US2400541A - Glue and process of manufacture therefor - Google Patents

Description

106. tomeosmous, CROSS FERENCE comma OB PLA 7 Patented May 21, 1946 GLUE AND PROCESS OF MANUFACTURE THEREFOR Charles N. Cone, Portland, reg., assignor to M and M Wood Working Company, Portland, 0reg., a corporation of Oregon No Drawing. Application October 6, 1941,

Serial No. 413,807

17 Claims.

My invention relates to glue, and to the process of making the same. The glue of the invention is particularly suitable for the manufacture of plywood panels, although it is to be understood that its field of use is not necessarily so limited.

More particularly, my invention relates to the method of making glues utilizing animal blood products and water with the addition of such other materials as caustic alkali, lime and silicate.

It has been known heretofore that glum made by dissolving uncoagulated animal blood in a quantity of water, and to which is added, in proper proportions, lime, caustic soda, and silicate. One such process is fully described in my prior patent, No. 1,976,436, issued October 9, 1934. Glues of thistype are suitable for manufacturing plywood panels, and are characterized by their qualities of forming a mechanically strong bond between the veneer plies, and of being exceedingly high water and weather resistant. A serious limitation of such glues, however, is that they require uncoagulated or water soluble blood, which is not readily obtainable, as such, on the market in sufficient quantities for large scale glue manufacture, and can be made obtainable only at a relatively high cost.

For practical purposes blood is dried in the slaughterhouse to facilitate the storage and handling thereof, since blood in its original liquid form is highly putrescible. It is a usual practice to coagulate the blood by heat treatment, after which it is dried, ground and sacked. This heat coagulated blood product is insoluble in water, and hence must be distinguished from soluble or uncoagulated dried blood heretofore used in the making of glues, the latter product requiring special treatment in its production. The heat coagulated blood, being the common form, is readily obtainable in relatively large quantities and is quite inexpensive.

It is economically desirable, therefore, to use heat coagulated blood as a glue base material, but no one, prior to my invention, has been able successfully to break down the particles of dried coagulated blood into a mass which could subsequently be treated to form a strong, highly water resistant glue. Accordingly, it is an object of the present invention to provide a new and improved glue having heat coagulated blood as a principal constituent, and to prom e a novel process for making such glue.

It is a still further object of the invention to provide a new and novel process for forming a glue base by treating dried coagulated animal blood products, which process is relatively simple an can be performed with readily obtainable apparatus.

Briefly stated, the invention consists of a glue and the process of making the same which comprises heating an aqueous mixture of coagulated blood particles and caustic alkali to am g temperature an cog ng e mixture at such temperature until the blood particles absorb water, swell, soften, and are transformed into a relatively homogeneous, viscous mass. At the end of the cooking period the heat is removed and the mixture is cooled to room or normal atmospheric temperature in order to check further hydrolysis. After the mass has cooled sufliciently to retard hydrolytic action, measured quantities of water, lime, additional caustic alkali, and sodium siliEHeT are added thereto, and a glue is ormed which is superior in many respects to glue made in accordance with prior known processes embodying purified soluble blood products.

In carrying out my invention, or discovery, I

have developed numerous formulae, a typical one 5 of which is as follows:

Parts Coagulated blood 100 Caustic soda (NaOH) 9 Lime 8 Silicate Water 650 I have found the following procedure a convenient method of preparing glue containing the above ingredients.

To 590 parts of water is added the 100 parts of coagulated b l o od, which is thoroughly mixed by a suitable stirring device and heated to a 40 temperature slightly lgss than 212: F. For practical reasonsf i'tis prefrfed'that this mixture ,be not allowed to boil, one reason being that upon boiling the mixture tends to froth and overflow the vessel. On the other hand, it is preferred to raise the temperature as high as possible in order that the reaction following the addition of the caustic soda may be carried out in a reasonably short time. To the mixture of water and blood is added approximately half of the total amount of caustic soda, or, in other words, four parts dissom'ibout 10 parts of water. As subsequently will appear, however, the exact amount of the caustic which may be added at this time is not critical, and may be varied sornewhat. After the causticsoda has been added to Examiner s 2 the mixture, the heating is continued for approximately ten to twenty minutes, when the blood particles will be found to have broken down and the mass become relatively homogeneous. The heating is then discontinued and the mass is cooled to substantially room temperature. The mass at this stage of the process will hereinafter be referred to simply as the glue base. this of water, is then stirred into the glue base, the remainder or 5 parts of g a ustic soda, dissolved in 20 parts of water, is then added, and u quently the s gdgrm si ligate is stirred into the mixture. The caustic soda and lime are first mixed with some water saved out of the original measured quantity to prevent lumping, which might occur if it were attempted to mix the dry ingredients into the base. A glue is then formed which is ready for use.

In the herein disclosed invention, caustic alkali is added to the mixture in two different stages of the process and for dis inct purposes:

In the first stage, coagulated blood in aqueous mixture is treated with c aus tip alkali to convert the insoluble, adhesively inert blood into a usable glue base dispersed in water. This change is hereinafter referred to as conversion, and, in the 'above mentioned example, is accomplished by treating the aqueous mixture of coagulated blood with four parts of caustic soda at near 212 F. for about ten to twenty minutes.

The glue base thus formed is treated in the second stage af'subs'ta'fitiall'iiformal atmospheric temperature with additional caustic alkali for the purpose of forming a strong and wat'ffsistant glue. The last mentioned step is hereinafter referred to as the conditioning of the glue base.

In the above cited"ei rafmpl'iaft'l'ieiiiixtufecoin prising the glue base contains four parts of caustic soda used to accomplish the conversion of the blood; and an additional five parts is added in the conditioning step, bringing the total caustic soda content to nine parts. M

In the first stage the action of caustic alkali upon the adhesively inert coagulated blood is progressive in character. If the conditions which produce the conversion are maintained, physical and chemical changes will continue which in time will result in the complete decomposition of the blood proteins into their constituent amino acids and other adhesively useless produc s. n the adhesive quality of the product is lost long before complete decomposition takes place. When the action is initiated the nature of the mixture changes from its original state in which it has no adhesive quality, and progressively produces products first of increasing value to an optimum and then of diminishing value until it is no longer usable as a glue base. Therefore, in order successfully to convert coagulated blood into a glue base by the herein disclosed process, the degree of change in the conversion sta ge must be held within limits. The egree of change can e regulated by controlling such factors as time, the amount of caustic alkali present, and the temperature of the mixture. The higher the caustic alkali content, or the higher the temperature, the more rapid the rate of change. When, as in the example above cited, four parts of caustic soda and a temperature near 212 F. are used, the conversion action can be rapidly and effectively terminated by cooling the mixture to normal atmospheric temperature.

The progression of change in the conversion stage is reflected in the appearance of the mix- The lime, which has been mixed in 335 ture so that by observation of a series of samples taken from a mixture at different time intervals and representing varying degrees of action, one can readily judge as to whether or not the mixture has had too little, too much, or about enough action to produce the most satisfactory product. These observations are best made when the samples are at room temperature.

The following description of the differences in appearance between samples of glue base which have undergone varying degrees of conversion applies to a mixture made with a ratio of 600 parts of water to parts of dried heat coagulated blood ground so as to pass through a 60- mesh screen and heated at a temperature of 210 F When the action is initiated, for instance, by the addition of four parts of caustic soda to the heated aqueous mixture, the blood particles swell rapidly absorbing the water present. As the action proceeds the particles of blood continue to swell and soften and become more adhesive in character, and begin to slough off dispersed blood to form a viscous medium surrounding the remaining undispersed portions. This process diminishes the number and size of the particles. The dispersedmedium, which at first increases in viscosity due to increasing concentration through the disintegration of the blood particles, eventually begins to lose viscosity due to the hydrolytic character of the action. Samples taken at the initial stage of action and cooled are grainy and dull in appearance and may separate out some free watery solvent if let stand. Samples taken at progressively later stages gain in luster and in smoothness of consistency due to the increase in the dispersed medium and its lubricating action upon the undispersed portions, and also, to the diminution of these undispersed portions. After the degree of action has been reached which produces samples containing such a proportion of dispersed blood that the particles are well lubricated and some smoothness of consistency is had, further action produces samples of decreasing viscosity and there finally is produced a watery solution of the deterioration products of the blood proteins which is useless for forming a glue base. It should be noted that a large content of undispersed portions does not connote lack of adhesive value. In fact, the favorable range of adhesive quality of the mixture begins at about the point where a sufficient proportion of the blood particles becomes dispersed so that the mixture begins to take on a lustrous appearance and the particles are lubricated sufficiently to form a cohesive mass.

As will be more fully explained hereinafter, the conversion of the mixture into a suitable glue base can be accomplished using temperatures and amounts of caustic soda other than those stated above. If either the temperature or the amount of caustic soda is lowered, the rate of change will be slower and a longer time is required to effect the conversion. In order to maintain a given rate of action, if the temperature is lowered the amount of caustic soda must be increased. It will readily be understood that a very wide variety of combinations of temperature, caustic soda content, and duration of treatment can be used to accomplish the desired conversion. The number of possible combinations is still further increased due to the wide range of characteristics of commercially available dried coagulated blood. From experimental tests with samples of blood prepared under widely varying we. COMPOSWONS,

COATlNG OR PLASUC It CROSS REFERENCE conditions, the observation has been made that while, for the most part, they can all be converted into a satisfactory glue base in accordance with the present invention, variations must be made in the process in accordance with the particular type of blood product being used. While no rigid segregation can be made of the different ty es of blood according to the individual properties of each, they may for convenience be classified into four general types according to their resistance, in an aqueous mixture, to the action of caustic soda. That is to say, aqueous mixtures of predetermined proportions of blood and water heated to a. predetermined temperature will, in general, require varying amounts of caustic soda in order to effect a certain degree of change or conversion within a predetermined cooking period according to the peculiarities of the dried coagulated blood being used. Thus, mixtures of 100 parts of various ones of the different general types of blood and 600 parts of water heated to a temperature .of 210 F. will require varying amounts of caustic soda in order to efiect substantially the same degree of conversion in a period of twenty Caustic soda-parts 3.514 424.75 4.75:7 Above 7 This classification of commercially available coagulated blood into types is for convenience only and it is not intended to teach that the varieties of blood fall into four groups of distinct and clearly defined character. A very large number of samples of blood will be found to vary from one extreme type to the other. Progressing from type I to type IV, the particles of insoluble blood show an increasing resistance to conversion into a viscous colloidal dispersion and more drastic conversion treatment is required to produce the best glue base. Type I coagulated blood is to be distinguished from type 11 coagulated blood by the fact that for a given procedure, at the degree of conversion of optimum adhesive value, its particles will have passed much more completely into dispersion. Also comparing the temperature-viscosity relationship of the resultant mixtures, that produced with type I will display a much more marked increase in viscosity as the temperature is lowered from 210 F. to 70 F. than will the mixture produced with type II. The designation, type IV, is herein applied to coagulated blood which is most resistant to the conversion action of caustic soda, and which, in the standard procedure above described, yields very unsatisfactory results. Blood of this type yields improved results when the amount of caustic soda present during conversion is increased, but the results obtained are definitely inferior to those obtainable with types I, II and III. Excessive heating of the coagulated blood at temperatures considerably above 212 F. for a prolonged time during or following the drying step in the manufacturing process, and prior to the conversion step in the instant process, makes the blood more resistant to the conversion action of caustie alkali, and blood which has been overheated will be of type IV. Those varieties of coagulated blood products falling into type IV constitute a relatively small percentage of the commercially available blood, and by far the greater part of the total come within types I, II and III, which can readily be converted into a satisfactory glue base.

Forty-four different samples of heat coagulated blood, each from a different source, have recently been examined and tested as regards their behavior in the conversion operation herein disclosed, and classified as to type. Also determinations of pH value were made on their aqueous mixtures containing 6 parts by weight of water to 1 part of blood. The results of these tests are shown in the following table:

Range of H g fi of sample as Type m g determined 3 e from aqueous type mixture It will be noted that although there is among the types some overlapping of pH values, there is a consistent decrease in pH progressing from types I to IV.

The occurrence of bacterial action during the preparation of dried coagulated blood markedly decreases the pH of the product, and this indicates that bacterial action is to a considerable degree responsible for the variations in type among commercially available lots, an increase in bacterial action accounting to at least-a certain extent for a change in type from I to IV.

The variation in pH value among the difierent types of coagulated blood furnishes a partial explanation as to why type III blood, for example, can be made to yield a glue base comparable in value to that produced with type II if more caustic soda is used when it is converted. However, although an increase in caustic soda increases the pH of the aqueous alkaline mixture during conversion, parity of pH at this stage does not appear to be the only requisite, for in order to obtain with type III an equal rate of conversion and comparable adhesive value to that obtained with type II, an increase in caustic soda considerably in excess of that required to give parity of pH during conversion is often required.

The pH value of the aqueous alkaline mixture is influenced by the extent to which the caustic soda has reacted with the blood. The more it has reacted the lower will be the pH and for that "reason the pH of a mixture becomes lower the longer it stands and the drop in pH is more rapid the higher the temperature at which the mixture is held. For example, a mixture of parts of type II heat coagulated blood, 600 parts of water,

and 4 parts of caustic soda was held at a temperature near 70 F., and the pH value of the mixture determined at varying intervals of time after the addition of the caustic soda to the mixture. The results of these determinations follow:

decrease in pH value when the mixture is held at a higher temperature: A mixture of 100 parts of type I heat coagulated blood and 590 parts of water was heated to 210 F. Four parts of caustic soda in 10 parts of water were added and Examiner the temperature maintained at 210 F. Samples were taken from the mixture at varying intervals of time after the addition of the caustic soda. The samples were cooled immediately to room temperature and the pH value of the samples was determined. The results of these determinations follow:

Another example illustrates the decrease in pH value to be expected when heat coagulated blood is cooked with a dififerent amount of caustic soda. A mixture of 100 parts of type I heat coagulated blood, 1 part of caustic soda and 300 parts of water was cooked at 210 F. A sample taken and cooled after five minutes cooking had a pH value of 9.0. A sample taken and cooled after the mixture had been cooked for 12 hours at 210 F. had a pH value of 8.3, and another sample after 24 hours cooking had a pH value of 8.0. The following tabulation gives the approximate pH values determined at room temperatures to be expected from mixtures of 600 parts of water and 100 parts of type II blood which have been cooked at 210 F. for about 20 minutes with varying amounts of caustic soda.

Parts of caustic soda pH value ONO The following tabulation gives the approximate pH values to be expected when increasing amounts of caustic soda are added to the mixture prepared by cooking 100 parts of type II blood with 600 parts of water and 4 parts of caustic soda at 210 F. for about 20 minutes. In this tabulation, the parts of caustic soda are the total amount including the a parts with which the mixture was cooked.

Parts of caustic soda pH value ture was found to be 11.54. 8 parts of hydrated line suspended in 30 parts of water were then added to the mixture and the pH vmue was found to have changed to 12.87. Five parts of caustic soda dissolved in 20 parts of water were added and a pH value of 13.29 determined. 40 parts of colloidal silicate of soda solution were added and a pH value of 13.07 determined. It will be noted that the silicate of soda solution slightly lowered the pH value of the mixture.

The rate of conversion in aqueous mixtures of heat coagulated blood and caustic soda is determined by the caustic soda content and the temperatures of the mixture. The following tabulation shows a wide variety of combinations of caustic soda content and temperature and the corresponding rates of conversion, and clearly indicates the change in rate of conversion to be expected from any specific change in either of these factors when applied to coagulated blood of type II.

- Temperature 32 33533 of mixture Duration of arts comprising treatment mastic Soda 600 parts within which per parts water to 100 opt mum adof 008 Wed parts of hesive value fgg coagulated is produced blood Part5: F. a 4 210 10-30 min b 4 200 50-80 min 6 4 190 2- 3 hrs d 6 210 3-15 mm e 6 200 5-25 min f 6 190 10-35 mm 0 6 1- 2 hrs. h 10 195 5 min i 10 160 2040 min j 10 140 2- 3 hrs I: 12 5-20 min I 12 140 2- 3 hrs 17: 12 125 5- 7 hrs Duration of cfii t fit n Temperature 9 t a nt parts of mixture compnswithin wi h tic soda p r mg 600 D ts optimum 100 parts coagl g fi g g eg ve 903g me 00 vs e pro. ulated blood ced Parts 4 210 220 min. 4 0 1-2% hrs. 12 125 H hrs.

It will be noted that when the action is very rapid, as, for instance, in the first example in each of the above tabulations, the same duration of treatment, for instance 15 minutes, will serve to produce an excellent glue base from coagulated blood of either type I or type II.

As heretofore pointed out, caustic alkali is used not only to disperse the coagulated blood, but also to give the glue strength and water resistance. The above tabulations show the use of .Uil. Cone-caucus,

CROSS REFERENCE (JOANNE OR PLASTIC IZXHITIIHET The internal friction thus produced aids in discaustic soda in the conversion steps in amounts varying from 4 parts to 12 parts. A very useful glue can be made from any of the resultant mixtures without any increase in its caustic soda content, but better results are obtained if the NaOH content of those mixtures containing less than 9 parts is adjusted to about that amount. All of the mixtures resulting from the conversion procedures set forth in the tabulations numbered 8 and 9 produce excellent glue when their NaOH content is adjusted, if necessary, to not less than 9 parts of NaOH, and hydrated lime and silicate of soda are added. The addition of sodium silicate greatly enhances the strength, and particularly the water resistance, of the glue and improves its working properties. Hydrated lime is also useful for improving strength, water resistance and working properties, particularly when used in conjunction with sodium silicate. The amounts of hydrated lime and sodium silicate may be varied over a wide range, but it has been found that particularly good results are obtained when amounts of the order of 8 parts and 40 parts, respectively, are used.

In the above cited examples there is a wide variation in the rate at which the coagulated blood is converted. Although all these examples provide a useful glue base, the more rapid the rate of conversion the higher the adhesive value of the resulting base. It is advantageous to use the most rapid rate of action that will conveniently permit efiective termination of the action before optimum adhesive usefulness has passed. The use of a high temperature provides, through cooling, a convenient and decisive means of terminating the action. Because of the large differential between the temperature of the material to be cooled and the temperature of the cooling medium, which may be water at about 50 to 70 R, an initial drop of as much as F. is very quickly accomplished. Such a drop in temperature is sufficient, in the presence of 4 parts of caustic soda, to so slow the rate of change that it is no longer effective, and at the normal atmospheric temperature to which the glue base is cooled, and at which the glue is used, the change is slowed to near extinction so that the base can be held at this temperature for several days without losing its usefulness.

Although the examples above cited cover a very wide range of caustic soda content and temperature employed in converting the coagulated blood into a glue base, these combinations do not encompass the extremes of these factors that can usefully be employed. For a given caustic soda content, the higher the temperature the more rapid is the rate of conversion. At a temperature near 212 F., the rate of conversion decreases sharply as the caustic soda content is decreased, so that if but 2 parts of caustic soda are used, the optimum time becomes a matter of hours, in contrast to a matter of minutes when 4 parts are used. For some purposes, for instance for gluing of very thin veneers susceptible to alkali staining, it is imperative to keep the alkali content of the glue at a minimum even with the sacrifice of a considerable degree of strength and Water resistance. Therefore, it is of importance to note that the rate of conversion can be hastened and the final result improved, when very 7 low caustic soda content is used, by heavy stirring of the mixture during the conversion to glue base with the use of, for example, 300 parts of water for each 100 parts of coagulated blood.

' 210 F. for 18 to 30 hours.

persing the swollen blood particles. water ratio in the final glue can be used to improve adhesion.

Using t alaed ed, a satisfactory glue basecan be made using only 2 parts of caustic soda for conversion, as follows: A mixture of parts of coagulated blood and 300 parts of water is heated to 210 F. and 2 parts of caustic soda are added. Stirring is continued and the temperature maintained for 4 to 24 hours. It has been discovered that the range of adhesiveness extends throughout this entire period. At the end of any selected cooking time within this period the mixture is cooled to room temperature.

If for any particular use the advantages of low alkali content justify a very slow process of conversion, a useful glue base can be made with as little as one part of caustic soda as follows: A mixture of 100 parts of type I coagulat bid and 300 parts of water is hea 21 R; 1 part of asic soda is added and the mixture stirred while w perature is maintained at At the end of the selected cooking time within this period, the mixture is cooled to room temperature.

Since the higher the caustic soda content the lower the temperature required to maintain a given rate of conversion, the lowest temperature that can successfully be used for this purpose is limited by the highest amount of caustic soda that can be used. Too large an amount of caustic soda is to be avoided, because a too highly alkaline glue may damage the material being glued; for instance, it may cause discoloration through the veneers in the manufacture of plywood. Also, even at room temperature, an excessive amount of caustic soda causes such rapid hydrolytic deterioration of the proteins as seriously to shorten the working life of the glue. Usually not more than about 12 parts of caustic soda would be used, but in special cases, for instance in the manufacture of plywood for concrete forms, where staining is not objectionable, and whenever the glue can be used within a short time after its preparation so as to avoid too much deterioration due to hydrolytic decomposition of the proteins, 15 parts or even more of caustic soda may be used.

Increased alkalinity for some uses gives slightly increased strength and water resistance. A glue capable of producing a strong and water resistant plywood bond can be made with a base produced from 100 parts of type I coagulated blood, 15 parts of oaustic s gda and 300 parts of water stirred in aWdougm' condition for 30 minutes at F., the mixture being immediately cooled after stirring. 8 parts of hydrated lime and 40 parts of soda are then added to the base and the water made up to 450 parts. If room temperature (TO-80 F.) is used during the conversion step in the above example, a useful glue can be made, but several hours will be required to accomplish the conversion. However, there are serious disadvantages entailed in the use of low temperature, and temperatures below 125 F. are not so conveniently used.

Alkaline agents other than caustic soda are not so successfully used to convert the mixture of blood and water into a glue base, but very strongly alkaline alkali metal salts as, for instance, sodium metasi me B, can e employed to produce a use u resu .e following is an .Mso a lower cool.

example in which sodium metasilicate is used for conversion instead of caustic soda: A mixture of 100 parts of type II 'coagulated blood and 600 parts of wa tgr is heated to ZlTJ 'F IY 12.5 sodium metasilicate (anhydrous basis) are adde an he mixture stirred at 210 F. for one hour, at the end of which time it is cooled to room temperature. This mixture will be found to have a pH value of approximately 11.0. The addition to this mixture of 8 parts oilime suspended in 30 parts of water, parts oitimlustic soda dissolved in 20 parts of water, and 30 parts 'of colloidal si ligate of soda solution, produces an excellent plywood are? ILtXRQLhlDOdis used, 40 parts of the colloidal solution of s iligat e gi sgda, commonly known as water glass can be substituted for the 12.5 parts 'of sodium metasilicate and conversion into a glue base of high value is obtained in about 30 minutes. A mixture thus produced, when cooled to room temperature, will be found to have a pH value of approximately 11.1. It is converted into an excellent plywood glue by the addition thereto of 9 parts of caustic soda dissolved in 20 parts of water and '8 parts'oi'iydrated lime suspended in 30 parts of water. Hydrated'fime combines with silicate of soda to form, by a double decomposition reaction, caustic soda and calciumjlicate, and can be used in conjunction with silicate parts of treads to convert the heat coagulated blood into a glue base.

In the herein disclosed process the viscosity of the glue is determined chiefly by two factors: (1) the water content of the glue; and, (2) the degree of action of the caustic alkali upon the coagulated blood during the cooking. Other factors being held constant, the more the caustic alkali acts upon the blood during cooking the lower will be the viscosity of the finished glue. The two factors above named can be so controlled as to compensate for each other within limits. Thus the total water content of the finished glue can be varied from as low as 400 parts to as high as 900 parts of water per 100 parts of dry coagulated blood, and the Viscosity of the resulting glues kept constant by varying the extent of the actionof caustic alkali upon the blood dure ing the conversion stage. The glues with highest water ratios are made with the least degree of action and those with the lowest water ratios are made with the greatest degree of action of caustic alkali on the blood during cooking.

Although, as above described, a series of glues of widely varying water contents can be made, all having the same viscosity, all of these glues will not be of equal adhesive value. An excessively high water content, for example one considerably above 650 parts of water to 100 parts of dry blood, will yield a glue of diminished adhesive value. On the other hand, an excessive amount of caustic alkali action during cooking, even though compensated for by lowering the water content of the glue, diminishes its adhesive value.

The exact amount of water used in the initial mixture may be varied considerably while the remainder may be added subsequently to efiect the desired consistency for the glue. It is preferred to use at least enough water in the initial mixture so that the consistency of the mass following a relatively short cooking period. of the order of 10 to 20 minutes, will be such that the remaining ingredients may readily be mixed therewith after the mass has been allowed to Then too, any amount of additional water may be added to the mass in the conditioning step to give the final product the desired consistency. The total amount of water constituent Will usually be of the order of 650 parts as stated.

In this disclosure particular reference is made to the use of dried, heat coagulated animal blood products, but this is merely the form in which the blood product is more readily obtainable on the market. The dried blood product may be kept in storage under normal atmospheric conditions for an indefinite period until it is desired for the preparation of a batch of glue. Wet or moist coagulated animal blood may be used with successful results, if precautions are taken to prevent excessive bacterial growths therein. Bacterial action upon the blood has the efiect of producing acidity as indicated by a lowering of the pH of the mixture of blood and water. Within limits, the detrimental effect of the action of bacteria upon the blood can be compensated for by increasing the amount of caustic alkali present during the step of conversion.

To summarize the information contained in the foregoing discussion and examples:

The conditions under which the process of the invention for the production of glue from insoluble blood are in large measure dependent upon .each other. Thus, as the concentration of alkali in the aqueous medium and its total amount relative to the blood content of the mixture are increased, the cooking temperature and the time of treatment are correspondingly decreased. When relatively high cooking temperatures are employed, the amount of alkali used and the time of cooking may correspondingly be reduced. Similarly, when it is desired to treat the blood for relatively long periods of time during the conversion step, the concentration of alkali and/or the cooking temperature should correspondingly be diminished.

In general, however, the operating conditions are relatively mild and must be kept within limits, as defined by the foregoing examples, in order to arrive at a satisfactory product. The temperature limits have been defined as between about 125 F. and about the boiling temperature of the solution, e. g. about 210 F. The concentration of alkali used, i. e. its amount relative to the amount of water present in the solution, lies within the maximum limit of 5%, the preferred range being between about 0.4% and about 1.6%. The total amount of alkali relative to the weight of blood treated is also important, since treatment of blood with even a dilute solution of alkali, if a suificient amount of such dilute solution be used, will result in degradation of the blood to too great an extent. The maximum amount of alkali per parts by weight of blood treated in about 18 parts, with the preferred range lying well below this figure, e. g. from about 4 to about 9 parts by weight alkali per 100 parts by weight blood. Obviously, it is impossible to specify rigidly the time of treatment, since this is so largely dependent upon the other variables. It depends upon such factors as the concentration of alkali, upon the cooking temperature, the type of blood being used, the nature and the amounts of conditioning agents which are to be added, the use to which the finished glue is to be put, etc. However, the optimum cooking time may be determined with sufficient precision in a given case by noting the time required to efiect the desiled degree of dispersion of the blood substance throughout the COATiNG OR PLASTlC aqueous alkaline medium, as determined by visual observation, by chemical tests, and by noting the adhesive value of the resulting glue base.

Having described my invention and what I consider to represent suitable embodiments thereof, I desire to have it understood that the specific elements and ratios mentioned are merely illustrative, and that the invention may be carried out with some latitude and variation of the proportions and ratios or by the substitution of well known equivalents for those chemicals mentioned herein by anyone skilled in the art, and that I intend in the appended claims to cover all such modifications as fall within the true spirit and scope of the invention.

I claim:

1. A glue comprising a mixture of blood, water, and caustic soda in which the blood constituent consists of coagulated, water insoluble blood dispersed by the action of an aqueous caustic soda solution of between about 0.3% and about concentration, at a temperature of between about 125 F. and about the boiling temperature of the mixture, to produce an easily spreadable, relatively homogeneous cohesive viscous mass.

2. A glue comprising a mixture of blood, water and caustic soda in which the blood constituent consists of coagulated, water insoluble blood dispersed by the action of an aqueous caustic soda solution of between about 0.3% and about 5% concentration at a temperature of between about 180 F. and about the boiling temperature of the mixture to produce an easily spreadable, relatively homogeneous cohesive viscous mass.

3. A glue comprising the reaction products of a mixture of blood, water, and caustic soda in which blood particles are dispersed so as to form a relatively homogeneous viscous cohesive mass, resulting from treating a mixture of water insoluble coagulated blood and water at a temperature of between about 125 F. and about the boiling temperature of the mixture with caustic alkali in an amount between about 0.3 and about 5 parts by weight per 100 arts water.

4. A glue comprising the reaction products of a mixture of blood, water, and caustic soda in which blood particles are dispersed so as to form a relatively homogeneous viscous cohesive mass, resulting from treating a mixture of water insoluble coagulated blood and water at a temperature of between about 125 F. and about the boiling temperature of the mixture with caustic alkali in an amount between about 1 and about 15 parts by weight per 100 parts blood.

5. A glue comprising the reaction products of a mixture of blood, water, and caustic soda in which blood particles are dispersed so as to form a relatively homogeneous viscous cohesive mass, resulting from the treatment of a mixture of water insoluble coagulated blood and water at a temperature of between about 125 F. and about the boiling temperature of the mixture with caustic alkali in an amount between about 0.3 and about 5 parts by weight per 100 parts water, and subsequently cooled and treated with additional caustic alkali and sodium silicate.

67 A glue comprising the reaction products of a mixture of blood, water, and caustic soda in which blood particles are dispersed so as to form a relatively homogeneous viscous cohesive mass, resulting from the treatment of a mixture of water insoluble coagulated blood and water at a temperature of between about 125 F. and about the boiling temperature of the mixture with caustic alkali in an amount between about 0.3 and CROSS REFERENCE about 5 parts by weight per parts water, and subsequently cooled and treated with hydrated lime and sodium silicate.

7. A glue comprising the reaction products of a mixture of blood, water, and caustic soda in which blood particles are dispersed so as to form a relatively homogeneous viscous cohesive mass, resulting rom the treatment of a mixture of water insoluble coagulated blood and water at a temperature of between about F. and about the boiling temperature of the mixture with caustic alkali in an amount between about 1 and about 15 parts by weight per 100 parts blood, and subsequently cooled and treated with sodium silicate.

8. A glue comprising the reaction products of a mixture of blood, water and caustic soda in which blood particles are dispersed so as to form a relatively homogeneous viscous cohesive mass resulting from the treatment of a mixture of water insoluble blood and water at a temperature of between about F. and about the boiling temperature of the mixture with caustic soda in an amount of between about 1 and about 15 parts by weight for each 100 parts blood.

9. A glue comprising the reaction products of a mixture of blood, water and caustic soda in which blood particles are dispersed so as to form a relatively homogeneous viscous cohesive mass resulting from the treatment of a mixture of water insoluble blood and water at a temperature of between about 180 F. and about the boiling temperature of the mixture with caustic soda in an amount of between about 1 and about 15 parts by weight for each 100 parts blood, and subsequently cooled and treated with sodium silicate, saidglue containing in excess of 5 parts of water for each part of blood.

10. A glue comprising the reaction products of a mixture of blood, water and caustic soda in which blood particles are dispersed so as to form a relatively homogeneous viscous cohesive mass resulting from the treatment of a mixture of water insoluble blood and water at a temperature of between about 180 F. and about the boiling temperature of the mixture with caustic soda in an amount of between about 1 and about 15 parts by weight for each 100 parts blood, and subsequently cooled and treated with lime and sodium silicate.

11. A glue comprising the reaction products of a mixture of blood, water and caustic soda in which blood particles are dispersed so as to form a, relatively homogeneous, viscous cohesive mass resulting from the treatment of a mixture of water insoluble blood and water containing between about 1 and about 15 parts by weight sodium hydroxide per 100 parts by weight of blood and having a concentration of between about 0.3% and about 5% by weight sodium hydroxide at a temperature of between about 125 F. and about the boiling temperature of the mixture.

12. A glue base comprising the reaction products of a mixture of blood, water and caustic soda in which the blood constituent consists of coagulated, water insoluble blood dispersed by the action of an aqueous caustic soda solution of between about 0.3% and about 5% concentration at a temperature of between about 180 F. and about the boiling temperature of the mixture and subsequently cooled to room temperature, said caustic soda solution containing of the order of 6 parts of water for each part of blood.

13. The process of dispersing water insoluble, coagulated blood particles to produce an easily Examiner spreadable, relatively homogeneous, cohesive, viscous glue, comprising forming an aqueous mixture of 'said blood particles, the water content of said mixture being not less than :3 parts of water for each part of blood, adding thereto caustic soda in an amount between about 1% and about 15% based on the blood constituent, heating said mixture at a temperature between about 125 F. and the boiling point of the mixture until a substantial portion of the blood particles have dispersed to form a homogeneous, cohesive, viscous mass, and then removing the heat and cooling said mass to substantially normal atmospheric temperature.

14. A process for the production of a glue which comprises dispersing water insoluble blood in an aqueous alkaline medium by reacting it with an aqueous solution of sodium hydroxide having a concentration of between about 0.4% and about 1.6% sodium hydroxide, based on water content, said aqueous solution being used in a total amount sufilcient to supply a total quantity of sodium hydroxide of between about 1 and about 15 parts by weight sodium hydroxide per 100 parts by weight blood and said reaction being effected at a temperature of between about 180 F.

tration of between about 0.3% and about 5% by weight'ol' caustic alkali and containing between about 1 and about 15 parts by Weight caustic alkali per parts by weight blood, heating said mixture at a temperature of between about F. and. about the boilingpoint of the mixture, cooling said mixture and adding to the resulting dispersion a conditioning agent comprising an additional quantity of caustic alkali.

16. A process for the production of a glue base which comprises dispersing water insoluble blood in an aqueous alkaline medium by reacting it with an aqueous solution of sodium hydroxide having'a concentration of between about 0.4% and about 1.6% sodium hydroxide, based on water content said aqueous solution being used in a total amount sufficient to supply a total quantity of sodium hydroxide of between about 1 and about 15 parts by weightsodium hydroxide per 100 parts by weight blood and said reaction being effected at a temperature of between about F. and about the boiling temperature of the solution.

17. A process for the production of a glue base, which process comprises dispersing water insoluble blood in an aqueous medium by the action of a, solution containing between about 0.4 and about 1.6 parts by weight sodium hydroxide per 100 parts by weight water, said solution being used in a total amount sufficient to supply between about 4 and about 9 parts by weight sodium hydroxide per 100 parts by weight blood, at a temperature of between about 180 F. and about the boiling temperature of the solution.

CHARLES N. CONE.