US1821306A - Apparatus for applying thin even layers of liquids on surfaces - Google Patents

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Sept. 1, 1931. A. K. G. HlNGT 1,821,306

APPARATUS FOR APPLYING THIN EVEN LAYERS OF LIQUIDS on SURFACES Filed April 20. 1929 FIGzE Ll enldf:

Patented Sept. 1, 1931 UNITED STATES PATENT? OFFICE ALBERT KARL GOTTHELF HINGST, OF VENLO, NETHERLANDS, ASSIGNOR TO FRANS VAN DER GRINTEN, OF VENLO, NETHERLANDS APPARATUS FOR APPLYING THIN EVEN LAYERS O1 LIQUIDS ON SURFACES Application filed April 20, 1929, Serial No. 356,779, and in the Netherlands December 8, 1928.

In the developing of modern photo-types (e. g. diazotypes), a thin layer of a liquid developer, e. g.a solution of an alkali, a solution of alkali and an azodyestulf component,

15 or a neutral solution of an azodyestuif component, either mixed or not, with salts, bufl'er salts, anti-yellowing means, means for gluing etc., is often and very profitably spread in a thin even layer over the entire surface. With this process it is .of great importance,

that the layer should be even and exceedingly thin and that it should be applied without rubbing. It is also important, that the developer should come only on the side of the print to be developed and not on the other side. Apparatus which effect this with a certain de ree of perfection are known, (see Van er' Grinten et al., No. 299,042, filed August 11, 1928). so Such apparatus are, however, rather complicated and expensive and, because for instance the work is done with two rollers, pressing'on each other, they have the drawback, that pleats or other imperfections are sometimes formed. Also, the developer at the beginning of the sheet to be developed comes in contact with the back.

All these drawbacks are practicall entirely removed by the; use of an exce' ingly simple and cheap apparatus The proper working of this small apparatus is based-on the fact, that-an exceedingly thin and even layer of ii uid can be put on bymeans of a single rol er, and therefore entirely without pressure.

The sheet of paper or other material to 'be' developed passes in the apparatus in such manner that it is laid against the roller by a comb or a similar non-rotating device which acts on the back of the paper or other material. a

The material to be developed follows the roller over a part, for example to 1/20 of its circumference, whereas on leaving the roller surface a'very thin and perfectly even layer of liquid remains onthe material, withoutformation of drops or strips of liquid on the paper or other material. It is remarkable that in the relatively short time of contact the liquid is taken up so well by the surface to be developed and this without any pressure being exerted on it for the comb exerts pressure only where its teeth rest, but not in the interstices, and yet the paper is evenly moistened. The pressure of the comb is only to effect the laying on of the paper against the roller and should be sufficient only for that purpose. It naturally goes without saying, that this surface must also co-operate, in so far that it may not push off the liquid through being too slippery or too hard or too hardly sized or by entire lack of sucking power; the liquid itself must also be taken up more or less easily. The liquid for instance must not have too high, a viscosity.

It seems that the capillary forces are so larieflhat they effect all that was supposed to ave to take place mechanic-ally in the older apparatus.

The nature of the roller surface plays a large part. The roller is preferably chosen of moderatel hard material. Yet a. metal roller covere with a thin layer of soft rubher, works much better than a hard metal surface or ebonite or glass. The surface must also preferably be rough and not slippery. It should not be greasy.

A long-used surface of thin soft rubber on a hard su porting roller can profitably be made roug again, for example by a treatment with fine emery-paper. The circum-v ference and diameter of the roller also influences the result.

Preferably 'thin rollers are used of about 3-4 cm. diameter. This is of special im rtance with thin, slack sheets. With '01: coarse material the roller may have a larger diameter. The diameter of the roller may for instance be so regulated, that it works well for. a certain use within certain limits for thin as well as for thick material.

With phototype papers these limits are 40-150 g. per m2 and therefore a roller of Mom. diameter can be used very well.

The apparatus consists, therefore, in prmciple, of one roller only, running in a trough, and a comb which rests on it. Instead o a comb having its teeth s aced about to 2 cm. from each other an made of any' suitable material, an equivalent device may be roller may also be supplied, for example in the form of a comb with a distance between its teeth of 5-10 cm.; the teeth being as thin as possible. When leaving the roller the paper should be touched as little as ossible on its printed side until it is dry, ecause otherwise stripes will be formed. It is practicable to connect the trough with a reservoir containing the developing liquid in such a manner that the level in the trough is automatically kept constant, the connection, for example, being based on the well-known principle of the bottle of Mariotte.

The apparatus'is illustrated in the accom-.

panying drawing, in which Figure 1 is a diagrammatic side view, partly in section, and Fig. 2 is a front view.

In the drawing letter a is the roller, 6 the paper, 0 is a celluloid comb, which is brought into and out of contact with the paper on the roller by rods e, pivoting on an axle d. The weight of the comb should be sufficient to exert enough pressure to insure the proper laying of the paper against the roller. 7 is a table over which the paper is conducted, 9 is a device to take off the paper from the roller, which may for example be'a celluloid comb, which prevents the paper being carried around the roller.

h is the trough in which the roller (1 turns I and which is filled with the developing liquid, the surface of which is kept on a determined level because the trough is connected by an opened cock is, with a closed flask Z. When the developing liquid is used u the cock k is closed, the flask Z opened, re lled, closed and placed in its original position, after which the cock is opened.

Any known drying device of approved type can be combined with the apparatus.

By the use of a small table etc, before and behind the roller, eflicient Working is promoted. When using thin limp sheets, the sheet is preferably put across a stationary roller and a short distance over the take-off device. To this end, the su plying comb is made so that it can be tippet up. After putting in the sheet, the comb is tipped down and the apparatus is set in motion in one of the abovementioned ways.

By this method thin, limp'sheets are prevented from adhering and going round with the rollers and underneath the take-off device. A small slip of the beginning of the sheet (which remains undeveloped) is then sacrificed. The quantity of li uid which is put on, depends on the speed 0 the apparatus. If this is small, then the quantity is little, in other words, the layer is thin.- If tl e speed is high, then the quantity of liquid is large, in other words, the layer is thick. It

is, however, always uniform, except with very high speed. Speeds of 1} to 6 meters per minute (circumference speed of the roller) can certainly be used.

The apparatus are made in widths (lengths of the rollerg up to 120 cm. that is, suitable for the broa est existing sheets. The length of the sheets to be operated with, is unlim-v such as small holes, scratches etc. so that these do not mfiuence the result unfavourably.

Example 1 Highly-absorbent, mat paper prepared with a solution of 1.8% l-diaethylaminoi-diazoniumchlorostannate 1 gelatine 1 oxalic acid 2 Gummi arabicum reduction agents 2 glucose 2 thiocarbamide (antioxygene according to Moureu) is exposed under a transparent drawing and the print is led through the described apparatus With a speed of 1 meters per minute. In the trough is a solution of the following composition reduction agents.

On leaving the apparatus a perfectly uniformly developed black image has been obtained, which is hardly moist and perfectly dry in a few minutes. If the apparatus is supplied with an extra drying device, the print is immediately perfectly dry. The speed of the apparatus can vary from 1-6 meters per minute circumferential speed of the roller.

. On account of the larger quantity of developer that is taken up with high speed, in

that case a developer is preferably used which is poorer 1n alkali and azodyestuff component but is rich in the other components.

'65 cry of said roller in suc manner Example 2 With the aid of the apparatus described, prints are developed exactly as in example 1 5 "on highly-absorbent mat paper, prepared with a solution of: I

1.8% 1-dimethylamino-3-methylbenzene-4- diazonium-chloro stannate 3% boric acid 0.3% phloroglucinol 0.2% resorcm 1.3% hydroxylaminesulphate 8% glucose 4% sodium citrate reduction agents 2% tartaric acid I 3% thiocarbamide 0.1% hydrochinon antioxygenes The operation is carried out with the de-' scribed apparatus exactly as in examples 1 and 2 and with paper prepared with a solution of:

2% 1diagg-Q-oxynaphthalin-4-sulphonic aci 0.3% phloroglucinol 1.0% oxalic acid,

developer.

What I claim is 1. Apparatus for developing phototypes comprising a roller for applying a developing liquid to the surface of a sheet to be developed, means for supplying developing liquid to the surface of said roller, an elongated non-rotating device having a plurality of spaced toothed members or ressing the sheet against said roller, an means for mounting said device in operative relation with said roller so that said members bear against the sheet with a pressure suflicient to cause the sheet to follow art of the eriphcry of said roller in suc manner, t at the developing liquid is spread upon the surface pf the sheet to be developed in a thin even a er.

Apparatus for developing photo-types comprising a roller for ap lying a developing liquid to the surface 0 a sheet to be developed, means for supplying develo ing liquid to the surface of sa1d roller, ane ongated non-rotating device having a comb for press- 0 ing the sheet against said roller, and means for mounting said device in operative relation with said roller sothat said comb bears against the sheet with a pressure suflicient to cause the sheet to follow art of the eripllliat t e developing liquid is spread upon the surface of the sheet to be developed in a thin even layer.

In testimony whereof I afiix my signature.

ALBERT KARL GOTTHELF HINGST.

'35 whereas a solution as in example 2 is used as

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