CA2015040A1 - Two-component compositions and coatings and sealants produced therefrom - Google Patents

Abstract

TWO-COMPONENT COMPOSITIONS AND
COATINGS AND SEALANTS PRODUCED THEREFROM
ABSTRACT OF THE DISCLOSURE
The present invention relates to two-component coating or sealing compositions which contain a) a polyisocyanate component and b) a reactive component consisting of at least one compound containing at least two isocyanate reactive groups which are optionally reversibly blocked in quantities corresponding to an equivalent ratio of isocyanate groups to free and blocked isocyanate reactive groups of about 0.8:1 to 10:1 characterized in that polyisocyanate component a) is based on compounds corresponding to the formula A-[O-CO-B-NCO]n wherein n is an integer of 2 or greater, A is an n-valent organic group obtained by removing the hydroxyl groups from an n-valent organic polyhydroxyl compound having a molecular weight of 400 to about 20,000, such compound being inert to isocyanate groups at room temperature with the exception of its hydroxyl groups and B is an aliphatic, cycloaliphatic or aromatic hydrocarbon group optionally having substituents which are inert to the reactive groups present in the compositions.
The present invention also relates to coatings or sealants prepared from these two-component compositions.

Description

2~a~

Mo3351 LeA 26,872 TWO-COMPONENT COMPOSITIONS AND
COATINGS AND SEALANT~ PRODUCED THEREFROM
BACKGROUND OF THE_IYY~YlI9 Field of the Invention The present invention relates to novel compositions and coatings and sealants produced therefrom. These compositions can be used with little or no solvent and are based on special prepolymers cnntaining isocyanate groups and compounds containing isocyanate reactive groups or groups convertible o into such groups.
Descrietion of the Prior Art Coating compositions based on isocyanate prepolymers and compounds containing isocyanate reactive groups or groups conYertible into such groups are known. Thus DE-OS 1 520 139, for example, describes a process for the preparation of moisture hardening mixtures of palyisocyanates and polyketimines or polyaldimines in which the polyisocyanates used are preferably isocyanate prepolymers; DE-AS 1 240 654 describes a process for the preparation of cross-linked resins from ~socyanate prepolymers and special aromatic diamines; and DE-OS 2 018 233 describes moisture hardening preparations of compounds containing isocyanate groups and polyoxazolidines.
Common to all of these publications is the use of known isocyanate prepolymers which are prepared by the reaction of relatively high molecular weight polyhydroxyl compounds such as polyether or polyester polyols with excess quantities of di- or polyisocyanates. The reaction products generally contain relatively high proportions of monomeric di- or polyisocyanates which in many cases must be removed for purposes of industrial hygiene, e.g., by thin layer distillation.
The monomer-free isocyanate prepolymers thus obtained always have much higher viscosities than the starting compounds and therefore in many cases require the addition of organic 353761~R0706 : -: :: : : :: ~ :-: ~ , .. ,: . ~ . . . ..
: - .: ` - : : :

: . :............. : :, . ~ -: .'. ~ ' ' ',: ~ , .

201~

solvents or plasticizers before they can be used for the preparation of lacquers or coating materials.
It is well known, however, that the use of solvents is undesirable for ecological reasons and often regulations 5 require the coating compositions to have the lowest possible solvent content. The use of plasticizers also has disadvantages. Plasticizers remain in the coatings and, thus, impair the mechanical properties of the polymers and their adherence to the substrate and over time migrate from the coatings.
It is therefore an object of the present invention to provide new two-component compositions based on isocyanate prepolymers and compounds containing isocyanate reactive groups or groups convertible into such groups which have substantially 15 lower viscosities than comparable ~nown compositions so that they can be applied with less solvent or without solvent or plasticizer.
This obiect may be achieved in accordance with the present invention by using compositions wherein the polyisocyanate component is based on certain isocyanate prepolymers containing ester groups.
Isocyanate prepolymers which are similar to the isocyanate prepolymers used as the polyisocyanate component according to the present have been described in DE-OS 2 120 090; however, 25 the isocyanate prepolymers disclosed in this prior publication are used for finishing textiles containing keratin fibers and must be used in the form of highly diluted organic solutions or aqueous emulsions. There is no indication in this prior publication that the isocyanate prepolymers are particularly 30 suitable for the preparation of low solvent or solvent-free coating compositions. In particular, there is absolutely no indication to prepare isocyanate prepolymers, which are particularly suitable for the present invention, by the process described hereinafter.

Mo3351 . . ~ . ~ . . .
. .
- , . . .

2015~4~

SUMMARY OF THE INVENTIO~
The present invention relates to two-component coating or sealing compositions which contain a~ a polyisocyanate component and b) a reactive component consisting of at least one compound containing at least two isocyanate reactive groups which are ~ptionally reversibly blocked in quantities corresponding to an equivalent ratio of isocyanate groups to free and blocked isocyanate reactive : lo groups of about 0.8:1 to 10:1 characterized in that polyisocyanate component a~ is based on compounds corresponding to the formula A- [O-CO-B-NCO~n wherein n is an integer of 2 or greater, A is an n-valent organic group obtained by removing the hydroxyl groups from an n-valent organic polyhydroxyl compound having a molecular weight of 400 to about 20,000, such compound being inert to isocyanate groups at room temperature with the exception of its hydroxyl groups and B is an aliphatic, cycloaliphatic or aromatic hydrocarbon group optionally having substituents which are inert to the reactive groups present in the compositions.
The present invention also relates to coatings or sealants prepared from these two-component compositions.
DETAILED DESCRTPTION OF THE INVENTION
Polyisocyanate component a) consists substantially of compounds corresponding to the formula A-[O-CO-B-Nco]n wherein Mo335 1 . . . ~ , . , ;. .. .
.. ; ~., . . . . . . . ~ , :., , , .,. :
:, . . . . .: ~ - ~

. .
.. . . .

2013B~O

n, A and B have the meanings already ;ndicated. It is preferred to use those isocyanate prepolymers corresponding to the above mentioned fonmula wherein n stands for an integer having a value of 2 to 8, more preferably 2 to 4, A denotes an n-valent group obtained by removing the hydroxyl groups from a polyhydroxyl compound having a molecular weight of about sno to 5000 and containing ether, ester, carbonate and/or urethane groups and B denotes an aliphatic hydrocarbon group containing 2 to 10 carbon atoms, preferably 4 to 8 carbon atoms, or a cycloaliphatic hydrocarbon group containing 6 carbon atoms, provided that at least two carbon atoms are situated between the carbonyl group and ~he isocyanate group.
The isocyanate prepolymers corresponding to the above formula are prepared by modifying organic polyhydroxyl compounds corresponding to the formula A(OH)n This modification may involve reacting the polyhydric alcohols with isocyanatocarboxylic acid chlorides corresponding to the formula Cl-CO-B-NCo in accordance with the teachings of DE-OS 2 120 090.
Conversion of the above-mentioned polyvalent polyhydroxyl compounds into the isocyanate prepolymers used as component a) according to the invention is preferably carried out by a process analogous to that described in DE-OS 3 634 248.
In this process, the polyhydroxyl compounds are converted into corresponding O-silylated compounds corresponding to the formula Mo3351 :,.:. - ~ .,: ., : - -, 2 ~

A-[0-SiR3]n in a first reaction stage which is analogous to the process described by M. Lalonde and C.H. Chan in "Synthesis" 1985, pages 817 to 845. The polyhydroxyl compounds are reacted with, 5 for example, chlorosilanes or disilazanes corresponding to the formulas R35iCl or R3Si-NH-SiR3, optionally in the presence of an auxiliary solvent. The reaction with chlorosilane is generally carried out at a molar ratio of hydroxyl groups to chlorosilane of 1:1 to 1:2 and at temperatures of about 0 to ~0C. The reaction generally requires the addition of at least an equimolar quantity of an 15 organic base such as pyridine or triethylamine for binding the hydrogen chloride formed in the reaction. The reaction with disilazanes is preferably carried out at a molar ratio of hydroxyl groups to disilazane of 1:0.5 to 1:1 at temperatures of about 60 to 140C until ammonia ceases to be split off. It 20 iS frequently advisable to add a small quantity of an acid catalyst such as p-toluene sulfonic acid or trimethyl chlorosilane.
The solvents optionally used for this reaction include n-hexane, cyclohexane, toluene, xylene, methoxypropylacetate, 25 ethyl acetate, butyl acetate, methyl ethyl ketone or mixtures of such solvents. Chlorosilanes and disilazanes which are particularly suitable for the reaction are those correspond;ng to the above formulae wherein R is an alkyl group with 1 to 4 carbon atoms or a phenyl group, preferably a methyl group.
The 0-silylated polyhydroxyl compounds are then reacted with isocyanatocarboxylic acid chlorides corresponding to the above formula. The components for this reaction are used in quantities which provide about 0.~ to 1.2 moles of silylated hydroxyl groups for each mole of chlorocarbonyl groups.
Mo3351 ... ..
.

~: .

2 0 ~

Equimolar ratios of reactants are preferably maintained. The reaction of the silylated hydroxyl compounds with isocyanatocarboxylic acid chlorides is generally carried out at temperatures of about 50 to 150C, optionally with the addition of catalysts commonly used for this reaction, such as quinoline or pyridine.
A trialkyl or triaryl chlorosilane is formed as by-product of the reaction according to the invention and can easily be removed from the reaction mixture by distillation.
This reaction may also be carried out either in the presence or the absence of a solvent of the type exemplified above. Solvents may generally be omitted if the silylated ; hydroxyl compounds have a sufficiently low viscosity for carrying out the process according to the invention.
: 15 Because it is an object of the present invention to provide binders with as low a solvent content as possible, the use of solvents is less preferred; however, residues of volatile components may be removed from the prepolymers by thin layer distillation.
The polyhydroxyl compound used for the preparation of polyisocyanate component a) may be any organic polyhydroxyl compound which has a molecular weight range of 400 to about 20,000, which is at least divalent and which, apart from its hydroxyl groups, is inert to isocyanate groups at room temperature such that the isocyanate prepolymers are stable in storage at room temperature. These polyhydroxyl compounds, A(OH~, preferably have a molecular weight of about 800 to 5000 and contain ether, ester, carbonate and/or urethane groups. The molecular weights may be determined, for example, by gel permeation chromatography (MW > 5000) or from the hydroxyl group content and OH fùnctionality (MW ~ 5000).
The isocyanate prepolymers a) may be prepared, for example, from known relatively high molecular weight polyols of the type used as raw materials in polyurethane chemistry.
Examples of such compounds are given in High Polymers, Vol.XVI, Mo3351 ' ' :: ' ' , '. ` . ~ ' ' . ' "' ~ ' ' ' ' , ;' ' ' . ' ~ . ., '~

2 ~

"Polyurethanes, Chemistry and Technology", by Saunders-Frisch, Interscience Publishers, New York, London, Volume I, 1962, pages 32-42 and pages 44-54 and Volume II, 1964, pages 5-6 and 198-199; and in Kunststoff-Handbuch, Volume VII, 5 Vieweg-Hochtlen, Carl-Hanser-Verlag, Munich, 1966, e.g. on pages 45-71.
Polyhydroxyl compounds containing two or more different groups of the type mentioned above and mixtures of different polyhydroxyl compounds of the type mentioned above are also o suitable. Suitable polyether polyols for use in accordance with the invention may be prepared, for example, by the polymerization of epoxides (such as ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, styrene oxide or epichlorohydrinJ on their own (e.g. in the presence of Lewis 5 catalysts such as BF3) or by chemical addition of these epoxid~s, preferably ethylene oxide and propylene oxide, optionally as mixtures or successively, to starter compounds containing reactive hydrogen atoms (such as water, alcohols, ammonia or amines). Examples of suitable starter compounds 20 include ethylene glycol, propylene glycol-(1,3~ or -(1,2), trimethylolpropane, glycerol, sorbitol, 4,4'-dihydroxy-diphenylpropane, aniline, ethanolamine and ethylene diamine. Sucrose polyethers such as those described, for example, in German Auslegeschriften 1 176 358 and 1 063 938 25 and polyethers started on formitol or formose (German Offenlegungsschriften 2 639 083 and 2 737 951) may also be used.
The polyester polyols which may be used according to the invention are also known and are based on reaction products of 30 polyhydric, preferably dihydric alcohols, optionally with the addition of trihydric alcohols, with polybasic, preferably dibasic carboxylic acids. Instead of the free polycarboxylic acids, the corresponding polycarboxylic acid anhydrides or corresponding polycarboxylic acid esters of lower alcohols or 35 mixtures thereof may be used for preparing the polyesters. The Mo3351 , . , ~ . - . ~
c.
. ~ . , ~ . .
- . . , ~ , -.

2 ~ ~ 3 polycarboxylic acids may be alipha~ic, cycloal iphatic, aro~atic and/or heterocyclic and may be unsaturated and/or substituted, e.g. by halogen atoms.
Examples of suitable carboxylic acids and their ;~ 5 derivatives include succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid~ isophthalic acid, trimellitic acid, phthalic acid anhydride, tetrahydrophthalic acid anhydride, hexahydrophthalic acid anhydride, tetrachlorophthalic acid anhydride, endomethylene tetrahydrophthalic acid anhydride, glutaric acid anhydride, maleic acid, maleic acid anhydride, fumaric acid, dimerized and trimerized unsa~urated fatty acids (optionally mixed with monomeric unsaturated fatty acids such as oleic acid), terephthalic acid dimethylester and terephthalic acid bis-glycol ester. Examples of suitable polyhydric alcohols include ethylene glycol, propylene glycol-(1,2~ and -(1,3), butylene glycol-(1,4) and -(2,3), hexanediol-(1,6), octanediol-~1,8), neopentyl glycol, 1,4-bis-hydroxymethyl-cyclohexane, 2-methyl-1,3-propanediol, glycerol, trimethylolpropane, hexanetriol-(1,2,6~ butanetriol-(1,2,4) trimethylolethane, pentaerythritol, quinitol, mannitol and sorbitol, formitol, methyl glycoside, diethylene glycol, triethylene glycol and tetraethylene glycol and higher MW
polyethylene glycols, dipropylene glycol and higher MW
polypropylene glycols and dibutylene glycol and higher MW
polybutylene glycols.
Polyesters of lactones such as ~-caprolactone or hydroxycarboxylic acids such as ~-hydroxycaproic acid may also be used.
Suitable hydroxyl polycarbonates are known and include ;-~
those obtained by the reaction of diols such as -~
propanediol-(1,3), butanediol-(1,4) and/or hexanediol-(1,6) diethylene glycol, triethylene glycol, tetraethylene glycol or ~ -thiodiglycol with phosgene or diarylcarbonates such as diphenylcarbonate (German Auslegeschriften Nos. l 694 080, 1 Mo3351 ; .. ~ - - . . .. . - .. . . . . . .

~ - .
... . ~ , - -- - .
; .. ~ .. . ~ . . . . - , .. . . . . .

, ;.: . . . . : . . , . :
: . . -; .. .. , -, , .

~ . ~ :-, . :
,.. . . .. . ..

2 ~ 0 915 gO8 and 2 221 751; German Offenlegungsschrift No.
2 6~5 0243.
Polyester polycar~onates containing hydroxyl groups which may be obtained, for example, according to DE-AS 1 770 245 are also suitable. These compounds may be prepared, e.g., by reacting ~-caprolactone with polyols such as hexane-1,6-diol followed by a reacting the resulting ester glycols with diphenylcarbonate.
Suitable polyurethane polyols for use in accordance with n the present invention are prepared by the polyaddition of one or more of the previously mentioned relatively high molecular weight polyhydroxyl compounds, optionally in admixture with low molecular weight polyols such as ethylene glycol, propylene glycol-(1,2) and -(1,3), butylene glycol-(1,4~ and -(2,3), hexanediol-(1,6), octanediol-(1,83, neopentyl glycol, 1,4-bis-hydroxymethylcyclohexane, 2-methyl-1,3-propanediol, glycerol, trimethylolpropane, diethylene glycol, dipropylene glycol or higher MW polyalkylene glycols w;th polyisocyanates such as 2,4- and/or 2,6-toluylene diisocyanate, diphenyl-methane-2,4'- and/or -4,4'-diisocyanate, 1,6-hexamethylene-diisocyanate, cyclohexane-1,3- andtor -1,4-diisocyanate, l-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane (isophorone diisocyanate), 4,4'-dicyclohexylmethane diisocyanate and/or adducts of the above mentioned polyisocyanates containing biuret or isocyanurate groups. The polyhydroxyl compounds and pGlyisocyanates are used in quantitative proportions such that the hydroxyl groups are present in stoichiometric excess to the isocyanate groups.
Suitable isocyanatocarboxylic acid chlorides corresponding to the above formula which are suitable for the preparation of the isocyanate prepolymers a) include 3-isocyanatopropionic acid chloride, 4-isocyanatobutyric acid chloride, 6-isocyanatocaproic acid chloride, 11-isocyanatoundecanoic acid chloride and 4-isocyanatocyclohexane carboxylic acid chloride.

Mo3351 :; , ,, , . ::

.: . : ,: , .: . :
.

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~ , ~

2 ~

In addition to these preferred isocyanatocarboxylic acid chlorides, it is also possible to use isocyanato carboxylic acid chlorides which correspond to the above formula wherein B is an aromatic hydrocarbon group optionally 5 containin~ inert substituents. 4-isocyanatobenzoic acid chloride is given as an example of these compounds.
The isocyanate prepolymers used as component a) according to the invention are distinguished by their low monomer content and exceptionally low viscosities.
Reactive component b~ is based on at least one compound containing at least two isocyanate reactive groups or at least two groups capable of being converted, preferably hydrolytically, into such groups. Compounds containing both free and reversibly blocked isocyanate reactive groups may also 15 be used but are less preferred. Also, mixtures of compounds having free isocyanate reactive groups and compounds having reversibly blocked isocyanate reactive groups may also be used but are less preferred. The compounds used as component b) preferably contain 2 to 4 free or blocked isocyanate reactive 20 groups per molecule. The molecular weight of the compounds used as component b) is not critical but comparatively low molecular weight compounds, i.e., compounds haviny a molecular weight of not more than 600, are preferably used.
The quantity of the components used in the coating compositions according to the present invention is chosen to provide a ratio of (i) isocyanate groups of component a) to (ii) free and/or reversibly blocked isocyanate reactive groups of component b) of about 0.8:1 to 10:1, preferably about 0.9:1 to 4:1, more preferably 1:1 to 2:1 and most preferably 1:1 to 1.2:1.
The following may be used as as all or a portion of component b):
- Polyoxazolidines which are known from polyurethane chemistry and described, e.g., in DE-PS 2 018 233 (US-PS 3 Mo3351 ! ~ .

- : , ' ,: ':
, . i `, ~ " , , ' '~ ' .
'' , ~ : : .

2 0 ~

743 626, herein incorporated by reference) and DE-OS 2 446 438 (US-PS 4 002 601, herein incorporated by reference);
- polyketimines or polyaldi~ines which are known from polyurethane chemistry and described, e.g., in DE-OS l 520 139, (US-PS 3 420 800 and US-PS 3 ~67 692, both of which are herein incorporated by reference) or DE-OS 3 308 418 (US-PS 4 481 345, herein incorporated by reference);
- aromatic polyamines, in particular diamines containing sterically hindered amino groups, e.g., those used as chain lengthening agents according to US-PS 4 218 543, herein incorporated by reference, preferably l-methyl-3,5-diethyl-2,4-diaminobenzene a~d mixtures thereof with l-methyl-3,5-diethyl-2,6-diaminobenzene; and - polyhydric alcohols having a molecular weight of 62 to 39g as well as polyhydric alcohols having a molecular weight of at least 400. Examples of low molecular polyhydric alcohols include ethylene glycol, propylene glycol, butane-1,4-diol, glycerol, trimethylolpropane, pentaerythritol, diethylene glycol, dipropylene glycol and 2~ mixtures of such polyols. Examples of suitable higher molecular weight alcohols include the starting materials A(OH)n mentioned above as examples for the preparation of polyisocyanate component a). Other polyhydroxyl compounds which are suitable include epoxide resins, phenol resins, alkyl resins, castor oil, polyester resins containing hydroxyl groups and silicone resins containing hydroxyl groups.
For the preparation of the two-component compositions according to the invention, the individual components a) and b) are mixed together. When component b) contains reversibly blocked isocyanate reactive groups, in particular reversibly blocked amino groups, storage stable preparations are obtained which remain stable in the absence of moisture and rapidly harden in the presence of moisture after they have been applied to a suitable substrate. The hardening reaction may also be Mo3351 ,. . ., . ~ . ,, ., , , . :, .: . .

? : -- . : ~ ` . . . . . .

, ,; , .- . . . .
, . ~ ,: - ~ . ... . . .

~V~ 4~

accelerated by the addition of known catalysts such as p-toluenesulphonic acid, dibutyl tin octoate or zinc chloride.
When the reactive components b3 contain free isocyanate reactive groups, in particular amino or hydroxyl groups, the reaction mixtures obtained will react at room temperature to form polyurethanes or polyureas, i.e. they have only a limited pot life and must be worked up within this period.
The term "two-component compositions" means that the o compositions according to the invention are composed of the individual components a) and b) and when blocked reactive components b) are used then the individual components may also be combined to form a one-component system.
Inert organic solvents or plasticizers may be added to the individual components or to the combinations according to the invention before, during or after the compositions have been prepared by mixing of the individual components a) and b).
These solvents or plasticizers should be substantially free from water to ensure sufficient storage stability of the binders, especially when polyoxazolidines, polyketimines or polyaldimines are used as component b). The use of solvents or plasticizers is however, not preferred in view of the object of the invention to produce binders which have as low a solvent content as possible.
The addition of pigments and other auxiliary agents and additives required for most applications such as fillers, levelling agents, etc. is preferably carried out by adding the additives to one of the starting components before the preparation of the compositions according to the invention.
The compositions according to the invention are particularly suitable for the preparation of coatings and sealants. The coating compositions according to the invention may be applied as one or more layers to any substrates by known methods such as spraying, spread coating, immersion, flooding 35 or application with rollers or knife coaters. Suitable Mo3351 .

: . . . .

,~

. . :, . ~ ~

2 ~

-~3-substrates include metal, wood, glass, stone, ceramic materials, concrete~ hard and flexible plastic textiles, leather and paper.
The substrates may, of course, be coated with the known primers before application of the coating compositions according to the invention.
The following examples serve to illustrate the invention in more detail. Percentages are percentages by weight and parts are parts by weight unless otherwise indicated.
o EXAMPLES
General method of preparation of O-silylated polyhydroxyl compounds ~_ The O-silylated polyhydroxyl compounds used for the preparation of isocyanate prepolymers I to III were prepared from the corresponding polyhydroxyl compounds by reacting them with hexamethyldisilazane:
1 OH equivalent of the hydroxyl compound and 0.8 moles of hexamethyldisilazane were stirred together at 100 to 120C with the addition of 0.5 g of trimethylchlorosilane until evolution of NH3 ceases. The progress of the reaction was followed by observation of the OH band by IR spectroscopy. After the reaction, excess disilazane was removed from the reaction mixture by distillation.
Isocvanate prepolvmer I
1073 g of an O-silylated polyether ~based on trimethylolpropane and propylene oxide, OH number = 56, viscosity at 22C = 500 mPas) and prepared by the above method and 175.5 9 of 6-isocyanatocaproic acid chloride were stirred together at 80 to 100C with the addition of 1 ml of pyridine until the IR spectrum showed no acid chloride band.
Trimethylchlorosilane produced during the reaction was continuously removed by distillation. An isocyanate prepolymer having the followin~ characteristics was obtained after thin layer distillation at 140C/0.05 mbar:
NCO content = 3.45%;
Mo3351 : : ~ , ........ . . .

, , - , . . .
.: . : . , , - , , ;.

. , - -2 0 ~ ~ ~ 4 ~

viscosity at 22C = 600 mPas.
IsocYanate DrepolYmer II
1073 9 of an O-silylated polyester carbonate diol [based on a polyester carbonate diol prepared according to DE-AS 1 770 245 (U.S. Patent 3,640,967) from hexane-1,6-diol, ~-caprolactone and diphenylcarbonate in a molar ratio of about 8:8:7, OH number = 56, viscosity at 22nC = 20,000 mPas]
prepared by the above-described method and 175.5 g of 6-isocyanatocaproic acid chloride were reacted as described above for the preparation of isocyanate prepolymer I. After removal of residues of volatile constituents by thin layer distillation, the isocyanate prepolymer obtained had the following characteristics:
NCO content = 3.2%, viscosity at 22C = 20,000 mPas.
Isocvanate prepolYmer III
1673 g of an O-silylated polyether triol (based on a polyether triol prepared by the propoxylation of trimethylolpropane followed by ethoxylation of the propoxylation product at a PO:EO ratio by weight of 86.5:13.5, OH number = 35, viscosity at 22C = 500 mPas) prepared by the method described above and 175.5 g of 6-isocyanatocaproic acid chloride were reacted as described above for the preparation of isocyanate prepolymer I. The isocyanate prepolymer obtained had the following characteristics after thin layer distillation at 140C/0.05 mbar:
NCO content = 2.46%, viscosity at 22C = 600 mPas.
IsocYanate Dre wlvmer IV
A mixture of 1000 9 of the polyester carbonate diol used for the preparation of isocyanate prepolymer II, 500 ml of ethyl acetate and 102 g of triethylamine was added dropwise to a solution of 175.5 g of isocyanatocaproic acid chloride in 300 ml of ethyl acetate at room temperature at such a rate that the temperature did not rise above 30 C. The reaction mixture was Mo3351 ~ . . , . . . ~ ..
.. . . ..................... :.,: ;, .
., - . - , . . . . .

20~5~

stirred overnight and filtered from the precipitated ammonium salt. The filtrate was freed from volatile constituents by thin layer evaporation. The isocyanate prepolymer obtained had the following character;stics:
: 5 NC0 content = 3.16%
viscosity at 22C = 80,000 mPas.
Example_l 88 parts of isocyanate prepolymer I were mixed with 12 parts of a bisoxazolidine prepared from 2 moles of 2-(2-isopropyl-1,3-oxazolidin-3-yl)ethanol and 1 mole of hexamethylene diisocyanate. The mixture was completely stable in a closed container. The solvent-free mixture thus prepared had a viscosity of 800 mPas (22C). When the compound was applied in a thickness 8 mm, it hardened in air at room temperature to an elastic coating.
Example 7 93 parts of isocyanate prepolymer I were thoroughly mixed with 7 parts of 1-methyl-3,5-diethyl-phenylenediamine-(2,4).
The mixture obtained had a pot life of 15 minutes. A film of lacquer applied at room temperature was pressure dry after about 40 minutes. After aging, the film had a Shore A hardness of 66.
Example 3 89 parts of isocyanate prepolymer II were intimately mixed 25 with 11 parts of the bisoxazolidine described in Example 1. A
solvent-free mixture which was completely stable in closed containers and had a viscosity of 17,000 mPas (22C) was obtained. The mixture hardened in air at room temperature to form tough elastic films which had excellent abrasion 30 resistance.
Example 4 187 parts of isocyanate prepolymer II were vigorously mixed with 13 parts of 1-methyl-3,5-diethyl-phenylenediamine-(2,4). The solvent-free mixture had an initial viscosity of 35 20,000 mPas (22C) and a pot life of 15 minutes. A film Mo3351 .. .. , . ~ . .
. , ... , , . . . ~ . .

,: , , ~ - . . . .
:............. .. . - . : : :
. : ~ , - .. ` : -: . - . , . .
. - . ~ .

2 ~

applied at room temperature was pressure dry after about 40 minutes. A tough elastic film with good abrasion resistance was obtained after aging.
ExamPle 5 95 parts of isocyanate prepolymer III were intimately mixed with S parts of 1-methyl-3,5-diethyl-phenylenediamine-(2,4). The solvent-free mixture had an initial viscosity of 650 mPas (22C) and a pot life of 20 minutes. A lacquer film applied at room temperature was pressure dry after about 90 minutes. A highly elastic film was obtained after aging.
Example 6 ~1 parts of isocyanate prepolymer II were mixed with 9 parts of a bisketimine prepared by the condensation of isophorone diamine with methyl isobutyl ketone. A storage stable mixture having a viscosity of 18,000 mPas (2~C) was obtained. A film applied at room temperature had good abrasion resistance.
Example 7 195 parts of isocyanate prepolymer II were mixed with 5 parts of glycerol. The mixture had an initial viscosity of 20,000 mPas (22C). A sample was heated to 100C for 70 minutes to accelerate hardening. A tough elastic polymer with good mechanical properties was obtained.
Example 8 94 parts of isocyanate prepolymer IV were mixed with 6 parts of 1-methyl-3,5-diethyl-phenylenediamine-(2,~). The solvent-free mixture had an initial viscosity of 80,000 mPas (22C) and a pot life of 20 minutes. A film applied at room temperature was pressure dry after about 60 minutes. A tough 3a elastic film with good abrasion resistance was obtained after aging.
Example 9 (Comparison) 1000 g of the polyester carbonate diol used for the preparation of isocyanate prepolymer II and 222 g of isophorone diisocyanate were prepolymerized to a constant isocyanate Mo3351 - ~ . . . . . .
, . ~ . ..
. . . . -. . .
. .

~, . . .

20~

content at 100C. The prepolymer obtained had the following characteristics:
NC0 content = 3.35%
viscosity a~ 22~C = 400,000 mPas 5 monomer content = 2.5%.
The prepolymer had to be diluted to a solids content of 80% with butyl acetate to enable it to be applied.
NC0 content = 2.68%
viscosity at 22~ = 12,000 mPas.
1~9 Parts of the solvent-containing prepolymer were mixed with 11 parts of l-methyl-3,5-diethyl-phenylenediamine-(2,4)0 The mixture had an initial viscosity of 13,000 mPas (22C) and a pot life of 15 minutes. A film applied at room temperature was pressure dry after about 60 minutes.
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 2Q except as it may be limited by the claims.

Mo3351 - . : . . .
. ~ -;, , - : . : .

~: ., : ; . :: : , .. .
: . ~ . ., - . ,.: .

: ............ , - .
;: , , :. : . . : -

Claims (20)

1. A two-component coating or sealing composition which comprises a) a polyisocyanate component comprising a compound corresponding to the formula:

A-[O-CO-B-NCO]n wherein n is an integer of 2 or greater, A is an n-valent organic group obtained by removing the hydroxyl groups from an n-valent organic polyhydroxyl compound having a molecular weight of 400 to about 20,000, said compound being inert to isocyanate groups at room temperature with the exception of its hydroxyl groups and B is an aliphatic, cycloaliphatic or aromatic hydrocarbon group optionally having substituents which are inert to the reactive groups present in said composition and b) a reactive component comprising at least one compound containing at least two isocyanate reactive groups which may optionally be reversibly blocked, in quantities corresponding to an equivalent ratio of isocyanate groups to free and blocked isocyanate reactive groups of about 0.8:1 to 10:1.

2. The composition of Claim 1 wherein n is an integer from 2 to 8, A is an n-valent group obtained by removing the hydroxyl groups from an n-valent polyhydroxyl compound having a molecular weight of about 800 to 5000 and containing ether, ester, carbonate and/or urethane groups and B is an aliphatic hydrocarbon group having 2 to 10 carbon atoms or a cycloaliphatic hydrocarbon group having 6 carbon atoms.

3. The composition of Claim 1 wherein polyisocyanate component a) comprises the reaction product of an O-silylated polyhydric alcohol corresponding to the formula:
A-[O-SiR3]n with an isocyanatocarboxylic acid chloride corresponding to the formula:

wherein R is an alkyl group having 1 to 4 carbon atoms or a phenyl group.

4. The composition of Claim 3 wherein n is an integer from 2 to 8, A is an n-valent group obtained by removing the hydroxyl groups from an n-valent polyhydroxyl compound having a molecular weight of about 800 to 5000 and containing ether, ester, carbonate and/or urethane groups and B is an aliphatic hydrocarbon group having 2 to 10 carbon atoms or a cycloaliphatic hydrocarbon group having 6 carbon atoms.

5. The composition of Claim 1 wherein component b) comprises a polyamine containing reversibly blocked amino groups and selected from the group consisting of polyoxazolidines, polyketimines, polyaldimines and mixtures of these compounds.

6. The composition of Claim 2 wherein component b) comprises a polyamine containing reversibly blocked amino groups and selected from the group consisting of polyoxazolidines, polyketimines, polyaldimines and mixtures of these compounds.

7. The composition of Claim 3 wherein component b) comprises a polyamine containing reversibly blocked amino groups and selected from the group consisting of polyoxazolidines, polyketimines, polyaldimines and mixtures of these compounds.

8. The composition of Claim 4 wherein component b) comprises a polyamine containing reversibly blocked amino groups and selected from the group consisting of polyoxazolidines, polyketimines, polyaldimines and mixtures of these compounds.

9. The composition of Claim 1 wherein component b) comprises a compound containing isocyanate reactive groups and selected from the group consisting of aromatic polyamines, polyhydric alcohols and mixtures of these compounds.

10. The composition of Claim 2 wherein component b) comprises a compound containing isocyanate reactive groups and selected from the group consisting of aromatic polyamines, polyhydric alcohols and mixtures of these compounds.

11. The composition of Claim 3 wherein component b) comprises a compound containing isocyanate reactive groups and selected from the group consisting of aromatic polyamines, polyhydric alcohols and mixtures of these compounds.

12. The composition of Claim 4 wherein component b) comprises a compound containing isocyanate reactive groups and selected from the group consisting of aromatic polyamines, polyhydric alcohols and mixtures of these compounds.

13. A coating or sealant which is prepared from a two-component composition which comprises a) a polyisocyanate component comprising a compound corresponding to the formula:
A-[O-CO-B-NCO]n wherein n is an integer of 2 or greater, A is an n-valent organic group obtained by removing the hydroxyl groups from an n-valent organic polyhydroxyl compound having a molecular weight of 400 to about 20,000, said compound being inert to isocyanate groups at room temperature with the exception of its hydroxyl groups and B is an aliphatic, cycloaliphatic or aromatic hydrocarbon group optionally having substituents which are inert to the reactive groups present in said composition and b) a reactive component comprising at least one compound containing at least two isocyanate reactive groups which may optionally be reversibly blocked, in quantities corresponding to an equivalent ratio of isocyanate groups to free and blocked isocyanate reactive groups of about 0.8:1 to 10:1.

14. The coating or sealant of Claim 13 wherein n is an integer from 2 to 8, A is an n-valent group obtained by removing the hydroxyl groups from an n-valent polyhydroxyl compound having a molecular weight of about 800 to 5000 and containing ether, ester, carbonate and/or urethane groups and B is an aliphatic hydrocarbon group having 2 to 10 carbon atoms or a cycloaliphatic hydrocarbon group having 6 carbon atoms.

15. The coating or sealant of Claim 13 wherein polyisocyanate component a) comprises the reaction product of an O-silylated polyhydric alcohol corresponding to the formula:
A-[O-SiR3]n with an isocyanatocarboxylic acid chloride corresponding to the formula:
Cl-CO-B-NCO

wherein R is an alkyl group having 1 to 4 carbon atoms or a phenyl group.

16. The coating or sealant of Claim 14 wherein n is an integer from 2 to 8, A is an n-valent group obtained by removing the hydroxyl groups from an n-valent polyhydroxyl compound having a molecular weight of about 800 to 5000 and containing ether, ester, carbonate and/or urethane groups and B is an aliphatic hydrocarbon group having 2 to 10 carbon atoms or a cycloaliphatic hydrocarbon group having 6 carbon atoms.

17. The coating or sealant of Claim 13 wherein component b) comprises a polyamine containing reversibly blocked amino groups and selected from the group consisting of polyoxazolidines, polyketimines, polyaldimines and mixtures of these compounds.

18. The coating or sealant of Claim 16 wherein component b) comprises a polyamine containing reversibly blocked amino groups and selected from the group consisting of polyoxazolidines, polyketimines, polyaldimines and mixtures of these compounds.

19. The coating or sealant of Claim 13 wherein component b) comprises a compound containing isocyanate reactive groups and selected from the group consisting of aromatic polyamines, polyhydric alcohols and mixtures of these compounds.

20. The coating or sealant of Claim 16 wherein component b) comprises a compound containing isocyanate reactive groups and selected from the group consisting of aromatic polyamines, polyhydric alcohols and mixtures of these compounds.