DE20020588U1 - Detergent for cleaning processing units for reactive compounds - Google Patents

Description

• a

Henkel Doms GmbH & Co. KG
H 4431 EN
Dr. Mathes/Ge
30.11.2000

Utility model application
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Cleaning agents for cleaning processing units for reactive links

The present invention relates to a cleaning agent for cleaning processing units for compounds which react with one another to increase molecular weight and are highly viscous or solid at ²⁰ ° C.

Adhesives, sealants and similar coating agents are often processed in molten form. Such compounds based on thermoplastic polymers can usually be processed without any problems in the molten state in suitable processing units. Residues accumulating in the units can usually remain in the units after production has ended until they are liquefied again by the addition of heat during the next production cycle and thus made reusable.

However, the processing of compounds that react with each other to increase their molecular weight is problematic. This can involve just one component, the corresponding functional groups of which react with each other, for example when moisture or oxygen is present. However, it can also involve mixtures of different compounds (components) that are only mixed together shortly before application to a substrate to be coated. Aggregates suitable for processing such two- or multi-component systems usually convey the different components from separate storage containers or containers, dose the components in the correct mixing ratio, combine the components in a mixing head, for example, and place them in a mixing chamber.

static or dynamic mixing devices to create a homogeneous mixture.

If, for example, air humidity comes into contact with a component that hardens when exposed to air humidity, or if two components of a multi-component mixture that reacts with one another during hardening come together in the processing unit, a molecular weight buildup occurs. In order to prevent blockages in such processing units, the parts of the unit filled with the hardening compounds, such as the mixing head, mixer, hoses, application guns, application nozzles, mixing vessels, rollers and the like, must be rinsed when work is interrupted.

This can be done, for example, by rinsing with solvents or solvent mixtures such as aromatic or aliphatic solvents or chlorinated hydrocarbons in which the compounds in the aggregate are soluble. Furthermore, rinsing processes for two-component systems are known in which rinsing is carried out by one of the two components, whereby the aim is to suppress the curing reaction by strongly diluting with one component.

However, this method leads to considerable difficulties, particularly with very reactive materials. If the reactive material remains for too long or if the solvent or solvent mixture has too little rinsing effect, hardened material builds up on the walls of pipes, hoses, containers or on roller surfaces because the hardening reaction is not completely suppressed. Finally, the unit becomes blocked, particularly at narrow points within the unit, and production comes to a standstill. The use of solvents also carries the risk that the washed-out, reactive material will continue to react in the dissolved state and will then be difficult to separate from the solvent and will also be very difficult to dispose of.

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Various solutions are known from the state of the art to circumvent the problems mentioned above.

For example, DE-U G 91 14 780.8 describes a cleaning compound for removing reactive polyurethane hot melt adhesives from manufacturing and processing equipment, machines and systems, in particular application equipment. The cleaning compound described consists of a mixture of a particularly plastically deformable mass that does not react with the polyurethane hot melt adhesive and a monohydroxy-functional compound that can saturate the remaining NCO groups of the polyurethane hot melt adhesive. However, the disadvantage of the cleaning compound described is that the cleaning effect is often not sufficient to completely remove residues that have already hardened or hardened. In addition, long processing times and a large amount of cleaning compound are often required to achieve an adequate cleaning effect.

DE-A 197 18 065 relates to a cleaning agent for post-crosslinking polyurethane hot melts. The compounds described do have a good cleaning effect, but require a depolymerization catalyst. In some cases, a long period of time is also required to achieve a good cleaning effect.

EP-A 0 188 833 also relates to an agent for cleaning processing systems for highly viscous multi-component mixtures. The publication describes a solvent-based agent that contains a chain terminator to intervene in the polymerization reaction of the polymer system to be flushed. A disadvantage of the system described is that solvents such as chlorinated hydrocarbons, aromatic solvents or ethers have to be used. However, such solvents are generally undesirable for users due to their partially toxic properties, their flammability or their potential to endanger the environment.

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In addition, the processing of waste containing such solvents and their disposal is often complex and costly.

US-A 5,856,285 relates to a composition for removing already cured polyurethane adhesives and sealants. The solution described consists of a composition that contains PMA glycol ether acetate, dipentene and nonylphenol polyethylene glycol ether. However, the use of such a composition for cleaning processing machines for multi-component, mutually reactive compounds is not described in the publication. In addition, such use would again raise the disposal problems mentioned above. Furthermore, the exposure times described in the publication are too long for such an application.

Finally, US-A 5,772,790 describes a method and a composition for removing residues from PUR hot melt adhesives. A composition is described that contains a monofunctional amine and a non-reactive polyurethane. However, fillers are not described in the cited document.

There was therefore a need for cleaning agents for processing units for compounds that react with one another to increase their molecular weight and are highly viscous or solid at 20 ⁰ C, which do not have the above-mentioned disadvantages of the prior art. In particular, there was a need for cleaning agents for processing units for compounds that react with one another to increase their molecular weight and are highly viscous or solid at 20 ⁰ C, which have a quick cleaning effect using as little material as possible. In addition, there was a need for cleaning agents for processing units for compounds that react with one another to increase their molecular weight and are highly viscous or solid at 20 ⁰ C, which also have a cleaning effect in places that are usually difficult to clean and usually require subsequent cleaning by hand, for example slot nozzles or rollers.

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have a good cleaning effect, so that no further cleaning by hand is necessary.

The present invention was therefore based on the object of providing a cleaning agent for cleaning processing units for compounds which react with one another to increase their molecular weight and which are highly viscous or solid at 20 ^° C, which partially or completely satisfies the above-mentioned needs and does not have the disadvantages of the prior art.

The object according to the invention is achieved by a cleaning agent for cleaning processing units for compounds which react with one another to increase molecular weight and are highly viscous or solid at 20 ^° C, as described in more detail in the following text, in particular in the patent claims.

In the context of the present invention, a "processing unit" is understood to mean basically any device that can be used to process highly viscous compounds that react with one another to increase their molecular weight. In particular, such processing units are machines or machine parts that are directly or indirectly involved in the application of highly viscous compounds that react with one another to increase their molecular weight. The corresponding machine parts can be, for example, storage containers, melting containers, tank systems, drum melting systems, supply and discharge hoses, application nozzles such as slot or ring nozzles, roller application devices and the associated rollers, application guns, cartridge devices, foam melt systems, doctor blade systems or spray systems, extruder housings or extruder screws.

The term "compounds reacting with one another to increase their molecular weight" in the context of this text refers to compounds which are formed, for example, by polyaddition, polycondensation or polymerization or

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by two or more of the above reactions reacting with each other successively or simultaneously to increase the molecular weight.

In the context of the present invention, at least one of the compounds reacting with one another has a viscosity of at least about 500 cps, for example about 100 to about ^100,000 cps (measured under customary measuring conditions known to the person skilled in the art), at the processing temperature, for example at its melting temperature or above, in particular at about 120 to about ¹⁸⁰ °C or about 130 to about 15 °C.

Suitable compounds which react with one another to increase molecular weight and are highly viscous or solid at 20 ^° C are, for example, hot melt adhesives or corresponding surface coating agents which have one or more components and are essentially solid at room temperature or at least can only be plastically deformed with the application of force. Particularly suitable within the scope of the present invention are hot melt adhesives based on polyurethane which have at least one NCO group. Also suitable are, for example, epoxides which react with an OH or COOH group on the same molecule or the OH, COOH or NH group of another component by ring opening. Also suitable are polysulfide polymers or polymers containing silyl groups or unsaturated polymers such as polyesters or polymers containing unsaturated groups.

In the context of the present invention, a "cleaning agent" is understood to mean a composition which contains at least one organic compound having a melting point of at least about 50 ^° C and at least one inorganic or organic filler.

In the context of the present invention, an inorganic or organic filler is understood to mean a filler which is essentially present as a solid at the application temperature of the cleaning agent. The filler is preferably

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Cleaning agent is not or at least not significantly deformable in at least one dimension.

Suitable fillers can be fibrous, for example. According to the invention, the use of organic or inorganic fibers is possible. Suitable organic natural fibers include, for example, animal fibers such as wool, hair or silk. Plant fibers can also be used, for example cotton, kapok, flax, hemp, jute, kenaf, ramie, broom, manila, coconut or sisal. Suitable plastic fibers made from natural polymers are cupro, viscose,
Modal, acetate, triacetate, protein or alginate fibres or mixtures of two or more of the above fibres, provided that the fibres do not decompose at the application temperatures of the cleaning agent.

Also suitable within the scope of the present invention as a filler in the cleaning agent according to the invention are, for example, organic fibers made of synthetic polymers. Suitable fibers made of synthetic polymers are, for example, polyacrylic, polymethacrylic, polyvinyl chloride, fluorine-containing polymer fibers, polyethylene, polypropylene, vinyl acetate, polyacrylonitrile, polyamide, polyester or polyurethane fibers, provided they do not decompose at the application temperatures of the cleaning agent.

Suitable inorganic fibers include fibers such as asbestos, glass fibers and glass fiber short cuts or carbon fibers.

Fibers useful in the present invention may have a length of about 0.01 mm to about 10 cm, provided that the fiber dimensions allow passage of the cleaning agent through the processing unit without clogging or damaging the unit or parts of the unit.

However, in a preferred embodiment of the present invention, the cleaning agent according to the invention contains particulate fillers.

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The term "particulate" is used in the context of the present invention in relation to the dimensions of the filler particles used to distinguish filler particles that are considered to be "fibrous". In relation to the present invention, all fillers are particulate in which the length of the particle in relation to a specific spatial axis does not exceed the length of another spatial axis by more than about 20 times.

The spatial shape of suitable particles can essentially be any. In principle, for example, spherical, cubic, cuboid, conical, cylindrical or needle-shaped particles are suitable. In a preferred embodiment of the present invention, however, particles are used which have corners or edges or tips or other irregular surface elements such as bulges or dents.

In a preferred embodiment of the present invention, a particulate filler that can be used in the cleaning agents according to the invention has a particle size that is such that the particles contained in the cleaning agent can pass through any narrow passages that may be present in the processing unit without damaging or clogging the processing unit.

If, for example, a processing unit has exclusively large dimensions such as those found in storage containers, melting containers, tank systems or drum melting systems, a cleaning agent according to the invention can have particulate fillers whose particle size can be up to, for example, about 10 mm or up to about 5 mm in diameter. If, on the other hand, a processing unit has components with narrow passages such as hoses, feed lines or nozzles, the particle diameter should be correspondingly smaller than the diameter of the narrowest passage point. In such cases, the cleaning agent can, for example, have particulate fillers with a particle diameter of about 0.1 μηδ or more, for example more than about 1 pm, 2 pm, 5 pm, 10 pm or more.

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Optionally, the particulate fillers contained in the cleaning agent may have a particle diameter in the order of about 0.01 to about 5 mm or about 0.1 to about 1 mm, provided that the passages present in the processing unit allow the passage of such particles without clogging.

The particulate fillers contained in the cleaning agent can, for example, only have filler particles with a certain narrowly defined particle diameter. However, it is also possible and preferred within the scope of the present invention that the particles contained in the cleaning agent according to the invention have a distribution of particle diameter. If the filler particles contained in the cleaning agent according to the invention have a certain particle size distribution, the particle diameter, usually designated x50 or d50, should be within the above-mentioned ranges. Corresponding values can be determined, for example, by means of sieving methods, light or electron microscopy.

In principle, all organic or inorganic materials are suitable as fillers which, at the operating temperature of the cleaning agent according to the invention, allow the removal of hardened or preferably already hardened deposits of the highly viscous compounds in the processing unit which react with one another to increase their molecular weight. In addition, such fillers should be chemically stable at the operating temperatures of the cleaning agent and should not decompose.

Suitable particulate organic fillers include, for example, shredded organic materials with a melting or softening temperature above the operating temperature of the cleaning agent. Short fiber cuts, plastic granules or hollow plastic spheres are particularly suitable.

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The hardness of a suitable organic filler is preferably selected so that it is greater than the hardness of partially cured material in the processing unit, but preferably greater than the hardness of fully cured material in the processing unit.

Suitable inorganic fillers include, for example, rutile (&Pgr;&Ogr;2), chalk, lime powder, precipitated silica, pyrogenic silica, zeolites, bentonites, quartz, barite, light spar, metal nitrides, metal carbides, gypsum or anhydrite, ground minerals, glass beads, glass powder and other inorganic fillers known to the person skilled in the art.

Preferably, however, fillers are used whose Mohs hardness does not exceed 7, in particular fillers whose Mohs hardness is in a range from about 2 to about 6.

A cleaning agent according to the invention can, for example, contain only one of the above-mentioned fillers. However, it is also possible for a cleaning agent according to the invention to contain two or more of the above-mentioned fillers. Suitable combinations comprise, for example, one or more inorganic or one or more organic fillers. However, combinations of organic and inorganic fillers can also be used within the scope of the present invention.

The proportion of fillers in the cleaning agent according to the invention is about 5 to about 80% by weight, for example about 10 to about 70% by weight. Suitable filler proportions are, for example, about 20 to about 45% by weight or about 45 to about 65% by weight.

In addition to one or more of the above-mentioned fillers, a cleaning agent according to the invention also contains at least one organic compound with a melting point of more than about 50 ^° C, which does not decompose at the application temperatures of the cleaning agent.

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Suitable organic compounds have, for example, a molecular weight of about 200 to about 1,000,000, provided they have a melting point above the above-mentioned value. Corresponding compounds can be inert towards the reactive groups of the reactive compound or compounds.

For example, monomolecular or oligomeric organic compounds are suitable as a component of the cleaning agent according to the invention, as are usually used as plasticizers in polymers, for example the corresponding esters of phthalic acid, isophthalic acid or terephthalic acid with melting points above about 5O ⁰ C or the corresponding esters of glycerol or oligoglycerol with about 2 to about 10 glycerol units with aromatic or aliphatic monocarboxylic acids, for example glycerol trilaurate or glycerol tribenzoate.

In addition to or instead of one of the above-mentioned compounds, cleaning agents within the scope of the present invention can also contain polymers as organic compounds. Suitable polymers have, for example, a molecular weight of about 200 to about 1,000,000, in particular about 500 to about 500,000. In principle, all polymers, polyaddition products or polycondensation products that have a melting point of more than about 50 ^° C are suitable as polymers. Suitable examples include polyesters, polyethers, polyether esters, polyamides, polyurethanes, for example thermoplastic polyurethanes, polyolefins such as polystyrene, polyethylene or polypropylene, polyvinyl acetate or copolymers with two or more of the structural units mentioned, such as poly(ethylene vinyl acetate) (EVA) copolymers. Other suitable polymers are described later in this text.

In a further embodiment of the invention, a polyurethane is used as the polymer. Suitable polyurethanes can be produced, for example, using the following building blocks:

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(a) at least one polyisocyanate,

b) at least one polyol.

If necessary, up to about 20 wt.% of chain extender (component c), based on the weight of the polyurethane, can additionally be used.

Suitable isocyanates (building block a) are any organic compounds that have on average more than one, in particular 2 isocyanate groups.

Diisocyanates Q(NCO^ are preferably used, where Q is an aliphatic, optionally substituted hydrocarbon radical having 4 to about 12 carbon atoms, an optionally substituted cycloaliphatic hydrocarbon radical having 6 to about 15 carbon atoms, an optionally substituted aromatic hydrocarbon radical having 6 to about 15 carbon atoms or an optionally substituted araliphatic hydrocarbon radical having 7 to about 15 carbon atoms. Examples of such diisocyanates are tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), dodecamethylene diisocyanate, dimer fatty acid diisocyanate, 1,4-diisocyanatocyclohexane, 1-isocyanato-3,3,5-trimethyl-5-isocyanato-methylcyclohexane

(Isophorone diisocyanate, IPDI), 4,4'-diisocyanatodicyclohexylmethyl, 4,4'-diisocyanatodicyclohexylpropane^^, 1,3- and 1,4-diisocyanatobenzene, 2,4- or 2,6-diisocyanatotoluene (2,4- or 2,6-TDI) or mixtures thereof, 2,2'-, 2,4 or 4,4'-diisocyanatodiphenylmethane (MDI), tetramethylxylylene diisocyanate (TMXDI), p-xylylene diisocyanate, and mixtures consisting of these compounds.

Aliphatic diisocyanates are preferred, especially m- and p-tetramethylxylylene diisocyanate (TMXDI) and isophorone diisocyanate (IPDI).

It is of course also possible to use the higher functional polyisocyanates known in polyurethane chemistry or also modified ones known per se, for example carbodiimide groups, allophanate groups,

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Polyisocyanates containing isocyanurate groups, urethane groups or biuret groups must be used proportionately.

Suitable building block (b) are OH-terminated polyols or polyol mixtures, as are known to those skilled in the art of polyurethane production and can usually be used in the production of polyurethanes. In the context of the present invention, polyols from the group of polyether polyols, polyester polyols, polyether ester polyols, polyalkylene diols, polycarbonates or polyacetals, or a mixture of two or more thereof, each with 2, 3, 4 or more OH groups, but preferably not more than about 2 OH groups, can be used.

The polyols mentioned and their preparation are known from the prior art. For example, polyester polyols can be prepared by reacting dicarboxylic acids with diols or higher polyols or a mixture of diols and higher polyols or an excess of diols or higher polyols or a mixture thereof, and by ring opening of epoxidized esters, for example epoxidized fatty acid esters, with alcohols.

Suitable polyester polyols are obtainable, for example, by reacting dicarboxylic acids with diols or higher polyols or a mixture of diols and higher polyols or an excess of diols or higher polyols or a mixture thereof, and by ring opening of epoxidized esters, for example epoxidized fatty acid esters, with alcohols. Polycaprolactone diols, for example those that can be prepared from ε-caprolactone and diols or higher polyols, are also suitable as polyester polyols. Within the scope of the present invention, for example, polyester polyols that can be obtained from low molecular weight dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, isophthalic acid, terephthalic acid or phthalic acid, or a mixture of two or more thereof, with an excess of linear or branched, saturated or unsaturated aliphatic diols having about 2 to about 12 carbon atoms can be used. If necessary, in the preparation of the polyester polyols

There may still be a small proportion of higher-value alcohols, such as glycerine, trimethylolpropane, triethylolpropane, pentaerythritol or sugar alcohols such as sorbitol, mannitol or glucose.

Polyester polyols suitable for the production of polyurethanes in the context of the present invention are essentially linear and have, for example, a molecular weight of about 1,000 to about 50,000 and an OH number of about 10 to about 200, for example about 20 to about 80.

Polycaprolactone diols, for example those that can be prepared from ε-caprolactone and diols or higher polyols, are also suitable as polyester polyols. Within the scope of the present invention, polyester polyols that can be used to prepare the polyurethanes are, for example, polyester polyols that are obtainable from low molecular weight dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, isophthalic acid, terephthalic acid or phthalic acid, or a mixture of two or more thereof, with an excess of linear or branched, saturated or unsaturated aliphatic diols having about 2 to about 12 carbon atoms. If appropriate, a small proportion of higher-hydric alcohols can also be present during the preparation of the polyester polyols, these include, for example, glycerine, trimethylolpropane, triethylolpropane, pentaerythritol or sugar alcohols such as sorbitol, mannitol or glucose. Preferably, however, the polyester polyols are essentially linear.

Examples of polyacetals are the polycondensation products of formaldehyde and diols or polyols or their mixtures in the presence of acidic catalysts.

Polyalkylenediols such as polybutadienediol are commercially available products that are offered in various molecular weights. In the context of the present invention, they are suitable, for example, as a polyol component in the production of polyurethanes, such as those that can be used in the dispersions according to the invention.

Polyether polyols can be obtained, for example, by homo-, co- or block polymerization of alkylene oxides such as ethylene oxide, propylene oxide or butylene oxide, or mixtures of two or more thereof, or by reacting polyalkylene glycols with di- or trifunctional alcohols. The polymerized ring-opening products of cyclic ethers, for example tetrahydrofuran, with corresponding alcohols as starter molecules are also suitable. If ester compounds, for example oligo- or polyesters, are used as starter molecules, polyether esters are obtained which have both ether and ester groups. The compounds mentioned can also be used as polyol components in the production of polyurethanes, as can be used in the dispersions according to the invention within the scope of the present invention.

In a preferred embodiment of the present invention, the alkoxylation products, in particular the ethoxylation or propoxylation products of di- or trifunctional alcohols, are used as polyether polyols in the production of polyurethanes. The di- or trifunctional alcohols used are in particular alcohols selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, dipropylene glycol, the isomeric butanediols, hexanediols, octanediols, technical mixtures of hydroxy fatty alcohols with 14 to 22 carbon atoms, in particular hydroxystearyl alcohol, trimethylolpropane or glycerin, or mixtures of two or more of the alcohols mentioned.

In addition to the polyols mentioned above, linear or branched, saturated or unsaturated aliphatic, monofunctional alcohols, in particular methanol, ethanol, the isomers of propanol, butanol or hexanol, and fatty alcohols with about 8 to about 22 carbon atoms, for example octanol, decanol, dodecanol, tetradecanol, hexadecanol or octadecanol, can also be used as building block b). The fatty alcohols mentioned are obtainable, for example, by reducing natural fatty acids and can be used both as pure substances and in the form of their technical mixtures. Linear monoalcohols, for example, and in particular those

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with about 4 to about 18 carbon atoms. Instead of the linear or branched aliphatic alcohols or in mixtures with these, monoalkyl polyether alcohols of different molecular weights can also be used, preferably in the molecular weight range from about 1,000 to about 2,000. The monofunctional alcohols are preferably used in the production of the polyurethanes in such an amount that the resulting polyurethane has no NCO groups and in particular no OH groups.

Also usable as building block b) are polyhydric, in particular dihydric alcohols, as are obtainable, for example, by hydrogenation of di- or oligomeric fatty acids or their esters, castor oil, with C-M alkyl alcohols, ring-opened, epoxidized fats or oils, Ci2-18 fatty acid diethanolamides, monoglycerides of aliphatic C8-22 fatty acids, polypropylene glycols or polysiloxanes with terminal OH groups, or mixtures of two or more of the compounds mentioned.

Suitable chain extenders, such as those which can be used as building block c) in the context of the present invention to produce the polyurethanes, are, for example, polyhydric, in particular dihydric alcohols such as ethylene glycol, propylene glycol, propanediol-1,3, butanediol-1,4 or hexanediol-1,6. Low molecular weight polyester diols such as succinic acid, glutaric acid or adipic acid bis(hydroxyethyl) esters, or a mixture of two or more thereof, or low molecular weight diols containing ether groups such as diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol or tetrapropylene glycol can also be used as building block c). Also suitable are amines such as ethylenediamine, hexamethylenediamine, piperazine, 2,5-dimethylpiperazine, 1-amino-3-aminomethyl-3,5,5-

trimethylcyclohexane (isophoronediamine, IPDA) ₁ 4,4'-diamino-dicyclohexylmethane, 1,4-diaminocyclohexane, 1,2-diaminopropane, hydrazine, hydrazine hydrate, amino acid hydrazides such as 2-aminoacetic acid hydrazide or bis-hydrazides such as succinic acid bishydrazide. The use of tri- or higher-functional compounds in small amounts in the sense of an isocyanate polyaddition reaction is also possible to achieve a certain degree of branching

such as the already mentioned possible use of tri- or higher-functional polyisocyanates for the same purpose.

In a further preferred embodiment of the invention, polyamides are used as polymers. Polyamides can be produced in a known manner by reacting dicarboxylic acids with diamines. Suitable dicarboxylic acids are, for example, the dicarboxylic acids already mentioned in this text that are suitable for producing polyesters, in particular dimer fatty acids. In a preferred embodiment of the present invention, polyamides are used that are obtainable by reacting dimer fatty acids or their alkyl esters with alcohols having 1 to about 6 carbon atoms and alkylenediamines, in particular alkylenediamines having 2 to about 10 carbon atoms.

Also suitable as polymers in the context of the present invention for use in a cleaning agent according to the invention are the polymers of olefinically unsaturated monomers. Suitable polymers are, for example, vinyl ester polymers whose basic monomeric building block is a vinyl ester of a linear or branched carboxylic acid with about 2 to about 44, for example about 3 to about 15, carbon atoms. Suitable monomers for these homo- or polymeric polyvinyl esters are vinyl formate, vinyl acetate, vinyl propionate, vinyl isobutyrate, vinyl pivalate, vinyl 2-ethylhexanoate, vinyl esters of saturated branched monocarboxylic acids with 9 to about 15 carbon atoms in the acid residue, vinyl esters of longer-chain saturated or unsaturated fatty acids such as vinyl laurate, vinyl stearate or vinyl esters of benzoic acid and substituted derivatives of benzoic acid such as vinyl p-tert-butyl benzoate. The vinyl esters mentioned can each be present individually or as mixtures of two or more of the vinyl esters mentioned in the polyvinyl ester. The proportion of such vinyl esters in the total polymer is, in a preferred embodiment of the invention, at least about 10% by weight, for example at least about 20% by weight and at most about 75% by weight or at most about 60% by weight.

In a further preferred embodiment of the present

According to the invention, the polymer dispersion may also contain polymers which, in addition to one of the abovementioned vinyl esters or a mixture of two or more of the abovementioned vinyl esters, also have further comonomers. Other ethylenically unsaturated monomers which can be copolymerized with the abovementioned vinyl esters are, for example, acrylic acid, methacrylic acid and their esters with primary and secondary saturated monohydric alcohols having 1 to about 28 carbon atoms, such as methanol, ethanol, propanol, butanol, 2-ethylhexyl alcohol, cycloaliphatic alcohols such as cyclohexanol, hydroxymethylcyclohexane or hydroxyethylcyclohexane. The esters of the abovementioned ethylenically unsaturated acids with longer-chain fatty alcohols are also suitable.

Also suitable as comonomers are simple ethylenically unsaturated hydrocarbons such as ethylene or a-olefins with about 3 to about 28 carbon atoms, for example propylene, butylene, styrene, vinyltoluene, vinylxylene, and halogenated unsaturated aliphatic hydrocarbons such as vinyl chloride, vinyl fluoride, vinylidene chloride, vinylidene fluoride and the like. Such comonomers can have a proportion of up to about 50% by weight or less, for example about 0.5 to about 25% by weight, of the polymer used in the cleaning agents according to the invention.

For example, terpolymers made from three or more of the above-mentioned monomers can also be used, in particular terpolymers made from ethylene/vinyl acetate/acrylic acid ester or from ethylene/acrylic acid ester/acrylic acid.

Also usable in minor amounts as comonomers within the scope of the present invention are, for example, polyethylenically unsaturated monomers. Examples of such monomers are diallyl phthalates, diallyl maleate, triallyl cyanurate, tetraallyloxyethane, divinylbenzene, butanediol-1,4-dimethacrylate, triethylene glycol dimethacrylate, divinyl adipate, allyl acrylate, allyl methacrylate, vinyl crotonate, methylenebisacrylamide, hexanediol diacrylate, pentaerythritol diacrylate or trimethylolpropane triacrylate or mixtures of two or more thereof.

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Other polymers suitable for producing the cleaning agents according to the invention in the context of the present invention come from the group of styrene-butadiene rubbers (SBR). Such rubbers are produced by copolymerizing styrene and butadiene and generally contain the two monomers in a weight ratio of about 23.5 to 76.5 or about 40 to 60.

Another suitable group of polymers are polyvinyl acetates (PVAC). Polyvinyl acetates are thermoplastic polymers of vinyl acetate. Polymerization is usually carried out by suspension or emulsion polymerization.

Another suitable group of polymers are polyethylene homopolymers and copolymers. A radical polymerization of ethylene is carried out, for example, in the context of high-pressure polymerization to LDPE at pressures of around 1,400 to 3,500 bar and temperatures of 150 to 350 ^° C. The reaction is started by oxygen or peroxides. Linear or branched α,β-unsaturated olefins are suitable as comonomers.

Another suitable polymer is polyvinylidene chloride. The polymer is preferably obtained by emulsion polymerization of 1,1-dichloroethylene. Copolymers of 1,1-dichloroethylene with acrylates, methacrylates, vinyl chloride or acrylonitrile are particularly suitable.

Another suitable polymer is polyvinylidene fluoride. The polymer can be obtained by polymerizing vinylidene fluoride and can be adapted in terms of chemical and mechanical properties, for example, by copolymerizing with suitable monomers such as ethylene, acrylonitrile, acrylate esters, methacrylate esters and the like.

Also suitable are polyvinyl chlorides, such as those obtained by emulsion polymerization (E-PVC).

In the context of the present invention, the polymers mentioned can be present in the polymer dispersion according to the invention both individually and in a mixture of two or more thereof.

In a preferred embodiment of the present invention, a copolymer of vinyl acetate and ethylene (EVA copolymer) is used as the polymer in the cleaning agent according to the invention.

In a further preferred embodiment of the present invention, the cleaning agent according to the invention contains EVA or a polyurethane or a mixture thereof.

The polymers suitable for use in the cleaning agents according to the invention preferably have a softening point or a melting point of at least about 60 ^° C (measured by DSC). The upper limit for the melting or softening point is about 230 ^° C, but preferably lower, for example about 180 ^° C or about 160 ^° C.

The polymers which can be used in the cleaning agent according to the invention preferably have a melt flow index (MFI) according to ASTM D1238 or DIN 53735 of about 0.1 to about 2000 or about 1 to about 1500, in particular about 50 to about 800.

In a further embodiment of the present invention, organic compounds used in the cleaning agent according to the invention are compounds which hinder, preferably even completely block, the molecular weight build-up of the reactive compounds in the processing unit. Organic compounds suitable for this purpose are, for example, monofunctional with respect to at least one of the reactive groups of the reactive compound, forming a covalent bond.

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If, for example, a compound carrying isocyanate groups was used as the reactive compound in the processing unit to be cleaned, for example in the processing of reactive hot melt adhesives, the cleaning agent according to the invention contains, for example, a compound of the general formula R-X, in which R is a linear or branched aliphatic hydrocarbon radical, a cycloaliphatic

Hydrocarbon radical or aromatic hydrocarbon radical and X is a functional group which can react with an isocyanate group to form a covalent bond. The radical R preferably has a molecular weight which gives the corresponding compound RX a melting point of more than about 50 ^° C. Preferably, X is NHR ¹ , SH or OH, in which R ¹ is a linear or branched hydrocarbon radical having 1 to about 12 carbon atoms.

In particular, when the cleaning agent according to the invention comprises two or more organic compounds, a compound of the general formula RX can also have a melting point of less than 50 ⁰ C. The cleaning agent according to the invention then contains a mixture of two or more organic compounds, wherein at least one of the organic compounds has a melting point of more than about 50 ⁰ C.

Suitable compounds of the general formula R-X are, for example, primary and secondary amines such as diethylamine, dibutylamine, methylstearylamine, trimethylhexamethylenediamine, dodecylalkylamines such as N-methyldodecylamine, hexadecylalkylamines such as N-methylhexadecylamine, cycloalkylalkylamines, bis(dodecylamine), N-butylaniline, or monoalcohols, for example monoalcohols as already mentioned above in this text, but in particular monoalcohols with 18 to 30 C atoms.

In a further embodiment of the present invention, the cleaning agent according to the invention can contain a polymer or a mixture of two or more polymers which have a functional group X, as above

DE 200 20 Sm U

DE 200 20 Sm Ui

EN 200 20

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Suitable polymers with a correspondingly functionalized or functionalizable polymer backbone have already been described in the present text, whereby the preparation of polymers with only one functional group X is known to the person skilled in the art.

The cleaning agent according to the invention can also contain further additives, as mentioned later in the text. In addition, a cleaning agent according to the invention can also contain depolymerization catalysts, as mentioned, for example, in DE-A 197 18 065.

The cleaning agent may also contain essentially only a low molecular weight organic compound or at least a compound having a melting point of less than about 50 ^° C and a corresponding amount of a filler or a mixture of two or more fillers. It is expediently solid at room temperature (25 ^° C).

Suitable low molecular weight organic compounds or compounds with a melting point of less than about 50 ^° C include waxes, resins or plasticizers.

Suitable plasticizers in addition to the plasticizers already mentioned above are, for example, esters such as abietic acid esters, adipic acid esters, azelaic acid esters, benzoic acid esters, butyric acid esters, acetic acid esters, esters of higher fatty acids with about 8 to about 44 C atoms, esters of OH-group-bearing or epoxidized fatty acids, fatty acid esters and fats, glycolic acid esters, phosphoric acid esters, phthalic acid esters, linear or branched alcohols containing 1 to 12 C atoms, propionic acid esters, sebacic acid esters, sulfonic acid esters, thiobutyric acid esters, trimellitic acid esters, citric acid esters, and mixtures of two or more thereof. The asymmetric esters of difunctional, aliphatic or aromatic dicarboxylic acids are particularly suitable, for example the esterification product of adipic acid monooctyl ester with 2-ethylhexanol (Edenol DOA, Henkel,

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23
Düsseldorf) or the esterification product of phthalic acid with butanol.

Also suitable as plasticizers are the pure or mixed ethers of monofunctional, linear or branched C4_i6 alcohols or mixtures of two or more different ethers of such alcohols, for example dioctyl ether (available as Cetiol OE, Henkel, Düsseldorf).

Also suitable as plasticizers are end-capped polyethylene glycols such as polyethylene or polypropylene glycol di-Ci-4-alkyl ethers, in particular the dimethyl or diethyl ethers of diethylene glycol or dipropylene glycol, as well as mixtures of two or more thereof.

Waxes such as PE waxes, paraffins or micro waxes are also suitable for use.

Resins such as glycerine esters of rosin or hydrocarbon resins are also suitable for use.

The plasticizers mentioned can be used in the context of the invention together with a corresponding filler or a mixture of two or more fillers, either alone or as a mixture of two or more of them. However, the plasticizers mentioned are also suitable for use in a cleaning agent according to the invention together with one of the above-mentioned compounds with a melting point of more than about 50 ^° C or a mixture of two or more such compounds.

In a preferred embodiment of the present invention, a cleaning agent according to the invention contains two or more organic compounds, wherein at least one of the organic compounds has a functional group that can form a covalent bond with a reactive group of a reactive compound in the processing unit. Preferred cleaning agents according to the invention have, for example, the following composition:

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Option A:

Variant B:

Variant C:

· t ·

rts*··»

24

50 - 90 wt.% organic compounds without reactive groups
10-50 wt.% fillers

10-80 wt.% organic compounds without reactive functional groups

10-80 wt.% monoalcohols or monoamines or their mixture

10-80 wt.% fillers

20 - 60 wt.% polymers without reactive groups

5-50 wt.% low molecular weight organic compounds without reactive groups

20 - 60 wt.% monoalcohols or monoamines or their mixture
10-50 wt.% fillers.

The cleaners according to the invention are produced by mixing the ingredients contained in the cleaner. Preferably, the meltable components or at least some of the meltable components of the cleaner are initially introduced and melted, and then the fillers and optionally further meltable components are mixed with the melt in a suitable manner. If the melt has a suitably low viscosity, the fillers can be incorporated into the melt in a stirrer, for example, and distributed as evenly as possible. If the melt has a high viscosity, as is often the case with polymer melts, for example, the ingredients can be mixed

for example in a kneader or in other equipment suitable for mixing highly viscous melts.

The cleaning agents according to the invention are generally suitable for cleaning processing units for compounds which react with one another to increase molecular weight and which are highly viscous or solid at 20°C.

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The invention is explained in more detail below by means of examples.

Examples

Two comparison cleaners and three cleaners according to the invention were produced. Cleaning tests were carried out with these cleaners on various units for processing polyurethane hot melts.

The preparation of cleaners 1, 3 and 4 was carried out on a heatable kneader at a temperature of 160 ⁰ C. The preparation of cleaner 5 was carried out in a stirrer at room temperature.

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The composition of the cleaners can be found in Table 1:

Table 1:

Recipe
component Weight percentage of recipe ingredients in Example 2
(Comparison) Example
3 Example
4 Example
5 example 1
(Comparison) — 36 30 — EVE
Vac = 28%
MFI = 150g/10
min 50 33.9 30 20 Mono-fatty alcohol
Ci8 - C22 49.9 0.1 0.1 0.1 0.1 Chromphthalic
blue 0.1 99.9 9.9 49.9 Glyceryltribenzoa
t — 30 30 30 chalk —

EVA = ethylene vinyl acetate

Vac = vinyl acetate content in EVA

MFI = Melt Flow Index

Testing the cleaners:

Attempt 1:

Cleaning behavior in a hot melt spray gun

Purmelt QR 6200 (manufacturer: Henkel) was processed in a hot melt spray gun. The gun was then cleaned with the cleaner according to Example 1.

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Purmelt QR 6200 (manufacturer: Henkel) was processed in a hot melt spray gun. The gun was then cleaned with the cleaner as per Example 1. The cleaning effect could be observed from the blue color of the cleaner. After a rinsing time of about 5 minutes, the gun was cleaned, with a mixing phase being observed at the beginning of the cleaning process. Heavy thread formation was observed during spraying.

After cleaning was completed, Purmelt QR 6200 was added to the gun again and the gun was used for about 1 hour in normal operation for spray bonding. The gun was then cleaned with the cleaner from example 3.

The cleaning time was now only about 30 seconds. No mixing phase was observed. Furthermore, no thread formation occurred.

Attempt 2:

Cleaning behaviour in a hot melt gun

The adhesive Purmelt QR 6222 (manufacturer: Henkel) was processed in a hot melt gun with a nozzle diameter of about 2 mm. For cleaning, cleaners according to examples 1, 3 and 4 were used.

When using the cleaner according to Example 1, mixed phase formation was again observed. In some cases, mechanical removal of the polyurethane hot melt from the nozzle tip using a wooden spade was necessary.

In contrast, the nozzle tip was cleaned by the cleaners according to Examples 3 and 4 without mixed phase formation and without the need for mechanical post-cleaning.

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Attempt 3:

Cleaning behaviour regarding the tank and the application roller in a roller application device

Before cleaning, the adhesive Purmelt QR 6202 (manufacturer: Henkel) was in a Hardo hot melt adhesive applicator (manufacturer: H+H Maschinenbau GmbH) at a temperature of 150 ⁰ C. The reactive hot melt was drained from the tank. The rollers were rolled with strong cardboard paper.

The tank was then filled with granulated cleaner according to Example 3. The granulate melted at a temperature of 150 ^° C. The tank could be cleaned without any problems using the cleaner according to Example 3. The rollers rolled off without leaving any residue. The cleaner could be easily rolled onto strong cardboard paper.

Attempt 4:

Purmelt QR 3551 was applied for surface lamination on a Black Bros. Co. Model 775 roller coater machine. This machine consists of a heated steel roller and a rubber application roller that serves as an adhesive application roller. The temperature of the heating oil for the roller was 155 ⁰ C.

After the adhesive had been drained, about 500g of the cleaner according to Example 2 was added to the roller and cleaned for about 5 minutes while the rollers were running. The cleaning effect was evident from the dulling of the rubber roller. In order to obtain a completely cleaned rubber roller, the cleaning process had to be repeated twice. A total of 1.5 kg of the cleaner according to Example 2 was used. The cleaning time was about 15 minutes.

·

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After cleaning with the cleaner according to Example 2, the system was refilled with Purmelt QR 3551 and used in normal operation to carry out bonding.

Then 500 g of cleaner according to Example 5 were added to the system. After just 5 minutes, the rubber roller was completely matt and thus free of Purmelt QR 3551 residue. Compared to the cleaner according to Example 2, only about a third of the amount of cleaner was used. In addition, cleaning was completed after a third of the cleaning time.

Claims (6)

1. Cleaning agent for processing units for reactive compounds having at least one reactive functional group, containing at least one organic compound with a melting point of more than 50°C and at least one inorganic or organic filler. 2. Cleaning agent according to claim 1, characterized in that it contains the inorganic or organic filler in an amount of 5 to 70 wt.%. 3. Cleaning agent according to claim 1 or 2, characterized in that the cleaning agent comprises a particulate inorganic or organic filler whose particle diameter is such that it can pass through all passages in the processing unit. 4. Cleaning agent according to one of claims 1 to 3, characterized in that it contains a compound which is monofunctional with respect to the reactive functional group in the reactive polymer to form a covalent bond. 5. Cleaning agent according to one of claims 1 to 4, characterized in that it contains a polymer with a melting point of more than 50°C. 6. Cleaning agent according to claim 1, characterized in that the cleaning agent has a softening or melting point of more than 50°C.