DE2423466B2 - ENCAPSULATED BLEACHING AGENT BASED ON ORGANIC PERSACID - Google Patents

Description

Encapsulated peracid bleaching agents are known. So is z. B. in US-PS 34 94 787 a dry Composition described, which has a core of f> 5 Contains perphthalic acid, which turns into a hydrated water-soluble salt, which is the water of hydration . Loses below 150 ° C, is encapsulated. This composition has proven to be advanced since the coating protects the perphthalic acid against decomposition caused by alkaline materials, ie usually found in detergents, is produced. In addition, this agent has the advantage that e acts as a heat consumer because it releases its water of hydration at elevated temperatures thereby preventing a detonation of the peracid proven to be a very effective bleaching agent in warm water, which dissolves quickly and easily in the dissolves warm water and thus can quickly release its active oxygen. But it has al proved disadvantageous that this composition ii cold water is not as effective as much Dissolve organic peracids in cold water only relatively slowly. This low resolution speed The use of the composition is particularly important in: a temperature of 20 ° C or lower is a common washing medium. The difficulty touches on the part also from the fact that the automatic washing machines NEN in their set program only one allow a limited period of time for the washing and bleaching stages. If the bleach is too slow dissolves, as a result, an insufficient! Period of time available to be in touch with mi Adequate amounts of dissolved bleach and active oxygen are available for dirty laundry place. A second undesirable feature of the slow dissolution of the peracid is that C local high concentrations of the bleaching agent can occur due to the fact that solid particles in the folds of the Textile material can become trapped, causing local over-bleaching and bleaching White spots appear on colored materials.

There is therefore a need to increase the rate of dissolution of organic peracids in bleach. In addition, the acid should be in a form in which it can withstand materials that make your Can cause decomposition is protected. Because the peracid in a bleach is usually with alkaline detergents is combined and since alkaline detergents the decomposition of the peracid It is an object of the invention to produce the peracid in a bleach in a fast dissolvable form available, but with a contact between the peracid and the Avoid detergents.

This object is achieved according to the invention by an encapsulated bleaching agent based on an organic Peracid dissolved, the bleaching agent being characterized in that the core consists of particles of a solid organic peracid mixed with particles of one in water better than the organic peracid soluble dispersant from a hydrated and / or a non-hydrated salt, or from an acidic or weakly basic agent that promotes the action of detergents, and that the core is encapsulated in a water-dispersible material made from a hydrated salt, optionally in combination with a non-hydrated salt, from a non-hydrated salt in Combination with a binder that forms a gel on contact with water, or one in water dispersible organic material.

In a preferred embodiment of the invention

dung contain either the core or the encapsulating material is a hydrated salt which retains the water of hydration below 3O ⁰ C, but at least a portion emits its water of hydration below the decomposition temperature of the peracid, wherein the hydrated salt is present in an amount to provide at least 0.1 part by weight of To provide water of hydration to 1 part by weight of organic peracid.

Particularly preferred are bleaches in which the hydrated salt is present in an amount sufficient to provide at least 0.25 parts by weight of water of hydration per part by weight of peracid. From hydrated salts, those which give off at least part of their hydration water below 150 ^° C., preferably below 120 ^° C., can be used.

Organic peracids containing greater than 3 weight percent active oxygen are in the invention preferred. The organic peracids can be aliphatic, alicyclic and aromatic peracids. Examples of such acids are diperadipic acid, diperaze'ainic acid, cydohexyldipercarboxylic acid, cycloheptyldipercarboxylic acid, Cyclooctyldipercarboxylic acid, perbenzoic acid, para-nitroperbenzoic acid and meta-chloroperbenzoic acid. Typical perphthalic acids are mono- and diperphthalic acid, per-isophthalic acid and Perterephthalic acid, among these acids diperisophthalic acid is preferred. The formulation according to the present invention is in particular then of Meaning if the peracid is only sparingly soluble in water, d. H. less than about 1 weight percent and preferably less than about 1/2 weight percent.

In the invention, the organic acid is combined with a dispersant which is in water is more soluble than the peracid. Advantageously, these two components become uniform mixed. The core then has the form of a matrix of peracid particles in which the particles of the dispersant are dispersed. Particularly suitable dispersants are those compounds which are used in Water at 15 ° C have a solubility of at least 1 g per 100 g of water. Those are preferred Compounds of which 2 to 200 g dissolve in 100 g of water at 15 ° C. and particularly preferably those Compounds with a solubility of 4 to 200 g per 100 g of water at 15 ° C. The core of the bleach, the formed by the peracid and the dispersant contains 1 in a preferred embodiment up to 90 wt .-% dispersant, which at 15 ° C in water has a solubility of at least 1 g per 100 g of water. Preference is given to 2 to 75 in the core, especially 5 to 60% dispersant is present.

The core containing the peracid and the dispersant is in a water dispersible substance encapsulated, which in the absence of free water prevents the core from coming into contact with substances contained in the Are able to bring about the decomposition of the peracid. As encapsulation materials can be with good Use hydrated salts, as disclosed in the aforementioned US Pat. No. 3,494,787. When such a hydrated salt is used to encapsulate the peracid core, it combines Water of hydration with that of the hydrated salt in the core and thereby gives the Total amount of water of hydration available. The total amount of water of hydration in the bleach including the core and encapsulation material is at least 0.1 and preferably more than 0.25 part by weight per part by weight of peracid, the total amount of water of hydration being up to 5 parts by weight per part by weight of peracid can increase. Examples of hydrated salts that can be used as both encapsulating materials and dispersants can be used in the core are the hydrates of sodium acetate, monobasic sodium phosphate, dibasic sodium phosphate, sodium sulfate, sodium potassium tartrate, acid sodium tartrate,

ig magnesium acetate, magnesium ammonium sulfate, aluminum nitrate, aluminum sulfate, aluminum magnesium nitrate, Potassium benzoate, magnesium sulfate, potassium magnesium sulfate and sodium aluminum sulfate. Others hydrated Salts that keep their water of hydration below 30 ° C, but at least partially below 150 ° C are also suitable.

Non-hydratable salts can be used as both dispersants and encapsulating materials be used. Suitable non-hydratable

; o Salts are e.g. B. potassium sulfate, acid potassium sulfate, Potassium dihydrogen phosphate, potassium acid phthalate, sodium nitrate and ammonium acid sulfate. Normally a non-hydratable salt is used in combination with a hydrated salt to produce a To have composition that can give off hydratable water. The hydrated salt can with mixed with the non-hydratable salt either in the core or in the encapsulation. Alternatively, a non-hydrated salt can be combined with the organic peracid in the core and become a hydrated Salt can be used as a coating material.

In another variation of the invention, a hydrated salt can act as a dispersant in the core and a non-hydrated salt can be used as an encapsulating material. If a non-hydrated Salt used as an encapsulation material is usually a binder that is capable of the Contact with water to form a gel, combined with the salt. Obtained by using the binder a better cohesive coating than with the salt alone. Binders that are used with the Encapsulation salt used can be mixed to make a better cohesive coating to result are z. B. Magnesium aluminum silicate, polyvinyl alcohol, soluble starch, hydroxypropyl cellulose, Hydroxyethyl cellulose, polyvinyl pyrrolides, casein, zein and agar-agar.

In another embodiment of the invention, the peracid core is dispersed in water with one encapsulated organic material such as polyvinyl alcohol, soluble starch, gelatin or carboxymethyl cellulose. Such encapsulation is normally achieved by sealing the core parts with the encapsulates organic material in a liquid state, such as By spraying or immersing the particles into the liquid.

As a dispersant can be an acidic or weakly basic agent, which has the effect of detergents promotes, be used. Examples of such

Bo substances that are compatible with the organic peracid are citric acid, mellitic acid, pyrromellitic acid, maleic acid, diglycolic acid, oxydisuccinic acid, nitrilotriacetic acid, ethylenediaminetetraacetic acid, polyacrylic acid, cyclopentane-1,2,3,4-tetracarboxylic acid and

('5 Tetrahydrofuran-2,3,4,5-tetracarboxylic acid. In combination With the peracid bleaching, these compounds fulfill a double task, as they on the one hand the Increase the dissolution rate of the peracid and

on the other hand, trap ions that cause hardness in the washing solution.

Examples of other organic acids that can be used as dispersants are Oxalic acid, malic acid, 1,3-cyclobutenedicarboxylic acid, Glutaric acid, maleic acid and malonic acid.

Among the dispersants which can be used in the invention, preference is given to those in water of 15 ° C have a solubility of more than 1 wt .-%, are compatible with the peracid and their 1% aqueous solution has a pH in the range from 2 to 8

Double salts can also be used as dispersants. Such double salts can be obtained by adding two salts to the peracid slurry in proportions suitable for the formation of the double salt. This embodiment is advantageous when the double salt has desired properties which neither of the two individual salts has. So is z. B. Na ₂ Mg (SO ^ ₂ · 4 H2O a double salt, which is obtained in the core by slurrying peracid _{particles with Na 2} SO ₄ and MgSO ₄ in a ratio of 10: 1, a particularly advantageous dispersant. The double salt contains water of hydration, which as The double salt is preferred over Na ₂ SO ₄ because it forms smaller crystals that can be distributed more evenly in the peracid particles.

The core particles can be prepared by dissolving the dispersant in an aqueous slurry of the peracid or mixing it with such a slurry. After the addition of the dispersant, the mixture is usually worked through well to achieve an even distribution of the dispersant and peracid. After mixing, the slurry is converted into core particles. One method of making cores is to thin the slurry and freeze it. The frozen layer is then broken up into particles of the desired sizes. An alternative method provides that hydrous solid peracid particles are produced by dividing the slurry of the peracid into fine particles. This can be accomplished by passing the slurry through a spray nozzle or an atomizer device to create liquid droplets. The liquid droplets can be cooled with an inert liquid coolant, such as. B. with liquid nitrogen, are brought into contact in order to solidify them. Other methods of producing the core particles are, for example, extrusion through a die and tableting. Depending on the thickness of the slurry, it is not necessary to freeze out the particles. However, frozen particles are easily handled as disclosed in US Pat. No. 3,622,366. The peracid particles are then contacted with fine particles of a material which contains the constituents of the composition for the protective overcoat. The encapsulation material is usually a hydratable salt or a non-hydratable salt in combination with a binder. During encapsulation with the hydratable salt, the salt is in an incompletely hydrated state, preferably in a substantially non-hydrated form, such that it is capable. To absorb water as water of hydration from the core particles. For example, magnesium sulfate or magnesium monohydrate can serve as the encapsulating salt, the coating then consisting of a hydrated magnesium sulfate containing 1 to 7 moles of water per mole of magnesium sulfate.
The core particles can be contacted with the encapsulation material in a static bed, but preferably the contact is made in a dynamic system. Ideally, the water-containing peracid particles are brought into contact with finely divided salt particles in a fluidized bed.

Suitable fluidizing agents for the generation of the Fluidized beds are inert gases such as nitrogen or air under these conditions. One proceeds in such a way that a Bed of a hydratable salt or a non-hydratable salt in combination with one Binder is suspended in an ascending stream of an inert gas. The core particles then become introduced into the upper part of the bed. Water present in the hydrous particles appears then in the coating as a hydrating agent if a hydratable salt is used as an encapsulating agent and as a gelling agent when a non-hydratable salt is in combination with a Binder is used as an encapsulation material. When the core particles are frozen, the Fluidizing gas temperature above 0 ° C.

Hydratable organic compounds are produced in a manner similar to hydratable inorganic ones Salts and non-hydratable organic compounds are applied to the core as non-hydratable inorganic salts applied.

The dispersant and the salt used for coating can be the same compound.

In this case, encapsulated particles of peracid can be used for the specific purpose either are large or too small can be reused in an economical manner for the manufacture of the cores. this is achieved by re-slurrying too large and too small particles and from that slurry produces core particles in the manner already indicated. These core particles that are already the dispersant contain, d. H. the material that has previously formed the encapsulation material can with a Protective coating to be encapsulated again.

The encapsulated cores are essentially

-is spherical and preferably have a diameter from 0.1 to 5 nm, in particular from 0.2 to 2 mm. The protective sheath or encapsulation usually has one mean thickness of at least 0.05 mm and preferably from 0.1 to 1.0 mm. The core preferably has

such a diameter of 0.05 to 5 mm. The dispersant, which is embedded in the matrix of the peracid, generally has a particle size of 0.001 to 1 mm, preferably 0.005 to 0.5 mm.
In the invention, encapsulated cores with

a complete and continuous encapsulation shell preferred, but products that are less perfect but essentially complete are also useful are encapsulated. Such products can also be mixed with synthetic alkaline detergents without

that there is an undesirable decomposition of the peracid

The invention is explained in more detail in the following examples

B e i s ρ i e 1 1

Slurries of diperisophthalic acid that contain less than 5% isophthalic acid are made by using that as a dispersant too

(ο

using salt dissolves in a sufficient amount of deionized water so that the desired Concentration of the salt is present when the solution is slurried with the moist cake of diperisophthalic acid will. The slurries obtained are homogenized in an electric mixer, formed into thin layers between polyethylene foils and quickly frozen out with dry ice. The frozen layers are broken up, crushed and sieved out as frozen kernels Particle sizes from -18 to +70 mesh.

An encapsulation material is made by mixing Na ₂ SO ₄ and MgSO ₄ · 1 H ₂ O in ratios of 1: 1 to 9: 1. The frozen core particles are encapsulated by contacting them with the salt particles in a heated fluidized bed 7.5 cm in diameter. Hot air is used as the fluidizing agent, the temperature of which is selected so that a temperature of 40 to 45 ° C. is maintained. After a residence time of about 15 minutes, the contents of the fluidized bed are sieved on a sieve device with sieves with a diameter of 20 cm for 2 minutes with a load of about 250 g. A product is obtained with particle sizes in the range from -14 to +60 mesh. Subsequently, the dissolution rate of these samples at 50 ⁰ C and 2O ⁰ C is determined and compared to the dissolution rate of diperisophthalic acid that has been encapsulated with no dispersant.

Table I.

Comparison of the dissolution rates of encapsulated diperisohthalic acid with and without additives in the core

The dissolution rates are as follows certainly:

A simulated washing solution is prepared by dissolving 0.15% by weight of a common household detergent in tap water. For each Tesi, a 250 ml portion is given in a 400 ml beaker, the beaker being placed on a hot plate mi! set temperature or in a cooling bath with set temperature. A magnetic bar is used to stir at a constant speed. Sufficient encapsulated diperisophthalic acid is added to make a solution containing 60 ppm active oxygen with stirring for a given passage space. At the end of the stirring period, all of the solution is quickly filtered through a Buchner funnel into a flask containing _{approximately 250 ml of 4.3% H-SO 4.} The damp filter paper and any residue left behind are placed in another flask containing the same amount of isopropanol and. Contains 4.3% H ₂ SO ₄ to dissolve any solids present. The diperisophthalic acid is then determined in both solutions by titration with an Na2S ₂ O3 solution. The operation is repeated for each of several time periods at 50 ⁰ C and 20 "C. In the table, the dissolution rates of encapsulated diperisophthalic acid with and without the presence of additives in the cores are collected.

Dispersants composition 1
) DPI ² ) in % on encapsulated product Na ₂ SO ₄ , H) O Resolution speed ir Detergent solution stir 60 1 solved 0.15% Sec. at the core 13th in the cover Lö- 30th 57 Disper IPS ³ sensational % added DPI Sec. 17th 120 greed 26.9 ) MgSO ₄ 0 26.3 tempe- after 13th 66 Sec. middle rature 37 96 20th 14.4 0 24.2 C. 14th 99 85 15th 46 29 None 0 17.5 1.5 37.7 13.8 20th Sec. 94 98 90 45.2 50 - 99 - 98 None 0 0.8 20th - 97 100 9.8 60.6 53.2 9.7 50 - 96 100 Na ₂ SO ₄ 4.9 1.0 20th - 99 98 98 9.0 25.1 49.2 13.4 50 88 81 100 - Na ^ SO ₄ + 2.0 98 100 96 98 MgSO ₄ · 6 H ₂ O 1.9 8.5 0.5 52.8 10.8 20th 95 100 100 22.8 50 95 100 97 98 Na ₃ C ₆ H ₅ O ₇ · 2 H ₂ O 3.2 9.3 0.5 49.5 13.1 20th 97 92 100 100 24.7 50 74 99 99 100 NaH ₂ PO ₄ • H ₂ C 3.0 9.1 0.5 50.7 12.4 20th 99 94 100 98 24.4 50 80 99 98 NaHSO ₄ · H ₂ O 3.2 9.1 0.5 50.5 13.0 20th 99 98 98 100 24.4 50 87 99 99 99 KHSO ₄ 2.8 0.5 20th 99 iOO 9.7 24.5 49.8 11.4 50 87 97 K ₂ SO ₄ 2.8 0.5 20th 99 99 99 24.1 50 97 99 Na ₂ SC ₄ + 1.5 99 709 526/468 MgSO ₄ · _{6H 2} O 2.8 0.5 20th 24.2 50 94 99

9 composition DPI ^:) 24 23 466 ) ₄ Na ₂ SO ₄ H ₂ O Ϊ Detergent solution stir 60 solved Γ ίο Sec. continuation Together ) Dispersants in% 30th 99 at the core ' % added DPI Sec. 99 120 after Sec. Disper 9.5 encapsulated product 51.7 12.1 98 98 greed IPS ³ ) 99 100 99 middle 15th 98 100 9.0 in the cover 53.0 11.2 Sec. 98 99 99 84 98 1.0 12.8 MgSC 41.3 12.0 95 97 100 100 Na ₃ SO ₄ + 0.9 Dissolution rate in 98 99 99 MgSO ₄ 6 H ₂ O 17.0 0.5 0 24.2 0.15% 83 100 0.7 94 99 90 Na ₁ SO ₄ + 1.3 Lo- 98 100 MgSO ₄ 6H ₂ O 0.5 sensational 94 7.9 24.3 tempe- 99 Na ₂ SO ₄ 0.7 rature 84 9.3 C. 96 MgSO ₄ · _{6H 2} O 0.9 24.3 25.3 20th 50 48.6 20th 50 20th 50 20th 50

It is assumed that all of the dispersant has remained in the core and that after encapsulation no free:

Water, but only water of hydration is present in the core. ■) DP! = Diperisophthalic acid.
') IPS - isophthalic acid.

Example 2

Two encapsulated diperisophthalic acid bleaching agents for test purposes are prepared in a manner similar to Example 1. Sample A consists of capsules with cores of diperisophthalic acid which make up 26.9% by weight of the capsules. The kernels also contain isophthalic acid, which makes up 1.8% of the capsules. These cores are coated with a coating mass of MgSO ₄ and H ₂ O, this mass corresponding to 45.2 or 26.1% by weight of the capsules. Sample B is prepared in a similar manner, but the cores contain MgSO ₄ · 6 H ₂ O, diperisophthalic acid and isophthalic acid in proportions of 9.5% by weight, 17.3% by weight and 0.8% by weight. based on the weight of the capsules. The cores of the capsules B are coated with a coating mass of MgSO ₄ , Na ₂ SO * and H ₂ O in proportions of 20.7% by weight, 39.1% by weight and 12.6% by weight, based on the weight of the capsules, encapsulated.

Ordinary city tap water containing 0.15% of a commercially available detergent is used to determine the dissolution rates. For jedt test, a 250 ml portion of the test solution in a 400 ml beaker is added and the temperature is adjusted to 2 (or 50 ⁰ C. Is stirred with a magnetic stir bar.

Add enough ar-encapsulated diperisophthalic acid to the beaker to make a solution with 60 ppm active oxygen, given and the contents of the beaker for the intended purpose touched. The amount of diperisophthalic acid dissolved in a given period of time is as in Example 1 certainly.

The relative rates of dissolution of the diperisophthalic acid alone and the diperisophthalic acid with the dispersant are plotted graphically in the drawing. From the drawing, it is apparent that the diperisophthalic ;, containing a dispersant, to be dissolves much faster even at 50 ⁰ C as the D'iperisophthalsäure both at 20 without addition of a dispersant.

1 sheet of drawings

Claims (9)

Claim ;: 1. Encapsulated bleaching agent based on an organic peracid, characterized in that the core consists of particles of a solid organic peracid mixed with particles of a dispersant which is more soluble in water than the organic peracid and consists of a hydrated and / or a non-hydrated ι ο based salt, or from an acidic or weakly basic agent, which promotes the action of detergents, composed and that the core is encapsulated in a water-dispersible material, which consists of a hydrated salt, optionally in combination with a non-hydrated salt , of a non-hydrated salt in combination with a binder which forms a gel on contact with water, or of a water-dispersible organic material iu 2. Bleaching agent according to claim 1, characterized in that the core or the encapsulation material contains a hydrated salt which ^{retains the water of hydration below 30 0} C, but releases at least part of the water of hydration below 150 ° C, the hydrated salt in a sufficient amount Amount is present to provide at least 0.1 part by weight of water of hydration to 1 part by weight of organic peracid available. 3. bleach according to claim 2, characterized in that the hydrated salt in one sufficient amount is present to include at least 0.25 parts by weight of water of hydration to 1 part by weight To provide peracid. 4. bleach according to claims 1 to 3, characterized in that the peracid is more than Contains 3% by weight of active oxygen. 5. Bleaching agent according to Claims 1 to 4, characterized in that the peracid is diperisophthalic acid is. 6. bleach according to claims 1 to 5, characterized in that the core 1 to 90 Contains% by weight dispersant which has a solubility of at least 1 g in water at 15 ° C 100 g of water. 7. bleach according to claims 1 to 6, characterized in that the dispersant in Water of 15 ° C. has a solubility: of more than 1% by weight and that its i% aqueous Solution has a pH in the range of 2 to 8. 8. Bleaching agent according to Claims 1 to 7, characterized in that it contains Na2Mg (SO4) ₂ as a dispersant in hydrated or non-hydrated form. 9. bleach according to claims 1 to 8, characterized in that the encapsulated Core is spherical and has a diameter in the range of 0.1 to 5 mm.