DD289898A7 - WAESSER RISSUEBERBRUECKENDER COATING MATERIAL FOR GASBETON EXTERNAL WAITING OF WARMBAUTEN - Google Patents

Abstract

The invention particularly relates to coating materials for exterior gas concrete concrete walls of warm buildings to permanently maintain their thermal insulation and structural strength in conjunction with the three main parameters: low capillary water absorption from the outside, maximum water vapor diffusion from the inside, expansion reserve for up to 2 mm widening cracks. The binder base of the coating material according to the invention contains a high-speed filming component at normal temperature and a second, the former softening and flexibilizing component, which is used in deficiency and sticks or does not film at normal temperature. This binder combination is composed of at least two different aqueous pure acrylate polymer dispersions. When filling this binder combination with inorganic materials and optionally supplementing with organic short-cut fibers a) the particle size of the fillers used are chosen in a wide range of 60 ... 500 my m and b) a significant part of coarser material, such as quartz sand, especially added. Thus, the binder flexibility can be obtained so far that with surprisingly good effect for necessary water vapor diffusion sufficiently thin layers with a stretch reserve, which is otherwise expected only of thicker layers, are achieved, {aerated concrete; Outside wall; Concrete; thermal insulation; Concrete; coating; Binder combination, flexible; pure acrylate; Filler, inorganic; filler particle size; Water absorption; Kapilla; Water vapor diffusion; Expansion reserve; Layer thickness}

Description

In GB 1534043 and JA 79-24944 weroen called to accommodate the luagehonden Wechsolspannungen layers of 1.3 ... 3mm thickness, which are thus 5, .. 10 times thicker than conventional façade colors and thus at the limits of Wasserdampfdlffuslonsfählgkelt. The fillers mentioned for filling the Beschchtungsstoffen are mainly of natural origin and are in particular Caiclt (CaCO ₃ ), but also marble, DoIo ,, lit, kaolin, silica, mica, diatomaceous earth. In part, nuoh fiber additives for film reinforcement are mentioned (US 4354000). The particle size distribution of the fillers in GB 1034043 with a diameter of 4 to 10 μm, however, is very narrow and is expected to supply very the same coatings. A broader distribution up to a maximum of 160pm grain size is mentioned in GB 2026003. The reserve of binder not bound by pigment and filler wrap is limited in both cases. In none of the cited patent descriptions is the building material called aerated concrete as a coating carrier and discussed the above-described specific conditions dos building material.

Object of the invention

The object of the invention is to protect the outer walls of especially large-sized aerated concrete mounting elements of hot buildings durable against penetrating rain water and don loss of structural strength and excellent Wärmdämmvormögens to avoid.

Essence of the invention

The task is to formulate the coating material so that it receives special suitability for the special construction gas concrete and eppüziert multi-layered as a coating on the outer surfaces, the very large porosity and water absorption capacity of the gas concrete against penetrating Niedarschlagswasser (churning, dew water, etc.) greatly reduced but at the same time is so permeable to water vapor, that the coating does not substantially hinder the dehydration of the structure and the escape moisture moisture. Furthermore, the coating should have sufficient flexibility to permanently bridge the shrinkage and haze cracks that form due to hygricho, thermal and mechanical stresses in the aerated concrete wall in the near-surface zones and to prevent capillary-penetrating water under all local climatic conditions protect.

Erfindungsgomäß this object is achieved in that the Beschichtungsunfisstoff consists of a mixture of two known per se weather-resistant and in particular UV radiation-resisting polyacrylate DispeHonen, which are synthesized almost exclusively from acrylate and methacrylate monomers, so-called pure acrylates.

The mixture contains 20 to 45% by weight of a dispersion, based on so-called pure acrylate, which films in the temperature range of 253 to 293 Kzu to tacky layers and 80 to 55 parts by mass in% of a dispersion also on so-called pure acrylate basis, with tack-free filmability between 291 and 293K. .

It also consists of known crystalline, optionally Inmellaren fillers, preferably calcite, marble, dolomite, barite, quartzite and optionally talc, mica and coloring pigments on predominantly oxidic basis and conventional additives and adjuvants for regulating the film-forming temperature, the flow and settling , water repellency, pH, microbicidal stability and other characteristics. The particle size distribution of the fillers and pigments is between 0.1 and 500 μm. At least 30 parts by weight in% of the substances have a particle size between 60 and 500 pm, the theoretical ratio of binder in the form of the solids volume of the polyacrylate dispersions to the sum of the volumes of the fillers and pigments, expressed in the so-called pigment-filler volume concentration ( PVK), below the so-called critical pigment-to-filler volume concentration (KPVK), the densest pigment-to-binder ratio, is 42 to 45% by volume. In this PVK are in the original consistency in a two-ply coating with a total of 1700 to 2 20OgZm ¹ order amount coatings achieved with water absorption values that are less than 0.5kg / m ² h ⁰ · ⁶ according to TGL 27327 (standard of the GDR), a Water vapor diffusion resistance of less than 2.0m according to TGL 27327 and an elongation of the coating at room temperature of more than 2.0mm over an opening crack achieved.

Surprisingly, it has been found that thus Rißüberbrückungswerta up to temperatures of from -1O ⁰ C obtained where comparatively commercial aerated concrete coatings exhibit virtually no Rißüberbrückungswerte. A condition for this is that the inorganic filling of the coating material on the basis of the above-characterized binder mixture has a broad particle size range of 0.1 to 500 μm and of which at least 30% by weight of the total filler anion is from a part having a structure of 60 to 500 μm Grain size exists.

This can be achieved in a comparatively small coating thickness of about 0.8 to 1.0 mm instead of otherwise with layer thicknesses of 1.6 to 3mm bridging over up to about 1 mm wide-opening shrinkage and hairline cracks in aerated concrete.

In addition to the inorganic fillers and pigments mentioned, synthetic fibers, in particular polyacrylonitrile short-cut fibers up to 6 mm in length, preferably from 2 to 4 mm in length, may also be added in small amounts of about 0.5 to maximally 1.5% of the total formulation and homogeneously be distributed in the coating material. They act primarily to stop cracks caused by predominantly thermal effects and also facilitate the application of thicker layers.

The application of the coating materials can be done in dry weather in a known manner by brushing, rolling, brushing, drawing, pneumatic and hydraulic spraying. In order to avoid in particular continuous defects with certainty, the coating materials are applied at least two days at intervals of about one day, with a total order amount of at least 1700 to 2 200g / m ² results without any problems.

For a two-day coating, the top coat and top coat can be made of identical coating material or selected from a fibrous and a fiber-free coating composition.

The gas concrete surface to be coated can be both untreated, d. H. free from dust and loose particles, as well as be pre-impregnated in a known manner with aqueous or solvent-containing inlet primers.

Ausführungsbelsplole

(The details are given in parts by weight)

example 1

Crack-bridging, water-repellent coating material for exterior aerated concrete walls made of assembly elements 260 T. Polyacrylate dispersion 1.50% (tack-free drying)

125 T. Polyacrylate dispersion II, 50% (tacky - 20Ό

4 ... 5T. Notz and dispersant mixture based on polyacrylic acid alkali salt and Graham's salt (polyphosphate) 1 T. Defoamer / deaerator

2 ... 4 Γ. Ammonia25% pH-dependent at least up to pH 8.5

10 to 15 parts of antifreeze (for example 15 parts of 1,3-propanediol) are stirred successively in a running dissolver stirrer, then a solution of

8 T. methylsilicone resin in

15 ... 25T. Film forming aids, e.g. 25 T. white spirit, mixed.

In this mixture are dispersed intensively

50 T. color pigment, afterwards

175 T. Calcite flour A (grain freedom ... 60 μιτι)

85 T. Calcite flour B (grain clearance ... 200 pm)

After completion of the intensive dispersion, individually 0.5 to 4 T. microbicide / preservative according to the microbicidal effect of the preparation (4T. Kombinat HS 15 VEB CK Bitterfeld)

250 T. Filler C (calcite, marble and quartz 60 ... 500pm)

3.5 T. polyacrylate thickener between 2.5 and 4.5 T. Addition possible for the purpose of realizing a concrete intrinsic viscosity) The material is highly pseudoplastic, solid-rich and can be diluted to application consistency with 2 to 10 T. water to produce the processing capacity ,

The PVK is calculated 52%.

Gas concrete specimen with a predetermined breaking point and a two-layer coating with Example 1 (total 1700 ... 1900g / m ² )

after storage for 6 days at room temperature and measurement with a tensile tester, a <

Crack bridging distance of at least 2.5mm at 23 ⁰ C or at least 1, lmm at -1ü ° C.

The capillary water uptake with direct water immersion of analogously coated Gasboton test specimens yielded a distance of less than 0.3 kg / m ² h "x ⁶ under standard conditions The value of the measurement of the water vapor diffusion resistance for the same coating was less than 1.5 m under standard conditions.

Example 2

Rißüberbrückonder, water-repellent, fiber-containing coating material for exterior aerated concrete walls from Montageelerr.enten 342 T. Polyacrylate dispersion 1.50% (tack-free drying)

135 T. Polyacrylate Dispersion II, 50% (tacky - 20 ^c C)

3 to 4 T. Wetting agent and dispersant mixture based on polyacrylic acid alkali salt and Graham's salt (polyphosphate) 1 T. Defoamer / deaerator

3 to 4 T. Ammonia 25% pH-dependent, at least up to pH 8.5

10 to 12 T. antifreeze (eg 12 T. Propandiol 1.3) are stirred one behind the other in a running dissolver agitator, then a solution of

8 T. methylsilicone resin in

15 to 25 T. film-forming aids, z. B. 25 T. white spirit, mixed.

In this mixture are dispersed intensively

50 T. color pigment, afterwards

142 T. Caica flour A (grain clearance ... 60 pm)

70 T. Calcite flour B (grain clearance ... 200pm)

After completion of the intensive dispersion, stirring is carried out individually until homogeneous distribution 0.5 to 4 T. Microbicide / preservative (according to the effect)

12 to 15 T. polyacrylonitrile short cut fibers V »mm and 1.7 tex, up to the fiber acceptance limit 203 T. Filler C (calcite, dolomite and quartz 60 ... 500pm)

4 T. polyacrylate thickener.

The (material is highly pseudoplastic, solid-bodied and can be diluted to application consistency with 10 to 20 T. of water to make the processing capability. The PVK is calculated to be 42%.

Concrete specimens with a predetermined breaking point and a two-layer coating with Example 2 (a total of 1700 to 1950g / m ²⁾ gave, after 60tägiger storage at room temperature, and measurement with a tensile tester a Rißüberbrückungsweitevon at least 3.0mm at 23 ⁰ C, or at least 1.5 mm in -10 ° C.

The capillary water absorption in direct water immersion of analogously coated gas concrete test specimens gave a value of less than 0.3 kg / m'h ° ' ^s under standard conditions. The value of the water vapor diffusion resistance was less than 1.8 m under standard conditions.

With the coating materials of Examples 1 and 2, aerated concrete outer walls of hot buildings after a corresponding pretreatment two-layer coating in the form that either two layers of the same material of Example 1 or 2 or a base coat of Example 2 with a Deckbeschlchtung according to Example 1 combined to apply. For this purpose, to begin with the pretreatment of the gas concrete by removing dust and loose particles, optionally with a known to ε> aqueous (based on polyacrylate dispersion) or solvent-containing inlet primer (based on a polyacrylate-chloropolymer combination) of the gas concrete impregnate. On the wordon then first a layer of the coating material with 800 to 1100g / m ² and after a day of intermediate drying, the second layer with 800 to 1100g / m ² , total 17OO ... 22OOg / m ² applied. The job can be done by brushing, rolling, brushing, drawing, pneumatic or hydraulic spraying. Due to very small additions of water, the original consistency can be adapted to an application consistency.

A special favorable and functionally reliable aerated concrete coating is obtained if one chooses the base coating fibrous and the Deckbeschlchtung fiber-free. , Still be bridged by means of this coating, which is capable of cracks at 23 ⁰ C up to 3.0 mm and at -10 ° C up to 1.5 mm crack width, a capillary water uptake of 0.3 kg / m ² · h ^{0 6} and a water vapor diffusion resistance value of 1.5m, a permanent gas concrete protection can be achieved up to 10 years. This means a 10-year maintenance of the thermal insulation of the wall without repeating coating, while at the same time lasting adhesion and color stability of the coating without coating destruction.

Claims (1)

Use of aqueous crack-bridging coating materials for exterior gas concrete walls of hot buildings on the basis of polymer dispersions, pigments, fillers and excipients and optionally synthetic fibers, characterized in that the coating material as a binder, a mixture of 20 to 45 parts by mass in% of a dispersion based on pure acrylate, in the temperature range of 253K to 293K to give tacky films, and 80 to b5% by weight of a pure acrylate-based dispersion having tack-free filmability of between 301 and 303K, the filler / pigment volume concentration being between 42 and 55% by volume with grain size distribution of customary inorganic granular or lamellar substances between 0.1 and 500 pm, of which at least 30 parts by mass in% have a particle size of 60 to 500 pm. Field of application of the invention The invention relates to colored coating materials based on aqueous dispersion for exterior walls of hot buildings of large-sized aerated concrete elements. Characteristic of the known state of the art Based on the fact that aerated concrete is a very special building material, special requirements are to be made on suitable means for its coating. Only when it is reached and maintained can certain advantages of this material, such as durability and excellent thermal insulation, be ensured. The high level of thermal insulation in the dry state would be lost if it was soaked, whereas the unprotected aerated concrete is very vulnerable. Therefore, to demand from a gas concrete coating that it allows only values of less than 0.5 kg / m ^J h ^0j6 capillary Wassoraufnahme, such a coating material can thus be applied dickgenuy and is dense enough to interfere with the water absorption capacity of the gas concrete permanently. However, it proves to be a special problem that arise in gas concrete principally due to hygrischer, thermal and / or mechanical stresses close to the surface, opening shrinkage and hairline cracks after coating. Only if these do not propagate into the coating, for example by crack propagation or delamination, the capillary water absorption can be permanently suppressed. This requires a gas concrete well adhering and over the opening cracks very elastic coating, which must be very flexible and in their layer thickness must have a sufficient expansion reserve for constrictions. On the other hand, it is necessary that such a gas concrete coating remains sufficiently permeable to water vapor, so that the production moisture contained in the aerated concrete as well as the moisture of antrophogner origin can be dissipated and the wall can be kept dry. The internationally accepted and valid limit value of the water vapor diffusion resistance is a maximum of 2.0 m, based on an air layer thickness set as a diffusion equivalent. Its exceeding would lead to the wet accumulation in the wall and thus also to the loss of the required thermal insulation.
With respect to the layer thickness of otherwise equivalent coated layers, the following relationship should be assumed: if layer thickness a) high b) lower then water repellency lower then better reducing crack bridging then durability higher worse but water vapor permeability too low better. These building physics requirements for the building material gas concrete and this to a gas concrete coating detlv.lb to make demands (see H. KÜNZEL: gas concrete, heat and moisture behavior - Wiesbaden and Berlin, 1971: Bauverlag GmbH) corresponds to none of the known building protection of otherwise partially full of high efficiency. Bokannt are highly filled coating materials based on different aqueous polymer dispersions for coating mortar plaster on facades and different concretes, which are also used for outdoor concrete aerated walls and are marked accordingly. It is generally possible to apply thick layers to them, which, however, calls into question the provision of sufficient water vapor permeability with sufficient ability to break cracks. Further, by using more flexible polymer dispersions, by combining with plasticizers and / or other flexibilizing binders, as well as by increasing the binder content, it has been attempted to provide crack bridging capability which overcomes due to aging processes such as polymer degradation by UV rays and hydrolysis Oxidation, migration and volatilization, with only limited improvements. Only the consideration of the interaction of contraction and Fxpansion by thermal influences on substrate and crack, the dependence of the coating properties of climate-induced temperature limits lead to new solutions, especially for the use of mixtures of the same aging quality of highly weathering, especially UV-stable polyacrylate dispersic (DE 1272803 / US 4390570 / GB 1534043 / JA 79-24944) with high-expansion polymer components (DE 1272803 / GB 2026003 / JA 79 24944) or polymer proportions with extremely low glass transition temperature T ₀ (GB 1534043 / US 4390570) with flexibilizing effect. The mixing ratios of the polymer components are given in part within very wide limits.