US1572461A - Application of cellulose-ester lacquers - Google Patents

Description

Feb. 9 1926. 1,572,461

R. A. BEAUSEJOUR APPLICATION OF GELLULCSE ESTER LACQUERS Filed August 19, 1925 Maud Bane! to be Lucguerebb Zacguer Film Coal: Pam-:1 and lllwes flownmrdlyw l'th P4 We) 10/1122 1615 lllmmmed a nd Faces: la c yuer' Drains Off llfil'lz [1-1: Wilt/14rd um flo ting layer m (EM/lose [sterlacqmer $aturate4 flea/anus Wufinpp/fidxhm (Nitride INVENTOR lfieme fleause our';

' gzgawaw ATTORNEY5 Patented Feb. 9, 1926.

UNITED STATES PATENT OFFICE.

REME A. BEAUSEJ'OUR, OF PORT RICHMOND, NEW YORK, ASSIGNOR T0 STANDARD VARNISH WORKS, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

APPLICATION OF GELLULOSE-ESTER LACQUERS.

Application filed August 19, 1925. Serial No. 51,201.

To all whom it may concern:

Be it known that I, Rnzun A. BEAUSEJOUR, a subject of the King of Great Britain, residing at PortRichmond, in the county of Richmond, State of New York, have invented certain new and useful Improvements in the Application of Cellulose-Ester Lacquers; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to,

make and use the same.

My invention relates to improvements in the application of cellulose ester lacquers. The lacquers to which I particularly refer comprise a solution of a cellulose ester, such as cellulose nitrate or cellulose acetate, in a solvent or mixture of solvents, such as ethyl acetate or butyl acetate or a mixture of the two. Such lacquers also usually include diluents such as toluol, turpentine or petroleum benzine, and may also include pignents as well as gums, such as ester gum, and plasticizers, such as castor oil or tricresyl phosphate, for imparting special prope ties to the lacquer.

Such lacquers have been applied by various methods, such as brushing, flowing, spraying or dipping, but for the application of such lacquers on a large scale to objects having considerable surface area, spraying is at present the most importantmethod. These lacquers are hardened by the evaporation of their solvent or diluent content and are comparatively quick-drying. For thisreason it is difficult directly to obtain asmooth coating or a glossy coating, necessitating the use of a smoothing or polishing operation as part of the application of the lacquer. The cellulose ester content of the lacquers, moreover, tends to be again sof-, tened on further contact with solvents therefor so that these difliculties are not avo ded by the apparent expedient of applying successive coats. With spray application particularly, the resulting coat has a rough or finely-pebbled surface. I

In the application of lacquers to objects having considerable surface area it accortb' ingly has been necessary to employ smoothing or polishing operations, and, due to the character of the dried lacquer. coats, particularly where deposited in a rough or uneven condition, these smoothing and polishing operations have involved considerable time and labor and have been a large part of the expense of procuring a satisfactory finished coating,while at the same time over intensive smoothing or polishing frequently resulted in marring of the finished surface, leaving it deficient in finish or gloss and lustre.

More satisfactory results have been secured in lacquering small objects of a size such that they could conveniently be dipped witliout requiring excessive volumes of lacquer, but for practical purposes it is usually desirable to carry out the dipping operation upon a large number of such small objects at the same time. For the treatment either of a large number of small objects or of objects having considerable surface area, a dipping bath of comparatively large volume has been required and this involves further difiiculties. The lacquer compositions usually employed are very inflammableand the fire riskis considerably increased. Evaporation losses are also much greater and the difliculties of maintaining the lacquer composition in the dipping bath constant are also accentuated. Moreover, from the practical I standpoint, the expense incident to the maintenance of a lacquer bath of large volume is not to be overlooked.

There have been proposals to apply cer-,

tain types of coating compositions by dipping the objects to be coated through a relatively thin layer of the coating composition floating on an aqueous bath. Hitherto, however, the substantial exclusion of water -inany form from all operations which in-.

volve the use of cellulose ester lacquers'has been considered essential, probably due to the blooming or blushing of the finish whichalways seems to accompany the presence of water or moisture or water-vapor during the application of the lacquer to the object to be coated. Apparently, this predis osi- 1y accomplished the application of cellulose ester lacquers to both wooden and metallic objects from a layerof the lacquer floating on an aqueous liquid body, and I have secured improved results with respect to the character of the applied coating and unexpected results with respect to freedom of the applied coating from bloom or blush.

. soluble in or which dissolve water to any material extent. I then dip the object to which the lacquer is to be applied through the floating layer of cellulose ester lacquer.

Some of the components of the lacquer may be more or less extracted by the aqueous liquid body without seriously interfering with the operation, but I find it best to correlate the composition of the l1qu1d body and of the lacquer employed in any single operation so that the liquid body is substantially immiscible with the lacquer. To accom lish these results, I may employ a saline liquid body of a composition such that it is substantially immiscible with the lacquer, or I may em loy a lacquer composition substantially which are soluble in or which dissolve water, or I may employ such a liquid body in conjunction with such a lacquer composition.

S ecific limitations of the composition of t e liquid body or of the composition of the lacquer cannot be given because they are mutually interrelated, and in any case the composition of the one to be employed will be somewhat dependent upon the composition of the other. For' example, the saline solution employed may be a solution of sodium chloride, sodium sulphate, potassium chloride, potassium iodide, potassium sulphate, magnesium chloride, magnesium sulphate or calcium chloride. In general, I have found it advantageous to employ heavy solutions, such as saturated solutions or solutions of salts forming solutions of relatively high density, but it will be apparent, for example, that with specific lacquer compositions certain salts may give better results than others. As a further exam le, with' lacquer compositions substantially free from components which dissolve orwhich are soluble in water, water alone may be employed as the aqueous liquid body, whereas with a lacquer contaming, for example, substantial amounts of ethyl alcohol better results are secured by employing a saturated solution of ree from components.

sodium chloride or potassium iodide as this decreases the miscibility of the acqueous body with the lacquer composition.

Commercial cellulose nitrate is usually transported and handled wet with ethyl alcohol to reduce the fire hazard, and the solvents-and diluents employed in making up lacquers as commercially available frequently contain ethyl alcohol. This watersoluble and water-dissolving content of lacquers made from these materials as commercially available are not to be disregarded if they are employed as such. According to my invention, however, I take care of such components as are introduced into the lacquer compositions from such sources by correspondingly regulating the composition of the liquid body on which the lacquer layer is floated. In the case of ethyl alcohol, for example, I employ as a liquid body a watersolution substantially saturated with, for example, sodium chloride or potassium iodide. The alcohol may also to some extent dissolve in the aqueous body but any such tendency may be counteracted by the addition of an appropriate amount of some other diluent immiscible with water or if the amount of alcohol so removed does not materially affect the character of the lacquer, for example with respect to viscosity, this removal oi alcohol may be ignored. Solvents and diluents and cellulose esters. substantially free from such components may, however, be employed with advantage. To reduce the fire hazard in handling cellulose nitrate, it may be wet with toluol instead of ethyl alcohol.

The accompanying drawings illustrate in a diagrammatic and conventional manner apparatus adapted for carrying out my invention, and I will further describe my invention in connection therewith, but it will be understood that my invention can be carried out in other and difierent apparatus. In the accompanying drawings,

Fig. 1 represents in elevation and partly in section with parts broken away an apparatus adapted for carrying out my invention, and

Fig. 2 schematically illustrates, in a view corresponding to a transverse section through ranged beneath a vertically movable frame or track 6. The objects-to be dipped are supported from a truck or carriage which during the dipping operation is carried on the frame 6. The carriage 7 is movable on to and oil of the frame 6 and by providing a number of these carriages successive dipping operations can be carried out rapidly by running the carriage supporting the object or objects which have just been dipped off on the track and replacing it with a carriage supporting the object or objects next to be dipped. To provide for regular and controlled vertical movement of the frame or track 6, one end of the frame is supported by a plunger 8 of a hydraulic jack 9 and the other end of the frame or track is supported by a wire rope or equalizing cable 10 running over suitable pulleys and connected to the end of the frame or track adjacent the lunger so that vertical movement of the rame or track will be uniform at both ends. To operate the hydraulic jack, fluid under pressure from connection 1.1 is supplied to the two-way valve 12 which also communicates with the chamber of the jack through connection 13 and an outlet connection 14. The valve 12 is arranged to permit the introduction of fluid under pressure from connection 11 into the jack chamber or to permit the escape of fluid from the jack chamber through connection 14 or to close the jack chamber. The valves 15. and 16 are provided in the fluid inlet and outlet connections respectively for regulating the rate of flow of fluid there through, and thereby.the rate of vertical movement of the track or frame 6.

Dipping apparatus of the type illustrated provides for uniform and regular motion of the object or objects to be dipped dur-- ing the dipping operation and also enables the rate of motion of the object or objects to be dipped both up and down to be closely controlled. I have found apparatus of this type to be advantageous in carrying out the invention, but it will be apparent that other dipping apparatus might be used.

In operation, the dipping tank 3 is partially filled with a liquid body of greater density than the lacquer composition to be employed and substantially immiscible there with, and a layer of the cellulose ester lacquer is floated on this liquid body. The amount of lacquer in the floating layer should be suflicient to supply the lacquer necessary to coat the objects to be dipped at least for a single operation and to insure the'provision of a continuous film of acquer about the objects to be dipped during immersion. The lacquer layer may, for example, be of a thickness of from some thing less than 1 up to 2 to 3" or more. \Vith a lacquer composition substantially free from water-soluble or water-dissolving components, water may be employed as the liquid body for floating the lacquer layer unless due to the use of heavy-pigments -the density of the lacquer is greater thaii that of water. For floating heavier, lacquers, or to promote the immiscibility of the aqueous body with the lacquer, a saline solution such as a solution of sodium chloride or potassium iodide may be used as the liquid bod The object or objects to be dipped are t en slowly immersed through the floating layer of lacquer until coated over so much of their surface as may be desired and are then withdrawn, the speed of immersion and withdrawal being regulated to avoid undue disturbance of the floating lacquer layer and to allow for draining of excess lacquer from the coated object or objects.

The mechanism of the dipping operation itself will be clear from Fig. '2, and it may be directly observed by carrying out the dipping operation within a glass container. As the object to be dipped, illustrated in the drawings as a-wood panel'17, enters the dipping bath it first contacts with the.

floating lacquer layer so that a film of the lacquer is formed across its lower edge and as it continues to move downwardly through the floating lacquer layer a lacquer film forms coating and covering the exposed surface of the object.' As the object is withdrawn, excess lacquer drains off into the floating layer leaving a coating of the lacquer upon the exposed surface of the object. Any portions of the lacquer broken away from the floating layer during the operation tend to separate in the aqueous liquid body as globules which quickly rise and on contact with the floating lacquer layer again to join it.

My invention will be further illustrated by the following example: A lacquer composition consisting of 150 lbs. of cellulose nitrate, 5 gals. of tricresyl phosphate, 35 gals. of toluol, 25 gals. of ethyl acetate and 20 gals. of butyl acetate may be employed in conjunction with a liquid body of water, or better of a saturated solution of sodium chloride or potassium iodide. The dipping operation may then be carried out as has been described in connection with the apparatus illustrated in the drawings using a lacquer and a liquid body of'these compositions. In the foregoing lacquer composition, 30 pounds of the cellulose nitrate may, for example, be replaced with 50 lbs. of ester gum, and the toluol may, for example, be replaced in part by turpentine or petroleum benzine or in whole or in part by other diluents or diluent mixtures. Likewise, solvents other than ethyl acetate and butyl acetate may be employed. 1

'Cellulose nitrate as commercially available usually contains about 30% by weight of ethyl alcohol, the cellulose nitrate being Wet with the alcohol to reduce the fire hazard, and commercial ethyl acetate and commercial butyl, acetate usually contain substantial amounts. alcohol 1s not excessive, lacquer compositions about 15% of ethyl alcohol and about 10% It-will acof butyl alcohol respectively. cordingly be apparent that, if these commercial materials in the form in which they are usually available are employed in a lacquer used in carrying out an operation similar to thatdescribed in the above example, ethyl alcohol, which is soluble in water and which dissolves water, will be present in Where the amount of made from the commerical materialsin their usual form may nevertheless be floated on an aqueous bath, and, where an excessive amount of alcohol is so introduced into the lacquer composition, satisfactory results can be secured by employing a saline liquid body of suitable composition, such as a saturated solution of sodium chloride or potassium iodide.

In some cases, when the dipping operation is continued for prolonged periods, an emulsification of the lacquer in the aqueous body or of water from the aqueous body in the lacquer may tend to take place, and this is' usually due eitherto the presence in the lacquer composition or ini'the aqueous bod of components which tend to promote suc 1 emulsification or to the maintenance of excessive temperaturesin the dipping bath. Certain gums which are sometimes employed in lacquers, for example, may tend to promote emulsification. With respect to temperature, the dipping operation is best carried out at temperatures as low as can conveniently be maintained, although refrigeration is not essential. The operationcan be carried out with a lacquer composition of the type described above with bath temperatures of from to F. or higher although a better separationbetween the lac. quer layer and the liquid body may be maintained by the maintenance of lower temperatliresr The dipping bath may, for example, be cooled by circulating water or other cooling medium through pipe coils arranged in the dippin tank or in heat exchanging relation wit the walls of the dipping tank to maintain bath temperatures of from 40 to 65F, although lower temperatures may be used. Low bath temperatures have the further advantages of retarding eva. oration from the bath and of assisting in e application of relatively thick single coats with any particular lacquer composi tion. If emulsification proceeds to any objectionable' extent, the lacquer layer and the emulsified part of the dipping bath may be withdrawn and run through 'a filter or a centrifuge or otherwise treated to break the emulsion. a

The lacquer coating which -I obtain in carrying out my invention is of good quality, free from bloom or blush, and of improved smoothness. While polishing operations may still be desirable or necessaryto propolishing and the intensit of the operation may be materially reduce consequently enabling a substantial reduction in the time, labor and expense involved in the polishing operation. One or more coats may be applied according to my invention. Thethickness of the individual coat can be controlled by regulating the viscosity of the lacquer and the speed at which the object or objects to be dipped are immersed and withdrawn. With a straight panel, such as that illustrated in the drawing, the speed of immersion may be as much as 8" per minute or somewhat more and the speed of withdrawal may be in the neighborhood of 6" per minute or somewhat less. I find it advantageous to so regulate the speed of withdrawal that opportunit is provided for substantially all excess of acquer'to drain from the object or objects dipped as they are withdrawn and so that dippin of lacquer from the loweredges ofthe o ject or objects after they are withdrawn 1S substantially avoided. Other things being the same, a thicker coating is obtained as the viscosity of the lacquer composition is increased and as the speed of withdrawal is increased. 1 have found my invention to be a particularly advantageous way of applying relativel thick lacquer coatings'in a single dip.

W iile my invention is of general utility in connection with the application of cellulose ester lacquers, in the case of pigmented lacquers containing relatively heavy 0&1 mcnts it is sometimes necessary to m the operation in order to provide for suflicient separation between the floating lacquer layer and the su porting liquid body in the dipping bath. gvith' lacquer compositions containing comparatively light pigments or relatively small amounts of lightpigments,

such as a black lacquer pigmented with lamp biack, water alone mav be used as the supporting liquid body. With lacquers containmg heavy pigments, however, it is sometimes advantageous [to employ heavier liquid bodies, such as concentrated solutions of sodium chloride or potassium iodide or of- .for many purposes flat finishes of satisfactory quality can be obtained by my invention using such lacquer compositions without the necessity of any smoothing operation or with very materially reduced expenditure of time and labor in smoothing.

While I have described my invention particularly in connection with the use of an aqueous liquid body for floating the lacquer layer, it will be apparent that other liquid bodies of greater density than the lac uer used and which are substantially immiscible with the lacquer are useful in the application of cellulose ester lacquers in accordance with my invention.

My invention has several important advantages. From the standpoint o-f operation, it will be apparent that I have provided a method of applying cellulose ester lac quers by dipping which is applicable where a large aggregate surface is coated in a single operation and which at the same.

time avoids the necessity of using large volumes of the lacquer. By avoiding the use of excessively large volumes of the cellulose ester lacquer, I avoid or minimize fire hazards, I reduce the expense and I. make it easier to maintain the composition of the lacquer bath. I also provide an operation in which cheap liquids may be employed for floating the lacquer layer, for example water or saline solutions such as a solution of sodium chloride may be used. From the standpoint of the lacquer coating obtained, my invention enables the production directly from the dipping operation of a coating of improved smoothness reducing the amount of smoothing or polishing necessary to secure smooth or glossy finishes. My invention also provides an operation in which bloom or blush of the lacquer coat due to the presence of water is avoided. My invention also is advantageous in the application of relatively thick individual lacquer coats.

I claim:

1. An improved method of applying cellulose ester lacquers, which comprises floating a layer of the cellulose ester lacquer on a liquid body of greater density which is substantially immiscible with the lacquer and dipping the object to which the lacquer is to be applied through the floating layer of cellulose ester lacquer.

2. An improved method of applying cellulose ester lacquers, which comprises floating a layer of the cellulose ester lacquer on a liquid body of greater density which is substantially immiscible with the lacquer,

liquid body, and dipping the object to which the lacquer is to be applied through the floating layer of cellulose ester lacquer.

3. An improved method of applying cellulose ester lacquers, which comprises floating a layer of cellulose ester lacquer substantially free from components substantially soluble in or capable of dissolving water on an aqueous body of greater density which is substantially immiscible with the lacquer and dipping the object to which the lacquer is to be applied through the floating layer of cellulose ester lacquer. I

4. An improved method of applying cellulose ester lacquers, which comprises floating a layer of the cellulose ester lacquer on a body of an aqueous saline solution of greater density which is substantially immiscible with the lacquer and dipping the tially soluble or capable of dissolving water on a body of aqueous saline solution .of greater density which is substantially immiscible with the lacquer and dipping the object to which the lacquer is to be applied through the floating layer of the cellulose ester lacquer.

7. An improved method of applying cellulose ester lacquers, which comprises floating a layer of the cellulose ester lacquer on an equeous body of greater density which i is substantially immiscible with the lacquer and dipping the object to which the lacquer is to be applied through the floating layer of cellulose ester lacquer.

In testimony whereof I aflix my signature.

REME BEAUSEJOUR.

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