The present invention describes a system and method for communicating voice and data over a packet-switched network that is adapted to coexist and communicate with a legacy PSTN. The system permits packet switching of voice calls and data calls through a data network from and to any of a LEC, a customer facility or a direct IP connection on the data network. The system includes soft switch sites, gateway sites, a data network, a provisioning component, a network event component and a network management component. The system interfaces with customer facilities (e.g., a PBX), carrier facilities (e.g., a LEC) and legacy signaling networks (e.g., SS7) to handle calls between any combination of on-network and off-network callers.

1. Field of the Invention
The present invention relates generally to telecommunications networks and, more particularly, to a system and method for providing transmission of voice and data traffic over a data network, including the signaling, routing and manipulation of such traffic.
2. Related Art
The present invention relates to telecommunications, and in particular to voice and data communication operating over a data network. The Public Switched Telephone Network (PSTN) is a collection of different telephone networks owned by different companies which have for many years provided telephone communication between users of the network. Different parts of the PSTN network use different transmission media and compression techniques.
Most long distance calls are digitally coded and transmitted along a transmission line such as a T1 line or fiber optic cable, using circuit switching technology to transmit the calls. Such calls are time division multiplexed (TDM) into separate channels, which allow many calls to pass over the lines without interacting. The channels are directed independently through multiple circuit switches from an originating switch to a destination switch. Using conventional circuit switched communications, a channel on each of the T1 lines along which a call is transmitted is dedicated for the duration of the call, whether or not any information is actually being transmitted over the channel. The set of channels being used by the call is referred to as a xe2x80x9ccircuit.xe2x80x9d
Telecommunications networks were originally designed to connect one device, such as a telephone, to another device, such as a telephone, using switching services. As previously mentioned, circuit-switched networks provide a dedicated, fixed amount of capacity (a xe2x80x9ccircuitxe2x80x9d) between the two devices for the entire duration of a transmission session. Originally, this was accomplished manually. A human operator would physically patch a wire between two sockets to form a direct connection from the calling party to the called party. More recently, a circuit is set up between an originating switch and a destination switch using a process known as signaling.
Signaling sets up, monitors, and releases connections in a circuit-switched system. Various signaling methods have been devised. Telephone systems formerly used in-band signaling to set up and tear down calls. Signals of an in-band signaling system are passed through the same channels as the information being transmitted. Early electromechanical switches used analog or multi-frequency (MF) in-band signaling. Thereafter, conventional residential telephones used in-band dual-tone multiple frequency (DTMF) signaling to connect to an end office switch. Here, the same wires (and frequencies on the wires) were used to dial a number (using pulses or tones), as are used to transmit voice information. However, in-band signaling permitted unscrupulous callers to use a device such as a whistle to mimic signaling sounds to commit fraud (e.g., to prematurely discontinue billing by an interexchange carrier (IXC), also known as a long distance telephone company).
More recently, to prevent such fraud, out-of-band signaling systems were introduced. Out-of-band signaling uses a signaling network that is separate from the circuit switched network used for carrying the actual call information. For example, integrated services digital network (ISDN) uses a separate channel, a data (D) channel, to pass signaling information out-of-band. Common Channel Interoffice Signaling (CCIS) is another network architecture for out-of-band signaling. A popular version of CCIS signaling is Signaling System 7 (SS7). SS7 is an internationally recognized system optimized for use in digital telecommunications networks.
SS7 out-of-band signaling provided additional benefits beyond fraud prevention. For example, out-of-band signaling eased quick adoption of advanced features (e.g., caller id) by permitting modifications to the separate signaling network. In addition, the SS7 network enabled long distance xe2x80x9cEqual Accessxe2x80x9d (i.e., 1+ dialing for access to any long distance carrier) as required under the terms of the modified final judgment (MFJ) requiring divestiture of the Regional Bell Operating Companies (RBOCs) from their parent company, ATandT.
An SS7 network is a packet-switched signaling network formed from a variety of components, including Service Switching Points (SSPs), Signaling Transfer Points (STPs) and Service Control Points (SCPs). An SSP is a telephone switch which is directly connected to an SS7 network. All calls must originate in or be routed through an SSP. Calls are passed through connections between SSPs. An SCP is a special application computer which maintains information in a database required by users of the network. SCP databases may include, for example, a credit card database for verifying charge information or an xe2x80x9c800xe2x80x9d database for processing number translations for toll-free calls. STPs pass or route signals between SSPs, other STPs, and SCPs. An STP is a special application packet switch which operates to pass signaling information.
The components in the SS7 network are connected together by links. Links between SSPs and STPs can be, for example, A, B, C, D, E or F links. Typically, redundant links are also used for connecting an SSP to its adjacent STPs. Customer premises equipment (CPE), such as a telephone, are connected to an SSP or an end office (EO) switch.
To initiate a call in an SS7 telecommunications network, a calling party using a telephone connected to an originating EO switch, dials a telephone number of a called party. The telephone number is passed from the telephone to the SSP at the originating EO (referred to as the xe2x80x9cingress EOxe2x80x9d) of the calling party""s local exchange carrier (LEC). A LEC is commonly referred to as a local telephone company. First, the SSP will process triggers and internal route rules based on satisfaction of certain criteria. Second, the SSP will initiate further signaling messages to another EO or access tandem (AT), if necessary. The signaling information can be passed from the SSP to STPs, which route the signals between the ingress EO and the terminating end office, or egress EO. The egress EO has a port designated by the telephone number of the called party. The call is set up as a direct connection between the EOs through tandem switches if no direct trunking exists or if direct trunking is full. If the call is a long distance call, i.e., between a calling party and a called party located in different local access transport areas (LATAs), then the call is connected through an inter exchange carrier (IXC) switch of any of a number of long distance telephone companies. Such a long distance call is commonly referred to as an inter-LATA call. LECs and IXCs are collectively referred to as the previously mentioned public switched telephone network (PSTN).
Emergence of competitive LECs (CLECs) was facilitated by passage of the Telecommunications Act of 1996, which authorized competition in the local phone service market. Traditional LECs or RBOCs are now also known as incumbent LECs (ILECs). Thus, CLECs compete with ILECs in providing local exchange services. This competition, however, has still not provided the bandwidth necessary to handle the large volume of voice and data communications. This is due to the limitations of circuit switching technology which limits the bandwidth of the equipment being used by the LECs, and to the high costs of adding additional equipment.
Since circuit switching dedicates a channel to a call for the duration of the call, a large amount of switching bandwidth is required to handle the high volume of voice calls. This problem is exacerbated by the fact that the LECs must also handle data communications over the same equipment that handle voice communications.
If the PSTN were converted to a packet-switched network, many of the congestion and limited bandwidth problems would be solved. However, the LECs and IXCs have invested large amounts of capital in building, upgrading and maintaining their circuit switched networks (known as xe2x80x9clegacyxe2x80x9d networks) and are unable or unwilling to jettison their legacy networks in favor of the newer, more powerful technology of packet switching. Accordingly, a party wanting to build a packet-switched network to provide voice and data communications for customers must build a network that, not only provides the desired functionality, but also is fully compatible with the SS7 and other, e.g., ISDN and MF, switching networks of the legacy systems.
Currently, internets, intranets, and similar public or private data networks that interconnect computers generally use packet switching technology. Packet switching provides for more efficient use of a communication channel as compared to circuit switching. With packet switching, many different calls (e.g., voice, data, video, fax, Internet, etc.) can share a communication channel rather than the channel being dedicated to a single call. For example, during a voice call, digitized voice information might be transferred between the callers only 50% of the time, with the other 50% being silence. For a data call, information might be transferred between two computers 10% of the time. With a circuit switched connection, the voice call would tie-up a communications channel that may have 50% of its bandwidth being unused. Similarly, with the data call, 90% of the channel""s bandwidth may go unused. In contrast, a packet-switched connection would permit the voice call, the data call and possibly other call information to all be sent over the same channel.
Packet switching breaks a media stream into pieces known as, for example, packets, cells or frames. Each packet is then encoded with address information for delivery to the proper destination and is sent through the network. The packets are received at the destination and the media stream is reassembled into its original form for delivery to the recipient. This process is made possible using an important family of communications protocols, commonly called the Internet Protocol (IP).
In a packet-switched network, there is no single, unbroken physical connection between sender and receiver. The packets from many different calls share network bandwidth with other transmissions. The packets are sent over many different routes at the same time toward the destination, and then are reassembled at the receiving end. The result is much more efficient use of a telecommunications network than could be achieved with circuit-switching.
Recognizing the inherent efficiency of packet-switched data networks such as the Internet, attention has focused on the transmission of voice information over packet-switched networks. However, such systems are not compatible with the legacy PSTN and therefore are not convenient to use.
One approach that implements voice communications over an IP network requires that a person dial a special access number to access an IP network. Once the IP network is accessed, the destination or called number can be dialed. This type of call is known as a gateway-type access call.
Another approach involves a user having a telephone that is dedicated to an IP network. This approach is inflexible since calls can only be made over the UP network without direct access to the PSTN.
What is needed is a system and method for implementing packet-switched communications for both voice calls and data calls that do not require special access numbers or dedicated phones and permit full integration with the legacy PSTN.
The present invention is a system and method for communicating both voice and data over a packet-switched network that is adapted to coexist and communicate with a PSTN. The system permits efficient packet switching of voice calls and data calls from a PSTN carrier such as, for example, a LEC, IXC, a customer facility or a direct IP connection on the data network to any other LEC, IXC, customer facility or direct IP connection. For calls from a PSTN carrier, e.g., LEC or IXC, the invention receives signaling from the legacy SS7 signaling network or the ISDN D-channel or from inband signaling trunks. For calls from a customer facility, data channel signaling or inband signaling is received. For calls from a direct IP connection on the data network, signaling messages can travel over the data network. On the call destination side, similar signaling schemes are used depending on whether the called party is on a PSTN carrier, a customer facility or a direct IP connection to the data network.
The system includes soft switch sites, gateway sites, a data network, a provisioning component a network event component and a network management component. The system of the invention interfaces with customer facilities (e.g., a PBX), carrier facilities (e.g., a PSTN carrier, a LEC (e.g., ILECs and CLECs), an independent telephone company (ITC), an IXC, an intelligent peripheral or an enhanced service provider (ESP)) and legacy signaling networks (e.g., SS7) to handle calls between any combination of on-network and off-network callers.
The soft switch sites provide the core call processing for the voice network architecture. Each soft switch site can process multiple types of calls including calls originating from or terminating at off-network customer facilities as well as calls originating from or terminating at on-network customer facilities. Each soft switch site receives signaling messages from and sends signaling messages to the signaling network. The signaling messages can include, for example, SS7, integrated services digital network (ISDN) primary rate interface (PRI) and in-band signaling messages. Each soft switch site processes these signaling messages for the purpose of establishing new calls through the data network and tearing down existing calls and in-progress call control functions. Signaling messages can be transmitted between any combination of on-network and off-network callers.
Signaling messages for a call which either originates off-network or terminates off-network can be carried over the out-of-band signaling network of the PSTN via the soft switch sites. Signaling messages for a call which both originates on-network and terminates on-network can be carried over the data network rather than through the signaling network.
The gateway sites originate and terminate calls between calling parties and called parties through the data network. The soft switch sites control or manage the gateway sites. In a preferred embodiment, the soft switch sites use a protocol such as, for example, the Internet Protocol Device Control (IPDC) protocol, to manage network access devices in the gateway sites to request the set-up and tear-down of calls. However, other protocols could be used, including, for example, network access server messaging interface (NMI) and the ITU media gateway control protocol (MGCP).
The gateway sites can also include network access devices to provide access to network resources (i.e., the communication channels or circuits that provide the bandwidth of the data network). The network access devices can be referred to generally as access servers or media gateways. Exemplary access servers or media gateways are trunking gateways (TGs), access gateways (AGs) and network access servers (NASs). The gateway sites provide for transmission of both voice and data traffic through the data network. The gateway sites also provide connectivity to other telecommunications carriers via trunk interfaces to carrier facilities for the handling of voice calls. The trunk interfaces can also be used for the termination of dial-up modem data calls. The gateway sites can also provide connectivity via private lines and dedicated access lines (DALs), such as T1 or ISDN PRI facilities, to customer facilities.
The data network connects one or more of the soft switch sites to one or more of the gateway sites. The data network routes data packets through routing devices (e.g., routers) to destination sites (e.g., gateway sites and soft switch sites) on the data network. For example, the data network routes internet protocol (IP) packets for transmission of voice and data traffic from a first gateway site to a second gateway site. The data network represents any art-recognized data network including the global Internet, a private intranet or internet, a frame relay network, and an asynchronous transfer mode (ATM) network.
The network event component collects call events recorded at the soft switch sites. Call event records can be used, for example, for fraud detection and prevention, and billing.
The provisioning event component receives provisioning requests from upstream operational support services (OSS) systems such as, for example, for order-entry, customer service and customer profile changes. The provisioning component distributes provisioning data to appropriate network elements and maintains data synchronization, consistency, and integrity across multiple soft switch sites.
The network management component includes a network operations center (NOC) for centralized network management. Each network element(NE) (e.g., soft switch sites, gateway sites, provisioning, and network event components, etc.) generates simple network management protocol (SNMP) events or alerts. The NOC uses the events generated by each network element to determine the health of the network and to perform other network management functions.
In a preferred embodiment, the invention operates as follows to process, for example, a long distance call (also known as a 1+ call). First, a soft switch site receives an incoming call signaling message from the signaling network. The soft switch site determines the type of call by performing initial digit analysis on the dialed number. Based upon the information in the signaling message, the soft switch site analyzes the initial digit of the dialed number of the call and determines that it is a 1+ call. The soft switch site then queries a customer profile database to retrieve the originating trigger plan associated with the calling customer. The query can be made using, for example, the calling party number provided in the signaling message from the signaling network. This look-up in the customer profile database returns subscription information. For example, the customer profile may indicate that the calling party has subscribed to an account code verification feature that requires entry of an account code before completion of the call. In this case, the soft switch site will instruct the gateway site to collect the account code digits entered by the calling party. Assuming that the gateway site collects the correct number of digits, the soft switch site can use the customer profile to determine how to process the received digits. For account code verification, the soft switch site verifies the validity of the received digits.
Verification can result in the need to enforce a restriction, such as a class of service (COS) restriction (COSR). In this example, the soft switch site can verify that the account code is valid, but that it requires that an intrastate COSR should be enforced. This means that the call is required to be an intrastate call to be valid. The class of service restriction logic can be performed within the soft switch site using, for example, pre-loaded local access and transport areas (LATAs) and state tables. The soft switch would then allow the call to proceed if the class of service requested matches the authorized class of service. For example, if the LATA and state tables show that the LATA of the originating party and the LATA of the terminating party are in the same state, then the call can be allowed to proceed. The soft switch site then completes customer service processing and prepares to terminate the call. At this point, the soft switch site has finished executing all customer service logic and has a 10-digit dialed number that must be terminated. To accomplish the termination, the soft switch site determines the terminating gateway. The dialed number (i.e., the number of the called party dialed by the calling party) is used to select a termination on the data network. This termination may be selected based on various performance, availability or cost criteria. The soft switch site then communicates with a second soft switch site associated with the called party to request that the second soft switch site allocate a terminating circuit or trunk group in a gateway site associated with the called party. One of the two soft switch sites can then indicate to the other the connections that the second soft switch site must make to connect the call. The two soft switch sites then instruct the two gateway sites to make the appropriate connections to set up the call. The soft switch sites send messages to the gateway sites through the data network using, for example, IPDC protocol commands. Alternately, a single soft switch can set up both the origination and termination.
The present invention provides a number of important features and advantages. First, the invention uses application logic to identify and direct incoming data calls straight to a terminating device. This permits data calls to completely bypass the egress end office switch of a LEC. This results in significant cost savings for an entity such as an internet service provider (ISP), ILEC, or CLEC. This decrease in cost results partially from bypass of the egress ILEC end office switch for data traffic.
A further advantage for ISPs is that they are provided data in the digital form used by data networks (e.g., IP data packets), rather than the digital signals conventionally used by switched voice networks (e.g., PPP signals). Consequently, the ISPs need not perform costly modem conversion processes that would otherwise be necessary. The elimination of many telecommunications processes frees up the functions that ISPs, themselves, would have to perform to provide Internet access.
Another advantage of the present invention is that voice traffic can be transmitted transparently over a packet-switched data network to a destination on the PSTN.
Yet another advantage of the invention is that a very large number of modem calls can be passed over a single channel of the data network, including calls carrying media such as voice, bursty data, fax, audio, video, or any other data formats.

Voice over data telecommunications network architecture

Abstract: The soft switch sites provide the core call processing for the voice network architecture. The soft switch sites manage the gateway sites in a preferred embodiment, using a protocol such as the Internet Protocol Device Control (IPDC) protocol to request the set-up and tear-down of calls. The gateway sites originate and terminate calls between calling parties and called parties through the data network. The gateway sites include network access devices to provide access to network resources. The data network connects one or more of the soft switch sites to one or more of the gateway sites. The provisioning and network event component collects call events recorded at the soft switch sites. The network management component includes a network operations center (NOC) for centralized network management.


A computer system and method for transmitting LAN signals over transport systems. LAN signals are generated in any client LAN compliant interface. A transceiver receives the client LAN signal in the LAN format. The client LAN signals are not converted to a SONET transmission format at any time before reaching the transceiver. The transceiver then converts the client LAN signal to an internal electrical LAN signal before re-clocking the internal electrical LAN signal. The re-clocked internal electrical LAN signal is then re-modulated into a second LAN signal. The second LAN signal is then transmitted to a transport system.

Data networks that cover large geographical distances have historically been fundamentally different from those that cover short distances. This fact primarily was derived from the different evolutionary paths that were followed by the Enterprise networks (ones that reside inside of a business, home, educational institution, or government agency) and the Carrier networks (ones that are provided by a common carrier). Over the past few decades the Enterprise networks and Carrier networks mostly evolved independently, each addressing a different problem and each following a different set of standards. The Enterprise networks mostly evolved to support data from computing environments via LAN infrastructures and data protocols. After decades of competition between different LAN standards and networking protocols during the 1980s and 1990s, the LANs are now predominantly built on Ethernet and Internet Protocol (IP) technologies. Ethernet is defined by the Institute for Electrical and Electronics Engineers (IEEE) and specifically is defined by the IEEE 802.3 standard. The Internet Engineering Task Force (IETF) defines IP.
The Carrier networks mostly evolved to support voice services from home and business customers via various circuit-switched Time Domain Multiplexing (TDM) technologies. The Carrier networks are now predominantly comprised of various TDM technologies built on the Synchronous Optical Network (SONET) standard or its European counterpart Synchronous Digital Hierarchy (SDH). The American National Standard Institute (ANSI) defines SONET and the International Telecommunications Union (ITU) defines the SDH standard.
Historically, the Ethernet LAN technologies provided very cost-effective high-speed "local" connections among computers, but sacrificed the ability to span distances longer than approximately 10 km. Typical Ethernet LANs spanned relatively small areas like a building or a campus. Such a transport system may be called an inter-office transport system. More recently, Ethernet has been used directly over optical fiber in Metropolitan Area Networks (MANs) to deliver Ethernet services natively to areas on the order of 100 km in diameter. The method on how to utilize Ethernet natively on optical fiber for distances shorter than approximately 100 km is specified by the IEEE 802.3 standard.
As the need arose for the Enterprise LAN networks to interconnect their geographically separate facilities, the only available services at the Enterprise's disposal were from the public Carriers' networks. However, the asynchronous, connectionless, packet-oriented nature of the LAN technology was mostly incompatible with the synchronous, connection-based, bit-oriented nature of the Carriers' TDM facilities. To join the two technological worlds together, various data technologies were invented. In the realm where speeds are comparable to that of LANs (i.e. 10 Megabits/second or greater) Asynchronous Transfer Mode (ATM), Frame Relay (FR), and Packet over SONET (POS) became the most popular data technologies that Carriers utilized. ATM, FR, and POS are generally considered Wide Area Networking (WAN) technologies and are built on top of the SONET-based TDM infrastructure currently deployed by the carriers. In general, ATM, FR, and POS sacrificed the simplicity, efficiency, and cost-effectiveness of LAN technologies in order to be compatible with the existing carrier TDM infrastructure, which was primarily designed for voice traffic. At the time ATM, FR, and POS were being developed in the late 1980s, it made sense to make these sacrifices because the volume of data traffic over the TDM infrastructure was insignificant when compared to the volume of voice traffic. However, since the later part of the 1990's, data traffic has grown exponentially so that now it comprises the majority of the traffic on the Carrier's TDM infrastructure.
Since Carriers adopted ATM, FR, and POS as the WAN technologies, Enterprise networks were forced to utilize these inefficient and expensive technologies to interconnect their LANs between their various locations. Typically the interconnections were accomplished via routers with ATM, FR, and POS interfaces and ATM switches, see FIG. 1. The introductions of these WAN technologies to the Enterprise's LAN infrastructures lead to significant new technological learning curves and significant capital and operational expenses. Many Enterprises created entirely separate departments to deal with the Carriers and their WAN technologies.
As the Ethernet LAN technologies evolved, data rates grew from 10 Mbits/sec to 100 Mbits/sec, 1 Gbit/sec, and now 10 Gbit/sec Ethernet (10GE). Each successive generation of Ethernet remained compatible with the previous, thus allowing for interoperability as the network grew. Enterprises quickly adopted each new generation of Ethernet technology to support the exploding traffic volumes on their LANs. With the introduction of 10GE standard, Enterprise networks will once again scale to the next level. The high throughput rate of 10GE makes the technology extremely attractive for use on corporate backbone networks. Because the original packet format and minimum/maximum packet size were retained between the various versions of Ethernet, all forms of Ethernet interoperate seamlessly. Consequently it is possible, for example, to collect traffic from one hundred 100 Base-T Ethernets, each running at full speed, and pass this traffic along a single 10GE network.
However, the Carrier WAN technologies have lagged behind the LAN Ethernet implementations in terms of capacity, price/performance, and ease of use. Enterprises have voiced their desire to implement Ethernet connections across WANs as a mechanism to supplant the traditional WAN technologies (ATM, FR, and POS) offered by Carriers. There are several potential mechanisms available to transport the various Ethernet technologies across WAN infrastructures. In general, these mechanisms can be broken into two categories: encapsulation and native. In the case of encapsulation, an Ethernet frame is removed from its native media format and encapsulated inside of the payload area of another protocol. There are numerous examples of the encapsulation approach including: Ethernet over FR, Ethernet over POS, Ethernet over SONET (x86, 10GE WAN, and others), and Ethernet over ATM (LANE). All of these encapsulation techniques were invented in order to allow Ethernet to be run over existing Carrier WAN technologies that, in turn, were transported on top of traditional Carrier TDM technologies, thus creating additional unnecessary layers of cost and complexity. The native Ethernet formats are defined by the IEEE 802.3 committee standards for each of the Ethernet variations. The physical layer (PHY) of the IEEE Ethernet standards defines how Ethernet is transmitted over a given media. For each of the Ethernet speeds (10 Mb, 100 Mb, 1 Gb, and 10 Gb) the IEEE defines at least one native PHY format that transports Ethernet directly on optical fiber facilities and at least one PHY format that transports Ethernet directly on copper facilities (coax or twisted pair media). In addition to various copper-based PHYs, each of the Ethernet speeds support multiple PHYs for optical fiber in order to support different reaches, different price points, and different optical fiber types. However, the IEEE-defined PHYs do not support:
1. Reaches beyond about 100 km
2. Optical media other than optical fiber
3. Media other than optical fiber or copper
4. Multiplexing multiple Ethernet signals over a given optical media.
The 100 km limit on optical fiber is the approximate point at which an optical signal will degrade beyond the point of recovery without some form of signal regeneration. The IEEE 802.3 committee's charter ended at this point as they saw that distances beyond 100 km were in the realm of WAN technologies and they were a committee chartered to focus on LAN issues.
When developing the 10GE standard, the IEEE 802.3ae committee developed two different 10GE frame formats. These frame formats are generally known as the "LAN" standard and the "WAN" standard, though these are somewhat misnamed terms. The 10GE "LAN" standard utilizes a native frame format identical to all previous IEEE 802.3 Ethernet standards. But, in order to allow compatibility with the existing SONET framing structure and data rate, the IEEE 802.3ae committee defined the 10GE "WAN" standard. The IEEE 802.3ae WAN standard encapsulates native Ethernet frames inside of an OC-192 SONET Payload Envelope (SPE) and adjusts the clock rate of the 10GE signal such that it is compatible with that of OC-192. Both the 10GE WAN and 10GE LAN standards support the same set of optical fiber PHYs and thus both have the same distance limitations on a single span of optical fiber without resorting to additional equipment. The "LAN" and "WAN" designations simply refer to their differences in framing format and data rates.
To transport native Ethernet signals further than the nominal 100 km limit on optical fiber, and/or to support multiple optical Ethernet signals natively on a given optical fiber, other technologies must be introduced to multiplex, amplify, and condition the optical signal. The technologies that allow optical signals to cost-effectively travel beyond 100 km and/or be multiplexed on optical fiber are well known and have been applied to the SONET industry for well over a decade. These technologies include: optical amplification (via Erbium Doped Fiber Amplifiers (EDFA) or Raman amplifiers), dispersion compensation, optical multiplexing via Coarse Wave Division Multiplexing (CWDM, less than 17 channels) or Dense Wave Division Multiplexing (DWDM, greater than or equal to 17 channels), gain equalization, Forward Error Correction (FEC), and various modulation techniques. Combined, these technologies are generally referred to as Metro (less than 100 km in length), Long Haul (LH, between 100 and 1000 km), and Ultra Long Haul (ULH, greater than 1000 km) transport systems. Recent ULH systems allow more than 100 ten-gigabit signals to be transmitted 1000's of kilometers over an optical fiber without the need to be converted to an electronic signal.
Transport systems are that class of systems that allow a signal (or signals) to be transmitted and received via a media while including functionality beyond that of the original signal. An optical transport system may include optical fiber or free space optics. A fiber transport system can include fiber optics, copper wire, or any thread like substance, such as carbon fiber, capably of carrying a signal. Transport systems include support for functionality such as (but not limited to):
1. Media: optical fiber, Free Space Optics (FSO), Radio Frequency (RF), and electrical-based solutions (twisted copper pairs, coaxial cable)
2. Topological organizations: linear, rings, stars, and meshes
3. Switching capabilities: protection, restoration, and cross-connections
4. Multiplexing capabilities: single channel, CWDM, and DWDM
5. Directional capabilities: unidirectional or bi-directional
6. Distance capabilities: Metro, LH, ULH, submarine, and satellite systems
7. Transport system network elements: Optical Add/Drop Multiplexers (OADM), Optical Wavelength Cross-connects (OXC), and Regenerators (Regen)
8. Management and Control systems: signaling protocols, performance monitoring, and configuration and control interfaces
These functionalities may be used independently or in various combinations to create a wide variety of transport system implementations to solve specific transport system problems.
In the prior art, to adapt a standard IEEE 802.3 10GE client signal to a format that is suitable for a specific transport system, a device called a transceiver is employed. A transceiver converts the 10GE signal from a client system (the tributary signal) to a signal that is defined by the particular transport system (the line signal). Prior art transceivers such as those offered by Nortel, Lucent, Hitachi and others are available to convert 850, 1310 and 1550 nm optical tributary signals compatible with the 10GE WAN standard to the signals suitable for their respective Metro/LH/ULH systems. However, a need exists in the industry for a transceiver that is capable of receiving tributary signals of the 10GE LAN standard. In other words, a need exists for a high-speed transport system that is compatible with the 10GE LAN standard and does not require conversion to the IEEE 10GE WAN standard, or any other SONET-based standard, for use in creating networks.
Prior art systems suffer from the ability of using the 10GE LAN standard for a high-speed transport system. For example, United States Patent No. 2001/0014104, to Bottorff, et al., entitled "10 Gigabit Ethernet Mappings For A Common Lan/Wan Pmd Interface With A Simple Universal Physical Medium Dependent Interface", discloses an Ethernet mapping that enables high speed Ethernet data streams having a data rate of 10 Gb/s to be transported across a synchronous packet switched network having a standard SONET OC-192 line rate. The Bottorff invention, as with many of the other prior art inventions, requires conversion to a SONET-based standard.
U.S. Pat. No. 6,075,634 to Casper, et al., entitled "Gigabit Data Rate Extended Range Fiber Optic Communication System And Transponder Therefor", discloses a method and system for a fiber optic digital communication system and associated transponder architecture. The system interfaces Gigabit Ethernet digital data over an extended range fiber optic link, using digital data signal regeneration and optical signal processing components that pre- and post-compensate for distortion and timing jitter. Casper does not disclose a transceiver that is capable of receiving tributary signals of the 10GE LAN standard.
U.S. Pat. No. 6,288,813 to Kirkpatrick, et al., entitled "Apparatus And Method For Effecting Data Transfer Between Data Systems", discloses a receiver that converts an optical signal to digital data signals. The digital data signals are then converted to balanced bipolar signals and are then outputted onto buses for input into data systems. Kirkpatrick does not disclose an architecture for transporting 10GE LAN signals.

Apparatus and method for transmitting LAN signals over a transport system


A current controlled, phase locked loop device includes a phase detector configured to compare a reference frequency to an output frequency of a current controlled oscillator (ICO), a charge pump coupled to the phase detector and a low pass filter coupled to the charge pump. A voltage to current (V to I) converter is coupled to the low pass filter, providing an output current for integral control of the ICO. A control circuit is coupled to the ICO, and receives increment and decrement outputs of the phase detector, wherein the control circuit is configured to provide proportional control of the ICO through an amount of bias current applied thereto.

The present invention relates generally to current controlled oscillation (ICO) devices, and, more particularly, to an improved ICO device and method having wide frequency range and integrated proportional frequency control capable of operation at low supply voltages.
Controlled oscillators are used in a variety of integrated circuits for applications such as, for example, signal generation and detection, as well as in phase locked loop (PLL) circuits. In a controlled oscillator, the frequency of an output signal is responsive to a control signal provided thereto. There are various types of controlled oscillators, with one of the more common types being a current controlled oscillator (ICO). A typical ICO includes a controlled current source coupled to a ring oscillator, which in turn features a chain of inverter stages (typically an odd number). The output of one inverter in the stage is coupled to the input of a succeeding inverter, and so on, with the output of the last inverter fed back to the input of the first inverter in the stage. Typical inverters are formed from CMOS transistors, although other types of devices may also be used.
The frequency of the output signal of an ICO is inversely proportional to the delay/switching time of the inverters that form the oscillator. In turn, the switching time of an inverter corresponds to the time needed to charge and discharge the input capacitance of a successive inverter to a level respectively above or below the switching threshold of the successive inverter. The charge and discharge period is determined by the magnitude of current that is used to charge the input capacitance. It is this charging current that is provided and controlled by the controlled current source.
One disadvantage associated with conventional current controlled oscillators is that the gain of the oscillator is not controllable at a given operating frequency. This is particularly the case for an oscillator that is used over a wide range of operating frequencies, as the gain of a conventional ICO (i.e., the relationship of output frequency versus bias current) is constrained by the desired frequency range. It would therefore be desirable to be able to configure a wide range oscillator for applications such as phase locked loops, for example, that also keeps the gain at a low level so that the overall loop bandwidth can be optimized.

This patent is subject to a terminal disclaimer.

Current controlled oscillation device and method having wide frequency range

International Business Machines Corporation


A disposable absorbent article is provided which includes a substantially liquid-impermeable outer cover, a liquid permeable bodyside liner, an absorbent body located between the outer cover and the bodyside liner, and a pair of fasteners located on the laterally opposed side edges in one of the waist sections of the absorbent article. The outer cover can be configured to provide a substantially permanent deformation of at least about 10 percent when subjected to a tensile force of 100 gmf per inch (per 2.54 cm) of width according to the Material Elongation and Deformation Tensile Test set forth herein. The outer cover can further define a water vapor transmission rate of at least about 800 g/m2/24 hr. The permanent deformation of the outer cover in use can result in a longitudinal breathability gradient ratio between the outer cover in the waist section and the crotch or intermediate section of the article of at least about 1.25 according to the Product Deformation Test set forth herein.

The present invention relates to absorbent articles, desirably disposable absorbent articles, which have a distinctive extensible outer cover that provides zoned breathability in use.
It is desired that absorbent articles such as diapers, training pants or incontinence garments provide a close, comfortable fit about the wearer and contain body exudates while maintaining skin health. In certain circumstances, it is also desirable that such absorbent articles are capable of being pulled up or down over the hips of the wearer to allow the wearer or caregiver to easily pull the article on and easily remove the article if it has not been soiled. For example, such absorbent articles can assist in the toilet training of children.
Many conventional absorbent articles have typically employed fasteners that attach the waist sections of the articles around a wearer as well as various configurations of waist elastics, leg elastics, elasticized liners, and elasticized outer covers. The fasteners and elastic components have been employed to help produce and maintain the fit of the articles about the body contours of the wearer that can lead to improved containment. Maintaining this fit as the wearer moves and changes body position has been particularly difficult. For example, articles such as diapers are typically applied while the wearer is in a prone position wherein their torso is extended and their abdomen is sunken. As the wearer changes from the prone position to a sitting position, the wearer""s torso compresses and their abdomen extends outwardly thereby exerting forces on the article. If the waistband of the article does not have enough xe2x80x9cgivexe2x80x9d, such forces can cause the waistband to shift that can undesirably result in increased leakage.
In an attempt to provide a maintained fit during movement, some conventional absorbent articles have included an outer cover composed of elastomeric materials, such as elastomeric, stretch-bonded-laminate materials. Such materials have included a layer of meltblown elastomeric fibers, which has been stretched and sandwiched between facing layers composed of polypropylene spunbond nonwoven materials. The meltblown layer has typically been pattern-bonded to the facing layers with thermal bonds, sonic bonds and/or adhesive bonds. Other conventional absorbent articles have included folded pleats in the outer cover. The pleats are arranged to expand open as the article absorbs liquids.
In absorbent articles that are capable of being pulled up or down over the hips of the wearer, the ability of the article to provide and maintain the desired fit is particularly important. For example, some conventional absorbent articles, such as conventional training pants, have included integral side panels that connect the front waist section to the back waist section of the absorbent article. The side panels have been made stretchable such that the waist opening of the absorbent article can expand to allow the absorbent article to be pulled up or down over the hips of the wearer if desired. Such side panels have also been designed such that they may be torn to remove the training pant from the wearer after it has been soiled but typically are not refastenable.
Moreover, in an attempt to reduce the humidity level within such absorbent articles to help maintain the health of the wearer""s skin, breathable polymer films have been employed as outer covers for such absorbent articles. The breathable films are typically constructed with micropores to provide desired levels of liquid impermeability and air permeability. Other absorbent article designs have been arranged to provide breathable regions in the form of breathable panels or perforated regions in otherwise vapor-impermeable outer covers to help ventilate the articles.
However, many of such attempts to provide absorbent articles that provide the desired fit while maintaining breathability have not been completely satisfactory. For example, some absorbent articles that include elastic outer cover materials have resulted in excessive skin irritation, as it has been difficult to control the tension in such products. Moreover, such elastic outer covers typically have not exhibited the desired resistance to leakage, as they have not readily expanded to provide void volume for the containment of fecal exudates. In addition, absorbent articles such as training pants have not always been able to achieve a close conforming fit to the wearer while still being able to expand enough to be pulled up and down over the hips of the wearer. Often such training pants fit the waist of the wearer loosely, which can undesirably result in leaks. As a result, many of such articles have not contained bodily exudates as effectively as conventional diaper-type articles which can be adjusted to achieve a more conforming fit to the wearer.
Further, articles which employ selectively located breathable panels can be difficult to manufacture. In addition, articles that employ microporous or perforated films that are highly breathable over their entire surface can exhibit excessive leakage of liquids or high levels of moisture or dampness on their outer surface in the region of the article receiving the greatest insults. As a result, the breathability of such microporous and perforated films has been maintained at relatively low levels to reduce the incidence of leakage and dampness on the outer cover. Thus, many of such absorbent articles have not been able to maintain a high level of breathability to sufficiently reduce the hydration of the wearer""s skin. As a result, the wearer""s skin has remained susceptible to rashes, abrasion and irritation.
Accordingly, despite the attempts to develop improved absorbent articles, there remains a need for absorbent articles that can provide improved fit, resistance to leakage and breathability without excessive irritation to the skin of the wearer. Moreover, in some circumstances, there remains a need that such absorbent articles provide the benefits of conventional training pants and conventional diapers. That is, there remains a need for absorbent articles that conform to the wearer to effectively contain bodily exudates, are breathable and are capable of being pulled up and down over the hips and buttocks of the wearer.
In response to the difficulties and problems discussed above, new absorbent article designs have been discovered which provide improved breathability, fit and containment. Generally stated, the present invention provides a disposable absorbent article that defines a front waist section, a rear waist section, an intermediate section which extends between and connects the waist sections, a pair of laterally opposed side edges, a pair of longitudinally opposed waist edges, a longitudinal direction and a lateral direction. The absorbent article includes a substantially liquid-impermeable outer cover, a liquid permeable bodyside liner and an absorbent body located between the outer cover and the bodyside liner. The absorbent article may also include a pair of fasteners located on the laterally opposed side edges in one of the waist sections. In certain aspects, the disposable absorbent article may be provided in a prefastened, pant-like configuration such that the article can be pulled on or off over the hips of the wearer similar to conventional training pants. For example, the fasteners may refastenably attach the laterally opposed side edges in the front waist section to the laterally opposed side edges in the rear waist section to provide the pant-like, prefastened absorbent article prior to packaging the articles.
In particular aspects, the outer cover may be extensible and configured to provide a substantially permanent deformation of at least about 10 percent, desirably at least about 15 percent, particularly at least about 17 percent, more desirably at least about 20 percent, even more desirably at least about 25 percent, and yet even more desirably at least about 30 percent when subjected to a tensile force of 100 gmf per inch of width according to the Material Elongation and Deformation Tensile Test set forth herein.

Absorbent article having an extensible outer cover with activatable zoned breathability


A process for selectively hydrogenating ethylenically unsaturated double bonds in polymers P involves reacting the polymers P with hydrogen in the presence of at least one hydrogenation catalyst selected from the salts and complex compounds of rhodium and/or of ruthenium in an aqueous dispersion of the polymers P that comprises not more than 20% by volume of an organic solvent. This process can be used to give hydrogenated polymer dispersions and, from these dispersions, polymers. Also claimed are aqueous polymer dispersions comprising polymers Pxe2x80x2, which include structural units I, II and III as in claim 10, with or without structural units IV and/or V as in claim 11.

The present invention relates to a process for selectively hydrogenating ethylenically unsaturated double bonds in addition polymers by reacting the polymers with hydrogen in the presence of at least one hydrogenation catalyst selected from salts and complex compounds of rhodium a nd/or of ruthenium.
The hydrogenation of ethylenically unsaturated double bonds is an important method of derivatizing polymers containing such bonds. A range of polymers of this kind are produced on the industrial scale, examples being butadiene- and/or isoprene-based polymers. The ethylenically unsaturated double bonds in these polymers are starting points for the aging processes as may occur under the action of light, oxygen and/or heat. Depending on the degree of exposure, such aging processes often entail a dramatic deterioration in the mechanical properties of the polymers and/or the articles produced from the polymers, and are also the cause of instances of very obvious and disruptive discoloration. By hydrogenating the double bonds it is intended to remove such weak points. Furthermore, hydrogenation makes it possible in principle to provide classes of polymer which are new or which can otherwise be prepared only by a very much more complex method.
In developing hydrogenation processes for polymers a fundamental consideration is that the polymer hydrogenation substrates may include not only the ethylenically unsaturated double bonds but also other hydrogenation-reactive functionalities. A feature of the hydrogenation process must therefore be, in general, a high level of selectivity toward the target double bonds. Further, an intrinsic risk of hydrogenation is that there may be generated on the polymer reactive intermediates which have the capacity to react with remaining double bonds and so cause crosslinking.
Techniques for hydrogenating polymers that contain ethylenically unsaturated double bonds are fundamentally known. An overview of such techniques is given by N. T. McManus et al. (J. Macromol. Sci., Rev. Macromol. Chem. Phys. (C 35(2), 1995, 239-285). A common feature of all of the techniques described is that the reaction is conducted in an organic medium. This includes the homogeneous reaction of the dissolved polymer in the presence of a homogeneously dissolved catalyst in an organic solvent, and heterogeneous reactions of polymers in suspension in an organic solvent in the presence of homogeneously dissolved catalysts, and also the hydrogenation of polymer solutions and/or polymer melts in the presence of heterogeneous catalysts. However, gelling is generally observed in the course of the hydrogenation, which points to crosslinking reactions.
EP-A 588 097 discloses the hydrogenation of polymers based on butadiene/acrylonitrile. In these processes the polymers are reacted in the form of aqueous dispersions in at least five times the amount, based on the dispersion, of an organic solvent and in the presence of ruthenium catalysts. Special additives are added to suppress the formation of crosslinked polymers. A disadvantage of this process is the large quantities of solvent that are employed.
Fundamentally there is great interest in the transfer of the catalytic hydrogenation of polymers containing ethylenically unsaturated double bonds to aqueous reaction systems. For instance, some industrially important butadiene polymers are available commercially as aqueous polymer dispersions. Furthermore, the use of solvents in the course of production is a not insignificant cost factor. Solvent avoidance also appears desirable on the grounds of workplace safety and environmental protection.
It is an object of the present invention to provide a process for selectively hydrogenating ethylenically unsaturated double bonds in polymers which firstly operates without the use of large amounts of solvent and secondly ensures high selectivity of the hydrogenation reaction of the ethylenic double bond over the hydrogenation of other functionalities and over crosslinking reactions.
We have found that this object can be achieved, surprisingly, by a process in which the polymers are hydrogenated in the presence of rhodium and/or ruthenium compounds or their salts, as hydrogenation catalysts, in an aqueous dispersion of the polymers that contains little if any organic solvent.
The present invention therefore provides a process for selectively hydrogenating ethylenically unsaturated double bonds in polymers P by reacting the polymers with hydrogen in the presence of at least one hydrogenation catalyst selected from the salts and complex compounds of rhodium and/or of ruthenium, which comprises conducting the hydrogenation in an aqueous dispersion of the polymers that comprises not more than 20% by volume of an organic solvent.
The hydrogenation of polymers in aqueous dispersion has to date been considered an impossibility. For successful hydrogenation it has been assumed that the polymers must be present in the dissolved or melted state, or at least in a swollen state, so that the catalytically active species can get to the reactive sites, in other words the ethylenically unsaturated double bonds in the polymers. In organic reaction media, hydrophobic polymers will naturally be present in dissolved or at least swollen form, but this is not the case in water or aqueous reaction systems. For this reason the hydrogenation of hydrophobic polymers, as already mentioned, has to date always been conducted in an organic medium or in the melted state.
This opinion is confirmed, inter alia, by B. Cornils, Angew. Chem. 107, 1995, 1709-1711. This reference states that catalytic reactions in two-phase systems where the substrate is the hydrophobic phase and the catalyst is in the aqueous phase come up against their limits when the starting materials, in this case the polymers, are of inadequate solubility in water and, consequently, when the transfer of organic substrate into the aqueous phase or to the interface is hindered. The ruthenium- and/or rhodium-comprising catalyst systems employed in accordance with the invention, on the other hand, appear able under the reaction conditions to penetrate at least partly into the polymer phase/water interface or to cross said interface.
In the process of the invention the hydrogenation catalysts or catalyst precursors that can be employed are all salts and/or complex compounds of ruthenium or of rhodium which are able under the respective reaction conditionsxe2x80x94that is, hydrogen partial pressure, reaction temperature, reaction mixture pH, and any coligands present (or inorganic or organic compounds that act as coligands)xe2x80x94to form active hydrogenation species of low molecular mass. Examples of rhodium and ruthenium salts suited to this purpose are their hydrides, oxides, sulfides, nitrates, sulfates, halides, such as their chlorides, carboxylates, such as their acetates, propionates, hexanoates and benzoates, their salts with sulfonic acids, and mixed salts, ie. salts with different anions, such as the oxide chlorides. Also suitable are salts of complex ions of rhodium and/or ruthenium, examples being the salts of rhodium or ruthenium oxoacids, the salt of haloruthenates and halorhodates, especially the chlororuthenates and chlororhodates, the ammine and aqua complexes of rhodium halides and of ruthenium halides, especially the chlorides, and the salts of nitroruthenates. Examples of the above salts and complex salts are ruthenium(III) chloride, ruthenium(III) nitrosylchloride, ammonium pentachloroaquaruthenate(III), hexaammineruthenium(II) and -(III) chloride, dichlorobis(2,2xe2x80x2-bipyridyl)ruthenium(II), tris(2,2xe2x80x2-bipyridyl)ruthenium(II) chloride, pentaamminechlororuthenium(III) chloride, potassium pentachloronitrosylruthenium(II), ruthenium(IV) oxide, tetraacetatochlorodiruthenium(II,III), hexakisacetatotriaqua-xcexc-oxotriruthenium(III) acetate, rhodium(III) chloride, rhodium(III) hydroxide, rhodium(III) nitrate, rhodium(III) sulfate, ammonium pentachloroaquarhodate(III), potassium pentachlororhodate(III), sodium hexachlororhodate(III), triamminetrichlororhodium(III), trisethylenediaminerhodium(III) chloride, rhodium(II) acetate dimer, hexakisacetatotriaqua-xcexc-oxotrirhodium(III), rhodium(IV) oxide and potassium hexanitrorhodate(III). Neutral complexes of rhodium and of ruthenium are likewise suitable. It should be noted here that the transitions between salts of ruthenium or rhodium and the saltlike and neutral complexes are imprecise, and the subdivision made here is merely an aid to organization. Examples of neutral complexes include the 2,4-pentanedionates of rhodium and ruthenium, such as ruthenium(III) tris-2,4-pentanedionate, rhodium(I) dicarbonyl-2,4-pentanedionate, rhodium(III) tris-2,4-pentanedionate, bisethylenerhodium(I) 2,4-pentanedionate and norbornadienerhodium(I) 2,4-pentanedionate, and the carbonyl complexes of ruthenium and rhodium, such as dodecacarbonyltetrarhodium, hexadecacarbonylrhodium, tetracarbonyldi-xcexc-chlorodirhodium(I) and dodecacarbonyltriruthenium.
Also suitable are ruthenium complexes of the formula
Ru X1X2(CO)k(L1)1(L2)2
with organophosphorus compounds, where
X1 and X2 independently are hydrogen, halogen, preferably chloride, the anion of a carboxylic acid, such as acetate, benzoate or hexanoate, or of a sulfonic acid, such as phenolsulfonate, acetylacetonate or substituted or unsubstituted phenyl,
k and 1 independently are 0, 1 or 2 with the proviso that k+1=1 or 2,
L1 is selected from carbonyl, pyridine, benzonitrile, dibenzophosphol, cycloolefins and a ligand of the formula PR3, in which
R is alkyl, alkyloxy, cycloalkyl, cycloalkyloxy, aryl, preferably phenyl, which can be unsubstituted or substituted, or aryloxy, and
L2 is PR3 and (L2)2 can also be R2Pxe2x80x94Axe2x80x94PR2 in which R is as defined above and A is alkylene or arylene.
In this context alkyl is either linear or branched alkyl of preferably 1 to 12 and especially 1 to 4 carbons, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, 2-butyl, isobutyl, tert-butyl, n-hexyl, 2-ethylhexyl and n-decyl. Alkoxy is generally C1-C12-alkoxy and preferably C1-C4-alkoxy, such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, 2-butyloxy, tert-butoxy, n-hexyloxy and 2-ethylhexyloxy. The alkyl may also carry hydroxyl or amino functions or can be substituted by one or more nonadjacent oxygens or imino groups. Examples of such radicals are 2-hydroxyethyl, hydroxypropyl, 2-aminoethyl, and 5-hydroxy-3-oxapentyl. Aryl is, for example, phenyl or naphthyl, each of which may carry one or more substituents. Suitable substituents are halogen, such as chloro, alkyl, especially C1-C4-alkyl, alkoxy, especially C1-C4-alkoxy, and hydroxyl, which can also be in ethoxylated form. Preferred aryls are phenyl, o-, m- or p-tolyl, p-chlorophenyl, p-tert-butylphenyl and p-hydroxyphenyl, which can also be in ethoxylated form (with a degree of ethoxylation (EO degree) of 1 to 50). Alkylene is preferably 1,2-ethylene or 1,2- or 1,3-propylene, each of which may be substituted and/or may be part of a carbocycle or heterocycle. Arylene embraces, in particular, o-phenylene, o,o-diphenylene and (o o-diphenylene)methane.
Examples of ligands PR3 are triphenylphosphine, triisopropylphosphine, tris-n-butylphosphine, tris-n-octylphosphine, tricyclohexylphosphine, trisanisylphosphine, tris(p-tolyl)phosphine, triethyl phosphite and tri-n-butyl phosphite.
Further suitable hydrogenation catalysts are rhodium phosphine complexes of the formula
Rh XmL3L4(L5)n
where
X is halide, preferably chloride or bromide, the anion of a carboxylic acid, acetylacetonate, aryl- or alkylsulfonate, hydride or the diphenyltriazine anion,
L3, L4 and L5 independently are CO, olefins, cycloolefins, dibenzophosphol, benzonitrile, PR3 or R2Pxe2x80x94Axe2x80x94PR2,
m is 1 or 2 and n is 0, 1 or 2,
with the proviso that at least one of L3, L4 and L5 is one of the abovementioned phosphorus-containing ligands of the formula PR3 or R2Pxe2x80x94Axe2x80x94PR2.
X is preferably hydride, chloride, bromide, acetate, tosylate, acetylacetonate or the diphenyltriazine anion, especially hydride, chloride or acetate.
Example of suitable phosphine complexes of ruthenium or rhodium are carbonylchlorohydridobis(tricyclohexylphosphine)ruthenium(II), carbonylchlorohydridobis(triisopropylphosphine)ruthenium(II), carbonylchlorohydridobis(triphenylphosphine)ruthenium(II), carbonylchlorostyrylbis(tricyclohexylphosphine)ruthenium(II), carbonylchlorostyrylbis(triisopropylphosphine)ruthenium(II), carbonylchlorobenzoatobis(triphenylphosphine)ruthenium(II), dichlorotris(triphenylphosphine)ruthenium(II), bis(triphenylphosphine)rutheniumdicarbonyl chloride, acetatohydridotris(triphenylphosphine)ruthenium(II), chlorotris(triphenylphosphine)rhodium(I), hydridotetrakis(triphenylphosphine)rhodium(I), hydridotris(dibenzophosphol)rhodium(I).
The hydrogenation activity of the abovementioned ruthenium and rhodium salts and of the complex compounds can in principle be increased by adding phosphorus-containing compounds having the capability to form at least one co-ordinative bond between the phosphorus-and the transition metal. Examples of suitable phosphorus-containing compounds are the abovementioned compounds of the formula PR3 and R2Pxe2x80x94Axe2x80x94PR2, and also trifluorophosphine, dibenzophosphol, etc. Such compounds can also be modified by giving them further atoms or groups suitable for co-ordination with the metal atom, such as amino or imino groups, examples being oxazoline and imidazoline groups. The probable explanation for the action of such phosphorus-containing compounds is that they promote the formation of active hydrogenation species from the individual ruthenium or rhodium precursor employed. Preferred phosphorus-containing compounds are the abovementioned compounds of the formula PR3 or R2Pxe2x80x94Axe2x80x94PR2.
In a preferred embodiment of the present invention the hydrogenation catalysts employed are salts and/or complex compounds of ruthenium. They are employed preferably together with the abovementioned phosphorus-containing compounds, especially with compounds of the formula PR3 and/or R2Pxe2x80x94Axe2x80x94PR2. In this case the phosphorus-containing compounds are selected in particular from triisophosphine, tri-n-butylphosphine, tris-n-octylphosphine, tricyclohexylphosphine, triphenylphosphine, trisanisylphosphine and tris(p-tolyl)phosphine.
In a specific embodiment of the present process a catalyst system is employed which comprises at least one of the abovementioned pentanedionates of ruthenium, especially ruthenium(III) tris-2,4-pentanedionate, and at least one compound of the formula PR3 and/or R2Pxe2x80x94Axe2x80x94PR2, especially triisopropylphosphine, tri-n-butylphosphine, tricyclohexylphosphine and/or triphenylphosphine.
The molar ratio of phosphorus-containing compound to metal atom is generally within the range from 1:2 to 40:1, preferably from 1:1 to 20:1 and, in the case of a combination of a ruthenium pentanedionate with a phosphorus-containing compound, is in the range from 1:2 to 20:1, preferably from 2:1 to 10:1. Before being deployed in the hydrogenation reaction such catalyst systems are preferably prepared by mixing together the components, with or without heating at from 50 to 150xc2x0 C., for example, in an appropriate solvent and, if desired, under a hydrogen pressure of from 1 to 20 bar, for example. Suitable solvents are exemplified by aromatic hydrocarbons, such as benzene, toluene, xylenes, chlorobenzene, anisole, cumene, ethers, such as diethyl ether, tetrahydrofuran, dioxane, amides, such as dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, alcohols, such as methanol, ethanol, n-propanol, isopropanol, n-butanol, tert-butanol or ketones, such as acetone or methyl ethyl ketone.
Suitable substrates for the hydrogenation process of the invention are in principle all aqueous dispersions of polymers having ethylenically unsaturated double bonds. These include both dispersions prepared by free-radical polymerization of aqueous monomer emulsions (primary dispersions) and those whose polymers are prepared by another route and are then converted to an aqueous dispersion form (secondary dispersions). The term polymer dispersion also embraces, in principle, dispersions of microcapsules.
Suitable polymers P containing ethylenically unsaturated double bonds are homo- or copolymers of conjugated dienes comprising generally from 10 to 100% by weight of at least one conjugated diene as monomer (a). Examples of suitable diene monomers (a) include butadiene, isoprene, chloroprene, 1-methylbutadiene, 2,3-dimethylbutadiene, 2-(tri-C1-C4-alkyl)silylbutadiene, such as 2-triethylsilyl-1,3-butadiene, and mixtures thereof. Preferred monomers (a) are butadiene and isoprene, especially butadiene.
In a preferred embodiment the process of the invention is used to hydrogenate polymers P which are built up from at least one conjugated diene as monomer (a) and from at least one further monomer, (b), which is copolymerizable with the diene. Copolymers of this kind are generally composed of from 10 to 99% by weight, in particular from 20 to 95% by weight of monomer(s) (a) and from 1 to 90% by weight, preferably from 5 to 80% by weight of monomer(s) (b).
Examples of suitable monomers (b) are olefins, such as ethylene, propylene, vinylaromatic monomers, such as styrene, xcex1-methyl styrene, o-chlorostyrene or vinyltoluenes, vinyl esters of aliphatic or branched C1-C18 monocarboxylic acids, such as vinyl acetate, propionate, butyrate, valerate, hexanoate, 2-ethylhexanoate, decanoate, laurate and stearate, esters of preferably C3-C6 ethylenically unsaturated mono- and dicarboxylic acids, such as especially acrylic, methacrylic, maleic, fumaric and itaconic acid, with generally C1-C12-, preferably C1-C8-, and, in particular, C1-C4-alkanols, such as methanol, ethanol, n-propanol, isopropanol, 1-butanol, 2-butanol, isobutanol, tert-butanol, n-hexanol, 2-ethylhexanol, or C5-C10-cycloalkanols, such as cyclopentanol or cyclohexanol, and of these preferably the esters of acrylic and/or methacrylic acid, examples being methyl methacrylate, n-butyl methacrylate, tert-butyl methacrylate, n-butyl acrylate, 2-ethylhexyl acrylate and tert-butyl acrylate. Further suitable monomers (b) are ethylenically unsaturated nitriles such as acrylonitrile or methacrylonitrile; preferred monomers (b) are styrene, xcex1-methylstyrene and acrylonitrile.
In addition to the monomers (a) and (b) the polymers P to be hydrogenated may also comprise modifying monomers (c) in copolymerized form. The polymers P can generally contain up to 20% by weight, based on the overall weight of the monomers (a), (b) and (c), of such copolymerized, modifying monomers (c). The modifying monomers (c) include monomers (cxe2x80x2), which are of increased solubility in water (for example,  greater than 60 g/l at 25xc2x0 C. and 1 bar). The monomers (cxe2x80x2) include, for example, the abovementioned ethylenically unsaturated carboxylic acids, especially acrylic, methacrylic, maleic and itaconic acid, the amides of the abovementioned ethylenically unsaturated carboxylic acids, such as acrylamide and methacrylamide, the N-alkylolamides of the abovementioned ethylenically unsaturated carboxylic acids, such as N-methylolacrylamide and N-methylolmethacrylamide, the hydroxyalkyl esters of the abovementioned ethylenically unsaturated carboxylic acids, such as 2-hydroxyethyl acrylate and methacrylate, ethylenically unsaturated sulfonic acids and their alkali metal salts, such as vinylsulfonic acid, allylsulfonic acid, methallylsulfonic acid and acrylamido-2-methylpropanesulfonic acid, and also N-vinyllactams, such as N-vinylpyrrolidone or N-vinylcaprolactam, for example. Such monomers (cxe2x80x2) are generally employed in a minority, in other words  less than 20% by weight, based on the overall amount of the monomers (a), (b) and (c) that are to be polymerized, preferably xe2x89xa610% by weight and, for example, in amounts of up to 0.1 to 10% by weight and especially 0.5 to 8% by weight.
The monomers (c) also include monomers (cxe2x80x3), which have at least two nonconjugated, ethylenically unsaturated bondsxe2x80x94examples are the diesters of dihydric alcohols with ethylenically unsaturated monocarboxylic acids. Examples of these are alkylene glycoldiacrylates and dimethacrylates, such as ethylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, 1,4-butylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, and also divinylbenzene, vinyl methacrylate, vinyl acrylate, allyl methacrylate, allyl acrylate, diallyl maleate, diallyl fumarate, diallyl phthalate, methylenebisacrylamide, cyclopentadienyl acrylate and methacrylate, tricyclodecenyl acrylate and methacrylate, N,Nxe2x80x2-divinylimidazolin-2-one and triallyl cyanurate. Such monomers are employed, if desired, in amounts of from 0.01 to 10% by weight, based on the overall amount of the monomers (a)+(b)+(c).
The advantages of the process of the invention are manifested in particular in connection with the hydrogenation of polymer dispersions comprising copolymerized monomers (b) and/or (c) which carry functional groups that are amenable, in principle, to hydrogenation. Such monomers include, in particular, those having carbonyl, nitrile and/or aryl groups, such as phenyl groups, which can be unsubstituted or substituted.
Preferred embodiments of the process of the invention relate to the hydrogenation of polymer dispersions whose polymers P are built up essentially from butadiene and/or isoprene, especially butadiene as sole monomer (a), and from styrene, acrylonitrile, methacrylonitrile, isobutene and/or alkyl (meth)acrylates as monomer(s) (b).
Preferred monomer combinations (a)/(b) are butadiene and/or isoprene with styrene and/or xcex1-methylstyrene, butadiene with acrylonitrile and/or methacrylonitrile, butadiene and isoprene with acrylonitrile and/or methacrylonitrile, butadiene with acrylonitrile and styrene; butadiene with isobutene; and butadiene with alkyl (meth)acrylates.
One specific embodiment of the present invention relates to the hydrogenation of polymer dispersions whose polymers P are composed essentially of
from 20 to 95% by weight of monomers (a) selected from butadiene and isoprene and
from 5 to 80% by weight of monomers (b) selected from styrene, xcex1-methylstyrene and acrylonitrile,
the proportions of the monomers (a) and (b) adding up to 100% by weight. It is also possible for such polymers to contain copolymerized, modifying monomers (c) in the abovementioned amounts, preferably in amounts of up to 10% by weight based on the overall amount of the monomers (a), (b) and (c). Preferred monomers (c) are acrylic, methacrylic and itaconic acid, acrylamide, methacrylamide, N-methylolacrylamide and/or N-methylolmethacrylamide.
The preparation of such polymers P is known to the skilled worker and can in principle be carried out by anionic, free-radical or Ziegler-Natta polymerization in solution, in bulk, in suspension or in emulsion. Depending on the type of reaction, the conjugated dienes are 1,4- and/or 1,2-polymerized. For the hydrogenation process of the invention it is preferred to employ polymers prepared by free-radical aqueous emulsion polymerization of the above monomers (a) and, if used, (b) and/or (c) (including mini- and microemulsion polymerization). These techniques are sufficiently well known to the skilled worker and are described at length in the literature, for example in Ullmann""s Encyclopedia of Industrial Chemistry, 5th Ed., Vol. A 21., pp. 373-393. In general, such polymers are prepared in the presence of free-radical initiators and, if desired, surface-active substances such as emulsifiers and protective colloids (see, for example, Houben-Weyl, Methoden der organischen Chemie, Vol. XIV/1, Makromolekulare Stoffe, [Macromolecular substances], Georg Thieme-Verlag, Stuttgart 1961, pp. 192-208).
Suitable free-radical polymerization initiators include organic peroxides, such as tert-butyl hydroperoxide, benzoyl hydroperoxide, diisopropylbenzoyl peroxide, inorganic peroxides, such as hydrogen peroxide, salts of peroxomono- and/or peroxodisulfuric acid, especially the ammonium and/or alkali metal peroxodisulfates (persulfates), and azo compounds, particular preference being given to the persulfates. Preference is also given to combined systems composed of at least one organic reducing agent and at least one peroxide and/or hydroperoxide, such as tert-butyl hydroperoxide and the sodium salt of hydroxymethanesulfonic acid, or hydrogen peroxide and ascorbic acid (as an electrolyte-free redox initiator system), and to combine systems which additionally comprise a small amount of a metal compound which is soluble in the polymerization medium and whose metallic component can exist in a plurality of valence states, for example ascorbic acid/iron(II) sulfate/hydrogen peroxide, it also being possible frequently to replace the ascorbic acid by the sodium salt of hydroxymethanesulfinic acid, sodium sulfite, sodium hydrogensulfite or sodium bisulfite and the hydrogen peroxide by tert-butyl hydroperoxide, alkali metal peroxodisulfates and/or ammonium peroxodisulfate. Instead of a water-soluble iron(II) salt it is also possible to employ a combination of water-soluble Fe/V salts.
These polymerization initiators are employed in customary amounts, such as in amounts of from 0.01 to 5, preferably from 0.1 to 2.0% by weight, based on the monomers to be polymerized.
The monomer mixture can if desired be polymerized in the presence of customary regulators, such as mercaptans, an example of which is tert-dodecyl mercaptan. These regulators are then used in an amount of from 0.01 to 5% by weight, based on the overall amount of the mixture.
There are no particular restrictions on the emulsifiers that can be used. Preference is given to neutral emulsifiers such as ethoxylated mono-, di- and trialkylphenols (EO degree: 3 to 50, alkyl: C4 to C9) or ethoxylated fatty alcohols (EO degree: 3 to 50, alkyl: C8 to C36) and/or anionic emulsifiers, such as the alkali metal and ammonium salts of fatty acids (alkyl: C12 to C24), alkyl sulfates (alkyl: C8 to C22), of sulfuric monoesters of ethoxylated alkanols (EO degree: 4 to 30, alkyl: C8 to C22) and of ethoxylated alkylphenols (EO degree: 3 to 50, alkyl: C4 to C10), of alkylsulfonic acids (alkyl: C8 to C22) and of alkylarylsulfonic acids (alkyl: C4 to C18). Further suitable anionic emulsifiers are alkali metal or ammonium salts of mono- or di-C4-C24-alkyl derivatives of bis(phenylsulfonic acid) ether, such as technical-grade mixtures comprising from 50 to 80% of the monoalkylated product. Such emulsifiers are known from U.S. Pat. No. 4,269,749; the technical-grade mixtures are obtainable, for example, commercially under the designation Dowfax(copyright)2A1 (Dow Chemical).
Particular preference is given to the alkali metal and/or ammonium salts, especially the sodium salts, of alkylarylsulfonic acids, alkylsulfonic acids (eg. sulfonated C12-C18 paraffin; on the market as Emulgator K 30 from Bayer AG), alkylsulfates (eg. sodium lauryl sulfonate, on the market as Texapon(copyright)K12 from Henkel) and of the sulfuric monoesters of ethoxylated alkanols (eg. sulfoxylated ethoxylate of lauryl alcohol with 2 to 3 EO units; on the market as Texapon(copyright)NSO from Henkel KGaA). Further suitable emulsifiers are the sodium or potassium salts of fatty acids (C12-C23-alkyl radicals), such as potassium oleate. Additional appropriate emulsifiers are given in Houben-Weyl, loc. cit., pp. 192-208. Instead of or in a mixture with emulsifiers it is also possible, however, to employ conventional protective colloids, such as polyvinyl alcohol, polyvinylpyrrolidone or amphiphilic block polymers with short hydrophobic blocks, for the purpose of co-stabilization. In general the amount of emulsifiers used, based on the monomers to be polymerized, will not exceed 5% by weight.
The free-radical polymerization reaction can be carried out by the whole-batch initial charge (batch) technique, but is preferably operated, especially on the industrial scale, in accordance with the feed technique. In this latter technique the major amount (generally from 50 to 100% by weight) of the monomers to be polymerized are added to the polymerization vessel in accordance with the progress of the polymerization of the monomers already in the polymerization vessel. In this context; the free-radical initiator system can be either included entirely in the initial charge to the polymerization vessel or else added continuously or in stages to the polymerization reaction at the rate at which it is consumed in the course of the free-radical aqueous emulsion polymerization. In each individual case this will depend, as is known, both on the chemical nature of the initiator system and on the polymerization temperature. The initiator system is preferably supplied to the polymerization zone at the rate at which it is consumed.
The polymerization reaction is preferably conducted in the presence of an aqueous polymer dispersion as polymer (seed latex). Such techniques are fundamentally known to the skilled worker and are described, for example, in DE-A 42 13 967, DE-A 42 13 968, EP-A 567 811, EP-A 567 812 or EP-A 567 819, which are incorporated fully herein by reference. In principle it is possible, depending on the desired character, to include the seed in the initial charge or to add it continuously or in stages in the course of polymerization. The polymerization is preferably carried out with the seed in the initial charge. The amount of seed polymer is preferably in the range from 0.05 to 5% by weight, preferably from 0.1 to 2% by weight and, in particular, from 0.2 to 1% by weight, based on the monomers a) to d). The polymer particles of the seed latex that is used preferably have weight-average diameters in the range from 10 to 100 nm, preferably from 20 to 60 nm and, in particular, about 30 nm. Preference is given to the use of a polystyrene seed.
The polymerization reaction is preferably carried out under superatmospheric pressure. The period of polymerization can vary within a wide range, and is generally from 1 to 15 hours, preferably from 3 to 10 hours. The temperature of polymerization is also variable within a wide range and, depending on the initiator used, is from about 0 to 110xc2x0 C.
The polymer dispersions prepared in this way generally have solids contents of up to 75% by weight. Particular importance is attached to polymer dispersions having solids contents of from 40 to 70% by weight. For use in the hydrogenation process of the invention it is possible to employ the dispersions with these solids contents. In some cases, however, the dispersions have to be diluted to an appropriate solids content beforehand. The solids content of the dispersion employed is preferably in the range from 10 to 60% by weight, in particular from 20 to 50% by weight, based on the overall weight of the dispersion.
The surface-active substances still present, in general, in the polymer dispersions, and further substances used, for example, as customary polymerization auxiliaries in emulsion polymerizations, do not have a disruptive effect on the hydrogenation process of the invention. However, it is advisable to subject the polymer dispersions to chemical or physical deodorization before hydrogenation. Physical deodorization, by stripping the residual monomers with steam, is known, for example, from EP-A 584 458. EP-A 327 006 for its part recommends the use of conventional distillation methods. Chemical deodorization takes place preferably by means of a postpolymerization following the main polymerization. Such processes are described, for example, in DE-A 383 4734, EP-A 379 892, EP-A 327 006, DE-A 44 19 518, DE-A 44 35 422 and DE-A 44 35 423.
The hydrogenation of the invention is generally conducted in such a way that one of the abovementioned catalysts or catalyst precursors together, if desired, with one or more coligands, such as the abovementioned phosphorus-containing compounds, as they are or dissolved in an organic solvent, are added to the polymer dispersion. If desired, the dispersion is adjusted to an appropriate solids content by diluting it with water or a water/emulsifier mixture or with a water-miscible organic solvent. Then the desired hydrogen pressure is established and the batch is heated to an appropriate reaction temperature. In this context one possible procedure, for example, is first, after adding the catalyst to the dispersion, to establish a relatively low hydrogen overpressure, then to heat the reaction batch to the desired reaction temperature and then to establish the hydrogen overpressure required for the reaction. It is often judicious to flush the reaction vessel beforehand with an inert gas such as nitrogen, for example.
Suitable solvents for dilution include, in particular, the abovementioned C1-C4-alkanols, ketones such as acetone and ethyl methyl ketone, cyclic ethers such as tetrahydrofuran or dioxane, or amides such as N,N-dimethylformamide or N-methylpyrrolidone. The solvent content of the polymer dispersion that is to be hydrogenated, however, will generally not exceed 20% by weight based on the overall weight of the dispersion. The aqueous polymer dispersion, where necessary, is diluted preferably only with water or with a water/emulsifier mixture.
However, it is found judicious in many casesxe2x80x94and especially when using coligands such as the abovementioned phosphorus-containing compoundsxe2x80x94to combine the particular desired ruthenium and/or rhodium compound in an appropriate solvent with the coligand (see above) and to add the resulting solution or suspension to the polymer dispersion. If desired, this solution or suspension, before being added to the polymer dispersion, is reacted with hydrogen or with another reducing agent, for example with hydrogen, at pressures in the range from 1 to 20 bar and at from 50 to 150xc2x0 C., in the course of which reaction the catalytically active species is formed. Activation may also take place in situ, in other words in the polymer dispersion.
Hydrogenation also takes place in general at a hydrogen partial pressure of from 0.5 to 600 bar, preferably from 50 to 400 bar and, in particular, from 100 to 300 bar. The reaction temperature is generally from 20 to 250xc2x0 C., preferably from 50 to 200xc2x0 C., and, in particular, from 100 to 180xc2x0 C. Depending on the nature of the catalyst system and on the desired conversion the amounts of catalyst employed are in the range of from 1 to 1000 ppm ruthenium and/or rhodium, based on the overall weight of the polymer dispersion to be hydrogenated, preferably from 5 to 500 ppm. The reaction period is generally from 1 to 30 hours, preferably from 2 to 25 hours and, in particular, from 3 to 20 hours.
Depending on the desired character of the hydrogenated polymer the reaction can be conducted up to a certain degree of conversion, which can be established in a conventional manner by choosing the reaction parameters, such as hydrogen pressure, temperature and the nature and amount of the catalyst system employed. The degree of conversion can be determined, for example, by IR spectrometry, by monitoring the bands typical of ethylenically unsaturated double bonds in the range from 900 to 1000 cmxe2x88x921.
The polymer dispersions hydrogenated by processes of the invention are notable for the fact that the ethylenic double bonds of the polymers P present therein have been hydrogenated selectively, even in the presence of other hydrogenation-active double bonds, such as aromatic Cxe2x80x94C double bonds, carbonyl groups, nitrile functions, etc.
The polymer dispersions thus obtainable are novel and are likewise provided with the present invention. The polymers obtainable therefrom, which are obtained in a known manner from the dispersions (see below) and are likewise provided by the present invention, are notable for a highxe2x80x94and in comparison with the nonhydrogenated base dispersions markedly improvedxe2x80x94stability with respect to environmental effects such as light, oxygen and/or elevated temperature. This predestines the polymers of the invention for use in exterior applications, for example as binders for emulsion paints and other coating compositions and as finishes for textiles, leather and paper.
A particularly preferred embodiment of the present invention relates to the hydrogenation of aqueous dispersions of styrene-butadiene polymers. Polymer dispersions comprising copolymerized butadiene and styrene are preferably prepared by free-radical emulsion polymerization and are important industrial products. In many respects they can be compared with polymers based on styrene/butyl acrylate, with the copolymerized butadiene taking over the role of the xe2x80x9csofteningxe2x80x9d butyl acrylate. Although butadiene possesses a considerable cost advantage over butyl acrylate, in that the former can be separated directly from the C4 cut from the steam cracker whereas the latter has to be prepared in at least two steps starting from steam cracker products, butadiene-containing polymers are, on the other hand, hampered by the abovementioned disadvantages in respect of their weathering stability, so that their possible applications have to date been greatly limited.
The hydrogenation process of the invention surprisingly leads, in the case of the above polymers based on butadiene/styrene, to polymers Pxe2x80x2 which in terms of their mechanical properties are at least comparable with, if not superior to, the nonhydrogenated polymers and which have a markedly lower sensitivity to environmental conditions. Both the hydrogenated polymer dispersions and the polymers Pxe2x80x2 present therein are novel and are likewise provided by the present invention. The polymers Pxe2x80x2 can be obtained from the aqueous dispersions in a known manner by removing the water and any solvents present, by precipitation and filtration, for example, or by drying, such as spray drying or freeze drying, or in evaporative extruders.
The polymers Pxe2x80x2 hydrogenated in accordance with the invention that are obtainable starting from polymers P based on styrene and/or xcex1-methylstyrene as monomers (a) and on butadiene and/or isoprene as monomers (b) are composed essentially of structural units I, II and III
where R1, R2 and R3 independently are hydrogen or methyl.
R1 and R2 are preferably hydrogen. In general, such polymers Pxe2x80x2 contain from 55 to 98 mol-% of structural units I and II and from 2 to 45 mol-% of structural units III, based in each case on the overall molar number of the structural units I, II and III.
Such polymers Pxe2x80x2 may additionally include structural units IV
where X is selected from hydrogen, COOH and CH2xe2x80x94COOH, Y from COOH, CONH2, CONHxe2x80x94CH20H and Z from hydrogen, CH3 and, if X=H, from CH2COOH as well. In addition, if Z=H or methyl, X and Y can also be a group xe2x80x94C(O)xe2x80x94Oxe2x80x94C(O)xe2x80x94 and C(O)xe2x80x94N(R)xe2x80x94C(O), in which R is hydrogen, C1-C6-alkyl or aryl. Structural units IV result from the modifying monomers (c) in the polymers P of the starting dispersions. The molar proportion of the structural unit IV is preferably in the range from 0.05 to 10 mol-%, based on the overall molar number of the structural units I, II and III.
The polymers Pxe2x80x2 may also feature structural units V
where R4 is hydrogen or methyl, preferably hydrogen. Structural units V result from copolymerized acrylonitrile or methacrylonitrile in the polymers P of the initial dispersions. The proportion of structural units V can be up to 40 mol-%, based on the overall molar number of the structural units I, II and III, and is for example from 0.5 to 35 mol-%.
The hydrogenated polymers Pxe2x80x2 are notable for high resistance to environmental influences; for example, a low propensity to yellowing and embrittlement. In addition, the polymers Pxe2x80x2 feature an improved tear strength relative to the nonhydrogenated polymers P and a heightened elongation at break. An unwanted buildup in molecular weight caused by crosslinking in the course of hydrogenation has not been observed, and nor has the hydrogenation of the phenyl groups in such polymers.
The polymers Pxe2x80x2 and their dispersions can be employed, for example, as binders for sealing or coating compositions; for example, in emulsion paints, in polymer-modified plasters, especially for exterior applications, and also as pressure-sensitive adhesives and as an elastomeric component in molding compounds.

Method for selective hydrogenation of ethylene unsaturated double bonds in polymerizates