US3095571A

US3095571A - Toasted blood glue

Info

Publication number: US3095571A
Application number: US846628A
Authority: US
Inventors: Charles N Cone
Original assignee: Pacific Resins and Chemicals Inc
Current assignee: Pacific Resins and Chemicals Inc
Priority date: 1959-10-15
Filing date: 1959-10-15
Publication date: 1963-06-25
Anticipated expiration: 1980-06-25

Description

iUU-IU June 25, 1963 C Njaollg Filed Oct. 15, 1959 TOASTED BLOOD GLUE 2 Sheets-Sheet 1 FIGURE I POWDERED SOLUBLE BLOOQ mm mm Io TO Ioo% av WEIGHT (0N DRY moon) oN soup FILLER IN pARTIcLE FORM INsURE THAT THE RESULTING MIXTURE HAS A MoIsTuRE coNTENT or 2. To 35 com. To A TEMPERATURE OF BELOW I70 "F.

MIX WITH WATER AND GLUE-MAKING CHEMICALS, fie.

ALKALI METAL HYDROXIDE, AND PREFERABLE ALKALI METAL SILICATE AND/OR LIME, WITH OR WITHOUT ADDED THERMO5ETTING RESIN FINISHED GLUE CHARLES N. CONE INVENTOR.

BY OIIIIIIIILI June 25, 1963 c N. CONE 3,095,571

TOASTED BLOOD GLUE Filed Oct. 15, 1959 2 Sheets-Sheet 2 FIGURE IE POWDERED SOLUBLE BLOOD MIX WITH 0.5 To I034 BY WEIGHT (ON DRY BLooD) OF AN ALKALINE EARTH METAL CARBONATE HEAT THE MIXTURE AT A MOISTURE CONTENT OF 2 TO 35 Z BY WEIGHT AND A TEMPERATURE ABOVE ITO F. UNTIL THE BLOOD IS SUBSTANTIALLY .DENATURE'D COOL MIX WITH FILLER WATER AND GLUE-MAKING CHEMICALS Le. ALKALI METAL HYDROXIDE AND PREFERABLE ALKALJ METAL sILIcATE AND/OR LIME WITH or: WITHOUT ADDED THERMO- SETTING RESIN FINISHED GLUE CHARLES N. CONE United States Patent 3,095,571 TOASTED BLOOD GLUE Charles N. Cone, Portland, 0reg., assignor, by mesne assignments, to Pacific Resins & Chemicals, Inc., Seattle, Wasln, a corporation of Washington Filed Oct. 15, 1959, Ser. No. 846,628 38 Claims. (Cl. 106-79) This invention relates to a novel toasted blood glue and to a process of making the same. The presently described glue is particularly applicable as a glue for uniting wood veneers in the manufacture of plywood, although it is useful in diverse other applications.

The present application is a continuation in part of my prior application S.N. 453,105 filed August 30, 1954, and of my prior application Ser. No. 663,781, filed June 3, 1957, both applications having been abandoned.

Two grades of blood, soluble and insoluble, are available commercially for use as raw materials in the manufacture of glues. Soluble blood is prepared by drying fresh blood without coagulating it, usually by spraying the blood into a stream of air heated to such a temperature that the blood dries before it has time to coagulate. As the name implies, the product is soluble, or at least dispersible, in aqueous media. Insoluble blood is prepared by heating or otherwise treating fresh blood to coagulate it, after which it is dried and ground. This product is not soluble in water and ordinarily is used for feed or fertilizer.

In my United States Patent 1,976,436, there is disclosed a blood glue comprising soluble blood mixed at normal temperatures with caustic alkali, hydrated lime, and sodium silicate. While this glue is useful for some purposes, it is subject to a pronounced tendency to become too viscous for use and to gel when used in conventional glue spreading apparatus. As a result, it has never been used commercially except in admixture with at least an equal amount of other adhesive materials such as soybean flour and casein, which to some extent mask or control its undesirable viscosity and spreading properties.

In my United States Patent 2,400,541, a glue is described which is made from fertilizer grade, insoluble, coagulated blood, the primary purpose of the invention being to convert this abundant, relatively inert, dried product to a usable glue. The process employed consists of heating the blood in aqueous alkaline medium at a temperature of preferably between 180 F. and the boiling point of the medium. This hydrolyzes or otherwise acts upon the blood and causes it to swell, soften, and disperse until it becomes a relatively homogeneous, viscous mass. The hydrolyzed blood then is cooled to approximately room temperature after which glue conditioning agents includ ing additional alkali, lime and sodium silicate are added to form the final glue mixture.

The above glue also is useful in some applications, but its preparation is attended by the serious difiiculty that the mixture resulting from cooking the blood with alkali p ygemanmumrnesnthickmnnsonling. As a result, it is impossible to secure effective heat transfer between the cooling medium and the glue mixture. This, in turn, extends to many hours the period of time required to bring the mixture down to room temperature, which has apparent disadvantages in loss of time and the necessity of using elaborate cooling equipment.

In my United States Patent 2,895,928, issued July 21, 1959, there is disclosed a blood glue made from either fresh blood or the soluble blood of commerce. It is made by coagulating the blood in dispersed form in an aqueous medium by increasing the temperature of the blood to about 120 F. while agitating it for maintaining the coagulated blood particles in finely divided condition and dispersed throughout the aqueous blood medium. The

resulting aqueous dispersion of coagulated blood then is cooled to a temperature of below F. after which the resulting glue base is converted to a commercial glue by the addition of one or more glue-making chemicals, i.e., glue conditioning agents, including alkali metal hydroxide, preferably with added alkali metal silicate, and/ or lime, and if desired, a thermosetting resin.

The glue made by the latter procedure has had substantial commercial success. Its manufacture and use are, however, attended by certain significant disadvantages. It has some tendency to gel. Its viscosity is such that the amount of water which may be added to it is limited, increasing correspondingly the cost of the glue. The ratio of water to blood in the glue is not adjustable over as wide a range as is desirable to produce a range of glue products suitable for various applications. The precedure for coagulating the blood is relatively time consuming, requires relatively elaborate equipment, and consequently is relatively costly. Since ordinarily preliminary to the coagulating procedure dry soluble blood is introduced into water, a sticky mass having a tendency to lump may be formed, requiring that special precautions be taken.

Still further, the diificulty is present that if the blood is coagulated at a central location for distribution to the plywood plants which use it, the transportation costs are lii'gfifiifi'c''the blood contains such a large proportion of water. On the other hand, if it is desired to overcome this difliculty by coagulating the blood at the plywood plant, special equipment is required which ordinarily is not available. Also, since the proper coagulation of the blood is critical to the success of the final glue, skilled supervision of the coagulating procedure is required. This is particularly true since various sources of blood are used and the coagulating properties of the blood obtained from these sources vary substantially.

However, the most significant disadvantage characterizing the blood glues of my US. Patent 2,895,928 resides in the fact that they have to be mixed immediately before use by the plywood manufacturer at his plant, unsupervised by the glue manufacturer. This procedure requires skilled personnel of a class not always available. This disadvantage stems from the fact that after the soluble blood has been coagulated in aqueous medium, addition of the glue-making (conditioning) chemicals, including alkali metal hydroxide, alkali metal silicate, lime, etc., may produce alkaline hydrolysis of the blood. Also, the blood is subject to putrefaction during storage and shipment unless serious efforts are made to preserve it.

Accordingly, it is the general object of this invention to provide a blood glue and process for making the same wherein the glue base may be prepared by the glue maker at a central location and shipped dry to the mills where it is mixed with the glue-making chemicals, resulting in the formulation of a glue of superior properties.

In accordance with one form of the presently described process, powdered soluble blood is mixed wi Ol n-"1Q- mMby weightfbaseoift'he'weighfof the dry blood, of a p wdered solid filler. Next, the moisture content of the resulting mixture is adjusted, if necessary, to insure a moisture content of from 2 to 35%. The solid mixture of controlled moisture content next is heated with agitation for denaturing the blood.

I have further found that an economic advantage may be obtained by pretreating soluble blood powder with a minor proportion, i.e. from 0.5 to 10% by weight based on th blood, of a aw used mg '5 nely divided, pgwwduct.

tion of heat the particles remain separate, or form friable aggregates which may easily be reduced to the form of denatured blood particles. This result, using finely divided earth metal carbonate enables heating and handling of smaller proportion of filler material.

Although the reactions occurring during the heating operation are not capable of precise definition, the blood is denatured to form a product which is different from that obtained by coagulating blood in aqueous medium. Thus, the denatured product is substantially insoluble in water. However, it retains a substantial solubility in a dilute aqueous solution of alkali metal hydroxide at a temperature of less than 100 F.

After denaturing, the grainy, solid mass is cooled to a temperature of below 170 F., preferably below 120 F. This forms the glue base, which may be shipped dry to the desired plant destination. There it is mixed with water and the selected glue-making chemicals in the selected proportions. This results is the formulation of the finished glue.

Hence it will be seen that the process disclosed herein differs essentially from that set forth in my aforesaid United States Patent 1,976,436, in that in the process of the patent the soluble blood is used throughout in aqueous medium and no attempt is made to coagulate it. To the contrary, coagulation of the b lood ba se material s call ided whereas in the instant application the blood base material is denatured in the dry state prior to the incorporation of the conditioning chemicals.

Also, the process disclosed herein differs fundamentally 7 rom that disclosed in my aforesaid Patent U. S. 2,400,541 in that the process of the latter employs dried, insoluble or coagulated blood as the base material and uses a causticalkali treatment at elevated temperature as a means of dispersing the blood and dissolving it in an aqueous medium. In the present process, on the other hand, soluble blood is used as the starting material. This is denat'iird in" of'dffiiifiitiofitm'i'esirltihg denatured solid product then is used as the glue base and is mixed with the glue-making chemicals.

Still further, the presently described process differs fundamentally from that disclosed in my US. Patent 2,895,928 in that, in the process disclosed in the latter, soluble blood is placed in aqueous medium and then coagulated by the application of heat. After heating, the aqueous suspension of coagulated blood particles is cooled and mixed with the glue-making chemicals, water being present at all times as the conveying or suspending medium.

In the process of this invention, on the other hand, the soluble blood is denatured by the application of heat to solid blood having a certain stipulated moisture content, this being substantially less than the amount required to dissolve or disperse the blood. The resulting solid product then forms the glue base which may be converted to a commercially useful adhesive by the addition of gluemaking chemicals such as alkali metal hydroxide, preferably with added alkali metal silicate, and/or lime, with or without the addition of a thermosetting resin.

Considering the procedure of this invention in greater detail, and with particular reference to the drawings, consisting of FIGS. 1 and 2 each being a flow plan of the presently described process:

The blood which is employed as the starting material for the process of this invention comprises, as has been stated above, the SPIa5L dIied. Oluble blc odsm mm This is obtainable in the form of a powder of varying particle size. In general, however, a finely divided product should be employed, i.e. one having a particle size of less than 20 mesh, preferably less than 100 mesh, U.S. Sieve Series. If blood having too large a particle size is used, the subsequent denaturing process is non-uniform and the glue will contain swollen blood particles of such a size as to impair its spreading char acteristics.

The soluble blood starting material first is mixed with a powdered solid filler. The addition of such a filler is required since the blood is heated in powdered form. Consequently, if the filler is not added, the present techniques for heating and denaturing the blood cause it to cake and to stick to the walls of the vessel in which it is contained. In addition, the presence of the tiller materially accelerates the denaturing operation.

The amount of orgfgni c flller to be used varies from 10 to preferab y from 20 to 60% by weight, dry blood basis. Generally, if less than 10% by weight is employed, the blood sticks to the containing vessel to such an extent that the denaturing operation cannot be carried out eflectively. However, If more than 100% by weight is used, the adhesive qualities of the resulting glue are materially impaired, so that an inferior bond is obtained.

A wide variety of fillers may be used, either qrganic or inorganic, pr thydn not degrade the blood. As examples of organic fillers, there may be cited soybean flour and similar powdered vegetable material," powdered insoluble blood, and the cellulosic fillers such as wood flour, walnut shell flour, powdered bark and selected mechanical fractions of powdered bark. Diatomaceous earth, powdered clays, and talc are examples of suitable inorganicfillers. Although the particle sizes of the filler is variable, it should be finely divided, having a particle size of less than 20 mesh, preferably less than 100 mesh, U.S. Sieve Series.

When the soluble blood starting material is mixed h a P i.e. of c ma nesiugirrium or strontium, a lesser proportion of filler, i.e. from 03 m By weight may be used. Of these, calcium carbonate is preferred because of its effective action and availability.

The carbonate material should be in finely divided form, having a mesh size of through 200 mesh or smaller, preferably less than 325 mesh U.S. Sieve Series. An eminently suitable carbonate material is commercial precipitated calcium carbonate having a particle size of from .04 to .05 micron.

It also is essential for the success of the presently described process that the moisture content of the mixture of blood and filler be maintained at a level of from 2 to 35% by weight, preferably from 6 to 20% by weight, based on the dry weight of the mixture. If less than this amount of moisture is present, the denaturing operation takes place very slowly, too slowly to be practical. However, if more than this amount of moisture is present, the mixture cakes excessively on heating, cannot be handled satisfactorily, and produces a glue having poor spreading characteristics.

In addition, there is a tendency to degrade the blood extensively, particularly with long denaturing durations. Adjustment of the moisture content of the mixture may be accomplished in any desired way, as by drying the raw materials before mixing them, or by adding moisture to them, as required.

Nejftthe bloodfiller mixture of controlled moisture content is' h'eated to denatu r'ethe blood. This operation may be effectuated imarrysuitable-equipment wherein means are provided for agitating the blood while heating it uniformly. Thus, it may be carried out in a steam jacketed cylinder provided with rotating scraper blades which prevent the blood from adhering to the interior of the cylinder and at the same time agitate it effectively. Also, it may be carried out in apparatus comprising a cylinder containing a pair of hollow, steam heated, interlocking screws which agitate the blood while heating it and advancing it the length of the cylinder.

The dry powdered soluble blood in admixture with solid filler is denatured by heating the mixture at a temperature between F. and 350 F. for so long a time as its moisture content dictates. Such heating to produce satisfactory denaturation normally will extend from M4 to 3 hours.

It will be appreciated that in view of the diverse sources of the soluble blood of commerce, the various conditions of spray drying to which it has been subjected, the length of time it has been stored, the nature and particle size and relative proportion of filler employed, the moisture content of the mixture, etc. make it extremely difiicult to set arbitrary limits on the time and temperature required for denaturing the blood according to the presently described procedure.

Whatever the apparatus employed, the blood is heated until it is denatured sufiiciently to produce a satisfactory glue base. This is accomplished when the denaturing operation has proceded to such an extent that the blood has been rendered substantially insoluble in water. This may be determined by placing a sample of the denatured product in water and noting whether coloring of the water occurs. If the coloring produced by the introduction of the blood is not substantial, then it has been denatured to the desired extent.

If the blood is insufficiently denatured, a satisfacory glue is not obtained because it will have the defects noted above as being characteristic of the blood glue described in my U.S. Patent 1,976,436. Also, it cannot be used at the high water content characterizing the glue of the present invention.

It also is necessary that the blood not be over denatured. If this is the case, the addition of the gluemaking chemicals at a later stage is not effective in swelling and softening the blood granules and dispersing the blood as required to provide a satisfactory glue. Accordingly, the denaturing operation should be carried on only to such an extent that the blood retains substantial dispersibility in cold, dilute aqueous alkali metal hydroxide, i.e., alkali metal hydroxide at a temperature of less than 100 F.

Although insofar as is known by me, no test standards are available for measuring the dispersibility of a blood glue base in alkali substantial solubility in aqueous alkali metal hydroxide, as defined herein, is obtained when the blood passes the following test procedure, which represents an appropriate modification of the test procedure advanced by the Armour Co., of Chicago, Illinois, for determining the water solubility of blood.

A sample containing grams of blood and having a moisture content of about 10%, is placed in 100 cubic centimeters of 0.2% sodium hydroxide at a temperature of from 60 to 80 F. The resulting mixture is stirred for one hour and then permitted to stand for an additional hours. At the end of this time it is stirred and filtered. For the present purposes at least 1% of the blood should be dispersed or dissolved in the filtrate.

After the blood has been heated until it has been den tured and dried t2 the desired extehmm a temperature 0 less 555770 F, preferably less than 120 F. This terminates the denaturing operation. The cooling may be etiectuated in any suitable manner, as by expelling the blood mixture from the denaturing apparatus and permitting it to cool by depositing it in thin layers in air on a suitable support, by permitting it to flow a predetermined distance through air at substantially atmospheric temperature, or by passing it with agitation through a cylinder having a water cooled jacket.

The glue base obtained in this manner is gagulgg and may contain 'a proportion of friable aggregates, resulting from the fusing together of the blood particles during the denaturing operation. The product may then be processed for disintegration of the aggregates into particles which are discrete and have but little tendency to stick to each other. Since it is substantially dry, it may be stored for long periods of time and shipped togagp us plant locations without danger of degradation. Accordingly, it is ready for use as a glue base to which various glue-making agents may be added for the production of a glue having the desired properties.

Such agents, defined broadly herein as glue conditioning chemicals, comprise in general alkali metal caustic, including principally sodium hydroxide and potassium hydroxide; alkali metal silicates, including primarily sodium silicate; and lime, or an equivalent material. A thermosetting resin also may be incorporated, depending upon whether a highly water-and-mold-resistant glue product is desired.

The denatured blood-filler mixture and the glue-making or conditioning chemicals are mixed together in the desired proportions together with the amount of water necessary for the production of a glue having the required consistency. Although the proportions of constituents in a :given glue formulation are variable, in general they fall within the following broad range, proportions being expressed in parts by weight.

TABLE I General range A glue having the above composition has decided adhesive characteristics and is suitable for some purposes. However, a better glue is obtained by the addition of other conditioning chemicals, i.e. alkali metal silicate, and/or lime. Preferably, both of these additional conditioning agents are included, in which case the glue will have the following formulation, proportions being expressed in parts by weight.

TABLE II General range In addition to the foregoing constituents, there may be included an a i ent such as pine oil. This may be included in the proportion required to overcome any foaming problem which may be present. In general, from 1 to 10 parts pine oil are suitable for this purpose, the proportion of the remaining ingredients being as given above.

The mixing operation, whereby the denatured blood glue base is mixed with the glue-making or conditioning chemicals may vary as required. In general, a mixing vessel is employed which is provided with means for agitating the contents. The solid glue base comprising denatured blood and filler is added first with part of the water. Next, the alkali metal caustic dissolved in a predetermined amount of water is added, with stirring.

Next, the lime may be mixed with suflicient water to disperse it and added with further stirring. Finally, the alkali metal silicate may be added in the form of its commercial water solution, and thoroughly incorporated in the mix. The pine oil, or other anti-foaming agent, may be added at any suitable point in the procedure. Also, if filler is required in addition to that mixed with the blood prior to denaturing, it may be incorporated at a suitable point in the mixing procedure. After the constituents have been blended together thoroughly, the glue may be withdrawn from the mixer and is ready for application.

As has been indicated above, here also may be incorporated in the presently described glue, a thermosetting resin which makes the glue particularly useful in hot press operations, forming a strong bond, improving its handling properties, improving the water resistance of the glued product and improving its resistance to attack by microorganisms such as bacteria, molds and fungi. The glues described herein are particularly well suited for use with such resins since the addition of the resin does not cause the glue mix to thicken and gel and become inapplicable on conventional glue spreaders. This has been a problem widely encountered in the use of blood and other (e.g. soybean") glues containing thermosetting resins.

Furthermore, the use of the resin has the beneficial effect of substantially improving the assembly time and spreadability of the glue. Still further, contrary to expectations, the thermal requirements of the glue, i.e. the amount of heat required to set it in a hot press operation, are not materially increased by the addition of the thermosetting resin.

The thermosetting resins which may be used together with the blood glues of the present invention comprise broadly the phenol-aldehyde resins as a class. Illustrative of such resins are the resinous condensation prodnets of phenol and formaldehyde, the cresols and formaldehyde, resorcinol and formaldehyde, phenol and furfural and the like. These may be used in their usual commercial form, i.e. in the for of their aqueous solutions having a solids content of about 40% by weight.

The amount of thermosetting resin incorporated in the presently described glue may vary, for example, from about parts to about 1000 parts by weight (solids basis) of thermosetting resin per 100 parts of blood, the other constituents of the mix being employed in substantially the proportions set out above. The thermosetting resin may be incorporated at various stages of the mixing procedure, although it is preferred to add it after the caustic alkali has been added to the denatured blood glue base.

Thus in this preferred procedure, the blood may be denatured by the action of heat in admixture with a filler as indicated above. The denatured product then is cooled, if necessary, after which water, caustic soda, lime, sodium silicate, filler and an anti-foaming agent are added, these materials being intimately mixed together to form a thick, grainy mixture. The phenolic resin then is added as an aqueous solution, if desired, and the mixing continued until the resin has been intimately dispersed throughout the glue mixture. The glue then is ready for application to the wood veneers or other objects to be glued together.

The glue mixtures prepared as described above may be applied in the plywood fabricating operation using the conventional glue spreaders and other equipment. Their application in such equipment is particularly easy because of their spreadability, stable viscosity, and nongelling characteristics. Also, their consistency is such as to prevent excessive penetration into the wood veneers during the assembling operation, which increases the assembly time correspondingly. After applying the glue, the veneers may be assembled in the usual manner and pressed, either in the cold press or in the hot press, depending upon the particular composition employed and the plywood application contemplated.

The novel glues of the present invention and the process for their preparation are illustrated in the following examples wherein parts are expressed as parts by weight.

Example 1 100 parts of spray dried soluble blood and 45 parts of wood flour filler were mixed together. The resulting mixed powder had a moisture content of 9.75%, dry basis. 35 pounds of this powder was introduced into a horizontal steam jacketed, cylindrical heater provided with means for stirring the powder and scraping it from the inner heated surface of the cylinder.

The stirring and scraping mechanism was put into operation and steam at 115 p.s.i. (374 F.) passed through the jacket of the mixer. The temperature of the bloodfiller mixture within the heater was determined at intervals. After 5 minutes its temperature was 223 F.; after 11 minutes it was 243 F.; and after 15 minutes it was 260 F. At the end of 15 minutes, a 4 lb. sample was withdrawn from the heater and cooled rapidly by con tact with atmospheric air to a level of below 120 F.

Example 2 Another sample of denatured blood glue base was obtained by continuing the heating operation described in Example 1 until a total heating time of 23 minutes had elapsed. At the end of this time the temperature of the blood-filler mixture within the heater had risen to 293 F. A sample was withdrawn at this temperature level and cooled to a temperature of below 120 F.

Example 3 Still another sample was obtained by continuing the heating operation of Example 1 until the total elapsed time of heating was 31 minutes. The heated mixture thereupon had reached a temperature of 310 F. A sample then was withdrawn from the heater and cooled to a temperature of below 120 F.

Example 4 Ten pounds of a mixture of spray dried soluble blood and wood flour in the same proportions as set forth in Example 1 was introduced into the heater described in that example. In this case, temperature elevation of the sample occurred much more rapidly than in the preceding examples, because of the relatively small weight of blood mixture heated. At the end of 5 minutes heating, the temperature of the mixture had reached 276 F. and after 9 minutes it had reached 304 F. Thereupon a sample was withdrawn and cooled below a temperature of 120 F.

Example 5 Thirty-five pounds of the dry soluble blood-wood flour mixture of Example 1 was introduced into the heater described in that example. Steam at 115 psi. (347 F.) was introduced into the heater jacket. However, as soon as the temperature of the mixture had reached 218-227 F., the steam was applied intermittently as required to maintain this relatively low temperature range.

The contents of the heater then were heated at this temperature level for minutes, after which a sample was withdrawn and air cooled to a temperature of less than 120 F.

Example 6 The procedure of Example 5 was repeated with the exception that the steam pressure was applied in such a manner as to maintain the contents of the heater at a temperature of from 199 to 206 F. After minutes a sample was withdrawn and air cooled to a temperature of below F.

Example 7 Thirty-five pounds of the soluble blood-wood flour mixture of Example 1 was contemporaneously stirred and sprayed with water until the moisture content of the mixture, dry basis, had been adjusted to 15.7 by weight. The moist mixture was then introduced into the heater of Example 1 and treated in the manner described in that example. After six minutes of heating the temperature of the mixture had reached 226 F., after fourteen minutes, 277 F. A sample was then withdrawn and cooled rapidly to a value of less than 120 F. by contact with air at atmospheric temperature.

Example 8 100 parts of spray dried soluble blood was mixed with 38 parts of 325-mesh walnut shell flour. 36 pounds of the resulting mixture was introduced into the heater and Example 9 The cooled powders of Examples l8 were put individually through a grinder for disintegration of any lumps that had formed. Glues then were made using the powdered glue bases of Examples 2, 4, 5, 6, 7 and 8, as follows:

140 parts of the glue base was mixed with 890 parts water at 65 F. Five parts pine oil then was added. To this mixture was added 24 parts of 50% aqueous caustic soda solution and 14 parts hydrated lime suspended in 28 parts water. The resulting mixture was stirred for ten minutes and then 50 parts silicate of soda added and the stirring continued for another three minutes.

The resulting glues contained soft swollen grains of denatured blood. They were fluid and not characterized by a dry graininess.

All of them were of superior spreading consistency, having viscosities within the broad range of 40 to 500 poises, specifically 150 to 300 poises. In addition, their consistencies, handling properties and adhesive qualities were excellent, showing that in each case the blood had been denatured to about the same degree. All of them were superior for the gluing of plywood.

The results obtained using the glue base of Example 4, as compared with those obtained using that of Example 2, illustrate that the denaturing is more rapid at an elevated temperature. The application of the glue bases of Examples and 6 illustrates that satisfactory denaturing can be accomplished at lower temperatures by prolonging the time of heating. Use of the glue base of Example 7 in the production of a satisfactory glue illustrates the acceleration of the denaturing rate by increasing the amount of moisture present.

Other glue formulations were made following the general procedure outlined above but using various glue conditioning chemicals in various proportions. These demonstrate the effect of such variation and, in the case of Examples 15 and 16, illustrate the accommodation of the formula to suit glue bases made by procedures resulting in divergent degrees of denaturing. These were as fol- 10 applied to the core veneer the panel assembly was put under a pressure of 290 pg ilhwti g This pressure was maintained for 14 minutes.

At the end of this time sufiicient bond was formed so that the panels could be handled. The panels were allowed to stand for six days in order to let the bond fully cure and then 20 one-inch shear strength test pieces were cut from each panel. Ten test pieces from each panel were sheared on a standard break machine and the shear strength and wood failure noted.

Also ten test pieces from each panel were soaked in water at F. for two days. Thereafter they were removed from the water, broken and again evaluated for shear strength and wood failure. In all cases substantial bonding of the veneers was obtained, even when the lime and/or sodium silicate were omitted. Markedly superior bonding was obtained however, when these glue conditioning agents were included.

Example 17 This example illustrates the application of the presently described blood glues in conjunction with a thermosetting phenolic resin.

A glue base was prepared according to the procedure of Example 2. It was formulated into a glue using the general procedure outlined in Example 9, except that after the addition of the sodium silicate 40 pounds of a liquid 50% solids phenol formaldehyde resin was added and the stirring continued for three minutes.

This glue was used in the manufacture of plywood using the same procedure outlined in Example 9, except that the wet glue spread was reduced to approximately lbs. per thousand square feet of core veneer. The panels were then hot ressed for 3 minutes in a press having platens heated to 260 F. Tl're'p'ressure on the panels was 200 lbs. per square inch. The resulting panels were tested for shear strength, wood failure, water resistance, and mold resistance, and found to be superior in all of these qualities.

When a mixture of denatured blood and a small proportion of extremely finely divided carbonate is used, this mixture is mixed with cellulosic filler and the glue making chemicals in the desired proportions together with the amount of water necessary for the production of a glue having the required consistency. Although the proportions of constituents in a given glue are variable, in general they fall within the following broad range, prolows; portions being expressed in parts by weight.

TABLE III H20 at Powder Amt. KOH in 50% Lime 1n Silicate Viscosity, Er. N0. 65 F. Pine oil of powder H2O NaOH Hi0 Stir of soda Stir poises Ex. No. soln.

890 5 2 24 14-28 10' 50 3' 233 5 2 24 14-28 10 146 890 5 2 24 10' so 3' 111 see 5 2 24 10 are 890 5 2 14-28 10' 5o 3' 284 825 5 s 22 13-2 10' 45 a 264 600 5 1 24 14-28 10 50 3 247 H2O at F.

Plywood panesl were made with the glues of Examples TABLE IV 9-16. In each case the glue was spread uniformly on both surfaces of a .1 inch Douglas Fir veneer at the rate General Preferred of -130 lbs. of wet glue per thousand square feet of 70 range range core veneer.

Blood 100 100 The core veneer with wet lied was laid between 1; earth mem1ca1-b0nate (1540 340 t v sFir ven "em 'e 3 er 10-100 20-60 t shee s of 1 inch D 11.,1a r o ass hi my aoHzoo M00 a 3-ply ply woo pane each ply consisting of .1 inch of Alkali metal caustic 1-50 5-20 Douglas Fir veneer. Eighteen minutes after the glue was 75 1 1 The above composition has decided adhesive characteristics and is suitable for some purposes. However, a better glue is obtained by the addition of other conditioning chemicals, i.e. alkali metal silicate and/ or lime. Prefer- ,ably both the additional conditioning agents are included,

in which case theglue will have the following formulation,

:proportions being expressed in parts by weight.

In addition to the foregoing constituents, there may be included further components as previously described for mixtures of denatured blood and filler requiring larger proportions for effective action.

Example 1 30 pounds of spray-driedsoluble-blood and 1.6 pounds (5.3% by weight) of pr carbonate hava article size of 04 .05 micron were 1m 1m y mixe together. The resulting mixed powder had a moisture content of approximately 8%, dry basis. This powdery mixture was introduced into a horizontal, steamjacketed, cylindrical heater provided with means for stirring the powder and scraping it from the inner heated surface of the cylinder.

The stirring and scraping mechanism was put into operation and steam at 115 p.s.i. (347 F.) passed through the jacket of the mixer. The temperature of the bloodcalcium carbonate mixture within the heater was measured at predetermined time intervals, and samples withdrawn as follows:

Heating time (minutes) Temperature F.

Sample No.

attained) Immediately after heating each sample was cooled to a temperatureof below 120 F.

The foregoing example was repeated, except that steam was applied until the contents of the heater had reached a temperature of 204to 215 P. where it was maintained. Samples then were withdrawn at the following time intervals:

Heating Tempera- Sample No. time ture F.

r (minutes) attained) 12 of wood flour. T o the resulting mixture there were added 8 to 25 parts water at 75 F. and five parts pine oil. 26 parts of a 50% aqueous solution of caustic soda and 13 parts hydrated lime suspended in 26 parts of water then were added in succession. The resulting mixture was istirred for five minutes after which 50 parts sodium silicate were added and the stirring continued for another three minutes.

The glues produced by the foregoing procedure contained soft, swollen grains of denatured blood. They were fluid and not characterized by dry graininess. All ofthem were of superior strength and consistency, having viscosities within the broad range of 40-500 poises, specifically -400 poises. In addition, their consistencies, handling properties, and adhesive qualities were excellent. All were superior for-use in the gluing of plywood.

Example 19 This example illustrates the application of the presently described blood glues in conjunction with a thermosetting phenolic resin.

A glue base was prepared according to the procedure of Example 1 wherein the heating was carried out for a total heating time of 12 minutes (Sample No. 3). It was formulated into a glue using the general procedure outlined in Example 1, except that after the addition of the sodium silicate, 40 parts of a liquid 50% solids phenol formaldehyde resin was added and the stirringcontinued for three minutes.

This glue was used in the manufacture of plywood using a glue spread of approximately 80 lbs. per thousand square feet of core veneer. The panels were then hot pressed for three minutes in a press having platens heated to 260 F. The pressure on the panels was 200 lbs. per square inch. The resulting panels were tested for shear strength, wood failure, water resistance, and mold resistance, and found to be superior in all of these qualities.

Accordingly, it will be apparent that by the present invention I have provided a novel blood glue and a process of making the same which are characterized by several advantages of the greatest significance. The glue is characterized by superior spreadability and high bonding strength; Its viscosity characteristics are such that a subtantial proportion of 'water, at least '15 more than can be used with the glue disclosed in my aforesaid patent, Serial No. 461,947; may be employed in the formulation of the final glues. This cuts down the glue cost correspondingly.

In addition, the glue base may be prepared using relatively simple equipment in a-rapid, efficient operation. When prepared, it is stable and may be shipped dry to the plants where it is to be used. The glue then may be formulated at the plant without the use of elaborate equipment and highly skilled personnel. In this manner, substantial savings are achieved through lower transportation and labor costs.

Having thus described my invention in preferred embodiments, I claim:

1. The process of making a glue base which comprises mixing spray dried soluble blood particles with from 10% to by weight of solid filler in particle form to form a mixture, insuring that the moisture content of the mixture is from 2% to 35% by weight based on the dry weight of the mixture, denaturing the blood in the mixture by heating the mixture above F. until the blood content thereof is substantially insoluble in water, while retaining substantial solubility in dilute aqueous alkali metal hydroxide at a temperature of less than 100 F., and cooling the heated mixture to a temperature of below 170 F. for arresting the denaturing operation.

2. The process of making a glue base-which comprises forming a mixture of spray dried soluble blood in particle form with from 20 to 60%- by weight of solid filler, insuring that the moisture content of the resulting mixture is from 6 to 20% based on the dry weight of the mixture denaturing the blood in the mixture by heating the mixture above 170 F. until the blood content thereof is substantially insoluble in water, but retains substantial solubility in dilute aqueous alkali metal hydroxide at a temperature of less than 100 F., and cooling the heated mixture to a temperature below 170 F. for ar resting the denaturing operation.

3. The process of making a glue which comprises mixing spray dried soluble blood particles with from to 100% by weight of solid filler in particle form, insuring that the moisture content of the resulting mixture is from 2 to 35% by weight based on the dry weight of the mixture, denaturing the blood in the mixture by heating the mixture above 170 F. until the blood content thereof is substantially insoluble in water but retains substantial solubility in dilute aqueous alkali metal hydroxide maintained at a temperature of less than 100 F., cooling the heated mixture to a temperature below 170 F. for arresting the denaturing operation, and admixing with the resulting cooled glue base glue-making chemicals comprising alkali metal caustic and water.

4. The process of making a glue which comprises mixing spray dried soluble blood with from 10 to 100% by weight of solid filler in particle form, insuring that the moisture content of the resulting mixture is from 2 to 35% by weight, denaturing the blood in the mixture by heating the mixture above 170 F. until the blood content thereof is substantially insoluble in water, while retaining substantial solubility in dilute aqueous alkali metal hydroxide at a temperature of below 170 F. for arresting the denaturing operation, and forming a mixture comprising the resulting denatured blood glue base, alkali metal caustic and water in the following proportions:

5. The process of claim 4, wherein the alkali metal caustic comprises sodium hydroxide.

6. The process of making a glue which comprises mixing spray dried soluble blood with from 20 to 60% by weight of solid filler in particle form, insuring that the moisture content of the resulting mixture is from 6 to 20% by weight, denaturing the blood in the mixture by heating the mixture above 170 F. until the blood content thereof is substantially insoluble in water while retaining substantial solubility in dilute aqueous alkali metal hydroxide maintained at a temperature of less than 100 F., cooling the heated mixture to a temperature of below 170 F., for arresting the denaturing operation, and forming a mixture comprising the cooled blood glue base, alkali metal caustic, and water in the following proportions:

Parts by weight 7. The process of making a glue which comprises mixing spray dried soluble blood particles with from 10 to 100% by weight of solid filler in particle form, insuring that the moisture content of the resulting mixture is from 2 to 35 by weight, denaturing the blood in the mixture by heating the mixture above 170 F. until the blood content thereof is substantially insoluble in water but retains substantial solubility in dilute aqueous alkali metal hydroxide at a temperature of less than 100 F., cooling the heated mixture to a temperature of below 170 F. for arresting the denaturing operation, and forming a mixture comprising the cooled blood Filler 10 00 Water 300-1200 Alkali metal caustic k li metal silicate IMQO 8. The process of making a glue which comprises mixing spray dried soluble blood particles with from 10 to by weight of solid filler in particle form, insuring that the moisture content of the resulting mixture is from 2 to 35% by weight, denaturing the blood in the mixture by heating the mixture above F. until the blood content thereof is substantially insoluble in water while retaining substantial solubility in dilute aqueous alkali metal hydroxide at a temperature of less than 100 F., cooling the heated mixture to a temperature of below 170 F. for arresting the denaturing operation, and incorporating the resulting denatured blood glue base in a mixture comprising:

Parts by weight 9. The process of making a glue which comprises mixing spray dried soluble blood particles with from 10 to 100% by weight of solid filler in particle form, insuring that the moisture content of the resulting mixture is from 2 to 35% by weight, denaturing the blood in the mixture by heating the mixture above 170 F. until the blood content thereof is substantially insoluble in water while retaining substantial solubility in dilute aqueous alkali metal hydroxide maintained at a temperature of less than 100 F., cooling the heated mixture to a temperature of below 170 F. for arresting the denaturing operation, and incorporating the resulting denatured blood glue base in a mixture comprising:

Parts by weight 10. The process of making a glue which comprises mixing spray dried soluble blood particles with from 10 to 100% by weight of solid filler in particle form, insuring that the moisture content of the resulting mixture is from 2 to 35% by weight, denaturing the blood in the mixture by heating the mixture above 170 F. until the blood content thereof is substantially insoluble in water while retaining substantial solubility in dilute aqueous alkali metal hydroxide maintained at a temperature of less than 100 F., cooling the heated mixture to a temperature of below 170 F. for arresting the denaturing operation, and incorporating the resulting denatured blood glue base in a mixture comprising:

Parts by weight mixing spray dried soluble blood particles with from 10 to 100% by weight of solid filler in particle form, insuring that the moisture content of the resulting mixture is from 2 to 35 by weight, denaturing the blood in the mixture by heating the mixture above 170 F. until the Denatured blood 100 Filler 10-100 Water 300-1200 Alkali metal caustic 1-50 Thermosetting phenol aldehyde resin 10-1000 12. The process of making a glue which comprises mixing spray dried soluble blood particles with from 10 to 100% by weight of solid filler in particle form, insuring that the moisture content of the resulting mixture is from 2 to 35% by weight, denaturing the blood in the mixture by heating the mixture above 170 F. until the blood content thereof is subst-antially insoluble in water while retaining substantial solubility in dilute aqueous alkali metal hydroxide at a temperature of less than 100 F., cooling the heated mixture to a temperature of below 170 F. for arresting the denaturing operation, and incorporating the resulting denatured glue base in a formulation comprising:

Parts by weight 13. The process of making a glue base, comprising: mixing spray dried soluble blood with solid filler in particle form at a ratio of blood to filler between 100:10 and 100:100; denaturing the blood in the mixture by heating the mixture between 170 F. and 350 F. in the presence of moisture at a ratio of mixture to moisture between 100:2 and 100:35; and thereafter cooling the mixture to below 120 F. to arrest denaturation of the blood.

14. The process of making a glue, comprising: mixing spray dried soluble blood with solid filler in particle form at a ratio of blood to filler between 100:10 and 100:100; denaturing the blood in the mixture by heating the mixture between 170 F. and 350 F. for a time from A to 3 hours in the presence of moisture at a ratio of mixture to moisture between 10022 and 100:35; and thereafter cooling the mixture to below 120 F. to arrest denaturation of the blood.

15. The process of making a glue base, comprising: mixing spray dried soluble blood with solid filler in particle form at a ratio of blood to filler between 100:10 and 100:100; heat denaturing the blood in the mixture between 170 F. and 350 F. in the presence of moisture at a ratio of mixture to moisture between 100:2 and 100:35 until the blood is substantially insoluble in water while retaining substantial solubility in dilute aqueous alkali metal hydroxide at a temperature below 100 F.; and cooling the mixture to below 120 F. to arrest denaturation of the blood.

16. The process of making a glue base, comprising mixing spray dried soluble blood with solid filler in particle form at a ratio of blood to filler between 100: 10 and 100:100; heat denaturing the :blood in the mixture between 170 F. and 350 F. for a time from A to 3 hours in the presence of moisture at a ratio of mixture to moisture between 100:2 and 100:35 until the blood is substantially insoluble in water while retaining substantial solubility in dilute aqueous alkali metal hydroxide at a temperature below 100 F.; and cooling the mixture to below 120 F. to arrest denaturation of the blood.

17. The process of making a glue base, comprising: mixing spray dried soluble blood with solid filler in par- 16 ticle form at a ratio of blood to filler between :10 and 100:100; agitating the mixture and denaturing the blood in the mixture by heating the mixture between 170 F. and 350 F. in the presence of moisture at a ratio of mixture to moisture of between 100:2 and 100:35; and thereafter cooling the mixture to below F. to arrest the denaturation of the blood.

18. The process of making glue, comprising: mixing spray dried soluble blood with solid filler in particle form at a ratio of blood to filler between 100:10 and 100:100 agitating the mixture and denaturing the blood in the mixture by heating the mixture between F. and 350 F. for a time from A to 3 hours in the presence of moisture at a ratio of mixture to moisture between 100:2 and 100:35; and thereafter cooling the mixture to below 120 F. to arrest denaturation of the blood.

19. The process of making a glue base, comprising: mixing spray dried soluble blood with solid filler in particle form at a ratio of blood to filler between 100:10 and 100:100; agitating the mixture and heat denaturing the blood in the mixture between 170 F. and 350 F. in the presence of moisture at a ratio of mixture to moisture between 100:2 and 100:35 until the blood is substantially insoluble in water while retaining substantial solubility in dilute aqueous alkali metal hydroxide at a temperature below 100 F.; and cooling the mixture to below 120 F. to arrest denaturation of the blood.

20. The process of making a glue base, comprising; mixing spray dried soluble blood with solid filler in particle form at a ratio of blood to filler between 100:10 and 100:100; agitating the mixture and heat denaturing the blood in the mixture between 170 F. and 350 F. for a time from A to 3 hours in the presence of moisture at a ratio of mixture to moisture between 100:2 and 100:35 until the blood is substantially insoluble in water while retaining substantial solubility in dilute aqueous alkali metal hydroxide at a temperature below 100 F.; and cooling the mixture to below 120 F. to arrest denaturation of the blood.

21. The process of making a glue base which comprises mixing spray dried soluble blood powder with from 0.5 to 10% by weight based on the blood powder of a carbonate 0 an alkaline earth metal selected from the group consisting of calcium, magnesium, strontium and barium in powdery form, denaturing the blood in the mixture by heating it at a moisture content of from 2% to 35 and at a temperature of above 170 F. and below the charring temperature of the blood until the blood content thereof becomes substantially insoluble in water, while retaining substantial solubility in dilute aqueous alkali metal hydroxide at a temperature of less than 100 F. and cooling the heated mixture to a temperature below 170 F. for arresting the denaturing operation.

22. The process of claim 21 wherein the carbonate of an alkaline earth metal comprises calcium carbonate.

23. The process of claim 21 wherein the carbonate of an alkaline earth metal comprises magnesium carbonate.

24. The process of claim 21 wherein the carbonate of an alkaline earth metal comprises barium carbonate.

25. The process of claim 21 wherein the carbonate of an alkaline earth metal comprises strontium carbonate.

26. The process of making a glue base which comprises mixing spray dried soluble blood powder with from 3 to 10% by weight based on the blood powders of powdery calcium carbonate, heating the mixture at a moisture content of from 6-20% by weight and a temperature of above 170 F. and below the charring temperature of the blood until the blood content thereof becomes substantially insoluble in water while retaining substantial solubility in dilute aqueous alkali metal hydroxide at a temperature of less than 100 F., and cooling the heated mixture to a temperature of below 170 F. for arresting the denaturing operation.

27. The process of making a glue which comprises mixing spray dried soluble blood powder with from 0.5

17 to by weight based on the blood powder of a pen?- dery carbonate of an alkaline earth metal selected from the group consisting of calcium, magnesium, strontium and barium, heating the mixture at a moisture content of from 235% by weight and a temperature of above 170 F. and below the charring temperature of the blood until the blood content thereof is rendered substantially insoluble in water but retains substantial solubility in dilute aqueous alkali metal hydroxide maintained at a temperature of less than 100 F., cooling the heated mixture to a temperature below 170 F. to arrest the denaturing operation, and mixing with the resulting denatured blood glue base glue making chemicals comprising alkali metal caustic, a finely divided cellulosie filler having a particle size of less than 20 mesh and water in the following proportions:

Parts by weight Blood glue base 100 Filler 10-100 Water 300-1200 Alkali metal caustic 28. The process of claim 27 wherein the carbonate of an alkaline earth metal comprises calcium carbonate.

29. The process of making a glue which comprises mixing spray dried soluble blood powder with from 3 to 10% by weight based on the blood powder of powdery calcium carbonate, heating the mixture at a moisture content of from 6-20% by weight and a temperature of above 170 F. and below the charring temperature of the blood until the blood content thereof becomes substantially insoluble in water while retaining substantial solubility in dilute aqueous alkali metal hydroxide at a temperature of less than 100 F., cooling the heated mixture to a temperature of below 170 F. for arresting the denaturing operation and incorporating the resulting denatured blood glue base in a mixture comprising:

flour 10-100 Water 300-1200 Alkali metal caustic 150 Alkali metal silicate 10-400 Lime 1-50 30. The process of making a glue which comprises mixing spray dried soluble blood powder with from 1 to 10% by weight based on the blood powder of a powder carbonate of an alkaline earth metal selected from the group consisting of calcium, magnesium, strontium, barium, heating the mixture at a temperature of above 170 F. and below the charring temperature of the blood, and a moisture content of from 2-.35% by weight until the blood content thereof becomes substantially insoluble in water while retaining substantial solubility in dilute aqueous alkali metal hydroxide at a temperature of less than 100 F., cooling the heated mixture to a temperature below 170 F. to arrest the denaturing operation, and incorporating the resulting denatured glue base in a formulation comprising:

Parts by weight Water 300-1200 Alkali metal caustic 1-50 Thermosetting phenol-aldehyde resin 10-1000 31. The process of claim 30 wherein the thermosetting phenol-aldehyde resin comprises a thermosetting phenol formaldehyde resin.

32. The process of claim 30 wherein the alkaline earth metal carbonate comprises calcium carbonate and the thermosetting phenol-aldehyde resin comprises a thermosetting phenol-formaldehyde resin.

33. The process of making a glue base which comprises mixing dry soluble blood particles with solid filler in particle form to form a mixture, insuring that the moisture content of the mixture is from 2 to 35% by weight based on the weight of the mixture, denaturing the blood in the mixture by heating the mixture above 170 F. until the blood content thereof is substantially insoluble in water, while retaining substantial solubility in dilute aqueous alkali metal hydroxide at a temperature of less than F., and cooling the heated mixture to a temperature below 170 F. for arresting the denaturing operation, said filler being employed in an amount sufficient to prevent substantial caking of the blood particles during the denaturing operation.

34. The process of making a glue base, comprising: mixing powdered soluble blood with solid filler in particle form; denaturing the blood in the mixture by heating the mixture between 170 F. and 350 F. in the presence of moisture at a ratio of mixture to moisture between 100:2 and 100:35; and thereafter cooling the mixture to below F. to arrest denaturation of the blood, said filler being employed in an amount sufiicient to prevent substantial caking of the blood particles during the denaturing operation.

35. The process of making a glue which comprises mixing soluble blood powder with from 0.5 to 10% by weight based on the blood powder of a solid filler in particle form, insuring that the moisture content of the mixture is from 2 to 35% by weight based on the weight of the mixture, heating the mixture to a temperature above F. until the blood content thereof is substantially insoluble in water while retaining substantial solubility in dilute aqueous alkali metal hydroxide at a temperature less than 100 F., cooling the heated mixture to a temperature below 120 F. for arresting the denaturing operation, and forming a glue mixture comprising the resulting denatured blood glue base, alkali metal caustic,

and water in the following proportions:

Parts by weight Blood 100 Filler An amount sufiicient to prevent substantial caking of the blood particles during the denaturing operation. Water 300-1200 Alkali metal caustic"--- l-50 37. The process according to claim 35 in which there is also included a thermosetting phenol-aldehyde resin. 38. The process according to claim 36 in which there is also included a thermosetting phenol-aldehyde resin.

References Cited in the file of this patent UNITED STATES PATENTS 1,976,436 Cone Oct. 9, 1934 2,292,624 Fawthrop Aug. 11, 1942 2,400,541 Cone May 21, 1946 2,620,280 Pencil et a1. Dec. 2, 1952

Claims

7. THE PROCESS OF MAKING A GLUE WHICH COMPRISES MIXING SPRAY DRIED SOLUBLE BLOOD PARTICLES WITH FROM 10 TO 100% BY WEIGHT OF SOLID FILLER IN PARTICLE FORM, INSURING THAT THE MOISTURE CONTENT OF THE RESULTING MIXTURE IS FROM 2 TO 35% BY WEIGHT, DENATURING THE BLOOD IN THE MIXTURE BY HEATING THE MIXTURE ABOVE 170*F. UNTIL THE BLOOD CONTENT THEREOF IS SUBSTANTIALLY INSOLUBLE IN WATER BUT RETAINS SUBSTANTIAL SOLUBILITY IN DILUTE AQUEOUS ALKALI METAL HYDROXIDE AT A TEMPERATURE OF LESS THAN 100*F., COOLING THE HEATED MIXTURE TO A TEMPERATURE