US2042917A - High concentration agar agar gel and combinations thereof - Google Patents

Description

- June 2, 1936. H VQN BRANDT I v 2,042,917

,. HIGH CONCENTRATIO R-AGAR GEL A D Patented 2, 1936 I UNITED STATES PATENT OFFICE HIGH CONCENTRATION AGAR AGAR GEL AND COMBINATIONS THEREOF Henry von Brandt, New York, N. Y. Application July 22, 1932, Serial No. 624,119 13 Claims. (Cl. 1847) This invention concerns a high concentration time after the imprint has been taken so th t homogeneous agar agar gel as a base for an imtrue casts may be made therefrom. prin material,and a method of making the Furthermore provisions have been made that earne -more particularly a material serving to the imprint may be preserved, and may be reobtain a negative imprint of the shape of a plastic duced at a later date to the exact size which it body, be it a sculpture, an art object, or a comhad at the time the imprint was taken, a simple mercial article, a fossil, or a live or dead organic process being required thus to Iii-condition th body. imprint.

This material finds a prominent use in the Provisions have also been made whereby it is arts and in the medical sciences, where a true possible to preserve the exact dimensions, shape in replica of the human body or any part thereof, and detail of a fresh imprint for larger periods like the ear or foot, is to be made. Thus for of time without whole or partial losses due to instance, the dentist may use the material of shrinkage, bacterial growth, or mold; this is acmy invention, where he desires to obtain an imcomplished by one single, lasting treatment.

print of the oral cavity, and in the following Another object of this invention has reference 15 exemplary descriptionIhave specific reference to to hygiene. Throughout the whole manufacan adaptation of my invention for such purposes, turing process this imprint material or any part although it is understood, that the material as thereof does not require th t h of human described as well as more or less concentrated may hands. The product is sterile, and until the very 0 serve in ramifled uses. time of actual use I preserve the material in its 20 The grade of concentration as well as the original sterile condition. grade of consistency depend largely upon the A further object of this invention is to create nature of the object of which an imprint is to an imprint material oi whiteor very lightbe taken. For instance, if a true replica of the color, which may be colored to any desired shade.

dental cavities of a jaw are desired-which case It is a very important object of this invention, 25 the dental tray filled with the imprint material and one which largely influences the choice of may have to be turned upside-down in order to the ingredients, that the material, after an imbe applied-the imprint material should be more print has been taken, may be exposed to any concentrated and denser than for taking a deli atmosphere without putrefaction or molding.

3 cate imprint, of hair and the like, for instance. It is also an object of this invention to allow One object of this invention is to prepare an close control of the setting speed and temperaimprint material, which sets quickly while the hir i p nt s being taken, said imprint material It is further understood that a material of showing however Suflicient r s e y after the this kind must comprise a binder which holds it t 8 that it y be removed from the together, so that it does not readily break apart;

or in l. r in n iaw. w h shows n rat the same time the material should not be cuttings as in dental cavities, the resilient parts mucilaginous to the extent of adhering to the 0f the mater a being temporarily Stretched articles of which an imprint is to be taken; I

ing removal, While slipping aw y from Su have reached the object of obviating the coverundercuttings. ing of the article of which an imprint is to be It is however understood that the material taken with a coat of material which prevents admust resume exactly the same shape it had hesion of the imprint material to said article. On before, after having been withdrawn over th the other hand the material is to show the greatest protruding parts and must then retain its shape DOSSIble Coheslonand size. In other words, it must be truly elastic In ordertto otftam these vanous and and resilient and should not remain distorted. Others" winch be furuller understood i Another object of this invention is to prepare the folowmg' I have not on y brought about an imprint material in such a manner that it provements as to the ingredients used in my material, but I have also developed special and eco may be preserved mdefinitely' and so that only nomical processes of preparing the material, and 50 a short Process is required to place It f the binder used therein a method of preserving the dition take an imprint Whenever deslredimprint material and of conditioning it for use.

A further object of this invention is to provide The binder used in preparin'g t material is an imprin m t ri whi h p rv its xact of utmost importance. Gelatinous jellies, the shape and dimensions for a reasonable length of consistency of which should be as high as possible,

are desirable, and I have found that class of such material, which broadly falls under the term of agar agar, the most suitablebinder, provided a highly concentrated homogeneous aqueous mixture thereof can be prepared, which does not form lumps.

In the prior art commercial agar agarcould not be liquefied in aqueous solution without forming lumps at a higher concentration than at an approximate agar-water ratio of 1:20.

The major object of my invention is to condition commercial agar agar in such a way that it forms a homogeneous, cohesive mixture with water at a considerably higher concentration than that mentioned above or known heretofore.

This is attained by freezing the commercial agar agar after it has been mixed with the water, or otherwise changing or destroying the cell structure thereof and releasing the readily soluble gelosine. In this manner I have obtained a homogeneous binder, which contains agar agar and water in a ratio of up to 1:6.

This novel agar solution provides a basis for many other compounds which require ahigh concentration of agar agar.

Such a high concentration may also be obtained by exposing the mixture to ultra-violet rays, which destroys the cellular structure of agar agar, releasing the gelosin.

As a. body for a molding compound of this kind organic materials and argillaceous earth have been used most commonly heretofore. I have found the predominant use of such materials for the purpose of giving body to an imprint material to be incompatible with the objects which were mentioned above; they do not furnish a lasting material, allowing putrefaction, contraction and molding; they crack when dried: most of them cannot be restored to their original shape; and they will,--particularly argillaceous earth, bentonites, and fuller's earth,absorb and retain air, to an extent where the negative casts made from such a material, are of an inferior quality.

The object of providing a body substance which is not subject to such short-comings has been attained by using as a major part of the body a substantially insoluble virgin rock which in itself provides for a more compact structure; still, a minor part of the body may be made up of a filler such as clays, diatomaceous-earth, fossil earth, argillaceous earth, and the like so that a material of denser structure is obtained. But the proportionate contents of the organic material or of such materials that are partly organic, are in all instances restricted to a minor proportion of the ingredients of the body, so that their disadvantages do not prevail.

The following exemplary formula may be used for explaining a simple and economic way in which this imprint material may be prepared:

Binder Parts Powdered dry agar 24 Distilled water U. S. P. glycerine 18 Body Powdered dry soapstone (rock) 34 Powdered dry zinc oxide 17 Powdered dry silica (rock) 32 Pulverized dry clays 2O 15 parts E. Ball clay 5 parts molding clay All ingredients of body and binder are computed by weight".

The zinc oxide, commercial or natural (zincite) serves as a cohesive agent as well as for the purpose of closing the pores of the finished material. As coloring agent Fe-iOa was used. The choice of coloring matter is of course arbitrary.

There are several ways to prepare this imprint material, but one of them I consider highly suitable, hygienic and economical:

(1) The liquid ingredients (water, glycerine) should be mixed at room temperature;

(2) All dry and pulverized ingredients such as commercial agar agar, stone, clays, zinc oxide (if 'desired, also asbestos fiber) should be weighed sure of live steam.

pressure rises above afore-mentioned limits, the

and mixed thoroughly with each other;

(3) Under constant but slow stirring the thoroughly mixed dry ingredients are added to the liquid (water-glycerine-solution), until a homogeneous batter has formed. Special care should be taken that no air is introduced into this batter (while and after mixing) that will happen if the stirring device rotates too fast.

(4) This homogeneous batter should be frozen in any one of the rapid-acting commercial freezers (using crushed dry-ice combined with ether, or the like). The freezing should continue even after all of the batter seems to be frozen stiff in order to assure the mutilation or destruction of substantially all agar agar cells.

(5) The frozen batter is melted and under constant slow stirring gradually heated up to the point where the agar agar mixture will being to liquefy,and there the heating should be discontinued. (This point varies with the kinds of agar employed, but will be in the neighborhood of from 40 to 70 centigrades) This warm batter is filled into containers, preferably of the design referred to hereinafter. After introducing the batter in these containers, the latter may be sealed permanently as the further steps of the process do not require direct handling of the material. (Under certain circumstances the frozen and re-melted batter may be introduced into the containers without previous heating, although care must be taken not to bring free air into the containers as this may have a detrimental eil'ect upon the contents therein).

(6) The containers with the material are then placed into an autoclave. This name is commonly applied to a machine much used in industrial plants for the purpose of subjecting materials to heat and pressure. Here the material is subjected for 60 minutes to a heat of 250 Fahrenheit (121 centrigrade) and to not more than 15 lbs. pres- (If the heat and the steam characteristic quality of re-jellification of the agar agar will gradually decrease until, at a certain temperature or pressure (20 lbs.) the agar agar will cease to gelatinize). During this heating process certain important changes will 6 take place in the material: (a) the agar agar will liquefy and combine with the water-glycerine mixture, forming later,-when cooled-,the desired highly concentrated agar-jelly; (b) the liquid agar solution will be evenly distributed throughout the whole batter inside the container, forming a fine network of agar-channels between the multi-shaped solid particles of the mixture, and I obtain a substantially homogeneous mass,- the imprint material; (0) incidentally allbacteria and spores, which might havebeen' introduced into the mixture, will be destroyed-leaving the material absolutely sterile until the container is opened for the purpose of using the contents for making an imprint.

Another way to manufacture terial would be the following:-

The powdered dry agar agar is mixed thoroughly with the water until a stifi batter is formed in which all agar-particles have come into direct contact with the liquid. Then this batter is frozen as quickly as possible in order to prevent loss of water by evaporation. The freezing process should be continued until the greenish-gray color of the agar-agar batter temporarily turns white.

Precaution should be taken that the freezing fluid does not come into direct contact with the batter as this will prevent in most cases re-jellification, and moreover, when ether contacts with the agar agar it confers upon the latter a nauseating odor and unpleasant taste.

The freezing process should be continued until the agar agar batter is thoroughly frozen and its color has changed temporarily to white. The frozen cake of agar is then removed from the freezer, placed into a heating vessel equipped with a slowly rotating stirring device, and covered with so much glycerine as the ultimate use of the material may warrant. This treatment serves twofold: First, while the frozen agar is melting the layer of glycerine prevents loss of water by evaporation; second, due to the slow melting of the frozen agar and the constant stirring, the glycerine will be thoroughly and finely distributed throughout the whole agar solution. Direct application of heat up to the boiling point will finally yield a highly concentrated homogeneous agar solution of the afore-mentioned ratio.

This novel agar solution furnishes a basis for many compounds which require a high concentration of agar agar.

From this stage I proceed as follows to obtain the imprint material:

The frozen agar agar, as it was covered with glycerine, is melted, heated under constant stirring, and likewise under constant stirring the dry and powdered ingredients are added until thoroughly mixed with the agar-water-glycerine mixture, forming a stiff batter of high consistency, the heating temperature is raised up to centigrade, and kept at the boiling point for a short period.

The mixture is now filled into containers and sealed.

There is another method whereby the highly concentrated agar solution may be obtained:

Again the dry agar agar and water are thoroughly mixed and then irradiated with ultraviolet rays. Such ultraviolet treatment will destroy the cellular structure lower the absorption capacity of agar agar to considerable extent and by releasing the soluble gelosin lower the dissolving temperature of agar agar to about 40 centigrade, permitting thereby much higher concentration than heretofore has been possible. Due to the fact that certain agar agars are less re sistant to ultra-violet rays than others, the irradiation period should,-general1y,-not exceed 30 minutes. Excessive irradiation may result in partial or complete loss of the agar agars characteristic quality of being liquefied and solidified repeatedly, without detrimental influences. After treatment of the agar agar with ultra-violet rays an imprint material is prepared exactly as described in a connection with the previously described processes after freezing and thawing.

In order to increase the cohesion in such concentrated agar agar solutions commercial or the imprint manatural zinc oxide (zincite) (up to 15% of the body-forming ingredients) may be added to and incorporated in the mixture in finest distribution.

To increase elasticity and likewise to absorb surplus water, non-frozen powdered dry agar agar may be added additionally in small quantities (up to 2%). The tiny cells of the agar agar possess high absorption power (about 20 times their dry-weight) and besides are valuable for the reconstruction of the dried-out and shrunk materials to their former original dimensions and shape.

In accordance with the intended use of the material, certain modifications of the basic formula may be brought about, which may be guided by the following considerations:

The necessary concentration of agar agar may be reduced by substituting substances of. more tenacious and mucilaginous character such as gelatin (glue of bones), Mouss de Chine, Layor Caranga, algae of the rhodo hyceae-specie, or isinglass and the like, resulting in an imprint material of high viscosity but slower setting speed.

An increase of the glycerine oontents,with or without a proportionate decrease in water,- will give a fatty, slow-drying material, which, when air dried possesses leather-like appearance of rather tough and tenacious character-but the material will also mold more readily.

Increasing the silica-rock and decreasing the clay contents, will result in a more porous and faster drying material, but it is also apt to crack while a cast dries.

Replacing part or the whole of the natural rock ingredients in the mixture by commercially improved silica such as calcined diatomaceous silica or calcined fossil silica will result in a material of extremely light weight as may be desired for taking delicate imprints of such objects as hair.

A suitable formula is:

Binder Parts Dry powdered agar agar 20. Distilled water Glycerine 10 Body Silica ash 30 Powdered S102 R Zinc oxide 20 South Carolina clay 10 Generally, the calcined silica may be added in a quantity sufficient to impose upon the imprint material a characteristic compactness, lightness and yieldability, lightness in color too, unless 011'- set by coloring ingredients. In the foregoing the SiOz and clay may also be replaced by calcined silica also termed silica ash.

For purposes of this invention calcined silica should therefore be classified as a rock".

An introduction of asbestos fiber into the material will provide structure and tensile strength in the compound as a whole, but not more than 3% of the entire weight of ingredients in the imprint material should be added. Long fibers have a tendency to coil up" in the mixture forming annoying lumps, and likewise may impair the detail of the imprint. In order to increase the tensile strength it is. advisable to use raw,

crude asbestos fiber in preference to commercially improved fiber.

If material of less consistency is desired, the agar water proportion may be stretched, although the glycerine should be increased in proportion;

due to the'lessenedv amount of the agar binder in such a material another cohesion-increasing agent should be introduced in the material to make up for the loss in binding power.

Exceedingly fine-grained clays produce sharper imprints, but may lose in detail if immersed in cold water and may also color the saliva-if used for dental purposes.

Darker clays are more fatty, than light-colored ones; the former will ordinarily retain water and moisture longenthan the latter, but they dry slower and invite bacterial growth.

Bentonite clays absorb about 12 times their weight in water and increase in volume considerably while doing so, but upon drying they shrink extremely and crack the cast due to their ab- "normal shrinkage; besides, bentonites have a tendency to absorb and retain air, which may give the material large voids and a sponge-like appearance, which is very annoying if detail is wanted. a v

The term agar agar is used here to describe certain material which has certain physical characteristics. The derivates of agar agar, gelose for instance or any. other equivalent compound may be substituted wholly or partly for the agar agar.

Agar agar is very sensitive to acids, and in the choice of rocks, earth, and organic material, care should be taken that such material is not acidic.

In order to illustrate modifications, for in-- .stance for the purpose of introducing a higher silica content, I also give the following exemplary formula:

Binder Parts Powdered dry agar 23 Distilled water .1. 140 U. S. P. glycezine 1o Powdered 810i". 60 Powdered soapstone 24 Dry South Carolina clay; 22 -.z1'n nxidn I 16 I may go to the polnt of eliminating argillaceous earth and clays altogether; in which instance the followin'g exemplary formula may be adhered to in preparing my material as described Proceeding .in accordance with the second manufacturing niethod described above, the material is substantially finished, when it is placed into a container and sealed therein; any type of a closure. a can for instance, which can be sealed or closed air tight, is suitable.

, But in the first method referred to, the material is subjected to-further treatments after hav- ,ing been sealed in the container, and, since these comprise heat and pressure treatments in which the material changes in volume, and since it is not advisableto allow the amount of air necessary for a cushion inthecontainer, the .contair 1 er should be collapsible and readily allow propagation of pressure and heat'therethrough and throughout the contents. Therefore I prefer the use of a flattened container, made of thin-sheet metal or other 'ylel'dable material.

Such a container is illustratedin the accompanying drawing, in which:

Fig. 1 shows a perspective view of the closed container;

Fig. 2 shows a. longitudinal section thereof. Fig. 3 is a cross-section.

In the drawing, the collapsible tube His the flat body of the container; the ends l2 are folded over, and sealed and the container is filled with the material.

These metal containers are filled with the imprint ,material,not to the amount they could receive when shaped cylindrically, but to their capacity in the fiat condition shown,closed and sealed permanently. Turning the ends of the collapsible tube over fiat, will also allow for expansion during heat treatments. In this state, the metal containers and the material therein enclosed are subjected to the heat and pressure specified above.

The material, in a sealed container of the type shown, may be kept indefinitely. When to be used, its temperature is raised to about 60 centigrade in boiling water, whereupon one end of the container is clipped off and the material squeezed out of the container and then used to take the imprint. Itwill set in one or two minutes (according to its consistency and ingredients) and their the imprint may be withand then, in the period of days according to climatic conditions willshrink as it loses moisture. A shrunken, and dried out, imprint may be reproduced to true imprint size at any time by being soaked in plain water or in water with a trace of glycerine. This soaking should extend from a few minutes up to about 24 hours,-depending upon the grade of desiccation of the cast.

Freshly made imprints may be preserved for days and weeks in their exact shapeand size,

- without shrinkage, by keeping them in an airtight container, such as a glass jar with fitted-in stopper. A few drops of distilled water keeps the air moist inside of this container, and a drop of phenol, formaldehyde (formalin) or the like should be added to prevent bacterial growth.

Although I have shown and described one form of embodiment of my invention in detail, yet I do not wish to be limited thereby, except as the state of the art and the appended claims may require, for it is obvious that various modifications and changes may be made in the form t of embodimentof my invention, without departing from the spirit and scope thereof.

What I claim is:--

1. An imprint material comprising a highly concentrated homogeneous gelatinous binder, a

. body of powdered material and a mixture of hard and soft virgin rock forming the major part of said body material.

2. In an imprint material a homogeneous gelatinous binder comprising agar agar and water, at a ratio exceeding 1 to 7.

3. The method of preparing a homogeneous binder of an imprint material containing a high concentration of agar agar in water, comprising mixing agar agar into water, irradiating said mixture with ultra-violet rays, and heating it until it forms av gel.

4. The method of preparing an imprint material with an agar agar binder and a mineral body, comprising rapidly freezing an agar agarwater-glycerine batter, and boiling said solution with a mineral body in powdered form.

5. An agar agar solution characterized by a high concentration of agar agar and water, said solution being a homogeneous gel containing agar agar and water of substantially the ratio 1 part agar agar to 6 parts of water and'obtained by heating a non-gelatinous mixture of agar agar and water, after the cellular structure of the agar agar in said mixture has been broken up so that the gelosin in the cells is set free.

6. A highly concentrated agar agar solution obtained by rapidly freezing a substantially nongelatinous mixture oi agar agar and water, and later heating said mixture to the point where the agar agar dissolves.

7. An agar agar solution, characterized by a concentration of agar agar in water in excess of a proportion of 1:7, prepared by rapidly freezing a substantially non-gelatinous agar agar-water mixture, and then heating said mixture to the point where the agar agar dissolves.

8. The method of preparing an imprint material, comprising mixing a batter of agar agar and cold water in high concentration. irradiating said mixture with ultra-violet rays for a predetermined period, heating the mixture until it dissolves, and adding a powdered body material thereto.

9. A substantially non-shrinking imprint material comprising a concentrated agar agar water gel 01' the type described in claim 5 and powdered rock.

10. In an imprint material a binder comprisinga viscous homogeneous mixture containing agar agar and water substantially in the ratio 01' 1 part agar agar to approximately 6 parts by weight of water.

11. The method of preparing a homogeneous binder for an imprint material containing a highly concentrated emulsion of agar agar in water, comprising mixing agar agar and cold water, rapidly freezing the mixture, and heating said mixture to the point where the agar agar dissolves.

12. The method of terial, comprising the preparation of a cold mixture of commercial agar agar, water, and the required mineral substances, freezing said mix-- ture, melting said frozen mixture and heating it until a highly concentrated paste is obtained.

13. A highly concentrated agar agar solution prepared from a frozen non-gelatinous substan tially 1:6 mixture 01' agar agar and water.

HENRY VON BRANDT.

preparing an imprint ma-

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