Патент USA US2404353код для вставки
Patented July 25, i . I ' _ v . UNITED STATES PATENT oF-Fice REMOVABLE COATIHG COMPOSITION Harry K. Ash, Cincinnati, Ohio, assignor to Inter chemical Corporation, New York, N. Y., a cor . pcratlon of Ohio No Drawing. Application July 28, 1943, ~ Serial No. 496,473 , 5 Claims. r (01. ice-189) ' p l 2 I‘ This invention aims to provide a temporary protective coating for soft plastic surfaces, char- cizing my ethyl cellulose above about 50%, and by ' choice of ingredients, and by pigmentation. ' .acterized by the ability to strip cleanly‘ from the A third important consideration in my new ' surface even after a prolonged period of time. compositions stems from my discovery of the fact In the aircraft industry in particular, sheets i 5 that a stripping lacquer,.in order to be satisfac of thermoplastics such as “Plexiglas" and tory, must deposit a film of atleast about 1 mil “Lucite" (methacrylate polymers) and cellulose in dry thickness; thinner ?lms do not strip prop acetate, are used as window materials. They are erly no matter how strong the ?lm is. This moss-1 I generally formed to shape by heat of the order of sity for a thick film in o'necoat requires high 250 to 350°‘ F., combined with pressure. It is 10 solids in the lacquer. High solids areordina'rily essential that they be protected against scratchattained by the use of low: viscosity cellulose de ing during the forming operation, and during rivative, combined with large quantities of plasti- 7 handling before assembly, as scratches interfere - cizer or resin. Such normal high solids lacquers with vision; removal of scratches by bu?ing may are, however, not useable as stripping lacquers, cause distortion by variation in thickness. Hence, 16 because of their formulation, being generally too elaborate precautions have been used to protect adherent, as well as either soft (too much plasti the sheets. Because paper and similar protectcizer) or-brittle (too much resin) for proper strip ing devices have been hard to handle, investlgaping. In order to get the necessary highvsolids, _ tors have attempted to deposit strippable ?lms on I use viscosities much above those commonly ap the plastic. Poor stripping, sticking in the molds, 20 plied. I ?nd a minimum viscosity of 50 seconds and deleterious action on the plastic, have contributed to the failure oi’ the known stripping lacquers. ‘I > in, a. No. 4 Ford cup‘ at 70° F. to' be essential in producing the desired ?lm. thickness. Spraying . ' lacquers may go up to 100 seconds viscosity, I have discovered how to produce lacquers brushing lacquers up to 200 seconds. Thesevis ‘which produce satisfactory strippable protective 25 cosities compare with the approximate 20 second ?lms on thermoplastic sheets. These lacquers viscosities preferred in ordinary spraying lacquers. consist essentially of solutions of low viscosity - Typical examples of my. invention are the, £01 (10 centipoise) ethyl cellulose of standard ethoxy lowing: content (ca. 47%) in solvents preferably consist- ing of alcohols and petroleum hydrocarbons, and 30 Ex‘Tml-e 1' Gem,v ‘ 0m 41 time f cizer, based upon the weight of the ethyl cellulose.~ Ethyl >_¢e11\110$e-—10, centipoise Standard vIf desired, a stripping agent (such as carbitol ethOXY ‘citrate oi’ Alumil'eaf) may be incorporated in the composition. 7 " uza?lm .. ' Parts by weight . plasticized with from about 25% to 50% ‘o! plasti-i _ . 12-00 Dow plasticizer N0- 6 (dim-Kenn) mono , 35 ' phenyl phosphate) _________________ .._'_ The most important consideration in a strip- Neville’s P- H- 0. oil (viscous cumaronee _ .ping lacquer forthermoplastics lsthat the lacquer . 2.00 v ; indene Phenol condensate) -----'- ---- -- ‘4-00 ‘have no e?ect on-the plastic. A prime considera- n-Butyl alcohol _.. ................ -‘._-..__ 21.00 tion is. solvent; it is important that the solvent ' fl‘roluo? (Petroleum distillate of toluene in the lacquer be anon-solvent for the thermo- 40 evaporation rate) ---,----_- ----------- -- 61 00 plastic to be used. For universal application, I ’ . Viscosity 105 seconds in a No. 4 Ford cup at i have found a mixture of petroleum naphthas and 70°‘ F. ' ‘I ‘lower water-immiscible volatile aliphatic alco- This may be used on both acetate and meth-s - hols (e'. g. butyl, amyl, hexyl) , but not below butyl scl'ylate sheets. (no ethyl or methyl) to be most desirable. Where 4'5 - Example 2 cellulose acetate is to be the base material, other _ - ' ' Parts by weight . hydrocarbons, such as the coal-tar distillates, may , be used; but Iprefer to use the petroleum naph- mgtsgoxgenmose 1° can-um tha-alcohol; combination for all purposes. Another important consideration is the the 50 Dow plastlmr No 8 - standard 12 5o ' _ v 4.00 nun who --_-:__::::::::-::::::::3:- 10.00 ?lm oi’ stripping lacquer shall not be as thermoplastic as the. sheet it. protects,,_ else it will stick. n.Buty] alcohol ____._ __________________ __ 153° 'Toiuol substitute _____ __'____; ___________ __ 35,50 in the mold, or fuse to the sheet, during the tomb‘ Solvent naphtha __________________ _______ 21.00 ing operation. I obtain this result by notplasti- 65 Alumileaf (stripping agent) __________....__. 2.00 2,404,353 . ' This formulation ‘cannot be used on methacry late plastics; it is highly useful on cellulose acetate. ‘ ' - ‘ " Above paste ‘ . Parts by weight ' 14.97 Ethyl cellulose 10 centipoise standard ethoilryv 8.85 - ' Viscosity‘66 seconds in a No. 4 Ford cup at‘ Troluoil 70° F. ‘ -' 4 l ' ‘ 54.82 Butanol __________________________ ...'._>..-_ 17.9’! Example 3-Colored1aaquer ‘ Hercolyn ' - 2.60 Parts by weight Ethyl cellulose. 10 -centipoise ethoxy Zone nil Dye solution ~ .27 standard ‘ ‘ 12.50‘ 10 I Viscosity 60 seconds in a No. 4 Ford cup at 70° F. 4.00 The examples may be multiplied inde?nitely Ethyl alcohol___;v ______________________ __ 10.00 without departing from the scope oi’ the inven ‘ - Dow plasticizer No. 6___________ .._,_____'..__ _ tion, which is de?ned in the claims. n-Butyl alcohol _______________________ __ 15.00 Toluol substitutea _____ __'_ ______________ .._ 35.20‘ 21.00‘ 15 Solvent naphtha Carbitol citrate_~_ ______________________ __ 1. A lacquer which will deposit a permanently - single application, which ?lm can‘ be stripped, from a'sheet of cellulose acetate thermoplastic fI'his formula is similar to Example 2, and its ' , . strippable ?lm of at~least 1 mil thickness in a 2.00 nee dye solution (Sairanine A)..___‘_.._..__ _ .30‘ use is similarly restricted. . I claim: without injury thereto, consisting essentially of 20 a binder and a solvent, the binder consisting es- - ' ‘ sentially of ethyl cellulose of 10 centipoise- vis cosity and approximately‘ 47% ethoxy content, plasticized with from about 25 to 50% of its weight of plasticizer, the solvent consisting en iii-Viscosity 66 seconds in a No. 4'Ford cup at I have-also found that a small amount oi' pig-Y _ ‘ment in the formula. improves the ability of the ‘?lm to withstand drawing and forming. This 25 tirely of alcohols and hydrocarbons, the lacquer being further characterized by a viscosity between pigmentation‘also has the e?ect of producing a 50 and 200 seconds in a No. 4 Ford cup at 70° F. ?lm which can be marked on with'a pencil, etc., .2./ The lacquer of claim 1, in which a stripping tor layout purposes. I may use a small amount agent-is included in amount varying from about ' ('from about 1 to 5%) of an'inert extender pig-j 30 three tenths of a percent to about three‘ percent; ment such as silica aerogel, calcium sulfate, cal 3. The lacquer of claim .1, in which a small .ciurn carbonate, barytes, clay, ‘ earths, magnesium silicate, or other known inerts. A typical example oi.’ such a- material, which is‘ amount of coloring matter is incorporated. 4. Alacquer which will deposit a permanently strlppable ?lm of at least 1 mil thickness in ‘a suitable for both methacrylate and acetate plas single spray application to methyl methacrylate plastic sheeting, consisting essentially-oi’ a binder ' tics is the following: diatomaceous , ' l and a solvent, the binder consisting essentially of - . I _ 4 . Example 4 ' , Silica aerogel Surfer - ethyl cellulose of 10*ceritipoise viscosity and ap _ proximately 47 %, ethoxy content, plasticized with Parts by weight 8.20 40 .trom about 25 to 50%’ of'its weight of plasticizer, ‘ the solvent consisting entirely of alcohols and hy 2.35 -..- drocanbons, the lacquer being further character Ethyl cellulose 10 centipoise standard ized by a viscosity between 50 and 100 seconds in a No. 4 Ford cup at 70° F. Dow plasticizer No; 6 _____ __' ______ .._,_'____ 1.30 45 5. A lacquer as described in claim 4, having the ri-Butanol , ' > ' 20.30‘ ‘7 ethoxy __-_ ‘7.25 Troluoil'____.>; ___________ __; __________ __ 60.60 ' additional property of resistance to die-forming H - The above is ground to a paste of suitable ?ne-l of claim 4 and from 1 to 5% of an inert extender ness, and is made intoxa ?nishedJacquer as . follows: ‘Y and ability to be marked, consisting of the lacquer 50 pigment dispersedtherein. - ' , ‘ , Y - HARRY K. ASH.