DE2357859C2 - Catalyst for the production of polyurethanes - Google Patents

Description

The invention relates to a catalyst for the production of polyurethanes with an opposite known Catalysts increased activity at a temperature significantly above room temperature.

Urethane and epoxy resin reactions for the production of cellular polyurethanes, polyurethane coatings and epoxy moldings must be carried out catalytically.

For certain applications of polyurethanes and epoxy resins, it is useful to use a mass available that contains all components in a stable form at a comparatively low temperature and a rapid polymerization reaction can be allowed when the mass is heated to the activation temperature Amines used as catalysts for such heat-activatable masses, then these amines tend to to catalyze the polymerization to a considerable extent even at room temperature. A catalysis with delayed action has heretofore been achieved by using an acid salt of a tertiary amine became. For example, a delayed onset of catalysis by using benzoate salts or Acetate salts achieved by tertiary amines. Such salts, however, tend to be at room temperature as well partial dissociation even at elevated temperature when used as a polymer precursor system Catalysts are added. Partial dissociation occurs at room temperature and leads to a premature amine catalysis, so that the storage stability is adversely affected. At increased Temperatures some of the amines are unsuitable for catalysis because of their reversible dissociation.

It is also already known to use a mixture of an amine catalyst and a tin catalyst to achieve this to use a balanced catalysis of polyurethane compounds. Because of the incompatibility between the benzoate salts of tertiary amines and the tin catalysts, however, the use of such

3: 5 do not enforce catalyst mixtures.

The invention has therefore set itself the task of creating a catalyst for the production of polyurethanes which no longer has the disadvantages of the known catalysts described above.
This object is achieved by the invention by means of a catalyst according to the patent claim.
Essential to the catalysts of this invention for the production of polyurethanes is the fact that these irreversibly to a catalytically akiiven tertiary amine at temperatures between 70 and 200 ⁰ C decompose, ie, within an ideal temperature range for carrying out Polyurethanpolymerisationen.

Compared to catalysts known to date for the production of polyurethanes, those according to the invention are distinguished Catalysts have the following advantages.

The catalysts according to the invention show a considerably reduced catalytic activity at room temperature, while at the same time they have delayed activation ^{properties at elevated polyurethane polymerization temperatures (70 to 200 °} C.). Such reduced activity at room temperature enables good shelf life and / or long useful life when the catalyst is used in a polyurethane precursor system. Despite this reduced catalytic activity at room temperature

so the catalysts of the invention can easily be decomposed by elevated temperatures, the tertiary amine is released for the activation of the precursor system and for an execution in the technical Scale good catalytic converter rates can be achieved.

Various tertiary amines are already known as suitable catalysts for polyurethane reactions. However, when they are placed in a polyurethane precursor system at room temperature, it begins immediately their catalytic effect, so that the inability to store and / or the useful life are short. Since the free tertiary amines start too quickly, attempts have been made to add acidic salts such as triethylenediamine formate use. Such salts are reversibly dissociated, whereby not only the amine, but also the Acid is released, which either competes with the tertiary amine or is possible Looks for reactants in the precursor formulation.

The surprising technical progress achieved by the present invention is that certain thermally unstable -substituted carboxylic acids react with the tertiary nitrogen in tertiary amines, effectively suppressing any catalytic activity of the tertiary amine at room temperature, when heated to a temperature between 70 and 200 ⁰ C, however, irreversible decomposition takes place, as a result of which the tertiary amine is released, which can be fully used as a catalyst. It is essential that the acid released does not remain as such, but rather decomposes itself further, so that there is no competition between the acid and the amine in the precursor formulation.

Examples 9 and 10 according to the invention show that triethylenediamine formate and triethylenediamine acetate, typical representatives of the state of the art, only a short service life in contrast to the invented

deliver salts according to the invention (cf. Example 1, Table II).

It is also known in the polyurethane art to use a mixture of an amine catalyst and a Use tin catalyst. The lack of compatibility between the reversible benzoate salts of the tertiary amines and the tin catalysts have problems with the use of such catalyst systems raised.

The salt of triethylenediamine and cyanoacetic acid is a new compound.

The amine salts are usually prepared by mixing 1 mol of amine with 1 mol of a monobasic Acid or 1 to 2 moles of a dibasic acid. Bis-tertiary amine salts are made by mixing 1 mole of a bis-tertiary amine is generated with 1 to 2 moles of either a monobasic or dibasic acid Although direct mixing of the amine with the acid is possible, a solvent is used Preferred suitable solvents are, for example, water, alcohols, ethers and acetone. Particularly beneficial is the use of acetone. The temperature range for the reaction is between 30 and 50 ° C. To When the reaction is complete, the product salt is separated from the solvent, for. B. by filtration, centrifugation or with the aid of other suitable separation processes if the salt formed is a solid If the product salt is a liquid, the solvent can be removed by evaporation under reduced pressure removed. The amine salts used according to the invention can be either the hydrates or the also about anhydrous salts. So z. B. the product salt obtained in an aqueous solvent be in the hydrated form, or the anhydrous salt can be used as an activator-catalyst on or before use to be hydrated.

Due to the selection of the -substituted carboxylic acid component of the amine salt, the invention suffer Amine salts cause irreversible thermal decomposition at the activation temperature according to the below indicated reaction 2 and not just a reversible dissociation according to the indicated Reaction 1.

⁰ -

Reaction 1:

Reaction 2: X-CH ₂ -CO HA

XCH ₃ + A + CO ₂ J

In these reaction equations, A denotes an amine with at least one tertiary nitrogen atom and X denotes a radical of the formulas CN, SO, SO ₂ , CO, NO ₂ , COCH ₃ and CO Φ.

The rapid, irreversible thermal decomposition of the acid component of the salt at the activation temperature releases the amine for effective catalysis of the aromatic or aliphatic polyisocyanate and Polyol precursor compounds or the epoxy precursor compounds at the activation temperature. The those Compound containing precursor compounds for polyurethane or epoxy resin production can therefore use the Salt of the amine-containing catalytic components at room temperature and is still, whether in mixed or unmixed form, stable over long periods of time, regardless of sensitivity against decomposition to develop activation at elevated temperature.

The catalysts can be used solely from the specified salt as an activator for the formation of polyurethane or epoxy resin exist or exist as co-catalysts together with other catalysts, be it with another amine catalyst or an organometallic catalyst, e.g. B. a tin, silicon, antimony, Lead, copper or iron catalyst.

The catalysts can also be used advantageously in polyurethane or epoxy resin precursors, what common known additives, e.g. B. blowing agents, pigments, fillers or surface-active agents, contain.

The following examples are intended to explain the invention in more detail.

example 1

A solution of 100 ml of acetone containing 0.2 mol of cyanoacetic acid was mixed with 100 ml of acetone, the Containing 0.1 mol of triethylenediamine, mixed. The mixture of the two solutions resulted in the formation of one Precipitation, the molecular formula

C ₁₂ H ₁₈ N ₄ O ₄

This precipitate was dried in a vacuum oven at 6O ⁰ C. It was found that its melting point was 124 ° C. The analytical values given below confirmed that the composition corresponded to that of the expected triethylenediamine bis-cyanoacetate.

Calculated: C 51.06 H 6.38 N 19.86

Found: C 50.72 H 6.32 N 19.49

In further experiments, triethylenediamine monocyanoacetate was prepared in an analogous manner. This compound also decomposed in a sublimation device at 135 to 140 ^° C. The analysis values for this

Compounds of gross formula C ₉ Hi ₅ N ₃ P ₂ were as follows:

Calculated; C 54.82 H 7.61 N 2132
Found: C 54.50 H 8.50 N 20.35

To determine the catalytic activities, a polyisocyanate end group intended for vinyl coatings was used A series of tests were carried out at 100 ° C under the use of

ίο 0.2 g triethylenediamine bis-cyanoacetate in 10 g of the prepolymer mixture with a curing time of 60 minutes.

g per 10 g with a curing time of 45 minutes,
0.4 g per 10 g with a hardening time of 30 minutes and 0.5 g per 10 g with a hardening time of 26 minutes.

The conditions are summarized again in Table I below.

Table 1

Hardening time at 100 ° C below

use of
NCCH ₂ CO ₂ H · N (C ₂ Hi) ₃ N _{· HO 2} CCH ₂ CN

g catalyst min hardening

0.2 60

0.3 45

0.4 30

0.5 26

The same triethylenediamine bis-cyanoacetate was used as a hardener for the one kept at room temperature Coating prepolymer used. The conditions for the same curing times with different The amount of triethylenediamine biscyanoacetate used as a catalyst is shown in Table II below listed.

Table II

Cure time at room temperature using
NCCH ₂ CO ₂ H · N (C ₂ H ₄ ) SNHO ₂ CCH ₂ CN

g hours

0.20 24

0.30 24

0.40 24

0.50 24

0.60 24

As a comparative sample, a solution that contained practically 35% triethylenediamine in polypropylene glycol was used, used as a comparative catalyst, the same polyester urethane precursor compound in 10 g batches was used. However, there were significant deviations in the curing time depending on the Concentration of the catalyst both at room temperature and at 100 ° C, as in the following tables III and IV is shown.

Table III

Cure time at room temperature using a 33% solution of N (C ₂ H ₄ ) ₃ N

g hours

0.22 3.55

0.33 3.62

0.44 2.92

0.55 2.38

0.66 1.50

Table IV

Hardening time at 100 ° C below

Using a 33% solution of

N (C ₂ IU) ₃ N

g min

0.33 113

0.44 90

0.55 65

0.66 53

The fact that the triethylenediamine bis-cyanoacetate salt exhibited a delayed effect was revealed from the finding that it was much slower than the solution of triethylenediamine at room temperature, whereas it worked much faster at 100 "C. The results show that triethylenediamine-bis-cyanoacetate at elevated temperature is an equally useful catalyst for the prepolymer being tested, as is the Solution of triethylenediamine, but that triethylenediamine-bis-cyanoacetate by far at room temperature has an advantageous stability and durability in the mixture for a longer period of time.

Example 2

It has been the decomposition temperature of the properties of triethylenediamine-bis-cyanoacetate examined by heating a 3.4 g sample of the salt in a Sublimierapparat over a temperature range of 130 to 15O ⁰ C, that is to say above the melting point temperature of 124 ° C. The developed Gas from the sublimer was passed through a gas cuvette and into a gas meter. The evolved gas was identified as carbon dioxide by bubbling it through a solution of barium hydroxide, whereby a white precipitate of barium carbonate formed. After the salt was decomposed, the remaining residue was weighed to find that its weight was 1.30 g, and it was identified as triethylenediamine. The theoretical value for the gas volume was 5.4 dm ³ , which came very close to the measured value for the gas volume of 5.1 dm ^3. The measured weight of 1.30 g for the triethylenediamine also largely corresponded to the theoretical amount of 1.34 g.

It must be emphasized that the terms "decomposition temperature" and "thermal activation temperature" are not synonymous, since the beginning of the decomposition of such salts usually at a lower Temperature occurs as it is the "decomposition temperature" and over an increasing temperature range progresses. When used as a catalyst, these salts decompose and start up at elevated temperatures an exothermic reaction in the polymerization, which in turn leads to further catalytic decomposition Salt promotes

B e i s ρ i e 1 3

Into a combined gas chromatograph (G.C.J mass spectrometer instrument, the G.C. of which was equipped with a 4.5 m chromatography column packed with 15% of a high molecular weight hydrocarbon Gas Chromatograph-Q-Substrate, various aqueous or methanolic solutions were used in the G.C. at Entered 150 ° C and the temperature of the column was programmed from 100 to 200 ° C

The decomposition products of the salts tested were separated on the column and then on the mass spectrometer with the help of which they were identified. The results obtained are as follows Table V listed

Table V Triethylenediamine bis-cyanoacetate

Decomposition products approximate amount in%,
gas chromatography
certainly theoretical
Amount% by weight CO ₂
Acetonitrile
Triethylenediamine 3430
29.62
35.43 31.2
29.1
39.7 CO ₂
acetone
Triethylenediamine 24.2
27.7
48.1 233
15.7
603 CO ₂
DMSO
Triethylenediamine 42.4
3.0
53.4 31.7
28.0
40.3

Triethylenediamine acetone dicarboxylate CO ₂ 24.2 233 Triethylenediamine thionyl diacetate Example 4

A polyurethane precursor composition containing 100 g of polypropylene glycol having a molecular weight of about 3,000 which served as the polyol was used for the following tests. The composition containing the precursor compound also contained 10 g of technically pure tolylene diisocyanate, the ratio of the 2,4- to 2,6-isomer of about 80:20. At room temperature, the use of triethylenediamine bis-cyanoacetate in a series of tests using increasing amounts of the catalyst showed the same degree of cure over a period of 48 hours, indicating that the cure was spontaneous and not due to catalyst concentration . At 100 ^° C., the curing time was greatly reduced compared to a non-catalyzed sample, the effect of the catalyst concentration on the curing time being practically the same, regardless of whether the triethylenediamine solution or the triethylenediamine bis-cyanoacetate salt was used. At a concentration of 0.1 g of catalyst per 10 g of precursor compound, the curing time was 14 minutes for both the decomposable salt and the triethylenediamine solution. When using 0.2 g of catalyst per 10 g of precursor compound, the curing time was 12 minutes for the decomposable salt and 8 minutes for the triethylenediamine solution. When using 0.4 g of catalyst per 10 g of precursor compound, the curing time was 8 minutes for the salt of triethylenediamine-bis-cyanoacetate and 6 minutes for the solution of triethylenediamine. At room temperature, when the triethylenediamine solution was used, the curing times were 100, 60, 30 and 20 minutes, respectively, for the amounts of 0.12, 0.24, 0.36 and 0.48 g of catalyst used per 10 g of the polyurethane precursor compound.

The results obtained showed that triethylenediamine bis-cyanoacetate was an effective catalyst with delayed action that can be activated by heat and the same reliable practical behavior as a free triethylenediamine catalyst shows.

Example 5

Triethylenediamine thionyl diacetate was prepared from triethylenediamine and thionyl diacetic acid. The production took place in a round bottom flask equipped with a reflux condenser and mechanical stirrer was by adding the equivalent amount of the amine to the acetone solution of the acid in the flask. The reaction temperature was kept below 50 ° C. by external cooling. When the addition was complete, the The reaction mixture was cooled and the product formed was isolated by filtration. The yields were quantitative.

After drying in a vacuum oven, the purity and composition of the salt were determined chemical analysis determined.

Table VI

Amine Salt Empirical Formula F (° C) Analysis

ber.

Triethylenediamine thionyl diacetate Ci ₀ Hi ₈ O ₅ SiN ₂ 103 C 43.52 C 43.17

H 6.70 H 6.47

N 10.12 N 10.07

Example 6

For the following tests, about 100 parts of the polyol mixture were used, made up of approximately equal parts Polypropylene glycol with a molecular weight of about 2000 and a polyethylene glycol with a molecular weight consisted of about 4000. The precursor composition contained approximately 12 grams of tolylene diisocyanate per 100 grams of polyol and 4 g of triethylenediamine bis-cyanoacetate. The precursor mass was used in a coating device, in which a textile web passed through a coating zone with a uniformly thin one Coating of precursor mass was provided. The coated web was directed into zones in which the Precursor compounds were framed, foamed, swollen and cured to cover the polyurethane foam to tie on the forward moving textile web. The curing zone was held at 100 ° C and off this zone was peeled off the hardened sheet, covered with polyurethane foam. The the precursor compounds containing mass was kept practically at room temperature, where it turned out to be important that it was stable for a long time, so that no adverse viscosity increase during ordinary operations took place.

Triethylenediamine and sulfonyldiacetic acid were used to prepare the tertiary amine salt used mixed in acetone and the salt formed is filtered off from the acetone. When this salt is used as a catalyst The delayed action of the catalyst proved to be very satisfactory and because of the decomposition of the A good product was obtained in the salt, whereas in a comparative sample, in the triethylenediamine diacetate salt was used, only dissociation of the salt occurred.

Example 7

A catalyst was used to produce a textile product with a polyurethane foam coating Mixture used from 0.40 parts of catalyst per 10 parts of polyol, which is composed of 100 parts 65. Ethylene glycol terephthalate with a molecular weight of 3000 and 20 parts of dipsocyanatochloro-phenylmethane. The amine salt catalyst was triethylenediamine acetone dicarboxylate, in which the two acetyl groups are linked by a carbonyl group. Using this catalyst with delayed action gave results that were better than using a dibenzoate salt of

Triethylenediamine as a thermally activated catalyst. The superior results are evident at least partly explainable with the ease of thermal decomposition of the acetone dicarboxylate anion and the reduced tendency to reversible dissociation.

Example 8

A mixture of 10 parts of glycidyl polyether and 1 part of amine curing agent was used to cure an epoxy resin Stirred for 2 minutes and then left to harden at different temperatures. In the following Table VII gives the various cure times for triethylenediamine and triethylenediamine bis-cyanoacetate salt compared to each other.

Table VII Cure Temperature "C

Room temperature

80 100 135 150

The results clearly show that it is suitable for applications where stability over prolonged periods of time It is desirable that the catalysts of the invention offer great advantages since they are activated thermally develop full activity corresponding to practice.

Example 9

A polyurethane precursor composition of 100 parts of polyol and 10 parts of tolylene diisocyanate (isomer ratio 2,4 / 2,6 = 80/20) was cured at room temperature and at 100 ⁰ C using reversible amine salts. The concentrations of reversible amine salt used per 10 g of polymer and the curing times are listed in Table VIII below.

Table VIII

Curing time in minutes Triethylenediamine-bis- Triethylenediamine cyanoacetate > Week 420 - 48 _ 11th 55 8th 12th 3 8th 1

Reversible amine salt

Concentrations

Curing time in minutes
at room temperatures

at 100 ^° C

Triethylenediamine diformate

85
65
45
30th

13th 9 6th 5

The results show that triethylenediamine diformate shows only a short stability at room temperature, in contrast to the salts according to the invention, whose advantageous behavior z. As shown in Example 1, Table II .

Example 10

A prepolymer mixture of 100 parts of polyol and 10 parts of tolylene diisocyanate (isomer ratio 80/20) was cured with various amounts of Triätfiyiendiäiiiin-bis-aceiai (a reversible salt) both at room temperature and at 10G ¹ C. The concentrations used (in parts per 100 parts, expressed as pph) and the curing times found are listed in Table IX below

Table IX

Amine salt

Concentrations pph

Curing time in minutes

at room temperatures at 100 ° C

Triethylenediamine bis-acetate

106 51 36

10
6th

The results show that triethylenediamine bis-acetate has only a brief stability at room temperature In contrast to the salts which can be used according to the invention, whose advantageous properties are e.g. B. off Example!, Table II.

Claims (3)

Patent claims: 1. Catalyst for the production of polyurethanes, characterized in that it consists of a Salt of a «-substituted carboxylic acid, selected from cyanoacetic acid, nitroacetic acid, an acetone dicarboxylic acid, Sulphonyldiacetic acid, thionyldiacetic acid, acetonacetic acid and benzoylacetic acid, and an amine selected from triethylenediamine, tetratmethylbutanediamine, trimethylaminoethylpiperazine, Tetratmethylguanidine, an azabicycloheptane, an azabicyclooctane, an N-allylpiridine, 2,2'-oxybis (morpholinoethylether, an amidine, an N-alkali imidazole or a silylmorpholine 2. Salt of triethylenediamine and cyanoacetic acid. ίο 3. Use of a catalyst according to claim 1 or the salt of claim 2 as a catalyst for Manufacture of polyurethanes.