阅读说明：本技术 具有长乳白时间和快速固化行为的包含聚异氰脲酸酯的泡沫 (Polyisocyanurate comprising foams with long cream time and fast curing behaviour ) 是由 T·J·容舍雷 J·贝尔纳蒂尼 G·J·古梅兹 J·范登布罗克 于 2018-10-05 设计创作，主要内容包括：本发明公开了用于制备密度为50-500 kg/m<Sup>3</Sup>的包含聚异氰脲酸酯的硬质泡沫的反应混合物和方法,所述方法具有>35秒的乳白时间和快速固化行为。(The invention discloses a method for preparing a high-density polyethylene glycol terephthalate with the density of 50-500 kg/m 3 The process having a reaction mixture and a process for preparing rigid foams comprising polyisocyanurate having>Cream time of 35 seconds and fast curing behaviour.)

1. Used for preparing the material with the density of 50-500 kg/m³A reaction mixture comprising a Polyisocyanurate (PIR) foam of (a), the reaction mixture having an isocyanate index of at least 200 and comprising at least:

-a polyisocyanate composition comprising one or more polyisocyanate compounds;

-a catalyst composition comprising at least a trimerization catalyst compound in an amount of at least 50 wt. -%, based on the total weight of all catalyst compounds in the catalyst composition;

-an isocyanate reactive composition comprising at least a low MW polyol having a Molecular Weight (MW) below 200 g/mol in an amount of 0.1 up to 30 wt. -%, based on the total weight of the isocyanate reactive composition;

-one or more blowing agents comprising at least 50 mole% of water, based on the total molar amount of all blowing agents;

-optionally, one or more surfactants, one or more flame retardants, one or more antioxidants, or a combination thereof;

wherein the wt% of the trimerization catalyst compound is <0.5 wt% based on the total weight of the trimerization catalyst compound and the polyisocyanate composition.

2. The reaction mixture according to claim 1, wherein the trimerization catalyst compound is selected from organic salts, preferably from alkali metal organic salts, alkaline earth metal organic salts and/or quaternary ammonium organic salts, such as potassium acetate, potassium hexanoate, potassium ethylhexanoate, potassium octanoate, potassium lactate, ammonium N-hydroxypropyl trimethyl octanoate, ammonium N-hydroxypropyl trimethyl ammonium formate and mixtures thereof.

3. The reaction mixture according to any of claims 1-2, wherein the low Molecular Weight (MW) polyol has a molecular weight below 150 g/mol, preferably below 100 g/mol.

4. The reaction mixture of any one of claims 1-3, wherein the low Molecular Weight (MW) polyol is selected from glycerol and/or ethylene glycol.

5. The reaction mixture according to any one of claims 1-4, wherein the amount of the low Molecular Weight (MW) polyol is from 1 up to 25 wt. -%, more preferably from 2 up to 20 wt. -%, based on the total weight of the isocyanate reactive composition.

6. The reaction mixture according to any of claims 1-5, wherein the amount of the trimerization catalyst compound is at least 75 wt. -%, preferably at least 90 wt. -%, based on the total weight of all catalyst compounds in the catalyst composition.

7. The reaction mixture according to any one of claims 1-6, wherein the polyisocyanate compound is selected from toluene diisocyanate, methylene diphenyl diisocyanate or a polyisocyanate composition comprising methylene diphenyl diisocyanate or a mixture of such polyisocyanates.

8. The reaction mixture according to any one of claims 1 to 7, wherein the one or more isocyanate-reactive compounds further comprise a mono-and/or polyol having an average nominal hydroxyl functionality of from 1 to 8 and a number average molecular weight of 200 and 8000 g/mol, and mixtures of said mono-and/or polyols, such as polyether polyols and polyester polyols, thiols, carboxylic acids such as polyacids, amines, polyamines.

9. The reaction mixture according to any one of claims 1-8, wherein the blowing agent comprises isobutylene, dimethyl ether, methylene chloride, acetone, chlorofluorocarbons (CFCs), Hydrofluorocarbons (HFCs), Hydrochlorofluorocarbons (HCFCs), hydrogen (chloro) fluoroolefins (HFOs/HCFOs) and/or hydrocarbons in addition to water.

10. Used for preparing the material with the density of 50-500 kg/m³A process for the production of rigid foams comprising polyisocyanurate, the process having>Cream time of 35 seconds and fast curing behavior and comprises combining and mixing the components of the reaction mixture according to any one of claims 1 to 9 in an isocyanate index of at least 200 to obtain a foam.

11. The method according to claim 10, wherein the cream time is >45 seconds, more preferably >55 seconds, and the fast curing behavior (defined as the difference between the tack-free time and the cream time) is <110 seconds, preferably <90 seconds, more preferably <70 seconds.

12. The process according to any one of claims 10-11, wherein the isocyanate index is higher than 220, preferably higher than 250.

13. The process according to any one of claims 10-12, wherein the wt% of the trimerization catalyst compound is preferably <0.45 wt%, more preferably <0.40 wt%, most preferably <0.35 wt%, based on the total weight of trimerization catalyst compound and polyisocyanate composition.

14. The method according to any one of claims 10-13, wherein the wt% of the trimerization catalyst compound is <0.30 wt% based on the total weight of trimerization catalyst compound and polyisocyanate composition.

15. Polyisocyanurate comprising material obtained by the process according to any of claims 10-14.

16. Polyisocyanurate comprising material according to claim 15 having a free rise density (measured according to ISO 845) of 75 kg/m³Up to 300 kg/m³More preferably 100 kg/m³Up to 200 kg/m³。

17. Use of a polyisocyanurate comprising material according to claim 16 in composite honeycomb structures.

18. A composite material having a composite honeycomb structure with a core layer comprising a polyisocyanurate comprising material according to any of claims 15-16.

Technical Field

The present invention relates to reaction mixtures for preparing polyisocyanurate comprising cellular materials, in particular polyisocyanurate comprising rigid foams, for use in composite materials, such as honeycomb structures.

Further, the present invention relates to a process for the preparation of said polyisocyanurate comprising materials, whereby long cream times and fast curing behaviour (snap-cure behaviour) are achieved.

Still further, the present invention relates to polyisocyanurate comprising foams suitable for use in the preparation of composites.

Background

However, the current techniques for preparing polyisocyanurate comprising foams suitable for the preparation of composite honeycomb structures have several processing problems, such as too short cream times and/or too long curing times.

It is an object of the present invention to provide a reaction mixture which is intended for the preparation of polyisocyanurate comprising composites and which allows for the preparation of polyisocyanurate comprising composites with greater processing flexibility, in particular in terms of cream time and fast curing behaviour.

US 6,602,927 provides a polyisocyanurate system for making polyisocyanurate foam components. The reaction system comprises a polyisocyanate and a polyisocyanate-reactive component comprising a trimerisation catalyst, a polyol and a carboxylic acid blowing agent, optionally containing water as co-blowing agent. The reaction system can be foamed with only carboxylic acid to produce SRIM (structural reaction injection molded) products that can be demolded with reduced mold residence time. However, US' 927 does not give sufficient processing flexibility, especially in terms of cream time and fast curing behaviour, for polyisocyanurate systems which are predominantly water-blown (having at least 50 mole% of water based on the total molar amount of all blowing agents used).

US 5,109,031 relates to rigid cellular low density polymers prepared by reacting an organic polyisocyanate with a polyol component comprising a polyester polyol having a free diol content of less than about 7% by weight of the polyester polyol, in the presence of a blowing agent. The aim of US '031 is to improve the thermal insulation properties, however, US' 031 does not give sufficient processing flexibility, especially in terms of cream time and fast curing behaviour, for higher density polyisocyanurate cellular systems which are predominantly water blown (with at least 50 mole% water based on the total molar amount of all blowing agents used).

US 6,207,725 also relates to a process for the preparation of rigid polyurethane or urethane-modified polyisocyanurate foams prepared by reacting an organic polyisocyanate composition with an isocyanate-reactive composition comprising a polyester polyol in the presence of an amine catalyst. The purpose of US' 725 is to achieve a fast initial foam rise. US' 725 therefore does not give any processing details for foaming predominantly with water (with at least 50 mole% of water based on the total molar amount of all blowing agents used) thereby achieving long cream times and fast curing behaviour.

It is an object of the present invention to improve the processing for the preparation of polyisocyanurate foams suitable for use in composite materials such as honeycomb. The aim is to achieve the formation of polyisocyanurate comprising foams while achieving long cream times of at least 35 seconds and fast curing behaviour. A fast curing behavior will result in a more efficient curing and reduced cycle time, while a long cream time will allow flexibility in processing time, e.g. enough time to spray the reaction mixture and/or fill the mould before curing.

We have surprisingly found reaction mixtures for the preparation of polyisocyanurate comprising foams which lead to long cream times and fast curing behaviour.

The reaction mixtures of the present invention result in extended cream times and fast curing behavior, which enables easier processing on a laminator, and may also enable molding of PIR foams (this is not currently possible with prior art reaction mixtures due to foaming kinetics limitations of prior art reaction mixtures).

Disclosure of Invention

According to a first aspect, it is disclosed for preparing a foam having a density of 50 to 500kg/m³A reaction mixture comprising a Polyisocyanurate (PIR) foam of (a), the reaction mixture having an isocyanate index of at least 200 and comprising at least:

-a polyisocyanate composition comprising one or more polyisocyanate compounds;

-a catalyst composition comprising at least a trimerization catalyst compound in an amount of at least 50 wt. -%, based on the total weight of all catalyst compounds in the catalyst composition;

-an isocyanate reactive composition comprising at least a low MW polyol having a Molecular Weight (MW) below 200 g/mol in an amount of 0.1 up to 30 wt. -%, based on the total weight of the isocyanate reactive composition;

-one or more blowing agents comprising at least 50 mole% of water, based on the total molar amount of blowing agent;

-optionally, one or more surfactants, one or more flame retardants, one or more antioxidants, or a combination thereof;

wherein the wt% of the trimerization catalyst compound is <0.5 wt% based on the total weight of trimerization catalyst compound + polyisocyanate composition.

According to an embodiment, the wt% of the trimerization catalyst compound is <0.5 wt%, preferably <0.45 wt%, more preferably <0.4 wt%, most preferably <0.35 wt%, based on the total weight of catalyst composition + polyisocyanate composition.

According to an embodiment, the wt% of the trimerization catalyst compound is <0.3 wt% based on the total weight of catalyst composition + polyisocyanate composition.

According to an embodiment, the trimerization catalyst compound is selected from organic salts, preferably from alkali metal organic salts, alkaline earth metal organic salts and/or quaternary ammonium organic salts, such as potassium acetate, potassium hexanoate, potassium ethylhexanoate, potassium octanoate, potassium lactate, ammonium N-hydroxypropyl trimethyl octanoate, ammonium N-hydroxypropyl trimethyl ammonium formate and mixtures thereof.

According to an embodiment, the low Molecular Weight (MW) polyol has a molecular weight below 150 g/mol, preferably below 100 g/mol.

According to an embodiment, the low Molecular Weight (MW) polyol is selected from glycerol and/or ethylene glycol.

According to embodiments, the amount of the low Molecular Weight (MW) polyol is from 1 up to 25 wt. -%, more preferably from 2 up to 20 wt. -%, based on the total weight of the isocyanate reactive composition.

According to an embodiment, the amount of trimerization catalyst compound(s) is at least 75 wt. -%, preferably at least 90 wt. -%, based on the total weight of all catalyst compounds in the catalyst composition.

According to an embodiment, the polyisocyanate compound is selected from toluene diisocyanate, methylene diphenyl diisocyanate or a polyisocyanate composition comprising methylene diphenyl diisocyanate or a mixture of such polyisocyanates.

According to embodiments, the one or more isocyanate-reactive compounds in the reaction mixture further comprise a mono-and/or polyol having an average nominal hydroxyl functionality of 1-8 and a number average molecular weight of 200-8000 g/mol, as well as mixtures of said mono-and/or polyols, such as polyether polyols and polyester polyols, thiols, carboxylic acids such as polyacids, amines, polyamines.

According to an embodiment, the blowing agent is selected from water, isobutylene, dimethyl ether, methylene chloride, acetone, chlorofluorocarbons (CFCs), Hydrofluorocarbons (HFCs), Hydrochlorofluorocarbons (HCFCs), Hydrofluoroolefins (HFOs) and/or hydrocarbons and is present in an amount of 0.1 to 80 parts by weight (pbw), preferably 0.2 to 60pbw, calculated per hundred parts by weight of the one or more isocyanate-reactive compounds.

According to a second aspect, it is disclosed for preparing a density of 50 to 500kg/m³A process for the production of rigid foams comprising polyisocyanurate, the process having>A cream time of 35 seconds and a fast curing behaviour and comprises combining and mixing the components of the reaction mixture according to the first aspect in an isocyanate index of at least 200 to obtain a foam.

According to embodiments, the cream time is >45 seconds, more preferably >55 seconds, and the fast curing behavior is <110 seconds, preferably <90 seconds, more preferably <70 seconds.

According to an embodiment, the isocyanate index is higher than 220, preferably higher than 250.

According to a third aspect, a polyisocyanurate comprising material obtained by the process according to the second aspect is disclosed.

According to an embodiment, the polyisocyanurate comprising material according to the invention has 50 kg/m³Up to 500kg/m³Preferably 75 kg/m³Up to 300 kg/m³More preferably 100 kg/m³Up to 200 kg/m³Free rise density (measured according to ISO 845).

According to a fourth aspect, the use of a polyisocyanurate comprising material according to the invention in composite honeycomb structures is disclosed.

Particular and preferred features of the invention are set forth in the independent and dependent claims. Features from the dependent claims may be combined with features of the independent or other dependent claims as appropriate.

The above and other features, features and advantages of the present invention will become apparent from the following detailed description. The description is given for the sake of example only, without limiting the scope of the invention.

Definitions and terms

In the context of the present invention, the following terms have the following meanings:

1) "isocyanate index" or NCO index or indices:

the ratio of NCO groups present in the formulation relative to isocyanate-reactive hydrogen atoms, given as a percentage:

。

in other words, the NCO-index expresses the percentage of isocyanate actually used in the formulation with respect to the amount of isocyanate theoretically required for reacting with the amount of isocyanate-reactive hydrogen used in the formulation.

It should be observed that the isocyanate index as used herein is considered from the point of view of the actual polymerisation process for preparing the material comprising the isocyanate ingredient and the isocyanate-reactive ingredient. Any isocyanate groups consumed in the preliminary step to produce modified polyisocyanates (including those isocyanate derivatives referred to in the art as prepolymers) or any active hydrogens consumed in the preliminary step (e.g., reacted with isocyanate to produce modified polyols or polyamines) are not taken into account in the calculation of the isocyanate index. Only the free isocyanate groups and the free isocyanate-reactive hydrogens (including those of the water, if used) present at the actual polymerization stage are taken into account.

2) The expressions "isocyanate-reactive compound" and "isocyanate-reactive hydrogen atom" herein for the purpose of calculating the isocyanate index refer to the sum of the hydroxyl groups present in the isocyanate-reactive compound and the active hydrogen atoms in the amine groups; this means that for the purpose of calculating the isocyanate index in the actual polymerization process, one hydroxyl group is considered to contain one reactive hydrogen, one primary amine group is considered to contain one reactive hydrogen and one water molecule is considered to contain two active hydrogens.

3) "reaction system": a combination of compounds wherein the polyisocyanate is stored in one or more containers separate from the isocyanate reactive component.

4) The term "average nominal hydroxyl functionality" (or simply "functionality") is used herein to refer to the number average functionality (number of hydroxyl groups per molecule) of the polyol or polyol composition, assuming this is the number average functionality (number of active hydrogen atoms per molecule) of the initiator(s) used in the preparation of the polyol or polyol composition, although in practice it is generally somewhat lower due to some terminal unsaturation.

5) Unless otherwise stated, the word "average" is exponential.

6) As used herein, "trimerization catalyst" refers to a catalyst capable of catalyzing (promoting) the formation of isocyanurate groups from a polyisocyanate. This means that isocyanates can react with other isocyanates to form macromolecules with isocyanurate structures (polyisocyanurate = PIR). The reaction between isocyanate-polyol and isocyanate-isocyanate (homopolymerisation) may take place simultaneously or directly in succession, forming macromolecules with urethane and isocyanurate structures (PIR-PUR).

7) "polyisocyanurate comprising material" (foam) refers to a material composition comprising urethane and isocyanurate structures (PIR-PUR) prepared at an isocyanate index of 200 or more, more preferably at an isocyanate index higher than 220.

8) "free rise density" refers to the density measured according to ISO845 on foam samples made under atmospheric conditions (in the presence of a blowing agent).

9) "cream time" means the time required for the reaction mixture to change from a liquid state to a cream state (fresh state) and then to begin foaming (expansion).

10) "fast cure behavior" or "fast cure" refers to a reduced or minimal difference between open time and cream time. The curing time is also commonly referred to as the demold time. Tack-free time (TFT) is the period of time from the beginning of cure to the point at which the foam skin loses its tackiness. It can be determined by pressing a polyethylene film onto a surface and checking for the presence of any adhering material when the film is removed.

Detailed Description

The invention will be described with respect to specific embodiments.

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 of only components a and B. This means that for the purposes of the present invention, the only relevant components of the device are a and B.

Throughout this specification, reference is made to "one embodiment" or "an embodiment". Such references indicate that a particular feature described in connection with the embodiment is included in at least one embodiment of the invention. Thus, the 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, although they may. Furthermore, it will be apparent to one of ordinary skill in the art that the specific features or characteristics may be combined in any suitable manner in one or more embodiments.

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

The invention relates to a reaction system which enables long cream times (> 35 seconds) and fast curing (fast curing behaviour). The present invention further relates to a process for the preparation of polyisocyanurate comprising foams, more particularly for the preparation of polyisocyanurate comprising rigid foams for use in composites, such as honeycomb, whereby the reaction system of the present invention is used.

According to a first aspect of the present invention, a process for preparing a free rise density of from 50 to 500kg/m is disclosed³(according to IS)O845 measured). The reaction system comprises at least:

-a polyisocyanate composition comprising one or more polyisocyanate compounds;

-a catalyst composition comprising at least a trimerization catalyst compound in an amount of at least 50 wt. -%, based on the total weight of all catalyst compounds in the catalyst composition;

-an isocyanate reactive composition comprising at least a low MW polyol having a Molecular Weight (MW) below 200 g/mol in an amount of 0.1 up to 30 wt. -%, based on the total weight of the isocyanate reactive composition;

-one or more blowing agents comprising at least 50 mole% of water, based on the total molar amount of blowing agent;

-optionally, providing one or more surfactants, one or more flame retardants, one or more antioxidants, or a combination thereof;

wherein the wt% of the trimerisation catalyst compound is <0.5 wt% based on the total weight of the catalyst composition + polyisocyanate composition.

According to an embodiment, the wt% of the trimerization catalyst compound is <0.5 wt%, preferably <0.45 wt%, more preferably <0.4 wt%, most preferably <0.35 wt%, based on the total weight of catalyst composition + polyisocyanate composition.

According to an embodiment, the wt% of the trimerization catalyst compound is <0.30 wt% based on the total weight of catalyst composition + polyisocyanate composition.

According to an embodiment, the low Molecular Weight (MW) polyol has a molecular weight below 200 g/mol, preferably below 150 g/mol, more preferably below 100 g/mol.

One advantage of the reaction mixture of the present invention is that it can be used to achieve long cream times and short cure times involving Polyisocyanurate (PIR) formation. This combined effect results in reduced production cycle times, for example in composite applications.

According to an embodiment, the catalyst composition comprises at least a trimerization catalyst compound in an amount of at least 75 wt. -%, more preferably in an amount of at least 90 wt. -%, based on the total weight of all catalyst compounds in the catalyst composition.

According to a preferred embodiment of the first aspect of the present invention, the trimerization catalyst is selected from organic salts, preferably from organic salts of alkali metals, organic salts of alkaline earth metals and/or organic salts of quaternary ammonium. More preferably, the organic salt is selected from carboxylates or alkoxides and mixtures thereof, the carboxylate/alkoxide groups preferably having from 1 to 12 carbon atoms and mixtures thereof. Preferred examples are potassium carboxylates, sodium carboxylates, potassium alkoxides and sodium alkoxides. Carboxylates/alkoxides having a ring structure (e.g. sodium benzoate or potassium benzoate) are also suitable trimerisation catalysts. Most preferred examples are potassium acetate, potassium hexanoate, potassium ethylhexanoate, potassium octanoate, potassium lactate, ammonium N-hydroxypropyl trimethyl octanoate, ammonium N-hydroxypropyl trimethyl ammonium formate and mixtures thereof. Suitable catalysts are commercially available; examples are Catalyst LB from Huntsman or Dabco from Air Products^®K2097 (containing potassium acetate) and Dabco^®K15 (containing potassium caprylate).

According to an embodiment, the low Molecular Weight (MW) polyol having a Molecular Weight (MW) of less than 200 g/mol is present in the reaction mixture in an amount of from 0.1 up to 30 wt. -%, preferably from 1 up to 25 wt. -%, more preferably from 2 up to 20 wt. -%, based on the total weight of the isocyanate reactive composition.

According to an embodiment, the one or more isocyanate reactive compounds having a low molecular weight are selected from monoalcohols and/or polyols, such as diols. Suitable examples are monoalcohols selected from methanol, ethanol, propanol, butanol, phenol, cyclohexanol and hydrocarbon monoalcohols having a number average molecular weight of up to 200 g/mol, such as aliphatic and polyether monoalcohols, and/or polyols selected from monoethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, trimethylolpropane, sorbitol, glycerol, propylene glycol, butanediol, pentanediol, hexanediol, aromatic and/or aliphatic polyols having a molecular weight of <200, preferably <150 g/mol, more preferably <100 g/mol.

According to the factEmbodiments, the isocyanate reactive composition comprises, in addition to the low MW polyol, a high molecular weight polyol having a number average molecular weight of preferably 200-8000 and an average nominal functionality of preferably 1-8. The high molecular weight polyol may be selected from polyether polyols having an average nominal hydroxyl functionality of 1-8 and a number average molecular weight of up to 8000, polyester polyols, thiols, carboxylic acids such as polyacids, amines, polyamines and mixtures thereof. An example of a suitable polyol is Hoopol^®F-1390 (polyester polyol from Synthesis) and Daltolac^®R-166 (polyether polyol from Huntsman).

According to a second aspect of the present invention, a process for preparing a polyisocyanurate comprising foam is disclosed whereby the reaction mixture of the present invention is used. Thus, the method comprises combining and mixing the ingredients of the reaction mixture at an isocyanate index of at least greater than 200, preferably an isocyanate index of 220 or greater.

According to embodiments, the process for preparing polyisocyanurate comprising foams according to the present invention results in cream times of >35 seconds, preferably >45 seconds, more preferably >55 seconds and fast curing behavior of <110 seconds, preferably <90 seconds, more preferably <70 seconds.

There are many different sequences of contacting or combining the compounds required to make polyisocyanurate comprising foams of the present invention. One skilled in the art will recognize that it is within the scope of the present invention to vary the order of addition of the compounds.

According to an embodiment, the polyisocyanate compound used in the reaction mixture for preparing the PIR-containing foam according to the present invention is selected from organic isocyanates containing a plurality of isocyanate groups, including aliphatic isocyanates, such as hexamethylene diisocyanate; more preferably aromatic isocyanates such as m-and p-phenylene diisocyanate, toluene-2, 4-and-2, 6-diisocyanate, diphenylmethane-4, 4' -diisocyanate, chlorophenylene-2, 4-diisocyanate, naphthalene-1, 5-diisocyanate, biphenylene-4, 4' -diisocyanate, 4' -diisocyanato-3, 3' -dimethylbiphenyl, 3-methyldiphenylmethane-4, 4' -diisocyanate and diphenylether diisocyanate; 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 and triisocyanates, such as 2,4, 6-triisocyanatotoluene and 2,4,4' -triisocyanatodiphenyl ether.

According to an embodiment, the polyisocyanate composition comprises a mixture of polyisocyanates. For example, mixtures of isomers of toluene diisocyanate, such as the commercially available mixtures of 2, 4-and 2, 6-isomers, and mixtures of diisocyanates and higher polyisocyanates prepared by phosgenation of aniline/formaldehyde condensates. Such mixtures are well known in the art and include crude phosgenation products containing mixtures of methylene bridged polyphenyl polyisocyanates, including diisocyanates, triisocyanates and higher polyisocyanates as well as any phosgenation by-products.

Preferred polyisocyanate compositions of the present invention are those wherein the polyisocyanate is an aromatic diisocyanate or higher functionality polyisocyanate, especially crude mixtures of methylene bridged polyphenyl polyisocyanates containing diisocyanates, triisocyanates and higher functionality polyisocyanates. Methylene bridged polyphenyl polyisocyanates (e.g. methylene diphenyl diisocyanate, abbreviated MDI) are well known in the art and have the general formula I wherein n is 1 or greater and in the case of crude mixtures represents an average value greater than 1. They are prepared by phosgenation of the corresponding mixtures of polyamines obtained by condensation of aniline and formaldehyde.

Other suitable polyisocyanate compositions may include isocyanate-terminated prepolymers made by reacting an excess of a diisocyanate or higher functionality polyisocyanate with a hydroxyl-terminated polyester or hydroxyl-terminated polyether, as well as products obtained by reacting an excess of a diisocyanate or higher functionality polyisocyanate with a monomeric polyol or mixture of monomeric polyols, such as ethylene glycol, trimethylolpropane or butanediol. One preferred class of isocyanate-terminated prepolymers are isocyanate-terminated prepolymers comprising a crude mixture of methylene bridged polyphenyl polyisocyanates of diisocyanates, triisocyanates and higher functionality polyisocyanates.

According to an embodiment, the polyisocyanate compound in the polyisocyanate composition is selected from toluene diisocyanate, methylene diphenyl diisocyanate or a polyisocyanate composition comprising methylene diphenyl diisocyanate or a mixture of such polyisocyanates.

According to an embodiment, the isocyanate index is higher than 200, preferably higher than 220, more preferably higher than 250. For example, the isocyanate index may be 200 to 1000, 200 to 600, or 200 to 400.

The use of a reaction mixture having an isocyanate index >200 (resulting in the production of isocyanurate formulations) in, for example, composite honeycomb applications provides several advantages over reaction mixtures having an isocyanate index of about 100 (resulting in the production of polyurethane formulations). For example, the heat released is generally higher, which results in lower mold temperatures required to achieve resin cure (i.e., energy savings), the high aromatic content of the reaction mixture with an isocyanate index >200 provides better fire properties to the final composite, and the high crosslink density results in enhanced mechanical properties (higher Tg, … …).

According to embodiments, the blowing agent is preferably water, used alone or in combination with an alternative blowing agent. The alternative blowing agent may be selected from isobutylene, dimethyl ether, methylene chloride, acetone, chlorofluorocarbons (CFCs), Hydrofluorocarbons (HFCs), Hydrochlorofluorocarbons (HCFCs), Hydrofluoroolefins (HFOs) and hydrocarbons such as pentane. The amount of blowing agent used can vary depending on, for example, the intended use and application of the foam product and the desired stiffness and density of the foam. The blowing agent may be present in an amount of from 0.1 to 80 parts by weight (pbw), more preferably from 0.2 to 60pbw, per hundred parts by weight of isocyanate reactive compounds (polyols) (including the weight contribution of the catalyst composition).

According to embodiments, if desired, one or more urethane catalyst compounds may be added to the reaction mixture, although the trimerization catalyst compound should be present in an amount of >50 wt.%, based on the total weight of all catalyst compounds used. Suitable urethane catalysts for use herein include, but are not limited to, metal salt catalysts, such as organotin, and amine compounds, such as Triethylenediamine (TEDA), N-methylimidazole, 1, 2-dimethylimidazole, N-methylmorpholine, N-ethylmorpholine, triethylamine, N '-dimethylpiperazine, 1,3, 5-tris (dimethylaminopropyl) hexahydrotriazine, 2,4, 6-tris (dimethylaminomethyl) phenol, N-methyldicyclohexylamine, pentamethyldipropylenetriamine, N-methyl-N' - (2-dimethylamino) ethylpiperazine, tributylamine, pentamethyldiethylenetriamine, hexamethyltriethylenetetramine, heptamethyltetraethylenepentamine, dimethylaminocyclohexylamine, pentamethyldipropylenetriamine, organotin, and amine compounds, Triethanolamine, dimethylethanolamine, bis (dimethylaminoethyl) ether, tris (3-dimethylamino) propylamine, or acid blocked derivatives thereof, and the like, as well as any mixtures thereof.

The invention also relates to foams comprising polyisocyanurate prepared with the process according to the invention and using the reaction mixtures disclosed in the invention, and to the use of said foams in, for example, composites, such as fiber reinforced honeycomb composite structures (package trays, trunk floors, roof trims, trash trays (trays), semi-structural components … …) for fast cycle automotive applications.

According to an embodiment, the polyisocyanurate comprising material according to the invention has 50 kg/m³Up to 500kg/m³Preferably 75 kg/m³Up to 300 kg/m³More preferably 100 kg/m³Up to 200 kg/m³Free rise density (measured according to ISO 845).

According to a preferred embodiment, a composite material having a composite honeycomb structure with a core layer comprising a polyisocyanurate comprising material made according to the present invention is disclosed.

According to embodiments, the reaction mixture of the invention may be applied by spraying, for example, onto the honeycomb structure or into a mold after mixing the desired ingredients at the point of exit from the nozzle.

According to an embodiment, the polyisocyanurate comprising foams of the present invention may be used in, for example, honeycomb structures. The polyisocyanurate comprising foams of the present invention meet all the requirements to allow sufficient time for the reaction mixture to be sprayed uniformly onto the substrate (e.g. glass fiber or honeycomb assembly) and/or placed into a heated compression mold where it is then cured, while preferably a fast curing behavior to minimize cycle time.