US2396129A - Plasticizers and method of making the same - Google Patents

Description

Patented Mar. 5, 1946 j UNITED STATE 'PLASTICIZERSAND METHOD or THE SAME MAKING Ernest A. Badman, Newburgh; N. Y., assignor to I E.'I. du Pont de Nemours & Company, Wilmington, Del., acorporation of Delaware i No Drawing.

Application March 25, 1942 SerialNo.'436, 151:

Claims. (011105-171).

This invention relates to new and novel plasticizers for cellulose derivatives and methods of makingthe same.

At present certain vegetable oils are used very extensively as plasticizers for cellulose: deriva tives, particularly cellulose nitrate. Among the more common examples are castor oil, cottonseed oil, rapeseed'oil, etc. While these vegetable oils are satisfactory 'for -plasticizing nitrocellulose coatings in a .great many uses, they cannotbe used wnere the coating is to be subjected to ele-' delays productionand large storage space is re-t1 I quired for the book covers between the blanking and printing operation.

The primary object of this invention is to pro- "vide'a new and novel plasticizer for nitrocellulose? which will not exude orspew from a dry nitrocellulose film when subjected to elevated'temperatures and pressures.

vated temperatures, since the oil will spew, to I the' surface when subjected to temperatures of approximately 160 F. and higher. For this reason the vegetable oils are not entirely'satisfactory as plasticizers for cellulosenitrat'e coatings.""

The plasticizers herein disclosed are of .particular value'with cellulose derivatives for coating fabrics used extensively as a bookbinding material because oftheir" superior wear resistance, vermin resistance; washability and easily fabricating qualities. yWhen cellulose nitrate coatings are plasticized with certain plasticizers of vegetable origin, they may be objectionable because they tend to spew to the surface when subjected to elevated temperatures.

The cellulose nitrate coated fabrics are usually supplied to the bookbinders with asurface design or grain embossed in the coating which is made up into book covers by covering a stiff or semiflexible card board with the coated fabric. It is often. desired to print the front portion as'iwell as the backbone of the book cover with a design of different color fromthe coating on the fabric.

. Itfis often desired toflatt'en-out a portion of. the

embossed surface after the coated fabric is made up into a book cover where it is desired to print. This is accomplished by using a smooth embossing plate in a conventional embossing apparatus in which the book coveris subjected to heat and pressure to flatten out a limited area to be- ".-Afinore specific object is the provisionof a plasticized cellulose nitrate composition for coat- .ing fabrics for book-binding material whichmay be blanked and printed immediately thereafter.

These and other objects will be readily apparent to those skilled in, the art as the description of theinvention proceeds."

ob'ects are accomplished by re.-

The foregoing acting certain blown oils with certain oarboxylic acids-or anhydrides in such manner that when the reaction product is present within certain limits 'in'a' dried cellulose nitrate coating, it is resistant toexuding to thesurface when the coating is subject'tothe influences of heat and pressure. The reaction product of blown corn oil and phthalic or 'fnaleic acid is particularly satisfactory.

Raw corn oil i's-unsatisfactory as'a-plasticizer' for nitrocellulose in that it is relatively incompatible with nitrocellulose. It-has been discovered that by blowingthe raw corn oil with air that a suitable product is obtained which is sufficiently compatiblewith nitrocellulose to efiect I plasticization to'permit its use with nitrocellulose where flexible coatings are desired However,;ii'

the'dry films comprising-the blown corn oil and nitrocellulose are subjected to "temperature as F.,'the oil will spew'to thesuriace and result in a sticky or tacky surprohibits the use of the-oxidized corn oil in coatings which areto be subjected to temperatures above 180 F.,"such as book-binding of the film material which is normally blanked at temperaprinted. This operation is referred tom the bookbindlng' industryas "blanking. The heat and pressure on the coating employed in the blanking operation causes the oil in the cellulose nitrate coating to exude or spew to the surface which interferes with the drying of the printing inks which are-subsequently applied to the blanked out areas It is, therefore, necessary to allow the book'covers to stand twelve to twentyfour hours after blanking in order-that the oil which exudes to the surface may be reabsorbed by the coating before the covers are printed. This delay between blanking and the printing'operatlon is very costly to the bookbinder in that it on, is reacte'd with tures wellin'excess of180 F. v h

It has been discovered that if the blowncorn phthalic anhydride or similar acid anhydride, the exudation characteristics of the pyroxylin composition containing-the..reaction product aregreatly improved, permitting the use got the reacted corn oil in v to be subjected to heat as 'high 'as240-250f1i'. which'are 'commonly'encountered in the embossfling-and processing of nitrocellulose coated fabrics.

compositions which are The detailed description hereinafter is given for' the purposelof illustration and not limitation.

The preparation of oxidized corn oil phthalate comprises two steps, the flrstof which is the treatv nient of the oil by blowing with air until the desired extent of reaction has taken place between the air and the oil as measured essentially by the increased viscosity of the oil. The second step comprises the reaction of the oxidized oil with phthalic anhydride- Experimentation in regard to solubility of the untreated oil and exudation characteristics of the coated products has indicated that the ultimate product containing 95 per cent of oxidized oil and 5 per cent of phthalic anhydride is most desirable.

A grade of raw corn oil which has been found to be particularly suited for the purpose of this invention has the following specifications:

solidifying point C -15 Saponificatio'n value 188-1 93 Iodine number 113-129 Saturated fatty acid per cent 11.8 Unsaturated fatty acid do 86.5 Acetyl value 101 1.5 Unsap onifiable matter 1.3-2.0 Refractive index/155 C isms-1.47.7

The raw corn oil is charged to a suitable reaction vessel, i. e. fitted with a thermometer, a heating arrangement, and a sparger pipe in the bottom to disperse the air through the oil. The oil is heated to approximately 93 C. Simultaneously with the heating, air is forced through the oil.

During the process of blowing the oil it is heated to 93 C. and the blowing is continued until a viscosity of approximately35 to 50 seconds (Gardner-Holdt tube). at 25 C. is obtained. On this scale 1.467 seconds equals one poise at 25 C. To obtain this viscosity with the .Oil heated to 93 C. requires approximately 40 hours.

It has been found that the extent to which the oil is oxidized by blowing with air has a considerable effectin its reactivity with phthalic anhydride,-and by experimentation it has been discovered that if the raw corn oil is blown until a viscosity of 35 to 50 seconds (Gardner-Holdt tube at 25 C.) is obtained, the most satisfactory reactivity with phthalic anhydride is obtained.

If the oil is blown until a viscosity of 55 sec onds (Gardner-Holdt tube at25 C.). is obtained, the subsequent reaction'with phthalic anhydride proceeds at such a rapid ratethat it is very difficult to control the reaction so as to ob'taina uniform product. If the blowing of the oil is stopped when the viscosity of the oil has reached 30 seconds (Gardner-Holdt tube at 25 C.) the subsequent reaction with phthalic anhydride is very slow and the resulting product is less miscible with nitrocellulose coating composition and is much darker in color. Further if the oil is only blown to 30 seconds, a greater portion of blending solvent is required for satisfactory miscibility with nitrocellulose coating compositions dispersed in the usual alcohol and ester. solvent mixtures. 1

It has been discovered by experimentation that if the temperature of the oil during the oxidation process exceeds 105 C. a cracking and polymerization of the oil takes place and the resulting product is not sufficiently reactive with phthalic anhydride. If the temperature of the Oil during the oxidizing process is approximately 80 C., the time required for blowing to obtain a viscosity of 35 to 50 seconds (Gardner-Holdt tube at 25 C.) is approximately 70 hours. The lower the temperature of the oil during the oxidizing proc- 35 to 50 seconds (Gardner-Holdt tube at 25 C.). It is not economically practical to blow the oil longer than '70 hours.

After the oil has reached 35 to 50 seconds viscosity (Gardner-Holdt tube at 25" C.) the air being forced through the oil is stopped and the temperature of the oil elevated to 132" C. During the elevation of the temperature of the oil, a mechanical stirrer is used to agitate the oil and carbon dioxide gas is slowly bubbled through the sparger pipe to facilitate agitation and to aid in preventing discoloration of the product. When the temperature of the blown oil has reached 132 C., p'nthalic anhydride is added slowly to the charge with vigorous agitation. For every 95 parts of oxidized corn oil five parts of phthalic anhydride are added to the reaction kettle. Since the reaction runsthrough to-completion the reaction product has the approximate composition of 95 parts oxidized corn oil and five parts of phthalic anhydride.

During the addition of the phthalic anhydride there is an exothermic reaction and the temperature rises to 140 C. Temperature is maintained at this point until a viscosity of approximately between 200 and 250 seconds (Gardner-Holdt tube at 25 C.) is obtained. When the desired viscosity is reached, the oil is cooled as rapidly as possible to about 65 C. Sufficient solvent is added to the reaction kettle to make a solution of the blown corn oil phthalate. The solvent added to the reaction kettle should be miscible with both the reaction product and pyroxylin. Butanol has been found satisfactory for this purpose, as well as toluol, pentasol and mixtures of various solvents. The material is removed from the reaction kettle and is ready for use as a nitrocellulose plasticizer for book-binding material. The butancl is added to facilitate compatibility of the oxidized corn oil phthalate in a nitrocellulose coating composition. dispersed in an alcohol-ester solvent mixture, such as c. g., ethyl alcohol and ethyl acetate.

The oxidized corn oil phthalate has the following properties:

Viscosity at 25 C Sec 200-250 Acid number 23-30 Iodine number 65-75 Saponification N0 270-300 Color Dark amber 1 Gardner-Holdt tube."

In themethod outlined above parts of the oxidized oil are reacted'with 5 parts of the anhydride. However, it has been found that desirable plasticizers can be madeusing as much as 15 parts of the anhydride to 85 parts of the oxidized oil. Plasticizers containing more than 15 parts of the anhydride to 85 parts of oxidized oil are not entirely satisfactory because of incomplete reactionof the anhydride with the oxidized oil, which results in a material having an excessively high acid number for the purposes of this invention. a Y

Plasticizers containing less than 2% of phthalic anhydride have not been found satisfactory for the purposes of this invention since such small modifications of the oxidized oil do not result in any material advantage. j

In a like manner oxidized corn oil maleate may also be prepared in which case 97.8 parts of oxidized corn oil is reacted with 2.2 par s of maleic anhydride at avtemperature of C. instead of C. as in the case of phthalic anhydride. Where maleic anhydride is used 2.2

1 equivalent.

parts of maleic anhydride are used in place of 5 parts of phthalicanhydride which is the reactive The result is essentially the same except in the case of the oxidized corn oil maleate which is ofa light straw color which is of extreme importance in the case of its use with light colored coating compositions. Plasticizers containing more than 5 parts of the maleic anhydride as well as those containing-less than 1 part are not satisfactory for the purposes of this invention for the same reasons discussed above in connection with the preferred range of phthalic anhydride.

Example I Per cent Cellulose nitrate; 10.50 90% solution of oxidized corn oil phthalate in'butanol 14.00 Pigments 17.85

Butanol 15.06 Ethyl acetate 21.69 Ethyl alcohol 21.30

The method of preparing the above composition which comprises first dissolving the cellulose nitrate in the solvents and'separately grindingthe pigments in the'blown corn oil phthalate and then combiningthe materials is well known in the art and further detailed description does not appear to be necessary.

The tension of the fabric and position of the doctor knife is so adjusted that the coatingcomposition is actually driven intothe interstices of fabric instead of bridging across them. Approximately 4.7 ounces of the wet coating composition are applied to the fabric which corresponds to approximately 2.0 ounces of non-volatile components. The material is passed through a heated chamber after each successive coat to expel the volatile solvents. Following the impregnating of the fabric it is embossed by conventional embossing methods, such-as roller or fabric is subjected tola heat and pressure treatment. A design counter to the design of the embossing element is transferred to the treated fab- ,ric. .At this stage the material is supplied to the .or semi-rigid material to form a book cover.'-- In order to further enhance the appearance of the book cover and provide a smooth printing surface fortitles and decorative work the thus prepared cover is subjected to a blanking operation in which a limited area of the cover is flattened out by a heated smooth embossing plate under pressure. The temperature of the smoothembossing plate is approximately 280. F. and sufficient pressure'is applied to flatten or obliterate the original embossed design. During this heat and' pressure treatment the blown corn oil phthalate does not exude to the surface. Immediately following the blanking operation and while the blanked area is still hot it can be printed with conventional printing inks designed for use on cellulose nitrate containing surfaces without interfering with the norplate embossing apparatus in which the treated mal drying time of the printing ink. A suitable printing ink for thecellulose nitrate treated fabric is disclosed in U. S. Patent, 2,049,507, which issued August 4 1936, to McBurney et a1.

Example 11' A coated fabric as distinguished from an impregnated fabric is' prepared as follows: To a cotton sheeting running 3.69 yards per pound per i 39" width is'applied a plurality of coats of the following composition by means of a doctor knife:

Per cent Cellulose nitrate 11.65 Pigments Q. 9.65 solution of oxidized corn oil phthalate in buta-nol 21.10 Butanol 14.70 Ethyl acetate 21.45 Ethyl alcohol 21.45

Thedoctor knife and tension of the fabric'is adjusted so that the coating is applied on the surface of the fabric rather than driven into the interstices. Sufficient coats of the above composition are applied to deposit approximately ten ounces per yard of wet composition on the fabric which correspond to 4.2 ounces per yard of non-volatile components. A final surface coat of the following composition is applied in the amount of 1.5 wet ounces per yard which corresponds to 0.2 dry ounce per yard.

I Percent Cellulose nitrate 12.35 Ethyl acetate 43.83 Ethyl alc 43.82

The volatile solvents are expelled after each successivecoat by passing through a heated chamber. The material prepared is next embossed with an overall'design by conventional embossing apparatus. The material thus prepared is supplied to the book-binders. "It is ready to be made up into book covers and treated in the same manner as mentioned in EXample I by blanking and printing immediately after blankmg,

While the preferredembodiment of this inventionemploys raw corn oil having "an iodine value of 113. to 129 as a starting material in the manufacturing of the oil 'phthalate, other unsaturated semi-drying oils having an iodine value of 80 to may be used with varying degrees of success. The following oils which are listed below with thecorresponding iodine value fall within the scope of this invention as equivalents of raw corn oil used to illustrate the in- Oils having an iodine value below 80 contain such quantities of saturated components which do not oxidize sufiiciently-when blown with'air, that th blown oil will not react satisfactorily with phthalic acid to give the desired properties. Oils having an iodine value greater. than 135 are,

so highly unsaturated as to form solid oxidation products and are not satisfactory in preparing nitrocellulose plasticizers.

The preferred embodiment of this invention employs the anhydride of the carboxylic acid slnce they are more active. It is, however, within purview of the invention to employ carboxylic acids and their anhydrides other than phthalic acid. Those which may be used to react with the oxidized oils include unsaturated dicarboxylic acids, such as, e. g., maleic acid; saturated dicarboxylic acids, such as, e. g. succinic and adipic acids; saturated monobasic carboxylic acids, such as, e. g. acetic and lauric acids; and carboxylic acids; with hydroxyl groups, such as, e. g. lactic acid.

In the claims and specification, the term acid" is used generically to include the anhydrid as well as the carboxylic acid, and in most cases the former is preferred.

This method is to be distinguished from making alkyd resins wherein they are modified with a blown oil in that the embodiments of this invention do not require the addition of a polyhydric alcohol. In the present case no glycerine as such is added and th acid is present in a relatively very minor proportion.

The new plasticizers herein disclosed are useful in plasticizing certain polyvinyl resins, such as, e. g. the copolymer vinyl acetate and vinyl chloride resins disclosed in U. S. Patent 1,935,577 to Reid; the copolymer of vinyl chloride and diethyl fumarate or dimethyl fumarate resins disclosed in U. S. Patent 1,945,307 to Dykstra; and the polyvinyl acetal resins disclosed in U. S. Patent Reissue 20,430 to Morrison et al. A small portion of a solvent type plasticizer is sometimes desirable to use with the new plasticizers herein disclosed when plasticizing polyvinyl resins to prevent the blown semi-drying oil-acid reaction product from sweating out. I

This invention will find great utility in the nitro-cellulose lacquer industry wherever a nonspewing plasticizer is desired. The non-spewing plasticizer herein disclosed will also find great utility as a plasticizer for ethyl cellulose, as well as for synthetic resins with which it is compatible therewith. Coatings employing the non-spewing plasticizer may be applied over rigid base materials, such as wood, metal, etc., as well as flexible base materials, such as paper, cellulose film, non-woven fabrics, etc. Specific uses as a nitrocellulose plasticizer other than book-binding material described in the foregoing examples include outdoor furniture upholstery, lacquered table cloths, and coated fabrics in general. Other important uses will be readily apparent to those skilled in the art. Cellulose derivatives, such as ethyl cellulose, benzyl cellulose, and similar film-. forming cellulose derivatives may replace the cellulose nitrate.

The primary advantage of the invention is the provision of a non-spewing nitrocellulose plasticizer which permits the use of plasticized nitrocellulose compositions at temperatures which cause spewing of the conventional vegetable oil plasticizers. A further advantage is the provision of a bookbinding material which may be blanked and printed immediately over the blanked area.

It is apparent that many widely diiferent embodiments of this invention may be made without departing from the spirit and scope thereof, and therefore, it is not intended to be limited except as indicated in the appended claims.

I claim:

1. A composition consisting of the reaction product of corn oil blown to. a viscosity of 35 to 50 seconds (Gardner-Holdt Scale) and material selected from the group consisting of phthalic acid, maleic acid, and their anhydrides.

2. The product of claim 1 in which the dicarboxylic acid is phthalic acid and the ratio of oil to phthalic acid is between to 15 and 95 to 5.

3. The product of claim 1 in which the dicarboxylic acid is maleic acid and the ratio of oil to maleic acid is between 95 to 5 and 99 to 1.

4. A nitrocellulose composition comprising nitrocellulose and the reaction product of blown corn oil and material selected from the group consisting of phthalic acid, maleic acid and their anhydrides, the said corn oil having been blown to a viscosity of 35 to 50 seconds (Gardner-Holdt Scale) before reacting with the acid material.

5. A nitrocellulose composition comprising nitrocellulose and blown corn oil phthalate the corn oil having been blown to a viscosity of 35 to 50 seconds (Gardner-Holdt Scale) before reacting with phthalic acid,

6. A nitrocellulose composition comprising nitrocellulose and blown corn oil maleate the corn oil having been blown to a viscosity of 35 to 50 seconds (Gardner-HOldt Scale) before reacting with maleic acid.

'7. The method of preparing a plasticizer for nitrocellulose compositions which does not spew therefrom at elevated temperatures which consists in blowing a semi-drying oil having iodine number between 80 and 135 until a viscosity of 35 to 50 seconds (Gardner-Holdt Scale) is reached and thereupon reacting the same with material selected from the group consisting of phthalic acid, maleic acid and their anhydrides.

8. Process of preparing a non-spewing nitrocellulose plasticizer comprising blowing a raw semi-drying oil until the viscosit of the oil reaches 35 to 50 seconds (Gardner-Holdt tube at 25 C.), and thereupon reacting the blown oil with phthalic anhydride until the viscosity of the reaction product reaches a viscosity of 200-250 seconds (Gardner-Holdt tube at 25 C.).

9. Process of preparing a non-spewing nitrocellulose plasticizer comprising blowing at 80-105 C. a raw corn oil until the viscosity of the oil reaches 35 to 50 seconds (Gardner-Holdt tube at 25 0.), and thereupon reacting the oxidized corn oil with phthalic anhydride until the viscosity of the reaction product reaches a viscosity of 200-250 seconds (Gardner-Holdt tube at 25 C.)

10. Process of preparing a non-spewing nitrocellulose plasticizer comprising oxidizing raw corn oil by blowing with air at 80-105 C. until the viscosity of the oxidized oil reaches 35 to 50 seconds (Gardner-Holdt tube at 25C.) said corn oil having an iodine number between 80 and 135 seconds before oxidation, reacting the said oxidized corn oil with phthalic anhydride until the viscosity of thereaction product reaches a viscosity of 200-250 seconds (Gardner-Holdt tube at 25 C.), and adding sufiicient solvent to the reaction product to make a per cent solution of said reaction product.

11. The process of claim 10 in which the ratio of oil to phthalic anhydride is parts of oil to 5 parts of phthalic anhydride.

12. Process of preparing a non-spewing nitrocellulose plasticizer comprising blowing a raw semi-drying oil until the viscosity of the oil reaches 35 to 50 seconds (Gardner-Holdt tube at 25 C.) and thereupon reacting the blown oil with maleic anhydride until the ViSCOSityOf the reaction product reaches a viscosity of 200-250 seconds (Gardner-Heidi: tube-at 25 C.).

' oil having an iodine number between 80 and 135 seconds before oxidation, reacting the oxidized corn oil with maleic anhydride until the viscosity of the reaction product reaches a viscosity of 200- 250 seconds (Gardner-Holdt tube at 25 C.), and adding sufficient solvent to the reaction product to make a, 90 per cent solution of said reaction product.

15. The process of claim 14 in which the ratio of oil to maleic anhydride is 97.8 parts of oil to c 2.2 parts of maleic anhydride,

ERNEST A. RODMAN.