DE1126792B - Dry mortar mix - Google Patents

Description

Dry plaster mortar mixture The invention relates to a plaster mortar mixture from lime gypsum mortars and especially those mixtures which calcium hydroxide and Contains calcium sulfate hemihydrate with added retarder.

So far this has been the most common in the production of such plastering mortars satisfactory process, the dry, possibly with a. Delay means mix in the mixed calcium sulphate hemihydrate in a so-called "lime dough made of quicklime", this lime dough contained half its weight in water. and for several weeks Keep one by slaking quicklime with more water than to form Slaked lime required, subsequent chopping and sieving of the dough obtained became. While mixing, an additional amount of water was added to make a mortar of suitable consistency. It is also known to use the dried hemihydrate added to a retarder and, if necessary, additional water a dough made from commercially available dry slaked lime and water add which has been kept for at least 16 hours and preferably longer. However, the plaster mortars obtained are even when using one for the Manufacturers recommended times of slaked lime ripened dough from well Underlay matured lime dough made from quick lime. Insufficient ripening of the lime leads, among other things, to the disadvantages that the amount of water required to achieve a plaster mortar with a consistency suitable for the application can, is less that the plastering mortar does not flow so well under the trowel and that when freshly applied to an absorbent pad, easier Shrinkage and cracking occur. This type of cracking is called "heat cracking" known. Although there is obviously an economic advantage in getting one off to use slaked lime instead of quick lime made lime dough, pull many plasterers still use a lime dough made from quicklime as a basis for making their gypsum lime mortars, as they find it difficult to with dry slaked lime as the starting material a plastering mortar with under to produce the above-mentioned aspects satisfactory properties. Further It has always been the case in the production of such plastering mortars from slaked lime still need to make a lime dough and let it mature before that with one Gypsum hemihydrate was added as the hemihydrate was in solidify for a much shorter period of time than that required for the lime dough to mature target.

From the German patent specification 694 037, the production is more gypsum-based Compounds for filling or surface design of masonry; Walls, doors etc. with prolonged setting time of the plaster known in such a way that the Fired plaster of paris in a dry state or in a state mixed with water in an anhydrous state or nearly anhydrous organic solvents insoluble, water-soluble cellulose ethers clogs. However, the presence of slaked lime is not mentioned in it.

The German patent specification 868 572 discloses a plaster mortar and Filler, which is made from a water-soluble cellulose derivative and inorganic There are fillers of different grain sizes and contains so much water that the The mass has a pasty or plastic consistency. Here, too, slaked lime is nowhere called.

From the German patent specification 935 898 is a dry mortar mixture known from slaked lime and calcium sulfate anhydrite. This has the disadvantage that a substantial calcium hydroxide content causes slower setting and one Plaster of lower hardness with a tendency to crumble and due to shrinkage supplies with bad cracking. Also the French patent specification 1 157 637 describes a dry mortar mixture made of lime and gypsum, without the cited ones Eliminate disadvantages.

It would now be very desirable if a plasterer were to use a gypsum lime mortar by mixing dry slaked lime and with a retarder suitably provided gypsum hemihydrate and adding the necessary amount of water could produce to the dry mixture obtained and the plaster mortar thus obtained would be suitable for use without any maturation period.

The invention relates to a novel dry mortar mixture which from a mixture of dry slaked lime, calcium sulphate hemihydrate with additives of a retardant and a small percentage - "one finely divided Alkyl, hydroxyalkyl or alkyl hydroxyalkyl cellulose ethers having a viscosity of at least 500 cP in 2% aqueous solution at 15 ° C, the weight ratio from calcium sulfate hemihydrate to calcium hydroxide is from 4: 1 to 1: 4.

The cellulose ether should preferably be fine enough to fit a 0.15 mm sieve to happen, and a material of the required fineness can be obtained by grinding the cellulose ether can be obtained in a fibrous or non-fibrous state. Generally around the less cellulose ether needed, the higher its viscosity, and it is preferred Material with a viscosity of at least 2000 cP in a 20% aqueous solution at 15 ° C used. In general, an amount of about 0.2 to 1.0 percent by weight, based on the solids. Methyl cellulose, hydroxyethyl cellulose and Methyl hydroxyethyl cellulose are commercially available with the viscosities mentioned above and can be used. The products currently with the highest viscosity Commercially available are methyl cellulose and hydroxyethyl cellulose with approximately 4250 eP viscosity, and these are particularly suitable.

The water can be the solids on a board, in a bucket or Tank using a hand mixer or a simple mechanical mixer are mixed in. If desired, the mixtures can contain mineral fillers or vegetable and coloring matter. Among these are substances such as Sand or fibrous fillers or those of low density, such as asbestos or Perlite, mentioned.

An advantage of the invention is that the admixing of the water to the dry hemihydrate-slaked lime mixture or vice versa is that of less skill and supervision and also less physical exertion as the incorporation of gypsum hemihydrates and water into a matured one Lime dough, and it is obviously an advantage that there is no time for the Lime component is required. The plaster mortar obtained must of course be used before it solidifies due to the hemihydrate content.

Further advantages compared to the plaster mortar produced according to the invention Hemihydrate mortars made with slaked lime or quick lime are including the following: They contain the for spreading with the trowel on most desirable consistency more water per part by weight of dry solids and are therefore more economical to use; they tend to use less shrinkage and formation on absorbent surfaces when fresh of heat cracks; the water gets from them through the absorbent surfaces absorbed at a slower rate, so that when the hemihydrate ingredient the solidification of the plaster mortar on the surface causes the coating in one is in a damp condition and smoothed more easily with the trowel the last time it was applied can be; they adhere better to surfaces when dry, such as concrete, Wood and plaster components, and the dry plaster coating is less brittle.

Although the addition of cellulose ethers to plastering mortars and doughs, made from gypsum hemihydrate in the absence of lime, the slope of the liquid material to adhere to the trowel, noticeably increased, have the invention Plaster mortar does not have this disadvantage, although on the surface, on which they have been applied, adhere well after solidification and drying.

The invention is illustrated by the following examples, parts and percentages are based on weight.

Example 1 50 parts of powdered slaked lime was mixed with 50 parts gypsum hemihydrate with a retardant and 0.3 part methyl cellulose with a viscosity of 4000 cP in 2o / () iger aqueous solution at 15 ° C, which in Shape of a fine, fibrous; powder passing through a 0.15 mm sieve was added. 70 parts of water were added to the whole of the dry, solid mixture, their Particles were quickly wetted. The contents of the mixing vessel were then with the help mixed by hand with a mixer to produce a plaster mortar, which ready for immediate use as interior finish plaster for walls and ceilings.

Example 2 Following the procedure of Example 1, 75 parts became more powdery slaked lime, 25 parts of gypsum hemihydrate with a retardant, 0.5 parts of hydroxyethyl cellulose in the form of a fine fibrous powder, which passed through a 0.15 mm sieve and had a viscosity of 4500 cP in 2o / o aqueous Solution and mixed 81 parts of water. The plaster mortar obtained could immediately can be used as interior wall or ceiling plaster.

Example 3 Following the procedure of Example 1, 33 parts became more powdery slaked lime, 67 parts of gypsum hemihydrate with a retardant, 0.25 part of methyl hydroxyethyl cellulose in the form of a fine powder, which went through a 0.15 mm sieve and a viscosity of 3500 eP in 2o / oiger aqueous Solution showed and 58 parts of water mixed. The plaster mortar obtained was suitable for the same purposes as that of Example 1. Example 4 The solid additives passed from a mixture of 50 parts of powdered slaked lime, 50 parts with a Delay means provided Gypsum hemihydrate and 0.7 parts methyl cellulose in the form of a fine fibrous powder which passed through a 0.15 mm sieve and had a viscosity of 1500 cP in 2o / o aqueous solution. The mix of Solids were added to 71 parts of water and the contents of the mixing vessel with mixed with a paddle. The plaster mortar obtained was for immediate use for the same purposes as in example 1 done.

Trial plasters, which are made from plaster mixes according to the Examples 1 to 4 passed, the last plaster applied to partition walls showed a satisfactory adhesion for more than 1 year, and oil paints, which over one normally recommended for use over alkaline plastering Primer applied, adhered well for more than 1 year.

Claims (6)

PATENT CLAIM: 1. Dry plaster mortar mixture, consisting of dry slaked lime and calcium sulfate hemihydrate with the addition of a retarder, characterized by a small percentage of a finely divided alkyl, hydroxyalkyl or alkyl hydroxyalkyl cellulose ether. 2. Dry plaster mortar mixture according to claim 1, characterized in that the cellulose ether in an amount of approximately 0.2 to 1.0 percent by weight, based on the ingredients, is used. 3. Dry plaster mortar mixture according to claim 1 or 2, characterized in that the cellulose ethers methyl cellulose, hydroxyethyl cellulose or methylhydroxyethyl cellulose is. 4. Dry plaster mortar mixture according to claim 3, characterized in that the cellulose ether methyl cellulose or hydroxyethyl cellulose with a viscosity of about 4250 cP in 20% aqueous solution at 15 ° C. 5. Dry plaster mortar mixture according to claim 1, characterized in that the cellulose ether is sufficiently fine to go through a sieve with 0.15 mm mesh size. 6. Dry plaster mortar mixture according to claim 5, characterized in that it contains a filler or a dye. Considered publications German Patent Nos. 935 898, 868 572, 694 037; French patent specification No. 1 157 637.