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CN-122003489-A - Preparation of sp2Method for stabilizing homogeneous dispersions of carbon allotropes in lipophilic matrices and related composite materials obtainable thereby

CN122003489ACN 122003489 ACN122003489 ACN 122003489ACN-122003489-A

Abstract

A process for preparing a lipophilic matrix composite comprising a dispersion of sp 2 carbon allotropes is described, comprising the steps of (A) mixing sp 2 carbon allotropes with a compound comprising a pyrrole ring of formula (i), wherein R 1 and R 3 are each independently of the other hydrogen or an alkyl group having a number of carbon atoms of 1 to 20, -R 3 is a linear or branched aliphatic group, with or without unsaturation, unsubstituted and free of functional groups such as OH, C=O, said R 3 having a number of carbon atoms of 1 to 40, (B) heating the mixture, (C) mixing the mixture obtained in step (B) with a lipophilic compound forming the matrix of the composite to obtain the composite. (i)。

Inventors

  • Julio Asanelli
  • Marcelo Notari
  • Ricardo Bo
  • Antonio Armico
  • Maurizio Stefano Galinbetti

Assignees

  • 埃尼股份公司

Dates

Publication Date
20260508
Application Date
20240731
Priority Date
20230801

Claims (19)

  1. 1. A method of preparing a composite material having a lipophilic matrix and comprising a dispersion of sp 2 carbon allotropes in the lipophilic matrix of the composite material, the method comprising the steps of: (A) Mixing an sp 2 carbon allotrope, in particular an sp 2 carbon allotrope having at least one dimension of less than 100 nm, with a compound containing a pyrrole ring of formula (i), optionally in the presence of one or more solvents Wherein: r 1 and R 2 are each independently of the other hydrogen or alkyl having a number of carbon atoms of 1 to 20, preferably 1 to 10, more preferably 1 to 5, even more preferably 1 to 2, R 1 、R 2 is preferably alkyl as defined above; -R 3 is an unsubstituted straight or branched aliphatic group, with or without unsaturation, and contains no functional groups such as OH, c=o, said R 3 containing a number of carbon atoms ranging from 1 to 40, preferably from 1 to 30, more preferably from 1 to 20, even more preferably from 6 to 20; Or alternatively R 3 is a polymer chain preferably derived from polyamines such as triethylenetetramine (TETA), diethylenetriamine (DETA), and from Polyisobutene (PIB) and maleimide, or R 3 is a polymer chain composed of polyetheramines containing polyoxyalkylene chains, such as jeffamine (5, 8-dimethyl-4, 7, 10-trioxatridecane-2, 12-diamine), The compound (i) is optionally obtained in situ in the step (a) by reaction of a1, 4-diketone with a primary amine R-NH 2 , wherein R = R 3 of the compound of formula (i); (a') optionally removing one or more of said solvents, when present, to obtain a solid or semi-solid mixture; (B) Heating, preferably with stirring and/or mixing, a mixture comprising the sp 2 carbon allotrope and the pyrrole compound of formula (i); (C) Mixing the mixture obtained in step (B) with a lipophilic compound constituting the lipophilic matrix of the composite, preferably under heating, to obtain a composite, preferably in the form of a paste, having a predetermined concentration of the sp 2 carbon allotrope in the lipophilic matrix of the composite; Optionally, a plurality of (D) Preferably, the composite material obtained in step (C) is diluted with the same or different lipophilic compound as used in step (C) under mixing to obtain a composite material having a total concentration of the sp 2 carbon allotrope lower than the predetermined concentration obtained in step (C).
  2. 2. The method of claim 1, wherein the lipophilic compound comprising the lipophilic matrix of the composite material has a molecular weight of greater than 200 g/mol excluding isoprene rubber, butadiene rubber, and the like.
  3. 3. The method according to claim 1 or 2, wherein the sp 2 carbon allotrope is selected from graphene, nanographites consisting of several graphene layers (several layers to several tens of layers), nanographites (HSAG) with a high surface area of preferably 100 to 400 m 2 /g, graphites, graphene, fullerenes, carbon nanotubes or combinations thereof, preferably high surface area nanographites (HSAG).
  4. 4. The process according to claim 1, 2 or 3, wherein steps (A), (B) and (C) can be carried out separately in sequence, or all three steps can be carried out simultaneously, each component (allotrope, pyrrole compound (i) and lipophilic matrix) being added separately in any order, or the first two steps (A) and (B) can be carried out simultaneously to obtain an addition product of the sp 2 carbon allotrope and the pyrrole compound (i), followed by step (C), wherein the product obtained in step (B) is mixed with the lipophilic matrix.
  5. 5. The process according to any one of the preceding claims 1-4, wherein step (a) is performed by dispersing the allotrope and the compound (i) in a low boiling point solvent selected from the group consisting of a non-polar solvent, a polar protic solvent, or a polar aprotic solvent under stirring or ultrasound.
  6. 6. The method according to any one of the preceding claims 1-4, wherein steps (a), (B) and (C) are performed simultaneously, the allotrope and the pyrrole compound (i) being added separately to the lipophilic matrix, optionally under heating (one-step one-pot method).
  7. 7. The process according to any one of the preceding claims, wherein prior to said step (a), a step (A0) is provided for the passage of a1, 4-dione of the formula And a primary amine R-NH 2 , wherein the R group is equal to the R 3 group of the compound of formula (i).
  8. 8. The process according to any one of the preceding claims, wherein step (B) is carried out with heating at a temperature typically from 80-100 ℃ to 170 ℃, preferably from 130 ℃ to 170 ℃, more preferably from 130 ℃ to 160 ℃, even more preferably about 150 ℃.
  9. 9. The method according to any of the preceding claims, wherein step (C) is performed with heating at a temperature at which the lipophilic matrix is in a liquid or molten state, preferably at a temperature of at least 80-100 ℃.
  10. 10. The method according to any one of the preceding claims, wherein the predetermined concentration of the sp 2 carbon allotrope in the lipophilic matrix of the composite material obtained from step (C) ranges as follows: -a number of 0.5 to 50 phm, Preferably from 1 to 35 phm and, Where phm refers to every hundred parts of lipophilic matrix (every hundred parts of matrix) which may be a base oil, wax, elastomer, grease or other type of lipophilic matrix or a combination thereof, preferably a base oil, wax, grease or a combination thereof.
  11. 11. A process according to any one of the preceding claims, wherein the amount of pyrrole compound of formula (i) is in the range 3 phc to 50 phc (per hundred parts carbon, 100 phc being considered to be the amount (weight) of the sp 2 carbon allotrope) relative to the amount of sp 2 carbon allotrope.
  12. 12. The method according to any one of the preceding claims, wherein the lipophilic compound (lipophilic matrix) is selected from the following: -lubricating oils or base oils for use in lubricating compositions, said oils being of mineral or synthetic origin or derived from renewable raw materials; -a fat lubricant; Waxy compound solids at room temperature, such as paraffin waxes, animal waxes, vegetable waxes, preferably hydrocarbon compounds, saturated fatty acids, saturated fatty acid esters having a carbon number equal to or greater than 12 to 32, such as myristate, palmitate, laurate, stearate, hexacosanoate and the like, the molecules of which have alkyl chains having a carbon number equal to or greater than 12 to 32; Polymer matrices, such as elastomers (e.g. gaskets, rubber materials), in particular "EPR/EPM" (ethylene-propylene copolymer based rubber) and typical block copolymers known as SBS (styrene/butadiene/styrene); -combinations thereof.
  13. 13. A process according to any one of the preceding claims, wherein the amount of pyrrole compound of formula (i) used is in the range 3 phc (per hundred parts carbon) to 50 phc relative to the sp 2 carbon allotrope, wherein phc means "per hundred parts carbon", considering that 100 phc is the amount (weight) of the allotrope.
  14. 14. A metal-free additive for imparting anti-friction and anti-wear properties to a lubricating composition in the form of an oil or grease, said additive being in the form of a composite comprising: sp 2 carbon allotropes, in particular sp 2 carbon allotropes having at least one dimension smaller than 100nm, A pyrrole compound of formula (i) as defined in any one of the preceding claims, A lipophilic base in the form of a base oil or lubricant as defined in claim 2 and/or 12, Wherein the concentration of said allotrope in said base oil or lubricating oil is in the range of 0.5 to 50 phm (per hundred parts of substrate, 100 phm being considered to be said base oil or lubricant), The additive is preferably obtainable from step (C) of the method according to any of the preceding claims.
  15. 15. A wax-based composite comprising Sp 2 carbon allotropes, in particular sp 2 carbon allotropes having at least one dimension smaller than 100nm, A pyrrole compound of formula (i) as defined in any one of the preceding claims, A lipophilic material in the form of a waxy compound as defined in claim 2 and/or 12, Wherein the concentration of said sp 2 carbon allotrope in said waxy compound ranges from 0.5 to 50 phm (per hundred parts of substrate, 100 phm is considered to be said waxy compound), The composite material is preferably obtainable from step (C) of the method according to any of the preceding claims.
  16. 16. A masterbatch additive for an elastomer to impart mechanical strength to an elastomeric material such as a gasket, rubber material, coating, said additive being in the form of a composite material comprising: sp 2 carbon allotropes, in particular sp 2 carbon allotropes having at least one dimension smaller than 100nm, A pyrrole compound of formula (i) as defined in any one of the preceding claims The lipophilic matrix in elastomeric form is preferably chosen from SBS and EPM, Wherein the concentration of said sp 2 carbon allotrope in said lipophilic matrix is in the range of 0.5 to 50 phm (per hundred parts of matrix, 100 phm being considered to be said elastomer), The composite material is preferably obtainable from step (C) of the method according to any of the preceding claims.
  17. 17. The additive according to any of the preceding claims 14, 16 and/or the composite according to claim 15, wherein the sp 2 carbon allotrope is selected from graphene, nanographites consisting of several graphene layers (several layers to several tens of layers), high surface area nanographites (HSAG), preferably 100 to 400 m 2 /g, graphite, graphene, fullerenes, carbon nanotubes or combinations thereof, preferably high surface area nanographites (HSAG).
  18. 18. An additive and/or composite according to any one of the preceding claims 14 to 17, wherein the amount of pyrrole compound of formula (i) used is in the range 3 phc (per hundred parts carbon) to 50 phc relative to the sp 2 carbon allotrope, wherein phc means "per hundred parts carbon", considering 100 phc as the amount (weight) of sp 2 carbon allotrope.
  19. 19. Lubricating composition in the form of a lubricating oil and/or grease comprising a base oil and at least one metal-free additive imparting anti-friction and anti-wear properties, wherein the at least one additive is a composite material according to any one of claims 14, 17, 18.

Description

Method for preparing stable and uniform dispersion of sp 2 carbon allotrope in lipophilic matrix and related composite material obtainable thereby Technical Field The present invention relates to a method for preparing a homogeneous dispersion of sp 2 carbon allotropes, in particular of at least one allotrope (e.g. graphene and nanographite) having a dimension of less than 100 nm, said allotrope being stable in a lipophilic matrix, since the dispersibility of said allotrope in said lipophilic matrix is improved. In particular, the present invention relates to a method as defined above for promoting the dispersion of sp 2 carbon allotropes in a lipophilic matrix, such as: Elastomer matrix (for example unsaturated elastomers such as natural rubber or saturated elastomers such as ethylene/propylene copolymers, which can be used to obtain gaskets, conveyor belts, etc.) and/or polymer matrix (including non-elastomeric matrix), with the result of improved dynamic mechanical properties, for example a non-linear (G 'decrease when measured with shear stress) of the modulus of elasticity, and therefore a variation value (Δg') of which decreases with the variation of the elongation, due to a decrease in the number of lattices formed by the allotrope itself; -a lubricating base oil which gives the allotrope dispersion a better stability in the lubricant; -a grease having improved lubricating ability due to uniform dispersion of allotropes; Waxy compounds, such as paraffin waxes, animal waxes, vegetable waxes or other waxy compounds (e.g. saturated fatty acid methyl esters having a C12 or higher number up to 32, such as lauric acid derivatives, stearic acid derivatives), the stability of carbon allotrope dispersions in wax matrices is improved when the wax matrix is above its melting point. More particularly, the present invention relates to a composite material comprising a functionalized sp 2 carbon allotrope obtainable by the above-described method, which is useful as an additive (e.g. master batch) for lubricating oils, greases and/or elastomeric compositions. Background In chemistry, an allotrope is a form of chemical element that differs in the manner in which atoms are bonded together. Carbon is one of the known chemical elements in the form of various allotropes and classification of carbon allotropes is usually based on hybridization of carbon atoms, carbon is sp 3 hybridized in diamond, and carbon is sp 2 hybridized in carbon black, graphite, nanographite, graphene, fullerene, carbon nanotubes, almost all of which are commonly used for preparing composite materials. Graphite, carbon nanotubes and carbon black are composed of graphene layers of different organization, and the graphene layers are an aromatic polycondensate system composed of one layer of carbon atoms, the thickness of which is a single carbon atom. The aforementioned sp 2 carbon allotropes (hereinafter also referred to as carbonaceous materials) are polymeric in nature. The repeating units are aromatic rings, typically having 5 or 6 carbon atoms. Sp 2 carbon allotropes are traditionally divided into "nanoscale" and "nanostructured". Chemical species are defined as "nanoscale" when at least one dimension is less than 100nm, with graphene, nanographite, fullerenes, and carbon nanotubes belonging to this class. On the other hand, carbon black used to reinforce polymeric materials and many other applications is "nanostructured" in that it is composed of nano-sized base spherical particles that are bound together to form an aggregate, wherein the base particles are bound together by covalent bonds. These aggregates are greater than 100 nm. The typical thermo-mechanical stresses to which carbon black is admixed with the polymer matrix and the thermo-mechanical stresses to which the composite is subjected during its application are not capable of separating the aggregates into their fundamental components. Sp 2 carbon allotropes have excellent electrical and thermal conductivity, respectively, due to their aromatic nature and structure, and are capable of imparting important mechanical properties, such as mechanical enhancement, "nanoscale" and "nanostructured" sp 2 carbon allotropes, thus having a variety of different and numerous important applications. In order to prepare a composite material containing sp 2 carbon allotropes, a mixing operation must be performed between the allotropes and the matrix of the composite material to achieve the distribution and dispersion of the allotropes in said matrix. In order to have a uniform distribution, the allotropes must be uniformly distributed throughout the matrix of the composite material, regardless of the agglomeration and aggregation state of the starting carbonaceous material. During mixing, the underlying spherical particles or carbon atom layers of the allotrope aggregates must be dispersed in the matrix to obtain optimal dispersion. However, it is well known that distributing and dispersing graphit