Surface-cleaning method

Cleaning and liquid contact with solids – Processes – Using sequentially applied treating agents

Reexamination Certificate

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C134S002000, C134S003000, C134S028000, C134S036000, C134S041000, C134S042000, C510S108000, C510S219000, C510S238000, C510S240000, C510S245000, C510S275000, C510S276000, C510S475000, C510S480000, C510S495000

Reexamination Certificate

active

06387189

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of cleaning surfaces made of glass, graphite, ceramics, polymeric and metallic materials, synthetic and vegetable fibres, e.g. fabrics, textiles or waste paper, in particular membrane surfaces, by detaching or dissolving organic and inorganic soilings by a simple flushing operation.
Deposits of organic and inorganic impurities are a constant problem in industry and the home. Thus, the deposits lead, for example, to a reduction in flow rate or even to blockages in pipes, to contaminations in reactors or soilings on objects of everyday use.
Glassware is particularly susceptible to soilings and is a particular problem in the domestic sector. In order to maintain the operation of equipment and materials and hygiene, the cleaning of surfaces is an important procedure in many fields.
Membranes, as a specific example of surfaces, are used in a variety of ways in industry and in the medical field. For their use to be economical, it is important to maintain a high flow rate. Deposits on the membrane surface partially block the membrane, resulting in a reduced and uneconomical permeate flow. Cleaning compositions can be used to largely remove the soilings and increase the flow rate again.
2. Description of the Related Art
The Aachen membrane colloquium, preprints page 41 (1991) reports on the use of various flushing chemicals; only alkaline formulations which contain, for example, EDTA, phosphates, anionic and nonionic surfactants and enzymes lead to adequate cleaning performances. Citric acid and peracetic acid do not exhibit an adequate action.
Permasep Engineering Manual, Bulletin 507, page 1-4 (1982) describes various cleaning compositions and cleaning procedures for cleaning membranes. The cleaning compositions proposed were frequently standard commercial cleaning compositions, which are a complex mixture of very many different active components.
Desalination, 77, 135-179 (1990) reports on flushing procedures for various applications of ultrafiltration, where purification is in some instances necessary after an operating period of just a few hours.
A list of cleaning compositions and their activity mechanisms is given in Desalination, 71, 325-335 (1989), and the need to use a variety of cleaning compositions in a certain sequence to achieve satisfactory cleaning performances is emphasized in particular.
The specialist journal Vom Wasser, 67, 59-68 (1986) reports on the optimization of flushing processes during water treatment using reverse osmosis plants, where the aim is to use chemically pure surfactants instead of formulated cleaning compositions. The investigations showed that a combination of EDTA and a formulated cleaning composition produced inferior performances than EDTA on its own.
EP 0 513 948 describes the cleaning of hard surfaces by a cleaning composition that is composed of a variety of components and inter alia comprises a complexing agent and an organic solvent.
EP 0 261 874 discloses a cleaning composition for hard surfaces which comprises EDTA and an alkanesulphonate. U.S. Pat. No. 4,808,328 likewise discloses cleaning compositions for hard surfaces which, in addition to EDTA, comprise an alkanesulphonate.
It is a common feature of all cleaning compositions and in particular all membrane cleaners which cover a broad field of use that they are composed of a complex mixture of many different cleaning chemicals and auxiliaries, and even that in most cases a flushing procedure with various cleaning compositions has to be carried out in a certain sequence for effective cleaning. In particular, most formulated membrane cleaners contain phosphates or phosphonates to improve the membrane cleaning performance.
BRIEF SUMMARY OF THE INVENTION
Surprisingly, it has now been found that the use of a cleaning composition which comprises at least one component selected from the group consisting of
i) iminodisuccinic acid of the formula (I)
 in which
R
1
, R
2
, R
3
and R
4
independently of one another are H, Li, Na, K, NH
4
, H
3
NCH
2
CH
2
OH, H
2
N(CH
2
CH
2
OH)
2
or HN(CH
2
CH
2
OH)
3
,
R
5
and R
6
independently of one another are H or OH, and
R
7
is H, CH
2
CH
2
OH, CH
2
CH
2
CH
2
OH, CH
2
CH(OH)CH
3
, CH
2
COOR
8
or CH
2
CH
2
COOR
8
, where R
8
independently of R
1
has the scope of meanings of R
1
,
ii) polyamino acid or
iii) emulsifier,
 by a simple flushing operation (no procedure with various cleaners in sequence) achieves significantly better cleaning performances on surfaces, in particular membrane surfaces, than does the use of cleaners recommended in the literature. In addition, better cleaning performances are also achieved than when phosphate- and phosphonate-containing cleaners are used.
DETAILED DESCRIPTION OF THE INVENTION
The invention relates to a method of cleaning surfaces made of glass, graphite, ceramics, polymeric and metallic materials, synthetic and vegetable fibres, and membranes by detaching or dissolving organic or inorganic soilings or a mixture of the two by a simple flushing operation with a solution of a cleaning composition at, in particular, 10-100° C. and a pH of in particular 3-13, which is characterized in that the cleaning composition used is at least one component selected from the group consisting of
i) iminodisuccinic acid of the formula (I)
 in which
R
1
, R
2
, R
3
and R
4
independently of one another are H, Li, Na, K, NH
4
, H
3
NCH
2
CH
2
OH, H
2
N(CH
2
CH
2
OH)
2
or HN(CH
2
CH
2
OH)
3
,
R
5
and R
6
independently of one another are H or OH, and
R
7
is H, CH
2
CH
2
OH, CH
2
CH
2
CH
2
OH, CH
2
CH(OH)CH
3
, CH
2
COOR
8
or CH
2
CH
2
COOR
8
, where R
8
independently of R
1
has the scope of meanings of R
1
,
ii) polyamino acid or
iii) emulsifier,
 comprises and the solvent used is water or a mixture of water and a C
1
-C
4
-alcohol or a C
3
-C
4
-ketone.
The invention further relates to a composition for cleaning surfaces made of glass, graphite, ceramics, polymeric and metallic materials, synthetic and vegetable fibres and membranes, based on at least one component selected from the group consisting of
i) iminodisuccinic acid of the formula (I)
 in which
R
1
, R
2
, R
3
and R
4
independently of one another are H, Li, Na, K, NH
4
, H
3
NCH
2
CH
2
OH, H
2
N(CH
2
CH
2
OH)
2
or HN(CH
2
CH
2
OH)
3
,
R
5
and R
6
independently of one another are H or OH, and
R
7
is H, CH
2
CH
2
OH, CH
2
CH
2
CH
2
OH, CH
2
CH(OH)CH
3
, CH
2
COOR
8
or CH
2
CH
2
COOR
8
, where R
8
independently of R
1
has the scope of meanings of R
1
,
ii) polyamino acid or
iii) emulsifier
 and a solvent from the group consisting of water and a mixture of water and a C
1
-C
4
-alcohol or a C
3
-C
4
-ketone, where the solvent constitutes in particular 40-99.9% by weight, preferably 50-99% by weight, particularly preferably 60-90% by weight of the total composition.
The emulsifiers to be used according to the invention are preferably C
8
-C
25
-alkanesulphonates, particularly preferably C
10
-C
20
-alkanesulphonates, very particularly preferably C
12
-C
18
-alkanesulphonates. It is also preferable to use linear alkanesulphonates.
The iminodisuccinic acids of the formula (I) to be used according to the invention are used in aqueous solution.
Preferably, R
6
is H, and particularly preferably R
5
and R
6
are H. In a likewise preferred manner, R
7
is H. In a further preferred manner R
5
, R
6
and R
7
are H, so that (I) represents the unsubstituted iminodisuccinic acid (IDS) and its salts of the above-described type.
In a further preferred manner, the radicals R
11
, R
12
, R
13
and R
14
appear in the position of R
1
, R
2
, R
3
and R
4
and have the meaning H, Na, K, NH
4
or H
3
NCH
2
CH
2
OH.
The iminodisuccinic acids of the formula (I) used according to the invention are in pure form or are combined with small amounts of secondary components from the preparation of (I), such as maleic acid, fumaric acid, aspartic acid, malic acid, asparagine, tartaric acid, hydroxyaspartic acid, condensates of aspartic acid etc. or their s

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