JPH0127013B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing gypsum boards (gips karton platten) for the building industry with hydrophobic properties. In this method, as in conventional building board manufacturing, an aqueous slurry of gypsum is applied to a continuous, horizontally laid Karton that covers the face and edges of the gypsum building board. The upper edge for the back side of the plaster board is placed on top of the plaster water slurry and applied to the protruding side areas of the lower edge.
The gypsum aqueous slurry is mixed with other additives that give hydrophobic properties to the gypsum board after heating and drying and allow it to remain exposed to higher moisture loads than normal building boards. Ru.

A building material that would make plaster water resistant has been desired for a long time. According to many publications,
Water-repellent substances and lime were also added to the plaster. Agents used in recent years are, inter alia, silicones, paraffin wax emulsions, ceresin, waxes, picyumen, resin emulsions and also water-soluble silicates. Disregarding water-soluble silicates, their water-resistance imparting action is primarily due to their tendency to mechanically inhibit the movement of water. The effect of this additive depends primarily on the size and distribution of the emulsion particles. Numerous patent documents describe water-repellent properties for plasters, which are combined with additives such as wax and/or asphalt and corn flour and potassium permanganate; water-insoluble thermoplastics. and petroleum and natural asphalts, coal tars and polymers based on vinyl azide and vinyl chloride; alkali metal-resin soaps;
Water-soluble alkaline earth metal salts and fuel oil residues, pine resin and coal tar; fuel oil residues and resins; aromatic isocyanates and diisocyanates; organic hydrodiene polysiloxanes; wax-asphalt emulsions; polyvinyl alcohol adducts and metal components; This is accomplished by using an aqueous emulsion additive consisting of asphalt/wax together with calcined gypsum and small amounts of borate compounds.

In the process for impregnating or hydrophobizing plasterboard, the problem of adhesion between paperboard and plaster also plays an important role. The overwhelming number of hydrophobizing agents are
This can adversely affect the tight bond or cause the board to delaminate from the plaster due to the influence of moisture and, in addition to adhesion problems, has an undesirable effect on the quality of the board. Furthermore, it has been found that the strength in gypsum boards is reduced and the water resistance decreases over time.

In Federal Republic of Germany Patent No. 1266200,
The production of water-repellent plasterboard coated with paper is a problem. Plaster pastes are formed between paper channels and for this purpose water-repellent substances are used, namely emulsions consisting of toluene, wax-like aliphatic hydrocarbons and drying oils and/or aliphatic esters of pentaerythritol. This emulsion is brought onto paper,
It is then heated in a furnace to a temperature of at least 130°C.

However, this surface impregnation suffers from the disadvantage that the plaster suffers if the paper layer is damaged or if atmospheric moisture or dew passes through the building board and fills the conduit. German Democratic Republic Patent No. 125861
According to the method of No. 1 and No. 130,133, the product is impregnated onto concrete, plaster and clay bases with liquid paraffin to make it impermeable to pressure water. For the same purpose, German Democratic Republic Patent No. 132,426 proposes a melt impregnation method. Paraffin grease or paraffin-bituemen granules are added to the starting material and the product is dried after manufacture. The molten impregnating agent enters the pores, cools and plugs them. However, as practice has shown, sufficient water resistance in plaster is only achieved with the addition of about 15% by weight of paraffin. This method is uneconomical due to the high material costs.

In German Patent Application No. 2614394, inter alia paraffin is also used. Emulsions are made and used to obtain economical applications. The solids proportion of the hydrophobizing agent to the gypsum hemihydrate is 5% by weight. In particular, paraffin emulsions are used, the manufacture and composition of which is subject to patent protection. For the production of gypsum board, the drawback is the necessary purchase of emulsion equipment, storage capacity for at least five starting materials and the employment of skilled personnel for the complete technical process of addition and metering of the components. However, for emulsions from chemical plants, 65% of water has to be additionally transported; furthermore, the stability and storage capacity of this emulsion is limited, and in cold seasons thermal insulation of tank storage is required. It is.

The object of the invention is to provide a generally hydrophobic material which, with as little use as possible of hydrophobizing additives, has the same building-technical properties as normal gypsum board and which can additionally be used in rooms with relative temperatures of more than 75%. The goal is to economically produce stone gypsum boards.

The present invention seeks to find a method for the hydrophobization of plaster, in particular for making plasterboard that ensures resistance to plaster/paperboard adhesion as well as to the sometimes high moisture content of the surrounding air. Set a challenge. According to the invention, this problem is achieved by adding water to a hard wax as a hydrophobizing agent or a hard wax in combination with a solid hydrocarbon in powder form and/or in granules together with plaster;
The problem was solved by mixing the slurry into a complete slurry or by mixing the hydrophobizing agent into the gypsum water slurry. That is, the present invention provides a method for making hydrophobic plaster for plasterboard, in which a hemihydrate and/or anhydride and less than 4% by weight of hard wax, especially montan wax or a solid hydrocarbon. A mixture of solid or finely powdered additives is placed in water, and after the setting of the gypsum, a chemical reaction is caused by heat treatment, in which the carboxyl groups of the hard wax, especially the montan wax, and the cement Provided is a method characterized in that partial saponification occurs between the cations of the gypsum, thereby significantly suppressing the capillary suction force of the gypsum. In this method the setting process and the wet plaster/board bond remain unaffected. Dihydrate, hard wax and water exist side by side. In the subsequent heat treatment, the temperature in the dryer is controlled in such a way that at material temperatures of up to approximately 60° C., the gypsum board is completely dried to hardness with the formation of voids. The plate is then heated for a short time at about 85° C., so that the hard wax or hard wax combination melts and is able to penetrate into the existing voids with the aid of the residual water vapor pressure. A chemical reaction takes place during this process, resulting in the formation of a bond between the hydrophobizing agent and the binder (cement). This reaction is characterized by partial saponification,
There, the carboxyl groups of the hydrophobizing agent react with the resulting cations of the cement under short heating conditions. A concomitant improvement in bonding is achieved by the formation of a physical bond between the hydrophobizing additive and the cement due to the polarity of the ester groups. Preferably, the hard wax or hard wax combination has an acid rating greater than 5. In this case, a good impregnating effect is achieved by using mixtures in combination in suitable quantitative ratios, in which hydrophobic groups as well as hydrophilic groups are combined.

The water-repellent effect is provided by the blocking of the dihydrate skeleton by the hydrophobizing agent, whereby the tortuous capillary wicking forces for the plaster are significantly reduced or largely prevented. As additives, hard waxes such as montan wax and/or carnauba wax alone or in combination with solid hydrocarbons whose solidification point is 50 DEG C. come into consideration.
Taking into account the production of gypsum board according to this method, the hydrophobizing agent should be between 0.063 and 0.8 mm, preferably between 0.1 and 0.8 mm.
It has been found to be used in the form of microgranules with a particle size range of 0.5 mm. A particularly hydrophobicizing effect is achieved when using combinations with a proportion of solid hydrocarbons of at least 10%. This is because the resulting reduction in the melt viscosity creates favorable conditions for the described reaction. Additives 65-90℃
It has a melting point of , and the volume expansion in the melting range is 5.0~
12.8% and a melt viscosity at 90°C of 15 cP to 70 cP is preferable.

The composition is the system used for the targeted achievement of the desired architectural physical properties of the plasterboard.
Depending on the CaSO ₄ -H ₂ O modification, it varies from 90 to 25% hard wax and 10 to 75% solid hydrocarbon. The respective predetermined proportions are melted, mixed in liquid state and sprayed into microgranules. By the use of fine granules in the form of a combination of solid hydrocarbons and hard waxes, for example in the case of paraffin wax mixtures, the melting point can be brought to the heat treatment range desired for gypsum board production as described and the melt viscosity of the hydrophobizing agent is lowered, making it easier for the escaping water to penetrate into the voids formed,
The desired conditions for the rapid chemical reaction of saponification are then set up. This brings the required addition amount to less than 4% by weight, which is still unusual compared to such hydrophobizing agents customary in the industry and reported in the literature in the treatment or production of gypsum boards. is reduced to the amount of Hydrophobic gypsum boards according to the invention can also be made with a proportion of the paraffin wax mixture of about 3% by weight relative to the amount of gypsum hemihydrate used. Its properties correspond to those of ordinary building boards and, in addition, are significantly water resistant. This means that a large number of approximately 100 m ²
This was confirmed by measurements of 40 samples (400mm x 300mm) taken at various locations from the plasterboard made of. The average water absorption is 1.48% after 2 hours.
4.1% after 24 hours, 6.5% after 96 hours and 6.8% after 120 hours. Stored water is replaced every 24 hours.
Along with this desirable value, the hydrophobizing agent simultaneously provides the desired strength of the paperboard against short-term overheating in the dryer. Further improvements in properties such as strength, water resistance etc. occur when, under the conditions mentioned above, the water requirement of the used plaster cement is reduced in order to obtain working hardness and thereby a denser structure is created. It becomes possible. This is possible, for example, by the use of α-hemihydrate cements or anhydride cements or by the addition of customary hemihydrate gypsum liquefiers, such as melamine resins. However, good results are also obtained when foaming- or pore-forming substances are added to the stone slurry to reduce the apparent density of the finished board. In fact, the bending strength is inferior to normal building boards, but the hydrophobicity of the light boards thus produced corresponds perfectly to the requirements for the construction of damp rooms.

Claims (1)

[Claims] 1. A method for making hydrophobic plaster for plasterboard, in which a hemihydrate and/or anhydride and less than 4% by weight of hard wax or a solid hydrocarbon in combination with A mixture of finely powdered additives is placed in water and, after the gypsum has set, a chemical reaction is caused by heat treatment, during which
A method characterized by causing partial saponification between the carboxyl of hard wax and the cation of cement, thereby significantly suppressing the capillary suction force of soap. 2. The method of claim 1, wherein the hard wax or combination containing the same has an acidity rating of 5. 3 Combinations containing hard waxes range from 90 to 25
% hard wax and 10-75% solid hydrocarbons. 4. A method according to claim 1, 2 or 3, in which the individual components are mixed in the molten state in the hard wax-containing combination. 5. Claims 1, 2, 3, or 4, in which the hard wax or hard wax-containing combination is sprayed into fine granules.
The method described in section. 6. A method according to claim 1 or claim 3, using a hard wax or a hard wax-containing combination having an acidity ratio greater than 6.5 and which undergoes a partial saponification reaction with the cement under the conditions of heat treatment of the hardened plaster. . 7. A process according to any one of claims 1 to 6, wherein the partial saponification is carried out at a temperature above 60°C. 8. Claims 1, 2, 3, 5 or 8 using hard waxes in the form of granules with a particle size range of 0.063 to 0.8 mm and/or their combination with solid hydrocarbons. The method described in Section 6. 9. Claim 1, wherein the additive has a melting point of 65 to 90°C, a volumetric expansion in the melting range of 5.0 to 12.8%, and a melt viscosity of 15 to 70 cP at 90°C; The method according to item 2, 3, 5, 6 or 8. 10. A method as claimed in claim 1, in which a substance having a liquefaction effect is additionally introduced, especially in order to obtain a structure. 11 To make a lightweight hydrophobic stone board,
2. A method as claimed in claim 1, in which a pore or bubble forming substance is added.