US2370648A - Noncaking flatting agent - Google Patents

Description

Patented Mar. 6, 1945 NON CAKING FLATTIN G AGENT Earl K. Fischer, Long Island City, N. Y., asslgnor to Interchemical Corporation, New York, N. Y., a corporation of hio No Drawing.

Application December 12, 1941, Serial No. 422,683

4 Claims. (Cl. 260-71) This invention relates to the preparation .of dull or flat coating compositions containing as the flatting agent insoluble carbamide-aldehyde resin powders, and it is particularly directed to a method for treating these powders so as to make them easily dispersible.

It is often desired to obtain finishes which are more or less matte, either for the decorative or for the frequently desirable optical effect. The trade in general has adopted, as flatting agents, Powders which are relatively insoluble in the coating compositions and which can be dispersed therein to yield films which are dull or fiat because of the fact that the insoluble fiatting agent scatters the incident light. Where a fiatting agent is desired which may be incorporated in any of the standard coating compositions in large quantity without materially detracting from physical properties of the finished film, powders of the insoluble carbamide-aldehyde resins have been developed, particularly the insoluble ureaformaldehyde resins, and these form the subject matter of co-pending application Serial No. 407,623,'filed August 20, 1941, in the name of Loy S. Engle.

Although these carbamide-aldehyde resin fiatting agents (hereinafter referred to as urea fiatting agents) are outstanding in their fia'tting abilities and minimize the efiects of abrasion, they are sometimes difficult to disperse perma neatly in the conventional vehicles. When they have been dispersed in the vehicles and have been allowed to stand, as in storage, they settle out in the form of fairly hard cakes which are not redispersible without regrinding, and which do not give the expected flatting on application.

This invention provides a treatment whereby these urea resin flatting agents may settle out, if at all, in the form of soft or curdy deposits which are easily redispersed in the vehicle by simple stirring. The invention also includes the treated urea resin flatting agents and finishing compositions containing the same.

I have found that the urea fiatting agents will not settle out into hard cakes after dispersion 4 in conventional vehicles if they are in a fiocculated condition. The resin particles may be treated prior to, or during, incorporation in the vehicle in a way which causes them to flocculate, and this treatment consists in depositing an extremely fine film of a polar liquid on the surfaces of the particles. This is most easily done by bringing the resin particles into intimate contact with the polar liquid prior to introduction or mealy mass and to stir his mass intn the vehicle.

Although all polar liquidswill have some flocculating effect on the resin particles, the more highly polar liquids are more effective, provided, of course, the liquid is not so chemically reactive that it will attack the particles themselves or materially alter their physical and chemical properties. Also, for most coating formulations it is desirable that the flocculating liquid be sufficiently volatile that it will be expelled from the coating during baking or other drying'operations. I have found that the polar liquids which are most satisfactory for this purpose are those which may be broadly classed as polyhydroxy compounds, and three especially satisfactory compounds of this class are ethylene glycol, glycerol and triethanolamine. Water can be used in some cases, but usually it is necessary for other reasons to avoid the presence of much water in the finishing composition. Of course, mixtures of two or more of these liquids may be used.

A comparison was made between the settling characteristics and re-dispersibility of an insoluble urea-formaldehyde powder in three different types of finish, both when treated with various polar liquids and when untreated. The urea resin powder was ground on a three-roll mill with an equal weight of the polar liquid, and the paste thus obtained was stirred into the finish and allowed to settle by standing for 20 days. The three finishes were as follows:

(A) A varnish containing an oil soluble phenolic resin, China-wood oil varnish and 50% hydrocarbon solvent.

(B) A urea-alkyd baking finish containing 65% solvent comprising toluene and butanol.

(C) A nitrocellulose lacquer base thinned with ester solvents to spraying consistency.

In finish A the untreated resin/powder settled into a firm gel which was very difliculty redispersible. On the other hand, the resin powder which had been wet with polar liquids, especially hydroxy compounds (e. g., water, ethylene glycol,

glycerol, butanol, octanol, diethanolamine, triethanolamine, ethyl lactate, etc.) settled into soft masses which were readily redispersed by simple stirring.

In finish B the untreated resin powder settled into a tough solid which could not be redispersed by stirring, whereas the resin powder which had been wet with a polar liquid could be redispersed.

However, with this finish not all of the polar into the vehicle, and it is preferred to grind the liquids were equally satisfactory. The monopowder and liquid on a roll mill to form a paste hydroxy compounds which were so successful with finish A permitted the powder to settle into rather compact resin cakes which required vigorous stirring for redispersion. n the other hand, the polyhydroxy compounds, such as ethylene glycol, glycerol and the polyalkylolamines (e. g., the diand tri-ethanolamines) yielded soft resin cakes which were easily redispersed.

In finish C the untreated resin powder settled to a tough solid in the same way as with finish B. However, the resin powders which had been wet with polar liquids were not all easily redispersed. Those powders which were wet with liquids having less than two hydroxyl groups settled into such hard and compact cakes in this finish that they were redispersed only with difii- I of which are described in the following examples 0 by way of illustration.

Example 1-(Matte-finish black baking enamel) A urea. resin fiatting agent is thoroughly wet with an equalweight of ethylene glycol by grinding on a three-roll mill. Four passes at a relatively loose roll setting provide the necessary wetting. A matte-finish, synthetic black baking enamel may be formulated as follows:

' Per cent by weight Carbon black, high color 1.5 Urea resin, 50% in butanol 36.0 Alkyd resin, 50% in xylene 36.0 Above described flatting'paste 15.0 Butanol 3.0 Toluene s 8.5

This composition is suitable for spray application by further dilution with of a solvent mixture containing four parts of toluene to one part of butanol.

Example 2-(Dull finish printing ink) A dull finish printing ink may be prepared by dispersing'carbon black in linseed oil varnishv in conventional manner by five passes on a threeroll ink mill, in the following ratios:

Per cent by weight Carbon black, ink grade 19.0

Bodied linseed oil (No. l Gardner-Holdt)--- 65.0

Then add- Cobalt linoleate drier 6.0 Flatting paste from Example 1 10.0

This mixture is,given two loose passes on the roll mill.

Example 3 -(Matte varnish for brush application) A matte finish varnish for brush application may be formulated from a conventional varnish by addition of a urea resin flatting paste prepared by grinding, as described in Example 1, a urea resin flatting agent with glycerol in equal proportions. In this case a. phenolicmodified drying oil varnish was used, which gave a breakdown formulation of the final product as follows:

Per cent by weight 100% phenolic resin-tung oil complex Linseed oil (boiled) l0 Urea resin in glycerol fiatting paste 15 Turpentine 5 Mineral spirits 40 able thickening, or otherwise detrimentally affect the finish.

About 5% of iiocculating agent, based on the weight of the condensation product, is generally required to produce the desired results.

The preferred method of coating the resin particles with the polar liquid is, of course, to bring the two into intimate contact before incorporation in the finish or vehicle.

However, it is possible (and sometimes practical)- to wet the resin powder after it has been dispersed in the vehicle or finish, simply by addingthe polar liquid to the finish and intimately dispersing it by milling or otherwise thoroughly agitating the mixture.

I claim:

1. A finishing composition which dries to a fiat surface, comprising an organic film-forming composition which normally dries to a glossy film, said composition having dispersed therein a substantially insoluble carbamide aldehyde condensation product in finely divided form to produce the fiat drying properties, the particles of condensation product being coated with at least 5%, based on the weight of condensation prodnot, of a fiocculating agent therefor comprising an organic liquid containing an alcoholic hydroxyl group.

2. A finishing composition which dries to a flat surface, comprising an organic film-forming composition which normally dries to a glossy film, said composition having dispersed therein a substantially insoluble carbamide aldehyde condensation product in finely divided form to produce the flat drying properties, the particles of condensation product being coated with at least 5%, based on the weight of condensation product, of a fiocculating agent therefor comprising a polyhydric alcohol.

3. A fiatting agent useful in the production of flat organic finishing compositions consisting essentially of a substantially insoluble carbamide aldehyde condensation product in finely divided form, the particles of condensation product being coated with at least 5%, based on the weight of condensation product, of a fiocculating agent therefor comprising an organic liquid containing an alcoholic hydroxyl group.

4. A fiatting agent useful in the production of fiat'organic finshing compositions consisting essentially of a substantially insoluble carbamide aldehyde condensation product in finely divided form, the particles of condensation product being coated with at least 5%, based on the weight of condensation product, of a fiocculating agent therefor comprising a polyhydric alcohol.

EARL K. FISCHER.