Claims
- 1. A method of forming a tableted detergent from 20% to 60% of a partially hydrated phosphate mixture, anhydrous caustic, 0.5% to 5% free water and 5 to 40% filler comprising:
- adding said free water to said phosphate mixture without adding said filler, and allowing said water to be absorbed by said phosphate mixture;
- and subsequently adding 20% to 70% caustic to said phosphate mixture to form a second mixture whereby the temperature of said second mixture is maintained at less than 75.degree. C.;
- compressing said second mixture to form tablets.
- 2. The method claimed in claim 1 wherein at least 5% filler is added to said phosphate mixture after said caustic is added to said phosphate mixture.
- 3. The method claimed in claim 1 wherein said temperature of said second mixture is maintained at less than 50.degree. C.
- 4. The method claimed in claim 2 wherein said hydrated phosphate comprises a mixture of sodium tripolyphosphate and sodium tripolyphosphate hexahydrate.
- 5. The method claimed in claim 3 comprising adding fillers to said phosphate mixture after said water has been absorbed by said phosphate.
- 6. The method claimed in claim 3 comprising 1% to 3% free water.
- 7. The method claimed in claim 2 wherein said filler is selected from the group consisting of soda ash, alkali metal silicates, alkali metal polysilicates, alkali metal metasilicates, alkali metal chloride, alkali metal sulfates, and alkali metal bicarbonates.
- 8. The method claimed in claim 2 comprising 40 to 70% caustic.
- 9. The method claimed in claim 3 wherein the temperature of said second mixture is maintained at less than 40.degree. C.
- 10. A method of forming a compressed detergent tablet, said tablet comprising:
- from about 20% to about 70% by weight caustic;
- from about 20% to about 60% by weight of a sequestering agent consisting of a combination of sodium tripolyphosphate and sodium tripolyphosphate hexahydrate;
- from about 1 to about 4% by weight polycarboxylic acid having a molecular weight of 2,000 to 20,000;
- from about 0.5 to 5% by weight of a defoaming agent, and from about 1 to about 5% by weight propylene glycol and from about 5% to about 40% filler;
- and free water;
- said method comprising combining said propylene glycol, said defoaming agent, said polycarboxylic acid and said free water to form a liquid mixture, combining said liquid mixture with said sequestering agents, and permitting said liquid mixture to be adsorbed by said sequestering agents to form a first detergent mixture;
- subsequently combining said filler and said caustic to said first detergent mixture to form a second detergent mixture and compacting said second detergent mixture to form tablets whereby the order of addition of the detergent components prevents the second detergent mixture from reaching a temperature in excess of 50.degree. C.
- 11. The method claimed in claim 10 wherein said fillers are selected from the group consisting of alkali metal silicates, alkali metal polysilicates, alkali metal metasilicates, alkali metal chlorides, alkali metal sulfates, alkali metal carbonates, and alkali metal bicarbonates.
- 12. A method of forming a tableted detergent form 20% to 60% from a partially hydrated phosphate mixture, anhydrous caustic, 0.5% to 5% free water and 5% to 40% filler comprising:
- Combining said free water with said phosphate mixture, said filler and 20% to 70% caustic to form a detergent mixture; cooling said detergent mixture to prevent said detergent mixture from heating to above 50.degree. C. for a period of time effective to prevent said caustic from reacting further with said free water;
- Compressing said mixture to form a tablet.
RELATED APPLICATIONS
This application is a file wrapper continuation of application Ser. No. 08/408,538 filed on Mar. 22, 1995 now abandoned, which is a continuation-in-part of application Ser. No. 08/120,563 filed Sep. 13, 1993, abandoned, entitled "Tableted Detergent, Method of Manufacture and Use."
The institutional detergent market distributes a variety of products for washing silverware, pots and pans, dishes, floors, walls, stainless steel surfaces, tile and other areas.
Unlike products used in the home, institutional detergents are often sold in bulk and dispensed from mechanical dispensers. There are a variety of different physical forms these can take, including liquids, powders, solidified bricks, granules and tablets. Several factors enter into the determination of which particular physical form is most suitable for the desired application.
Feed rate is a very important consideration. With a liquid, where the product is directly injected for use, use concentration is easy to control. Unfortunately with liquids, the concentration of active components in the product is generally relatively low and therefore the container size can be prohibitively large. With solid forms, which are dissolved with water, the rate of dissolution will influence dispensing rate.
Delivering consistent feedstock is very important. With a brick formulation, the product consistency can be maintained to a certain extent, but dissolution rate can be slow and, as with many forms, there may also be problems with disposing of the container.
Another very important factor in distributing institutional detergents is packaging. For environmental reasons, it is preferable to minimize packaging. U.S. Pat. No. 5,078,306 discloses a bag of detergent tablets wherein the bag is a water soluble material. This product is apparently designed to minimize packaging, but has several significant disadvantages. Primarily, with a water soluble bag, the water will act to dissolve the plastic bag. However, the undissolved residue of such bags tend to clog the dispenser. Also with a water soluble bag, there is the requirement of an exterior overwrap to prevent humidity or extraneous water from destroying the water soluble bag during shipping and storage.
All of these problems are compounded with highly hygroscopic (highly caustic) and/or hydratable materials. Of course, with the caustic materials, the operators should never physically handle the detergent, Powdered cleaning compounds are typically dispensed with water. Given that premature exposure to water tends to increase the caking tendency of powders, clogging of the dispenser and uniform dispensing from powder systems, especially those prone to prolonged periods of inactivity, may be a problem.
Many detergents, particularly highly caustic detergents, dissolve in water and liberate a great deal of heat. It is therefore preferable to control the dissolution rate of these detergents to avoid temperature peaks in the dispensing equipment.
With tableted, high-caustic detergent, a further problem can be encountered. Anhydrous sodium hydroxide and potassium hydroxide are, of course, very hygroscopic. Typical detergent formulations generally include some free water, and certainly water of hydration from sources such as sodium tripolyphosphate hexahydrate. When tableting, the caustic comes into very close physical proximity to the water. The water is necessary for the tableting to occur at reasonable pressures. But once combined together, the caustic will exothermically react with the free water. For tableted high caustic detergents, if this reaction occurs after compression, the mechanical strength of the tablet will be reduced.
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Continuations (1)
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Number |
Date |
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| Parent |
408538 |
Mar 1995 |
|
Continuation in Parts (1)
|
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Date |
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| Parent |
120563 |
Sep 1993 |
|
Patent Grant
5759976
