Compositions containing isocyanate group and isocyanate group and PUR / PIR hard foam made therefrom

Abstract

The invention relates to a composition containing isocyanate groups and isocyanurate groups, obtained by reacting pMDI in the presence of a trimerization catalyst, and to a method for producing PUR / PIR rigid foams from such a composition. The invention further relates to a method for producing compositions containing isocyanate groups and isocyanurate groups, to the production of PUR / PIR rigid foams from these compositions, to the rigid foams themselves, and to the use of such rigid foams.

Description

[0001] The present invention relates to compositions containing isocyanate groups and isocyanurate groups for the production of PUR / PIR rigid foams, and to the production of compositions containing isocyanate groups and isocyanurate groups by partial trimerization of polymeric MDI (pMDI). The present invention further relates to the production of PUR / PIR rigid foams from these compositions, the rigid foams themselves, and the use of such rigid foams.

[0002] For the production of insulating foams, such as those used for facade cladding, polyisocyanurate-polyurethane foam systems (PUR / PIR foams) are increasingly being used to improve fire safety, which are produced by using - based on the polyol component - significantly more than stoichiometric amounts of the polymeric polyisocyanates conventionally used for the production of rigid foams. Thus, the polymeric polyisocyanates used have a decisive influence on the properties of the rigid foams. In addition to the final properties such as thermal insulation efficiency and final strength, an important technical property also lies in the mechanical strength shortly after the production of the rigid foam. This determines how long the rigid foam can be mechanically processed and stacked.

[0003] It is known that the time required for the curing of PUR / PIR foams can be influenced by various factors, in particular by the use of oligomeric (polynuclear) polyisocyanates. The synthesis of polynuclear isocyanurate structures is achieved by the trimerization of polyisocyanates.

[0004] US 4,743,627 describes particularly low-colored PUR / PIR foams made from compositions containing isocyanate groups and isocyanurate groups. The method described therein comprises the following steps: (a) trimerizing polymeric MDI in the presence of a trimerization catalyst to obtain an isocyanurate-containing polyisocyanate; (b) deactivating the trimerization catalyst; and (c) mixing the isocyanurate-containing polyisocyanate with monomeric MDI to form a final product having a viscosity comparable to that of standard pMDI and a binuclear content of at least 60% by weight. This final product is used to produce foams having a lighter color compared to foams based on standard pMDI. The disadvantage of step c) of mixing with monomeric MDI is that it reduces the isocyanate functionality of the mixture, which has an adverse effect on the final properties such as strength of the PUR / PIR rigid foams made therefrom.

[0005] US2009 / 105359 A1 relates to a process for producing isocyanurate-modified liquid pMDI having a controlled viscosity. The process comprises the steps of: (a) trimerizing a "conventional pMDI", i.e., a trimer-free mixture of monomeric and oligomeric MDI having a viscosity between 30 and 300 mPa*s, in the presence of a trimerization catalyst to obtain an isocyanurate-containing pMDI having a viscosity in the range of 2000 mPa*s to 200000 mPa*s at 25 °C; (b) deactivating the catalyst with a catalyst deactivator to obtain a mixture containing isocyanurate-modified pMDI and deactivated catalyst; (c) mixing the mixture from step (b) with an amount of trimer-free pMDI sufficient to obtain a mixture having a viscosity at 25 °C in the range of 400 mPa*s to 20000 mPa*s and a free NCO group content comparable to that of conventional pMDI having a viscosity between 30 and 1000 mPa*s.

[0006] The disadvantage is that this three-step process for producing isocyanurate-containing pMDI (which proceeds via highly viscous pMDI in an intermediate step) causes defects in the production of insulating panels.

[0007] WO 2017 / 046274 A1 discloses a process for producing polyurethane-polyisocyanurate rigid foams (PUR / PIR rigid foams) which uses an isocyanate blend of predominantly monomeric MDI and polymeric MDI and then partially trimerizes it. The isocyanate blend used according to the invention contains 15 - 25 wt% of isocyanurate groups and has a viscosity > 1000 mPa*s at 25 °C; blends having a lower viscosity and / or a higher isocyanurate content have proven disadvantageous here, for example with regard to storage stability.

[0008] JP H06256460A, JP 2008260843 A, JP H0873557A, JP H0892346A and JPH08120048A disclose isocyanurate-modified polyisocyanates and foams made therefrom. The production of the modified polyisocyanates uses a relatively high catalyst concentration (greater than 0.5 wt%), and the results do not show a linear relationship between the NCO content, viscosity and isocyanurate content. MDI having a viscosity of 130 mPa*s (25 °C) is used in each case. A catalyst concentration above 0.5 wt% makes the reactivity difficult to control.

[0009] JP S59163357A also discloses the production of modified polyisocyanates using a high catalyst dosage, where these are terminated thermally rather than chemically. However, this has the disadvantage that catalyst residues that have not been chemically inactivated can have an adverse effect on the further reaction to produce polyurethanes. In addition, the trimerization reaction continues for some time during thermal termination, so it is almost impossible to establish a specific product viscosity in a controlled manner.

[0010] DE 69116583 T2 discloses the trimerization of polyisocyanates using the catalyst tetramethylguanidine (an iminosemicarbazide derivative). This catalyst cannot be terminated with acyl chlorides or hydrochloric acid, so methanesulfonic acid must be used as the terminator, which has an adverse effect on the corrosivity of the composition.

[0011] EP 3974460 A1 discloses an isocyanate preparation that contains a radical initiator (tert-butyl peroxybenzoate) and an inhibitor (butylated hydroxytoluene), where the inhibitor is added simultaneously with the radical initiator. During the reaction of the isocyanate preparation with a polyol, the radical initiator is said to undergo thermal decomposition into radicals at an elevated temperature and initiate the radical polymerization of an olefin. The inhibitor has been added together with the radical initiator to keep the isocyanate preparation stable and not increase in viscosity and ultimately cure before use, i.e., during storage. In addition, the invention does not describe the radical initiator, especially peroxides or azo compounds.

[0012] WO 2020 / 221662 A1 also discloses the trimerization of isocyanates using a radical initiator. The reaction is not terminated and no terminator is added. Therefore, the trimerization reaction can continue without restriction until gelling, and the resulting isocyanate cannot be used for foaming reactions.

[0013] Starting from the above prior art, an object of the present invention is to provide a polyisocyanate component that enables the production of PUR / PIR rigid foams with good initial strength, which allows for the early handling and stackability of insulation panels made therefrom and exhibits good flame retardancy. At the same time, the polyisocyanate component should overcome the disadvantages of the methods described in the prior art (insufficient storage stability, insufficient foam properties, defects in the produced panels).

[0014] Surprisingly, this object can be achieved by an isocyanurate-containing pMDI having a viscosity of <2000 mPa*s at 25°C, in particular <1000 mPa*s at 25°C and a number-average molecular weight Mn of >350 g / mol, which can be obtained directly by trimerization of a conventional polymeric MDI having a monomeric MDI content of <55% by weight, in particular <50% by weight and a viscosity of 130 - 400 mPa*s at 25°C, preferably 140 to 400 mPa*s, more preferably 140 - 300 mPa*s at 25°C, and containing 5 - <13% by weight of isocyanurate groups.

[0015] The present invention thus relates to a process for producing a composition A2 containing isocyanate groups and isocyanurate groups, which comprises the steps of:

[0016] 1) reacting a polyisocyanate A1 in the presence of a trimerization catalyst, and

[0017] 2) terminating the reaction of step 1) using a suitable terminator to obtain the composition A2;

[0018] wherein the trimerization catalyst is not semicarbazide, a derivative of semicarbazide or a radical initiator, and based on A1, the concentration of the trimerization catalyst used is <0.50% by weight, in particular <0.45% by weight, more preferably <0.40% by weight, very particularly preferably <0.30% by weight, and

[0019] wherein the polyisocyanate A1 used in step 1) is a polymeric MDI having a monomeric diphenylmethane diisocyanate content of <55% by weight, particularly preferably 30 - 50% by weight of monomeric diphenylmethane diisocyanate, and a viscosity of 140 - 400 mPa*s (measured without solvent according to DIN 53019-1:2008-09), and

[0020] wherein step 2) is carried out when the reaction mixture from step 1) contains 5 - <13% by weight of isocyanurate groups and has a viscosity of <2000 mPa*s at 25°C (measured without solvent according to DIN 53019-1:2008-09).

[0021] In the present application, "oligomeric MDI" is understood to mean a polyisocyanate mixture composed of polynuclear homologues of MDI having at least 3 aromatic nuclei and an NCO functionality of at least 3.

[0022] In the present invention, the terms "polymeric diphenylmethane diisocyanate", "polymeric MDI" or pMDI are used to describe a mixture of oligomeric MDI and optionally monomeric MDI. Based on the total mass of the pMDI, the monomer content of the polymeric MDI is generally in the range of 30 - 50% by weight.

[0023] The polyisocyanate A1 contains <55% by weight of monomeric MDI, in particular 30 - ≤50% by weight of monomeric MDI, and has a viscosity of 130 to 400 mPa·s at 25°C, preferably 140 to 400 mPa·s at 25°C, particularly preferably 140 - 300 mPa·s at 25°C (measured without solvent according to DIN 53019-1:2008-09). It is particularly preferred to use polymeric MDI having the following composition:

[0024] 4,4'-diphenylmethane diisocyanate of 35 - 50% by weight, 2,4'-diphenylmethane diisocyanate of 1 - 10% by weight, >0% by weight to ≤5% by weight of 2,2'-diphenylmethane diisocyanate, and higher homologues of diphenylmethane diisocyanate (having ≥3 aromatic nuclei) of 45% by weight to <64% by weight. It is particularly preferred to use a composition of 40 - 50% by weight, in particular 40 - 46% by weight, of 4,4'-diphenylmethane diisocyanate, 1 - 5% by weight of 2,4'-diphenylmethane diisocyanate, >0% by weight to ≤5% by weight of 2,2'-diphenylmethane diisocyanate, and higher homologues of diphenylmethane diisocyanate (having ≥3 aromatic nuclei) of 45% by weight to <60% by weight.

[0025] The polyisocyanate A1 is trimerized [step (1)]. The trimerization reaction itself is known and is described, for example, in WO 2009 / 039332 A,

[00015] -

[00021] , which is hereby incorporated by reference. Suitable trimerization catalysts include, for example, Mannich bases of phenols or phenol derivatives, such as Mannich bases of 2,4,6-tris(dimethylaminomethyl)phenol and 4,4'-isopropylidene bis[2,6-bis(dimethylaminomethyl)phenol], potassium acetate, and / or aliphatic quaternary ammonium salts. Iminoureas, such as 1,1,3,3-tetramethylguanidine, are not suitable as catalysts because the subsequent trimerization reaction is difficult to terminate with acyl chlorides. Also not suitable as catalysts are free radical initiators, especially peroxides and azo compounds, because free radical-induced trimerization reactions are also difficult to terminate.

[0026] Based on A1, the concentration of the trimerization catalyst used is <0.50% by weight, especially <0.45% by weight, more preferably <0.40% by weight, and very particularly preferably <0.30% by weight. At higher concentrations, the trimerization reaction proceeds too fast and is difficult to terminate at the right time.

[0027] The content (in % by weight) of isocyanurate groups in the composition A2 containing isocyanate groups and isocyanurate groups obtained after the trimerization reaction is determined as follows:

[0028] Isocyanurate % (A2) = (NCO % (A1) - NCO % (A2)) / (NCO % (A1) / 2) * 100

[0029] The determination of the weight ratio of the NCO groups is carried out according to DIN EN 1242:2013.

[0030] The viscosity data in this application relate to the viscosity determined according to DIN 53019-1 (2008-09) (solvent-free).

[0031] The composition of the composition A2 or the isocyanate component A containing isocyanate groups and isocyanurate groups can be determined by gel permeation chromatography (GPC) in tetrahydrofuran as a solvent at 35 °C according to DIN 55672-1:2016-03.

[0032] The composition A2 or the isocyanate component A has a seventh peak ("peak G", corresponding to the fraction with the seventh lowest molecular weight) with a peak area preferably > 4.6 area % in its GPC.

[0033] The composition A2 or the isocyanate component A preferably has a number average molecular weight Mn > 350 g / mol.

[0034] The composition A2 has

[0035] - an isocyanate group content of isocyanurate groups of -5 - < 13% by weight,

[0036] -> a number average molecular weight Mn of > 350 g / mol and

[0037] - a seventh peak in its GPC with a peak area preferably > 4.6 area % (corresponding to the fraction with the seventh lowest molecular weight) and

[0038] - a viscosity of < 2000 mPa*s at 25 °C, preferably < 1000 mPa*s at 25 °C.

[0039] Compared with the compositions from the prior art, the composition A2 prepared by the method according to the invention has a lower trimerization catalyst content and a favorable molecular weight distribution, which is manifested in favorable properties such as better surface quality during subsequent processing into PUR / PIR rigid foams.

[0040] According to the present invention, the trimerization reaction is terminated in a controlled manner by adding an inactivator ("terminator"). In principle, various acyl chlorides or various Bronsted acids other than sulfonic acid, sulfuric acid or their derivatives (due to the severe corrosiveness of these compounds) can be used. The acyl chlorides that can be used include, in particular, acetyl chloride and benzoyl chloride and mixtures thereof. A preferred example of an acyl chloride is benzoyl chloride, and another preferred example is isophthaloyl chloride. The acids that can be used include, in particular, hydrochloric acid, acetic acid, oxalic acid and phosphoric acid. Hydrochloric acid, acetic acid and oxalic acid are preferred. A particularly preferred example of an acid is hydrochloric acid. The acyl chloride or Bronsted acid can also be used as a solution or dispersion in an organic solvent, monomeric MDI or polymeric MDI.

[0041] The composition A2 containing isocyanate groups and isocyanurate groups obtained after step 2) can be used alone or in admixture with other isocyanates for the production of polymers, in particular PUR and PUR / PIR rigid foams. It is possible, for example, to establish a specific viscosity by blending with other polyisocyanates. Suitable for this purpose are aliphatic, cycloaliphatic, araliphatic diisocyanates and / or polyisocyanates known in polyurethane chemistry, in particular aromatic isocyanates. In particular, isomers and oligomers of MDI and TDI can be used.

[0042] A further aspect of the present invention is the composition A2 containing isocyanate groups and isocyanurate groups obtainable by the process according to the present invention and the isocyanate component A comprising said composition A2.

[0043] The present invention also relates to a process for producing PUR / PIR rigid foams by reacting a PUR / PIR system consisting of an isocyanate component A and a polyol formulation B in the presence of a blowing agent C and a catalyst D, wherein the isocyanate component A comprises the composition A2 containing isocyanate groups and isocyanurate groups according to the present invention.

[0044] The PUR / PIR system is preferably used for the production of composite elements. Foaming is usually carried out continuously or discontinuously against at least one outer layer.

[0045] The PUR / PIR rigid foam can be obtained by reacting the PUR / PIR system. During the reaction, the isocyanate component A and the polyol formulation B usually react in such amounts that the isocyanate index of the foam is ≥250 to ≤450, preferably ≥320 to ≤400.

[0046] The isocyanate index (also referred to as the index or isocyanate index) is herein the quotient calculated by dividing the molar amount [mol] of isocyanate groups actually used by the molar amount [mol] of isocyanate groups stoichiometrically required to fully convert all isocyanate-reactive groups, and then multiplying by 100. Since the conversion of 1 mole of isocyanate-reactive groups requires 1 mole of isocyanate groups, the following equation applies:

[0047] Index = (moles of isocyanate groups / moles of isocyanate-reactive groups) · 100 The isocyanate component A in particular has the following properties:

[0048] <13 wt% of isocyanurate groups,

[0049] 20 - 50 wt%, preferably 20 - 40 wt% of monomeric MDI,

[0050] 23 - 30 wt% NCO content (DIN EN 1242:2013),

[0051] in each case based on the total weight of component A,

[0052] and a viscosity of < 2000 mPa·s at 25°C, preferably < 1000 mPa·s at 25°C.

[0053] To produce the isocyanate component A, the composition A2 containing isocyanate groups and isocyanurate groups of the present invention can optionally be blended with other isocyanates, for example to establish a lower or higher viscosity. In a preferred embodiment, the composition A2 containing isocyanate groups and isocyanurate groups according to the present invention is not used in a blend with other isocyanates. Suitable isocyanates for blending with the composition A2 containing isocyanate groups and isocyanurate groups of the present invention include conventional aliphatic, cycloaliphatic, araliphatic diisocyanates and / or polyisocyanates known in polyurethane chemistry, especially aromatic isocyanates. Aromatic isocyanates, especially homologues and isomers of the MDI series, are particularly preferred. The isocyanates suitable for blending can further be polyurethane prepolymers or modified isocyanates. The term "polyurethane prepolymer" especially refers to a reactive intermediate in the reaction to provide a polyurethane polymer by isocyanate reaction. They are produced by the reaction of a polyol component with an excess of an isocyanate component. Preferred modified isocyanates include: urea-modified isocyanates; biuret-modified isocyanates; urethane-modified isocyanates; isocyanurate-modified isocyanates; urethane-modified isocyanates; carbodiimide-modified isocyanates; uretdione-modified isocyanates and uretonimine-modified isocyanates. Such modified isocyanates are commercially available and are produced by reacting an isocyanate with a sub-stoichiometric amount of an isocyanate-reactive compound or with itself.

[0054] In particular, isomers and oligomers of MDI and TDI can be used for blending.

[0055] As the polyol for the polyol preparation B, compounds based on polyester polyols or polyether polyols are preferably used. The functionality of the polyether polyol and / or polyester polyol is generally from 1.9 to 8, preferably from 1.9 to 7, and particularly preferably from 1.9 to 6.

[0056] The polyol particularly has a hydroxyl value of greater than 70 mg KOH / g, preferably greater than 100 mg KOH / g, and particularly preferably greater than 120 mg KOH / g. The upper limit of the hydroxyl value that has proven advantageous is generally 1000 mg KOH / g, preferably 900 mg KOH / g, and particularly 800 mg KOH / g. The above OH value is based on all the polyols in the polyol preparation B, and does not exclude that individual components of the mixture may have higher or lower values.

[0057] The polyol preparation B preferably contains a polyether polyol produced by known methods from one or more alkylene oxides having 2 to 4 carbon atoms in the alkylene group, for example, by anionic polymerization using an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide, or an alkali metal alcoholate such as sodium methoxide, sodium ethoxide, potassium ethoxide or potassium isopropoxide as a catalyst and in the presence of at least one initiator molecule containing 2 to 8, preferably 2 to 6 bonded reactive hydrogen atoms, or by cationic polymerization using a Lewis acid such as antimony pentachloride, boron fluoride etherate, etc. or bleaching earth as a catalyst. Suitable alkylene oxides include, for example, tetrahydrofuran, 1,3-propylene oxide, 1,2- and 2,3-butylene oxides, styrene oxide, preferably ethylene oxide and 1,2-propylene oxide. The alkylene oxides can be used individually, successively alternately or as a mixture. The initiator molecules considered include alcohols such as glycerol, trimethylolpropane (TMP), pentaerythritol, sucrose, sorbitol and amines such as methylamine, ethylamine, isopropylamine, butylamine, benzylamine, aniline, toluidine, toluenediamine, naphthylamine, ethylenediamine, diethylenetriamine, 4,4'-methylenedianiline, 1,3-propanediamine, 1,6-hexanediamine, ethanolamine, diethanolamine, triethanolamine, etc. Condensation products of formaldehyde, phenol and diethanolamine, or ethanolamine, formaldehyde, alkylphenol and diethanolamine, or ethanolamine, formaldehyde, bisphenol A and diethanolamine, or ethanolamine, formaldehyde, aniline and diethanolamine, or ethanolamine, formaldehyde, cresol and diethanolamine, or ethanolamine, formaldehyde, toluidine and diethanolamine or ethanolamine, and ethanolamine and formaldehyde, toluenediamine (TDA) and diethanolamine or ethanolamine, etc. can also be used as initiator molecules. The initiator molecules used are preferably TMP and TDA.

[0058] The polyol preparation B may contain a crosslinking agent as other component. The crosslinking agent is understood to be a compound having a molecular weight of 60 to less than 400 g / mol and at least 3 isocyanate-reactive hydrogen atoms. An example thereof is glycerol. The crosslinking agent is usually used in an amount of 1% to 10% by weight, preferably 2% to 6% by weight, based on the total weight of the polyol preparation B (but without the physical blowing agent).

[0059] The polyol preparation B may further contain a chain extender, which is used to increase the crosslinking density. The chain extender is understood to be a compound having a molecular weight of 60 to less than 400 g / mol and at least 2 isocyanate-reactive hydrogen atoms. Examples include butanediol, diethylene glycol, dipropylene glycol, and ethylene glycol. The chain extender is usually used in an amount of 2% to 20% by weight, preferably 4% to 15% by weight, based on the total weight of the polyol preparation B (but without the physical blowing agent).

[0060] The crosslinking agent and the chain extender can be used alone or in combination for the polyol mixture.

[0061] The production of PUR / PIR rigid foams further uses a chemical and / or physical blowing agent (C).

[0062] Preferred chemical blowing agents include water or carboxylic acids, especially formic acid. Based on the weight of component B, the chemical blowing agent is usually used in an amount of 0.1% to 5% by weight, especially 1.0% to 3.0% by weight.

[0063] The term physical blowing agent is understood to mean a compound that is dissolved or emulsified in the starting materials for polyurethane production and evaporates under the polyurethane-forming conditions. Examples include hydrocarbons, halogenated hydrocarbons, and other compounds, such as perfluoroalkanes, such as perfluorohexane, chlorofluorocarbons, and ethers, esters, ketones, and / or acetals. Based on the total weight of component B, these are usually used in an amount of 1% to 30% by weight, preferably 2% to 25% by weight, particularly preferably 3% to 20% by weight.

[0064] The production of PUR / PIR rigid foams further uses catalyst D. Catalyst D for accelerating the reaction of the hydroxyl group-containing compound of component B with the isocyanate group of component A is generally and preferably an organotin compound, such as a tin(II) salt of an organic carboxylic acid, and / or a basic amine compound, preferably a tertiary amine, such as triethylamine, and / or 1,4-diazabicyclo(2,2,2)octane. Catalyst D for forming isocyanurate groups in the production of PUR / PIR rigid foams generally includes metal carboxylates, preferably potassium acetate or potassium octanoate, and their solutions. A mixture of a catalyst for accelerating the reaction of the hydroxyl group-containing compound of component B with the isocyanate group of component A and a catalyst for forming isocyanurate groups is used in PUR / PIR rigid foams. Based on the weight of component B, the catalyst is generally used in an amount of 0.001% to 5% by weight of the catalyst.

[0065] In the PUR / PIR system, further auxiliaries and / or additive substances E can also be optionally incorporated. These are understood to refer to auxiliaries and additives known and conventional in the prior art. These can be added to the polyol component B or directly to the reaction mixture. They include, for example, surface-active substances, foam stabilizers, cell regulators, fillers, dyes, pigments, flame retardants, antistatic agents, anti-hydrolysis agents, and / or substances that inhibit fungi and bacteria.

[0066] The present invention also relates to PUR / PIR rigid foams obtainable by the method according to the present invention. In the present invention, the rigid PUR / PIR foam has an apparent density in the range of 15 kg / m 3 to 300 kg / m 3 according to DIN EN ISO 3386-1-98 (September 2010 version) and a compressive strength in the range of 0.1 MPa to 3 MPa according to DIN EN 826 (May 1996 version).

[0067] Surprisingly, it has been found that these PUR / PIR rigid foams have improved stackability compared to rigid foams produced using conventional MDI or pMDI with a relatively high isocyanurate content. This is measured in the form of the indentation depth at a defined weight and a defined plunger area after production (for the description, see the experimental section), and is thus related to the curing rate. At the same time, the PUR / PIR rigid foams also exhibit very good storage stability and foam properties, improved flame retardancy, and few defects in the finished boards. The PUR / PIR rigid foams according to the present invention also have advantages in terms of their water absorption properties.

[0068] The PUR / PIR rigid foams according to the present invention can thus be advantageously used as insulating foams in the production of composite elements.

[0069] The invention also relates to a composite element, which comprises a rigid foam layer containing a PUR / PIR rigid foam according to the invention and at least one outer layer. In this case, the outer layer is at least partially in contact with the layer containing the PUR / PIR rigid foam according to the invention. The material of the outer layer is generally aluminum, steel, bitumen, paper, mineral non-woven fabric, non-woven fabric containing organic fibers, plastic sheet, plastic film and / or wooden board.

[0070] In another embodiment of the composite element, it is in the form of a heat-insulating board.

[0071] Experimental part:

[0072] Methods used:

[0073] Mold temperature: The temperature of the mold for foaming, in °C.

[0074] Mixing time: The time for mixing the reaction mixture, in seconds.

[0075] Cream time: The time elapsed from the start of mixing to the perceptible start of the reaction, in seconds.

[0076] Fiber time: The time elapsed from the start of mixing to the curing of the foam surface, in seconds.

[0077] Skin dry time: The time elapsed from the start of mixing to the foam surface no longer feeling sticky, in seconds.

[0078] Indentation depth (after a certain time): An indentation depth test is carried out on freshly made laboratory foam in a test package with a bottom area of 20x20 cm 2 . The indentation depth of a plunger with a diameter of 3.5 cm and a plunger weight of 6 kg is measured after the specified time during the curing stage.

[0079] Cell size: Scaled between 1 and 6; where 1 represents very fine or very uniform, and 6 represents very coarse or irregular.

[0080] Surface / inner surface of the foam: Qualitative distinction between brittle, sandy and tough

[0081] Core apparent density: DIN EN ISO 845:2009 "Rubber and plastic foams - Determination of apparent density"

[0082] Isocyanate content: DIN EN 1242:2013 "Determination of isocyanate content"

[0083] Viscosity: DIN 53019-1:2008 "Viscosity - Measurement of viscosity and flow curves using a rotational viscometer". This measurement is carried out without a solvent.

[0084] Hydroxyl value (OH value): The OH value is determined according to the instructions of DIN 53240-2:2007.

[0085] Dimensional stability (Dim.Stab.): Store the foam specimen at 20 - 25 °C for at least 24 hours, then take out two foam cubes with dimensions of 10·10·10 cm from the core. 3 After marking the three spatial directions of each cube, measure these with a caliper and store them at -22 °C and 100 °C for 24 hours respectively. Then measure the cubes again at room temperature. The dimensional stability is the percentage change ΔL of the side lengths in all three spatial directions A, B, and C, where C always corresponds to the foaming direction. ΔL = (L - OL) / OL·100%, where L = the side length of the specimen after storage, and OL = the side length of the specimen before storage. If the change in each direction at -22 °C and 100 °C is less than 1%, the foam passes this test.

[0086] Water absorption: Weigh a cube of 90mm x 90mm x 60mm and immerse it in water in a desiccator, and evacuate it to 100 mbar for 60 seconds. Then drain the excess water and determine the water absorption by weighing.

[0087] Swiss fire test: Conduct the test according to the fire protection instruction No. 585.113 of the Federal Office of Civil Protection VKF (SAR585.113; Switzerland; March 23, 2015; Annex 5 of the Fire Protection Ordinance).

[0088] KBT: (Small burner test) The flammability test according to DIN EN ISO 11925-2 (2020-07) for grading the flame retardant properties

[0089] Compressive strength: The compressive strength at 10% compression in the running direction according to DIN EN 826-01 (2013-05)

[0090] Thermal conductivity: The thermal conductivity according to DIN EN 12667-01 (2001-05) (at 10 °C or 70 °C, 0 value); the 0 value is understood to mean the measurement is carried out directly after production without prior storage.

[0091] The content of isocyanurate groups in isocyanates 1, 2, and 3 is determined according to the following equation:

[0092] Isocyanurate % (isocyanate 1, 2, or 3) = (NCO% (input material) - NCO% (isocyanate 1, 2, or 3)) / (NCO% (input material) / 2)*100; where NCO% (input material) is the NCO content of the polyisocyanate A1 (MDI200 or MDI100) used.

[0093] Storage test: The storage stability of isocyanates was qualitatively evaluated by storing the test specimens in the laboratory at room temperature for 3 months and visually evaluating them.

[0094] GPC Gel Permeation Chromatography: The contents of different species were determined by gel permeation chromatography (GPC) according to DIN 55672-1:2016-03 at 35 °C in tetrahydrofuran solvent (SECurity GPC system from PSS Polymer Service, flow rate 0.6 ml / min; columns: 2 × PSS SDV 50A 5 μm, 2 × PSS SDV 100A 5 μm, 8 × 300 mm; RI detector). Calibration was carried out using polystyrene standards of known molecular weight. The number-average molecular weight was calculated using PSSWin GPC software. In the chromatogram, the peaks were named as shown in Figure 1. The peak with the seventh lowest molecular weight was named "Peak G".

[0095] Materials used:

[0096] MDI100: Desmodur 44V10L, polymeric diphenylmethane diisocyanate (Covestro Deutschland AG); isocyanate content 31.8 wt%, viscosity at 25 °C approximately 100 mPas,

[0097] MDI200: Desmodur 44V20L, polymeric diphenylmethane diisocyanate (Covestro Deutschland AG); isocyanate content 31.5 wt%, viscosity at 25 °C approximately 200 mPas

[0098] MDI700: Desmodur 44V70L, polymeric diphenylmethane diisocyanate (Covestro Deutschland AG); isocyanate content 30.9 wt%, viscosity at 25 °C approximately 700 mPas,

[0099] Benzoyl chloride: Obtained from Sigma-Aldrich; 99.5%; boiling point 198 °C

[0100] Tris(dimethylaminomethyl)phenol: Obtained from Sigma-Aldrich 95%; refractive index n20 / D 1.516, boiling point: 130 - 135 °C

[0101] Polyol 1: Aromatic polyester polyol (Synthesia Technology), with an OH value of 240 mg / kg KOH, functionality determined from the raw materials of 1.9 and viscosity at 25 °C of 1500 mPa*s

[0102] Polyol 2: Polyether diol (Covestro), with an OH value of 28 mg / kg KOH and a viscosity of 860 mPa*s at 25 °C, produced using 1,2-propanediol as the initiator and a mixture of ethylene oxide and propylene oxide in a ratio of 30:70 parts by weight

[0103] Polyol 3: Aromatic polyester polyol (Covestro), with an OH value of 370 mg / kg KOH, a functionality of 1.9 determined by raw material calculation, and a viscosity of 1400 mPa*s at 25 °C

[0104] Polyol 4: Aromatic polyester polyol (Covestro), with an OH value of 795 mg / kg KOH, a functionality of 2.0 determined by raw material calculation, and a viscosity of 1400 mPa*s at 25 °C

[0105] Polyol 5: Aromatic polyester polyol (Stepan Company), with an OH value of 240 mg / kg KOH, an acid value of 0.8, and a viscosity of 3000 mPa*s at 25 °C

[0106] Polyol 6: Polyether diol (Covestro), with an OH value of 35 mg / kg KOH and a viscosity of 860 mPa*s at 25 °C, produced using glycerol as the initiator and a mixture of ethylene oxide and propylene oxide in a ratio of 13:87 parts by weight, where ethylene oxide is added as the second block

[0107] Diethylene glycol: Diethylene glycol (Aldrich)

[0108] Triethyl phosphate: Flame retardant (Lanxess)

[0109] Disflamol DPK: Flame retardant (Lanxess)

[0110] Tegostab B8443: Foam stabilizer (Evonik)

[0111] DABCO LK443: Foam stabilizer (Evonik)

[0112] Desmorapid 1792: Potassium acetate catalyst (Covestro)

[0113] Desmorapid DB: Benzyl dimethylamine catalyst (Covestro)

[0114] Desmorapid VP.PU1221 VN: Catalyst (Covestro)

[0115] Desmorapid 1118: Catalyst (Covestro)

[0116] Tetramethylguanidine: 1,1,3,3 - Tetramethylguanidine (Aldrich)

[0117] n - Pentane: n - Pentane blowing agent (Aldrich)

[0118] Cyclopentane: Cyclopentane blowing agent (Aldrich)

[0119] Isopentane: Isopentane blowing agent (Aldrich)

[0120] Adhesion promoter: 2K Adhesion promoter (Covestro)

[0121] TCPP: Fyrol PCF Flame retardant (ICL)

[0122] Tegostab B8421: Foam stabilizer (Evonik)

[0123] Desmorapid PV: Pentamethyldiethylenetriamine catalyst (Covestro)

[0124] Kosmos 75MEG: Potassium octanoate catalyst (Biesterfeld)

[0125] Polyol mixture 1: A mixture consisting of the following components:

[0126] Polyol 1 parts by weight 79 Polyol 2 parts by weight 10 Triethyl phosphate parts by weight 8 TEGOSTABB 8443 parts by weight 2.5 Polyol 3 parts by weight 2 Polyol 4 parts by weight 0.5 Water parts by weight 0.5

[0127] Example 1: Production of Isocyanate 1 (the present invention)

[0128] Initially load 99.80 parts by weight of MDI 200 under dry nitrogen and heat to 60 °C. Add 0.17 parts by weight of tris(dimethylaminomethyl)phenol. Keep the reaction temperature constant at 60 ± 2 °C. After reaching the target viscosity of 700 mPas at 25 °C, add 0.03 parts by weight of benzoyl chloride and stir at 60 °C for 20 minutes. Viscosity, NCO content, and isocyanurate group content of Isocyanate 1: 678 mPas at 25 °C; NCO content: 29.92% NCO; 10.0 wt% isocyanurate groups.

[0129] The GPC of Isocyanate 1 is shown in Figure 1 - Table 1 shows the comparison of peak areas and number - average molecular weights obtained from the gel permeation chromatograms of Isocyanate 1 and Isocyanate 2.

[0130]

[0131] Figure 1: The RI signal of the gel permeation chromatogram of Isocyanate 1 with peak markings. The area corresponding to peak G is 5.0 area %.

[0132] The number average molecular weight Mn is 356 g / mol.

[0133] Example 2a*: Production of Isocyanate 2 (comparative redilution, not the present invention)

[0134] Initially load 99.80 parts by weight of MDI200 under dry nitrogen and heat to 60 °C. Add 0.17 parts by weight of tris(dimethylaminomethyl)phenol. Keep the reaction temperature constant at 60 ± 2 °C. After reaching the target viscosity of 3000 mPas at 25 °C, add 0.03 parts by weight of benzoyl chloride and stir at 60 °C for 20 minutes. Viscosity of the intermediate product: 3360 mPas at 25 °C; NCO content of the intermediate product: 28.52% NCO.

[0135] After termination of the trimerization reaction, subsequently add 94.97 parts by weight of MDI200 to establish the same viscosity and trimer content as in Isocyanate 1. The obtained Isocyanate 2 after mixing has a viscosity of 705 mPas at 25 °C, an NCO content of 29.91% NCO, and 10.0 wt% isocyanurate groups.

[0136] The area corresponding to peak G is 4.4 area %.

[0137] The number average molecular weight Mn is 346 g / mol.

[0138] Example 2b*: Production of Isocyanate 3 (comparative lower viscosity, DE 69116583 T2, not the present invention)

[0139] Initially load 99.80 parts by weight of MDI100 under dry nitrogen and heat to 60 °C. Add 0.17 parts by weight of tris(dimethylaminomethyl)phenol. Keep the reaction temperature constant at 60 ± 2 °C. When the NCO drops by approximately 1.5% NCO (corresponding to approximately 10 wt% isocyanurate groups), add 0.03 parts by weight of benzoyl chloride and stir at 60 °C for 20 minutes. Viscosity, NCO content, and isocyanurate group content of Isocyanate 3: 355 mPas at 25 °C; NCO content: 29.98% NCO; 11.4 wt% isocyanurate groups.

[0140] Example 2c*: Production of Isocyanate 4 (comparative semicarbazone catalyst, DE 69116583 T2, not the present invention)

[0141] 99.80 parts by weight of MDI 200 were initially charged under dry nitrogen and heated to 60 °C. 0.17 parts by weight of tetramethylguanidine were added. The reaction temperature was kept constant at 60 + / - 2 °C. In the case of a drop in NCO to about 1.5% NCO (corresponding to about 10% by weight of isocyanurate groups), 0.03 parts by weight of benzoyl chloride were added and stirred at 60 °C for 20 minutes. The reaction did not stop after the addition of benzoyl chloride. Subsequently, the reaction mass was cooled to room temperature. The reaction still did not stop but continued such that solids were present after 24 hours.

[0142] Table 1: Peak areas and number-average molecular weights obtained from gel permeation chromatograms of Isocyanate 1 and Isocyanate 2* Comparison

[0143]

[0144] Examples 3 - 6: Production of PUR / PIR foams

[0145] The isocyanate group- and isocyanurate group-containing compositions thus produced, i.e., isocyanates 1 and 2, were used for the production of PUR / PIR rigid foams and compared with a standardly used isocyanurate-free polyisocyanate composition of similar viscosity. In Table 2 below, in each case, Example 5 of the present invention containing the isocyanate group- and isocyanurate group-containing composition, i.e., isocyanate 1, Comparative Examples 3* and 4* containing the composition containing only isocyanate groups, i.e., MDI 700, and Comparative Example 6* containing the isocyanate group- and isocyanurate group-containing composition, i.e., isocyanate 2, were foamed with the same polyol formulation. For better comparability, the isocyanate compositions were replaced with the same parts by weight in each case, which resulted in a slight change in the index.

[0146] Table 2: Laboratory foaming

[0147]

[0148]

[0149] Experiments have shown that the use of the composition containing isocyanate groups and isocyanurate groups of the present invention, namely Isocyanate 1, enables the production of PUR / PIR rigid foams by weight ratio substitution of conventional pMDI (i.e., without adjusting the index), where in the comparison of their physical / mechanical properties and processing properties, the PUR / PIR rigid foams are not inferior to those made from conventional pMDI, and the indentation depth after 2.5 minutes and 5 minutes is significantly more excellent (Example 5). Example 6* of the present invention shows that although the re-dilution of highly viscous trimerized pMDI (viscosity greater than 2000 mPas at 25 °C before dilution, see the production of Isocyanate 2) to provide a composition containing isocyanate groups and isocyanurate groups (Isocyanate 2) with a viscosity of approximately 700 mPas brings the same advantages in terms of indentation depth after 2.5 minutes and 5 minutes, the PUR / PIR rigid foams do not show such good properties in the fire test.

[0150] Examples 7 - 9: Production of composite elements with a steel outer layer on a double belt

[0151] In each case, industrial-scale tests were carried out on the isocyanate components, namely Isocyanate 1, Isocyanate 2, and MDI700, on a double-layer conveyor belt with a steel outer layer (so-called metal panel, Table 3). The test conditions, input materials, and results are summarized in Table 3.

[0152] The results show that the use of the composition containing isocyanate groups and isocyanurate groups of the present invention, namely Isocyanate 1, enables the production of composite elements containing PUR / PIR rigid foams with comparable physical / mechanical properties and processing properties by weight ratio substitution of conventional pMDI (i.e., without adjusting the index) (Example 8). Example 9* of the present invention shows that although the re-dilution of highly viscous trimerized pMDI (viscosity greater than 2000 mPas at 25 °C before dilution, see the production of Isocyanate 2) to provide a composition containing isocyanate groups and isocyanurate groups (Isocyanate 2) brings the same mechanical properties, it also results in undesirable defects on the lower side of the metal plate and poor fire test results.

[0153] Table 3: Composite elements with a steel outer layer on a double-layer belt

[0154]

[0155]

[0156] Examples 10 - 12: Production of composite elements with an aluminum outer layer on a double belt

[0157] Industrial-scale tests on a double-layer conveyor belt with an aluminum outer layer (so-called heat-insulating panel; Table 4) have shown that the use of the composition containing isocyanate groups and isocyanurate groups according to the invention, i.e., Isocyanate 1, enables the production of composite elements containing PUR / PIR rigid foams with comparable physical / mechanical properties and processing properties by weight ratio substitution of conventional pMDI (i.e., without adjusting the index) (Example 11). Example 12* not according to the invention has shown that, although the use of a rediluted trimeric pMDI with a very high viscosity before redilution (viscosity greater than 2000 mPas at 25 °C before dilution, see production of Isocyanate 2) (to provide a composition containing isocyanate groups and isocyanurate groups (Isocyanate 2) of approximately 700 mPas) results in the same mechanical properties, it also leads to unacceptable defects at the outer layer, and the compressive strength in Example 11 of the invention (compressive strength) is superior to both Comparative Example 10* using conventional pMDI and Comparative Example 12*.

[0158] Laboratory-scale tests (so-called heat-insulating panel, Table 5) have shown that, compared with Isocyanate 3 not according to the invention (compared with DE69116583 T2, Example 14*), the use of the composition containing isocyanate groups and isocyanurate groups according to the invention, i.e., Isocyanate 1, exhibits advantages in terms of indentation depth after 3 minutes and 5 minutes and water absorption (Example 13). This is attributed to the high content of monomeric diphenylmethane diisocyanate. MDI100 used here is similar to the isocyanate used as an input material in DE69116583 T2. In Comparative Example 14*, the use of MDI100 led to a low functionality of Isocyanate 3 not according to the invention.

[0159] In summary, it must be pointed out that, compared with conventional MDI700 and the composition containing isocyanurate groups not according to the invention, i.e., Isocyanate 2, the use of the composition containing isocyanate groups and isocyanurate groups according to the invention, i.e., Isocyanate 1, brings advantages in terms of stackability of foam boards or initial strength measured as indentation depth after 2.5 minutes and 5 minutes, in terms of the quality of composite elements (especially the surface), and in terms of flame retardancy.

[0160] Table 4: Foaming on a double-layer conveyor belt with an aluminum outer layer

[0161]

[0162]

[0163] Table 5: Laboratory foaming

[0164] Parameters Unit Example 13 Example 14* DISFLAMOL DPK parts by weight 11.6 11.6 Polyol 6 parts by weight 10 10 DEG parts by weight 3.4 3.4 Water parts by weight 1.2 1.2 DABCOL K443 parts by weight 1 1 Polyol 4 parts by weight 1.8 1.8 Desmorapid VP.PU1221 VN parts by weight 1.2 1.2 Desmorapid 1118 parts by weight 3.6 3.6 Cyclopentane / isopentane 70 / 30 parts by weight 13.8 13.8 Isocyanate 1 parts by weight 100 Isocyanate 3 parts by weight 100 Index (100 NCO / OH) 267 272.1 Cream time [s] 21 20 Fiber time [s] 57 55 Surface dry time [s] 120 110 Dimensional stability after 24 hours, 100 °C [％] 0.4 / 0.3 / -0.3 0.3 / 0.6 / -0.1 Dimensional stability after 24 hours, -22 °C [％] -0.1 / 0.1 / 0.1 0.0 / -0.1 / 0.3 Indentation depth (3 min) [mm] -10.3 -16.4 Indentation depth (5 min) [mm] -11.1 -17.0 Water absorption [g] 9.5 11.7 Core apparent density <![CDATA[[kg / m 3 > 37.4 34.8 KBT / grading E E KBT / average maximum flame height [mm] 101 101

Claims

1. A process for producing composition A2 containing isocyanate groups and isocyanurate groups, which comprises the steps of: 1) reacting polyisocyanate A1 in the presence of a trimerization catalyst, and 2) terminating the reaction of step 1) with a suitable terminator to obtain composition A2; wherein the trimerization catalyst is not semicarbazide, a derivative of semicarbazide or a free radical initiator, and based on A1, the concentration of the trimerization catalyst used is <0.50% by weight, and wherein the polyisocyanate A1 used in step 1) is a polymeric MDI having a monomeric diphenylmethane diisocyanate content of <55% by weight and a viscosity at 25 °C of 130 to 400 mPa·s, preferably 140 to 400 mPa·s (measured without solvent according to DIN 53019-1:2008-09), and wherein step 2) is carried out when the reaction mixture from step 1) contains 5 - <13% by weight of isocyanurate groups and has a viscosity at 25 °C of <2000 mPa·s (measured without solvent according to DIN 53019-1:2008-09).

2. The process according to claim 1, wherein the polyisocyanate A1 used contains ≤50% by weight of monomeric MDI and / or has a viscosity at 25 °C of 140 to 300 mPa·s (measured without solvent according to DIN 53019-1:2008-09).

3. The process according to claim 1, wherein the terminator is a compound selected from acyl chlorides or Brønsted acids, provided that it is not a sulfonic acid, sulfuric acid or a derivative of these acids.

4. Composition A2 containing isocyanate groups and isocyanurate groups obtainable by the process according to any one of claims 1 to 3.

5. The composition A2 according to claim 4, characterized in that Having a seventh peak in its GPC with a peak area >4.6 area%, which corresponds to the fraction with the seventh lowest molecular weight.

6. Composition A2 according to any one of claims 4 or 5, which has a number average molecular weight Mn >350 g / mol.

7. The composition A2 according to any one of claims 4 to 6, characterized in that Having a viscosity at 25 °C of <1000 mPa·s (measured without solvent according to DIN 53019-1:2008-09).

8. Isocyanate component A, which contains composition A2 according to any one of claims 4 to 7.

9. A PUR / PIR system for producing PUR / PIR rigid foams from the isocyanate component A according to claim 8 and a polyol formulation B in the presence of a blowing agent C and optionally a catalyst D and auxiliaries and additives E.

10. The PUR / PIR system according to claim 9, characterized in that The isocyanate index of the foam is ≥250 to ≤450, preferably ≥320 to ≤400.

11. A process for producing PUR / PIR rigid foams by reacting the PUR / PIR system according to claim 9 or 10.

12. PUR / PIR rigid foams obtainable by the process according to claim 11.

13. Use of the PUR / PIR rigid foam according to claim 12 as a thermal insulation foam in the production of composite elements.

14. Composite element, comprising a rigid foam layer containing the PUR / PIR rigid foam according to claim 12 and at least one outer layer.

15. Composite element according to claim 14, wherein the material of the outer layer is aluminum, steel, bitumen, paper, mineral nonwoven fabric, nonwoven fabric containing organic fibers, plastic sheet, plastic film and / or wooden board.

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