Polyurea compositions having low monomeric diisocyanate content

Abstract

The present invention relates to a polyurea composition having a monomeric diisocyanate content of not more than 0.5% by weight. The composition comprises a first component A containing a primary aromatic diamine A1 and a second component B containing a polyether polyurethane polymer B1 containing isocyanate groups and having a monomeric diisocyanate content of not more than 0.5% by weight, and an aliphatic polyisocyanate B2 having an NCO content of 8 to 25% by weight. The polyurea composition according to the invention has very good processability, a long open time, and rapid curing. This results in an elastic material having high tensile strength, high stretchability, and a high modulus of elasticity, which also exhibits very good adhesion and high stability to heat and moisture.

Description

Technical Field

[0001] The present invention relates to polyurea compositions and their use as coatings. Existing technology

[0002] Polyurea compositions that crosslink and cure to form elastomers by reaction of isocyanate groups with amine groups are particularly useful as coatings in the construction industry, for example as floor coatings or roof sealants. Due to their good adhesion and elasticity, they can gently absorb and overcome forces acting on the substrate, for example, caused by vibrations or temperature fluctuations.

[0003] Such polyurea compositions contain conventional isocyanate-containing polymers as binders, prepared by reacting polyols with monomeric diisocyanates. Due to chain extension reactions, the resulting polymers contain residual monomeric diisocyanate contents, typically ranging from 1% to 3% by weight. Monomeric diisocyanates are potentially harmful to health. Formulations containing monomeric diisocyanates, particularly at concentrations above 0.1% by weight, must carry hazard symbols and warnings on labels and data sheets, and in some countries may only be sold and used under regulatory restrictions.

[0004] Various approaches exist to produce isocyanate-group-containing polymers with a low monomeric diisocyanate content. The most attractive approach, with respect to product properties, is to use an excess of monomeric diisocyanate in the preparation of the polymer and then remove the majority of the unconverted monomeric diisocyanate by suitable separation methods, in particular by distillation. The polymers obtained by this process have relatively low viscosities and low residual monomeric diisocyanate contents. Polyurea compositions containing such polymers have very good processability, but exhibit slow curing, reduced strength, and weaknesses in developing adhesion to substrates.

[0005] DE 60032938 describes the preparation of castable polyurethane prepolymers containing a lower or reduced content or amount of unconverted MDI monomer.

[0006] DE 102010028269 discloses reactive one-component or two-component adhesives which are in the form of pastes at room temperature and are based on polyurethane prepolymers with a low content of monomeric isocyanates and contain viscosity-reducing reactive compounds.

[0007] DE 102007025659 describes NCO prepolymers having a low content of free monomeric diisocyanates, a process for their preparation and the use of the NCO prepolymers prepared in a single step. SUMMARY OF THE INVENTION

[0009] It was therefore an object of the present invention to provide polyurea compositions having a low content of monomeric diisocyanates which overcome the disadvantages of the prior art.

[0010] This object is achieved by a polyurea composition as described below. The polyurea composition comprises at least one polyether polyurethane polymer containing isocyanate groups and having a low monomeric diisocyanate content and at least one aliphatic polyisocyanate. The composition of the present invention has a monomeric diisocyanate content of less than 0.5%; therefore, it can be handled safely even without special safety precautions and can be sold in many countries without hazard labels.

[0011] The compositions of the present invention surprisingly have fast cure rates and long open times / workability, and after cure have high tensile strength and high elastic modulus, which are very advantageous for many applications.

[0012] Unexpectedly, the polyurea compositions of the invention also exhibit a higher elastic modulus and a higher elongation at break at extended open time compared to corresponding compositions with a high monomer content. These advantageous properties could not be expected from the prior art.

[0013] The polyurea compositions of the present invention have good processability, a long open time, and rapid curing. This results in an elastic material with high tensile strength, high ductility, a high elastic modulus, good adhesion properties, and high stability to heat and moisture. Furthermore, well-applicable compositions can be efficiently prepared with no or very low amounts of organic solvents. The polyurea compositions are particularly suitable for use as elastic coatings. Detailed Description of the Invention

[0015] The present invention provides a polyurea composition having a monomeric diisocyanate content of no more than 0.5 wt%, comprising:

[0016] The first component A comprises:

[0017] at least one primary aromatic diamine A1 selected from diethyltoluenediamine (DETDA), in particular 3,5-diethyltoluene-2,4-diamine and 3,5-diethyltoluene-2,6-diamine, 4,4′-methylenebis(2,6-diethyl)aniline (MDEA), 4,4′-methylenebis(2,6-diisopropyl)aniline (MDIPA), 4,4′-methylenebis(3-chloro-2,6-diethyl)aniline (MCDEA) and dimethylthiotoluenediamine (DMTDA), in particular 3,5-dimethylthio-2,6-toluenediamine and 3,5-dimethylthio-2,4-toluenediamine;

[0018] and a second component B comprising:

[0019] at least one polyether polyurethane polymer B1 comprising isocyanate groups and having a monomeric diisocyanate content of not more than 0.5% by weight, which is obtained by reacting a monomeric diisocyanate with at least one polyether polyol in an NCO / OH ratio of at least 3 / 1, with subsequent removal of the majority of the monomeric diisocyanate by suitable separation methods, wherein the monomeric diisocyanate is 4,4′-diphenylmethane diisocyanate and optionally with a proportion of 2,4′-diphenylmethane diisocyanate and / or 2,2′-diphenylmethane diisocyanate, and

[0020] at least one aliphatic polyisocyanate B2 having an NCO content of 8 to 25% by weight.

[0021] The weight ratio of B1 / B2 is 5-50, especially 7.5-30, preferably 8-25.

[0022] "Monomeric diisocyanate" refers to an organic compound having two isocyanate groups separated by a divalent hydrocarbon radical having from 4 to 15 carbon atoms.

[0023] "Polyether polyurethane polymer" refers to a polymer having ether groups as repeating units and additionally containing urethane groups.

[0024] Substance names beginning with "poly", such as polyol, refer to substances that formally contain two or more of the functional groups appearing in their name per molecule.

[0025] "NCO content" refers to the content of isocyanate groups (% by weight).

[0026] "Molecular weight" refers to the molar mass (g / mole) of a molecule or a molecular residue. "Average molecular weight" refers to the number average molecular weight (Mn) of a polydisperse mixture of oligomeric or polymeric molecules or molecular residues. It is determined by gel permeation chromatography (GPC) using polystyrene standards, particularly with tetrahydrofuran as the mobile phase and a refractive index detector.

[0027] A substance or composition is said to be "storage-stable" or "storable" when it can be stored in a suitable container at room temperature for an extended period of time, generally at least 3 months to 6 months or more, without its application or use properties being altered by storage to an extent relevant to its use.

[0028] "Room temperature" refers to a temperature of 23°C.

[0029] All industry standards and specifications mentioned in this document relate to the versions in effect on the filing date of the initial application.

[0030] Unless otherwise indicated, weight percent (wt%), abbreviated as wt%, refers to the proportion by mass of a component of a composition or molecule based on the total composition or total molecules. The terms "mass" and "weight" are used synonymously in this document.

[0031] "Primary hydroxyl" refers to an OH group attached to a carbon atom having two hydrogen atoms.

[0032] "Primary amino" refers to an NH2 group attached to one organic group, and "secondary amino" refers to an NH2 group attached to two organic groups, which may also together form a common portion of a ring.

[0033] So-called "two-component" compositions are compositions in which the ingredients of the composition are present in two different components that are stored in separate containers and are not mixed with one another until shortly before or during application of the composition.

[0034] "Open time" refers to the time, after mixing of the components, that the composition can be applied without loss of final properties.

[0035] The two components A and B are stored in separate containers and are mixed with one another only shortly before or during application of the polyurea composition. Such compositions are also referred to as "two-component" compositions.

[0036] The polyurea composition has a monomeric diisocyanate content of no greater than 0.5 wt%, preferably no greater than 0.3 wt%, no greater than 0.2 wt%, more preferably no greater than 0.1 wt%, and most preferably less than 0.1 wt%.

[0037] The first component A comprises at least one primary aromatic diamine A1 selected from diethyltoluenediamine (DETDA), in particular 3,5-diethyltoluene-2,4-diamine and 3,5-diethyltoluene-2,6-diamine, 4,4′-methylenebis(2,6-diethyl)aniline (MDEA), 4,4′-methylenebis(2,6-diisopropyl)aniline (MDIPA), 4,4′-methylenebis(3-chloro-2,6-diethyl)aniline (MCDEA) and dimethylthiotoluenediamine (DMTDA), in particular 3,5-dimethylthio-2,6-toluenediamine and 3,5-dimethylthio-2,4-toluenediamine.

[0038] Particularly preferably, the primary aromatic diamine A1 is DMTDA, most preferably 3,5-dimethylthio-2,6-toluenediamine or 3,5-dimethylthio-2,4-toluenediamine, especially mixtures of these isomers. Such mixtures are commercially available, for example as 300 (from Albemarle).

[0039] The second component B contains at least one polyether polyurethane polymer B1, which comprises isocyanate groups and has a monomeric diisocyanate content of not more than 0.5% by weight, obtained by reacting a monomeric diisocyanate with at least one polyether polyol in an NCO / OH ratio of at least 3 / 1, followed by removal of the majority of the monomeric diisocyanate by suitable separation methods, wherein the monomeric diisocyanate is 4,4′-diphenylmethane diisocyanate and optionally with a proportion of 2,4′-diphenylmethane diisocyanate and / or 2,2′-diphenylmethane diisocyanate.

[0040] The above-mentioned polyether polyurethane polymer containing isocyanate groups can also be referred to as polyurethane prepolymer.

[0041] The polyether polyurethane polymer containing isocyanate groups preferably has a monomeric diisocyanate content of not more than 0.3% by weight, 0.2% by weight, in particular not more than 0.1% by weight, most preferably less than 0.1% by weight.

[0042] Preferably, the polyether polyurethane polymer containing isocyanate groups has an average molecular weight M of 1'000 to 8'000 g / mol, preferably 1'500 to 6'000 g / mol, in particular 2'000 to 4'000 g / mol. n .

[0043] The NCO content of the isocyanate group-containing polyether polyurethane polymer B1 is preferably from 1 to 8.4% by weight, particularly preferably from 1.4 to 5.6% by weight, in particular from 2 to 4.2% by weight.

[0044] This is advantageous because a longer open time / processability and better mechanical properties are achieved, especially with regard to the modulus of elasticity and elongation at break. This can be achieved, for example, in Figure 1 This is clear from the comparison between Z4 and Z10 in Table 2.

[0045] The polyether polyurethane polymer containing isocyanate groups preferably has a 1,2-ethyleneoxy group, a 1,2-propyleneoxy group, a 1,3-propyleneoxy group, a 1,2-butyleneoxy group or a 1,4-butyleneoxy group as a repeating unit.

[0046] More preferably, the repeating unit mainly contains or only contains 1,2-propyleneoxy groups.

[0047] The monomeric diisocyanate used in the reaction is 4,4'-diphenylmethane diisocyanate (4,4'-MDI), optionally with a portion of 2,4'-diphenylmethane diisocyanate and / or 2,2'-diphenylmethane diisocyanate.

[0048] Particularly preferred is 4,4'-MDI. This 4,4'-MDI is of a quality that contains only a small fraction of 2,4'-diphenylmethane and / or 2,2'-diphenylmethane diisocyanate and is solid at room temperature. It enables the production of polyurea compositions with particularly high strength, ductility, and elasticity.

[0049] The 4,4′-MDI is preferably distilled and has a purity of at least 95%, in particular at least 97.5%.

[0050] Commercially available 4,4'-diphenylmethane diisocyanate of this quality is, for example 44MC (purchased from Covestro) or MRSS or ME (available from BASF) or 1400 (purchased from Huntsman).

[0051] The average molecular weight M of polyether polyol n It is preferably 400-5'000 g / mol, more preferably 1'000-3'000 g / mol.

[0052] The OH value of the polyether polyol is preferably 20-280 mg KOH / g, preferably 35-120 mg KOH / g, more preferably 50-60 mg KOH / g.

[0053] The polyether polyols preferably have an average OH functionality of 1.7-3, in particular 1.8-2.

[0054] Suitable polyether polyols are polyoxyalkylene diols and / or polyoxyalkylene triols, in particular the polymerization products of ethylene oxide or 1,2-propylene oxide or 1,2- or 2,3-butylene oxide or oxetane or tetrahydrofuran or mixtures thereof, which can be polymerized with the aid of starter molecules having two or three active hydrogen atoms, such as, in particular, water, ammonia or compounds having a plurality of OH or NH groups, such as ethane-1,2-diol, Propane-1,2- or -1,3-diol, neopentyl glycol, diethylene glycol, triethylene glycol, the isomeric dipropylene glycol or tripropylene glycol, the isomeric butanediols, pentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, undecanediol, cyclohexane-1,3- or -1,4-dimethanol, bisphenol A, hydrogenated bisphenol A, 1,1,1-trimethylolethane, 1,1,1-trimethylolpropane, glycerol or aniline or mixtures of the aforementioned compounds.

[0055] Particularly preferred are polyoxypropylene diols, polyoxypropylene triols, or ethylene oxide-terminated polyoxypropylene diols or triols. These are polyoxyethylene-polyoxypropylene mixed polyols, which are obtained, in particular, by further alkoxylating polyoxypropylene diols or triols with ethylene oxide after the polypropoxylation reaction, and thus ultimately have primary hydroxyl groups. Polyoxypropylene diol is particularly preferred.

[0056] Preferred polyether polyols have an unsaturation level of less than 0.02 mEq / g, in particular less than 0.01 mEq / g.

[0057] Particular preference is given to polyoxypropylene glycols having an OH value of 35 to 120 mg KOH / g, 40 to 80 mg KOH / g, in particular 50 to 60 mg KOH / g.

[0058] The NCO / OH ratio in the reaction between monomeric diisocyanates and polyether polyols is preferably in the range of 3 / 1 to 10 / 1, more preferably in the range of 3 / 1 to 8 / 1, in particular in the range of 4 / 1 to 7 / 1.

[0059] The reaction is preferably carried out at a temperature of 20 to 160° C., in particular 40 to 140° C., with exclusion of moisture, optionally in the presence of a suitable catalyst.

[0060] After the reaction, the monomeric diisocyanate remaining in the reaction mixture is removed by means of suitable separation methods up to the stated residual content.

[0061] A preferred separation method is distillation, in particular thin-film distillation or short-path distillation, preferably under reduced pressure.

[0062] Particular preference is given to a multistage process in which the monomeric diisocyanate is removed in a short-path evaporator at a jacket temperature of 160 to 200° C. and a pressure of 0.001 to 0.5 mbar.

[0063] The monomeric diisocyanate is preferably reacted with the polyether polyol and subsequently the majority of the monomeric diisocyanate remaining in the reaction mixture is removed without the use of solvents or entrainers.

[0064] In the reaction, the OH groups of the polyether polyol react with the isocyanate groups of the monomeric diisocyanate. This also leads to so-called chain extension reactions, i.e., reactions of the OH groups and / or isocyanate groups of the reaction product between the polyol and the monomeric diisocyanate. The higher the NCO / OH ratio selected, the less chain extension reactions occur and the lower the polydispersity, and therefore the lower the viscosity of the resulting polymer. A measure of the chain extension reaction is the average molecular weight of the polymer, or the width and distribution of the peaks in a GPC analysis. Another measure is the effective NCO content of the monomer-free polymer relative to the theoretical NCO content calculated from the reaction of each OH group with the monomeric diisocyanate.

[0065] The NCO content of the polyether polyurethane polymer is preferably at least 80%, in particular at least 85%, of the theoretical NCO content, calculated from the addition of one mole of monomeric diisocyanate per mole of OH groups of the polyether polyol. Such polyether polyurethane polymers have a particularly low viscosity.

[0066] Particularly preferred polyether polyurethane polymers have an NCO content of 1 to 8.4% by weight, more preferably 1.4 to 5.6% by weight, in particular 2 to 4.2% by weight, and a monomeric diisocyanate content of not more than 0.3% by weight, in particular not more than 0.2% by weight, and are obtained by reacting 4,4′-MDI with polyoxypropylene glycol having an OH number of 35 to 120 mg KOH / g, 40 to 80 mg KOH / g, in particular 50 to 60 mg KOH / g.

[0067] The second component B comprises at least one aliphatic polyisocyanate B2 having an NCO content of 8 to 25% by weight, preferably 10 to 22.5% by weight, in particular 10 to 21% by weight, more preferably 15 to 21% by weight.

[0068] "Aliphatic isocyanate" refers to an isocyanate in which the isocyanate group is directly attached to an aliphatic carbon atom. For this reason, such isocyanate groups are referred to as "aliphatic isocyanate groups."

[0069] Preferably, the aliphatic polyisocyanate B2 is derived from 1,6-hexamethylene diisocyanate (HDI) or isophorone diisocyanate (IPDI), in particular an oligomer, polymer and / or derivative of HDI.

[0070] The aliphatic polyisocyanates B2 preferably have an average NCO functionality of at least 2.1. They particularly preferably have an average NCO functionality of 2.1 to 4.0, preferably 2.1 to 3.0, in particular 2.1 to 2.6.

[0071] This is particularly beneficial for higher elongation at break, as can be seen in Table 1, for example, by comparing Z3-Z6 with Z7-Z8.

[0072] Furthermore, it may be advantageous if the aliphatic polyisocyanates B2 have an average NCO functionality of from 2.2 to 3.0, in particular from 2.3 to 2.8, particularly preferably from 2.4 to 2.6.

[0073] This contributes in particular to a higher tensile strength. This can be seen, for example, in Table 1 by comparing Z5-Z6 with Z3-Z4 and Z7-Z8.

[0074] Furthermore, it may be advantageous when the aliphatic polyisocyanates B2 have an average NCO functionality of from 2.2 to 4.0, in particular from 2.4 to 3.8, more preferably from 2.8 to 3.6.

[0075] This contributes in particular to a higher modulus of elasticity. This can be seen, for example, in Table 1 by comparing Z7-Z8 with Z5-Z6 and Z3-Z4.

[0076] Aliphatic polyisocyanates B2 particularly advantageously include oligomers, polymers and / or derivatives derived from HDI, in particular polymers derived from HDI, especially those having an average NCO functionality of from 2.1 to 2.6.

[0077] They preferably have a viscosity at 23° C. of 300 to 2000 mPa·s, preferably 400 to 1500 mPa·s, in particular 500 to 1350 mPa·s, in accordance with DIN EN ISO 3219 / A.3.

[0078] Among them, commercially available products are particularly suitable, such as 2863XP, 2860XP and N 3900 (both from Covestro).

[0079] It is also more advantageous when the monomeric diisocyanate content of the aliphatic polyisocyanate B2 is not more than 0.75% by weight, not more than 0.5% by weight, not more than 0.4% by weight and in particular not more than 0.3% by weight.

[0080] The weight ratio of B1 / B2 is 5-50, especially 7.5-30, preferably 8-25.

[0081] This is advantageous because it results in a longer open time / processability, a higher curing rate, and better mechanical properties, especially in terms of elastic modulus and tensile strength. This can be clearly seen, for example, by comparing Z3-Z8 with Z1 in Table 1. The composition based on P1 alone (Z1), while having very long processability, has a low curing rate and also has insufficient mechanical properties, especially in terms of elastic modulus and tensile strength.

[0082] It may be advantageous when the weight ratio of B1 / B2 is in the range of 7 to 30, 7 to 15, in particular 7 to 12, preferably 8 to 10. This is advantageous since a higher curing rate and a higher modulus of elasticity are thereby achieved.

[0083] It may be more advantageous when the weight ratio B1 / B2 is in the range of 7 to 30, 10 to 30, in particular 15 to 25, preferably 17 to 22. This is advantageous because a longer open time and a higher elongation at break are thereby achieved.

[0084] It may further be advantageous if the sum of the NCO groups not originating from B1 or B2, based on the sum of all NCO groups of the polyurea composition, is ≤10%, ≤5%, in particular ≤2%, particularly preferably ≤1% and most preferably ≤0.5%.

[0085] The polyurea composition may contain other ingredients.

[0086] The first component A may comprise further compounds suitable as curing agents, in particular further amines, amino alcohols, chain extenders such as 1,4-butanediol or polyols, and amines having blocked amino groups such as aldimines, ketimines or enamines.

[0087] Component A preferably contains only small amounts of such further curing agents. In particular, the content of groups which are not derived from the primary aromatic diamine A1 and which are reactive toward NCO groups is less than 50 mol %, preferably less than 20 mol %, in particular less than 10 mol %, based on all the groups reactive toward NCO groups in component A.

[0088] The second component B may contain other isocyanate-containing components, in particular other polymers or polyisocyanates. Preferably, component B contains only small amounts of other isocyanate-containing components. In particular, the content of NCO groups not originating from the polyether polyurethane polymer B1 or the aliphatic polyisocyanate B2 is less than 25%, preferably less than 10%, and in particular less than 5%, based on all NCO groups in component B.

[0089] It may further be advantageous if the sum of the NCO groups not originating from B1 or B2 is ≤10%, ≤5%, in particular ≤2%, particularly preferably ≤1%, most preferably ≤0.5%, based on the sum of all NCO groups of the polyurea composition.

[0090] Preferably, the polyurea composition additionally contains at least one further component selected from fillers, inorganic or organic pigments, flame retardants and additives.

[0091] The proportion of fillers is preferably 5 to 30% by weight, in particular 10 to 25% by weight, more preferably 10 to 20% by weight, based on the total weight of the polyurea composition.

[0092] The proportion of inorganic or organic pigments, flame retardants and additives is preferably 2-10% by weight, in particular 3-8% by weight, more preferably 3-5% by weight, based on the total weight of the polyurea composition.

[0093] Preferably, the inorganic or organic pigment is titanium dioxide, chromium oxide or iron oxide.

[0094] The flame retardant substances are preferably selected from the group consisting of aluminum hydroxide, magnesium hydroxide, organic phosphates, such as, in particular, triethyl phosphate, tricresyl phosphate, triphenyl phosphate, diphenylcresyl phosphate, isodecyl diphenyl phosphate, tris(1,3-dichloro-2-propyl) phosphate, tris(2-chloroethyl) phosphate, tris(2-ethylhexyl) phosphate, tris(chloroisopropyl) phosphate, tris(chloropropyl) phosphate, isopropylated triphenyl phosphate, mono-, di- or tris(isopropylphenyl) phosphate with varying degrees of isopropylation, resorcinol-bis(diphenyl phosphate), bisphenol A-bis(diphenyl phosphate) and ammonium polyphosphate.

[0095] Additives are especially additives selected from wetting agents, leveling agents, defoamers, deaerators, stabilizers against oxidation, heat, light or UV radiation, and biocides.

[0096] Suitable fillers are especially selected from ground or precipitated calcium carbonate, optionally coated with fatty acids (especially stearates), barite, quartz powder, quartz sand, dolomite, wollastonite, calcined kaolin, sheet silicates such as mica or talc, zeolites, silica, silicon dioxide including finely divided silicon dioxide from pyrogenic processes, cement, gypsum, fly ash, industrially produced carbon black, graphite, metal powders, for example of aluminum, copper, iron, silver or steel, PVC powder or hollow beads.

[0097] Preferred are calcium carbonate, optionally coated with fatty acids, especially stearates, and calcined kaolin.

[0098] In the preparation of the polyurea compositions of the invention, the monomeric diisocyanate content is optionally further reduced by reaction with moisture present when the isocyanate group-containing polyether polyurethane polymer is mixed with the other components of the composition, in particular fillers.

[0099] The polyurea composition preferably contains:

[0100] 3 to 15% by weight, 5 to 12% by weight, in particular 7 to 10% by weight, of a primary aromatic diamine A1 selected from diethyltoluenediamine, in particular 3,5-diethyltoluene-2,4-diamine and 3,5-diethyltoluene-2,6-diamine, 4,4′-methylenebis(2,6-diethyl)aniline (MDEA), 4,4′-methylenebis(2,6-diisopropyl)aniline (MDIPA), 4,4′-methylenebis(3-chloro-2,6-diethyl)aniline (MCDEA) and dimethylthiotoluenediamine (DMTDA), in particular 3,5-dimethylthio-2,6-toluenediamine and 3,5-dimethylthio-2,4-toluenediamine,

[0101] 55 to 90% by weight, 60 to 90% by weight, 70 to 85% by weight, in particular 75 to 85% by weight, of a polyether polyurethane polymer B1 containing isocyanate groups and having a content of not more than 0.5% by weight of monomeric diisocyanates,

[0102] 2 to 15% by weight, 3 to 10% by weight, in particular 4 to 8% by weight, of an aliphatic polyisocyanate B2 having an NCO content of 8 to 25% by weight,

[0103] - 5 to 30% by weight, in particular 10 to 25% by weight, more preferably 10 to 20% by weight, of fillers,

[0104] - 2 to 10% by weight, in particular 3 to 8% by weight, more preferably 3 to 5% by weight, of inorganic or organic pigments, flame retardants and additives.

[0105] The polyurea composition preferably consists of more than 80% by weight, more than 90% by weight, more than 95% by weight, more than 98% by weight, and especially more than 99% by weight of the components listed above for the polyurea composition.

[0106] In order to make such products easily applicable, for example, considerable proportions of volatile organic solvents can be added to reduce the viscosity and thus ensure good applicability. However, this is disadvantageous for environmental and health reasons, as the compositions have high VOC emissions.

[0107] Preferably, the polyurea composition contains less than 5 wt%, less than 2 wt%, less than 1 wt%, less than 0.5 wt%, in particular less than 0.1 wt% of solvent, based on the total weight of the polyurea composition.

[0108] These solvents are, in particular, acetone, methyl ethyl ketone, methyl n-propyl ketone, diisobutyl ketone, methyl isobutyl ketone, methyl n-amyl ketone, methyl isoamyl ketone, acetylacetone, isopropylidene ether, cyclohexanone, methylcyclohexanone, ethyl acetate, propyl acetate, butyl acetate, n-butyl propionate, diethyl malonate, 1-methoxy-2-propyl acetate, ethyl-3-ethoxypropionate, diisopropyl ether, diethyl ether, dibutyl ether, diethylene glycol diethyl ether, ethylene glycol diethyl ether , ethylene glycol monopropyl ether, ethylene glycol mono(2-ethylhexyl) ether, acetals such as, in particular, methylal, acetal, propionate, butyral, 2-ethylhexane acetal, dioxolane, glycerol formal or 2,5,7,10-tetraoxaundecane (TOU), and also toluene, xylene, heptane, octane, naphtha, white spirit, petroleum ether or gasoline, and also dichloromethane, propylene carbonate, butyrolactone, N-methylpyrrolidone or N-ethylpyrrolidone.

[0109] This is advantageous for environmental and health reasons, since the composition thereby has low VOC emissions.It has been found that, surprisingly, the present invention achieves low viscosities without the above-mentioned solvents.

[0110] In the polyurea composition, the ratio of isocyanate groups to groups reactive toward isocyanate groups, in particular amino groups, is preferably in the range from 1 to 1.2, preferably in the range from 1 to 1.1.

[0111] Preferably, the composition has a viscosity of 1'000-20'000 cPs, preferably 2'000-15'000 cPs, in particular 3'000-12'000 cPs, measured 120 seconds after mixing the two components using a Brookfield HBDV-II+ viscometer, using spindle 7 at 23° C. and 50% relative humidity, in particular at 100 rpm.

[0112] The first and second components of the composition are prepared separately. The ingredients of the individual components are mixed with one another while excluding moisture to obtain a macroscopically homogeneous liquid. Each component is stored in a separate moisture-proof container. Suitable containers include, in particular, drums, containers, pails, barrels, cans, bags, jars, or bottles.

[0113] To use the composition, the two components are mixed shortly before or during application. The mixing ratio is preferably selected so that the isocyanate-reactive groups are present in a suitable ratio to the isocyanate groups, as described above. The ratio of the components is generally in the range of about 1:1 to 1:20, in particular 1:2 to 1:10.

[0114] The two components are mixed with the aid of a suitable stirring device, such as a twin-shaft mixer, with the components appropriately premixed in the correct mixing ratio. Continuous machine processing is also possible with the aid of two-component metering systems with static or dynamic mixing of the components. During mixing, it is important to ensure that the two components are mixed with maximum homogeneity. If mixing precedes application, care must be taken to ensure that too much time does not elapse between mixing the components and application, as this could lead to problems such as poor flow or delayed or incomplete adhesion to the substrate. Mixing is typically carried out at ambient temperature, typically between approximately 5 and 50°C, preferably between approximately 10 and 35°C.

[0115] As the two components are mixed, curing begins via a chemical reaction. Here, the NCO-reactive groups present, particularly amino groups, react with the isocyanate groups present. As a result of these reactions, the composition cures to form a solid material. This process is also known as crosslinking.

[0116] The invention also relates to a cured composition obtained from a composition as described above, after mixing and curing the two components mentioned above.

[0117] In application, the freshly mixed, still liquid composition can be applied to the surface as a coating. The composition is preferably applied by pouring it onto the substrate and then spreading it over the surface until the desired layer thickness is achieved (e.g., by means of a roller, slide, toothed scraper, spatula, brush, or bristle brush).

[0118] The present invention also provides a coating or sealing method, comprising the following steps:

[0119] (i) mixing the components of the polyurea composition,

[0120] (ii) applying the mixed polyurea composition to at least one substrate,

[0121] (iii) curing the composition.

[0122] The polyurea composition is preferably mixed and applied at ambient temperature, especially in the range of about -10 to 50°C, preferably in the range of -5 to 45°C, especially 0 to 40°C.

[0123] The polyurea composition is preferably likewise cured at ambient temperature.

[0124] Polyurea compositions have a long processing time (open time) and a fast cure.

[0125] The cured polyurea composition preferably has a tensile strength of at least 5 MPa, at least 8 MPa, in particular at least 10 MPa, as determined as described in the examples.

[0126] The cured polyurea composition also preferably has an elongation at break of at least 300%, at least 500%, and in particular at least 700%, as determined as described in the examples.

[0127] The cured polyurea composition also preferably has an elastic modulus of at least 8 MPa, in particular 9 to 40 MPa, preferably 10 to 20 MPa, as determined as described in the examples.

[0128] Polyurea compositions are preferably used as elastomeric coatings.

[0129] The polyurea compositions are particularly suitable as coatings for protecting and / or sealing building structures or parts thereof, in particular for balconies, terraces, roofs, in particular flat roofs or slightly sloping roof areas or roof gardens, or for use under tiles or ceramic panels in wet rooms or kitchens inside buildings.

[0130] As a coating, it can be distributed flatly, for example, by means of rollers, slides, toothed blades or spatulas until the desired layer thickness is achieved. The resulting layer thickness is generally 0.5 to 3 mm, in particular 1.0 to 2.5 mm.

[0131] Suitable substrates which can be coated with the polyurea composition are, in particular:

[0132] – concrete, mortar, cement mortar, fibre cement, in particular fibre cement board, bricks, tiles, plaster, in particular plasterboard or waterless screed (Estrich), or natural stone such as granite or marble;

[0133] – Repair or levelling compounds based on PCC (polymer-modified cement mortar) or ECC (epoxy-modified cement mortar);

[0134] – metals or alloys such as aluminium, copper, iron, steel, non-ferrous metals, including metals or alloys with surface finishing such as zinc- or chromium-plated metals;

[0135] – tar or bitumen;

[0136] If desired, the substrate can be pretreated before application, in particular by physical and / or chemical cleaning methods or by application of an activator or primer.

[0137] By applying and curing the polyurea composition, or by coating or sealing, an article sealed or coated with the composition is obtained. The article may be a building structure or a part thereof, in particular a building structure above or below ground level, a balcony or a stairwell.

[0138] Therefore, the present invention also provides an article obtained by the coating or sealing method.

[0139] Polyurea compositions have advantageous properties. Due to their low monomeric diisocyanate content, they can be handled safely even without special safety precautions and do not require any hazard marking associated with monomeric diisocyanates. They are very adaptable and have a long processing time (open time) and surprisingly fast curing. This results in an elastic material with surprisingly high tensile strength and ductility, good adhesion properties, and high stability to heat and moisture. BRIEF DESCRIPTION OF THE DRAWINGS

[0140] Figure 1 A graph showing the viscosity evolution over time is shown for Examples Z4, Z6 and Z10. Example

[0141] In the following, examples will be described which are intended to further illustrate the invention described. The invention is of course not limited to these described examples.

[0142] Unless otherwise stated, chemicals used were from Sigma-Aldrich.

[0143] Preparation of polymers containing isocyanate groups:

[0144] The viscosity was measured using a thermostatic cone-plate viscometer Rheotec RC30 (cone diameter 50 mm, cone angle 1°, cone tip-plate distance 0.05 mm, shear rate 10 s -1 ) determination.

[0145] The monomeric diisocyanate content was determined by HPLC (detection by photodiode array; 0.04 M sodium acetate / acetonitrile as mobile phase) after prior derivatization with the aid of N-propyl-4-nitrobenzylamine.

[0146] Polymer P1:

[0147] 613.0 g of polyoxypropylene glycol (OH value 56 mg KOH / g, 2000L, from Dow) and 387.0g of 4,4'-diphenylmethane diisocyanate ( 44MC L from Covestro) into a polymer having an NCO content of 10.5% by weight and a viscosity of 4 Pa·s at 20° C. and a content of monomeric 4,4′-diphenylmethane diisocyanate of about 24% by weight.

[0148] Subsequently, the volatile components, in particular the majority of monomeric 4,4'-diphenylmethane diisocyanate, were distilled off in a short-path evaporator (jacket temperature 180° C., pressure 0.1-0.005 mbar, condensation temperature 47° C.). The polymer thus obtained had an NCO content of 3.0% by weight, a viscosity of 21 Pa·s at 20° C., and a monomeric 4,4'-diphenylmethane diisocyanate content of 0.05% by weight.

[0149] Polymer P2:

[0150] 500.0g polyoxypropylene glycol (OH value 56mg KOH / g, 2000L, from Dow) and 131.0g of 4,4'-diphenylmethane diisocyanate ( 44MC L from Covestro) was converted by known methods at 80° C. into a polymer having an NCO content of 3.5% by weight and a content of monomeric 4,4′-diphenylmethane diisocyanate of about 2% by weight.

[0151] Polyurea composition:

[0152] Compositions Z1 to Z10:

[0153] For each composition, the mixture was centrifuged at 2500 rpm and under the condition of excluding water. TM DAC 150.1VZ, FlackTek Inc.) The ingredients listed in Tables 1 and 2 were mixed in the listed amounts (weight percent) for 30 seconds and stored under conditions excluding moisture. Each composition was tested as follows:

[0154] Polyisocyanates used:

[0155]

[0156] The viscosity of the composition is measured using a Brookfield HBDV-II+ viscometer, using spindle 7, at 23° C. and 50% relative humidity at a speed of 100 rpm.

[0157] The viscosity was measured periodically at 2 minute intervals in order to determine the gel point and the build-up of viscosity over time. The initial viscosity was measured 2 minutes after the start of mixing in the Speedmixer. The results are shown in Tables 1 and 2 as "Initial Viscosity" measured after 2 minutes and in Tables 2 and 3. Figure 1 Plot the graph against time.

[0158] The moment of loss of self-leveling properties ("VSE") was measured as a measure of the processing time (open time). The loss of self-leveling properties was determined by evaluating the coating surface for the presence of crater marks and / or brush marks. Each composition was applied at a thickness of 2 mm at one-minute intervals, and the coating surface was visually evaluated after 2 hours.

[0159] As a measure of the curing rate, the "walkability" in hours at 23° C. and 50% relative humidity was determined. For this purpose, each composition was applied to an aluminum substrate in a thickness of 2 mm. 2 A load of 100 kg was applied to the coating for 5 seconds over an area of 100 kg and the process was repeated at regular intervals of 1 hour. "Walkability" was determined as the period of time during which no cracks or indentations of the applied load occurred in the coating surface.

[0160] Mechanical properties were determined using a Lloyds Instruments LR5k tensiometer. For Table 1 the following were determined:

[0161] 1) Tensile strength "ZF" (N / mm 2 ),

[0162] 2) Elongation at break "BD" (%),

[0163] 3) Elastic modulus "E-mod" (N / mm 2 )

[0164] In Table 2, the mechanical properties are tested after heat aging "4w 80°C" or hydrolytic stability "4w 70 / W" and compared with untreated samples "2d NK" stored for 2 days at 23°C and 50% relative air humidity:

[0165] 80℃ heat aging stability ("4w 80℃"):

[0166] The films of each composition were stored in an incubator at 80°C for 4 weeks.

[0167] After removal from the incubator, the films were conditioned at 23° C. / 50% relative humidity for 24 hours before the mechanical properties were determined.

[0168] Hydrolytic stability at 70°C ("4w70 / W"):

[0169] The film of each composition was immersed in water and stored in water in an incubator at 70°C for 4 weeks.

[0170] After removal from the incubator, the membranes were stored at an elevated temperature of 60°C for 24 hours to remove moisture.

[0171] Conditioning at 23° C. / 50% relative humidity was then carried out for a further 24 hours before the determination of the mechanical properties.

[0172] The results are reported in Tables 1 and 2.

[0173] Compositions Z3-Z8 are examples of the present invention. Compositions Z1, Z2, Z9 and Z10 are comparative examples and are given the designation "(Ref.)".

[0174] It is evident from Table 1 that the processability of the compositions according to the prior art (Z2) is too low and that they have insufficient mechanical properties, in particular the elastic modulus and tensile strength.

[0175] Compositions (Z1) based on P1 alone, although having very long processability, have a low curing rate and also have insufficient mechanical properties, in particular the elastic modulus and tensile strength.

[0176] Furthermore, it is clear from Table 2 that the addition of HDI in the case of prepolymer P2 leads to a lower elastic modulus and, in the case of 2d NK and 4w 70 / W, to a lower elongation at break compared to P1. Figure 1 A significantly shorter open time (increased viscosity) compared to Z4 is also shown.

[0177] Table 1: Weight percentages of Z1 to Z9

[0178]

[0179] 1 Desmodur 2863XP, NCO functionality 2.2 (from Covestro)

[0180] 2 Desmodur 2860XP, NCO functionality 2.5 (from Covestro)

[0181] 3 Desmodur N3900, NCO functionality 3.5 (from Covestro)

[0182] 4 MDI monomer, Desmodur V50L (from Covestro)

[0183] 5 Ethacure 300, DMTDA (from Albemarle)

[0184] 6 Additives: defoamers, dispersants and pigments

[0185] Table 2: Weight percentage of Z10, Z4 and Z6

[0186] Z10 (Ref.) Z4 Z6 P1 79.4 78.0 P2 78.6 <![CDATA[HDI 1 1 ]]> 7.9 7.9 <![CDATA[HDI 2 2 ]]> 7.7 <![CDATA[amine 5 > 8.9 7.8 9.4 <![CDATA[Additive 6 > 4.6 4.9 4.9 total 100.00 100.00 100.00 NCO / NH 105:100 105:100 105:100 Initial viscosity after 2 minutes (cPs) 22.800 10.360 9.720 2d NK <![CDATA[ZF(N / mm 2 )]]> 2.26 2.12 3.4 2d NK BD (%) 298 448 810 2d NK <![CDATA[E-mod(N / mm 2 )]]> 5.2 5.5 9.8 4w 80℃ <![CDATA[ZF(N / mm 2 )]]> 6.71 6.71 10.25 4w 80℃ BD (%) 407 407 445 4w 70 / W <![CDATA[ZF(N / mm 2 )]]> 7.24 6.95 7.34 4w 70 / W BD (%) 808 1232 585

[0187] 1 Desmodur 2863XP, NCO functionality 2.2 (from Covestro)

[0188] 2 Desmodur 2860XP, NCO functionality 2.5 (from Covestro)

[0189] 5 Ethacure 300, DMTDA (from Albemarle)

[0190] 6 Additives: defoamers, dispersants and pigments

Claims

1. A polyurea composition having a monomeric diisocyanate content of not more than 0.5 wt%, comprising a first component A comprising: at least one primary aromatic diamine A1 selected from diethyltoluenediamine, 4,4′-methylenebis(2,6-diethyl)aniline, 4,4′-methylenebis(2,6-diisopropyl)aniline, 4,4′-methylenebis(3-chloro-2,6-diethyl)aniline and dimethylthiotoluenediamine; and a second component B, which contains: at least one polyether polyurethane polymer B1 containing isocyanate groups and having a monomeric diisocyanate content of not more than 0.5% by weight, obtained by reacting a monomeric diisocyanate with at least one polyether polyol in an NCO / OH ratio of at least 3 / 1 and subsequently removing the majority of the monomeric diisocyanate by suitable separation methods, wherein the monomeric diisocyanate is 4,4′-diphenylmethane diisocyanate, optionally with a proportion of 2,4′-diphenylmethane diisocyanate and / or 2,2′-diphenylmethane diisocyanate, and at least one aliphatic polyisocyanate B2 having an NCO content of 8 to 25% by weight; The weight ratio of B1 / B2 is 5-50.

2. The polyurea composition according to claim 1, characterized in that The diethyltoluenediamine is 3,5-diethyltoluene-2,4-diamine or 3,5-diethyltoluene-2,6-diamine.

3. The polyurea composition according to claim 1, characterized in that The dimethylthiotoluenediamine is 3,5-dimethylthio-2,6-toluenediamine or 3,5-dimethylthio-2,4-toluenediamine.

4. The polyurea composition according to claim 1, characterized in that The weight ratio of B1 / B2 is 7.5-30.

5. The polyurea composition according to claim 1, wherein The weight ratio of B1 / B2 is 8-25.

6. The polyurea composition according to claim 1, wherein The NCO content of the polyether polyurethane polymer B1 is 1-8.4% by weight.

7. The polyurea composition according to claim 1, characterized in that The NCO content of the polyether polyurethane polymer B1 is 1.4-5.6% by weight.

8. The polyurea composition according to claim 1, wherein The NCO content of the polyether polyurethane polymer B1 is 2-4.2% by weight.

9. The polyurea composition according to any one of claims 1 to 8, characterized in that The OH value of the polyether polyol is 20 to 280 mg KOH / g.

10. The polyurea composition according to any one of claims 1 to 8, characterized in that The OH value of the polyether polyol is 35 to 120 mg KOH / g.

11. The polyurea composition according to any one of claims 1 to 8, characterized in that The OH value of the polyether polyol is 50 to 60 mg KOH / g.

12. The polyurea composition according to any one of claims 1 to 8, characterized in that The average OH functionality of the polyether polyol is 1.7-3.

13. The polyurea composition according to any one of claims 1 to 8, characterized in that The average OH functionality of the polyether polyol is 1.8-2.

14. The polyurea composition according to any one of claims 1 to 8, characterized in that The NCO / OH ratio in the reaction between the monomeric diisocyanate and the polyether polyol is in the range from 3 / 1 to 10 / 1.

15. The polyurea composition according to any one of claims 1 to 8, characterized in that The NCO / OH ratio in the reaction between the monomeric diisocyanate and the polyether polyol is in the range from 4 / 1 to 7 / 1.

16. The polyurea composition according to any one of claims 1 to 8, characterized in that The at least one primary aromatic diamine A1 is dimethylthiotoluenediamine.

17. The polyurea composition according to claim 16, characterized in that The dimethylthiotoluenediamine is 3,5-dimethylthio-2,6-toluenediamine or 3,5-dimethylthio-2,4-toluenediamine.

18. The polyurea composition according to any one of claims 1 to 8, characterized in that The aliphatic polyisocyanate B2 is an oligomer, polymer and / or derivative derived from 1,6-hexamethylene diisocyanate or isophorone diisocyanate.

19. The polyurea composition according to claim 18, characterized in that The aliphatic polyisocyanate B2 is an oligomer, polymer and / or derivative derived from 1,6-hexamethylene diisocyanate.

20. The polyurea composition according to any one of claims 1 to 8, characterized in that The aliphatic polyisocyanate B2 has an average NCO functionality of at least 2.

1.

21. The polyurea composition according to any one of claims 1 to 8, characterized in that The aliphatic polyisocyanates B2 have an average NCO functionality of from 2.1 to 3.

0.

22. The polyurea composition according to any one of claims 1 to 8, characterized in that The aliphatic polyisocyanates B2 have an average NCO functionality of from 2.1 to 2.

6.

23. The polyurea composition according to any one of claims 1 to 8, characterized in that It contains less than 5 wt% of solvent, based on the total weight of the polyurea composition.

24. The polyurea composition according to any one of claims 1 to 8, characterized in that It contains less than 2 wt% of solvent, based on the total weight of the polyurea composition.

25. The polyurea composition according to any one of claims 1 to 8, characterized in that It contains less than 1 wt. % of solvent, based on the total weight of the polyurea composition.

26. The polyurea composition according to any one of claims 1 to 8, characterized in that It contains less than 0.5 wt. % of solvent, based on the total weight of the polyurea composition.

27. The polyurea composition according to any one of claims 1 to 8, characterized in that It contains less than 0.1 wt. % of solvent, based on the total weight of the polyurea composition.

28. The polyurea composition according to any one of the preceding claims 1 to 8, characterized in that The ratio of the isocyanate groups to the groups reactive toward isocyanate groups is 1 to 1.

2.

29. The polyurea composition according to claim 28, characterized in that The ratio of the isocyanate groups to the groups reactive toward isocyanate groups is 1 to 1.

1.

30. The polyurea composition according to claim 28, characterized in that The group reactive toward an isocyanate group is an amino group.

31. The polyurea composition according to any one of the preceding claims 1 to 8, characterized in that It contains: - 3 to 15% by weight of a primary aromatic diamine A1 selected from diethyltoluenediamine, 4,4'-methylenebis(2,6-diethyl)aniline, 4,4'-methylenebis(2,6-diisopropyl)aniline, 4,4'-methylenebis(3-chloro-2,6-diethyl)aniline and dimethylthiotoluenediamine, - 55 to 90% by weight of a polyether polyurethane polymer B1 containing isocyanate groups and having a content of not more than 0.5% by weight of monomeric diisocyanates, - 2 to 15% by weight of an aliphatic polyisocyanate B2 with an NCO content of 8 to 25% by weight, – 5-30% by weight of fillers; The total content of each component of the composition satisfies 100% by weight.

32. The polyurea composition according to claim 31, wherein They contain 5 to 12% by weight of primary aromatic diamines A1.

33. The polyurea composition according to claim 31, wherein They contain 7-10% by weight of primary aromatic diamine A1.

34. The polyurea composition of claim 31, wherein The diethyltoluenediamines are 3,5-diethyltoluene-2,4-diamine and 3,5-diethyltoluene-2,6-diamine.

35. The polyurea composition of claim 31, wherein The dimethylthiotoluenediamines are 3,5-dimethylthio-2,6-toluenediamine and 3,5-dimethylthio-2,4-toluenediamine.

36. The polyurea composition of claim 31, wherein It contains 60% to 90% by weight of a polyether polyurethane polymer B1 containing isocyanate groups and having a monomeric diisocyanate content of not more than 0.5% by weight.

37. The polyurea composition of claim 31, wherein It contains 70% to 85% by weight of a polyether polyurethane polymer B1 containing isocyanate groups and having a monomeric diisocyanate content of not more than 0.5% by weight.

38. The polyurea composition of claim 31, wherein It contains 75% to 85% by weight of a polyether polyurethane polymer B1 containing isocyanate groups and having a monomeric diisocyanate content of not more than 0.5% by weight.

39. The polyurea composition of claim 31, wherein They contain 3 to 10% by weight of aliphatic polyisocyanates B2 having an NCO content of 8 to 25% by weight.

40. The polyurea composition of claim 31, wherein They contain 4 to 8% by weight of aliphatic polyisocyanates B2 having an NCO content of 8 to 25% by weight.

41. The polyurea composition of claim 31, wherein It contains 10-25% by weight of filler.

42. The polyurea composition of claim 31, wherein It contains 10-20% by weight of filler.

43. The polyurea composition of claim 31, wherein It contains 2-10% by weight of inorganic or organic pigments, flame retardants and additives.

44. The polyurea composition of claim 31, wherein It contains 3-8% by weight of inorganic or organic pigments, flame retardants and additives.

45. The polyurea composition of claim 31, wherein It contains 3-5% by weight of inorganic or organic pigments, flame retardants and additives.

46. A method of coating or sealing comprising the following steps (i) mixing the components of the polyurea composition according to any one of claims 1 to 45, (ii) applying the mixed polyurea composition to at least one substrate, (iii) curing the composition.

47. An article obtained by the method of claim 46.

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