondensate produced therefrom with an average of up to 10 Si atoms, the Sum of (a) and (b) is 40 to 100% by weight, preferably 70 to 100% by weight;
• (c) 0 to 10% by weight, preferably 1 to 5% by weight, of a catalyst; and
• (d) 0 to 50% by weight, preferably 0 to 25% by weight, of an inert organic solvent or solvent mixture.

The above consolidation tool is particularly suitable for consolidation of natural stones, bricks, mortar and mineral Building materials, it being for the consolidation of natural stones, e.g. B. sandstones, is particularly well suited.

The inventive method can, for. B. be carried out by using the consolidating agent described above in a suitable manner Way onto the building material to be treated. This can be done in any known manner, e.g. B. by Spraying, painting, dipping and pouring, but preferably through Spraying.

The following example describes the preparation of an inventive By means of that as such on a building material can be applied.

example

1000 g n-C₈H₁₇-Si (OC₂H₅) ₃ (3.6 mol), 753 Si (OC₂H₅) ₄ (3.6 mol) and 16 g of B (OCH₃) ₃ in 1.6 l of ethanol (96%) at room temperature solved. The water present in the ethanol leads partial hydrolysis and condensation of the existing ones Si and B connections. The solution can be immediately or but also only applied to the building material after a few hours (e.g. sprayed on).

Claims (12)

1. A process for the consolidation of inorganic building materials by treating them with hydrolyzable, organic silicate, characterized in that at least 20% by weight of the silicate consists of at least one compound of the general formula (I): SiX _n R _{4- n} (I) in which
the groups X, which may be the same or different, represent alkyl groups with 3 to 20 carbon atoms, cycloalkyl groups with 5 to 8 carbon atoms, aryl groups with 6 to 20 carbon atoms or aralkyl or alkaryl groups with 7 to 20 carbon atoms, the groups just mentioned optionally including 1 to 3 C _1-4 alkoxy groups can be substituted;
the radicals R, which may be the same or different, represent alkoxy groups having 2 to 18 carbon atoms and / or oxy groups derived from polyethylene oxide, polypropylene oxide and / or polyethylene propylene oxide with up to 5 ethylene oxide and / or propylene oxide units; and n = 1, 2 or 3;
and / or a precondensate derived therefrom with up to 10 silicon atoms. 2. The method according to claim 1, characterized in that the Proportion of compound (s) of the general formula (I) and / or precondensate derived therefrom is 50 to 100% by weight. 3. The method according to any one of claims 1 and 2, characterized in that the remaining silicate consists of compounds of the general formula (I) with n = 0 and / or precondensates derived therefrom with up to 10 Si atoms. 4. The method according to any one of claims 1 to 3, characterized characterized in that the silicate together with a catalyst is used.   5. The method according to claim 4, characterized in that the Catalyst is selected from B (OR ′) ₃, Al (OR ′) ₃, Ti (OR ′) ₄ and Zr (OR ′) ₄ or mixtures thereof, where R ′ is is an alkyl group having 1 to 4 carbon atoms. 6. The method according to any one of claims 4 and 5, characterized characterized in that the catalyst in amounts of 1 to 5 wt .-%, based on the silicate is used. 7. The method according to any one of the preceding claims, characterized characterized that it is in the inorganic Building materials around natural stones, bricks, mortar and mineral Building materials, especially natural stones. 8. Polycondensates, obtainable by hydrolysis and subsequent condensation of compounds of the general formula (I) with n = 1 and / or 2 and compounds of the general formula (I) with n = 0 in a molar ratio of 1: 3 to 1: 0.1 in Presence of the amount of water that provides an average degree of condensation of 2 to 10. 9. polycondensates according to claim 8, characterized in that the hydrolysis in the presence of a as defined in claim 5 Catalyst is carried out. 10. Polycondensates according to claim 9, characterized in that the catalyst in amounts of 1 to 5 wt .-%, based on the compounds of general formula (I) is used. 11. Polycondensates according to one of claims 8 to 10, characterized characterized in that the groups X in the compounds the general formula (I) are selected from hexyl, octyl and / or phenyl and that the radicals R are ethoxy, propoxy and / or Butoxy stand. 12. Consolidating agent for inorganic building materials, made from:

• (a) 20 to 100% by weight of a silicate of the general formula (I) as defined in claim 1 and / or a precondensate derived therefrom with up to an average of 10 Si atoms;
• b) 0 to 80% by weight of a silicate of the general formula (I) with n = 0 and / or a precondensate derived therefrom with up to an average of 10 Si atoms, the sum of (a) plus (b) 40 to 100% by weight;
• (c) 0 to 10% by weight of a hydrolysis or condensation catalyst; and
• (d) 0 to 50% by weight of an inert organic solvent with a boiling point of 50 to 200 ° C or a mixture of such solvents.