Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Patent
1993-09-27
1996-04-02
Cain, Edward
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
524485, 524486, 524491, 524848, C08K 501
Patent
active
055041353
DESCRIPTION:
BRIEF SUMMARY
This invention relates to the use of specified oil compositions as processing oils for rubbers, particularly, but not exclusively, for aromatic rubbers, and to methods of making rubbers employing such oils, and to rubbers made with such oils.
Rubber process oils and extender oils are added to natural and synthetic rubbers for a number of reasons, for example to reduce mixing temperatures during processing and prevent scorching or burning of the rubber polymer when it is being ground to a powder, to decrease the viscosity of the rubber and thereby facilitate milling, extruding and general workability of the rubber compound (which may include added components), to reduce mill and calender shrinkage, to aid the dispersion of fillers, and to modify the physical properties of the vulcanised and/or finished rubber compound, and for other reasons which are well-known to those skilled in the art.
To act as a useful process oil, the oil must have a certain degree of miscibility and/or solvency for the rubber. The degree of miscibility and/or solvency of the process oil with or for the rubber depends upon the nature of the rubber, the components with which it is blended or compounded, and its final use, and is well-known to those skilled in the art. For a rubber containing largely saturated groups, such as butyl rubber, paraffinic process oils are conventionally used. Similarly, for a rubber containing a significant proportion of aromatic groups, such as styrene-butadiene rubber ("SBR"), a highly aromatic process oil is usually employed. Typically such an aromatic oil contains at least 70 weight percent (e.g. 70 to 85 weight percent) total aromatics and from 10 to 15 weight percent polynuclear aromatic compounds ("PNAs"). Whilst these oils show good compatibility with SBR and other rubbers, they have the disadvantage that they are toxic and carcinogenic, largely due to the high PNA content.
There is accordingly a need for a relatively low toxicity, relatively non-carcinogenic product suitable for use as a process oil for rubber compounds in general, and more particularly, aromatic rubber compounds.
According to one aspect, the invention provides the use of an oil composition which has a kinematic viscosity at 100.degree. C. in the range of from 32 to 50 cSt and contains less than 3 weight percent polynuclear aromatic compounds ("PNA") based on the total weight of the hydrocarbons contained in the oil composition, as a process oil for rubber compounds.
The use of the oil according to the invention is especially beneficial as a process oil for aromatic rubbers, such as SBR and the like, as it is sufficiently compatible with such rubbers to aid processing, but contains far fewer PNAs than conventional aromatic rubber process oils and so does not have the disadvantage of being highly toxic.
According to another aspect, the invention provides a method of making or compounding rubber, the method comprising the step of mixing a rubber process oil having a viscosity in the range of from 32 to 50 cSt at 100.degree. C. and a PNA content below 3 weight percent (of the weight of the oil) with (a) rubber or rubber compound (preferably in a suitable form such as crumb, particles and/or powder) and/or (b) one or more monomer precursors of rubber or rubber compound.
According to another aspect, the present invention provides a rubber or a rubber composition or a rubber artefact comprising a process oil having a viscosity in the range of from 32 to 50 cSt at 100.degree. C. and a PNA content below 3 weight percent (relative to the oil).
The oil may be obtained by deasphalting a residuum (e.g. a vacuum residuum) from crude oil, and then dewaxing the resulting deasphalted oil. The deasphalting may be effected with any suitable deasphalting agent such as a paraffinic liquid hydrocarbon (e.g. selected from C.sub.3 to C.sub.7 alkanes or any mixture thereof). Propane may be preferred as a deasphalting agent. The dewaxing may be performed in any convenient manner using suitable dewaxing agents which may be selected from ketones, alkylbenzen
REFERENCES:
patent: 4801373 (1989-01-01), Carman et al.
patent: 5034119 (1991-07-01), Blackburn et al.
Kautschuk und Gummi--Kunstoffe, vol. 45, No. 1, Jan. 1992, (Heidelberg), R. Wummelsdorff et al,: "Ein Beibrag zur Reduzierung der polyzyklischen Aromaten aus aromatischen Mineralolweichmachern", pp. 24-29--and English translation thereof.
Rubber World, Dec. 1971, "A New Look at Oils in Rubber", H. F. Weindel and R. R. Terc.
Ardrizzi Emilio
Vivirito Rolando
Allocca Joseph J.
Cain Edward
Exxon Research and Engineering Company
Takemoto James H.
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