A medical device includes a catheter and a stent mounted on the catheter, the stent having a hollow, cylindrical body made with a plurality of rings. The rings each extend circumferentially around the cylindrical body and include an undulating series of peaks and valleys. The rings are joined together by a series of links which are shaped and arranged to promote longitudinal flexibility as the stent is delivered on the catheter and effective scaffolding after deployment. In one aspect of the invention, the rings are provided with inflection points on some portions of the rings which extend in a generally circumferential direction for a short distance. A link is joined at one end at the inflection point on one ring and also joined at a second end at a second inflection point on an adjacent ring. This construction allows the crimped stent to flex longitudinally when it is subjected to bending forces such as those encountered during delivery of the stent and catheter through a tortuous coronary artery.

This invention relates to intraluminal endovascular stenting, a method by which a prosthesis is inserted into a body tube and expanded so as to reopen a collapsed vessel wall and prevent the wall from recollapsing into the lumen. Endovascular stenting is particularly useful for arteries which are blocked or narrowed and is an alternative to surgical procedures that intend to bypass the occlusion.
Percutaneous transluminal coronary angioplasty (PTCA) is used to open coronary arteries which have been occluded by a build-up of cholesterol fats or atherosclerotic plaque. Typically a guidewire is steered through the vascular system to the site of therapy. A guiding catheter, for example, can then be advanced over the guidewire and a balloon catheter advanced within the guiding catheter over the guidewire. The balloon at the distal end of the catheter is inflated causing the site of the stenosis to widen. The dilatation of the occlusion, however, can form flaps, fissures and dissections which threaten re-closure of the dilated vessel or even perforations in the vessel wall. Implantation of a metal stent can provide support for such flaps and dissections and thereby prevent reclosure of the vessel or provide a patch repair for a perforated vessel wall until corrective surgery can be performed. Reducing the possibility of restenosis after angioplasty reduces the likelihood that a secondary angioplasty procedure or a surgical bypass operation will be necessary.
An implanted prosthesis such as a stent can preclude additional procedures and maintain vascular patency by mechanically supporting dilated vessels to prevent vessel collapse. Stents can also be used to repair aneurysms, to support artificial vessels as liners of vessels or to repair dissections. Stents are suited to the treatment of any body lumen, including the vas deferens, ducts of the gallbladder, prostate gland, trachea, bronchus and liver. The body lumens range in size from 1.5 mm in the coronary vessels to 30 mm in the aortic vessel.
A stent typically is a cylindrically shaped device formed from wire(s)or a tube and intended to act as a permanent prosthesis. A stent is deployed in a body lumen from a radially compressed configuration into a radially expanded configuration which allows it to contact and support a body lumen. The stent can be made to be radially self-expanding or expandable by the use of an expansion device. The self expanding stent is made from a resilient springy material while the device expandable stent is made from a material which is plastically deformable. A plastically deformable stent can be implanted during an angioplasty procedure by using a balloon catheter bearing a stent which has been crimped onto the balloon. Stents radially expand as the balloon is inflated, forcing the stent into contact with the body lumen thereby forming a supporting relationship with the vessel walls. Deployment is effected after the stent has been introduced percutaneously, transported transluminally and positioned at a desired location by means of the balloon catheter.
A balloon of appropriate size and pressure is first used to open the lesion. The process is repeated with a stent crimped on a balloon. The stent is deployed when the balloon is inflated. The stent remains as a permanent scaffold after the balloon is withdrawn. A balloon capable of withstanding relatively high inflation pressures may be preferable for stent deployment because the stent must be forced against the artery""s interior wall so that it will fully expand thereby precluding the ends of the stent from hanging down into the channel encouraging the formation of thrombus.
Previous structures used as stents or intraluminal vascular grafts have included coiled stainless steel springs; helical wound spring coil made from shape memory alloy; expanding metal stents formed in a zig-zag pattern; diamond shaped, rectangular shaped, and other mesh and non-mesh designs. Exemplary stent devices are disclosed in U.S. Pat. No. 5,776,161 issued to Globerman, U.S. Pat. No. 5,449,373 issued to Pinchasik et al, U.S. Pat. No. 5,643,312 issued to Fischell et al and U.S. Pat. No. 5,421,955 issued to Lau et al.
Problems to be overcome in stent design include inadequate radial force to maintain expansion; inadequate scaffolding of tissue to the wall; pre-dilated longitudinal rigidity which negatively impacts on stent delivery; and shortening of the stent as a consequence of radial expansion. Predilation stent longitudinal rigidity is a significant shortcoming, and prevents the threading of the stent through long tortuous vessels and lesions. Shortening of the stent is also a problem, as it is important that the stent cover the entire lesion to minimize the risk of post-operative complications. Many of these problems are the result of difficult design problems resulting from the often conflicting goals of stent design. For example, it is desirable to have a high degree of scaffolding in the stent when the stent is expanded to its rated radial size so that the vessel wall will have uniform support. However, it is also desirable to have a small, relatively smooth delivered profile when the stent is mounted on the catheter to permit the stent and catheter to traverse small diameter lesions. The person skilled in the art will appreciate that as a stent with a very small delivered profile expands radially its structural elements become farther apart and create openings which reduce the amount of scaffolding available to support the vessel. A similar situation exists with respect to the conflicting goals of improved scaffolding and flexibility during catheter delivery since proper scaffolding will not be accomplished if there are few supporting structural elements and yet a stent with too many structural elements may be difficult to crimp onto the balloon catheter such that the structural elements will not abut or interfere with each other during delivery through tortuous vessels. Also, in some stents, during plastic deformation of the stent (i.e. balloon expansion) the strain is concentrated at small zones. This limits the properties of the material that can be used as well as the radial force and the expansion rate.
U.S. Pat. No. 5,776,161 issued to Globerman, which is incorporated by reference herein in its entirety, addresses a number of these issues. Globerman discloses an expandable stent having a small initial diameter, flexibility along its longitudinal axis prior to expansion and minimization of rigid local strain on the stent material by the presence of rotation joints which have minimal strain during stent expansion. The stent is substantially the same length before and after expansion and being flexible longitudinally when constrained, it is easy to deliver. However additional improvements in longitudinal flexibility in the crimped stent during delivery and scaffolding after delivery are still desired.
These and other objects are accomplished by the present invention. The medical device of the present invention includes a catheter and a stent mounted on the catheter, the stent having a hollow, cylindrical body made with a plurality of rings. The rings each extend circumferentially around the cylindrical body and include an undulating series of peaks and valleys. Typically, the undulating peaks and valleys of the rings are formed by opposing curved segments joined to each other by substantially straight segments. The rings are joined together by a series of links which are shaped and arranged to promote longitudinal flexibility as the stent is delivered on the catheter and effective scaffolding after deployment and to prevent shortening of the stent as the stent is expanded.
In one aspect of the invention, the rings are provided with inflection points on some portions of the rings which extend between an adjacent peak and valley of the ring. At each inflection point, a portion of the ring extends in a generally circumferential direction for a short distance. Typically, the inflection point is substantially centered between a peak and a valley of the ring. A link is joined at one end at the inflection point on one ring and also joined at a second end at a second inflection point on an adjacent ring. This link joins the rings together. Preferably, the link includes at least two curved segments in the unexpanded device which are capable of deflecting to promote the tendency of the stent to flex longitudinally when it is subjected to bending forces such as those encountered during delivery of the stent and catheter through a tortuous coronary artery. Also preferably, the short portion of the ring at the inflection point which extends generally circumferentially has a length measured circumferentially which is at least as great as the width of the link to which it is attached. Preferably, the circumferential length is no more than about twice the width of the link to which it is attached. This promotes the scaffolding provided to the vessel by the expanded stent since the links can be fit together closely in a nested arrangement with the undulations of the rings as the stent is crimped on the balloon catheter. By xe2x80x9cnestxe2x80x9d, xe2x80x9cnestedxe2x80x9d or nestingxe2x80x9d herein we mean that the elements are conformally arranged such they can be in very close proximity when the stent is crimped onto the catheter but without substantial contact that would affect the ability of the various elements to move in relation to each other as the stent and catheter are advanced through a tortuous body vessel. Where the undulations of the ring include generally straight segments between the peaks and valleys, the straight segments may be interrupted by an inflection point which produces a offset portion in the straight segment in a generally circumferential direction. In some preferred embodiments of the invention, no more than one link is connected to either of the first and second inflection points. This makes the inflection point a xe2x80x9cdead endxe2x80x9d in the longitudinal extent of the connecting links for the stent and permits some of the flexing forces which are not absorbed by the link itself to be absorbed by the rings to which it is attached. The links can be arranged to provide flexibility whether the peaks and valleys of the rings are arranged to make the rings appear to be mirror images to each other (i.e. peaks line up with or closely approach each other) or whether the peaks and valleys are paired with each other in an in-phase relationship or any alignment of the rings intermediate to those positions. Preferably, the rings are joined by multiple links (most preferably 3 or more) and have the same number of inflection points on each ring as the number of attaching links. When a large number of connecting links are employed, any curves or bends in the links are preferably of a complimentary shape to each other such that they will nest together when the stent is crimped onto the catheter.
Another aspect of the invention is the conformal nesting of ring and link components such that the stent can be readily crimped onto a balloon or other expansion device on the catheter. The stent made according to the present invention may be made from a tube which is cut with lasers or other techniques which are well known to those skilled in the art. The initial pattern cut into the tube includes link and ring components which cooperate with each other but which provide sufficient spacing between components that the stent can be crimped onto a catheter without causing general abutment of the ring and link components with each other and also permit longitudinal movement of the link components without disturbing the crimp of the ring components on the catheter during deployment of the stent through tortuous coronary arteries. The need for spacing between the components in the crimped condition must be balanced with the need to provide improved scaffolding of the vessel being treated. A relatively abundant number of links provides improved scaffolding of the vessel but potentially interferes with the ability to crimp the stent onto the catheter. In the present invention, the inflection points can provide the spacing needed for the nesting of the ring and link components by extending the ring in a generally circumferential direction for a distance which is sufficient to accommodate the width of the link component and provide space needed between the link components and the ring components which allows the stent to be crimped onto the catheter. In some embodiments of the invention, each inflection point includes an attachment to two connecting links extending in opposing directions and the circumferential offset at the inflection point provides for nesting of both connecting links with the ring components on the opposite sides. Thus, in the present invention, large numbers of connecting links can be included within a crimpable stent design.
Another aspect of the invention is to provide flexibility in the stent crimped on the catheter such that the stent can flex near the inflection points without significant radial expansion as the stent is subjected to bending along a longitudinal axis as it is advanced through bends in a coronary artery. As stents are advanced through tortuosities of a vessel, they are subjected to bending forces which can produce longitudinal stresses on the connector links. If the movement of connector links pulls the undulations open from their crimped position, the stent can become radially enlarged and have difficulty in crossing a narrow lesion. The present invention reduces the potential for this problem by aligning the connection of the links with the rings at a short, circumferentially extending portion, by providing curvature in the links which are then able to flex and thereby reduce stress on the junctions between the rings and the links and by providing xe2x80x9cdead endxe2x80x9d connections with the links which then avoids the transmission of forces from ring to ring throughout the length of the stent.
Yet another aspect of the invention is in connection with the stent configuration in which the undulating peaks and valleys of the rings are oriented such that the rings have peaks and valleys which are paired with each other in an in-phase relationship. In such a configuration, a link can be provided which interconnects with the rings at points on the rings which are substantially centered between the respective peaks and valleys of the rings and yet allows the link to nest within the peaks and valleys of the rings. This can be accomplished by providing at least two curved segments in the link in a central portion of the link.
Yet another aspect of the invention is in connection with the stent configuration in which the undulating peaks and valleys of the first ring are arranged with the undulating peaks and valleys of the second ring such that the first and second rings appear as mirror images of each other. In such a configuration, a link can be provided which interconnects with the rings at points on the rings which are substantially centered between the respective peaks and valleys of the rings and yet allows the link to nest within the peaks and valleys of the rings. This can be accomplished by providing a link including a sharp radius segment at each end and a gently curved central segment.

Medical device for intraluminal endovascular stenting


In alternative embodiments, provided are compositions, including products of manufacture and kits, and methods, for treating or ameliorating a cancer by inhibiting expression or activity of Mouse Double Minute 2 homolog (MDM2), an APOBEC3G (A3G) protein, message (mRNA) or gene, and/or an ADAR1p150 protein, message (mRNA) or gene, e.g., by increasing the presence of in a cell or adding to a cell a molecule inhibitory to MDM2, APOBEC3G and/or ADAR1p150 expression, such as an miRNA that binds to MDM2, APOBEC3G and/or ADAR1p150 transcripts, or any molecule that can inhibit or destabilize the transcripts, resulting in decreased MDM2, APOBEC3G and/or ADAR1p150 expression, to treat a cancer such as leukemia, e.g., by inhibiting the propagation of a cancer cell, a leukemia cell, a leukemia stem cell (LSC) or a pre-leukemia cell stem cell (pre-LSC).

Mouse Double Minute 2 homolog (MDM2), also known as E3 ubiquitin-protein ligase Mdm2, is a protein that in humans is encoded by the MDM2 gene. MDM2 is an important negative regulator of the p53 tumor suppressor. MDM2 protein functions both as an E3 ubiquitin ligase that recognizes the N-terminal trans-activation domain (TAD) of the p53 tumor suppressor and as an inhibitor of p53 transcriptional activation.

Anticancer compositions and methods for making and using them

The Regents of the University of California


The invention relates to thermoplastic molding compound that contain A) 1 to 97.85% by weight of at least one thermoplastic polyester, B) 1 to 97.85% by weight of at least one polycarbonate, C) 1 to 50% by weight of a rubber-elastic polymer, D) 0.1 to 5% by weight of a phosphorous stabilizer, E) 0.05 to 2% by weight of an organic acid, F) 0 to 60% by weight of further additives. The weight percentages of the components A) to F) add up to 100%.

The invention relates to thermoplastic molding compositions comprising
A) from 1 to 97.85% by weight of at least one thermoplastic polyester,
B) from 1 to 97.85% by weight of at least one polycarbonate,
C) from 1 to 50% by weight of an elastomeric polymer,
D) from 0.1 to 5% by weight of a phosphorus-containing stabilizer,
E) from 0.05 to 2% by weight of an organic acid, and
F) from 0 to 60% by weight of other additives,
where the percentages by weight of components A) to F) give 100%.
The invention further relates to the use of the novel molding compositions for producing fibers, films or moldings, and also to the resultant moldings of any type.
Industry is increasingly interested in polymer mixtures, since they provide tailored combinations of properties. Of particular interest here are polymer mixtures made from incompatible polymers which have unusual combinations of properties.
Polymer mixtures based on polyesters and polycarbonates are known (U.S. Pat. Nos. 4,522,797, 4,764,556, 4,897,448, EP-A 180 648, DE-A 3302124). Industrially significant products also have impact modifiers present to improve toughness, in particular at low temperatures, and preferred modifiers here are MBS modifier, acrylate graft rubbers and also ethylene copolymers with polar comonomers.
J. Devaux, P. Godard, J. P. Mercier, Polym. Eng. Sci., 22, 229 (1982) has disclosed that catalyst residues present in the polyester cause transesterification during melt compounding with polycarbonate. This gives copolymers, which improve the mechanical properties of the resultant blends. However, at high processing temperatures the transesterification is so rapid that there is substantial impairment of the mechanical and thermal properties of the resultant moldings. In addition, molding compositions prepared at high processing temperatures have poor surface quality (streaks and discoloration).
A wide variety of experiments has also been undertaken to improve the processing stability of polyester/polycarbonate blends. For example, EP-A 114 288 describes polyester/polycarbonate blends in which the MBS rubber added is premixed with a stabilizer in a prior step. This measure improves the mechanical properties of the molding compositions. However, the stability of the molding compositions at relatively high processing temperatures is unsatisfactory.
EP-A 634 435 describes a catalyst mixture composed of a Ti compound and a phosphorus compound which can be used to prepare polyesters. Polyesters prepared in this way have a slightly reduced tendency to transesterify in blends with polycarbonate.
U.S. Pat. No. 4,452,932 proposes, for example, ortho-substituted aromatic hydroxyl compounds to protect polycarbonate/polybutylene terephthalate blends from transesterification.
DE-A 19900891 proposes a process for premixing phosphonites with polyesters to improve processing stability.
EP-A 256 461 describes molding compositions based on polycarbonate and polyesters, which comprise small amounts of sulfonic acids. Although the products have improved toughness, processing stability is inadequate.
In particular when large-surface-area parts are produced, the long flow paths continue to cause processing problems since the blends known hitherto do not have sufficient stabilization.
It is an object of the present invention to provide polyester-polycarbonate blends which have improved processing stability and mechanical properties. In particular, heat resistance and melt stability for long cycle times should be improved.
We have found that this object is achieved by means of the thermoplastic molding compositions defined at the outset. Preferred embodiments are given in the subclaims.
The novel molding compositions comprise, as component (A), from 5 to 97.85% by weight, preferably from 10 to 92.7% and in particular from 12.5 to 89.85% by weight, of a thermoplastic polyester.
Use is generally made of polyesters A) based on aromatic dicarboxylic acids and on an aliphatic or aromatic dihydroxy compound.
A first group of preferred polyesters is that of polyalkylene terephthalates whose alcohol moiety has from 2 to 10 carbon atoms.
Polyalkylene terephthalates of this type are known per se and are described in the literature. Their main chain contains an aromatic ring which derives from the aromatic dicarboxylic acid. There may also be substitution of the aromatic ring, e.g. by halogen, such as chlorine or bromine, or by C1-C4-alkyl, such as methyl, ethyl, iso- or n-propyl, or n-, iso- or tert-butyl.
These polyalkylene terephthalates may be prepared by reacting aromatic dicarboxylic acids, or their esters or other ester-forming derivatives, with aliphatic dihydroxy compounds in a manner known per se.
Preferred dicarboxylic acids are 2,6-naphthalenedicarboxylic acid, terephthalic acid and isophthalic acid, and mixtures of these. Up to 30 mol %, preferably not more than 10 mol %, of the aromatic dicarboxylic acids may be replaced by aliphatic or cycloaliphatic dicarboxylic acids, such as adipic acid, azelaic acid, sebacic acid, dodecanedioic acids and cyclohexanedicarboxylic acids.
Preferred aliphatic dihydroxy compounds are diols having from 2 to 6 carbon atoms, in particular 1,2-ethanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,4-hexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol and neopentyl glycol, and mixtures of these.
Particularly preferred polyesters (A) are polyalkylene terephthalates derived from alkanediols having from 2 to 6 carbon atoms. Among these, particular preference is given to polyethylene terephthalate, polypropylene terephthalate and polybutylene terephthalate, and mixtures of these. Preference is also given to PET and/or PBT which comprise, as other monomer units, up to 1% by weight, preferably up to 0.75% by weight, of 1,6-hexanediol and/or 2-methyl-1,5-pentanediol.
The viscosity number of the polyesters (A) is generally in the range from 50 to 220, preferably from 80 to 160 (measured in a 0.5% strength by weight solution in a phenol/o-dichlorobenzene mixture in a weight ratio of 1:1 at 25xc2x0 C. in accordance with ISO 1628.
Particular preference is given to polyesters whose carboxyl end group content is up to 100 mval/kg of polyester, preferably up to 50 mval/kg of polyester and in particular up to 40 mval/kg of polyester. Polyesters of this type may be prepared, for example, by the process of DE-A 44 01 055. The carboxyl end group content is usually determined by titration methods (e.g. potentiometry).
Particularly preferred molding compositions comprise, as component A), a mixture of polyesters which are different from PBT, for example polyethylene terephthalate (PET). The proportion e.g. of the polyethylene terephthalate in the mixture is preferably up to 50% by weight, in particular from 10 to 30% by weight, based on 100% by weight of A).
It is also advantageous to use recycled PET materials (also termed scrap PET), if desired in a mixture with polyalkylene terephthalates, such as PBT.
Recycled materials are generally:
1) those known as post-industrial recycled materials: these are production wastes during polycondensation or during processing, e.g. sprues from injection molding, start-up material from injection molding or extrusion, or edge trims from extruded sheets or films.
2) post-consumer recycled materials: these are plastic items which are collected and treated after utilization by the end consumer. Blow-molded PET bottles for mineral water, soft drinks and juices are easily the predominant items in terms of quantity.
Both types of recycled material may be used either as ground material or in the form of pellets. In the latter case, the crude recycled materials are isolated and purified and then melted and pelletized using an extruder. This usually facilitates handling and free flow, and metering for further steps in processing.
The recycled materials used may either be pelletized or in the form of regrind. The edge length should not be more than 6 mm, preferably less than 5 mm.
Because polyesters undergo hydrolytic cleavage during processing (due to traces of moisture) it is advisable to predry the recycled material. The residual moisture after drying is preferably from 0.01 to 0.7%, in particular from 0.2 to 0.6%.
Another group to be mentioned is that of fully aromatic polyesters deriving from aromatic dicarboxylic acids and aromatic dihydroxy compounds.
Suitable aromatic dicarboxylic acids are the compounds previously mentioned for the polyalkylene terephthalates. The mixtures preferably used are made from 5 to 100 mol % of isophthalic acid and from 0 to 95 mol % of terephthalic acid, in particular from about 50 to about 80% of terephthalic acid and from 20 to about 50% of isophthalic acid.
The aromatic dihydroxy compounds preferably have the formula
where Z is alkylene or cycloalkylene having up to 8 carbon atoms, arylene having up to 12 carbon atoms, carbonyl, sulfonyl, oxygen or sulfur, or a chemical bond, and m is from 0 to 2. The phenylene groups of the compounds may also have substitution by C1-C6-alkyl or alkoxy and fluorine, chloride or bromine.
Examples of parent substances for these compounds are
dihydroxydiphenyl,
di(hydroxyphenyl)alkane,
di(hydroxyphenyl)cycloalkane,
di(hydroxyphenyl)sulfide,
di(hydroxyphenyl)ether,
di(hydroxyphenyl)ketone,
di(hydroxyphenyl)sulfoxide,
xcex1,xcex1xe2x80x2-di(hydroxyphenyl)dialkylbenzene,
di(hydroxyphenyl)sulfone, di(hydroxybenzoyl)benzene resorcinol and
hydroquinone and also the ring-alkylated and ring-halogenated derivatives of these.
Among these, preference is given to
4,4xe2x80x2-dihydroxydiphenyl,
2,4-di(4xe2x80x2-hydroxyphenyl)-2-methylbutane,
xcex1,xcex1xe2x80x2-di(4-hydroxyphenyl)-p-diisopropylbenzene,
2,2-di(3xe2x80x2-methyl-4xe2x80x2-hydroxyphenyl)propane and
2,2-di(3xe2x80x2-chloro-4xe2x80x2-hydroxyphenyl)propane,
and in particular to
2,2-di(4xe2x80x2-hydroxyphenyl)propane,
2,2-di(3xe2x80x2,5-dichlorodihydroxyphenyl)propane,
1,1-di(4xe2x80x2-hydroxyphenyl)cyclohexane,
3,4,xe2x80x2-dihydroxybenzophenone,
4,4,xe2x80x2-dihydroxydiphenylsulfone and
2,2-di(3xe2x80x2,5xe2x80x2-dimethyl-4xe2x80x2-hydroxyphenyl)propane
or mixtures of these.
It is, of course, also possible to use mixtures of polyalkylene terephthalates and fully aromatic polyesters. These generally comprise from 20 to 98% by weight of the polyalkylene terephthalate and from 2 to 80% by weight of the fully aromatic polyester.
It is, of course, also possible to use polyester block copolymers, such as copolyetheresters. Products of this type are known per se and are described in the literature, e.g. in U.S. Pat. No. 3,651,014. Corresponding products are also available commercially, e.g. Hytrel(copyright) (DuPont).
According to the invention, the molding compositions comprise, as component B), amounts of from 1 to 97.85% by weight, preferably from 5 to 87.7% by weight and in particular from 7.5 to 84.15% by weight, of at least one polycarbonate.
Halogen-free polycarbonates are preferably used as component B). Examples of suitable halogen-free polycarbonates are those based on biphenols of the formula
where Q is a single bond, C1-C8-alkylene, C2-C3-alkylidene, C3-C6-cycloalkylidene, C6-C12-arylene, or also xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94 or xe2x80x94SO2xe2x80x94, and m is an integer from 0 to 2.
The phenylene radicals of the biphenols may also have substituents, such as C1-C6-alkyl or C1-C6-alkoxy.
Examples of preferred biphenols of this formula are hydroquinone, resorcinol, 4,4xe2x80x2-dihydroxybiphenyl, 2,2-bis(4-hydroxyphenyl)propane, 2,4-bis(4-hydroxyphenyl)-2-methylbutane and 1,1-bis(4-hydroxyphenyl)cyclohexane. Particular preference is given to 2,2-bis(4-hydroxyphenyl)propane and 1,1-bis(4-hydroxyphenyl)cyclohexane, and also to 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane.
Either homopolycarbonates or copolycarbonates are suitable as component B, and preference is given to the copolycarbonates of bisphenol A, as well as to bisphenol A homopolymer.
Suitable polycarbonates may be branched in a known manner, specifically and preferably by incorporating from 0.05 to 2.0 mol %, based on the total of the biphenols used, of at least trifunctional compounds, for example those having three or more phenolic OH groups.
Polycarbonates which have proven particularly suitable have relative viscosities nrel of from 1.10 to 1.50, in particular from 1.25 to 1.40. This corresponds to an average molar mass MW (weight-average) of from 10,000 to 200,000 g/mol, preferably from 20,000 to 80,000 g/mol.
The biphenols of this formula are known per se or can be prepared by known processes.
The polycarbonates may, for example, be prepared by reacting the biphenols with phosgene in the interfacial process, or with phosgene in the homogeneous-phase process (known as the pyridine process), and in each case the desired molecular weight is achieved in a known manner by using an appropriate amount of known chain terminators. (In relation to polydiorganosiloxane-containing polycarbonates see, for example, DE-A 33 34 782).
Examples of suitable chain terminators are phenol, p-tert-butylphenol, or else long-chain alkylphenols, such as 4-(1,3-tetramethylbutyl)phenol as in DE-A 28 42 005, or monoalkylphenols, or dialkylphenols with a total of from 8 to 20 carbon atoms in the alkyl substituents as in DE-A 35 06 472, such as p-nonylphenyl, 3,5-di-tert-butylphenol, p-tert-octylphenol, p-dodecylphenol, 2-(3,5-dimethylheptyl)phenol and 4-(3,5-dimethylheptyl)phenol.
For the purposes of the present invention, halogen-free polycarbonates are polycarbonates made from halogen-free biphenols, from halogen-free chain terminators and, if desired, from halogen-free branching agents, where the content of subordinate amounts at the ppm level of hydrolyzable chlorine, resulting, for example, from the preparation of the polycarbonates with phosgene in the interfacial process, is not regarded as meriting the term halogen-containing for the purposes of the invention. Polycarbonates of this type with contents of hydrolyzable chlorine at the ppm level are halogen-free polycarbonates for the purposes of the present invention.
Other suitable components B) which may be mentioned are amorphous polyester carbonates, where phosgene has been replaced by aromatic dicarboxylic acid units, such as isophthalic acid and/or terephthalic acid units, during the preparation. For further details reference may be made at this point to EP-A 711,810.
EP-A 365 916 describes other suitable copolycarbonates having cycloalkyl monomer units.
It is also possible to replace bisphenol A with bisphenol TMC Polycarbonates of this type are commercially available from Bayer with the trade mark APEC HT(copyright).
The novel molding compositions comprise, as component C), from 1 to 50% by weight, preferably from 2 to 30% by weight and in particular from 3 to 25% by weight, of an elastomeric polymer (also frequently termed an impact modifier, elastomer or rubber).
These are very generally copolymers which have preferably been built up from at least two of the following monomers: ethylene, propylene, butadiene, isobutene, isoprene, chloroprene, vinyl acetate, styrene, acrylonitrile and acrylates and/or methacrylates having from 1 to 18 carbon atoms in the alcohol component.
Polymers of this type have been described, for example, in Houben-Weyl, Methoden der organischen Chemie, Vol. 14/1 (Georg-Thieme-Verlag, Stuttgart, 1961), pages 392-406, and in the monograph by C. B. Bucknall, xe2x80x9cToughened Plasticsxe2x80x9d (Applied Science Publishers, London, 1977).
Some preferred types of such elastomers are described below.
Preferred types of such elastomers are those known as ethylene-propylene (EPM) and ethylene-propylene-diene (EPDM) rubbers.
EPM rubbers generally have practically no residual double bonds, whereas EPDM rubbers may have from 1 to 20 double bonds per 100 carbon atoms.
Examples which may be mentioned of diene monomers for EPDM rubbers are conjugated dienes, such as isoprene and butadiene, non-conjugated dienes having from 5 to 25 carbon atoms, such as 1,4-pentadiene, 1,4-hexadiene, 1,5-hexadiene, 2,5-dimethyl-1,5-hexadiene and 1,4-octadiene, cyclic dienes, such as cyclopentadiene, cyclohexadienes, cyclooctadienes and dicyclopentadiene, and also alkenylnorbornenes, such as 5-ethylidene-2-norbornene, 5-butylidene-2-norbornene, 2-methallyl-5-norbornene and 2-isopropenyl-5-norbornene, and tricyclodienes, such as 3-methyltricyclo[5.2.1.02,6]-3,8-decadiene, or mixtures of these. Preference is given to 1,5-hexadiene, 5-ethylidenenorbornene and dicyclopentadiene. The diene content of the EPDM rubbers is preferably from 0.5 to 50% by weight, in particular from 1 to 8% by weight, based on the total weight of the rubber.
EPM and EPDM rubbers may preferably also have been grafted with reactive carboxylic acids or with derivatives of these. Examples of these are acrylic acid, methacrylic acid and derivatives thereof, e.g. glycidyl (meth)acrylate, and also maleic anhydride.
Polyolefin copolymers obtainable by polymerizing in the presence of a metallocene catalyst are also suitable.
Particularly preferred elastomers C) are polyethyleneoctene and polyethylenebutene copolymers with a proportion of up to 50% by weight, preferably up to 45% by weight, of octene and/or butene. Copolymers of ethylene with acrylic acid and/or methacrylic acid and/or with the esters of these acids are another group of preferred rubbers. The rubbers may also include dicarboxylic acids, such as maleic acid and fumaric acid, or derivatives of these acids, e.g. esters and anhydrides, and/or monomers containing epoxy groups. These monomers containing dicarboxylic acid derivatives or containing epoxy groups are preferably incorporated into the rubber by adding to the monomer mixture monomers containing dicarboxylic acid groups and/or epoxy groups and having the formula I, II, III or IV
where R1 to R9 are hydrogen or alkyl having from 1 to 6 carbon atoms, and m is an integer from 0 to 20, g is an integer from 0 to 10 and p is an integer from 0 to 5.
R1 to R9 are preferably hydrogen, where m is 0 or 1 and g is 1. The corresponding compounds are maleic acid, fumaric acid, maleic anhydride, allyl glycidyl ether and vinyl glycidyl ether.
Preferred compounds of the formulae I, II and IV are maleic acid, maleic anhydride and (meth)acrylates containing epoxy groups, such as glycidyl acrylate and glycidyl methacrylate, and the esters with tertiary alcohols, such as tert-butyl acrylate. Although the latter have no free carboxyl groups their behavior approximates to that of the free acids and they are therefore termed monomers with latent carboxyl groups.
The copolymers are advantageously composed of from 50 to 98% by weight of ethylene, from 0.1 to 20% by weight of monomers containing epoxy groups and/or methacrylic acid and/or monomers containing anhydride groups, the remaining amount being (meth)acrylates.
Particular preference is given to copolymers composed of
from 50 to 98% by weight, in particular from 55 to 95% by weight, of ethylene,
from 0.1 to 40% by weight, in particular from 0.3 to 20% by weight, of glycidyl acrylate and/or glycidyl methacrylate, (meth)acrylic acid and/or maleic anhydride, and
from 1 to 45% by weight, in particular from 10 to 40% by weight, of n-butyl acrylate and/or 2-ethylhexyl acrylate.
Other preferred (meth)acrylates are the methyl, ethyl, propyl, isobutyl and tert-butyl esters.
Besides these, comonomers which may be used are vinyl esters and vinyl ethers.
The ethylene copolymers described above may be prepared by processes known per se, preferably by random copolymerization at high pressure and elevated temperature. Appropriate processes are well known.
Preferred elastomers also include emulsion polymers whose preparation is described, for example, by Blackley in the monograph xe2x80x9cEmulsion Polymerizationxe2x80x9d. The emulsifiers and catalysts which may be used are known per se.
In principle it is possible to use homogeneously structured elastomers or those with a shell structure. The shell-like structure is a function of the sequence of addition of the individual monomers. The morphology of the polymers is also affected by this sequence of addition.
Monomers which may be mentioned here, merely as examples, for the preparation of the rubber fraction of the elastomers are acrylates, such as n-butyl acrylate and 2-ethylhexyl acrylate, and corresponding methacrylates, and butadiene and isoprene, and also mixtures of these. These monomers may be copolymerized with other monomers, such as styrene, acrylonitrile, vinyl ethers and with other acrylates or methacrylates, such as methyl methacrylate, methyl acrylate, ethyl acrylate or propyl acrylate.
The soft or rubber phase (with a glass transition temperature below 0xc2x0 C.) of the elastomers may be the core, the outer envelope or an intermediate shell (in the case of elastomers whose structure has more than two shells). Elastomers having more than one shell may also have more than one shell made from a rubber phase.
If one or more hard components (with glass transition temperatures above 20xc2x0 C.) are involved, besides the rubber phase, in the structure of the elastomer, these are generally prepared by polymerizing, as principal monomers, styrene, acrylonitrile, methacrylonitrile, xcex1-methylstyrene, p-methylstyrene, or acrylates or methacrylates, such as methyl acrylate, ethyl acrylate or methyl methacrylate. Besides these, it is also possible to use relatively small proportions of other comonomers.
It has proven advantageous in some cases to use emulsion polymers which have reactive groups at their surfaces. Examples of groups of this type are epoxy, carboxyl, latent carboxyl, amino and amide groups, and also functional groups which may be introduced by concomitant use of monomers of the formula
where:
R10 is hydrogen or C1-C4-alkyl,
R11 is hydrogen or C1-C8-alkyl or aryl, in particular phenyl,
R12 is hydrogen, C1-C10-alkyl, C6-C12-aryl or xe2x80x94OR13,
R13 is C1-C8-alkyl or C6-C12-aryl, if desired with substitution by O- or N-containing groups,
X is a chemical bond or C1-C10-alkylene or C6-C12-arylene, or
Y is Oxe2x80x94Z or NHxe2x80x94Z, and
Z is C1-C10-alkylene or C6-C12-arylene.
The graft monomers described in EP-A 208 187 are also suitable for introducing reactive groups at the surface.
Other examples which may be mentioned are acrylamide, methacrylamide and substituted acrylates or methacrylates, such as (N-tert-butylamino)ethyl methacrylate, (N,N-dimethylamino)ethyl acrylate, (N,N-dimethylamino)methyl acrylate and (N,N-diethylamino)ethyl acrylate.
The particles of the rubber phase may also have been crosslinked. Examples of crosslinking monomers are 1,3-butadiene, divinylbenzene, diallyl phthalate and dihydrodicyclopentadienyl acrylate, and also the compounds described in EP-A 50 265.
It is also possible to use the monomers known as graft-linking monomers, i.e. monomers having two or more polymerizable double bonds which react at different rates during the polymerization. Preference is given to the use of compounds of this type in which at least one reactive group polymerizes at about the same rate as the other monomers, while the other reactive group (or reactive groups), for example, polymerize(s) significantly more slowly. The different polymerization rates give rise to a certain proportion of unsaturated double bonds in the rubber. If another phase is then grafted onto a rubber of this type, at least some of the double bonds present in the rubber react with the graft monomers to form chemical bonds, i.e. the phase grafted on has at least some degree of chemical bonding to the graft base.
Examples of graft-linking monomers of this type are monomers containing allyl groups, in particular allyl esters of ethylenically unsaturated carboxylic acids, for example allyl acrylate, allyl methacrylate, diallyl maleate, diallyl fumarate and diallyl itaconate, and the corresponding monoallyl compounds of these dicarboxylic acids. Besides these there is a wide variety of other suitable graft-linking monomers. For further details reference may be made here, for example, to U.S. Pat. No. 4,148,846.
The proportion of these crosslinking monomers in the impact-modifying polymer is generally up to 5% by weight, preferably not more than 3% by weight, based on the impact-modifying polymer.
Some preferred emulsion polymers are listed below. Mention is made firstly of graft polymers with a core and at least one outer shell and the following structure:
Instead of graft polymers whose structure has more than one shell it is also possible to use homogeneous, i.e. single-shell, elastomers made from 1,3-butadiene, isoprene and n-butyl acrylate or from copolymers of these. These products, too, may be prepared by concomitant use of crosslinking monomers or of monomers having reactive groups.
Examples of preferred emulsion polymers are n-butyl acrylate-(meth)acrylic acid copolymers, n-butyl acrylate-glycidyl acrylate or n-butyl acrylate-glycidyl methacrylate copolymers, graft polymers with an inner core made from n-butyl acrylate or based on butadiene and with an outer envelope made from the abovementioned copolymers, and copolymers of ethylene with comonomers which supply reactive groups.
The elastomers described may also be prepared by other conventional processes, e.g. by suspension polymerization.
Preference is likewise given to silicone rubbers, as described in DE-A 37 25 576, EP-A 235 690, DE-A 38 00 603 and EP-A 319 290.
It is, of course, also possible to use mixtures of the types of rubber listed above.
Suitable phosphorus-containing stabilizers D) are preferably organic phosphonites of the formula I
where
m is 0 or 1,
n is 0 or 1,
Y is an oxygen bridge, a sulfur bridge or a 1,4-phenylene bridge, or a bridging unit of the formula xe2x80x94CH(R2)xe2x80x94; each of the Rxe2x80x94Oxe2x80x94 and R1xe2x80x94O-groups, independently of one another, is the radical of an aliphatic, alicyclic or aromatic alcohol which may contain up to three hydroxyl groups, but excluding any arrangement of the hydroxyl groups which permits these to be part of a phosphorus-containing ring (termed monovalent Rxe2x80x94O-groups), or two Rxe2x80x94Oxe2x80x94 or, respectively, R1xe2x80x94O-groups, bonded to a phosphorus atom, in each case independently of one another, together are the radical of an aliphatic, alicyclic or aromatic alcohol having a total of up to three hydroxyl groups (termed bivalent Rxe2x80x94Oxe2x80x94, or, respectively, R1xe2x80x94O-groups),
R2 is hydrogen, C1-C8-alkyl or a group of the formula COOR3, and
R3 is C1-8-alkyl.
It is preferable for at least one Rxe2x80x94Oxe2x80x94 and at least one R1xe2x80x94O group to be a phenol radical which carries a sterically hindered group, in particular t-butyl, in the 2 position.
Particular preference is given to tetrakis(2,4-di-tert-butylphenyl)biphenylenediphosphonite, which is available commercially from Ciba Geigy AG as Irgaphos(copyright) PEPQ.
If Rxe2x80x94Oxe2x80x94 and R1xe2x80x94Oxe2x80x94 are bivalent radicals, they preferably derive from di- or trihydric alcohols
R is preferably the same as R1 and is alkyl, aralkyl (preferably unsubstituted or substituted phenyl or phenylene), aryl (preferably unsubstituted or substituted phenyl) or a group of the formula xcex1
where the rings A and B may carry other substituents and Yxe2x80x2 is an oxygen bridge or a sulfur bridge or a bridging unit of the formula xe2x80x94CH(R3)xe2x80x94,
R2 is hydrogen, C1-C8-alkyl or a group of the formula xe2x80x94COOR3, and
R3 is C1-8-alkyl, and
n is 0 or 1 (termed bivalent Rxe2x80x2).
Particularly preferred radicals R are radicals Rxe2x80x3, where this is C1-22-alkyl, phenyl, which may carry from 1 to 3 substituents selected from the group consisting of cyano, C1-22-alkyl, C1-22-alkoxy, benzyl, phenyl, 2,2,6,6-tetramethylpiperidyl-4-, hydroxyl, C1-8-alkylphenyl, carboxyl, xe2x80x94C(CH3)2xe2x80x94C6H5, xe2x80x94COOxe2x80x94C1-22-alkyl, CH2CH2xe2x80x94COOH, xe2x80x94CH2CH2COOxe2x80x94, C1-22-alkyl or xe2x80x94CH2xe2x80x94Sxe2x80x94C1-22-alkyl; or a group of the formulae i to vii
or two Rxe2x80x3 together are a group of the formula viii
where
R8 is hydrogen or C1-22-alkyl,
R6 is hydrogen, C1-4-alkyl or, xe2x80x94COxe2x80x94C1-8-alkyl,
R4 is hydrogen or C1-22-alkyl,
R5 is hydrogen, C1-22-alkyl, C1-22-alkoxy, benzyl, cyano, phenyl, hydroxyl, C1-8-alkylphenyl, C1-22-alkoxycarbonyl, C1-22-alkoxycarbonylethyl, carboxyethyl, 2,2,6,6-tetramethylpiperidyl-4- or a group of the formula xe2x80x94CH2xe2x80x94Sxe2x80x94C1-22-alkyl or xe2x80x94C(CH3)2xe2x80x94C6H5, and
R7 is hydrogen, C1-22-alkyl, hydroxy or alkoxy, and
Yxe2x80x2 and n are as defined above.
Particularly preferred radicals R are radicals Rxe2x80x3 which have one of the formulae a to g
where
R9 is hydrogen, C1-8-alkyl, C1-8-alkoxy, phenyl, C1-8-alkylphenyl or phenyl-C1-8-alkylphenyl or phenyl-C1-4-alkyl,
R10 and R11, independently of one another, are hydrogen, C1-22-alkyl, phenyl or C1-8-alkylphenyl,
R12 is hydrogen or C1-8-alkyl, and
R13 is cyano, carboxyl or C1-8-alkoxycarbonyl.
Preferred groups of the formula a are 2-tert-butylphenyl, 2-phenylphenyl, 2-(1xe2x80x2,1xe2x80x2-dimethylpropyl)phenyl, 2-cyclohexylphenyl, 2-tert-butyl-4-methylphenyl, 2,4-di-tert-amylphenyl, 2,4-di-tert-butylphenyl, 2,4-diphenylphenyl, 2,4-di-tert-octylphenyl, 2-tert-butyl-4-phenylphenyl, 2,4-bis(1xe2x80x2,1xe2x80x2-dimethylpropyl)phenyl, 2-(1xe2x80x2-phenyl-1xe2x80x2-methylethyl)phenyl, 2,4-bis(1xe2x80x2-phenyl-1xe2x80x2-methylethyl)phenyl and 2,4-di-tert-butyl-6-methylphenyl.
Suitable inorganic transesterification stabilizers are described, for example, in U.S. Pat. No. 5,674,928. Particularly suitable compounds which may be mentioned are acid salts of phosphoric acid, e.g. monozinc phosphate, calcium dihydrogen phosphate, sodium dihydrogen phosphate and potassium dihydrogen phosphate. It is also possible to use phosphates, e.g. zinc phosphate or copper phosphate. Other metal phosphates with metals of the first or second transition group are also suitable. Use may also be made of P-containing acids, e.g. phosphoric acid. Examples of suitable compounds are Na3HP2O7, K2H2P2O7, KaH2P2O7 and Na2H2P2O7.
The amount of the stabilizers D) present in the novel molding compositions is from 0.1 to 5% by weight, preferably from 0.2 to 2.5% by weight and in particular from 0.25 to 2% by weight.
According to the invention the molding compositions comprise, as component E), an organic acid or a mixture of two or more different organic acids, in particular low-molecular-weight halogen-free acids. The proportion of this component in the molding compositions is generally from 0.05 to 2% by weight, preferably from 0.1 to 1.8% by weight, in particular from 0.1 to 1.5% by weight, based on the total weight of the molding compositions.
For the purposes of the present invention, low-molecular-weight compounds may have up to a multiplicity of rings, for example up to 5 rings, and are in particular monomolecular compounds, and, of course, acids include the associated moieties typical of acids. Acid hydrates are also included.
According to the invention the acids are halogen-free, i.e. their molecular structure contains no halogens. However, acids which have small amounts of halogen-containing impurities are included according to the invention.
Use is advantageously made of acids which have little or no volatility at the processing temperatures and, respectively, do not decompose at up to about 300xc2x0 C.
The acids may contain one, two or more acid groups, for example up to ten acid groups.
Preference is given to the use of organic acids, which may be aromatic or else aliphatic. It is also possible to use aliphatic-aromatic acids. Preferred acids include palmitic acid, stearic acid, benzoic acid, isophthalic acid, terephthalic acid, trimellitic acid, sulfonic acids, such as p-toluenesulfonic acid, fumaric acid, citric acid, mandelic acid and tartaric acid.
Particular preference is given to the use of citric acid or p-toluenesulfonic acid or mixtures of these. The proportion of citric acid in these by weight may, for example, be from 1 to 99%, preferably from 10 to 90% and that of p-toluenesulfonic acid correspondingly from 1 to 99%, preferably from 10 to 90%.
Besides the essential components A), B), C), D) and E) amounts of up to 60% by weight, preferably up to 50% by weight, of other additives F) may be added to the molding compositions.
Fibrous or particulate fillers which may be mentioned are carbon fibers, glass fibers, glass beads, amorphous silica, asbestos, calcium silicate, calcium metasilicate, magnesium carbonate, kaolin, chalk, powdered quartz, mica, barium sulfate and feldspar, used in amounts of up to 50% by weight, in particular up to 40% by weight.
Preferred fibrous fillers which may be mentioned are carbon fibers, aramid fibers and potassium titanate fibers, and particular preference is given to glass fibers in the form of E glass. These may be used as rovings or chopped glass in the commercially available forms.
The fibrous fillers may have been surface-pretreated with a silane compound to improve compatibility with the thermoplastic.
Suitable silane compounds have the formula
(Xxe2x80x94(CH2)n)kxe2x80x94Sixe2x80x94(Oxe2x80x94CmH2m+1)4xe2x88x92k
where:
n is an integer from 2 to 10, preferably 3 or 4
m is an integer from 1 to 5, preferably 1 or 2, and
k is an integer from 1 to 3, preferably 1.
Preferred silane compounds are aminopropyltrimethoxysilane, aminobutyltrimethoxysilane, aminopropyltriethoxysilane and aminobutyltriethoxysilane, and also the corresponding silanes which contain a glycidyl group as substituent X.
The amounts of the silane compounds generally used for surface-coating are from 0.05 to 5% by weight, preferably from 0.5 to 1.5% by weight and in particular from 0.8 to 1% by weight (based on F).
Acicular mineral fillers are also suitable.
For the purposes of the invention, acicular mineral fillers are mineral fillers with strongly developed acicular character. An example which may be mentioned is acicular wollastonite. The mineral preferably has an L/D (length to diameter) ratio of from 3:1 to 35:1, preferably from 8:1 to 11:1. The mineral filler may, if desired, have been pretreated with the abovementioned silane compounds, but the pretreatment is not essential.
Other fillers which may be mentioned are kaolin, calcined kaolin, wollastonite, talc and chalk.
The novel thermoplastic molding compositions may comprise, as component F), conventional processing aids, such as stabilizers, oxidation retarders, agents to counter thermal decomposition and decomposition by ultraviolet light, lubricants, mold-release agents, colorants, such as dyes and pigments, nucleating agents, plasticizers, etc.
Examples of oxidation retarders and heat stabilizers are sterically hindered phenols and/or phosphites, hydroquinones, aromatic secondary amines, such as diphenylamines, various substituted representatives of these groups and mixtures of these in concentrations of up to 1% by weight, based on the weight of the thermoplastic molding compositions. These differ from B).
UV stabilizers which should be mentioned and are usually used in amounts of up to 2% by weight, based on the molding composition, are various substituted resorcinols, salicylates, benzotriazoles and benzophenones.
Colorants which may be added are inorganic pigments, such as titanium dioxide, ultramarine blue, iron oxide and carbon black, and also organic pigments, such as phthalocyanines, quinacridones and perylenes, and also dyes, such as nigrosine and anthraquinones.
Nucleating agents which may be used are sodium phenylphosphinate, aluminum oxide, silicon dioxide and also preferably talc.
The amounts of lubricants and mold-release agents used are usually up to 1% by weight. These are preferably long-chain fatty acids (e.g. stearic acid or behenic acid), salts of these (e.g. Ca stearate or Zn stearate) or montan waxes (mixtures of straight-chain saturated carboxylic acids with chain lengths of from 28 to 32 carbon atoms), or also low-molecular-weight polyethylene waxes or low-molecular-weight polypropylene waxes.
Examples of plasticizers which should be mentioned are dioctyl phthalates, dibenzyl phthalates, butyl benzyl phthalates, hydrocarbon oils and N-(n-butyl)benzenesulfonamide.
The molding compositions may also comprise from 0 to 2% by weight of fluorine-containing ethylene polymers. These are polymers of ethylene with a fluorine content of from 55 to 76% by weight, preferably from 70 to 76% by weight.
Examples of these are polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymers and tetrafluoroethylene copolymers with relatively small proportions (generally up to 50% by weight) of copolymerizable ethylenically unsaturated monomers. These are described, for example, by Schildknecht in xe2x80x9cVinyl and Related Polymersxe2x80x9d, Wiley-Verlag, 1952, pp. 484 to 494 and by Wall in xe2x80x9cFluorpolymersxe2x80x9d (Wiley Interscience, 1972).
These fluorine-containing ethylene polymers have homogeneous distribution in the molding compositions and preferably have a particle size d50 (number average) in the range from 0.05 to 10 xcexcm, in particular from 0.1 to 5 xcexcm. These small particle sizes may particularly preferably be achieved by using aqueous dispersions of fluorine-containing ethylene polymers and incorporating these into a polyester melt.
Other additives which should be mentioned are flame retardants present in the novel molding compositions in amounts of from 0 to 30% by weight, preferably from 0 to 25% by weight. Particularly suitable flame retardants are halogen-containing compounds, such as brominated oligo- or polystyrenes, nitrogen-containig compounds, such as melamine, melamine cyanurate or guanidines, or phosphorus-containing compounds of any type.
The novel thermoplastic molding compositions may be prepared by processes known per se, by mixing the starting components in conventional mixing equipment, such as screw extruders, Brabender mixers or Banbury mixers, and then extruding. The extrudate may be cooled and comminuted. It is also possible to premix individual components and then to add the remaining starting materials to these, individually and/or likewise mixed. Mixing temperatures are generally from 230 to 290xc2x0 C.
In a preferred method of operation, the components B) to E) and also, if desired, conventional additives F) may be mixed with a polyester prepolymer, compounded and pelletized. The resultant pellets are then condensed to the desired viscosity in the solid phase under an inert gas, continuously or batchwise, at below the melting point of component A).
In another preferred method of operation, components A) and D) are compounded in advance as the masterbatch (concentrate) and then mixed in a usual manner with the other components.
The novel thermoplastic molding compositions have a good combination of mechanical properties, in particular toughness, flowability and melt stability. They are suitable for producing fibers, films or moldings, in particular for applications in the motor vehicle sector and electronics sector, and also as household products or devices in medical engineering.


A flat flexible and imperforate mirror which is conveniently designed and sized to fit anywhere a credit card can be stored is disclosed. The mirror has a substantially flat rectangular body, a front reflective layer and rounded edges. An indicia bearing layer is applied to the opposite side of the body from the reflective layer.

The present invention relates in general to a flat, flexible, imperforate mirror that can be conveniently carried in a credit card pocket of a man or a woman""s wallet, while providing maximum advertising space on one surface for an advertiser, maximum mirror viewing space on an opposite surface for the man or woman. The mirror is constructed as a laminated assembly of equal sized layers providing ease of manufacture all of these features increase the mirror""s commercial value.
In the past, plastic mirrors have been disclosed in the art, but none have been specifically designed to be stored in a credit card pocket to provide maximum advertising space for an advertiser, and maximum viewing space for the user of the mirror, and constructed for ease of manufacture.
U.S. Pat. No. 4,511,618 to Duchene discloses a layer arrangement of a mirror sheet, a mirror coating an optional waterproof layer, a layer of adhesive material, and a flat glass backing layer. Since Duchene is directed to a solar reflecting panel, Duchene would have no need for an indicia bearing area covering an entire surface of the mirror. Duchene is not sized to fit a credit card pocket.
U.S. Pat. No. 4,780,372 to Tracy discloses a layer arrangement of a paint coat, a layer of copper, a silver layer, a layer of silver nitride, and a glass substrate. Not all layers are of the same size in Tracy. Tracy does not disclose an indicia bearing layer, and is not sized to fit into a credit card pocket.
U.S. Pat. No. 5,247,395 to Martinez discloses a layer arrangement of a mirror film, a raised film support surface, and a layer of stamped or formed members. Martinez discloses applications for xe2x80x9cwashrooms, gyms, locker rooms etc.xe2x80x9d (col. 1, lines 13-14). Martinez does not disclose an indicia bearing area covering an entire surface of the mirror. Martinez"" device is perforated reducing the viewing and advertising area.
U.S. Pat. No. 4,792,482 to Leach discloses a layer arrangement of an optional plastic sheet or film or cardboard protective layer, a mirror layer, a porous layer of fibrous material, and a backing layer. Leach discloses support surfaces for the mirrors as wells and the ceiling of buildings. In an environment in which the mirror is mounted to a wall or ceiling, such as in Leach, there would be no use in placing an indicia bearing layer on the backside. The layers in Leach are not equal in size, and the mirror is not sized to fit into a credit card pocket.
U.S. Pat. No. 4,889,419 to Kite discloses a layer arrangement of a mirror and a base material. Kite discloses that only a portion of a surface may be used as a place for textual material such as advertising. Kite has notches and perforations in his device further reducing viewing and advertising space.
U.S. Pat. No. 4,605,292 to McIntosh discloses a layer arrangement of non-magnetically attractive supporting surface, a layer of adhesive, a carrier strip, an adhesive coating, a magnet, an adhesive coating, and a rear surface. In McIntosh, the layers are not all equal sized. Also, in McIntosh the visible indicia is placed on a reflective surface, obstructing viewing area.
U.S. Pat. No. 3,743,389 to Stiller discloses a layer arrangement of polyvinyl chloride, mirror, and polyvinyl chloride. Stiller does disclose that the exterior of the case is imprinted with a slogan. In Stiller, the indicia layer obstructs the reflective layer, and the indicia layer is of a different size than the reflective layer.
U.S. Pat. No. 4,636,047 to Green discloses a layer arrangement of a paper layer, a remaining paper layer, an adhesive layer, metal lamina, and a chromium plating layer. The mirror accessory of Green is designed to adhere to the back of a watch, and would serve no purpose for it to have an indicia bearing layer on the opposite side. In Green, the unreflective layer and the reflective layer are not of the same size. The layer arrangement of Green is much thicker than can fit into a credit card holder.
U.S. Pat. No. 4,024,828 to Knoll discloses a protective coating, chrome plating, and a plate. Knoll has a perforated structure reducing viewing and advertising space.
U.S. Pat. No. 2,647,441 to Boydston discloses a layered arrangement of a magnesium fluoride overcoating, a metallic or other reflecting film, and glass or other mirror base. Boydston does not disclose a layer or visible indicia and is not sized to fit a credit card pocket.
U.S. Pat. No. 1,454,678 to Krueger discloses a layered arrangement of a front cover having an outer surface for the placing of a suitable advertising inscription, an intermediate supplementary, and a metallic disk. The reflector of Krueger has a hole, reducing viewing and advertising space, and the indicia layer obstructs the reflective layer.
It is therefore an object of the present invention to provide for a flat, flexible, imperforate mirror, which is conveniently designed and sized to fit anywhere a credit card can be stored. At the same time it provides an unreflective surface which will provide maximum space for advertising and reflective surface that provides maximum surface for the user of the mirror, and equally sized layers to provide ease of manufacture.

Credit card pocket mirror and miniature billboard


A location system in a cellular communication network has a first set of base stations which transmits and receives signals in a first communication format. The second set of base stations transmits and receives signals in a second communication format. All the base stations transmit known signals at predetermined times for use in deriving location data. A transmitting and receiving unit of the known location determines the times of arrivals of these signals from each base station in each set of base stations. Similarly, a mobile unit at an unknown location determines the times of arrival of the signals from each base station. By comparing timing differences between signals received at the unknown location and signals received at the known location, it is possible to determine the unknown location therefrom. This can then be transmitted back to either of the sets of base stations. In a situation where two communication networks are used, the mobile units will be dual mode transmitting and receiving units.

This invention relates to a location system for use in a cellular communication network.
Cellular communication networks are being continuously developed and upgraded. The operators of these networks are, in combination with this, looking at ways of producing additional sources of revenue. One of these is known as "location based services". These are uses of mobile units in a cellular communication network, such as mobile telephone handsets, that rely upon the network knowing where the handset is. The type of services which can be provided to handsets include local information, map information, traffic reports, etc. The networks see these services as being potentially very lucrative. However, the range of services that can be offered and their usefulness to a user is limited by the accuracy with which the location of a user can be derived.
A number of different mechanisms have been proposed for determining location of mobile units within a cellular communication network. One of the most commonly used is known as Enhanced Offset Time Differential (E-OTD). This system works by measuring at a mobile unit, the time difference between specific signals arriving from different base stations. Three or more base stations are required. This produces an offset between the signals from the different base stations which is reported back to the network. Appropriate processing within the network can then compare the offset with equivalent data from a measurement made at a known fixed location. This comparison then allows the location of the handset to be calculated in relation to the base stations and the fixed location.
Referring to FIG. 1, the figure shows a simple mobile network comprising three base stations 20. Two units receive signals from the base stations; a mobile handset 24 and a fixed location unit 26. Each of these units measures the time difference between defined signals from each base station. Each unit reports this offset data to the network.
The network knows the locations of all the base stations 20 and of the fixed location unit 26 it is possible to calculate the distance of the handset 24 from each of the three base stations 20. The maths required to perform this calculation is and need not be reproduced here but will be familiar to those skilled in the art.
The output of the calculation is a series of arcs describing the separation between the handset and each base station. There is an inherent error in each arc due to factors such as the accuracy of the measurement. The location of the handset 24 is therefore determined as the center of the overlap of the arcs, subject to an uncertainty of the size of the overlap area.
There are a number of factors which contribute to the accuracy of the determined location. Four of the principle factors are as follows;
1. The accuracy with which an offset measurement can be made. This is a function of the data rate of the network and the sampling speed of the handset. It is not usually possible to alter either of these.
2. The accuracy of the radio propagation model which is held by the cellular network. This is usually limited by the processing power of the network and the availability and accuracy of geographical data on which to work.
3. The number of measurements that are averaged before an offset is reported to the network. The larger the number of measurements averaged, the greater the accuracy, providing the mobile unit is not moving. If the mobile unit is moving, then a larger number leads to a decrease in accuracy.
4. The number of different base stations from which offsets are measured. This is limited by the network design since it is not possible to measure offsets from base stations which are not within the network. One option would be to monitor base stations in rival networks, although this is not a popular option with network operators since it would involve major changes to the "neighbor cell" information that the network provides to a mobile unit.
These limitations make it very difficult to improve the accuracy of E-OTD.
Currently what are known as third generation (3G) cellular communication networks and handsets are being introduced. For a significant period of time there will be a large number of handsets which are known as "dual mode" handsets. That is to say, they are capable of monitoring both 2G and 3G systems. The fact that these dual mode handsets are able to communicate with two cellular communication networks using 2G and 3G radio access technology (RATs) means that the number of base stations monitored can be increased. This can be achieved without making any significant additional complication to the network signalling requirements since the majority of signalling required is already supplied under the 3G network interoperability design.
In addition, dual mode handsets potentially solve a problem in the Universal Mobile transmission Standard (UMTS), which is a spread spectrum system. It is therefore necessary for each cell briefly to stop transmitting to allow a handset to receive signals from other cells from on the same frequency and to measure their time offset. This period is known as Idle Period in Downlink (IPDL). IPDL is complicated in that all handsets in the area have to be made aware that the signals from the cell is going to vanish temporarily and then reappear. The network has to provide processing power to schedule the gaps and the mobile units or handsets must provide processing power to redirect their transmitters and receivers to look for other cells.
IPDL is also inefficient because when the cell is turned off, it is not sending data. Thus network bandwidth is reduced and a potentially billable resource is lost. Furthermore, many UMTS networks and handsets as currently proposed do not support IPDL.
As has been stated, a dual mode handset is capable of monitoring two radio systems. To get a location fixed, only one radio system must be monitored (although more systems lead to better accuracy). Thus, subject to appropriate data conversion being possible, a dual mode UMTS/GSM handset can obtain a location fix using the GSM (Global System for Mobile communication) network signals and escape the need for IPDL and UMTS.
Dual mode handsets are able to operate on both the 2G and 3G networks. By definition a dual mode handset must be capable of receiving signals from both radio systems. There are, however, two types of dual mode handset; those that can operate on both radio systems simultaneously; and those that can only operate on one radio system at a time.
Handsets which can operate on both radio systems simultaneously are able to perform monitoring of the second system without interfering with the first. The latter type require operation on one system to cease while operation on the other proceeds.
The 2G system which is envisaged in the current embodiment of the invention is the GSM cellular communications system and the 3G system contemplated is the UMTS system. Where we have a GSM/UMTS dual mode handset, UMTS can operate in the gaps which are inherent in the GSM time division structure. GSM can then operate by what is known as compressed mode which is a technique that creates gaps in the UMTS data stream to allow monitoring of other radio systems or frequencies. For a mobile to be a dual mode GSM/UMTS, it must be able to operate in one of these ways. Such units are available although they are not currently used or intended to be used in E-OTD.
Specific embodiments of the present invention provide a method for determining the location of dual mode mobile units in a dual mode cellular communications network by deriving location data from both communication networks.
In one embodiment, location information is derived by each mobile unit.
In an embodiment of the invention, there is provided a timer to provide a temporal point of reference between the two cellular networks to overcome differences in the time bases of the different networks.
The invention is defined in more precision in the appended claims to which reference should now be made.
E-OTD as currently proposed is capable of working independently in either the GSM or UMTS networks. Nevertheless, the data reported to each network is very similar and takes the following form:
1. The time when the measurement was made (derived from the frame number of the ell serving the mobile unit at the time of the measurement, and the cell in which the mobile unit is located).
2. The identity of the cell currently being monitored for E-OTD signals.
3. The time offset between signals received from the serving cell and the cell being monitored.
As the reporting data is of similar form for both transmission standards, it is not difficult to combine provided that it is all referenced to a common point in time This is where complication arises. There are three main problems associated with combining data from one RAT with data from another, These are as follows:
1. The time bases of the different RATs are different;
2. A dual mode handset is usually connected to only one RAT while it monitors the other. This applies equally when in a call or just in standby mode. Thus, there is no serving cell on the second RAT and therefore no defined timebase against which it may perform offset monitoring;
3. There is currently no mechanism for reporting data measured in one RAT by sending it over a second RAT.
We have appreciated the first of these problems can be dealt with by some data processing supplied in hardware, the second by a change in the operating of the handset, and third by changes to network signalling. Embodiments which solve these problems are described below.
The requirements described below will also have to be used at the network fixed location units which are required in E-OTD to calculate the positions of mobile units. These will need to report dual mode data. Therefore, the techniques which will be described below and are used in the handset must also be built into the network fixed units. If this is not done, then there will be no E-OTD reference data easily available. One option would be to have data from single mode units in each of the two networks combined when the location calculation is formed.
A dual RAT E-OTD system has a number of other requirements. These are already covered by default in a GSM/UMTS dual mode combination but they may require addressing when the technique is applied to other radio access technologies.
Firstly, the handset must know where to look for cells on the alternate RAT. In a situation where the same or cooperative operators deploy the two networks in the same area, each network supplies details of the others local cells. This is useful since it provides to a handset almost all the details needed to make offset measurements on the other RAT.
Secondary, the handset must be able to make E-OTD measurements on the alternate RAT. This is actually very simple to achieve in GSM/UMTS dual mode units as the required signals are already monitored. For GSM this is the BSIC decode, and for UMTS this is part of the synchronization information. Some additional processing power is required but there is no extra radio activity.
The structure of transmissions on each RAT in a dual mode system will be known and well defined and therefore timing conversions between the two can be made as long as there is a point of reference. In a GSM/UMTS combination the time bases can be referenced by performing a simple offset measurement. This measurement records the offset between the start of a transmission frame on each system. In addition, the GSM and UMTS frame numbers at which the measurement was performed must be recorded. If these three pieces of information are available it is then possible to convert between GSM and UMTS time bases as described below.
FIG. 2 shows a UMTS multiframe known as a UTRA superframe and a GSM multiframe starting at a different time to the UTRA superframe. The time difference is Toffset.
For the purposes of these explanation, the following designations apply:
fn=frame number
fp=frame period
sn=slot number
cn=chip number
sfn=superframe number
pb=quarter bit.
A UMTS frame is 10 ms long and made up of 15 slots each of 10/15 ms. Each slot is made up of 2560 chips each of 10/38400 ms.
Each GSM superframe is 3060/13 ms length and is made up of 51 frames of 60/13 each frame is eight slots of 15/26 ms in length. Each slot is made up of 625 qb numbers of 15/16250 ms in duration.
In order to measure the time Toffset in FIG. 1, a knowledge of the frame offset timing and the respective GSM and UMTS frame numbers at which the offset was measured will enable the total offset to be calculated. This can be derived from the following equation:Toffset=[(UTRA—fn×UTRA—fp)−(GSM—fn×GSM—fp)+Frame_Offset ]MOD(51×GSM—fp).
In order to define the GSM timebase from that of the UMTS time base, we need to know the elapsed time from the start of the UTRA superframe*. This is given in ms by:GSM_Time=(Time from start of UTRA superframe)−(Toffset).
The corresponding GSM superframe, frame, slot and quarter bit numbers can now be calculated into dividing the GSM time by the duration of each and taking an appropriate modulus. This is given in the following equations:
                    GSM_sfn        =                  INT                                [                          GSM_Time                              (                                  3060                  /                  13                                )                                      ]                                                  GSM_fn        =                              INT                                      [                              GSM_Time                                                      30                    /                    13                                    )                                            ]                                                      MOD                                      (              51              )                                                              GSM_sn        =                              INT                                      [                              GSM_Time                                                      15                    /                    26                                    )                                            ]                                                      MOD                                      (              8              )                                                              GSM_qb        =                              [                          GSM_Time                              (                                  15                  /                  16250                                )                                      ]                                          MOD                                      (              625              )
The UMTS time base can be defined in that of the GSM timebase in a similar manner as shown below:UTRA Time−(Time from start of GSM multiframe)+(Length of N GSM multiframe)+(Toffset)which becomes:
  UTRA_Time  -      [                  (                  GSM_fn          ×                      60            13                          )            +              (                  GSM_sn          ×                      15            26                          )            +              (                  GSM_qb          ×                      16            16250                          )            +              (                  N          ×          51          ×                      60            13                          )            +              T        offset              ]
The frame slot and chip numbers can then be determined in a manner similar to that shown for GSM and indicated below:
      UTRA_fn    =                  INT                          [                      UTRA_time            10                    ]                                  MOD                          (          4096          )                          UTRA_sn    =                  INT                          [                      ITRA_Time                          10              /              15                                ]                                  MOD                          (          15          )                          UTRA_chip    =                  [                  UTRA_Time                      10            /            38400                          ]                          MOD                          (          2560          )
Thus, it can be seen that by making a simple offset measurement, timebase conversion between RATs is possible. The above example is shown applied specifically to GSM and UMTS RATs but the principle can be applied to any RAT which uses a cyclic transmission scheme.
In order to perform the timebase conversion, we must first know the offset between the two RATs—we need the temporal point of reference denoted frame—reference in the above equations. This is done by using a high resolution timer. This is shown in at reference numeral 2 in FIG. 3. The timer has three inputs, a clock 4, a UMTS interrupt 6 and a GSM interrupt 8. All these signals are present in a dual mode handset. The clock is present for obvious reasons. The UMTS and GSM frame interrupts which occur at the start of each radio frame on the appropriate system are there to ensure that synchronization is maintained with radio operations.
The timer 2 is activated by a command from a CPU 9. Counting starts on receipt of a UMTS interrupt. It is then incremented at the cock rate until it is stopped by a GSM interrupt. When the timer stops, the count multiplied by the clock period (1/F) is the frame offset time. The CPU can then read the counter time and combine this value with knowledge of the clock rate and the current value of GSM and UMTS frame counters 10 and 12 to calculate the offset time to calculate Toffset in unit 14. As can be seen, the three inputs to the calculate Toffset unit 14 are the counts from the GSM frame counter 10 of the UMTS frame counter 12 and the frame offset time reported by the timer 2.
The counter module is implemented in a programmable semiconductor device—CPLD (Complex Programmable Logic Device), FPGA (Filed Programmable Gate Array) or similar and takes the form shown in FIG. 4.
(1) To initialize the counter module, the CPU writes a 1 to a control register 30. This action automatically resets a counter 34 to zero and initializes flip-flops to zero output.
(2) When the next UMTS interrupt arrives, it passes into an AND gate 36 where it is combined with the current control bit value. If the control is set to 1, then the AND output goes high for the duration of the interrupt pulse, and a flip-flop is triggered. The flip-flop output will then go high. This will cause the inputs to an XOR 38 gate to be different, and hence logic high will be output from the XOR 38. This logic high will start the counter running.
(3) When the next GSM interrupt arrives it passes into an AND gate 40 where it is combined with the current output value of the XOR gate 38. If this is high, then the AND 40 output goes high for the duration of the interrupt pulse, and a flip-flop is triggered. This will cause the inputs to the XOR gate 38 to be the same, and hence logic low will be output from the XOR. This will stop the counter.
(4) An edge detect circuit 42 detects the transition of the XOR 38 output from high to low and resets the control bit 30 to indicate that counting is complete As an alternative, the edge detect 42 can also provide an interrupt to the CPU to notify of count completion.
(5) The CPU reads the control bit, and if it is now zero, then reads the completed count. If the bit is not zero, the count is still underway so that the CPU must wait.
The electronics is arranged so that only the above sequence of events can generate a timer value. The control bit must be set before a UMTS interrupt can start the timer; the time must be running before the GSM Interrupt can stop it. It is impossible for a second UMTS interrupt to arrive before the first GSM interrupt because of the relative frames lengths in the two systems.
Note that all the electronic processes in this sequence have inherent delays. The electronics through which each of the interrupt signals passes has been made the same (AND, flip-flop, XOR) in an attempt to keep the delay on each signal the same. If the same delay applies to both signals, measuring an offset between them is still valid. Care must be taken over the physical implementation of the circuit to ensure that the delays are the same.
It is important to have a timer with sufficient resolution. The resolution must be better than that of E-OTD measurements to be reported since the accuracy of the timer dictates the maximum accuracy of location that can be determined. For example, if there is a 10 NS resolution in the timer then this will correspond to three meters of radio propagation giving a potential error of three meters in the report made by the handset. Therefore, the maximum accuracy with which location can be stated is three meters although it will in fact be worse than this as the E-OTD calculation itself is not completely accurate.
E-OTD systems are typically accurate to tens of meters and the resolution of the timer must give a maximum error considerably less than this to avoid the errors simply compounding and being unacceptably large. Most mobile handsets available now have internal clock speeds of tens to hundreds of megahertz. An offset performed using a timer clock of a hundred megahertz give a resolution of 10 ns which as shown above is 3 m of radio propagation and this is acceptable.
It is important that the timer is able to measure between timebases regardless of which RAT the handset is currently using. The frequency of measurement depends on external factors such as movement which can cause the timebases within the handset to move out of step and, also, a new measurement is needed after every cell selection or handover on the primary RAT. If the secondary RAT timebase is linked to a particular cell then a measurement is needed after every change in the secondary RAT cell used for the synchronization.
In order to solve the problem of not having a a defined timebase on the second RAT, a free running timebase of the format used by the second RAT is established within the handset and clocked from the same source as the primary RAT. This establishes a baseline against which to measure It does, however, need to be tied to the baseline used for the primary RAT if measurements from the two systems are to be combined. This is achieved by driving the two timebases from the same master clock through appropriate dividers to ensure that the timebases stay in step. Thus, the frame offset value need only be measured when the serving cell on the primary RAT changes and at this point the primary RAT timebase undergoes a step change to synchronize with its new serving cell.
Alternatively, the secondary RAT timebase can be aligned with that of the best available cell on the secondary RAT. This is slightly more complicated as slippage between the two timebases is then possible. This will be caused by motion of the handset, reselection of the best cell, etc. Re-measurement of frame offset is then required in each of these cases. In order to obtain maximum accuracy, the frame offset should e measured alongside each E-OTD measurement. This is not desirable from a power saving point of view as it requires the radio CPU to be active for slightly longer than would otherwise be the case.
The above now enables us to convert between RAT timebases and therefore E-OTD measurements made on different RATs can be converted to a common format. This therefore increases the number of base stations available for user in a location calculation and improves the accuracy of the calculated location.
The remaining step is that of getting the location data back to the network This requires changes to the signalling layers on the handset, core network and fixed location units.
In one embodiment, the timebase conversions can be performed within the network. The handsets and the fixed location units measure and supply frame offset information, this can be either Toffset as described above or can be frame offset plus the GSM and UMTS frame numbers at which it was measured. This can then be reported in addition to performing standard E-OTD measurements on the alternate RAT. Data is returned i the format used by the alternate RAT. This requires a change to the network signalling and specifically a new structure needs to be included as an option for E-OTD reporting. This new structure is the standard E-OTD report used by the alternate RAT with an additional field for the offset measurement. As either network can be the primary network in use, changes to signalling structure must be made in both networks.
Another option would be for the handset and fixed location units to perform the timebase conversion and thus avoid the need for a network change. Each would then be able to send data to the primary RAT in the correct format. This has the drawback that processing is moved to the handsets from the network thereby increasing power consumption. Also, changes to the network are still required as ID codes for cells on one RAT do not fit the E-OTD reporting measurement on the other RAT. Therefore, as network changes are needed in any case, it is expedient to also add the conversion functionality to the network.
If the only requirement is to allow data from the a secondary RAT to be passed to and used by the primary RAT and it is not be combined with this data of the primary RAT and there is no need to convert timebases. This is only true if the fixed location units were reporting the data in the same format as the handset. This is the situation where we wish to avoid using IPDL in UMTS and so E-OTD is measured only on the alternate RAT, (i.e. GSM) and reported to the network in GSM format. There is no UMTS data to be combined and so no conversion from GSM to UMTS timebase is required.

Location systems in cellular communication networks