US1926614A - Fixation of dyes on colored paper - Google Patents

Description

Patented Sept. 12, 1933 UNITED STATES 1,92%,tl4 Y PATEN FIXATION F DYES 0N COLORED PAPER No Drawing.

Claims.

This invention relates to a method for'the fixation of the dyes on colored paper and more particularly to a method for rendering the dyes present on surface colored paper non bleeding 5. or relatively fast to the action of water and relates also to the resulting product.

In the art, it is often the practice to color paper after the sheet as been formedrather than by adding the dye tufi to the pulp when in the \1 J tion is. carried to the sheet upon the surface of v a roll is often accomplished by placing dye boxes upon the calender stack in contact with the calender rolls. Coloring and calendering are thus accomplished in one operation and the process is known as calender dyeing.

Acid dyes are usually preferred for surface coloring because they possess great tinctorial value and brightness 'of shade with satisfactory iastness to light. On the other hand, since the acid dyes have 'very little afinity for cellulose, they are held to the surface of the dry paper after it has been colored by any of the above processes merely by mechanical forces. Although 1 direct dyes have much more real amnity for "cellulose than acid dyes, paper which has been surface colored with direct dyes also bleeds much more than paper. which has been dyed in the beater because much of the direct dye likewise When paper so colored comes into contact with water, a partial resolution of the dye occurs. This is objectional for two reasons: First, the appearance of the paper is harmed by the resulting spots and streaks; Second, any nearby object coming into contact with the paper in the presence of water is badly This invention as anobject the rendering of the dyestufif on surface colored paper relatively insoluble in water. This object be accomplished by the following invention. Paper, surface colored with'acid or direct dyes either in the wet or state, is mm ith in. guanidine in excess of the theoretical ount required to precipitate the dye. The complex formed by the w n' dine is held to the surface merely by mechanical forces.

, of a weak acid exhibits less tendering action :1

Application July 24, 1931 Serial No. 553,008 1 with the dye is relatively insoluble in. water. However, the presence of excess diaryl guanidine causes more complete precipitation which results in less tendency for the dye to bleed.

My invention is generally applicable in connec- W tion with all dyes that-are characterized by the presence of acid groups, such as, for example, the sulfonic acid or carboxylgroups, indeed to all dyes which give rise to colored anions when dissolved in aqueous solution. It is also in. many cases of advantage to use a penetrating agent, such as, for example, methyl or ethyl alcohol or a higher alcohol.

The process may be applied to calender dyeing by placing a box uponthe calender stack in such a position that the paper, after being coated with the dye solution contained in one box, is coated with diaryl g'uanidine solution contained in a second box. For example, the process may be satisfactorily applied, in this manner to Kraft. 7 lined container board The dye solution con-- taining 9 pounds 10 ounces of metanh yellow (C. I. No. 138)- in 216 gallons of water is applied irom' the top box on the calender stack. An approximately 10% solution ofdiphenyl guani dine hydrochloride is prepared by pasting" 6' pounds 10 ounces of diphenyl guanidine with 3 pounds 3 ounces of concentrated (38%) hydrochloric acid and'diluting to eight gallons. This solution is applied continuously to the board from 35 a lower box on the calender stack after the board has been colored from the box on an upper roll.

When-surface dyed paper is dipped or calendered in a solution of diphenyl guanidine hydro:-

chloride which contains enough free hydrochloric acid to be acid to Congo red, e. g. an excess of I a% over theaniount necessary to form the hydrochloride, and is then heated in an oven, at me C. for an hour, the tensile strength of the paper is decreased more than 25%. The tearing strength is probably decreased still more. It is therefore desirable to prepare the solution of the diaryl guanidine for after treatment in such a way that it does not contain an excess of strong acid. j 1% Weak acids, such as acetic acid and hydrofluoric acid, the advantage for forming a soluble salt 'of th diaryl guanidine so that an exces a @mparable excess of a strong, or highly io'. 1 acid. The character of the acid'employed to dissolve-the new dine has nothing to do with the property of the yl guanidine in rendering the dye inmluble so long theacid in question b the free base into solution spi ficiently that it can react with the dye. Experiments show that dyed paper is not tendered be- .cause of after treatment with a salt of diaryl guanidine when the solution employed for after '-treatment is neutral in reaction, even when the in the dry state by evaporation of the aqueous .solution., Th'edry salt is not very hygroscopic and yet dissolves readily; it is convenient to handle and to ship and possesses the advantage of containing no excess acid even when the solution from which it is made-by evaporation is slightly acid., s

The dyestufi may be any acid or. direct color or any combination of dyes from these twoclasses. Direct dyes-form non-bleeding complexes upon treatment with solutions containing approximate-' ly one-eighth molecular weight of diaryl guanidine per liter of solution. Acid dyes require higher concentrations of the diaryl guanidine, yarying from one-eighth molecular weight per liter to, one molecular weight per. liter. It will. be understood that the amount of diaryl guanidine required tobring about a fairly complete precipi-v tation of the dye, will vary with each individual case and is dependentupon'the solubility of the complex formed, upon the number of acidic groups im'the dye, upon the depth of shade of the dyeing, 'upon the absorbency of the paper,

and upon the method by which the treatment is carried out. For these reasons the diaryl guanidine solution may .vary in concentration from' relatively soluble, such as guinoline yellow Conc.

plied by the calendering method satisfactorily (C. \I. No; 801) and tartrazine O (C. I.--No. 640) when fixed by the calendering process. Acnefourth molar solution of diaryl guanidine apfixes any of the following direct dyes which have Q been applied to the surface, of paper:

Du Pont brilliant paper yellow Conc. (.C. I. No. 364), Du Pont stilbene yellow G Gone. (0. I.

' No. 622), pontamine fast scarlet 4138 (C. I. No.

326), pontamlne fastred BBL (C. I. No. 278), pontamine sky blue 63X (C. I. No. 518), p0ntamine green GK ((3. I. No.r594), pontamine black E (C. I. No. 581) et cetera. 1

Acid dyes such as pontacyl green NV Conc.

' (0. I. 'No. 735), pontacyl fast blue R (c. I. No.

208), pontacyl'fast violet 103 (C. I. No. 696),

- Du Pont crocein scarlet N Extra (0.1. No. 252) and Du Pont metanil'yellow Conc. (C. I. No. 138) may be satisfactorily rendered non-bleed-. ing by coating sheets, surface coloredwith these- -dyes in moderately heavy'shades, with ahalf molar solution of diaryl guanidine by the calen-. dering process. some acid dyes, such as pontacyl blue black SX- (C. I. No. 246) Du Pont naphthol green B (0.1. No. 5) and poritacyl violet 43L -(C. I. No. 693), require a diaryl guanidine'solution of lower concentration for fixation than the I 252), diluted to one gallon. Paper surface dyed with the above solution is rendered non-bleeding by passage between rolls one of which carries-a proper concentrations paper.

film of one-fourth'molar diphenyl guanidine hydrochloride solution.

Any diaryl-guanidine may be employed as the I fixing agent. Diphenyl, di-o-tolyl, di-o-an-isyl, di-p-phenetyl, etc. may be utilized or triphenyl- 8 0 guanidine may be employed- Further, any acid giving to the diaryl guanidine the required solubility in-water may be used. Diphenyl guanidine hydrochloride is 'to be preferred on the basis of cost. Also, since the hydrochloride of diphenyl guanidine can be made into stock solutions containing as little as 10% water, it is more convenient to apply than the sulfate which has a much lower solubility in water.,'.- The acetate is very soluble in concentrated solutions, but hy- 9 drolyzes considerably 'upon being diluted to the for use in treating colored {The above process may be modified by applying'the fixing agent previous to the dye. Alcohol or other penetrating agents'may be added .to either dye or fixing solution. The free base'of an ,aryl guanidine maybe applied from an ,alcoholic solution if desired, although organic solutions possess the-disadvantage of greater cost.

'The paper may be given a double treatment ,of the fixing bath to secure less bleeding'of the be used to apply the di lguanidme to the paper. The dyed paper may be either wet or dry when after-treated.

The invention may be used in fixing dyestuffs upon board, wrapping, tissue, crepe, absorbent, building, cardboard, cover, news, printing or writ- 0 ing papers. In general, the processis applicable to any surface dyed paper requiring water-fast. colors. The paper produced by the process here disclosed can be moistened with drops of water and 16 the dye thereon will not spot or' run from the paper as with surface dyed paper produced by the usual methods in which the water soluble-dye is not rendered insoluble but is dried into the sheet.

and allowed .to remain in its original form. The D disadvantages of dyed paper fromwhich the dye will bleed are that such paper when wet stains the hands or clothing or articles which maycome in contact with it and that drops of water cause an unattractive spotting of the surface of the paper. 2

The aryl guanidines possess the great advantage over certain other organicbases, such as the naphthylamines, vbenzidene and 5-ethoxy-1-aminobenzothiazol which are also effective in preventing the bleeding of surface colored paper, that the aryl guanidines affect the fastness to light much less than other organic bases.

'As many, apparent and widely difl'erent embodiments of this invention may be made without departing from thespirit thereoffit is to be understood that I do not 1mm myself to the foregoing examples or descriptions except as'lndicated in the following claims.

I claim:

prises applying a dye containing an acid group thereto and-fixing said dye by applying to the dyed paper a substance of the group consisting of diand tri-aryl guanidines.- 2. The method of coloring paper which com- 5 prises applying-a 'dy'e containing an acid group thereto and fixingsaid dye by applying to the dyed paper a: diaryl guanidine.

'3. The method of coloring paper which comprises applying a dye containing an acid group 1 1. The method of coloring paper which comthereto and fixing said dye by applying to the dyed paper diphenyl guanidine.

4. The method of coloring paper which comprises applying a dye containing an acid group thereto andfixing said dye by applying tothe dyed paper diphenyl guanidine in concentration exceeding about one-eighth mol per liter.

5. The method of coloring paper which comprises applying a dye containing an acid group thereto and fixing said dye by applying to the dyed paper diphenyl guanidine in concentration from about 0.5 to 25 per cent.

I 6. The method of rendering dyed paper nonbleeding to water which comprises treating paper, dyed with a dye containing an acid group with a solution of a diaryl guanidine in excess of the theoretical amount necessary to precipitate the dye.

Patent N0. 1,926,614.

/ cm z. BRAVES.

. centr c-Amos connection.-

a. Paper dyed with a dye containing an acid group of improved non-bleeding quality comprising a diaryl guanidine as a fixative.

9. Paper dyed with a dye containing an acid group of improved non-bleeding quality comp'rising diphenyl guanidine as a fixative.

10, Paper dyed with a dye containing an acid group of improved non-bleedingrquaiity comprising diphenyl guanidine in excess of the theoretical 7 amount necessary to precipitate the dye.

1 CARL 'Z DRAVES.

with 12. 1933.

It is herebyeertiiied' thatv error-appears in the printed specification of the above numbered patent requiring correctionas follows: "Page 3, lines 84. -8 7, and 90, claims 8, 9, and 10,- respectively, after "group" insert the words and being; and that the said'Letters Patent should be read with these corrections therein that the same may' conform to the record'oi the case in thcglltcnt Off ice.

sen

'Signed and sealed jth'is Zthdfly of November,

Hcpkim I Act'in gfdl omiaaioner of