Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic oxygen compound
Reexamination Certificate
2002-03-11
2004-05-11
McAvoy, Ellen M (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic oxygen compound
C252S068000, C526S332000, C568S621000
Reexamination Certificate
active
06734151
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a process for producing a high purity compound having oxygen such as a high purity polyvinyl ether compound and a lubricating oil comprising the high purity compound having oxygen obtained in accordance with this process. More particularly, the present invention relates to a process for efficiently producing a high purity compound having oxygen which has a high volume specific resistance and is advantageously used as a component of a lubricating oil for refrigerators by an adsorption treatment, and a lubricating oil, in particular, a lubricating oil for refrigerators which comprises the high purity compound having oxygen obtained in accordance with this process and has an improved volume specific resistance.
BACKGROUND ART
In general, compression-type refrigerators are constituted with a compressor, a condenser, an expansion valve and an evaporator and has a structure in which a mixed fluid of a refrigerant and a lubricating oil is circulated in a closed system. In the compression-type refrigerator, in general, temperature is as high as 50° C. or higher in the compressor and as low as about −40° C. in the refrigerating chamber although the conditions may be different depending on the type of the apparatus and it is required, in general, that the refrigerant and the lubricating oil be circulated in the system without causing a phase separation in the temperature range of −40 to 50° C. If the phase separation takes place during the operation of a refrigerator, the life and the efficiency of the apparatus are adversely affected to a great extent. For example, if the phase separation of the refrigerant and the lubricating oil takes place in the compressor, lubrication of moving parts deteriorates and seizure occurs to cause a great decrease in the life of the apparatus. If the phase separation takes places in the evaporator, the efficiency of heat exchange decreases because of the presence of a lubricating oil of high viscosity.
Since the lubricating oil for refrigerators is used for the purpose of lubricating moving parts in refrigerators, the lubricating property is naturally important. In particular, since the temperature in the compressor becomes high, the viscosity which can maintain the oil film necessary for the lubrication is important. The required viscosity is different depending on the type of the compressor used and working conditions and, in general, it is preferable that the viscosity (the kinematic viscosity) of the lubricating oil before mixing with a refrigerant is 5 to 1,000 mm
2
/sec at 40° C. When the viscosity is lower than this range, the oil film becomes thin and the lubrication tends to become insufficient. When the viscosity is higher than this range, the efficiency of heat exchange decreases.
As the refrigerant for compression-type refrigerators, mainly dichlorodifluoromethane(fron 12) has heretofore been used. As the lubricating oil, various types of mineral oils and synthetic oils satisfying the required properties described above have been used. However, chlorofluorocarbons (CFC) including dichlorodifluoromethane are more rigorously restricted world-wide because there is the possibility of causing environmental pollution such as the ozonosphere destruction. Due to this reason, hydrofluorocarbons (HFC) and hydrochlorofluorocarbons (HCFC) which are fluorocarbons having hydrogen has been attracting attention as the novel types of refrigerant. The fluorocarbons having hydrogen, in particular, hydrofluorocarbons (HFC) such as fron 134a (1,1,1,2-tetrafluoroethane) as a typical example are preferable as the refrigerant for compression-type refrigerators since these hydrofluorocarbons have little possibility of causing the ozonosphere destruction and can be used in place of dichlorodifluoromethane with a little change in the structure of conventional refrigerators. Refrigerants prepared by mixing more than one HFC are also attracting attention from the standpoint of the efficiency of refrigeration. Other refrigerants having a small coefficient of atmospheric warming such as a carbon dioxide, hydrocarbons, ether and ammonia are also attracting attention from the standpoint of the global warming of the atmosphere.
When a fluorocarbon having hydrogen such as fron 134a or a carbon dioxide is used as the refrigerant for a compression-type refrigerator in place of fron 12, a lubricating oil having excellent compatibility with the fluorocarbons having hydrogen such as fron 134a or a carbon dioxide and excellent lubricating properties satisfying the above requirements are naturally required. However, since conventional lubricating oils used in combination with fron 12 do not have sufficient compatibility with fluorocarbons having hydrogen such as fron 134a or a carbon dioxide, a novel lubricating oil suitable for these compounds is required. In this case, no change in the structure of the apparatus is desired when the novel lubricating oil is used in place of fron 12. Therefore, it is not desirable that the structures of the currently used apparatuses must be changed to a great extent by replacing a lubricant.
As the lubricating oil for compression-type refrigerators using a hydrofluorocarbon as the refrigerant, for example, the use of a polyvinyl ether compound which is a compound having oxygen has been proposed (Japanese Patent Application Laid-Open Nos. Heisei 6(1994)-234815 and Heisei 9(1997)-272886).
In electric refrigerators and air conditioners, a motor and a compressor are integrally formed as a single member and an excellent electric insulating property is required for a lubricating oil used for them. However, it occasionally occurs that a compound having oxygen such as a polyvinyl ether compound is contaminated with polar substances or metal components during the process of production thereof and the volume specific resistance is decreased. As the method for increasing the decreased volume specific resistance, a treatment such as washing with an alkali or water is known. However, the effect of the washing is not always sufficient. Therefore, development of a novel treatment process for increasing the volume specific resistance of the compound having oxygen such as a polyvinyl ether compound has been desired.
DISCLOSURE OF THE INVENTION
Under the above circumstances, the present invention has an object of providing a process for efficiently producing a high purity compound having oxygen which has a high volume specific resistance and a lubricating oil, in particular, a lubricating oil for refrigerators which comprises the high purity compound having oxygen obtained in accordance with this process and has an improved volume specific resistance.
As the result of extensive studies by the present inventors to achieve the above object, it was found that a high purity compound having oxygen which has a great volume specific resistance could be obtained by treating the compound having oxygen with an adsorbent, and in particular that a high purity polyvinyl ether compound having a volume specific resistance of 10
14
&OHgr;·cm or greater at 30° C. could be obtained, by treating a crude polyvinyl ether compound having a specific constituting unit as the main component with an adsorbent, and that a lubricating oil comprising this compound and having an improved volume specific resistance could be advantageously used especially for refrigerators. The present invention has been completed based on this knowledge.
The present invention provides a process for producing a high purity compound having oxygen selected from a group consisting of high purity polyvinyl ether compounds, high purity polyalkylene glycol compounds, high purity polyol ester compounds, high purity cyclic polyether compounds and high purity carbonate compounds, comprising a step of treating with an adsorbent at least one crude compound having oxygen selected from a group consisting of crude polyvinyl ether compounds, crude polyalkylene glycol compounds, crude polyol ester compounds, crude cyclic polyether compounds and crude carbonate compound
Kamimori Shigeru
Kubota Minoyuki
Ogawa Akihisa
Suzuki Kazuhiko
Yamazaki Hirotaka
Idemitsu Kosan Co. Ltd.
McAvoy Ellen M
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