I
J. C. PETROPOULOS, L. E. CADWELL', and W. F. HART' Stamford Laboratories, Research Division, American Cyanamid Co., Stamford, Conn.
Acrylonitrile in Styrenated Alkyd Resins As surface coatings, styrenated alkyds have low resistance to oils, greases, an,d hydrocarbon solvents. Acrylonitrile as a partial replacement for styrene, improves solvent resistance, drying rate, and in enamels during early stages of exterior exposure, reduces chalking and bronzing
ACRYLONITRILE
was discovered more than half a century ago but it did not attain commercial importance until after World War I when German chemists found that in combination with butadiene it produced rubbers with exceptionally good resistance to oils, greases, and various solvents. Large-scale production was undertaken in this country during World War I1 in conjunction with the national synthetic rubber program. With the ending of the war, however, military Y rubber diminished demands for Buna i and acrylonitrile became available in large volume at a reasonable price. Since then acrylonitrile or its copolymers have found steadily increasing use in molding compounds to improve toughness and flexibility, poly(viny1 chloride) resins as nonmigratory plasticizers with excellent flexibility and chemical resistance, latices for leather, paper, textiles and paint, synthetic fibers, and as intermediates in various chemical processes to produce new and useful derivatives. Improved solvent resistance and toughness exhibited by copolymers containing acrylonitrile prompted an investigation of its use as a partial replacement for styrene in styrenated alkyd resins ( 4 ) . The latter have gained wide acceptance in the surface coating field because of their fast drying properties, excellent gloss: and toughness (6); but their use Present address, American Cyanamid Co., Bridgeville, Pa.
Table I. Composition and Characteristics of Alkyd Resins Materials, pts. by wt.
A
B
Phthalic anhydride 148 148 Glycerol, C.P., 98% 9 106 Linseed monoglycerides 363 Double distilled tall oil fatty acids (DDTOFA) 287
...
...
Completed resin Acid value Viscositp, Gardner-Holdt ColoP, Gardner Oil content, yo
11.5
8.4
H-I 9
F 7-8
60
60
Determined for a 70% solution of resin ,in xylene.
Table II. Compositions of Fatty Acid Modifiers Linseed Oil
Fit& DDTOFA, Acids, Acid Typea Saturated Oleic (-CH=CHCHa-) Linoleic (-CH=CHCH*CHeCH-) * Linolenic (-CH=CHCHzCH=CHCHzCH=
*
%
%
2 50
11 21
48
18
0
50 180
*
CH-, Iodinevalue, Wijs
130
a The groups i n parentheses are the olefinic unsaturated portion of fatty acids. * Starred methylene groups are activated by two adjacent allylic groups.
in certain applications has been limited by their sensitivity to oils, greases, and hydrocarbon solvents. Modifying these resins with acrylonitrile extends their range of usefulness by markedly improving solvent resistance, drying speed, and hardness (2, 8, 9). Interpolymers were prepared by coreaction of a substantially nonconjugated oil modified alkyd resin with styrene or methylstyrene and with mixtures of each of these and acrylonitrile in xylene solution using di-tert-butyl peroxide catalyst. The resulting interpolymers were compared for color, viscosity, monomer conversion, and solution clarity. The interpolymers were also compared in clear air-dry films for rate of dry, and for aliphatic solvent resistance and clarity. The methylstyrene used throughout this work was a mixture of 65% para, 33y0 ortho, and 2% meta methylstyrenes.
Experimental Preparation of Alkyd Resins. Alkyd resins were prepared from commercially available materials according to the formulations given in Table I. Approximately 3300 grams of material was heated to 260' C. in a three-necked glass flask equipped with stirrer, thermometer, and a means for introducing nitrogen a t a rate of about 500 cc. per minute. The ingredients were held a t 260' C. until esterification was substantially completed (approximately 4 hours). Linseed monoglycerides were prepared VOL. 49, NO. 3
MARCH 1957
379
Table 111.
Styrene,
70
Characteristics and Composition for Interpolymers of Linseed Alkyd
Monomer Methyl- AcryloConstyrene, nitrile, verbion,
.. .. ..
40 38 35
.. 2
5
..
30 28
..
.. ..
40 35 30 28
..
.. a
70
70
10 12
..
G-I1
90.8 90.8 91.7 90.0 90.8
B
90.0 92.5 93.3 90.8
5 10 12
Yi>cosity,
c /c
TackFree Time, Nin.
Mineral Spirits Failure 'Ihe, hlin.
Color, Ciadner
Claritya. Film
7 9.- 10 10 10-11 10-11
9 10 10 10 10
88 96 99 24
10
10 20 80 >360 360
10 10 10 10
78 101 34 15
5 120 360 360
C G-H
Y Z j tail
A-B
6 9+ 9 9+
E-F x-Y ZJ tail
> >
All solutions were clear.
Table IV.
Characteristics and Composition for lnterpolymers of DDTOFA Alkyd MonolllPr
Styrene,
Methyl- -4crylostyrene, nitrile,
70
7c
.. .. ..
40 38 35 33 30
*.
..
.. ..
40 38 35 30
.. ..
c? /C
.. 2
5 7 10
.. 2
5 10
Conversion.
\-i,+
c*osity. (.:
