WO1997045399A1

WO1997045399A1 - Method for treating polyisocyanate, resulting product, and use of same for the production of oligomers or polymers, and compositions thus obtained.

Info

Publication number: WO1997045399A1
Application number: PCT/FR1997/000928
Authority: WO
Inventors: Jean-Marie Bernard; Denis Revelant
Original assignee: Rhodia Chimie
Priority date: 1996-05-31
Filing date: 1997-05-28
Publication date: 1997-12-04
Also published as: AU3096797A; FR2749302A1

Abstract

The invention discloses a product useful as monomer. This product is characterised in that when it is subjected to the action of an amount of phosphine of 0.005 mol per isocyanate function equivalent for one and a half hours at a temperature of 40 to 60 °C, it develops staining of less than 50 Hazen units, advantageously 30 Hazen units. The invention is useful in organic synthesis.

Description

PROCESS FOR TREATING POLYISOCYANATE, PRODUCT OBTAINED, AND

USE OF THIS PRODUCT FOR THE MANUFACTURE OF OLIGO- OR

POLY-MERES, AND COMPOSITIONS THUS OBTAINED

The subject of the present invention is a process for treating polyisocyanates, the product thus obtained, the use of the latter for the manufacture of oligo- or polymers, as well as the compositions thus obtained. It relates more particularly to the pretreatment of the monomeric polyisocyanates in order to avoid them all or part of the risks of untimely coloring during subsequent treatments.

In order to better understand the invention, it seemed appropriate to recall certain aspects of the polyurethane and polyisocyanate industry.

The raw materials generally consist of a hydrocarbon skeleton, most often purely hydrocarbon, and of several isocyanate functions, in general two. These compounds are often referred to as monomers. They are rarely used as is.

In general, a precondensation is carried out under the action of a compound having at least one mobile hydrogen function (For example water in the case of biuret, polyols or polyamines) or a prepolymerization (For example dimerization or oligomerization as in the case of the formation of isocyanuric rings).

It is the compositions resulting from the above operations, which are used most frequently.

The above compositions, which have not exhausted their isocyanate functions, whether or not they are masked, are subjected to condensation with a compound comprising several reactive hydrogen functions, in general polyols or polyamines. The characteristics of the final product (glue, coating, ...) can be modified by curing by cooking.

During these various operations, an unpleasant coloring can develop. Among the operations which most certainly lead to the development of these regrettable colorations, it is worth mentioning the so-called "dimerization" operation which especially when it is catalyzed by phosphorus derivatives where the phosphorus is trivalent, develops colorations tending to yellow worst effect for some applications.

It is because of this paroxysmal effect of dimerization that it was chosen as the touchstone of the techniques studied during the research which led to the present invention.

This is the reason why, after dimerization, various bleaching operations are carried out using the techniques often tried in chemistry, but which do not always give the expected results. Among the most widely used techniques, mention may be made of "dimer" treatments by destruction of the colored derivatives by means of various peroxides.

However on the one hand this technique only imperfectly solves the problem posed and on the other hand it only alleviates the problem of dimerization.

This is why one of the aims of the present invention is to provide a monomer product which makes it possible to avoid these untimely coloring.

Another object of the present invention is to provide a product of the above type which leads to prepolymers or precondensates which are neither chromatophoric nor chromogenic.

Another object of the present invention is to provide a product of the above type which does not inhibit the prepolymerization or precondensation reactions.

Another object of the present invention is to provide a product of the preceding type which does not involve a too heavy or too thorough purification operation.

Another object of the present invention is to provide a product of the above type which tolerates a level of impurities which is not too low. For example which can contain less than 0.1 to 0.3% or even up to 0.5% without being too chromatophores or chromogenic. These aims and others which will appear subsequently are achieved by means of a product carrying isocyanate functions (hereinafter referred to as polyisocyanates) which, when it is subjected to the action of an equal amount of phosphine at 0.005 mole per equivalent of isocyanate function for one hour and a half and at a temperature between 40 and 60 ° C., develops a coloration less than 50 Hazen advantageously than 30 Hazen.

The most sensitive phosphine for determination is tributylphosphine.

The present invention is particularly advantageous when said isocyanate is a monomeric isocyanate.

The present invention relates more particularly to polyisocyanates which statistically have at most four isocyanate functions.

When the present invention relates to pure compounds, said polyisocyanate has at least two isocyanate functions, whereas when the present invention relates to mixtures, as is sometimes the case, said polyisocyanate statistically has at least one and a half isocyanate function.

The present invention is particularly effective when the coloring problems set out above relate to polyisocyanates which comprise at least one isocyanate function attached to an aliphatic carbon, that is to say a sp3 hybridization carbon.

Advantageously, said aliphatic carbon (that is to say a sp3 hybridization carbon) to which said isocyanate function is attached carries at least one hydrogen atom, advantageously two. Advantageously, this same carbon carries at least one aliphatic carbon (that is to say sp3 hybridization) itself also carrying at least one hydrogen atom.

In other words, said aliphatic carbon, that is to say a sp3 hybridization carbon, to which said isocyanate function is attached, is not of the neopentyl type.

What has just been explained above is explained below. Thus according to the invention the polyisocyanate, having at least about two isocyanate functions, advantageously more than two, (with the possibility of fractional values in the case of a mixture of more or less condensed oligomers which are themselves most often derived from precondensation or prepolymerization of unit diisocyanate) generally has an average molecular mass at most equal to approximately 2000 (in the present description the term "approximately" is used to emphasize the fact that, when the , or the rightmost digits of a number are zeros, these zeros are position zeros and not significant digits, except of course if specified otherwise), more commonly around 1000 (preferably two significant figures).

The preferred polyisocyanates are those which have at least one aliphatic isocyanate function. In other words at least one free isocyanate function is linked to the skeleton via a sp3 type carbon advantageously carrying a hydrogen atom, preferably two; which sp3 type carbon is advantageously itself bound to at least aliphatic carbon (that is to say sp3 hybridization) itself also carrying at least one hydrogen atom.

Among the most targeted polyisocyanates, mention should be made of polymethylenediisocyanates. And more particularly hexamethylene diisocyanate.

Given the treatment necessary to obtain the product according to the present invention, it is desirable that it comprises at least one ketone content at least equal to 25, advantageously 50 ppm. According to a particularly advantageous implementation of the present invention, said ketone contains from 3 to 15 carbon atoms, advantageously at most 10, preferably with 8 carbon atoms.

Most often said ketone has 3 to 6 carbon atoms. Another object of the present invention is to provide a process of the above type which makes it possible to obtain a non-coloring isocyanate in the presence of trialkyl phosphine.

This isocyanate treatment method comprises step b) of bringing an isocyanate having 0.05 to 0.5% of impurity (s) into contact with a compound having at least one peroxide function (-OO- ).

Advantageously, said compound having at least one hydro-peroxide (-O-O-H) function.

It is even particularly interesting that said compound has two peroxide functions including at least one hydroperoxide function (-O-O-H).

Among the compounds having at least one peroxide function, it is more particularly appropriate to cite the derivatives, symmetrical or not (with respect to a peroxide function), whose formula (which does not imply anything in terms of production processes) derives formally replacing oxygen from a carbonyl function with two peroxide functions, one of which is advantageously a hydroperoxide function).

The compound known as butanone peroxide [(MeHEt) C (O-O- H) -O-J2 gives particularly good results.

The contacting of said polyisocyanate with the compound comprising at least one peroxide function is carried out at a temperature at least equal to the ambient, advantageously at 30 ° C., preferably at 40 ° C.

With regard to the upper temperature limit, it is desirable that the contacting of said compound comprising at least one peroxide function is carried out at a temperature at most equal to approximately 100 ° C., advantageously at 90 ° C., preferably at 80 ° C

This bringing into contact (or this reaction time) of said compound comprising at least one peroxide function is carried out at a temperature at least equal to 40 ° C. for a period at least equal to a quarter of an hour, advantageously at least equal to a half hour, preferably at least one hour. Furthermore, bringing said compound comprising at least one peroxide function at a temperature above the ambient temperature lasts for at most half a day, advantageously at most to a quarter of days, preferably at most to an eighth of a day. As regards the quantity of said compound comprising at least one peroxide function, introduced into said polyisocyanate, it is at least equal to 0.01% expressed in moles relative to the equivalent of isocyanate function.

In addition, it is desirable that the quantity of said compound comprising at least one peroxide function, introduced into said polyisocyanate is at most equal to 1%, advantageously at most 0.5%, preferably at most 0.2 mol% relative to the equivalent of isocyanate function.

Before stage b), it is desirable to carry out stage a) of distillation (to be specified) making it possible to reach a content of impurity (s) of between 0.05 and 0.5% advantageously between 0, 1 and 0.3%.

Another object of the present invention is to provide a use of the above type leading to prepolymers or oligomers of little color.

The reaction leading to oligomers (in particular to dimers) is carried out by catalysis using organic base. Said organic base is a pnictine.

Among the said organic bases of the elements of column V, the preferred ones are those derived from hydrogen pnictures by partial or preferably total substitution of hydrogen by hydrocarbon residues which can be linked to the atom of column VB by a double (as in imines or pyridine), or even a triple bond (as in nitriles).

However, the hydrocarbon derivatives of the elements of column V are advantageously derived from hydrogen pnictures by total or partial substitution of hydrogen by monovalent hydrocarbon residues advantageously by alkyls [in the present description ALco-y / e is taken in its sense etymological of hydrocarbon residue of an ALCO-OZ after ignorance of the alcohol (or ol) function]; these alkyl compounds will, by analogy with the term pnicture, designated in the present description, under the term of pnictines.

Thus in the case of nitrogen the substitution of hydrogen nitride (ammonia) gives the amines, in the case of phosphorus the substitution of hydrogen phosphide gives the phosphines, in the case of arsenic the substitution of hydrogen arsenide gives the arsines and in the case of antimony the substitution of the hydrogen antimoniide (or stibiure) gives the stibnids. The organic bases are advantageously chosen from hydrocarbon derivatives of phosphorus such as phosphines.

One of the many advantages of the new polyisocyanates according to the invention is that they can serve as a basis for the preparation of polymers and / or cross-linkings which are useful, for example, as main constituents of coatings of all kinds, such as paints or varnishes. . In such uses, the hardness qualities of the crosslinkable polymers are among those which are sought from a technical and functional point of view.

The above preparation of polymers consists of:

- Putting the polyisocyanates and especially their oligomers in accordance with the invention (I) in the presence of a reagent of formula R ^a OH and / or R ^D NH2 with

R ^a and R ^D representing aliphatic, alicyclic or aromatic hydrocarbon groups, preferably alkyls, cycloalkyls, aryls, aralkyls, alkenyls, aralkenyls, linear or branched, substituted or unsubstituted

- And to heat the reaction medium thus formed at a temperature less than or equal to 150 ° C, preferably between 80 and 140 ° C and, more preferably still, between 110 and 130 ° C and this, for a duration less than or equal at 3 p.m., preferably at 10 a.m. and, more preferably still, at 8 a.m.

To meet industrial imperatives of economy and profitability, it is important to take into account this reaction time parameter by approaching the right temperature / time compromise as well as possible.

Advantageously, provision is made to include an organic solvent in the reaction medium. This solvent is preferably non-polar and of dielectric constant, preferably greater than or equal to 4 and, more preferably still, to 5.

According to the invention, the preferred non-polar solvents are, inter alia, benzene, chlorobenzene (1,2-dichlorobenzene), nitrobenzene, cyclohexanone, methyl ethyl ketone and acetone.

As regards the co-reactant, generally polyfunctional, R ^a OH or R ^b NH2 which can be mono-, oligo- or polymeric, used for the preparation of optionally crosslinked polyurethanes, its choice will be dictated by the functionalities expected for the polymer the final application. These co-reactants are generally well known to those skilled in the art.

R ^a OH and / or R & NH2 represent polyfunctional β aliphatic, alicyclic or aromatic, preferably alkyl, cycloalkyl, aryl, aralkyl, alkenyl, aralkenyl, linear or branched, substituted or unsubstituted entities.

These co-reactants are naturally mono- or polyfunctional and can thus give access to various polymer skeletons.

The invention therefore also relates to paint compositions comprising, for successive or simultaneous additions: a masked polyisocyanate according to the invention; • a reagent (R ^a OH and / or R ^b NH2 and possible catalysts), as described above;

• possible catalysts;

• optionally at least one pigment;

• optionally an aqueous phase; • optionally a surfactant to keep the constituent components of the mixture in emulsion or in suspension;

• optionally an organic solvent;

The invention also relates to the paints and varnishes obtained by the use of these compositions.

The following nonlimiting examples illustrate the invention. Dimerization tests for hexamethylene diisocyanate - Pretreatment of hexamethylene diisocyanate with butanone peroxide

Procedure

In a stirred one liter reactor equipped with a condenser and a temperature probe, 500 g of hexamethylene diisocyanate are introduced;

250 mg butanone peroxide [(Me) (Et) C (O-O-H) -O-] 2-

The mixture is heated and stirred, then when the desired temperature is reached, after 20 minutes of maintaining at the tested temperature, 2.5 g of tributylphosphine are introduced.

The temperature and the stirring are maintained for 1 hour and a quarter, then 1.7 g of methyl sulphate is introduced to inhibit the action of tributylphosphine (1.1 mol / mol of BU3P).

The mixture is then cooled to room temperature (_20 ° C).

The product obtained, the coloration of which is less than 20 Hazen, is subjected three times to the action of a scraped film evaporator (160 ° C.-1 mm of mercury) to remove the unreacted HDI.

At the end of the third pass, a mixture containing substantially 55% by mass of hexamethylene diisocyanate dimer is recovered, the coloration of which is then evaluated. The summary table below brings together the results obtained with regard to the operating conditions.

Claims

1. Polyisocyanate useful as a monomer, characterized in that, when subjected to the action of an amount of phosphine equal to 0.005 mole per equivalent of isocyanate function for one and a half hours and at a temperature between 40 and 60 ° C, it develops a coloration of less than 50 Hazen advantageously than 30 Hazen.

2. Polyisocyanate according to claim 1, characterized in that said isocyanate is a monomeric isocyanate.

3. Polyisocyanate according to claims 1 and 2, characterized in that said polyisocyanate statistically has at most four isocyanate functions.

4. Polyisocyanate according to claims 1 to 3, characterized in that said polyisocyanate statistically has at least one and a half isocyanate function.

5. Polyisocyanate according to claims 1 to 4, characterized in that comprises at least one isocyanate function attached to an aliphatic carbon, that is to say a sp3 hybridization carbon.

6. Polyisocyanate according to claims 1 to 5, characterized in that comprises at least one isocyanate function attached to an aliphatic carbon, that is to say a sp3 hybridization carbon, said aliphatic carbon carrying at least one atom d hydrogen, advantageously two.

7. Polyisocyanate according to claims 1 to 6, characterized in that it comprises at least one isocyanate function attached to an aliphatic carbon, that is to say a sp3 hybridization carbon, said aliphatic carbon carrying at least one hydrogen atom, advantageously two, not being of the όopentyl type.

8. Polyisocyanate according to claims 1 to 7, characterized in that comprises at least one isocyanate function attached to an aliphatic carbon, said aliphatic carbon carrying at least one hydrogen atom, advantageously two, is itself linked to at least an aliphatic carbon carrying at least one hydrogen atom.

9. Polyisocyanate according to claims 1 to 8, characterized in that it comprises a ketone content at least equal to 25, advantageously at 50 ppm.

10. Polyisocyanate according to claim 9, characterized in that said ketone contains from 3 to 15 carbon atoms advantageously at most 10, preferably 8 carbon atoms.

11. Polyisocyanate according to claims 9 and 10, characterized in that said ketone has from 3 to 6 carbon atoms.

12. Isocyanate treatment method, characterized in that it comprises step b) bringing me into contact with an isocyanate having 0.05 to 0.5% of impurity (s) with a compound having at least one peroxide function (-O- O-).

13. Method according to claims 11 to 12, characterized in that said compound having at least one hydroperoxide function (-OOH).

14. Method according to claims 11 to 13, characterized in that said compound having two peroxide functions including at least one hydroperoxide function (-O-O-H).

15. Method according to claims 11 to 14, characterized in that said compound having at least one peroxide function is a symmetrical derivative or not (with respect to a peroxide function) formally derived from the replacement of oxygen for a carbonyl function by two peroxide functions, one of which advantageously is a hydroperoxide function.

16. Method according to claims 11 to 15, characterized in that said compound having at least one peroxide functions is the compound known as butanone peroxide [(Me) (Et) C (OOH) -O-] 2 .

17. Method according to claims 11 to 16, characterized in that the contacting of said compound comprising at least one peroxide function is carried out at a temperature at least equal to the ambient, advantageously at 30 ° C, preferably at 40 ° vs.

18. Method according to claims 11 to 17, characterized in that the contacting of said compound comprising at least one peroxide function is carried out at a temperature at most equal to approximately 100 ° C, advantageously at 90 ° C, preferably at 80 ° C.

19. The method of claims 11 to 18, characterized in that the contacting of said compound comprising at least one peroxide function is carried out at a temperature at least equal to 40 ° C for a duration at least equal to a quarter of hour, advantageously at least equal to half an hour, preferably at least equal to one hour.

20. Method according to claims 11 to 19, characterized in that bringing said compound into contact comprising at least one peroxide function to a temperature above ambient lasts for at most half a day, advantageously at most to a quarter of days, preferably at most to an eighth of a day.

21. Method according to claims 11 to 20, characterized in that the quantity of said compound comprising at least one peroxide function, introduced into said polyisocyanate is at least equal to 0.01 mol% relative to the equivalent of isocyanate function.

22. Method according to claims 11 to 21, characterized in that the quantity of the said compound comprising at least one peroxide function, introduced into the said polyisocyanate is at most equal to 0.25%, advantageously at most 0.1%, preferably at most 0.05 mol% relative to the equivalent of isocyanate function.

23. Method according to claims 11 to 22, characterized in that before step b) stage a) of distillation is carried out, making it possible to reach an impurity content (s) of between 0.05 and 0 , 5% advantageously between 0.1 and 0.3%.

24. Use of the compounds according to claim 1 for producing oligomers and prepolymers according to claim 23, characterized in that.

25. Use according to claim 24, characterized in that the reaction of the oligomers is carried out by catalysis using organic base.

26. Use according to claims 24 and 25, characterized in that said organic base is a pnictine advantageously a phosphine.

27. Use according to claims 24 to 26, characterized in that said organic base has at least one tertiary phosphine function where at least one preferably at least two of the three substituents are alkyl substituents, including aralkyls.

28. Use of the oligomers and prepolymers obtained according to one of claims 24 to 27 for producing coatings including paints and varnishes according to claim.

29. Coating obtainable according to claim 28 according to claim.