CA1112535A - Feed unit of a detergent composition based on alkali carbonate - Google Patents

Abstract

FEED UNIT OF A DETERGENT COMPOSITION
BASED ON ALKALI CARBONATE

Abstract of the Disclosure The present invention relates to a feed unit of a detergent composition containing one or more surfactants, an alkali carbonate, and an acid which forms water-soluble calcium salts and magnesium salts and/or complexes, and in which detergent composition the acidic constituent and the alkaline, constituent are separately present, the acidic constituent having a higher rate of solubility in a wash liquor than the alkaline constituent, and the total amount of alkali being present in excess relative to the amount of acid.
The invention is characterized in that the feed unit comprises a sachet which entirely or partly consists of a material permeable to or disintegrating in water and is filled with the acidic and the alkaline constituent, the acidic constituent containing 5-30 per cent by weight, calculated on the total amount of detergent composition, of an acid having a pK1 value in the range of 2,8 to 4,8.
It is preferred that the sachet should have 2 compartments, the acidic constituent being contained in the one compartment and the alkaline constituent in the other compartment.

Description

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The present invention rela~es to a feed unit of a ¦ detergent composition containing one or more surfactants, an alkali carbonate, and an acid which forms water-soluble calcium I salts and magnesium salts and/or com~lexes, and in which 1i detergent composition the acidic constituent and the alkaline 11 constituent are separately present, the acidic constituent having a higher rate of solubility in a wash liquor than the alkaline constituent, and the total amount of alkali being present in I excess relative to ~he amount of acid.
! A feed unit of the type indicated above is known from the United States Patent Specification 3 761 415. Said patcnt 1I specification describes a phosphate-free detergent composition ¦¦ in the form of a tablet consisting of a substance such as citric ! acid which when in solution releases citrate ions, and an alkali ¦i carbonate and a synthetic surfactant. The tablet described ¦ comprises an outer layer of the source of citrate ions and an ¦ inner body of alkali carbonate.
In essence, the citrate ions go into solution before the sodium carbonate and in such an amount that the formation of water-insoluble calcium carbonates and magnesium carbonates is inhibited.
Disadvantages to the tablet described are that it dissolves relatively slowly and comes into direct contact ~7ith the washing.
This direct contact may give rise to fibre damage and dis-coloration of the washing. This disadvantage is f~ndespecially with the above-mentioned detergent composition because it contains a relatively high percentage by weight of citric acid.
At a German Hardness of 6 the wash liquor should preferably contain 0,5 per cent by wei~ht of citric acid and 30 ~ p~r cent- hy weight of alkali carbonate. Converted for a ¦ feed unit, I -1- ,'~

l, 5~q~ :

! the detergent compositions given in the examples contain 33 ¦, to 57 per cent by weight of citric acid. Also for reasons of , economy, partly because of the relatively high cost price of citrates and citric acid, such a percentage is unacceptably high.
I Moreover, even at low initial hardness values the remaining hardness a~pears to be relatively high, which for instance Il unfavourably affects the envisaged cleaniny effect.
! The feed unit according to the invention does not show these ' drawbacks and is characterized in that the feed unit comprises i a sachet which entirely or partly consists of a material ¦, ermeable to and disintegrating in water and is fillec~ with the ¦, acidic and the alkaline constituent, the acidic constituent ¦ containing 5-30 per cent by weight, calculated an total amount of detergent composition, of one or more acids having a pK
value in the range of 2,~ to 4,8.
The present invention provides a solution to the problem of excluding from detergent compositions those components that are (may be) harmful from an ecological point of view. As examples Il of such ~ossibly harmful components may be mentioned the i frequently employed sodium polyphosphate and other phosphates.
Phosphates form an indispensable nutrient for vegetable and ~
¦l animal life. When present ln highconcentrations in stagnant or slowly flowing water, however, they ma~ give rise t-o excessive growth of algae. One of its consequences is a decrease of the 11 oxygen content in the dee~er parts of the water, and anoerobic i processes may cause the formation of gases such as methane and carbon disulphide. These phenomena may have a detrimental influence on fish-stock and may cause considerable damage to I areas of natural beauty and recreation.
3~ In vittl of the severity of the above problem there has in the ~1 5;~

¦l last few years been an intensive search for suitable substitutes for phos~hates in detergent compositions.
Il The phosphates are added to the detergents because they are ¦l capable for instance of binding calcium ions and magnesium ions ~! to form soluble complexes. As a result, these ions can no longer j form objectionable precipitates along with ingredients of the j wash liquor or with dirt held by the fabric to be laundered.
, These precipates are objectionable in that they deposit on the ~1 laundered fabric. Substitutes for ~hosPhate that have been proposed include oxidized polysaccharides, certain cellulose derivatives, citrates, nitrilotriacetates and water-insoluble sodium alumino-silicates.
I Total replacement of r,hosphates has so far been realized only ¦l on a limited scale.
ll According to the invention the above problem can be !~ solved in an inexpensive ~lay by the use of a detergent ¦I composition based on alkali carbonate. The conventional ~ detergent compositions based on alkali carbonate have the disadvantage that in successive washing cycles they give rise to considerable growth of water-insoluble carbonates on the I fabric being cleansed. This drawback is still agc~ravated in that ¦ such incrustation is cumulative and may increase more than ¦I proportionally as a function of the number of washing cycles.
¦¦ As a result, the quality of the fabric treated with these ¦¦ compositions will be affected and the fab~ic ~ill display little ¦~ absorption power and have a stiff and hard handle; moreover, Il wear and discoloration will occur~
¦¦ Besides, as a result of aging, the carbonate precipitate will ¦! become more and more diflicult to dissolve.

il -It has been found, however, that in one washing cycle so little I fabric incrustation occurs that the above-mentioned drawbacks i are not met. The useof afeed unit of the detergellt composition I according to the invention results 1n the fabric incrustation I formed in one washing cvcle being brought into solution at the beginning of the next washing cycle by a reaction with acid j under mildly acid conditions. The mildly acid conditions should be maintained sufficiently long to allow the precipitated I carbonates to practically completely dissolve.
Subsequently, as a result of the alkaline constituent going into solution, the wash li~uor is softened. For the presence I ! of the alkali carbonate in the water causes the calcium ions and the rnagnesium ions contained in the wash liquor to he , precipitated as water-inso]uble carbonates. For maximum ¦I softening and optimum ~Jashing effect the pH of the wash liquor, Il after almost complete dissolution of the alkaline constituent, - 1 should have a value in the ran~e of 9,Q to 10, 5 . Application ¦l of the present invention prevents appreciable growth in a ¦ fabric of insoluble carbonates or other salts.
1l The use of a sachet on the one hand leads to avoiding direct ¦ contact between the acid and the washinq and on the other hand ' makes it possible for the detergent composition to be brought into a form in which both the acidic and the alkaline constituent ~¦ sufficiently rapidly dissolve in the wash liquor. Moreover, a ¦ feed unit of the detergent composition according to the inventioi;
need contain only a relatively small percentage oE acid.
, It should be added that the German Patent Specification 2 437 173 ¦ describes a ~rocess which comprises successive treatments with ¦ll an acidic pre-wash detergent composition and an alkaline main ll wash detergent composition based on sodium carbonate. The 53~

li present invention has the advantage over that according to ¦, said German Patent Specification 2 437 173 that the envisaged prevention of appreciably cumulative incrustation is realized by the use of a single detergent composition. Moreover, with the feed unit according to the inventlon direct contact is ¦ avoided between the detergent composition and the washing, at least as far as the acidic constituent is concerned.
Moreover, when use is made of the present deteryent I composition it is unnecessary and mostly even undesirable for ! the wash liquor entirely or largely to be drained off between i the acid and the alkaline phase of the washing process.
The acid contained in the acidic constituent should be capable of formin~ calcium salts and magnesium salts and/or complexes , that are moderately to well soluble in water.
15 ¦¦ The amount of acid should be sufficiently high to dissolve calcium carbonate and magnesium carbonate in a fabric. The required percentage by weight of acid is dependent, inter alia, , on the acid used, the bicarbonate content and the hardness of I the water employed for the washing treatrnent.
`I In practice it has been found that an amount of 5 to 30 per cent by weight, calculated on the total amount of deter~ent composition, is sufficient.
j The acidic constituent should dissolve to such an extent in the I wash liquor that within 5 minutes and preferably within 2 ~ minutes after the detergent composition has been added the wash liquor has a pH in the range of 2,Q to 5,0.
; Should the pH drop to below 2,0, then certain types of fibres may be damaged. On the other hand, a pH above 5,0 would in practice result in the carbonate taking too long to completely 30 I dissolve.

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I The pKl-value of the acid should be in the range of 2,~ and ¦l 4,8. Should the acid have pKl-value below 2,8, then the pH of i the wash liquor may temporarily dro~ to below 2,0, whereas a I pKl-value above 4,8 would in ~ractice call for the use of ¦ uneconomically large amounts of acid in order to attain a pH
I below 5,0.
¦ The alkaline constituent should not dissolve until the fabric incrustation formed in the Previous wash cycle has gone into I solution. In actual practice this means that the alkaline ¦ constituent should dissolve in the wash lic,uor only after at ¦ least 2 and not more than 10 minutes and preferably after at I least 3 and not more than 6 minutes.
¦ The acidic and the alkaline constituent should be separately li present in the detergent com~osition. To this end it is onl~
I required that the two constituents can be separately distin-¦ guished. This requirement consequently does not exclude the two constituents from being in contact with each other.
The detergent com~osition is brought into the form ~ of a feed unit comprising a sachet entirely or partly made of a material permeable to or disintegrating in water and filled ¦ with the acidic and the alkaline constituent. In this way the ~ acid is prevented from getting into contact with the washing ¦ before it dissolves. As a result, even the sli~htes-t chance of fibre damage and discoloratlon of the washing is avoided. A
sachet is filled with an amount of detergent composition which is sufficient for one washing cycle. The filled sachet can ¦ therefore be brought into the wash liquor as such.
j Such a sachet may consist of a material which does not dis-¦ integrate in water and is closed with a strip of material which I does a~sintegrate in water.

Alternatively, the sachet may be closed by means of seams filled with a material that disintegrates in water.
As examples of suitable materials that do not disintegrate in water may be mentioned polyethylene, polypropylene and poly-vinyl chloride. To close the sachet use may be made of water-dispersible paper. sy ~reference, however, the sachet consists entirely or nartly of a non-woven material. This material is ¦ permeable to water and relatively strong.
The acidic constituent should contain 5-30 per cent by ~Jeight, calculated on the total amount of detergent compo-sition, of an acid having a nKl value in the range of 2,8 to 4,8.
¦ As examples of acids which have these properties may be ¦ mentioned adipic acid, succinic acid, citric acid, diglycolic 1l acid, glycolic acid, glutaric acid, fumaric acid, lactic acid ¦l and tartartic acid.
¦ The acidic constituent may, of course, also contain a mixture ¦ of acids. By ~reference the acidic constituent should then be ¦ a mixture of adinic acid, ~lutaric acid and succinic acid. It i has been found that such a mixture very rapidly dissolves and moreover very favourably influences the rate of solubility of the precipitated carbonates during the acid phase of the washing process.
If the acidic constituent contains a mixtu~e of acids,then at ¦ least one acid should have a pKl-value in the range of 2,8 ¦ to 4,8. Such an acid may be mixed with inorganic acids such as sodium bisulphate. In combination with other acids use may also be made of polycarboxylic acids, such as polyacrylic acid, the acid form of oxidized cellulose and starch, mono- and poly-carbDxylated products obtained hy substitution of hydrogen , ' . :

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atoms of starch and cellulose, such as carboxymethyl cellulose and dicarbox~methyl starch.
I Depending on the envisaged application of the detergent com-¦¦ position one or more conventional componen-ts may be incorporated ~ into the acidic constituent.
By preference the acidic constituent contains a surfactant.
Its presence results in the acids, the washing and the precipitated carbonates being wetted more rapidly, which I favourably influences the rate of solubility of the carbonates.
I Particularly suitable for this purpose areethoxylated fatty ¦ alcohols.
Another category of materials that may be incorporated into the acidic constituent are per-cor,lpounds such as peroxides, I which have an optimum bleaching effect at a pH lower than that lS , at which the detergent composition displays optimum cleaning ~ action. Also compounds such as peroxomonosulphate, which have ¦ insufficient storage stability in the usual detergent com-positions, may be included in the acidic constituent.
I The alkaline constituent should contain such an amount of alkali ; 20 I that after the alkaline constituent has almost completely~lssolvel the ~H of the was~l liquor is 9,0-10,5. 'i'his p-l is re(luired for obtaining an optimum cleaning effect and effective softening.
¦ By preference, the alkali used is an alkali carbonate or a I mixture of alkali carbonate and, for instance, sodium silicate.
The alkali content may vary between wide limits. The detergent composition should however contain at least 5 per cent by weight of alkali carbonate in order that the calcium ions and the magnesium ions may be precipitated in the wash liquor. A
l! lower percentage would be ineffective even under the most 3~ ~I favourable ccnditions. ln some ci~cumstances it may be li ~

ll :
¦~ desirable for the detergent com?osition to contain as much as 65 per cent by wei~ht of alkali carbonate.
l A suitable alkali carbonate is sodium carbonate. Sodium ¦I carbonate and its hydrates, however, are relatively sensitive 1I to moisture. ~ith the present detergent composition this may ¦l lead to difficulties in that this detergent composition contains ¦ an acidic as ~7ell as an alkaline constituent. Also the rather ' high alkalinity sometimes forms a drawback. For these reasons ~I in addition to calcined sodium carbonate the alkaline constituent I may be made to contain as alkali carbonate sodium bicarbonate and/or sodium sesquicarbonate. These combinations of compounds are less sensitive to moisture than sodium carbonate and also have a lower alkalinity.
, ~loreover, the alkaline constituent may con-tain one I or more usual detergent components such as surfactants, builders, ~ bleaching agents, fluorescent brighteners, enzymes, foaming ¦l agents, substances such as sodium carboxymethyl cellulose, which serve to prevent dirt from re-depositiny on the fabric, , bactericides, corrosion inhibitors, perfumes, colourants, ' etcetera.
As surfactants may be used the water-soluble salts of higher fatty acids ("soaps"~ or the synthetic surLactants described in, for instance, the British Patent Specifications Il 1 429 143 and 1 473 201.
¦1 It is preferred that the surfactant contained in the alkaline ¦ constituent should be an alkyl ether sulphate. Alkyl ether sulphates have the advantage that they contribute to reduciny incrustation. Preferably use is made of sodium tallow fatty ! alcohol ether sulhate.
1, The retarded dissolution of the alkaline constitu~nt may be Il _ 9 _ i l obtained in various ways.
For example, use may be made of known shaping techniques, which I are grouped here under the generic name of agglomeration 1 techniques. By agglomeration techniques are to be understood, 1 inter alia, pelletizing, tabletting, granulating, extruding, marumerizing, briquetting, rolling followed by cutting. In this way also the surface area of the alkaline constituent is drastically reduced, which is of course of importance for the 1 present invention.
l The most important parameters influencin~ the rate o~ solution ' are the composition of the alkaline constituent, the shaping method and the shaping pressure that may be used.
It is preferred that the alkaline constituent should be pro-vided ~7ith a coating which disintegrates only after at least

2 and at most 10 minutes and preferably after at least 3 and at most 6 minutes. By disintegration are to be understood here, inter alia, dissolution and dispersion. The amount of coating material to be used is 0,1-15, and preferably 0,5-10 per cent by weight, calculated on the total amount of detergent ll composition.
¦ As coating material may be used any material kno~n to be employed for the present purpose.
, As exam?les of suitable water-soluble or water~dispersable ! pol~mers may be mentioned polyethylene glycols, polyvinyl 1~ alcohol, polyvinyl pyrrolidone! polyvinyl acetate, carboxyme-thy:l cellulose, carboxymethyl starch, hydroxypropyl cellulose, gela~
I, arabic gum, etcetera, provided that they are applied in a ',l sensible manner.
¦I Excellently suitable are (co)polymers of methacrylic acid and methacrylic esters, available under the trade names ~udra~it ~1 .

I' .

30 D and E 30 D.
It is ~referred that the feed unit should be given a form such ! that there is no direct contact between the acidic and the ~ coated or non-coated, alkaline constituent.
' To that end it is ~referred that a feed unit of the detergent cornposition should be brought into a form such that the sachet has two compartments, the acidic constituent being contained in ; the one and the alkaline constituent in the other com~artment.
Such a feed unit comr~rises for instance a sachet consistin~ of i 2 non-woven outer ~talls and a polyethylene partition ~all, the one com~artment being fillec with a powdered acidic constituent and the other compartment with a coated alkaline constituent.
The seams of these sachets may be sealed with a glue or by using pressure at elevated tem~erature.
Or the sachets may be so formed that the alkaline constituent goes into retarded dissolution as a result of the construction of the sachet.
The use of such sachets has the advantage that the alkaline constituent may be contained in the sachet in the form of powder.
; To that end a sachet may be made of which the com~artMent con-taining the alkaline constituent (the "alkaline" compartment) entirely or partly consists of a material which becomes permeable to ~1ater or disintegrates in it only after at least 1 2 and not more than 10 minutes and preferably after at least Ij 3 and not more than 6 minutes.
By disintegration is also to be understood here tearin~
of the sachet. A sachet may in ~rinciple consist of, for instance, 3 layers of material, the outer wall of the "acidic"
¦I compartment being permeable to water, the outer wall of the alkaline "compartment" being impermeable to water and the Il il .

3~ ~:
partitiOn wall for instance consisting of a mixture of poly(meth) acrylic acid (Eudragit L 30 D) polymethacrylic esters (Eudragit E 30 D) and polypropylene glycol, or a mixture of ~olymethacrylic I estsrs (Eudragit E 30 D) and hydroxypropyl methyl cellulose.
',, The water-permeable outer wall preferably consists of a non-woven material.
For the water-im~ermeable wall various materials may be used.
~; By preference however use is made of polyethylene, polypropylene, Il polyvinyl chloride or a non-woven material provided with a I water-insoluble coating.
Alternatively, the "alkaline" compartment may be closed with a strip which becomes permeable to water or disintegrates after , at least 2 and not more than 10 minutes and preferably after at least 3 and not more than 6 minutes. Such a strip may be pro-, vided as connecting strip between an im~ermeable partition wall and outer wall. Such a strip may for instance entirely or partly i consist of a mixture of polymethacrylic acid (Eudragit L 30 D), polymethacrylic esters (Eudragit E 30 D) and polypopropylene 1 glycol, or of a mixture of polymethacrylic esters and hydroxy-¦1 propyl methyl cellulose.
- l Alter~atively, the al~aline compartment may be provided with 1l one or more seams that open in water after at least 2 and not ¦I more than 10 minutes and E~referably after 3 and not more than ; 1, 6 minutes. A sachet of this type may be made by providing in 25 1~1 the seams a material which disintegrates in water within the above-mentioned period.
; For example, the seams of the sachet may entirely or partly be ¦¦ filled with a mixture of polyethylene glycol, one or more ! thermoplastic acrylic resins and highly disperse silicium oxide.
i, The seams of such a sachet will open after 4-5 minutes at a wash temperature of 55 C.
¦ The invention is further described in the following cxa-pLes.

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Exam le 1 (Comparative) The ~ollowing bundle tests were carried out in a " Wringer washing machine. The volume of the ~ash liquor t~as 50 Il litres, the water had a German Hardness of 7,5.
¦ 2,95 kilogrammes of washing consisting of napkins, bath towels, Il tea towels and parts of bed sheets were washed 20 times. The ¦I washing tests were carried out both at room temperature and at 55C. To the wash liquor there were added 83,4 grammes of a 1 traditional detergent composition based on sodium carbonate.
1, The detergent composition contained the follo~ing ingred1ents:
1,8 grammes of tallow fatty alcohol, 25 ethylene oxide 7,0 grammes of tallow fatty ether sulPhate l5,0 grammes of sodium dodecyl benzene sulphonate ,;10,0 grammes of sodium disilicate 111,8 grammes of sodium carbonate 21,5 grammes of sodium bicarbonate 1,0 gramme of sodium carboxymethyl cellulose 23,0 grammes of sodium su]Phate ,2,3 grammes of water , Of each type of washing the incrustation was determined before starting the washing tests, and after the 1Oth and the 20th washing cycles. Table I shows the results obtained after washing at room temperature. Table II gives the results obtained after washing at 55C.

1, .

( Table I
_ ~
: Number of Percentage incrustation in the washing washing cycles napkins ~sheets bath towels¦tea towcLs¦average 1,' ______ ____ ___ ~ _ __ _ ~ 0 0,19 0,21 0,42 0,21 0,26 1.10 0,63 0,54 1,02 1,01 0,80 1,20 1,19 1,08 1,72 1,54 1,38 1. _ _ i~ Table II

Number of Percentage incrustatic>ll in tl~e washillg ¦1 washing cycles napkins sheets bath towels¦t~a towels - -!j _ _ _ _ ___ '0 0,19 0,21 0,~2 0.,21 0,26 1.10 0,48 0,~9 1,87 0,66 0,88 ,120 0,88 0,96 2,31 ~,27 ~ 1,35 The above results show that when use is made of the traditional I, detergent compositions based on alkali carbonate, there will be lS 1l considerable accumulation in the washing of insoluble calcium carbonates and magnesium carbonates.
¦1 _xample 2 ¦I The following washing tests were all carried out at 55C under the conditions described in ExamPle 1. Instead of a , traditional detergent composition based on alkali carbonate a feed unit of the detergen-t composition according to the invention l~ was added to the wash liquor.
¦I The feed unit comprised a 2-compartment sachet measuring ~5x12 Il cm having an outer wall of the "alkaline" compartment of a 11 laminated non-woven material, and an outer ~Jall of the "acidic"
compartment oE a non-woven material and a partition wall of polyethylene. The seams were sealed with glue. On one side of the sachet a tear stri~ was provided between the outer wall of ¦I the alkaline compartment and the partition wall, which tear ¦I strip was about 0,07 mm thick and tore af-ter 5 minutes at a ¦I wash liquor temperature of 55C. The strip consisted of 5 parts jl of Eudragit E 30 D and 0,25 parts of Methocel H G 100 (hydroxyl propyl methyl cellulose).
!! The sachet was filled with 22,a grammes of the acid constituent ¦l and 69,0 grammes of the alkaline constituent.
Il The acidic constituent was present in the form of extrudates ! having a diameter of 0,8 mm and a length of 1 to 3 mm; thc I alkaline constituent was Present in the form of powder.
- !I The acidic constituent was made up of:
6,2 grammes of adipic acid '6,2 grammes of succinic acid 8,3 grammes of glutaric acid 1,7 grammes of tallow fatty alcohol, 25 ethylene oxide.
The alkaline constituent was made up of:
7,0 grammes of tallow fatty ether sulphate 1¦5,0 grammes of sodium dodecyl benzene sulphonate lQ,0 grammes of sodium silicate 'll39~0 grammes of sodium carbonate li1,0 gramme of sodium carboxymethyl cel]ulose Il7,0 grammes of water 1¦ During each washing cycle the pl~ of the wash liquor was measured after S and 15 minutes.
The results are shown in the following table.
' 11 .

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: I Table III

Number of pH after 5 p~l after 15 washing cycles minutes minutes . j. _ __ :: I 1 ~,1 10,2 . 5 Il 5 4,6 10,2 -1 10 4,7 10,2

4,~ 10,2 4,7 10,2 . . ~ ~_ ' The relation between pEE of the wash liquor and tirne during the ::
~ 20th washing cycle is given in the following Table IV.
,~ , j Table IV
; 1 ~
,, ............ ._. .. ~ .
:~ i, Time (in minutes) pH
. .__ .. .

j, 4 4,7 !1 8 10,2 . , _15 _ 10,2 , i Also in these washing tests the incrustation was determined ¦ before starting the washing tests, and after the 10th and the I 20th wash cycles. The resul-ts are given in the following Table V.
. ~1 : j!

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Table V

l, Nurnber of Percentage incrustation in washing ¦ washing cycles napkins ¦sheets bath towels~ tea towels avcrage 0 0 19 ~ 21 0 41 0 21 0 26 Il 10 0 08 0 12 0 42 0,23 0 21 l 20 0,18 0 17 0,43 0 31 0 27 IThe above bundle test shows that use of the present invention ¦jhardly leads to any incrustation It also a~peared that the ¦¦primary cleansing effect Or the detergent composition according ~Ito the invention com~ares with that of the ~hosphate-containing detergent composiiions.
No fibre damage was found. Nor did the washing show any appreciab1,~
discoloration.
IlExample 3 1l In the following bundle test use was made of a feed ¦lunit as described in Example 2 except that the tear strip ¦Iconsisted of 3 75 parts of Eudragit E 30 D and 0 30 parts of !~IMethocel 90 H G 100 (hydroxy~ropyl methyl cellulose).
- ¦The washing tests were carried out at room temperature and further 1¦ under the same conditions as described in Example 1.
¦ITable VI gives the p~ values measured during the washing cycles after 5 and 15 minutes.
Table VI
I ~
l Number of washing cycles pH after 5 minutes pH after 15 minute l _ ~
25 l 1 q,3 10 4

5- 4 6 10 1 Il 10 4 7 10 ~

i' 15 4 7 10 2 ~ 20 _ _ _ 4 7 _ _10 1 5~
il , ~he relation bet~een pH of the wash liquor and time during the 1! 20th washing cycle is given in Table VII.

I Table VII

! .
1 Time in minutes pH .
i _ l 2 4,8 4 4,7 4,7 ~ 8 ~ 2 ,, 15 i:
Table VIII gives ~he incrus~tion values measured before starting the washing tests, and after the 10th and the 20th washiny cycles.

' Table VIII
i ,. Number of Percentage. incrustatlon in washinc~

i washing cycles napkins sheets bath towëls tea tow~ëls average !! ' ,_ . . ~ _____ _____ I
. 0 0,19 0,210,~1 0,2l 0,26 0,16 0,160,33 0,22 0,22 ! `20 0,10 0,100,38 o,16 0,19 . ~ .. --___ _ . . ~
, 1'The above data confirm the results described in Example 2.

IIExample 4 The bundle tests described in the Examples 2 and 3 were repeated, use being made of the same procedure with the ¦only exception that the acidic constituent was in the form of a .
.

I, .

i l.
Ilpowder and consisted of 18,3 grammes of fumaric acid, and 1,7 llgrammes of tallow fatty alcohol, 25 ethylene oxide. Table IX
I gives the pll values measured during the washing cycles both at a wash temperature of 55C and at room temperature.

I Table IX
!l _ I Number of Wash temperature. 55C Wash tem~era-ture: room temp_ washing p~l after ~1-1 after pH after pH after ,~ cycles - 5 min. 15 min. 5 min. 15 min.
1~ '-- _ _ i1 3,A 10,3 3,5 10,3 1 5 4,0 10,2 4,1 10,2 4,1 10,2 4,1 10,1 4,2 10,1 4,2 10,2 4,2 10,2 4,1 10,2 !: _ __ ___ ~
., 1 The relation between pH of the wash liquor and time during the 1! 20th washinc3 cycle is given in the following table X.
., Table X
! _ _ _ _ _ Time in minutes _pH (55 C~ pH (room temperature) i 4,2 4,2 -- - -1 4 ~,2 4,1 11 5 ~,2 4,~

6 10,1 10,2 8 10,2 10,2 10,2 10,2 . ..... ______ .___, IThe average incrustation figures measured before starting the Iwashiny tests, and after the 10-th and the 20th washing cycles arc given in the following table XI.

Il 1$1~5 ~, Table XI
I~ .
I' Number of Percentage incrustation in washing ~ washing cycles o _ _ __ _ _ _ ;1 55 C room temperature .~ _ _ __ _ 0 0,26 0,26 ,, 10 0,20 0,21 - 1 20 0,~5 0,22 i, __ ~,Example 5 I A feed unit according to the inven-tion comprised a ~non-woven sachet of 12x13 cm having only one compartment and I filled with 91,4 grammes of a detergent composition. The powdered acidic constituent had the same composition as the one in Example 2, and the alkaline constituent was formed in-to spherical particles of an average diameter of about 1 mm bv extruding ancl , I, marumerizing.
, These spherical particles were coated with 2,5~ by weiyht of Eudragit E 30 D and 10~ by weight of Eudragi-t L 30 D. The amount 1'f coating material was 9,4% kg weight, calculated Oll the total ¦~ amount of detergent composition.
1lA washing test was carried out under the conditions described in 1! Example 1.
The following table shows the relationship between pH and time during the first washing cycle. The wash liquor temperature was 55C.

I! , Il - 20 -3 ~ 5~

Table XII

,.time in minutes I -., 1 4,2 ~
~ 1. 2 ~,3 . ~ .
1 ~ 5,0 . :
i 4 6,5 . 5 9,0 ,! 6 lo,l l,i 8 10,2 1! 10 1 10,2 1. .
; ' After 10 and 20 wash cycles the average incrustat'on values were 0,23% and 0,28%, respectively.
The above data show that a satisfactory feed unit of the ~ detergent composition according to the invention can also be 15 ¦ obtained in the above~described way.

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Claims (10)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A feed unit of a detergent composition containing one or more surfactants, an alkali carbonate and an acid which forms water-soluble calcium salts and magnesium salts and/or complexes, and in which detergent composition the acidic constituent and the alkaline constituent are separately present, the acidic constituent having a higher rate of solubility in a wash liquor than the alkaline constituent, and the total amount of alkali being present in excess relative to the amount of acid, characterized in that the feed unit comprises a sachet which entirely or partly consists of a material which is permeable to or disintegrates in water and is filled with the acidic and the alkaline constituent, the acidic constituent containing 5-30 per cent by weight, calculated on the total amount of detergent composition, of one or more acids having a pK1 value in the range of 2,8 to 4,8.

2. A feed unit according to claim 1, characterized in that the sachet entirely or partly consists of a non-woven material.

3. A feed unit according to claim 1, characterized in that the sachet has 2 compartments and the acidic constituent:
is contained in the one and the alkaline constituent in the other compartment.

4. A feed unit according to claim 3, characterized in that the compartiment containing the alkaline constituent partly or entirely consists of a material which becomes permeable to water or disintegrates in it only after at least 2 and at most 10 minutes.

5. A feed unit according to claim 4, characterized in that the compartment containing the alkaline constituent entirely or partly consists of a material which becomes permeable to water or disintegrates in it only after at least 3 and at most 6 minutes.

6. A feed unit according to claim 5, characterized in that the compartment in which the alkaline constituent is present entirely or partly consists of polymers or copolymers of methacrylic acid and/or methacrylic esters.

7. A feed unit according to claim 5 or 6, characterize in that the compartment containing the alkaline constituent partly consists of hydroxypropyl methyl cellulose.

8. A feed unit according to claim 3, characterized in that the compartment containing the alkaline constituent is provided with one or more seams which open in water after at least 2 and at most 10 minutes.

9. A feed unit according to claim 8 characterized in that the compartment containing the alkaline constituent is provided with one or more seams which open in water after at least 3 and at most 6 minutes.

10. A feed unit according to claim 8, characterized in that one or more seams are partly or entirely filled with a mixture containing polyethylene glycol and one or more thermoplastic resins.