USRE22402E

USRE22402E - Coatino composition containing

Info

Publication number: USRE22402E
Authority: US
Publication date: 1943-12-07

Description

Reiesued Dec. 7, 1943 COATING COMPOSITION CONTAINING POLYVINYL ACETATE METHYLAL Robert 0.. Swain, Riverside, and Pierrepont Adams. Glenbrook. Conn assignors to American Cyanarnid Company, New York, corporation of Maine No Drawing. Original No. 2.32am. dated August 10. 1943.8erlal No. 371,183. December as. 1940. Application tor reissue September 27, 1943, I

Serial No. 504.000

3 Claims. ('01. 260-42) This invention relates to coating compositions containing polyvinyl acetate methylai and melamine-formaldehyde resins.

An object of this invention is to improve the physical and chemical properties of coating compositions containing polyvinyl acetate methylal, e. g., chemical resistance such as acid resistance, heat resistance. etc.

Another object 01' this invention is to provide compositions containing polyvinyl acetate methylal and compatible proportions of compatible melamine-formaldehyde resins.

These and other obiects are attained by blending polyvinyl acetate methylal with not more than about 40% (total solids weight basis) of a melamine-formaldehyde resin which has been aikylated with a butyl alcohol or benzyl alcohol wherein the molal ratio of formaldehyde to mela- V mine is at least about 4:1. i

The following examples in which the proportions are in parts by weight are given by way of illustration and not in limitation.

The polyvinyl acetate methyial used in the ioliowingexamples is a product sold under the trade name oi l 'ormvar by Shawinigan Products Corporation. Polyvinyl acetate methylal resins may be produced by reactinsmlyvinyi acetate with formaldehyde asdescribed for example in the patent to Morrison et al., U. 8. sue No. 20,430.

trample 1 Parts Melamine-formaldehyde resin A".......... 10 Polyvinyl acetate metbylal (Pomvaf')---'. 80 A composition containing these is prepared by admixing parts of melamineiormaldehyde resin A solution resin) with mpartsoi'polyvinyi amatemethylalstockeolution" (containing 10% of polyvinyl acetate methylal and of dioxane); Films of the composition are applied to metal objects and baked at a temperature of about C. for about one-half hour. The product is a hard. transparent coating havind 800d iiim strength.

trample 2 g Parts Melamine-formaldehyde resin B"..- 25 Polyvinyl acetate metlwlal (l'brmvar) I5 Acompoeifloncontainingtbeceingredientsis prepar d radnuxinseopartsormeiamineposition ientltantiallyanhydrous appliedtometalobiectsaudbakedatatemper- I turewiiibeaboutiM-m',

ature of about 135' C. for about one-half hour.

A clear, tough film is formed.

Example 3 7 Parts Melamine-formaldehyde resin "C" 10 Polyvinyl acetate methylal ("Formvar) 90 Example 4 4 Parts Melamine-formaldehyde resin D 25 Polyvinyl acetate methylal ("Formvar") 75 A composition containing these ingredients is prepared by admixing 50 parts of melamineformaldehyde resin D solution (50% resin) and 750 parts of "polyvinyl acetate methylal stock solution. Films of the composition are applied to metal objects and baked at a temperature 0! about C. for about one-half hour.

' A water-white illm having good chemical properties is iormed. Preparation of melamine-formaldehyde resin "A" Parts Melamine (1 mo1)... 128 Formalin (4 mols) (37% formaldehyde in water Thismixtureisplacedinarefluxapparatuswhich ieprovidedwithaandasuitablewater trapflarcmghwhich the reflux condensatepasscs onitsreturntothereactionchamberandinwhich the essentially aqueous traction oi the condensatemaybeeeparatedimmtheessentiallynonaqueomiractionandmeansisprovidedsothat theiormertractionmaybe drawn'oiliidesirable. 'rhereactionmixtureisrenuxedatatemperature oiabout 91-03 C. at atmosphericpres sureiorG-flhours. 'I'hewaterisremovedby distlllationiromthereactionminture duringflaereiiuxoperationpreierahly atterabontfl-ohomshaveelapecdandthewater so removed is separated iron the reflux eondemateinthewatertrap. nm'lng thedisflllapi'alureillowered sufllciently to reduce the vapor temperature to about 85-90 C. and the resin solution is concentrated to about 60-70% solids by vacuum distillation. The resulting resin solution may be diluted to about 50% solids with any desired solvent or diluent, e. g., xylene.

Preparation of melamineformaldehyde resin "B" Parts Melamine (1 mol) 126 Formalin (5 mols) (37% formaldehyde in water) 405.5 n-Butanol 440 This mixture is placed in a reflux apparatus which is provided with a condenser and a suitable water trap through which the refiux condensate passes on its return to the reaction chamber and in which the essentially aqueous fraction of the condensate may be separated from the essentially nonaqueous fraction and means is provided so that the former fraction may be drawn on if desirable. The reaction mixture is refluxed at a temperature of about 91-93 C. at atmospheric pressure for 6-12 hours. The water is removed by azeotropic distillation from the reaction mixture during the reflux operation beginning preferably after about 2-5 hours have elapsed and the water so removed is separated from the reflux condensate in the water trap. During the distillation about 550 additional parts of butanol are added gradually. When the reflux condensate is substantially anhydrous the vapor temperature Will be about 100-105" C. The pressure is lowered sufficiently to reduce the vapor temperature to about 85-90 C. and the resin solution is concentrated to about 60-70% solids by vacuum distillation. The resulting resin solution may be diluted to about 50% solids with any desired solvent or diluent. e. g., xylene.

Preparation of malamine-formaldehyde This mixture is placed in a reflux apparatus which is provided with a condenser and a suitable water trap through which the reflux condensate passes on its return to the reaction chamber and in which the essentially aqueous fraction of the condensate may be separated from the essentially non-aqueous fraction and means is provided so that the former traction may be drawn 0!! if desirable. The reaction mixture is refluxed at a temperature of about 91-93 C. at atmospheric pressure for 6-12 hours. The water is removed by azeotropic distillation from reaction mixture during the reflux operation beginning preferably after about 2-5 hours have elapsed and the water so removed is separated from the reflux condensate in the water trap. During the distillation about 550 additional parts of butanol are added gradually. When the reflux condensate is substantially anhydrous the vapor temperature will be about 100-105C. The pressure is lowered sumeiently to reduce the vapor temperature to about 85-90 C. and the resin solution is concentrated to about 60-70% solids by vacuum distillation. The resulting resin solution may be diluted to about 50% solids with any desired solvent or diluent. e. 8., xylene.

Preparation 0! melamine-formaldehyde resin "D Parts Melamine (1 mol) 126 Formalin (5 mols) (37% formaldehyde in water) 405.5 Benzyl alcohol 600 means is provided so that the former fraction may be drawn off if desirable. The reaction mixture is refluxed at a temperature of about 93-95-C. at atmospheric pressure for 6-12 hours. The water is removed by azcotropic distillation from the reaction mixture during the reflux operation beginning preferably after about 2-5 hours have elapsed and the water so removed is separated from the reflux condensate in the water trap. When the reflux condensate is substantially anhydrous the vapor temperature will be about IOU-105 C. The pressure is lowered sufficiently to reduce the vapor temperature to about 95-90 C. and the resin solution is concentrated to about 60-70% solids by vacuum distillation. The resulting resin solution may be diluted to about 50% solids with any desired solvent or diluent, e. g., xylene.

Alkylated melamine-formaldehyde resins may be produced in accordance with the procedures outlined above, as well'as in any other suitable manner. Aqueous syrups of melamine-formaldehyde resins may be first produced and then alkylated either simultaneously with dehydration or subsequent to dehydration. Generally the simultaneous condensation of melamine, formaldehyde and a suitable alcohol is used because of convenience. The condensation may be carried out either with or without an acid catalyst and in some instances basic catalysts may desirably be utilized.

The melamine formaldehyde resins vary slightly according to minor variations of control during their production and in some instances small proportions of a suitable solvent material, e. g., dioxane, acetone, acetone-alcohol mixtures, the monoethyl ether of ethylene glycol (Cellosolve"), etc., may be added to the original solutions of polyvinyl acetate methylal and melamine-formaldehyde resin in order to produce perfectly clear solutions if such solutions are not originally obtained.

While formaldehyde has been used in the previous examples, it will be obvious that other aldehydes such as the various polymers of formaldehyde, e. g., paraformaldehyde, or substances which yield formaldehyde may be used in place 01' part or all of the formaldehyde.

As indicated by the above examples polyvinyl acetate methylal has been found to be compatible with not more than about 40% oi a melaminelformaldehyde resin alkylated with butyl and benzyl alcohols, wherein the molal ratio or formaldehyde to melamine is at least about 4:1. Melamine-formaldehyde resins which have been alkylated with hexyl and octyl alcohols are compatible with polyvinyl acetate methylal in proportions up to about 10% and butylated melamine-formaldehyde resins wherein the molal ratio of formaldehyde to melamine is 5:1 are compatible in proportions as high as about 60%. While higher ratios of formaldehyde to melamine than 6:1 may be used, it is generally undesirable inasmuch as formaldehyde is lost during the curing so that usually the product in its cured condition does not contain more than about 6 mols of formaldehyde to 1 mol of melamine. The percentage composition in each instance in this paragraph is on a total solids weight basis.'

The melamine-formaldehyde resins may be alkylated with benzyl alcohol and with n-butyl alcohol as in the above examples or they may be alkylated with other butyl alcohols or mixtures of any oi these alcohols. The term alkylated melamine-formaldehyde resin is intended to denote compositions which are reacted with an alcohol.

Our products may be plasticized with a wide variety of materials such as the alkyl phthalates. tricresyl phosphate, fatty acid amides, various alkyd'resins, etc.

Various fillers, pigments, dyes and lakes may be added to our compositions, e. g., lithopone,

zinc oxide, titanium oxide, ferric oxide, Prussian trocellulose, etc.. as well as in varnishes, especially drying oil varnishes, such as those from tung oil, linseed oil, etc. I

Our products may be used in lacquers and other coating compositions including enamels, paints, etc. They ar particularly suitable for wire coating and for the production of insulating materials. Our mixtures may be. applied to paper, cloth and the'like and the resulting product may be used for a wide variety of purposes. Films of our materials may be used in the production of photographic films. Our. compositions are also suitable as adhesives such as for shatterprooi glass and they may also be used in the manufacture of filaments, sheets, etc.

The melamine-formaldehyde resins improve the chemical resistance such as acid resistance, of polyvinyl acetate methylal resins and our mixtures have improved color retention upon heating. Another important improvement in polyvinyl acetate methylal resins which is achieved by the incorporation of melamine-formaldehyde resins is the reduction in the thermoplastlcity thereof. In some instances the polyvinyl acetate methylal resin may exhibit a toughening effect upon the melamine-formaldehyde resins.

The term compatibie" as used herein is intended to denote compositions, films of which are clear and homogeneous after baking.

Obviously many modifications and variations in the processes and compositions described above may be made without departing from the spiri and scope of the invention as defined in the appended claims. We claim: 1. A coating composition containing polyvinyl 2s acetate methylai and a melamine-formaldehyde resin which has been heated until reacted with an alcohol selected from the group consisting of butyl alcohols and benzyl alcohol, wherein the molal ratio of formaldehyde to melamine i at least about 4:1 and wherein the weight ratio of polyvinyl acetate methylal to melamine resin is at least about 3 :2.

2. A coating composition containing polyvinyl acetate methylal and a melamine-formaldehyde resin which has been heated until reacted with n-butyl alcohol, wherein the molal ratio of formaldehyde to melamine is at least about 4:1 and wherein the weight ratio or polyvinyl acetate methylal to melamine resin is at least about 8:2.

3. A coating composition containing P lyvinyl acetate methylal and a melamine-formaldehyde resin which has been heated until reacted with benzyl alcohol, wherein the 'molal ratio or formaldehyde to melamine is at least about 4:1 and wherein the weight ratio of polyvinyl acetate methylal to melamine resin is at least about 3:2.

ROBERT C. SWAIN. PIERREPONT ADAMS;

CERTIFICATE orflcomcrrqn. {Reieeue 1m. 22,1;02. Decepber 7,- 191 ROBERT 0. mm, 21' AL.

It is hereby certified thet error appears in the printed epeciricetion or the above numbered p tent requiring correction ae rollers: Page 2, eec- 0nd column, line 2a, for "95-90 c.'-rua'--e5-9o c.--; and that the "in Letters Petent be reed with this correction therein that the heme oontom to the record of the cue in the Patent Office.

Signed and .154 um- 8th 'day or February, A. 1). 191m.

Henry Ven" Arednle, (8011) Acting commissioner ot retegteb