USRE17379E - Carleton ellis - Google Patents

Description

Reissued July 23,

UNITED STATES PATENT OFFICE.

CABLE'I'OH ELLIS, OF KON'ICLAIB, NEW JERSEY, LASSIGNOR TO ELLIS-FOSTER GOI- PANY, A CORPORATION OF NEW JERSEY.

ARTICLE SURFACED WITH NITBOCELLULOSE AND SYNTHETIC RESIN COATINGS AND PROCESS OE MIAKING SAME.

In Drawing. Original No. 1,529,056, dated liarch 10, 1925, Serial No. 084,359, filed January 4, 1924.

- Application for reissue filed March 29, .1926. Serial No. 98,378.

This invention relates to articles such as sheet metal surfaced with coatings contain ingnitrocellulose and a synthetic resin or resins as essential constituents and to the process of makin same and relates especiallyto sheet meta having .one or more surfaces coated with com ositions of the character hereinafter speci ed.

Automobile metal bodies, metal furniture l0 and other objects or articles of sheet aluminum, steel, copper, brass and the like hearing a protective or-orna-me'ntal coating compris-' ing nitrocellulose and a compatible synthetic resin fall within the purview of the present invention.

The invention will be illustrated more particularly with respect to its application in the automobile industry. The painting of automobile bodies with a durable coating h as long been a problem. Automobile bodies, being erposcd to sun-and rain usually present. a dilapidated appearance after a seasons use. A durable surface for exposed body parts is much desired.

()ne object of the presentinvention is to achieve a high degree of durability for coated able materials. I

In the exterior finish of an automobile body there is required acertain degree of hardness to resist abrasion coupled with toughness and metal by the use of relatively cheap and availelasticity. Furthermore the cou ting must adhere tenaciously as not to chip or scale with. The s nthetic resin acts not only as an j agent town or greater adherence but also increases the total binder solids thereby giving I greater substance and producing'a more effective. finish. The surface finish, whether'int'cntionally dull or lustrous,.s ho1 1ld have a .quality of smoothness ,which results only when suf icient bindingagent is p esent to cement or bind together the particles of pig ment.

There are very definite limits to the solubility of nitrocellulose. The same is true of the natural resins. Furthermore some of the natural gums or resins are by no means compatible with nitrocellulose. Only a restricted number of the natural resins are appropriate for compounding with nitrocellulose and the supply of. these natural resins is limited or the market prices thereon are .subject to considerable fluctuation which is disadvantageous from a manufacturing standpoint; On the other hand there are a number of synthetic resins, which, according to the present invention, may be used Without therestrictions or disturbances imposed in using the natural resins, which is a condition of affairs highly advantageous.

Furthermore the cost of manufacture of such synthetic resins generally speaking, is not subject to great variation due to violent fluctuations in the cost of raw materials.

The following paragraphs denoted by numerals indicate some of the considerations, conditions and requirements involved in con nection with the present invention.

.1. C'o'nsz'stency of the coating composition.

The consistency should be such that the composition can be applied by means of a brush or a spraying device. If applied by the former method the composition should dry'slowly enough to not show brush marks. 1

Itshould work freely under the brush. This depends in art on the proportion of so]- vents and t eir degree of volatility. A quicker drying medium may be used'for application by spraying.

p 2. Quick drying.In any event the quality of quick-drying enerally is .very important as this feature a1 ows several coats to be applied in a day. With a quick-drying mate rial articles may be moved through the paint department rapidly and less space therefore is required for the operation.

3. Sand papering.The surface should be capable of being sand papered soon after application, without gumming of the sand paper.

Avoidance of preei ati0n.- There should be no precipitation uring drying due to a Change in theproportiqn 0f S IYGN y.

adjusted: to prevent any precipitation or coagulation during the drying period.

5. Water eZiminatiOn;In the preferred form of coating material water should not v be present. This may be secured by care in the selection of therraw materials and especially by the use of anhydrous solvents. If water is present a high boiling solvent or water-eliminant preferably isadded. This solvent should exert its solvent effect not only on the nitrocellulose but also on the synthetic resin during the stage of drying when water is being expelled.

Tptal s0ZizZs'.The Coating compositionpreferably should have a high content of total solids, preferably 50 per cent or more, in order that each application of a coat will leave on drying a substantial film. Since solvents or thinners represent a loss as they are used only to render the composition liquid for application the percentage of solvents or thinners should be liept as low as possible, i

'resin has too great a softening effect, and

consistent with ease of application. Expensive solvents usually are not feasible as the cost of manufacture should be kept low.

7. Pigmenta-There is a direct connection or co-operative efi'ect existing between pigment and binder. Films of nitrocellulose and synthetic resins suitably incorporated with pigment are more durable and resistant than the unextended film. The igment should be compatible with nitrocellu ose and notbe of an acid character such as would tend to impair the stability of the nitrocellulose to an objectionable degree. If stabilizers of a basic character are used in the nitrocellulose the pigment should not produce any thickening or livering effects with the synthetic resin employed. .Mineral colors-such as ochre, um ber, iron oxide or mineral red, variouslakes and the like may be used. White pigments may be employed for making enamels. It is important to have the pigment finely divided an it is best to grind the pigment either with the solvents or the solution in the solvents of either the nitrocellulose or the synthetic resin or both.

8. Synthetic resim This material must be compatible or blend adequately with nitrocellulose, as the composition dries the resin.

should colloid well with the nitroceluose. Furthermore the resin" should be soluble in solvents appropriate for nitrocellulose ineluding any high boiling solvents used aswater eliminants, which solventsare generally last to leave the coating. Even though the solid constituents blend in the original solution separation may occur as the solvents evaporate due to changing composition. This should not occur and the ratio of one solvent to another in evaporation of a composite solvent preferably should be such as will at all times accommodate and promote a colloidal blend of the nitrocellulose and synthetic resin. v

If nitrocellulose is incorporated with an incompatible resin in asuitable solvent mix- 'ture the liquid especially if very viscous may dry without segregation. In the solid film which forms the incompatible consituents will however be in a state of tension or stress and aggregation, yielding a-brittle product,

will result on standing especially under the action, of light and moisture. Such a coatcellulose is used the character of the resin may be quite soft. Its effect on the nitrocellulose will be to render the latter more fiexible. In other words it acts also as a softening agent. Nitrocellulose will however take up or assimilate'only a moderate amount of such a soft material without detriment to its other properties. A high proportion of soft harder resins should be employed in this case. As a general rule thehardness of the resin preferably should increase withthe proportion employed. In some cases a soft resin may be used for softening purposes, coupled with a hard resin as an extending binder in order to secure the desiredphysical properties. In the present invention I preferably employ the synthetic resin in considerable proportion; for example in an amount at llll least equal to the nitrocellulose and in some casesin the ratio of up to two parts of synthetic resin to one part of nitrocellulose or even in higher proportions.

10. 00101 of the synthetic -;-csin.This depends on the color of the coating material dc.-v sired. White or colorless synthetic resins should be used for very light colored coating s, while red, brown or black synthetic resins may be used for darker'colored coat: ings.

J0. Solubility-As noted the synthetic resin should be soluble in solvents appropriate for nitrocellulose. For examplegacetone. various alcohols, ethyl acetate, amyl cetate and the like and mixtures of thesebenzol, etc. r 1

12. iS'tabilitg of resin on ewfwsmieI-Flreferably the synthetic resin should show good res stance to weathering influences; It apvllli pears however that the synthetic resin and nitrocellulose may'supplcment each other so' til ' coating in a pro-eminent way. therefore the maximum amount of nltrocellulose Wl'llCh can fore are not as desirable. Ordinary nitro cellulose of the type known as soluble cotton low-viscosity nitrocellulose basic pigments such as oiide or white lead and react with these pigments to cause objectionable thickening so that the coating becomes difiicult to apply.

.14. Nitrocellulose-The toughness and elasticity of nitrocellulose are desired in the beincorporated without making a solutions'o viscous-that it cannot be readily applied should be an objective. A low-viscosityni trocellulose preferably is used in order to secure the maximum proportion of this substance consistent with ease of application. Nitrocelluloses such as gun cotton and the like forming highly viscous solutions theremay be used. ,Cotton which has been exposed to heat at a temperature above 100 C. and having thereby a greatly diminished viscosity is especiallyuseful. The cheapest stock for making the coating probably is celluloid scrap. Moving picture film or other white of the present inventionfurther details will be hereinafter given.

invention and their use is preferablyconiined to the status of moderate additions.

19. Miscellaneous ingredients. 0 t h e r substances which, may be used toa greater or less degree include cellulose acetate, cellulose ethers and the like. Also fire retardants may 15. Stabfl izers.llrea and its derivatives, amlnes, magnesium lactate and the like may be used as stabilizers. Zinc oxide, whiting and other basic pigments act as stabilizers. Celluloid ordinarily contains astabilizer.

.76. Dehydratiom-$oluble cotton containing 5 per cent or so of water maybe dried before use. A bone-dry product reduces the amount of relatively costly wateryeliminants.

' eners is-to prevent brittleness.

17'. Softe'neria 'llhe purpose ofusing softsubstances may be employed which are compatible with nitrocellulose and the synthetic resins employed. Softeners include castor oil. nitrated castor oil. certain boiled and blown oils. such for exmuple as blown rape oil. camphor, camphor acetate, diethyl -phthalate. acetanilidev triacetin. triphenyl and tricresyl phosphates. For best results the softener should be entirely compatible both with the nitrocellulose and the synthetic resin.

.78. Natural rcs ins.The addition of nat-' ural resins such as dammar or shellac, Congo, copal and the like is not precluded. A proportion in excess of the amount of synthetic resin simultaneously employed is not. usuallv desirable. Natural resins are too inflexible in their physical properties to be readily adj ustable to meet the conditions of the present be added including various chlorinated solids and appropriate mineral salts. When the coating is to be used on wooden surfaces the inflammability' preferably is reduced to the lowest point practicable.

20. SolventsE-As stated these are usually composite'and a typical one consists of three components,

(a). a highly volatile liquid which isa good solvent for nitrocellulose (7)) a slowly volatile solvent which is a good solvent for nitrocellulose and which serves as a watereliminant (c) a volatile non-solvent employed as a 'cheapening agent.

Under group (a) are included such solvents as acetone, methyl acetone, methyl and ethyl acetate, various ethers and ethyl formate.

'Methyl and ethyl alcohol are not good solvents and are best used with one or more of the foregoing active solvents.

Under group (5) butyl and amyl alcohol, myl acetate, diacetonc alcohol, ethyl car-- bonate audlhc like are included as high boil ing solvents or wter climinants. Furfural may be used to advantage. Furfural is a very active solvent for most forms of nitrocellu-- lose but is especially useful in preparing solutions made from lmv-viscosity nitrocellulose, particularly those products which have been reduced in viscosity by special heat treatment. Furfural is usually dark in color and it is resinified by acids. Therefore in using furfural some mildly basic material. advantageously may be present to stabilize the solution and prevent the formation of acids which would. aifect the fur'fural. Also it is best tormploy furfural only in the preparation of darker colored coatings.

A variety of (c). In this group benzol isprobably the most important solvent... Light coal tar distillate, toluol and xylol and solvent naphtha also may be used in some cases. Preferably however the non-solvent should be very readily volatile as it is undesirable to have too great a concentration of non-solvent in the coating during drying. Carbon tetrachlm ride, trichlorcthylene and petroleum spirits sometimes may be employed. ,Benzol is far preferable to petroleum spirits as it does not loo - coagulate nitrocellulose nearly as 'readily as" the petroleum spirits. This enables a greater proportion of benzol to be used in the com-- position than is the 7 case when petroleum spirits is used as a-substitute. Theclass (c) solvents usually are substantially free from water. They are valuable either because they actas resin solvents or because when admixed with alcohol or acetone they afiord a solvent lilll mixture which dissolves many synthetic" resins very freely. V

I Sometimes solvents ,of the group (c)v type are omitted entirely for various reasons such as-modificationiof viscosity-or increase in the quantity of synthetic resin, etc.

21. Anhydrous conditions. The presence of water in small amounts causes blushmg on dryingand uiiless aw'ater-ellmlnant,

treatment with calcium carbide, quick lime and the like or by boiling with magnesium powder. Dry nit-rocellulose'and anhydrous solvents of a highly volatile character reduce the amount of or-ren-der unnecessary the use of the more costly highly boiling .solvents. In any event a lesser amount of the latter. is generally required in the winter season when the air is dry. In a humid climate the amount of high boiling solvents may be increased to correspond to the conditions.

522. Varnz'skea-Larquers made from nitrocellulose usually have a high proportion of solvents. varnishes made in accordance with the present invention are preferably produced with theaid of heat-treated low-viscosity .nitrocellulose in conjunction with a fairly .high proportion of synthetic resins in order to raise the total solids to as high a degree as possible. Preferably the total solids should be from 30 to per cent. The addition of dyes soluble in the solvents employed but preferably water-insoluble serves to make varnish stains.

23. Use of-a priming c'oat.Thc'surface preferably is primed. with an oil-primer such as is used in ordinary painting operations as a first coat. Such a primer is especially desirable on metal to assist in adhesion. Nitrocellulose coatings of themselves as noted have low adhesive properties. An oil-primer or a primer of a character substantially dissimilar so that of the outer coatings preferably is use It may be noted that the surface, if of steel or other metal, first may be cleaned by sandblasting or treatment with some solvent or cleaning liquid e. g. a solution of phosphoric acid in alcohol. a The surface may be scoured with steel wool and washed with hot water.

After cleaning the surface a primer or oilprimer is applied andvmay be exposed to a temperature of C; for 1 to 2 hours to cause rapid and thorough drying. The automobile body or whatever metallic surface is being treated may be putty glazed and coated After sanding the surface with a sand surfacer. The latter likewise may be baked at about 150 C. for an hour or more. These coatings serve to form a good under-finish or foundation which can be rubbed to a smooth surface by sand papering. is washed With water.

'When applying the coating to wooden surthe primer used be free from nitrocelluluose nor that; it be simply an oil-primer. In some cases a synthetic resin priming coat may be employed.

24. Apply 5n nitrocellulose-synthetic resin coating.-Sur ace nowin readiness to receive the nitrocellulose synthetic resin coatings. These may be applied with brush or air-gun. After applying a coating the latter may be exposed to a temperature of 50 C. for half an hour. A second coat is applied and similarly dried. The finish then is rubbed with boiled linseed oil and rotten stone and if desired may be given a wax finish or polish (carnauba or candelilla wax). If two coats arenot adequate an additional number may be applied.

The following indicate various compositions illustrative of the present invention.-

Ewample 1.

Low-viscosity nitrocellulose 5 parts by weight.

Phthalic glyceride rosin ester 5 parts.

Blown rape oil 7 parts.

Prussian blue 1% parts (and upwards).

Composite solvent 60 parts. 7

The low-viscosity nitrocellulose referred to in the foregoing formula has been heat-treated to-render its viscosity as low as possible and its solubility high. The composite solvent is made from 7 parts denatured alcohol, 28 parts ethyl acetate, 45 parts butyl alcohol, 20 parts amyl acetate. It will be noted that this solvent does not contain any benzol. The synthetic resin is made as follows: 35 parts by weight of glycerine, 134 parts. of common rosin and 31 parts of phthalic anhydride are mixed and heated under a reflux condenser until a temperature of 270 C. is reached. The condenser is of such length that the water formed by the reaction escapes while glycerine is retained.

Example 2. Moving picture film is boiled in water, preffrom the heat-treated product exhibited a viscosity of about 45 seconds.

2.7 parts by weight of phthalic anhydride and 1 part of glycerine were heated together to a temperature of about230 C. When the temperature reached this point the heating was discontinued as further heating is liable to bring about the formation of an insoluble product. A soluble resin was obtained which was incorporated with the heat-treated celluloid film obtained as above.

Proportions used were 2 parts by Weight of the heat-treated film to 4.8 parts phthalicglyceride resin. These components were dis: solved in 8 parts of a composite solvent made up of 2 parts furfural, 1 part ethyl acetate, 3 parts acetone and 2 parts benzol. On drying a brownish film was obtained which showedno segregation, under the microscope, and which was hard and tough. To the foregoing various softeners such for example as those previously described and the requisitequantity of a suitable pigment may be added. The pigment should be ground in the solvent solution or in a mixture to secure the best spreading qualities.

The various methods of producing nitrocellulose of low-viscosity by heat treatment have been set forth in my patent application, Serial No. 682,553. The disaggregation or depolymerization of nitrocellulose by such heat-treatment to produce low-viscosity material is of special value in connection with the use of furfural as a solvent. It may be noted that commercial furfural may contain water which will separate and cause turbidity on the addition of. benzol. This may be cleared by of preferably 10 to per cent of the total.

solvents, the balance being highly volatile solvents such as acetone, ethyl acetate, alcohol, benzol and the like. i

Furthermore it may be noted'that the addition of benzol to such low viscosity solutions tends to increase the viscosity somewhat and when the lowest degree of viscosity is re quired benzol and similar non-solvent preferably should be avoided and acetone, ethyl acetale and the like used instead.

E trample 3.

30 parts by weight of toluidine and a like amount of tung oil are heated with 6 parts of zinc chloride dissolvedin 5 parts of Water.

The heating'is carried out in aflask open or arranged with an ordinary condenser to carry oil vapors without refluxing action, temperature being raised to 285 C. producing a reddish resin. Equal parts of this resin and low-viscosity soluble cotton were dissolved in acetone to produce a solution of 20 per cent strength and upwards. The solutions were low in viscosity and on. drying formed yellow to brown films which were very flexible. The to] uidine-tung oil resin has a very useful softening action as Well as furnishing a resinous extending constituent. The films were bright and clear with a good gloss and without any indications of segregation when subjected to microscopic examination.

To compositions of this character a dye ofjan appropriate shade may be-added to produce a varnish stain, or a finely ground pigment may be introduced. Thus one may prepare stains or paints of for example a mahogany color intended for coating the steel interiors of railway coaches to yield an imitation of mahogany wood. A thorough baking is desirable with this type of resin. A coated metal product within the purview of the present invention thus is'obtained. V

. E mamplefi. 1 part of nitrocellulose film, rendered low in viscosity by heating a few minutes to 16(1 C. as described in the foregoing, 2 parts of resin made from toluidine and tung oil as described above, 2 to 3 parts of acetone and V to 1 part of furfural, the proportions being by weight, yields a heavy-bodied liquid from which a varnish, paint or stain can be made in accordancewith the foregoing.

Example 5.

described .above, were incorporated with a mixed solvent composed of 2 parts by weight of furfural to 1 part of ethyl acetate, 3 parts of acetone and 2 parts of benzol. This yield ed a composition which although liquid was too heavy to be applied by brushing or spraying and required the addition of a thinner to yield a consistency adapted for addition of pigments and thelike. The films obtained or coatings produced werevery dark in color hence the composition is adapted only for producing coatings in the darker shades.

The composition referred to in these claims ble phthalic glyceride.

is specifically claimed in the copending application, Serial No. 684.358, filed January 4. 1924.

Having thus set forth my invention, what 1 claim is:

1. Sheet metal carrying a coating composition containing nitrocellulose and a syntheticresin compatible therewith.

2. A sheet metal article carrying a synthetic resinous coating composition toughened with nitrocellulose, the resinous materials being compatible with the nitrocellulose.

3. Sheet metal carrying a coating containing nitrocellulose, a synthetic resin compatible therewith and a natural resin.

4. Sheet metal carrying a coating containing nitrocellulose, a synthetic resin compatible therewith and a pigment.

5. Sheet inetal carrying a coating containing-nitrocellulose, a synthetic resin compatible therewith, and a finely divided pigment.

6. Asheet metal article carrying a coating containig nitrocellulose, a pigment finely ground with the nitrocellulose, and a synthetic resin compatible therewith.

7. Sheet metal carrying a tightly adherin coating containing nitrocellulose of reduce viscosity and a synthetic resin compatible therewith.

8. Sheet metal carrying a coating containing nitrocellulose and a phthalic glyceride' resin. 9. Sheet metal carrying a coating containing nitrocellulose of low-viscosity and a solu- 10. Sheet metal carrying a coating containing nitrocellulose and soluble synthetic phtha'lic glyceride resin. I

11. Sheet metal carrying a coating containing nitrocellulose of low viscosity and phthalic glyceride.

12. Sheet metal carryinga coatin containg nitrocellulose and soluble phthafic glycer- 1 e.

13'. Sheetmetal carrying a primer and a coating containing nitrocellulose and a symtheic resin compatible therewith.-

14. Sheet metal carrying an oil-primer and a coating containing nitrocellulose and a synthetic resin compatible therewith.

15. A process which comprises applying an oil-primer to a metal surface asa-n anchoring coating, allowing the same to dry, and applying thereto a plurality of coats with a composition containing nitrocellulose and a synthetic resin compatible therewith.

16'. A process which comprises coating sheet metal consecutively with a primer and a nitrocellulose composition containing a synthetic resin compatible therewith.

17. A process which comprises applying a coating composition containing nitrocellulose and a synthetic resin compatible therewith to a metallic surface-that has been putty CARLETON ELLIS.