EP0132184B1 - Washing compositions suitable for washing dishes in washing-machines - Google Patents

Abstract

1. A washing compound suitable for washing crockery in dishwashers, comprising as a percentage by weight relative to composition : - 25 to 60% softening agent selected from polyphosphates, - 30 to 70% alkalinising agent selected from sodium salts containing sodium metasilicate, - 0.5 to 4% non ionic surface-active agent, - 0.5 to 5% coated trichloroisocyanuric acid, characterised in that the trichloroisocyanuric acid is coated using a polyethylene wax in a proportion of 0.5 to 10% by weight relative to the weight of the acid, the said wax having a mean molecular weight of approximately 2 500, a low melting point of less than 70 degrees C, a dripping point of 70 to 80 degrees C with a density of 0.86 to 0.88.

Description

The present invention relates to new detergent compositions suitable for washing dishes in a washing machine, and to a process for their preparation.

• - d'un agent adoucissant généralement choisi dans la classe des polyphosphates. Parmi les polyphosphates utilisés, on peut citer le tripolyphosphate de sodium, l'hexamétaphosphate de sodium, le pyrophosphate de sodium, ainsi que les polyphosphates de potassium correspondants.
• - d'un agent alcalinisant qui est constitué par un sel de sodium contenant un métasilicate de sodium sous sa forme anhydre ou sous sa forme pentahydrate, De façon connue le silicate de sodium peut être partiellement remplacé par du carbonate de soude, du sulfate de sodium, ou de la soude,
• - d'un agent tensio-actif non moussant du type non ionique choisi parmi les classes de produits suivants : alcools linéaires éthoxylés, condensat d'oxyde d'éthylène sur l'oxyde de propylène, oxyalcoyl amines, polyéthoxyéthers d'alcools gras, alkyl phénols éthoxylés ou esters phosphoriques d'alcools gras. De préférence, pour des raisons d'efficacité, de biodégradabilité et de coûts, on choisit un agent tensio-actif de la classe des alcools linéaires éthoxylés,
• - et d'un agent de désinfection.

Dishwashing in the machine involves both the detergent action and the mechanical action of water. Apart from its detergent action, the detergent must also have a disinfecting power and softening properties of water. It is therefore necessary that the detergent has a strong detergency but also a composition such that it does not cause foaming. harmful to the mechanical action of water. This is why the detergent compositions are constituted in a known manner:

• - a softening agent generally chosen from the class of polyphosphates. Among the polyphosphates used, mention may be made of sodium tripolyphosphate, sodium hexametaphosphate, sodium pyrophosphate, as well as the corresponding potassium polyphosphates.
• - an alkalizing agent which consists of a sodium salt containing a sodium metasilicate in its anhydrous form or in its pentahydrate form, In known manner the sodium silicate can be partially replaced by sodium carbonate, sodium sulfate , or soda,
• - a non-foaming surfactant of the nonionic type chosen from the following classes of products: ethoxylated linear alcohols, ethylene oxide condensate on propylene oxide, oxyalkyl amines, polyethoxy ethers of fatty alcohols, alkyl ethoxylated phenols or phosphoric esters of fatty alcohols. Preferably, for reasons of efficiency, biodegradability and costs, a surfactant from the class of ethoxylated linear alcohols is chosen,
• - and a disinfection agent.

The disinfecting agent used which releases active chlorine is generally a solid chlorine product, most often a sodium or potassium salt of dichloroisocyanuric acid. Until now, an anhydrous sodium dichloroisocyanurate titrating 63% active chlorine has been used in practice, or a sodium dihydrate dichloroisocyanurate titrating 56% active chlorine, or an anhydrous potassium dichloroisocyanurate titrating 59% active chlorine, either a potassium dichloroisocyanurate monohydrate titrating 56% active chlorine, or a calcium dichloroisocyanurate tetrahydrate titrating 56% active chlorine. Active chlorine is defined as the oxidizing power due to positive chlorine. To better understand what positive chlorine corresponds to, it should be remembered that the chlorine present in the chlorinated derivatives described above is fixed on the nitrogen atom and is there in the form of the degree of oxidation + 1, c 'ie CI'. During the oxidation-reduction process, a CI + ion combines with two electrons to pass to the Cr (chloride) stage. Two equivalents of oxidants are released which correspond to 71 g of elemental chlorine although the atomic mass is only 35.5. This also means that an atom of CI + has the same oxidizing power as a molecule of elementary chlorine C1 ₂ .

Among the other chlorinated disinfectants in the chloroisocyanuric family, there is one: trichloroisocyanuric acid, which contains almost 91% active chlorine. It would therefore be advantageous to be able to use this compound given its high percentage of active chlorine. Unfortunately, until now its use was not possible because it has too great a reactivity with respect to the other constituents of the detergent compositions in particular with respect to the surfactants, which makes the detergents containing trichloroisocyanuric acid unstable on storage as they lose both significant amounts of chlorine and surfactants by mutual destruction.

Different methods of stabilizing chlorinated disinfectants have been developed. According to European patent application 54094, the chlorinated agent, which is a chlorinated trione triazine, is coated with phthalic diester acid or adipinic acid. American patent US Pat. No. 3,703,470 proposes the coating of nonionic and anti-foaming surfactants with synthetic resins in order to avoid their reaction with chlorinated agents. According to American patent US-A-3 108 078, the chlorinated agent which is trichloroisocyanuric acid is stabilized using olefins having a tertiary carbon on a double bond, such as terpenes. In a different way, American patent US-A-4,126,717 proposes a coating using a mixture consisting of a fatty acid, a microcrystalline wax and possibly a copolymer of polyoxyethylene-polyoxypropylene, at the right rate. at least 35% by weight relative to the particle of coated acid.

We have now found a way to stabilize trichloroisocyanuric acid, in particular to stabilize it for the manufacture of storage stable laundry compositions suitable for washing dishes in washing machines.

• - 25 à 60 % en poids d'un agent adoucissant choisi parmi les polyphosphates,
• - 30 à 70 % en poids d'un agent alcalinisant choisi parmi les sels de sodium contenant du métasilicate de sodium,
• - 0,5 à 4 % en poids d'un agent tensio-actif non ionique,
• - 0,5 à 5 % en poids d'acide trichloroisocyanurique enrobé,

caractérisé par le fait que l'acide trichloroisocyanurique est enrobé à l'aide d'une cire de polyéthylène utilisée à raison de 0.5 à 10% en poids par rapport au poids d'acide, ladite cire possédant un poids moléculaire moyen d'environ 2 500, un bas point de fusion inférieur à 70 °C. un point de goutte de 70 à 80 °C et une densité de 0,86-0.88.The present invention relates to a new detergent composition suitable for washing dishes in a washing machine, containing with respect to the composition:

• 25 to 60% by weight of a softening agent chosen from polyphosphates,
• 30 to 70% by weight of an basifying agent chosen from sodium salts containing sodium metasilicate,
• - 0.5 to 4% by weight of a nonionic surfactant,
• - 0.5 to 5% by weight of coated trichloroisocyanuric acid,

characterized in that the trichloroisocyanuric acid is coated using a polyethylene wax used in an amount of 0.5 to 10% by weight relative to the weight of acid, said wax having a weight molecular average of about 2,500, a low melting point below 70 ° C. a drop point of 70 to 80 ° C and a density of 0.86-0.88.

Polyethylene waxes have been found to be compatible with trichloroisocyanuric acid. In addition, they allow using relatively low doses to obtain good acid stabilization. Furthermore, they are dispersible under washing conditions, that is to say in aqueous media having a temperature of 50 to 65 ° C.

Polyethylene waxes are used in an amount of 0.5 to 10% by weight relative to the trichloroisocyanuric acid and preferably in an amount of 3 to 5% by weight. Beyond 5% of the difficulties for the implementation of the coating appear and it is necessary to adjust the conditions of the coating.

The use of amounts greater than 10% does not bring a significant improvement in the storage stability of the laundry compositions; the use of amounts less than 0.5% leads to an insignificant acid stabilization.

The laundry compositions which are the subject of the invention are produced by first coating the trichloroisocyanuric acid with the aid of polyethylene waxes. This coating is carried out in any industrial mixer, such as a drum mixer, preferably a mixer provided with a heating device. It is also possible to use a rotary mixer of the concrete mixer type in which the molten wax is sprayed on the acid heated to a temperature close to 50 ° C. The processing temperature allows a good distribution of polyethylene waxes which solidify on cooling. The wax-coated trichloroisocyanuric acid is then mixed in another mixer with the other constituents of the detergent.

The amounts of the various constituents used for the manufacture of the new detergent compositions which are the subject of the invention are used in conventional weight ratios. The softening agent chosen from polyphosphates is used in an amount of 25 to 60% by weight and preferably from 40 to 50% by weight relative to the weight of the composition. The alkanizing agent chosen from sodium salts containing sodium metasilicate is used in an amount of 30 to 70% by weight and preferably from 40 to 60% by weight relative to the weight of the composition. In known manner, the sodium silicate can be partially replaced by sodium carbonate, sodium sulphate or soda. The nonionic surfactant is used in an amount of 0.5 to 4% by weight and preferably in an amount of 1 to 3% by weight relative to the weight of the composition, the trichloroisocyanuric acid coated with the using polyethylene waxes is used in an amount of 0.5 to 5% by weight and preferably 1 to 3% by weight relative to the weight of the composition.

The following examples illustrate the present invention.

Example 1

• L'acide est chauffé à une température de 50 °C puis est mis dans un mélangeur tournant. Durant la rotation du mélangeur, on pulvérise dessus à l'aide d'un pistolet des cires de polyéthylène. La température de mise en oeuvre permet une bonne répartition des cires qui se solidifient au refroidissement. Les cires de polyéthylène utilisées ont un point de fusion inférieur à 70 °C, un point de gouttes de 70 à 80 °C et une densité de 0,86 à 0,88. On réalise divers mélanges d'acide et de cires en mettant en oeuvre des pourcentages variables de cires de polyéthylène. Les mélanges ainsi obtenus sont utilisés pour la fabrication de compositions de lessive.

Trichloroisocyanuric acid is stabilized beforehand using polyethylene waxes as follows:

• The acid is heated to a temperature of 50 ° C and then put into a rotating mixer. During the rotation of the mixer, polyethylene waxes are sprayed on it with a gun. The processing temperature allows a good distribution of the waxes which solidify on cooling. The polyethylene waxes used have a melting point below 70 ° C, a drop point of 70 to 80 ° C and a density of 0.86 to 0.88. Various mixtures of acid and waxes are produced using variable percentages of polyethylene waxes. The mixtures thus obtained are used for the manufacture of laundry compositions.

• - tripolyphosphate de sodium : 50 parties.
• - métasilicate de sodium (anhydre ou hydraté 5 H₂0) : 50 parties
• - un tensio-actif non ionique éthoxylé fabriqué par la Société PCUK, de dénomination commerciale PLURAFAC RA 43: 2 parties,
• - acide trichloroisocyanurique enrobé de cires de polyéthylène : 2 parties.

Detergents are prepared having the following composition (the parts are expressed in parts by weight):

• - sodium tripolyphosphate: 50 parts.
• - sodium metasilicate (anhydrous or hydrated 5 H ₂ 0): 50 parts
• an ethoxylated nonionic surfactant manufactured by the company PCUK, with the commercial name PLURAFAC RA 43: 2 parts,
• - trichloroisocyanuric acid coated with polyethylene waxes: 2 parts.

First, the sodium tripolyphosphate is premixed with the nonionic surfactant in a rotary type mixer. After 20 minutes a homogeneous mixture is obtained. The metasilicate is then added to the mixer and after 20 minutes the coated trichloroisocyanuric acid is added. The assembly is then left in the rotating mixer for 20 minutes. The percentage of chlorine dosed by iodometry in the detergent composition is then 1.65%.

• - température : 42 °C,
• - humidité relative : 85 %.

The composition of detergent thus obtained is put in plastic bags closed by a non-hermetic link. The bags are stored in a controlled atmosphere oven under the following conditions:

• - temperature: 42 ° C,
• - relative humidity: 85%.

Samples are taken after a storage period of between 2 and 3 months and the remaining chlorine is analyzed by iodometry. Table 1 shows the results obtained after 80 days of storage for detergent compositions prepared either from anhydrous sodium metasilicate, or from sodium metasilicate pentahydrate and from trichloroisocyanuric acid coated with waxes. polyethylene used in variable percentages (by weight). Chlorine results remaining are expressed as percentages relative to the initial chlorine.

Example 2

Example 1 is repeated using trichloroisocyanuric acid coated with various quantities of polyethylene waxes and the determination of the remaining chlorine is carried out after 70 days of storage. Table 2 summarizes the results obtained.

Claims (4)

1. A washing compound suitable for washing crockery in dishwashers, comprising as a percentage by weight relative to composition :

- 25 to 60 % softening agent selected from polyphosphates,

- 30 to 70 % alkalinising agent selected from sodium salts containing sodium metasilicate,

- 0.5 to 4 % non ionic surface-active agent,

- 0.5 to 5 % coated trichloroisocyanuric acid,

characterised in that the trichloroisocyanuric acid is coated using a polyethylene wax in a proportion of 0.5 to 10 % by weight relative to the weight of the acid, the said wax having a mean molecular weight of approximately 2 500, a low melting point of less than 70 °C, a dripping point of 70 to 80 °C with a density of 0.86 to 0.88.

2. A compound according to claim 1, characterised in that the trichloroisocyanuric acid is coated using polyethylene wax in a proportion of 3 to 5 % by weight.

3. A method for preparing compounds suitable for washing crockery in dishwashers according to claim 1, characterised in that the trichloroisocyanuric acid is coated in advance using polyethylene waxes and the coated trichloroisocyanuric acid is then mixed with the other constituents of the washing powder.

4. A method for preparing washing compounds according to claim 3, characterised in that the melted wax is then sprayed onto the trichloroisocyanuric acid which is heated to 50 °C.