8 Oleochemistry Products
239
(70:30 w:w) resulted in desired improvement and application for coating purposes
[19]. Modification of long oil palm stearin based alkyd resin was done through blending it with a commercially available ketone resin (cyclohexanone–formaldehyde) to
improve its coating characteristics. The effects of blending on air drying time, hardness, adhesion, gloss, impact strength, chemical resistance and thermal behaviour of
dried films of blends were investigated and compared to virgin alkyds. It was found
that blending results in modifying coating characteristics of palm stearin based alkyd
resins, significantly. The best result was observed for weight ratio 70:30 of alkyd and
ketone resins [19].
Polyesteramides: modified alkyds obtained by the esterification reaction between
VO amide diol and an acid/anhydride. They are characterized by improved properties
over alkyds such as water vapour resistance, hardness, ease of drying and resistance
to alkalis. The synthesis of polyesteramides follows two different steps: (i) VO amidation with diethanolamine in the presence of sodium methoxide; (ii) esterification
between the hydroxyl groups of amide diols with an anhydride. These steps generally
require high reaction temperatures (>120 °C) and long times (>5 h) in the presence
of solvents [9]. Microwaves were recently proposed to reduce the reaction times
(4 min) and temperatures [9]. The presence of ester, amide, double bonds, leads to
a superior chemical resistance, thermal stability and imparts flexibility. Moreover,
further chemical reactions are possible on the mentioned functional groups to give
the final product chemical and physical properties tailored to the final application
[240].
Polyetheramides: alternating amide and ether moieties. The synthesis of
polyetheramides consists of a two-step process: (i) preparation of VO amide diols;
(ii) condensation reaction between amide diols, bisphenol-A and resorcinol [8]. In
this case, drying occurs by two consecutive steps: solvent evaporation and baking at
elevated temperature (thermal polymerization through migration of double bonds).
Fatty acids: although fatty acid modified polyurethane dispersions are well
known, fatty acid methyl esters are quite new as a raw material for coating resins.
The chemical difference between these two raw materials is the carboxylic group
and methyl ester group, which has no influence on the resulting polyester polyol,
because both groups lead to ester bonds. However, the reaction velocity at the beginning can be accelerated by using fatty acid methyl esters, because of the better leaving
group in the case of fatty acid methyl ester. Different kinetics may cause different
polyester structures as well. Another reason why fatty acids have been more favoured
in coating resins than fatty acid methyl esters is their fatty acid composition, which
often comprises a high amount of unsaturation. High amounts of unsaturation, especially linolic (18:2) and linolenic acid (18:3), can additionally be cured by oxidation
(alkyds). Fatty acids methyl esters, commercially produced for biodiesel, are often
based on lower amounts of unsaturation such as rapeseed oil or palm oil. The dominant fatty acid in these fatty acid compositions is oleic acid (18:1). The lower level
of unsaturation may be an advantage and lead to less yellowing [166].
Philipp et al. [166] further concluded that fatty acid methyl esters are suitable
to substitute fatty acids in polyester polyurethane coatings [164]. The reaction time
for polycondensation can be shortened. Furthermore, the neutralization and stirring
239
(70:30 w:w) resulted in desired improvement and application for coating purposes
[19]. Modification of long oil palm stearin based alkyd resin was done through blending it with a commercially available ketone resin (cyclohexanone–formaldehyde) to
improve its coating characteristics. The effects of blending on air drying time, hardness, adhesion, gloss, impact strength, chemical resistance and thermal behaviour of
dried films of blends were investigated and compared to virgin alkyds. It was found
that blending results in modifying coating characteristics of palm stearin based alkyd
resins, significantly. The best result was observed for weight ratio 70:30 of alkyd and
ketone resins [19].
Polyesteramides: modified alkyds obtained by the esterification reaction between
VO amide diol and an acid/anhydride. They are characterized by improved properties
over alkyds such as water vapour resistance, hardness, ease of drying and resistance
to alkalis. The synthesis of polyesteramides follows two different steps: (i) VO amidation with diethanolamine in the presence of sodium methoxide; (ii) esterification
between the hydroxyl groups of amide diols with an anhydride. These steps generally
require high reaction temperatures (>120 °C) and long times (>5 h) in the presence
of solvents [9]. Microwaves were recently proposed to reduce the reaction times
(4 min) and temperatures [9]. The presence of ester, amide, double bonds, leads to
a superior chemical resistance, thermal stability and imparts flexibility. Moreover,
further chemical reactions are possible on the mentioned functional groups to give
the final product chemical and physical properties tailored to the final application
[240].
Polyetheramides: alternating amide and ether moieties. The synthesis of
polyetheramides consists of a two-step process: (i) preparation of VO amide diols;
(ii) condensation reaction between amide diols, bisphenol-A and resorcinol [8]. In
this case, drying occurs by two consecutive steps: solvent evaporation and baking at
elevated temperature (thermal polymerization through migration of double bonds).
Fatty acids: although fatty acid modified polyurethane dispersions are well
known, fatty acid methyl esters are quite new as a raw material for coating resins.
The chemical difference between these two raw materials is the carboxylic group
and methyl ester group, which has no influence on the resulting polyester polyol,
because both groups lead to ester bonds. However, the reaction velocity at the beginning can be accelerated by using fatty acid methyl esters, because of the better leaving
group in the case of fatty acid methyl ester. Different kinetics may cause different
polyester structures as well. Another reason why fatty acids have been more favoured
in coating resins than fatty acid methyl esters is their fatty acid composition, which
often comprises a high amount of unsaturation. High amounts of unsaturation, especially linolic (18:2) and linolenic acid (18:3), can additionally be cured by oxidation
(alkyds). Fatty acids methyl esters, commercially produced for biodiesel, are often
based on lower amounts of unsaturation such as rapeseed oil or palm oil. The dominant fatty acid in these fatty acid compositions is oleic acid (18:1). The lower level
of unsaturation may be an advantage and lead to less yellowing [166].
Philipp et al. [166] further concluded that fatty acid methyl esters are suitable
to substitute fatty acids in polyester polyurethane coatings [164]. The reaction time
for polycondensation can be shortened. Furthermore, the neutralization and stirring