POLYURETHANE COMPRISING FORMULATIONS WITH ISOCYANATE

Abstract

A urethane group-containing reactive polyisocyanate composition is disclosed which contains not more than 1 wt % of monomeric starting di-isocyanate based on the total weight of said polyisocyanate composition, having an NCO value in the range 0.1-15%, and wherein said composition comprises urethane groups and allophanate groups and wherein the ratio of allophanate groups over urethane groups is between 0.05 and 100.

Claims

1. A urethane group-containing reactive polyisocyanate composition which contains not more than 1 wt % of monomeric starting di-isocyanate based on the total weight of said polyisocyanate composition, having an NCO value in the range 0.1-15%, and wherein said composition comprises urethane groups and allophanate groups and wherein the ratio of allophanate groups over urethane groups is between 0.05 and 100.

2. The reactive polyisocyanate composition according to claim 1, wherein the amount of monomeric starting di-isocyanate molecules is below 0.5 wt %, based on the total weight of said polyisocyanate composition.

3. The reactive polyisocyanate composition according to claim 1, wherein the NCO value is in the range 0.8-2%.

4. The reactive polyisocyanate composition according to claim 1, wherein the ratio allophanate groups over urethane groups is larger than 0.1.

5. A method to prepare the reactive polyisocyanate composition according claim 1, said method comprising mixing at least following compounds: an allophanate based polyisocyanate intermediate prepolymer containing 0.1 wt % and 25 wt % of monomeric di-isocyanate compounds based on the total weight of said prepolymer and having an NCO value in the range 5-15%, and an isocyanate reactive composition containing isocyanate reactive compounds having a functionality between 1 and 10 and a molecular weight in the range 100-10000, and wherein the allophanate based polyisocyanate intermediate prepolymer is the reaction product of at least one polyisocyanate compound and an isocyanate reactive compound selected from a monool having a molecular weight in the range 32-2000 g/mol, preferably 36-2000 g/mol, and wherein the ratio of allophanate groups over the urethane groups is higher than 0.05.

6. The method according to claim 1, wherein the allophanate based polyisocyanate intermediate prepolymer contains 5 wt % and 20 wt % monomeric starting di-isocyanate compounds based on the total weight of said prepolymer.

7. The method according to claim 1, wherein the ratio of allophanate groups over the urethane groups in the allophanate based polyisocyanate intermediate prepolymer is in the range 1-100.

8. The method according to claim 1, wherein the allophanate based polyisocyanate intermediate prepolymer has an NCO value in the range 8-12%.

9. The method according to claim 1, wherein the monools are selected from polyoxyalkylene polyether monools, polyester monools and modified castor oil monools, having an average molecular weight of 32-1000 g/mol.

10. The method according to claim 1, wherein the polyisocyanate compounds used to make the polyisocyanate intermediate prepolymer are selected from diphenylmethane diisocyanate (MDI) based polyisocyanates having <40 wt % 2,4 MDI calculated on the total weight of the organic polyisocyanate mixture.

11. The method according to claim 1, wherein the isocyanate reactive compounds used to react with the allophanate intermediate prepolymer is having a functionality between 1.8 and 10.

12. The method according to claim 1, wherein the isocyanate reactive compounds used to react with the allophanate intermediate prepolymer are selected from the group comprising polyethers, polyesters, acrylic polyols, castor oil and modified castor oils, polybutadiene, polyolefin, or combinations thereof.

13. An allophanate based polyisocyanate intermediate prepolymer suitable for making the urethane group-containing polyisocyanate composition according to claim 1, said intermediate prepolymer is the reaction product a reactive composition comprising of at least one polyisocyanate compound and at least one isocyanate reactive compound selected from a monool having a molecular weight in the range 32-2000 g/mol and wherein the composition comprises: (i) 0.1 wt % and 25 wt % monomeric di-isocyanate compounds based on the total weight of said prepolymer; (ii) an NCO value in the range 5-15%; (iii) a ratio of allophanate groups over urethane groups higher than 0.05.

14. (canceled)

Description

DETAILED DESCRIPTION

[0054] The present invention will be described with respect to particular embodiments.

[0055] It is to be noticed that the term comprising, used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to be interpreted as specifying the presence of the stated features, steps or components as referred to, but does not preclude the presence or addition of one or more other features, steps or components, or groups thereof. Thus, the scope of the expression a device comprising means A and B should not be limited to devices consisting only of components A and B. It means that with respect to the present invention, the only relevant components of the device are A and B.

[0056] Throughout this specification, reference to one embodiment or an embodiment are made. Such references indicate that a particular feature, described in relation to the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases in one embodiment or in an embodiment in various places throughout this specification are not necessarily all referring to the same embodiment, though they could. Furthermore, the particular features or characteristics may be combined in any suitable manner in one or more embodiments, as would be apparent to one of ordinary skilled in the art.

[0057] It is to be understood that although preferred embodiments and/or materials have been discussed for providing embodiments according to the present invention, various modifications or changes may be made without departing from the scope and spirit of this invention.

[0058] The present invention relates to a urethane group-containing polyisocyanate composition (also referred to as a 1 component isocyanate prepolymer) which has an NCO value below 15 and contains not more than 1 wt % of monomeric starting di-isocyanate based on the weight of said polyisocyanate composition. Further the invention relates to a process for making the polyisocyanate composition and the intermediate allophanate based polyisocyanate prepolymers and polyol composition required to make the urethane group-containing polyisocyanate composition according to the invention. Furthermore, the invention relates to the use of the urethane group-containing polyisocyanate composition according to the invention in adhesive and coating applications.

[0059] According to a first aspect of the invention, a urethane group-containing reactive polyisocyanate composition which contains not more than 1 wt % of monomeric (starting) di-isocyanate molecules based on the total weight of said polyisocyanate composition and having an NCO value in the range 0.1-15% is disclosed. Said urethane group-containing polyisocyanate composition is containing urethane groups and allophanate groups and has a ratio of allophanate groups over urethane groups larger than 0.05 and below 100.

[0060] According to embodiments the amount of monomeric starting di-isocyanate molecules in the urethane group-containing polyisocyanate composition of the invention is preferably below 0.5 wt %, most preferably below 0.1 wt % monomeric starting di-isocyanate molecules based on the total weight of said polyisocyanate composition.

[0061] According to embodiments, the NCO value in the urethane group-containing polyisocyanate composition of the invention is preferably in the range 0.8-2%, preferably in the range 1-2%, most preferably the NCO value is around 1%, for example the NCO value may be 0.9%, 1%, 1.1%, 1.2%.

[0062] According to embodiments, the ratio allophanate groups over urethane groups is below 100 and larger than 0.05, preferably larger than 0.1, preferably larger than 1.

[0063] According to a second aspect a method is disclosed to prepare the urethane group-containing polyisocyanate composition according to the present invention. Said method comprising mixing at least following compounds: [0064] An allophanate based polyisocyanate intermediate prepolymer containing 0.1 wt % and 25 wt % of monomeric starting di-isocyanate compounds based on the total weight of said prepolymer and having an NCO value in the range 5-15%, and [0065] An isocyanate reactive composition containing isocyanate reactive compounds having a functionality between 1.8 and 10, and [0066] Wherein the allophanate based polyisocyanate intermediate prepolymer is the reaction product of at least one polyisocyanate compound and an isocyanate reactive compound selected from a monool having a molecular weight in the range 32-2000 g/mol, preferably 36-2000 g/mol and wherein the ratio of allophanate groups over the urethane groups is larger than 0.05, preferably in the range 1-100.

[0067] According to preferred embodiments, the allophanate based polyisocyanate intermediate prepolymer contains 5 wt % and 20 wt % of monomeric starting di-isocyanate compounds based on the total weight of said prepolymer. Most preferred the wt % of monomeric starting di-isocyanate is in the range 8-15 wt % based on the total weight of said prepolymer.

[0068] According to preferred embodiments, the allophanate based polyisocyanate intermediate prepolymer has an NCO value in the range 8-12%.

[0069] Allophanates are typically formed at elevated temperatures (higher than 100 C.) or in the presence of special catalysts at lower temperatures by a reaction between urethane groups and isocyanate groups to form allophanate linkages:

##STR00001##

[0070] Wherein R.sub.1 and R.sub.2 represent a rest group or any other isocyanate molecule and M is representing in this invention a monool.

[0071] Suitable polyisocyanates comprise polyisocyanates of the type R(NCO).sub.x with x being at least 1 and R being an aromatic or aliphatic group, such as diphenylmethane, toluene, dicyclohexylmethane, hexamethylene, or a similar polyisocyanate. Preferably, said polyisocyanate comprises at least two isocyanate groups.

[0072] Non-limiting examples of suitable organic polyisocyanates which may be used in the present invention include aliphatic isocyanates such as hexamethylene diisocyanate; and aromatic isocyanates such as diphenylmethane diisocyanate (MDI), in the form of mixtures of its 2,4-, 2,2- and 4,4-isomers and mixtures of diphenylmethane diisocyanates (MDI) and oligomers thereof, as well as polymeric methylene diphenyl diisocyanate (pMDI), m- and p-phenylene diisocyanate, tolylene-2,4- and tolylene-2,6-diisocyanate (also known as toluene diisocyanate, and referred to as TDI, such as 2,4 TDI and 2,6 TDI) in any suitable isomer mixture, chlorophenylene-2,4-diisocyanate, naphthylene-1,5-diisocyanate, diphenylene-4,4-diisocyanate, 4,4-diisocyanate-3,3-dimethyl-diphenyl, 3-methyl-diphenylmethane-4,4-diisocyanate and diphenyl ether diisocyanate; and cycloaliphatic diisocyanates such as cyclohexane-2,4- and -2,3-diisocyanate, 1-methylcyclohexyl-2,4- and -2,6-diisocyanate and mixtures thereof and bis-(isocyanatocyclohexyl)methane (e.g. 4,4-diisocyanatodicyclohexylmethane (H12MDI)), triisocyanates such as 2,4,6-triisocyanatotoluene and 2,4,4-triisocyanatodiphenylether, isophorone diisocyanate (IPDI), butylene diisocyanate, trimethylhexamethylene diisocyanate, isocyanatomethyl-1,8-octane diisocyanate, tetramethylxylene diisocyanate (TMXDI), 1,4-cyclohexanediisocyanate (CDI), and tolidine diisocyanate (TODI); any suitable mixture of these polyisocyanates.

[0073] Suitable catalysts for initiating the formation of allophanates are for example Zn-neodecanoate, commercially available as Valikat Zn1910 from Umicore and alkylacetoacetate based catalysts such as Zn-acetylacetonate or any suitable catalyst capable of forming allophanate linkages in polyisocyanates.

[0074] Catalyst deactivators to be used in the invention include acidic materials such as thionyl chloride. Generally, catalyst stoppers are added in a ratio of at least 1 equivalent of deactivator to each mole of the allophanate catalyst, e.g. Zn-acetylacetonate.

[0075] According to embodiments, the monools suitable for making the allophanate based polyisocyanate intermediate prepolymer of the invention may be selected from polyoxyalkylene polyether monools which may be prepared by the simple addition of one or more alkylene oxides to an initiator fatty hydrocarbon having one alkylene oxide active hydrogen represented by the general formula RX where R represents a C8-C24 branched or unbranched, saturated or ethylenically unsaturated, aliphatic or alicyclic radical; preferably an aliphatic linear, saturated or ethylenically unsaturated radical; more preferably a linear alkyl (saturated) radical, and most preferably a linear C12-C15 alkyl radical; and X represents OH, NRH, or SH, preferably OH.

[0076] According to embodiments, the monools suitable for making the allophanate based polyisocyanate intermediate prepolymer of the invention may be selected from methanol, ethanol, propanol, butanol, phenol, cyclohexanol and hydrocarbon monools having an average molecular weight in the range 32-2000 g/mol, preferably 36-2000 g/mol, more preferably 32-1000 g/mol, even more preferably 100-1000 g/mol, and advantageously 250-750 g/mol, such as aliphatic monools, polyether monools, polyester monools and modified castor oil monools. A preferred example of a suitable polyether monool is poly(ethylene glycol) methyl ether.

[0077] According to embodiments, the polyisocyanate compounds used in the urethane group-containing polyisocyanate composition according to the present invention are selected from organic isocyanates containing a plurality of isocyanate groups including aliphatic, cycloaliphatic and/or araliphatic polyisocyanates, preferably diphenylmethane diisocyanate (MDI) based polyisocyanates, preferably diphenylmethane diisocyanate (MDI) based polyisocyanates having <50 wt % 2,4 MDI, most preferably diphenylmethane diisocyanate (MDI) based polyisocyanates having <40 wt % 2,4 MDI calculated on the total weight of the organic polyisocyanate mixture. Advantageously, it has been observed that using diphenylmethane diisocyanate (MDI) based polyisocyanates containing 2,4 MDI at a content ranging from 10 to 40 wt % is preferred, based on the total weight of the organic polyisocyanate mixture.

[0078] Methylene bridged polyphenyl polyisocyanates (e.g. Methylene diphenyl diisocyanate, abbreviated as MDI) are well known in the art and have the generic formula I wherein n is one or more and in the case of the crude mixtures represents an average of more than one. They are prepared by phosgenation of corresponding mixtures of polyamines obtained by condensation of aniline and formaldehyde.

##STR00002##

[0079] According to embodiments, the isocyanate reactive compounds used to react with the allophanate intermediate prepolymer (in order to make the urethane group-containing polyisocyanate composition according to the present invention) have a functionality between 1 and 10, preferably between preferably 2 to 4.

[0080] According to embodiments, the isocyanate reactive compounds used to react with the allophanate intermediate prepolymer have an average molecular weight in the range 100-10000 g/mol, preferably 500-5000 g/mol.

[0081] According to embodiments, the isocyanate reactive compounds used to react with the allophanate intermediate prepolymer (in order to make the urethane group-containing polyisocyanate composition according to the present invention) are selected from the group comprising polyethers, polyesters, acrylic polyols, polycarbonates, castor oil and modified castor oils, polybutadienes, polyolefines. Examples of suitable isocyanate reactive compounds are polyester polyols such as Hoopol F1390 or Hoopol F931 (polyester polyols from Synthesia).

[0082] According to a third aspect of the invention, an allophanate based polyisocyanate intermediate prepolymer suitable for making the urethane group-containing reactive polyisocyanate composition according to the present invention is disclosed. Said allophanate based polyisocyanate intermediate prepolymer is the reaction product of at least one polyisocyanate compound and at least one isocyanate reactive compound selected from a monool having a molecular weight in the range 32-2000 g/mol, preferably 36-2000 g/mol, more preferably 32-1000 g/mol, even more preferably 100-1000 g/mol, and advantageously 250-750 g/mol and having following characteristics: [0083] Containing 0.1 wt % and 25 wt %, preferably 5 wt % and 20 wt %, more preferably 8 wt % and 15 wt % monomeric di-isocyanate compounds based on the total weight of said prepolymer, and [0084] Having an NCO value in the range 5-15%, preferably in the range 8-12%, and [0085] Having a ratio of allophanate groups over urethane groups higher than 0.05, preferably in the range 1-100.

[0086] The allophanate based polyisocyanate intermediate prepolymer is made by at least one polyisocyanate compound and at least one isocyanate reactive compound selected from a monool thereby using a specific allophanate forming catalyst at temperatures (cook temperature) below 120 C., preferably <110 C. and most preferred <100 C.

[0087] According to a fourth aspect, the use of the urethane group-containing polyisocyanate composition of the present invention is disclosed (also referred to commercially as 1 component PU systems) for making sealants, coatings, adhesives.

[0088] According to embodiments, the urethane group-containing polyisocyanate composition of the present invention may be applied by means of spraying after the required ingredients were mixed at the departure point from a spray nozzle, by dispensing, by roller or by brush application.

[0089] The invention is now illustrated with below reference to the examples. The examples are given for the sake of example only, without limiting the scope of the invention.

Examples

[0090] Chemicals Used: [0091] Hoopol F-931: Polyester polyol from Synthesia (OH value: 37-40 mgKOH/g) [0092] Suprasec 1306 from Huntsman (pure 4,4 MDI, NCO value 33.6%) [0093] Suprasec 2008 from Huntsman (prepolymer from MDI and polyether polyol, NCO value 10.2%) [0094] Suprasec 3030 from Huntsman (mix from 60-65% 4,4 MDI and 35-40% 2.4 MDI, NCO value 33.6%) [0095] Daltocel XF460 from Huntsman (polyether polyol, Mw4000, OHv 30, f 1.8, PO-EO tipped) [0096] MPEG500 from Ineos, Poly(ethylene glycol) methyl ether with average molecular weight of 500 g/mol used as monool [0097] Valikat Zn1910 from Umicore, zinc neodecanoate: an allophanate initiating catalyst [0098] Zn-acetylacetonate from Aldrich, an allophanate initiating catalyst [0099] Thionyl chloride from Aldrich, a catalyst deactivator.

[0100] The NCO content of all prepolymers was determined by titration according to DIN 53185. The MDI monomeric content (di-isocyanate) was determined by GPC (determination di-isocyanate) combined with GC-MS (correction 4,4/2,4). The degree of allophanation was determined by 13C NMR.

[0101] In the following examples, the urethane group-containing polyisocyanate composition is referred to as a reactive hot melt composition (RHM). The reactive hot melt composition made according to the invention are resulting in compositions having <1.0 wt % monomeric di-isocyanate.

1) Comparative Example: Reactive Hot Melt (RHM) Based on Pure MDI

[0102] Suprasec 1306 (pure MDI) was prepolymerized with Hoopol F931 to an NCO value of 3.0%.

[0103] 85.6 g Hoopol F931 was dried under vacuum at 100 C. and after cooling to 80 C., weighted into a reaction flask under nitrogen atmosphere. 14.4 g Suprasec 1306 was added while blanketing with nitrogen and stirring vigorously. Temperature was maintained for 1.5 hours until a NCO value of 3.0% was reached with a monomeric di-isocyanate content of 4.6%.

[0104] Conclusion: the RHM based on pure MDI (100% di-isocyanate) did not enable to achieve a monomeric di-isocyanate content <1.0%.

2) Comparative Example: Reactive Hot Melt (RHM) Based on Suprasec 2008

[0105] Suprasec 2008 (a prepolymer from MDI and polyether polyol, NCO value 10.2%; viscosity of 1700 mPa.Math.s at 25 C.) was prepolymerized with Hoopol F931 (commercial polyester polyol) to NCO value of 3.0%.

[0106] 42.5 g Hoopol F931 was dried under vacuum at 100 C. and after cooling to 80 C., weighted into a reaction flask under nitrogen atmosphere. 57.5 g Suprasec 2008 was added while blanketing with nitrogen and stirring vigorously. Temperature was maintained for 1.5 hours until a NCO content of 3.0% was reached with a monomeric di-isocyanate content of 4.1%.

[0107] Conclusion: the RHM based on a state of the art prepolymer with NCO value 10.2% (26% di-isocyanate) did not enable to achieve a monomeric di-isocyanate content <1%.

3) Example of the Invention: Reactive Hot Melt (RHM) Based on an Allophanate Based Polyisocyanate Intermediate Prepolymer

[0108] The allophanate intermediate is a prepolymer based on MDI and a monool (NCO value=10.7%; monomeric di-isocyanate content=15.9%; viscosity=2200 mPa.Math.s at 25 C.; degree of allophanation: allophanate/urethane ratio=6.9) using Zn AcAc as allophanate initiating catalyst and thionyl chloride as deactivator.

[0109] This allophanate intermediate prepolymer was further polymerised with Hoopol F931 (commercial polyester polyol) to NCO value of 1.5%.

[0110] 71.0 g Hoopol F931 was dried under vacuum at 100 C. and after cooling to 80 C., weighted into a reaction flask under nitrogen atmosphere. 29.0 g of the allophanate was added while blanketing with nitrogen and stirring vigorously. Temperature was maintained for 1.5 hours until a NCO content of 1.5% was reached with a monomeric di-isocyanate content of 0.4%.

[0111] Conclusion: the RHM based on an allophanate based prepolymer with NCO value 10.7% (15.9% di-isocyanate) enabled to achieve a monomeric di-isocyanate content <1.0%.

4) Example of the Invention: Reactive Hot Melt (RHM) Based on an Allophanate Based Polyisocyanate Intermediate Prepolymer

[0112] The allophanate intermediate is a prepolymer based on MDI and a monool (NCO value=10.7%; monomeric di-isocyanate content=15.9%; viscosity=2200 mPa.Math.s at 25 C.; degree of allophanation: allophanate/urethane ratio=6.9) using Zn AcAc as allophanate initiating catalyst and thionyl chloride as deactivator.

[0113] This allophanate intermediate prepolymer was further polymerised with Hoopol F931 (commercial polyester polyol) to NCO value of 1.0%.

[0114] 75.5 g Hoopol F931 was dried under vacuum at 100 C. and after cooling to 80 C., weighted into a reaction flask under nitrogen atmosphere. 24.5 g of the allophanate was added while blanketing with nitrogen and stirring vigorously. Temperature was maintained for 1.5 hours until a NCO content of 1.0% was reached with a monomeric di-isocyanate content <0.1%.

[0115] Conclusion: the RHM based on an allophanate based prepolymer with NCO value 10.7% (15.9% di-isocyanate) enabled to achieve a monomeric di-isocyanate content <0.1%.

5) Example of the Invention: Reactive Hot Melt (RHM) Based on an Allophanate Based Polyisocyanate Intermediate Prepolymer

[0116] The allophanate intermediate is a prepolymer based on MDI and a monool (NCO value=9.5%; monomeric di-isocyanate content=10.4%; viscosity=2040 mPa.Math.s at 25 C.; degree of allophanation: allophanate/urethane ratio=1.9) using Zn AcAc as allophanate initiating catalyst and thionyl chloride as deactivator.

[0117] This allophanate intermediate prepolymer was further polymerised with Hoopol F931 (commercial polyester polyol) to NCO value of 1.0%.

[0118] 72.3 g Hoopol F931 was dried under vacuum at 100 C. and after cooling to 80 C., weighted into a reaction flask under nitrogen atmosphere. 27.7 g of the allophanate was added while blanketing with nitrogen and stirring vigorously. Temperature was maintained for 1.5 hours until a NCO content of 1.0% was reached with a monomeric di-isocyanate content <0.1%.

[0119] Conclusion: the RHM based on an allophanate based prepolymer with NCO value 9.5% (10.4% di-isocyanate) enabled to achieve a monomeric di-isocyanate content <0.1%.