Many phenolic resins can readily be punched hot. The effect of heat is to provide energy necessary to overcome the secondary bond forces and permit polymer segments to relocate. O u r object was to reduce the energy necessary to punch a laminate successfully without appreciably reducing the ultimate strength of the material. I t was also our aim to obtain this effect as a function of the structure of the molecule itself, rather than by external additives. In phenolic resins, the principal secondary forces take the form of hydrogen bonds. The action of heat and plasticizers or either one individually is to destroy hydrogen bonds in a given system. An alternative to this situation is needed. We reasoned that because the bond strength for secondary bonds in general, and hydrogen bonds in particular, is a n inverse function of distance between polar centers, a n improvement might be realized by preventing the close approach of such centers in and between polymeric chains. The phenol molecule is planar. A substituent which is out of plane to the maximum extent should create the maximum interference to the close approach of the planes and thus, of the polar hydroxyl groups attached to these planes. The problem then becomes one of introducing steric hindrance. Steric hindrance is a function of size of the attached group. For alkyl groups, the greatest hindrance is caused by chain branching. Extended length of the
Condensed from a paper presented at the Symposium on Plasticized Thermosetting Systems, Division of Organic Coatings and Plastics Chemistry, 138th Meeting, ACS, New York City, September 1960. The complete article will be published in the SPE Journal.
chain beyond the second carbon atom is not effective because the chain is free to conform to any configuration and will extend itself beyond the area where steric hindrance is a factor. I t became important to prepare a resin from a phenol having a substituent which was branched a t the carbon atom attached to the phenyl ring. Suitable examples considered were tert-butylphenol, isopropylphenol, cyclohexylphenol, “octyl” (di-tert-butyl) phenol and phenylphenol. To interfere as little as possible with the normal primary valence bond structure, a meta-substituted phenol was indicated. The ortho and para positions then remain free for reaction with formaldehyde. Use of some ortho- or parasubstituted phenol as a co-reactant was not excluded, however. Among the suitable meta-substituted phenols, the most readily available in quantity was isopropylphenol. Examination of an atom model of a polymer
based on this reagent indicated that the adjacent methylene bridges in the resin chain would serve to keep the meta isopropyl gr0r.p oriented perpendicular to the plane of the aromatic ring. This compound therefore became the principal subject of our investigation. The findings seem to confirm the hypothesis just described. This made possible, for the first time, a cold punching grade laminate to which no extraneous substances were added. Self-plasticized. laminated materials for punching and postforming can be manufactured. They can be produced from polymers based on suitably substituted phenolic components, especially meta isopropylphenol. The use of any extraneous plasticizer compounds can be avoided. This work does not unequivocally prove the hypothesis upon which it was based, The observed improvement in the properties of the product may conceivably be due to some factor not considered by the authors. But the degree of success from a minimum of trial and error effort does constitute a strong endorsement of the inductive analytical approach. A successful product was demonstrated within three months from the time the problem was first proposed and the complete program involved less than one man-year effort.
RECEIVED for review October 21, 1960 ACCEPTEDDecember 21, 1960
Corrections O n page 228, reference (20) of the Literature Cited should read :
Correlation and Prediction of Binary Vapor-Liquid Equilibria In this article by Roger Gilmont, David Zudkevitch, and Donald F. Othmer [IND. ENG. CHEM.53, 223-8 (March 1961)], the following errors should be corrected. O n page 226, column 3. the last line of the fourth paragraph, the reference should be : Den0 and Berkheimer (20).
The last item of column 3 of the table should be:
T h e second item from the bottom of the table should read :
O n page 227, column 2, line 9 should read: [PI = parachor
(16, bO)
In the last line of column 2, the equation should read: [P,12f3kz,
5
d, ___
+
[P,12‘3k,%
[PJ213 [P,I2 / 3 w l l
The first equation in column 3 should read:
Halogens with active H
574
Detergents from Diglucosylurea
- 0.05
In Table 11, column I (Component Type), the third item from the bottom should read : Halogens without active H
(20) Deno, N. C., Berkheimer, H. E.; J . Chem. Eng. Data 5,1, No. 1 (January 1960).
INDUSTRIAL AND ENGINEERING CHEMISTRY
In this arricle by Paul R. Steyermark, Thomas R. Steadman, and Richard P. Germann [IND.ENG.CHEM.53, 212-14 (March 1961)], the caption under thr reaction scheme. page 214, should read : Transesterification of methyl esters of fatty acids gave diglwosylurea monoesters
O n page 214, column 1, beginning on line 5, the sentence should read: Its high activity may be due to iis ability to form negatively charged complexes with polyhydroxy compounds.
