An adaptive control apparatus for keeping a dropping probability of a handoff call requested without user mobility information below a predefined level, to guarantee a quality of service (QoS). The apparatus adaptively controls an admission threshold of each cell in a wireless network to maintain the handoff dropping probability below a predefined level. The admission threshold is dynamically adjusted based on handoff drop events. The apparatus can guarantee QoS and maximize channel utilization. Since the apparatus is simply based on the handoff drop events of each cell rather than mobility of the respective calls, it is possible to remarkably decrease the complexity as compared with the existing mobile-oriented apparatus. In addition, the apparatus can solve the inter-cell unfairness problem.

1. Field of the Invention
The present invention relates generally to an apparatus and method for controlling a drop of a requested call in a wireless network. More particularly, the present invention relates to an apparatus and method for guaranteeing a quality of service (QoS) by keeping a dropping probability of a handoff call requested without user mobility information below a predefined level.
2. Description of the Related Art
Recently, the population of mobile users, particularly among those using systems such as CDMA (Code Division Multiple Access), PCS (Personal Communication System), and GSM (Global System for Mobile communication), has grown at a rapid rate. Also, the demand has increased for multimedia applications requiring high bandwidth, such as high quality video. Therefore, the current trend in wireless networks is to decrease cell sizes (into micro-cells or pico-cells) to provide higher capacity and accommodate more users in a given area. However, smaller cell sizes increase the frequency of handoffs, which results in rapid changes in the conditions of the network traffic. Thus, the QoS provisioning in wireless networks becomes more difficult to achieve.
One of the important QoS issues in wireless networks is how to control handoff drops. When a mobile user moves into an adjacent cell during a session, a handoff occurs and the mobile user communicates continuously through the new base station (BS). However, the handoff could fail if the available bandwidth in the new cell is insufficient for the mobile user. Such a failure is referred to as "a handoff drop".
In general, a handoff drop is considered to have more of a negative impact on a users' perception of quality than does a new call block. As a result, there are required strategies for prioritizing handoff calls over new calls, for example, such as reserving a portion bandwidth exclusively for handoffs. The concept of the bandwidth reservation for handoffs was first introduced in mid-80s (see D. Hong and S. S. Rappaport, "Traffic model and performance analysis of cellular radio telephone systems with prioritized and non-prioritized handoff procedures," IEEE Trans. on Vehicular Technology, 35(3), August 1986). Since then, various strategies that give priority to handoffs have been studied.
Ideally, it would be desirable if handoff drops never occur. However, this would require the network to reserve so much bandwidth in all cells in which a particular mobile unit might enter, and would result in very low channel utilization and/or high new call blocking probability Pb. Therefore, another approach is to provide probabilistic QoS guarantees by keeping the handoff dropping probability Pd below a certain level, rather than eliminate it completely.
In a paper, M. Naghshineh and M. Schwartz, "Distributed Call Admission Control in Mobile/Wireless Networks," IEEE Journal on Selected Areas in Communications, 14(4), May 1996, the admission threshold to satisfy the QoS constraint is a calculation based on the number of users in the current cell and adjacent cells, given the probability that a mobile unit would be handed-off within some time interval. However, this scheme does not specify how to predict the user mobility, and such predictability is essential in their scheme, and assumes the exponential distribution of the cell residence time.
In practice, the cell residence time may not be exponentially distributed (see M. M. Zonoozi and P. Dassanayake, "User Mobility Modeling and Characterization of Mobility Patterns," IEEE Journal on Selected Areas in Communications, 15(7), September 1997).
Moreover, another paper, authored by O. T. W. Yu and V. C. M. Leung, "Adaptive Resource Allocation for Prioritized Call Admission Over an ATM-based Wireless PCN," IEEE Journal on Selected Areas in Communications, 15(7), September 1997, also proposes a technique to compute the reserved bandwidth to maintain the handoff dropping probability Pd within a specified level. However, the paper also assumes the exponentially distributed cell residence time.
In yet another paper, D. Levine, I. Akyildiz, and M. Naghshineh, "A Resource Estimation and Call Admission Algorithm for Wireless Multimedia Networks Using the Shadow Cluster Concept," IEEE/ACM Trans. on Networking, 5(1), February 1997, the shadow cluster concept has been used as a way to estimate future resource requirements and perform admission control in order to limit the handoff dropping probability Pd. In this scheme, mobiles inform the base stations (BSs) in neighboring cells of their bandwidth requirements and movement patterns at the call setup time. Based on this set of information, the BSs predict future demands and admit only those mobiles that can be supported adequately. The drawback of this particular scheme is that precise user mobility should be known a priori, which is impractical, and it requires the exchange of a large number of messages among BSs.
A more practical method of predicting the user mobility has been presented quite recently in a paper, by S. Choi and K. G. Shin, "Predictive and Adaptive Bandwidth Reservation for Handoffs in QoS-Sensitive Cellular Networks," in Proc. ACM SIGCOMM'98, pp. 155-166, September 1998. This method uses the adaptive and predictive bandwidth reservation scheme to provide probabilistic QoS guarantees. Herein, the method disclosed in this paper will be referred to as "CS98". This CS98 scheme is based on the observed history of mobility information to calculate the reserved bandwidth.
In CS98, a predictive and adaptive bandwidth reservation scheme is proposed. First, user mobility is estimated based on an aggregate history of handoffs observed in each cell. This user mobility information is then used to (probabilistically) predict mobiles' moving directions and handoff times. For each cell, the bandwidth to be reserved for handoffs is calculated by estimating the total sum of fractional bandwidths of the expected handoffs within a estimation time window Test. The estimation time window Test is adaptively controlled for the efficient use of bandwidth and effective response to (i) time-varying traffic/mobility and (ii) inaccuracy of mobility estimation.
Although the CS98 scheme is not based on any impractical assumptions, it has still high complexity (see S. Choi and K. G. Shin, "Comparison of Connection Admission Control Schemes in the Presence of Handoffs in Cellular Networks," in Proc. ACM/IEEE Mobicom'98, October 1998). This is because, in the CS98 scheme, a rather complex history-based method is used to calculate the target reserved bandwidth. Handoff events must be cached and the handoff probability of every call in adjacent cells must be calculated every time a new call is tested for admission.
Here, it should be noted that many previous schemes were based on the user mobility information, called "mobile-oriented reservation schemes". If the design goal is to reduce handoff drops to as little as possible, then the user mobility information should be used to predict mobiles' handoff times and next cells and to reserve some bandwidths for those mobile users. However, if the design goal is to keep the handoff dropping probability Pd below a certain level, the user mobility information is not essential. It should be noted that a handoff drop is basically a cell-oriented event (i.e., a handoff drop occurs when a cell is overloaded).
There is another practical scheme in which the cell-oriented policy was introduced (see C. Oliveira, J. B. Kim and T. Suda, "An Adaptive Bandwidth Reservation Scheme for High-Speed Multimedia Wireless Networks," IEEE Journal on Selected Areas in Communications, 16(6), August 1998). Herein, this scheme will be referred to as "OKS98 scheme". This OKS98 scheme determines the amount of reserved bandwidth by the largest of all the requested bandwidths from adjacent cells. After some bandwidth is reserved, it is dynamically adjusted at each cell to keep the handoff dropping probability Pd below a target value.
However, this original adaptive algorithm in OKS98 has some un-specified aspects. First, there is no mention about the monitored period of the handoff dropping probability Pd. Second, it is not clear when to increase or decrease R. In addition, this OKS98 scheme has the inter-cell unfairness problem.

Adaptive admission control method and apparatus for guaranteeing handoff QoS in a wireless network


A chassis dynamometer is disclosed having a dynamometer drum member, a housing member to house a stator, a shoe member to form a gap with the dynamometer drum member, an extension shaft member to radially vary the gap dimension. The extension shaft member may extend radially from the housing member, and the extension shaft member may include external threads. The extension shaft member may include a smooth portion, and the extension shaft member may cooperate with a collar member. The extension shaft member may include a hole member, and the extension shaft member may include a fastening member. The collar member may include a shoulder member, and the extension shaft member may include a flange member.

The art of making various dynamometers has existed for decades. Continuous improvement in the construction of dynamometers for activities including brake testing, performance testing and emissions testing is evidenced by a series of issued patents including U.S. Pat. No. 5,375,461 to Suzuki, U.S. Pat. No. 4,450,728 to D'Angelo et. al., U.S. Pat. No. 4,468,955 to Yamasaki et. al., U.S. Pat. No. 4,688,419 to D'Angelo et al., U.S. Pat. No. 4,870,585 to Manzolini, U.S. Pat. No. 5,010,763 to Schneider, U.S. Pat. No. 3,277,703 to Cline, U.S. Pat. No. 3,554,023 to Geul, U.S. Pat. No. 6,257,054 to Rostkowski et. al., U.S. Pat. No. 5,193,386 to Hesse, Jr. et. al., U.S. Pat. No. 5,844,145 to D'Angelo, U.S. Pat. No. 5,450,748 to Evans et al., U.S. Pat. No. 4,483,204 to Warsaw, U.S. Pat. No. 4,899,595 to Warsaw, U.S. Pat. No. 3,289,471 to Maxwell, U.S. Pat. No. 3,490,276 to Maxwell et. al., U.S. Pat. No. 5,419,192 to Maxwell et. al., U.S. Pat. No. 4,050,299 to Maxwell, U.S. Pat. No. 3,979,950 to Maxwell and U.S. Pat. No. 3,020,753 to Maxwell.
The use of chassis dynamometers for measuring various variables in automotive performance is widely known in the industry. A chassis dynamometer generally includes a frame, at least one set of rollers supported on a frame and a dynamometer attached to the rollers for the purpose of road load stimulation.
For brake testing, general motoring and driving of chassis dynamometer rollers, much less power is required than is necessary for load testing to measure the vehicle power. Frequently, machines use a motor or electric dynamometer that is capable of both functions, i.e. motoring and absorbing power with the chassis dynamometer. However, with the advent of higher horsepower vehicles, it has become necessary to have machines that require greatly oversized motors or electric dynamometers to provide full vehicle power absorption while still providing the lesser power required for driving the rollers. An additional disadvantage of using a large motor or electric dynamometer is the necessity to dissipate heat generated through a resistive load bank or to regenerate the absorbed power as electrical power. Both these functionalities add undesirable complexity and additional cost to the machine.
Accordingly, the need exists for a motoring chassis dynamometer that is very economic in construction. The motoring chassis dynamometer must be modularly built such that the machine may be easily assembled transported and installed as modules. Similarly, if any repair, maintenance or adjustment is required on the chassis dynamometer, the chassis dynamometer may be capable of easy modular disassembly, repair, maintenance and adjustment. Also, the need exists for a chassis dynamometer to provide test performance surpassing the current and anticipated vehicle capability so that tests of vehicle performance, such as brake testing, transmission testing and full engine power testing for higher horsepower vehicles, can be performed without greatly over-sizing the motor or electric dynamometer. The need also exists to offer alternatives to the currently existing dynamometers to provide the same or greater performance by using a reduced size motor and appropriately sized dynamometer. Finally the need exists to construct chassis dynamometers to allow for testing of both low horsepower and high horsepower vehicles by decreasing construction and equipment cost.
There is increasing concern in the United States about the effect of vehicle emissions on air quality. A number of states and local governments have implemented mandatory emissions testing programs to help identify vehicles that are releasing unacceptable levels of harmful emissions.
To conduct emissions testing, dynamometers are typically used to hold the vehicle stationary while its wheels turn.
U.S. Pat. No. 6,886,811 to Spingett discloses a portable dynamometer station with a vehicle mounted lifting assembly. It includes (a) a vehicle, such as a bus, for transporting the dynamometer, (b) a dynamometer with associated monitoring equipment, and (c) a lifting assembly mounted in the vehicle, for transporting the dynamometer from the vehicle to the ground. The lifting assembly includes (i) an upper support beam, (ii) a lower support beam, (iii) a moving trolley on the lower support beam, (iv) a first hydraulic cylinder for moving the lower support beam and the trolley relative to the upper support beam, (v) a second hydraulic cylinder for raising and lowering the dynamometer or other load from the moving trolley, and (vi) a series of pulleys and cables for movement of the lower support beam, the moving trolley, and the dynamometer or other load.
U.S. Pat. No. 6,860,145 to Bergst discloses a motorized chassis dynamometer machine. In one embodiment, the dynamometer machine includes a fixed frame assembly. At least one roller assembly is mounted on the fixed frame assembly. At least one independent motor assembly is connected to each roller assembly. The independent motor assembly is used for driving the roller assembly. At least one independent loading dynamometer assembly capable of measuring the vehicle input power at each roller assembly is coupled to each roller assembly. In a preferred embodiment, the dynamometer assembly is only operable for loading each independent roller assembly, while the motor assembly is operable for driving each independent roller assembly. The machine has at least one motor controller capable of controlling each independent motor assembly and at least one dynamometer controller capable of controlling each independent dynamometer assembly. Each roller assembly, motor controller and dynamometer controller are in turn controlled and manipulated by an overall controller. The dynamometer machine may further include a torque sensor for each motor assembly and each dynamometer assembly. The torque sensors are used to measure torque reaction, each torque sensor independently measuring torque for each of the roller assemblies.

Chassis dynamometer having an eddy current brake with adjustable air gap and modular components


An oil particularly suited for equipment having copper containing alloy elements, is compounded from about 20 to 99.75% by weight of natural or synthetic oil, and about 0.25 to 30% by weight of an acid forming friction modifier, particularly, a fully esterified compound, such as glycerol trioleate (GTO). The oil evidences a marked improvement in frictional behavior and wear protection, especially regarding the corrosive wear of Cu based alloys. The oil containing glycerol trioleate does not release oleic acid unless and until boundary conditions are present, thereby on one hand effectively lubricating under boundary conditions, while on the other hand minimizing the presence of oleic acid and thereby reducing chemical wear.

1. Field of the Invention
This invention relates to lubricating oils. More specifically, this invention relates to protective oils for equipment with copper alloy components as in polyethylene compressors.
2. Discussion of the Prior Art
Heretofore it was well known in the lubricating art to provide white mineral oil lubricants for compressors, as is disclosed in W. A. Potanina, E. N. Marcheva, E. N. Sidlyaronok, S. K. Bogdanov, T. P. Ponomareva "NKM-40 naphthenic compressor oil used in the production of polyethylene". Khim. Technol. Topliv Masel, No. 1 (1978) 22-23; and E. N. Marcheva, W. A. Potanina, G. T. Fuks, "Production of NKM-40 White Oil Compressor Lubricant From the West Siberian Crudes" Khim. Technol. Topliv Masel, No. 7 (1984) 11-12.
It was also known in the prior art to provide amounts of oleic acid in white mineral oil as friction modifier, such as disclosed in British Patent No. 1,338,505. The continued presence of oleic acid in the blends used for copper based alloy parts lubrication caused unnecessary chemical wear. That is, oleic acid provided good lubricity, but its continual presence caused unnecessary chemical wear because of its ongoing reactivity with the copper-containing alloy.
Other lubricating compositions used certain phosphates and oleates as anti-wear additives, such as disclosed in U.S. Pat. No. 3,970,570 to Pratt, et al.
Wisotsky, U.S. Pat. No. 4,505,829 discloses the use of glycerol monoleate and glyceroi dioleate as stabilizing additives for the lubricating oil. Waldmann, U.S. Pat. No. 3,235,449 also discloses the use of partial esters of glycerols for foam stabilization in lubricants.
British Patent No. 1,340,804 discloses a lubricating composition for a two-stroke internal combustion engine. That composition includes the synergistic combination of a polybutene or polyisobutylene with a triglyceride of an unsaturated aliphatic carboxylic acid containing 18 carbon atoms, with the triglyceride to polymer ratio being 1:10 to 1:30.
Culpon, U.S. Pat. No. 5,156,759 discloses the use of di and tri synthetic polyol esters as solubilizers for other additives in polyalphaolefin base oil.
In the art relating to the lubrication of equipment with copper bearing alloy surfaces, there was the specific problem of chemical wear caused by the oleic acid friction modifier. The art therefore desired an oil that not only improved frictional characteristics but exhibited a high level of protection against copper base alloy chemical wear.

Lubricating oil having lubrication condition responsive activity


A biopsy device includes an outer cannula, an inner rod, a sheath operably associated with the outer cannula, a handle assembly removably attachable to the sheath, and a release member for releasably attaching the handle assembly to the sheath. In one embodiment, a locking element associated with the sheath comprises a pair of notches located on either side of the sheath, and a locking element associated with the handle assembly comprises a pair of slots in communication with an opening within the handle assembly. The release member comprises a rotatable collar located in a channel on the handle assembly. When the release member is rotated from a first position to a second position, a portion thereof protrudes through the slots into the notches on the sheath, thereby locking the sheath in place.

1. Field of the Invention
The present invention relates in general to biopsy devices and, more particularly, to a biopsy device with a removable handle assembly.
2. Background Art
Biopsy devices have been known in the art for many years. In particular, many such biopsy devices have included a hollow outer cannula with some form of inner rod slidable within the outer cannula. The outer cannula conventionally consists of a proximal end, a distal end, and some form of a handle associated with the proximal end. The inner rod may typically take several different forms, including a sharpened stylet for insertion of the biopsy device into a patient, an inner cannula for sampling tissue, and/or an ejector rod for forcing the sample out of the outer cannula. The inner rod also typically includes a second or connection handle which may be secured to the handle portion of the outer cannula.
Such devices typically provide for the securable joining together of the outer cannula and inner rod handles when the inner rod is inserted within the outer cannula. Once the entire assembly is inserted within a patient, the inner rod is typically removed by separating the outer cannula and inner rod handles, and removing the inner rod by means of the inner rod handle. This type of structure is disclosed by Baldridge, U.S. Pat. No. 5,357,974, Tretinvak, U.S. Pat. No. 4,403,617, Tretinvak, U.S. Pat. No. 4,630,616, Lee, U.S. Pat. No. 4,655,266, and Strasser, et al., U.S. Pat. No. 4,838,282, among others.
Many of these types of devices require rotation of one of the handles themselves to unlock and separate the handles from one another, resulting in a change of orientation of the handles with respect to one another while the device is within the patient. This change in orientation of the handles, however, can often cause a corresponding change in the orientation of the inner rod with respect to the outer cannula, which can be undesirable to the user. Likewise, the manipulations of the overall device while in use can inadvertently separate the cannula handle from the rod handle, unlocking the device and causing the aligned tips of the cannula and rod to become misaligned. Other such devices contain a locknut securing device positioned directly atop the inner rod, which must be repeatedly rotated in order to remove the inner rod, thereby allowing the user to directly remove the rod itself from the interior of the cannula.
One application in which such devices are used is to repair crushed vertebrae. Typically, the cannula and rod portions of the biopsy device are inserted within the patient in order to locate the proper vertebra. After the cannula has been positioned within a vertebra, then an imaging device, such as an x-ray machine, is used to view the location of the cannula tip to determine whether it is positioned properly. If the cannula is not in the desired position, then the position of the biopsy device is adjusted as needed. Once it is determined that the cannula is positioned properly, then the inner rod is removed, and a form of cement or other binding element is injected into the vertebra through the cannula in order to reexpand the crushed vertebra. The devices in the prior art, however, present a particular disadvantage for this type of application. Once the user has removed the inner rod, along with its corresponding handle, the outer cannula handle remains in place, providing an undesired impediment to the imaging process.
It is therefore desired to provide a biopsy device with a separate handle assembly which is capable of being removed after the device is inserted into a patient, leaving the outer cannula and inner rod in place in the desired location, thereby eliminating the impediment to the imaging process presented by the presence of the outer cannula handle, as described above.
It is further desired to provide a biopsy device which allows the user to readily unlock and remove the handle assembly without affecting the orientation of the outer cannula and the inner rod with respect to one another, in order to prevent an undesired corresponding change in orientation of the distal ends of each.
Another object of the invention is to provide a biopsy device having a threaded region for the connection of external devices to the outer cannula, thereby allowing the outer cannula to be used with any number of medical devices requiring access to interior regions of the body.
It is also an object of the invention to provide a biopsy device in which the handle assembly may be resterilized after use and reused, resulting in significant cost savings over similar devices with attached handles which are disposed along with the rest of the device after use.
These and other objects of the present invention will become apparent in light of the present specification, claims, and drawings.
The present invention is directed to a biopsy device having a removable handle for alternatively attaching and removing a handle assembly while the cannula portion of the device is inserted into a patient, without affecting the orientation of the cannula portion of the device within the patient. The biopsy device comprises an outer cannula having a proximal end, a distal end, and a substantially hollow cross-section between the proximal and distal ends; an inner rod capable of being telescopically inserted into and retracted from the outer cannula and having a proximal end and a distal end; a sheath operably associated with and surrounding at least a portion of the outer cannula, and comprising a locking element; a handle assembly removably attachable to the sheath comprising a locking element and an opening for receiving at least a portion of the sheath; and a release member for releasing the handle assembly from attachment to the sheath by interacting with the locking elements associated with the sheath and the handle assembly. Further, the sheath may be at least partially inserted within the opening in the handle assembly and attached thereto, thereby retainably, yet releasably, locking the handle assembly to the outer cannula and the inner rod.
In another embodiment of the invention, the release member is a release element which is capable of toggling by the user between at least two positions in order to alternatively lock and release the handle assembly to the sheath.
In a further embodiment, the locking element associated with the sheath comprises at least one slot on the sheath which is capable of interacting with the release member to prevent separation of the sheath and the handle assembly.
In a still further embodiment, the locking element associated with the handle assembly comprises at least one aperture in the handle assembly which is capable of interacting with the release member to prevent separation of the sheath and the handle assembly.
In a yet further embodiment, the release member comprises a rotatable collar associated with at least one of the sheath and the handle assembly, and which is capable of being rotated at least partially about the sheath and the handle assembly when the two are joined together. The rotatable collar has at least two stationary positions, so that when the collar is in one position, a portion of the collar interacts with both of the locking elements associated with the sheath and the handle assembly to prevent separation of the sheath and the handle assembly. When the collar is in the other position, it avoids interaction with both of the locking elements, thereby permitting separation of the sheath and handle assembly from one another.
In an alternative embodiment, the release member comprises a slide member associated with at least one of the sheath and the handle assembly, and which is capable of lateral movement relative to the sheath and the handle assembly when the two are joined together. The slide member has at least two stationary positions, so that when the slide member is in one position, a portion of the slide member interacts with both of the locking elements associated with the sheath and the handle assembly to prevent separation of the sheath and the handle assembly. When the slide member is in the other position, it avoids interaction with both of the locking elements, thereby permitting separation of the sheath and handle assembly from one another.
In another embodiment of the invention, the opening in the handle assembly for receipt of the sheath is asymmetrical about at least one axis substantially perpendicular to the longitudinal axis of the opening.
In a further embodiment, at least a portion of the sheath has an asymmetrical cross-section substantially similar to that of the asymmetrical opening in the handle assembly, so as to be insertable into the handle assembly only when the sheath and the handle assembly are aligned in one particular orientation. This ensures that the outer cannula and the inner rod will be aligned in the same particular orientation relative to the handle assembly when the sheath and the handle assembly are locked together.
In still another embodiment of the invention, at least a portion of the outer surface of the sheath is threaded to enable the attachment of a comparably threaded component of a separate conduit for attachment to the outer cannula after the handle assembly is removed from the sheath.
An additional embodiment of the invention further includes an attachment member for securably attaching the inner rod within the outer cannula.
In a further embodiment, the attachment member comprises at least one prong associated with the inner rod for engaging with the sheath to securably attach the inner rod within the outer cannula.
Yet another embodiment includes a locking indicia for readily indicating whether the sheath and the handle assembly are in a locked or an unlocked orientation, relative to one another.
In alternative embodiments of the invention, the inner rod may comprise at least one of an inner cannula, a stylet, an obturator and an ejector rod.


A composition is disclosed comprising:

1. Field of the Invention
The present invention relates to the oxidative stabilization of organic materials, especially polyolefin-based thermoplastic resins. More particularly, the present invention relates to the oxidative stabilization of thermoplastic resins with synergistic blends of (1) secondary aromatic amines and/or N,Nxe2x80x2-substituted oxamides, (2) sterically hindered phenols, and (3) lactones having a base structure of a 3-phenylbenzofuran-2-one.
2. Description of Related Art
Manufacturers of plastic goods have experienced a long-standing problem in stabilizing plastic resins during the high temperature, high shear, blending, and extrusion processes that are common in the industry. Resins that show excellent long-term heat stability characteristics may not be sufficiently protected against the type of degradation that occurs in an extruder during long residence times or in applications where the plastic is exposed to high temperature heat fusion followed by compression molding.
U.S. Pat. No. 4,611,016 discloses a process for stabilizing organic polymeric materials comprising incorporating therein a benzofuran (2) one or indolin (2) one compound as stabilizer. Such stabilized polymeric materials are said to be stabilized against degradation during the polymer processing.
U.S. Pat. No. 4,797,511 discloses a composition stabilized against oxidative degradation comprising: a polyolefin, carbon black homogeneously incorporated in said polyolefin, a stabilizing amount of thiodiethylene bis(3,5-di-t-butyl-4-hydroxy)hydrocinnamate first stabilizer component incorporated into said polyolefin and a second stabilizer component of at least one amine antioxidant selected from the group consisting of a para-substituted aralkyl-substituted diphenylamine; a para-phenylenediamine and a polymerized dihydroquinoline incorporated into said polyolefin.
U.S. Pat. No. 4,837,259 discloses polypropylene stabilized against oxidative degradation by the presence therein of a stabilizing amount of an antioxidant composition that comprises:
(a) at least one aralkyl-substituted diarylamine; and
(b) at least one sterically hindered phenol.
U.S. Pat. No. 5,175,312 discloses compounds of the formula
in which R1 is C13-C30 alkyl, R2 is hydrogen, C1-C10 alkyl, C5-C12 cycloalkyl, C5-C7 cycloalkyl which is substituted by C1-C4 alkyl, or is phenyl or C7-C12 phenylalkyl, R3 is hydrogen or C1-C4 alkyl and Z is phenyl, phenyl which is substituted by C1-C8 alkyl, C1-C4 alkoxy or chlorine, a group
n which n is 1 or 2 or a group
in which the radicals A independently of one another are C1-C8 alkyl, methoxy or ethoxy, that are said to be suitable for stabilizing organic material against oxidative, thermal and actinic degradation.
U.S. Pat. No. 5,516,920 discloses compounds of the formula
as stabilisers for protecting organic materials, in particular polymers and lubricants, against thermal, oxidative or light-induced degradation.
U.S. Pat. No. 5,607,624 discloses a process for the preparation of 3-arylbenzofuranones of a defined structure similar to the above.
U.S. Pat. No. 5,807,505 discloses compounds of the formula
as stabilizers for protecting organic materials against thermal, oxidative or light-induced degradation.
WO 99/03915 discloses synergistic blends of phosphites and lactones having a base structure of 3-phenylbenzofuran-2-one with or without other additives as stabilizers for polymers, particularly during melt processing as evidenced by changes in melt flow and in some instances, resistance to yellowing.
Krxc3x6nke, C., Proceedings from Polyolefins X International Conference; pp. 555-569 (1997) discloses, inter alia, an extremely active stabilizer for polyolefin processing based on a benzofuranone (lactone) derivative. The author states that, when used in combination with phenolic/phosphite antioxidant blends, new levels of performance are achieved.
The disclosures of the foregoing are incorporated herein by reference in their entirety.
The present invention is characterized by a polymeric material that includes a stabilizing mixture comprising at least three components. The first component is a secondary aromatic amine, the second component is a sterically hindered phenol, and the third component is a lactone having a base structure of a 3-phenylbenzofuran-2-one.
The synergistic effect of blends of secondary aromatic amines and/or N,Nxe2x80x2-substituted oxamides and hindered phenols when used to stabilize polyolefins is known in the art. However, the use of these blends suffers from a major drawback, i.e., they have been found to a furnish sub-par performance as stabilizers during melt processing, especially when subjected to multiple pass extrusion testing, as evidenced by measuring retention of melt-flow rate and resistance to yellowing. Multiple pass extrusion is a very common test method to assess the process stabilization afforded to a polymer. Moreover, this lack of processing stabilization effect has impeded the more widespread use of secondary aromatic arnine/phenol blends in more demanding applications as far as processing stabilization is concerned.
It has now, surprisingly, been found that this impediment to the use of secondary aromatic amines and/or N,Nxe2x80x2-substituted oxamide/phenol blends as processing stabilizers can be circumvented when a third component, chosen from the class of 2-phenylbenzofuran-2-one lactones, is included, thus giving a ternary blend. Thus, the present invention is directed to the discovery that various combinations of secondary aromatic amines and/or N,Nxe2x80x2-substituted oxamides and sterically hindered phenols form synergistic blends with 3-phenylbenzofuran-2-one lactone with tremendously improved process stabilization, as evidenced by retention of melt flow rate and, in some cases, resistance to yellowing on multiple pass extrusion.
More particularly, the present invention is directed to a composition comprising:
(A) a thermoplastic resin; and
(B) a stabilizing amount of a blend of at least one sterically hindered phenol antioxidant, at least one secondary aromatic amine and/or N,Nxe2x80x2-substituted oxamide antioxidant, and at least one lactone antioxidant having a 3-phenylbenzofuran-2-one structure.
In a preferred embodiment, the present invention is directed to a composition comprising:
(A) a thermoplastic resin; and
(B) a stabilizing amount of:
(1) a first stabilizer comprising at least one secondary aromatic amine and/or N,Nxe2x80x2-substituted oxamide antioxidant selected from the group consisting of
(i) a hydrocarbon-substituted diarylamine,
(ii) a reaction product of a diarylamine and an aliphatic ketone,
(iii) an N,Nxe2x80x2-hydrocarbon Substituted para-phenylenediamine, and
(iv) a polymerized dihydroquinoline;
(2) a second stabilizer comprising at least one sterically hindered phenol antioxidant; and
(3) a third stabilizer comprising at least one lactone antioxidant of the structure
xe2x80x83wherein
R1 and R2 are independently selected from the group consisting of hydrogen, chloro, hydroxy, C1-C25 alkyl, C7-C9-phenylalkyl, unsubstituted or C1-C4 alkyl-substituted phenyl, unsubstituted or C1-C4 alkyl-substituted C5-C8 cycloalkyl; C1-C18 alkoxy, C1-C18 alkylthio, C1-C4 alkylamino, di-(C1-C4 alkyl)amino, C1-C25 alkanoyloxy, C1-C25 alkanoylamino, C3-C25 alkenoyloxy, C3-C25 alkanoyloxy which is interrupted by oxygen, sulfur or  greater than Nxe2x80x94R8; C6-C9 cycloalkylcarbonyloxy, benzoyloxy or C1-C12 alkyl-substituted benzoyloxy;
R8 is hydrogen or C1-C8 alkyl; and
R3 and R4 are independently selected from the group consisting of C1-C8 alkyl, C1-C4 alkoxy, halogen, a group
xe2x80x83in which n is 1 or 2, or a group
xe2x80x83in which the radicals A are independently selected from the group consisting of C1-C8 alkyl and C1-C8 alkoxy.
In another aspect, the present invention is directed to a method for stabilizing a composition comprising a thermoplastic resin comprising adding thereto a stabilizing amount of a blend of at least one sterically hindered phenol antioxidant, at least one secondary aromatic amine and/or N,Nxe2x80x2-substituted oxamide antioxidant, and at least one lactone antioxidant having a 3-phenylbenzofuran-2-one structure.
In a preferred embodiment of this aspect, the present invention is directed to a method for stabilizing a composition comprising a thermoplastic resin against oxidative degradation comprising adding to said composition a stabilizing amount of:
(A) a first stabilizer comprising at least one secondary aromatic amine and/or N,Nxe2x80x2-substituted oxamide antioxidant selected from the group consisting of
(i) a hydrocarbon-substituted diarylamine,
(ii) a reaction product of a diarylamine and an aliphatic ketone,
(iii) an N,Nxe2x80x2-hydrocarbon substituted para-phenylenediamine, and
(iv) a polymerized dihydroquinoline;
(B) a second stabilizer comprising at least one sterically hindered phenol antioxidant; and
(C) a third stabilizer comprising at least one lactone antioxidant of the structure
xe2x80x83wherein
R1 and R2 are independently selected from the group consisting of hydrogen, chloro, hydroxy, C1-C25 alkyl, C7-C9-phenylalkyl, unsubstituted or C1-C4 alkyl-substituted phenyl, unsubstituted or C1-C4 alkyl-substituted C5-C8 cycloalkyl, C1-C18 alkoxy, C1-C18 alkylthio, C1-C4 alkylamino, di-(C1-C4 alkyl)amino, C1-C25 alkanoyloxy, C1-C25 alkanoylamino, C3-C25 alkenoyloxy, C3-C25 alkanoyloxy which is interrupted by oxygen, sulfur or  greater than Nxe2x80x94R8; C6-C9 cycloalkylcarbonyloxy, benzoyloxy or C1-C12 alkyl-substituted benzoyloxy;
R8 is hydrogen or C1-C8 alkyl; and
R3 and R4 are independently selected from the group consisting of hydrogen, C1-C8 alkyl, C1-C4 alkoxy, halogen, a group
xe2x80x83n which n is 1 or 2, or a group
xe2x80x83in which the radicals A are independently selected from the group consisting of C1-C8 alkyl and C1-C8 alkoxy.
The present invention is characterized by a polymeric material to which a stabilizing mixture comprising at least three components has been added. Polymeric materials afforded stabilization by the stabilizing mixtures of the present invention are from the group of thermoplastic resins, especially polyolefins, preferably polypropylene. Further included are such thermoplastic resins to which certain inorganic filler materials, e.g., glass, have been added, up to a level of about 50 percent of the total weight of the glass and resin.
A further preferred embodiment of the present invention includes the presence of carbon black in the polymer or glass filled polymer. The carbon black is useful, inter alia, for providing resistance to the effects of ultraviolet light.
The thermoplastic resins that can be stabilized against oxidative degradation employing the ternary mixtures of the present invention include resins derived from ethylene including low density polyethylene (LDPE), linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), or other ethylene derived resins that have densities from 0.85 to 1.4 gm/cm3; homopolymers derived from mono- and di-ethylenically unsaturated hydrocarbon monomers of C3 and above, such as, polypropylene, polyisobutylene, polymethylbutene-1, polymethylpentene-1, polybutene-1, polyisobutylene, and the like; copolymers derived from two or more monomers, such as, ethylene-propylene copolymers, preferably having at least a majority of propylene, propylene-butene-1 copolymers, propylene-isobutylene copolymers, and the like, and blends thereof, polystyrenes; polyvinylhalides; and engineering thermoplastics, for example, polyamides, polyesters, polyphenyleneoxides, polyphenylenesulfides, polyacetals, aliphatic polyketone co- or terpolymers, poly(ethersulfones), polycarbonates, liquid crystalline polymers, poly(etheretherketones), and poly(arylates). It is preferred that the thermoplastic resin that is protected by the stabilizing blends of the present invention be a polyolefin, PET, PBT, polystyrene, a polyacrylic, a polycarbonate, PVC, EPDM, SAN, PPO, SBR, ABS, or a nylon, more preferred that it be a polyolefin, and most preferred that it be polypropylene.
As stated above, one of the components in the stabilizing blend incorporated in the thermoplastic resin, whether or not it contains glass and/or carbon black, is a sterically hindered phenol. Another component is a secondary aromatic amine and/or an N,Nxe2x80x2-substituted oxamide, and a third component is a lactone antioxidant having a 3-phenylbenzofuran-2-one structure. These blends of sterically hindered phenols, secondary aromatic amines and/or N,Nxe2x80x2-substituted oxamides, and lactones have unexpectedly been found to protect thermoplastic resins, e.g., polypropylene, optionally in the presence of carbon black and/or glass, from polymer breakdown, as evidenced by retention of melt flow rate and, in some cases, resistance to yellowing upon multiple pass extrusion.
It has further been found that the stabilizing three-component blend may be made up from two different secondary aromatic amines and/or N,Nxe2x80x2-substituted oxamides and at least one lactone, provided that one of the secondary aromatic amines and/or N,Nxe2x80x2-substituted oxamides employed also possesses hindered phenol functionality. Thus, in the practice of the present invention, there must be at least three separate components, i.e., there must be a component having secondary aromatic amine and/or N,Nxe2x80x2-substituted oxamide functionality, there must be a component having hindered phenol functionality, and there must be a component having the above defined lactone functionality.
The sterically hindered phenols that are useful in the practice of the present invention are preferably selected from the group consisting of hindered phenols having a molecular weight above 500 Da. Preferred examples include 2,4-dimethyl-6-octyl-phenol; 2,6-di-t-butyl-4-methyl phenol (i.e., butylated hydroxy toluene); 2,6-di-t-butyl-4-ethyl phenol; 2,6-di-t-butyl-4-n-butyl phenol; 2,2xe2x80x2-methylenebis(4-methyl-6-t-butyl phenol); 2,2xe2x80x2-methylenebis(4-ethyl-6-t-butyl phenol); 2,4-dimethyl-6-t-butyl phenol; 4-hydroxymethyl-2, 6-di-t-butyl phenol; n-octadecyl-beta(3, 5-di-t-butyl-4-hydroxyphenyl)propionate; 2,6-dioctadecyl-4-methyl phenol; 2,4,6-trimethyl phenol; 2,4,6-triisopropyl phenol; 2,4,6-tri-t-butyl phenol; 2-t-butyl-4,6-dimethyl phenol; 2,6-methyl-4-didodecyl phenol; tris(3,5-di-t-butyl-4-hydroxy isocyanurate, and tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane.
More preferred are octadecyl-3,5-di-t-butyl-4-hydroxy-hydrocinnamate (NAUGARD 76, Uniroyal Chemical; IRGANOX 1076, Ciba-Geigy); tetrakis{methylene(3,5-di-t-butyl-4-hydroxy-hydrocinnamate)}methane (NAUGARD 10, Uniroyal Chemical; IRGANOX 1010, Ciba-Geigy); 2,2xe2x80x2-oxamido bis{ethyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)}propionate (NAUGARD XL-1, Uniroyal Chemical); 1,2-bis(3,5-di-t-butyl-4-hydroxyhydrocinnamoyl)hydrazine (IRGANOX MD 1024,Ciba-Geigy); 1,3,5-tris(3,5-di-t-butyl-4-hydroxybenzyl)-s-triazine-2,4,6 (1H,3H,5H)trione (IRGANOX 3114,Ciba-Geigy); 1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)-s-triazine-2,4,6-(1H,3H,5H)trione (CYANOX 1790, American Cyanamid Co.); 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene (ETHANOX 330, Ethyl Corp.); 3,5-di-t-butyl-4-hydroxyhydrocinnamic acid triester with 1,3,5-tris(2-hydroxyethyl)-5-triazine-2,4,6(1H,3H,5H)-trione, and bis(3,3-bis(4-hydroxy-3-t-butylphenyl)butanoic acid)glycolester.
Most preferred are the hindered phenols having molecular weights above 700, especially polyphenols that contain three or more substituted phenol groups, such as tetrakis{methylene(3,5-di-t-butyl-4-hydroxy-hydrocinnamate)}methane and 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene.
The secondary aromatic amines that are useful in the practice of the present invention can be represented by the general formula
R1xe2x80x94NHxe2x80x94R2
where R1 and R2 may be, but are not necessarily, identical. Thus, in a preferred embodiment, R1 and R2 can be independently selected from the group consisting of (i) aromatic carbon, (ii) aliphatic R1 and aromatic R2 carbon atoms, and (iii) aromatic carbon linked to a second nitrogen atom to give a phenylene diamine.
Where R1 is aliphatic, it can be straight chain or branched and can have from one to twelve carbon atoms, e.g., methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, and isomers thereof. It is preferred that, where R1 is aliphatic, it be a straight or branched chain aliphatic group having from one to eight carbon atoms, and more preferred that it have from one to four carbon atoms.
The amine antioxidants can be hydrocarbon substituted diarylamines, such as, aryl, alkyl, alkaryl, and aralkyl substituted diphenylamine antioxidant materials. A nonlimiting list of commercially available hydrocarbon substituted diphenylamines includes substituted octylated, nonylated, and heptylated diphenylamines and para-substituted styrenated or xcex1-methyl styrenated diphenylamines. The sulfur-containing hydrocarbon substituted diphenylamines, such as p-(p-toluenesulfonylamido)diphenylamine, i.e.,
are also considered as part of this class.
Hydrocarbon-substituted diarylamines that are useful in the practice of this invention can be represented by the general formula
Arxe2x80x94NHxe2x80x94Arxe2x80x2
wherein Ar and Arxe2x80x2 are independently selected aryl radicals, at least one of which is preferably substituted with at least one alkyl radical. The aryl radicals can be, for example, phenyl, biphenyl, terphenyl, naphthyl, anthryl, phenanthryl, and the like. The alkyl substituent(s) can be, for example, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, isomers thereof, and the like.
Preferred hydrocarbon-substituted diarylamines are those disclosed in U.S. Pat. Nos. 3,452,056 and 3,505,225, the disclosures of which are incorporated by reference herein. The preferred hydrocarbon-substituted diarylamines an be represented by the following general formulas:
where
R11 is selected from the group consisting of phenyl and p-tolyl radicals;
R12 and R13 are independently selected from the group consisting of methyl, phenyl, and p-tolyl radicals;
R14 is selected from the group consisting of methyl, phenyl, p-tolyl, and neopentyl radicals;
R15 is selected from the group consisting of methyl, phenyl, p-tolyl, and 2-phenylisobutyl radicals; and,
R16 is a methyl radical.
xe2x80x83where
R11 through R15 are independently selected from the radicals shown in Formula I and R17 is selected from the group consisting of methyl, phenyl, and p-tolyl radicals;
X is a radical selected from the group consisting of methyl, ethyl, C3-C10 sec-alkyl, xcex1,xcex1-dimethylbenzyl, xcex1-methylbenzyl, chlorine, bromine, carboxyl, and metal salts of the carboxylic acids where the metal is selected from the group consisting of zinc, cadmium, nickel, lead, tin, magnesium, and copper; and,
Y is a radical selected from the group consisting of hydrogen, methyl, ethyl, C3-C10 sec-alkyl, chlorine, and bromine.
xe2x80x83where
R11 is selected from the group consisting of phenyl or p-tolyl radicals;
R12 and R13 are independently selected from the group consisting of methyl, phenyl, and p-tolyl radicals;
R14 is a radical selected from the group consisting of hydrogen, C3-C10 primary, secondary, and tertiary alkyl, and C3-C10 alkoxyl, which may be straight chain or branched; and
X and Y are radicals selected from the group consisting of hydrogen, methyl, ethyl, C3-C10 sec-alkyl, chlorine, and bromine.
xe2x80x83where
R18 is selected from the group consisting of phenyl and p-tolyl radicals;
R19 is a radical selected from the group consisting of methyl, phenyl, p-tolyl and 2-phenyl isobutyl; and
R20 is a radical selected from the group consisting of methyl, phenyl, and p-tolyl.
xe2x80x83where
R21 is selected from the group consisting of hydrogen, xcex1,xcex1-dimethylbenzyl, xcex1-methylbenzhydryl, triphenylmethyl, and xcex1,xcex1 p-trimethylbenzyl radicals;
R22 is selected from the group consisting of phenyl or p-tolyl radicals;
R23 is selected from the group consisting of methyl, phenyl, and p-tolyl radicals; and
R24 is selected from the group consisting of methyl, phenyl, p-tolyl, and 2-phenylisobutyl radicals.
Typical chemicals useful in the invention are as follows:

where R18 is phenyl and R19 and R20 are methyl.
Of the foregoing preferred hydrocarbon-substituted diarylamines, the substituted diphenylamines of the formula:
where R25 and R26 are methyl or phenyl are especially preferred. The compound wherein R25 and R26 are both methyl is 4,4xe2x80x2-bis(xcex1,xcex1-dimethylbenzyl)diphenylamine and the compound wherein R25 and R26 are both phenyl is 4,4xe2x80x2-bis(xcex1-methylbenzyl)diphenylamine.
A second class of amine antioxidants comprises the reaction products of a diarylamine and an aliphatic ketone. The diarylamine aliphatic ketonereaction products that are useful herein are disclosed in U.S. Pat. Nos. 1,906,935; 1,975,167; 2,002,642; and 2,562,802. Briefly described, these products are obtained by reacting a diarylamine, preferably a diphenylamine, which may, if desired, possess one or more substituents on either aryl group, with an aliphatic ketone, preferably acetone, in the presence of a suitable catalyst. In addition to diphenylamine, other suitable diarylamine reactants include dinaphthyl amines; p-nitrodiphenylamine; 2,4-dinitrodiphenylamine; p-aminodiphenylamine; p-hydroxydiphenylamine; and the like. In addition to acetone, other useful ketone reactants include methylethylketone, diethylketone, monochloroacetone, dichloroacetone, and the like.
A preferred diarylamine-aliphatic ketone reaction product is obtained from the condensation reaction of diphenylamine and acetone (NAUGARD A, Uniroyal Chemical), for example, in accordance with the conditions described in U.S. Pat. No. 2,562,802. The commercial product is supplied as a light tan-green powder or as greenish brown flakes and has a melting range of 85xc2x0 to 95xc2x0 C.
A third class of suitable amines comprises the N,Nxe2x80x2hydrocarbon substituted p-phenylene diamines. The hydrocarbon substituent may be alkyl or aryl groups, which can be substituted or unsubstituted. As used herein, the term xe2x80x9calkyl,xe2x80x9d unless specifically described otherwise, is intended to include cycloalkyl. Representative materials are:
N-phenyl-Nxe2x80x2-cyclohexyl-p-phenylenediamine;
N-phenyl-Nxe2x80x2-sec-butyl-p-phenylenediamine;
N-phenyl-Nxe2x80x2-isopropyl-p-phenylenediamine;
N-phenyl-Nxe2x80x2-(1,3-dimethylbutyl)-p-phenylenediamine;
N,Nxe2x80x2-bis-(1,4-dimethylpentyl)-p-phenylenediamine;
N,Nxe2x80x2-diphenyl-p-phenylenediamine;
N,Nxe2x80x2-di-beta naphthyl-p-phenylenediamine; mixed diaryl-p-N,Nxe2x80x2-bis-(1-ethyl-3-methylpentyl)-p-phenylenediamines, and
N,Nxe2x80x2-bis-(1 methylheptyl)-p-phenylenediamine.
A fourth class of amine antioxidants comprises materials based on quinoline, especially, polymerized 1,2-dihydro-2,2,4-trimethylquinoline (Naugard Super Q, Uniroyal Chemical). Representative materials also include 6-dodecyl-2,2,4-trimethyl-1,2-dihydroquinoline; 6-ethoxy-2,2,4-trimethyl-1-2-dihydroquinoline, and the like.
Secondary amines that are especially preferred for use in the practice of the present invention are 4,4xe2x80x2-bis(xcex1,xcex1dimethylbenzyl)diphenylamine (Naugard 445, Uniroyal Chemical), octylated diphenylamine (Naugard Octamine, Uniroyal Chemical), polymerized 1,2-dihydro-2,2,4-trimethylquinoline (Naugard Super Q, Uniroyal Chemical) and p-(p-toluene-sulfonylamido)-diphenyl amine (Naugard SA, Uniroyal Chemical).
As an alternative, or in addition, to the foregoing secondary amines, material based upon an N,Nxe2x80x2-substituted oxamide, preferably possessing hindered phenol functionality, can be used. An especially preferred member of this class is 2,2xe2x80x2-oxamido-bis{ethyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)}propionate (Naugard XL-1, Uniroyal Chemical).
The lactones having a base structure of a 3-phenylbenzofuran-2-one that are employed in the blends of the present invention are of the structure
wherein
R1 and R2 are independently selected from the group consisting of hydrogen; chloro; hydroxy; C1-C25 alkyl; C7-C9-phenylalkyl; unsubstituted or C1-C4 alkyl-substituted phenyl; unsubstituted or C1-C4 alkyl-substituted C5-C8 cycloalkyl; C1-C18 alkoxy; C1-C18 alkylthio; C1-C4 alkylamino; di-(C1-C4 alkyl)amino; C1-C25 alkanoyloxy, C1-C25 alkanoylamino; C3-C25 alkenoyloxy; C3-C25 alkanoyloxy which is interrupted by oxygen, sulfur, or  greater than Nxe2x80x94R,; C6-C9 cycloalkylcarbonyloxy; benzoyloxy or C1-C12 alkyl-substituted benzoyloxy;
R8 is hydrogen or C1-C8 alkyl; and
R3 and R4 are independently selected from the group consisting of hydrogen, C1-C8 alkyl, C1-C4 alkoxy, halogen, a group
xe2x80x83in which n is 1 or 2, or a group
xe2x80x83in which the radicals A are independently selected from the group consisting of C1-C8 alkyl and C1-C8 alkoxy.
A particularly useful representative of these lactones is 5,7-di-t-butyl-3-(3,4,-dimethylphenyl)-3H-benzofuran-2-one, which is of the structure
This compound is commercially available from Ciba Specialties as HP 136.
The compounds can be prepared by methods described in U.S. Pat. No. 5,516,920, the disclosure of which is incorporated herein by reference. More specifically, such compounds can be made by reacting a phenol of the formula
with a mandelic acid derivative of the formula
at elevated temperature, preferably in the range of from about 130xc2x0 C. to about 200xc2x0 C., in the melt or in a solvent, under normal pressure or a slight vacuum.
Alternatively, a compound of the formula
an be reacted with a compound of the formula
at elevated temperature, preferably in the range of from about 70xc2x0 C. to about 200xc2x0 C., in the melt or in a solvent, under normal pressure or a slight vacuum, preferably in the presence of a catalyst, such as, a protonic acid, a Lewis acid, an aluminum silicate, an ion exchange resin, a zeolite, a naturally occurring sheet silicate, or a modified sheet silicate.
The combined amounts of the amine/oxamide derivative(s), hindered phenol(s), and lactone(s) incorporated into the thermoplastic resins of the present invention, which may contain glass and/or carbon black, will at a minimum be that required to impart a significant level of stability against oxidative degradation. In general, such amounts can vary from about 0.01 to about 10.0 weight percent, and preferably from about 0.2 to about 5 weight percent, of the thermoplastic resin blend. Although combined amounts of the antioxidants in excess of about 10 weight percent can be employed, such amounts may have a deleterious effect on the physical and mechanical properties of the polymeric substrate, in which case they should ordinarily be avoided.
For the blends of secondary aromatic amines, sterically hindered phenols, and lactones, the lactone is added in a synergistic amount. The relative proportions of secondary aromatic amine to sterically hindered phenol to lactone can vary widely. In general, the ratios of secondary aromatic amine:sterically hindered phenol:lactone may be any ratio between 100:100:1 and 0.01:0.01:1. A preferred range is from 20:20:1 to 0.1:0.1:1. Additionally, two or more secondary aromatic amines, two or more sterically hindered phenols, and/or two or more lactones may be blended together in any ratio to make the secondary aromatic amine/sterically hindered phenol/lactone blend.
Preferred secondary aromatic amine/sterically hindered phenol/lactone blends are blends of 4,4xe2x80x2-bis(xcex1,xcex1-dimethylbenzyl) diphenylamine with either octadecyl 3,5-di-t-butyl-4-hydroxy-hydrocinnarnate, tetrakis{(methylene (3,5-di-t-butyl-4-hydroxyhydrocinnamate)}methane, or 2,2xe2x80x2-oxamido bis{ethyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)}propionate with 5,7-di-t-butyl-3-(3,4-dimethylphenyl)-3H-benzofuran-2-one; blends of polymerized 1,2-dihydro-2,2,4-trimethylquinoline with either octadecyl 3,5-di-t-butyl-4-hydroxyhydrocinnamate, tetrakis{methylene(3,5-di-t-butyl-4-hydroxyhydrocinnamate)}methane, or 2,2xe2x80x2-oxamido bis{ethyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)}propionate with 5,7-di-t-butyl-3-(3,4-dimethylphenyl)-3H-benzofuran-2-one; and blends of p-(p-toluenesulfonylamido)-diphenylamine with either octadecyl 3,5-di-t-butyl-4-hydroxyhydrocinnamate, tetrakis{methylene(3,5-di-t-butyl-4-hydroxyhydrocinnamate)}methane, or 2,2xe2x80x2-oxamido bis{ethyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)}propionate with 5,7-di-t-butyl-3-(3,4-dimethylphenyl)-3H-benzofuran-2-one.
As described above, it is possible to employ an antioxidant in the practice of the present invention that has both secondary aromatic amine/oxamide and hindered phenol functionality. Where this is done, such a difunctional antioxidant can take the place of either the secondary aromatic amine and/or N,Nxe2x80x2-substituted oxamide antioxidant of the invention or the hindered phenol of the invention, but not both. Thus, the proportions described in the preceding paragraph will still apply.
If desired, glass can be present in the thermoplastic resin employed in the practice of the present invention in an amount of up to about 50 percent by weight of the thermoplastic resin. Preferably, when glass is present, it will be in an amount ranging from about 5 to about 50 percent by weight, more preferably from about 20 to about 40 percent by weight.
If desired, carbon black can be present in the thermoplastic resin in an amount up to about 10 percent by weight of the thermoplastic resin. It is preferably present in an amount ranging from about 0.01 to about 10 percent by weight and, more preferably, in an amount ranging from about 0.1 to about 5 percent by weight.
The procedures employed to incorporate the amine/oxamide derivative(s), the hindered phenol(s), and the lactone(s) into the thermoplastic resins are not critical and, in general, follow any of the known procedures for incorporating additives into such resins. For example, these materials can be introduced into the thermoplastic resin as a premix or they can be maintained separately and added to the resin simultaneously or sequentially and then homogeneously distributed throughout the polymer by milling, extrusion blending, or some other mechanical working procedure. Either the first, the second, or the third stabilizer, or two of the foregoing, or all three can be added to the thermoplastic resin by way of a preconcentrate or in a carrier system, for example, in a suitable solvent or cosolvent.
Following common practice, other additives can be introduced-into the resin prior to, during, and/or following addition of the antioxidants. Such additives include other stabilizers, colorants, reinforcements, fillers, antistatic agents, lubricants, plasticizers, and the like, present in the customary amounts.

Thermoplastic resins stabilized by blends of sterically hindered phenols, secondary amines, and lactones

Abstract: A composition is disclosed comprising:

Abstract: (A) a thermoplastic resin; and

Abstract: (B) a stabilizing amount of a blend of at least one sterically hindered phenol antioxidant, at least one aromatic amine and/or N,Nxe2x80x2-substituted oxamide antioxidant, and at least one lactone antioxidant having a 3-phenylbenzofuran-2-one structure.

Abstract: A method is also disclosed for stabilizing a thermoplastic resin, wherein the method comprises adding thereto a stabilizing amount of a blend of at least one sterically hindered phenol antioxidant, at least one aromatic amines and/or N,Nxe2x80x2-substituted oxamide antioxidant, and at least one lactone antioxidant having a 3-phenylbenzofuran-2-one structure.


A method and apparatus is provided for controlling the effect of centrifugal force on pulp stock while being ground in the grinding space of a defibrating apparatus. The grinding space includes a central portion, a first grinding zone defined between first and second rotatable grinding discs and extending outwards from the central portion, and a second grinding zone extending angularly from the outer end of the first grinding zone and being defined between one of the rotatable grinding discs and a stationary grinding surface. Pulp stock to be ground is introduced into the central portion and accelerated through the first and second grinding zones by centrifugal force generated by the rotating discs. The angular second grinding zone serves to retard centrifugal force acting on the pulp in the second grinding zone to increase the dwell time of the pulp in the grinding space for achieving optimum refining efficiency.

In the refining process to which the grinding discs according to the invention are particularly applicable, the pulp stock or grist is ground in a grinding space defined between a pair of discs which rotate relative to one another in an environment of fluid medium. Each disc comprises disc segments disposed annularly about the discs and is provided with ridges and grooves which shear the fibers of the grist in grinding-like fashion. The pulp material, which may consist of wood chips, bagasse, fiber pulp or similar fibrous material, is fed by a screw feeder or the like through an opening in the central portion of one of the grinding discs into the "eye" of the grinding space and from which it is propelled by the centrifugal force generated by the rotational movement of the discs towards their periphery, where the grist is ejected with greatly accelerated force into the surrounding casing.
In order to generate the necessary centrifugal force to accelerate the stock from the inner central portion of the grinding space radially outwards and to obtain the desired degree of defibration and operating capacity in the grinding space, a high rotational speed must be imparted to the discs, such as on the order of 1500 r.p.m. to 3600 r.p.m.. However, the resultant relatively high centrifugal force required to accelerate the stock from the inner disc portion, which determines the capacity of the apparatus, concommitantly subjects the grist as it progresses radially outwards to the outer disc portion to a progressively intensified centrifugal force. This intensified centrifugal force will accelerate the outward radial speed of the grist to such a degree that, unless special measures are taken to hold back the grist in the outer disc portion, the grist will be ejected prematurely from the grinding space, in only partly-treated condition, with consequent impairment of the defibration efficiency of the grinding apparatus. This problem becomes even more accentuated when steam or other vapor is generated during the grinding operation, as the result of high power input or dryness of the grist. The steam or other vapor will then flow with the grist outward through the grinding space between the discs and further accelerate the radial flow of the grist. As the centrifugal acceleration exerted on the grist is proportional to the disc diameter, as well as to the square of the r.p.m. of the disc, according to Newton's law of force and motion, the larger the diameter of the disc in the apparatus, the greater will be the problem of controlling the flow of the grist through the outer portion of the grinding space. Depending on application and capacity demand, grinding apparatuses used today normally have a disc diameter ranging between 20" and 64". Even if the larger diameter discs should be rotated at relatively slow speeds varying between 900 r.p.m. and 1800 r.p.m., they will still produce a centrifugal force of acceleration on the grist in the order of 700 g's to 2800 g's. Assume, for example, that a disc rotating at 900 r.p.m. generates a centrifugal force of 700 g's; if the r.p.m. should be increased to 1800 r.p.m., the centrifugal force will be increased by a factor of 4, thus generating an increased centrifugal force of 2800 g's.
While discs of large diameter are desirable for capacity reasons, they require large amounts of energy, which is partly wasted because of their high peripheral velocity and consequent intensified centrifugal force, which renders the peripheral portion of the grinding space substantially ineffective for defibrating purposes. In addition, the high peripheral velocity of these large discs creates a serious noise problem.
Because of increasing demand for large capacity defibration equipment with adequate refining efficiency, it has proved to be a problem in the industry to properly control the radial passage of the stock between the outer part of the opposed grinding disc segments so as to obtain maximum performance. It should be understood that, as the stock progresses through the radial passage, it migrates alternately between the grinding segments on the opposing discs, and the more work on the stock in a single pass, i.e., the longer the dwell time in the grinding space, the more efficient and economical becomes the refining process. Unless the stock flow is properly retarded, the movement of the pulp becomes too rapid, as explained herein, and the defibrating action is minimized. Heretofore, attempts have been made to retard the passage of the grist through the grinding space by arranging the ridges and grooves in the grinding segments so that they can serve additionally as flow retarders. Such attempts are exemplified by applicant's U.S. Pat. Nos. 3,674,217, dated July 4, 1972, and 3,974,471, dated Aug. 17, 1976; and U.S. Pat. No. 3,040,997 granted to Donald A. Borden on June 26, 1962, U.S. Pat. No. 3,125,306 to E. Kollberg et al and U.S. Pat. No. 1,091,654 to Hamachek.
While these ridges and grooves serve to retard the flow, they still do not provide full utilization of the entire working area of the grinding space, since the grooves or channels between the ridges are spread out over a greater area at the periphery than at the inner portion of the grinding space. Furthermore, they do not solve the problem associated with high peripheral velocity of the presently-used large-diameter discs.
Another attempt to solve the problem of controlling the flow is exemplified by U.S. Pat. No. 4,090,672 dated May 23, 1978, to Bo A. Ahrel. The primary object of that invention is to solve the problem created by the high pressure steam in the peripheral zone of the grinding space. In order to prevent the partly defiberized stock from being blown out from the peripheral grinding zone by the high velocity steam, Ahrel utilizes the centrifugal force to separate the stream and to open up an escape passage for the steam while retaining the steam-liberated stock between the opposing grinding surfaces.
Other examples of prior art are U.S. Pat. Nos. 1,098,325 1,226,032, 3,684,200 and 3,845,909; German Pat. No. 1,217,754 and Swedish Pat. No. 187,564.
My co-pending patent application Ser. No. 877,809 filed on Feb. 17, 1978, discloses a method and apparatus for controlling the effect of centrifugal force on pulp stock while being ground in the grinding space of a defibrating apparatus. The preferred embodiment discloses a grinding space defined between a first stationary grinding disc and a second rotatable grinding disc. The grinding space comprises a first grinding zone in a plane substantially perpendicular to the axis of rotation of the grinding discs, and a second grinding zone extending at an angle from the first grinding zone. The angle of the second grinding zone relative to the first grinding zone is calculated to retard the centrifugal force in the outer peripheral portion of the grinding discs, so as to cause the pulp stock to progress through the grinding space at a controlled rate of flow with full utilization of the entire working area of the grinding space and without any substantial fluid separation regardless of the dimension of the grinding discs.
The preferred embodiment of my co-pending application also discloses further control of the effect of centrifugal force on pulp stock by varying the degree of the angle between ridges and grooves of the opposing disc segments relative to the generatrix of the grinding space in the outer inclined grinding zone.

Method and apparatus for controlling the effect of the centrifugal force on the stock in pulp defibrating apparatus


A tramp metal separation device adapted to be removably inserted into a housing which directs pelletized raw material to an industrial machine and to separate tramp metal contaminants therefrom. A drawer frame having an outer face plate with a plurality of openings disposed therethrough is adapted to be removably inserted into the housing. A plurality of cylindrical magnets adapted to be inserted through the plurality of openings in the outer face plate are secured to a drawer plate. In one embodiment of the present invention, the at least one silicon-based O-ring disposed in a groove in on of the plates so as to form an air tight seal between the face plate and the magnetic drawer. Additionally, a plurality of silicon-based O-rings may be disposed in grooves on the inner surface of the openings so as to form a wiper mechanism to aid in removing particles from the magnets.

There are many devices which store or further process a supply of granular material in an industrial environment. Many devices, such as grain storage apparatus or pharmaceutical handling apparatus, are designed to simply direct a supply of granular material to containers for storage. Other devices, such as a variety of industrial fabricating devices, process the material to form a component therefrom. For example, a plastic injection molding machine typically accepts a supply of pelletized plastic material, melts the pellets, injects the resulting liquid plastic into a mold, and discharges a molded part after the part has formed and cooled.
The prior art with respect to devices which handle granular materials is best described by continuing the example with respect to a product-forming machine. In the past, it has been common to use an overhead hopper for feeding the granular pellets of raw material to the product-forming machines. A quantity of pellets is placed in a very large container, such as a self-contained feed hopper, positioned above and adjacent to the machine. This arrangement permits the pellets to be gravity fed continuously into the molding machine.
In this arrangement, all of the raw material in the overhead storage container is directed to the molding machine. Frequently, the supply of raw material includes unwanted microscopic foreign metal material or foreign metal bodies, in the form of metal fragments, screws, washers, or the like. Such unwanted metallic foreign contaminants are referred to as "tramp metals" in the industry. These contaminants may be found in the plastic materials as it comes from the manufacturer due to wear or flaws in the manufacturer's transportation, manufacturing, packaging or conveying machinery. Other metal contaminants may be introduced into the raw materials from operations associated with handling the material at the end manufacturing facility itself. In addition, the growing use of recycled plastic materials for molding purposes increases the frequency of contaminant occurrences in the raw material supplies. The process of reclaiming the recyclable plastics often results in unwanted metallic contaminants becoming intermixed with the recovered plastics as a result of poor separation techniques at material recycling facilities. Frequently, recycling houses process recyclable plastics by chopping them into pieces of suitable size for reuse in molding apparatus. These plastic pieces may contain minute metal contaminants, as well as imbedded metal brackets, screws, nuts, and so on.
The presence of these metallic contaminants in the raw materials being processed in product-forming machines is undesirable for a variety of reasons. Contaminants may actually damage an industrial machine or render the finished part unusable. Even if the part is properly formed, the customer may object to the presence of metal therein as it may cause unacceptable structural, visual, or magnetic aberrations in the finished part.
Magnetic separators have been installed at the feed side of such industrial processing equipment to insure that metallic contaminants are removed. A magnetic separator typically comprises a housing component which acts as an intermediate hopper adapted to be placed above the forming machinery for the infeed of raw materials. A plurality of magnets form a magnetic drawer adapted to be removably inserted and secured in place in the feed path of this housing. As the granular material feeds through the housing, the metallic particles are attracted to the magnets. Periodically, the drawer is removed and the metallic materials are physically cleared from the magnets. The drawer is then reinserted into the housing for additional service.
Existing separator systems typically seal the mating surfaces between the housing and the separator drawer with an open cell foam gasket. The punishing environment in which this equipment operates results in rapid deterioration of such gasket materials. This deterioration turns the gasket itself into a contaminant which may enter the housing, and ultimately, contaminates the material being processed.
Further, overhead hopper configurations have recently fallen out of favor because of the difficulties encountered in changing the overhead supply hopper when a change in raw material composition is needed. The hoppers are difficult to transport and manipulate since they may weigh several hundred pounds when loaded with raw material. To overcome these problems with overhead or gravity feed hopper systems, a vacuum-feed system has been developed to supply the raw granular material from a container disposed adjacent to the processing machine. Materials are drawn from the container by operation of a vacuum applied thereto and fed into the processing machine. Materials can be changed by merely redirecting the vacuum between supply containers at ground level.
In this new vacuum-feed environment, metallic foreign matter is quite easily drawn into the processing equipment with the raw material, making the use of a separator a virtual necessity. However, the open cell foam gaskets of conventional magnetic separators provide a very poor seal which prevents the machinery from operating properly in a vacuum fed manner.
Therefore, a need exists for a magnetic tramp metal separator for removing tramp metal from equipment utilizing non-metallic granular materials which resists deterioration during use and may be used with vacuum feed equipment. This need exists with respect to product-forming machines, granular handling equipment, and most other devices which handle granular materials.