EP1250393A1

EP1250393A1 - Shaped body containing dye for producing an aqueous binding agent system

Info

Publication number: EP1250393A1
Application number: EP00979670A
Authority: EP
Inventors: Peter Schmiedel; Ingo Hardacker; Bernhard SCHÖTTMER; Martin Roth
Original assignee: Henkel AG and Co KGaA
Current assignee: Henkel AG and Co KGaA
Priority date: 1999-12-15
Filing date: 2000-12-07
Publication date: 2002-10-23
Also published as: RU2002119020A; DE10056007A1; AU1707501A; WO2001044399A1; RU2267510C2

Abstract

The invention relates to a shaped body consisting of substances for producing an aqueous binding agent system which contains preferably between 30 and 100 wt. % of water-soluble or water-dispersible inorganic or organic, natural or semi-synthetic polymers, which are non-adhesive in their dry state at an ambient temperature and between 0 and 70 wt. % of fully synthetic polymers as binding agents. Said shaped body is constructed of at least two different phases, of which at least one contains a dye and which are positioned in the shaped body in such a way that they can be optically differentiated on the surface of the shaped body. The dye is preferably decolourised during or after the production of the aqueous binding agent system.

Description

Dye-containing molded article for producing an aqueous binder system

The invention relates to dye-containing molded articles made of substances for the production of an aqueous binder system, their production and use.

Dry mixtures based on cellulose and / or starch derivatives, which are used for the production of aqueous adhesive preparations, are known. Such aqueous adhesive preparations are widely used for gluing wall coverings to walls. In particular, it is (wallpaper) paste that is used for wallpapering walls and ceilings.

Such wallpaper paste is made from different dry mixtures.

For example, DE-A 31 03 338 describes a dry paste product based on powdered cellulose ethers. Granules with grain sizes of about 100 to 600 μm are used, which are obtained by granulating finer powders. The granules are quickly soluble, but have a low bulk density.

WO 99/03945 describes aggiomerates for the production of an aqueous binder system, which are used in particular as wallpaper paste. They contain water-soluble or water-dispersible re base polymers and optionally also fully synthetic polymers and also contain a disintegrant which facilitates the dissolving or dispersing of the agglomerates.

The presentation of the wallpaper paste described in tablet form facilitates dosing and avoids dirt and dust during use. Presentation in tablet form has already proven itself many times in the field of detergents.

In contrast to powders, the use of tableted products requires more precise control of the dissolution of these products before use. For example, a complete dissolution or dispersion of a paste tablet must be ensured before it is used for wallpapering.

From JP-A 76 2744 it is also known to provide adhesives and paste with dyes in order to visually indicate the adhesiveness. For example, a dye component is incorporated into the wallpaper paste and a wallpaper is coated with it and dried. Before gluing, the wallpaper is moistened again, the aqueous medium used for moistening containing a second dye component. By reaction of the two dye components, a dye is formed in the paste, which thus indicates the wetting and thus the adhesiveness of the paste. The dye is only formed when the paste is adhesive. It is also described that one of the dye components in microencapsulated form can be present in the dried paste alongside the other dye component. Moisturizing destroys the water-soluble microcapsules and the dye forms on the moistened paste. Different dye systems are listed, which are see or implement two components to generate the dye. A disadvantage of this procedure is that with some materials, especially with light and thin wallpapers, the dye can show through the wallpaper. The dye thus hinders the aesthetic effect of the glued product.

Starting from the prior art, the object of the invention was to avoid the disadvantages listed and to provide a shaped body made of substances for the production of an aqueous binder system, in particular a wallpaper paste in tablet form, in which it is visually indicated when an aqueous binder system obtained from the shaped body is ready for use ,

Furthermore, it should be possible to visually indicate the presence of certain components in the molded body to the consumer.

The object is achieved according to the invention by a shaped body made of substances for producing an aqueous binder system, the shaped body being composed of at least two different phases, at least one of which contains a dye, and which are arranged in the shaped body in such a way that they are on the surface of the shaped body are optically distinguishable. The at least two different phases are preferably different in color. The shaped body preferably contains 30 to 100% by weight of water-soluble or water-dispersible, inorganic or organic, natural or semisynthetic polymers which are not tacky in the dry state at room temperature and 0 to 70% by weight of fully synthetic polymers as binders. The dye is preferably decolorized during or after the preparation of the aqueous binder system. It has been found, according to the invention, that molded articles made of substances for the production of an aqueous binder system, in particular wallpaper paste tablets, can be colored in such a way that the coloring preferably disappears during or after the preparation of the aqueous binder system and before the same is used. The disappearance of the coloration can thus optically indicate the processability of an aqueous binder system. This simplifies the use of the shaped body made of substances for producing an aqueous binder system and in particular wallpaper paste tablets. No additives are required during use to determine the processability of an aqueous binder system. In addition, the presence of certain additives in the moldings can be indicated to a consumer in a visual manner. For example, the presence of substances modifying the adhesive force or viscosity can be indicated. This makes it possible to distinguish differently shaped articles or tablets from one another by choosing different dyes or different distribution of the dyes in the tablet. This can, for example, prevent confusion between different wallpaper paste regardless of their packaging.

According to the invention, the shaped bodies are constructed from at least two different phases. The term “phase” does not refer to the state of matter, but to areas or portions of the (solid) shaped body that are constructed differently. For example, both phases can be constructed from the same binder, but one phase additionally contains a dye dyes can also be present in different concentrations in both phases. In addition, the phases can also have the same coloring, but differ in their structure lying on the surface. For example, one phase can appear grainy and the other appear smooth. This can for example, be caused by the production by pressing one phase from a powder or granulate, but casting the other phase. It is therefore important that the phases on the surface of the molded body can be distinguished visually, as a result of which the different phases can be identified.

At least one of the phases contains a dye. This can be any substance that gives the phases of the molded body a colored appearance or makes the different phases of the molded body optically distinguishable. The dye can thus be inorganic or organic pigments as well as dyes dissolved in the phase. The type of dye can be chosen as desired. Depending on the desired embodiment, any natural or synthetic coloring substances or dyes or colorants can be used. The dye serves to color the respective phase of the shaped body and should therefore be compatible with the constituents of the individual phases of the shaped body. Adhesion to substrates such as textiles is not important. The term “dye” is thus to be understood to the broadest extent and is not restricted to specific dyeing properties, such as are relevant, for example, in textile dyeing.

The preferred decolorization of the dye during or after the production of the aqueous binder system ensures that the dye cannot have a negative influence on the appearance of, for example, a wallpaper. It is harmless, for example, if adhesive residue gets on the face of the wallpaper.

The moldings according to the invention are constructed from at least two different phases which are arranged in the moldings that they are optically distinguishable on the surface of the molded body. It is thus clear to the user of the tablets simply by looking at the shaped body that there are at least two different phases with a different composition in the shaped body. The phases can be present in the shaped body in any desired manner and can be distributed as long as it is ensured that the user recognizes the multiphase nature. For example, the phases can form two or more layers, or one phase can be distributed in granular form with an average particle diameter of 0.5 to 10 mm in the other phase, or one phase can concentrically enclose a cylindrical core of the other phase, so that the End faces of the core remains visible (two-phase toroidal tablet). According to the invention, one phase should not form the core of the molded body and another phase should form a final shell around it. The different phases should be recognizable at least in an outer surface area of the molded body.

The shaped bodies according to the invention can have any suitable geometric shape. For example, they can be in the form of spheres, cylinders or cuboids or in other three-dimensional geometric shapes such as tablets, bars, tablets, etc. They are preferably in such a geometric shape that allows the moldings to be packed tightly. Such shapes are regular shaped bodies, such as spheres, ellipsoids, cylinders or cuboids. The moldings can have a significantly smaller extent in one spatial direction and thus be flat. However, like in a sphere or in a cube, they can also have the same dimensions in all spatial directions. The tablets are particularly preferably in the form of cylinders or cuboids, edges being rounded or faceted. The size of the moldings can be freely selected in a wide range. Shaped bodies with a geometric shape are preferred which can contain at least one hypothetical cube with an edge length of 2.5 mm in their interior. The shape should allow easy handling of the shaped bodies during storage and use. For example, the weight of the moldings should allow the production of customary portions of aqueous adhesives or pastes without the need to use other measuring aids such as scales. The moldings preferably have a weight of 0.5 to 500 g, in particular 1-100 g. If the shaped bodies have notches such as, for example, in a divided panel, the fractions should have a weight of at least 1 g.

The shaped body according to the invention is particularly preferably a two-phase and two-layer tablet in the shape of a cylinder or cuboid. Approximately equal parts by volume of the shaped body can be present in each layer or phase.

According to the invention, the dye is preferably decolorized during or after the preparation of the aqueous binder system. The decolorization is preferably carried out by interaction of the dye with a further component which is contained in a phase not containing dye, or by interaction with an aqueous medium.

The dye can be decolorized by any suitable interactions that are possible in an aqueous medium, and there should be no back reaction under the conditions of use. For example, the decolorization of the dye is achieved by oxidation, reduction, change in pH or by hydrolysis. The oxidizing agent, reducing agent or agent for changing the pH can be present in a further phase which contains no dyes. In a preferred two-phase embodiment of the shaped body, the dye is thus present in one phase and a decolorizing substance in the second phase. When dissolved or dispersed in water, the dye and the decolorizing substance can interact, in particular undergo a chemical reaction, so that the aqueous binder system obtained is decolorized. Another possible decolorization mechanism is the photochemical bleaching of the dye.

In the oxidation, the dye can be a bleachable dye that is bleached with a bleaching or oxidizing agent from the second phase. For example, the dye can be aniline blue, while a bleaching agent usually used in detergents is used as the bleaching agent. For example, a perborate such as sodium perborate can be used. Other suitable bleaching agents are organic or inorganic peroxides, such as percarboxylic acids in monomeric or polymeric form, or perhydrates, such as the sodium percarbonate frequently used in detergents. Since wallpaper paste or other aqueous binder systems are generally prepared at room temperature, the dye is preferably bleachable at room temperature. The bleach should have sufficient activity for this. If necessary, a bleach activator or bleach booster can be added. This bleach activator or bleach booster is preferably added to the dye in order not to release the bleach prematurely. The concentration of the bleaching agent should be such that rapid bleaching of the dye takes place, but an unfavorable influence on, for example, wallpaper or another substrate is avoided.

The dye is in the dye-containing phase in an individual case to be tested, sufficient for coloring the phase, preferably in an amount of 0.001 to 5 wt .-%, particularly preferably 0.01 to 2 wt .-%, based on this Phase. The amount will vary depending on the "coloring power" of the dye. The amount of the decolorizing substance can be determined by simple experiments and should be set so that rapid decolorization of an aqueous binding system obtained from the shaped body is ensured. The weight ratio of bleach to dye depends strongly depends on dye and bleach and can be determined by simple tests in practice.

When bleaching by oxidation, either the dye itself is oxidized and thus broken down into colorless compounds, or a metal ion contained in the dye is oxidized, so that the dye loses its color.

In the case of corresponding dyes, the dye can also be decolorized using a reducing agent, for example by reducing a metal ion contained in the dye so that the dye loses its color.

Suitable dyes and oxidizing or reducing agents are known.

The aqueous binder system obtained from the shaped body or the wallpaper paste tablet should preferably be based on the dye with the decolorizing compound can be decolorized within a short time, preferably within 20 minutes or less. Depending on the choice of the decolorization mechanism, spontaneous decolorization can also be achieved. With a suitable choice of the amounts or the dye and the decolorizing substance, the decolorization can be correlated with an increase in viscosity when the wallpaper paste is applied. The decolorization can also be used as an indicator of the ready-to-use paste. Delaying the decolorization can also be achieved, for example, by microencapsulating the decolorising substance, the microcapsules slowly dissolving in aqueous systems. The type and thickness of the microencapsulation can be used to set the rate at which the decolorizing substance dissolves, so that the time at which the aqueous binder system is decolored can be freely selected within wide limits. With such a delayed decolorization, decolorization preferably occurs after 1 to 20 minutes, depending on how quickly the processable state of the corresponding product is reached.

In the case of pH-induced decolorization, a phase which contains no dye contains a pH-active substance which decolorizes the color of the colored phase by the pH change which occurs when the tablet or tablet disintegrates in water. It is expedient to use a dye which is colored in the acidic pH range and colorless in the alkaline pH range. Since many wallpapering bases are alkaline, the risk of recoloring is avoided. Due to the spatial separation of dye and decolorizing substance, decolorization is only achieved in this system when the aqueous binder system is being produced. In the shaped bodies according to the invention, the adhesive strength or the viscosity-modifying substances can be contained in at least one of the phases. For example, one of the phases can contain these modifying substances. It is also possible that the substances modifying the adhesive force and / or the substances modifying the viscosity are contained in the two phases in different concentrations. The presence of a dye in one phase can indicate the increased or exclusive presence of such modifying substances, wherein different colors can be assigned to different modifying substances. This makes it possible to provide a range of different shaped articles with different properties, for example for a large number of special applications, the different shaped articles or tablets being able to be distinguished from one another by means of the coloring. Such a distinction is particularly advantageous if the tablets or tablets have already been removed from a pack and are still intended to be distinguishable from one another.

A binder composed of 30 to 100% by weight of water-soluble or water-dispersible, inorganic or organic, natural or semisynthetic polymers which are not tacky in the dry state at room temperature and 0 to 70% by weight of fully synthetic polymers, based on the binder, is used in the moldings according to the invention , The natural or partially synthetic polymers are used as base polymers, with the fully synthetic polymers acting as a strengthening agent.

In addition to water glass, the base polymer is at least one of the following water-soluble or water-dispersible natural or partially synthetic polymers h question, especially if a paste is to be produced: a) starch and / or starch derivatives and b) cellulose derivatives, in particular cellulose ethers.

The starch should be water soluble, possibly water swellable. Modified starch is of particular interest, the modification being brought about by physical or slight chemical action. Specific examples are: partially degraded starch and swelling starch.

The starch derivatives should also be water-soluble and possibly water-swellable. Starch esters or starch ethers are of particular interest, especially carboxylated and alkoxylated starch. Suitable carboxylated and / or alkoxylated starches are all appropriately modified natural starch types from potatoes, corn, wheat, rice, milo, tapioca and the like, with derivatives based on potatoes and / or corn starch being preferred. The useful starch derivatives have a degree of carboxylation of 0.1 to 2.0 (DS) or an degree of alkoxylation of 0.05 to 1.5 (MS). The starch derivatives can also be cross-linked. Difunctional compounds are suitable as crosslinking agents. Crosslinking agents of this type are known (see, for example, EP-B-0 311 873, page 3, from line 49 to page 4, line 5).

The following types are particularly suitable as cellulose ethers: carboxymethylcellulose (CMC), carboxymethylmethylcellulose (CMMC), ethylcellulose (EC), hydroxybutylcellulose (HBC), hydroxybutylmethylcellulose (HBMC), hydroxydoxyethylcellulose (HEC), hydroxyethylcarboxymethylcellulose (HEC) (HEEC), hydroxypropylcellulose (HPC), hydroxypropylcarboxymethylceilulose (HPCMC), hydroxypropylmethylcellulose (HPMC), hydroxyethylmethylcellulose (HEMC), Methylhydroxyethylcellulose (MHEC), methylhydroxyethylpropylcellulose (MHEPC), methylcellulose (MC) and propylcellulose (PC), with carboxymethylcellulose, methylcellulose, methylhydroxyethylcellulose and methylhydroxypropylcellulose as well as the alkali metal salts of CMC and the slightly ethoxylated MC being preferred.

The cellulose derivatives can be slightly cross-linked so that they are soluble at a pH of over 8 and the solution in water is delayed. Crosslinking can be done by adding glyoxal or polyglyoxal. In order to ensure a pH of at least 8 in the solution after dissolution, there should be an excess of the basic component over the acid component. The pH is preferably in a range between 8 and 9.5.

It may be appropriate to use several base polymers together.

The water-soluble or water-dispersible, fully synthetic polymers, polyvinylpyrrolidone, polyacrylamide, polyvinyl alcohol or polyacrylic acid salts can also be used at least in part as adhesive strength enhancers. Polyacrylates with 1 to 8 carbon atoms in the alcohol component are preferred, as are vinyl polymers, in particular polyvinyl acetate.

Furthermore, redispersible dispersion powders of fully synthetic polymers can be used as adhesive strength enhancers. These are, for example, the following homopolymers and copolymers: vinyl esters, styrene, acrylate and vinyl chloride polymers: vinyl ester polymers suitable as base polymers are, for example: Vinyl acetate homopolymers; Copolymers of vinyl acetate with ethylene and / or vinyl chloride and / or other vinyl esters, such as vinyl laurate, versatic acid vinyl esters, vinyl pivalate and / or esters of valeinic acid / fumaric acid, or homopoiymeπsate of vinyl esters of saturated C ₃ - to C ₈ - alkyl carboxylic acids or their copolymers with ethylene, vinyl chloride and / or other vinyl esters The (meth) acrylate and / or styrene ( Co) polymers are derived from polymers of styrene and / or esters of acrylic acid and / or methacrylic acid (here referred to as (meth) acrylate) with straight-chain, branched or cyclic aliphatic alcohols with 1 to 20 C atoms. Further styrene (Co ) -Polymeπsate can be styrene-butadiene-Copolymeπsate Vinylchloπd-ethylene copolymers are suitable as Vinylchloπd-Poliymeπsate

Vinyl acetate homopolymers, vinyl acetate-ethylene copolymers or copolymers of vinyl esters of saturated C ₃ - to C ₈ -alkyl carboxylic acids and ethylene with an ethylene content of 1 to 40% by weight of ethylene and 0 to 40% by weight of other vinyl esters from the Group of vinyl esters of saturated C ₃ - to C ₈ -alkylcarboxylic acids and / or vinyl chloride, styrene-acrylates such as styrene-butyl acrylate or styrene-ethylhexyacrylate with a styrene content of 1 to 70% by weight. These redispersing polymers are usually prepared by spray drying polymer dispersions Made in spray towers It can be useful to use several bond strength enhancers together

The base polymers can be used in all or in combination with the bond strength enhancers. Cellulose ethers and the starch derivatives mentioned are particularly suitable as the sole binders. The cellulose derivatives and the starch derivatives are suitable for a combination of two binders, to which the redispersible polymers can be added as bond strength enhancers Furthermore, the base polymer can be replaced in whole or in part by polyvinyl alcohol, optionally copolymerized with other ethylenically unsaturated monomers such as vinyl acetate. In addition, water-soluble proteins can also be used as base polymers, such as are obtainable, for example, by the partial hydrolysis of vegetable or animal protein-containing phases. Casein, soy protein and their water-soluble derivatives are particularly suitable. As a rule, however, the above cellulose derivatives are used.

The moldings or wallpaper paste tablets can also be a hydrophilic explosive! included, which is insoluble in water and creates a swelling pressure.

A disintegrant is to be understood as meaning substances or mixtures of substances which ensure the rapid disintegration of the shaped body, in particular the tablet, in an aqueous medium and thus contribute to the rapid and complete action of the active substances. The use of disintegrants made of water-soluble or water-insoluble substances which swell on contact with water and thereby generate a swelling pressure and increase their volume are known in principle. In pharmaceutical technology in particular, such disintegrants are used as disintegration accelerators for tablet-shaped drugs. The disintegration mechanisms of tablets which contain a water-insoluble tablet disintegrant which generates a swelling pressure when water is added are described, for. B. by A.M. Guyot-Hermann in the work "Tablet Disintegration and Disintegrating Agents", S.T.P. Pharma Sciences 2 (6), pages 445 to 462, 1992.

Hydrophilic solids are suitable for the moldings according to the invention. Hydrophilic means that water wets it quickly and completely. The wettability of the disintegrant can expediently be improved by addition, in particular by surface treatment with surfactants, in amounts of 0.1 to 10, preferably 0.5 to 3 g, surfactant per 100 g disintegrant. Nonionic surfactants are preferred over anionic or cationic surfactants.

The disintegrant must generate a strong swelling pressure. Thus, the maximum swelling pressure of the disintegrant should be above the maximum swelling pressure of each individual adhesive component and at least 10 ⁵ Nrrr ² (1 bar), preferably at least 1, 4 • 10 ⁵ Nm ^"2 (1, 4 bar) at a 20% i - Concentration measured according to the measuring method specified in WO 99/03945. It is particularly important that the swelling pressure of the disintegrant is greater than the swelling pressure of the adhesive components within one minute after the addition of water. It should preferably be by a factor of 1. 3 be bigger.

Advantageously, not only the swelling pressure, but also the swelling volume (= amount of water absorbed) should be large, since the volume increase is then also large. The disintegrants should advantageously absorb at least 2 times, in particular 5 times, their weight in water.

The disintegrant is insoluble in water, ie the solubility is less than 1 g, preferably less than 0.01 g, based on 100 ml of water at 20 ° C., measured after 1 minute from the addition of water with stirring, preferably also after a long period of time until saturation. Solubility is usually determined gravimetrically as the residue of the solution after the undissolved portion, for. B. was separated by filtering or centrifuging. If the disintegrant is a polymer, the insolubility can also be determined by the viscosity. It may within a minute, preferential increase with saturation by a maximum of 10%, but preferably not at all. An example of polymeric disintegrants are cellulose derivatives. These are reversibly cross-linked Ceululose derivatives, which are insoluble in the cross-linked state but soluble in the non-cross-linked state. The crosslinking is canceled by water with a pH of at least 8.

A fibrous inner and / or outer structure of the disintegrant is advantageous for a rapid action. "Fibrous" should be understood to mean a shape in which one dimension is at least twice as large as the two other dimensions, which are roughly the same size. As a rule, fibers with a length of 0.03 to 1.5, preferably from 0.1 to 1.0, mm are present. The fibers preferably consist of cellulose and its derivatives. However, other easily wettable materials are also possible, e.g. B. glass. But non-fibrous forms can also be used.

The disintegrant is above all a natural or partially synthetic polysaccharide and its derivatives, in particular based on cellulose. But starch is also a good basis. However, fully synthetic disintegrants based on crosslinked polyvinylpyrrolidones (PVP) can also be used. Short cut fibers or microcrystalline polymers are particularly preferred. Possible collagens, amyloses, polyamides and especially cellulose, e.g. B. in the form of softwood flour.

In principle, you can choose from a variety of known explosives. Examples of the celluloses and modified celluloses are Avicell® PH 101, 102 or 200 from FMC, Arbocel® Bww 40, from Rettenmaier, EIcema®, from Degussa or Lattice® NT 200. Examples of starch products are the highly cross-linked hydroxypropyl starch Prejel® VA 70-S-AGGL, from Schölten and the sodium carboxymethyl starches CMS UAP 500 and Primojel®. The cross-linked sodium carboxymethyl cellulose Ac-Di-Sol® from FMC and the cross-linked polyvinylpyrrolidone derivatives Kollidon® CL from BASF and Polyplasdone XL from GAF are also suitable.

The disintegrant is preferably compacted. This is understood to mean compressing (compressing) starting materials into larger units, with or without a binder. The explosive starting materials should preferably be present in a mixture of different dimensions. Mixtures of cellulose and their derivatives with a fiber length of approx. 30 to 150 μm on the one hand and z. B. 500 to 1500 microns on the other hand. The surfactants and other additives such as. B. polyols such as sorbitol and water-soluble polymers such as polyvinyl alcohol and polyvinyl pyrrolidone are advantageously added before compacting. The disintegrant compactate has a bulk density of 200 to 700, in particular 350 to 450 g / l and a grain size of preferably 0.1 to 3, in particular 0.2 to 2 mm.

The moldings or wallpaper paste tablets may also have other ingredients customary for such binder systems in order to give the binders certain properties according to the intended use, for. B. preservatives, wetting agents, release agents, pigments, stabilizers, etc. A filler important in terms of quantity are the fillers. These are substances that are mainly added to increase the volume or weight. In addition, they can also improve technical usability, e.g. B. reduce stickiness when it matters in the specific case. Common fillers are carbonates (e.g. calcium carbonate), silicates (e.g. Talc, clay, mica), silica, sulfates (calcium and barium), aluminum hydroxide and glass fibers and spheres. Such fillers can be present in the molding in an amount of 0 to 30, preferably 1 to 10,% by weight, based on the sum of the substances for producing an aqueous binder system and the disintegrant. However, the fillers can also be mixed with the shaped body.

If you want to have a foamy binder system, then the gas-generating system should not be contained in the binder, but in a mixture with these.

The substances mentioned above for the production of an aqueous binder system are generally solid and should be processed as powders or agglomerates to give the moldings. The grain size of the starting materials should be at least 0.01 mm and expediently in the range from 0.2 to 3 mm, in particular in the range from 0.5 to 1.5 mm.

The moldings according to the invention can be produced according to the invention by the action of pressure or temperature on powdery or granular layers or mixtures of the different phases. Coarse-grained powders or agglomerates are preferably used. The preparation can be carried out, for example, as described in Ullmann's Encyclopedia of Industrial Chemistry, 5th edition, volume B2, pages 7-1 to 7-37.

When making pieces into pieces by pressing (briquetting), the fine-grained mixture is mechanically compressed (compacted) with or without the addition of a binder. Briquetting binders are advantageously used for the moldings according to the invention, which binders reduce the pressure to be applied due to their plasticizing effect. The type and amount of the briquetting binder depends primarily on the grain size of the powder. Suitable agents are e.g. B. solid polyethylene glycols in an amount of up to 10 wt .-%, preferably up to 5 wt .-%, based on the mixture to be compressed. Of the press systems to be used, the roller press in addition to the stamp press with a closed or open shape and the ring roller press are of particular importance. The moldings are preferably produced by water-free roller compaction of the powdery original product, two powder layers being formed beforehand.

The shaped bodies according to the invention quickly give a lump-free aqueous solution or dispersion with water. This is preferably a paste, that is to say an adhesive in the form of an aqueous swelling product which, even at a relatively low solids concentration, forms a highly viscous, non-stringy mass. These pastes are particularly suitable for gluing wallpapers and other wall coverings. However, other aqueous adhesives can also be produced in this way. With the appropriate composition, the moldings are also suitable for the production of lump-free primers for mineral substrates such as plaster, screed or concrete from walls, ceilings and floors. The surface solidified in this way is then usually coated, for. B. with paint, with a filler or with an adhesive. The aqueous adhesives for in particular textile or ceramic coverings of floors, walls and ceilings can also be produced easily with the shaped bodies according to the invention without lumps.

The procedure for producing the paste is appropriately as follows: a) The moldings are added to the water provided with stirring. b) If necessary, stirring is continued until the moldings have dissolved.

In this way a lump-free paste is obtained. that is, the paste does not contain any dry components of the molded body.

Compared to a paste that was produced directly from the powder-like substances, the paste produced according to the invention shows practically no change in properties that are important for use, such as: viscosity, wet adhesive strength and dry adhesive strength.

The further advantages of the invention are: no dusting when the paste is applied and no separation of the paste components in the package, and easy differentiation from other paste by visual (color) display of certain ingredients.

The invention is illustrated by the examples below.

Examples

In the following, MC 5000 means methyl cellulose with an average molecular weight of 5000, PVAc polyvinyl acetate.

In Example 1, a shaped body according to the invention with the dye-bleach system is described, in Example 2 a shaped body according to the invention with the dye-pH-changing substance system. Example 1 :

A two-phase paste tablet, diameter 40 mm, phase ratio 1: 1, of the following formulation was produced:

With a pressing force of 30 kN with a hydraulic laboratory press, the tablet hardness was 70 N. The disintegration time in cold tap water was 45 seconds. At and shortly after the disintegration, the paste (batch ratio 1:20) was, as expected, slightly colored blue. At the concentrations used, the coloring disappears according to the invention within 3 minutes after the tablet has disintegrated.

Example 2:

A two-phase paste tablet, 40 mm in diameter, was produced using the following recipe:

The physical data in the table are comparable to that from Example 1. The blue color disappears immediately when the paste is applied (ratio 1:20), since a slightly alkaline pH value is established, at which the dye is colorless.

Claims

claims

1. Shaped body made of substances for the production of an aqueous binder system, characterized in that the shaped body is constructed from at least two different phases, at least one of which contains a dye, and which are arranged in the shaped body in such a way that they can be optically distinguished on the surface of the shaped body are.

2. Shaped body according to claim 1, characterized in that it contains 30 to 100% by weight of water-soluble or water-dispersible, non-tacky inorganic or organic, natural or semisynthetic polymers in the dry state at room temperature and 0 to 70% by weight. contains fully synthetic polymers.

3. Shaped body according to claim 1 or 2, characterized in that the dye is decolorized during or after the preparation of the aqueous binder system.

4. Shaped body according to one of claims 1 to 3, characterized in that it is a paste for wall coverings in the aqueous binder system.

5. Shaped body according to one of claims 1 to 4, characterized in that the shaped body is constructed from two different phases, the phases forming two or more layers or one phase granular with an average particle diameter of 0.5 to 10 mm in the other Phase is distributed, or one phase concentrically surrounds a cylindrical core of the other phase.

6. Shaped body according to one of claims 1 to 5, characterized in that the dye or is photochemically decolorized by interaction with a further component which is contained in a phase not containing dye, or by interaction with an aqueous medium.

7. Shaped body according to claim 6, characterized in that the decolorization of the dye is carried out by oxidation, reduction, change in pH or by hydrolysis.

8. Shaped body according to one of claims 1 to 7, characterized in that the adhesive force or the viscosity-modifying substances are contained in at least one of the phases.

9. Shaped body according to one of claims 1 to 8, characterized in that the shaped body contains a hydrophilic disintegrant which is insoluble in water and generates a swelling pressure.

10. A process for the production of moldings according to one of claims 1 to 9 by the action of pressure and / or temperature on a stratification or mixture of the different phases.

11. Use of moldings according to one of claims 1 to 9 for the production of a paste for wall coverings.