CA2039891A1 - Stable peroxycarboxylic acid granules - Google Patents

Abstract

Abstract of the disclosure:

Stable peroxycarboxylic acid granules Stable peroxycarboxylic acid granules composed essentially of (1) an imidoperoxycarboxylic arid or its salts of the formula in which A is a group of the formula , , or n is the number 0, 1 or 2, R1 is hydrogen, chlorine, bromine, C1-C20-alkyl, C1-C20-alkenyl, aryl or alkylaryl, R2 is hydrogen, chlorine, bromine or a group of the formula -SO3M, -CO2M or -OSO3M, M is hydrogen, an alkali metal or ammonium ion or the equivalent of an alkaline earth metal ion, and X is Cl-Cla-alkylene or arylene/
(2) an inorganic sulfate and/or phosphate salt and/or a non-oxidizable surfactant as granulating auxiliaries and (3) a homo- or copolymer of (meth)acrylic acid or its salts or a copolymer of (meth)acrylic acid or its salts and other carboxylic acids polymerizable therewith as a film-forming coating substance.

Description

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HOEOEIST AKTIENGESELLSCHAFT HOE 90/F 107 Dr.GT/gm DQ~cription Stable peroxycarboxylic acid granules The present invention rela~es to storage-stable, high-percentage bleach active compounds in granulated form, which contain ~olid imidoperoxycarboxylic acids as bleaching components. The granules according to the invention can be employed as bleaching additives or oxidants in detergents, cleaning agents and 1~ disinfectants.

Inorganic persalts such as sodium perborate or percar-bonates are long-known as bleaching agent additives in detergents. However, they display their optimum bleaching power only at temperatures above 60C. For their activa-~5 tion, a number of organic compounds are described which,during the washing process, release a peroxycarboxylic acid with hydrogen peroxide. This has a bleaching effect e~en at temperatures below 60 DC . ThP best-known example of these is tetraacetylethylenediamine ~TAED).

Additionally, however, more recently a number of peroxy-carboxylic acids for direct use in detergents have been described.
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However, a problem both with the activators and with the previously prepared peroxycarboxylic acids is their low storage stability in alkaline detergent formulations. An adequate storage stability can only be achieved with these substances by a suitable granulating or coating process.

Known granulating auxiliaries for the most frequently used persalt activator tetraacetylethylenediamine are, for example, carboxymethylcellulose or ethoxylates of longer-chain alcohols.

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~ore reactive persalt activators such as phthalic anhydride, on the other hand, require a more effective protection. Thus, to prépare storage-stable granules, previously prepared activator granules, composed of phthalic anhydride and a car:rier material, are coated with a coating material composed of polymeric organic compounds such as polyacrylamide, copolymers of acrylic acid, methacrylic acid or maleic anhydride, or starch or cellulose ethers ~US 4,009,113).

The stabilization of o~her sensitive detergent components (en~ymes or percarbonates) by coating with polymeric materials meanwhile belongs to the prior art.

A particular problem, however, even nowadays is still the stabilization of reactive peroxycarboxylic acid~. In the presence of basic detergent constituents, perfumes and ~nzymes, redox reactions easily occur with the loss of active oxygen. In addition, oxidation reactions can ~exy easily occur in which valuable detergent components such as perfumes or enzymes are destroyed by oxidation.

A number of proposals have been made to solve the -~ problem.

Thus, EP 200,163 describes granules Gf uniform com-position, comprising 3-50% of an aliphatic perosycax-boxylic acid, 40-95% of a hydratable inorganic salt and 0.2-10% of an organic polymer compound such as poly-acrylic acid.

Granules having a particle size of 0.5 to 2 mm, composed of 20~65~ of a pero~ycarboxylic acid, 30-79.5~ of an inorganic salt and 0.5-6.5% of a polymeric acid ~s a binder are described in EP 256,443. The product can be coated with a coating material in an additional reaction step and can thus be protec-ted from reactions with oxidizable detergent constituen~s.

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Analogous granules and their preparation are described in EP 272,402. In this case, previously prepared peroxycar--boxylic acid granules are sprayed while agitating with an aqueous solution of a homo- or copolymer, which i6 soluble in alkaline medium, of an unsaturated organic carboxylic acid containing 3-6 carbon atoms and the mixture is simultaneously or subsequently dried.
Preferred previously prepared granules are composed of 3-50, in particular 7-20%, of a peroxycarboxylic acid, n,~-di-perdodecanoic acid, for its part, being preferred.

Granules composed of solid, preferably aliphatic, peroxy carboxylic acid particles which are coated with ~urface~
active substances have add.itionally been described - (German Offenlegungsschrift 2,737,864). To control an exothermic decomposition reaction, the coated peroxycar-boxylic acid particles can also be combined with inorganic sulfates. Moreover, in order to protect the granules further, an additional coating of the granule core with acid-, ester-, ether- or hydrocarbon-containing substances can be carried out. These materials help in preventing moisture from reaching the peroxycarboxylic acid particles.

Patent Applications EP 200,163 and EP 272,402 particu-larly emphasize that the experience which has been obtained with one type of peroxycarboxylic acid can only ; rarely be transferred to another type. OptLmum granules can therefore only be obtained ~y measures which are tailored to the particular type of peroxycarboxylic acid.
Thus, it is known, for example, from US 3,639,285 that surfactants favor the decomposition of peroxycarboxylic acids, whereas in German Offenlegungsschrift 2,737,864, they can be employed without problems as granulating auxiliaries.

In most of the granules described hitherto, ~ di-perdodecanoic acid (DPDDA) is employed as the organicperacid. Because of its thermal instability, it can only - 4 - ~03~
be converted in desensitized ~orm into storage-stable granules having a content up to 30~.

Storage-stable granules of more reactive peracids having active contents of above 60% have hardly been described hitherto and place high demands on ~he granulating technique.

Using the imidoperoxycarboxy:Lic acids ~EP 325,288 and 349,940), a group of peroxycarboxylic acids was developed which have a distinctly higher oxidizing and bleaching power than ~ di-pexdodecanoic acid. Economically and in terms of application technology, e-phthalimidoper caproic acid (PAP) is of particular interest.

It was the aim of the present invention to convert this class of compounds into suitable storage-stable granules having active contents of at least 60%.

The object is achieved by agglomerating the ~midoperoxy-carboxylic acid with a granulating auxiliary in a mixer and then coating the agglomerate with a film-forming agent. The use of agents for the thermal stabilization of the peracid can be dispensed with in this case.

The invention therefore relates to storage-stable peroxy-carboxylic acid granules, composed essentially of an imidopero~ycarboxylic acid or its salts of the formula o A / \ N - X ~ OOM
~C/
o in which A is a group of the formula 2~3~8~
~ - 5 -R
R \ / 2 R1 R2 or o N-X-C-OOM
C/
o n is the number 0, 1 or 2, Rl is hydrogen, chlorine, bromine, Cl-C20-alkyl, Cl~C20-alkenyl, aryl, preferably phenyl, or alkylaryl, preferably Cl-C4-alkylphenyl, R2 is hydrogen, chlorine, bromine or a group of the formula -SO3N, -C02M or -OSO3N, M is hydrogen, an alkali metal or ammonium ion or the equivalent of an alkaline earth metal ion, and 0 X is Cl-Cl9-, preferably C3-Cll-alkylene, or arylene, preferably phenylene, an inorganic sulfate and/or phosphate salt and/or a non-oxidizable surfactant as granulating auxiliaries and a homo- or copol~mer of ~meth)acrylic acid or its salts or a copolymer of (meth)acrylic acid or its salts and other organic carboxylic acids polymeri~able therewith a~ a film-forming coating substance~

The three essential components of the bleaching agent according to the invention are therefore a peroxycar~
boxylic acid from the i~idopero~ycarboxylic acid group, a granulating auxiliary and the coating agent. These are described, together with components to be used alterna-ti~ely, in t:he following.

2~3~g:~

The p~roxycarboxylic aoid Suitable peroxycarboxylic acids are the imidoperoxycar-- boxylic acids of the abovementioned formula. Preferred compounds of this formula are those in which R

A is a group of the formula -CH2-(CH2)D-CH2- or -CH2-CHRl-, n is the number 0 or 1, Rl is hydrogen, Cl-C20-alkyl or Cl-C20-alkenyl, R2 is hydrogen ox CO2M
X is C3-Cl1-alkylene and M is hydrogen, an alkali metal or ammonium ion or the equivalent of an alkaline earth metal ion.

Examples of preferred compounds of ~his type, which are employed in the granules according to the invention, are ~-phthalimidoperoxyhexanoic acid (PAP), ~-~dodecylsuc-cinimido] peroxyhexanoic acid, ~-phthalLmidoperoxybutyric acid and ~-trimellitimidoperoxyhexanoic acid, their salts or their mixtures.

~he imidoperoxycarboxylic acids can be prepared, for example, according to EP-349,940, for example by reaction of an anhydride of the formula / \
\ C
o with amino acids of the formula o H2N - X - ~ - OE
and oxidation of the imidocarboxylic acid obtained in this way with hydrogen peroxide in the presence of a strong acid. According to one variant of this process~
the anhydride can also be reacted under pressure with a lactam in the presence o~ water.

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The concentration of these peracids in the granules i5 at least 60, preferably 65-90~.

The imidoperoxycarboxylic acids employed for granulation are normally solids at room temperature having a melting point of above 60C. ~hey can be employed for granulation in powder form, and in the dry or moist state.

l'he granulating a~xiliary The granulating auxiliaries halve the object of forming a mechanically stable granuls core and thus the basic L0 structure of the actual granules by agglomeration with the peroxycarboxylic acid.

The granulating auxiliaries to be used according to the invention can be divided into two groups: a) inorganic sulfates and/or phosphates and b) organic compounds having surface-active properties (surfactants). ~he assumption is that these substances cannot be oxidized by the peracid.

Suitable inorganic sulfates/phosphates for the granules are sulfates/phosphates of alkali metals or alkaline earth metals, which are easily water-soluble and after dissolution have a neutral or acidic reaction. Sodium sulfate, sodium hydrogen sulfate, potassium sulfate, potassium hydrogen sulfate, sodium dihydrogen phosphate or magnesium sulfate are preferably used. Mixtures of the salts can additionally be employed.

Water-soluble anionic sulfates or sulfonates or zwit-terionic surfactants are preferably employed as surface-active substances. Examples of compounds of this type are alkali meta:L or alkaline earth metal salts of alkyl-sulfates or -sulfonates having an alkyl group of 9 to 22 carbon atoms, which are obtained from natural or syn-thetically prepared fatty alcohols, or from hydrocarbons such as, for example, paraffin. Other useful surfactants 2~3~

which can be used are salts of alkylbenzenesulfonates in - which the alkyl group contains 9 to 22 carbon atoms and can be branched or unbranched. All ~aid compounds can optionally carry ethoxylated groups in the molecule.
Preferred compounds are sec. alkanesulfonates, (Hostapur~SAS),alkylsulfatesandalkylbenzene-sulfonates.

The substances can be employed in solid or pasty form or as a solution for granulation. The preferred solvent is in this case water.

Mixtures of the granulating auxiliaries of group a) can be employed in any ratio with those of group b) for the granulation.

The amount of the granulation auxiliary in the finished granules is 5 to 39, preferably 15 to 35% by weight.

The film-forming coating s~bstance Polymers of (meth)acrylic acid or copol~mers of these acids with other unsaturated organic caxboxylic acids are used as a film-forming coating substance. These compounds can also be employed in partly neu~ralized form. It is Lmportant, however, that the pH of the compounds is or is adjusted to between 2.5 and 7. Possible polymers are, for example, polyacrylic acid, polymethacrylic acid and copolymers of acrylic acid or methacrylic acid with maleic acid, fumaric acid or itaconic acidO The Gompounds have an average molecular weight of 800~2,000,000 preferably 2,000-500,000.

The polymeric film-forming agents are preferably applied to the granule cor~ in aqueous solution. Their concen-tration in the solution is 5-50%, preferably 10-30~.

The amount of the film-forming substance in the granule is l to 15, preferably 3-12%.

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- g :, ~dditional components In some cases, it may bé desirable that the granules - according to the invention contain certain additional components. Examples of these are chelate-forming systems~ dyes and agents for xegula~ing the pH.
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It is known that metal ions are capable of catalytically decomposing organic or inorganic percompounds. To overcome this problem, up to 3% of a chelating agent can be added to the granules. Preferred compounds are inorganic or organic phosphates or phosphonates or aminomethylenecarboxylic acids. ~xamples of these are ethylenediaminetetramethylenephosphonic or -carboxylic acids or diethylenetriaminepen~amethylenephosphonic acid or their salts.

Agents for adjusting the pH are employed for changing or maintaining the pH within the granules. Examples of these are citric acid, fatty acids or succinic acid or salts such as silicates, phosphates or sodium bisulfate.

PrepAration The imidoperoxycarboxylic acid and the granulating auxiliaries of the type a) and/or b) are mixed in a first step such that suitable granules are formed by agglomeration. This can be carried out in a kneader or mixer. The use of a kneader is appropriate wherever, owing to addition of a pasty granulating auxiliary, intensive mechanical mixing is nece~sary. If the mixing ; is carried out in a kneader, for example a Brabender kneader, it has proved advantageous also to additionally compress the material obtained in a granulator, for example a Eirich granulator. If inorganic, hydratable salts are used as granulating auxiliaries, it is advan-tageous to employ the imidoperoxycarboxylic acid with a water content of 50 to S, preferably 35-20%. In this case, mixing can be carried out, for example, in a - 10- 20~98~:~
plowshare mixer from Lodige. The granules thus obtained require no ~urther compaction after their drying. Cus-tomarily, granules having a granule size of 0.5 to 2 mm are aimed at. This can be achieved by sieving the granules. The amount of usable granules is in general 80%. The amounts lying above or below this can be fed back into the granulation process.

In a second step, the aqueous solution of the film-forming coating substance is sprayed onto the imido-peroxycarboxylic acid granules prepared in this way. Inorder to obtain a coating which is as complete as pos-sible, the granules must be agitated during spraying. A
particularly preferred form is ~herefore spraying in a fluidized bed. In this case, the coated granules can be simultaneously dried by warming the fluidizing air. The spraying is carried out in such a way that further agglomeration is prevented. Granule size and granule size distribution are therefore only insignificantly influenced by the coating process. Chelating agents, dyes ~0 and agents for regulating the pH can additionally also be dissolved in the aqueous polymer solutisn. The coated granules still have to be dried, depending on the spray-ing process.

The granules according to the invention are white, free-flowing granules having a bulk density between 500 and 1,200 kg/m3, preferably between 550 and 1,100 Xg/m3.

Subsequent treatment, for example compression to give tablets or larger agglomerates, is possible and advan-tageous for particular application purposes.

Use The granules according to the invention can generally be used wherever the imidoperoxycarboxylic acids are used as oxidants, bleaching agents and disinfectants. In par-ticular, these granules can be employed in pulverulent ~ 1; 3 ~

detergents, cleaning agents and disinfectant~. A further preferred field of application is found in the hygiene sector, fox example as an additive to disinfectants or cleaning agents for hard surfaces, sanita~y cleaners, dental hygiene agents, or cleaning salts. The dissolution rate of ~he peroxycarboxylic acid is not influenced or only insignificantly influenced by granulation. At 20C, more than 70% of the available active oxygen for bleaching, oxidizing or disinfecting i9 available within 5 min. An effective action of the peracid is therefore achieved even at room temperature.

The granules can be formulated for this purpose with other solid active substances which are required in the corresponding field of application. In particular, it may be stressed that combinations with other bleaching agents such as persalts, persalt/activator systems or other peroxycarboxylic acids are al~o preferred in some cases~

Additional components which can be mentioned for use in detergents and cleaning agents are anionic, nonionic or cationic surfactants, builder systems on a zeolit0, layer silicate or phosphate basis, co-builders, optical brighteners and perfume substances.

Example 1 140 g of ~-phthalimidoperoxyhexanoic acid are kneaded at 100 revolutions per minute in a 0.3 1 Brabender kneader wi~h 47 g of sec. sodium alkanesulfonate (Hostapur~
SAS 60) for 5 minutes. The entire material from three kneader batches is then granulated at 900 revolutions per minute for 2 minutes in a 12 liter Eirich mi~er granu~
lator and subsequently dried in a vacuum drying oven at 40C to constant weight. Aftex sieving, 85~ of high-grade granules between 0.5 and 2.00 mm are obtained. 337 g of high-grade granules are initially introduced into a fluidized bed unit and fluidized by means of a stream of warm air at 40C flowing at about 50 m3/h. An aqueous 2~39~

25.3% strength polyacrylic acid solution (~ - 15,000 by GPC analysis), in which 0.24% of diethylenetriamine-pentamethylenepho6phonic acid (Dequest~ 2066 Mons~nto) is dissolved, is simultaneously sprayed on by means of a nozzle situated at the bottom. 176 g of polyacrylic acid solution are sprayed onto the agitated granules in the course of 36 minutes. ~fter d3~yiny in the vacuum drying oven at 40C, 351 g of coated granules having the follow-ing composition reæult. 69!~ of ~-phthalimidoperoxy-hexanoic acid (corresponding to an active oxygen contentof the granules of 3.98%), 18~ of secondary sodium alkanesulfonate (determined by two-phase titxakion according to Epton) and 11.8% of polyacrylic acid. The bulk density is 604 g/l.

Washing tests For the washing tests, ~-phthalimidoperoxyhexanoic acid (PAP) as a powder (contents. 96%) and the granules according to the invention in accordance with Example 1 above and also granules based on lauric acid w~re employed.

Granules 1: in accordance with Example 1: 69% PAP, 18~o Na alkanesulfonate, 11.8% polyacrylic acid Granules 2: PAP granules not according to the invention based on lauric acid The washing tests were carried out in a Launder-0-Meter using the test stains tea on cotton (WFK) and red wine on - cotton (EMPA, St. Gallen, CH). The water hardness was 15dH. 1.5 g/l of phosphate-free standard detergent (WFK~
were employed as a detergent. The amount of bleaching agent was selected such that theoretically 25 mg of active oxygen were available in each case per liter of washiny liquor. The washing temperature was 20C and the washing period 30 min.

The bleaching power was determined as the increase in 2039~9 ~

reflection of the various test fabrics. E~aluation was carried out in the usual way.
Reflection [%]
Tea Red wine 5Bleaching agent PAP powder 65.6 55.6 Granules 1 64.9 54.9 Granules 2 60.4 51.8 The washing results show tha~ the active oxygen-releasing ability of the peroxycarboxylic acid i8 only slightly influenced at low temperature by granulation according to the invention. Granules ~ not according to the invention, on the other hand, lead to distinctly poorer bleaching results because of reduced cold water solubility.

Storage tests Determination of ~he s~orage stability 100 mg each of the granules according to Example 1 were mixed with 900 mg of phosphate-free standard detergent and the mixture was stored in open glass bottles at 20C/60~ atmospheric humidity, 38C/30% atmospheric humidity and 38C/80% atmospheric humidity. After one week in each case, the active oxygen conten~ of an entire sample is determined and ~he result compared to the s~arting value.

Storage stability Degree of retention of the active oxygen in percent of the original content.
Storage period~weeks Condition 1 2 3 6 20C/60% RH 100 100 100 100 38C/30% RH 100 100 95 97 3~C/80% RE 97 87 55 20

Claims (10)

1. A stable peroxycarboxylic acid granule, composed essentially of an imidoperoxycarboxylic acid or its salts of the formula in which A is a group of the formula , or n is the number 0, 1 or 2, R1 is hydrogen, chlorine, bromine, C1-C20-alkyl, C1-C20-alkenyl, aryl, preferably phenyl, or alkylaryl, preferably C1-C4-alkylphenyl, R2 is hydrogen, chlorine, bromine or a group of the formula -SO3M, -CO2M or -OSO3M, M is hydrogen, an alkali metal or ammonium ion or the equivalent of an alkaline earth metal ion, and X is C1-C19-, preferably C3-C11-alkylene, or arylene, preferably phenylene, an inorganic sulfate and/or phosphate salt and/or a non-oxidizable surfactant as yranulating auxiliaries and a homo- or copolymer of units of acrylic acid, methacrylic acid and/or their salts and/or a copolymer of units of acrylic acid, methacrylic acid andtor their salts and other carboxylic acids polymerizable therewith as a film-forming coating substance.

2. A stable peroxycarboxylic acid granule as claimed in claim 1, wherein, as a peroxycarboxylic acid, a compound of the formula or its salts is employed, in which A is a group of the formula -CH2-(CH2)n-CH2-, -CH2-CHR1- or n is the number 0 or 1, R1 is hydrogen, C1-C20-alkyl or C1-C20-alkenyl, R2 is hydrogen or CO2M
X is C3-C11-alkylene and M is hydrogen, an alkali metal or ammonium ion or the equivalent of an alkaline earth metal ion.

3. A stable peroxycarboxylic acid granule as claimed in claim 1, wherein sodium sulfate and/or alkylbenzene sulfonate, alkanesulfonate or alkylsulfate are used as a granulating auxiliary.

4. A stable peroxycarboxylic acid granule as claimed in claim 1, wherein polyacrylic acid or copolymers of acrylic acid or methacrylic acid with maleic acid, fumaric acid or itaconic acid are employed as the polymeric coating substance.

5. A stable peroxycarboxylic acid granule as claimed in claim 1, wherein the amount of imidoperoxycarboxylic acid is at least 60%.

6. A stable peroxycarboxylic acid granule as claimed in claim 1, wherein the amount of the granulating auxiliary in the finished granule is 5 to 39, preferably 15 to 35%.

7. A stable peroxycarboxylic acid granule as claimed in claim 1, wherein the amount of polymeric coating sub-stance is 1 to 15%, preferably 3 to 12%.

8. A stable peroxycarboxylic acid granuie as claimed in claim 1, which additionally contains a non-polymeric chelate complex-forming substance to complex heavy metals.

9. The use of granules as claimed in claim 1 as bleach-ing agents, oxidants and disinfectants.

10. The use of granules as claimed in claim 1 in deter-gents, cleaning agents and disinfectants.