DE1300693B - Process for the production of non-cellular polyurethanes - Google Patents

Description

The invention relates to a process for the production of non-cellular solid polyurethanes which by reacting reaction mixtures of aromatic polyisocyanates and acid-free polyhydroxy compounds have been produced, e.g. B. by converting liquid or at least malleable. Reaction mixtures of polyisocyanates and neutral polyhydroxy compounds in the presence of certain soluble metal salts of organic Acids that enable these mixtures to harden into solid products so that they become their final products Properties obtained in a relatively short time at ordinary room temperature.

Tough, solid elastomers are known to be produced by heating reaction mixtures of polyhydroxy compounds and polyisocyanates are produced at elevated temperatures, and used for treatment the mixtures in an atmosphere of elevated temperature, e.g. B. around 165 ° C required Time can be shortened considerably by adding catalysts or curing accelerators. It it has been found that a number of organometallic compounds (those compounds which have a carbon-metal bond) the hardening of castable reaction mixtures of neutral Polyhydroxy compounds and polyisocyanates with the formation of solid elastomers at low temperature allows. Such compounds are e.g. B. Dibutyltin dilaurate and similar tin compounds that have both a carbon-tin bond as well have a tin-oxygen or -sulfur bond.

Despite the good effectiveness of these catalysts, the solid product obtained suffers after a long period of time Exposure to sunlight causes degradation to the point of uselessness. With the decrease in the amount of the tin catalyst in the reactive system, the rate of conversion decreases, and the for Achieving the final properties necessary hardening time is extended, thereby causing side reactions increase, resulting in a softer end product.

The claimed process for the production of non-cellular polyurethanes by reacting Reaction mixtures produced by the reaction of aromatic diisocyanates and polymeric polyols, containing predominantly secondary hydroxyl groups have been obtained, among practical anhydrous conditions and in the presence of metal compounds as curing catalysts under Shaping is characterized in that the reaction is carried out at room temperature in the presence a catalytic amount of a soluble salt of an organic acid with Pb (II) or less preferred, with Hg (II), Sn (II), Bi (III) or Sb (III)

performs. These cold-hardened products are generally • of high molecular weight.

Aromatic diisocyanates commonly used in high molecular weight systems are the moderately hindered arylene diisocyanates, such as. B. the isomeric tolylene diisocyanates. However, they are unimpeded Diisocyanates, such as 4,4'-biphenylene diisocyanate, and hindered diisocyanates, such as that 3,3'-dimethoxy-4,4'-biphenylene diisocyanate and durene diisocyanate

OCN

H ₃ CCH ₃

H ₃ C CH ₃ NCO

also useful for carrying out the process. Polyhydroxy compounds are acid-free organic Polyols that contain end groups with activating groups covalently attached to carbon atoms are bound, which are in o- or / ^ - position to primary or carbon atoms bearing secondary hydroxyl groups. Such end groups are e.g. B.

j activating 1

\ Rest J

- CH, - CH, - CH, OH

I activating 1

1 remainder J #

- CH, - CH - CH, OH

55

These activating residues are OH, S, O or N.

The activating radical is attached to the α or jS carbon atom by a single covalent bond, this α- or jS-carbon atom should at least carry a covalently bonded hydrogen atom so that the activating residue can work better.

Polyols that fall under this definition are lower alkylene glycols, such as ethylene glycol, propylene glycol, 1,2-, 2,3- and 1,3-butylene glycol, and the 'polyalkylene ether glycols, such as the polyethylene and polypropylene glycols and the higher glycols of the type mentioned, in the end groups of the poly compound in the α- or / S-position to a primary or secondary hydroxyl group an activating Bear rest.

Polyester with a terminal hydroxyl group (anhydrous and acid-free), which are produced by condensation of Polycarboxylic acids, such as adipic, terephthalic, sebacic, maleic and succinic acid, with ether glycols, such as ethylene glycol or higher alkylene and polyalkylene ether glycols have been obtained, contain the required end groups with activating The remainder. Another group of useful polyols comprises the celluloses. For the purpose of manufacture of high molecular weight with good water resistance and other desirable properties however, the polyalkylene ethers, especially polypropylene glycol, are preferred among the polyols.

Metal salts preferred for catalysis are the soluble carboxylic acid salts, such as the naphthenates, Octoates, oleates and stearates, e.g. B. lead naphthenate, leadallate, lead octoate (-2-ethylhexoate), bismuth naphthenate, Antimony octoate, mercury naphthenate, tin (II) octoate and tin (II) oleate.

To be effective as catalysts, these salts of strongly chelating groups, such as OH, SH, NR2, in the vicinity of the carboxyl

carbon atom, ζ. B. in the α or / 3 position this, be free. R denotes hydrogen or a monovalent organic radical.

In order for the reaction mixtures to harden to solid elastomers at room temperature, the Systems practically free of acids and water and free of any strongly chelating compounds, like catechol

OH

OH

and 1,10-phenanthroline

/ Ν — X _x / ^ ^N \

While the molar NCO / OH ratio can vary within wide limits, one obtains the most useful products at an NCO / OH ratio of 1, so that all of them can be implemented Atoms are consumed and side reactions that lead to a deterioration in the properties of the Elastomers could not occur. Likewise, the ratio can be between about 0.5: 1 to 1.5: 1 vary. A ratio of about 0.9: 1 to about 1.1: 1 provides optimal products.

The amount of catalyst to be used, based on the weight of the NCO and hydroxyl reaction partners, can vary within very wide limits. ¹ ZsO ⁰ Zo metal salt catalyst has already proven to be sufficient in some systems to accelerate curing at room temperature. About I ⁰ Zo catalyst, the upper limit is in a marked shortening of the curing time necessary at room temperature. Larger amounts result in no appreciable abbreviation that time. In some cases, the heat resistance of the product can be adversely affected. Therefore, a larger amount is only indicated if certain plasticizing or other effects are to be achieved with the ^ product.

The hardness and the amount of the rubbery component in the elastomeric end products can within relatively narrow limits by including trifunctional components in predetermined amounts in the system or by incorporating such a trifunction in the isocyanate or polyol are regulated, whereby one obtains crosslinking sites that have a crosslinked high molecular weight Let structure arise. So a small amount of a triol, such as 1,2,6-hexanetriol, can be used to initiate the formation of a polyalkylene ether triol. In the polyisocyanate portion the system may contain a small amount of a triisocyanate, e.g. B. one of tolylene diisocyanate and trimethylolpropane, be included. The calculable amount of these additives determines the number of Crosslinks that are predetermined based on the molecular weight of the final polyadduct can be.

As usual, the elastomers can contain antifoams, antioxidants, stabilizers and reinforcers, Contains fillers and pigments. These additives should be as anhydrous, acid-free and free as possible be from strongly chelating groups.

As expected, the catalysts within the group are not in every polyol-polyisocyanate system equally effective. The lead salt catalysts are mostly preferred because they consist of all isocyanate-polyol combinations produce solid elastomers in a relatively short time at room temperature. The lead salt catalysts seem to be involved in urethane formation specifically to catalyze the NCO-hydroxyl reaction more strongly than possible side reactions, also the formation of solid high molecular weight even from sterically hindered diisocyanates, like durene diisocyanate.

Aromatic diisocyanate-diol systems of the above Art gel when reacted in the presence of catalan amounts of the soluble metal salts according to the invention at room temperature usually within a period of 10 minutes and can after watering after less than an hour, usually after half an hour, of the Form to be freed. The solid products obtained achieve their final properties at room temperature within a period of 72 hours and usually within a period of less than about 12 hours.

example 1

It shows the importance of the presence of the activating residues in the hydroxyl groups End groups when these groups with isocyanates in the presence of the soluble metal salts according to the invention implemented.

Reaction mixtures are in the form of dioxane solutions with different monohydric alcohols a toluene diisocyanate-trimethylolpropane adduct (toluene diisocyanate to trimethylolporpane = 10: 1) produced, with a viomolar hydroxyl and a viomolar NCO concentration in the solution is present. 1 part of catalyst is added to every 100 parts by weight of the solution.

In all cases, adducts are formed from a mixture of the isomeric 2,4- and 2,6-tolylene diisocyanates (80:20) and trimethylolpropane in the ratio 10: 1 together with the particular monovalent ones Alcohols and soluble metal salts from the table below are used.

For all mixtures, the maximum temperature increase compared to room temperature is complete conversion at room temperature about 34 ° C, as by rapid reactions within about 10 seconds or less and determined from the temperature rises. The fast ones Reactions were promoted by faster acting catalysts, usually lead octoate, with a active, hydroxyl group-bearing compound, such as (CH3) 2NCH2CH2OH, achieved, with only slight or there was no heat loss. If one compares this value of 34 ° C with the following temperature increases, this gives a good indication of the relative activity of different combinations of metal salts and activating residues. In the following cases, the temperature rise was tracked for over 2 minutes.

Tabel

catalyst

Temperature rise after 2 minutes (° C)
Monohydric alcohol

C ₂ H ₅ OCH ₂ CH ₂ OH HC ₄ H ₉ OH

C ₂ H ₅ SCH ₂ CH ₂ OH

No catalyst

Lead octoate (Pb-di-2-ethylhexoate)

Antimony octoate

Tin octoate ....

Mercury naphthenate.

Bismuth naphthenate ............

Cobalt octoate ....

Manganese octoate

Ferric octoate

28

31

28

25th

21

10

0
4th
4th
4th
4th

13th
4th

12th
6th

30th

29

29

30th

22nd

12th

It turns out that with this simple comparison of values the activating influence of the monovalent alcohol residues on the lead, antimony, tin, mercury and bismuth catalysts is evident, as opposed to the uncatalyzed systems or those in which the usual drying salts, such as cobalt octoate, manganese octoate and Ferric octoate can be used. The group relationship of lead, tin, antimony, mercury, and Bismuth sake does not emerge when converted into n-butanol, but only in alcohols which contain an activating residue. The two alcohols compared with n-butanol in this example contain sulfur or oxygen atoms, in both cases bonded to carbon atoms in the a-position to the carbon atom bearing the hydroxyl group.

The lack of this group relationship of the invention Metal salts with one another in simple alcohols without activating residues has been demonstrated by using conversion systems, the simple alcohols such as butanol and unhindered isocyanates such as phenyl isocyanate, as well as hindered isocyanate adducts, such as the tolylene diisocyanate isomer mentioned in this example, which by reaction with trimethylolpropane contains some trifunctional isocyanate (100 parts Tolylene diisocyanate per 10 parts of trimethylolpropane) contain.

Example 2

50

It is the effect of various activating residues, ie O, OH, N and S, in connection with the soluble carboxylic acid salts of Sb (III), Pb (II), Sn (II), Bi (III) and Hg (II) of Example 1 explains. Drawings I through VIII show how various alcohols containing an activating group are reacted with a hindered diisocyanate which has some trifunctional substance (as is necessary to form useful solid polyadducts) in the presence of various soluble carboxylic acid metal salts, which are the salts are those mentioned in Example 1. The reaction mixtures were prepared from equimolar amounts of hydroxyl and isocyanate groups f> 5 (except in the case of drawings I and II, "where there are two hydroxyl groups per isocyanate group), with 0.1 molar solutions in dioxane being prepared. The catalysts were in the same The manner and amount added as in Example 1. The temperature rise in all examples, unless otherwise stated, is approximately at room temperature (25 ^° C.). "

As can be seen from the drawings I to VIII, the mixtures, the catalyzing Pb, Sn, Contain Bi, Sb and Hg salts, more reactive than the mixtures, the cobalt, manganese and "iron salts" included, although the order of these catalyzing salts with the nature of the terminal alcohol group varies.

Example 3

Ethylene glycol and durene diisocyanate, a sterically hindered diisocyanate, are reacted with one another, using 0.2 mol of ethylene glycol and 0.1 mol of diisocyanate in dioxane, which contains about 1 part of soluble metal salt catalyst per 100 parts by weight of dioxane, so as to be catalytic Explain effectiveness. Similar reaction mixtures are made using _{0.1 mol (CHskN - CH 2} - CH ₂ OH and 0.1 mol

NCO

OCH ₃

a very inert isocyanate compound. The results are shown in the table below.

The durene diisocyanate samples are designated with (a) and the o-methoxyphenyl isocyanate samples with (b). The maximum theoretical temperature rise during the reaction should be about 34 ^C C; in practice, however, a temperature rise of about 30 C indicates complete conversion.

Table 2

Measured temperature rise (a) (b) Metal salt after 6 minutes ( ⁰ C) 33 32 31 32 Pb 24 18th Bi 19th 32 Sb Sn

continuation

Measured temperature rise (a) (b) Metal salt after 6 minutes ( ⁰ C) 12th 28 14th Π Ed - 5 Co 14th - Mn - 2 Fe

With these increasingly sterically hindered isocyanate groups the lead salts within the metal salt group consistently show their good catalytic properties Effect.

Example 4

Solid polyadducts from the following, different The reaction mixture containing metal salt catalysts is converted into small, flat, open-topped Casting ladles, hardened into solid sheets and removed from the molds.

3,3'-dimethyldiphenylmethane-4,4'-diisocyanate 375 parts

CH ₂

Y \

NCO

CH,

/ 2

Polypropylene glycol MW = 1025
(1 part of trimethylolpropane for each
Containing 40 parts) 1100 parts

The difference between the readings on the when measured with the durometer The top and bottom of the sheets of the solid elastomer show to some extent the occurrence of side reactions at the exposed surface in the melting pans. These side reactions are of little concern with lead, tin and mercury salts, as well in the case of the antimony and bismuth salts, on the other hand, fall

ίο the deviations when using the cobalt, Manganese and iron salts.

All reaction mixtures hardened with the metal salt catalysts according to the invention harden at room temperature within 20 hours with the formation of tough, solid elastomers, which is not the case with other mixtures.

Similar results are obtained with reaction mixtures of tolylene diisocyanate and trimethylolpropane (10: 1) with polypropylene glycol. The catalyst cured products of the invention provide Elastomers with a reading of about 45 in the durometer and a difference of ± 3 points between the readings on the top and bottom of the molded article after 20 hours have been taken out of the molds, while those with the cobalt, manganese and iron salts cured products show differences of 20 to 35 points, while only one polyadduct that contains cobalt salt, yields one of 20 after heating in the oven for 6 hours 65 C. The results are shown in Table 4.

Table 4

In this mixture, each NCO group encounters an OH group. 1 g of metal salt catalyst is added to every 550 g of this reaction mixture. These catalyst-containing mixtures are mixed by hand and simply poured into the ladle; the samples are cured in air at room temperature; then the samples are in placed an oven to ensure that the polyadducts have their final strength properties had achieved.

45

Table 3

Hardness ("Shore A ₂ durometer") below Hardened below 32 20 hours at 32 Hardened 30th Room temperature and 30th IVICloIlSoliC 20 hours at 2C 6 hours at 20th Room temperature 34 65 = C in the oven 37 30th above 30th above 7th 30th 20th Pb octoate 30th 15th 27 24 Sn octoate 27 gelled, but closed 20th 12th Sb octoate 18th soft for one 35 Hg naphthenate 32 Measurement with 26th Bi-naphthenate 26th the hardness 15th Co-octoate 3 testing device 10 Mn-octoate 0 8th Fe (I ID-octoat

Hardness (»Shore-Aj-Durometer«) below Hardened below 40 20 hours at
Room temperature and 45 catalyst Hardened
20 hours at 44 6 hours in the oven 46 Room temperature 32 at 65 ° C 46 33 above 45 above 32 45 35 Pb octoate 35 7th 44 35 Sn octoate 40 36 44 30th Bi-naphthenate 27 gelled, yes 43 36 Hg naphthenate 17th not enough 25th Sb octoate 20th hard to the mes 20th Co-octoate 3 sung with the 8th Mn octoate 2 »Shore Ao- 0 + Fe octoate Penetrometer

Example 5

Solid, shaped, rubbery sheets were made using a number of metal salts to accelerate the hardening 'prepared at room temperature from the following reaction mixture :

6s diphenylmethane-4,4'-diisocyanate ... 340 parts

CH,

NCO

909 532/346

ίο

40 parts polypropylene glycol,)

MG = 1025 \ ...

1 part trimethylolpropane J

All parts are parts by weight.

1 g of a metal salt (see table below) is added to every 150 g of the reaction mixture. the Salt-containing reaction mixtures are then poured into open molds at room temperature, where they are remain at room temperature overnight. The shaped products are measured with a »Shore A2 penetrometer« checked for hardness. Thereafter, some products were heated to 65 ° C. for a further 6 hours and checked for their durometer hardness. Since there are several of each reaction mixture containing a salt When molded products were present, the durometer values given in the following table are average values.

Table 5

Hardness ("Shore A ₂ durometer") below Hardened below 42 20 hours at 44 Hardened 42 Room temperature and t catalyst 20 hours at 40 6 hours in the oven 43 Room temperature 37 at 65 ° C 35 35 ' above 38 above 35 42 33 Pb octoate 42 15th 39 33 Sn octoate 39 31 38 Bi-naphthenate 37 39 Hg naphthenate 37 30th Sb octoate 30th 28 Co-octoate 28 gelled Mn octoate gelled 28 Fe octoate 27

As Table 5 shows, the catalytically superior 1100 Part of the lead, tin, bismuth, mercury and antimony salts in unhindered diisocyanates Due to simple durometer measurements not as obvious as with polyadduct systems, which hindered Contain diisocyanates as a reaction partner. Containing the cobalt, manganese and iron salts Polyadducts remained sticky on their exposed surfaces, causing side reactions on the surface that does not occur with the other polyadducts. The duration of the Curing until the products are removed from the mold can be achieved with those with cobalt, manganese and Iron-hardened polyadducts differ in their shortness from those of other polyadduct systems compare those in which it has been hardened with other metal salts specified in the table is.

“Anhydrous” here means a water content of less than about 0.3 percent by weight of the polyol Understood. "Acid-free" means that the product in question is practically acid-free.

Claims (1)

Claim: Process for the production of non-cellular polyurethanes by reacting reaction mixtures obtained by reacting aromatic Diisocyanates and polymeric polyols, which mainly contain secondary hydroxyl groups, have been obtained under practically "anhydrous conditions as well as in the presence of Metal compounds as curing catalysts with shaping, characterized in that that the reaction at room temperature in the presence of a catalytic amount of a soluble salt of an organic Acid with Pb (II) or, less preferably, with Hg (II), Sn (II), Bi (III) or Sb (III). For this purpose 2 sheets of drawings