Functionalized copolymer rubber containing nitrile groups

Abstract

The present invention relates to functionalized copolymer rubbers containing nitrile groups and to the preparation thereof, to vulcanizable mixtures comprising functionalized copolymer rubbers containing nitrile groups and to the preparation thereof, and to vulcanizates based on functionalized copolymer rubbers containing nitrile groups, to the preparation thereof and to the use thereof as technical material.

Claims

1. A functionalized copolymer rubber containing nitrile groups, the rubber comprising: 10% to 60% by weight of an ,-ethylenically unsaturated nitrile units, 31% to 89% by weight of a conjugated diene units, and 1% to 9% by weight of at least one ,-ethylenically unsaturated monomer units containing carbonyl groups, wherein, the ,-ethylenically unsaturated monomer units comprise: units of the general formula (I) ##STR00004## where R.sup.1 is hydrogen, branched or unbranched C1-C18-alkyl, aryl, cycloalkyl, cyanoalkyl, hydroxyalkyl, aminoalkyl, or polyethylene glycol radical, R.sup.2, R.sup.3 and R.sup.4 are each independently hydrogen, methyl or ethyl, A is CH.sub.2, and n is 1 to 18, wherein the rubber has a glass transition temperature lower than 20 C., and an oil swelling of not more than 20%.

2. The functionalized copolymer rubber according to claim 1, wherein the conjugated diene units have a level of hydrogenation of 50% or more.

3. The functionalized copolymer rubber according to claim 1, wherein the , -ethylenically unsaturated nitrile units are derived from at least one component of the group consisting of: acrylonitrile, methacrylonitrile, ethacrylonitrile, and mixtures thereof.

4. The functionalized copolymer rubber according to claim 1, wherein the conjugated diene units are derived from at least one component of the group consisting of: 1,3-butadiene, isoprene, 2,3-dimethylbutadiene, 1,3-pentadiene (piperylene), and mixtures thereof.

5. A process for preparing the functionalized copolymer rubbers according to claim 1, the process comprising: functionalizing a functionalizable copolymer rubber containing carbonyl groups and nitrile groups with alcohols, epoxides or amines, to provide an intermediate rubber, and hydrogenating the intermediate rubber.

6. A process for preparing the functionalized copolymer rubbers according to claim 1, the process comprising: hydrogenating a functionalizable copolymer rubber containing carbonyl groups and nitrile groups, to produce an intermediate rubber, and functionalizing the intermediate rubber with alcohols, epoxides or amines.

7. A vulcanizable mixture comprising the functionalized copolymerized rubbers according to claim 1 and at least one crosslinker.

8. A process for producing vulcanizable mixtures according to claim 7, the process comprising mixing the functionalized copolymerized rubber with the at least one crosslinker.

9. A process for producing vulcanizates comprising functionalized copolymer rubbers containing nitrile groups, the process comprising vulcanizing the vulcanizable mixtures according to claim 7 at a temperature of 100 C. to 200 C.

10. A vulcanizate comprising the functionalized copolymerized rubbers according to claim 1.

11. A moulding produced by the process according to claim 9.

12. The functionalized copolymer rubber according to claim 1, wherein: the rubber comprises: 20% to 50% by weight of the , -ethylenically unsaturated nitrile units, 42% to 78.75% by weight of the conjugated diene units, and 1.5% to 8% by weight, of the at least one , -ethylenically unsaturated monomer units containing carbonyl groups, the glass transition temperature is lower than 23 C., and the oil swelling is not more 18%.

13. The functionalized copolymer rubber according to claim 12, wherein: the conjugated diene units have a level of hydrogenation of 75% or more, and the conjugated diene units are derived from at least one component of a group consisting of 1,3-butadiene, isoprene, 2,3-dimethylbutadiene, 1,3-pentadiene (piperylene), and mixtures thereof, and the , -ethylenically unsaturated nitrile units are derived from at least one component of a group consisting of acrylonitrile, methacrylonitrile, ethacrylonitrile, and mixtures thereof.

14. The functionalized copolymer rubber according to claim 1, wherein: the rubber comprises: 34% to 43% by weight of the ,-ethylenically unsaturated nitrile units, 49% to 64.5% by weight of the conjugated diene units, and 1.5% to 8% by weight of the at least one , -ethylenically unsaturated monomer units containing carbonyl groups, the glass transition temperature is lower than 25 C., and the oil swelling is not more 15%.

15. A functionalized copolymer rubber containing nitrile groups, the rubber comprising: 10% to 60% by weight of an ,-ethylenically unsaturated nitrile units, 31% to 89% by weight of a conjugated diene units, and 1% to 9% by weight of at least one ,-ethylenically unsaturated monomer units containing carbonyl groups, wherein: the conjugated diene units have a level of hydrogenation of 85% or more, and the conjugated diene units are derived from 1,3-butadiene, the ,-ethylenically unsaturated nitrile units are derived from acrylonitrile, and the , -ethylenically unsaturated monomer units containing carbonyl groups are those of the general formula (I) ##STR00005## where R.sup.1 is hydrogen, methyl, ethyl, branched or unbranched butyl or 2-ethylhexyl, C.sub.6-C.sub.14-aryl, C.sub.3-C.sub.18-cycloalkyl, C.sub.1-C.sub.18-cyanoalkyl, C.sub.1-C.sub.18-hydroxyalkyl, C.sub.1-C.sub.18 aminoalkyl, methoxy or ethoxy polyethylene glycol radical having 1 to 7 repeat ethylene glycol units, R.sup.2, R.sup.3 and R.sup.4 are each independently hydrogen, methyl or ethyl, A is CH.sub.2, and n is 1.

16. The functionalized copolymer rubber according to claim 15, wherein: the rubber comprises: 34% to 43% by weight of the ,-ethylenically unsaturated nitrile units, 49% to 64.5% by weight of the conjugated diene units, and 1.5% to 8% by weight of the at least one a,-ethylenically unsaturated monomer units containing carbonyl groups, and the rubber has a glass transition temperature lower than 25 C., and an oil swelling of not more 15%.

Description

EXAMPLES

(1) Test Methods

(2) The nitrogen content for determination of the ACN content in the copolymer rubbers containing nitrile groups is determined to OS 01960 by LECO TruSpec. Combustion of the sample weighed out in the CHN machine at about 950 C. in pure oxygen, aliquoting of the combustion gases, absorption of the disruptive components and detection of N.sub.2 by TCD (thermal conductivity measurement cell).

(3) The RDB content (residual double bond content) in % is determined by the following FT-IR measurement the IR spectra of the copolymer rubber containing nitrile groups before, during and after the hydrogenation are recorded by means of an IR instrument of the Thermo Nicolet FT-IR spectrometer, AVATAR 360 type. For this purpose, a monochlorobenzene solution of the copolymer rubber containing nitrile groups is applied to an NaCl disc, dried to a film and analysed. The hydrogenation level is determined by means of FT-IR analysis by the ASTM D 567095 method.

(4) The values for the Mooney viscosity (ML1+4@100 C.) are determined in each case by means of a shearing disc viscometer in accordance with DIN 53523/3.

(5) The conversion of the HNBR was checked via 1H NMR measurements. The measurements were conducted in 1,1,2,2-tetrachloroethane-d2 with 128 scans and a delay of 5 seconds on a Bruker DPX400. The incorporation was calculated from the integrals over the appropriate signals.

(6) The molecular weight was determined by gel permeation chromatography (GPC). A modular system was used, having a Shodex RI-71 differential refractometer, S 5200 autosampler (from SFD), column oven (ERC-125), Shlmadzu LC 10 AT pump and a column combination of 3 mixed-B columns from Polymer Labs. The solvent used was tetrahydrofuran; the molecular weights present are based on polystyrene standards from PSS (Mainz). The measurements were conducted at 40 C. and a flow rate of 1 ml/min in tetrahydrofuran.

(7) The molecular parameters such as number-average molecular weight M.sub.n, mass-average molecular weight M.sub.w and the resulting polydispersity index PDI were determined from the RI signal by means of the Empower 2 data base software from Waters.

(8) The glass transition temperature of the copolymer rubber containing nitrile groups was obtained with the aid of a DSC measurement. For this purpose, between 10 and 15 mg of sample were weighed into an aluminium boat and sealed. The boat was heated up twice from 100 C. to 100 C. at a heating rate of 20 K/minute in a Mettler Toledo DSC 821e/STAR SW 11.00 DSC instrument. The glass transition temperature was determined from the second heating curve by the standard method for finding the mean value.

(9) The vulcanization characteristics of the rubber mixtures were determined by monitoring the torque as a function of vulcanization time in a moving die rheometer (MDR 2000E), measuring at an angle of 0.5 and an oscillation frequency of 1.7 Hz at 180 C. for 30 minutes.

(10) For the tensile testing, 2 mm plaques were produced by vulcanization of the vulcanizable mixture at 180 C. The dumbbell-shaped test specimens were punched out of these plaques and tensile strength and elongation were determined to ASTM D2240-81.

(11) Hardness was determined with a durometer to ASTM D2240-81.

(12) To determine oil swelling, dumbbell-shaped test specimens as used for the tensile testing were stored in IRM 903 oil in a closed vessel at 150 C. for 7 days. Thereafter, the samples were measured and weighed, and the volume swelling and increase in mass were determined. Subsequently, tensile strength and elongation were determined to ASTM D2240-81.

(13) The abbreviations given in the tables below have the following meanings: RT room temperature (232 C.) S min is the minimum torque of the crosslinking isotherm S max is the maximum torque of the crosslinking isotherm delta S is S maxS min TS1 is the time by which the Mooney viscosity has increased by one unit after the Mooney viscosity minimum has been attained, compared to the starting point TS2 is the time by which the Mooney viscosity has increased by two units after the Mooney viscosity minimum has been attained, compared to the starting point t 50 is the time when 50% of S max is attained t 90 is the time when 90% of S max is attained t 95 is the time when 95% of S max is attained M 10 modulus at 10% elongation, measured at RT M 25 modulus at 25% elongation, measured at RT M 50 modulus at 50% elongation, measured at RT M 100 modulus at 100% elongation, measured at RT M 300 modulus at 300% elongation, measured at RT EB elongation at break, measured at RT TS tensile strength, measured at RT H hardness, measured at RT

(14) The Following Substances were Used in the Examples:

(15) The following chemicals were purchased as commercial products from the companies specified in each case, or originate from production plants of the companies specified. monochlorobenzene Merck, purity 99% methanol Azelis diethylene glycol methyl ether Merck, purity 98% triethylene glycol ethyl ether Sigma Aldrich, technical grade product methoxy polyethylene glycol (mPEG 7) Sigma Aldrich, commercial product having 7 ethylene glycol units methoxy polyethylene glycol (mPEG 11) BASF (Pluriol A520E), technical grade product, 11 ethylene glycol units methoxy polyethylene glycol (mPEG 16) BASF (Pluriol A750E), technical grade product, 16 ethylene glycol units butyl glycidyl ether Merck, purity 95% ethylhexyl glycidyl ether Sigma Aldrich, purity 98% 1-decanol Merck, purity 99% 1-pentanol VWR, technical grade product 3,7-dimethyl-1-octanol Sigma Aldrich, purity 98% 3-methyl-1-butanol Sigma Aldrich, purity 98% pyridine VWR, purity 99.7% 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) Merck, synthesis quality methanesulphonic acid Merck, purity 299% polycarboxylic acid Orothan; Rohm and Haas Europe Trading APS

(16) Other Substances Used in the Vulcanizable Composition: Corax N330: carbon black, commercially available from Orion Engineered Carbons Rhenofit DDA: 70% masterbatch based on octylated diphenylamine, produced by Rheinchemie Vulkanox ZMB2/C5: zinc salt of 4- and 5-methyl-2-mercaptobenzothiazole, commercially available from Lanxess Perkadox 14-40: di(tert-butylperoxyisopropyl)benzene 40% supported on silica, commercially available from Akzo Nobel Polymer Chemicals BV TAIC: triallyl isocyanurate, 70% masterbatch, commercially available from Kettlitz Chemie GmbH & Co KG. Maglite: magnesium oxide, commercially available from CP Hall.

(17) Hydrogenated Functionalizable Copolymer Rubbers Containing Carbonyl Groups and Nitrile Groups Used:

(18) As basis, two different HNBRs were used.

(19) HNBR_V1: ACN content of 34% by weight, methacrylic acid content of 4.6% by weight, residual double bond content of 3.5%, Mooney viscosity ML(1+4, 100 C.) of 77. The glass transition temperature of the polymer was 19.6 C.

(20) HNBR_V2: ACN content of 34.6% by weight, methacrylic acid content of 5.2% by weight, residual double bond content of 0.3%, Mooney viscosity ML(1+4, 100 C.) of 95.8. The glass transition temperature of the polymer was 25.5 C.

(21) I Preparation of the Functionalized Copolymer Rubbers Containing Nitrile Groups

(22) I.a Esterification of Functionalizable Copolymer Rubber Containing Carbonyl Groups and Nitrile Groups with Alcohols in Solution

(23) The rubber is dissolved in monochlorobenzene in a concentration of 7% by weight on an agitator platform. The solution is initially charged in a two-neck flask with condenser, and an excess of the alcohol based on the carboxyl groups to be converted is added. The mixture is heated while stirring. As catalyst, methanesulphonic acid diluted in monochlorobenzene is added to the hot solution, and the reaction mixture is refluxed for 4 to 6 hours. The results of the experiments with HNBR_V1 are shown in Table 1, the results with HNBR_V2 in Table 2.

(24) TABLE-US-00001 TABLE 1 Esterification of HNBR_V1 with alcohols in chlorobenzene solution Amount Amount Incor- Experiment of of Time porated Tg number Reagent reagent acid [h] [% by wt.] [ C.] #1 Diethylene 3 eq 2.9 eq 4 5.5 22 glycol methyl ether #2 Triethylene 3 eq 2.9 eq 4 5.1 25 glycol ethyl ether #3 mPEG7 3 eq 2.9 eq 4 8.0 25 #4 mPEG11 3 eq 0.8 eq 6 5.1 24 #5 mPEG11 5 eq 1.4 eq 6 6.0 28 #6 mPEG11 10 eq 1.4 eq 6 8.5 28 #7 mPEG16 3 eq 2.9 eq 4 8.2 22

(25) TABLE-US-00002 TABLE 2 Esterification of HNBR_V2 with alcohols in chlorobenzene solution Amount Amount Incor- Experiment of of Time porated Tg number Reagent reagent acid [h] [% by wt.] [ C.] #8 mPEG11 3 eq 2.9 eq 4 4.9 28 #9 mPEG11 5 eq 2.9 eq 6 3.8 27 #10 mPEG11 5 eq 1.4 eq 6 5.6 28

(26) I.b Esterification of Functionalizable Copolymer Rubber Containing Carbonyl Groups and Nitrile Groups with Epoxides in Solution

(27) The rubber is dissolved in monochlorobenzene in a concentration of 7% by weight on an agitator platform. The solution is initially charged in a two-neck flask with condenser, and an excess of the epoxide based on the carboxyl groups to be converted and of a non-nucleophilic base are added. The mixture is heated while stirring and the reaction mixture is refluxed for 6 hours. The results are listed in table 3.

(28) TABLE-US-00003 TABLE 3 Reaction of HNBR 1 with epoxides in chlorobenzene solution Amount Amount Incor- Experiment of of porated Tg number Reagent reagent base base [% by wt.] [ C.] #11 ethylhexyl 3 eq pyridine 5 eq 9.6% 28 glycidyl ether #12 butyl 3 eq DBU 5 eq 9.4% 24 glycidyl ether #13 butyl 3 eq pyridine 5 eq 8.0% 25 glycidyl ether

(29) Workup of the Polymer Solution by Reprecipitation

(30) After the reaction time has elapsed, the polymer solution is poured into a large excess of methanol while stirring and thus precipitated. The methanol was squeezed out of the material precipitated on an aluminium plate and the solid was dissolved again in monochlorobenzene on the agitator platform. The precipitation was repeated twice and the solid obtained was dried to constant weight in a vacuum drying cabinet at 55 C.

(31) II Production of Vulcanizates of the Hydrogenated Functionalized Copolymer Rubber Containing Nitrile Groups:

(32) Production of the Vulcanizable Mixtures:

(33) TABLE-US-00004 TABLE 4 Properties of the copolymer rubbers containing nitrile groups HNBR 1* HNBR 2* Experi- Experi- Invention ment #4 ment #5 ACN content [% by wt.] 32.6 32.6 Functionalized monomer unit [% by wt.] 5.1 6 Glass transition temperature Tg [ C.] 24 28 HNBR 3 Comparison Therban 3407 ACN content [% by wt.] 34 Functionalized monomer unit [% by wt.] 0 Glass transition temperature Tg [ C.] 24

(34) TABLE-US-00005 TABLE 5 Compositson of the vulcanizable mixtures (inventive functionalized copolymer rubbers containing nitrile groups were indicated with an asterisk*) Example 1* 2* 3 Rubber parts parts parts HNBR 1* 100 HNBR 2* 100 HNBR 3 100 Other components phr phr phr CORAX N330 30 30 30 RHENOFIT DDA 1.4 1.4 1.4 VULKANOX ZMB2/C5 0.4 0.4 0.4 PERKADOX 14-40 7 7 7 TAIC 70% 1.5 1.5 1.5 MAGLITE 2 2 2

(35) All the test mixtures were produced on a mixing roll mill. The diameter of the rolls was 80 mm, the length 200 mm. The rolls were preheated to 40 C.; the speed of the front roll was 16.5 rpm, that of the rear roll 20 rpm, which achieved a friction of 1:1.2.

(36) The rubber was initially charged and mixed for one (1) minute until a smooth milled sheet had formed. Subsequently, first the carbon black, then the additives and finally the crosslinking chemicals were mixed in. The total mixing time was 5 to 8 minutes.

(37) TABLE-US-00006 TABLE 6 Crosslinking density of the vulcanizates MDR 180 C. 1* 2* 3 S min dNm 4.37 3.33 1.41 S max dNm 16.74 14.21 20.71 S end dNm 16.74 14.21 20.64 delta S dNm 12.37 10.88 19.3 TS 1 s 46 31 32 TS 2 s 58 41 41 t 50 s 121 86 117 t 90 s 351 260 330 t 95 s 487 350 426

(38) TABLE-US-00007 TABLE 7 Physical properties of the unaged vulcanizates Tensile test 1* 2* 3 2 mm plaques vulcanized at 180 C. for 10 minutes M 10 MPa 1 0.7 0.6 M 25 MPa 2 1.4 1 M 50 MPa 3.5 2.3 1.4 M 100 MPa 8 5 2.8 M 300 MPa 23.8 EB % 262 242 322 TS MPa 35 23 27 H ShA 75 70 62

(39) TABLE-US-00008 TABLE 8 Physical properties of the hot air-aged vulcanizates (n.d = not determined) Tensile test 1* 2* 3 Ageing of the vulcanizates in hot air, 168 h at 150 C. M 10 MPa (n.d.) 1.3 0.8 M 25 MPa (n.d.) 2.7 1.4 M 50 MPa (n.d.) 5.4 2.1 M 100 MPa (n.d.) 11.8 4.8 M 300 MPa (n.d.) EB % (n.d.) 230 261 TS MPa (n.d.) 30.1 23.7 H ShA (n.d.) 81 69

(40) TABLE-US-00009 TABLE 9 Change in the physical properties of the vulcanizates before and after ageing in hot air Change 1* 2* 3 Ageing of the vulcanizates in hot air, 168 h at 150 C. EB % (n.d.) 5 19 TS % (n.d.) 30 12 H ShA (n.d.) 11 8

(41) TABLE-US-00010 TABLE 10 Ageing of the vulcanizates in IRM 903 Tensile test 1* 2* 3 Ageing of the vulcanizates in IRM 903, 168 h at 150 C. M 10 MPa 0.8 0.8 0.4 M 25 MPa 1.9 1.6 0.8 M 50 MPa 3.9 3.1 1.3 M 100 MPa 10.4 7.7 3 M 300 MPa EB % 192 217 233 TS MPa 29.3 28.3 16.3 H ShA 73 74 54

(42) TABLE-US-00011 TABLE 11 Change in the physical properties of the vulcanizates before and after ageing in IRM 903 Change 1* 2* 3 Ageing of the vulcanizates in IRM 903, 168 h at 150 C. EB % 27 10 28 TS % 17 13 39 H ShA 2 4 8 V % 15 8 21

(43) Oil swelling is much improved in the vulcanizates based on the inventive functionalized copolymer rubbers containing nitrile groups, 1* and 2*, compared to the vulcanizates based on HNBR 3.