Patent Application
20080064768
In Example 1 described in the following, it is shown that compositions according to the invention which display particular rheological characteristics, such as structural viscosity, thixotropy and approximately Newtonian flow properties, are obtained using microgels based on SBR.
The use of the composition according to the invention as a functional and/or rheological additive, inter alia, emerges from this. Microgels which have little influence on the viscosity, that is to say in a first approximation show Newtonian flow properties, have favourable prerequisites for the use of the mixtures according to the invention in rubber or plastic. Microgels which greatly influence the viscosity, that is to say show structural viscosity or thixotropy flow properties, are suitable in particular for use of the mixtures according to the invention in greases.
The composition is shown in the following table:
Nynas T 110 is a hydrogenated naphthenic oil from Nynas Naphthenics AB.
Micromorph 5 P is a crosslinked rubber gel having an OH number of 4 based on SBR from RheinChemie Rheinau GmbH. Micromorph 5 P comprises 40 wt. % styrene, 57.5 wt. % butadiene and 2.5 wt. % dicumyl peroxide.
Micromorph 1 P is a crosslinked, surface-modified rubber gel based on SBR from RheinChemie Rheinau GmbH. Micromorph 1 P comprises 80 wt. % styrene, 12 wt. % butadiene, 5 wt. % ethylene glycol dimethacrylate (EGDMA) and 3 wt. % hydroxyethyl methacrylate (HEMA).
The characteristic data of the SBR gels are summarized in Table 1.
The abbreviations in the table have the following meanings:
Qi=wet weight of the microgel/dry weight of the microgel.
The gel content corresponds to the content which is insoluble in toluene at 23° C. The gel content is given by the quotient of the dried residue and the amount weighed out and is stated in percent by weight.
Micromorph 1 P is a microgel based on hydroxyl-modified SBR, prepared by direct emulsion polymerization using the crosslinking comonomer ethylene glycol dimethacrylate.
325 g of the Na salt bf a long-chain alkylsulfonic acid (330 g Mersolat K30/95 from Bayer AG) and 235 g of the Na salt of methylene-bridged naphthalenesulfonic acid (Baykanol PQ from Bayer AG) are dissolved in 18.71 kg water and the solution is initially introduced into a 40 I autoclave. The autoclave is evacuated and charged with nitrogen 3 times. Thereafter, 8.82 kg styrene, 1.32 kg butadiene, 503 g ethylene glycol dimethacrylate (90% pure), 314 g hydroxyethyl methacrylate (96%) and 0.75 g hydroquinone monomethyl ether are added. The reaction mixture is heated up to 30° C., while stirring. An aqueous solution consisting of 170 g water, 1.69 g ethylenediaminetetraacetic acid (Merck-Schuchardt), 1.35 g iron(II) sulfate*7H2O, 3.47 g Rongalit C (Merck-Schuchardt) and 5.24 g trisodium phosphate*12H2O is then metered in. The reaction is started by addition of an aqueous solution of 2.8 g p-menthane hydroperoxide (Trigonox NT 50 from Akzo-Degussa) and 10.53 g Mersolat K 30/95, dissolved in 250 g water. After a reaction time of 5 hours, the mixture is post-activated with an aqueous solution consisting of 250 g water, in which 10.53 g Mersolat K30/95 and 2.8 g p-menthane hydroperoxide (Trigonox NT 50) are dissolved. When a polymerization conversion of 95-99% is reached, the polymerization is stopped by addition of an aqueous solution of 25.53 g diethylhydroxylamine, dissolved in 500 g water. Thereafter, unreacted monomers are removed from the latex by stripping with steam. The latex is filtered and, as in Example 2 of U.S. Pat. No. 6,399,706, stabilizer is added and the product is coagulated and dried.
Micromorph 5 P is prepared analogously. The dry microgel powders Micromorph 1 P and Micromorph 5 P further processed according to the invention were obtained from the latex by spray drying.
For the preparation of the composition according to the invention, Nynas T 110 was initially introduced into the preparation vessel and Micromorph 5 P was added, while stirring by means of a dissolver. The composition was passed through the homogenizer four times under 950 bar.
The laboratory high-pressure homogenizer APV1000 from Invensys was used as the homogenizer.
The rheological properties of the composition were determined with a rheometer, MCR300, from Physica. A plate-cone system, CP25-1, was used as the measuring body. The measurements were carried out at 20° C.
Some measurement results for the composition of 80% Nynas T 110 and 20% Micromorph 1 P and Micromorph 5 P are shown in the following Table 2.
The greases Li-12OH, a semi-finished product, and E301 (15%), a laboratory product from RheinChemie Rheinau GmbH, were also measured as a comparison.
The viscosities η, which were measured at shear rates v′ of 5 s−1, 100 s−1, 1,000 s−1, 3,000 s−1 and 0,1 s−1, are shown in the table. The measurement was carried out with a measurement programme in which the measurement values (dynamic viscosities η etc.) were recorded in the sequence given above. The quotient η (v′=0.1 s−1)/η (v′=3,000 s−1) was defined as an arbitrary measure of the viscosity-increasing action of the microgel.
The composition of 80% Nynas T 110 and 20% Micromorph 5 P, which was passed through the homogenizer four times under 950 bar, shows rheological properties comparable to those of Li-120H AK33 or E301, i.e. Micromorph 5 P is suitable as a raw material for the preparation of greases.
The values in Table 2 show very clearly what diverse rheological properties can be achieved with the microgels.
1)20 wt.% Micromorph 5P in Nynas T 110
2)20 wt.% Micromorph 5P in Nynas T 110
3)η(v′ = 0.1 s−1)/ηv′ = 1,000 s−1)
The values measured show a thickening which, with suitable choice of the microgel/lubricant combination from the point of view of rheology, surprisingly allows the preparation of lubricating greases.
Moreover, rheological properties can be controlled with microgels in the liquid media described. The compositions according to the invention are of particular interest as thickeners, as agents for preventing running and settling out and as a rheological additive.
The compositions described or similar compositions can advantageously be used in lubricating greases, lacquers and paints, adhesives, rubber, plastics and gel coats or thermoplastic elastomers.
The compositions prepared in Example 1 can be used particularly advantageously in lubricating greases. In these, they lead to particularly favourable properties, such as a high thixotropy or structural viscosity.
Further very advantageous properties which are co-introduced into the particular systems via the microgels can be seen from the following examples.
In Example 2 described in the following, it is shown that compositions according to the invention which display particular characteristics in respect of transparency and stability towards separation are obtained using microgels based on SBR and NBR.
The composition is shown in the following table:
Shell Catenex S 932 is a paraffinic, highly refined mineral oil from Deutsche Shell GmbH.
Shell Gravex 921 is a hydrogenated, naphthene-based manufactured oil from Shell&DEA Oil GmbH.
Methyl Ester SU is a methyl ester (Radia 7961) from Oleon NV.
Silicone Oil M350 is a polydimethylsiloxane from Bayer MaterialScience AG.
Baylube 68CL is a polyether from RheinChemie Rheinau GmbH.
The microgels OBR 1210 and OBR 1212 are crosslinked, surface-modified rubber gels based on SBR from RheinChemie Rheinau GmbH. Micromorph 4 P is a crosslinked rubber gel which is not surface-modified and is based on SBR, from RheinChemie Rheinau GmbH.
OBR 131OD is a crosslinked, surface-modified rubber gel based on NBR (Tab. 3). The microgels are prepared by a procedure analogous to that described in Example 1 for Micromorph 1 P.
The characteristic data of the SBR gels and of the NBR gel are summarized in Table 4.
The abbreviations in the table have the following meanings:
For the preparation of the composition according to the invention, the particular lubricating oils were initially introduced into the preparation vessel and the particular microgel was added, while stirring by means of a dissolver. The mixture was left to stand for at least one day, and then further processed with the homogenizer. The composition according to the invention was introduced into the homogenizer at room temperature and passed through the homogenizer six times in batch operation under 900 to 1,000 bar. During the first pass the microgel paste heats up to approx. 40° C., and during the second pass to approx. 70° C. Thereafter, the microgel paste was cooled down to room temperature by being left to stand, and the operation was repeated until six passes had been achieved.
The rheological properties of the composition were determined with a rheometer, MCR300, from Physica. A plate-cone system, CP 50-2, was used as the measuring body. The measurements were carried out at 40° C.
Some measurement results for the microgels described above are shown in the following Table 5 to 7.
From Tab. 5 it can be seen that there are many compositions according to the invention which on the one hand are based on different lubricating oils and on the other hand do not settle out. In particular, Micromorph 4 P shows no settling out in any combination. This is surprising, since only 2 wt. % microgel was added.
Furthermore, a composition which is largely transparent and does not separate, namely OBR 1210 in Methyl Ester SU, was found.
From the values of Table 6, the rheological action of the microgels even at a concentration of two percent can be clearly seen; nevertheless, there is a clear differentiation into Newtonian, structural viscosity and thixotropic flow properties. OBR 1210 has Newtonian flow properties in Silicone Oil M350.
SRV tests were furthermore carried out for determination of the coefficient of friction (Tab. 7;
It can be seen from Table 7 that for the composition according to the invention, OBR 1210/Baylube 68CL, a clearly lower coefficient of friction is found compared with the pure lubricating oil Baylube 68CL. It is moreover found that the course of the curve during measurement is smoother, which indicates that the microgels lead to a lower wear on the surface of the test plate.
The microgel, like many other microgels also, surprisingly has properties which reduce the coefficient of friction and can therefore be employed as a coefficient of friction modifier.
In Example 3 described in the following, it is shown that compositions according to the invention which display particular characteristics in respect of transparency and stability in respect of separation can be obtained using microgels based on SBR and NBR. It is furthermore found that lubricating greases can be obtained.
The composition of the microgel paste is shown in the following table:
Shell Catenex S 932 is a paraffinic, highly refined mineral oil from Deutsche Shell GmbH.
Methyl Ester SU is a methyl ester (Radia 7961) from Oleon NV.
Refined rapeseed oil is an oil from Cereol Deutschland GmbH, which is obtained from renewable raw materials.
Baylube 68CL is a polyether from RheinChemie Rheinau GmbH.
Nynas T 110 is a hydrogenated naphthenic oil from Nynas Naphthenics AB.
The microgels OBR 1210 and OBR 1212 are crosslinked, surface-modified rubber gels based on SBR from RheinChemie Rheinau GmbH. OBR 1135 and Micromorph 5 P are crosslinked rubber gels which are not surface-modified and are based on BR and SBR respectively, from RheinChemie Rheinau GmbH.
Micromorph 5 P is described in Example 1. The compositions of the microgels OBR 1210 and OBR 1212 are described in Example 2. OBR 1135 is a BR gel; it comprises 97.5% and 2.5% dicumyl peroxide. The microgels are prepared as described in Example 1 for Micromorph 1 P.
The greases Li-120H, a semi-finished product, and E301 (15%) and M10411, laboratory products from RheinChemie Rheinau GmbH, were also measured as a comparison.
The characteristic data of the microgels are summarized in Examples 1 and 2.
The composition according to the invention was prepared as already described above. In deviation from this, an air pressure of 1 to 5 bar was required in certain cases to convey the material into the homogenizer. The number of passes is stated in the following.
The rheological properties of the composition were determined with a rheometer, MCR300, from Physica. A plate-cone system, CP 25-1, was used as the measuring body. The measurements were carried out at 20° C.
Some measurement results for the microgels described above are shown in the following (Tab. 8-10):
20 and 30% Micromorph 5 P/Nynas T110 exude little lubricating oil and are solid.
Only 30% OBR 1135 and OBR 1210/Nynas T110 exude little lubricating oil and are solid.
20% OBR 1135/rapeseed oil and 20Micromorph 5 P/rapeseed oil also show no separation on the surface, even after 1.5 years. Hardly any separation is also shown with 10% of the same gels in rapeseed oil.
In Example 4 described below, it is shown that, using microgels based on SBR which are modified by hydroxyl groups, compositions according to the invention which chiefly contain primary particles having an average particle diameter of approx. 43 nm can be prepared in a homogenizer by applying 900 to 1,000 bar with 2 to 6 passes.
Baylube 68CL is a polyether from RheinChemie Rheinau GmbH.
The microgel OBR 1312B is a crosslinked, surface-modified rubber gel based on SBR from RheinChemie Rheinau GmbH (Tab. 12). The microgel is prepared analogously to Example 1 for Micromorph 1 P.
The characteristic data of OBR 1312B are summarized in Table 13.
For the preparation of the composition according to the invention, Baylube 68CL was initially introduced into the preparation vessel and OBR 1312B was added, while stirring by means of a dissolver. The mixture was left to stand for at least one day, and then further processed with the homogenizer.
The composition according to the invention was introduced into the homogenizer at room temperature and passed through the homogenizer 6 times under 960 bar in batch operation. During the first pass the microgel paste heats up to approx. 40° C., and during the second pass to approx. 70° C. Thereafter, the microgel paste was cooled to room temperature and dispersed a third and fourth time. This was repeated until six passes had been achieved.
The particle diameter of the latex particles was -determined by means of ultracentrifugation (W. Scholtan, H. Lange, “Bestimmung der TeilchengröBenverteilung von Latices mit der Ultrazentrifuge”, Kolloid-Zeitschrift und Zeitschrift für Polymere (1972) volume 250, issue 8).
The particle size distributions of the original, not yet dried latex of the OBR 1312B microgel and of the OBR 1312B redispersed in Baylube 68CL (TZE 122) can be seen in the following figures.
It can be seen that, surprisingly, almost the entire amount of the dried and therefore agglomerated OBR powder has been successfully redispersed down to the primary particles, the average particle diameter of the redispersed mixture even being below the average particle diameter of the original latex. It is to be noted in addition that the measurement was carried out on a redispersed sample which had been stored for 6 months at room temperature, i.e. the dispersion surprisingly remained stable for 6 months.
Because of its low content of reagglomerated particles, the redispersed composition moreover is highly transparent.
| Number | Date | Country | Kind |
|---|---|---|---|
| 103 44 975.2 | Sep 2003 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP04/52290 | 9/23/2004 | WO | 00 | 8/8/2007 |
