Abstract: To provide the micromixing method for liquefied matter containing plural types of substance which can be also applicable to promote chemical reaction among the plural types of substance with the micromixing when the plural types of substance are reactive each other.

Abstract: A low-viscosity polyisocyanate of reduced color, containing isocyanurate groups is prepared by partially trimerizing an aliphatic and/or cycloaliphatic diisocyanate in the presence of 0.02 to 2% by weight, based on the weight of the diisocyanate starting material, of at least one trimerization catalyst containing a quarternary amine component and then removing excess diisocyanate from the reaction medium.

Abstract: A polyisocyanate curing agent for laminate adhesive, comprising: (A) an isocyanate group-terminated prepolymer having isocyanurate group and urethane group, obtained by reacting an organic polyisocyanate containing at least (a1) an aromatic diisocyanate with an active hydrogen group-containing compound containing at least (a2) a diol compound having a number-average molecular weight of 100 to 2,000, and, as an optional component, (B) an isocyanate group-terminated prepolymer having urethane group, and, also as an optional component, (C) a silane coupling agent represented by the following general formula (1): OCN—(CH2)m—Si(OR)3  (1)  (wherein R is a methyl group or an ethyl group, and m is an integer of 1 to 5); and a process for producing the polyisocyanate curing agent. The polyisocyanate curing agent is usable in a laminate adhesive which can be aged in a short time without shortening the pot life, which has good adhesivity, and which can withstand a severe retort treatment.

Abstract: This invention relates to storage-stable, liquid, partially trimerized polyisocyanates having an NCO group content of 24 to 40% by weight, and comprising 20 to 88% by weight of toluene diisocyanate and 12 to 80% by weight of a polyisocyanate of the diphenylmethane series. The present invention also relates to a process for the preparation of the storage-stable, liquid, partially trimerized polyisocyanates; to storage-stable, liquid urethane prepolymers of these partially trimerized polyisocyanates; and to a process for the production of these storage-stable, liquid, urethane prepolymers.

Abstract: The object of the invention is to provide an excellent compound as a drug.

Abstract: The invention provides polyisocyanates containing isocyanate groups from 1,4-diisocyanato-2,2,6-trimethylcyclohexane, having a trimer fraction of more than 80% by weight and an NCO content of at least 19.3%.

Abstract: The present invention provides a process, which includes: partially trimerizing isophorone diisocyanate in the presence of a catalyst having the formula: [R—NX3]⊕Y⊖ wherein R and X are butyl groups and Y− is CH3COO−; or wherein R is a benzyl group, Y− is a carboxylate anion having from 4 to 8 carbon atoms and each X is an alkylene group having from 2 to 3 carbon atoms, wherein the three alkylene groups share a common carbon atom and, together with the N atom in the formula, form a tricyclic structure, and wherein at least one alkyene group has at least one OH group in an &agr; or &bgr; &ggr; position relative to the N atom, to obtain a monomer-containing polyisocyanurate mixture. The present invention also provides a monomer-containing polyisocyanurate mixture made from the above process.

Abstract: Optically active &bgr;-type tris-(2,3-epoxypropyl)-isocyanurate is obtained by a method of reacting isocyanuric acid with an optically active epihalohydrin, or a method of optically resolving a racemic modification of tris-(2,3-epoxypropyl)-isocyanurate by using an amylose or cellulose derivative. It is a method for producing a high melting point type tris-(2,3-epoxypropyl)-isocyanurate obtained by mixing two enantiomers of optically active &bgr;-type tris-(2,3-epoxypropyl)-isocyanurate.

Abstract: The present invention relates to polyisocyanate mixtures prepared from aliphatic and/or cycloaliphatic diisocyanates and having a) an average isocyanate functionality of at least 2.0, b) a content of isocyanate groups (calculated as NCO; molecular weight=42) of 4.0 to 28.0 wt. % and c) a content of alkoxy groups having up to 36 carbon atoms of 2.0 to 37.5 wt. %, wherein the alkoxy groups are constituents of allophanate groups or optionally urethane groups, provided that >50 mol % of the alkoxy groups are a constituent of allophanate groups that are connected to at least two polyisocyanate molecules which are each prepared from at least two diisocyanates. The present invention also relates to a process for preparing these polyisocyanate mixtures and to coating compositions, which are highly diluted or dilutable with non-polar solvents and contain these polyisocyanate mixtures and lacquer binders or binder components optionally containing isocyanate-reactive groups.

Abstract: The present invention provides methods of correlating genetic variants in the beta-chemokine receptor 5 (CCR5) locus, more specifically CCR5 promoter alleles and genotypes, with HIV-1 transmission and/or disease progression in individuals and populations.

Abstract: The present invention provides a process, which includes:

Abstract: The invention provides polyisocyanates containing isocyanate groups from 1,4-diisocyanato-2,2,6-trimethylcyclohexane, having a trimer fraction of more than 80% by weight and an NCO content of at least 19.3%.

Abstract: A monomer useful in the formulation of a radiation curable coatable composition comprises (a) polyfunctional isocyanurate having at least three terminal reactive groups reacted with (b) hydroxyalkyl acrylate and (c) tertiary amine alcohol in a molar ratio of a:b:c of about 1:1-2.5:0.5-2, wherein b+c is at least 3 and no greater than the total number of terminal reactive groups of (a). The monomer is included in a radiation curable coatable composition suitable for use as a floor finish and in a floor finishing system comprising the foregoing coatable composition with a primer. A method for the treatment of a substrate using the floor finish and the floor finishing system is also described.

Abstract: The present invention is directed to cyclic amines of the formula I: ##STR1## (wherein R.sup.1, R.sup.2, R.sup.3, m and n are defined herein) which are useful as modulators of chemokine receptor activity. In particular, these compounds are useful as modulators of the chemokine receptors CCR-1, CCR-2, CCR-2A, CCR-2B, CCR-3, CCR-4, CCR-5, CXCR-3, and/or CXCR-4.

Abstract: This invention relates to a novel trimerization catalyst system, and to a process for trimerizing organic polyisocyanates in the presence of thermally active catalyst systems. These catalyst systems comprise (A) compounds selected from the group consisting of (i) lithium salts of aliphatic or aromatic carboxylic acids, (ii) lithium salts of hydroxyl group containing compounds wherein the hydroxyl groups are directed attached to an aromatic ring, and (iii) lithium hydroxide; (B) an allophanate catalyst; and (C) an organic compound which contains at least one hydroxyl group.

Abstract: The present invention relates to a process for the production of trimerized polyisocyanates containing at least 30 mole % of iminooxadiazinedione groups (asymmetric trimers) in the trimer mixture by catalytically trimerizing a starting isocyanate selected from organic di- or polyisocyanates having a number average molecular weight of 140 to 600 and containing aliphatically, cycloaliphatically and/or araliphatically bound isocyanate groups in the presence of quaternary ammonium and phosphonium fluoride trimerization catalysts corresponding to the formulaR.sub.4 E.sup.+ F.sup.- (I),whereinE represents N or P andR represents identical or different, optionally branched, aliphatic, aromatic and/or araliphatic C.sub.1 -C.sub.

Abstract: A reduced-color isocyanurate-functional polyisocyanate is prepared by partially trimerizing 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI) having a low total chlorine content of less than 80 mg/kg in the presence of a catalyst, thereby resulting in a product isocyanurate-functional polyisocyanate having a content of free NCO groups of between 10 and 22% and a residual monomer content of less than 0.7%.

Abstract: The present invention relates to a process for the preparation of trimerized polyisocyanates that contain at least 30 mole % of iminooxadiazinedione groups (asymmetric trimers) in the trimer mixture, by catalytically trimerizing a starting isocyanate selected from organic di- or polyisocyanates having a number average molecular weight of 140 to 600 and containing aliphatically, cycloaliphatically and/or araliphatically bound isocyanate groups in the presence of a quaternary phosphonium polyfluoride trimerization catalyst corresponding to the formulaR.sub.4 P.sup.+ F.sup.- n(HF)whereinR represents identical or different, optionally branched aliphatic, aromatic and/or araliphatic C.sub.1 -C.sub.20 groups, or two or more R groups may also form, with one another and with the phosphorus atom, saturated or unsaturated rings andn has a value of 0.1 to 20.

Abstract: This invention relates to a novel freeze-stable allophanate modified toluene diisocyanurates, and to a process for producing these freeze-stable allophanate-modified toluene diisocyanurates which requires a catalyst which is capable of forming both trimer and allophanate groups, or a catalyst system comprising at least one catalyst capable of forming trimer groups and at least one catalyst capable of forming allophanate groups. This invention also relates to novel freeze-stable blends of the allophanate-modified toluene diisocyanurates with di- and/or polyisocyanates of the diphenylmethane series; and to freeze-stable urethane prepolymers of the allophanate-modified toluene diisocyanurates, or the blends of these with an isocyanate of the diphenylmethane series.

Abstract: Solid vinyl ether terminated curing agents for powder coatings can be prepared by reacting an aliphatic diisocyanate with a polyol and then with a hydroxy vinyl ether, or by reacting an aliphatic polyisocyanate with a hydroxy vinyl ether. Powder coatings based on the so prepared curing agents are extremely useful for coating heat sensitive substrates by exposure to ultraviolet light, heat, or both.

Abstract: This invention relates to a novel trimerization catalyst system, and to a process for trimerizing organic polyisocyanates in the presence of thermally active catalyst systems. These catalyst systems comprise (A) compounds selected from the group consisting of (i) lithium salts of aliphatic or aromatic carboxylic acids, (ii) lithium salts of hydroxyl group containing compounds wherein the hydroxyl groups are directed attached to an aromatic ring, and (iii) lithium hydroxide; (B) an allophanate catalyst; and (C) an organic compound which contains at least one hydroxyl group.

Abstract: The present invention relates to a process for the preparation of blocked polyisocyanates containing isocyanurate groups bya) reacting 20 to 80 equiv. % of the isocyanate groups of an organic diisocyanate with a pyrazole or triazole blocking agent,b) trimerizing the remaining unblocked isocyanate groups in the presence of a basic trimerization catalyst until the isocyanate content is less than 2.5% by weight, based on the weight of the blocked polyisocyanate andc) optionally blocking any remaining isocyanate groups with a blocking agent for isocyanate groups.The present invention also relates to the use of these blocked polyisocyanates for the production of polyisocyanate addition products.

Abstract: The present invention relates to compounds that can maintain, increase, or restore sensitivity of cells to therapeutic or prophylactic agents. This invention also relates to pharmaceutical compositions comprising these compounds. The compounds and pharmaceutical compositions of this invention are particularly well-suited for treatment of multi-drug resistant cells, for prevention of the development of multi-drug resistance, and for use in multi-drug resistant cancer therapy.

Abstract: This invention relates to a process for trimerizing organic polyisocyanates in the presence of thermally active catalyst systems. The catalyst systems comprise (a) compounds selected from the group consisting of 1) lithium salts of aliphatic or aromatic carboxylic acids, 2) lithium salts of hydroxyl group containing compounds wherein the hydroxyl groups are directed attached to an aromatic ring, and 3) lithium hydroxide; used in conjunction with (b) an organic compound which contains at least one hydroxyl group.

Abstract: Disclosed is a blocked polyisocyanate composition comprising: a blocked polyisocyanate obtained by blocking the terminal isocyanate groups of a two or more terminal isocyanate groups-containing polyisocyanate derived from at least one diisocyanate selected from an aliphatic diisocyanate and an alicyclic diisocyanate with a blocking agent comprising at least one active methylene compound selected from a malonic diester and an acetoacetic ester; and a salt of a basic compound with an acidic compound, or a mixture of the salt with the basic compound or the acidic compound, the composition having a pH value of from 1 to 8.5. The blocked polyisocyanate composition of the present invention not only exhibits high stability even under high temperature conditions, but also is capable of maintaining such high stability for a prolonged period of time.

Abstract: A process for the production of polyisocyanates containing isocyanurate groups by the catalytic trimerization of a mixture of low molecular weight isocyanate components having aliphatically and aromatically bound isocyanate groups in the presence of aminosilyl compounds, the resulting polyisocyanates and their use in coating compositions.

Abstract: The present invention is directed to a polyisocyanate mixture whichi) is prepared from a monomeric starting material containinga) 95 to 100% by weight, based on the weight of a) and b), of an aliphatic diisocyanate having 4 to 18 carbons in the hydrocarbon chain andb) 0 to 5% by weight, based on the weight of a) and b), of a diisocyanate other component a),ii) has an equivalent weight that is at least 30% greater than the average molecular weight of the monomeric starting material and a viscosity of greater than 10,000 to 100,000 mPa.s when determined at 25.degree. C. on a sample having a solids content of 100% and containing less than 2% by weight of unreacted diisocyanates a) and b), andiii) contains isocyanurate groups and allophanate groups in a molar ratio of 10:1 to 1:10, wherein the allophanate groups are derived from urethane groups that are the reaction product of starting material i) with 0.01 to 0.6 moles, per mole of starting material i), of a monoalcohol having a molecular weight of up to 2500.

Abstract: A process for the preparation of isocyanurate group-containing polyisocyanates in solvents which are inert towards isocyanate groups by reacting 0.2 to 1.5% of the isocyanate groups of diisocyanatotoluene with an aliphatic monohydric alcohol having 6 to 22 carbon atoms and subsequently trimerizing at least a portion of the isocyanate groups of the urethanized diisocyanates in the form of 40 to 70 wt. % solutions in lacquer solvents which are inert towards isocyanate groups, and the use of these polyisocyanates in two-component polyurethane coating compositions.

Abstract: The present invention is directed to a polyisocyanate containinga) polyisocyanates containing isocyanurate groups and corresponding to formula 1 ##STR1## wherein R represents the residue obtained by removing one of the isocyanate groups from 4-isocyanatomethyl-1,8-octamethylene diisocyanate,optionally in admixture withb) unreacted 4-isocyanatomethyl-1,8-octamethylene diisocyanate,c) higher homologs of the polyisocyanates set forth in formula 1 containing more than one isocyanurate group andd) a polyisocyanate containing allophanate groups.The present invention also relates to the use of these polyisocyanate mixtures, optionally in blocked form, as an isocyanate component in one- or two-component coating compositions.

Abstract: A method for preparing a polyurethane foam which comprises reacting an organic polyisocyanate and a polyol in the presence of a blowing agent, a cell stabilizer and a catalyst composition comprising at least one compound of either of the following formulas IA and IB: ##STR1## where R is hydrogen, methyl or hydroxymethyl. The preferred catalysts comprise 3-hydroxymethyl quinuclidine, 3-methyl-3-hydroxymethyl quinuclidine and 4-hydroxymethyl quinuclidine.

Abstract: A process for preparing isocyanate adducts having a high proportion of monoisocyanurate using a quaternary ammonium carboxylate trimerization catalyst. Also claimed are specific carboxylate catalysts, together with a process for producing the catalysts. The catalysts are particularly useful for trimerizing hexamethylene diisocyanate and isophorone diisocyanate.

Abstract: A process for preparing liquid lacquer polyisocyanates with aliphatically and aromatically bound isocyanate groups and an NCO content of 5 to 25 wt. % by trimerizing an isocyanate component A), containing A1) 70 to 100 wt. % of diisocyanatotoluene and A2) 0 to 30 wt. % of other aromatic isocyanates and B) aliphatic lacquer polyisocyanates, optionally with prior, simultaneous and/or subsequent reaction of a portion of the isocyanate groups with an alcohol component C) having a molecular weight of 32 to 900, and optionally in the presence of D) inert solvents; the resulting lacquer polyisocyanates; and their use in coating compositions, in particular as a cross-linking agent for polyhydroxyl compounds in two-component polyurethane coating compositions.

Abstract: The present invention is directed to a polyisocyanate mixturei) having an NCO content of 5 to 35% by weight and prepared from an organic diisocyanate,ii) containing at least 1% by weight of isocyanurate groups (calculated as N.sub.3, C.sub.3, O.sub.3, MW 126),iii) containing allophanate groups in an amount such that there are more equivalents of allophanate groups than urethane groups andiv) containing fluorine (calculated as F, AW 19) in an amount of 0.

Abstract: Diisocyanates containing carboxylic acid ester groups corresponding to the formula: ##STR1## in which R and R.sup.1 represent specified groups are produced by phosgenation of the corresponding diamines, optionally present in the form of an ammonium salt. These diisocyanates are useful as starting materials in the production of plastics containing urethane and/or urea groups and as starting materials for the production of intermediate products used for the production of such plastics.

Abstract: The present invention is directed to a polyisocyanate mixturei) having an NCO content of 5 to 35% by weight and prepared from an organic diisocyanate,ii) containing less than 5% by weight of isocyanurate groups (calculated as N.sub.3, C.sub.3, O.sub.3, MW 126),iii) containing allophanate groups in an amount such that there are more equivalents of allophanate groups than urethane groups andiv) containing fluorine (calculated as F, AW 19) in an amount of 0.001 to 50% by weight, based on solids.,wherein fluorine is incorporated with compounds containing two or more carbon atoms, one or more hydroxyl groups and one or more fluorine atoms. The present invention is also directed to a process for the production of this polyisocyanate mixture and to its use, optionally in blocked form, as an isocyanate component in one- or two-component coating compositions.

Abstract: A method for preparing a polyurethane foam which comprises reacting an organic polyisocyanate and a polyol in the presence of a blowing agent, cell stabilizer and a catalyst composition consisting essentially of a pyrrolizidine of the formula: ##STR1## where R.sub.1 and R.sub.2 independently are --H, --OH, ##STR2## or --NR.sub.4 R.sub.5, R.sub.3 is hydrogen, a C.sub.1 -C.sub.12 alkyl, C.sub.5 -C.sub.6 cycloalkyl, C.sub.6 -C.sub.10 aryl, or C.sub.7 -C.sub.11 arylalkyl group, andR.sub.4 and R.sub.5 independently represent H, a C.sub.1 -C.sub.12 alkyl group, C.sub.5 -C.sub.10 cycloalkyl, C.sub.6 -C.sub.10 aryl, or C.sub.7 -C.sub.11 arylalkyl group, provided that at least R.sub.1 or R.sub.2 is not hydrogen.

Abstract: The present invention relates to a process for the production of storage stable prepolymers containing free isocyanate groups by reactinga) an organic polyisocyanate component having (cyclo)aliphatically bound isocyanate groups and a maximum functionality of 4.5 withb) one or more hydroxy-functional polyacrylate resins having a content of alcoholic hydroxy groups of 0.05 to 7% by weight at an equivalent ratio of isocyanate groups of component a) to hydroxyl groups of component b) of 3:1 to 40:1, wherein components a) and b) are selected to provide a value B of at most 4 when calculated in accordance with the formula: ##EQU1## wherein F.sub.1 and F.sub.2 represent the NCO and OH functionalities of components a) and b), F.sub.1 representing the component with the lower functionality when the components differ in functionality andval.sub.A /val.sub.I represents the OH/NCO equivalent ratio of components a) and b).

Abstract: Melamine cyanurate is prepared by heating melamine powder and cyanuric acid powder at 250.degree. to 500.degree. C. substantially in the absence of any liquid medium. The melamine cyanurate can be obtained in a granular form when the heating is conducted subsequent to granulation of a mixture of both the powders.

Abstract: Polyisocyanates containing isocyanurate groups are prepared by a partial trimerization of (cyclo)aliphatic diisocyanates in the presence of at least one trimerization catalyst selected from the group consisting of tetraalkylammonium alkyl carbonates of the formula (I) ##STR1## (quaternary ammonioalkyl) carbonates having a betaine structure of the formula (II) ##STR2## and the preferred use of the polyisocyanates containing isocyanurate groups which are obtainable in this way is aspolyisocyanate component in polyurethane finishes.

Abstract: The present invention is directed to a polyisocyanate mixture having an NCO content of 10 to 47% by weight and a viscosity of less than 10,000 mPa.s and containing isocyanurate and allophanate groups in a molar ratio of monoisocyanurates to monoallophanates of 10:1 to 1:5, wherein the allophanate groups are formed from urethane groups which are based on the reaction product of an organic diisocyanate having (cyclo)aliphatic bound isocyanate groups and an aromatic monoalcohol containing 6 to 9 carbon atoms.The present invention is also directed to a process for the production of a polyisocyanate mixture having an NCO content of 10 to 47% by weight, having a viscosity of less than 10,000 mPa.s and containing isocyanurate and allophanate groups in a molar ratio of monoisocyanurates to monoallophanates of 0:1 to 1:5 bya) catalytically trimerizing a portion of the isocyanate groups of an organic diisocyanate having (cyclo)aliphatically bound isocyanate groupsb) adding 0.01 to 0.

Abstract: Isocyanurate- and/or uretidone-containing polyisocyanates having a reduced color index and improved shelf life are prepared by conventional catalytic oligomerization of aliphatic and/or cycloaliphatic diisocyanates and treatment of the oligomerization products with peroxycarboxylic acids.

Abstract: A process for the preparation of isocyanurate and urethane group-containing and, if desired, uretdiode and allophanate group-containing polyisocyanate mixtures by partially cyclizing organic, preferably (cyclo)aliphatic diisocyanates, in the presence of trimerization catalysts, deactivating these catalysts, reacting the partially trimerized, isocyanurate and, if desired, uretdiode group-containing polyisocyanate mixture with 0.5 to 10 mol % of at least one aliphatic or cycloaliphatic alcohol and/or polyoxyalkylene alcohol, and separating off the monomeric diisocyanates.

Abstract: An amine-boron composition for catalyzing the urethane reaction, particularly in preparing a polyurethane foam, consisting essentially of the addition product of a tertiary amine and a boron compound of the formulaR.sub.n B(OH).sub.3-nwheren=0 or 1, andR=C.sub.1 -C.sub.8 alkyl, C.sub.5 -C.sub.8 cycloalkyl or C.sub.6 -C.sub.10 aryl.Preferred catalysts are prepared by mixing triethylenediamine or 3-quinuclidinol with boric acid.

Abstract: An amine-boron composition for catalyzing the urethane reaction, particularly in preparing a polyurethane foam, consisting essentially of the addition product of a tertiary amine and a boron compound of the formulaR.sub.n B(OH).sub.3-nwheren=0 or 1, andR=C.sub.1 -C.sub.8 alkyl, C.sub.5 -C.sub.8 cycloalkyl or C.sub.6 -C.sub.10 aryl.Preferred catalysts are prepared by mixing triethylenediamine with boric acid.

Abstract: Energy polymerizable compositions comprising at least one cyanate monomer and as curing agent an organometallic compound are disclosed. The compositions are useful in applications requiring high performance, such as high temperature performance; in composites, particularly structural composities; structural adhesives; tooling for structural composities; electronic applications such as printed wiring boards and semiconductor encapsulants; graphic arts; injection molding and prepregs; and high performance binders.

Abstract: The present invention is directed to a polyisocyanate mixture whichi) has an NCO content of 5 to 47% by weight,ii) is prepared from an isocyanate component substantially containing one or more cyclic organic diisocyanates having (cyclo)aliphatically-bound isocyanate groups andiii) contains isocyanurate and allophanate groups in a molar ratio of monolsocyanurates to monoallophanates of 10:1 to 1:10, wherein the allophanate groups are formed from urethane groups which are based on the reaction product of an organic diisocyanate having (cyclo)aliphatically bound isocyanate groups and a monoalcohol containing at least 1 carbon atom and having a molecular weight of up to 2500.The present invention is also directed to a process for the production of these polyisocyan mixtures and to their use, optionally in blocked form, as an isocyanate component in two-component coating compositions.

Abstract: A method for preparing a polyurethane foam which comprises reacting an organic polyisocyanate and a polyol in the presence of a blowing agent, cell stabilizer and a catalyst composition which comprises a quaternary ammonium carboxylate inner salt having the following formula I ##STR1## where R.sub.1 -R.sub.3 are independently C.sub.1 -C.sub.12 alkyl, C.sub.5 -C.sub.8 cycloalkyl or a heterocycle, C.sub.6 -C.sub.10 aryl or heteroaromatic. R.sub.1 and R.sub.2 or R.sub.1 -R.sub.3 together with the nitrogen atom can also be part of nitrogen containing ring system such as piperidine, morpholine, triethylenediamine, imidazole, or 1,8-diazabicyclo-[5.4.0]undec-7-ene. R.sub.4 is a divalent R.sub.1.

Abstract: A process for producing an isocyanate trimer and a process for producing an urethane with a catalyst for isocyanate trimerization or urethane formation, which comprises cesium fluoride or a tetraalkylammonium fluoride.

Abstract: A method is provided to prepare triaryl isocyanurates from aryl isocyanates by using triazaprophosphatrane catalysts.

Abstract: A method for preparing a polyurethane foam which comprises reacting an organic polyisocyanate and a polyol in the presence of a blowing agent, cell stabilizer and a catalyst composition which comprises a quaternary ammonium carboxylate inner salt having the following formula I ##STR1## where R.sub.1 -R.sub.3 are independently C.sub.1 -C.sub.12 alkyl, C.sub.5 -C.sub.8 cycloalkyl or a heterocycle, C.sub.6 -C.sub.10 aryl or heteroaromatic. R.sub.1 and R.sub.2 or R.sub.1 -R.sub.3 together with the nitrogen atom can also be part of nitrogen containing ring system such as piperdine, morpholine, triethylenediamine, imidazole, or 1,8-diazabicyclo-[5.4.0]-undec-7-ene. R.sub.4 is a divalent R.sub.1.