Use of carbodiimide containing compositions for controlling pot life

[0001] The invention relates to the use of compositions containing carbodiimide for controlling viability in the production of polyurethane (PU) based systems, preferably PU elastomers, PU glues, PU cast resins or PU foams.

[0002] Polyurethanes are formed as a result of polyaddition or polycondensation reactions of polyisocyanates with polyhydric alcohols, polyols, almost quantitatively. The bond is formed by reacting one isocyanate group (-N = C = O) of one molecule with a hydroxyl group (-OH) of the other molecule to form a urethane group (NH-CO-O-).

[0003] The course of the reaction between diisocyanate and polyol depends on the molar ratio of the components. Of course, intermediates with the desired average molecular weight and desired end groups can be obtained. These intermediates can then be reacted (chain elongated) with a diol or diamine, whereupon the desired polyurethane or polyurethane-polyurea hybrid is formed. Intermediates are generally referred to as prepolymers.

[0004] Suitable polyols for the preparation of prepolymers are, in addition to diols, also poly (alkylene glycol) ethers, polyether ester or polyesters with hydroxyl terminal groups (polyester polyols).

[0005] Polyester polyols are preferably used for the production of mechanically or dynamically loaded polyurethanes.

[0006] Polyetheroesters or polyesters with hydroxyl terminal groups formed by polycondensation of simple diols and carboxylic acids still contain free carboxylic acids. They catalyze the reaction between the free isocyanate groups contained in the prepolymer and the diamine necessary for chain elongation, which leads to short mixing times and causes the reaction to be uncontrolled. In addition, they often have low hydrolytic stability.

[0007] Carbodiimides currently available on the market, as disclosed in EP-A 0799843, are too slow to react in rapid acid degradation within the time necessary for the preparation of prepolymers, or because of insufficient solubility they are inadequate and uneconomical.

[0008] The object of the invention is therefore to provide compositions that are suitable for the production of polyurethane (PU) based systems, in particular for the production of PU elastomers, PU glues or PU cast resins or PU foams, which are resistant to hydrolysis and have an acceptable lifetime without requiring the use of materials that are expensive and difficult to produce.

[0009] Surprisingly, this task can be solved by the use of specific compositions containing carbodiimide.

[0010] The subject of the invention is therefore the use of compositions for controlling viability, comprising at least one polyol and at least one carbodiimide of formula (I)

R¹- (O) OC-HN- (RN = C = N-) m-NH-CO- (O) -R¹ (I), zm = 1 - 40,

R is C6-C18-alkylene or C6-C18-cycloalkylene, preferably

<img file="PL2844682T3_D0001.tif" />

or

<img file="PL2844682T3_D0002.tif" />

R¹ is C1-C4-alkyl as well as the rest - (CH2) hO - [(CH2) kO] gR², zh = 1-3, k = 1-3, g = 5-20 and R² is H or C1-C4-alkyl, preferably CH3 and at least one diisocyanate.

[0011] In another preferred embodiment of the invention, the carbodiimide used is a compound of formula (I) in which m = 10-30,

R is C6-C18-alkylene or C6-C18-cycloalkylene, preferably

<img file="PL2844682T3_D0003.tif" />

-3lub

<img file="PL2844682T3_D0004.tif" />

R¹ is C1-C4-alkyl or the residue - (CH2) hO - [(CH2) kO] gR², zh = 1-3, k = 1-3, g = 10-12 and R² is H or C1-C4-alkyl, preferably CH3. [0012] In another preferred embodiment of the invention, the carbodiimide of formula (I) is a compound in which m = 20,

R is C6-C18-alkylene or C6-C18-cycloalkylene, preferably

<img file="PL2844682T3_D0005.tif" />

or

<img file="PL2844682T3_D0006.tif" />

R¹ is the residue - (CH2) hO - [(CH2) kO] gR², zh = 2, k = 2, g = 10-12 and R² means CH3.

Preferably R has the same meaning in the carbodiimide of formula (I).

[0014] The compounds of formula (I) are those commercially available compounds which are e.g. available from the company Rhein Chemie Rheinau GmbH e.g. under the trade names Stabaxol®, Hycasyl®.

[0015] Mixtures of many carbodiimides of formula (I) are equally preferred. For a mixture, determining the average value for m can also lead to fractional numbers.

[0016] In the context of the invention, polyols are compounds that preferably have a molecular weight in (g / mol) of up to 2000, preferably in the range from 500 to 2000 and particularly preferably in the range from 500 to 1000.

[0017] The term polyol in the context of the invention here includes both compounds having two or three hydroxyl groups per molecule as well as compounds having more than three hydroxyl groups per molecule.

[0018] Preferred polyols are polyester polyols and / or polyether ester polyols, particularly preferably polyester polyols.

[0019] It is preferred if the polyol has an OH number of up to 200, preferably between 20 and 150, and particularly preferably between 50 and 115.

[0020] Polyester polyols, which are reaction products of various diols with aromatic or aliphatic dicarboxylic acids and / or lactone polymers, are particularly suitable.

[0021] Aromatic dicarboxylic acids are preferred, which can be used to form the corresponding polyester polyols. Terephthalic acid, isophthalic acid, phthalic acid, phthalic anhydride and substituted dicarboxylic acid compounds with a benzene core are particularly preferred.

[0022] Preferred aliphatic dicarboxylic acids are those that can be used to form the corresponding polyester polyols, particularly preferably sebacic acid, adipic acid and glutaric acid.

[0023] Preferred as polymers of lactones are those that can be used to form the corresponding polyester polyols, particularly preferably polycaprolactone.

[0024] Both dicarboxylic acids and lactone polymers are commercially available substances.

[0025] Also particularly preferred are those diols that can be used to form the corresponding polyester polyols, particularly very preferably ethylene glycol, butanediol, neopentyl glycol, hexanediol, propylene glycol, dipropylene glycol, diethylene glycol and cyclohexanedimethanol.

[0026] Preference is given to the reaction products of polyols of the various polyols mentioned above with aromatic or aliphatic dicarboxylic acids and / or lactone polymers (e.g. polycaprolactone).

[0027] The polyols used in the context of the invention are commercially available compounds that are available under the trade name DESMOPHEN® from Bayer MaterialScience AG.

[0028] In another embodiment of the invention, the composition further comprises at least one diisocyanate.

[0029] Aromatic and aliphatic diisocyanates are preferred as diisocyanates. Particularly preferred are toluene 2,4-diisocyanate, toluene 2,6-diisocyanate, phenyl diisocyanate, 4,4-diphenylmethane diisocyanate, methylene bis (4-phenylisocyanate), naphthalene 1.5 diisocyanate, tetramethylene diisocyanate and / or Hexamethylene diisocyanate, particularly very preferably toluene 2,4 diisocyanate and toluene 2,6 diisocyanate.

[0030] The diisocyanates used in the context of the invention are commercially available compounds that are available from Bayer MaterialScience AG under the trade name Desmodur®.

[0031] In another embodiment of the invention, the composition further comprises at least one diamine.

[0032] As diamines that are used for chain elongation, 2-methylpropyl-3,5-diamino-4-chlorobenzoate, bis- (4,4'-amino-3-chlorophenyl) methane, 3,5-dimethylthio-2, are preferred 4-toluenediamine, 3,5-dimethylthio-2,4-toluenediamine, 3,5-diethyl-2,4-toluenediamine, 3,5-diethyl-2,6-toluenediamine, 4,4'-methylene-bis- (3- chloro-2,6-diethylaniline) and 1,3-propanediol-bis (4-aminobenzoate).

[0033] In the context of the invention, the diamines used to extend the chain are commercially available compounds that are available from the company Rheinchemie Rheinau GmbH under the trade name Addolink®.

[0034] The ratio of carbodiimide to polyol is preferably 0.1-5, particularly preferably 13% by weight per 100 parts by weight of polyol.

[0035] The ratio of diisocyanate to polyol is preferably 20-50 to 100 parts by weight, particularly preferably 30 to 100 parts by weight.

[0036] In cases where the composition additionally contains at least one diamine in addition to the polyol and carbodiimide and diisocyanate, the amount of diamine is 5-30% by weight of the composition.

The invention furthermore relates to the preparation of a composition according to the invention, according to which the polyol is placed and mixed with a carbodiimide of formula (I) or a mixture of carbodiimides of formula (I).

[0038] In cases where the mixture according to the invention additionally contains diisocyanate, it is mixed with the polyol composition and at least one carbodiimide of formula (I) at temperatures from 80 to 130 ° C.

[0039] In cases where the mixture according to the invention contains, in addition to the diisocyanate, a diamine, it is mixed with the composition of the polyol and at least one carbodiimide of formula (I) and diisocyanate at temperatures in the range from 40 to 130 ° C.

[0040] The use of the previously described compositions preferably takes place preferably in PU elastomers, adhesives or cast resins to control the viability and / or as protection against hydrolytic degradation.

[0041] The scope of the invention includes all of the above mentioned definitions, below or generally in preferred ranges, residue definitions, coefficients, parameters and explanations among themselves, as well as between respective ranges and preferred ranges in any combination.

[0042] The following examples are intended to explain the invention, but are not limiting.

Examples [0043] The following examples use the following substances:

Desmophen® 2000MM, a linear polyester polyol with an OH number of 56 mg KOH / g and an acid number of 0.83 mg KOH / g from Bayer MaterialScience AG.

[0044] Carbodiimide of formula (I) with an average m of 20, R¹ = - (CH2) hO - [(CH2) kO] gR² with R²= methyl, h = 2, k = 2 and g = 10-12.

[0045] Stabaxol® P200 polymeric aromatic carbodiimide based on tetramethyloxyl diisocyanate from Rhein Chemie Rheinau GmbH.

[0046] Stabaxol® I, a monomeric carbodiimide based on 2,6-diisopropylphenylisocyanate from Rhein Chemie Rheinau GmbH.

[0047] Desmodur® T100 is 2,4-toluene diisocyanate from Bayer Material Science.

[0048] Addolink® 1604 2-methylpropyl-3,5-diamino-4-chlorobenzoate from Rhein Chemie Rheinau GmbH as the diamine component.

[0049] Carbodilite® HMV-8 CA: polymeric aliphatic carbodiimide from Nisshinbo Industries, INC.

[0050] The following mixtures were prepared as below.

[0051] Mixture A (comparison): 100g Desmophen® 2000MZ was melted at 100 ° C.

[0052] Mixture B (according to the invention): 100g of Desmophen® 2000MZ was melted at 100 ° C and mixed with 0.6 g of carbodiimide of formula (I) with an average of 20, R¹ = - (CH2) 10 - [(CH2) kO] gR² with R²= Methyl

<img file="PL2844682T3_D0007.tif" />

h = 2, k = 2 and g = 10-12.

[0053] Mixture C (comparison): 100g Desmophen® 2000MZ was melted at 100 ° C and mixed with 0.6 g of monomeric carbodiimide based on 2,6-diisopropylphenylisocyanate.

Mixture D (comparison):

[0054] 100g Desmophen® 2000MM was mixed with 0.6g Carbodilite® HMV-8 CA and stored for 24h at 30 ° C. Both substances do not mix with each other.

Therefore, this mixture could not be used in subsequent experiments.

[0055] All data are given in weight percentages unless otherwise stated.

Table 1:

<td>Shares / No mixture</td><td>Mixture AND</td><td>Mixture B</td><td>Mixture C</td><td>Desmodur.RTM T100</td><td>Addolink 1604</td>

<td>I (V)</td><td>100</td><td></td><td></td><td>21</td><td>16:16</td>

<td>II (according to invention)</td><td></td><td>100</td><td></td><td>21</td><td>16:16</td>

<td>III (V)</td><td></td><td></td><td>100</td><td>21</td><td>16:16</td>

<td colspan="6">V = comparative example, according to the invention = according to the invention</td>

[0056] Mixtures A to C were reacted at 80 ° C with the amounts of Desmodur® T 100 given in Table 2, to an isocyanate content of 5%, followed by the Addolink® 1604 chain extender with the amounts given in Table 2. With yet after a few minutes to the liquid, gelling liquid to the solid elastomer mixture, the viability was determined. Vitality is the time between mixing a multi-constituent substance and the end of processability. The marked values ​​are shown in Table 2.

Table 2:

<td>Mixture</td><td>Lifetime in seconds</td>

<td>AND</td><td>240</td>

<td>II</td><td>420</td>

<td>III</td><td>340</td>

Interpretation of experiment results:

[0057] From the value for mixture II it is clearly seen that the mixture with the carbodiimide according to the invention of formula (I) with an average m of 20, R¹ = - (CH2) 10 - [(CH2) kO] gR²with R²= methyl, l = 2, k = 2 and g = 10-12, leads to a significantly longer mixing time and thus to improved processability.