US2999761A

US2999761A - Liquid laundry starch

Info

Publication number: US2999761A
Application number: US794523A
Authority: US
Inventors: James L Miller
Original assignee: Tate and Lyle Ingredients Americas LLC
Current assignee: Primary Products Ingredients Americas LLC
Priority date: 1959-02-20
Filing date: 1959-02-20
Publication date: 1961-09-12
Anticipated expiration: 1978-09-12

Description

2,999,761 LIQUID LAUNDRY STARCH James L. Miller, Decatur, 111., assignor to A. E. Staley Manufacturing Company, Decatur, 111., a corporation of Delaware No Drawing. Filed Feb. 20, 1959, Ser. No. 794,523 8 Claims. (Q1. 1t 6213) This invention relates, generally, to improvements and innovations in liquid laundry starch compositions which are stabilized and have prolonged shelf life, and which are characterized by their freedom from corrosive action on garments and fabrics in the presence of metal attachments such as metal zippers, buttons, hooks, and ornaments.

Liquid laundry starches have become increasingly popular, particularly for home laundry use, since starch in this form obviates the need for preparing a starch dispersion each time starch is needed. It is, of course, Well known that the ordinary starch dispersions prepared at home do not keep well and therefore it is the practice to prepare only enough for immediate needs and any extra amount is usually discarded. Not only is this practice wasteful of the starch, but in addition there is little uniformity in the starch dispersions prepared under home conditions.

By the designation liquid laundry starch as used herein and in the appended claims, it is intended to designate a commercial product of high uniformity which is stable under ordinary conditions encountered in merchandising, storage and transit so as to have a prolonged and good shelf life whereby it will be and remain in excellent condition when it reaches the housewife for use by her over a substantial period of time. An ordinary solution or dispersion of starch consisting only of starch and water will not meet these rigid conditions so as to constitute a liquid laundry starch within the above designation.

Numerous addition agents have from tirne to time been incorporated in liquid laundry starches with a view of making suitable products. In general, the prior art has suggested addition of various salts, particularly common salt or sodium chloride, to impart many of the desired properties. Major functions of these salts are to stabilize the paste or impart resistance to cold, so that the product will resist freezing or other undesired change during shipment and during storage in unheated Warehouses or storage rooms, and to prolong shelf life under normal store conditions.

The stabilizing of the liquid laundry starch products is desirable, not only from a standpoint of providing resistance to freezing and cold, but also in inhibiting and preventing separation of the ingredients in the product if it is exposed to low temperatures. The liquid laundry starch products of this type tend, under low temperature conditions, to lose their original homogeneous character with the result that some of the ingredients may settle out or form layers. Once this occurs, it may not be possible to re-constitute the product to its original condition, even upon vigorous shaking or mixing.

While the electrolyte salts previously used may impart adequate resistance to these undesirable changes or developments in a liquid laundry starch product, a troublesome effect has been traced to the incoiporation or presence of these strong electrolyte salts in liquid laundry starch compositions. Thus, it was discovered in connection with the making of the present invention that when clothes or garments having metallic zippers, ornaments, fasteners, etc., are starched with a liquid laundry starch containing a strong electrolyte salt such as ordinary salt, as a Winterizing or stabilizing agent, the fabrics often weakened, and were even completely eaten through.

Originally, the cause of the damage was obscure, but it was established that it was due to an electro-chemical corrosive action which occurred, particularly during the conditioning, when the damp clothes were rolled up and metallic fasteners or ornaments were in intimate contact with the damp salt-containing starch compositions. The action of the strong acids generated was accentuated when brought into contact with a hot iron, resulting in the formation of many holes and scorching in the fabrics.

According to United States Patent 2,796,354, the foregoing objectionable behavior is prevented by replacing the strong electrolyte stabilizing salts with a mixture of borax and sodium bicarbonate. These two salts, being salts of weak acids, cannot yield corrosive acids by electrolysis.

According to the present invention, a further substantial improvement in the stabilization and ironing properties of liquid laundry starches is obtained by using a mixture of borax and sodium tripolyphosphate as the stabilizing agent. Sodium bicarbonate catalyzes or enhances the darkening of starch when heated to pyrolyzing temperature. Sodium bicarbonate in a liquid laundry starch contributes to the undesirable yellowing of a starched and ironed fabric, particularly when the fabric is ironed at high temperature. This objectionable property of liquid laundry starches containing sodium bicarbonate is eliminated by the present invention.

Replacement of the sodium bicarbonate with additional borax, or elimination of the bicarbonate without replacement, solves the foregoing fabric yellowing problem but creates another problem. Borax has the well known property of altering the viscosity and stringiness of starch pastes to which it is added. Its presence in starch pastes also causes many of the pastes to set to a semi-rigid gelv after a moderate storage period atroom temperature. creasing starch and/or borax concentration. Borax is also a less eificient freeze-thaw stabilizer of starch pastes than the strong electrolyte salts such as sodium chloride. Consequently, when using borax as the principal or sole ifreeze-thaw stabilizer, one must compromise between its beneficial stabilizing action on one hand and its deleterious gelling elfect on the other. Heretofore, the net result of the compromise has been a sacrifice in stability. The freeze-thaw stability of such products can not be brought up to the sodium chloride level, for example, without leading to gelling when borax is the sole stabilizer or to serious yellowing of the starched and ironed fabric when a substantial part of the borax is replaced with sodium bicarbonate.

The new liquid laundry starch compositions conforming to the present invention have almost as much freezethaw stability as similar prior art compositions stabilized with sodium chloride, but they are free of the foregoing drawbacks. The new compositions lack the objectionable gelling characteristic of those stabilized with borax alone, they do not lead to yellowing of the starched and ironed fabric as do those stabilized with a mixture of borax and sodium bicarbonate, and they lack the fabric discoloration and weakening effect of the sodium chloride stabilized compositions, an effect produced when the starched and dampened fabric is allowed to remain in contact with a bimetallic fastener, such as a zipper, for a substantial length of time.

In addition to the borax and sodium tripolyphosphate, the new liquid laundry starch compositions may also contain relatively minor proportions of such additives as water softeners (e.g., sodium hexamethaphosphate), soaps, dyes, perfumes, ironing aids (e.g., sulfonated castor oil), preservatives (e.g., phenyl mercuric acetate), and optical whitening and brightening agents.

According to the present invention, the starch co'rm The gelling tendency increases with in-' ponent of the new compositions is stablized against freeze-thaw separation with about 1% to about 4% by weight, based on the finished liquid laundry starch composition, of a mixture of borax and sodium tripolyphosphate wherein the Weight ratio of the tripolyphosphate to combined weight of borax and phosphate ranges from about 0.1 to about 0.5. Preferably, however, the combined Weight percentage of the borax and sodium tripolyphosphate in the finished product lies within the range of 2% to 3% and the preferred weight ratio of sodium tripolyphosphate to combined weight of borax and phosphate lies within the range of 0.10 to 0.15.

The present invention is applicable to liquid laundry starch pastes made from starches generally. In regard to its vegetable orig n, the starch may come from the root, stem, or seed of a plant. Examples are com, potato, wheat, rice, tapioca, waxy maize, sorghum, sage, and waxy sorghum. The starch may be raw (i.e., native) or it may be modified by one or more of the different methods well known in the art. The modifying means include (1) the chemical type such as oxidation with hypochlorite mild hydrolysis with mineral acids, and low degree of derivatization -(e.g., reaction with ethylene oxide to form the beta hydroxyethyl ether of starch); (2) the physical type such as ball milling and Working or kneading in differential smooth rolls (cf. U.S. Patent 2,464,081), and in extruders, (cf. US. Patent 2,214,- 018); and (3) the combined chemical and physical type exemplified by dextrinization with or Without catalysts.

Although the raw starch pastes are quite satisfactory for laundry use and, ingeneral, are more eflicient fabric stiffening agents than the corresponding chemically modified starch pastes, the latter are preferred for commercial manufacture and distribution. The chief reason for this preference is that the raw starches, by comparison with the hypochlorite oxidized starches for example, form relatively thick aqueous pastes per unit concentration of dispersed starch. As measured by the volume of equal value diluted paste, i.e., a paste ready for use in the home laundry and having a standard index of fabric stiffening power, that can be made from a unit volume of concentrated paste with maximum commercially feasible viscosity, the chemically modified starches are generally superior to the corresponding raw starches.

The starch component of the new liquid compositions may also be derived from pregelatinized starch products, i.e., pastes of the foregoing starches dried and ground in such manner that the final products will redisperse in water to yield satisfactory reconstituted pastes.

Economic considerations favor the manufacture and distribution of the most concentrated paste consistent with stability and usable viscosity. There are two main considerations: (1) the cost of handling and transporting water, which is the principal and inert component of the finished product; and (2) the container cost per unit weight of starch. As mentioned earlier, it is in the area of such concentrated starch pastes that the present invention has particular utility. In accordance with the-present invent-ion, the starch concentration in the finished product may vary from about 5% to about 15% by weight.

, The preferred general method of preparing the new liquid laundry starch compositions is based on the pasting or gelatinizing of an aqueous slurry of u-ngelatinized starch granules with heat. First, the starch and water are mixed together below the starch pasting temperature and in the finished product ratio, making proper allowances for gain or loss of Water during the heating step. Next, the well agitated slurry is heated to about 190 F. to about 210 F. This may be done by injecting steam into the stirred slurry or by heating it indirectly with steam coils or a steam jacket. The stirring and heating at the elevated temperature are continued for several minutes, preferably not less than about thirty, to paste the starch thoroughly. If desired, all of the optional 4 additives except some of the commonly used perfumes and preservatives may be added to the starch slurry prior to the pasting step. The essential borax and sodium tripolyphosphate are withheld from the hot pasting stop because their presence makes the paste sufiiciently alkaline (pH 8 to 9) to lead to air oxidation of the starch at the elevated temperature and to associated undesirable viscosity and color changes in the'paste. The perfumes are preferably withheld from the starch pasting step because of their volatility, and some of the preservatives, notably phenyl mercuric acetate, are preferably withheld because of their heat sensitivity. After the paste has been prepared, with or Without the permissible additives, it is cooled to about 135 F. to about 145 P. Then the borax and sodium tripolyphosphate, plus perfume and preservative if desired, are stirred into the cooled paste.

It is desirable to finish off and package the final product at the highest temperature which can be tolerated by the glass containers or the product itself, Whichever is lower. Usually the latter is the controlling temperature. High packaging temperature alleviates the problem of controlling subsequent spoilage of the product by fermentation.

Alternative methods of preparing the new liquid laundry starch compositions comprise the following: (I) prepare the base starch paste by dissolving or dispersing a suitable pregelatinized and dried starch product in water, then incorporate the other ingredients, including the essential borax and sodium tripolyphosphate, with or without heating the mixture; (2) prepare the base starch paste by mixing the required proportions of ungelatinized starch and water with sodium hydroxide equivalent to the borax and sodium tripolyphosphate normally added with heating, if necessary, then add the other ingredients including the essential boric and tripolyphosphoric acids.

A preferred particular method of preparing a commercially successful liquid laundry starch composition,

one replete with blue dye, perfume, preservative, water softener, optical whitener, and essential freeze-thaw stabilizing agents is as follows. The ungelatinized starch is added to the required amount of water with agitation in a tank. If desired in the final product, the water softener, ironing aid, optical whitener, soap, and dye are added to the starch-water slurry at this time. The resulting mixture is then heated with agitation to about l-210 F. with injected steam and held at that temperature with continued stirring for about 30 minutes. The hot paste is cooled, or allowed to cool, to F. The borax and sodium tripolyphosphate, plus optiona1 perfume and heat-sensitive preservative, are then stirred into the cooled paste. After the latter ingredients are thoroughly dispersed and dissolved in the starch paste, the product is packaged in glass containers.

The following examples present more detailed information about illustrative embodiments of the present invention.

The water, starch, sodium hexametaphosphate, sulfonated castor oil, soap, and dye are stirred together at room temperature until the Water soluble materials are dissolved and the others are uniformly dispersed. Then the mixture is heated and stirred, without substantial loss or gain of water, at about 210 F. for about 30 minutes. Then it is cooled to about 140 F. and the remaining ingredients in the above formulation are added with continued agitation of the warm paste. The resulting homogeneous product is now ready'for packaging or use.

If desired, some of the water in the aboveformulation may be withheld from the starch pasting operation and added later. passed through a screen (50 mesh, for example) or centrifuged at moderate centrifugal forces to remove any solid foreign material present. The paste remains fluid during prolonged storage and has good freeze-thaw stability.

Example 2 Grams Water 810 Starch 150 Borax 20 Sodium tn'polyphosphate 20 Example 3 Grams Water 827 Starch 150 Borax 18 Sodium tripolyphosphate 3 Sodium hexametaphosphate 2 The water, starch, and sodium hexametaphosphate are stirred together cold, then heated with continued stirring for about 30 minutes at 205-210 F. to paste the starch thoroughly. The paste is then cooled to about 145 F., at which temperature the borax and tripolyphosphate are added with stirring.

Example 4 Grams Water 890 Starch 100 Borax 9 Sodium tripolyphosphate 1 The ingredients in the foregoing formulation are mixed and processed according to the procedure outlined in Example 2.

Example 5 Grams Water 900 Starch 70 Borax 20 Sodium tripolyphosphate The foregoing ingredients are mixed and processed according to the procedure outlined in Example 2.

Example 6 Grams Water 910 Starch 50 Borax Sodium tripolyphosphate 20 The foregoing ingredients are mixed and processed according to the procedure outlined in Example 2.

As used in the foregoing specification and in the following claims, the term borax designates sodium tetraborate dodecahydrate represented by the empirical formula Na B O .10I-I O. It is to be understood that equivalent amounts of other forms of sodium tetraborate on Also, the finished product may be' the anhydrous salt basis, may be substituted for borax in the examples and claims. One such other commerically available form is the pentahydrate of sodium tetraborate, Na B 0 .5H O. The term sodium tripolyphosphate used in the foregoing specification and in the following claims designates a solid, anhydrous, Water-soluble inorganic salt represented by the empirical formula Na P O It is commercially available under the name sodium tripolyphosphate (anhydrous). V

The term starch as used in the foregoing specification and following claims designates the known class of materials at a typical commercial moisture content of about 12%. When the term refers to starch dispersed in a starch paste, as, for example, an aqueous starch paste containing from about 5% to about 15% thereof by weight of starch, it means 12% moisture starch, i.e., 88 parts by weight of starch drysubstance accompanied by 12 parts by weight of water.

Having fully described my invention, what I claim as new is:

l. A non-gelling liquid laundry starch composition consisting essentially of an aqueous starch paste containing from about 5% to about 15% thereof by weight of starch, said paste being stabilized against objectionable separation of the dispersed starch therein, during alternate freezing and thawing thereof, with about 1% to about 4% thereof by weight of a mixture of borax and sodium tripolyphosphate, the weight ratio of said phosphate to combined weight of borax and said phosphate ranging from about 0.1 to about 0.5.

2. A non-gelling liquid laundry starch composition consisting essentially of an aqueous starch paste containing from about 5% to about 15 thereof by weight of starch and an efiective amount of sodium hexametaphosphate up to about 1% thereof by weight, said paste being stabilized against objectionable separation of the starch dispersed therein, during alternate freezing and thawing thereof, with about 1% to about 4% thereof by weight of a mixture of borax and sodium tripolyphosphate, the weight ratio of said phosphate to combined weight of borax and said phosphate ranging from about 0.1 to about 0.5.

3. The method of preparing a non-gelling and freezethaw stabilized liquid laundry starch composition comprising heating an aqueous slurry of ungelatinized starch containing from about 5% to about 15% thereof by weight of starch within the temperature range of about 190 F. to about 210 F. for a time ranging from about 15 to about 60 minutes, whereby the starch is pasted, cooling the hot paste to within the temperature range of about F. to about F., and mixing and dissolving therein from about 1% to about 4% thereof by weight of a mixture of borax and sodium tripolyphosphate, the weight ratio of said phosphate to combined weight of borax and said phosphate ranging from about 0.1 to about 0.5.

4. The method of preparing a non-gelling and freezethaw stabilized liquid laundry starch composition comprising heating an aqueous slurry of ungelatinized starch containing from about 5% to about 15% thereof by weight of starch and up to about 1% thereof by weight of sodium hexametaphosphate within the temperature range of about F. to about 210 F. for a time ranging from about 15 minutes to about 60 minutes, whereby the starch is pasted, cooling the hot paste to the temperature range of about 135 F. to about 145 F., and mixing and dissolving therein from about 1% to about 4% thereof by weight of a mixture of borax and sodium tripolyphosphate, the weight ratio of said phosphate to combined weight of borax and said phosphate ranging from about 0.1 to about 0.5.

5. A non-gelling liquid laundry starch composition as defined in claim 1 wherein the starch is hypochlorite oxidized starch.

6. A non-gelling liquid laundry starch composition as defined in claim 2 wherein the starch is hypochloritc oxidized starch.

7. The method of preparing a non-gelling and freezethaw stabilized liquid laundry starch composition as de- 5 fined in claim 3 wherein the starch is hypochlori'te oxidized starch. V

8. The method of preparing a non-gelling and freezethaw stabilized liquid laundry starch composition as defined in claim 4 wherein the starch is hypochlorite 10' oxidized starch.

References Cited in the file of this patent UNITED STATES PATENTS Kaufiimann et a1. July 28, 1942 Smith et a1. May 9, 1944 Becker et a1. July 15, 1947 Fuller June 18, 1957 Todd Dec. 23, 1958 FOREIGN PATENTS Great Britain July 13, 1936

Claims

1. A NON-GELLING LIQUID LAUNDRY STARCH COMPOSITION CONSISTING ESSENTIALLY OF AN AQUEOUS STARCH PASTE CONTAINING FROM ABOUT 5% TO ABOUT 15% THEREOF BY WEIGHT OF STARCH, SAID PASTE BEING STABILIZED AGAINST OBJECTIONABLE SEPARATION OF THE DISPERSED STARCH THEREIN, DURING ALTERNATE FREEZING AND THAW THEREOF, WITH ABOUT 1% TO ABOUT 4% THEREOF BY WEIGHT OF A MIXTURE OF BORAX AND SODIUM TRIPOLYPHOSPHATE, THE WEIGHT RATIO OF SAID PHOSPHATE TO COMBINED WEIGHT OF BORAX AND SAID PHOSPHATE RANGING FROM ABOUT 0.1 TO ABOUT 0.5.