EP0507790A1

EP0507790A1 - Process for preparing crosslinked polymers

Info

Publication number: EP0507790A1
Application number: EP19910900773
Authority: EP
Inventors: Brigitte Hase; William E. Fristad; Ulrich Dr. Eicken
Original assignee: Henkel AG and Co KGaA
Current assignee: Henkel AG and Co KGaA
Priority date: 1989-12-27
Filing date: 1990-12-17
Publication date: 1992-10-14
Also published as: DE3943111A1; JPH05502685A; WO1991009897A3; WO1991009897A2

Abstract

Pour la fabrication des nouveaux polymères, on fait réagir des poly-N-imines d'acyle alkylène, dans lesquels au moins une partie des groupes N-acyles portent des groupes hydroxyles comme substituants, avec des réactifs renfermant plusieurs groupes réagissant avec des groupes hydroxyles. Des exemples de tels réactifs sont des polyisocyanates et des précondensats aminoplastes. Les nouveaux polymères se prêtent à l'utilisation comme matériaux et matières de revêtement pour surfaces stables.In order to manufacture the new polymers, poly-N-imines of alkylene acyls are reacted, in which at least part of the N-acyl groups carry hydroxyl groups as substituents, with reagents containing several groups reacting with hydroxyl groups . Examples of such reagents are polyisocyanates and aminoplast precondensates. The new polymers are suitable for use as materials and coating materials for stable surfaces.

Description

"Process for the preparation of crosslinked polymers"

The invention relates to a new process for the preparation of crosslinked polymers from linear polymers containing hydroxyl groups and to polymers containing new hydroxyl groups as starting materials for this process.

Crosslinked polymers are used today in many fields of technology, for example as materials (thermosets, rubber), as coating agents and as carrier materials (gelling agents). Crosslinked polymers of this type can belong to a wide variety of substance classes, it being possible to distinguish essentially two construction principles: firstly, there is the possibility of building up the polymeric networks in one step from low-molecular-weight compounds, and secondly one of those which have already been prepared linear polymers and crosslink them with suitable honorary reagents or in some other way.

Although suitable crosslinked polymers are already available today for many applications, efforts are still being made to find new polymers which have similar or different properties and which can be easily prepared on an industrial scale.

It has been found that new valuable crosslinked polymers can be obtained by crosslinking certain hydroxyl-containing soluble polyalkyleneimines in a suitable manner.

The invention relates to a process for the preparation of crosslinked polymers, in which one reagent has several for reaction having groups capable of hydroxyl groups is reacted with a soluble poly-N-acylalkyleneimine in which at least some of the N-acyl groups have hydroxyl groups as substituents.

Poly-N-acylalkyleneimines are understood to mean polymers of the general formula A

- (alkylene - N -) _y (A)

R'- C = 0

which can in principle be prepared by acylation of polyalkyleneimines with carboxylic acids or carboxylic acid derivatives (y = integer). However, production by cationic polymerization of cyclic imino ethers of the formula B is more common

R '- ^ alkylene (B) 0 ^

wherein the alkylene group generally represents an optionally substituted chain of 2 or 3 carbon atoms. These cyclic imino ethers are also referred to as delta-2-0xazolines or 5,6-dihydro-4H-0xazines, and consequently the term polyiminoethers (polyoxazolines or polyoxazines) is also introduced for the polymers.

Soluble poly-N-acylalkyleneins which carry hydroxyl groups in the radical R ¹ or in some of these radicals are now used for the process according to the invention. They can be obtained, for example, by saponification of poly-N-acylalkyleneimines which contain acetoxy groups as substituents in the acyl radical (A. Levy and M. Litt, J. polym. Sei. AI, 6, 1883-1894 (1968) and US Pat. No. 3,483 145). The labeling of these polymers as soluble is to be understood qualitatively and is not restricted to a specific solvent. It is only intended to distinguish these polymers from crosslinked polymers, which are generally not soluble in solvents, but rather can swell at best. Soluble poly-N-acylalkyleneimines are preferably used, which can be prepared by copolymerizing 1 to 100 mol% of at least one cyclic imino ether of the formula I with 99 to 0 mol% of at least one cyclic imino ether of the formula II, the Formulas I and II have the following appearance:

Formula I:

with the following meaning of the abbreviations:

R = alkyl or alkenyl with 1 to 12 carbon atoms, or aryl;

M = direct bond or double-bonded group with 1 to 12 C atoms, selected from alkylene, alkenylene, arylene and alkarylene groups, which may optionally contain ether oxygens in its chain, where R and M are represented by further hydroxyl groups and / or can be substituted by alkoxy groups having 1 to 3 carbon atoms;

Z = direct bond or the group CR ^ RÖ;

R * to - each independently of one another are H, alkyl or aryl having 1 to 8 C atoms;

Formula II: -CRiR ²

0-CR ³ R ⁴ with the following meaning of the abbreviations: R ⁷ = alkyl, alkenyl, aryl, alkaryl with 1 to 21 C atoms or the group RÖ-0- (CH2CH θ-) _x ⁹ - with x = 0 to 2, R8 = Cι-C3 -Alkyl, R ⁹ = Ci - C3-alkylene; Z, R! -R6 = meaning as in formula I, but independent of this.

Particularly preferred are poly-N-acylalkyleneimines which, by copolymerization of 15.1 to 100 mol%, in particular 20 to 98 mol%, of at least one cyclic imino ether of the formula I with 84.9 to 0 mol%, in particular 80 to 2 Mol% of at least one cyclic imino ether of the formula II can be prepared.

The vast majority of the cyclic isoethers are known and all of them can be prepared by known methods, for example according to DE 16 70 012, DE 14 45 642 or according to the earlier applications DE-P 39 14 155, P 39 14 133 and EP 88 118090.5 . Examples of cyclic imino ethers of the formula I are:

2-hydroxypropoxyphenyl) oxazoline 1-hydroxyethyl) oxazoline

2-hydroxypropyl) dihydrooxazine

1-hydroxybutyl) oxazoline

3-hydroxybutyl) dihydrooxazine

1-hydroxypentyl) oxazoline

3-hydroxypentyl) oxazoline

3-hydroxyheptyl) oxazoline

3-hydroxynonyl) oxazoline α-hydroxybenzyl) oxazoline

4-hydroxyundecyl) dihydrooxazine l-hydroxy-3-methylbutyl) oxazoline

11-hydroxyheptadecyl) oxazoline

11-hydroxy-9-heptadeceny1) oxazo1in

9-hydroxy-10-methoxyheptadecyl) oxazoline

13,14- (hydroxy, methoxy) heneicosyl] oxazoline Examples of cyclic imino ethers of the formula II are:

2-ethyloxazole in

2-heptyloxazole in

2- (2-ethylpentyl) oxazole in

2-0ctyloxazoline

2-nonyloxazoline

2-undecyloxazine

2-pentadecyloxazoline

2-heptadecy1oxazo1in

2- (8-heptadecenyl) oxazoline

2- (8, ll-heptadecadienyl) oxazoline

2-heptyl-3-methyl-oxazoline

2-phenyl-4-methyl-oxazoline

2-phenyloxazine

2- (4-tert-butylphenyl) oxazoline

2- (4-chlorophenyl) oxazoline

2- (2-0xopropy1) oxazine

2- (2,5-dioxahexyl) oxazoline

2- (2,5,8-trioxanonyl) oxazoline

The iminoethers can also be polymerized by methods known per se, for example according to DE 12 06 585, US 3,458,456 or the earlier application DE-P 39 00859.2. In contrast to the information in US Pat. No. 3,458,456, when iminoethers of the formula I are used, the poly-N-acylalkyleneimines formed during the polymerization are not insoluble, even in the case of higher molar proportions.

For the process according to the invention, particular preference is given to poly-N-acylalkyleneimines which are prepared from cyclic imino ethers in whose formula I and / or II at least 4 of the radicals R * to R6 are hydrogen atoms and the others consist of C 1 -C 3 -alkyl . Furthermore in formula I and / or formula II Z preferably the meaning of a direct bond, ie the monomers are delta-2-0xazo.ine. Of these in turn, those with the following substitution patterns are particularly preferred:

R ¹ = CH3, R ² -R ⁴ = H

R ³ = CH3, C2H5 or phenyl; R ¹ , R ² and R ⁴ = H

Poly-N-acylalkyleneimines in which all of the radicals R ¹ to R ^ are hydrogen are very particularly preferred.

Insofar as the poly-N-acylalkyleneimines are copolymers, they can be prepared in a customary manner by choosing the polymerization conditions with a more or less random distribution of the monomers in the chain or else as block polymers. All forms are suitable for the process according to the invention, but the statistical polymers are preferred in most cases. The molecular weight of the poly-N-acylalkyleneimines can be chosen within wide limits, for example between 1,000 and 1,000,000, preferably between 3,000 and 50,000.

The majority of the above-mentioned hydroxyl-containing soluble poly-N-acylalkyleneimines have not yet been described. So far, it has been established that a few percent of a cyclic imino ether containing hydroxyl groups leads to crosslinking during the polymerization and therefore leads to insoluble poly-N-acylalkyleneimines (US 3,458,456 and A. Levy and M. Litt in J. Polym. Sei AI, 6_, 1883-1894 (1968)). However, it was found that when using certain cyclic iminoethers of the formula I, soluble poly-N-acylalkyleneimines are formed. These compounds are therefore a separate subject of this invention. These are poly-N-acylalkyleneimines which, by copolymerization, from 15.1 to 100 mol%, preferably 20 to 98 mol%, of a cyc- Tables of Iminothers of formula I with 84.9 to 0 mol%, preferably 80 to 2 mol% of a cyclic imino ether of formula II are prepared, with the exception of polyacylalkylimines according to the earlier application DE-P 39 00 859.2, which contains 20% by weight. -% and more contain monomer units that carry acyl residues of an unsaturated al phatic carboxylic acid with 16 to 22 carbon atoms. For the rest, the explanations given above for the poly-N-acylalkylenimines apply. With regard to the preparation of the new compounds, reference is made in particular to the information in the older application DE-P 39 00 859.2, the disclosure of which is expressly made part of the content of the present application in this regard. Particularly preferred compounds are those which carry acyl groups of 2-hydroxypropionic acid, 3-hydroxybutyric acid, 4-hydroxyoctanoic acid, 12-hydroxystearic acid or 9,10- (hydroxy, methoxy) stearic acid, and those where R? represents an alkyl radical having 1 to 21 carbon atoms, preferably 2 to 17 carbon atoms, or a phenyl radical.

The reagents required for crosslinking are preferably relatively low molecular weight compounds which carry at least two functional groups which can react with hydroxyl groups. Examples of such groups are anhydride groups and acid chloride groups. The reactivity of these groups essentially determines the reaction conditions of the process. The amount of crosslinking reagent in relation to the hydroxyl groups present determines the degree of crosslinking, the upper limit of which is otherwise determined by the density of the hydroxyl groups in the poly-N-acylalkyleneimine.

Preferred crosslinking reagents for the process according to the invention are polyisocyanates and aminoplast precondensates, but phenol-formaldehyde precondensates are also suitable, for example.

The polyisocyanates can be compounds of the formula III A (-NC0) _n (III)

in which A represents an aliphatic, aromatic or araliphatic group with 4 to 40 C atoms and n free valences on different C atoms and n has one of the values 2, 3 or 4. These polyisocyanates are compounds which are well known in chemical engineering and are usually prepared from the corresponding amines using COCI2. They preferably contain 6 to 26 carbon atoms in the molecular part A. With regard to the details, reference is made to the information in manuals such as Kirk-Othmer, Encyclopedia of Chemical Technology, 3rd edition, volume 23, p. 586 (1984). Examples of suitable polyisocyanates are N, N'N '' -Tris- (omega-isocyanatohexyl) biuret; 2,2,4-trimethylhexamethylene-1,6-di-isocyanate; 1,6-hexamethylene diisocyanate; 2,4-tolylene diisocyanate; 4,4'- and / or 2,4'-diphenylmethane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate and isophorone diisocyanate. Diisocyanates are particularly preferred in the context of the invention. Instead of the polyisocyanates of the formula III, so-called masked polyisocyanates can be used with equal success. These are adducts with polyisocyanates of the formula III, which disintegrate when the temperature rises to form the polyisocyanates and then undergo additions in the same way as the polyisocyanates. So-called prepolymers with isocyanate end groups, which are usually prepared from long-chain alpha, o-diols with average molecular weights of about 500-5,000 and excess diisocyanates of the formula A, are also suitable.

The reaction between the isocyanates III and the poly-N-acylalkyleneimines proceeds smoothly under the conditions customary for the reaction of alcohols with isocyanates, that is to say at temperatures between about room temperature and about 160 ° C. and reaction times of about 1 to 10 hours. Depending on the reactivity of the isocyanates and the alcohol component, these conditions can also be significantly exceeded or fallen short of. The reaction can be carried out in the presence of suitable aprotic solvents, for example aromatic hydrocarbons, chlorinated hydrocarbons, esters or ketones, it being generally carried out with the exclusion of moisture. However, the crosslinking is preferably carried out without solvent. For acceleration, the catalysts customary for the reaction of alcohols with isocyanates, especially tin compounds such as dibutyltin dilaurate or tertiary amines such as 1,4-diazabicyclo [2,2,2] octane, can be added. The progress of the reaction can be followed by determining the unreacted isocyanate, for example by reaction with excess dibutyla in in toluene and back titration with HC1.

As a rule, no more polyisocyanate is used for crosslinking than is necessary for complete reaction with the available hydroxyl groups. In many cases, however, a deficit of polyisocyanate is sufficient, especially if only a small amount of crosslinking is intended and / or the end product should still have hydroxyl groups.

The amino plast precondensates, which are also preferred as crosslinking reagents, are condensation products of formaldehyde with various amides, preferably urea and / or melamine, which may be etherified with lower alcohols.

Characteristic structural features of these products, which are offered in various forms in technology, are methylene bridges between amidic nitrogen atoms and methylol groups bonded to nitrogen, and optionally alkoxymethyl groups. With regard to further details, reference should also be made here to suitable manuals, for example Ull ann's Encyclopedia of Technical Chemistry, 4th edition, volume 7, p. 403 (1974). The reaction between the poly-N-acylalkyleneimines and the aminoplast precondensates is preferably carried out in a solvent-free manner, but the components are first mixed using suitable solvents, for example aromatic hydrocarbons, or suspending agents, for example water. can be made. The actual crosslinking reaction takes place at higher temperatures, preferably between 100 and 220 ° C., and generally takes 5 to 45 minutes.

The reaction between the aminoplast precondensates and the poly-N-acylalkyleneimines does not follow a fixed stoichiometry. The ratio of the reactants can therefore be freely selected within wide limits depending on the desired properties of the end product. Weight ratios of 1 to 0.2 are customary for hydroxyl group contents above 15 mol% in poly-N-acylalkyleneimine; 0.7 to 0.25 are preferred (in each case precondensate to poly-N-acylalkyleneimine), but these values can also be exceeded or fallen below if necessary.

The end products of the process are highly elastic to hard materials which can swell in solvents with a low degree of crosslinking. They are particularly suitable as materials and, if necessary, can also be made smooth in molds. Their suitability as coating agents for solid surfaces, where they produce resistant and firmly adhering coatings, is also outstanding.

B E I S P I E L E

Preparation of the poly-N-acylalky¬ lenimines containing hydroxyl groups

Poly-N-acylalkyleneimines suitable according to the invention were prepared by cationic polymerization of cyclic imino ethers of the formula I and cyclic imino ethers of the formula II in bulk with the addition of methyl p-toluenesulfonic acid as the catalyst. For this purpose, the iminoethers were mixed in the intended ratio at room temperature or just above their melting point, and a small amount of methyl p-toluenesulfonic acid as catalyst was then added with stirring and the mixture was heated at 160 ° C. for 30 minutes. When imino ethers with a lower boiling point were used, the polymerization was carried out correspondingly longer below the boiling point, but in any case until the reaction was complete. Tables 1 and 2 give the details of the iminoethers used for the polymerization based on mostly technical carboxylic acids. They were produced analogously to the information in the older patent applications EP 88 118090.5, DE-P 39 14 133 and DE-P 39 14155. The polymerizations were generally carried out in batch sizes of approximately 100 g. They supplied solid products at room temperature which could be used for the process according to the invention without further purification. The polymers were characterized by the molecular weight (determined as the weight average with the aid of gel permeation chromatography against the polystyrene standard). Table 3 shows the details of the polymerizations and the molecular weights of the resulting products. Table 1: Cyclic iminoethers of the formula I.

No. Mol. Carboxylic acid base M wt. Of the imino ether

Table 3: Pol -N-ac lalk lenimine

Crosslinking of the poly-N-acylalkyleneimines with aminoplast precondensates

In these examples, the crosslinking process was carried out on deep-drawn iron sheets, in order in this way to produce a hot-hardened coating on the sheets.

For this purpose, 70% solutions of the poly-N-acylalkyl enimines in toluene or 55% dispersions of these polymers in water in a weight ratio of 7: 3 (based on solvent-free products) with a melamine resin (type Cymel 301, American) Cyanamide) mixed and applied to the sheets with the help of a squeegee. The aqueous dispersions were produced in such a way that initially 33% solutions of the polymers in isopropanol were prepared, which were then mixed with 2.5 times the amount of water (based on polymer) with stirring. Isopropanol and water were then removed from the mixture under vacuum until a 55% dispersion remained in water. After the sheets had been vented at room temperature, the coated sheets were heated in a forced-air oven at 160 ° C. for 25 minutes in order to crosslink the films. The next day, the pendulum hardness of the paint films was determined in accordance with the German standard DIN 53 157. The results, shown in Table 1 below, showed that films of good hardness were formed.

Weight ratio of poly-N-acylalkyleneimine: aminoplast precondensate 4: 1

Crosslinking of the poly-N-acylalkyleneimines with polyisocyanate

This crosslinking reaction was also carried out here on reaction mixtures which had been applied as films to iron sheets with the aid of a doctor blade, in order in this way to produce adherent coatings. In the examples, the mixture consisted of equivalent amounts of poly-N-acylalkyleneimine (based on hydroxyl groups) and 4,4'-diphenylmethane diisocyanate (MDI) or a diisocyanate blocked with caprolactam (Grillbond IL6 (Ems- Chemistry), equivalent weight 238). The film was crosslinked by placing the coated sheet for 25 minutes in a forced air heating cabinet at 160 ° C. The next day, the properties of the coating film were determined in the form of the pendulum hardness in accordance with DIN 53157, the deepening (reverse) in accordance with US standard ASTM-D 2795-69 and the cross cut in accordance with the German standard DIN 53 151. there correspond to higher numerical values for pendulum hardness and impact depth to a greater hardness or better flexibility of the coating. The cross-cut was assessed visually with a rating between 0 (best adhesion) and 4 (poor adhesion).

Table 2: Networking on iron sheets

Claims

1. A process for the preparation of crosslinked polymers, characterized in that a reagent which has several groups capable of reacting with hydroxyl groups is reacted with a poly-N-acylalkyleneimine, in which at least some of the N-acyl groups carry hydroxyl groups as substituents becomes.

2. The method according to claim 1, in which a poly-N-acylalkyleneimine is used, which can be prepared by copolymerization of 1 to 100 mol% of a cyclic imino ether of the formula I with 99 to 0 mol of a cyclic imino ether of the formula II, where formulas I and II have the following appearance:

Formula I:

with R = alkyl or alkenyl having 1 to 12 carbon atoms, or aryl;

M = direct bond or divalent group with 1 to 12 carbon atoms, selected from alkylene, alkenylene, arylene and alkarylene groups, which may optionally contain ether oxygens in their chain, where R and M are represented by further hydroxyl groups and / or by Alkoxy groups with 1 to 3 carbon atoms can be substituted;

Z = direct bond or the group CR ^ RG;

R1 to R6 = each H, alkyl or aryl having 1 to 8 carbon atoms; Formula II:

N-CRiR ²

R7. ) 0-CR ³ R ⁴

with R ⁷ = alkyl, alkenyl, aryl, alkaryl with 1 to 21 C atoms or the group R ⁸ -0- (CH2CH2θ-) _x R ⁹ - with x = 0 to 2, R ⁸ = Cι-C3-alkyl, R ⁹ = Ci - C3 alkylene; Z, R ^ -R ⁶ = meaning as in formula I, but independently of this.

3. The method according to claim 2, in which in formula I and / or formula II the symbol Z is a direct bond.

4. The method according to claim 2, in which in formula I and / or in formula II R ¹ to R6 are hydrogens.

5. The method according to any one of claims 1 to 4, wherein the reagent capable of reacting with hydroxyl groups is a polyisocyanate, a blocked polyisocyanate or a prepolymer with isocyanate end groups.

6. The method according to any one of claims 1 to 4, wherein the reagent capable of reacting with hydroxyl groups is an Amino¬ plast precondensate.

7. poly-N-acylalkyleneimine, which can be prepared by copolymerization of 15.1 to 100 mol% of a cyclic imino ether of the formula I with 84.9 to 0 mol% of a cyclic imino ether of the formula II, these formulas being as stated in claim 2 Appearance, with the exception of poly-N-acylalkyleneimines which contain 20% by weight or more of monomer units and which carry acyl radicals of an unsaturated aliphatic carboxylic acid having 16 to 22 carbon atoms.

8. poly-N-acylalkyleneimine according to claim 7, producible by copoly ersation of 20 to 98 mol of a cyclic imino ether of the formula I with 80 to 2 mol% of a cyclic imino ether of the formula II.

9. poly-N-acylalkyleneimine according to one of claims 7 or 8, in which in formula I and / or in formula II, preferably in both, at least 4 of the radicals R to R ^ are hydrogen atoms and the rest of Ci - C3 ~ alkyl consist.

10. poly-N-acylalkyleneimine according to one of claims 7 or 8, in which in formula I and / or formula II, preferably in both, Z is a direct bond.

11. poly-N-acylalkyleneimine according to claim 10, in which in formula I and / or in formula II, preferably in both, R ¹ to R ^ are hydrogens.

12. Poly-N-acylalkyleneimine according to one of claims 7 or 8, in which in formula I the group H0-CHR-M- the alkyl group of 2-hydroxypropionic acid, 3-hydroxybutyric acid, 4-hydroxyoctanoic acid, 12- Hydroxystearic acid or the 9,10- (Hydroxy.methoxy) stearic acid.

13. poly-N-acylalkyleneimine according to one of claims 7 or 8, in which in formula II R ^{7 represents} an alkyl radical having 1 to 21 carbon atoms, preferably having 2 to 17 carbon atoms, or a phenyl radical.

14. Poly-N-acylalkyleneimine according to one of claims 7 or 8, with an average molecular weight of 1000 to 1,000,000, preferably 3,000 to 50,000.