1. A process for manufacturing an epoxy resin by reaction of dichloropropanol with a compound containing at least one active hydrogen atom and with a basic agent, in order to produce the epoxy resin and a salt, in which epichlorohydrin is formed in situ during the reaction, in which at least part of the epichlorohydrin formed in situ is recovered and at least one fraction of the recovered epichlorohydrin is recycled to the reaction, and wherein the chemical formula of the epoxy resin contains at least one 2.3-epoxypropyloxy group.
2. The process according to claim 1 wherein the epoxy resin is selected from the group consisting of Type I Grade 1 Classes A to H, Type II Grade 1 Classes A to F and Type VI Grade 1 Class A resins, as defined in the ASTM D 1763 - 00 (2005) standard entitled "Standard Specifications for Epoxy Resins", and any mixture thereof.
3. The process according to claim 1 or 2 wherein the compound containing at least one active hydrogen atom is a polyol selected from the group constituted of bisphenol A (4,4'-dihydroxy-2,2-diphenylpropane, 4,4’-isopropylidenediphenol), tetrabromobisphenol A (4,4’-isopropylidenebis(2,6-dibromophenol)), bisphenol AF (4,4'-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]bisphenol), hexafluorobisphenol A (4,4'-dihydroxy-2,2-diphenyl-1,1,1,3,3,3-hexafluoropropane), 1,1,2,2-tetra(p-hydroxyphenyl)ethane, tetramethylbisphenol (4,4’-dihydroxy-3,3’,5,5’-tetramethyl bisphenol), 1,5-dihydroxynaphthalene, 1,1’,7,7’-tetrahydroxydinaphthylmethane, 4,4’-dihydroxy-α-methylstilbene, a condensation product of bisphenol A with formaldehyde (bisphenol A novolac), a condensation product of phenol with formaldehyde, a condensation product of cresol with formaldehyde (mixture of o,o’, o,p’ and p,p’ isomers of methylhydroxydiphenylmethane), an alkylation product of phenol and of dicyclopentadiene (2,5-bis[hydroxyphenyl]octahydro-4,7-methano-5H-indene), a condensation product of phenol and of glyoxal (tetrakis(4-hydroxyphenyl)ethane), a condensation product of phenol and of a hydroxybenzaldehyde (e.g. tris(4-hydroxyphenyl)methane), 1,1,3-tris(p-hydroxyphenyl)propane, and mixtures of at least two of them, or p-aminophenol, or wherein the compound containing at least one active hydrogen atom is a polyol selected from the group consisting of a polyphenol, a sugar, a polyol derived from a sugar, an acid polyphenol, any derivative thereof, and any mixture thereof.
4. The process according to claim 1 or 2, wherein the basic agent is selected from the group consisting of alkali and alkaline-earth metal oxides, hydroxides, carbonates, hydrogen

carbonates, and mixtures of at least two of them, and wherein the salt is selected from the group consisting of alkali and alkaline-earth metal chlorides, and mixtures of at least two of them.
5. The process according to claim 1, comprising at least one liquid-liquid phase separation step to remove at least one part of the epichlorohydrin formed in situ.
6. The process according to claim 1, wherein at least 50 % of the recovered epichlorohydrin is recycled to the reaction.
7. The process according to claim 1 or 2, comprising adding to the reaction, epichlorohydrin which has been obtained in another process.
8. The process according to claim 1 or 2, wherein the reaction is carried out in the presence of a solvent.
9. The process according to claim 8, wherein at least one of the dichloropropanol, of the compound containing at least one active hydrogen atom, of the epichlorohydrin obtained in the other process, of the basic agent and of the solvent, has been obtained from renewable raw materials.
10. The process according to claim 1, wherein the reaction is carried out in a reaction zone, said reaction zone is fed with the dichloropropanol, with the compound containing at least one active hydrogen atom, with the basic agent and with the recycled epichlorohydrin, and exhibiting at least one of the following features :

• the ratio between the quantity of dichloropropanol expressed in mol of dichloropropanol and of the quantity of the compound containing at least one active hydrogen atom expressed as mol of active hydrogen atoms, fed to the reaction zone, is higher than or equal to 0.1 and lower than or equal to 10,
• the ratio between the quantity of the recycled epichlorohydrin expressed in mol of epichlorohydrin and the quantity of dichloropropanol expressed in mol of dichloropropanol ; fed to the reaction zone, is higher than or equal to 0.01 and lower than or equal to 0.999.

11. The process according to claim 1 or 2 carried out under discontinuous mode.
12. The process according to claim 1 or 2, wherein the basic agent is caustic soda and the salt is sodium chloride obtained as a brine exhibiting a Total Organic Carbon, comprising treating the brine to reduce its Total Organic Carbon, electrolyzing the treated brine to produce

hydrogen, chlorine and the caustic soda, reacting the hydrogen and the chlorine to produce hydrogen chloride, and reacting the hydrogen chloride with glycerol to produce the dichloropropanol.
13. The process according to claim 12, wherein at least one part of the hydrogen chloride has been obtained by reacting hydrogen and chlorine, in a molar ratio between hydrogen and chlorine lower than or equal to 1.
14. The process according to claim 12, wherein the molar ratio between the hydrogen chloride consumed in the process, and the sodium chloride generated in the process, expressed as elemental chlorine (Cl) is higher than or equal to 0.9.