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New method of metal-to-thermoplastics bonding
Mar., I963 .]
CURRENT ToPIcs
New Method of Metal-to-Thermoplastics Bonding.--A new method of
263
form a physical bond with the thermoplastic. One end of the stearic acid bonding metals to thermoplastics formed aluminum stearate with the with a single layer of molecules as an metal plate; the other end became adhesive has been developed at Bell immersed in the polyethylene. These Telephone Laboratories. A bond so reactions account for the permanence formed between aluminum and poly- of the bond. To prepare the monolayer, Dr. ethylene is more permanent than any previously achieved and more resist- Schonhorn dissolved the stearic acid ant to tearing and pulling than the in benzene and spread the solution on water contained in a long trough. plastic itself. Up to now it has not been possible The volatile benzene evaporated and to form a direct bond between left a monolayer of stearic acid on the metals and polyethylene that will surface. He then used a float to push withstand mechanical stress if the these molecules close together. The humidity and temperature are high. hydrocarbon portion of the stearic Dr. Harold Schonhorn reports that acid is insoluble in water and tends to an aluminum-polyethylene-aluminum stand up straight when the film is bond, prepared by this method, has compressed. The acid portion disheld up for months under 600 psi. solves and lies just below the surface of tensile-shear stress at 100 per cent of the water. relative humidity and 80-120 F. Next, Dr. Schonhorn lowered an Dr. Schonhorn bonded these mate- aluminum plate through the monorials together with a monolayer of layer into a rectangular well at one end of the trough. During its descent stearic acid (CH3 (CH2) 16COOH). His method could find a number of the plate contacted the hydrocarbon applications in the electronics in- portion of the monolayer. Since this dustry. For example, a permanent part of the stearic acid molecule has bond between polyethylene insulators no affinity for aluminum, it did not and copper conductors could improve adhere to the plate. But when Dr. the mechanical properties of telephone Schonhorn raised the aluminum plate cables or increase the reliability of a it contacted the acid portion of the printed circuit. molecule to form a chemical bond. Dr. Schonhorn applied a technique The molecules adhered to the sides of developed in 1935 by Irving Langmuir the plate so that the hydrocarbon part and Katherine Blodgett and used faced out. since by chemists to study the strucOnce coated with such a monolayer, ture of single molecules. The tech- metals cannot absorb appreciable nique, which enables scientists to amounts of water or gases from the deposit a single layer of molecules atmosphere and can be stored for ("mouolayer") of a substance on a months before they are bonded to water surface, had never been applied thermoplastics. Unprotected metals before to adhesion. become contaminate~ by the atmosIf certain long chain hydrocarbon phere in a short time and must be acids are used as the monolayer, Dr. specially treated before they are suitSchonhorn demonstrated in his ex- able for bonding. periment, the acid end of the molecule In the final stage of his experiment, will form a chemical bond with the Dr. Schonhorn melted polyethylene metal and the hydrocarbon part will onto the monolayer. The hydro-
264
CUI~RENT TOVlCS
carbon portion of the stearic acid molecule became immersed in the polyethylene, itself a long chain hydrocarbon. This completed the bond. Ordinarily, stearic acid and other long chain hydrocarbon acids are used in thicker films to release parts from molds. However, so long as these compounds are used in a single molecular layer, they act as adhesives. Dr. Schonhorn has also bonded aluminum, stainless steel and copper to polypropylene and polystyrene using octadecylamine and octadecylphosphonate. By varying the adhesive, he can, in principle, bond other thermoplastics and metals together.
Experimental Machine "Reads" Many Styles of Printing.--An experimental machine that automatically "reads" a wide variety of printed type styles and sizes has been demonstrated by International Business Machines Corporation. The machine converts printed or typewritten information into electrical signals that can be fed into a digital computer for processing. Scientists at the Thomas J. Watson Research Center in Yorktown, N. Y., report that the new technique permits machine recognition of printing of variable quality and alignment. This includes typewritten carbon copies and other kinds of office copies. The experimental machine, called a "multifont optical character reader," can also accept any size of type in English, Russian and other alphabets. IBM emphasized that the experimental machine was developed for research in automatic character recognition, and that in its present form it is not suitable for commercial production. At present the maximum reading speed of the system is 50 characters
[J. F. I.
per second. This limit is primarily determined by the relatively slow electronic circuitry of the logical unit Used in the present experimental model. The same basic system employing a more advanced logical unit should be capable of reading hundreds of characters per second. Dr. Edward N. Adams, Director of Engineering Science at the IBM Research Center, cited two characteris. tics of the system as particularly significant for character recognition. "First," he said, "the machine determines for itself the information it requires for distinguishing one character from another. Second, by the use of stored information, the machine automatically adjusts itself to recognize different type fonts. The system thus demonstrates both adaptive behavior and self-design." The machine's ability to determine its own criteria for distinguishing among characters is demonstrated by the fact that it can read samples of type style for which it has not previously been adjusted. Once the machine has taught itself to recognize a new type style, it can store its recognition criteria on magnetic tape. When the same type style is encountered again, the machine can retrieve this information from the tape. The process is not automatic in the present experimental system, but it could be made automatic if development were carried further. Under favorable conditions, the system has operated with a low error rate, but it is not planned to make modifications that would be required in the present experimental system to achieve the very low error rate necessary for practical applications. According to Dr. Adams, if a wellengineered machine were built using the principles of the experimental system, it should have an error rate on
CURRENT ToPIcs
New Method of Metal-to-Thermoplastics Bonding.--A new method of
263
form a physical bond with the thermoplastic. One end of the stearic acid bonding metals to thermoplastics formed aluminum stearate with the with a single layer of molecules as an metal plate; the other end became adhesive has been developed at Bell immersed in the polyethylene. These Telephone Laboratories. A bond so reactions account for the permanence formed between aluminum and poly- of the bond. To prepare the monolayer, Dr. ethylene is more permanent than any previously achieved and more resist- Schonhorn dissolved the stearic acid ant to tearing and pulling than the in benzene and spread the solution on water contained in a long trough. plastic itself. Up to now it has not been possible The volatile benzene evaporated and to form a direct bond between left a monolayer of stearic acid on the metals and polyethylene that will surface. He then used a float to push withstand mechanical stress if the these molecules close together. The humidity and temperature are high. hydrocarbon portion of the stearic Dr. Harold Schonhorn reports that acid is insoluble in water and tends to an aluminum-polyethylene-aluminum stand up straight when the film is bond, prepared by this method, has compressed. The acid portion disheld up for months under 600 psi. solves and lies just below the surface of tensile-shear stress at 100 per cent of the water. relative humidity and 80-120 F. Next, Dr. Schonhorn lowered an Dr. Schonhorn bonded these mate- aluminum plate through the monorials together with a monolayer of layer into a rectangular well at one end of the trough. During its descent stearic acid (CH3 (CH2) 16COOH). His method could find a number of the plate contacted the hydrocarbon applications in the electronics in- portion of the monolayer. Since this dustry. For example, a permanent part of the stearic acid molecule has bond between polyethylene insulators no affinity for aluminum, it did not and copper conductors could improve adhere to the plate. But when Dr. the mechanical properties of telephone Schonhorn raised the aluminum plate cables or increase the reliability of a it contacted the acid portion of the printed circuit. molecule to form a chemical bond. Dr. Schonhorn applied a technique The molecules adhered to the sides of developed in 1935 by Irving Langmuir the plate so that the hydrocarbon part and Katherine Blodgett and used faced out. since by chemists to study the strucOnce coated with such a monolayer, ture of single molecules. The tech- metals cannot absorb appreciable nique, which enables scientists to amounts of water or gases from the deposit a single layer of molecules atmosphere and can be stored for ("mouolayer") of a substance on a months before they are bonded to water surface, had never been applied thermoplastics. Unprotected metals before to adhesion. become contaminate~ by the atmosIf certain long chain hydrocarbon phere in a short time and must be acids are used as the monolayer, Dr. specially treated before they are suitSchonhorn demonstrated in his ex- able for bonding. periment, the acid end of the molecule In the final stage of his experiment, will form a chemical bond with the Dr. Schonhorn melted polyethylene metal and the hydrocarbon part will onto the monolayer. The hydro-
264
CUI~RENT TOVlCS
carbon portion of the stearic acid molecule became immersed in the polyethylene, itself a long chain hydrocarbon. This completed the bond. Ordinarily, stearic acid and other long chain hydrocarbon acids are used in thicker films to release parts from molds. However, so long as these compounds are used in a single molecular layer, they act as adhesives. Dr. Schonhorn has also bonded aluminum, stainless steel and copper to polypropylene and polystyrene using octadecylamine and octadecylphosphonate. By varying the adhesive, he can, in principle, bond other thermoplastics and metals together.
Experimental Machine "Reads" Many Styles of Printing.--An experimental machine that automatically "reads" a wide variety of printed type styles and sizes has been demonstrated by International Business Machines Corporation. The machine converts printed or typewritten information into electrical signals that can be fed into a digital computer for processing. Scientists at the Thomas J. Watson Research Center in Yorktown, N. Y., report that the new technique permits machine recognition of printing of variable quality and alignment. This includes typewritten carbon copies and other kinds of office copies. The experimental machine, called a "multifont optical character reader," can also accept any size of type in English, Russian and other alphabets. IBM emphasized that the experimental machine was developed for research in automatic character recognition, and that in its present form it is not suitable for commercial production. At present the maximum reading speed of the system is 50 characters
[J. F. I.
per second. This limit is primarily determined by the relatively slow electronic circuitry of the logical unit Used in the present experimental model. The same basic system employing a more advanced logical unit should be capable of reading hundreds of characters per second. Dr. Edward N. Adams, Director of Engineering Science at the IBM Research Center, cited two characteris. tics of the system as particularly significant for character recognition. "First," he said, "the machine determines for itself the information it requires for distinguishing one character from another. Second, by the use of stored information, the machine automatically adjusts itself to recognize different type fonts. The system thus demonstrates both adaptive behavior and self-design." The machine's ability to determine its own criteria for distinguishing among characters is demonstrated by the fact that it can read samples of type style for which it has not previously been adjusted. Once the machine has taught itself to recognize a new type style, it can store its recognition criteria on magnetic tape. When the same type style is encountered again, the machine can retrieve this information from the tape. The process is not automatic in the present experimental system, but it could be made automatic if development were carried further. Under favorable conditions, the system has operated with a low error rate, but it is not planned to make modifications that would be required in the present experimental system to achieve the very low error rate necessary for practical applications. According to Dr. Adams, if a wellengineered machine were built using the principles of the experimental system, it should have an error rate on