Corrosion protection for glassware in a dishwasher

Description

[0001] The present invention relates to a polysaccharide-based gel comprising glass protection additives selected from zinc salts, polyvinylamide, and polyvinylamine, or combinations thereof. Furthermore, the present invention relates to the use of this gel for corrosion protection of glassware during cleaning and / or rinsing processes, particularly in a dishwasher, and to a method for inhibiting corrosion of glassware during cleaning and / or rinsing processes, particularly in a dishwasher.

[0002] Corrosion of glassware during cleaning and / or rinsing processes in a dishwasher has been a long-standing problem. Glassware is subject to varying degrees of corrosion during repeated dishwasher cycles. Following the release of minerals, the silicate network undergoes progressive hydrolysis. This can then lead to the formation of visible cloudiness and streaks in the glass through deposition.

[0003] Various approaches to overcoming the problems described are known from the state of the art.

[0004] For example, EP 1 141 190 A1 describes the use of water-soluble glass as corrosion protection for glassware. However, the production of water-soluble glass is both time-consuming and energy-intensive, as it must be carried out at process temperatures of approximately 850°C. Rinse aids for reducing glassware corrosion are also known from WO 2004 / 061068 A. WO 2010 / 065482 A1 discloses the use of cationic polysaccharides to reduce glass corrosion. US 2005 / 075258 A1 discloses a composition comprising magnesium or zinc and an organic acid to reduce glass corrosion. DE 10 255 115 A1 discloses the use of an active ingredient-containing polymer matrix to reduce glass corrosion.

[0005] The object of the present invention was therefore to provide a system which can prevent or slow down the corrosion problems described above and is simple to manufacture.

[0006] In this regard, the inventors of the present invention have found that the object can be achieved by a polysaccharide-based gel which comprises glass protection additives selected from zinc salts, polyvinylamide or polyvinylamine or combinations thereof.

[0007] In a first aspect, the present invention therefore relates to a gel according to claim 1, which is suitable for the corrosion protection of glassware.

[0008] In a further aspect, the invention also relates to the use of the gel according to the invention for corrosion protection of glassware, in particular during cleaning and / or rinsing processes in a dishwasher.

[0009] Finally, the invention also relates to methods for inhibiting the corrosion of glassware, in particular in cleaning and / or rinsing processes, comprising the steps: i) bringing the glassware into contact with the gel according to the invention, wherein the gel has been dissolved in water, in particular in a dishwasher; ii) optionally carrying out a cleaning or rinsing step.

[0010] The weight average molecular weight can be determined according to the present invention by gel permeation chromatography using polystyrene standards.

[0011] Unless otherwise stated, all quantities stated in connection with the components of the gel described herein refer to wt.%, each based on the total weight of the gel. Furthermore, such quantities referring to at least one component always refer to the total amount of that component contained in the gel, unless explicitly stated otherwise. This means that such quantities, for example in connection with "at least one additive," refer to the total amount of additive contained in the gel.

[0012] "At least one," as used herein, refers to 1 or more, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, or more. In the context of components of the compositions described herein, this statement does not refer to the absolute amount of molecules but to the type of component. "At least one additive" therefore means, for example, one or more different additives, i.e., one or more different types of additives. When used in conjunction with quantities, the quantities refer to the total amount of the correspondingly designated type of component, as defined above.

[0013] "Substantially free" as used herein means that the respective compound is present in the respective component or composition in less than 0.01 wt.%, preferably 0.001 wt.%, more preferably 0.0001 wt.%, and most preferably not at all. In particular, it also means that the respective compound has not been intentionally added.

[0014] The term "gels" or "solid gels", as used interchangeably herein, refers to preparations for which, under standard conditions (25°C; 1013 mbar), a force of at least 0.03 mN is required to penetrate a 30° stainless steel cone 5 mm deep into the respective product matrix (measured with the Texture Analyzer TA.XT plus).

[0015] The polysaccharide-based gel is a gel based on a cationic polysaccharide, in particular selected from the group of cationic cellulose polymers and / or cationic guar derivatives.

[0016] The at least one polysaccharide polymer is contained in 0.1 wt.% to 3 wt.%, preferably 0.2 to 1.5 wt.%, based on the total weight of the gel.

[0017] The gels preferably contain as cationic polysaccharide polymer(s) - based on the weight of the gel - 0.1 to 3 wt.%, preferably 0.15 to 2 wt.%, more preferably 0.1 to 1.5 wt.% and in particular 0.15 to 0.8 wt.% of at least one polymer from the group of cationic cellulose polymers and / or cationic guar derivatives.

[0018] Cationic cellulose polymers within the meaning of the invention are those that carry more than one permanent cationic charge in at least one side chain. Cellulose is composed of beta-1,4-glycosidically linked D-glucopyranose units and forms unbranched, water-insoluble chains. The "side chain" of a cellulose is defined as chemical substituents that bind to the cellulose backbone and are not part of the native cellulose, for example, because they were subsequently introduced through chemical synthesis.

[0019] Preferred are quaternized cellulose polymers derived from hydroxy(C2-C4)alkylcelluloses, particularly preferably from hydroxyethylcelluloses.

[0020] Such polymers are known to the person skilled in the art and are commercially available from various companies.

[0021] Particularly preferred are the cationic cellulose derivatives known under the INCI names Polyquaternium-4, Polyquaternium-10, Polyquaternium-24, Polyquaternium-67, and / or Polyquaternium-72. Very particular preference is given to Polyquaternium-10, Polyquaternium-24, and / or Polyquaternium-67, and especially preferred is Polyquaternium-10.

[0022] Preferred gels according to the invention contain as cationic polysaccharide polymer(s) - based on the weight of the gel - 0.01 to 3 wt.%, preferably 0.05 to 2 wt.%, more preferably 0.1 to 1.5 wt.% and in particular 0.15 to 0.8 wt.% of at least one polymer from the group of polyquaternium-4, polyquaternium-10, polyquaternium-24, polyquaternium-67 and / or polyquaternium-72.

[0023] Particularly preferred gels according to the invention contain as cationic polysaccharide polymer(s) - based on the weight of the gel - 0.01 to 3 wt.%, preferably 0.05 to 2 wt.%, more preferably 0.1 to 1.5 wt.% and in particular 0.15 to 0.8 wt.% polyquaternium-10.

[0024] Suitable cationic guar derivatives within the meaning of the invention are cationic hydroxyalkyl guar derivatives, preferably cationic hydroxyethyltrimethylammonium guar and / or cationic hydroxypropyltrimethylammonium guar with weight-average molecular weights between 100,000 and 2,000,000 g / mol.

[0025] Particularly preferred are the cationic guar polymers known under the INCI name Guar Hydroxypropyltrimonium Chloride, which have a weight-average molecular weight between 200,000 and 1,600,000 g / mol. The cationic charge density of these guar polymers is preferably at least 0.4 meq / g, more preferably at least 0.5 meq / g, and especially at least 0.6 meq / g. The determination can be carried out, for example, by titration. Their nitrogen content is preferably in the range of 1.1 to 1.8 wt.% (based on their total weight).

[0026] Cationic guar derivatives, known under the INCI name Guar Hydroxypropyltrimonium Chloride, are known to those skilled in the art and are available from various suppliers, for example, under the trade names Cosmedia ®< Guar, N-Hance ®< and / or Jaguar ®<.

[0027] Particularly preferred gels according to the invention contain as cationic polysaccharide polymer(s) - based on the weight of the gel - 0.01 to 3 wt.%, preferably 0.05 to 2 wt.%, more preferably 0.1 to 1.5 wt.% and in particular 0.15 to 0.8 wt.% guar hydroxypropyltrimonium chloride.

[0028] The gel of the present invention further contains at least one glass protection additive selected from zinc salts, polyvinylamine, polyvinylamide or mixtures thereof.

[0029] The at least one glass protection additive is contained in 0.1 to 15.0 wt.%, preferably 2.0 to 10.0 wt.%, based on the total weight of the gel.

[0030] Preferred zinc salts are zinc acetate, zinc chloride, zinc oxide, zinc sulfide, zinc stearate, zinc carbonate, and zinc ricinoleate, particularly preferred are zinc chloride, zinc acetate and zinc ricinoleate.

[0031] Polyvinylamine compounds within the meaning of the invention are polyvinylamine polymers. Polyvinylamide compounds within the meaning of the invention are polyvinylamide polymers.

[0032] The polyvinylamine- and / or polyvinylamide-containing polymers to be used with preference according to the invention can be prepared by radical polymerization of N-vinylcarboxamides, such as N-vinylformamide, N-vinyl-N-methylformamide, N-vinylacetamide, N-vinyl-N-methylacetamide, N-vinyl-N-ethylformamide, N-vinyl-Nn-propylformamide, N-vinyl-N-isopropylformamide, N-vinyl-N-isobutylformamide, N-vinyl-N-methylacetamide, N-vinyl-Nn-butylacetamide and N-vinyl-N-methylpropionamide, preferably of N-vinylformamide, and preferably subsequent complete or in particular partial hydrolysis of the amide functions to amine functions.

[0033] The hydrolysis can be carried out under alkaline or acidic conditions, preferably in an aqueous medium and at a temperature of 70 to 90°C. However, it is also possible to use inert organic solvents, such as dioxane or aliphatic or aromatic hydrocarbons, or alcohols, e.g., tert-butanol, as the reaction medium.

[0034] The polymers to be used according to the invention may additionally contain a monoethylenically unsaturated comonomer as polymerized units. Of course, several comonomers may also be polymerized. Suitable comonomers include anionic, nonionic, and cationic monomers.

[0035] Suitable anionic comonomers include: α,β-unsaturated monocarboxylic acids, preferably having 3 to 6 carbon atoms, such as acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid, and vinylacetic acid, and their alkali metal and ammonium salts; unsaturated dicarboxylic acids, preferably having 4 to 6 carbon atoms, such as itaconic acid and maleic acid, their anhydrides, such as maleic anhydride, and their alkali metal and ammonium salts; half esters of unsaturated dicarboxylic acids with C1-C6 alcohols, such as itaconic and maleic acid half esters.

[0036] Acrylic acid and its salts, especially sodium acrylate, are preferred as anionic comonomers.

[0037] Suitable non-ionic comonomers include: Esters of monoethylenically unsaturated C3-C6 carboxylic acids, especially acrylic acid and methacrylic acid, with monohydric C1-C22 alcohols, especially with C1-C6 alcohols; and hydroxyalkyl esters of monoethylenically unsaturated C3-C6 carboxylic acids, especially acrylic acid and methacrylic acid, with dihydric C2-C4 alcohols, such as methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, ethylhexyl (meth)acrylate, hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate; Amides of monoethylenically unsaturated C3-C6 carboxylic acids, especially acrylic acid and methacrylic acid, with primary and secondary C1-C12 amines, such as (meth)acrylamide, N-methyl(meth)acrylamide, N-isopropyl(meth)acrylamide and N-butyl(meth)acrylamide; vinyl esters of saturated C1-C11 carboxylic acids, such as vinyl acetate and vinyl propionate; aliphatic and aromatic olefins, such as ethylene, propylene, C4-C24 α-olefins, especially C4-C16 α-olefins, e.g.Butylene, isobutylene, diisobutene, styrene and α-methylstyrene, as well as diolefins with an active double bond, e.g. butadiene; unsaturated alcohols, such as vinyl alcohol and allyl alcohol; unsaturated nitriles, such as acrylonitrile and methacrylonitrile.

[0038] Suitable cationic comonomers include: N-vinyllactams of lactams with 5- to 7-membered rings, such as N-vinylpyrrolidone, N-vinylcaprolactam and N-vinyloxazolidone; monomers containing vinylimidazole and vinylimidazoline units and their alkyl derivatives, in particular C1-C15 alkyl derivatives, and their quaternization products, such as N-vinylimidazole, N-vinyl-2-methylimidazole, N-vinyl-4-methylimidazole, N-vinyl-5-methylimidazole, N-vinyl-2-ethylimidazole, N-vinylimidazoline, N-vinyl-2-methylimidazoline and N-vinyl-2-ethylimidazoline; Vinylpyridines and their quaternization products, such as 4-vinylpyridine, 2-vinylpyridine, N-methyl-4-vinylpyridine and N-methyl-2-vinylpyridine;basic esters of ethylenically unsaturated carboxylic acids, in particular the esters of α,β-unsaturated C3-C6 monocarboxylic acids, especially acrylic acid and methacrylic acid, with amino alcohols, especially N,N-di(C1-C4-alkyl)amino-C2-C6 alcohols, and their quaternization products, such as dimethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylate, diethylaminoethyl acrylate, diethylaminopropyl acrylate, dimethylaminobutyl acrylate and diethylaminobutyl acrylate; basic amides of ethylenically unsaturated carboxylic acids, in particular the N,N-di(C1-C4-alkyl)amino(C2-C6-alkyl)amides of α,β-unsaturated C3-C6-monocarboxylic acids, in particular acrylic acid and methacrylic acid, and their quaternization products, such as dimethylaminoethyl(meth)acrylamide, diethylaminoethyl(meth)acrylamide, dimethylaminopropyl(meth)acrylamide and diethyleminopropyl(meth)acrylamide. ;

[0039] If the polymers to be used according to the invention contain comonomers in copolymerized form, their content is generally from 0.1 to 80 mol%, in particular up to 50 mol%, based on the polymer.

[0040] The polymers to be used according to the invention can be in water-soluble form, but they can also be cross-linked and thus water-insoluble. The polymers are preferably water-soluble polymers.

[0041] Crosslinking can be achieved by thermal treatment of the polymer and / or by reaction with formic acid derivatives, whereby amidines are deliberately formed. However, crosslinking is preferably carried out by polymerizing another crosslinking comonomer containing at least two ethylenically unsaturated, non-conjugated double bonds.

[0042] Suitable cross-linkers include: Alkylenebisacrylamides, such as methylenebisacrylamide and N,N'-acryloylethylenediamine; divinylalkyleneureas, such as N,N'-divinylethyleneurea and N,N'-divinylpropyleneurea; -ethylidenebis-3-(N-vinylpyrrolidone), N,N'-divinyldiimidazolyl(2,2')butane and 1,1'-bis(3,3'-vinylbenzimidazolit-2-one)1,4-butane; alkylene glycol di(meth)acrylates, such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate and tetraethylene glycol di(meth)acrylate; aromatic divinyl compounds, such as divinylbenzene and divinyltoluene; vinyl acrylate, allyl (meth)acrylate, triallylamine, divinyldioxane and pentaerythritol triallyl ether.

[0043] The polymers according to the invention preferably have weight-average molecular weights Mw of 1000 to 6 000 000 g / mol, preferably 45 000 to 450 000 g / mol.

[0044] A copolymer of vinylamine and N-vinylformamide is particularly preferred. Since vinylamine itself is not available, copolymers of vinylamine and N-vinylformamide are prepared by polymerizing N-vinylformamide and subsequent alkaline hydrolysis as described above. Products with varying degrees of hydrolysis can be produced. Copolymers of vinylamine and N-vinylformamide are commercially available from BASF, for example, under the name "Lupamin®".

[0045] In all embodiments of the invention, the gels are characterized in that the at least one glass protection additive is selected from zinc chloride, zinc acetate, zinc ricinoleate, polyvinylamine, polyvinylamide and mixtures thereof, preferably polyvinylamine and at least one zinc salt selected from zinc chloride, zinc acetate, zinc ricinoleate.

[0046] In preferred embodiments, the at least one zinc salt, in particular zinc chloride, zinc acetate, zinc ricinoleate, is present in 0.5 to 15.0 wt.%, preferably 2 to 10 wt.%, based on the total weight of the gel; and / or the polyvinylamine is present in 0.1 to 10 wt.%, preferably 1 to 5 wt.%, based on the total weight of the gel.

[0047] The gel may further contain at least one solvent. The at least one solvent is preferably an organic solvent, in particular a mixture of a polar and a non-polar solvent. The polar solvent is particularly preferably an organic solvent having at least one hydroxyl group, in particular alkanolamines, polyols such as ethylene glycol, 1,2-propylene glycol, and 1,2-glycerol, in particular 1,2-propylene glycol. The at least one non-polar organic solvent is preferably an oil, in particular a naturally occurring vegetable oil such as castor oil, castor oil, coconut oil, corn oil, linseed oil, cottonseed oil, sesame oil, palm oil, olive oil, sunflower oil, soybean oil, in particular castor oil.

[0048] In various embodiments, the at least one solvent is present in amounts of 20.0 to 90.0 wt.%, preferably 50.0 to 85 wt.%, particularly preferably 70.0 to 80.0 wt.%, in each case based on the total weight of the gel.

[0049] The gel may further contain at least one additive. The additives are preferably selected from alkali and alkaline earth metal salts, such as sodium sulfate, fillers such as silica or Aerosil, builders, corrosion inhibitors, enzymes, builders such as Aerosil, foam inhibitors, surfactants, bittering agents, sequestering agents, electrolytes, fragrances, antimicrobial agents, and dyes.

[0050] In various embodiments, the at least one additive is contained in an amount of 0.1 to 40 wt.%, preferably 5 to 30 wt.%, more preferably 15 to 25 wt.%, in each case based on the total weight of the gel

[0051] In preferred embodiments, the gel is substantially phosphate and / or phosphonate free.

[0052] In further preferred embodiments, the gel is bleach-free. Essentially "phosphate-free" and "phosphonate-free," as used herein, means that the gel in question is essentially free of phosphates or phosphonates, respectively, i.e., in particular, it contains phosphates or phosphonates in amounts of less than 0.1 wt.%, preferably less than 0.01 wt.%, based on the total weight of the gel.

[0053] The builders that can be used include aminocarboxylic acids and their salts, carbonates, organic cobuilders and silicates.

[0054] Aminocarboxylic acids and / or their salts represent another important class of builders. Particularly preferred representatives of this class are methylglycinediacetic acid (MGDA) or its salts, as well as glutamic diacetic acid (GLDA) or its salts, or ethylenediamine diacetic acid or its salts (EDDS). Also suitable are iminodisuccinic acid (IDS) and iminodiacetic acid (IDA). The content of these aminocarboxylic acids or their salts can be, for example, between 0.1 and 15 wt.%, preferably between 0.5 and 10.0 wt.%, and in particular between 0.5 and 6 wt.%. Aminocarboxylic acids and their salts can be used together with the aforementioned builders, in particular also with the phosphate-free builders.

[0055] Organic cobuilders include, in particular, polycarboxylates / polycarboxylic acids, polymeric carboxylates, aspartic acid, polyacetals and dextrins.

[0056] Suitable organic builders include, for example, polycarboxylic acids, which can be used in the form of the free acid and / or their sodium salts. Polycarboxylic acids are understood to be carboxylic acids that carry more than one acid function. Examples include citric acid, adipic acid, succinic acid, glutaric acid, malic acid, tartaric acid, maleic acid, fumaric acid, sugar acids, aminocarboxylic acids, nitrilotriacetic acid (NTA), provided that such use of NTA is acceptable for ecological reasons, and mixtures thereof.

[0057] For example, the use of carbonate(s) and / or bicarbonate(s), preferably alkali metal carbonate(s), particularly preferably sodium carbonate, is also possible. Alkali metal carbonates, especially sodium carbonate, can also be used as pH adjusters and are preferably present in various embodiments of the invention in an amount of 15 to 40 wt.%, more preferably 20 to 30 wt.%, based on the gel.

[0058] Polymeric polycarboxylates are also suitable as builders, for example the alkali metal salts of polyacrylic acid or polymethacrylic acid, for example those with a weight-average molecular weight of 500 to 70,000 g / mol.

[0059] Suitable polymers are, in particular, polyacrylates, which preferably have a weight-average molecular weight of 2000 to 20,000 g / mol. Due to their superior solubility, short-chain polyacrylates, which have a weight-average molecular weight of 2000 to 10,000 g / mol, and particularly preferably of 3000 to 5000 g / mol, may be preferred from this group.

[0060] The gels can also contain crystalline layered silicates of the general formula NaMSi x O 2x+1 * y H 2 O, in which M is sodium or hydrogen, x is a number from 1.9 to 22, preferably from 1.9 to 4, with particularly preferred values ​​for x being 2, 3 or 4, and y is a number from 0 to 33, preferably from 0 to 20. Amorphous sodium silicates with a modulus Na 2 O : SiO 2 of 1:2 to 1:3.3, preferably from 1:2 to 1:2.8 and in particular from 1:2 to 1:2.6, which are preferably dissolution-delayed and have secondary washing properties, can also be used.

[0061] In preferred gels, the silicate content is limited to amounts below 10 wt.%, preferably below 5 wt.%, and especially below 2 wt.%. Particularly preferred gels are silicate-free.

[0062] Individual fragrance compounds, e.g., synthetic products of the ester, ether, aldehyde, ketone, alcohol, and hydrocarbon type, can be used as perfume oils or fragrances within the scope of the present invention. However, mixtures of different fragrances that together produce an appealing fragrance note are preferred. Such perfume oils can also contain natural fragrance mixtures, such as those obtainable from plant sources, e.g., pine, citrus, jasmine, patchouli, rose, or ylang-ylang oil. The fragrances / perfume oils can be used encapsulated, for example, in microcapsules, or in free form, or both.

[0063] The gel according to the invention can be added directly into the wash cabinet or dishwasher during use. For example, dosing can be done via a dosing chamber of an automatic dishwasher. Addition can take place at any time during the wash cycle.

[0064] The gel according to the invention can be pre-portioned as a single portion, in particular in the form of a water-soluble pouch, preferably with a polyvinyl alcohol-based coating, usually in the form of a water-soluble PVA film.

[0065] All (preferred) embodiments described herein in connection with the gels according to the invention are also applicable to the use according to the invention and corresponding methods and vice versa. Examples:

[0066] Gels were prepared from the following compositions: Ingredient Example 1 Example 2 Example 3 Example 4 Example 5 % by weight % by weight % by weight % by weight % by weight 1,2-propylene glycol 40,0 40,0 40,0 40,0 40,0 Silica (Aerosil 300) 10,0 10,0 10,0 10,0 10,0 Jaguar C-13-S (Solvay) (cationic polysaccharide) 1 1 1 1 1 Sodium sulfate 8 8 8 8 8 castor oil 36 34 35 35 36 Zinc chloride - 7 3 - - Zinc acetate - - 3 4 - Zinc Ricinoleate - - - - 5 Lupamin 1595 (polyvinylamine) 5 - - 2 -

Claims

1. A gel suitable for corrosion protection of glassware comprising or consisting of - at least one polysaccharide polymer; - at least one glass protection additive selected from zinc salts, polyvinylamine, polyvinylamide or mixtures thereof; - optionally at least one solvent; and - optionally at least one additive; characterized in that (a) the at least one polysaccharide polymer is present in 0.1% to 3% by weight, preferably 0.2% to 1.5% by weight, based on the total weight of the gel; and (b) the at least one glass protection additive is present in 0.1 to 15.0% by weight, preferably 2.0 to 10.0% by weight, based on the total weight of the gel; and the at least one polysaccharide polymer is a cationic polysaccharide polymer.

2. Gel according to claim 1, characterized in that the at least one polysaccharide polymer is selected from the group of cationic cellulose polymers and / or cationic guar derivatives.

3. Gel according to any one of claims 1 or 2, characterized in that the at least one glass protection additive is selected from zinc chloride, zinc acetate, zinc ricinoleate, polyvinylamine, polyvinylamide and mixtures thereof, preferably polyvinylamine and at least one zinc salt selected from zinc chloride, zinc acetate, zinc ricinoleate is present.

4. Gel according to any one of claims 1 to 3, characterized in that the at least one zinc salt, in particular zinc chloride, zinc acetate, zinc ricinoleate, is present in 0.5 to 15.0% by weight, preferably 2 to 10% by weight, based on the total weight of the gel, and / or that the polyvinylamine is present in 0.1 to 10% by weight, preferably 1 to 5% by weight, based on the total weight of the gel.

5. Gel according to any one of claims 1 to 4, characterized in that (a) the at least one solvent is an organic solvent, in particular a mixture of a polar and a non-polar solvent, particularly preferably containing an organic solvent with at least one hydroxyl group, such as 1,2-propylene glycol and / or a non-polar organic solvent, such as oils, in particular castor oil; and / or (b) the at least one solvent is present in 20.0 to 90.0% by weight, preferably 50.0 to 85% by weight, particularly preferably 70.0 to 80.0% by weight, based on the total weight of the gel.

6. The gel according to any one of claims 1 to 5, characterized in that the gel further comprises at least one additive selected from alkali metal and alkaline earth metal salts, such as sodium sulfate, fillers, such as silica or aerosil, builders, corrosion inhibitors, enzymes, builders, foam inhibitors, surfactants, bittering agents, sequestering agents, electrolytes, fragrances, antimicrobial agents and colorants.

7. Gel according to one of claims 1 to 6, characterized in that the at least one additive is present in an amount of 0.1 to 40% by weight, preferably 5 to 30% by weight, more preferably 15 to 25% by weight, each based on the total weight of the gel.

8. Use of the gel according to any one of claims 1 to 7 for corrosion protection of glassware, in particular during cleaning and / or rinsing operations in a dishwasher.

9. A method of inhibiting corrosion of glassware, in particular in cleaning and / or rinsing operations, comprising the steps of: i) bringing the glassware into contact with the gel according to any one of claims 1 to 7, wherein the gel has been dissolved in water, in particular in a dishwasher; ii) optionally, carry out a cleaning or rinsing step.