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BR-102024018044-A2 - PROCESS FOR OBTAINING ORGANOPHILIC CLAYS, ORGANOPHILIC CLAYS THUS OBTAINED AND THEIR USE IN NANOCOMPOSITES

BR102024018044A2BR 102024018044 A2BR102024018044 A2BR 102024018044A2BR-102024018044-A2

Abstract

A process for obtaining organophilic clays by intercalation is described, comprising intercalating bentonite with quaternary ammonium salt, filtering the bentonite/quaternary ammonium salt intercalated product, drying and grinding the product; co-intercalating the powdered product with a long-chain amine in mass ratios from 1:1 to 1:4 bentonite/quaternary ammonium salt to long-chain amine, obtaining a long-chain intercalated product; drying and recovering the bentonite/quaternary ammonium salt/amine product with improved basal spacings compared to those obtained by prior art processes. In an alternative embodiment, the clay is intercalated with a primary long-chain amine and a long-chain carboxylic acid. In another alternative embodiment, the clay already intercalated with quaternary ammonium salt is intercalated with a primary long-chain amine and a long-chain carboxylic acid. The clays obtained are also described, as well as their use in nanocomposites.

Inventors

  • EDCLEIDE MARIA ARAÚJO
  • DAYANNE DINIZ DE SOUZA
  • Renata Barbosa

Assignees

  • Universidade Federal De Campina Grande - Pb

Dates

Publication Date
20260317
Application Date
20240902

Claims (20)

  1. 1. Process for obtaining organophilic clays, characterized by comprising the following steps: a) intercalating bentonite with quaternary ammonium salt by dispersing the bentonite in distilled water under agitation for 15-25 minutes, letting it rest for 24 hours and infusing with quaternary ammonium salt under vigorous agitation for 15-25 minutes, obtaining an intercalated bentonite/quaternary ammonium salt product; b) filtering the intercalated bentonite/quaternary ammonium salt product obtained in a), heating in an oven at 60°C for 48 hours, grinding and sieving through an ABNT #200 sieve, obtaining a bentonite/quaternary ammonium salt product in powder form; c) co-intercalating the sieved powdered intercalated product resulting from b) with a long-chain primary amine in mass ratios from 1:1 to 1:4 bentonite/quaternary ammonium salt a) convert ammonium to long-chain amine under stirring at 75-85°C for 15-25 minutes, obtaining an intercalated product of bentonite/quaternary ammonium salt/long-chain amine; b) dry the intercalated product of bentonite/quaternary ammonium salt/long-chain amine obtained in c) in a vacuum oven at 75-85°C for 4-6 hours, obtaining the desired product in powder form; c) recover the intercalated product of bentonite/quaternary ammonium salt/long-chain amine powder obtained in d) with improved basal spacings compared to those obtained by prior art processes.
  2. 2. Process according to claim 1, characterized in that the bentonite clays belong to the group of sodium smectite clays with a Cation Exchange Capacity of at least 70 meq/100 g of clay and a purity greater than 85%;
  3. 3. Process according to claim 1, characterized in that the quaternary ammonium salts are selected from stearyltrimethylammonium halide, distearyldimethylammonium halide, dialkyldimethylammonium halide, alkylbenzyldimethylammonium halide, alkyltrimethylammonium halide, cetyltrimethylammonium halide;
  4. 4. Process according to claim 3, characterized in that the quaternary ammonium salt is stearyltrimethylammonium halide;
  5. 5. Process according to claims 3 and 4, characterized in that the halide is chloride;
  6. 6. Process according to claim 1, characterized in that the long-chain primary amine is selected from amines with a carbon number between C8 and C18;
  7. 7. Process according to claim 6, characterized in that the primary amine is octadecylamine;
  8. 8. Process according to claim 1, characterized in that the mass ratio of bentonite/quaternary ammonium salt to long-chain primary amine is 1:1 to 1:2;
  9. 9. Process for obtaining organophilic clay, characterized by comprising the steps of: a) intercalating onto previously dried bentonite clay at 55-65°C for 15-25 minutes (unmodified), a long-chain primary amine and a long-chain carboxylic acid in molar ratios between 1:1:1 and 1:1:4, under vigorous stirring and heating at 75-85°C for 15-25 minutes, obtaining an intercalated product bentonite/long-chain amine/long-chain carboxylic acid; b) drying the intercalated product obtained in a) in a vacuum oven at 75-85°C for 4-6 hours, obtaining a dry powdered bentonite/long-chain amine/long-chain carboxylic acid product; and c) recovering the dry powdered bentonite/long-chain amine/long-chain carboxylic acid intercalated product obtained in b) with improved basal spacings compared to those obtained by prior art processes;
  10. 10. Process according to claim 9, characterized in that the bentonite clays belong to the group of sodium smectite clays with a Cation Exchange Capacity of at least 70 meq/100 g of clay and a purity greater than 85%;
  11. 11. Process according to claim 9, characterized in that the long-chain primary amine is selected from primary amines with a number of carbons between C8 and C18;
  12. 12. Process according to claim 11, characterized in that the primary amine is octadecylamine (ODA);
  13. 13. Process according to claim 9, characterized in that the long-chain carboxylic acids are selected from monocarboxylic acids with a number of carbons between C4 and C31;
  14. 14. Process according to claim 13, characterized in that the carboxylic acid is stearic acid (STA);
  15. 15. Process according to claim 9, characterized in that the molar ratios of bentonite clay to long-chain primary amine and long-chain carboxylic acid concentrations are from 1:1:1 to 1:1:2;
  16. 16. Process for obtaining organophilic clay, characterized by comprising the steps of: a) drying bentonite intercalated with quaternary ammonium salt at 55-65°C for 15-25 minutes, obtained by dispersing the same in distilled water under agitation for 15-25 minutes, resting for 24 hours and infusing with quaternary ammonium salt under vigorous agitation for 15-25 minutes; b) co-intercalating said dry intercalated bentonite in a mixture of a long-chain amine and a long-chain carboxylic acid in molar ratios between 1:1:1 and 1:1:4, under agitation and heating at 75-85°C for 5-15 minutes, obtaining an intercalated product bentonite/quaternary ammonium salt/long-chain amine/long-chain carboxylic acid; c) drying said intercalation product from step a) in a vacuum oven at 75-85°C for 4-6 hours obtaining a dry powdered bentonite/quaternary ammonium salt/long-chain amine/long-chain carboxylic acid intercalated product; and) recover the dry powdered bentonite/quaternary ammonium salt/long-chain amine/long-chain carboxylic acid product from step b) with improved basal spacings compared to those obtained by prior art processes;
  17. 17. Process according to claim 16, characterized in that the bentonite clays belong to the group of sodium smectite clays with a Cation Exchange Capacity of at least 70 meq/100 g of clay and a purity greater than 85%;
  18. 18. Process according to claim 16, characterized in that the long-chain primary amine is selected from primary amines with a number of carbons between C8 and C18;
  19. 19. Process according to claim 18, characterized in that the primary amine is octadecylamine (ODA);
  20. 20. Process according to claim 16, characterized in that the long-chain carboxylic acids are selected from among monocarboxylic acids with a number of carbons between C4 and C31;

Description

FIELD OF THE INVENTION [001] The present invention pertains to the field of processes for preparing organophilic clays for their subsequent use in nanocomposites. More specifically, the organophilization of the clays was based on the intercalation of octadecylamine molecules into unmodified sodium montmorillonite clays already intercalated with quaternary ammonium salts, as well as the co-intercalation of another molecular species. FUNDAMENTALS OF THE INVENTION [002] Clays are natural, earthy, fine-grained materials chemically formed from hydrated silicates of aluminum, iron, and magnesium. They consist of extremely small crystalline particles of a single clay mineral or a mixture of several of them. In addition to these, clays may also contain organic matter, soluble salts, particles of quartz, pyrite, calcite, other residual minerals, and amorphous minerals. [003] Clay minerals have a fibrous or layered (lamellar) network structure. Most fall into the latter category, and are therefore called phyllosilicates. Each layer is composed of one or more sheets of silica tetrahedra and aluminum hydroxide octahedra, and the number of sheets per layer divides clay minerals into two groups: diforms (1:1 layers, i.e., each layer of the clay mineral is composed of one sheet of tetrahedra bonded to one sheet of octahedra) or triprods (2:1 layers, i.e., two sheets of tetrahedra surrounding one sheet of octahedra). [004] Clay minerals can also be divided according to: the degree of occupation in the octahedral sheet (di versus trioctahedral); the possibility of the basal layers expanding through the introduction of polar molecules, increasing the basal distance between planes; and the type of arrangement along the crystallographic axes. According to these divisions, clay minerals can be classified into the following main groups: kaolinites, smectites, vermiculites, hydrated micas, chlorites, and mixed-layer clay minerals. [005] Bentonite clay, composed predominantly of the clay mineral smectite, has the property of increasing its initial volume several times in the presence of moisture, with a fine granulometry containing a minimum of 85.0% of the clay mineral montmorillonite. [006] Therefore, smectite clays that have montmorillonite as the predominant clay mineral, with the unit cell formula 0.67M+ (Al3.33Mg0.67Si8O20(OH)4) for the smectite clay mineral, can be considered bentonites. This formula shows that the unit cell has a negative electrical charge due to isomorphic substitutions of Al3+ by Mg2+. The M+ cation that balances the negative charge is called the exchangeable cation, since it can be reversibly exchanged for other cations, and can be anhydrous or hydrated. The exchangeable cation content, expressed in milliequivalents of the cation per 100g of clay, is called CEC - cation exchange capacity. If the exchangeable cations are Na+ or Li+ or Ca++, the bentonites will be sodium, lithium or calcium bentonites. [007] In clay minerals, the cation exchange capacity varies from 80 to 150 meq/100g in montmorillonite, from 3 to 15 meq/100g in kaolinite, from 5 to 10 meq/100g in halloysite^2H2O, from 10 to 40 meq/100g in halloysite^4H2O, from 10 to 40 meq/100g in illite or chlorite, and from 100 to 150 meq/100g in vermiculite. The organic matter contained in clays can also have a high cation exchange capacity on the order of up to 300 meq/100g; zeolites and vermiculites also have cation exchange capacities of this order (the data in meq are associated with the equivalence of the charges of the exchangeable ions). [008] In montmorillonite, the stacking of plates is governed by relatively weak polar forces and Van der Waals forces, and between these plates there are gaps called galleries or intermediate layers in which exchangeable cations such as Na+, Ca2+, Li+ reside, electrostatically fixed. The layers of the clay mineral montmorillonite are continuous and their stacking can be random or with some order. Its successive layers are loosely connected to each other, and layers of water can penetrate between them, separating them and leaving them free, when the interplanar distance reaches values greater than 40.0 Å. [009] When individual sheets of montmorillonite are exposed to water, water molecules are adsorbed onto the surface of the silica layers, which are then separated from each other. This behavior is called interlamellar swelling and is controlled by the cation associated with the clay structure. [0010] Obtaining inorganic-organic hybrid materials becomes possible through modifications such as heat treatment, pillaring, acid activation, and adsorption and intercalation of inorganic and organic species; these species can be small, in the case of metal adsorption, or large species such as polymers. This last method, intercalation, is one of the most explored modification processes. The term "intercalation" is used in Chemistry to describe the reversible insertion or introduction of a mobile "guest" (atoms, molecules