US2310419A

US2310419A - Varnish

Info

Publication number: US2310419A
Authority: US
Publication date: 1943-02-09
Anticipated expiration: 1960-02-09

Description

Patented Feb. 9, 1943 VARNISH I Wells W. Ginn, Cincinnati, Ohio, assignor, by

mesne assignments, to Chemical Novelties Corgoration, Cincinnati, Ohio, a corporation of No Drawing.

Application October 17, 1941, Serial No. 415,488

6 Claims. (01. 106-250) This invention relates to vegetable oils and the improvement of them. It .is directed generally to the varnish and printing ink industries, l and has application, particularli to the production of varnishes, printing inks coating compositions, and the like.

Thetypical vegetable :oils used for such purposes are linseed oil, China-wood oil, perilla oil, soybean oil and some others such as oiticica, rapeseed and sesame. In the raw state the oils are in liquid condition, but they are not sumciently pure to be used directly, so they are refined and purified by acid and alkali and de-- colorizing treatments. These oils are called varnish oils in the industry, and for convenience the same terminology is employed in the following specification and claims.

Some of the vegetable oils dry or oxidize and polymerize upon exposure to the atmosphere more quickly than the others and for this reason, the vegetable oils are classified generally as drying oils, semi-drying oils and non-drying oils. The varnish oils are all of the drying oil "and semi-drying type, and all of these possess the capacity to be bodied and polymerized upon prolonged heating at elevated temperatures.

In general, the varnish oils-are made into varnishes by heating them to a temperature of 450- 600 F. and cooking them at this temperature for a substantial period of time, as for instance, on hour in the case of China-wood oil and five to six hours, or more, in the case of linseed, epending'upon the consistency desired.

China-wood oil is peculiar in that it bodies very much faster than the other oils and also in that it provides varnish films which generally to, except by special manipulations which are useful only in specific instances, or by the addition of foreign materials, such as-rosin,.lime,

driers, and fatty acids of the vegetable oils.

are superior in toughness, durability and moisture-proofness. For these reasons China-wood oil is employed in the industry quite extensively in preference to'the other oils. However, this oil is quite expensive; and the supply of it is dependent upon foreign sources; the prices fiuctuate widely, in accordance with general economic; trade and social conditions. In some cases resins are cooked with the oils to increase their film forming capacity, and in other cases, the oils are bodied first and the resins are added at a later period. The technique depends uponthe oils and resins used and desired.

When the varnish oils are cooked in the varnish kettles the acid value of them is increased and the iodine value is decreased. In general, it is highly useful for the varnish makers to be able to control the acid value and iodine values of. the oils, sinceqthese serve as a guide indie "a' tir 1g the properties of the resultant varnishes, other factors being equal. But the varnish makers] have not been able, up to the present time, to control these values the way they have wanted the type of varnish The change which takes place in an oil when it is heated and polyme zed is a complex chemical change, of which this known or understood. For this reason, and because of the inability to control the acid and iodine values, the results, 'in the manufacture of the coating compositions, have been dependent largely upon the artisan skill of the varnish cookers. A primary objective of the present invention has been to provide a process for controlling the various chemical changes which take place in.an oil when it is being cooked to convert it into a varnish. In other words, a process has been sought, and the present invention provides the means enabling the varnish makers to control acid and iodine values of varnishes and ink vehicles during their polymerization, so that the final products may have the desired characteristics.

It has been another objective to shorten the time required for cooking, A reduction in cooking time is important because the longer an oil is cooked the more it tends to become discolored and the more its acid.value is increased. Dark possess different qualities and value by virtue of the differences between the oils themselves and the way they are treated and cooked. Some of the varnishes provide films which are very much better than others. For example, China-wood oil provides tougher, more durable, and more moisture-resistant film than soybean oil or linseed. 0n the other hand, the oils which provide these better varnishes are more expensive than the others and, consequently, the varnishes are costlier. It has been the objective in this invention to provide means for obtaining varnishes from the less costly oils, such as linseed, soybean and even cottonseed, which are equally as good as the varnishes and vehicles produced from the more expensive oils which heretofore have been used. Briefly, the present invention is a relatively simple one though the phenomena upon which it is predicated are very complex and difiicult to explain. Castor oil has occupied a peculiar position in the coating composition. industries. It has been used as a plasticizer to soften lacquer which otherwise would be brittle. Because of its peculiar chemical properties and its non-drying qualities, it has never been used in the formulation of varnishes and ink vehicles, and, in fact, its use has always been specifically avoided because the presence of its prevents the drying of varnish films.

This invention, however, is predicated upon the discovery that when the varnish oils are cooked in the presence of a small quantity of castor oil, the varnish oils become bodied in one-half to one-quarter of the time otherwise required for producing the heavier bodies, the film forming properties of the v resulting varnishes are improved, and the acid value and iodine value are directly controllable in relation to the amounts of castor oil employed.

When the vegetable oils are cooked in the presence of relatively small quantities of castor oil, as for example, less than 1%, then, paradoxically, the acid value may be held at neutral or any given value (or may be decreased if other acids are present) during the cooking, and the iodine value is increased, until the influence of the castor oil is exhausted. In other words, the changes which take place in the iodine and acid values of the varnish oil being cooked in the presence of the castor oil are diametrically opposite to the changes which would take place in its absence. The varnish is cooked to a given body in any-. where from one-half to one-fourth the time otherwise required. The films which these varnishes and coating compositions provide are much more durable, resistant to moisture and much tougher than the films which otherwise would be produced,

In relation to its various aspects, therefore, the invention provides a means for controlling the acid or iodine values of a given oil, whereby any desired acid value is obtained for any given body,

in respect to final quality; the means for providing better varnishes and film forming vehicles from the inferior vegetable oils, in respect to the substitution of one oil for another and in respect to the production of good varnishes at low cost; and the means for shortening the time of cooking in relation to the production of the varnishes.

For the most part, the chemistry which underlies the activity of the relatively small portion of castor oil in relation to the vegetable oil which it is used to treat is not explained by the chemical knowledge which is available at the present time, and for this reason no theories are proffered to explain the changes which take place. From the practical point of view, in general, the reduction in acid value is related to the quantity of castor oil used for given cooking periods. Because of this relationship, the acid value is controllable either by using a given amount of castor oil and adjusting the cooking time, or better, adjusting the quantity of castor oil when the cooking time is fixed, the greater the amount of castor oil being used, the smaller the acid valu for a given cooking period. The change in iodine value also is controllable in the same manner though the relationship is not so marked. In most cases the quantity of castor oil should not exceed more than about 2 /2% by weight of the varnish 011 being treated, it a drying oil or varnish is desired as the final product. As little as ,4; of 1% provides very useful results, and /4, of most usually is the amount employed.

However, if it is desired to body the oil quickly, without regard to its drying properties, then the amount of castor oil may be increased up to about 15%. When this is done the drying and film forming properties of the oil may, nevertheless, be restored to it by the addition of acid, for

example, rosin, vegetable and animal fatty acids,

such as linseed-fatty acids and acetic respectively, and even the acids such as hydrochloric and sulphuric. On the other hand, as little as one-eighth percent of castor oil is capable of producing a substantial reduction, both in the acid value of a given varnish oil, such as linseed, during the cooking of it, and the cooking time it requires. Thus, the amounts of castor oil employed are almost trivial in either instance.

On the other hand, the decrease in acid value which accompanies addition of the castor oil is quite rapid. For instance, as a typical illustration, ADM Superb linseed oil, and 10% of rosin were heated together with A of 1% of castor oil to cooking temperature. When the cooking temperature was reached the acid number was 8.6; ten minutes later it had dropped to 5.6. In fifteen minutes thereafter the number was 5.5, and in successive quarter hour intervals the values were 5.6, 7, 6.1, 5.9, and then 1.9, respectively. From this low point the acid value began to increase. In the absence of the rosin, or other varnish making gums or resins, the acid value remains at, or if free fatty acids are present drops gradually toward or to neutral, depending upon the quantity of castor oil, and then it again increases in normal fashion. By adjusting the quantity of castor oil, bearing in mind the time cooking is to continue, the acid value can be controlled to a given number at the end of the cook. The change in acid value, of course; is different for different oils and is influenced by the nature of the oil being cooked, but these factors are understood by those skilled in the art.

By the term castor oil, I mean to designate the commercial castor oil, for instance, commercial medicinal oil which is available on the market, and castor oil which has been blown with air. The mono glycerides of the fatty acids also have been found to be similar to castor oil as it is used in the practice of the present invention, though the results are not so pronounced, and they are, therefore, to be considered as only partial equivalents to it.

From the commercial point of view, the invention is practiced most conveniently by the use of what may be termed a control" oil. This control oil preferably is comprised of a portion of given varnish oil and a quantity of the castor oil which is so adjusted in amount that a predetermined portion of the control oil contains the proper amount of castor oil necessary for a treatment of the given batch of varnish oil to be made into varnish. An example of a suitable control oil is as follows:

EXAMPLE 1 Linseed oil base control oil To about 1600 parts heavy bodied raw linseed oil (oil which has been refined, bleached and air blown, as for example, ADM "white heavy bodied raw) is added 80 parts of commercial medicinal castor oil (such as Baker's AA) and about 715 parts of refined linseed oil, such as ADM superb, in the order stated to accomplish mutual solubility. Then 15 parts or 15% of this composition, for example, is used in conjunction with parts or 85% of the linseed varnish oil to be cooked. The 15% addition incorporates about of one percent of castor oil, by weight, in the total batch of varnish oil. This varnish oil then is cooked in the usual way. but bodies for instance in 1% hours to a given consistency, as against 7 to 8 hours required for the same consistency in the absence of the castor oil. In this way, a control oil is obtained which is freely miscible with the varnish oil in all proportions, and becomes mutually soluble upon heating. The control oil is useful because it pro-' vides a convenient material through which to incorporate the castor oil into the vegetable oil being cooked to make the varnish, and it also is much easier to make up batches of the control oil for subsequent use than it is to measure out and admix the small quantities of castor oil necpreparation of a control oil to be used for treating a linseed oil to be cooked. But a linseed oil base control oil also may be used for treating soya or perilla oil. Likewise, by adjusting the concentration of castor oil which is present in the control oil various proportions of it may be used instead of 15% which has been disclosed. It is not essential, however, that the intermediate step of preparing the control oil and then using it bepracticed since the castor oil can be incorporated directly into the v,oil in the varnish kettle, if desired. An example of the alternative procedure is as follows:

EXAMPLE 2 nents and less danger of improper incorporation.

There is also more prompt chemical activity when this is done.

The manner in which the varnishes and printing ink bases are made at the present time is well understood in the art, and the present in vention is adapted to be used in accordance with these recognized practices, as well as in accordance with specialized techniques.

The following examples will assist those skilled in the art in the application of the principles of the invention to the industry.

EXAMPLE 3' In place of the control oil of Example 1, the control oil may be as follows:

136 parts of white heavy bodied raw, 11.3 parts Bakers #16 castor oil (blown oil) and 533 parts printing ink linseed (e. g. ADM special raw) are mixed together in the order named. 15% of this base or control oil is added to 85% of the varnish oil to be kettle cooked. The varnishes resulting from cooking with this control oil are especially useful in printing ink formulations,

due to the freedom from livering which is provided.

EXAMPLE 4 Instead of using the control oil above, nonlivering printing inks are made adding about one-fourth of 1%, by weight, blown castor oil to the batch of printing ink oil (for example, special raw).

EXAMPLE 5 A typical synthetic resin varnish may be made by using 25 parts pale Bakelite resins (Bakelite Resin BR 254 for example) 4 parts of water white rosin, 90 parts linseed oil (Superb or Superior, for example) are mixed and heated to 575 F. within thirty minutes, at which time onefourth of 1%, by weight, of castor oil is added. The temperature is held for forty-five minutes. The body is quite heavy and may be thinned with -50% volatile solvent with addition of T" japan drier. The varnish dries in air in four hours and is useful as an outside spar or aircraft varnish. The varnish has better adhesion to galvanized iron than a similar varnish made in the conventional manner. In the absence of the castor oil, three hours cooking time is required, after the cooking temperature has been reached, to obtain the same body, but this varnish is very dark in color (due to the long cooking) and the varnish will not dry in the air. Perilla and .oi ticica oils respond to treatment and may be handled in the same way as linseed with due attention to the cooking temperatures which are used in the formulation of these oils. 3

EXAMPLE 6 A mixture of 240 parts non-break soybean oil, 1.3 parts castor oil and 27 parts blown soybean oil is heated to. 590 F. in thirty minutes with about 170 parts of amberol resin and cooked at this temperature for about forty-five minutes to body. At the' end of the cook 2.6 parts of hydrochloric acid are added. The resulting varnish provides a good oven drying varnish, yielding a hard, tough film of considerable flexibility. In place of the amberol other resins may be used with appropriate adjustments being made in the quantities, in accordance with the resins selected.

EXAMPLE 7 To make an outside spar type varnish of 50 gallon length using phenol formaldehyde resin the procedure is as follows:

The oil is made of one-half soybean oil and one-half perilla oil. parts of this oil, 4 parts of water white rosin and 25 parts of the phenol formaldehyde resin, for instance, Bakelite resin BR 254, are admixed together and the oil is heated to 575 F., and at this time, .2 part of castor oil, for example, Bakers AA are added. the castor oil amounting to one-fourth of 1% of the oil. The cooking temperature is run to 575 F. in thirty minutes and then held for body. The varnish is thinned with toluol to 40% volatile matter and driers added.

EXAMPLE 8 A varnish similar to the varnish of Example 7 is made by using an admixture of 50% linseed oil and 50% perilla oil instead of soybean and perilla of the previous example. The other procedure is the same.

EXAlidPLE 9 A varnish similar to the varnishes of Examples 7 and 8 is made by using the same procedure of Example 7 with the exception that the oil is made by using 50% of cottonseed oil with 50% of perilla oil and 1% of castor oil; for example, Baker's AA is used in place of one-fourth of 1%.

All cottonseed oil may be employed in place of the mixture of cottonseed and perilla, soybean and linseed, by varying the proportion of castor oil, though the employment of a faster drying oil in conjunction with the cottonseed is desirable to accelerate the drying properties.

EXAMPLE 10 Oiticica oil, for example, crude oil either solid or liquid, is cooked with A of 1% of castor oil, for example Baker's AA, for approximately one hour to attain the desired body. The oil is brought to cooking temperature over a. period of about forty-five minutes to an hour and fifteen minutes and it is preferable that the castor oil then be added. Cooking tempegature should not exceed approximately 450;' at above a temperature of about 460 a curd-like substance forms in the oil which is undesirable. This curd forms whether or not castorv oil be-present and it is due to maintenance of an improper cooking'temperature.

Resins may be added to the oiticica oil to make a varnish approximating a China-wood oil varnish. The varishes made in accordance with this example are unique in that they are considerably less brittle than the usual oiticica oil varnishes. It is to be noted here that the small quantity of castor oil eiiects a change in the chemical and physical properties of the oil and does not act merely as a plasticizer.

EXAMPLE 11 Fish oil, such as sardine oil,-is brought to cooking temperature over a period of forty-five minutes to an hour and fifteen minutes after which approximately /1 of 1% of castor oil, for example Bakers AA, is added. The oil is then cooked at a temperature of about 575 F. and after a period of two hours the oil has been bodied to a consistency that would require from five to six hours of cooking in the absence of the castor oil.

In place of using castor oil in the procedure of Examples 10 and 11 a linseed oil base control oil of the type disclosed in Example 3 may be utilized. Likewise, blown castor oil may be substituted for the Baker's AA castor oil as disclosed in Example 1.

It is also to be understood that mixtures of oiticica oil with soybean, linseed, perilla oil and the like may be cooked together in the presence of the castor oil as indicated,'with or without such gums and resins as may be employed to provide varnishes.

The vehicles which are used in the printing ink manufacture, when made in accordance with the present invention, have several important advantages. In the first place they are free 01' the tendency to liver or form stifl gels when used in conjunction with the pigments that have a tendency to cause this chemical action. For instance, with peacock clue and chrome lemon and Prussian orange, the most notable oflenders tending to cause livering, the inks made in accordance with the present invention were free from liveringafter an extended storage period, while iivering takes place in conventional ink varnishes otherwise treated in the same way. The var nishes made in this manner also have much better wetting properties in relation to the pigment and this explainsin part the non-livering tendencies, while the control of the acid value .also assists in the formulation of quality materials at low cost. The prevention of this action is important in the industry because it heretofore has been necessary for the printers to use the inks shortly after they were received, since livering would have occurred had they been stored.

In regard to physical properties the varnishes which are made through the practice of this invention are superior to the varnishes which otherwise would bemade in the conventional manner in several important respects. The films from the linseed oil varnishes, for example, ex.- hibit the properties of flexibility, toughness. durability and drying time of the typical Chinawood oil varnishes available at present. These varnishes, moreover, when subjected to ultra violet light show excellent durability. They withstand the caustic soda tests and the boiling water test to a marked degree. Also, in relation to adhesion, flexibility and bending and elasticity, the films of varnishes made in accordance with the present invention are better than similar films made without its practice. The films do not exhibit the usual tendency to check in a gaseous atmosphere and do not possess the undesirable taste or odorof the typical China-wood oil varnishes.

This application is a continuation in part of my application Serial No. 219,834, filed July 18, 1938, for "Vegetable oils, now issued into Patent No. 2,260,140.

The claims ,of the present application are directed particularly to the improvement of oiticica oil. Claims directed to the treatment of soybean, linseed, perilla and cottonseed oil appear in the aforesaid application Serial No. 219,834, and claims directed to the treatment of fish oil, such as sardine oil, appear in 00- pending application, Serial No. 415,489, filed as 01 even date herewith.

Having described my invention, I claim:

1. The method which comprises cookin oiticica oil in the presence of approximately of 1% to 2%% of castor oil.

2. The process which comprises cooking an oil comprised predominantly of oiticica oil in the presence 0! approximately A; of 1% to 2'/ of castor oil.

3. The method 01' making a varnish which comprises cooking oiticica oil in the presence of approximately A; of 1% to 2, oi castor oil at a temperature of approximately 450 until the oil has attained the desired body.

- 4. The method of making a varnish which comprises cooking an oil containing a substantial quantity of oiticica oil at the varnish cooking temperature therei'orin the presence of approximately of 1% to 254% or castor oil until the oil attains the desired body. v

5. An oiticica oil varnish that has been made from oiticica oil cooked in the presence of approximately oi 1% to 2%% of castor oil.

6. The method of improving oiticica oil to provide therefrom an oil capable of drying to a relatively flexible film which comprises cooking the oiticica oil at a suitable cooking temperature in the presence 01 approximately V. 01' 1% to 295% 01' castor oil.

' WELLS W. GINN.