US2904434A - Plasticization of gelatin - Google Patents

Description

2,904,434 PLASTICIZATION OF GELATIN Kirby M. Milton, Rochester, N.Y., assignor to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey N'o Drawing. Application May 31, 1957 Serial No. 662,564

7 Claims. (Cl. 96-94) This invention relates to the plasticization of gelatin and'ofphotographic gelatin emulsions by means of lower alkyl esters of ethylene bis glycolic acid.

Some materials such as glycerin or other polyols are known to plasticize gelatin probably because of their possible interaction with gelatin or their hygroscopicity. The use of suflicient amounts of those polyols to efiectively plasticize photographic emulsions at low humidities may be undesirable because of the physical and sensitometric properties they exhibit at high humidities and tempera.- tures. It has been previously recognized that certain polyethylene glycols may be useful in silver halideemulsions to improve anti-static properties, sensitometric properties and coatability. However, there has never been any statement in the art pointing out any unusual value of these glycols for gelatin plasticizing purposes.

One object of my invention is to provide gelatin coating compositions which give coatings having good flexibilities. Another object of my invention is to plasticize photographic gelatin layers and photographic films contaifiiiig those layers. A further object of'rny invention is to plasticize gelatin employed for photographic purposes'without any adverse physical or sensitometric effct's as might result from many currently knowngelatin plasticiiers'.

I have discovered that the above objects may be obtained by incorporating in gelatin coating compositions lower alkyl esters of ethylene bis glycolic acid in the amount of 40% based on the weight of the gelatin. The esters which have been found to be particularly suitable for this purpose are the dimethyl, diethyl and di- (ethoxy substituted ethyl) esters of ethylene bis glycolic acid. In those cases where the coating is dried under Very drastic conditions, it is desirable to-have as much as. 15%v (based on the weight of the gelatin) of the ester in. the. gelatin composition. With less drastic drying conditions, smaller amounts of the ester are used. The methyl'ester is preferred in that it appears to be useful in all situations which are encountered in the formation of -gelatin coatings. I have found that up to 40% of the plasticizer in accordance with my invention (based on the weight-of the gelatin) can be tolerated in gelatin coatings without giving riseto softness or tackiness at high humiditie's. The following examples illustrate my invention:

Example 1 Several gelatin skins and gelatin-silver halide photographic emulsion skins were prepared by coating out aqueousvsolutions comprising 8% of photographic gelatin and the indicated percentages of plasticizer onto stripping type plates so that skins of 4 mm. thickness were obtained; The skins were cured at 70 F. and 70% R.H. until dry, were stripped from the plates, slit to widths of 15 mm. and conditioned to 70 F. and 20% R.H. Folding endurance was tested with an MIT fold tester using a tension of 1 kg. and jaws of 0.0155 inch radius Patented Sept. 15, 1059 of curvature with a separation of 0.01 inch. The following results were obtained:

MIT folds at 20% R.H.

Percent 1 Plasticlzer Gelatin Emulsion skins skins 0 None of] Ethylene bis (methyl glycolate) O 1 5 rl n 20 dn 1 Parts per 100 parts of gelatin.

Example 2' Tackiness Brittleness, Sward 70 F., 15% R.H. Rocker Ooefiicient oi 709 EL, ,irictiome'mul- Per- Plasticizer 80% sion to emulsion cent R.H..

g Wedge; MIT Damp.-. 70 F4, 70." F

in. folds ing 50% 70% time, RLHI' 'RJH.

sec.

o None .28 o 41 .39. 1.34

20:..- Et ylenebis I (methyl glycolate) .18 l9 38. .33. 7.39

1 This value is believed to be a measure of tackiness and/or softness. Increased tackiness and/or softness is shown by a decrease in Sward Rocker damping times and an increase in the coefiicient of friction values. Increased flexibility is shown by a decrease in wedge-brittlenessivalue and by an increase in MIT fold value.

Example 3 Compositions were prepared from a negative type photographic emulsion, plasticized with various contents of plasticizer. The resulting emulsions were coated on cellulose acetate support and dried at F. wet bulb and 120 F. dry bulb temperature. The films obtained were tested and the results were as follows:

Tackiness Brittleness, Sward v I 70 F., 15% R.H. Rocker; Coefficient of I 70- F;, friction, emul Per- Plasticizer sionto emulsion cent R.H.

Wedge, MIT Damp-. 70 F;, 70F.,. 1n. folds ing 50% 70% time, RH .RJEL

sec.

0 None; 0.22 1 44 15. Ethylene bis- (methyl glycolate 12 17 43 .16 20 42 .18 20 40 .16 25 43 .19 24 40 Glycerin .19 16' 22 Example 4 Skins were prepared from gelatin and from a silver halide photographic emulsion in the manner described in Example 1 using various plasticizers. The skins so obtained were tested and the results were as follows:

MI'l folds at 70 F., 20% RH. Percent Plastlcizer Gelatin Emulsion sheets sheets N one 24 14 20 Ethylene bis (methyl glycolate) 33 56 20 Ethylene bis (ethyl glycolate) 71 20 Ethylene bis (Z-methoxyethylglycolate). 73 138 20 Ethylene bis (2 (2- methoxyethoxy) ethyl glycolate) 77 135 Example 5 Plasticized negative-type photographic emulsions were coated onto cellulose acetate film base in the same manner as described in Examples 2 and 3. The resulting product was tested and the results obtained were as follows:

Photographic films were prepared by the method described in Example 2. Those films were tested and the;

following results were obtained:

Tackiness Brittleness, Sward 70 F., 15% RH. Rocker, Coefficient of 70 F., friction, emul- Per- Plasticizer 80% sion to emulsion cent RH.

Wedge, MIT Damp- 70 F., 70 F., in. folds ing 50% 70% time, RH. R31.

sec.

0 None 0.23 0 48 0. 47 0. 44 20..-- Ethylene bis (methyl glycolate) 13 15 47 i 49 46 20 Ethylene bis (2- methoxyethyl glycolate) 21 0 45 39 41 20 Ethylene bis (2-(2- methoxyethoxy) thyl 23 0 47 34 .36 19 6 23 52 82 The use of the plasticizers in accordance with my invention in amounts up to as much as 40%, based on the weight of the gelatin, in gelatin coating compositions was found to have no derogatory effect upon the properties of the coatings prepared from those compositions or on photographic emulsions containing those plasticizers. If thought desirable, gelatin compositions instead of being plasticized entirely with the plasticizers described in accordance with my invention, may be plasticized with mixtures of one or more of these compounds with compatible glyeols providing 50% of the plasticized material is an ester of ethylene bis glycolic acid. As examples of mixtures which might be useful are compositions of ethylene bis (methyl glycolate) with glycerin and mixtures with polytriethylene glycols providing at least 50% of the plasticizer employed is the ester of ethylene bis glycolic acid.

Ordinarily the plasticizers will be added to the gelatin solution before the formation of a coating thereof al- 1 though plasticization of a gelatin layer can be accom- V R being selected from plished by imbibition of plasticizer from an aqueous solution thereof. However, where a multi-layer coating is desired, plasticization can be accomplished by incorporating a plasticizer in accordance with my invention into one of the gelatin layers which plasticizer migrates into layers adjacent thereto. Ethylene bis(glycolic acid) is also known under the name (ethylenedioxy) diacetic acid, HOOCCH OCH CH OCH COOH.

I claim:

1. A gelatin coating composition comprising an aqueous solution of gelatin containing therein 5-40%, based on the weight of the gelatin, of an ester having the formula:

OOHQOOOR in which formula R is a substituent selected from the group consisting of methyl, ethyl and alkoxyethyl.

2. A silver halide-gelatin photographic emulsion which contains therein 540%, based on the weight of the gelatin, of an ester having the following structural formula:

0011200011 i CH5 OCHEOOOR ethyl and alkoxyethyl.

3. A gelatin coating composition comprising an aqueous solution of gelatin containing approximately 20%, based on the Weight of the gelatin, of a compound having the formula:

OCHZCOOR OCHnOOOR R being selected from the group consisting of methyl, ethyl and alkoxyethyl.

4. A gelatin coating composition comprising an aqueous solution of gelatin having therein 540%, based on the weight of the gelatin, of ethylene bis(methyl glycolate).

5. A gelatin coating composition comprising an aqueous solution of gelatin having therein 5-40%, based on the weight of the gelatin, of ethylene bis(ethy1' glycolate). V

6. A gelatin coating composition comprising an aqueous solution of gelatin having therein 540%, based on the Weight'of the gelatin, of ethylene bis (methoxyethyl 'glycolate) 7. A silver halide-gelatin photographic emulsion containing therein 540%, based on the weight of the gelatin of ethylene bis(methyl glycolate).

References Cited in the file of this patent UNITED STATES PATENTS 1,757,482 Seel May 6, 1930 the group consisting of methyl,

Claims (1)

1. A GELATIN COATING COMPOSITION COMPRISING AN AQUEOUS SOLUTION OF GELATIN CONTAINING THEREIN 5-40%, BASED ON THE WEIGHT OF THE GELATIN, OF AN ESTER HAVING THE FORMULA: