Hydrolysis-stable thermoplastic polyurethanes, manufacturing process and uses thereof

Abstract

The present invention relates to: (a) at least one carbodiimide (b) sulfonate esters, and (c) Thermoplastic polyurethane The present invention relates to a composition comprising the compound, as well as a process for its manufacture and use.

Description

[Technical Field]

[0001] The present invention relates to the technical field of thermoplastic polyurethanes, their production and their use. [Background technology]

[0002] Thermoplastic polyurethane elastomers (hereinafter abbreviated as TPU) have been known for a long time. Their industrial importance is based on the combination of high levels of mechanical properties with the advantage of cost-effective thermoplastic processability. By using different chemical forming components, it is possible to achieve a wide range of variations in mechanical properties.

[0003] An overview of TPU, its properties, production and applications is described, for example, in (Non-Patent Document 1).

[0004] TPU can be produced continuously or batchwise by various processes, the best known processes also used industrially are those known as the belt process, e.g., according to US Pat. No. 5,623,491, and the extruder process, e.g., according to US Pat. No. 5,623,491.

[0005] TPUs are typically formed from linear polyhydroxy compounds, aromatic diisocyanates and diols.

[0006] These hardnesses are controlled by the content of what are known as hard segments, which consist essentially of diisocyanate-diol segments. By appropriately selecting the molar ratios of the forming components, it is easy to produce TPUs with hardnesses ranging from Shore A 85 to Shore D 74. In theory, TPUs with a Shore A hardness of less than 85 can be obtained by the same method, but the drawback is that the product is difficult to handle during production because it is very difficult to solidify and cure.

[0007] In many applications, plasticizers are added to thermoplastic polyurethanes to improve the properties of the molded articles. Many of these plasticizers are ester-based, but they also impair the hydrolysis resistance of the polymer.

[0008] Patent Document 3 discloses that this negative effect can be largely offset by adding a carbodiimide to an ester-based plasticizer selected from the group consisting of citrate esters, acetyl citrate esters, phthalate esters, benzoate esters, adipate esters, hydrogenated phthalate esters, and phosphate esters.

[0009] Patent Documents 4 and 5 disclose compositions containing a polyester-based NCO prepolymer having urethane groups, a monomeric aromatic carbodiimide (Stabaxol I: bis(2,6-diisopropylphenyl)carbodiimide), and ethyl p-toluenesulfonate.

[0010] In general, carbodiimides have been proven to be effective hydrolysis stabilizers for thermoplastics, including thermoplastic ester-based polyurethanes. However, carbodiimides are very expensive and have the drawback of decomposing or generating toxic gases (emission of isocyanates) during processing at relatively high temperatures. Therefore, there has been a need for compositions with improved hydrolysis resistance that allow for reduced amounts of carbodiimide to be used while maintaining the hydrolysis resistance of the polymer. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] GB Patent Application Publication No. 1 057 018A [Patent Document 2] U.S. Patent No. 3,642,964 [Patent Document 3] European Patent No. 3099725B1 [Patent Document 4] U.S. Patent Application Publication No. 2020071486A1 [Patent Document 5] European Patent Application Publication No. 0381897A1 [Non-patent literature]

[0012] [Non-Patent Document 1] Hans-Georg Wussow: “Thermoplastic Elastomers”, Ullmann's Encyclopedia of Industrial Chemistry, Electronic Release, 7th ed., chap.2 “Thermoplastic Polyurethane Elastomers”, Wiley-VCH, Weinheim 2004 Summary of the Invention [Problem to be solved by the invention]

[0013] Therefore, the present invention aimed to provide a thermoplastic polyurethane composition that has improved hydrolysis resistance and / or that allows the amount of carbodiimide used to be reduced while maintaining the same hydrolytic stability. [Means for solving the problem]

[0014] Here, surprisingly, the purpose is to use the following ingredients: (a) at least one carbodiimide selected from the group consisting of oligomeric aliphatic carbodiimides, polymeric aliphatic carbodiimides, oligomeric aromatic carbodiimides, and polymeric aromatic carbodiimides; (b) C2~C 20 -sulfonic acid esters of alkyl mono- or disulfonic acids with unsubstituted or C1- to C4-alkyl- and / or halogen-substituted phenols; and (c) Thermoplastic polyurethane It has been found that this can be achieved by a composition comprising:

[0015] Component (a) is a carbodiimide of formula (I) R 2 -R 1 -(-N=C=NR 1 -) n -R 2 (I) (In the formula, n corresponds to an integer between 2 and 500, preferably between 2 and 100, more preferably between 3 and 20, and very particularly preferably between 4 and 10, R 1 is C1~C 24 -Alkylene, C5-C 12 -Cycloalkylene, C1-C 12 -Alkyl-substituted or C1-C 24 -Oxyalkyl-substituted C6-C 12 -Cycloalkylene, C7-C 24 -aryl alkylene, C1-C 12 -Alkyl-substituted C6-C 10 -Arylene, C7~C 18 -Alkylaryl-substituted C6-C 10 -arylene and optionally bridged via an alkylene group and having a total of 8 to 30 carbon atoms, 12 -Alkyl-substituted C6-C 10 -arylene and / or C-C 10 -arylene, R 2 -H, -NCO, -NHCONHR 3 , -NHCONR 3 R 4 or -NHCOOR 5 and where: R 3 and R 4 are equal or different, and C1 to C 12 -Alkyl, C6-C 12 -Cycloalkyl, C7-C 18 represents an aralkyl or aryl group, and R 5 is C1~C 22 -Alkyl, C6-C 12-Cycloalkyl, C6-C 18 -aryl or C7-C 18 - aralkyl groups and unsaturated alkyl or alkoxypolyoxyalkylene groups having 2 to 22 carbon atoms, preferably of the formula: -(CH2CH2O) m -CH3 (where m=1 to 20) corresponds to a methoxylated polyethylene glycol group The use of is preferred.

[0016] Component (a) is: R 1 is C1~C 12 -Alkyl-substituted C6-C 10 -Arylene, C7~C 18 -Alkylaryl-substituted C6-C 10 -arylene and optionally bridged via an alkylene group and having a total of 8 to 30 carbon atoms, 12 -Alkyl-substituted C6-C 10 -arylene and / or C6-C 10 -arylene, and R 2 is H or -NHCOOR 5 Represents Carbodiimides are particularly preferably usable.

[0017] Component (a) is: R 1 is C1-C6-alkyl-substituted C6-C 10 -arylene and / or C6-C 10 -arylene, R 2 NHCOOR 5 and R 5 has the formula: -(CH2CH2O) m -CH3 (wherein m=1 to 20) represents a methoxylated polyethylene glycol group Carbodiimides are more preferred.

[0018] C1-C optionally bridged via alkylene groups and having a total of 8 to 30 carbon atoms 12-Alkyl-substituted C6-C 10 Arylene has the general structure -alkylene-arylene-alkylene-, where the alkylene group can be straight or branched, and the arylene group is C1-C 12 - may have up to four alkyl substituents, provided that the total number of carbon atoms does not exceed 30.

[0019] Here, the arylene group is bridged via an alkylene group, does not have an alkyl group on the arylene group, and each of the two alkylene groups has 1 to 6 carbon atoms. 10 -Arylenes are preferred.

[0020] Component (a) is R 1 represents -C(CH3)2-C6H4-C(CH3)2-, and R 5 has the formula: -(CH2CH2O) m Carbodiimides representing methoxylated polyethylene glycol groups of -CH3 (where m=1-20) are most preferred.

[0021] Component (b) is C 12 ~C 18 Sulfonic acid esters of alkyl mono- or disulfonic acids with unsubstituted or C1- to C4-alkyl- and / or halogen-substituted phenols are preferably used.

[0022] Component (b) is C 12 ~C 18 Sulfonic acid esters of alkyl mono- or disulfonic acids with unsubstituted or C1- to C4-alkyl- or halogen-substituted phenols are particularly preferably used.

[0023] Component (b) is C 14 ~C 17 Sulfonic acid esters of alkyl mono- or disulfonic acids with phenols are most preferably used.

[0024] The weight ratio of component (a) to component (b) in the composition according to the present invention is preferably 30:70 to 70:30, particularly preferably 40:60 to 60:40, and most preferably 50:50.

[0025] The weight ratio of component (a) to thermoplastic polyurethane in the composition according to the present invention is preferably 2:1000 to 25:1000, particularly preferably 5:1000 to 10:1000, and most preferably 7:1000 to 8:1000.

[0026] Preferably, the NCN content (carbodiimide group content) in the composition according to the present invention is 1 to 10% by weight, preferably 2 to 8% by weight, particularly preferably 3 to 7% by weight, based on the total amount of carbodiimide and alkylsulfonic acid ester. DETAILED DESCRIPTION OF THE INVENTION

[0027] The present invention further provides a process for producing a thermoplastic polyurethane composition, wherein component (a) and component (b) are added to a reaction mixture for producing a thermoplastic polyurethane, and the thermoplastic polyurethane is then formed by polymerization of the reaction mixture.

[0028] In a preferred embodiment, components (a) and (b) are first mixed and then this mixture is added to the reaction mixture for the production of the thermoplastic polyurethane.

[0029] In a preferred embodiment, component (a) is R 2 A carbodiimide of formula (I) is used which does not have an NCO function as a radical.

[0030] If the composition is added to the reaction mixture, this can in principle be done at any stage in the process for producing the thermoplastic polyurethane.

[0031] In an alternative embodiment, component (a) and component (b) are blended with a thermoplastic polyurethane.

[0032] If the mixture of components (a) and (b) is added to a thermoplastic polyurethane that has already been substantially fully reacted, this can be done, for example, by blending in or by swelling incorporation.

[0033] The invention further provides a shaped body, especially in the form of a roller, conveyor belt or membrane, comprising the composition according to the invention.

[0034] The scope of the present invention encompasses all definitions of radicals, indices, parameters and explanations hereinabove or below, in general terms or preferred ranges, including their combination with one another, i.e., any combination between the respective ranges and preferred ranges.

[0035] The following examples are intended to illustrate the present invention without, however, having a limiting effect. [Example]

[0036] Carbodiimide (CDI): A polycarbodiimide of formula (I), wherein R 1 = m-tetramethylxylene, R 2 =NHCOOR 5 , R 5 =-(C2H5O) m -CH3, n = about 4-5, m = about 11, and an NCN content of about 7 wt%. To determine the NCN content, the NCN groups were reacted with oxalic acid added in excess, and then the unreacted oxalic acid was subjected to potentiometric back titration with sodium methoxide, taking into account the blank value of the system.

[0037] Monomeric carbodiimide (CDI * ): Monomeric carbodiimide bis(2,6-diisopropylphenyl)carbodiimide and an NCN content of about 11% by weight. To determine the NCN content, the NCN groups were reacted with oxalic acid added in excess, and then the unreacted oxalic acid was subjected to potentiometric back titration with sodium methoxide, taking into account the blank value of the system.

[0038] Ester(I): Secondary C 14 ~C 17 alkyl sulfonates containing alkyl mono- or disulfonates and phenol (Mesamoll® from Lanxess Deutschland GmbH) Ester (II): Tri-n-butyl citrate (Uniplex 83 from Lanxess Deutschland GmbH) Thermoplastic polyurethane (TPU): Desmopan® 2587 A from Covestro AG

[0039] Hydrolytic stabilization in thermoplastic polyurethanes (TPUs) To evaluate the hydrolysis stabilization effect in TPU, polycarbodiimides or compositions composed of esters and polycarbodiimides (with a weight ratio of ester to polycarbodiimide of 1:1) were dispersed in TPU using a Werner & Pfleiderer ZSK 25 laboratory twin-screw extruder, after which the following measurements were carried out: F3 standard specimens used for measuring tear strength were then produced from the resulting pellets using an Arburg Allrounder 320 S 150-500 injection molding machine.

[0040] For the hydrolysis test, these F3 standard specimens were stored in water at a temperature of 90°C and their tear strength was measured in MPa. The results are shown in Table 1.

[0041] [Table 1]

[0042] The results in Table 1 show that the composition according to the invention makes it possible to reduce the proportion of carbodiimide in the TPU by at least 25%, whereas the esters known from the prior art do not show any improvement here.

[0043] [Table 2]

[0044] The results in Table 2 show that the monomeric carbodiimide in combination with ester (I) is not able to reduce the proportion of carbodiimide in the TPU.

Claims

1. (a) at least one carbodiimide selected from the group consisting of oligomeric aliphatic carbodiimides, polymeric aliphatic carbodiimides, oligomeric aromatic carbodiimides, and polymeric aromatic carbodiimides; (b) C ２ ~C ２０ - alkyl mono- or disulfonic acid and unsubstituted or C １ - C ４ sulfonic acid esters with alkyl- and / or halogen-substituted phenols; and (c) Thermoplastic polyurethane A composition comprising:

2. The carbodiimide is a carbodiimide of formula (I) R ２ -R １ -(-N=C=N-R １ -) ｎ -R ２ (I) (In the formula, n is an integer between 2 and 500, preferably between 2 and 100, more preferably between 3 and 20, and very particularly preferably between 4 and 10, R １ is C １ ~C ２４ - alkylene, C ５ ~C １２ -cycloalkylene, C １ ~C １２ -alkyl-substituted or C １ ~C ２４ -oxyalkyl-substituted C ６ ~C １２ -cycloalkylene, C ７ ~C ２４ -aryl alkylene, C １ ~C １２ -Alkyl-substituted C ６ ~C １０ -Arylene, C ７ ~C １８ -alkylaryl-substituted C ６ ~C １０ - arylene, optionally bridged via an alkylene group and having a total of 8 to 30 carbon atoms; １ ~C １２ -Alkyl-substituted C ６ ~C １０ -arylene or C ６ ~C １０ represents arylene, R ２ is -H, -NCO, -NHCONHR ３ , -NHCONR ３ R ４ or -NHCOOR ５ and where: R ３ and R ４ are the same or different, and C １ ~C １２ -Alkyl, C ６ ~C １２ -cycloalkyl, C ７ ~C １８ represents an aralkyl or aryl group, and R ５ is C １ ~C ２２ -Alkyl, C ６ ~C １２ -cycloalkyl, C ６ ~C １８ -aryl or C ７ ~C １８ an aralkyl group, an unsaturated alkyl group having 2 to 22 carbon atoms, or an alkoxypolyoxyalkylene group, preferably of the formula: -(CH ２ CH ２ O) ｍ -CH ３ (wherein m=1 to 20) corresponds to a methoxylated polyethylene glycol group. The composition of claim 1 selected from:

3. 2. The composition according to claim 1, wherein the weight ratio of component (a) to component (b) is from 30:70 to 70:30, preferably from 40:60 to 60:40, particularly preferably 50:

50.

4. 2. The composition according to claim 1, wherein the weight ratio of component (a) to thermoplastic polyurethane is from 2:1000 to 25:1000, preferably from 5:1000 to 10:1000, and particularly preferably from 7:1000 to 8:1000.

5. Component (b) includes C １２ ~C １８ - alkyl mono- or disulfonic acid and unsubstituted or C １ - C ４ -sulfonic acid esters with alkyl- and / or halogen-substituted phenols, preferably C １２ ~C １８ - alkyl mono- or disulfonic acid and unsubstituted or C １ - C ４ -sulfonic acid esters with alkyl- or halogen-substituted phenols, and most preferably C １４ ~C １７ 2. The composition according to claim 1, wherein a sulfonic acid ester of an alkyl mono- or disulfonic acid with a phenol is used.

6. R １ is C １ ~C １２ -Alkyl-substituted C ６ ~C １０ -Arylene, C ７ ~C １８ -alkylaryl-substituted C ６ ~C １０ - arylene and optionally bridged via an alkylene group and having a total of 8 to 30 carbon atoms １ ~C １２ -Alkyl-substituted C ６ ~C １０ -arylene, and / or C ６ ~C １０ represents arylene, and R ２ is H or -NHCOOR ５ The composition of claim 2 , wherein

7. R １ is C １ ~C ６ -Alkyl-substituted C ６ ~C １０ -arylene and / or C ６ ~C １０ represents arylene, R ２ NHCOOR ５ represents R ５ is a compound of the formula: -(CH ２ CH ２ O) ｍ -CH ３ 3. The composition of claim 2, wherein m represents a methoxylated polyethylene glycol group of the formula:

8. R １ is -C(CH ３ ) ２ -C ６ H ４ -C(CH ３ ) ２ - and R ５ is a compound of the formula: -(CH ２ CH ２ O) ｍ -CH ３ 3. The composition of claim 2, wherein m represents a methoxylated polyethylene glycol group of the formula:

9. 9. A process for producing the composition of any one of claims 1 to 8, comprising adding component (a) and component (b) to a reaction mixture for the production of a thermoplastic polyurethane, said thermoplastic polyurethane then being formed by polymerization of said reaction mixture.

10. 10. The process for making the composition of claim 9, wherein component (a) and component (b) are first mixed and then said mixture is added to the reaction mixture for producing the thermoplastic polyurethane.

11. A process for making the composition of any one of claims 1 to 8, wherein component (a) and component (b) are blended with a thermoplastic polyurethane.

12. 12. The process for making a composition according to claim 11, wherein said blending is carried out by incorporation by compounding or by incorporation by swelling.

13. A molded body comprising the composition according to any one of claims 1 to 8.

14. 14. The molded body according to claim 13, in the form of a roller, a conveyor belt or a membrane.

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