Manufacture of novolacs and resoles using lignin
Processes for manufacturing novolacs and resoles from lignin are disclosed. A phenol-aldehyde-lignin dispersion is formed which can then be used to make either a novolac or a resole, depending upon the catalysts used.
1. A process comprising:
a) heating a mixture of a first phenol, lignin, and a first catalyst comprising an acidic compound or a basic compound to a temperature in the range of from 100° C. to 200° C. to form a dispersion;
b) cooling the dispersion to a temperature in the range of 60° C. to 99° C.;
c) adding an aldehyde to the dispersion;
d) condensing the dispersion to form a phenol-aldehyde-lignin dispersion having from 1 to 10 weight percent of free aldehyde;
e) cooling the phenol-aldehyde-lignin dispersion;
f) adding a second phenol to the phenol-aldehyde-lignin dispersion;
g) condensing the phenol-aldehyde-lignin dispersion under reflux conditions in the presence of a second catalyst comprising an acidic compound to form a novolac having from 0.01 to 1 weight percent free aldehyde; and
h) vacuum distilling the novolac to produce a vacuum distilled novolac having from 0.01 to 10 weight percent free phenol.
2. The process of claim 1 , wherein in step c), the aldehyde is added to the dispersion in an amount in the range of from 0.9 to 4.5 moles of aldehyde per mole of phenol.
3. The process of claim 1 , wherein in step f), the second phenol is added to the phenol-aldehyde-lignin dispersion to provide a molar ratio of aldehyde to phenol of 0.1 to 0.9 moles of aldehyde per mole of phenol.
4. The process of claim 1 , wherein the lignin is selected from the group consisting of lignosulfonates, lignosulfonate salts, kraft lignins, pyrolytic lignins, steam explosion lignins, organosolv lignins, soda-ash lignins, dilute acid lignins, biorefinery lignins, and combinations thereof.
5. The process of claim 1 , wherein the lignin is present in the mixture of step a) in an amount in the range of from 1 weight percent to 60 weight percent.
6. The process of claim 1 , wherein the first phenol and second phenol are the same or different and are selected from the group consisting of phenol, o-methylphenol, p-methylphenol, m-methylphenol, para-tert-butyl phenol, p-octylphenol, p-phenylphenol, p-cumylphenol, p-isopropylphenol, p-nonylphenol, 2,3-dimethylphenol, 2,4-dimethylphenol, 2,5-dimethylphenol, 2,6-dimethylphenol, 3,4-dimethylphenol, 3,5-dimethylphenol, o-ethylphenol, m-ethylphenol, p-ethylphenol, bisphenol-A, resorcinol, catechol, alpha-naphthol, beta-naphtol, cardanol, and combinations thereof.
7. The process of claim 1 , wherein the aldehyde is selected from the group consisting of formaldehyde, paraformaldehyde, trioxane, acetaldehyde, polyoxymethylene, propionaldehyde, isobutyraldehyde, glyoxal, gluteraldeyhde, benzaldehyde, acrolein, crotonaldehyde, furfural, 5-hydromethylfural, and combinations thereof.
8. The process of claim 1 wherein the first catalyst is selected from the group consisting of sodium metal, sodium hydroxide, potassium metal, potassium hydroxide, lithium hydroxide, ammonium hydroxide, magnesium hydroxide, calcium hydroxide, barium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, potassium phosphate, sodium phosphate, lithium phosphate, ethanol amine, diethanol amine, triethanol amine, triethyl amine, tributyl amine, hexamine, melamine, hexamethylene diamine, guanidine, benzoguanamine, hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, oxalic acid, formic acid, acetic acid, trifluoroacetic acid, methane sulfonic acid, and p-toluenesulfonic acid; and wherein the second catalyst is selected from the group consisting of hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, oxalic acid, formic acid, acetic acid, trifluoroacetic acid, benzoic acid, methane sulfonic acid, and p-toluenesulfonic acid .
9. The process of claim 1 , further comprising i) adding a crosslinker to the vacuum distilled novolac.
10. The process of claim 9 , wherein the crosslinker is selected from the group consisting of hexamine, epoxy resins, resoles, polyisocyanates, paraformaldehyde, polybenzoxazines, cyanate esters, and combinations thereof.