WO2020152616A1

WO2020152616A1 - Polyurea-bodies and polyurea-coatings comprising improved mechanical properties

Info

Publication number: WO2020152616A1
Application number: PCT/IB2020/050526
Authority: WO
Inventors: Jan Dietrich; Tiantian DIETRICH; Wu-song LI; Wolfgang Bremser
Original assignee: Shenzhen Yuanjingang New Materials Co., Ltd.
Priority date: 2019-01-24
Filing date: 2020-01-23
Publication date: 2020-07-30
Also published as: CN113631617A; DE102019101729B4; CN113631617B; DE102019101729A1

Abstract

Provided is a process for the production of a polyurea-body or a polyurea-body part from a mixture comprising polyetheramines and isocyanates, wherein the process at least comprises the following steps: a) preparing a mixture of polyamidoamine dendrimers (PAMAM dendrimers) and at least one polyetheramine; and b) reacting the mixture obtained in process step a) and polyfunctional isocyanates to obtain the body or body part.

Description

Polvure molded bodies and coatings with improved mechanical properties

The present invention relates to a method for producing a polyurea molded body or a polyurea molded body part from a mixture comprising polyetheramines and isocyanates, the method comprising at least the following steps: a) producing a mixture of polyamidoamine dendrimers (PAMAM dendrimers) and at least one Polyetheramine; and b) reacting the mixture and polyfunctional isocyanates obtained from process step a) to obtain the shaped body or part.

The functional properties of polymers, i.e. statistical molecules made up of repeating individual building blocks, result from a complex parameter matrix which, in addition to the actual monomer composition, also shows, for example, the manufacturing conditions, process sequence, the further processing route and the use of additives. The latter can usually influence additional properties such as UV resistance, color, thermal stability and processability, whereas the former have a major influence on the basic properties of the polymers. For example, these interrelationships allow the mechanical properties of polymers to be specifically adjusted to the desired functionalities in a wide range, so that these substances provide targeted solutions for a wide range of applications in the fields of medicine, cosmetics, the building materials industry, corrosion protection and the consumer goods industry. Plastics with elastic properties are known and established, which can be obtained from a combination of at least two difunctional or polyfunctional monomers. Representatives of this class include, for example, polyesters, polyurethanes, polyamidoamines, polyamines and polyurea. The polyurea in particular is a system with a fast l Reaction kinetics known. In most applications, the kinetic boundary conditions result in a pot life in the range of seconds, which requires the use of mechanical two-component mixing systems. As a function of the monomers used, however, significantly less reactive systems can also be found. These are based on an admixture of secondary amines, which allow manual processing. The available polyureas have good to very good chemical resistance as well as high elasticity and tear resistance. Adapting the properties is particularly difficult for the fast-reacting systems, since the reaction kinetics complicate the general use of additives and the formation of equilibrium structures.

The literature contains a wide variety of options for functionalizing polyurea, either by adapting the monomer units used or by adding further additives.

For example, DE922736 C already describes a process for the preparation of polyurea derivatives, characterized in that in polyureas which contain basic amine or imino groups in the molecule, the basicity of the amino group is weakened in a manner known per se, in particular by acylation, oxalkylation or sulfalkylation or is canceled.

DE 10 20 0402 2683 A1 describes a way of controlling the properties via the monomer modules used. The process includes the production of polyurea spray elastomers by reacting a) polyisocyanates with b) amines and is characterized in that as polyisocyanates a) ai) reaction products from compounds having at least two isocyanate-reactive hydrogen atoms with 2,4'-MDI, one Mixture of 2,4'-MDI and 4,4'-MDI with a content of 2,4'-MDI of at least 50% by weight, optionally together with aii) Mixtures of MDI and polymethylene-polyphenylene polyisocyanates and / or aiii ) Isomers of MDI, which can be modified by incorporation of groups other than urethane, and as amines b) a mixture of bi) at least one polyetheramine and bii) at least one primary or secondary amine different from bi) are used as chain extenders.

DE19 914 885 (A1) describes a way of modifying the properties of thermoplastics through the use of additives. The document describes polyurethanes, Polyurethane-polyureas or polyureas in the form of dispersions which are modified with 0.1 to 15% by weight of dimethylpyrazole.

Despite the existing options for adapting the polymer properties, there is still great interest in further processes which, in particular, can specifically and reproducibly control and improve the mechanical properties of the polymers available. Furthermore, there is also an interest in improved moldings or coatings and an easy-to-use application system with the aid of which improved moldings or coatings can be obtained

It is the object of the present invention to provide a process for the preparation of polyurea with improved mechanical properties.

According to the invention, therefore, a method for fixing a polyurea shaped body or a polyurea shaped body part according to claim 1 and a polyurea shaped body according to claim 10 is proposed. Furthermore, a kit-of-parts according to claim 11 for fixing the shaped bodies and the specific use of the Kits according to claim 12 according to the invention. Advantageous further developments are specified in the subclaims. They can be combined as required, unless the context clearly indicates the opposite.

According to the invention, the object is achieved by a method for producing a polyurea molded part or a polyurea molded part from a mixture comprising polyetheramines and isocyanates, the method comprising at least the following steps: a) producing a mixture of polyamidoamine dendrimers (PAMAM dendrimers) and at least one polyetheramine; and b) The mixture and polyfunctional isocyanates obtained from process step a) are reacted to give the shaped body or part.

Surprisingly, it was found that particularly homogeneous moldings or molded body parts can be obtained via the above-mentioned process, which are also distinguished by improved mechanical properties. In particular, the process step on the PAMAM-dendrimer mixture can contribute to the fact that compared to Mixtures without this ingredient, improved tensile strength and elongation. Both the elongation at break and the tensile strength can be shifted towards higher values. Without being bound by theory, the premixing of the PAMAM dendrimers with the polyetheramines can improve the incorporation into the following process step b), which can contribute to a more homogeneous end product. In addition, the dendrimers have a particularly high number of functional groups which are in principle able to influence the degree of crosslinking in the first and second process steps. For example, the general incorporation of the PAMAM dendrimers can be controlled by partially reacting the dendrimers with the polyetheramines, resulting in a flexible reaction system whose properties can be controlled over a wide range.

Polyurea moldings or polyurea moldings are produced using the method according to the invention. Polyurea or polyurea refer to polymers that can be obtained via a polyaddition of isocyanates and amines. The polymer has at least in part the following structural element:

and is therefore structurally an aminoplast. The present polyurea molded parts are preferably “pure” polyurea molded parts, ie, according to the agreement of the Polyurea Development Association (PDA), polyurea which contains no components with hydroxyl groups. Polyurea moldings or molded body parts are either whole or parts of components, such as, for example, only the surface areas of a component which consist of or have the polyurea produced according to the invention. For example, entire components can be injection molded from the inventive Polyurea are produced or the polyurea according to the invention is used to coat all or part of a component surface.

The mixture for the production of the molded body parts comprises polyether amines and isocyanates. This means that the moldings consist largely of polyurea, whereby the polyurea is formed in addition to the PAMAM dendrimer from two main components, a hardener and resin component. The resin component is called component B in America and component A in Europe. The molded body can preferably have 70% by weight, furthermore preferably greater than 80% by weight, more preferably greater than 85% by weight, of polyurea. Furthermore, the molded article can have other conventional additives such as dyes, catalysts, rheology aids and adhesion promoters (amino-functional trialkoxysilanes), fillers (silicates), chain extenders and drying agents (e.g. molecular sieves). Preferred chain extenders can have a functionality of 2. An example of a chain extender that can be used according to the invention is dimethylmethylbenzene diamine. In the first process step a), a mixture of polyamidoamine dendrimers (PAMAM dendrimers) and at least one polyetheramine is produced.

Polyamidoamine dendrimers (PAMAM dendrimers) are made up of branched amide and amine units and the entire molecule has a more or less spherical shape. The basic structure is an ethylenamine core, to which repeated branched amidoamine structures can be attached. The surface of the dendrimer has amine functionalities. A possible PAMAM dendrimer structure results, for example, as follows:

PAMAM dendrimers of only one or different generations can be used for the mixture according to the invention. I.e. it is therefore possible for the basic structure shown above to be expanded by further grafting on further generations while increasing the molecular weight and increasing the amine functionality. The latter can be done, for example, by consecutive reaction of the basic molecule with methyl acrylates and subsequent reaction with ethylenediamine.

Polyetheramines are polymers in which primary amine groups are present at the ends of a polyether backbone. The polyether backbone is usually formed from propylene oxide, ethylene oxide or mixed ethylene / propylene oxide building blocks. The polyetheramines used can be monodisperse with a fixed molecular weight or in a more or less broad molecular weight distribution. Potentially existing side chains can furthermore be occupied by additional primary amine groups, so that polyfunctional polyether amines with more than two amine functionalities are present. Bifunctional polyetheramines can be represented using the following structural formulas, for example:

The molecular weight of the polyetheramines that can be used can vary, for example, between 200 and 5000 g / mol. The functionality of the polyetheramine can preferably be between 2 and 4, further preferably between 2 and 3. It is also possible to add further secondary polyetheramines to the mixture at this point. This can, for example, extend the reaction rate in process step b).

The mixing of the PAMAM dendrimers and the polyetheramine can take place, for example, mechanically with heating. The mixing can take place purely physically, or it is also possible for at least some of the PAMAM dendrimers to react with the polyetheramine during the mixing process to form larger molecules. The polyetheramine expediently forms the main component in the mixture. The proportion by weight of PAMAM dendrimers in relation to the polyetheramine can be, for example, in the range between 0.5% by weight and 10% by weight. The mixing time for homogeneously mixing the dendrimes into the polyetheramine can preferably be between greater than or equal to 5 minutes and 5 hours. In the second process step b), the mixture and polyfunctional isocyanates obtained from process step a) are reacted to give the shaped body or part. The mixture from process step a) is thus reacted with at least bi-functional isocyanates to obtain a covalently linked, three-dimensional network. Bi-functional isocyanates result from the general formula

where R represents both an aromatic, aliphatic or mixed hydrocarbon skeleton. Possible bi-functional isocyanates are, for example, toluene-2,4-diisocyanate (TDI), diphenylmethane diisocyanate or methylene diphenyl diisocyanate (MDI), hexamethylene diisocyanate (HDI, HMDI), polymeric diphenylmethane diisocyanate (PMDI), meta-tetramethyl-xylylene diisocyanate (TMXDI) Isophorone diisocyanate (IPDI), 4,4'-diisocyanatodicyclohexylmethane (H12MDI). It is also possible to use mixtures of these isocyanates. The quantitative ratio of the mixture produced in process step a) and the amount of isocyanate can expediently be determined from the functionality of the premix Process step a) and the isocyanate functionality can be determined. A purely arithmetical determination of the functionality is sufficient. One mole of isocyanate functionality is expediently used per mole of amine. However, the mixing ratio cannot be stoichiometric. Possible mixing ratios can be set between 1 and 4 (calculated as mole amine / mole isocyanate functionality).

In a preferred embodiment of the process, prior to process step a), the polyamidoamine dendrimers selected in a solubilizer from the group consisting of aldimines, ketimines, polyaspartates or mixtures of at least two components thereof are premixed. To obtain a premix which is as homogeneous as possible, it has proven to be particularly effective that in process step a) the PAMAM dendrimers are pre-dissolved in one of the above-mentioned substances before contact with the polyetheramines. This step can significantly simplify the mixing process and thus shorten it. The substances mentioned above act as solubilizers between the dendrimers and the polyetheramine. It has also been shown that the premix does not adversely affect the mechanical properties of the polyurea. Very good results are obtained with a weight ratio of solubilizer to PAMAM dendrimer of> 0, 1 and <5, preferably of> 0.5 and <3, furthermore preferably of> 1 and <2.5. Smaller ratios can lead to an insufficient preliminary solution of the PAMAM dendrimer in the solubilizer. Higher ratios can negatively influence the further reaction in process step b).

In a further preferred embodiment of the method, the solubilizer can be a polyaspartate. In particular, the polyaspartates as a means of solubilizing / compatibilizing the PAMAM dendrimer in the polyetheramine can contribute to particularly efficient process management. The polyaspartates are, apart from the solubilization, inert and do not have a negative influence on the mechanical properties of the available polyureas. There are particularly good processing properties with a weight ratio of polyaspartate to PAMAM dendrimer of> 0, 1 and <5, preferably of> 0.5 and <3, further preferably of> 1 and <2.5. The polyaspartate can preferably be a polymer of the following monomer units

where R 'is preferably an aliphatic cyclic radical.

In general, however, a wide variety of aspartic acid ester polyamines can be used. Aspartic acid ester polyamines are polyamines with secondary amino groups, which can be prepared, for example, by adding primary aliphatic diamines to maleic acid or fumaric acid dialkyl esters or by adding primary aliphatic amines to unsaturated oligoesters or polyesters. Suitable aspartic acid ester polyamines include, for example, aspartic acid ester polyamines with the general formula

wherein R ^{12 is} a divalent organic group (e.g., up to 40 carbon atoms), each R ^{12 is} independently an inert organic group towards isocyanate groups at temperatures of 100 ° C or less, and each R ^{13 is} independently is a lower alkyl group having 1 to 4 carbon atoms. For example, R ¹³ can be methyl, ethyl, propyl or butyl. Suitable aspartic acid ester amine resins are commercially available under the trade names Desmophen NH 1420, Desmophen NH 1520 and Desmophen NH 1220.

The use of aspartic acid ester polyamines, wherein R ^{12 is} a branched or unbranched group without cyclic structures and has less than 12, 10, 8 or 6 carbon atoms, is typically preferred for faster film curing times of 2 to 5 minutes. The inclusion of an aspartic acid ester polyamine that is unsubstituted cyclic structures can be used to extend the film curing time to 5 to 10 minutes. The use of an aspartic acid ester polyamine in which R ¹² comprises substituted cyclic structures can extend the film curing time even further. Typically, such partial ester polyamines are used only at low concentrations, in combination with another asparagine ester polyamine that provides faster film curing times.

In a further alternative of the process, the proportion by weight of PAMAM dendrimer based on the total mixture in process step b) can be greater than or equal to 0.5% by weight and less than or equal to 15% by weight. The weight ratio specified above has been found to be particularly suitable for forming polyurea molded parts that are as tensile and elastic as possible. Smaller proportions of PAMAM dendrimers can only lead to an insufficient increase in the mechanical parameters under consideration, whereas higher proportions can negatively influence the processing properties. The proportion can preferably be greater than or equal to 1.0% by weight and less than or equal to 10% by weight, furthermore preferably greater than or equal to 1.5% by weight and less than or equal to 8% by weight.

In a further preferred embodiment of the process, the PAMAM dendrimers in process step a) can be reacted with polyetheramines to form star polymers. It has also proven to be advantageous that not only a physical mixture of PAMAM dendrimers and polyetheramine is produced in process step a), but that at least some of the polyetheramines react with the PAMAM dendrimers to form higher molecular weight star polymers. This embodiment can help to achieve a significant increase in the mechanical usage properties with the lowest possible proportion of star polymers. This can help reduce process costs and process times. The polyetheramines can, for example, be mono- or bi-functional. The PAMAM dendrimers can preferably add at least two, more preferably 3, further preferably 4 polyetheramines per PAMAM dendrimer. Furthermore, the residual content of unreacted PAMAM dendrimers can preferably be less than or equal to 10 mol%, more preferably less than or equal to 5 mol%, based on the total molar amount of PAMAM dendrimers used. Especially when using star polymers, the use of solubilizers, such as polyaspartate. To form the star polymers it is also possible to work in a solvent, the solvent being removed again before process step b).

In a further alternative of the process, the polyetheramines can be at least bifunctional polyetheramines with a molecular weight greater than or equal to 200 and less than or equal to 5000 g / mol. In particular, the use of polyether amines within this molecular weight range in the process can contribute to particularly high increases in elongation at break and tensile strength. Without being bound by theory, polyetheramines in this molar mass range in particular can effect a particularly effective modification of the PAMAM dendrimers, since in the hardened network the star polymers represent a similar spatial arrangement with regard to the chain length between the network points. This is particularly because the molecular weight of the arms also corresponds to the molecular weight of the polyetheramines used.

In a preferred process variant, bifunctional polyetheramines with a molecular weight of greater than or equal to 230 g / mol and less than or equal to 4000 g / mol can be used in process step a). Polyetheramines with the above-mentioned molecular weight distribution appear to be particularly suitable for pre-dissolving the PAMAM dendrimers which can be used according to the invention. A homogeneous mixture results within short process times, which can be incorporated particularly easily in process step b). In addition, it is possible that polyetheramines with this molecular weight form a preferred geometry together with the PAMAM dendrimers, which contribute to a particularly efficient reaction with the isocyanates in process step b).

In a further preferred embodiment of the process, the polyfunctional isocyanate can be selected from the group consisting of diphenylmethane diisocyanate (MDI), toluene-2,4-diisocyanate (TDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI) or mixtures of at least two components thereof. It has been shown that the above-mentioned isocyanates can be reacted particularly efficiently with the polyetheramines modified via the PAMAM dendrimers. The result is polyurea components or component coatings, which are characterized by particularly good mechanical properties. In a preferred embodiment of the method, the polyamidoamine dendrimer can be selected from the group consisting of PAMAM of generation 0, PAMAM of generation G1, hyperbranched PAMAM of pseudogeneration GO, hyperbranched PAMAM of pseudogeneration G1 or mixtures of at least two components thereof. It has been shown in particular for the above-mentioned PAMAM dendrimers that significant increases in the desired mechanical properties of the polyurea can be obtained even with small amounts used.

Furthermore, according to the invention, a molded polyurea part is produced by the method according to the invention. The molded part or molded part regions produced by the process according to the invention, such as surface coatings, have a significantly higher tensile strength and a significantly higher elongation at break in comparison to polyurea without the addition of PAMAM dendrimer. In this respect, the components are more elastic and can withstand mechanical loads much better. For the further advantages of the molded parts, reference is made explicitly to the advantages mentioned for the method according to the invention.

Furthermore, a kit of parts according to the invention comprises at least a container for polyfunctional isocyanates, a container for a mixture of PAMAM dendrimers and polyetheramines, and a mixing and extrusion device. For the particularly efficient application of the method according to the invention, it has been found suitable to provide the user with the premix according to the invention from method step a) and the polyfunctional isocyanates from method step b) in separate containers. In use, partial flows are conveyed from the two containers and combined and mixed in the mixing device. The mixture is then extruded via the extrusion device and can be applied in the form of a molded part. The kit is also suitable for use in combination with spray devices after a static mixer as a "hot spray" or "cold spray" structure.

Likewise within the meaning of the invention is the use of the kit according to the invention in an injection molding or thick film coating process. The use of the kit according to the invention is in principle not limited and the method according to the invention can be used to produce coatings, as an elastomer, adhesive, lacquer, assembly foam, local foam and generally as a foam. Based on the special mechanical properties However, the kit is particularly suitable for the production of complete moldings in an injection molding process and for the formation of partial coatings in the context of thick film coating processes. Processes in the areas of (reactive) injection molding, reaction injection molding (RIM) and reinforced reaction injection molding (RRIM) can be carried out.

Furthermore, according to the invention, a polyurea composition comprising the

Individual components or their reaction products:

One part of amine-containing reaction mixture with the following composition

Polyetheramines: greater than or equal to 50% by weight and less than or equal to 100% by weight; Chain extenders greater than or equal to 10% by weight and less than or equal to 40% by weight;

Reactive diluents greater than or equal to 0% by weight and less than or equal to 30% by weight;

Additives greater than or equal to 0% by weight and less than or equal to 15% by weight;

PAMAM dendrimers greater than or equal to 0.1% by weight and less than or equal to 10% by weight; where the sum of the individual weight components of the amine-containing reaction mixture is 100% by weight.

An at least separate component for a period comprising up to 100% polyisocyanate. The amine-containing reaction mixture and the constituent comprising polyisocyanate can usually be mixed with one another in a ratio of 1: 1 and brought to reaction. Furthermore, according to the invention, a polyurea component is obtainable by reacting a PAMAM dendrimer / polyetheramine premix and polyfunctional isocyanates, having a proportion of PAMAM dendrimers of> 1.0% by weight and <10% by weight isolated or built into the polyurea network, with an average tensile strength greater than or equal to 18.5 MPa and less than or equal to 21 MPa and an average elongation at break greater than or equal to 220% and less than or equal to 250%, both parameters according to DIN 53504: 2017 -03 can be determined. Examples:

1 - Polyurea without the use of PAMAM dendrimers

example 1

Process step a)

A mixture of 74% by weight of polyetheramines (Huntsman Jeffamine D2000) and 26% by weight of dimethylbenzene diamine (Lonzacure DETDA 80) is produced by mechanical stirring at room temperature. The mixing process is carried out until a homogeneous premix is obtained.

Process step b)

The reaction mixture from a) is placed in a container. Another container contains the isocyanate (Huntsman Suprasec 2054). The reaction mixture and the isocyanate are sprayed with a suitable sprayer, e.g. a Graco Reactor, sprayed onto a workpiece to obtain a surface coating. A homogeneous surface is obtained. The mixing ratio of isocyanate to reaction mixture from process step a) is 1: 1.

Example 2

Process step a) A mixture of 22% by weight dimethylbenzene diamine (Lonzacure DETDA 80), 19% by weight solubilizer (Covestro Desmophen NH1420) and a mixture of two different polyetheramines, 30% by weight polyetheramine ( Huntsman SD2001), and 29% by weight. The mixing process is carried out until a homogeneous premix is obtained. Process step b) The reaction mixture from a) is placed in a container. Another container contains the isocyanate (Huntsman Suprasec 2054). The reaction mixture and the isocyanate are sprayed on a workpiece with a suitable spraying device, for example a Sulzer Mixcoat Spray, to obtain a surface coating. A homogeneous surface with a thickness of approx. Mm is obtained. The mixing ratio of isocyanate to reaction mixture from process step a) is approximately 1: 1.

2. Polyurea using PAMAM dendrimers with solubilizers

Example 3 Process Step a)

8% by weight of PAMAM Generation GO (Mw = 518) is initially introduced with mechanical stirring at 60 ° C. A polyaspartate solubilizer (Covestro Desmophen NH1420) is metered into the PAMAM so that the amount corresponds to 22% by weight, based on the total mass of the reaction mixture. The mixing process is carried out until a homogeneous premix is obtained. 21% by weight of dimethylbenzene diamine (Lonzacure DETDA 80) and a mixture of two different polyetheramines, 30% by weight of polyetheramine (Huntsman SD2001) and 28% by weight of polyetheramine (Jeffamin D2000) are added to this mixture. The mixing process is carried out until a homogeneous premix is obtained. Process step b)

The reaction mixture from a) is placed in a container. Another container contains the isocyanate (Huntsman Suprasec 2054). The reaction mixture and the isocyanate are sprayed with a suitable sprayer, e.g. a Sulzer Mixcoat Spray, sprayed on a workpiece to obtain a surface coating. A homogeneous surface with a thickness of approx. Mm is obtained. The mixing ratio of isocyanate to reaction mixture from process step a) is. 1: 1.

3. Polyurea using star polymers Process step a)

A mixture of two polyetheramines, 30% by weight of polyetheramine (Huntsman SD2001) and 29% by weight of polyetheramine (Jeffamin D2000), 22% by weight of dimethylbenzene diamine (Lonzacure DETDA 80) and 19% by weight is mixed by mechanical stirring at room temperature. -% of a polyaspartate solubilizer (Covestro Desmophen NH1420) produced. The mixing process is carried out until a homogeneous premix is obtained. Star polymers are added to this mixture in an amount which corresponds to 2% by weight of the total amine-containing mass. The star polymers are statistical reaction products made from PAMAM dendrimers and polyetheramine with n = 1, 2, 3, 4 arms per dendrimer and a molar mass of a single arm of approx. 400 g / mol. The mixing process is carried out until a homogeneous premix is obtained.

The star polymers can be produced from the PAMAM dendrimers as follows: 1 g of PAMAM G0 is dissolved in 100 ml of ethanol. With vigorous stirring, 1.93 g of methylene diphenyl isocyanate and then 3.32 g of polyoxypropylenediamine Jeffamin D400 are added at room temperature. The reaction is noticeable through an increase in viscosity and a color change (greenish to white). The solvent is then removed under vacuum. The stoichiometry, the reaction and the mechanical stirring ensure that predominantly star polymers with n = 4 arms are formed. By using a solvent, the reaction can be carried out at room temperature. The solvent also prevents cross-linking of the PAMAM by bi-functional isocyanates, which can therefore be added without protective groups. As a solvent e.g. Ethanol are used. Although ethanol is not usually used together with isocyanates, it is shown that this is not a problem in an isocyanate-amine reaction. The kinetics of the isocyanate-amine reaction is very fast, and thus outweighs the isocyanate-hydroxy reaction.

Process step b) The reaction mixture from a) is placed in a container. Another container contains the isocyanate (Huntsman Suprasec 2054). The reaction mixture and the isocyanate are sprayed on a workpiece with a suitable spraying device, for example a Sulzer Mixcoat Spray, to obtain a surface coating. A homogeneous surface is obtained. The mixing ratio of isocyanate to reaction mixture from process step a) is 1: 1.

Results

Table 1: The tensile strength and elongation at break are determined in accordance with DIN 53504: 2017.

Claims

1 . A method for producing a polyurea molded body or a polyurea molded part from a mixture comprising polyether amines and isocyanates, characterized in that the method comprises at least the following steps: a) preparing a mixture of polyamidoamine dendrimers (PAMAM dendrimers) and at least one polyetheramine; and

b) The mixture and polyfunctional isocyanates obtained from process step a) are reacted to give the shaped body or part.

2. The method according to claim 1, wherein before step a) the

Polyamidoamine dendrimers in a solubilizer selected from the group consisting of aldimines, ketimines, polyaspartates or mixtures of at least two components thereof are premixed.

3. The method of claim 2, wherein the solubilizer is a polyaspartate.

4. The method according to any one of the preceding claims, wherein the proportion by weight of PAMAM dendrimer based on the total mixture in process step b) is greater than or equal to 0.5% by weight and less than or equal to 15% by weight.

5. The method according to any one of the preceding claims, wherein the PAMAM dendrimers in step a) are reacted with polyetheramines to form star polymers.

6. The method according to any one of the preceding claims, wherein the polyetheramines are at least bi-functional polyetheramines with a molecular weight of greater than or equal to 200 and less than or equal to 5000 g / mol.

7. The method according to any one of the preceding claims, wherein in step a) bifunctional polyetheramines with a molecular weight of greater than or equal to 230 g / mol and less than or equal to 4000 g / mol are used.

8. The method according to any one of the preceding claims, wherein the polyfunctional isocyanate is selected from the group consisting of

Diphenylmethane diisocyanate (MDI), toluene-2,4-diisocyanate (TDI),

Hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI) or mixtures of at least two components thereof.

9. The method according to any one of the preceding claims, wherein the polyamidoamine dendrimer is selected from the group consisting of PAMAM of generation 0, PAMAM of generation G1, hyperbranched PAMAM of the pseudogeneration GO, hyperbranched PAMAM of the pseudogeneration G1 or mixtures of at least two components thereof.

10. Polyurea molded part produced by a method according to any one of claims 1-9.

1 1. Kit of parts at least comprising a container for polyfunctional isocyanates, a container for a mixture of PAMAM dendrimers and polyether amines and a mixing and extrusion device.

12. Use of a kit according to claim 1 1 in an injection molding or

Thick film coating process.