US2119164A - Coated paper - Google Patents

Description

Patented May 31, 1938 PATENT OFFICE 'coA'rEn PAPER Samuel S. Himmell, New York, N. Y.

Nb Drawing.

' 8 Claims. My invention relates to a new and improved coated paper, of the type which is generally des- ,ignated as enamelled paper.

This application is in part a continuation of my application Ser. No. 739,635, for improvements in Coated paper, filed August 13, 1934.

One of the objects of my invention is to provide an improved coated paper, which can be suitably identified by means of the trade-mark or the like of the paper manufacturer, without the necessity of using a water mark.

Another object of my invention is to provide an improved coated paper, which can be used like any ordinary coated paper which is oriii-v narily used for half-tone printing, and in printing books, magazines, or for any other purpose. Said coated paper has a suitable identifying mark or .marking imprinted upon the base stock thereof, andsince a water mark is eliminated from the base stock, the improved paper has a smooth surface layer or coating. This coated paper is preferably coated on both sides of the base stock. Another object of my invention is to print a suitable'identifying mark or marking upon one :5 side of the white base stock of the paper by means "of a suitable ink having a white color, prior to coating the paper. By using a suitable ink and a suitable method of printing, the white marking is printed upon the white base of the paper, withto out substantially indenting or injuring the surface of the base of the paper in any manner. When paper of this type is suitably coated, the marking or markings are substantially invisible, save when the paper is viewed by means of trans- ;5 mitted light". This type of paperis sufliciently permeable to light, so that the paper can be held up to the sunshine or to a suitable electric bulb, and the identifying marking is then clearly visible by transmitted light. The white identifying 40 marking is not masked by the white coating or coatings under transmitted light; if said white marking isof proper composition.

Another object of my invention is to provide an improved-white marking, which will not blend 45: or coalesce with the surface coating material, so

that the identifying marking remains clearly visible when the paper is viewed by means of transmitted light.

Other objects of my invention will be set forth 50 in the following description, which illustrates preferred embodiments, it being clearly understood that the above general statements of the objects of my invention are to generally explain the same, without limiting the invention in any 55 manner.

Application 0a.]... as, 193 Serial No. 107,949

In my previously issued Patent No. 1,825,796, issued by the United States Patent Oflice on October 6, 1931, I have disclosed a safety P p However, in putting this idea into actual use, if the identifying mark is printed by means of an 5 ink which has a color contrast with the .white base stock, it is necessary to use a thick layer of coating material upon one side of the paper, in order to secure the results desired. Such paper is suitable for manufacturing labels or the like,

but it is not suitable for manufacturing an ordinary coated paper, which is to be identified by the name or trade-mark of the manufacturer of the paper. A coated paper for printing labels can be and is coated on only one side thereof, but an ordinary coated paper must be coated on both sides thereof. When I refer to ordinary coated paper, I mean an enamelled paper which is used for ordinary printing purposes, like booklets, circulars, folders, etc. as distinguished from paper which is used for making labels or the like.

According to my invention; I print by means of a suitable white ink, upon the white base stock of the paper. This ink can-be made by grindinga suitable opaque and finely ,divided white pigment together with a small amount of aluminumpowder, into a water-color base or varnish; The aluminum powder is in finely divided metallic form. After the aluminum powder and the white pigment have been ground into the water-color varnish, water can then be added to said mixture in order to dilute it, with thoroughintermixing, in order to produce an-ink having the desired consistency which is required for proper printing on the press. Thewater-color varnish 35 is made) by dissolving in water, a suitable water soluble gum such as gum arabicor gum tragacanth. .Likewise, any of the dextrines could be "dissolved in a mixture of glycerine and water. For example, and without limiting myself to the ingredients or proportions or materials mentioned herein, I can take ten parts by weight of water-color varnish, mix this with five parts by weight of white titanium oxide, dilute this with five parts by weight of water, and I then add one sixteenth part by weight of aluminum. powder in the finely divided metallic form. Hence the proportion of the aluminum powder is about one per cent of the proportion of the titanium oxide. While the use of aluminum or like metallic powder is advantageous, the invention is not limited to the use of a metallic powder pigment. The. white titanium oxide can be used alone as the pigment.

The water-color varnish may be made according tolariousformulas, and since water-color varnish is well known per se, no further description there- Of is necessary.

Likewise the proportions specified in the above formula may be varied in order to produce printing inks of various consistencies, and of different covering power;

The titanium oxide is an opaque white pigment. The aluminum powder is a satisfactory and unique coloring agent for the purposes of my invention,

since it is almost colorless by reflected light. Un-

der reflected light, the aluminum powder has a. silver grey appearance, which does not form an objectionable color contrast with the white base stock of the coated paper. Hence the applied or imprinted marking becomes substantially invisible after the paper has been coated. and the coated paper is viewed by reflected light. However, when the paper is viewed by transmitted light, the aluminum powder gives a very dark opaque grey color effect or contrast relative to the light-permeable paper base stock, and the light-permeable coatings, so that the imprinted marking is then clearly visible. This color contrast under transmitted light is visible, after the paper has been given the normal coating on each side of about eight to thirteen pounds of coating per ream (500 sheets) of paper, each said sheet having dimensions of twenty-five inches by thirty;-eight inches. If the marking were printed by means of a tinted ink instead of with a white ink, it would be necessary to use a much heavier coating on each side of the paper of from 23 lbs.

to 30 lbs. on each side of the paper, in order to render the marking invisible by reflected light, and

such paper would be too brittle, and each paper.

could not be used practically.

Another formula for a white ink which will not blendor coalesce with the white surface coating or coatings is as follows:-

Titanium oxide lbs-- 1% Transparent lithographic varnish ..-lb 1 Standard paint dryer --os. 1

This ink has an oil base instead of a water-color base. so that the invention is not restricted to the base of the ink.

The paint dryer may be of any suitable type which is used for producing the rapid drying of paint in paste form. For example this dryer may be a cobalt dryer (cobalt resinate) which may be dissolved in mineral spirits. The cobalt resinate may be dissolved in an equal weight of mineral sp rits.

Likewise. while I have mentioned aluminum powder as being a highly desirable ingredient, I do not wish to be limited to any particular metallic powder, as other metallic powders could be sub- 'stituted, and .a suitable non-metallic pigment could be used without a metallic pigment, in order to produce an opaque white marking. having the necessary properties.

The improved ink prints sharply and it dries almost immediately in a heatedatmosphere, so that the paper roll can be'wound on a drum immediately after it is passed through the'printing Dress.

Hence the printing press can be used as an attachment in connection with the paper making machine, so that the printed paper can be wound up immediately on a suitable reel or the like.

The white coating of the paper may include well-known ingredients, namely, clay, starch or casein, and a suitable pigment, such as "satin white". This is a mixture of gypsum mixed with alumina, or a mixture of aluminium sulphate with calcium sulphate. The invention is not limited to a white coating, since paper having white base stock and having the trade-mark or the like imprinted thereon by means of white ink, can have a coating of any suitable color applied thereto.

White printing inks have hitherto been known and they have been used for special purposes in the printing art. However, certain special problems are presented in providing a light-permeable white paper stock and having a light-permeable which is applied in the form of an aqueous suspension.

For example, I have found that if a white ink is made with white pigment such as magnesium carbonate or aluminium hydrate, a satisfactory paper is not secured. if an oil base is utilized. such as the linseed oil varnish previously mentioned using such a formula marking on the coated paper is clearly visible by reflected light, and said marking is either wholly or almost wholly invisible under transmitted light. The yellow tint of the oil base renders said marking clearly visible under reflected light, and said marking either blends with the coating. or is masked by the coating, if the coating is of the usual and well known type.

Likewise, if a'water-eolor ink is used, the watercolor varnish base of said ink also has a tint, and the same objectionable results are secured, if the pigment which is utilized is magnesium carbonate alone, or aluminium hydrate alone.

By using a suflicient proportion of a pigment such as titanium oxide. the tint of the base of the ink is masked under reflected light, and the marking is clearly visible when the coated paper is viewed by transmitted light. Likewise the clay coating can adhere to the printed marking. Titanium oxide has high covering power, so that it is unnecessary to use an excessive proportion of pigment in the ink. 11 the ink has too much pigment, said ink tends to cake in the printing press, or it tends to crumble oi! the paper. after the printing. I have also found that if zinc oxide or lithopone is used for making white inks according to the usual formulas, such formulas are not satisfactory, because the inks are either visible under reflected light, or such inks blend substantially with the clay and pigment coatings, so that the markings are not sufficiently visible under transmitted light.

Likewise I prefer to use a base paper which is designated in the trade as "antique" paper. although I do not wish to limit myself to the use of "antique" paper.

It is customary in certain cases to calender the paper base stock prior to coating. The paper base stock which is known in the trade as "antique" paper is not calendered, so that such paper substantially retains its rough surface, as compared with papers which are calendered prior to the application of the coating so as to give them a smooth polished surface.

The rough surface of the "antique" paper serves to take up the white printing ink so that this aids in causing the white marking to remain English finish paper, which has been calen-' dered to some extent prior to the application of 3 the coating.

- Likewise I prefer to print the white'marking on what is known as the felt side of the paper, although I may print the white coating on the wire side of the paper, without departing from the invention.

Generally speaking, the invention covers the use of a white marking ink having a sufllcient proportion of white pigment of sufficiently high hiding or covering power, so that the white pigment masks the tint of the water base or of the linseed oil base, the proportion of pigment being sufliciently low to prevent the ink from caking in the press or from crumbling off the paper. Likewise the ink should dry almost immediately in the heated atmosphere of the ordinary paper mill and the maximum drying period should not exceed twenty-four hours, so that suflicient drier must be present in the ink and the ink must not contain an excess of pigment.

I prefer to print the white marking upon the white base of'the paper, by means of the direct or offset process, using soft-and yieldable printing members,.such as rubber'plates-so that the surface of the paper base is not substantially indented, and the printed surface of the paper base stock remains smooth.

Likewise a rubber printing plate deposits a very thin layer of the ink, so that the coating composition adheres to the printed part of the I paper base stock, even if an oilbase is used. If

a sufficient proportion of pigment is used in the marking composition, the clay coating can wet and adhere to the particles of pigment in the marking.

The paper base stock may be sized or otherwise treated, so as to secure clear printing on said paper stock. In order to distinguish from paper having a coating of wax or the like, which coating cannot be printed upon, I further identify my invention by stating that the improved paper has a coating of the clay type, which can be printed upon in the usual manner. usually provided with a casein binder.

'Whenever I refer to a white marking, in the description or claims, I wish to include a marking having a sufliciently light or faint tint, so

that said marking is substantially invisible, save when the paper is viewed by means of transmitted light, when a paper is used which is coated on. 1 both sides, said paper having the usual thickness of coating, and being suitable for the purposes previously described. \I

When I specify that the marking is substantially invisible by reflected light and clearly visible by transmitted light, I refer to a paper having a printed marking'which in these respects is similar to an ordinary watermark.

The printed marking is very thin, since the pigment is at least partially absorbed by the paper base.- Hence, when the coating is applied after the printed marking has dried thoroughly, the layer of coating is smooth and of substantially uniform thickness throughout. In this respect, the improved paper is superior to an enamelled watermarked paper, because the watermarking is made by a species of embossing which causes the coating to sink therein, thus producing a surface This clay coating is pigments which accomplish the aforesaid purposes.

I have shown and described preferred embodiments of my invention, but it is clear that numerous changes and omissions could be made without departing from its spirit.

I claim;

l. A coated and light-permeable paper having a coatingron each side thereof, said coating being light-permeable and being of the clay type and being adapted to receive a printed impression, the weight .of the coating on each side corresponding substantially to from eight to thirteen pounds 'per five hundred sheets of paper each of which is twenty-five inches by thirty-eight inches, said coated paper having white and light-permeable paper base stock, said paper base stock having a substantially white marking imprinted thereon,

said marking being more opaque than said paper and said coating, said white marking comprising ,a coating of the clay type, said coated paper having light-permeable and white base stock, said paper base stock having a marking imprinted thereon which is covered by said coating, said marking having a substantially white color and including a white non-metallic pigment and alu- 'minum powder, said aluminum powder comprising-about one per cent by weight of said nonmetallic pigment, said aluminum powder being substantially colorless under reflected light and having a dark appearance under. transmitted light, said marking being substantially invisible by reflected light and being visible by transmitted light.

3.A coated and light-permeable paper having a coating of the clay type, said coated paper having light-permeable and white paper base stock,

said paper base stock having a marking imprinted thereon which is covered by said coating, said I marking having a substantially white color, said and a smaller proportion by weight of an alumimarking having a white non-metallic pigment num powder, said aluminum powder being substantially colorless under reflected light and having a dark appearance. under transmitted light, the proportion of said aluminum powder to said white non-metallic pigment being such that said marking is substantially invisible by reflected light'and it is substantially visible by transmitted light.

4. A coated and light-permeable paper having a coating which comprises clay intermixed with a coating pigment and a binder, said coated paper having light permeable and white paper base .stock having a white marking imprinted thereon base 'or'the marking, the proportion of titanium.

oxide beingsufllciently low to make the marking composition non-caking and non-crumbling. said white marking being substantially invisible by reflected light and being visible by transmitted -light, t'he white pigment oi the coating being other than titanium oxide.

5. A'coated and light-permeable paper having a coating which comprises clay intermixed with,

a coating pigment and a binder, said coated paper having light-permeable and substantially white paper base stock having a white marking imprinted thercon and covered by said coating, said white marking including titanium oxide and a base for said markingwhich has a non-white tint, the proportion of titanium oxide in said marking being sufllcient substantially to mask the non-white tint of said base of the marking under reflected light, the proportion 01' titanium oxide being suillciently low to make the marking composition non-caking and non-crumbling, said marking beingsubstantially invisible by reflected light and being visible by transmitted light, said paper base stock having a rough surface.

-6. A coated and-light-permeable paper having a coating which comprises clay intermixed with a coating pigment and a bindensaid coated paper having light-permeable and substantially white pap r base stock having a white marking imprinted thereon and covered by said coating, said white marking including titanium oxide and a base for said marking which hasa non-white tint, the proportion of titanium oxide in said marking being sumcient substantially to mask the non-white tint of said base or the marking under reflected light, the proportion of titanium oxide being suiiiciently low to make the marking composition non-caking and non-crumbling. said marking being substantially invisible by reflected light and being visible by transmitted light, said paper being coated on both sides thereof, the

said coating, the color of said white marking blending with the color of said coating so that said marking is substantially invisible by reflected light, said marking being visible by transmitted light.

8. A coated and light-permeable paper having a substantially white coating having clay and which includes a coating pigment, said coated paper having a substantially light-permeable paper base stock having a white marking imprinted thereon and covered by said coating, said paper base stock having said coating on each face thereof. said white marking including tita-' nium oxide and being more opaquethan said coating, the color 01' said marking blending with the color of said coating so that said marking is substantially invisible by reflected light, said marking being visible by transmitted light, said marking having such composition that the dry marking can'be wetted by the aqueous suspension of the coating.

SAMUEL B. HIMMEIL.