Multilayer detergent tablets for dishwashing machines

Claim 2

A multilayer detergent tablet for dishwashing machines based on alkaline components selected from the group consisting of alkali metal metasilicates and pentaalkali metal triphosphates; an active chlorine compound; and surfactant; said tablet comprising a first cold water-soluble layer of alkali metal metasilicate nonahydrate and pentaalakli metal triphosphate containing from about 7 to about 22.4% by weight water of crystallization in a weight ratio of from 0.35:1 to 1:1, based on anhydrous compounds, and from about 1 to about 5% by weight of a low-foaming nonionic surfactant; and a second layer which dissolves rapidly at increasing water temperaures comprising from about 88 to about 98% by weight of anhydrous alkali metal metasilicate and pentaalkali metal triphosphate in a weight ratio of from about 2:1 to 1:2, based on anhydrous compounds, and from about 0.5 to about 5% by weight of an active chlorine compound, said first layer having a specific gravity of from about 1.2 to about 1.4 g/cm 3 , and said second layer having a specific gravity of from about 1.4 to about 1.7 g/cm 3 .

Claim 3

A mulilayer detergent tablet in accordance with claim 1 wherein said tablet contains as tabletting aids, from about 0.5 to about 2.5% by weight of calcium hydrogen phosphate dihydrate and from about 1 to about 5% by weight of anhydrous sodium acetate, based on the weight of said tablet.

Claim 4

A multilayer detergent tablet in accordance with claim 1 wherein said first layer is colored.

Claim 5

A multilayer detergent tablet in accordance with claim 1 wherein said alkali metal metasilicate nonahydrate is colored.

Claim 6

A multilayer detergent tablet in accordance with claim 1 wherein said alkali metal metasilicate present in said second layer is a mixture of anhydrous metasilicate and metasilicate nonahydrate.

Claim 7

A multilayer detergent tablet in accordance with claim 1 wherein said pentaalkali metal triphosphate present in said second layer is anhydrous.

Claim 8

A multilayer detergent tablet in accordance with claim 1 wherein said tablet has a specific gravity of from about 1.35 to about 1.55 g/cm 3 .

Claim 9

A dishwashing process comprising adding to a dishwashing machine a multilayer detergent tablet based on alkaline components selected from the group consisting of alkali metal metasilicates and pentaalkali metal triphosphates; an active chlorine compound; and surfactant; said tablet comprising a first cold water-soluble layer of alkali metal metasilicate nonahydrate and pentraalkali metal triphosphate containing from about 7 to about 22.4% by weight water of crystallization in a weight ratio of from 0.35:1 to 1:1, based on anhydrous compounds, and from about 1 to about 5% by weight of a low-foaming nonionic surfactant; and a second layer which dissolves rapidly at increasing water temperatures comprising from about 88 to about 98% by weight of anhydrous alkali metal metasilicate and pentaalkali metal triphosphate in a weight ratio of from about 2:1 to 1:2, based on anhydrous compounds, and from about 0.5 to about 5% by weight of an active chlorine compound, said first layer having a specific gravity of from about 1.2 to about 1.4 g/cm 3 , and said second layer having a specific gravity of from about 1.4 to about 1.7 g/cm 3 .

Claim 10

A dishwashing process comprising adding to a dishwashing machine a multilayer detergent tablet based on alkaline components selected from the group consisting of alkali metal metasilicates and pentaalkali metal triphosphates; an active chlorine compound; and surfactant; said tablet comprising a first cold water-soluble layer of alkali metal metasilicate nonahydrate and pentraalkali metal triphosphate containing from about 7 to about 22.4% by weight water of crystallization in a weight ratio of from 0.35:1 to 1:1, based on anhydrous compounds, and from about 1 to about 5% by weight of a low-foaming nonionic surfactant; and a second layer which dissolves rapidly at increasing water temperatures comprising from about 88 to about 98% by weight of anhydrous alkali metal metasilicate and pentaalkali metal triphosphate in a weight ratio of from about 2:1 to 1:2, based on anhydrous compounds, and from about 0.5 to about 5% by weight of an active chlorine compound, said first layer having a specific gravity of from about 1.2 to about 1.4 g/cm 3 , and said second layer having a specific gravity of from about 1.4 to about 1.7 g/cm 3 .

Claim 11

A process in accordance with claim 8 wherein said tablet contains as tabletting aids, from about 0.5 to about 2.5% by weight of calcium hydrogen phosphate dihydrate and from about 1 to about 5% by weight of anhydrous sodium acetate, based on the weight of said tablet.

Claim 12

A process in accordance with claim 8 wherein said first layer is colored.

Claim 13

A process in accordance with claim 8 wherein said alkali metal metasilicate present in said second layer is a mixture of anhydrous metasilicate and metasilicate nonahydrate.

Claim 14

A process in accordance with claim 8 wherein said pentaalkali metal triphosphate present in said second layer is anhydrous.