Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1999-06-16
2001-07-17
Dawson, Robert (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C528S107000, C564S373000
Reexamination Certificate
active
06262148
ABSTRACT:
The present invention relates to a novel class of phenalkamines and epoxy resin compositions containing the same wherein the cured coatings resulting therefrom have reduced Gardner color index. In particular, the novel phenalkamines are prepared via a Mannich base reaction sequence by reacting a selected phenol compound that is substituted with a carbonyl group containing compound and at least one selected aromatic or alicylic polyamine. The resulting phenalkamine can be used as a curing agent in epoxy resin compositions for coatings, finishes and varnishes.
BACKGROUND OF THE INVENTION
Mannich base reactions are well-known. Mannich base compounds are products based on the reaction of an aldehyde, generally formaldehyde, a phenolic compound and an amine. Various forms of phenolic compounds, amines and aldehydes have been proposed. Mannich base products are known to be suitable for curing epoxy resins.
Phenalkamine curing agents are a class of Mannich bases obtained by reacting a cardanol-containing extract derived from cashew nutshell liquid, an aldehyde compound, such as formaldehyde, and an amine. Commercially available phenalkamines use ethylenediamine and diethyltriamine as the amine. Phenalkamines are good epoxy resin hardeners for room temperature or low temperature curing applications. Phenalkamines, however suffer from the disadvantage that the cured epoxy articles are very dark in color (Gardner Color Index greater than 14), blushing and low mechanical properties. Due to the dark coloring of the cured coatings, epoxy resin compositions containing phenalkamine curing agents have been limited to use as primers and generally cannot be used as top coat material.
The extract from cashew nutshell liquid primarily contains a mixture of cardanol (I), cardol (II),
where n depends upon whether the side chain is saturated or unsaturated (n=0 for saturated, n=2 for monoene, n=4 for diene, and n=6 for triene), and related compounds of varying degrees of saturation. Numerous methods have been developed to purify the extract from cashew nutshell liquid with the stated goal of obtaining an isolated solution of cardanol. Typically, a purified extract solution will contain primarily cardanol with a minor amount of cardol.
SUMMARY OF THE INVENTION
The present invention relates to a novel phenalkamine compound according to formula (1)
wherein n is 0, 2, 4 or 6,
a, b and c are, independently of one another, 1 or 0, R
1-1a
R
1-1b
and R
1-1c
are, independently of one another, hydrogen, a hydrocarbyl containing 1 to 10 carbon atoms which are alkyl, aryl, alkylene, arylalkyl or alkylaryl or a hydrocarbyl containing 1 to 10 carbon atoms and at least one heteroatom which can be oxygen, sulfur or nitrogen;
R
2-1a
, R
3-1a
, R
4-1a
, R
5-1a
, R
2-1b
, R
3-1b
, R
4-1b
, R
5-1b
, R
2-1c
, R
3-1c
, R
4-1c
and R
5-1c
are independently of one another, hydrogen or C
1
-C
4
alkyl, R
6-1a
, R
7-1a
, R
6-1b
, R
7-1b
, R
6-1c
and R
7-1c
are, independently of one another C
1
-C
4
akyl; and A is an aromatic or alicyclic ring having 5 to 7 carbon atoms. Preferably, R
1-1a
, R
1-1b
and R
1-1c
are independently of one another, methyl, and a, b and c, independently of one another are 1 or 0. More preferably, R
1-1a
is hydrogen, a is 1 and b and c are 0.
R
2-1a
, R
3-1a
, R
4-1a
, R
5-1a
, R
2-1b
, R
3-1b
, R
4-1b
, R
5-1b
, R
2-1c
, R
3-1c
, R
4-1c
and R
5-1c
are preferably, independently of one another, hydrogen, methyl or ethyl, and a, b and c, independently of one another are 1 or 0. More preferably, R
2-1a
, R
3-1a
, R
4-1a
, and R
5-1a
are each hydrogen, a is 1 and b and c are 0. Most preferably, R
2-1a
, R
3-1a
, R
4-1a
, and R
5-1a
are each hydrogen, a is 1 and b and c are 0.
R
6-1a
, R
7-1a
, R
6-1b
, R
7-1b
, R
6-1c
and R
7-1c
are preferably, independently of one another, methyl or ethyl and a, b and c, independently of one another, are 1 or 0. More preferably, R
6-1a
and R
7-1a
are methyl or ethyl, a is 1 and b and c are 0.
A is preferably an aromatic or alicyclic ring having 6 carbon atoms. More preferably, A is an aromatic or alicylic ring having 6 carbon atoms.
The present invention is a compound ideally represented by formulae (1a) or (1b):
wherein n, a, b and c have been defined above.
The present invention further relates to a Mannich base reaction product obtained by combining an extract from cashew nutshell liquid with at least one aromatic or alicylic polyamine and at least one aldehyde compound. The extract cashew nutshell liquid preferably contains a major portion of cardanol (I) and a minor amount of cardol (II)
where n is 0, 2, 4 or 6. The extract cashew nutshell liquid preferably contains cardanol (I) and of cardol (II) in a weight ratio of about 90:10 to about 98:2. The Mannich base reaction product is preferably obtained by combining the extract and the at least one aldehyde compound with a polyamine selected from xylenediamine, 1,3-bis(aminomethyl)cyclohexane, and mixtures thereof. The Mannich base reaction product preferably comprises at least one compound ideally represented by structural formulae (1a) or (1b):
wherein n has been defined above, a, b and c, are, independently of one another, 1 or 0, and an average value for the sum of (a+b+c) is about 1.2 for all of the compounds corresponding to formulae (1a) and/or (1b) in said Mannich base reaction product mixture.
The present invention further relates to an epoxy resin composition including a) a novel phenalkamine compound described above and b) an epoxy resin having on average more than one glycidyl group per molecule. Alternatively, the present invention relates to an epoxy resin composition including a) a Mannich base reaction product described above and b) an epoxy resin having on average more than one glycidyl group per molecule.
The present invention further relates to a curable formulation including a) an epoxy resin composition containing the novel phenalkamine compound and an epoxy resin having on average more than one glycidyl group per molecule and b) a pigment. In the alternative, the present invention relates to a curable formulation including an epoxy resin composition containing a Mannich base reaction product and an epoxy resin having on average more than one glycidyl group per molecule and b) a pigment.
The present invention further relates to a method for coating a surface having reduced yellowness index using a phenalkamine-containing composition that comprises applying a curable formulation described above to the surface. In the alternative, the present invention relates to a method for coating a surface having reduced yellowness index using a Mannich base reaction product-containing composition that comprises applying a curable formulation described above.
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Print Outs of Chem. Abstracts Reg. File Structures for Phenols Substituted with Cis-Aliphatic Groups, pvc Jun. 1999.*
Expoy Resin Chemistry Series 114, No. 9, Gardiner et al., Phenalkamines—“A New Class of Epoxy Curing Agents”, pp. 98-114.
ASTM Designation:D 3363-92a “Standard Test Method for Film Hardness by Pencil Test” pp. 360& 361.
ASTM Designation:D 3359-95 “Standard Test Methods for Measuring Adhesion by Tape Test” pp. 350-355.
ASTM Designation:D 2794-82 “Standard Test Method for Resistance of Organic Coatings to The Effec
Bender David
Cheng Chi-Wen Frank
Wang Hsing Tie
Aylward D.
Dawson Robert
Lyon & Lyon LLP
Neuman Kristin H.
Shalek James H.
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