I N D U S T R I A L and ENGINEERING CHEMISTRY Vol. 31 C o n s e c u t i v e N o . 22
NEWS EDITION
H A R R I S O N E. HOWE Editor
Published by the A M E R I C A N CHEMICAL V O L U M E 17
SOCIETY
J U N E 10, 1939
N U M B E R 11
Casein Fiber1 E. O. WHITTIER AND S. P. GOULD Division of Dairy R e s e a r c h L a b o r a t o r i e s , B u r e a u of Dairy I n d u s t r y , U n i t e d S t a t e s D e p a r t m e n t of A g r i c u l t u r e , W a s h i n g t o n , D . C . NEW use for casein, which has aroused t h e interest and activity of textile and dairy people in Europe and America, is t h e production of a textile fiber similar in properties to wool. T o newspaper reporters and columnists, it has seemed amusing and surprising t h a t "wool" can be made from milk. T h e product is, of course, not wool, although it resembles it more closely, both physically and chemically, than rayon resembles silk. I n order t o understand t h e situation in regard t o t h e manufacture of textile fiber from casein, it is necessary t o know first something of the background and history of its development. T h e increase of world rayon production from none t o nearly 2,000,000,000 pounds a year has taken place almost entirely within a generation. This has involved, not only the solution of chemical and physical problems related directly to the substance of t h e fiber, but also the development of machinery of a hitherto unknown type. Rayon is a vegetable fiber, being either a regenerated cellulose or a cellulose derivative m a d e from cotton linters or wood pulp. I n t h e viscose process this raw material is dissolved in alkali and carbon disulfide, t h e solution is ripened and forced through fine openings into an acid bath, and the fibers are then stretched and wound. Rayon is used as a substitute for silk and, therefore, it has customarily been woven as a continuous fiber rather than as staple or c u t fiber. Only recently has there been available a staple rayon with the kink and resilience of animal fibers such as wool. Staple rayon is being woven in combination with wool t o a con= siderable extent, in spite of the facts t h a t its kink is not permanent and t h a t it does not take t h e same dyes as wool. T h e high cost of wool, relative to other textile fibers, has made a cheap substitute attractive in the same sense that the high cost of silk induced the development of rayon. Italy's difficulty in obtaining wool during t h e Abyssinian campaign acted as a stimulus to accelerate this development. A substitute for wool should nave approximately t h e same chemical properties of resistance to laundering agents as wool itself and also the ability t o take t h e same dyes. I t should have the physical properties of wool in as high a degree as possible— strength, resilience, stretch, etc. T h e chemical requirements point to casein, since it is a readily available animal protein closely approximating wool in chemical composition. Physical similarities are t o be attained mostly b y manufacturing details. T h e first p a t e n t for converting casein into textile fiber was granted t o Dr.
A
1 Presented as çart of the Joint Symposium on the Industrial Utilisation of Dairy Products before the Divisions of Agricultural and Food Chemistry and Biological Chemistry at the 97th Meeting of the American Chemical Society. Baltimore. Md., April 4. 1939.
Todtenhaupt in Germany in 1940. His process consisted of dissolving casein in an alkaline solution and extruding this solution through fine openings into a precipitating b a t h containing acid, formaldehyde, and alcohol. His process was unsuccessful commercially, principally because the individual fibers stuck together after extrusion and were brittle. Ferretti's patent application covering t h e production of the casein fiber known as Lanital was filed in Italy, August 28, 1935, and in other countries in August, 1936. I n November, 1935, the first sample of Lanital was presented to the Italian Government for examination and, shortly afterward, commercial production of the fiber was undertaken at the plant of the Snia Viscosa a t Cesano Maderno near Milan. I n 1936, 209,000 pounds were made a t this plant, and in 1937, 1,695,000 pounds. Ferretti's process is, in outline, the same as Todtenhaupt's. T h e outstanding novelty of t h e Ferretti process is t h a t t h e casein during manufacture is exposed t o the high acidity of pH 2.9, whereby, it is claimed, softness is imparted to t h e fiber a t t h e expense of some tensile strength. T h e term textile casein is used in Europe t o refer t o casein of this type. T h e casein is dissolved in alkali and t h e solution, after ripening, is extruded a t a definite viscosity into an acid bath containing formaldehyde. Various modifying agents may b e used in the casein solution and in the bath. The plant and machinery are essentially t h e same a s those used for t h e manufacture of viscose rayon, and this fact has had a tremendous influence on t h e rate of development of the casein fiber. A Dutch firm, known as AKU, is p r o ducing a casein fiber, called Lactofil, directly from skim milk without first isolating the d r y casein. Their process is said to be entirely different from t h a t of Ferretti, b u t details are not available. T h e Snia Viscosa has contracted for delivery of about 4,000,000 pounds of Dutch casein per year to its Italian plant and, in spite of rumors t o the contrary, it is stated on good authority t h a t no Lanital is being made in Holland. I t is reported t h a t rights to the Ferretti process have been acquired by companies in England, Canada, Poland, and Japan. A British company is said to be producing fiber in Denmark. T h e Japanese company has also acquired rights to a modification of t h e Ferretti process, whereby soybean protein may be used instead of casein. T h e European production of casein fiber in 1938 was probably between 6,000,000 a n d 8,000,000 pounds. Research on processes for making casein fiber has been undertaken in the United States by t h e laboratories of rayon producers a n d of dairy organizations. Undoubtedly many applications for patents are pending in t h e United States Patent 369
Office besides those for public-service patents m a d e by t h e authors. The only casein-fiber patent so far granted in this country was issued to us as No. 2,140,274 on December 13, 1938. T h e claims of this patent refer to a fiber comprising casein, salts of casein, and fat acids, and t o a fiber in which the aluminum salt of casein is specifically claimed a s a component. Our process uses any acidprecipitated casein of reasonably good quality, aluminum or other metal compounds being added to the alkaline casein solution to increase strength and waterresistance of the fiber. Fat acids are added to overcome the tendency t o brittleness or, in other words, to make the fibers flexible. T h e solution is extruded through a spinneret into a n acid bath containing formaldehyde and substances, such as salts or sugars, t o increase the osmotic pressure and thereby hasten the "settingu p " of t h e fiber. T h e fiber is then stretched and wound. Until developmental work has gone further, it will b e impracticable to make a proper comparison of our fiber with t h a t made commercially in Europe. Casein fiber is practically entirely casein, one pound of casein producing one pound of fiber. T h e modifying agents added in the manufacture add only a small amount t o its weight and the only losses are mechanical. T h e ultimate composition closely approximates that of wool, the chief difference being less sulfur. T h e fiber has a greater affinity for wool dyes than does wool itself. It is faintly yellow and has a fine kink. Unlike wool fiber, which has a scaly surface, casein fiber is smooth; consequently it cannot be felted, but, on t h e other hand, it does not shrink as much as wool. I t has a high resistance to creasing, similar to t h a t of wool and far exceeding t h a t of cotton or staple fiber. T h e softer grades have a n advantage over wool in t h a t the knitted fiber may be worn next to the most delicate skins that cannot tolerate knitted wool. T h e fineness of the fiber may be regulated to be constant at any value down to t h a t of the finest wool. T h e length of staple in any sample of wool varies between fairly wide limits, the shorter fibers being removed in the carding process. Casein fiber may be cut to uniform staple of any length. T h e earlier Lanital was reported to be about one fourth t o one sixth as strong as wool and its stretch was very slight. I t has more recently been claimed that Lanital has a much greater tensile strength and a stretch of 25 t o 35 per cent. When wet, casein fiber swells, and has greater stretch and breaks more easily than when dry. T h e disadvantages of casein fiber are similar to those which were characteristic of the early rayon—comparatively poor tensile strength, especially when wet. Its weakness when wet is particularly troublesome during the dyeing process.
J U N E 10, 1939
NEWS E D I T I O N
These characteristics tend t o limit their industrial use. The higher esters—butyl, amyl, lauryl, stearyl, etc.—are waterinsoluble and more stable. All the esters have utility a s solvents, plasticizers, and modifiers in lacquers, plastics, varnishes, cements, inks, etc. The alpha hydroxy group of these esters easily reacts with the acid anhydrides and with ketene t o form the corresponding esters. One example is the formation of methyl-alpha-acetoxy propionate OOCCH, CHsCHCOOCH* In this reaction the yield of the ester is practically quantitative. These esters are insoluble in water and may have utility a s solvents ; plasticizers, and modifiers in lacquers, plastics, varnishes, cements, inks, etc. By pyrolysis* these lactic acid di-esters can be converted into the corresponding acrylic' acid derivative. For example, the methyl-alpha-acetoxypropionate will yield monomelic methyl acrylate, H2C = CH.COOCHs, and acetic acid, CH»COOH. This monomeric material polymerizes readily with heat or peroxide catalysts into polymethyl acrylate. Laboratory re sults indicate that polymethyl acrylate can be produced as cheaply b y this procedure as by the cyanhydrin process now com mercially employed. The monomeric acrylates have a wide range of possible uses. They may be employed advantageously as an inter» polymerizing material with methacrylate esters, vinvl compounds, butadiene, and styrene. Several injection molding ma terials can be made by this interpolymerization, which will have improved molding properties and physical characteristics, a s well as cast rods, tubes, and sheets. They have more desirable physical character istics than those made with plasticizers and modifiers. ' Burns. Robert. Jones. D . T., and Ritchie, P. D . . J. Chem. Soe. Proc. 1988, Pert 1, 400-6.
371
When acrylic acid is polymerized t h e polymer separates a s a crustlike mass. Acrylic esters, on t h e other hand, gradu ally increase in viscosity and pass from a viscous liquid to a transparent and rubber like solid. These polyacrylic esters are insoluble i n water and alcohol, b u t they dissolve in the monomeric acrylic esters, aromatic solvents (benzene, toluene), ketones (acetone, methylethyIketone), and halogenated hydrocarbons (chloroform, ethylene dichloride). T h e polyacrylate esters are particularly valuable and prom ising because of their clarity, elasticity, toughness, ease of solubility, and stability to light. They have wide utility in the preparation of lacquers, varnishes, im pregnating compounds, and as supporting materials. All types of textile fabrics and paper may be coated or impregnated with out curing or use of special equipment. By this treatment fabrics and paper may be made moisture-resistant and imperme able t o gases. Lactic acid and its many derivatives will, in the near future, play an important role in the field of solvents, plasticizers, lacquers, plastics, inks, and as a n acidulent for beverages and foods. Specifications for A m e r i c a n Chemical Society Papers HE specifications for papers used for printing, covers, wrappers, and envel
T
opes were published in our N E W S EDITION
for May 10, 1938, on page 258. These specifications have now been revised in one or t w o particulars. These follow: Supercalendered book paper for INDUS TRIAL AND ENGINEERING CHEMISTRY.
B-lf. Oil penetration (castor oil method). Changed from 125 to 150 seconds to 100 to 150 seconds. Coated cover paper for INDUSTRIAL AND ENGINEERING
CHEMISTRY,
Industrial
and
Analytical Editions. B-3g. Color. Changed from white for Industrial Edition and light buff for Analyti cal Edition to white for both editions.
Coated cover paper for INDUSTRIAL AND E N G I N K K R I N G CmcMisTRY, N E W S E D I T I O N .
B-4c. Bursting strength. Average changed from not less than 30 points to not less than 20 points. B~4d. Folding endurance. Average, each direction, changed from not lees than 25 double folds to not less than 15 double folds. B-4g. Color changed from white to India. Cover paper for Journal of American Chemical Society and Chemical Abstract*. B-5b. Weight (25 X 38.500). Changed from 50 to 90 pounds. Methods of Sampling, Inspection, and Tests. CM. Wax used in wax test changed from No. 4 to No. 3 Dennison wax. The following is added: "The fading test is made by exposing the paper to carbon-arc light, in a Fade-Ometer apparatus, for β hours at 42° C." Oberiin-Holmes Dinner Boston
at
OB 25 years Harry N . Holmes has been t h e able chairman of the Depart F ment of Chemistry a t Oberlin. During this period over 300 men and women have majored or taken graduate work in chemis try at Oberlin. In grateful appreciation, his ex-students are sponsoring a special celebration in honor of Professor Holmes and his 25 years of untiring and fruitful efforts on behalf of his students, his col lege, and his profession. T h i s celebration will be held in Boston this fall at the time of the meeting of t h e AMERICAN CHEMICAL SOCIETY.
There will
be an Oberlin-Holmes dinner in t h e Ruby Room of Hotel Touraine on Tuesday, September 12, a t 6:30 P. M. Although t h e dinner is sponsored b y the former students of Professor Holmes it is not limited t o Oberlin graduates. Any and all friends of Professor Holmes w h o would like t o join in honoring him on this occasion will be welcome. I t will be helpful in making final ar rangements for t h e dinner if those w h o Plan t o attend will drop a card to Paul H. 'all, Williams College, Williamstown, Mass., as soon as possible. However, tickets will be o n sale a t t h e time of regis tration. Price, $1.65 per plate, including tips. Warren R. S m i t h
Retires
Wend of the current vear after 4 3 years of service a s head of the Depart ARREN R. SMITH will retire a t
U. S. D. A Photograph by Purdy
H. V. C l a b o r n switches o n t h e electric current that raises t o the desired point the temperature, indicated by ther mocouples, i n the furnace around the glass t u b e containing the a c e t y l a t e d methyl lactate
the
ment of Chemistry a t Lewis Institute, Chicago. Dr. Smith has been a member of
the
AMERICAN
CHEMICAL
SOCIETY
since 1897, and has been active in the affairs of t h e Chicago Section during his entire career. H e has served almost continuously for 42 years as a member of the Board of Directors of the Chicago Section. H e was Chairman in 1900 and 1907. Dr. Smith was born in Litchfield, Maine, in 1869, and received his A.B. degree from Bowdoin College in 1890. H e was a scholar in chemistry a t Clark University from 1891 t o 1892 and was the recipient of the first P h . D . in chemistry at t h e Uni versity of Chicago in 1894. Dr. Smith will live in Sutton's Bay, Mich. Under t h e auspices of t h e Chicago Sec tion
of
the
AMERICAN
CHEMICAL S O
CIETY and the Chemists' Club, the Warren R. Smith Dinner and Smoker will be held Monday, June 12, at 6:30 P. M. in the South Ball Room, Stevens Hotel, Chicago, 111.
