Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – With oxygen or halogen containing chemical bleach or oxidant...
Reexamination Certificate
2000-04-05
2001-07-03
Gupta, Yogendra (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
With oxygen or halogen containing chemical bleach or oxidant...
C252S186320, C008S111000
Reexamination Certificate
active
06255272
ABSTRACT:
The present invention relates to particles comprising a peroxy compound and an amino acid. The invention also relates to use of the particles and a composition containing such particles.
Powder detergent compositions often contain peroxy compounds as bleaching agents which release hydrogen peroxide or peroxy acids in aqueous solutions. However, many peroxy compounds are not storage stable. Their decomposition is supposed to be catalysed by metal cations moving comparatively freely through the water normally being present in detergents, but is also facilitated by the alkaline pH (normally from about 8 to about 12) and by other components commonly present in detergents, for example zeolites or bleaching activators such as TAED (tetraacetylethylene diamine), TAGU (tetraacetylglucoluril) or PAG (penta acetyl glucose).
In order to make environmental friendly detergents, it is desirable to use alkali metal carbonate peroxy hydrate, commonly known as percarbonate, as a bleaching agent. However, the activity of percarbonate in a detergent decreases rapidly through decomposition if the detergent is stored at normal room temperature and humidity.
Many attempts to stabilize percarbonate have been done, for example by mixing or coating with stabilizing substances such as sulfates, carbonates, borates, silicates or organic substances. Such stabilizing methods are described in the patent literature, for example in GB 1466799, GB 1538893, GB 1575792, EP 459625, U.S. Pat. No. 3,975,280 and EP 573731.
U.S. Pat. No. 5,362,412 discloses incorporating certain biodegradable amino compounds into detergent compositions in order to improve the bleaching. However, improvement of the storage stability of peroxy compounds is not dealt with.
WPI abstract 85-053698/09, abstract of JP-A-60011210, describes incorporation of aminoacids having less than two carboxyl groups and a polyphosphonic acid into percarbonate.
ES 407045 disclose a sodium percarbonate composition comprising a compound selected from e.g. certain amino acids.
The object of the present invention is to provide particles comprising a peroxy compound, particularly alkali metal percarbonate, with improved storage stability, particularly in detergent compositions. It is another object of the invention to provide particles comprising a peroxy compound only containing environmental friendly constituents.
Through the present invention, these objects has been fulfilled by providing particles comprising a peroxy compound with capability of releasing hydrogen peroxide or peroxy acids in aqueous solutions, the particles further comprising an amino acid selected from isoserine N,N-diacetic acid or an amino acid of the formula:
(HOOC—CH
2
)
2
N—C
n
H
m
COOH—R
in which R is H, CH
2
OH or CH
3
, n is 1, 2 or 3 and m is 0-2n; or a salt thereof.
Preferably n is 1 or 2 and most preferably m is n. In one preferred embodiment R is H, n is 2. In another preferred embodiment R is CH
2
OH or CH
3
, n is 1 and m is 1. Particularly preferred amino acids are selected from &bgr;-alanine-N,N-diacetic acid, methyl-glycine N,N-diacetic acid, isoserine N,N-diacetic acid, or mixtures thereof.
The particles suitably comprises up to about 15h by weight, preferably up to about 10% by weight, most preferably up to about 5% by weight of amino acid(s) as described above or a salt thereof.
The particles preferably comprise more than about 0.01% by weight, most preferably more than about 0.05% by weight of amino acid(s) as described above or a salt thereof. The amino acid may be mixed with the peroxy compound and/or be included in a coating.
It is assumed that the amino acid acts as a chelating agent, but it has surprisingly been found that the amino acids according to the invention gives better storage stability compared to conventional non-biodegradable chelating agents such a EDTA. Too high a concentration of amino acids or salts thereof may however decrease the thermal stability, particularly at high concentrations of the peroxy compounds.
It is preferred to use an alkali metal or an alkaline earth metal salt of the amino acid. Alkali metals are preferably selected from sodium, potassium or mixtures thereof, and alkaline earth metals are preferably selected from calcium, magnesium or mixtures thereof. Sodium salts are particularly preferred. In the following description of the invention, the term amino acid also refers to salts thereof.
The particles preferably contain silicate which further improves the stability and also enhances the mechanical strength. Silicate may be mixed with the peroxy compound and/or be included in a coating. Preferably at least some of the silicate is mixed with the peroxy compound. The silicate is suitably an alkali metal silicate, preferably of sodium, potassium or mixtures thereof, most preferably of sodium. The molar ratio SiO
2
:M
2
O, M being an alkali metal, is preferably from about 1 to about 3, most preferably from about 1 to about 2.5. The particles suitably contains from about 0.1 to about 20% by weight, preferably from about 0.2 to about 15% by weight, most preferably from about 0.5 to about 10% by weight of silicate expressed as sodium silicate.
It has been found that the stability is further improved if the particles contain a water soluble magnesium compound, preferably magnesium sulfate. The magnesium compound may be mixed with the peroxy compound and/or be included in a coating. Preferably at least some of the magnesium is mixed with the peroxy compound, most preferably in combination with alkali metal silicate. The particles preferably contains from about 0.01 to about 5% by weight, most preferably from about 0.1 to about 3% by weight of magnesium expressed as magnesium sulfate.
Particles according to the invention have high stability even if uncoated, but the highest stability is normally achieved if the particles are coated. Such a coating may for example contain one or more of amino acids as described herein, alkali metal silicate, water soluble magnesium compounds such as magnesium sulfate, alkali metal salts of carbonate, bicarbonate or sulfate, or environmental acceptable organic chelating agents, the different components being applied in one or several layers.
Suitably, the particles have an average diameter from about 50 to about 3000 &mgr;m, preferably from about 100 to about 1600 &mgr;m. The preferred density is from about 600 to about 1500 g/l, particularly from about 800 to about 1100 g/l. It has been found that a high density as well as a high average particle size improves the storage stability.
The invention is particularly advantageous if the peroxy compound is alkali metal percarbonate, but also other peroxy compounds can be stabilized, for example alkali metal salts of perborates, peroxysulfates, peroxyphosphates or peroxysilicates, peroxycarboxylic acids or peroxycarboxylic acid releasing compounds such as di-acylated di-peroxy carboxylic acids (see WO 91/17143).
Particles according to the invention can be prepared by conventional methods. Ingredients to be mixed with the peroxy compound are preferably added in a granulation step, but may also be included directly when, for example, alkali metal percarbonate is produced from alkali metal carbonate and hydrogen peroxide. If alkali metal silicate is to be included, it is preferably added in the form of an aqueous solution, and the amino acid or a salt thereof is then preferably mixed therein before addition to the peroxy compound. Granulazion may be performed by conventional methods well known among those skilled in the art, such as compacting, extruding, agglomeration in drum or disk, fluid-bed granulation, prilling or in different kinds of mixers. An optional coating step may be performed by spraying the particles with preferably aqueous solutions of the components to be applied, for example an a drum or a fluid bed.
The invention further concerns use of the described particles comprising a peroxy compound and an amino acid as a bleaching agent, preferably in connection with washing of textiles or dishwashing. The washing water may be supplied with particles ac
Jigstam Monica
Lagnemo Hans
Eka Chemicals AB
Gupta Yogendra
Petruncio John M
Serbin David J.
LandOfFree
Bleaching agent does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Bleaching agent, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Bleaching agent will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2478056