Binder composition for low-dust bulk material mixtures

Abstract

A low-dust binder composition, comprising: - Redispersible polymer powders for the formation of a stable film after the addition of water, - Cement to increase strength, - Defoamers, starch, urea and anhydrous liquids to optimize material properties - Quartz sand or crushed sand as carrier material, as well as the additives and admixtures specified under points 5 to 6.3

Description

1. Title of the invention:

[0001] Binder composition for low-dust bulk material mixtures 2. Technical field:

[0002] The present invention relates to the development of binders for the treatment of bulk materials, particularly those that are prone to dust or are contaminated. The focus is on reducing dust emissions during the storage, transport, and processing of bulk materials, as well as on creating stable, storable mixtures. This technology finds applications in the construction industry, environmental protection, and the recycling of building materials. 3. State of the art:

[0003] Bulk materials play a central role in modern industry, particularly in sectors such as construction, mining, agriculture, and the chemical industry. Bulk materials are materials handled in loose, granular, or powdery form, such as various types of soil, sand, gravel, cement, lime, or chemicals. These materials are frequently transported, stored, and processed. A significant problem in handling bulk materials is dust generation. 3.1 Dust problems with bulk materials

[0004] Dust is defined as very fine solid particles generated by the mechanical processing of solid materials, such as crushing, grinding, abrasion, relocation, or transport. Dust generation presents a challenge for several reasons: 3.1.1 Health hazards

[0005] Dust particles can be inhaled and lead to health problems, especially in the respiratory tract. Fine dust can penetrate deep into the alveoli of the lungs and cause diseases such as pneumoconiosis (dust lung) or other chronic respiratory illnesses. In the construction and mining industries, quartz-containing dusts are particularly dangerous, as they can lead to silicosis, a dust-related lung disease. 3.1.2 Security risks

[0006] In industrial environments, dust can be explosive if present in sufficient concentrations and an ignition source is available. Dust explosions can cause significant damage, which is why dust prevention is of paramount importance. 3.1.3 Environmental impact

[0007] Dust emissions can pollute the environment, especially near construction or industrial sites. Fine dust can enter the atmosphere and spread over long distances, leading to air pollution and soil contamination. 3.1.4 Production and process disruptions

[0008] Dust can settle on machines and equipment, potentially leading to malfunctions or increased maintenance. Furthermore, dust generation during the processing of bulk materials can result in undesirable raw material losses. 3.2 Previous approaches to solutions

[0009] Conventional methods for dust reduction in bulk materials include: 3.2.1 Wet mixing process

[0010] In this process, bulk materials are mixed with water to bind the dust. This method is effective, but only temporarily, as the dust reduction only lasts as long as the material remains damp. After drying, dust formation resumes. 3.2.2 Use of binders

[0011] Various binders, such as cement, lime, polymer dispersions, synthetic resins, or bituminous binders, are used to bind the particles together and reduce dust. However, these binders often lead to an immediate hardening, which makes further processing or storage of the material difficult. 3.2.3 Dust extraction and filtration

[0012] Industrial plants often use filter systems and dust extraction systems to reduce the dust concentration in the air. However, these systems are expensive and require regular maintenance. 3.2.4 Chemical sprays and additives

[0013] Various chemical agents can be applied to bulk materials to bind dust. However, these additives can have undesirable side effects, such as impairing material properties or causing environmental problems due to chemical residues. 4. Object of the invention

[0014] The present invention aims to overcome the aforementioned disadvantages and to offer an innovative solution for permanent dust reduction, especially in the case of fine-grained, highly dusty bulk materials.

[0015] The task is to develop a binder composition that makes it possible to process bulk materials in a dry state in order to produce a low-dust mixture without an immediate development of strength.

[0016] It is important that the mixture remains storable and that long-term dust reduction is ensured.

[0017] The activation of the bond at any given time should be possible through a resource that is practically available everywhere and at any time, in this case through the addition of water. 5. Solution approach

[0018] The invention's approach involves developing a special binder composition containing several chemical components. These components are selected and combined in such a way that they do not exhibit any strength development when used dry, yet still enable effective dust reduction. The binding forces are only activated upon the addition of water, resulting in a permanent and stable bond between the bulk material particles.

[0019] The binder composition gives the bulk materials to be bound a firmer bond than these materials would achieve under the same circumstances without the composition. 5.1 Chemical composition

[0020] The binder composition according to the invention consists of a combination of the following main components: Redispersible polymer powders (RDP) of type 5.1.1 Polyvinyl acetate (PVAc)-based redispersible powders: - Molecular formula: (C4H6O2) n Polyvinyl acetate is a polymer of vinyl acetate monomers. It is commonly used in tile adhesives and plasters. 5.1.2 Ethylene vinyl acetate (EVA)-based redispersible powders: - Molecular formula: (C4H6O2) x (C2H4) y EVA is a copolymer of ethylene (C2H4) and vinyl acetate (C4H6O2). It is used in cement mortars and other construction applications. 5.1.3 Styrene-acrylate (SA)-based redispersible powders: - Sum formula: (C8H8) x (C4H 13 O2) y Styrene acrylate is based on a copolymer of styrene (C8H8) and acrylic acid esters (mostly C4H6O2). These powders are frequently used in weather-resistant coatings. 5.1.4 Acrylate-based redispersible powders: - Molecular formula: (C4H6O2) n These powders consist of polyacrylates, which are polymers of acrylic acid esters (C4H6O2). They are used in fillers and sealants. 5.1.5 Vinyl acetate-vinylethylene carbonate (VAE)-based redispersible powders: - Molecular formula: (C4H6O2) x (C3H4O3) y (C2H4) z - VAE is a copolymer of vinyl acetate (C4H6O2), vinyl alcohol or vinylethylene carbonate (C3H4O3), and ethylene (C2H4). These powders offer a good balance between flexibility and strength. 5.1.6 Styrene-butadiene (SB)-based redispersible powders: - Sum formula: (C8H 13 ) x (C4H6) y - SB powders are copolymers of styrene (C8H8) and butadiene (C4H6). They are used in mortars and concrete mixes. 5.1.7 Polyvinyl alcohol (PVOH)-based redispersible powders: - Molecular formula: (C2H4O) n Polyvinyl alcohol (PVOH) is produced by the hydrolysis of polyvinyl acetate. PVOH-based powders are used in applications such as coatings, adhesives, and cement mortars due to their good adhesion and film-forming properties.

[0021] Function: Without being bound to any theory, the proportion of redispersible polymer powders in combination with other components of the binder composition after the addition of water causes the final stability, strength and water resistance of the binder film and the bulk material binding. 5.2 Defoamer

[0022] Powdered defoamers are used in the chemical industry to control foaming in various processes. Here is a list of common powdered defoamers along with their chemical formulas: 5.2.1 Polydimethylsiloxane (PDMS)-based defoamers - Sum formula: (C2H6OSi) n Polydimethylsiloxane is a silicone polymer frequently used as a defoamer. It has excellent defoaming properties and is particularly effective in aqueous systems. 5.2.2 Silicone-based defoamers - Sum formula: [SiO2] n , often combined with PDMS Silicone defoamers often consist of silicone di- or trioxide particles (SiO2) combined with hydrophobically modified polydimethylsiloxane. This combination is used in powder form to improve foam control. 5.2.3 Fatty acid amide-based defoamers: - Sum formula: C 17 H 35 CONH2 (for example, stearamid) Fatty acid amides such as stearamide are used as defoamers, especially in paints, varnishes and other coatings. They reduce surface tension and prevent foaming. 5.2.4 Wax-based defoamers - Sum formula: C 60 H 102 O5 (for example, for montan wax) Waxes such as montan wax, which is a mixture of various long-chain fatty acids and esters, are used as defoamers in powdered form. They are particularly effective in oily systems and at high temperatures. 5.2.5 Polyethylene oxide (PEO)-based defoamers - Molecular formula: (C2H4O) n Polyethylene oxide is a polymer used in the defoaming of aqueous systems. It works by breaking up foam bubbles and reducing surface tension. 5.2.6 Alkyl polyglycoside (APG)-based defoamers: - Sum formula: C 16 H 32 O6 (for example, for dodecyl glucoside) - Alkyl polyglycosides are non-ionic surfactants that also have defoaming properties. They consist of sugars and fatty acids and are biodegradable. 5.2.7 Carboxymethylcellulose (CMC)-based defoamers - Sum formula: C8H 16 NaO8 CMC is a water-soluble polymer used in the defoaming of aqueous systems. It reduces foam stability by adjusting viscosity.

[0023] These powdered defoamers are widely used in the chemical industry, particularly in areas such as paints, varnishes, cleaning agents, papermaking and other processes where foaming is undesirable.

[0024] Function: Foam leads to the inclusion of air bubbles in the binder film, which can negatively affect its strength, stability, and water resistance. Without being bound to any specific theory, the defoamer component of the binder composition, in combination with other components, increases the final stability, strength, and water resistance of the binder film and the bulk material binding. 5.3 Cement

[0025] Virtually all types of cement are suitable as a component of the binder composition. 5.3.1 Portland cement (CEM I): - Main components: - Tricalcium silicate (Ca3SiO5) - Dicalcium silicate (Ca2SiO4) - tricalcium aluminate (Ca3Al2O6) - Tetracalcium aluminate ferrite (Ca4Al2Fe2O 10 ) - Additives: No or only small amounts of additives 5.3.2 Portland composite cement (CEM II): - Main components: - Same as CEM I (Portland cement) - Additives: - blast furnace slag (Ca2SiO4), fly ash (CaO SiO2 Al2O3), limestone (CaCO3), silicate dust (SiO2) - Chemical formulas for additives: - Blast furnace slag: Ca2SiO4 - Fly ash: varies, often CaO·SiO2·Al2O3 - Limestone: CaCO3 - Silicate dust: SiO2 5.3.3 Blast furnace cement (CEM III): - Main components: - Portland cement clinker (as in CEM I) - Blast furnace slag (Ca2SiO4, CaO·Al2O3·SiO2) - Additives: Blast furnace slag (60-95%) 5.3.4 Pozzolana cement (CEM IV): - Main components: - Portland cement clinker (as in CEM I) - Pozzolanic materials (SiO2, Al2O3) - Additives: Natural pozzolans, lime-rich fly ash, silicate dust 5.3.5 Composite cement (CEM V): - Main components: - Portland cement clinker (as in CEM I) - Blast furnace slag (Ca2SiO4) - Pozzolans or fly ash (SiO2, Al2O3) - Additives: A mixture of blast furnace slag, pozzolans, fly ash 5.3.6 Sulfate-resistant cement: - Main components: - Tricalcium silicate (Ca3SiO5) - Dicalcium silicate (Ca2SiO4) - Additives: Small amount of tricalcium aluminate (Ca3Al2O6) to increase resistance to sulfates. 5.3.7 White cement: - Main components: - Tricalcium silicate (Ca3SiO5) - Dicalcium silicate (Ca2SiO4) - Additives: Reduced iron content to maintain the white color.

[0026] The specific chemical formulas describe the main components, but cement also contains a variety of other compounds that occur in smaller quantities and contribute to the performance and properties of the final product. - Function: Without being bound to any theory, the cement content, in conjunction with other components of the binder composition, supports the crosslinking of the polymer components after the addition of water and increases the final stability, strength and water resistance of the binder film and the bulk material binding. 5.4 Water glass (powdered) 5.4.1 Sodium water glass (sodium silicate): - Chemical formula: Na2SiO3 - Description: Sodium silicate is produced by the reaction of sodium carbonate (soda ash) with quartz sand at high temperatures. It is widely used as a binder, adhesive, and in the construction industry. 5.4.2 Potassium water glass (potassium silicate): - Sum formula: K2SiO3 - Description: Potassium silicate is produced by the reaction of potassium carbonate with quartz sand. It is often used in heat-resistant paints and coatings, as well as in the manufacture of refractory materials. 5.4.3 Lithium water glass (lithium silicate): - Chemical formula: Li2SiO3 - Description: Lithium silicate is used in special applications, such as as a binder in concrete and as an additive to improve the chemical resistance and durability of coatings. 5.4.4 Alkali metal silicate (general): - Molecular formula: M2O·nSiO2 (where M = Na, K, Li and n is a variable that describes the ratio of silicon dioxide to alkali metal oxide) - Description: The general formula describes various water glasses, where M represents an alkali metal (sodium, potassium, or lithium). The ratio of silicon dioxide (SiO2) to alkali metal oxide (M2O) varies depending on the specific composition and application.

[0027] Powdered water glass is used in many industrial applications, including construction chemicals, as a binder for refractory materials, in adhesives, as a protective coating against corrosion, and in papermaking. The molecular formulas represent the basic chemical composition of these compounds. - Function: The water glass content, in conjunction with other components of the binder composition, supports the crosslinking of the polymer components after the addition of water and increases the final stability, strength and water resistance of the binder film and the bulk material binding, without being bound to any theory. 5.5 Anhydrous liquids - Products: Vegetable oils, synthetic oils or mineral oils with suitable viscosity

[0028] 5.5.1 Vegetable oils are only suitable to a limited extent as a component of the binder composition, as the chemical composition often changes over time due to fatty acid oxidation.

[0029] 5.5.2 Synthetic oils offer very good resistance to aging and oxidation and are available in many viscosities. - Function: Without being bound to any theory, suitable anhydrous liquids reduce dust in the otherwise dry components of the binder composition and the bulk materials to be mixed with it, contribute to the stability of the dry mixture and prevent the particles from clumping together during storage.

[0030] Oils with a low viscosity across a wide temperature range are used for dust suppression by being applied to the surface of bulk materials. This can be done by spraying the oil onto the bulk material or by mixing it into the bulk material.

[0031] The oil films that form on the particles prevent the fine dust particles from becoming airborne. This significantly reduces dust generation and contributes to improved air quality. The oil's low viscosity ensures that it can be easily spread on the particles without excessively thinning the mixture or negatively affecting the bulk material's properties.

[0032] Reducing dust contributes to improved workplace safety, as dust particles can pose health risks to workers, especially when inhaled. Binding the dust particles minimizes, without relying on any specific theory, the risk of respiratory illnesses and other health-related problems. 5.6 Strength - Product: Amylose and amylopectin (C6H) 10 O5) n

[0033] Starch is a polysaccharide composed of glucose units. These glucose units are linked together by glycosidic bonds. Depending on how the glucose units are arranged, either amylose or amylopectin is formed. 5.6.1 Amylose: Consists mainly of linear chains of α-1,4-glycosidically linked glucose units. 5.6.2 Amylopectin: Has a branched structure with α-1,4-glycosidic bonds in the main chains and α-1,6-glycosidic branches.

[0034] The value of n can vary greatly and is typically in the range of several hundred to thousands, depending on the source and the type of strength.

[0035] Modified starch is produced by chemically, physically, or enzymatically treating native starch to alter or improve its properties. These modifications can involve the introduction of additional functional groups, such as acetyl, hydroxypropyl, or phosphate groups. While these modifications slightly alter the chemical structure, the basic structure of the glucose units remains intact.

[0036] 5.6.3 Acetylated starch: In this process, some hydroxyl groups (-OH) of the glucose units are replaced by acetyl groups (-COCH3). This leads to altered properties such as increased water solubility or altered gelling behavior. - Function: Acts as a thickening agent and, without being bound to any theory, ensures a uniform distribution of the binder components as well as improved coalescence in film formation after the addition of water. 5.7 Urea - Product: The molecular formula CH4N2O remains the same for all variants, but purity and intended use can vary greatly.

[0037] Here we distinguish between technical, fertilizer, and pharmaceutical urea. - Function: Slows down the reaction of the cement and allows for a controlled setting time, which facilitates the processing of the material and, without being bound to any theory, ensures improved coalescence in film formation after the addition of water. 5.8 Carrier material

[0038] If a carrier material is required to ensure uniform mixing with the intended bulk material, dry sand or another easily mixable bulk material can be used, for example. This method allows the production of concentrates or so-called premix products, which can then be combined with the main quantity of the bulk material to be mixed in a defined ratio. This eliminates the need to store and precisely dose all individual components separately.

[0039] Function: The bulk material used, independent of theoretical models, serves as a supporting framework and distribution medium for the other binder components. It ensures a uniform distribution of the components throughout the entire mixture and thus contributes to a homogeneous end product. 6. Mode of action of the composition

[0040] The composition according to the invention unfolds its effect on two levels: 6.1 Dust reduction Even during the dry mixing of the bulk materials with the binder, dust formation is significantly reduced. This is achieved through the uniform distribution of the polymer powders and anhydrous liquids, which ensure effective wetting of the bulk material particle surfaces. This surface wetting helps the particles adhere to one another, thus greatly reducing the formation of dust particles during the mixing process. 6.2 Long-term storage and activation The mixture remains stable in its dry state and can be stored dust-free for extended periods. The crucial binding strength and durability of the final product are only activated by the subsequent addition of water, giving the user a high degree of flexibility in process design. This property allows the mixture to be stored at any time and place and activated only when needed, thus ensuring optimal adaptation to specific production processes. 6.3 Supplementary components The binder composition according to the invention can be further modified and adapted to the requirements by using additional ingredients. In particular, these are substances that influence the technical properties, such as... Wetting and dispersing agents, Water repellent Thickening agent, Plasticizer, Surfactants Pigments, also in the form of pastes or liquids, pH regulators, Herbicides and fungicides, Calcium hydroxide microcrystalline silicon dioxide

[0041] Function: Without being bound to any theory, individual substances or combinations thereof listed above can further optimize processability, stability and water resistance. 7 advantages of the invention

[0042] The binder composition according to the invention offers several significant advantages: 7.1 Reduction of health and safety risks: Minimizing dust generation during the handling and storage of bulk materials significantly reduces health risks for workers. At the same time, the risk of dust explosions in industrial plants decreases. 7.2 Environmental friendliness: The binder composition contains no harmful chemicals that could be released into the environment. This makes it an environmentally friendly alternative to conventional dust suppressants. 7.3 Storage and transport capability: The ability to store and transport the bulk material in a dry state without dust generation offers logistical advantages and reduces the need for special protective measures during transport. 7.4 Flexibility in application: The binding of the bulk material particles can be activated at any time by adding water, allowing for flexible handling of the material. This is particularly advantageous in construction, where schedules often vary. 7.5 Improved material properties: Without being bound to any theory, the final product exhibits high water resistance and mechanical stability after activation, making it ideal for applications in construction and the recycling of building materials. 7.6 The binder composition, with an adjusted cement content of less than 5%, preferably less than 3% of the total quantity, without being bound to any theory, enables the formation of a stable, water-resistant but flexible binder film for applications where particularly high strengths and rigid binder films are unsuitable. 7.7 According to COMMISSION REGULATION (EU) 2023 / 2055 of 25 September 2023 amending Annex XVII to Regulation (EC) No 1907 / 2006 of the European Parliament and of the Council concerning the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) as regards synthetic polymer microparticles, polymers whose solubility exceeds 2 g / litre of water are not subject to the restriction of the Directive.

[0043] The redispersible polymer powders contained in the binder composition according to the invention exhibit a significantly higher solubility in water than specified in the regulation. 8 Detailed description

[0044] The binding composition according to the invention and the mixtures of binder and bulk material produced therewith enable the production of low-dust products for soil stabilization, the binding of loose sand or coarser aggregates, and the production of building materials that can be processed with low dust and whose strength development is activated by the addition or spraying with water. 8.1 The redispersion and film formation of polymer powders in binder compositions for bulk materials involves complex chemical processes. A detailed description of these processes is provided below: 8.1.1 Wetting and swelling When water is added, the process begins with the wetting of the polymer particles. The hydrophilic protective colloids surrounding the polymer particles absorb water and swell. This leads to an increase in particle volume and surface energy. 8.1.2. Dissolution of the protective colloids The swollen protective colloids, often polyvinyl alcohol (PVOH) with the molecular formula (C2H4O)n, gradually dissolve. This process releases the encapsulated polymer particles and allows them to disperse in water. 8.1.3. Deagglomeration The polymer particles, which were previously in agglomerates, begin to separate. This occurs through the combination of mechanical energy (e.g., stirring) and the electrostatic repulsion between the now charged particles. 8.1.4. Stabilization of the dispersion The dissolved protective colloids and other additives in the composition form a stabilizing layer around the dispersed polymer particles. This prevents premature coagulation and keeps the particles in suspension. 8.2 Film formation 8.2.1. Evaporation of the dispersion medium

[0045] As the water evaporates, the dispersed polymer particles move closer together. The concentration of particles in the remaining liquid steadily increases. 8.2.2. Capillary pressure and deformation

[0046] With further water evaporation, water menisci form between the particles, generating capillary pressure. This pressure, described by the Young-Laplace equation (ΔP = 2γ / r, where γ is the surface tension and r is the radius of curvature), leads to the deformation of the polymer particles. 8.2.3. Interdiffusion of the polymer chains Upon reaching the minimum film formation temperature (MFT), the polymer particles become sufficiently soft to fuse. The polymer chains at the particle interfaces begin to interdiffusion. This process can be described by reptation theory, where the diffusion time t is proportional to the cube of the molecular mass M of the polymer (t ∝ M). 3 ). 8.2.4. Coalescence and Networking

[0047] The polymer particles fuse completely and form a continuous film. In copolymers such as ethylene vinyl acetate (EVA) with the molecular formula (C4H6O2)×(C2H4)y, additional crosslinking reactions can occur, which increase the mechanical stability of the film. 8.3. Interaction with cement particles

[0048] 8.3.1 In the presence of cement particles, such as tricalcium silicate (Ca3SiO5) from Portland cement, interactions occur between the polymer films and the hydrating cement phases. This leads to the formation of an interpenetrating network structure, which further improves the bonding properties.

[0049] 8.3.2 Without being bound to any theory, the interaction of polymers with mineral oil components in the binder can lead to better crosslinking and improved properties of the binder. Here are some possible interactions and their effects: 8.4 Compatibilization and Dispersion 8.4.1. Improvement of miscibility Certain polymers, especially those with amphiphilic properties, can act as compatibilizers between the hydrophilic components of the binder and the hydrophobic mineral oil components. This leads to better dispersion and a more homogeneous distribution of the oil components within the binder. 8.4.2. Emulsion formation Polymers with emulsifying properties can contribute to the formation of stable oil-in-water emulsions, which facilitates the incorporation of the mineral oil components into the binder matrix. 8.5 Networking and Structure Formation 8.5.1. Interpenetrating Networks Some polymers can form interpenetrating networks (IPNs) with the mineral oil components. In this process, the polymer chains and the oil molecules interpenetrate each other, leading to improved mechanical stability. 8.5.2. Physical networking Through van der Waals forces and hydrophobic interactions between the polymer chains and the oil molecules, a physical cross-linking can occur, which increases the cohesion of the binder. 8.6 Modification of Interfacial Properties 8.6.1. Improvement of Adhesion

[0050] The presence of mineral oil components can modify the interfacial properties between the binder and the particles to be bound. Polymers can act as mediators in this process and improve adhesion. 8.6.2. Reduction of surface tension

[0051] The combination of polymers and mineral oil components can reduce the surface tension of the binder, leading to better wetting of the particles to be bound. 8.7 Rheological Modification 8.7.1. Viscosity Adjustment

[0052] The interaction between polymers and mineral oil components can influence the viscosity of the binder. This can lead to improved processability and application. 8.7.2. Thixotropy

[0053] Some polymer-oil combinations can impart thixotropic properties, which improves the stability of the binder during storage while ensuring good processability during application. 8.8 Chemical Reactions 8.8.1. Crosslinking Reactions

[0054] In reactive polymer systems, the mineral oil components can act as plasticizers or reaction mediators and thus influence the crosslinking reactions. 8.8.2. Oxidative Crosslinking

[0055] In the presence of oxygen, unsaturated components of mineral oils can undergo oxidative crosslinking reactions with certain polymers, leading to additional solidification of the binder.

[0056] These interactions, without being bound to any specific theory, can lead to a binder exhibiting improved cohesion, adhesion, and long-term stability. The precise effects depend on the specific chemical composition of the polymers and mineral oils used, as well as the environmental conditions. Careful selection and optimization of the components are necessary to achieve the desired properties. 8.9 Post-networking

[0057] In some cases, particularly with functionalized polymers, post-crosslinking reactions can occur. These can be triggered by humidity, temperature, or specific functional groups in the polymer and lead to a further increase in film strength.

[0058] These complex chemical processes result in the formation of a stable, water-resistant binder film that effectively binds the bulk material particles and ensures long-lasting dust reduction. The precise kinetics and thermodynamics of these processes depend on the specific composition of the polymers used and the environmental conditions.

[0059] Hydrogen bonds (also called hydrogen bridges) play a crucial role in the redispersion of polymer powders, especially in the initial phase of the process. Their importance can be described as follows: 8.10 Initial Hydration

[0060] Initial hydration describes the beginning of the hydration process, in which water molecules attach themselves to ions or polar compounds. This process is particularly important for understanding solution processes and chemical reactions in aqueous systems. Initial hydration process 8.10.1 Dissociation

[0061] First, the ions of a salt or the polar molecules in water dissociate. 8.10.2 First attachment

[0062] Water molecules attach themselves to dissolved particles due to ion-dipole interactions. 8.10.3 Formation of the primary hydration shell

[0063] The water molecules arranged directly around the ion form the first sphere, also known as the primary hydration shell. 8.10.4 Alignment of water molecules - In the case of cations: The oxygen atoms of the water molecules align themselves towards the positively charged ion. - In the case of anions: The hydrogen atoms of the water molecules orient themselves towards the negatively charged ion. 8.10.5 Factors influencing initial hydration

[0064] The strength and extent of initial hydration depend on various factors: Ion size: Smaller ions are generally more hydrated than larger ones. Charge: Ions with a higher charge attract more water molecules. Temperature: Higher temperatures accelerate the hydration process. 8.10.6 Importance of initial hydration

[0065] Initial hydration is of great importance for various processes and applications: Solubility of salts: Hydration energy significantly influences whether and how well a salt dissolves in water. Biochemical processes: Hydration plays an important role in protein folding and the stabilization of biomolecules. Construction chemistry: In cement hydration, initial hydration is the first step in the setting and hardening of concrete. Initial hydration lays the foundation for further reactions and processes in aqueous systems and is therefore a fundamental process in chemistry and related sciences. 8.11.1 Interaction with protective colloids:

[0066] The polymer powder particles are often surrounded by hydrophilic protective colloids such as polyvinyl alcohol (PVOH). PVOH, with the molecular formula (C2H4O)n, possesses numerous OH groups that can act as hydrogen bond donors and acceptors [1]. 8.11.2 Water absorption:

[0067] Upon contact with water, hydrogen bonds form between the OH groups of PVOH and the H2O molecules. This leads to the initial water uptake and swelling of the protective colloids [1]. 8.12 Swelling and Dissolution 8.12.1 Breaking of Internal Bonds

[0068] Hydrogen bonds play an important role in breaking the internal bonds within polymer particles. Water competes with the existing hydrogen bonds between the polymer chains and partially replaces them [1]. 8.12.2 Promoting swelling

[0069] The formation of hydrogen bonds between water and the hydrophilic groups of the polymers promotes the swelling of the particles. This increases the surface area and facilitates further water uptake [1]. 8.13 Stabilization of the dispersion 8.13.1 Hydration shell

[0070] Hydrogen bonds contribute to the formation of a hydration shell around the dispersed polymer particles. This shell stabilizes the particles in the aqueous dispersion and prevents their premature agglomeration [1]. 8.13.2. Interaction with additives

[0071] Other components of the binder composition, such as certain defoamers (e.g., carboxymethylcellulose, CMC), can also form hydrogen bonds with water and the polymer particles. This contributes to the overall stability of the dispersion. 8.14 Film Formation 8.14.1 Interdiffusion of Polymer Chains

[0072] During film formation, as the water evaporates, hydrogen bonds play a role in the interdiffusion of the polymer chains. They can form temporary bonds between adjacent chains and thus contribute to the cohesion of the forming film [1]. 8.14.2. Interaction with cement particles

[0073] In the presence of cement particles, hydrogen bonds can also contribute to the interaction between the polymer films and the hydrating cement phases. This promotes the formation of an interpenetrating network structure.

[0074] In summary, hydrogen bonds play a central role throughout the entire redispersion process of polymer powders. They are crucial for initial water uptake, particle swelling, dispersion stabilization, and contribute to film formation and interaction with other components of the binder composition. Their presence and dynamics significantly influence the efficiency and quality of the resulting binder film. 9 Applications 9.1 Application in road construction

[0075] In road construction, recycled building materials are frequently used, which, due to their crushing and the mixing in of, for example, cement as a binder, tend to form dusty mixtures.

[0076] The addition of the binder composition according to the invention significantly reduces dust formation during processing. After the addition of water, the material is compacted to form a stable, waterproof road surface that meets the requirements for mechanical strength and weather resistance. 9.2 Recycling of building materials

[0077] The recycling of construction waste and other building materials often generates fine particles that create dust during handling. The binder composition according to the invention binds the dust and enables dust-free processing and storage of the material. This leads to an improved working environment and reduces the burden on equipment from dust deposits. 9.3 Production of low-dust mixtures

[0078] When processing building materials, such as dry mortars, large quantities of dust are released during handling and processing. The binder composition according to the invention enables the development of new material formulations as well as the further development of existing products to facilitate low-dust processing. 10. Drawings and diagrams

[0079] No specific drawings are required to illustrate the invention. 12 examples and use cases: The invention finds application in various fields: 12.1 Recycling of building materials: For the processing of recycled material, which is compacted into a load-bearing, dust-free material. 12.2 Soil stabilization: For binding dry, dusty soils or sands that can be processed later. 12.3 Bulk material transport and storage: For dust-free storage and transport of powdered materials. 12.4 Construction and road building: For the production of building materials that are flexible in their application and can be activated as needed. 13 patent categories:

[0080] The invention covers several patent categories, including a new product and specific manufacturing processes necessary to achieve a processable and environmentally friendly product. Special features such as the improved water resistance, flexibility, and long-term shelf life of the dry binder open up numerous applications in construction and environmental protection.

Claims

[1] A low-dust binder composition comprising: - Redispersible polymer powders for the formation of a stable film after the addition of water, - Cement to increase strength, - Defoamers, starch, urea and anhydrous liquids to optimize material properties - Quartz sand or crushed sand as carrier material, as well as the additives and admixtures specified under points 5 to 6.3 [2] The use of the composition for dust-free storage and processing of bulk materials, whereby dust formation in the dry state is minimized and the binding of the particles can be activated by subsequent addition of water.