In one aspect, the present techniques include a heat exchange apparatus including: a) a body comprising an interior cavity, the body including: a first surface and a second surface defining at least a portion of the body and the first surface positioned exterior with respect to the second surface and the interior cavity, and the second surface positioned exterior with respect to the interior cavity and interior with respect to the first surface; b) a first conduit for conveying a fluid to the body; c) a second conduit in fluid communication with the first conduit wherein the second conduit is positioned at least partially within the interior cavity of the body; and d) a joint between the first conduit and the second conduit, wherein the joint moves between a first location and a second location based on the temperature within the interior cavity, wherein at least one of said first location and said second location is positioned intermediate the first surface and the second surface.

In a heat exchange apparatus, tubes are in fluid communication with each other and used to convey a fluid through an apparatus for purposes of either heating or cooling the conveyed fluid. In certain applications, it may be desirable to join one or more tubes positioned in a relatively extreme thermal region of the apparatus to one or more tubes in a relatively less extreme thermal region either within or external to the apparatus, such that thermal expansion and/or contraction may move or impose relatively severe stresses upon, the joint between the tubes. For example, in a hydrocarbon steam cracking furnace, tubes are arranged to pass a feed from outside a firebox, into and through the firebox, and then out of the firebox to a quench system. Due to the temperature differentials involved in the process and potentially the internal pressure of the feed within the tubes, the tubes experience thermal expansion and thermal stresses. Accordingly, the tubes are arranged to minimize the thermal stresses wherever possible. The joint connecting the tubes may be particularly vulnerable to stresses. As such, it may be challenging to sustain desired performance properties. Special precautions, with respect to joint integrity, strength, and/or protection against inadvertent ruptures or leaks may be required. Such tubular connections or joints may also involve a special connection apparatus, such as a special union fitting, or include redundant connection mechanisms such as threads and welds. Where a leak may be particularly hazardous, such as posing a risk of fire or toxic release, it may be desirable to position the joint within the confines of the apparatus casing so that any potential leak may be consumed, oxidized, or pyrolyzed within the high heat zone (e.g., firebox or radiant heating section).
One exemplary heat exchange apparatus is a hydrocarbon steam cracking furnace. Steam-cracking pyrolysis is the predominant process used in the production of ethylene and propylene. Steam cracking is typically conducted in a direct-fired tubular reactor. Volatile hydrocarbon feeds, such as ethane, naphthas, gas-oils, and crude fractions, are heated rapidly in the presence of steam to produce ethylene, propylene, and other product species. The steam cracking process typically involves conveying a feed fluid from a lower temperature region (outside the furnace) into and through a high temperature region (inside the furnace), and then out of the high temperature region into another lower temperature region (outside the furnace).
One of the process variables in this process is reactor residence time. For example, a greater portion of the hydrocarbon feed is converted to ethylene and propylene if the reaction time in the radiant coil (e.g., tube, tubes, or tubulars) is kept as short as possible. The industry-standard measure of residence time is the time required to pass through the tube in the radiant firebox and the exit tube to the quench unit. One common approach to reducing residence time is by using high strength steel that can tolerate higher heat fluxes, thus enabling use of reduced coil length and surface area. Exemplary materials include wrought or cast high-alloy austenitic stainless steels. Another common approach is to use furnace coil designs of shorter and shorter lengths. To avoid exceeding the radiant tube heat flux and/or temperature limits, as the coil length is reduced, a larger number of smaller diameter coils are used in parallel because smaller diameter coils have a larger surface area-to-volume ratio than larger diameter tubes.
Metallurgical-related limitations are impediments to still further reductions in furnace residence times. Austenitic steels commonly used for the radiant coil and unfired adiabatic zone of ethylene furnaces have reasonable high temperature strength up to 1100-1150° C. and are weldable, using well-proven techniques. However, the austenitic steels have the disadvantage that the interior surface of the tubes and fittings catalyzes carbon deposits (e.g., coke). As this coke layer grows, it insulates the process gas, which results in tube wall temperature increases to provide sufficient heat for the reaction to proceed. Eventually, the tube wall temperature limit is reached and the furnace is taken out of service for decoking. Thus, while a given material may be capable of operating at temperatures, for example, of up to 1100° C., the furnace design is limited to a "clean-coil" tube wall temperature of about 1020° C. to allow for the temperature rise. This limitation constrains both how short a residence time may be designed in a coil and how much feed can be processed in a coil of a given geometry.
While there are other contributors to coke formation, tube surface catalyzed coking is generally accepted as a predominant cause of coke formation, particularly for light gas feeds such as ethane. Surface catalyzed coking rates increase as surface temperature increases. Thus, the temperature limits of austenitic stainless steel radiant tube materials and the coke that forms, at least in part, due to the catalytic reactions that take place at the tube surface effectively combine to prevent designers from reducing residence times below approximately 0.10 seconds. This also sets a limitation on the maximum ethylene yield that can be achieved from a furnace.
If the coking phenomena could be eliminated or substantially reduced, furnaces could be designed for higher "start-of-run" or "clean wall" tube metal temperatures, thus permitting shorter reaction times and thus higher product yields, and may also permit a higher feed rate to be processed through a given radiant coil design. Such an improvement may be realized by using radiant tubes manufactured from a material whose inner surface does not catalyze coke. In addition, if radiant tube materials are used which operate at higher temperatures than the current austenitic stainless steels, then coil length and residence time, may be reduced even more, leading to even further increases in ethylene yield.
To reduce the formation of coke, ceramic tubes, which resist formation of surface-catalyzed coke, may be utilized. However, ceramic materials and some metals that form alumina rather than chromia oxide layers have extremely low ductility and are brittle and, thus are susceptible to cracks and leaking. Further, they do not tolerate extreme rapid cooling without a tendency to crack or shatter. As such, use of these materials has only been acceptable inside the radiant firebox of the furnace where any leak is contained and oxidized within the refractory lined casing plate. Such use is unacceptable outside the casing plate of the radiant section of the furnace. Any leak outside the radiant section (either radiant inlet or outlet) could immediately result in a fire as the hydrocarbon material is above its auto-ignition temperature at these locations. Therefore, the radiant inlets and radiant outlets located outside the radiant firebox are constructed of more ductile materials such as the existing high-alloy austenitic stainless steels to minimize leakage and fire risks.
Joining low coke catalyzing radiant coils to the austenitic inlets and outlets is a major challenge. Welding alumina formers to austenitic stainless steels, while possible, often results in a weld joint of significantly reduced high-temperature stress-rupture strength than the strength of austenitic materials. Such joints may not have sufficient strength to tolerate the high temperatures experienced inside radiant sections of pyrolysis furnaces. For this reason, such joints may use a complex threaded joint for mechanical strength with a seal weld for gas tightness. Joining ceramics to austenitic stainless steels also poses great engineering challenges due to the significantly different co-efficients of thermal expansion. This leads again to the use of complex mechanical joints or low strength brazing techniques that are not well suited for the high temperatures of a radiant section.
In one aspect, what is needed is a heat exchange apparatus that facilitates maintaining sensitive tubular joint connections within the high heat zone casing of the apparatus, while also protecting the connection from any high or extreme temperature that may be encountered at operating conditions that may compromise such connection joint.
What is also needed is a hydrocarbon steam cracking furnace that incorporates radiant tubes made of materials that do not catalyze coke formation securely and safely joined to austenitic stainless steel inlet and/or outlet sections outside the radiant firebox.

Apparatus and methods for utilizing heat exchanger tubes


A gas turbine engine augmentor has a centerbody within a gas flowpath from upstream to downstream. A plurality of vanes are positioned in the gas flowpath outboard of the centerbody. An augmenter fuel conduit extends through a first of the vanes to deliver fuel to the centerbody. An electrographitic carbon bushing guides and supports the augmentor fuel conduit.

This invention relates to turbine engines, and more particularly to turbine engine augmentors.
Afterburners or thrust augmentors are known in the industry. A number of configurations exist. In a typical configuration, exhaust gases from the turbine pass over an augmentor centerbody. Additional fuel is introduced proximate the centerbody and is combusted to provide additional thrust. In some configurations, the augmentor centerbody is integrated with the turbine centerbody. In other configurations, the augmentor centerbody is separated from the turbine centerbody with a duct surrounding an annular space between the two. U.S. Pat. Nos. 5,685,140 and 5,385,015 show exemplary integrated augmentors.
The centerbody may contain a burner serving as a combustion source. For introducing the additional fuel, a number of spray bars may be positioned within generally radially extending vanes. A pilot may be proximate an upstream end of the tailcone. Alternatively or additionally to the burner, a number of igniters may be positioned within associated ones of the vanes to ignite the additional fuel. Trailing portions of the vanes may serve as flameholder elements for distributing the flame across the flow path around the centerbody.
Separately, electro-graphitic carbon materials have been developed for a variety of uses. US Pre-grant Publication 20050084190A1 discloses a variable vane inner diameter (ID) bushing made from electro-graphitic carbon.


The invention is a flow controller attachable to a water supply. The controller has a body with inlet and outlet connections and a control element positioned between the inlet and outlet. The controller has an actuator extending from the control element that permits selection of three different settings. The first setting aligns a set of openings in the control element with the inlet and outlet of the body permitting unimpeded full flow of water. A second setting aligns another set of openings, which form a weep hole, in the control element to substantially impede flow from the inlet to the outlet. A third setting aligns a third set of openings in the control element with a flow control device, to partially impede flow from the inlet to the outlet, creating a low flow.

The use of a water flow control device for a shower is known in the prior art. Known prior art includes U.S. Pat. No. 6,474,621; U.S. Pat. No. 5,152,465; U.S. Pat. No. 5,123,628; U.S. Pat. No. 4,484,711; U.S. Pat. No. 4,398,668; U.S. Pat. No. 4,394,969; U.S. Pat. No. 4,273,289; U.S. Pat. No. 4,191,332; U.S. Pat. No. 3,547,353; and U.S. Pat. No. Des. 287,995. A myriad of regulations exist to conserve water by requiring devices to minimize consumption. Many of these water conservation devices focus of reducing the flow of water, i.e. low flow. The use of showers in personal hygiene is widespread in the United States and a pleasure to most users. Thus, showers provide a major opportunity in water conservation.
In a shower, the water is normally continuously running and results in excess consumption. Low-flow showerheads are well known. However, some users find these low-flow showerheads undesirable for many purposes, such as washing the hair, because of inadequate flow. During the shower there are many times when water flow is not needed and/or the user would be indifferent to a low flow. Standard flow arrangements could be used and, to achieve conservation, the user can rely upon manual adjustment of the main hot and cold shower water rate valves. This requires multiple adjustments that would be equally troublesome to the user.
Furthermore, many people prefer not to shut off the water supply for a number of reasons. First, they prefer to have a small quantity of water flowing from the showerhead while soap, shampoo and conditioner is applied to their body and hair, so as to keep the body and hair wet. Maintaining the body and hair wet makes it easier and more comfortable to apply the soap, shampoo and conditioner. Second, if the water supply is shut off and turned on again after soaping, shampooing, or conditioning, the water temperature will probably be different and the water temperature must be readjusted, causing the person great inconvenience. Accordingly, many people merely twist the showerhead to one side, thereby allowing water to flow continuously and causing water to be needlessly drained.
Therefore what is needed is a shower control system which minimizes shower water flow when full flow is not needed and permits the user to have full flow when desired. Furthermore what is needed is a shower control system that permits adjustments in water flow in a quick and easy manner that would not cause significant temperature fluctuations. Finally, what is needed is a shower control system that facilitates all these needs and which is also simple in construction to facilitate easy installation and low cost manufacturing.


Semiconductor devices having a contact window and fabrication methods thereof are provided. A lower dielectric layer, conductive patterns and an upper dielectric layer are formed sequentially on a semiconductor substrate. The lower dielectric layer has a higher isotropic etch rate than that of the upper dielectric layer. The upper dielectric layer and the lower dielectric layer are patterned by anisotropic etching to form a trench without exposing the semiconductor substrate. The resultant structure is subject to isotropic etching to expose the substrate and to form a contact window having a wider width in a lower region than in an upper region without damaging the semiconductor substrate.

1. Field of the Invention
The present invention relates to semiconductor devices and fabrication methods thereof and, more particularly, to semiconductor devices having a contact window providing low contact resistance and high reliability and fabrication methods thereof
2. Description of the Related Art
Multilevel interconnection in a semiconductor device is important for achieving higher device density and performance. Especially, structures of contact windows and fabrication method for forming the contact windows are essential for forming the multilevel interconnection. The contact windows electrically connect a wiring layer to a semiconductor substrate or connect a wiring layer to another wiring layer. With increased device density, a depth of the contact window tends to be deeper and its width tends to be narrower. The narrow width of the contact window leads to problems such as a small contact area and, as a result, high contact resistance.
With increased device density, a space between conductive patterns also tends to be closer and closer. This tendency makes the width of the contact window more decreased. This is because the contact window is generally formed to pass through a dielectric material between the conductive patterns. This will be further described below with reference to drawings.
FIGS. 1 to 4 are cross sectional views illustrating a process for forming a contact window in a semiconductor device in accordance with a Korean Patent Laid-open Publication No.99-46930.
Referring to FIGS. 1 and 2, a lower dielectric layer 5, conductive patterns 7 and an upper dielectric layer 9 are formed in sequence on a semiconductor substrate 1 having an impurity active region 3. The impurity active region 3 has a predetermined width 13. The lower dielectric layer 5 has a higher wet etch rate than a wet etch rate of the upper dielectric layer 9 for a selected oxide etching solution such as hydrofluoric acid (HF) solution. The lower dielectric layer 5 is formed of a borophosphosilicate glass (BPSG) layer or a spin-on-glass (SOG) layer. The upper dielectric layer 9 is formed of an undoped silicate glass (USG) layer or a high density plasma (HDP) oxide layer. On the upper dielectric layer 9, a photoresist pattern 11 having an opening is formed to define a contact window area. The upper dielectric layer 9 and the lower dielectric layer 5 are partially removed by a dry etching process using the photoresist pattern 11 as an etch mask. As a result, a contact window 19 is formed to expose the impurity active region 3. At this time, the conductive patterns 7 should not be exposed by the contact window 19 as shown in FIG. 2. Therefore, the width 21 of the contact window 19 should be narrower than the spacing 15 between the conductive patterns 7.
The exposed surface 22 of the impurity active region 3 is severely damaged due to the dry etching process during formation of the contact window 19. Accordingly, the etching damage may increase contact resistance and junction leakage current.
Referring to FIG. 3, the resultant structure is dipped into the selected oxide etching solution to form a final contact window 19xe2x80x2. With this wet etching, the upper dielectric layer 9 is etched to a lesser extent of a selected width 20 in a lateral direction; the lower dielectric layer 5 is etched to greater extent in the lateral direction. Consequently, the final contact window 19xe2x80x2 has a wider width 21xe2x80x2 in a lower region than the width in an upper region. Therefore, an exposed surface area of the impurity active region 3 is increased by the wet etching, as compared with an exposed surface area formed immediately after the dry etching. Referring to FIG. 4, the photoresist pattern 11 is removed. Then, a wiring material 24 is formed on the resultant structure to fill the contact window 19xe2x80x2.
In the prior art, the dry etching exposes the semiconductor substrate 1. If the dry etching is overdone, it may cause a surface damage 22 (See FIG. 2) of the impurity active region 3. Therefore, the dry etching should be controlled with high accuracy to prevent the damage. This dry etching damage causes serious problems such as high contact resistance and high junction leakage current in a semiconductor device.
The contact window 19 should not expose the conductive patterns 7 to insure electrical isolation therebetween. Therefore, a width 17 of the opening of the photoresist pattern 11 and a width 21 of the contact window 19 should not be increased greater than a distance 15 between the conductive patterns 7. In other words, the shorter the spacing between the conductive patterns 7 is, the narrower the width of the contact window 19 is, as described above.
The wet etching also should be controlled with high accuracy, because a distance 26 between the wiring material 24 and the conductive patterns 7 needs to be properly maintained. Assume that the wet etching is overdone and the lower dielectric layer 5 is excessively etched in the lateral direction, and, as a result, the contact window 19xe2x80x2 exposes a bottom side of the conductive patterns 7. This can result in an undesirable electrical connection between the wiring material 24 and the conductive patterns 7. Therefore, in the prior art, the width 21xe2x80x2 in a lower region of the final contact window 19xe2x80x2 cannot be greater than the spacing between the conductive patterns 7. Thus, a contact area between the wiring layer and the conductive patterns 7 is limited by the spacing between the conductive patterns 7. Accordingly, it is difficult to reduce contact resistance.
According to the prior art, the dry and the wet etching should be performed very carefully. That is to say, it is very difficult to maintain the high accuracy necessary to avoid above-mentioned problems during the dry and wet etching.
It is, therefore, an object of the present invention to provide a method for forming a contact window without dry etching damage in a semiconductor substrate. Another object of the present invention is to provide a method for forming a contact window that maximizes a contact area and improves electrical isolation characteristic with neighboring conductive patterns simultaneously.
Another object of the present invention is to provide a structure for a contact window that improves the contact resistance and junction leakage current characteristics as well as the electrical isolation characteristic with neighboring conductive patterns.
According to one aspect of the invention, a method of forming a contact window is provided. This method comprises forming a lower dielectric layer and an upper dielectric layer in sequence on a semiconductor substrate. The lower dielectric layer has a higher isotropic etch rate than an isotropic etch rate of the upper dielectric layer for a selected isotropic etching condition. The upper dielectric layer and the lower dielectric layer are etched by an anisotropic etching to form a trench not exposing the semiconductor substrate.
Thus, it is possible to prevent the semiconductor substrate from being damaged by the anisotropic etching. A sidewall of the trench is substantially perpendicular to the substrate. The resultant structure is subject to a wet etching using the selected isotropic etching condition to expose the substrate. A difference in the etch rates of the upper and the lower dielectric layers makes a contact window having a wider width in a lower region than a width in a upper region. For example, the lower dielectric layer is a layer selected from the group consisting of a borophosphosilicate glass (BPSG) layer, a spin-on-glass (SOG) layer and O3-TEOS layer. The upper dielectric layer is a layer selected from the group consisting of an undoped silicate glass (USG) layer, a high density plasma (HDP) oxide layer and O2-TEOS layer. The lower dielectric layer may be a TEOS layer. The TEOS layer is formed by a process in which a flow rate of O3 gas is decreased and a flow rate of O2 gas is increased from an initial stage to an ending stage of the process. In addition, before the wet etching, a polymer with a thickness of 100-500xc3x85 or a spacer formed of a material selected from the group consisting of polycrystalline silicon, silicon nitride and silicon oxynitride may be formed on the sidewall of the trench.
According to another aspect of the present invention, a semiconductor device is provided. The semiconductor device comprises a lower dielectric layer and an upper dielectric layer formed on a substrate, and a contact window formed through the dielectric layers. The contact window includes an upper contact window and a lower contact window extended from the upper contact window to the substrate. The upper contact window has a sidewall substantially perpendicular to the substrate. However, the lower contact window has a sloped sidewall profile such that a width of the lower contact window becomes wider and wider along the downward direction. The lower dielectric layer is a TEOS layer. The TEOS layer is formed by a process in which a flow rate of O3 gas is decreased and a flow rate of O2 gas is increased from an initial stage to an ending stage of the process. The semiconductor device also has a plurality of conductive patterns intervening between the upper dielectric layer and the lower dielectric layer. The plurality of conductive patterns is spaced apart from the contact window. A bottommost width of the contact window may be wider than a space between one conductive pattern and the other conductive pattern.
According to another aspect of the present invention, a semiconductor device has a first dielectric layer, a second dielectric layer and an upper dielectric layer sequentially stacked on a substrate, and has a contact window penetrating the dielectric layers. The semiconductor device also has a plurality of conductive patterns intervening between the first dielectric layer and the second dielectric layer. The plurality of conductive patterns is spaced apart from the contact window. The contact window in the first dielectric layer is wider than that in the second dielectric layer and the upper dielectric layer. A bottommost width of the contact window may be wider than a space between one conductive pattern and the other conductive pattern.
Accordingly, it is possible to maximize a contact area between a conductive material filling the contact window and the substrate, resulting in a reduction of the contact resistance. In addition, the semiconductor device may further comprise a spacer on the sidewall of the upper contact window. The spacer is formed of a material selected from the group consisting of polycrystalline silicon, silicon nitride and silicon oxynitride.

Semiconductor device having a contact window and fabrication method thereof


An incremental search user interface is implemented to reduce search requests from a client system to a server system. In one aspect, a result list is cached in a memory of the client system, where the result list corresponds to a search request from the client system to the server system. In another aspect, a check is repeatedly performed, in a predetermined time interval, to determine whether an input keystroke is received. Upon confirming the receiving of an input keystroke, based on a partial query and the cached result list, determine whether a search request to the server is unnecessary.

Traditional information retrieval systems return search results after a submits a fully formulated search query. A system waits for the user to type the query, after which it is the user who waits the system to process the search request. With such systems, the user has little visibility into how effectively the formulated search query may locate information of interest prior to completion the processing of the query. The user guesses, beforehand, what query pattern is sufficient for the system to distinguish the desired information from other, similar information within the searched content. This information-access paradigm is referred to as "delimited search".
Delimited search is opposed to an incremental search in which as the user types the search query character by character, possible matches for the partially typed query are found and presented to the user. Incremental search is also referred to as search-as-you-type, type-ahead-search, find-as-you-type, etc. With incremental search, search query suggestions or search query results are dynamically presented potentially upon each keystroke. The incremental search provides constant feedback as to the results while the user incrementally enters the search query. Incremental searching results in an increased number of search queries generated potentially by each keystroke compared to one query per submission. The increased number of search queries may increase the system's response time as perceived by the user. The perception of increased response time may have a negative effect on user satisfaction and usability of the search interface.

Instantaneous incremental search user interface


A system and method for writing the same data field to multiple RAM copies during a single write cycle that fans out write data, address data, and control data to multiple RAMs. The multiple copies of data held at the same address in the multiple RAM copies are also read during a single write cycle and the data from each RAM copy is concatenated into a single word that is read during a single read cycle.

In an ASIC/FPGA (Application Specific Integrated Circuit/Field Programmable Gate Array) utilized in a networking application, a context RAM may be needed to hold the per-port configuration that is specific to that port only. Usually, there are several functional blocks inside the ASIC/FPGA that want to access the context RAM to inquire the configuration of a particular port.
Ideally, only one context RAM is needed. However, if there is more than one functional block that needs access to the context RAM in the same cycle, there needs to be an arbitration scheme to resolve the conflict in a timely manner which would satisfy the required access time of each functional block. If there are more than two such functional blocks, then the design of an arbitration logic is much more complex. To simplify the design, an ideal solution is to duplicate the context RAM such that each functional block accesses its own identical copy of the context RAM.
However, other issues come up while maintaining several identical copies of a context RAM:                1. Each copy of the RAM must be separately updated so that the same information will be instant to all functional blocks that access the RAM.        2. The status of each copy of the RAM must be inquired in a time efficient manner.        3. Each copy of the RAM must be tested with minimum time and least cost, etc.        4. Each copy of the RAM will require a distinct set of addresses; the more copies that are used, the greater the address range needed.
Accordingly, an improved technique for providing context information to multiple functional units is required.

Accessing multiple copies of RAM distributed throughout an ASIC/FPGA and maintaining their content consistency


An immersion lithography apparatus includes a projection system having a final optical element and a stage that is movable to a position below the projection system such that a gap exists between the final optical element and a surface of the stage. An immersion liquid fills the gap between the surface and the final optical element. A liquid confinement member maintains the immersion liquid in the gap. The immersion liquid has a meniscus where the liquid contacts ambient gas, the meniscus defining a footprint of an immersion area. A movable liquid diverter is positioned between the liquid confinement member and the stage. The movable liquid diverter moves relative to the liquid confinement member in a direction parallel to the surface of the stage, and includes an opening that surrounds the immersion area, the opening contacting or being slightly spaced from the immersion area when the stage is stationary.

The invention relates to immersion lithography apparatus and methods, and particularly to apparatus and methods for controlling the immersion liquid between the projection system and the substrate.
A typical lithography apparatus includes a radiation source, a projection optical system and a substrate stage to support and move a substrate to be imaged. A radiation-sensitive material, such as a resist, is coated onto the substrate surface before the substrate is placed on the substrate stage. During operation, radiation energy from the radiation source is used to project an image defined by an imaging element (such as, for example, a mask) through the projection optical system onto the substrate. The projection optical system typically includes a plurality of lenses. The lens or optical element closest to the substrate can be referred to as the last or final optical element.
The projection area during an exposure is typically much smaller than the imaging surface of the substrate. The substrate therefore has to be moved relative to the projection optical system to pattern the entire surface of the substrate. In the semiconductor industry, two types of lithography apparatus are commonly used. With so-called "step and repeat" apparatus, the entire image pattern is projected at once in a single exposure onto a target area of the substrate. After the exposure, the wafer is moved or "stepped" in the X and/or Y direction and a new target area is exposed. This step and repeat process is performed over and over until the entire substrate surface is exposed. With scanning type lithography apparatus, the target area is exposed in a continuous or "scanning" motion. The imaging element is moved in one direction, while the substrate is moved in either the same or the opposite direction during exposure. After each scan, the substrate is then moved in the X and/or Y direction to the next scan target area. This process is repeated until all the desired areas on the substrate have been exposed.
Lithography apparatus are typically used to image or pattern semiconductor wafers and flat panel displays. The term "substrate", as used herein, is intended to generically mean any work piece that can be patterned, including, but not limited to, semiconductor wafers and flat panel displays.
Immersion lithography systems use a layer of fluid that fills a gap between the final optical element of the projection optical system and the substrate. The fluid enhances the resolution of the system by enabling exposures with a numerical aperture (NA) greater than one, which is the theoretical limit for conventional "dry" lithography. The fluid in the gap permits the exposure with radiation that would otherwise be completely internally reflected at the optical-air interface. With immersion lithography, numerical apertures as high as the index of refraction of the fluid are possible. Immersion also increases the depth of focus for a given NA, which is the tolerable error in the vertical position of the substrate, compared to a conventional dry lithography system. Immersion lithography therefore has the ability to provide greater resolution than can be performed using conventional dry lithography, as the fluid essentially becomes part of the optical system of the lithography apparatus.
One known way of maintaining the immersion fluid in the gap where exposure of the substrate is to occur is with the use of an air curtain. For more information on air curtain type immersion apparatus, see for example U.S. Patent Publication No. 2005/0007569, the disclosure of which is incorporated herein by reference in its entirety.
It is also known to maintain the immersion fluid in the gap between the final optical element and the imaging surface of the substrate by submersing both in a container filled with immersion fluid. See, for example, U.S. Pat. No. 4,509,852, the disclosure of which is incorporated herein by reference in its entirety.
Another known way of maintaining the immersion fluid within the gap of an immersion lithography apparatus is with the use of a confinement member that surrounds the final optical element immediately above the area to be exposed on the substrate. For more information on confinement member type immersion lithography apparatus, see U.S. Pat. No. 7,292,313 and WO 2005/111722, the disclosure of each of which is incorporated herein by reference in its entirety.
In yet another approach, which is a variation of the above-described submersion type apparatus, a large confinement plate is used for submerging the substrate to be imaged in the immersion fluid. For more details on confinement plate type immersion lithography apparatus, see U.S. Patent Publication No. 2007/0279608, the disclosure of which is incorporated herein by reference in its entirety.
During semiconductor wafer fabrication, for example, wafers are typically patterned one after another by the lithography tool. After a wafer has been patterned, it is replaced and the next wafer is exposed. This process is completed over and over, typically as fast as possible, to increase throughput. During a wafer exchange, the just exposed wafer typically has to be moved a relatively long distance from the exposure area to the wafer exchange area. This movement preferably is performed at a relatively high speed. Once the exchange takes place, the new wafer undergoes another relatively long-move to an alignment area. This movement also preferably is performed at a relatively high speed. After alignment, the wafer undergoes yet another long-move back to the exposure area for exposure. This movement also preferably is performed at a relatively high speed. For the sake of simplicity, all of the above-described moves are hereafter generically referred to as "long-moves".
It also is desirable to move from target area to target area on a substrate during the exposure operation at a relatively high speed. Furthermore, when exposure of a target area begins in a scanning exposure apparatus, it is desirable to accelerate at as high a rate as possible at the beginning of the scanning movement and to scan across the target area during exposure of the target area at as high a speed as possible.
High speed movements are desirable in order to increase the throughput (the rate of production) of the exposure process performed by the lithography apparatus.
High speed moves can be problematic with confinement member type immersion apparatus. In particular, if the speed is too fast, there is a tendency for the immersion fluid to leak out from under the confinement member, leaving a trail of water (or other liquid if a liquid other than water is used as the immersion fluid) behind on the substrate. Liquid that escapes from the liquid confinement member also can scatter inside the exposure apparatus, which can deteriorate components of the exposure apparatus and/or adversely change the environmental conditions (for example, temperature and humidity) within the apparatus.
U.S. Patent Publication No. 2007/0110213 discloses a plate disposed on a barrier member that confines a liquid between the projection system and the substrate. The plate separates the liquid-filled space between the barrier member and the substrate into upper and lower channels, such that a meniscus is formed in each of the channels.

Immersion lithography apparatus and method having movable liquid diverter between immersion liquid confinement member and substrate


Exemplary embodiments may disclose a wide angle lenses including: a first lens which has a negative refractive power; a second lens which has a positive refractive power; a third lens which has the positive refractive power; a fourth lens which has the negative refractive power; and a fifth lens which has the positive refractive power, wherein the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are in an order from an object to an image, wherein the wide angle lenses satisfy a condition of 0.2<f/BFL14<0.25, wherein f denotes an overall effective focal length of the wide angle lenses and BFL14 denotes a combined back focal length of the first lens through the fourth lens.

1. Field
Exemplary embodiments relate to a wide angle lens and a photographing apparatus, including the wide angle lens. More particularly, exemplary embodiments relate to a wide angle lens having excellent short distance performance, high optical performance, and a lightweight focus group, and a photographing apparatus including the wide angle lens.
2. Description of the Related Art
A solid image capturing device of the related art, such as a charge-coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS), may become small and realize a high pixel resolution. Further, according to user demand, a lens system included in an image forming device of the related art, such as a digital camera, a video camera, and a surveillance camera needs to have improved optical performance and become small.
The user demand is increasing for a wide viewing angle, a small size, and a high performance, short distance photographing. This user demand has been increasing for a lens system included in a video presenter and a microscope.

Wide angle lens and photographing apparatus including the same


A method and apparatus are disclosed for treating mitral regurgitation with electrical stimulation. By providing pacing stimulation to the left atrium during ventricular systole, a beneficial effect is obtained which can prevent or reduce the extent of mitral regurgitation.

The tricuspid and mitral valves, also referred to as the atrioventricular valves, separate the atrium and ventricle on the right and left sides of heart, respectively. The function of the atrioventricular valves is to allow flow of blood between the atrium and ventricle during ventricular diastole and atrial systole but prevent the backflow of blood during ventricular systole. The mitral valve is composed of a fibrous ring called the mitral annulus located between the left atrium and the left ventricle, the anterior and posterior leaflets, the chordae tendineae, and the papillary muscles. The leaflets extend from the mitral annulus and are tethered by the chordae tendineae to the papillary muscles which are attached to the left ventricle. The function of the papillary muscles is to contract during ventricular systole and limit the travel of the valve leaflets back toward the left atrium. If the valve leaflets are allowed to bulge backward into the atrium during ventricular systole, called prolapse, leakage of blood through the valve can result. The structure and operation of the tricuspid valve is similar.
Mitral regurgitation (MR), also referred to as mitral insufficiency or mitral incompetence, is characterized by an abnormal reversal of blood flow from the left ventricle to the left atrium during ventricular systole. This occurs when the leaflets of the mitral valve fail to close properly as the left ventricle contracts, thus allowing retrograde flow of blood back into the left atrium. Tricuspid regurgitation (TR) occurs in a similar manner. MR and TR can be due to a variety of structural causes such as ruptured chordae tendineae, leaflet perforation, or papillary muscle dysfunction. Functional MR and TR may also occur in heart failure patients due to annular dilatation or myocardial dysfunction, both of which may prevent the valve leaflets from coapting properly.
In acute mitral valve regurgitation, the incompetent mitral valve allows part of the ventricular ejection fraction to reflux into the left atrium. Because the atrium and ventricle are not able to immediately dilate, the volume overload of the atrium and ventricle results in elevated left atrial and pulmonary venous pressures and acute pulmonary edema. The reduction in forward stroke volume due to the reflux through the regurgitant valve reduces systemic perfusion, which if extreme enough can lead to cardiogenic shock. In chronic mitral valve regurgitation, on the other hand, the left atrium and ventricle dilate over time in response to the volume overload which acts as a compensatory mechanism for maintaining adequate stroke volume. The left ventricular dilatation, however, may further prevent proper coaptation of the mitral valve leaflets during systolic ejection, leading to progression of the left ventricular dilatation and further volume overload. Patients with compensated MR may thus remain asymptomatic for years despite the presence of severe volume overload, but most people with MR decompensate over the long term and either die or undergo a corrective surgical procedure.

Atrial pacing therapy for treating mitral regurgitation


An electric valve includes a valve member switchable between a closing state to close a flow passageway of a valve body and an opening state to open the passageway. An adaptor is connected to the valve member. A motor drives rotation of a rotation shaft connected to the adaptor. A circuit board is electrically coupled to the motor and a backup battery pack. A microprocessor control unit is electrically coupled to the circuit board. The motor drives the valve member through the rotation shaft and the adaptor to switch between the opening and closing states. The microprocessor control unit controls a time delay for switching the valve member from the opening state to the closing state.

The conventional electric valve is electrically switchable from an opening state to a closing state for a fluid flow therethrough. In use, after receiving a valve close signal, the conventional electric valve immediately switches from the opening state to the closing state so that the fluid flow is immediately stopped from passing through the conventional electric valve. Because there is no time delay for the conventional electric valve to switch from the opening state to the closing state, the conventional electric valve is unable to control an amount of the fluid flow therethrough after receiving the valve close signal. In addition, during a power outage, the conventional electric valve cannot function and has to be operated by hand.


The present invention relates to a method for the preparation of citalopram or any of its enantiomers and acid addition salts thereof comprising reaction of a compound of formula II

The present invention relates to a method for the preparation of the well known anti-depressant drug citalopram, 1-[3-(dimethylamino)propyl]-1-(4-fluorophenyl)-1, 3-dihydro-5-isobenzofurancarbonitrile.
Citalopram is a well-known antidepressant drug that has now been on the market for some years and has the following structure:
It is a selective, centrally acting serotonin (5-hydroxytryptamine; 5-HT) reuptake inhibitor, having antidepressant activities. The antidepressant activity of the compound has been reported in several publications, e.g. J. Hyttel, Prog. Neuro-Psychopharmacol. and Biol. Psychiat., 1982, 6, 277-295 and A. Gravem, Acta Psychiatr. Scand., 1987, 75, 478-486. The compound has also been disclosed to show effects in the treatment of dementia and cerebrovascular disorders, EP-A 474580.
Citalopram was first disclosed in DE 2,657,271 corresponding to U.S. Pat. No. 4,136,193. This patent publication describes the preparation of citalopram by one method and outlines a further method that may be used for preparing citalopram.
According to the process described, the corresponding 1-(4-fluorophenyl)-1, 3-dihydro-5-isobenzofurancarbonitrile is reacted with 3-(N,N-dimethylamino)propyl-chloride in the presence of methylsulfinylmethide as condensing agent. The starting material was prepared from the corresponding 5-bromo derivative by reaction with cuprous cyanide.
According to the second method, which is only outlined in general terms, citalopram may be obtained by ring closure of the compound:
in the presence of a dehydrating agent and subsequent exchange of the 5-bromo group with cyano using cuprous cyanide. The starting material of formula II is obtained from 5-bromophthalide by two successive Grignard reactions, i.e. with 4-fluorophenyl magnesium chloride and N,N-dimethylaminopropyl magnesium chloride, respectively.
A new and surprising method and an intermediate for the preparation of citalopram were described in U.S. Pat. No. 4,650,884 according to which an intermediate of the formula
is subjected to a ring closure reaction by dehydration with strong sulfuric acid in order to obtain citalopram. The intermediate of formula III was prepared from 5-cyanophthalide by two successive Grignard reactions, i.e. with 4-fluorophenyl magnesium halogenide and N,N-dimethylaminopropyl magnesium halogenide, respectively.
Further processes are disclosed in International patent application Nos. WO 98/019511, WO 98/019512 and WO 98/019513. WO 98/019512 and WO 98/019513 relate to methods wherein a 5-amino-, 5-carboxy- or 5-(sec. ammocarbonyl)phthalide is subjected to two successive Grignard reactions, ring closure and conversion of the resulting 1,3-dihydroisobenzofuran derivative to the corresponding 5-cyano compound, i.e. citalopram. International patent application No. WO 98/019511 discloses a process for the manufacture of citalopram wherein a (4-substituted-2-hydroxymethylphenyl-(4-fluorphenyl)methanol compound is subjected to ring closure and the resulting 5-substituted 1-(4-fluorophenyl)-1,3-dihydroisobenzofuran converted to the corresponding 5-cyano derivative and alkylated with a (3-dimethylamino)propylhalogenide in order to obtain citalopram.
Finally, methods of preparing the individual enantiomers of citalopram are disclosed in U.S. Pat. No. 4,943,590 from which it also appears that the ring closure of the intermediate of formula III may be carried out via a labile ester with a base.
It has now been found that citalopram may be obtained by a new process in which the citalopram skeleton is formed by Diels-Adler reaction of a dihydrobenzofurane with a diene.
Accordingly, the present invention relates to a novel method for the preparation of citalopram, its enantiomers and acid addition salts thereof comprising:
Reaction of a compound of formula
with
a) a diene having the formula III
wherein X is selected from O, S, SO2, xe2x80x94Nxe2x95x90Nxe2x80x94, xe2x80x94COxe2x80x94Oxe2x80x94 and xe2x80x94Oxe2x80x94COxe2x80x94, followed by oxidation to form citalopram,
or with
b) a compound of formula
wherein R is alkyl, or optionally substituted aryl or arylalkyl, followed by conversion of the resulting compound of formula
wherein R is as defined above to a compound of formula
which is converted to a compound of formula
followed by oxidation of the compound of formula VII to form citalopram.
The reaction of the compound of formula II with the diene of formula III is carried out using the conventional reaction conditions for carrying out reactions of the Diels-Adler type. Thus, the reaction is suitably carried out in a solvent, such as benzene, toluene, 1, 3,5-trimethylbenzene; at a temperature between 60 and 180xc2x0 C., preferably at reflux.
Initial reaction of the compound of formula II with the diene of formula III leads to the formation of the intermediate having the formula
wherein X is as defined above.
Oxidation of the intermediate of formula IIxe2x80x2 leads to the formation of citalopram.
The oxidation of the intermediate of formula IIxe2x80x2 is carried out in presence of oxygen and agents such as Pd/C, S, dideoxyquinon, and chloranil.
In some cases, i.e. where the compound of formula III is a 3-cyanofuran, the conversion of the intermediate of formula IIxe2x80x2 to citalopram is carried out in presence of a Lewis acid or a mineral acid. Suitable Lewis acids include ZnCl2, TiCl4, BF3 Et2O etc. Suitable mineral acids include hydrochloric acid, sulfuric acid etc.
When the compound of formula III used in the process is the 3-cyanofuran, the intermediate of formula IIxe2x80x2 may be isolated.
The reaction of the compound of formula II with the compound of formula IV is carried out using the conventional reaction conditions for carrying out reactions of the Diels-Adler type. Thus, the reaction is suitably carried out in an inert solvent, such as benzene, toluene, 1, 3,5-trimethylbenzene; at a temperature between 60 and 180xc2x0 C., preferably at reflux. The aryl and arylalkyl substituents R in formula IV may be substituted with substituents such as halogen, alkyl, alkoxy, etc.
The conversion of the compound of formula V to a compound of formula VI is suitably carried out in an aqueous acidic media or in an aqueous alkaline media.
The introduction of the cyano group into the compound of formula VI, is suitably carried out by reaction of a compound of formula VI with NaCN, KCN, or TMSCN in an aqueous media followed by dehydration using conventional dehydrating agents such as thionylchloride, POCl3, P2O5 or a Vilsmeier reagent. When TMSCN is used, the reaction is suitably carried out in presence of a Lewis acid such as ZnCl2, ZnI2 or BF3, Et2O.
The compound of formula VII is oxidised to form citalopram in presence of oxygen and agents such as Pd/C, dideoxyquinon, chloranil etc.
In a further aspect, the invention relates to the above processes in which the compound of formula II is used in the form of the S-enantiomer.
In yet another aspect, the present invention relates to citalopram and S-citalopram manufactured by the process of the invention, and an antidepressant pharmaceutical composition comprising citalopram or S-citalopram manufactured by the process of the invention.

Method for the preparation of citalopram

Abstract: with a diene having the formula

Abstract: wherein X is O, S, SO2, xe2x80x94Nxe2x95x90Nxe2x80x94, xe2x80x94COxe2x80x94Oxe2x80x94, xe2x80x94Oxe2x80x94COxe2x80x94, or

Abstract: or with a diene having the formula

Abstract: wherein R is alkyl or optionally substituted aryl or arylalkyl.

Abstract: The invention also relates to intermediates used in the new process for the preparation of citalopram, as well as citalopram prepared according to the new process.


A thermoplastic composition which is obtained by melt-kneading (1) 55 to 75 wt. % crystalline polypropylene resin together with (2) 10 to 30 wt. % elastomer comprising either a rubber containing a vinyl aromatic compound or a mixture thereof with an ethylene/xcex1-olefin random copolymer rubber and (3) 15 to 25 wt. % talc having an average particle diameter of 3 xcexcm or smaller. The composition satisfies specific requirements with respect to: the long period obtained by X-ray small-angle scattering attributable to the vinyl aromatic-containing rubber in a blend obtained by melt-kneading the ingredients (1) and (2); the shape and diameter of the elastomer particles present near the polypropylene/elastomer interface in the blend; and the difference between the glass transition point of the ingredient (1) and that of the composition attributable to the crystalline polypropylene homopolymer parts. The composition has a satisfactory balance between impact resistance and rigidity and has excellent injection moldability.

This invention relates to a thermoplastic resin composition having excellent characteristic features in rigidity, impact resistance and moldability and to injection moldings excellent in dimensional stability formed therefrom by an injection molding method, particularly injection moldings for automobile if interior and exterior trims.
In recent years, propylene-ethylene block copolymers have been used as automobile materials from the view points of weight reduction and cost reduction. However, previous propylene-ethylene block copolymer materials are low in impact resistance; to improve the impact resistance, it has been proposed to compound into propylene-ethylene block copolymers an ethylene-propylene copolymer rubber, ethylene-xcex1-olefin copolymer rubber or the like. When an ethylene-propylene copolymer rubber, ethylene-xcex1-olefin copolymer rubber or the like is compounded, however, though the resulting composition is improved in impact strength, the composition conversely shows a lowered rigidity and deteriorated thermal properties such as heat distortion temperature, and hence has difficulties for use as automobile interior and exterior trim materials. To solve the problems, it has been proposed to compound additionally into the composition inorganic fillers, such as calcium carbonate, barium sulfate, mica, crystalline calcium silicate and talc.
For example, JP-A-51-136735 discloses a thermoplastic resin composition comprising an ethylene-block copolymer mainly based on propylene, an ethylene-propylene rubber and talc, and describes the physical properties thereof. It also describes, only in general, that styrene-butadiene rubbers can be used similarly to the ethylene-propylene rubber, but it describes nothing about the structure and state of the product obtained by melt-kneading the rubber and about the molecular weight distribution, melt flow rate, styrene content, etc. of the rubber.
JP-A-6-192,500 discloses a propylene-based resin composition comprising a propylene-ethylene block copolymer and an ethylene-1-hexene copolymer. It further describes as additional compounding ingredients, the blend of talc or the like, which are auxiliary additive components conventionally used in the process for producing resin compositions, and styrene-butadiene type rubbers or the like. However, it describes nothing about the structure and state of the product obtained by melt-kneading the rubber and about the molecular weight distribution, melt flow rate, styrene content, etc. of the rubber.
JP-A-6-192506 discloses a polypropylene composition comprising polypropylene, ethylene-1-octene random copolymer and talc, but it describes nothing of the use of vinyl aromatic compound-containing rubbers.
As described above, previous resin compositions comprising a propylene-ethylene block copolymer, ethylene-propylene copolymer rubber or ethylene-xcex1-olefin copolymer rubber and inorganic filler have been, as automobile interior and exterior trim materials, still insufficient in the balance of impact strength with rigidity and in injection moldability. Further, prior technologies for using styrene-butadiene type rubbers or the like have also been unsatisfactory.
Under such circumstances, the object of this invention is to provide a polypropylene-based resin composition comprising a crystalline polypropylene-based resin, elastomer and talc which satisfies, in respect of physical properties, the impact resistance and rigidity required for automobile interior and exterior trim materials and is excellent in injection moldability and to provide injection moldings thereof, particularly injection moldings for automobile interior and exterior trim uses.
The present inventors have found that a polypropylene-based resin composition and injection moldings thereof which can meet the above-mentioned objects can be obtained by using a specific crystalline polypropylene-based resin as the main component and melt-kneading therewith, in specific compounding ratios, a specific elastomer component and talc, and resultantly attained this invention.
Thus, this invention relates to a thermoplastic resin composition which is obtained by melt-kneading a mixture comprising (1) 55-75% by weight of a crystalline polypropylene-based resin, (2) 10-30% by weight of an elastomer comprising a vinyl aromatic compound-containing rubber or comprising a vinyl aromatic compound-containing-rubber and an ethylene-xcex1-olefin random copolymer rubber and (c) 15-25% by weight of talc having an average particle diameter of not more than 3 xcexcm, and which satisfies the following conditions (a)-(c):
(a) when the crystalline polypropylene-based resin (1) has been melt-kneaded with the elastomer (2) comprising a vinyl aromatic compound-containing rubber or comprising a vinyl aromatic compound-containing rubber and an ethylene-a-olefin random copolymer rubber, the long period obtained by small angle X-ray scattering attributable to the vinyl aromatic compound-containing rubber is 12-24 nm,
(b) when the crystalline polypropylene-based resin (1) has been melt-kneaded with the elastomer (2) comprising a vinyl aromatic compound-containing rubber or comprising a vinyl aromatic compound-containing rubber and an ethylene-xcex1-olefin random copolymer rubber, elastomer particles which undergo micro phase separation to have the form of particle, and are present in the vicinity of the interface between particles of the elastomer and the crystalline polypropylene-based resin as matrix, have a particle diameter of not more than 30 nm, and
(c) the difference between the glass transition point (Tg1) assigned to the crystalline propylene homopolymer portion of the crystalline polypropylene-based resin (1) and the glass transition point (Tg2) assigned to the crystalline propylene homopolymer portion of a composition obtained by melt-kneading the crystalline polypropylene-based resin (1) with the elastomer (2) comprising a vinyl aromatic compound-containing rubber or comprising a vinyl aromatic compound-containing rubber and an ethylene-xcex1-olefin random copolymer rubber and talc (3) (that is, xcex94Tg=Tg1xe2x88x92Tg2) is 4.0-7.0xc2x0 C.
This invention also relates to injection moldings formed from the above-mentioned polypropylene-based resin composition by an injection molding method.
This invention further relates to injection moldings for automobile interior and exterior trim uses.
This invention is described in detail below.
The thermoplastic resin composition of this invention is a composition obtained by melt-kneading a mixture comprising (1) 55-75% by weight of a crystalline polypropylene-based resin, (2) 10-30% by weight of an elastomer comprising a vinyl aromatic compound-containing rubber or comprising a vinyl aromatic compound-containing rubber and an ethylene-xcex1-olefin random copolymer rubber and (3) 15-25% by weight of talc having an average particle diameter of not more than 3 xcexcm.
The crystalline polypropylene-based resin (1) used in this invention is not particularly limited so long as it is crystalline and may be, for example, propylene homopolymers, propylene-ethylene copolymers and propylene-xcex1-olefin copolymers. The xcex1-olefin in the copolymer has at least 4 carbon atoms and may be, for example, butene, pentene, hexene, heptene, octene, decene and the like.
Particularly preferably used crystalline polypropylene-based resin (1) is a crystalline polypropylene selected from a crystalline ethylene-propylene block copolymer (1A) or a mixture (1B) of the crystalline ethylene-propylene block copolymer (1A) with a crystalline propylene homopolymer.
The crystalline ethylene-propylene block copolymer (1A) herein referred to is a crystalline ethylene-propylene block copolymer consisting essentially of a propylene homopolymer portion (hereinafter referred to as the first segment) and an ethylene-propylene random copolymer portion (hereinafter referred to as the second segment).
The propylene homopolymer portion, which is the first segment, has a Q value of preferably 3.0-5.0, more preferably 3.5-4.5, which value is the weight average molecular weight (Mw)/number average molecular weight (Mn) ratio determined by the gel permeation chromatography (GPC) method. Further, the portion has an isotactic pentad fraction of preferably not less than 0.98, more preferably not less than 0.99, as calculated from its 13C-NMR, and has an intrinsic viscosity [xcex7]p of preferably 0.7-1.1 dl/g, more fit preferably 0.8-1.0 dl/g as measured in tetralin solution at 135xc2x0 C.
When the Q value of the propylene homopolymer portion of the first segment is less than 3.0, the fluidity tends to be poor, and when the Q value exceeds 5.0, a good result cannot be obtained in the balance of rigidity with impact resistance in some cases. Further, when the isotactic pentad fraction of the portion is less than 0.98, it is difficult to attain the intended rigidity, heat resistance and the like in some cases. When the intrinsic viscosity [xcex7]p of the portion is less than 0.7 dl/g the impact strength tends to be low, and when it exceeds 1.1 dl/g, the fluidity tends to deteriorate.
The ethylene-propylene random copolymer portion of the second segment has an intrinsic viscosity [xcex7]EP of preferably 5.0-8.0 dl/g, more preferably 5.5-7.5 dl/g as determined in tetralin solution at 135xc2x0 C., and has an ethylene content [(C2xe2x80x2)EF] of preferably 25-35% by weight, more preferably 27-33% by weight.
When the intrinsic viscosity [xcex7]EP of the ethylene-propylene random copolymer portion of the second segment is less than 5.0 dl/g, a good result cannot be obtained in the balance of rigidity with impact resistance in some cases. When it exceeds 8.0 dl/g, hard spots tend to develop and a good result cannot be obtained in respect of surface quality in some cases. When the ethylene content [(C2xe2x80x2)EP] of the portion is less than 25% by weight or higher than 35% by weight, a good result cannot be obtained in respect of the impact resistance of the composition in some cases.
The ratio of the ethylene-propylene random copolymer portion (the second segment) to the propylene homopolymer portion (the first segment) (namely, the second segment/the first segment) by weight is preferably 8/92 to 35/65.
The crystalline propylene homopolymer used in the above-mentioned mixture (1B) of the crystalline ethylene-propylene block copolymer (1A) with the crystalline propylene homopolymer is a polymer which have similar physical properties to those of the propylene homopolymer portion of the first segment. Thus, it has a Q value of 3.0-5.0, preferably 3.5-4.5, which value is the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) determined by the gel permeation chromatography (GPC) method, an isotactic pentad fraction, calculated from its 13C-NMR, of preferably not less than 0.98, more preferably not less than 0.99, and an intrinsic viscosity [xcex7]p of preferably 0.7-1.1 dl/g, more preferably 0.8-1.0 dl/g as determined in tetralin solution at 135xc2x0 C.
When the Q value of the crystalline propylene homopolymer used in the mixture (1B) of the crystalline ethylene-propylene block copolymer (1A) with a crystalline propylene homopolymer is less than 3.0, the fluidity tends to be poor, and when it exceeds 5.0, an unfavorable result is obtained in the balance of rigidity with impact resistance in some cases. Further, when the isotactic pentad fraction is less than 0.98, the intended rigidity, heat resistance and the like are hardly attained in some cases. Further, when the intrinsic viscosity [xcex7]p is less than 0.7 dl/g, the impact resistance tends to be low, and when it exceeds 1.1 dl/g, the fluidity tends to be poor.
The crystalline polypropylene-based resin (1) can be produced by using a Ziegler-Natta catalyst system and/or a metallocene catalyst system according to a bulk polymerization method, a solution polymerization method, a slurry polymerization method, a gas phase polymerization method, or any desired combination of these polymerization methods.
When the ethylene-propylene block copolymer is used in applications wherein a high impact resistance is particularly required, the block copolymer is preferably a product obtained by polymerizing propylene in the first step to produce a crystalline propylene homopolymer portion of the first segment and then polymerizing ethylene and propylene in the second step to produce an ethylene-propylene random copolymer portion of the second segment.
In the thermoplastic resin composition of this invention, the content of the crystalline polypropylene-based resin (1) is preferably 55-75% by weight relative to the whole of the composition.
Description is given below of the elastomer (2) comprising a vinyl aromatic compound-containing rubber or comprising a vinyl aromatic compound-containing rubber and an ethylene-xcex1-olefin random copolymer rubber used in this invention.
The vinyl aromatic compound-containing rubber (2A) referred to in this invention is a block copolymer composed of a vinyl aromatic compound polymer block and a conjugated diene-based polymer block wherein 80% or more, preferably 85% or more of the double bonds of its conjugated diene portion have been hydrogenated and it has a Q value, determined by the GPC method, of preferably not more than 2.5, more preferably not more than 2.3, has a vinyl aromatic compound content in the vinyl aromatic compound-containing rubber of preferably 10-20% by weight, more preferably 12-19% by weight, and has a melt flow rate (hereinafter referred to as xe2x80x9cMFRxe2x80x9d) (according to JIS-K-6758, 230xc2x0 C.) of preferably 1-15 g/10 min, more preferably 2-13 g/10 min.
The vinyl aromatic compound-containing rubber (2A) in this invention is a rubber which comprises an olefin-based copolymer rubber or conjugated diene rubber and a vinyl aromatic compound bonded to said rubber through polymerization, reaction, etc., and may be, for example, such block copolymers as styrene-ethylene-butene-styrene type rubber (SEBS), styrene-ethylene-propylene-styrene type rubber (SEPS), styrene-butadiene type rubber (SBR), styrene-butadiene-styrene type rubber (SBS) and styrene-isoprene-styrene type rubber (SIS) and further block copolymers resulting from hydrogenation of the rubber components thereof. Rubbers obtained by reacting a vinyl aromatic compound, such as styrene, to an ethylene-propylene-non-conjugated diene type rubber (EPDM) may also be favorably used.
When the vinyl aromatic compound content in the vinyl aromatic compound-containing rubber (2A) is, on the average, lower than 10% by weight or higher than 20% by weight, the affinity of the rubber to the crystalline polypropylene-based resin (1) tends to be low, and resultantly the impact resistance and the rigidity tend to decrease.
The ethylene-xcex1-olefin random copolymer rubber used in this invention is a random copolymer rubber comprising ethylene and an xcex1-olefin and is not particularly limited so long as it is such a rubber. The xcex1-olefin has 3 or more, preferably 3-12 carbon atoms and is, for example, propylene, butene, pentene, hexene, heptene, octene, decene, and the like, preferred thereof being propylene, butene, hexene and octene.
The random copolymer rubber is, for example, an ethylene-propylene random copolymer rubber, ethylene-butene random copolymer rubber, ethylene-hexene random copolymer rubber, ethylene-octene random copolymer rubber, and the like. Preferred examples thereof are an ethylene-octene random copolymer rubber (2B), ethylene-butene random copolymer rubber (2C) and ethylene-propylene random copolymer rubber (2D).
The ethylene-octene random copolymer rubber (2B) used in this invention has a Q value, determined by the GPC method, of preferably not more than 2.5, more preferably not more than 2.3, and has an octene content of 15-45% by weight, preferably 18-42% by weight. The ethylene-octene random copolymer rubber has a MFR (according to JIS-K-6758, 190xc2x0 C.) of preferably 1.0-15.0 g/10 min, more preferably 2-13 g/10 min.
When the Q value, determined by the GPC method, of the ethylene-octene random copolymer rubber (2B) exceeds 2.5, the rigidity tends to decrease in some cases. When the octene content in the ethylene-1-octene random copolymer rubber (2B) is less than 15% by weight, this is unfavorable in respect of the impact resistance; when it exceeds 45% by weight, a favorable result cannot be obtained in respect of the rigidity. When the MFR of the ethylene-octene random copolymer rubber (2B) exceeds 15 g/10 min, this is unfavorable in respect of the impact resistance; and when it is lower than 1.0 g/10 min, the dispersion of the rubber in the crystalline polypropylene-based resin (1) tends to be poor, leading to an unfavorable result in respect of the impact resistance.
The ethylene-1-butene random copolymer rubber (2C) used in this invention has a Q value, determined by the GPC method, of preferably not more than 2.7, more preferably not more than 2.5, and has a butene content of preferably 15-35% by weight, more preferably 17-33% by weight. The ethylene-butene random copolymer rubber (2C) has a MFR (according to JIS-k-6758, 190xc2x0 C.) of preferably 1-15 g/10 min, more preferably 2-13 g/10 min.
When the Q value, determined by the GPC method, of the ethylene-butene random copolymer rubber (2C) exceeds 2.7, the rigidity tends to decrease in some cases. When the butene content in the ethylene-butene random copolymer rubber (2C) is less than 15% by weight, this is unfavorable in respect of the impact resistance; when it exceeds 35% by weight, a favorable result cannot be obtained in respect of the rigidity. When the MFR of the ethylene-butene random copolymer rubber is lower than 1 g/10 min, this is unfavorable in respect of the rigidity and impact resistance; when it exceeds 15 g/10 min, the dispersion of the rubber in the crystalline polypropylene-based resin (1) tends to be poor, leading to an unfavorable result in respect of the impact resistance.
The ethylene-propylene random copolymer rubber (2D) has a Q value, determined by the GPC method, of preferably not more than 2.7, more preferably not more than 2.5, has a propylene content of 20-30% by weight, preferably 22-28% by weight, and has a MFR (according to JIS-K-6758, 190xc2x0 C.) of preferably 1-15 g/10 min, more preferably 2-13 g/10 min.
When the Q value, determined by the GPC method, of the ethylene-propylene random copolymer rubber (2D) exceeds 2.7, the rigidity tends to decrease. When the propylene content in the ethylene-propylene random copolymer rubber (2D) is lower than 20% by weight, this is unfavorable in respect of the impact resistance; when it exceeds 30% by weight, a favorable result cannot be obtained in respect of the rigidity in some cases. When the MFR of the ethylene-propylene random copolymer rubber (2D) is less than 1 g/10 min, this is unfavorable in respect of the rigidity and impact resistance; when it exceeds 15 g/10 min, the dispersion of the rubber in the crystalline polypropylene-based resin (1) tends to be poor, leading to an unfavorable result in respect of the impact resistance in some cases.
The ethylene-octene random copolymer rubber (2B), ethylene-butene random copolymer rubber (2C) and ethylene-propylene random copolymer rubber (2D) can be produced by copolymerizing ethylene with various xcex1-olefins with a catalyst system comprising a vanadium compound and an organoaluminum compound, Ziegler-Natta catalyst system or metallocene catalyst system through a solution polymerization method, slurry polymerization method, high pressure ionic polymerization method or gas phase polymerization method.
The content of the elastomer (2) comprising a vinyl aromatic compound-containing rubber or comprising a vinyl aromatic compound-containing rubber and an ethylene-xcex1-olefin random copolymer rubber relative to the whole of the thermoplastic resin composition of this invention is 10-30% by weight. When the content of the elastomer is less than 10% by weight, the impact resistance tends to decrease unfavorably; when it exceeds 30% by weight, the rigidity and the heat resistance tend to decrease unfavorably.
In using the above-mentioned rubber components (2A)-(2D), the respective contents of the various rubbers constituting the elastomer relative to the whole of the composition are, preferably, 3-15% by weight for the vinyl aromatic compound-containing rubber (2A), 0-15% by weight for the ethylene-octene random copolymer (2B), 0-10% by weight for the ethylene-butene random copolymer (2C) and 0-10% by weight for the ethylene-propylene random copolymer (2D).
In using the above-mentioned rubber components (2A)-(2D), it is preferable that the resulting resin composition contains the ethylene-octene random copolymer (2B), and it is further preferable that the composition contains both the ethylene-octene random copolymer (2B) and the ethylene-butene random copolymer (2C).
In the thermoplastic resin composition of this invention, furthermore, it is preferable that the contents (% by weight) and weight fractions of the respective components satisfy the following expressions 1)-3).
(Xpp)+(Xst)+(XEOR)+(XEBR)+(XEPR)+(Xtalc)=100,xe2x80x83xe2x80x831)
0.20xe2x89xa6{[(YBC)xc3x97(YEP)+(Xst)+(XEOR)+(XEBR)+(XEPR)]/100}xe2x89xa60.30,xe2x80x83xe2x80x832)
and
0.1xe2x89xa6{(YBC)xc3x97(YEP)/[(YBC)xc3x97(YEP)+(Xst)+(XEOR)+(XEPR)+(XEPR)]},xe2x80x83xe2x80x833)
wherein (Xpp) is the content (% by weight) of the crystalline polypropylene, (Xst) is that of the vinyl aromatic compound-containing rubber (2A), (XEOR) is that of the ethylene-octene random copolymer rubber (2B), (XEBR) is that of the ethylene-butene random copolymer rubber (2C) and (XEPR) is that of the ethylene-propylene random copolymer rubber (2D); (YBC) is the content (% by weight) of the crystalline ethylene-propylene block copolymer (1A), (YEP) is the weight fraction (weight fraction being content (% by weight)/100) of the ethylene-propylene random copolymer portion which is the second segment in the crystalline ethylene-propylene block copolymer (1A), and (Xtalc) is the content (% by weight) of talc.
When the numerical value of [(YBC)xc3x97(YEP)+(Xst)+(XEOR)+(XEBR)+(XEPR)]/100 in the above expression (2) is less than 0.20, the impact resistance tends to decrease unfavorably; when it exceeds 0.30, the fluidity tends to decrease unfavorably. When the numerical value of (YBC)xc3x97(YEP)/[(YBC)xc3x97(YEP)+(Xst)+(XEOR)+(XEBR)+(XEFR)] in the relational expression (3) for the weight fractions of respective components of the thermoplastic resin composition of this invention is less than 0.1, the impact resistance tends to decrease unfavorably.
The MFR (according to JIS-K-6758, 230xc2x0 C.) of the thermoplastic resin composition of this invention is preferably not less than 35 g/10 min, because when it is less than 35 g/10 min, the fluidity tends to be poor, resulting in lowered moldability.
The talc used in this invention is a product obtained by pulverizing magnesium silicate hydrate. The crystal structure of its molecule assumes a three-layer structure of pyrophyllite type, and talc is composed of said layers piled one upon another. Particularly preferred are those in the form of plate obtained by finely grinding the crystals approximately to the extent of unit layers.
The average particle diameter of the talc used in this invention is not more than 3 xcexcm. When it is more than 3 xcexcm, the impact resistance of the thermoplastic resin composition of this invention tends to decrease greatly, and the appearance, such as gloss, also tends to be poor. The talc may be used as such without being treated; however, it may also be used after its surface has been treated, for the purpose of enhancing the interfacial adhesiveness to the crystalline polypropylene-based resin (1) and enhancing the dispersibility, with various known silane coupling agents, titanium-coupling agents, higher fatty acids, higher fatty acid esters, higher fatty acid amides, higher fatty acid salts or other surfactants.
The average particle diameter of talc herein means a fifty percent particle diameter D50 determined from the integral distribution curve of the undersize method obtained by subjecting a suspension of talc particles in a dispersion medium, such as water, alcohol or the like, to measurement by using a centrifugal sedimentation particle size distribution measuring apparatus.
The content of the talc used in this invention is 15-25% by weight relative to the whole of the thermoplastic resin composition. When the content of talc to be used is less than 15% by weight, the rigidity and the heat resistance tend to decrease, whereas when it exceeds 25% by weight, the impact resistance tends to decrease unfavorably and the appearance also tends to be poor.
The thermoplastic resin composition of this invention satisfies the following conditions (a)-(c). That is, at first,
(a) when the crystalline polypropylene-based resin (1) has been melt-kneaded with the elastomer (2) comprising a vinyl aromatic compound-containing rubber or comprising a vinyl aromatic compound-containing rubber and an ethylene-a-olefin random copolymer rubber, it is necessary that the long period obtained by small angle X-ray scattering attributable to the vinyl aromatic compound-containing rubber is 12-24 nm.
The small angle X-ray scattering is, as described in known publications, for example, xe2x80x9cX-sen Kaisetsu no Tebiki (Guide to X-ray Diffraction), published by Rigaku Denki (K.K.), 1989 ed.)xe2x80x9d, scattering in a small angle region of 2{circle around (H)} of not more than several degrees, and the xe2x80x9clong periodxe2x80x9d refers to a periodic arrangement of crystalline portions and non-crystalline portions of approximately several ten to several hundred xc3x85. The long period attributable to the vinyl aromatic compound-containing rubber can be obtained by regarding diffraction peaks other than known diffraction peaks attributable to the crystalline polypropylene resin as attributable to the vinyl-aromatic compound-containing rubber.
The long period attributable to the vinyl-aromatic compound-containing rubber is preferably 12-23 nm. When it exceeds 24 nm, it greatly deviates from the long period of crystalline polypropylene-based resin, and resultantly the interfacial adhesive strength (interaction) between the elastomer phase and the crystalline polypropylene-based resin phase decreases.
(b) When the crystalline polypropylene-based resin (1) has been melt-kneaded with the elastomer comprising a vinyl aromatic compound-containing rubber or comprising a vinyl aromatic compound-containing rubber and an ethylene-xcex1-olefin random copolymer rubber, it is necessary that elastomer particles which undergo micro phase separation to have the form of particle, and are present in the vicinity of the interface between particles of the elastomer and polypropylene as matrix, have a particle diameter of not more than 30 nm.
The state of the vicinity of the interface between particles of the elastomer and crystalline polypropylene resin as matrix and the state of micro phase separation of elastomer particles present in the vicinity of the interface can be observed by a transmission type electron microscope (TEM). The shape of the particles can be judged by visually observing or photographing the transmitted image, and the particle diameter can be obtained by calculation based on the magnification of the microscope.
The particle diameter of the elastomer particles which undergo micro phase separation to have the form of particle, and are present in the vicinity of the interface between particles of the elastomer and polypropylene as matrix, are preferably not more than 25 nm. When the elastomer which is present in the vicinity of the interface between particles of the elastomer and crystalline polypropylene resin as matrix and undergo micro phase separation is in the form of rod or plate, or when, though it is in the form of particle, its diameter exceeds 30 nm, the impact resistance of the thermoplastic resin composition is decreased, and a favorable result cannot be obtained.
Furthermore, it is necessary that (c) the difference between the glass transition point (Tg1) assigned to the crystalline propylene homopolymer portion of the crystalline polypropylene-based resin (1) and the glass transition point (Tg2) assigned to the crystalline homopolymer portion of a composition obtained by melt-kneading the crystalline polypropylene-based resin (1) with the elastomer (2) comprising a vinyl aromatic compound-containing rubber or comprising a vinyl aromatic compound-containing rubber and an ethylene-xcex1-olefin random copolymer rubber and talc (3) (that is, xcex94Tg=Tg1xe2x88x92Tg2) is 4.0-7.0xc2x0 C.
The glass transition point herein referred to is the glass transition point in non-crystalline polymer, which is the temperature at which the non-crystalline polymer changes from the glass state to the rubber state (or conversely) and can be determined from the absorption peak obtained by the measurement of temperature dispersion of loss modulus. In the case of the crystalline polypropylene-based resin (1), in most instances only one glass transition point assigned to the crystalline propylene homopolymer portion is observed, which is designated Tg1. In the case of a polymer obtained by melt-kneading a mixture of a crystalline polypropylene-based resin (1), an elastomer (2) comprising a vinyl aromatic compound-containing rubber or comprising a vinyl aromatic compound-containing rubber and an ethylene-xcex1-olefin random copolymer rubber and talc (3), two glass transition points, that is, the glass transition point assigned to the crystalline propylene homopolymer portion and the glass transition point assigned to the elastomer portion are observed; of the two points, the glass transition point assigned to the crystalline propylene homopolymer portion is designated Tg2. From these two glass transition points, the difference (xcex94Tg=Tg1xe2x88x92Tg2) between the glass transition points assigned to the crystalline propylene homopolymer portion can be obtained.
When the difference (xcex94Tg=Tg1xe2x88x92Tg2) in the glass transition point assigned to the crystalline propylene homopolymer portion is less than 4.0, the affinity between the crystalline polypropylene resin (1) and the elastomer (2) comprising a vinyl aromatic compound-containing rubber or comprising a vinyl aromatic compound-containing rubber and an ethylene-xcex1-olefin random copolymer rubber tends to decrease greatly, resulting in the decrease of the impact resistance of the thermoplastic resin composition of this invention.
When the difference (xcex94Tg=Tg1xe2x88x92Tg2) in the glass transition point assigned to the crystalline propylene homopolymer portion exceeds 7.0xc2x0 C., the affinity tends to be in excess, resulting unfavorably in the decrease of the rigidity and the heat resistance of the thermoplastic resin composition of this invention, and the favorable result can not be obtained.
The thermoplastic resin composition of this invention can be produced by using a kneader, such as a single screw extruder, a twin screw extruder, a Banbury mixer, a hot roll or the like. The addition to and mixing in the kneader of the respective components may be conducted at the same time or may be conducted in portions. The operations may be conducted, for example, according to the following methods, but they are not limited thereto.
(Method 1)
A method which comprises kneading the crystalline polypropylene-based resin (1) with the talc (3) and then adding thereto the elastomer (2) (hereinafter abbreviated as xe2x80x9celastomerxe2x80x9d) comprising a vinyl aromatic compound-containing rubber or comprising a vinyl aromatic compound-containing rubber and an ethylene-xcex1-olefin random copolymer rubber.
(Method 2)
A method which comprises kneading the crystalline polypropylene-based resin (1) with talc in a high talc concentration beforehand to prepare a master batch and then separately kneading the master batch while diluting it with the crystalline polypropylene-based resin (1) and the elastomer (2), etc.
(Method 3)
A method which comprises kneading the crystalline polypropylene-based resin (1) with the elastomer (2), and then adding the talc (3) thereto and kneading the resulting mixture.
(Method 4)
A method which comprises kneading the crystalline polypropylene-based resin (1) with the elastomer (2) in a high elastomer concentration before-hand to prepare a master batch, and then adding thereto the crystalline polypropylene-based resin (1) and the talc (3) and kneading the resulting mixture.
(Method 5)
A method which comprises respectively kneading the crystalline polypropylene-based resin (1) with the talc (3) and the crystalline polypropylene-based resin (1) with the elastomer (2) beforehand and finally kneading them together.
The temperature required for the kneading is 170-250xc2x0 C., preferably 190-230xc2x0 C. The time necessary for the kneading is 1-20 minutes, preferably 3-15 minutes.
In these kneaders, in addition to these basic components, there can be compounded, as desired according to the objects of this invention, additives, such as an antioxidant, ultraviolet absorber, lubricant, pigment, antistatic agent, copper inhibitor, flame retardant, neutralizing agent, foaming agent, plasticizer, nucleating agent, foam inhibitor, cross-linking agent and the like.
The thermoplastic resin composition of this invention can be used for producing moldings of various shapes by the conventionally used injection molding method. The injection moldings thus obtained are suitably used particularly as automobile interior and exterior trim parts, such as a door trim, pillar, instrumental panel, bumper, and the like.

Thermoplastic resin composition and injection-molded object thereof


An image capturing apparatus for acquiring images having high dynamic range. The image capturing apparatus includes CCD consisting of a first photo detector for detecting light from central area of a subject, a second photo detector for detecting light from marginal area of the subject, a photometry sensor for measuring brightness of the central and the marginal areas of the subject, and a sensitivity control unit for controlling sensitivity of the first photo detector based on the brightness of the central area measured by the photometry sensor and controlling sensitivity of the second photo detector based on the brightness of the marginal area measured by the photometry sensor.

1. Field of the Invention
The present invention relates to an image capturing apparatus, an image capturing method, and a computer-readable medium storing program. More particularly, the present invention relates to an image capturing apparatus which obtains images having high dynamic range.
2. Description of Related Art
Image capturing apparatuses, such as digital cameras and video cameras, obtain an image by converting an optical image of a subject into an electrical signal by image sensing devices, such as CCD and MOS. However, the dynamic range of these image sensing devices is remarkably lower than dynamic range that exists in real life. Consequently, a conventional image capturing apparatus adjusts optical information of a main subject within the dynamic range of the image sensing devices to obtain an image using an optical stop, an electronic shutter and the like. For this reason, when a subject includes an area having high dynamic range, there has been a problem that the conventional image capturing apparatus can obtain only images that ranges from a predetermined brightness to a predetermined darkness.
A Japanese patent application publication No. 11-32242 discloses an image capturing apparatus which generates images with high dynamic range by compounding signals acquired by a plurality of CCDs having different sensitivity. Also, a Japanese patent application publication No. 5-260391 discloses an image capturing apparatus, where the image capturing apparatus is adapted to increase the amount of charges by reading charge pattern accumulated in CCD for multiple times so that the dynamic range of the image is expanded.
However, since the image capturing apparatus disclosed in the Japanese patent application publication No. 11-32242 requires optics, such as a plurality of CCDs and a beam splitter, large-size and high-cost of the apparatus cannot be avoided. Moreover, in the image capturing apparatus disclosed in the Japanese patent application publication No. 5-260391, although the amount of charge transfer from the CCD can be increased, the dynamic range cannot be expanded unless increase of the amount of charge storages is accomplished.

Image capturing apparatus, image capturing method, and computer-readable medium storing a program for an image capturing apparatus


The object of the invention is a heater of a corrosive fluid comprising at least one heat diffuser having at least a first portion intended to be immersed in a corrosive fluid, and at least a second portion intended to be arranged out of the corrosive fluid, at least one heating block comprising at least one heating member configured to heat the corrosive fluid, said heat diffuser comprising at least one housing in which the at least one heating block is housed at least partially, at least the first portion of the heat diffuser being made of anodized aluminum or of anodized aluminum alloy and is configured to be in direct contact with the corrosive fluid.

Generally, the aqueous urea solution is stored in a dedicated tank in the vehicle, which is connected to the selective catalytic reduction system of said vehicle.
In the present invention, the terms "selective catalytic reduction system" mean a system comprising a tank of an aqueous urea solution, a catalyst, an injector of the aqueous urea solution in the exhaust line and at least one pipe connecting the tank to the injector, the catalyst being positioned at the exhaust line downstream of the inlet of the injector so that the catalysis occurs on a mixture of exhaust gas circulating in the exhaust line and of aqueous urea solution injected upstream of the catalyst in said exhaust line.
In a known manner, the aqueous urea solution contained in a storage device of a vehicle tends to freeze around −11° C. Therefore, the aqueous urea solution storage device is generally equipped with a system for heating said solution in order to prevent the latter from freezing.
There are several types of aqueous urea solution heaters. For example, preferentially for heavy goods vehicles, the calories of the engine cooling system are used by means of a stainless steel plunger used as a heat exchanger immersed in the tank. This solution is not yet adopted for light motor vehicles to the extent that the aqueous urea solution tank is located opposite the engine cooling system, which requires piping of considerable length traversing the entire vehicle and consequently cumbersome piping. In addition, making stainless-steel plungers is expensive and complicated.
In addition, there are also heating devices comprising one or more heating member(s), such as resistive tracks or thermistors with a positive temperature coefficient called PTC in the following application, equipped or not with an aluminum heat diffuser for example, the whole being overmolded by a compatible material for an immersion in the aqueous urea solution, such as silicone, polyoxymethylene (POM) or high-density polyethylene (HDPE). These overmolded devices have several drawbacks. Plastic, generally thermoplastic, materials used for the overmolding have generally relatively low melt temperatures, which causes a limitation of the power density of the devices to prevent the overmolding from melting, which leads to an increase in the exchange surfaces and therefore to a high bulk. In addition, the plastic materials used are generally poor heat conductors, which reduces the efficiency of the heaters. Finally, these plastic materials having a coefficient of expansion different from the resistive tracks or diffusers, there is a significant risk of occurrence of cracks, breaks or detachment of the overmolding, thereby making the heater inefficient or even ineffective.

Corrosive fluid heater, tank and manufacturing method

Abstract: The object of the invention is also a corrosive fluid tank comprising a heater according to the invention and a method for manufacturing a heat diffuser of the heater according to the invention.