USE OF VULCANISATES COMPRISING HNBR-PEG ACRYLATE COPOLYMER IN CONTACT WITH COOLANT

Abstract

The present invention relates to the use of a vulcanisable composition comprising HNBR-PEG acrylate copolymer for production of vulcanisates that are in contact with coolant.

The invention further relates to the use of a vulcanisate produced from a vulcanisable composition comprising HNBR-PEG acrylate copolymer as a component part, preferably as a gasket or as a hose, in contact with coolant.

Claims

1. A process for producing a vulcanizate for use in contact with a coolant, the process comprising vulcanizing a vulcanisable composition comprising: (i) at least one HNBR-PEG acrylate copolymer, and (ii) at least one peroxide compound, where the HNBR-PEG acrylate copolymer contains 10% to 35% by weight of α,β-ethylenically unsaturated nitrile units, 15% to 80% by weight of conjugated diene units, and 10% to 50% by weight of PEG acrylate units, wherein the coolant is a composition comprising water, a freezing point depressant, and a corrosion inhibitor.

2. The process according to claim 1, wherein the HNBR-PEG acrylate copolymer (i) is a hydrogenated nitrile-butadiene-PEG acrylate copolymer comprising: (a) 10% to 35% by weight of at least one α,β-ethylenically unsaturated nitrile unit, (b) 15% to 80% by weight of at least one conjugated diene unit, and (c) 10% to 50% by weight of at least one PEG acrylate unit derived from a PEG acrylate of the general formula (I) ##STR00005## where R is hydrogen or branched or unbranched C.sub.1-C.sub.20-alkyl, n is 1 to 8, and R.sup.1 is hydrogen or CH.sub.3—.

3. The process according to claim 1, wherein the at least one peroxide compound (ii) is an organic peroxide.

4. The process according to claim 1, wherein the peroxide compound (ii) is present in an amount of 1 to 20 parts by weight based on 100 parts by weight of component (i).

5. The process according to claim 1, wherein the HNBR-PEG acrylate copolymer (i) has 18% to 33% by weight of acrylonitrile monomers units, 36% to 69% by weight of 1,3-butadiene monomer units and 13% to 30% by weight of butyldiglycol methacrylate monomer units.

6. The process according to claim 1, wherein the coolant comprises: a) water, b) alkyl glycol or salts, and c) a neutralized organic acid.

7. A process of producing a component part, of which at least one vulcanisate thereof is in contact with coolant, the process comprising (A) carrying out the process according to claim 1 to produce a vucanisate; and (B) processing the vulcanisate into the component part.

8. Component part produced according to the process according to claim claim 7.

9. Cooling unit comprising at least one component part according to claim 8 and a coolant, wherein the at least one vulcanisate is in contact with the coolant ii).

Description

EXAMPLES

[0142] Storage Tests (Raw Polymer): 8 grams of raw polymer are stored in 200 ml of medium at 150° C. for 7 days.

[0143] Determination of Tg (DSC):

[0144] The glass transition temperature was obtained with the aid of a DSC measurement in accordance with ASTM E 1356-03 or in accordance with DIN 11357-2. For this purpose, between 10 mg and 15 mg of the sample were weighed into an aluminium tray and sealed. The tray was heated twice from −150° C. to 150° C. at a heating rate of 10 K/min in a DSC instrument from TA Instruments. The glass transition temperature was determined from the second heating curve by the standard mean value method.

[0145] Determination of the Gel Content in MEK:

[0146] The gel content is the proportion of the polymer insoluble in methyl ethyl ketone (MEK) at 23° C. To determine the gel content, 250 mg of the polymer are dissolved in 25 ml of MEK by shaking at 23° C. for 24 hours. After centrifugation at 20 000 rpm, the insoluble fraction is removed and dried. The gel content is calculated from the quotient of the dried residue and the starting weight and is reported in per cent by weight.

[0147] The amounts in part by weight stated in the examples are based on 100 parts by weight of the rubber (i).

[0148] MDR

[0149] The MDR (moving die rheometer) vulcanisation profile and analytical data associated therewith were measured in a Monsanto MDR 2000 rheometer in accordance with ASTM D5289-95.

[0150] Determination of Hardness (H): Shore A hardness was measured in accordance with ASTM-D2240-81.

[0151] Determination of Tensile Strength (TS) and Elongation at Break (EB):

[0152] The tensile tests for determining the strain as a function of deformation were carried out in accordance with DIN 53504 or ASTM D412-80.

[0153] Determination of Increase in Volume (ΔV; Swelling) and Mass (Δmass):

[0154] The measurement is effected at room temperature directly after the storage.

[0155] Determination of Solubility in MCB (5%):

[0156] Solubility in monochlorobenzene (MCB) is determined by dissolving 5 g of polymer in 10 ml of MCB by shaking at 23° C. for 24 hours. The distinction between soluble and insoluble is made by visual monitoring.

[0157] Determination of Butanol Content:

[0158] The butanol content in the coolant was determined by use of headspace gas chromatography. The standard addition method was used for identification of the butanol peak and quantification.

[0159] Components Used:

TABLE-US-00001 Therban ® 3407 hydrogenated nitrile rubber, ACN content: 34% by weight, Mooney viscosity ML 1 + 4 @100° C.: 70 MU, residual double bond content: max. 0.9%, available from ARLANXEO Deutschland GmbH. Therban ® LT 1707 VP butyl acrylate-containing, hydrogenated nitrile rubber, ACN content: 17% by weight, Mooney viscosity ML 1 + 4 @100° C.: 74 MU, residual double bond content: max. 0.9%, available from ARLANXEO Deutschland GmbH. HNBR-PEG acrylate 1 PEG acrylate-containing, hydrogenated nitrile rubber (termonomer = methoxyethyl acrylate), ACN content: 20% by weight, Mooney viscosity ML 1 + 4 @100° C.: 28 MU, residual double bond content: max. 0.9% HNBR-PEG acrylate 2 PEG acrylate-containing, hydrogenated nitrile rubber (termonomer = butyldiglycol methacrylate), ACN content: 31% by weight, Mooney viscosity ML 1 + 4 @100° C.: 75 MU, residual double bond content: max. 0.9% HNBR-PEG acrylate 3 PEG acrylate-containing, hydrogenated nitrile rubber (termonomer = butyldiglycol methacrylate), ACN content: 20% by weight, Mooney viscosity ML 1 + 4 @100° C.: 26 MU, residual double bond content: max. 0.9% HNBR-PEG acrylate 4 PEG acrylate-containing, hydrogenated nitrile rubber (termonomer = butyldiglycol methacrylate), ACN content: 25% by weight, Mooney viscosity ML 1 + 4 @100° C.: 26 MU, residual double bond content: max. 0.9% Luvomaxx ® MT N-990 carbon black, available from Lehmann and Voss Luvomaxx ® CDPA 4,4′-bis(1,1-dimethylbenzyl)diphenylamine, available from Lehmann and Voss Tremin ® 283-600 VST vinylsilane-coated wollastonite, available from Quarzwerke Perkadox ® 14-40 B-PD di(tert-butylperoxyisopropyl)benzene 40% supported on silica; available from Akzo Nobel Polymer Chemicals BV Rhenofit ® TRIM/S 70% trimethylolpropane trimethacrylate on 30% silica; coagent; available from LANXESS Deutschland GmbH Vulkanox ® MB2 4- and 5-methyl-2-mercaptobenzimidazole; available from Lanxess Deutschland GmbH MgO magnesium oxide, available from CP Hall TAIC 70% KETTLITZ-TAIC 70; coagent; available from Kettlitz- Chemie GmbH & Co. KG Glysantin ® G64 Ready-Mix G64 coolant additive available from BASF; for the storage tests, 50 parts by volume of deionized water and 50 parts by volume of G64 coolant additive were mixed

Example 1

[0160] Process for Preparing the HNBR-PEG Acrylates 1-4

[0161] a) Polymerization

[0162] The nitrile-butadiene-PEG acrylate copolymers (PEG-NBRs) used in the series of examples which follow were prepared according to the base formulation specified in Table 1, wherein all feedstocks (except for the SDPA/Naugawhite® stabilizer) are reported in by weight based on 100% by weight of the monomer mixture. Table 1 also gives the particular polymerization conditions (temperature, conversion and time).

TABLE-US-00002 TABLE 1 Preparation of the PEG-NBRs PEG-NBR 1 2 3 4 Acrylonitrile (total/increment**) 19/3 37.5/9 18/9 27/9 1,3-Butadiene 42 44.5 41 46 Methoxyethyl acrylate (MEA) 39 Butyldiglycol methacrylate (BDGMA) 18 41 27 Total amount of water 190 190 190 190 Disponil ® SDS G 2.4 2.4 2.4 2.4 Na salt of the 0.5 0.5 0.5 0.5 disproportionated resin acid Na.sub.2CO.sub.3 0.12 0.12 0.12 0.12 Sodium hydroxide solution 0.005 0.005 0.005 0.005 pH 10.7 ± 0.5 10.7 ± 0.5 10.7 ± 0.5 9.4 ± 0.5 t-DDM 0.520 0.450 0.45 0.3 Glidox ® 500 0.02 0.02 0.02 0.02 Premix solution FeSO.sub.4 0.022 0.020 0.024 0.024 Diethylhydroxylamine 0.2 0.2 0.2 0.2 SDPA/Naugawhite ® 0.5/0.15 0.5/0.15 0.5/0.15 0.5/0.15 Polymerization temperature [° C.]   12 ± 0.5   12 ± 0.5   12 ± 0.5  12 ± 0.5 Polymerization conversion [%] 75.0 74.3 75.3 78.8 Polymerization time [h] 7.00 6.13 7.5 7.7 **The increment was added at a monomer conversion of 33%

[0163] The PEG-NBRs were prepared batchwise in a 5 I autoclave with stirrer system. In each of the autoclave batches, 1.30 kg of the monomer mixture and a total amount of water of 2.51 kg were used, as was EDTA in an equimolar amount based on the Fe(II). 2.25 kg of this amount of water were initially charged with the emulsifier in the autoclave and purged with a nitrogen stream. Thereafter, the monomers and the amount of the t-DDM molecular weight regulator specified in Table 1 were added and the reactor was closed. Once the reactor contents had been thermostatted, the polymerizations were initiated by addition of the premix solutions and of pinane hydroperoxide (Glidox® 500).

[0164] The progression of the polymerization was monitored by gravimetric conversion determinations. Upon attainment of the conversions reported in Table 1 the polymerization was terminated by adding an aqueous solution of diethylhydroxylamine. Unconverted monomers and other volatile constituents were removed by means of steam distillation.

[0165] Prior to the coagulation of each NBR latex, an emulsion of 50% SDPA and 15% Naugawhite® (0.5% by weight of SDPA/0.15% by weight of Naugawhite® based on NBR solids) was added to each. This was followed by coagulation with CaCl.sub.2, washing and drying of the crumbs obtained.

[0166] b) Hydrogenation

[0167] The hydrogenations which follow were performed using the above-synthesized nitrile-butadiene-PEG acrylate copolymers (PEG-NBR 1 to 4).

[0168] Dry monochlorobenzene (MCB), Wilkinson catalyst and triphenylphosphine were purchased from VWR and used as obtained. The results of the hydrogenation experiments are compiled in Table 2.

[0169] Hydrogenations 1-4 were performed in a 10 I high-pressure reactor under the following conditions: [0170] Solvent: monochlorobenzene [0171] Solids concentration: 12-13% by weight of PEG-NBR terpolymer in MCB (518 g) [0172] Reactor temperature: 137-140° C. [0173] Reaction time: up to 4 hours [0174] Catalyst & loading: Wilkinson catalyst: 0.337 g (0.065 phr);

[0175] Co-catalyst: triphenylphosphine: 5.18 g (1.0 phr) [0176] Hydrogen pressure (p H.sub.2): 8.4 MPa [0177] Stirrer speed: 600 rpm

[0178] The PEG-NBR-containing polymer solution is degassed three times with H.sub.2 (23° C., 2 MPa) with vigorous stirring. The temperature of the reactor was raised to 100° C. and the H.sub.2 pressure to 6 MPa. 123.9 g of a chlorobenzene solution consisting of Wilkinson catalyst (0.337 g) and triphenylphosphine (5.18 g) were added and the pressure was raised to 8.4 MPa, while the reactor temperature was adjusted to 137-140° C. Both parameters were kept constant during the reaction. The course of the reaction was monitored by means of measurement of the residual double bond content (RDB) of the nitrile-butadiene-PEG acrylate copolymer by means of IR spectroscopy. The reaction was ended after not more than 4 hours and/or attainment of an RDB content of <1% by releasing the hydrogen pressure.

[0179] The hydrogenated PEG-HNBR thus formed was isolated from the solution by means of steam coagulation. For this purpose, the chlorobenzene solution was diluted to a polymer content of 7% by weight and metered continuously into a stirred, water-filled glass reactor preheated to 100° C. At the same time, 0.5 bar steam was used for introduction into the coagulation water. The polymer crumbs thus precipitated were roughly dewatered and then dried to constant weight at 55° C. under reduced pressure.

TABLE-US-00003 TABLE 2 Properties of the hydrogenated polymers Therban ® LT Therban ® HNBR-PEG HNBR-PEG HNBR-PEG HNBR-PEG 1707 VP* 3407* acrylate 1 acrylate 2 acrylate 3 acrylate 4 ACN 17 34 20 31 20 25 BD 50 66 54 55 54 51 BA 33 — — — — — MEA — — 26 — — — BDGMA — — — 14 26 24 Tg [° C.] −40 −24 −35 −29 −40 −36 *Comparative experiment; monomer figures in % by weight

TABLE-US-00004 TABLE 3 Storage of the raw polymers (8 g) at 150° C. for 7 days in 200 ml of water/G64 medium (1:1) Therban ® Therban ® HNBR-PEG HNBR-PEG HNBR-PEG LT 1707 VP* 3407* acrylate 1 acrylate 2 acrylate 3 Storage time [d] 0 7 0 7 0 7 0 7 0 7 Solubility yes no yes yes yes yes yes yes yes yes Gel [%] 1.2 5.7 0.5 0.6 1.3 1.4 1.4 1.8 0.9 0.6 Butanol [mg/kg] — 126 — <d.l. — <d.l. — <d.l. — <d.l. <d.l. = below the limit of detection of 5 mg/kg

TABLE-US-00005 TABLE 4 Composition of the vulcanisable compositions (figures in parts by weight) V1* V2* V3 V4 V5 Therban ® 3407 100 Therban ® LT 1707 VP 100 HNBR-PEG acrylate 2 100 HNBR-PEG acrylate 3 100 HNBR-PEG acrylate 4 100 Luvomaxx ® MT N-990 50 50 50 50 50 Luvomaxx ® CDPA 1.5 1.5 1.5 1.5 1.5 Tramin ® 283-600 VST 35 35 35 35 35 MgO 3 3 3 3 3 MB2 0.3 0.3 0.3 0.3 0.3 Perkadox ® 14-40 B-PD 8.5 9 9 9 9 Rhenofit ® TRIM/S 1.5 1.5 1.5 1.5 1.5

TABLE-US-00006 TABLE 5 Vulcanisation characteristics of the vulcanisable compositions (MDR 180° C. 30 min S16) V1* V2* V3 V4 V5 S′ min dNm 1.67 1.56 1.58 0.78 2.23 S′ max dNm 30.91 16.85 19 16.49 20.22 S′ final dNm 30.51 16.69 18.56 15.96 19.51 Delta S′ dNm 29.24 15.29 17.42 15.71 17.99 TS 1 s 30 40 34 34 29 TS 2 s 36 49 41 41 35 t 10 s 40 45 39 38 34 t 25 s 57 66 56 52 46 t 30 s 63 74 62 58 50 t 50 s 96 113 95 90 74 t 70 s 150 176 149 142 119 t 80 s 195 228 193 182 156 t 90 s 273 317 267 250 218 t 95 s 352 407 340 316 278 S′@t 90 dNm 27.99 15.32 17.26 14.92 18.42 t@S′max s 799 924 706 631 563 tan D of end value 0.04 0.05 0.05 0.04 0.03 S′ min is the minimum torque of the crosslinking isotherm S′ max is the maximum torque of the crosslinking isotherm Delta S′ difference of S′max and S′min t50: time at which 50% of the final conversion has been attained t90: time at which 90% of the final conversion has been attained t95: time at which 95% of the final conversion has been attained

TABLE-US-00007 TABLE 6 Properties of the vulcanised compositions V1* V2* V3 V4 V5 Hardness ShA 69 61 64 60 63 M10 MPa 0.8 0.6 0.7 0.6 0.6 M25 MPa 1.5 1.1 1.3 1.1 1.2 M50 MPa 3 2.1 2.2 2 2.3 M100 MPa 7.6 4.6 5.2 4.7 5.6 M300 MPa — — 13 — — EB % 271 278 350 277 260 TS MPa 16.4 12 13.7 10.7 11.9

TABLE-US-00008 TABLE 7 Properties of the vulcanised compositions after storage (21 days; 150° C.) in G64 Ready-Mix (50/50 mixture with water)—ratio of vulcanisate to coolant = 1:80 V* V2* V3 V4 V5 Δ mass % 2.9 2.2 3.3 1.9 2.3 Δ volume % 4.1 3.5 2.8 0.8 1.5 Hardness ShA 71 78 67 66 70 Δ ShA 2 17 4 6 7 hardness M10 MPa 1 1.9 0.8 0.8 0.9 M25 MPa 1.8 3.6 1.5 1.4 1.7 M50 MPa 2.9 6 2.3 2.2 2.8 M100 MPa 5.3 9.1 4.5 4 5.5 M300 MPa 10.2 13.4 10.8 9.6 11.5 EB % 435 289 501 462 429 TS MPa 12.3 13.7 14.5 11.6 14.3 Δ EB % 61 4 43 67 65 Δ TS % −25 14.2 5.8 8.4 20.2

TABLE-US-00009 TABLE 8 Glass transition temperature of the vulcanisate V1* V2* V3 V4 V5 Tg ° C. −28 −42 −33 −45 −41

[0180] The vulcanisates of the PEG acrylate-HNBR rubbers according to the invention simultaneously have a low Tg of less than −30° C. and a small rise in hardness of less than 10% after storage in coolant. Moreover, there is no dissociation of the termonomers.

[0181] Therban® LT 1707 VP does have a low Tg, but also has a high rise in hardness and high gelation after storage in the coolant.

[0182] Therban® 3407 does have no rise in hardness, but has much too high a Tg.