US3001885A - Manufacture of artificial icicles - Google Patents

Description

United States Patent This invention relates to a viscous liquid composition especially useful in the formation of decorative imitation icicles and to a process for the preparation of these imitation icicles. This application is a continuation-inpart of application Ser. No. 441,647, filed July 6, 1954,

now abandoned.

In keeping with the Christmas season, or at least the wintry associations of that season, it is customary to decorate Christmas trees with simulations of the natural phenomena which occur during that season. Such phenomena, of course, include snow and ice. The problems incident to a realistic reproduction of snow have. already been solved so that it is possible to create a layer of snow indoors which captures much of the character of the actual. But to date the same cannot be said with respect to ice in the form of icicles. This is so because it is quite diflicult to provide something with the prop erties common to all ice formations, that is, a basic solid material which is colorless, translucent, brilliant, perhaps here and there having an air bubble inclusion, and at the same time provide something which will yield ice formations of variegated size and shape. Both these characteristics should be present in order that the illusion of realism be not destroyed.

Heretofore attempts to meet the problems thus presented have often involved the use of glass and plastic which have been the only material comparable in appear ance to ice, but the use of glass or plastic fails to meet the second desideraturn alluded to above. Obviously the glass or plastic must be preformed and, in order for its use to be economically feasible, it must be cast. This necessarily means that there are severe limitations as to the number of sizes and shapes which can be made avail able, since obviously these are ready-made, factory manufactured articles, With such limitations the possibility of achieving the objective of realism disappears.

It is an object of this invention to provide a new material for use in producing icicles in the home which in all of the respects already indicated will be eminently suitable.

Another object of this invention is to provide a viscous solution of certain cellulose esters which are suited for the producing of said artificial icicles.

It is a further object of the present invention to provide /2 oz. The flowing liquid gels spontaneously inmid-air after it has changed to the pointed cone-shaped form of about 4 to 7 inches in length; the solution neither drips nor flows too slowly to form neither a thread-like shape nor a lump. The solution develops a skin on the surface quickly which is dry to the touch yet is permeable to the solvent vapors to permit a gradual drying and hardening of the icicles. The solution dries clear without a pattern, without blushing, permanent haze, grain or turbidity. There is a minimum of volumetric shrinkage during the drying process. Since it is to be used as a decoration on Christmas trees, the icicles at anytime, when dry or while still containing solvent, do not sustain a flame when ignited. The solution does not spread an objectionable odor, is not corrosive, poisonous or hazardous to handle;

It has been found after considerable experimentation that the objects of the present invention could only be accomplished with a viscous cellulose ester solution meetmg certam minimum characteristics. Generally speak ing, the viscous solution of the present invention must comprise:

- least one of the cellulose esters more particularly defined a process for making artificial icicles on Christmas trees supporting, free-hanging, non-sticky mass at room tem perature. It will be observed that the artificial product, just as in the case of a natural icicle, is held to its support without the use of hooks or other hanging device, being held to its support because it-has itself formed about the support.

The icicle solution of this inventlon flows freely at room temperature and normal atmospheric conditions to form a pointed cone of an average length of about 3 to 7 inches, preferably 4 inches, within 1 to 5 seconds when released from a closed container in a quantity of about below.

(d) The solution in addition to other properties, must be sufficiently viscous to promote gelling in the time alloted for the formation of the icicle, and, at the same time, it must be suificiently fiuent to permit a free flowing out, so that the icicle can grow to the desired length and end in a point.

The solvent blends used in accordance with the presen invention are non-inflammable and must be composed of at least two solvents even if one solvent alone would be sufiicient to dissolve the cellulose ester. One or both solvents can be co-solvents or secondary solvents, though a blend is preferred containing at least one good primary solvent for the particular cellulose ester. Additional sol vents in very small quantities can be co-solvents or even diluents.

One solvent of the solvent system must evaporate at a faster rate than any other and the whole solvent system must be of the fast evaporation type to cause the spontaneous gelation of the solution at room temperature and normal atmospheric conditions.

The gelation phenomenon noted in connection with the present composition is believed to be due to the change in the viscosity of the solution resulting from the change in the solvent system on exposure to the atmosphere at normal temperatures and pressures. Every cellulose ester of a given acid substitution and molecular weight (average chain length as expressed by intrinsic viscosity) exhibits a definite viscosity if dissolved at a 7 given concentration in a given solvent which is characteristic for said solvent. The same cellulose ester when dissolved in another solvent, all conditions equal (concentration, temperature, etc.), might exhibit an entirely difierent viscosity. The variations of one and the same cellulose ester in various difierent solvents are remarlo able-from 50% to 10,000% or more, e.g. 9% LL-l Cellulose Acetate as described at page 4 in Hercules I Cellulose Acetate, Properties and Uses, 1954 edition, published by Hercules Powder Company, having 55.0- 56.0 combined acetic acid, dissolved in acetone has a viscosity of 46 cps, compared with 62 cps. in methylacetate and 203 cps. in methyl ethyl ketone. If 8 parts of methyl ethyl ketone are mixed with 2 parts of methanol the viscosity of said solution goes down to 70 cps. and in the ratio of'9 methyl ethyl ketonezl methanol to Patented Sept. 26, 196-1 62 cps; always using the same LL-l cellulose acetate as above in 9% concentration. A cellulose acetate-butyrate having a combined butyryl content of 26% and combined acetyl content of 20.5% and a combined cellulose residue of 53.5%, with 2.5% of it free hydroxyl, in a 15% solution in acetone has a viscosity of 272 cps. (Brookfield) at 25 C., but in ethylene chloride the viscosity is 71,000 cps.

From such examples it is evident that a change in the ratio of the components of a solvent blend changes the solvent characteristics of the blend. Not only the solvent capability is likely to change but also a spontaneous and radical change in viscosity can take place. The changing solvent blend at a certain phase might still be a powerful solvent, yet cause a greatly increased viscosity.

In accordance with the present invention the icicle solutions are exposed to air from all sides and change their solvent composition continuously and also become more concentrated. With high vapor pressure solvents the changes in viscosity take place very rapidly within a matter of seconds. For example, methyl-, ethylor isopropylalcohol are used as co-solvents in the present composition. In a ratio of about 10% to 25% they lower the viscosity of most cellulose esters in a methylene chloride solution. In ratios of less than 10% and more than 25% they increase the viscosity even beyond the viscosity of a cellulose ester solution in methylene chloride alone. Thus the change is very pronounced. The methylene chloride evaporates faster than the alcohols especially when the right cellulose esters are dissolved.

In a cellulose ester solution which is at the saturation concentration or close to saturation but still flowing, a change in viscosity may cause gelation. However, not all cellulose ester solutions which gel in accordance with this theory can be used for the production of artificial icicles. In order to be usable for this purpose they must meet a number of close specifications. Moreover, plasticizers and modifiers also influence the viscosity and solubility of the blended solute in a solvent or solvent blend and, therefore, must be carefully chosen in order to meet the specifications.

With all these limitations not all cellulose esters, plasticizers, modifiers and solvents can be used even if they behaved qualitatively" in a similar manner. Thus, for example, if two cellulose acetates x and y are both soluble in the same solvent but their viscosity figures or saturation rates are dilferent, such cellulose acetates might not be interchangeable for my purpose. The same is true for modifiers, solvents, etc. A plasticizer might be compatible with said ester x" in a certain ratio which is necessary for my purpose but not compatible in the same ratio with ester y. For example, cellulose acetate PM 3 such as described at page 4 in Hercules Cellulose Acetate, Properties and Uses, 1954 edition, published by Hercules Powder Company. in a formulation:

TABLE I Parts by weight Cellulose acetate PM-3 20 Santicizer M-17 (methyl phthalyl ethyl glycolate) Methylene chloridezethanol Santicizer M-17, as described in Handbook of Material Trade Names, by Zimmermann and Lavine, 1953 edition, page 500, as methyl phthalyl ethyl glycolate C H (COO) CH CH COC H is completely compatible with PM-3 in this ratio and almost in any other ratio. However Aroclor 1254 (chlorinated hiphenyl), which is useful for the present purposes, is not compatible with PM-3 in his ratio and, therefore, not interchangeable. The formula in Table 1 above is too viscous to flow freely and is not useful for the present purpose. The use of this results in a lump and not a pointed icicle. The same formula without the Santicizer M-17 gives a rippled pattern and slight turbidity with a great deal of shrinkage. This also is not usable for the present purpose. However, as will be noted below, PM-3 may be used in the present invention when blended with other cellulose esters.

In accordance with the present invention the drying icile should shrink in volume as little as possible. Thus there is dissolved only as much solute in the solvent as is consistent with free fiow and mutual compatibility. This cannot be effected with just any plasticizer or modi fier that is compatible with the respective ester but it must be selected judiciously. The total solute is preferably 4 0% to 50% by weight of the solution though, with certain bulky cellulose esters, icicles" on the somewhat lean side can be made with a little less solute. Thus the solids content i.e. the non-evaporable part of the solution, may vary from 30% to 50% by weight of the total solution.

The solvent system of this invention constitutes the largest portion of the solutions. It must be non-inflammable and must consist of at least two components with a high but different evaporation rate. The evaporation rates of solvents and solvent systems which are useful for the present purposes are as expressed by vapor pressure roughly between the limits of 30 to 350 mm. mercury at 20 C. Or, if N-butylacetate has an arbitrary evaporation rate of 100, the solvents useful for this invention should have an evaporation rate from 230 to 1200.

Some typical evaporation rates and vapor pressure of solvents that can be used in the present invention can be seen in Table II below:

The solvents, co-solvents or diluents which can be used in accordance with the present invention are: methylene chloride, methanol, ethanol, isopropanol, carbontctrachloride, ethylene dichloride and cyclohexanc. Only insignificant quantities of diluents may be added. The preferred ratio of methylene chloride: secondary solvent is 9:1, though ratios from 9.3:0.7 to 8.5115 can be used. A ratio of 8:2 is workable as far as icicle formation is concerned but not desirable because of flammability.

There are a number of cellulose esters which will dissolve in the solvent blonds mentioned herein and yet will not meet all the specifications of this invention and, therefore, are not usable for the present purposes. The useful cellulose esters are those which are highly soluble in the proper solvent blends as expressed by high concentration at the saturation point and at the same time result in a solution of relatively low viscositythe viscosity being such that a quantity of about /2 oz. of solution flows freely within 1 to 5 seconds to form a pointed cone of an average length of 3 to 7 inches after which time the cone gels. Thus, two factors are important for the choice of the right cellulose esters: solubility and viscosity. Solubility is a function of acid substitution, type of solvent and concentration. Sometimes, e.g., certain cellulose esters are less soluble at a lower concentration than at a higher .one. Viscosity depends on the type of ester which, in turn, is a function of acid substitution and chain length (mol. weight) and concentration. As solubility and viscosity also change with temperature, all specifications and information given herein are to be understood at room temperature of 20 C.-25 C.

Cellulose acetates which are useful for the present purposes have an acid substitution as expressed by combined easiest acetic acidof from 54.1% to 56% or an acetylc ontent from 39-40.35%. The viscosity ranges from 1 to .8 seconds as determined by the falling time of a i steel ball through in. of a 20% solution by weight of cellulose acetate dissolved in a solvent composed of 90:10 acetonezethanol (by weight) heldin a 1 in. diameter tube at 25? C. (ASTMD 871-48 Formula A).

Cellulose acetates with a higher combined acetic acid content, though being mostly used for solvent casting of films, etc., have even better solubility but, as such,- are not usable for the present purposes because all com mercial products in this range come in a viscosity grade not suitable for this invention. Also they have more sol-; vent retention.

However, it is admissible to blend different grades of cellulose acetates or cellulose acetate with the more compatible cellulose acetate-butyrates to obtain an intermediate viscosity grade. However, it is best that such blends of cellulose acetates be made of grades showing not more than fivefold variation in viscosity in order to avoid grain formation. It is also possible to blend small portions of cellulose acetates with combined acetic acid content of less than 54.1 or more than 56.0 with larger portions of the cellulose acetates with 54.1-56.0 combined acetic acid as long as the flow and gel characteristics necessary for the present purposes are obtained. How ever, the cellulose acetates with less than 54.1 or more than 56.0 combined acetic acid cannot be used alone, unblended that is, without usuable cellulose esters for the purpose of this invention.

' Of. the four commercial types of cellulose acetate butyrate which are presently available onthe American market each of them in several viscosity grades, I can use the following types (not viscosity grades) straight, unblended: cellulose acetate-butyrate EAM38l, having 37% combined butyryl, 13% combined acetyl, 50% com bined cellulose residue, the latter having 2% tree by droxyl; cellulose acetate-butyrate BAH-500 with 48% combined butyryl, 6% combined acetyl, 46% combined cellulose residue, containing 0.7% free hydroxyl.

5 Two other types of cellulose acetate-butyrate types, EAB-l71 and EAB-272, cannot be used straight but can be used blended especially with type EAB-381. Half Second butyrate .(cellulose. acetate-butyrate), most frequently used in the present examples, is a EAB-38l type (see Examples 7 and 8 below). The chemical composition of EAB-17l is 17% combined butyryl, 29.5% combined acetyl and 53.5% combined cellulose residue with 1.5% free hydroxyl. EAB272 has 26% combined butyryl, 20.5% combined acetyl, 53.5% combined cellulose residue with 2.5% freehydroxyl.

In accordancewith one aspect of this invention it 1s desirable to use abeuulsse ester solution which contains at least a minimum concentration of about 20% by weight and preferably in the range of 20 to 35% by weight. As noted above, the total solids content of the icicle solution may vary from 30 to 50% by weight of the total composition. The nonester solids dissolved in the icicle solution may vary from about 8% to about by weight of the total solution. The non-ester solids are added to help avoid shrinkage and impart flame resistance and other desirable properties such as clarity, transparency, reduced brittleness, etc. Qhlorrnated biphenyls such as the Arochlors and chlorinated paralfin are the most useful. Other useful additives are certain aryl sulfonamide formaldehyde resins, Santolite MHP (see Example 2 below), organic bromine, boron or phosphorous compounds.

The viscosity of the icicle solutions of the present invention as distinguished from the viscosity of the various cellulose esters used herein and expressed as described above, are diflicult to determine because of the fast jelling of the solution. However, it may be stated that the viscosity of the icicle solutions will vary within the limits of 85 to 170 seconds and preferably in the range of 85 to methanol.

. 6 130 seconds. The optimum range appears to bebetweefi 100 to 130 seconds. This viscosity is expressed as the falling time for a 91 in.- steel ball through 10 in. of solutiori;I contained in al .in. wide tube at 25 .C. and 760 mm.. 'pg- The following examples are further illustrative of the present'invention and it will be understood that the invention is not limited thereto. 1

Example 1 v 36 p.p.w. (parts by weight) cellulose butyrate acetate (V2 sec.) and '11 p.p2w.'"'chlorinated paraflin (40% "chlm rine) are dissolved in 53 p.p.w. methylenechloride. To 100% parts pay. qtthis solution 18 parts p.w. of carbon! tetrachloride are gradually added under slow agitation.

Remarks.-This water clear, non-inflannnable viscous liquid is free flowing; v vhen aquantity of about V2 to A of one ounce of this liquidfis squeezed at room temperature onto. the end of a tree branch through the opening of a collapsible metal tube, said opening having a diameter of A inch, this liquid will flow downwards in a cone-like shape until it has'reached a length of about 3 to 4 inches. Sudden gelation and hardening of the surface at room temperature will stop any further movement or change of shape. The icicle-like product will become thoroughly rigid within a short time. Itzis odorless and will not if exposed to the open flame of a match.

Example 2 22 p.p.w. of cellulose acetate 8 sec., 8.8 p.p.w. Aroclor 1254 (chlorinated biphenyl), 4.2 p.p.w. Santolite MHP (Arylsulfonamide formaldehyderesin) are dissolved in a blen d of 58.5 p.p.w. met hylenechloride and 6.5 p.p.w.

, -Remarks. Th:properties of the resulting liquid similar as described Example 1.

' "E ample-i 30 p.p.w.- cellulose butyrate acetate 1 sec., 10 p.piw. Aroclor 1254 (chlorinated biphenyl) are dissolved in ;a blend of 54 p.p.w. methylenechloride and 6 p.p.w. ethanol; Remarks .--The resulting solution has similar'properties as described in Example -1.' i Example 4. I

7 p.p.w. cellulose butyrate acetate 3 sec.,. 28 cellulose butyrate acetate /2 sec., 9 p.p.w. Aroclor 1254 (chlorinated biphenyl) are dissolved in a blend of 46 V p.p.w. methylenechloride, 4 p.p.w. ethylenedichloride, 5

p.p.w. methanol, 1 p.p.w. cyclohexane.

I Remarks-The resulting solution has similar properties as described in Example 1. I f "f Example 5 5 p.p.w. cellulose acetate 20 sec., 20 p.p.w. cellulose butyrate acetate 1 sec., 8 p.p.w. Aroclor 1254 (chlorinated biphenyl) are dissolved in a blend of 60.3 p.p.w. methylenechloride and 6.7 p.p.w. methylalcohol methanol.

Remarks.-The resulting solution has similar properties as described in Example 1.

Example 6 35 p.p.w. cellulose butyrate acetate /2 sec., 11 p.p.w. Aroclor 1254 (chlorinated biphenyl), 4 p.p.w. Santolite MHP (arylsulfonamide formaldehyde resin) are dissolved in a blend of 45 p.p.w. methylenechloride and 5 p.p.w. methanol.

The cellulose acetate in Examples 2 and 5 has about 39% acetyl which is equal to a combined acetic acid of 54.2%. The cellulose butyrate acetate in Examples 1, 3, 5 and 6 has 37% combined butyryl, 13% combined acetyl, 5 0% combined cellulose residue, the latter having 2% (free hydroxyl. The 3 second cellulose butyrate acetate in Example 4 is just inbetween a di and tri-ester or, more precisely, contains 26% combined butyryl, 20.5% corn- 7 bined acetyl, 53.5% combined. cellulose residue with 2.5% free hydroxyl.

Examples 7 and 8 Percent Percent by Wt. by-Wt.

Cellulose acetate butyrate 381-20 6. 6V 7. "Half second butyrato" (Cellulose acetatebutyrate) .c 25. 5 26. 5 Aroclor 1254 (chlorinated biphcnyl 10 i olvent 58. 0 56 The solvent in these examples consists of:-

86% by wt. of methylene chloride 4% by wt. of methanol 5% by weight of ethanol 3% by wt. of isopropanol 2% by wt. of n-propanol Example 9 Percent by wt. Cellulose acetate PM-3 (Hercules)..- 9 "Half second butyrate (cellulose acetate'butyrate)" 21 Aroclor 1254 (chlorinated biphenyl). -;;.--..-...-1O Methanol 6 Methylene chloride a 54 While the invention has been described with particular reference to specific embodiments, it is to be understood that it is not limited thereto, but is to be construed broadly and restricted solely by the scope of the appended claims.

I claim:

1. A viscous solution which is liquid and free flowing at normal room temperature in a closed container and which increases in viscosity rapidly and spontaneously to a point of gelation when released from said container and exposed to air at room temperature and normal at mospheric pressure consisting of a non-inflammable, high evaporation rate solvent system consisting of methylene chloride and a secondary solvent selected from the group consisting of methanol, ethanol, n-propanol, isopropanol, cyclohexane, carbontetrachloride, ethylene dichloride and mixtures thereof, and a cellulose ester componentdissolved therein, the ratio of methylene chloride to secondary solvent being in the range of from about 9.3:0.7 to 8:2, said methylene chloride and secondary solvent having a substantial difierence in vapor pressure, said solvent system having a vapor pressure in the range of about 30 mm. to 360 mm. of Hg. at 20 C., said cellulose ester component containing as a principal and essential con stituent a cellulose ester selected from the group consisting of cellulose acetate having an acetyl content of from 39 to 40.35% and a viscosity of from 1 to 8 seconds, cellulose acetate-butyrate having 6% combined acetyl and. 48% combined butyryl content and cellulose acetatebutyrate having 13% combined acetyl and 37% combined butyryl content, said solution having a total solids content of from about 30% to 50%.

2. A viscous solution according to claim 1 wherein said solution has a viscosity of from to 170 seconds.

3. A viscous solution according to claim 1 wherein the total cellulose ester component comprises at least 20% by weight of the solution.

4. A viscous solution according to claim 3 wherein the total cellulose ester component comprises from about 20% to 35% by weight of the total composition.

5. A viscous solution according to claim 1 wherein the ratio by Weight of methylene chloride to secondary solvent is about 9:1.

6. A viscous solution according to claim 1 wherein cellulose esters enumerated constitute from 50% to of said ester component. 7. A viscous solution according to claim 1 including a modifier selected from the class consisting of chlorinated biphenyl, chlorinated parafiins and arylsulfonamide formaldehyde resin;

8. A viscous solution according to claim 7 wherein said modifier is present in solution in the range of about 8% to 15% by weight of the total solution.

9. A process for making artificial icicles suspended directly from a support which comprises placing a small quantity of the composition of claim 1 on said support and allowing said composition to flow downwardly under the influence of gravity whereby an artificial icicle is formed. 1

References Cited in the file of this patent UNITED STATES PATENTS 2,003,655 Reid June 4, 1935 2,367,503 Hunter et al Ian. 16, 1945 2,492,978 Fordyce et al Jan. 3, 1950 2,669,521 Bierly Feb. 16, 1954 2,680,691 Olson et al June 8, 1954 2,739,070 Fordyce et al Mar. 20, 1956

Claims (1)

1. A VISCOUS SOLUTION WHICH IS LIQUID AND FREE FLOWING AT NORMAL ROOM TEMPERATURE IN A CLOSED CONTAINER AND WHICH INCREASES IN VISOCITY RAPIDLY AND SPONTANEOUSLY TO A POINT OF GELATION WHEN RELEASED FROM SAID CONTAINER AND EXPOSED TO AIR AT ROOM TEMPERATURE AND NORMAL ATMOSPHERIC PRESSURE CONSISTING OF NON-INFLAMMABLE, HIGH EVAPORATION RATE SOLVENT SYSTEM CONSISTING OF METHYLENE CHLORIDE AND A SECONDARY SOLVENT SELECTED FROM THE GROUP CONSISTING OF METHANOL, ETHANOL, N-PROPANOL, ISOPROPANOL, CYCLOHEXANE, CARBONTETRACHORIDE, ETHYLENE DICHLORIDE AND MIXTURES THEREOF, AND A CELLULOSE ESTER COMPONENT DISSOLVED THEREIN, THE RATIO OF METHYLENE CHLORIDE TO SECONDARY SOLVENT BEING IN THE RANGE OF FROM ABOUT 9.3:0.7 TO 8:2, SAID METHYLENE CHLORIDE AND SECONDARY SOLVENT HAVING A SUBSTANTIALLY DIFFERENCE IN VAPOR PRESSURE, SAID SOLVENT SYSTEM HAVING A VAPOR PRESSURE IN THE RANGE OF ABOUT 30 MM. TO 360 MM. OF HG. AT 20*C., SAID CELLULOSE ESTER COMPONENT CONTAINING AS A PRINCIPAL AND ESSENTIAL CONSTITUENT A CELLULOSE ESTER SELECTED FROM THE GROUP CONSISTING OF CELLULOSE ACETATE HAVING AN ACETYL CONTENT OF FROM 39 TO 40.35% AND A VISCOSITY OF FROM 1 TO 8 SECONDS, CELLULOSE ACETATE-BUTYRATE HGAVING 6% COMBINED ACETYL AND 48% COMBINED BUTYRYL CONTENT AND CELLULOSE ACETATEBUYTRATE HAVING 13% COMBINED ACETYL AND 37% COMBINED BUTYRYL CONTENT, SAID SOLUTION HAVING A TOTAL CONTENT OF FROM ABOUT 30% TO 50%.