CA2196148C - Low viscosity polyisocyanate mixtures and coating compositions prepared therefrom - Google Patents
Low viscosity polyisocyanate mixtures and coating compositions prepared therefrom Download PDFInfo
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- CA2196148C CA2196148C CA002196148A CA2196148A CA2196148C CA 2196148 C CA2196148 C CA 2196148C CA 002196148 A CA002196148 A CA 002196148A CA 2196148 A CA2196148 A CA 2196148A CA 2196148 C CA2196148 C CA 2196148C
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G18/00—Polymeric products of isocyanates or isothiocyanates
- C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
- C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
- C08G18/72—Polyisocyanates or polyisothiocyanates
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D251/00—Heterocyclic compounds containing 1,3,5-triazine rings
- C07D251/02—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings
- C07D251/12—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings having three double bonds between ring members or between ring members and non-ring members
- C07D251/26—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings having three double bonds between ring members or between ring members and non-ring members with only hetero atoms directly attached to ring carbon atoms
- C07D251/30—Only oxygen atoms
- C07D251/34—Cyanuric or isocyanuric esters
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G18/00—Polymeric products of isocyanates or isothiocyanates
- C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
- C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
- C08G18/72—Polyisocyanates or polyisothiocyanates
- C08G18/721—Two or more polyisocyanates not provided for in one single group C08G18/73 - C08G18/80
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G18/00—Polymeric products of isocyanates or isothiocyanates
- C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
- C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
- C08G18/72—Polyisocyanates or polyisothiocyanates
- C08G18/721—Two or more polyisocyanates not provided for in one single group C08G18/73 - C08G18/80
- C08G18/725—Combination of polyisocyanates of C08G18/78 with other polyisocyanates
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G18/00—Polymeric products of isocyanates or isothiocyanates
- C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
- C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
- C08G18/72—Polyisocyanates or polyisothiocyanates
- C08G18/77—Polyisocyanates or polyisothiocyanates having heteroatoms in addition to the isocyanate or isothiocyanate nitrogen and oxygen or sulfur
- C08G18/78—Nitrogen
- C08G18/79—Nitrogen characterised by the polyisocyanates used, these having groups formed by oligomerisation of isocyanates or isothiocyanates
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- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D175/00—Coating compositions based on polyureas or polyurethanes; Coating compositions based on derivatives of such polymers
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Abstract
The present invention relates to polyisocyanate mixtures containing 30 to 98 wt.%
of a polyisocyanate A) having a viscosity exceeding 700 mPa.s at 23°C
and 2 to 70 wt% of a (cyclo)aliphatic triisocyanate B) having a molecular weight of 200 to 600 and a viscosity below 200 mPa.s at 23°C, provided that the polyisocyanate mixtures have one-half of the viscosity of polyisocyanate component A) when triisocyanate B) is present in an amount of 30 wt.%, preferably in an amount of 20 wt.%, wherein the preceding percentages are based on the total weight of the polyisocyanate mixtures.
The present invention also relates to coating compositions containing these polyisocyanate mixtures, optionally in blocked form.
of a polyisocyanate A) having a viscosity exceeding 700 mPa.s at 23°C
and 2 to 70 wt% of a (cyclo)aliphatic triisocyanate B) having a molecular weight of 200 to 600 and a viscosity below 200 mPa.s at 23°C, provided that the polyisocyanate mixtures have one-half of the viscosity of polyisocyanate component A) when triisocyanate B) is present in an amount of 30 wt.%, preferably in an amount of 20 wt.%, wherein the preceding percentages are based on the total weight of the polyisocyanate mixtures.
The present invention also relates to coating compositions containing these polyisocyanate mixtures, optionally in blocked form.
Description
Le A 31 493-US /Eck/klu/S-P
I
LOW VISCOSITY POLYISOCYANATE MIXTURES AND COATING
COMPOSITIONS PREPARED THEREFROM
BACKGROUND OF THE INVENTION
Field of the Invention 7Che present invention relates to low viscosity polyisocyanate mixtures containing high viscosity polyisocyanates and low viscosity triisocyanate monomers.
Deseriution of the Prior Art Polyisocyanates, i.e, isocyanates having at least two NCO groups in the molecule, are of great economic importance in the production of synthetic materials, lacquers and coating compositions based on polyurethanes. Due to their reduced tendency to yellow under the influence of light, polyisocyanates exclusively containing (cycIo)aliphatically bound NCO groups are very important for producing high quality raw materials for lacquers and high grade coating compositions.
Low molecular weight aliphatic diisocyanates such as hexamethylene diisocyanate (HDI) or isophorone diisocyanate (IPDI) have an isocyanate functionality of 2, and due to their high vapor pressure cannot be used as such in the aforementioned applications for reasons of hygiene in the workplace. Therefore, use is made of various processes for modifying these diisocyanates, such as the formation of oligomers by reaction with difunctional or higher functional alcohols (prepoly merizatiop), biuretization and also trimerization accompanied by formation of iso cyanurate structures. A summary of these.processes pertaining to the state of the art is found in: H J Laas, R Halpaap and J Pedain, J. Prakt. Chem. 1994, 336, - 200.
It has been found that a mean--NCO functionality of the isocyanate hardener component of 3 to 4 is necessary for optimal properties for the lacquers and _ coating compositions that are produced from these polyisocyanates. Products of higher functionality do not provide any further substantial improvement in the mechanical and chemical resistance values; whereas, lower functionalities that lie clearly below 3 result in losses in quality of the end products, such as inadequate solvent resistance.
Le A 31 493-L1~ . ...
_2_ 2196148 One disadvantage of the state of the art systems that meet the aforementioned de-mands is that they generally have very high viscosities, which necessitates the use of solvents such as solvent naphtha, xylene, methoxypropyl acetate, etc., to obtain suitable processing viscosifies. These solvents escape during curing of the lacquer or coating, and if they are not disposed of (e.g., by incineration), they may pollute the environment as volatile organic compounds (VOC).
For this reason a number of substances and processes have been proposed which are intended to lower the viscosity of (lacquer) polyisocyanates without causing the VOC problems referred to. For example, the use of reactive thinners -i.e., substances which have a low specific viscosity, ordinarily below 200 mPa.s at 23°C, and which have isocyanate groups. Polyisocyanates of aliphatic diiso-cyanates, such as HDI, having a uretdione structure ("dimers") or an allophanate structure have proved particularly useful for this purpose (H J Laas, R
Halpaap and J Pedain, J. Prakt. Chem. 1994, 336, 196 - 198).
In this connection the viscosity of the polyisocyanate mixtures are independent of whether they were produced by simultaneously forming the higher - viscosity component (e.g., isocyanurates) and the lower viscosity component (e.g., allophanates) or whether products produced separately and containing pure iso cyanurate polyisocyanates and pure allophanate polyisocyanates are subsequently mixed.
Polyisocyanates that contain uretdione groups and also allophanate isocyanates, provided that they are prepared by reacting difunctional primary isocyanates with monoalcohols, are strictly difunctional. However, allophanates prepared from higher functional alcohols display no viscosity advantages when compared to biuret or isocyanurate polyisocyanates (DE-A 2,729,990). Therefore, itis apparent that the functionality of a polyisocyanate mixture is lowered by contamination, of whatever nature, with the aforementioned species. As demonstrated in Comparative Examples 1 and 2, to obtain a significant lowering of the viscosity of HDI polyisocyanates, such high concentrations of difunctional reactive thinners are necessary that the functionality of the resulting mixture is considerably less than 3.
To determine whether a significant lowering of viscosity has occurred in compositions containing the trirrier of HDI and reactive thinners, the viscosity of Le A 3~ .. . _____ _ __-___ _ _ these compositions must be compared to the viscosity that is known from the literature of the pure tris(6-isocyanato-hexyl)-isocyanurate, which is about 700 mPa.s at 23°C (see Example 3 and also D)rA 3,810,908; WO-A
93/07,183).
The pure monotrimer can be obtained as the principal product at very low conversion rates during the trimerization of HDI. The pure monotrimer can also be separated by extraction or distillation processes from mixtures, which also contain higher homologs, that are produced from monomeric HDI at higher conversion rates. However, neither of these processes are advantageous from an economic point of view. On the one hand the low conversion rates entail an IO enormous loss in the yield of resin and great expenditure of energy, due to the need to separate monomer from the product subsequent to the trimerization reaction. On the other hand the extraction and distillation processes bring about the inevitable accrual of higher viscosity fractions, in addition to the additional costs of the process.
These same difficulties apply to products that are obtained from diisocyanates other than HDI or by processes other than trimerization (formation of iso-cyanurate). Examples of these other processes include urethane polyisocyanates ("prepolymers"), biurets and allophanates.
Low viscosity aliphatic polyisocyanates having optimal functionality can also be produced by alternative synthesis reactions - e.g., by the reaction of silylated alcohols with isocyanatoalkanoic acid chlorides (Ch Zwiener, L Schmalstieg, M
Sonntag, K Nachtkamp and J Pedain, Farbe and Lack, 1991, 1052 -1057 and literature cited therein). One disadvantage of this process is the fact that iso-cyanatoalkanoic acid chlorides ara not commercially available and their handling may be problematic. The process could only be realized with great technical effort which is not offset by the expected advantages of the products, essentially the low viscosity of the polyisocyanates.
It is an object of the present invention to make available a polyisocyanate mixture which has distinctly reduced viscosity, in addition to retaining the properties of the known, state of the art products, in particular isocyanurate polyisocyanates.
To re-tain these properties the NCO functionality of the polyisocyanates according to the invention should be similar to the state of the art products, but in any case should be at least 3.
Le A 31 493-LTS
This object may be achieved in accordance with the present invention by mixing a polyisocyanate of higher viscosity (rl > 1,000 mPa.s at 23°C), for example one containing isocyanurate groups (trimers), with an NCO-trifunctional (cyclo)aliphatic polyisocyanate having a molecular weight of 200 to 600. Such (cyclo)aliphatic triisocyanates may be obtained according to the teachings of DE-A
3,109,276-C I, for example, by phosgenating the corresponding triamines and, al-though they boil at very high temperatures, subsequent distillation.
The exclusive use of these (cyclo)aliphatic triisocyanates as the hardener component in polyurethane coating compositions conflicts with their high NCO
content, which necessarily results in only a marginal reduction in the VOC
value of the coating composition. In addition, the vapor pressure of these triisocyanates is still not low enough and also a number of other disadvantages are found after the coating composition is formulated . - e.g., short pot-life, less than optimal drying, increased yellowing in the resulting coatings, etc (see M Ojunga-Andrew, H P Higginbottom and L W Hill, Waterborne, Higher Solids and Powder Coatings Symposium, Feb 22-24 1995, New Orleans, pages 200-210).
S-tTMMARY OF THE INVENTION
The present invention relates to palyisocyanate mixtures containing 30 to 98 wt.%
of a polyisocyanate A) having a viscosity exceeding 700 mPa.s at 23°C
and 2 to 70 wt.% of a (cyclo)aliphatic triisocyanate B) having a molecular weight of 200 to 600 and a viscosity below,200 mPa.s at 23°C, provided that the polyisocyanate mixtures have one-half c~f the viscosity of polyisocyanate component A) when tri-isocyanate B) is present in an amount of 30 wt.%, preferably in an amount of wt.%, wherein the preceding percentages are based on the total weight of the poly-isocyanate mixtures.
The present invention also relates to coating compositions containing these poly-isocyanate mixtures, optionally in blocked form.
BRIEF I3ESCRH'TION OF THE ~?RAWING
Figure 1 is a graph of the vapor pressure versus temperature for certain of the polyisocyanates described in the examples.
Le A 31 493-US
A surprising observation of the present invention is that the viscosity of polyiso-cyanates and polyisocyanate mixtures can be drastically reduced by the addition of very small amounts of (cyclo)aliphatic triisocyanates having a molecular weight of 200 to 600, whereas the addition of the known reactive thinners, which also have a very low specific viscosity (<_ 200 mPa.s at 23°C), results in only a very slow decrease in the viscosity as the percentage of reactive thinner increases in the polyisocyanate mixture. A further factor is that the known reactive thinners have a functionality of less than 3. Therefore when these reactive thinners are blended with polyisocyanates having viscosities exceeding 700 mPa.s and functionality of 3 to about 4.5, the functionality of the resulting mixture is 3 or less when its vis-cosity is reduced to the viscosity of the pure I3DI- homotrimer, i.e., about 700 mPa.s (Comparison Examples 1 to 3.).
On the other hand, when the aliphatic triisocyanates are blended according to the 1~5 invention with the same higher functionality polyisocyanates, only small propor-tions are needed to drastically reduce the viscosity, while only insignificantly reducing the functionality of the polyisocyanate mixture.
The polyisocyanate mixtures according to the invention are characterized both by their low viscosity and by a low vapor pressure that is lower than that of the tri-isocyanate component alone. Figure 1 r epresents a graph of vapor pressure versus temperature for three polyisocyanates, i.e., 1) the polyisocyanate mixture according to the invention from Table 6, No. 2, 2) the triisocyanate (NTI) used as one example of the low viscosity polyiso-cyanate components in accordance with the present invention and 3) a comparison polyisocyanate (component III, described in Examples 1 and 2), which is used as one of the low viscosity comparison polyisocyanates.
The polyisocyanate mixture according to the invention has a vapor pressure that is comparable to the comparison polyisocyanate and much lower than the vapor pressure of NTI. From the point of view of industrial hygiene the higher vapor pressure for NTI could be an obstacle to its exclusive use as NCO hardener component.
Le A 31 493-US
While preparing the polyisocyanate mixtures according to the invention, it is un-important whether the components are blended as the last process step or in a pre-ceding step, for example during the production of the higher viscosity polyiso-cyanate component. Given a sufficient difference between the boiling point or S enthalpy of evaporation of the monomeric compound employed used to produce the high viscosity polyisocyanate component (generally a diisocyanate or a diiso-cyanate mixture) and the boiling point or enthalpy of evaporation of the low vis-cosity (cyclo)aliphatic triisocyanate, it may be advantageous to admix the triiso-cyanate prior to separating unreacted monomer, e.g., by distillation, from the re-salting polyisocyanate containing, e.g., isocyanurate or biuret groups. In this way it is possible to liberate resins, which in themselves are very highly viscous, e.g, those based on cycloaliphatic diisocyanates, by distillation from monomeric diiso-cyanate at low temperatures. It is possible to conduct the distillation at these low temperatures only because of the presence of the triisocyanate. In the absence of this compound it would be necessary to conduct the distillation at a certain minimum temperature dictated by the melt viscosity of the resulting resin.
The low viscosity polyisocyanate mixtures according to the invention can also be blended with additional substances, such as the known reactive thinners, although this is not preferred. They may also be blended with lacquer solvents such as toluene, xylene, cyclohexane, chlorobenzene, butyl acetate, ethyl acetate, ethyl-glycol acetate, methoxypropyl acetate, acetone, white spirit, and aromatics with higher degrees of substitution, such as solvent naphtha, Solvesso, Shellsol, Isopar, IVappar and Diasol solvents. The low viscosity polyisocyanate mixtures may also contain additives, such as wetting agents, flow control agents, anti-skinning agents, anti-foaming agents, flatting agents, viscosity regulating substances, pigments, dyes, UV absorbers and thermal and oxidative stabilizers.
Suitable high viscosity polyisocyanates for use in the polyisocyanate mixtures according to the invention include all known polyisocyanates satisfying the pre-viously disclosed functionality and viscosity requirements, e.g., those containing urethane, biuret and isocyanurate groups, and also allophanate groups, such as those obtained by the allophanatization of aliphatic diisocyanates with dihydric and/or polyhydric alcohols as described, e.g., in DE-A 2,729,990 (U.S. Patent 4,160,080) . Other ex-amples of these polyisocyanate adducts are disclosed in U.S. Patent 5,523,376.
Le A 31 4~3-US
_7_ If these compounds are based on hexamethylene diisocyanate (HDI) and have a NCO-functionality > 3, they will not have a viscosity significantly less than 700 mPa~s at 23°C. Polyisocyanate adducts prepared from cycloaliphatic diiso-cyanates, such as isophorone diisocyanate (IPDI) or bis(isocyanatocyclohexyl)-methane (Desmodur W), are generally either solids or highly viscous oils (? 100,000 mPa~s) at room temperature.
Suitable (cycla)aliphatic triisocyanates having a molecular weight of 200 to are those corresponding to formula (I) OCN-(X)m ~ -(X7~ NCO
(I) NCO
wherein X, X' and X" are the same or different and represent -CR2-; -O-; -S-; -N(R')-;
-S(O)-; -S(O)2-; -O-S(O)2-; -O-S-(O)2-O-; divalent, four- to twelve-membered, preferably six-membered, optionally polycyclic cycloaliphatic residues, which optionally may contain additional substituents such as iso-cyanate groups or C1-C2o-alkyl groups which may be substituted by hetero-atoms (such as O, N or S);
R represents hydrogen or CI-CI2-alkyl;
R'- represent C1-C2o-alkyl;
Y is a trivalent radical such as CH, N or C4-C2o-cycloalkyl or -polycyclo-alkyl; and m, n and o are the same or different and represent zero or integers in which the sum ofm,nandois6to20.
Preferably X, X' and X" represent methylene groups, CH2; Y represents a methine linkage, CH; and the sum of m, n and o is 6 to 12.
These triisocyanates can be obtained from the corresponding triamines, optionally after their conversion into a derivative which is more readily susceptible to phos-Le A 31 493-L1S
~~96148 _8_ genation such as a (tris)hydrochloride, (tris)carbaminate or the like, by a known phosgenation reaction, e.g, in accordance with the teachings of DIrA 3,109,276 C1. They may also be synthesized by a phosgene-free method as described in M
Ojunga-Andrew, H P Higginbottom and L W Hill, Waterborne, Higher Solids and Powder Coatings Symposium, Feb. 22-24, 1995, New Orleans, pages 200-210, as well as the literature cited therein. In this connection they accrue as high boiling, almost odorless liquids having an NCO content of 21 to 63 wt.%.
In the following examples all parts and percentages are by weight, unless other-wise indicated. The viscosities were determined at 23°C using a "Rheomat 115"
rotational viscometer manufactured by Contraves. By taking measurements at dif ferent shear velocities it was ensured that the flow behavior of the polyisocyanate mixtures according to the invention and of the comparison corresponded to that of ideal Newtonian fluids. Therefore, the statement of the shear velocity was dis-pensed with.
The vapour pressures of the polyisocyanate mixtures according to the invention and of the comparison products Were determined by extrapolation with the aid of the Antoine equation to a temperature of 20 °C in accordance with the method de-fined in EC Directive 92/69/EEC, Appendix A4.
In the examples the measurements and observations that are essential to the in-vention, were based on the use of isocyanurate group-containing polyisocyanates prepared from HDI (HDI trimers) as the high viscosity polyisocyanate and triiso-cyanatononane (4-isocyanatomethyl-1,8-octanediisocyanate, "NTI") as the low vis-cosity triisocyanate. This has been done only for reasons of better comparability of the results obtained and does not signify any restriction of the invention to these products. The observations also apply to polyisocyanate mixtures based on polyisocyanates other than HDI or NTI and/or containing structural groups other than isocyanurates.
Le A 31 49~ "~ ", , EXAMPLES
Eyample 1 (Comparison Example) An HDI isocyanurate polyisocyanate having an average NCO functionality of 3.2, a viscosity at 23°C of 1,455 t 10 mPa.s and an equivalent weight of 187 (Component I) was blended with precisely weighed amounts of one of the follow-ing low viscosity reactive thinners:
a) an HDI uretdioneJisocyanurate polyisocyanate prepared in accordance with DE-OS 1 670 720 (Canadian Patent 837,636) and having an average NCO
functionality of 2.5, a viscosity at 23°C of 5 200 mPa.s and an equivalent weight of 187 (Component II), or b) an HDI allophanate polyisocyanate prepared from n-butanol in accordance with DE-A 2,729,990 (IT.S. Patent 4,160,080) and having an average NCO
functionality of 2.0, a viscosity at 23°C of S 200 mPa.s and an equivalent weight of 264 (Component III).
IS The viscosities of the homogeneous, clear polyisocyanate mixtures were then measured. The results are set forth in Tables 1 and 2.
Table 1 -No. Amount of Amount of Component Component II
I
2 90 10.0 1185 3 80.14 19.86 898 4 60.05 39.95 599 5 40.04 59.96 399 Le A 31 4 3-U _ _ _.
-lo_ ~~96148 No. Amount of Amount of r~~
Component I Com onent III
2 94.99 5.01 1346 3 89.96 10.04 1217 4 84.99 15.01 1097 80.01 19.99 937 6 70.2 29.98 818 7 60.02 39.98 658 8 50.07 49.93 539 9 19.98 80.02 300 le 2~Comparicnn Fx~mplel An I3DI isocyanurate polyisocyanate having an average NCO functionality of 3.5, a dynamic viscosity at 23°C of 3,720 t 100 mPa.s and an equivalent weight of 195 (Component IVY was blended with precisely weighed amounts of one of the following low viscosity reactive thinners:
a) an HDI uretdione/isocyanurate polyisocyanate prepared in accordance with DIrOS I 670 720 (Canadian Patent 837,636) and having an average NCO
functionality of 2.5, a viscosity at 23°C of <_ 200 mPa.s and an equivalent weight of 187 (Component II), or b) an HDI allophanate polyisocyanate prepared from n-butanol in accordance with DE-A 2,729,990 (U.S. Patent 4,160,080) and having an average NCO
functionality of 2.0, a viscosity at 23°C of _< 200 mPa.s and an equivalent weight of 264 (Component III).
The viscosities of the homogeneous, clear polyisocyanate mixtures were then measured. The results are set forth in Tables 3 and 4.
j a A 3--- i 4 ~~96I48 No. Amount of Amount of .Oa3 Component Component II
IV
3 80.07 19.93 1915 4 58.87 41.13 998 5 50.07 49.93 758 6 20.02 79.98 319 IO No. Amount of Amount of rla3 Com onent Component II
I
2 94.97 5.03 3112 3 90.05 9.95 2534 4 84.91 15.09 2294 S 79.87 20.13 1845 6 69.98 30.02 1456 7 60.13 39.87 1077 8 50.25 49.75 798 9 19.86 80.14 350 It can be seen from the results presented in Tables 1 to 4 that the gradual dilution of high viscosity polyisocyanate components I and IV with reactive-thinner components II and III results in a relatively slow decrease in the viscosity of the mixtures. In order to achieve . the viscosity of the pure I~I homotrimer (700 mPa.s, see Example 3), in each case at least 30 % of the reactive thinner has to be added. When a viscosity of 700 mPa.s was obtained for the mixtures used in Examples 1 and 2, the average NCO functionality of the polyisocyanate mixtures ranged from a maximum of 2.95 in Example la) and to a minimum of 2.58 in Example 2b).
As is shown in the following example, this viscosity can also be obtained with the almost pure ICI monotrimer, functionality n = 3. Therefore, the mixtures Le A 31 49~-t exemplified in Comparison Examples 1 and 2 represent no advance when com-pared to the state of the art polyisocyanates.
Fple 3 l~om~parative Exawlel 1500 g of Component I from Example 1 were subjected at a pressure of 0.05 mbar and at a temperature of 220°C to thin film distillation in a short-path evaporator.
In the process 267 g of distillate were collected. The distillate was then freed from monomeric HDI by thin film distillation at 120°C / 0.05 mbar. The resulting product had a viscosity of 700 t IO mPa.s at 23°C and, according to combined analytical methods (IR, NMR, GPC, MS), it contained 98% of the pure iso-cyanurate homotrimer of hexamethylenediisocyanate, i.e., 1,3,5-tris(6-isocyanato-hexyl)-isocyanurate.
These measurements are fully in accordance with data known from the literature, e.g., WO-A 93/07,183, wherein the viscosities set forth in the examples were measured at 25°C on less pure "ideal isocyanurate" fractions.
le 4 (Invention) An FiDI isocyanurate polyisocyanate having an average NCO functionality of 3.2, a viscosity at 23°C. of 1,455 ~ 10 mPa.s and an equivalent weight of (Component I) was blended with precisely weighed amounts of triisocyanato-nonane ("NTI", 4-isocyanatomethyl-1,8-octanediisocyanate, NCO functionality =
3, viscosity at 23°C <200 mPa.s, equivalent weight = 84 ). The viscosities of the homogeneous, clear polyisocyanate mixtures were then measured (Table 5).
Table S ~ . . . _. _ . ,- . . .. . .. .. .
No. Amount of Amount of Com onent I NTI
1 100 1446 t 10 2 89.24 10.76 .678 3 79.77 20.23 379 4 70.45 29.55 219 Le A 31 4g3- n~
~xamnle S (Inventiq_nlp An HDI isocyanurate polyisocyanate having an average NCO functionality of 3.5, a dynamic viscosity at 23°C of 3,720 f 100 mPa.s and an equivalent weight of 195 (Component I~ was blended with precisely weighed amounts of triisocyanto-nonane ("NTI", 4-isocyanatomethyl-1,8-octanediisocyanate, NCO functionality =
3, dynamic viscosity at 23°C <200 mPa.s, equivalent weight = 84). The viscosities of the homogeneous, clear polyisocyanate mixtures were then measured (Table 6).
No. Amount of Amount of qzs Component I NTI
1 100 3680 f 20 2 90.01 9.99 1845 3 79.98 20.02 695 4 69.61 30.39 339 It is apparent from the preceding examples that in order to lower the dynamic vis-cosily of the polyisocyanate mixtures according to the invention a much smaller amount of NTI is required to lower the viscosity of high viscosity polyisocyanate adducts when compared to the known reactive thinners used in Comparison Ex-amples l and 2.
Although the invention has been described in detail in the foregoing for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as it may be limited by the claims.
I
LOW VISCOSITY POLYISOCYANATE MIXTURES AND COATING
COMPOSITIONS PREPARED THEREFROM
BACKGROUND OF THE INVENTION
Field of the Invention 7Che present invention relates to low viscosity polyisocyanate mixtures containing high viscosity polyisocyanates and low viscosity triisocyanate monomers.
Deseriution of the Prior Art Polyisocyanates, i.e, isocyanates having at least two NCO groups in the molecule, are of great economic importance in the production of synthetic materials, lacquers and coating compositions based on polyurethanes. Due to their reduced tendency to yellow under the influence of light, polyisocyanates exclusively containing (cycIo)aliphatically bound NCO groups are very important for producing high quality raw materials for lacquers and high grade coating compositions.
Low molecular weight aliphatic diisocyanates such as hexamethylene diisocyanate (HDI) or isophorone diisocyanate (IPDI) have an isocyanate functionality of 2, and due to their high vapor pressure cannot be used as such in the aforementioned applications for reasons of hygiene in the workplace. Therefore, use is made of various processes for modifying these diisocyanates, such as the formation of oligomers by reaction with difunctional or higher functional alcohols (prepoly merizatiop), biuretization and also trimerization accompanied by formation of iso cyanurate structures. A summary of these.processes pertaining to the state of the art is found in: H J Laas, R Halpaap and J Pedain, J. Prakt. Chem. 1994, 336, - 200.
It has been found that a mean--NCO functionality of the isocyanate hardener component of 3 to 4 is necessary for optimal properties for the lacquers and _ coating compositions that are produced from these polyisocyanates. Products of higher functionality do not provide any further substantial improvement in the mechanical and chemical resistance values; whereas, lower functionalities that lie clearly below 3 result in losses in quality of the end products, such as inadequate solvent resistance.
Le A 31 493-L1~ . ...
_2_ 2196148 One disadvantage of the state of the art systems that meet the aforementioned de-mands is that they generally have very high viscosities, which necessitates the use of solvents such as solvent naphtha, xylene, methoxypropyl acetate, etc., to obtain suitable processing viscosifies. These solvents escape during curing of the lacquer or coating, and if they are not disposed of (e.g., by incineration), they may pollute the environment as volatile organic compounds (VOC).
For this reason a number of substances and processes have been proposed which are intended to lower the viscosity of (lacquer) polyisocyanates without causing the VOC problems referred to. For example, the use of reactive thinners -i.e., substances which have a low specific viscosity, ordinarily below 200 mPa.s at 23°C, and which have isocyanate groups. Polyisocyanates of aliphatic diiso-cyanates, such as HDI, having a uretdione structure ("dimers") or an allophanate structure have proved particularly useful for this purpose (H J Laas, R
Halpaap and J Pedain, J. Prakt. Chem. 1994, 336, 196 - 198).
In this connection the viscosity of the polyisocyanate mixtures are independent of whether they were produced by simultaneously forming the higher - viscosity component (e.g., isocyanurates) and the lower viscosity component (e.g., allophanates) or whether products produced separately and containing pure iso cyanurate polyisocyanates and pure allophanate polyisocyanates are subsequently mixed.
Polyisocyanates that contain uretdione groups and also allophanate isocyanates, provided that they are prepared by reacting difunctional primary isocyanates with monoalcohols, are strictly difunctional. However, allophanates prepared from higher functional alcohols display no viscosity advantages when compared to biuret or isocyanurate polyisocyanates (DE-A 2,729,990). Therefore, itis apparent that the functionality of a polyisocyanate mixture is lowered by contamination, of whatever nature, with the aforementioned species. As demonstrated in Comparative Examples 1 and 2, to obtain a significant lowering of the viscosity of HDI polyisocyanates, such high concentrations of difunctional reactive thinners are necessary that the functionality of the resulting mixture is considerably less than 3.
To determine whether a significant lowering of viscosity has occurred in compositions containing the trirrier of HDI and reactive thinners, the viscosity of Le A 3~ .. . _____ _ __-___ _ _ these compositions must be compared to the viscosity that is known from the literature of the pure tris(6-isocyanato-hexyl)-isocyanurate, which is about 700 mPa.s at 23°C (see Example 3 and also D)rA 3,810,908; WO-A
93/07,183).
The pure monotrimer can be obtained as the principal product at very low conversion rates during the trimerization of HDI. The pure monotrimer can also be separated by extraction or distillation processes from mixtures, which also contain higher homologs, that are produced from monomeric HDI at higher conversion rates. However, neither of these processes are advantageous from an economic point of view. On the one hand the low conversion rates entail an IO enormous loss in the yield of resin and great expenditure of energy, due to the need to separate monomer from the product subsequent to the trimerization reaction. On the other hand the extraction and distillation processes bring about the inevitable accrual of higher viscosity fractions, in addition to the additional costs of the process.
These same difficulties apply to products that are obtained from diisocyanates other than HDI or by processes other than trimerization (formation of iso-cyanurate). Examples of these other processes include urethane polyisocyanates ("prepolymers"), biurets and allophanates.
Low viscosity aliphatic polyisocyanates having optimal functionality can also be produced by alternative synthesis reactions - e.g., by the reaction of silylated alcohols with isocyanatoalkanoic acid chlorides (Ch Zwiener, L Schmalstieg, M
Sonntag, K Nachtkamp and J Pedain, Farbe and Lack, 1991, 1052 -1057 and literature cited therein). One disadvantage of this process is the fact that iso-cyanatoalkanoic acid chlorides ara not commercially available and their handling may be problematic. The process could only be realized with great technical effort which is not offset by the expected advantages of the products, essentially the low viscosity of the polyisocyanates.
It is an object of the present invention to make available a polyisocyanate mixture which has distinctly reduced viscosity, in addition to retaining the properties of the known, state of the art products, in particular isocyanurate polyisocyanates.
To re-tain these properties the NCO functionality of the polyisocyanates according to the invention should be similar to the state of the art products, but in any case should be at least 3.
Le A 31 493-LTS
This object may be achieved in accordance with the present invention by mixing a polyisocyanate of higher viscosity (rl > 1,000 mPa.s at 23°C), for example one containing isocyanurate groups (trimers), with an NCO-trifunctional (cyclo)aliphatic polyisocyanate having a molecular weight of 200 to 600. Such (cyclo)aliphatic triisocyanates may be obtained according to the teachings of DE-A
3,109,276-C I, for example, by phosgenating the corresponding triamines and, al-though they boil at very high temperatures, subsequent distillation.
The exclusive use of these (cyclo)aliphatic triisocyanates as the hardener component in polyurethane coating compositions conflicts with their high NCO
content, which necessarily results in only a marginal reduction in the VOC
value of the coating composition. In addition, the vapor pressure of these triisocyanates is still not low enough and also a number of other disadvantages are found after the coating composition is formulated . - e.g., short pot-life, less than optimal drying, increased yellowing in the resulting coatings, etc (see M Ojunga-Andrew, H P Higginbottom and L W Hill, Waterborne, Higher Solids and Powder Coatings Symposium, Feb 22-24 1995, New Orleans, pages 200-210).
S-tTMMARY OF THE INVENTION
The present invention relates to palyisocyanate mixtures containing 30 to 98 wt.%
of a polyisocyanate A) having a viscosity exceeding 700 mPa.s at 23°C
and 2 to 70 wt.% of a (cyclo)aliphatic triisocyanate B) having a molecular weight of 200 to 600 and a viscosity below,200 mPa.s at 23°C, provided that the polyisocyanate mixtures have one-half c~f the viscosity of polyisocyanate component A) when tri-isocyanate B) is present in an amount of 30 wt.%, preferably in an amount of wt.%, wherein the preceding percentages are based on the total weight of the poly-isocyanate mixtures.
The present invention also relates to coating compositions containing these poly-isocyanate mixtures, optionally in blocked form.
BRIEF I3ESCRH'TION OF THE ~?RAWING
Figure 1 is a graph of the vapor pressure versus temperature for certain of the polyisocyanates described in the examples.
Le A 31 493-US
A surprising observation of the present invention is that the viscosity of polyiso-cyanates and polyisocyanate mixtures can be drastically reduced by the addition of very small amounts of (cyclo)aliphatic triisocyanates having a molecular weight of 200 to 600, whereas the addition of the known reactive thinners, which also have a very low specific viscosity (<_ 200 mPa.s at 23°C), results in only a very slow decrease in the viscosity as the percentage of reactive thinner increases in the polyisocyanate mixture. A further factor is that the known reactive thinners have a functionality of less than 3. Therefore when these reactive thinners are blended with polyisocyanates having viscosities exceeding 700 mPa.s and functionality of 3 to about 4.5, the functionality of the resulting mixture is 3 or less when its vis-cosity is reduced to the viscosity of the pure I3DI- homotrimer, i.e., about 700 mPa.s (Comparison Examples 1 to 3.).
On the other hand, when the aliphatic triisocyanates are blended according to the 1~5 invention with the same higher functionality polyisocyanates, only small propor-tions are needed to drastically reduce the viscosity, while only insignificantly reducing the functionality of the polyisocyanate mixture.
The polyisocyanate mixtures according to the invention are characterized both by their low viscosity and by a low vapor pressure that is lower than that of the tri-isocyanate component alone. Figure 1 r epresents a graph of vapor pressure versus temperature for three polyisocyanates, i.e., 1) the polyisocyanate mixture according to the invention from Table 6, No. 2, 2) the triisocyanate (NTI) used as one example of the low viscosity polyiso-cyanate components in accordance with the present invention and 3) a comparison polyisocyanate (component III, described in Examples 1 and 2), which is used as one of the low viscosity comparison polyisocyanates.
The polyisocyanate mixture according to the invention has a vapor pressure that is comparable to the comparison polyisocyanate and much lower than the vapor pressure of NTI. From the point of view of industrial hygiene the higher vapor pressure for NTI could be an obstacle to its exclusive use as NCO hardener component.
Le A 31 493-US
While preparing the polyisocyanate mixtures according to the invention, it is un-important whether the components are blended as the last process step or in a pre-ceding step, for example during the production of the higher viscosity polyiso-cyanate component. Given a sufficient difference between the boiling point or S enthalpy of evaporation of the monomeric compound employed used to produce the high viscosity polyisocyanate component (generally a diisocyanate or a diiso-cyanate mixture) and the boiling point or enthalpy of evaporation of the low vis-cosity (cyclo)aliphatic triisocyanate, it may be advantageous to admix the triiso-cyanate prior to separating unreacted monomer, e.g., by distillation, from the re-salting polyisocyanate containing, e.g., isocyanurate or biuret groups. In this way it is possible to liberate resins, which in themselves are very highly viscous, e.g, those based on cycloaliphatic diisocyanates, by distillation from monomeric diiso-cyanate at low temperatures. It is possible to conduct the distillation at these low temperatures only because of the presence of the triisocyanate. In the absence of this compound it would be necessary to conduct the distillation at a certain minimum temperature dictated by the melt viscosity of the resulting resin.
The low viscosity polyisocyanate mixtures according to the invention can also be blended with additional substances, such as the known reactive thinners, although this is not preferred. They may also be blended with lacquer solvents such as toluene, xylene, cyclohexane, chlorobenzene, butyl acetate, ethyl acetate, ethyl-glycol acetate, methoxypropyl acetate, acetone, white spirit, and aromatics with higher degrees of substitution, such as solvent naphtha, Solvesso, Shellsol, Isopar, IVappar and Diasol solvents. The low viscosity polyisocyanate mixtures may also contain additives, such as wetting agents, flow control agents, anti-skinning agents, anti-foaming agents, flatting agents, viscosity regulating substances, pigments, dyes, UV absorbers and thermal and oxidative stabilizers.
Suitable high viscosity polyisocyanates for use in the polyisocyanate mixtures according to the invention include all known polyisocyanates satisfying the pre-viously disclosed functionality and viscosity requirements, e.g., those containing urethane, biuret and isocyanurate groups, and also allophanate groups, such as those obtained by the allophanatization of aliphatic diisocyanates with dihydric and/or polyhydric alcohols as described, e.g., in DE-A 2,729,990 (U.S. Patent 4,160,080) . Other ex-amples of these polyisocyanate adducts are disclosed in U.S. Patent 5,523,376.
Le A 31 4~3-US
_7_ If these compounds are based on hexamethylene diisocyanate (HDI) and have a NCO-functionality > 3, they will not have a viscosity significantly less than 700 mPa~s at 23°C. Polyisocyanate adducts prepared from cycloaliphatic diiso-cyanates, such as isophorone diisocyanate (IPDI) or bis(isocyanatocyclohexyl)-methane (Desmodur W), are generally either solids or highly viscous oils (? 100,000 mPa~s) at room temperature.
Suitable (cycla)aliphatic triisocyanates having a molecular weight of 200 to are those corresponding to formula (I) OCN-(X)m ~ -(X7~ NCO
(I) NCO
wherein X, X' and X" are the same or different and represent -CR2-; -O-; -S-; -N(R')-;
-S(O)-; -S(O)2-; -O-S(O)2-; -O-S-(O)2-O-; divalent, four- to twelve-membered, preferably six-membered, optionally polycyclic cycloaliphatic residues, which optionally may contain additional substituents such as iso-cyanate groups or C1-C2o-alkyl groups which may be substituted by hetero-atoms (such as O, N or S);
R represents hydrogen or CI-CI2-alkyl;
R'- represent C1-C2o-alkyl;
Y is a trivalent radical such as CH, N or C4-C2o-cycloalkyl or -polycyclo-alkyl; and m, n and o are the same or different and represent zero or integers in which the sum ofm,nandois6to20.
Preferably X, X' and X" represent methylene groups, CH2; Y represents a methine linkage, CH; and the sum of m, n and o is 6 to 12.
These triisocyanates can be obtained from the corresponding triamines, optionally after their conversion into a derivative which is more readily susceptible to phos-Le A 31 493-L1S
~~96148 _8_ genation such as a (tris)hydrochloride, (tris)carbaminate or the like, by a known phosgenation reaction, e.g, in accordance with the teachings of DIrA 3,109,276 C1. They may also be synthesized by a phosgene-free method as described in M
Ojunga-Andrew, H P Higginbottom and L W Hill, Waterborne, Higher Solids and Powder Coatings Symposium, Feb. 22-24, 1995, New Orleans, pages 200-210, as well as the literature cited therein. In this connection they accrue as high boiling, almost odorless liquids having an NCO content of 21 to 63 wt.%.
In the following examples all parts and percentages are by weight, unless other-wise indicated. The viscosities were determined at 23°C using a "Rheomat 115"
rotational viscometer manufactured by Contraves. By taking measurements at dif ferent shear velocities it was ensured that the flow behavior of the polyisocyanate mixtures according to the invention and of the comparison corresponded to that of ideal Newtonian fluids. Therefore, the statement of the shear velocity was dis-pensed with.
The vapour pressures of the polyisocyanate mixtures according to the invention and of the comparison products Were determined by extrapolation with the aid of the Antoine equation to a temperature of 20 °C in accordance with the method de-fined in EC Directive 92/69/EEC, Appendix A4.
In the examples the measurements and observations that are essential to the in-vention, were based on the use of isocyanurate group-containing polyisocyanates prepared from HDI (HDI trimers) as the high viscosity polyisocyanate and triiso-cyanatononane (4-isocyanatomethyl-1,8-octanediisocyanate, "NTI") as the low vis-cosity triisocyanate. This has been done only for reasons of better comparability of the results obtained and does not signify any restriction of the invention to these products. The observations also apply to polyisocyanate mixtures based on polyisocyanates other than HDI or NTI and/or containing structural groups other than isocyanurates.
Le A 31 49~ "~ ", , EXAMPLES
Eyample 1 (Comparison Example) An HDI isocyanurate polyisocyanate having an average NCO functionality of 3.2, a viscosity at 23°C of 1,455 t 10 mPa.s and an equivalent weight of 187 (Component I) was blended with precisely weighed amounts of one of the follow-ing low viscosity reactive thinners:
a) an HDI uretdioneJisocyanurate polyisocyanate prepared in accordance with DE-OS 1 670 720 (Canadian Patent 837,636) and having an average NCO
functionality of 2.5, a viscosity at 23°C of 5 200 mPa.s and an equivalent weight of 187 (Component II), or b) an HDI allophanate polyisocyanate prepared from n-butanol in accordance with DE-A 2,729,990 (IT.S. Patent 4,160,080) and having an average NCO
functionality of 2.0, a viscosity at 23°C of S 200 mPa.s and an equivalent weight of 264 (Component III).
IS The viscosities of the homogeneous, clear polyisocyanate mixtures were then measured. The results are set forth in Tables 1 and 2.
Table 1 -No. Amount of Amount of Component Component II
I
2 90 10.0 1185 3 80.14 19.86 898 4 60.05 39.95 599 5 40.04 59.96 399 Le A 31 4 3-U _ _ _.
-lo_ ~~96148 No. Amount of Amount of r~~
Component I Com onent III
2 94.99 5.01 1346 3 89.96 10.04 1217 4 84.99 15.01 1097 80.01 19.99 937 6 70.2 29.98 818 7 60.02 39.98 658 8 50.07 49.93 539 9 19.98 80.02 300 le 2~Comparicnn Fx~mplel An I3DI isocyanurate polyisocyanate having an average NCO functionality of 3.5, a dynamic viscosity at 23°C of 3,720 t 100 mPa.s and an equivalent weight of 195 (Component IVY was blended with precisely weighed amounts of one of the following low viscosity reactive thinners:
a) an HDI uretdione/isocyanurate polyisocyanate prepared in accordance with DIrOS I 670 720 (Canadian Patent 837,636) and having an average NCO
functionality of 2.5, a viscosity at 23°C of <_ 200 mPa.s and an equivalent weight of 187 (Component II), or b) an HDI allophanate polyisocyanate prepared from n-butanol in accordance with DE-A 2,729,990 (U.S. Patent 4,160,080) and having an average NCO
functionality of 2.0, a viscosity at 23°C of _< 200 mPa.s and an equivalent weight of 264 (Component III).
The viscosities of the homogeneous, clear polyisocyanate mixtures were then measured. The results are set forth in Tables 3 and 4.
j a A 3--- i 4 ~~96I48 No. Amount of Amount of .Oa3 Component Component II
IV
3 80.07 19.93 1915 4 58.87 41.13 998 5 50.07 49.93 758 6 20.02 79.98 319 IO No. Amount of Amount of rla3 Com onent Component II
I
2 94.97 5.03 3112 3 90.05 9.95 2534 4 84.91 15.09 2294 S 79.87 20.13 1845 6 69.98 30.02 1456 7 60.13 39.87 1077 8 50.25 49.75 798 9 19.86 80.14 350 It can be seen from the results presented in Tables 1 to 4 that the gradual dilution of high viscosity polyisocyanate components I and IV with reactive-thinner components II and III results in a relatively slow decrease in the viscosity of the mixtures. In order to achieve . the viscosity of the pure I~I homotrimer (700 mPa.s, see Example 3), in each case at least 30 % of the reactive thinner has to be added. When a viscosity of 700 mPa.s was obtained for the mixtures used in Examples 1 and 2, the average NCO functionality of the polyisocyanate mixtures ranged from a maximum of 2.95 in Example la) and to a minimum of 2.58 in Example 2b).
As is shown in the following example, this viscosity can also be obtained with the almost pure ICI monotrimer, functionality n = 3. Therefore, the mixtures Le A 31 49~-t exemplified in Comparison Examples 1 and 2 represent no advance when com-pared to the state of the art polyisocyanates.
Fple 3 l~om~parative Exawlel 1500 g of Component I from Example 1 were subjected at a pressure of 0.05 mbar and at a temperature of 220°C to thin film distillation in a short-path evaporator.
In the process 267 g of distillate were collected. The distillate was then freed from monomeric HDI by thin film distillation at 120°C / 0.05 mbar. The resulting product had a viscosity of 700 t IO mPa.s at 23°C and, according to combined analytical methods (IR, NMR, GPC, MS), it contained 98% of the pure iso-cyanurate homotrimer of hexamethylenediisocyanate, i.e., 1,3,5-tris(6-isocyanato-hexyl)-isocyanurate.
These measurements are fully in accordance with data known from the literature, e.g., WO-A 93/07,183, wherein the viscosities set forth in the examples were measured at 25°C on less pure "ideal isocyanurate" fractions.
le 4 (Invention) An FiDI isocyanurate polyisocyanate having an average NCO functionality of 3.2, a viscosity at 23°C. of 1,455 ~ 10 mPa.s and an equivalent weight of (Component I) was blended with precisely weighed amounts of triisocyanato-nonane ("NTI", 4-isocyanatomethyl-1,8-octanediisocyanate, NCO functionality =
3, viscosity at 23°C <200 mPa.s, equivalent weight = 84 ). The viscosities of the homogeneous, clear polyisocyanate mixtures were then measured (Table 5).
Table S ~ . . . _. _ . ,- . . .. . .. .. .
No. Amount of Amount of Com onent I NTI
1 100 1446 t 10 2 89.24 10.76 .678 3 79.77 20.23 379 4 70.45 29.55 219 Le A 31 4g3- n~
~xamnle S (Inventiq_nlp An HDI isocyanurate polyisocyanate having an average NCO functionality of 3.5, a dynamic viscosity at 23°C of 3,720 f 100 mPa.s and an equivalent weight of 195 (Component I~ was blended with precisely weighed amounts of triisocyanto-nonane ("NTI", 4-isocyanatomethyl-1,8-octanediisocyanate, NCO functionality =
3, dynamic viscosity at 23°C <200 mPa.s, equivalent weight = 84). The viscosities of the homogeneous, clear polyisocyanate mixtures were then measured (Table 6).
No. Amount of Amount of qzs Component I NTI
1 100 3680 f 20 2 90.01 9.99 1845 3 79.98 20.02 695 4 69.61 30.39 339 It is apparent from the preceding examples that in order to lower the dynamic vis-cosily of the polyisocyanate mixtures according to the invention a much smaller amount of NTI is required to lower the viscosity of high viscosity polyisocyanate adducts when compared to the known reactive thinners used in Comparison Ex-amples l and 2.
Although the invention has been described in detail in the foregoing for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as it may be limited by the claims.
Claims (7)
1. ~A polyisocyanate mixture containing 30 to 98 wt.% of a polyisocyanate A) having a viscosity exceeding 700 mPa.s at 23°C and 2 to 70 wt.% of a (cyclo)aliphatic triisocyanate B) having a molecular weight of 200 to 600 and a viscosity below 200 mPa.s at 23°C, provided that the polyisocyanatemixture has one-half of the viscosity of polyisocyanate A) when triisocyanate B) is present in an amount of 30 wt.%, wherein the preceding percentages are based on the total weight of the polyisocyanate mixture.
2. ~The polyisocyanate mixture of claim 1, wherein triisocyanate B) corresponds to formula (I):
wherein X, X' and X" are the same or different and represent -CR2-; -O-; -S-; -N(R')-; -S(O)-; -S(O)2-; -O-S(O)2-, -O-S-(O)2-O-; divalent, four- to twelve-membered, optionally polycyclic cycloaliphatic residues, which optionally may contain isocyanate groups or C1-C20-alkyl groups which may be substituted by heteroatoms O, N or S;
R represents hydrogen or C1-C12-alkyl;
R' represents C1-C20-alkyl;
Y is a trivalent radical such as CH, N or C4-C20-cycloalkyl or -poly-cycloalkyl; and m, n and o are the same or different and represent zero or integers in which the sum of m, n and o is 6 to 20.
wherein X, X' and X" are the same or different and represent -CR2-; -O-; -S-; -N(R')-; -S(O)-; -S(O)2-; -O-S(O)2-, -O-S-(O)2-O-; divalent, four- to twelve-membered, optionally polycyclic cycloaliphatic residues, which optionally may contain isocyanate groups or C1-C20-alkyl groups which may be substituted by heteroatoms O, N or S;
R represents hydrogen or C1-C12-alkyl;
R' represents C1-C20-alkyl;
Y is a trivalent radical such as CH, N or C4-C20-cycloalkyl or -poly-cycloalkyl; and m, n and o are the same or different and represent zero or integers in which the sum of m, n and o is 6 to 20.
3. ~The polyisocyanate mixture of claim 2, wherein X, X' and X°' represent methylene groups; Y represents a methine linkage; and the sum of m, n and o is to 12.
4. ~The polyisocyanate mixture of claim 1, wherein polyisocyanate A) is prepared from 1,6-hexamethylene diisocyanate and contains urethane, biuret, isocyanurate and/or allophanate groups.
5. ~The polyisocyanate mixture of claim 2, wherein polyisocyanate A) is prepared from 1,6-hexamethylene diisocyanate and contains urethane, biuret, isocyanurate and/or allophanate groups.
6. ~The polyisocyanate mixture of claim 3, wherein polyisocyanate A) is prepared from 1,6-hexamethylene diisocyanate and contains urethane, biuret, isocyanurate and/or allophanate groups.
7. ~A composition that is suitable for the preparation of optionally foamed polyisocyanate polyaddition products which comprises the polyisocyanate mixtures of claim 1, in which the isocyanate groups may optionally be blocked, and an isocyanate-reactive compound.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19603736A DE19603736A1 (en) | 1996-02-02 | 1996-02-02 | Low viscosity polyisocyanate mixture |
| DE19603736.0 | 1996-02-02 |
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|---|---|
| CA2196148A1 CA2196148A1 (en) | 1997-08-03 |
| CA2196148C true CA2196148C (en) | 2006-08-15 |
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| CA002196148A Expired - Fee Related CA2196148C (en) | 1996-02-02 | 1997-01-28 | Low viscosity polyisocyanate mixtures and coating compositions prepared therefrom |
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| EP (1) | EP0787752B1 (en) |
| JP (1) | JPH09216930A (en) |
| KR (1) | KR100465270B1 (en) |
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| BR (1) | BR9700840A (en) |
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| DE19611849A1 (en) * | 1996-03-26 | 1997-10-02 | Bayer Ag | New isocyanate trimer and isocyanate trimer mixtures, their production and use |
| DE19828935A1 (en) * | 1998-06-29 | 1999-12-30 | Basf Ag | High viscosity polyisocyanate composition useful as a surface coating |
| EP1347004B1 (en) * | 2000-11-27 | 2016-04-27 | Asahi Kasei Kabushiki Kaisha | High-solid coating composition |
| US7268202B2 (en) | 2001-09-20 | 2007-09-11 | Asahi Kasei Chemicals Corporation | Polyisocyanate composition having allophanate group and high-solid coating material |
| JP4974343B2 (en) * | 2006-06-13 | 2012-07-11 | 旭化成ケミカルズ株式会社 | Water-based polyisocyanate composition and water-based coating composition containing the same |
| JP6153293B2 (en) * | 2012-05-11 | 2017-06-28 | 旭化成株式会社 | Block polyisocyanate composition |
| EP3527599B1 (en) | 2016-10-14 | 2021-04-14 | Asahi Kasei Kabushiki Kaisha | Polyisocyanate mixture, coating composition, and coating film |
| JP2019014777A (en) * | 2017-07-04 | 2019-01-31 | 旭化成株式会社 | Polyisocyanate composition, dilution solution of polyisocyanate composition, coating composition and coating film |
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| DE1670720A1 (en) | 1966-07-21 | 1971-01-14 | Bayer Ag | Process for the preparation of aliphatically substituted uretdiones |
| GB1483957A (en) * | 1975-05-19 | 1977-08-24 | Ici Ltd | Diphenylmethane diisocyanate compositions |
| DE2729990A1 (en) | 1977-07-02 | 1979-01-18 | Bayer Ag | PROCESS FOR THE PREPARATION OF ALLOPHANATES HAVING ISOCYANATE GROUPS |
| JPS56127341A (en) | 1980-03-11 | 1981-10-06 | Asahi Chem Ind Co Ltd | New aliphatic triisocyanate, its preparation and nonyellowing polyurethane resin hardener composed thereof |
| GB2203159B (en) | 1987-04-03 | 1990-12-12 | Asahi Chemical Ind | An isocyanurate polyisocyanate and its use as a curing agent for a two-component polyurethane composition |
| DE4029809A1 (en) * | 1990-09-20 | 1992-03-26 | Bayer Ag | POLYISOCYANATE MIXTURE, A METHOD FOR THE PRODUCTION THEREOF AND ITS USE IN POLYURETHANE PAINTS |
| US5298431A (en) | 1991-09-30 | 1994-03-29 | Olin Corporation | Process for producing low viscosity isocyanate trimers |
| DE4426131A1 (en) * | 1994-07-22 | 1996-01-25 | Bayer Ag | Non-fading, solvent-free polyurethane coating agents and their use |
-
1996
- 1996-02-02 DE DE19603736A patent/DE19603736A1/en not_active Withdrawn
-
1997
- 1997-01-21 AT AT97100855T patent/ATE236942T1/en not_active IP Right Cessation
- 1997-01-21 ES ES97100855T patent/ES2196200T3/en not_active Expired - Lifetime
- 1997-01-21 DE DE59709731T patent/DE59709731D1/en not_active Expired - Lifetime
- 1997-01-21 EP EP97100855A patent/EP0787752B1/en not_active Expired - Lifetime
- 1997-01-28 CA CA002196148A patent/CA2196148C/en not_active Expired - Fee Related
- 1997-01-29 JP JP9028339A patent/JPH09216930A/en active Pending
- 1997-01-31 BR BR9700840A patent/BR9700840A/en unknown
- 1997-01-31 MX MX9700823A patent/MX9700823A/en not_active IP Right Cessation
- 1997-02-01 KR KR1019970003195A patent/KR100465270B1/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| EP0787752A2 (en) | 1997-08-06 |
| JPH09216930A (en) | 1997-08-19 |
| ES2196200T3 (en) | 2003-12-16 |
| MX9700823A (en) | 1997-08-30 |
| ATE236942T1 (en) | 2003-04-15 |
| CA2196148A1 (en) | 1997-08-03 |
| EP0787752B1 (en) | 2003-04-09 |
| DE59709731D1 (en) | 2003-05-15 |
| KR100465270B1 (en) | 2005-09-26 |
| KR970061929A (en) | 1997-09-12 |
| DE19603736A1 (en) | 1997-08-07 |
| BR9700840A (en) | 1998-09-01 |
| EP0787752A3 (en) | 1998-05-13 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |