JPH0229636B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a weatherproofing material for wall elements, in particular for lightweight structural elements, which have at least spaces open to the outside and whose total open area is greater than 5% of the external surface area of the wall element. Regarding coating.

Building facades and external walls require building materials with good thermal insulation, which can be achieved inter alia by means of a large number of generally open holes. Materials belonging to this group include, for example, cement-bonded wood wool, glass concrete or pumice bricks and tiles. This type of building material is widely used. In the case of weather-exposed walls, they have the serious disadvantage that when they contain organic components, they rot under the influence of moisture or are destroyed by frost and rain.

To avoid this type of damage, the surface is usually plastered. External walls require water-hardening plasters, which are often applied in the form of two-layer cement or lime-cement plasters, the first layer containing water-repellent additives, such as stearate.

Plaster application of lightweight walls is not without problems. It is labor intensive work and can only be rationalized to a certain extent. Plaster application requires skilled workers who have to work on the building site regardless of weather conditions, ie in the wind and rain. This is because it has not been possible to successfully prefabricate panels or boards using mineral-based plasters. Because, due to the lack of tensile strength, the panels will crack under the influence of unavoidable sagging during transportation and processing, resulting in a decrease in the quality of the panels, which is significant in some cases, and the panels will not sag. I can not use it. In addition, the transport weight is 5 to 50
Kg/m ² increases and the thermal insulation value decreases. These are also factors that are detrimental to the use of mineral-based plasters.

Attempts have also been made to use synthetic resin bonded plaster for lightweight structural panels.

In view of the rather large pores of many lightweight building materials, the consumption of synthetic resin plasters is so high that economical use is no longer possible.

It is therefore an object of the invention to combine low weight with a high level of surface water impermeability, which can be economically applied to lightweight building materials with a high percentage of openings, and in the case of prefabricated structural elements. The objective is to provide a weather-resistant and aesthetically appealing coating for walls and structural elements exposed to the elements, combining a high-quality surface with sufficient elasticity to withstand unintended deformations during processing.

According to the invention, this objective is achieved by coating the outer part of the element with a polyurethane composition for water resistance purposes, increasing the volume by 30-300% during curing.

The polyurethane composition penetrates into the open space opening to the outside of the structural element, with a subsequent volume increase of 30-300%, preferably 100-200%, establishing a strong bond with the lightweight structural element and forming a surface It is surprising to those skilled in the art that even a minimally thick coating, just sufficient to seal against water, no longer comes off. 5% of the designed covering
The required open area of more, preferably 10-30% of the space is generally generated during the actual fabrication of lightweight structural elements. However, it is also possible to subsequently introduce corresponding grooves or holes. The thin layer may be applied directly to the structural element, for example by means of a trowel, and obtains its final thickness only after increasing the volume. Material consumption is minimal. Even lightweight structural panels with large dimensions can be coated in the factory. Because they have a shock-resistant surface and are extremely stable against breakage, quality is guaranteed even during transport.
The outstanding properties of the material also allow it to be further processed on site without any significant reduction in quality.

In one particular embodiment, the space has an undercut.

There are many spaces within the structural element. When a structural element is cut along a certain plane, a space located near the cut plane is cut and an opening leading to the outside is formed. In this case, the space is said to have an undercut. Space is often spherical. An undercut is formed if the distance from the center of this sphere to the surface of the structural element is less than the radius of the sphere.

If the space undercuts, the polyurethane composition that permeates from the surface increases in volume and becomes a wedge, holding the thin coating firmly. These spaces with undercuts may consist of produced holes, partially covered cavities or undercut holes and depressions subsequently made in the form of grooves. The required anchoring depth is determined by material-dependent thermally induced and mechanical stresses.

In another embodiment, the coating is embossed prior to final curing.

With the help of a marking tool, it is possible to texture the surface of a finished structural component in order to give it a special effect.

In another embodiment, the coating is provided with mineral-based grains prior to final curing.

By dispersing mineral-based grains onto the coating before hardening, it is possible to significantly improve the aesthetic appearance of the structural element.

In one possible embodiment, the coating includes flame retardant additives.

Fire risk is reduced by flame retardant additives.

The polyurethane compositions used for producing the coatings according to the invention are one-component or two-component systems known per se in polyurethane chemistry.

When using a one-component system, according to the invention, an organic polyisocyanate compound and a substoichiometric amount of a compound having isocyanate-reactive hydrogen atoms,
A reaction product with an equivalent ratio of isocyanate to isocyanate-reactive groups of 1.5:1 to 15:1 is particularly preferably used, and when a large excess of polyisocyanate is used, the prepolymer can be prepared by thin-film evaporation or the like. Removed after production.

When a two-component system is used, the organic polyisocyanate is generally used in combination with a compound containing isocyanate-reactive groups in an equivalent ratio of about 0.8:1 to 1.2:1. In this case, the reaction components are mixed immediately before use. Curing is accomplished by a spontaneous isocyanate addition reaction between isocyanate groups and isocyanate-reactive groups. If NCO prepolymers are used, they are preferably cured by reaction with the water contained in the substrate.

Any isocyanate of the type commonly used in polyurethane chemistry can be used both for the preparation of the NCO prepolymer and also as a reactant in a two-component system; examples of such polyisocyanates are Hexamethylene diisocyanate, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane, 2,4- and 2,6-tolylene diisocyanate and mixtures of these isomers, 4,4 '-diphenylmethane diisocyanate and 4,4'-dicyclohexylmethane diisocyanate. It is also possible to use reaction components other than the biurets, uretdiones, trimers and monomeric polyisocyanates mentioned above that contain NCO groups.

Contains isocyanate-reactive hydrogen atoms,
Any compound having a functionality of at least two in the isocyanate addition reaction can be used both for the preparation of NCO prepolymers and also as a reaction component in two-component systems. Contains hydroxyl group or sulfhydryl group, 150~
Preference is given to using corresponding polymerizations or polycondensates having a molecular weight in the range 10,000, preferably in the range 1,000 to 5,000. Examples of such polymers or polycondensates include, for example, water, ammonia, ethylenediamine, ethylene glycol, trimethylolpropane, glycerol, pentaerythritol,
Polymerization, copolymerization or block copolymerization of alkylene oxides such as ethylene oxide and/or propylene oxide using difunctional or polyfunctional starter molecules containing active hydrogen atoms such as sorbitol, phosphorous acid and phosphonic acid. Polyether polyols are known per se in the compounding of polyurethanes of the type obtained by polymerization. For example, obtained using an acid catalyst,
It is also possible to use polyacetals such as polycondensates of formaldehyde and diols or polyols of the type mentioned above.

Preferred polyisocyanates for preparing the prepolymer are 4,4'-diphenylmethane diisocyanate and isomeric mixtures of 4,4'- and 2,4'-diphenylmethane diisocyanate. Particularly suitable polyisocyanate mixtures are
(a)2,2'-diisocyanatodiphenylmethane 0~
5%, (b) 2,4'-diisocyanatodiphenylmethane 20-80%, preferably 30-70% and (c) 4,
It consists of 80 to 20%, preferably 70 to 30%, of 4'-diisocyanatodiphenylmethane and/or diphenylmethane series difunctional or higher polyisocyanate. This preferred polyisocyanate mixture has a viscosity of less than 200 cp at 20°C. A special advantage of the preferred polyisocyanate mixture is that
It is a fact that it allows the production of solvent-free primer compositions without any troublesome crystallization phenomena occurring.

The reaction product containing free isocyanate groups is prepared by mixing the components in the above quantitative ratios in a known manner.
It is produced by reacting at 20-50°C, preferably 20-50°C. The reaction product thus obtained generally has a molecular weight of 1000 to 10000 at 20°C.
It has a viscosity of mpa.s.

The primer composition used in the method according to the invention generally contains from 20 to 100% by weight, preferably from 30 to 60% by weight, of the abovementioned reaction products.

In addition, the primer composition may contain auxiliaries and additives, such as catalysts of the types commonly used in polyurethane chemistry, such as tertiary amines or organometallic compounds, in particular alkaline components of building materials, such as phosphoric esters. plasticizers of a type characterized by resistance to, and also reaction products of chlorosulfonated paraffins with phenols and phenol derivatives, pigments in the form of powders or pastes, such as sand, kaolin,
Inorganic fillers, emulsifiers, flame retardants, anti-aging agents or adhesion promoters may be included, such as silica, barium sulfate, silicon dioxide. The foam structure created by the evolution of carbon dioxide may also be stabilized by polyether polysiloxanes, which are known per se in the chemistry of polyurethane foams. Although the primer compositions used in the method according to the invention are largely solvent-free, it is in principle possible to use solvents such as, for example, ethyl acetate, butyl acetate or xylene.

Conventional inorganic thickeners, such as highly dispersed silica or asbestos fibers, may be used to adjust the pasty consistency of the primer composition. The use of chemically reactive thickeners is particularly preferred for the method according to the invention. 4,4'-
Diphenylmethane diisocyanate or 2,
In the case of preferred diisocyanates based on isomeric mixtures with 4'-diphenylmethane diisocyanate, by addition of up to 4% of diethyltolylene diamine or other sterically hindered aromatic diamines, A pasty cosine consistency is obtained by chemical reaction with isocyanate groups. Isomer mixtures containing at least 20% of 2,4-diphenylmethane diisocyanate exhibit a low viscosity, which is particularly advantageous for processing.

For processing purposes, the primer composition is prepared by hand,
Alternatively, if prefabricated, it is applied by machine to the prewet surface of the lightweight structural component, generally in amounts of 250 to 5000 g/m ² . In one particular embodiment, mineral-based particles are dispersed in a thin layer onto a surface coated with a primer composition. Alternatively, buff the primer-coated surface. Reactions involving elimination of carbon dioxide are 5
This occurs over a period of ~30 minutes, resulting in curing and expansion of the primer composition after 1-3 hours. The curing rate can be increased by spraying water or introducing water vapor. After curing, the primed surface may be coated with emulsion paint or with a solvent content.

Example 1 A lightweight panel of cement-bonded wood wool conforming to DIN 1104 was wetted with water, and two panels of the following composition were added.
A component-based coating composition is applied as a primer.

Component A: 1000 g of polyalkylene oxide polyether (molecular weight approximately 600) based on trimethylolpropane and propylene oxide, 20 g of polyalkylene oxide/polysiloxane copolymer as stabilizer, 100 g of amorphous silica and quartz sand (particle size 0.2). mm) and mix with 3000g.

Component B: 148.5 g of diphenyl cresyl phosphate using 1.5 g of dibutyltin laurate as a catalyst.
1350 g of biuret polyisocyanate based on hexamethylene diisocyanate (NCO content 21.5% by weight) dissolved in

Before processing, the two components are mixed with each other and applied. The processing time is 20 minutes and the material consumption per m ² of coated panel is 2.75 Kg. Freshly applied coatings scatter quartz fragments (0-2 mm) while still wet. After curing, the resulting structural panel has a light-stable, elastic, textured surface texture containing other decorative components in the scattered and bound minerals.

Example 2 Component B of Example 1 with a viscosity of 180 mPa.s and an NCO content
This is replaced by 900 g of a technical isomer mixture of diphenylmethane diisocyanate having a concentration of 31.5%. After mixing with component A of Example 1, the operation is the same as described in Example 1. Processing time is 40
It's a minute. After curing, a plaster-like decorative non-porous surface is obtained. By coating it with standard emulsion paint,
Protected against damage by light and weather. Panels produced by the above method are suitable for building facades, walls and as ceiling panels.

Example 3 A multilayer lightweight construction panel consisting of a 15 mm polystyrene foam core and a 5 mm cemented wood wool shell according to DIN 1104 is moistened and coated with a primer composition having the following composition:

Polypropylene glycol ether (molecular weight approx.
1000) and 30 wt.
1000 g of a polyisocyanato prepolymer prepared from 100 g of a % mixture (NCO content approximately 31%) are mixed with a solution of 10 g of diethyltolylene diamine in 90 g of polyalkylene glycol ether. The mixture solidifies in 5-10 minutes, producing a thixotropic gel. After gel formation, quartz sand (particle size 0.2 mm)
Add 2000g. The consumption of material will be 1600g/m ² .

Moisture contained in the substrate initiates a curing reaction of the primer composition, accompanied by an increase in volume.
The curing reaction is completed after about 3 hours at 23°C.

The final product is a decorative component covered with an elastic, impact-resistant and waterproof coating.

Example 4 A light wood panel of cemented wool according to DIN 1104 (material thickness 20 mm) is coated with a primer composition according to Example 3.

The material consumption will be 2.0Kg/ ^m2 . The coating is cured in a room saturated with superheated steam.

After just 12 minutes, the coating is further heated at 23°C.
After cooling for 20 minutes, emulsion paints based on acrylate/styrene copolymers were cured enough to be applied.

Flexural tensile tests are carried out according to DIN 1164 and compared with untreated wood wool lightweight construction panels.

Untreated 0.81 N/mm ² Coated 1.87 N/mm ² It follows that the flexural tensile strength of the lightweight structural panel is significantly increased by the coating according to the invention.

Example 5 The coating of cement bonded pumice panels is illustrated in the following example.

The wet substrate is coated with a coating composition of the following composition: 2.1 Kg/m ² .

Prepolymer based on 2,4-tolylene diisocyanate and polyalkylene oxide polyether (MW 1000, NCO content 6.5%, viscosity
165000 Pa.s) are mixed with 400 g of a 75% solution of tolylene diisocyanate/trimethylolpropane adduct (NCO content 13%).

2 g of dibutyltin dilaurate, 20 g of polyalkylene oxide/polysiloxane copolymer and 120 g of amorphous silica are added together with 1600 g of quartz sand.

A buffing tool is applied to the fresh coating composition, leaving a brick pattern in the structured surface coating after it cures. The coated pumice panels are cut into brick shapes and used as thermally insulating decorative surfaces.

Example 6 A thixotropic isocyanate group-containing prepolymer having the composition shown in Example 3 is mixed with an equal amount of aluminum oxide hydrate and applied by means of a trowel to the wet surface of a foamed concrete board. do. The consumption of material will be 1100g/m ² . The curing reaction with an increase in volume begins after about 10 minutes and ends after about 5 hours. The volume increase is 285% near the foam concrete holes and 30% near the web. The surface of the coating is structured but without pores. The water permeation test is carried out by the Carstens method (“Warme and Humidity”).
"Feuchtigkeit", Berlin, 1960, Verlag Ernst, p. 30). After 3 days of testing,
It does not appear that any water was absorbed.
Fire test according to DIN 4102 yields special grade B1 (virtually non-flammable).

Claims (1)

[Claims] 1. At least a space opening to the outside, the total opening area of the space being 5 of the outer surface area of the structural element.
% weather-resistant coatings for structural elements, in particular lightweight structural elements, in which the outside of the element is coated with a polyurethane composition resulting in a volume increase of 30 to 300% during curing for a waterproof coating. Features a weather-resistant coating. 2. The weather-resistant coating according to claim 1, wherein the space has an undercut. 3. Weather-resistant coating according to claim 1 or 2, characterized in that the coating is grained before final curing. 4. Weather-resistant coating according to claim 1 or 2, characterized in that mineral particles are added to the coating before final curing. 5. Weather-resistant coating according to any one of claims 1 to 4, characterized in that the coating contains a fire-resistant additive. 6. Weather-resistant coating according to any one of claims 1 to 5, characterized in that it consists of an isocyanate group-containing prepolymer based on diphenylmethane diisocyanate and polypropylene glycol ether. 7 Diphenylmethane containing a minimum of 20% diphenylmethane-2,4'-diisocyanate
4,4'-diisocyanate and diphenylmethane-
Claims 1 to 3 are characterized in that an isomer mixture of 2,4'-diisocyanate is used as a prepolymer containing isocyanate groups.
The weather-resistant coating according to any of paragraph 5. 8. Claims 1 to 7, characterized in that the prepolymer containing isocyanate groups is gel-like and thixotropic as a result of a partial reaction with a sterically hindered aromatic diamine. The weather-resistant coating described in any of paragraphs.