US2760864A - Water resistant coatings for photographic paper and method for producing same - Google Patents

Description

United States Patent O inenting. (ci. 95.58,).

This invention relates to` alproess for treating paper with a reSin lateX coating which may er may netherlamented and which may be waterproofeor waterresista'nt'.

Waterproof coatings of paper, fabrics and other absorbent materials arewell known. Various waxes have beennced tciinnart Water recietance. by. lleating tlle. waX treated. material Se that tile.-

Pertneatee tite SticeS cf the material In` addition. VariQnS Syn... teSinS have been need. commercially especially te treat fabricSin the clothinaand. weaving indnetriea P11. cgraphieparlerL has cfteln beennnade. Water reeietantny coating with ancellulose lacquer, but this process isnn- Snitfalale in. certain instances ,fer generalpaper mill.. nte dne te thevclatilennlvents nSedand resnltantltaaarde The above methods have been found generally unsatisfactory in making .a Waterfresis'tant paper which may be. need. pheteataphieally, andv which.. lSf compatible with photographic emnleienet dyes and proceseinglcllentlcala Iier. instance) the nee et a treatment. nlaycance a gelatin eninlSien te peel freni. the. paper. Other. treatments snch as resin coatings from `solvent solutions or ligtnielt Permit abScrntiencf dyes inte.tllteiJaPer1 caating resulting instaining andother objectionable'after eiect'sw. It has also. been fcnndthat Seinecf the. Water-teSiStant enti-.aces perniitretentien cf processing chenicalein-'tlle Paper which later aiect. the. photographic itnageS.-

Accordingly, it is desirable to have a photographic paper base which iseither completelyl or partially resistant to Water and particularly. tolthe processing soluticne in which tlie Paper immersed. Snclitarer. ccnld be rapidly processed Without` retention of the. chemicals in the base and cenld be Saneegeed dry yter. immediate nee- For inetance, Partially reSiStant Steck might been# i'iciently temporarily resistant to Awater orphotographic processing solutionsy to permit contact with a shee'tl'wet vvith water or chemicals for a few seconds Without suf,- licient wetting ef. the. Stcele tocante. cocltle andtnettlecr similar defects and yet have a Waterresistange balanced in such a manner as to be receptive tothe transfer of a gelatin image.

An object of this invention is to provide a waterresistant paper- Which Willpermit/thel application of g a,- tin solutions or other similar Water based materials Withf out repellency, and to Ywhich the gelatin coating adhere during immersion in Water or photographic 'processing solutions. Another object of this invention is to providel a water-resistantcoating which will. have low or ne ligible absorption for chemical dyes, which willhave substantially the saine thermal expansion properties as gelatin, and which will form a continuous lm freeof holes,v A further object is to produce a water-resistant paper WlteSe SlieetS will remain Separate and individual ander pressure in roll form or in cut sheets. Another objectI is to provide paper which resists theabsorption. of water or chemical solutions in such quantity asto cause stain or change in physical characteristics during contat-vpeniods up to sixty seconds. Another.l object is to provide a water-resistant* paper` receptive` to. the. transfer of a gelatin image, but sufliciently WateLreSistantLas-to eliminate exceaewettine t 2: The altere eltiecteate cbtainedgtlncngh cataratta et coating a. .Snltalile bate nlaterlalwitli. a ntintn're cita/s1 resins which forms a good, clear, Water-white `water.- proof iilm. This mixture contains.,essentially'61) a'soft resin latex formed by the polymerization of styrene with butadiene, and (2) aA hardl polystyrene latex. This mixedsystem is unique in` that it has betterlrn forming properties; than, a system. containing the .sameoverall ratio of styrene, to butadiene that isvobtainedf d nringa norni a l fpo1yn 1eri zation. In the. preferred: embodiment of our invention, the mixture ofthe. polystyrene.. resin latex and the styrene-butadiene vresin latex was applied by a suitable method to the face of baryta coated stock. The resin latexcoating, after dryingwaspassedlin front of a Abank of-'infraredheatersat such arateasto bring the.coated,paper. to a temperature between180to 320 Tlhis .-.re.s,ults ixi`,a.Water-resistant paper. coatingcompatibl with gelatincoatings suitableforuses as descrbedfaboxze. The following. examplesv are... given. by.. vvay,y of.: illustra.- tion and it is understoodthatthe. invention is not limited there@ EXAMPLE. I.

A fell. eil? 1b... per. 1QQ0..Saftniietegfapllic. laaae ice Steele Waeceated with twc. .2.0 snif/Sa. inetercaa'ts. .baryta (1.19.6 by weight) en ille face aide. ant/SS1- tneter' ccat' vef' pelyetyrene feSin laten-f.. y tntadiene. laten. .cern inaticn (4515.5 tay'y .c lille Weight). was.. applied .by a.. .Suitable inetllnd te ttt-.e flaca et the baryta coated stock. The resin latex coating, after drying, was passed infront offa bank of infrared heaters at sucha rate as to bring the coated paper to `a temperatureofv 3009' F; at-the lastlheater. A "125 gm-JsQirieter coat composed of-equal parts. (by solids Weight) "ouf l"the above resinlatexmixturefand gelatin then applied-on the face side. This'gel-resin subcoat serves two purposes: (l1.) To prevent blocking between the face side'and vire side coats, and (2) toy act as a subcoat A(bin-rider?) between the resin latex coating and the 'gelatineniulsioin The subcoat-Was also heat treated in the fab-ove described manner. 2Q gm./ sq. meter coat offthe saine reslnla'tex combination was lthen applied` to the vvire side and nheat treated. The paper so coated was sensitized `vv-itiwa"..Suitable photographic emnlsilon.' After normal photographic processing and washing, the excess Water was removed with a tpengeer towel and thepnnt.waS-.sumcientlymy ter reaecnablynennal .landline` Fnrthenten cited that thepaper was-canal tc crfbetten tlianlt eilaneelrent Waterproofness of resin latex coated papeliys. dope coated (celluloseacetate.butyrqtejn siv'enr) paper Latex l Dope .Qeateli Coated.

Moisture Retention l. Y I Hypo Retention 2 1n- 1g Processing size change:

L -.0.4 .2o 10' 39 .0.2" .o 01 .04r l Valley PenetrationT l After minin processing solutions, surface'w'l ed-Wi lry 2 After 1 min; in developer', 10 min; in hypo, 2 mig. wasli. S/Iollllgi'grams per Squaw meh' a.. l; .mwa-o.. 'ZottyllceHnchange sine per lzchange Ln relative humidity. t(30%- 4 l min. developer, 2 min. hypo, 3 min. Water, consecutive exposures. Morsltnro gain, gramsper sq. om. (test for Waterrpernieahilitmfleclinaal-association of the Pulp'andlaper Industry method T 4f1lm).

The Valley penetrationt'e'st is described inT. AIP. P.' T."Inst'r`menta tien Study XVI, Q nrrclaticnBetweenine.Deereeotsizinaasfnetemined by Valley; T-. AJP. PIf'and Currier Methods!" 3 EXAMPLE n Photographic base stocks varying in weight from 2() lb. to 40 1b./ 1000 sq. ft. were baryta coated, resin latex coated, subbed, and sensitized in the manner described in Example I. Testing of the processed photographic stock showed waterproofness comparable to that described in Example I.

EXAMPLE III A suitable photographic base stock was coated with one 20 gm./sq. meter coat of baryta instead of two 20 gm./sq. meter coats of baryta. After resin latex coating, subbing and sensitizing in the manner described in Example I, the stock so prepared showed waterproofness comparable to that of Example I.

EXAMPLE IV A suitable photographic base stock was coated with 20 gm. of baryta having a gelzixe ratio of 1:16 instead of the 1:9.6 ratio described in Example I. After resin latex coating, subbing, and sensitizing in the manner described in Example I, the stock so prepared showed waterproofness comparable to that of Example I.

EXAMPLE V A suitable photographic base stock was resin latex coated and subbed in the manner described in Example I. A 20 gm. coat of baryta (gekxe ratio varying from 1:9.6 to 1:16) was applied over the subbing, and the stock so prepared was sensitized with a suitable photographic emulsion. The stock had waterproofness comparable to that of the stock prepared in Example I.

EXAMPLE VI A suitable photographic base stock was resin latex coated on the face side only and subbed in the manner described in Example I. A 20 gm. coating of baryta (gelzxe ratio of 1:16) was applied to the face side and the stock so prepared was sensitized with a suitable photographic emulsion. The stock so prepared was suitable for very rapid processing where the hot processing chemicals are sprayed on the face side of the stock and the wire side receives no wetting. The stock was also suitable for the chemical or photomechanical transfer of photographic images to the face side without mottle, cockle, etc.

EXAMPLE VII A suitable photographic base stock was coated with 2O gm./sq. meter of baryta (1:9.6, gelziixe ratio) and then was resin latex coated on the face side only and subbed inthe manner described in Example I. The sensitized stock was suitable for the uses described in Example VI.

EXAMPLE VIII A roll of suitable photographic base stock was baryta coated as in Example I except that an additional 20 gm. coat 4of baryta was coated on the wire side. The stock was then resin latex coated, subbed, and sensitized as in Example I with comparable waterproofness.

EXAMPLE IX Samples of suitable photographic base stock were baryta coated with two 20 gm. coats of baryta (1:9.6 gelzxe ratio). The paper was then coated with resin latex combinations in which the polystyrene resin latex to styrene-butadiene latex ratio was varied from 50:50 to 100 (by solids weight). The coatings were heat treated, subbed, and sensitized in the manner described in Example I. While the waterproofness was comparable on all samples, it was found that the optimum range with regards to non-blocking, color, heat and light stability, and general handling properties -was from 50-50 to 40-60 (styrenestyrene-butadiene by solids weight). Below the 40-60 ratio the coatings had a tendency to be yellow and tacky.

EXAMPLE X Baryta coated photographic paper, prepared as in Example I, was coated with a 20 gm./sq. meter coat of polystyrene resin latex-styrene-butadiene resin latex combination (45:55 by solids weight). Samples were heat treated at temperatures ranging from 180 F. to 350 F. (temperature of coated paper at last heater). The samples were then subbed; heat treated at the same temperatures as for the face coating; coated on the wire side and heat treated at the same temperature; and sensitized with a suitable photographic emulsion. All samples showed waterproofness comparable to that of Example I. However, it was found that a temperature range of 240*300 F. was optimum to provide good gloss, antiblocking qualities, and adequate adhesion between the subcoat and latex coat.

EXAMPLE XI Suitable photographic base stock was baryta coated as in Example I. Using a polystyrene resin latex-styrenebutadiene resin latex (45:55) combination, coating weights varying from 10 gm./sq. meter to 30 gm./sq. meter were applied to the face side. Similar weights of the same latex were applied to the wire side after subbing. It was found that the 10 gm. coatings oifered temporary water resistance for some purposes but that 15-20 gms. was optimum for good waterproofness.

EXAMPLE PGI Photographic base stock was baryta coated and resin latex coated on the face side as in Example I. Snbcoatings (1.5 gm./ sq. meter) were applied in which the resin latex to gel ratio was varied from -40 to 30-70 (by solids weight). The wire side coating was then applied and heat treated as in Example I. After sensitizing with the proper photographic emulsion, it was found that the entire range of resin-gel ratios provided adequate emulsion adhesion for some purposes. However, it was found that the optimum range for Vbest adhesion was from 50-50 to 30-70 resin to gel.

EXAMPLE XIII Photographic base stock was baryta coated as in Example I. A resin latex coating composed of from to parts of the poly-styrene resin latex and styrenebutadiene latex combination, and from 30 to 20 parts of gelatin by weight was applied at a laydown of 20 grn./ sq. meter. The coating was heat treated as described in Example I and the wire side coating was applied and heat treated. The resulting stock was sensitized with a proper photographic emulsion and was found to have waterproofness comparable to that of Example I. In addition, `\t was found that the addition of gelatin to the resin latex .combination provided adequate adhesion (for some pur- A roll of suitable photographic base stock was baryta coated, resin latex coated on the face side, and subbed with proper heat treatment between coatings. Then two consecutive 10 gin/sq. meter coatings of the same resin vlatex were applied to the wire side instead of one 20 igm./ sq. meter. Each coating was heat treated separately. After sensitizing with the proper photographic emulsion, it was found that the dual l0 gm. coatings prevented the penetration of the processing chemicals through weak spots in the coating when the stock was under the cinching pressure of the standard roll processing equipment or when there was considerable hydro-static pressure as in deep tank processing.

The above examples show our use of the water-resistant coating to paper to be used for photographic purposes. However, the coating mixture shown above could also be applied to any suitable absorbent base material such as cloth, leather and the like. In addition, various coating methods may be used in applying this resin composition to the paper. As can be seen from the above examples, there may be variations in the paper stock weight, number and weight of baryta coatings, gelriixe ratio in the baryta, position of the resin and baryta coatings, ratio of polystyrene to styrene-butadiene, temperature of heat treatment, resin coating weight, subbing formula and amount of gelatin, if any, added to the coating mixture.

The polystyrene resin which we use for 100% polystyrene contains from 32 to 50% resin solids. The styrene butadiene latex contains from 60 to 67% styrene and from 40 to 33% butadiene and has 43-55% solids.

Various coating means may be used which are within the scope of our invention. For example, a reverse roll coater, air knife doctor, coating hopper or the like may be used. Heating methods include infrared heaters, infrared blankets, and any other suitable method to obtain the desired temperature. Heat treating temperature is referred to above as the temperature of the coated paper as it passes in front of the last heating unit. Generally, the paper is passed in front of the heaters at such a rate as to obtain the temperature in about tifteen seconds, but this time is not considered critical and other time periods may be used to accomplish the purposes of this invention.

In photographic uses it is advantageous to apply a subbing coat over the waterproof coating as shown above in Example I. This subbing coat is applied from a water system and acts as a binder between the resin coating and photographic emulsion coating. However, it is also advantageous to add gelatin to the resin coating mixture. The resulting coating permits the application of a photographic emulsion directly on the water resistant surface without additional subbing.

This process for forming a water-resistant and waterproof coating for paper meets a need in the photographic industry for a waterproof surface which is compatible with a gelatin emulsion, and which resists staining by photographic dyes and chemicals.

In view of the many changes and modifications which may be made Without departing from the principles underlying the invention, reference should be made to the appended claims for an understanding of the scope of the protection afforded this invention.

We claim:

1. A process for preparing a photographic brous sheet base material comprising the successive steps of coating the material with a coating containing baryta, drying, coating with a mixture containing from 40 to 60% polystyrene resin latex and from 60 to 40% styrene-butadiene resin latex, drying, and heating to a temperature between 180 to 320 F., applying a subcoating containing from about 30 to 70% gelatin and from 70 to 30% of a mixture containing from 40 to 60% polystyrene resin latex and from to 40% styrene-butadiene resin latex, drying, and heating to a temperature between about 180 to 320 F., and coating with a photographic gelatin emulsion containing light-sensitive silver salts over the subcoating.

2. A process according to claim 1 wherein the base material is paper.

3. A process for making a photographic fibrous sheet base material comprising the successive steps of coating the material with a mixture containing from 40 to 60% polystyrene resin latex and from 60 to 40% styrenebutadiene resin latex, drying, and heating to a temperature of about 180 to 320 F., applying a subcoating containing gelatin and a mixture of from 40 to 60% polystyrene resin latex and from 60 to 40% styrene-butadiene resin latex, drying, and heating to a temperature between 180 to 320 F. and coating with a photographic gelatin emulsion containing light-sensitive silver salt.

4. A process according to claim 3 wherein the base material is paper.

5. A process for making a photographic paper comprising the successive stepsv of coating the paper with a mixture containing from 30 to 70% gelatin and from to 30% of a mixture containing from 40 to 60% polystyrene resin latex and from 60 to 40% styrene-butadiene resin latex, drying, and heating to a temperature between about to 320 F., and coating with a photographic gelatin emulsion containing light-sensitive silver salts.

6. A water resistant photographic paper produced in accordance with the process described in claim 1.

7. A water resistant photographic paper produced in accordance with the proces described in claim 2.

8. A water resistant photographic paper produced in accordance with the process described in claim 3.

9. A water resistant photographic paper produced in accordance with the process described in claim 4.

10. A water resistant photographic paper produced in accordance with the proces described in claim 5.

References Cited in the le of this patent UNITED STATES PATENTS 2,284,877 Martinez June 2, 1942 2,491,023 Alles et al. Dec. 13, 1949 2,574,439 Seymour Nov. 6, 1951 2,614,089 Harrison et al. Oct. 14, 1952 2,614,093 Wheelock Oct. 14, 1952 2,650,163 Horsey et al. Aug. 25, 1953 FOREIGN PATENTS 644,022 Great Britain Oct. 4, 1950

Claims (2)

1. A PROCESS FOR PREPARING A PHOTOGRAPHIC FIBROUS SHEET BASE MATERIAL COMPRISING THE SUCCESSIVE STEPS OF COATING THE MATERIAL WITH A COATING CONTAINING BARYTA, DRYING, COATING WITH A MIXTURE CONTAINING FROM 40 TO 60% POLYSTYRENE RESIN LATEX AND FROM 60 TO 40% STYRENE-BUTADIENE RESIN LATEX, DRYING, AND HEATING TO A TEMPERATURE BETWEEN 180 TO 320*F., APPLYING A SUBCOATING CONTAINING FROM ABOUT 30 TO 70% GELATIN AND FROM 70 TO 30% OF A MIXTURE CONTAINING FROM 40 TO 60% POLYSTYRENE RESIN LATEX AND FROM 60 TO 40% STYRENE-BUTADIENE RESIN LATEX, DRYING, AND HEATING TO A TEMPERATURE BETWEEN ABOUT 180 TO 320*F., AND COATING WITH A PHOTOGRAPHIC GELATIN EMULSION CONTAINING LIGHT-SENSITIVE SILVER SALTS OVER THE SUBCOATING.

6. A WATER RESISTANT PHOTOGRAPHIC PAPER PRODUCED IN ACCORDANCE WITH THE PROCESS DESCRIBED IN CLAIM 1.