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Dicarboxylic acid is an organic compound containing two carboxyl functional groups (-COOH). They are used in the preparation of copolymers such as polyamides and polyesters

Example: Pthalic acid An aromatic dicarboxylic acid ,which is one of three isomers of benzenedicarboxylic.

Polymerisation :

Chemical reaction in which two or more molecules combine to form larger molecules that contain repeating structural units

Dimerization:

The chemical union of two identical molecules.

Dimer:A dimer is an oligomer consisting of two structurally similar monomers joined by bonds that can be either strong or weak, covalent or intermolecular

Oligomer: is a polymer whose molecules consist of relatively few repeating units

Dimer Acid

Properties of Dimer acid

Drilling Fluids.

  • Light yellow transparent viscous liquid
  • Stable performance(Resist chemical decomposition in presence of water)
  • Non-toxic
  • Non-volatile
  • Non-flammable
  • High flash point and fire point
  • Good liquidity(flow and wetting properties)
  • Do not freeze in low temperature
  • Soluble in most organic solvents
  • Balance of hardness and flexibility
  • Carboxyl-multi-functionality,which allows conversion to high polymers

Definition

  • The reaction involves oligomerization of C18 unsaturated fatty acid derived from vegetable oil.
  • The predominant product of oligomerization reaction is are C36 di-acid compounds,in which the C18 units are linked together by carbon-carbon bonds in a variety of ways.for this reason,reaction is called dimerization.
  • A small amount of C54 tri-acid and higher poly acids also form during oligomerization process.
  • This undistilled dimer acid can be further processed by very high vaccum distillation and hydrogenation to yield premium dimer acids

Summary of production process:

1.Mixture of FattyAcid , Clay catalyst and water in certain ratio is fed to a reactor( Autoclave) and heated to desired temperature.

2. The mixture is left to cool to room temperature for couple of hours.

3. The catalyst is then separated from crude product by fitration.

4.The filtrate is fractioned to monomer acid(distillate),which is a co-product of saturated and unsaturated branched chain C-18 FA, and dimer acid mixed with higher polymers(residue).

5.The dimer acid is then subjected to high vaccum distillation to seperate from trimer acid.

6. Further hydrogenation and distillation to improve color and stability of the product.

لقبريؤيساليي

Typical applications

conversion of unsaturated fatty acids into a molecule with 36 carbon atoms, making it the longest dioic acid available.

Dimer acids, or dimerized fatty acids, are dicarboxylic acids prepared by clay-catalyzed, high temperature(>300 C) ,high pressure (400 psi) polymerization of unsaturated fatty acids obtained from tall oil (usually), oleic acid (rectified cotton oleic acid or soybean oleic acid), linoleic acid, canola oil , cottonseed oil, Rapeseed oil ,Dehydrated castor oil or Tallow.

Dimer acid in Polyamide resins

The major use category of dimer acids is non-nylon type polyamide resins. Non-nylon polyamides may be reactive(having amine functional groups) or nonreactive ( lacking amine functionality)

Continued..

The reactive polyamides are mainly used as curing agents for epoxy resins employed in adhesives and surface coatings.

Polyamide resins

High-molecular-weight polymers which feature amide linkages (single bond between carbon and nitrogen atom) along the molecular chain.

Natural polyamides include a wide range of proteins from which adhesives and plastics may be derived.

Synthetic polyamides, such as nylon and aramid resins, are used extensively in commercial applications.

The nonreactive polyamides find themselves predominantly in hot-melt adhesive applications and flexographic and rotogravure printing inks.

  • hydrolytic stability
  • chemical resistance
  • water repellency
  • balance of hardness and flexibility
  • impact strength
  • heat resistance
  • flow and wetting properties
  • oil and solvent solubility

The presence of dimer acid in these polymers imparts flexibility, corrosion resistance, impact strength, and water resistance in the finished resin.

  • Co-reactant in the manufacture of polymers such as Polyamide resins and polyamide hot melt adhesives.
  • Synthetic Lubricants
  • Fuel oil Additives and lubricants
  • Alkyd Resins
  • Polyol Esters(synthitic Esters-used as lubricants)
  • Oil field Drilling Muds
  • Corrosion Inhibitors for oil fields and refinary processes.
  • Personal Care(Due to their lipophilic (oil-loving) structure)
  • Adhesives

Properties of DAP's

(Dimer acid based polymers)

• Hydrolytically stable

• Have very low glass transition temperatures

• Increase colour strength through excellent pigment wetting

• Enhance adhesion to low polar substrates

• Boost water flash off in water borne coatings and adhesives

• Minimize internal stress and shrinkage in cross linked polymers

• Enhance water repellence, reduce water uptake and water diffusion

Trimer Acid & C36 Dimer acid

C36 dimer acid is a dimer acid of predominantly stearic acid ,making it the longest di-acid available.

The chemistry can be taken further to form a trimer acid where the product consists of three fatty acid molecules.

This hydrocarbon nature makes the dimer fatty acid and derived polymers extremely hydrophobic. In addition, the combination of hydrocarbon character and non-crystallinity provides lubricity and flexibility, even at very low temperatures.

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