EP2185618A1

EP2185618A1 - Process for the production of hyperbranched, dendritic polyurethanes by means of reactive extrusion

Info

Publication number: EP2185618A1
Application number: EP08787156A
Authority: EP
Inventors: Thomas Weihrauch; Stefan Bernhardt; Matthias Seiler; Kerstin Andres; Markus Schwarz; Silvia Herda
Original assignee: Evonik Degussa GmbH
Current assignee: Evonik Operations GmbH
Priority date: 2007-10-12
Filing date: 2008-08-13
Publication date: 2010-05-19
Also published as: CN101407570A; US20110065886A1; DE102007049328A1; WO2009049941A1

Abstract

The present invention relates to a process for the production of hyperbranched, dendritic polyurethanes by means of reactive extrusion.

Description

Process for the preparation of hyperbranched, dendritic polyurethanes by means of reactive extrusion

The present invention relates to a process for producing hyperbranched, dendritic polyurethanes by means of reactive extrusion.

Hyperbranched polymers are already known. C. Gao Hyperbranched polymers: from synthesis to applications Prog. Polym. Be. 29 (2004) 183-275 summarizes the current state of the art in this field and is particularly concerned with the different synthetic variants and the different fields of application of hyperbranched polymers. It is u. a. discussed the use of isophorone diisocyanate for the preparation of hyperbranched polyurethanes.

EP 1 026 185 A1 discloses a process for the preparation of dendritic or highly branched polyurethanes by reacting diisocyanates and / or polyisocyanates with compounds having at least two isocyanate-reactive groups, wherein at least one of the reactants having functional groups with respect to the other reactants of different reactivity and the Reaction conditions are chosen so that in each reaction step only certain reactive groups react with each other.

Preferred isocyanates include aliphatic isocyanates such as isophorone diisocyanate. Examples of the compounds having at least two isocyanate-reactive groups are propylene glycol, glycerol, mercaptoethanol, ethanolamine, N-methylethanolamine, diethanolamine, ethanolpropanolamine, dipropanolamine, diisopropanolamine, 2-amino-1, 3-propanediol, 2-amino-2-methyl -1, 3-propanediol and tris (hydroxymethyl) aminomethane mentioned by name. The polyurethanes obtainable by the process should serve as crosslinkers for polyurethanes or as building blocks for other polyaddition or polycondensation polymers, as phase mediators, thixotropic agents, nucleating agents or as active ingredient or catalyst carriers.

DE 100 30 869 A1 describes a process for the preparation of polyfunctional

Polyisocyanate polyaddition products comprising

(i) preparing an addition product (A) by reacting an a) isocyanate-reactive, at least trifunctional component (a1) or an isocyanate-reactive difunctional component

(a2) or with a mixture of components (a1) and (a2) with b) di- or polyisocyanate, the reaction ratio being selected so that on average the addition product (A) is an isocyanate group and more than one group reactive with isocyanate groups contains

(ii) optionally, intermolecular addition reaction of the addition product (A) to a polyaddition product (P) containing on average one isocyanate group and more than two isocyanate-reactive groups, and (iii) reacting the addition product (A) or the polyaddition product (P) with one at least difunctional, isocyanate-reactive component

(C).

As examples of the compound (a), u. a. Glycehn, trimethylolmethane and 1, 2,4-butanetriol called. A preferred diisocyanate (b) is isophorone diisocyanate.

The polyisocyanate polyaddition products obtainable by the process are proposed in particular for the production of paints, coatings, adhesives, sealants, cast elastomers and foams. WO 2004/101624 discloses the preparation of dendritic or hyperbranched polyurethanes by

1) Reaction of di- or polyols having at least one tertiary nitrogen atom and at least two hydroxyl groups having different reactivity towards isocyanate groups, with di- or polyisocyanates, such as. B.

Isophorone diisocyanate, to an addition product, wherein the di- or polyols and di- or polyisocyanates are chosen so that the addition product has on average an isocyanate group and more than one hydroxyl group or a hydroxyl group and more than one isocyanate group, 2) reaction of the addition product of step 1) to give a polyaddition product by intermolecular reaction of the hydroxyl groups with the isocyanate groups, it also being possible to react with a compound containing at least two hydroxyl groups, mercapto groups, amino groups or isocyanate groups, 3) optionally reacting the polyaddition product from step 2) with at least two hydroxyl groups, Mercapto, amino or isocyanate group-containing compound.

The polyaminourethanes obtainable by the process are used as crosslinkers for polyurethane systems or as a building block for other polyaddition or

Polycondensation polymers, as a phase mediator, as a rheology aid, as a thixotropic agent, as a nucleating reagent or as a drug or catalyst carrier proposed.

WO 02/068553 A2 describes a coating composition comprising 1) a carbamate resin with a hyperbranched or star-shaped polyol core, with a first chain piece based on a polycarboxylic acid or a polycarboxylic anhydride, with a second chain piece based on an epoxide and with carbamate groups at the core and / or the second chain piece and 2) a second resin having reactive groups that can react with the carbamate groups of the carbamate resin.

The polyol core can be prepared by reacting a first compound containing more than 2 hydroxy groups, such as. 1, 2,6-hexanetriol, with a second compound containing a carboxyl and at least two hydroxy groups.

The introduction of the carbamate groups can be achieved by reaction with aliphatic or cycloaliphatic diisocyanates. As part of a longer list here u. a. 2,2,4- and 2,4,4-trimethyl-1,6-diisocyanatohexane and isophorone diisocyanate.

WO 97/02304 relates to highly functionalized polyurethanes which are composed of molecules with the functional groups A (B) _n , where A is an NCO group or an NCO group-reactive group, B is an NCO group or one with an NCO group. Group reactive group, A is reactive with B and n is a natural number and at least equal to 2. The preparation of the monomer A (B) _n can be carried out, for example, starting from isophorone diisocyanate.

In view of this prior art, it was an object of the present invention to produce hyperbranched polyurethanes in the simplest possible way on an industrial scale.

The invention relates to a process for the solvent-free, continuous production of hyperbranched, dendritic polyurethanes obtained by solvent-free reaction of

A) at least one aromatic, aliphatic, (cyclo) aliphatic and / or cycloaliphatic polyisocyanate having at least two NCO groups and B) at least one monomeric, oligomeric and / or polymeric polyol having at least two OH groups;

C) in the presence of urethanization catalysts in a concentration of 0.01 to 3 wt .-% based on the total mass;

where other auxiliaries and additives may be included,

in an extruder, flow tube, intensive kneader, intensive mixer or static mixer by intensive mixing and short-term reaction with heat at temperatures> 25 ⁰ C and subsequent isolation of the

End product, in particular by rapid cooling.

Highly branched, globular polymers are also referred to in the literature as "dendritic polymers." These dendritic polymers synthesized from multifunctional monomers fall into two distinct categories, the "dendrimers" and the "hyperbranched polymers." Dendrimers have a very regular, radially symmetric generation structure They are monodisperse globular polymers that are synthesized in multi-step syntheses compared to hyperbranched polymers with high synthetic complexity, characterized by three distinct areas: - the polyfunctional core, which is the center of symmetry, - various well-defined radial-symmetric layers In contrast to the dendrimers, the hyperbranched polymers are polydisperse and irregular in their branching and structure In contrast to dendrimers, in hyperbranched polymers both the tritic and terminal units also have linear units. In each case an example of a dendrimer and a highly branched polymer, constructed from repeating units which each have at least three bonding possibilities, is shown in the following structures:

Dendrimer hyperbranched polymer

With regard to the different possibilities for synthesizing dendrimers and hyperbranched polymers, reference may be made in particular to a) Frechet J.M.J., Tomalia D.A. "Dendrimers And Other Dendritic Polymers" John Wiley & Sons, Ltd., West Sussex, UK 2001; and b) Jikei M., Kakimoto M. "Hyperbranched Polymers: A Promising New Class Of Materials" Prog. Polym. Sci., 26 (2001) 1233-1285 and / or c) Gao C, Yan D. "Hyperbranched Polymers: From Synthesis To Applications" Prog. Polym. See., 29 (2004) 183-275, hereby incorporated by reference and are considered part of the disclosure of the present invention.

Starting materials for the polyisocanates A: In principle, all known compounds are suitable as aromatic di- or polyisocyanates. Particularly suitable are 1, 3 and 1, 4-phenylene diisocyanate, 1, 5-naphthylene diisocyanate, tolidine diisocyanate, 2,6-toluene diisocyanate, 2,4-tolylene diisocyanate (2,4-TDI), 2,4'-diphenylmethane diisocyanate (2,4'-MDI), 4,4'-diphenylmethane diisocyanate, the mixtures of monomeric diphenylmethane diisocyanates (MDI) and oligomeric diphenylmethane diisocyanates (polymer-MDI), xylylene diisocyanate, tetramethylxylylene diisocyanate and triisocyanatotoluene.

Suitable aliphatic di- or polyisocyanates advantageously have 3 to 16 carbon atoms, preferably 4 to 12 carbon atoms, in the linear or branched alkylene radical and suitable cycloaliphatic or (cyclo) aliphatic diisocyanates advantageously 4 to 18 carbon atoms, preferably 6 to 15 carbon atoms, in the cycloalkylene radical. Under (cyclo) aliphatic diisocyanates, the skilled worker understands at the same time cyclic and aliphatic bound NCO groups, as z. B. isophorone diisocyanate is the case. In contrast, is meant by cycloaliphatic diisocyanates those which have only directly attached to the cycloaliphatic ring NCO groups, for. B. H ₁₂ MDI. Examples are cyclohexane diisocyanate, methylcyclohexane diisocyanate, ethylcyclohexane diisocyanate, propylcyclohexane diisocyanate, methyldiethylcyclohexane diisocyanate.

Preference is given to isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), diisocyanatodicyclohexylmethane (H12MDI), 2-methylpentane diisocyanate (MPDI), 2,2,4-trimethylhexamethylene diisocyanate / 2,4,4-trimethylhexamethylene diisocyanate (TMDI), norbornane diisocyanate (NBDI ). Very particular preference is given to using IPDI, HDI, TMDI and H ₁₂ MDI, the isocyanurates and uretdiones also being usable.

Also suitable are 4-methylcyclohexane-1, 3-diisocyanate, 2-butyl-2-ethylpentamethylene diisocyanate, 3 (4) -lsocyanatomethyl-1-methylcyclohexylisocyanate, 2-isocyanatopropylcyclohexylisocyanate, 2,4'-methylene-bis (cyclohexyl) diisocyanate , 1, 4-diisocyanato-4-methyl-pentane. Of course, mixtures of di- and polyisocyanates, isocyanurates and uretdiones can be used.

Furthermore, preference is given to using oligoisocyanates or polyisocyanates which are prepared from the abovementioned diisocyanates or polyisocyanates or mixtures thereof by linking by means of urethane, allophanate, urea, biuret, uretdione, amide, isocyanurate, carbodiimide, uretonimine , Oxadiazinthon- or iminooxadiazinedione structures. Particularly suitable are isocyanurates, especially from IPDI and HDI.

Suitable compounds B) are all polyols commonly used in PU chemistry, which have at least two alcohol groups of the

Molecular weight of at least 32 g / mol. The monomeric diols are, for example, ethylene glycol,

Triethylene glycol, butanediol-1, 4, pentanediol-1, 5, hexanediol-1, 6, 3-methylpentanediol

1, 5, neopentyl glycol, 2,2,4 (2,4,4) -thmethylhexanediol and

Hydroxypivalate.

The monomeric triols are, for example, trimethylolpropane, dithmethylolpropane, trimethylolethane, hexanthol-1, 2,6, butantol-1, 2,4, tris (β-)

Hydroxyethyl) isocyanurate, pentaerythritol, mannitol or sorbitol.

Also suitable are polyols which contain further functional groups (oligomers or polymers). These are the hydroxyl-containing polyesters, polycarbonates, polycaprolactones, polyethers, polythioethers, polyesteramides, polyurethanes or polyacetals known per se. They have a number average molecular weight of 134 to 3,500 g / mol. The polyols are used alone or in mixtures. The catalysts C) are urethanization catalysts, such as organic tin compounds of the following composition RnSnXm (II), in which R = alkyl radical having 1 to 10 carbon atoms and X = carboxylate radical of a carboxylic acid having 1 to 20 carbon atoms and n = 1 , 2 or 3, m = 1, 2 or 3 and n + m = 4. But also zinc catalysts, such as in particular, for example, zinc 2-ethylhexanolat in butyldiglycol, zinc salts of branched and unbranched fatty acids (C2 - C20), or bismuth catalysts, such as bismuth thneodecanoate in neodecanoic acid. They are used in a concentration of 0.01 to 3 wt .-%.

Especially suitable are catalysts such as butyltin tris (2-ethylhexanoate) and dibutyltin dilaurate.

As auxiliaries and additives z. As monofunctional isocyanates, chain terminators, blocking agents, chain extenders, degassing agents, stabilizers, other catalysts, flow control agents, inorganic and / or organic pigments and / or fillers, dispersants, wetting agents, defoamers, ionic liquids may be included.

The hyperbranched polyurethane prepared according to the invention preferably has a weight-average molecular weight Mw in the range from 1000 g / mol to 200000 g / mol, favorably in the range from 1500 g / mol to 100000 g / mol, particularly preferably in the range from 2000 g / mol to 75000 g / mol, in particular in the range of 2500 g / mol to 50,000 g / mol.

The determination of the molecular weight, in particular the determination of the weight average molecular weight Mw and the number average molecular weight, can in known manner, for. Example, be measured by gel permeation chromatography (GPC), wherein the measurement is preferably carried out in DMF and as a reference preferred polyethylene glycols Burgath et al in Macromol Chem. Phys., 201 (2000) 782-791). In this case, a calibration curve is advantageously used, which was conveniently obtained using polystyrene standards. These quantities therefore represent apparent measured values.

Alternatively, the number average molecular weight can also be determined by steam or membrane osmosis, the z. In K.F. Arndt; G. Müller; Polymer characterization; Hanser Verlag 1996 (steam pressure osmosis) and H. -G. Elias, macromolecules structure synthesis properties, Hütig & Wepf Verlag 1990 (membrane osmosis) are described in more detail. The GPC, however, has proven to be particularly useful according to the invention.

The polydispersity Mw / Mn of preferred hyperbranched polyurethanes is preferably in the range of 1 to 50, favorably in the range of 1, 1 to 40, in particular in the range of 1, 2 to 20, preferably to 10.

The principle of the process is that the reaction of the starting compounds is carried out continuously, in particular in an extruder, flow tube, intensive kneader, intensive mixer or static mixer by intensive mixing and short-term reaction with heat. This means that the residence time of the starting materials in the abovementioned aggregates is usually 3 seconds to 15 minutes, preferably 3 seconds to 5 minutes, particularly preferably 5 to 180 seconds. The reactants are briefly reacted with heat at temperatures of 25 ⁰ C to 325 ⁰ C, preferably from 50 to 250 ⁰ C, most preferably from 50 to 200 ⁰ C reacted. However, depending on the nature of the feedstocks and the end products, these residence time and temperature values may also occupy other preferred ranges. Optionally, a continuous after-reaction is followed. By subsequent rapid cooling, it is then possible to obtain the desired end product. As aggregates, extruders such as single- or multi-screw extruders, in particular twin-screw extruders, planetary roller extruders or ring extruders, flow tubes, intensive kneaders, intensive mixers or static mixers are particularly suitable for the process according to the invention and are preferably used.

Since the cooling of the products may be very important for the molecular design, it may be necessary to change the extruders in the head area, or to use certain nozzle structures. Often it is necessary here to allow a particularly gentle product discharge. This can for example be driven without a top plate.

The starting compounds are added to the aggregates usually in separate product streams. If there are more than two product streams, these can also be bundled. Various hydroxyl-containing starting materials can be combined to form a product stream. It is also possible to additionally add catalysts and / or additives such as leveling agents or stabilizers to this product stream. It is likewise possible to combine polyisocyanates and the uretdiones of polyisocyanates with catalysts and / or additives such as leveling agents or stabilizers in a product stream. The material flows can also be divided and thus supplied to the units in different proportions at different locations. In this way, concentration gradients are set deliberately, which can bring about the completeness of the reaction. The entry point of the product streams in the order can be handled variable and time offset. As a result, the structure of the target molecules can be varied.

For pre-reaction and / or completion of the reaction several aggregates can also be combined. The downstream of the reaction preferably rapid cooling may be integrated in the reaction part, in the form of a multi-housing embodiment as in extruders or Conterna machines. The following can also be used: tube bundles, pipe coils, cooling rolls, cooled chutes, air conveyors, metal conveyor belts and water baths, with and without a downstream granulator.

Depending on the viscosity of the product leaving the intensive kneader or the post-reaction zone, the preparation is first brought to a suitable temperature by further cooling by means of the corresponding aforementioned equipment. Then, the pastillation or crushing into a desired particle size by means of roll crusher, pin mill, hammer mill, shingles, strand granulator (eg., In combination with a cooling medium), other granulators or the like.

Hereinafter, the object of the invention will be explained by way of example.

Example 1: Preparation of a hyperbranched, dendritic polyurethane by the process according to the invention

It was worked with three streams: stream 1 consisted of 1, 2,6-hexanetriol. Stream 2 isophorone diisocyanate (IPDI). Stream 3 consisted of the catalyst DBTL. The total amount, relative to the

Total formulation was 0.025%.

Stream 1 was fed as melt at a rate of 630 g / h in the first housing of a twin-screw extruder (DSE 25) (temperature of the stream 25 ⁰ C).

Stream 2 was fed into the following housing at a rate of 2510 g / h

(Temperature of the stream 25 ⁰ C).

Stream 3 was introduced before entering the extruder in stream 2 via a static mixer section (0.78 g / h). The extruder used consisted of 8 housings which could be heated and cooled separately. Housing 1, 2 and 3: 20 - 30 ° C, housing 4: 25-35 ⁰ C, housing 5:

55 - 65 ⁰ C, housing 6 and 7: 150 - 165 ⁰ C, housing 8: 100 - 105 ⁰ C.

The snails were equipped with conveying elements.

All temperatures represented nominal temperatures. The regulation took place via electric heating or water cooling. It was driven without extruder head. The

Screw speed was 250 rpm. The reaction product was immediately cooled after exiting the extruder and discharged on a cooling belt and then ground. It had a content of free NCO groups of 12.1%.

Claims

claims:

1. A process for the solvent-free, continuous production of hyperbranched, dendritic polyurethanes obtained by solvent-free reaction of

A) at least one aromatic, aliphatic, (cyclo) aliphatic and / or cycloaliphatic polyisocyanate having at least two NCO-

Groups and B) at least one monomeric, oligomeric and / or polymeric polyol having at least two OH groups; C) in the presence of urethanization catalysts in a concentration of

0.01 to 3 wt .-% based on the total mass;

where other auxiliaries and additives may be included,

in an extruder, flow tube, intensive kneader, intensive mixer or static mixer by intensive mixing and brief reaction with heat at temperatures> 25 ⁰ C and subsequent isolation of the final product, in particular by rapid cooling.

2. The method according to claim 1, characterized in that the residence time of the starting materials is 3 seconds to 15 minutes.

3. The method according to at least one of the preceding claims, characterized in that the reaction takes place in one, two or more screw extruder, ring extruder or planetary roller extruder.

4. The method according to claim 3, characterized in that the reaction takes place in a twin-screw extruder.

5. The method according to claim 1 to 2, characterized in that the reaction is carried out in a multi-shaft extruder, such as a ring extruder, or a planetary roller extruder.

6. The method according to any one of claims 1 to 2, characterized in that the reaction takes place in a flow tube, intensive mixer or intensive kneader.

7. The method according to any one of claims 1 to 2, characterized in that the reaction takes place in a static mixer.

8. The method according to at least one of the preceding claims, characterized in that the reaction in an extruder, intensive kneader, intensive mixer or static mixer with several identical or different housings, which can be thermally controlled independently, takes place.

9. The method according to at least one of the preceding claims, characterized in that the temperature in the extruder, intensive kneader, intensive mixer or static mixer> 25 to 325 ⁰ C.

10. The method according to at least one of the preceding claims, characterized that the extruder or intensive kneader by appropriate placement of the mixing chambers and compilation of the screw geometry on the one hand lead to an intensive rapid mixing and rapid reaction with simultaneous intensive heat exchange, and on the other hand a uniform flow in the longitudinal direction with as uniform as possible

Effect residence time. In addition, the extruder end must be such that a rapid cooling of the exiting product is possible.

11. The method according to at least one of the preceding claims, characterized in that the starting materials and / or

Catalysts and / or aggregates are fed together or in separate product streams, in liquid or solid form, the extruder, flow tube, intensive kneader, intensive mixer or static mixer.

12. The method according to at least one of the preceding claims, characterized in that the aggregates are combined together with the starting materials to form a product stream.

13. The method according to at least one of the preceding claims, characterized in that as component A) isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), diisocyanatodicylcohexylmethane (H ₁₂ MDI) 2-methylpentane diisocyanate

(MPDI), 2,2,4-trimethylhexamethylene diisocyanate / 2,4,4-trimethylhexamethylene diisocyanate (TMDI), norbornane diisocyanate (NBDI), toluene diisocyanate (TDI), methylene diphenyl diisocyanate (MDI) and / or tetramethylxylylene diisocyanate (TMXDI) is used.

14. The method according to at least one of the preceding claims, characterized in that IPDI, HDI and / or H ₁₂ MDI is used as component A).

15. The method according to at least one of the preceding claims, characterized in that as component A) 4-methyl-cyclohexane-1, 3-diisocyanate, 2-butyl-2-ethylpentamethylenediisocyanat, 3 (4) -lsocyanatomethyl-1 - methylcyclohexylisocyanat, 2nd -isocyanatopropylcyclohexylisocyanate, 2,4'-methylene-bis (cyclohexyl) diisocyanate, 1, 4-diisocyanato-4-methyl-pentane are used.

16. The method according to at least one of the preceding claims, characterized in that component A) is selected from an aromatic, aliphatic, cycloaliphatic or (cyclo) aliphatic di- or polyisocyanate alone or in mixtures and / or urethane, allophanate, urea -, Biuret, uretdione, amide, isocyanurate, carbodiimide, uretonimine, oxadiazinethone or Iminooxadiazindion structures having oligo- and / or polyisocyanate.

17. The method according to at least one of the preceding claims, characterized in that isocyanurates, biurets and / or allophanates are used as component A).

18. The method according to at least one of the preceding claims, characterized in that are used as component A) isocyanurates, in particular of IPDI and HDI.

19. Hyperbranched, dendritic polyurethane according to at least one of the preceding claims, characterized in that as polyols B) ethylene glycol, triethylene glycol, butanediol-1, 4, pentanediol 1, 5, hexanediol-1, 6,3-methylpentanediol-1, 5th , Neopentyl glycol, 2,2,4 (2,4,4) -

Trimethylhexanediol, hydroxypivalic acid neopentyl glycol ester, trimethylolpropane, dithmethylolpropane, trimethylolethane, hexanetriol-1, 2,6, butanetriol-1, 2,4-tris (β-hydroxyethyl) isocyanurate, pentaerythritol, mannitol, sorbitol, hydroxyl-containing polyesters, polycarbonates, polycaprolactones, polyethers, polythioethers , Polyesteramides, polyurethanes and / or polyacetals, alone or in

Mixtures used.

20. The method according to at least one of the preceding claims, characterized in that as catalysts C) organic tin compounds of the composition

R _n SnX _m in which R = alkyl radical having 1 to 10 carbon atoms and X = carboxylate radical of a carboxylic acid having 1 to 20 carbon atoms and n = 1, 2 or 3, m = 1, 2 or 3 and n + m = 4,

be used.

21. The method according to at least one of the preceding claims, characterized in that zinc catalysts, in particular zinc 2-ethylhexanolat in

Butyl diglycol, zinc salts of branched and unbranched fatty acids (C2 - C20), or bismuth catalysts, in particular bismuth thneodecanoate in neodecanoic acid, are used.

22. The method according to at least one of the preceding claims, characterized in that as catalysts C) butyltin tris (2-ethylhexanoate) and / or

Dibutyltin dilaurate can be used.

23. The method according to at least one of the preceding claims with a

Weight average molecular weight in the range of 1000 to 200,000 g / mol.