A blind for hunters or observers and particularly geese hunters is characterized by having a decoy shell in the form of a goose which is sized to be large enough to accommodate the hunter or observer in a seated position on a swivel mount and to cover the greater portion of the hunter so as to be concealed from view, and the decoy is divided into symmetrical halves which are pivotal about a shell support structure at the base of the shell so as to be readily movable into an open position when the hunter wishes to fire at approaching geese.

This invention relates to a hunting blind and more particularly relates to a novel and improved blind adapted for hunting or observing fowl.
Various types of hunting blinds have been devised for hunting fowl, particularly ducks and wild geese, and these can generally be characterized as being portable and in many cases shaped to simulate a bird, such as, a wild goose. Representative examples are U.S. Pat. No. 4,067,346 to Husted, G. L., U.S. Pat. No. 4,086,931 to Hall, W. E., U.S. Pat. No. 4,110,941 to Scott, R. K., U.S. Pat. No. 4,375,488 to Hogan, M. J., U.S. Pat. No. 4,689,913 to Brice, R. V., U.S. Pat. No. 4,723,371 to Williams, D. C., U.S. Pat. No. 4,738,045 to Cardozo, D. W., U.S. Pat. No. 5,458,079 to Matthews, G. et al, U.S. Pat. No. 5,592,960 to Williams, C. R., U.S. Pat. No. 5,678,346 to Kellett, K. C., and U.S. Pat. No. 5,787,632 to Kraut, R.
The art of designing blinds has been extremely active and crowded over the years. Nevertheless, there is a continuing need for a hunter""s blind which is in the form of a decoy but is sufficiently large that the hunter can sit or stand comfortably within the decoy with virtually unlimited viewing. In this respect, it is important that the hunter be able to selectively open the shell or decoy quickly and be in a position to immediately fire a gun.
It is therefore an object of the present invention to provide for a novel and improved blind which is sized to permit a hunter or observer to sit or stand comfortably therein and wherein the blind has an appearance simulating that of a goose or other fowl and can be rapidly opened by the hunter when birds approach the blind.
It is another object of the present invention to provide for a novel and improved blind which can be easily assembled and disassembled in a minimum number of steps and in assembled position will form a housing which covers the greater part of the hunter""s body.
It is a further object of the present invention to provide for a novel and improved blind which will attract approaching geese and at the same time cover the hunter""s body; and further wherein the blind is so constructed and arranged that it can be swivelled to afford an unrestricted view of approaching fowl, is readily movable into an open position when the hunter wishes to fire at the approaching fowl and can be readily disassembled without the necessity of removing fasteners or other attachment devices.
In accordance with the present invention, it has been found that, for purposes of attracting geese, the size of a decoy is of little or no importance. Rather, the shape and appearance of the decoy are major factors in attracting geese and that it be formed in such a way as to substantially completely conceal the hunter stationed in the blind; yet, make it as comfortable as possible for the hunter who must wait over extended time periods before sighting the approaching geese. Still another desirable feature is that the blind be as lightweight as possible, readily transportable and stowable when not in use.
In accordance with the present invention, a hunter""s blind has been devised which comprises a housing in the form of a hollow shell of generally oval-shaped configuration having segmental wall portions movable between a closed position in which the segmental wall portions define a substantially continuous wall and an open position in which said segmental wall portions are movable laterally and outwardly to form an upper opening large enough for the hunter to protrude and fire a gun at approaching fowl; and opposite sides of the shell terminate in a lower annular edge, a seat mounted for upward extension from a support structure into the housing, the housing being sized to accommodate a hunter in a seated position therein, and housing-support means for mounting the housing above ground level so that a hunter can be positioned comfortably within the housing and be able to sight approaching fowl or game. In the preferred form of hunter""s blind, the seat mounting means is adapted to mount the seat for rotation about a vertical axis and the shell or housing is rotatable with the seat to enable the hunter to periodically rotate the blind to view or sight over substantially 360xc2x0 or a full circle. The shell is configured to be in the form of a fowl with an upper recessed portion for the head of the hunter and a viewing aperture through the upper recessed portion; and the segmental portions of the shell can be readily opened and closed by the hunter by hinging about lower pivotal support means between the lower end of the shell and the shell support means. The segmental portions are preferably symmetrical halves in normally closed relation to one another but which will open laterally outwardly about the lower hinges to permit the hunter to rapidly aim and fire his gun.
There has been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will form the subject matter of the claims appended hereto. In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.


A flame resistant thermoplastic molding composition is disclosed. The composition contains aromatic polycarbonate, graft polymer, a specifically structured phosphorous compound, fluorinated polyolefin and inorganic compound with an average particle size no greater that 200 nm and an optional vinyl(co)polymer. The inventive composition is characterized in its improved stress cracking resistance and mechanical properties.

The present invention relates to flame-proof polycarbonate ABS moulding compositions containing phosphate compounds and inorganic materials which have excellent resistance to stress cracking.
EP-A 0 174 493 (U.S. Pat. No. 4,983,658) describes flame-proofed, halogen-containing polymer mixtures consisting of aromatic polycarbonate, styrene-containing graft copolymer, monophosphates and a specific polytetrafluoroethylene formulation. Although these mixtures are adequate in terms of fire behaviour and level of mechanical values, shortcomings may arise as regards resistance to stress cracking.
U.S. Pat. No. 5,030,675 describes flame-proof thermoplastic moulding compositions consisting of aromatic polycarbonate, ABS polymer, polyalkylene terephthalate as well as monophosphates and fluorinated polyolefins as flame-proofing additives. Good resistance to stress cracking is contrasted by disadvantages in the form of shortcomings as regards notch impact strength and inadequate thermostability under high thermal load such as the processing process.
Diphosphates are known as flame-proofing additives. JA 59 202 240 describes the production of such a product from phosphorus oxychloride, diphenols such as hydroquinone or bisphenol A and monophenols such as phenol or cresol. These diphosphates may be used in polyamide or polycarbonate as flame-proofing agents. In this literature, however, there is no indication of improved resistance to stress cracking by addition of the oligomeric phosphate to polycarbonate moulding compositions.
EP-A 0 363 608 (=U.S. Pat. No. 5,204,394) describes polymer mixtures consisting of aromatic polycarbonate, styrene-containing copolymer or graft copolymer and oligomeric phosphates as flame-proofing additives. U.S. Pat. No. 5,061,745 describes polymer mixtures consisting of aromatic polycarbonate, ABS graft polymer and/or styrene-containing copolymer and monophosphates as flame-proofing additives. The level of the stress cracking resistance of these mixtures is often inadequate for the production of thin-walled housing parts.
EP-A 0 767 204 describes flame-proof polyphenylene oxide (PPO) and/or polycarbonate mixtures which contain a mixture consisting of oligophosphates (bisphenol A (BPA)-oligophosphate type) and monophosphates as flame-proofing agents. High flame-proofing agent contents lead to disadvantageous mechanical properties and reduced heat deflection temperature.
EP-A 0 611 798 and WO 96/27600 describe moulding compositions which contain oligomeric, terminally alkylated phosphoric acid esters of the BPA type in addition to polycarbonate. Because of the alkylation, high contents are required in order to achieve effective flame-proofing, and this is very disadvantageous for many technical application properties.
EP-A 0 754 531 describes reinforced PC/ABS moulding compositions which are suitable for precision components. Inter alia, oligophosphates of the BPA type are used as flame-proofing agents. The high filler contents have a very disadvantageous effect on the mechanical properties.
Surprisingly it has now been found that flame-proof polycarbonate ABS moulding compositions have excellent stress cracking resistance and notch impact strength as well as a high heat deflection temperature when they contain an additive combination consisting of a specific phosphorus compound and a synergistically acting quantity of one or more inorganic materials. A particularly favourable property combination is achieved when the phosphorus compound is made up of bisphenol A units. These moulding compositions are particularly suitable for producing thin-walled housing parts (data processing housing parts) where high processing temperatures and pressures lead to considerable stress on the material used.
The invention provides flame-proof thermoplastic moulding compositions containing
A. 40 to 98 parts by weight, preferably 50 to 95 parts by weight, particularly preferably 60 to 90 parts by weight of an aromatic polycarbonate,
B. 0 to 50, preferably 1 to 30 parts by weight, of a vinyl (co)polymer consisting of at least one monomer selected from the series styrene, xcex1-methylstyrene, ring-substituted styrenes, C1-C8-alkyl methacrylates, C1-C8-alkyl acrylates with at least one monomer from the series acrylonitrile, methacrylonitrile, C1-C8-alkyl methacrylates, C1-C8-alkyl acrylates, maleic anhydride, N-substituted maleinimides,
C. 0.5 to 60 parts by weight, preferably 1 to 40 parts by weight, particularly preferably 2 to 30 parts by weight of a graft polymer,
D. 0.5 to 20 parts by weight, preferably 1 to 18 parts by weight, particularly preferably 2 to 15 parts by weight of a phosphorus compound of formula (I)
in which
R1, R2, R3 and R4 independently of each other mean C1-C8 alkyl optionally substituted by halogen, C5-C6-cycloalkyl, C6-C10-aryl or C7-C12-aralkyl optionally substituted by halogen and/or alkyl in each case,
n independently of each other means 0 or 1,
q independently of each other means 0, 1, 2, 3 or 4,
N means 0.1 to 5 and
R5 and R6 independently of each other mean C1-C4-alkyl, preferably methyl or halogen, preferably chlorine and/or bromine,
Y means C1-C7-alkylidene, C1-C7-alkylene, C5-C12-cycloalkylene, C5-C12-cycloalkylidene, xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94SOxe2x80x94, xe2x80x94SO2xe2x80x94 or xe2x80x94COxe2x80x94,
E 0.05 to 5 parts by weight, preferably 0. 1 to 1 part by weight, particularly preferably 0.1 to 0.5 parts by weight of a fluorinated polyolefin,
F. 0.01 to 50 parts by weight, preferably 0.1 to 20 parts by weight, particularly preferably 0.5 to 10 parts by weight of finely divided inorganic powder with an average particle diameter xe2x89xa6200 nm.
The sum of all parts by weight A+B+C+D+E+F is 100.
Thermoplastic aromatic polycarbonates suitable according to the invention according to Component A are those based on diphenols of formula (II)
in which
A is a single bond C1-C5-alkylene, C2-C5-alkylidene, C5-C6-cycloalkylidene, xe2x80x94Sxe2x80x94 or xe2x80x94SO2xe2x80x94,
B is chlorine, bromine,
q is 0,1 or 2 and
p is 1 or 0,
or alkyl-substituted dihydroxyphenyl cycloalkanes of formula (III)
in which
R7 and R8 independently of each other, in each case mean hydrogen, halogen, preferably chlorine or bromine, C1-C8-alkyl, C5-C6-cycloalkyl, C6-C10-aryl, preferably phenyl, and C7-C12-aralkyl, preferably phenyl-C1-C4-alkyl, particularly benzyl,
m means a whole number of 4, 5, 6 or 7, preferably 4 or 5,
R9 and R10, individually selectable for each Z and independently of each other mean hydrogen or C1-C6-alkyl, and
Z means carbon, with the proviso that on at least one atom Z R9 and R10 simultaneously mean alkyl.
Examples of suitable diphenols of formula (H) are hydroquinone, resorcinol, 4,4xe2x80x2-dihydroxydiphenyl, 2,2-bis-(4-hydroxyphenyl)-propane, 2,4-bis-(4-hydroxyphenyl)-2-methylbutane, 1,1-bis-(4-hydroxyphenyl)-cyclohexane, 2,2-bis-(3-chloro-4-hydroxyphenyl)-propane, 2,2-bis-(3,5-dibromo-4-hydroxyphenyl)-propane.
Preferred diphenols of formula (II) are 2,2-bis-(4-hydroxyphenyl)-propane, 2,2-bis-(3,5-dichloro-4-hydroxyphenyl)-propane and 1,1-bis-(4-hydroxyphenyl)-cyclohexane.
Preferred diphenols of formula (III) are 1,1-bis-(4-hydroxyphenyl)-3,3-dimethyl-cyclohexane, 1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethyl cyclohexane and 1,1-bis-(4-hydroxyphenyl)-2,4,4-trimethyl-cyclopentane.
Polycarbonates suitable according to the invention are both homopolycarbonates and copolycarbonates.
Component A may also be a mixture of the thermoplastic polycarbonates defined above.
Polycarbonates may be produced in known manner from diphenols with phosgene by the interface process or with phosgene by the process in homogeneous phase, the so-called pyridine process, wherein the molecular weight can be set in known manner by means of a corresponding quantity of known chain terminators.
Examples of suitable chain terminators are phenol, p-chlorophenol, p-tert.-butyl phenol or 2,4,6-tribromophenol, but also long-chain alkyl phenols such as 4-(1,3-tetramethylbutyl)-phenol according to DE-OS 2 842 005 or monoalkyl phenol and/or dialkyl phenol with a total of 8 to 20 C atoms in the alkyl substituents according to German patent application P 3 506 472.2 such as 3,5-di-tert.-butyl phenol, p-iso-octyl phenol, p-tert.-octyl phenol, p-dodecyl phenol and 2-(3,5-dimethyl-heptyl)-phenol and 4-(3,5-dimethyl-heptyl)-phenol.
The quantity of chain terminators is generally between 0.5 and 10 mole %, related to the sum of the diphenols of formulae (II) and/or (III) used in each case.
The polycarbonates A suitable according to the invention have average molecular weights ({overscore (M)}w), weight average, measured by ultracentrifuging or scattered light measurement for example) of 10,000 to 200,000, preferably 20,000 to 80,000.
The polycarbonates A suitable according to the invention may be branched in known manner, and indeed preferably by the incorporation of 0.05 to 2 mole %, related to the sum of the diphenols used, of tri- or more than trifunctional compounds, such as those with three or more than three phenolic groups.
In addition to the bisphenol A homopolycarbonate, preferred polycarbonates are the copolycarbonates of bisphenol A with up to 15 mole %, related to the mole sum of diphenols, of 2,2-bis-(3,5-dibromo-4-hydroxyphenyl)-propane and the copolycarbonates of bisphenol A with up to 60 mole %, related to the mole sum of diphenols, of 1,1-bis-(4-hydroxyphenyl)-3,3,5 -trimethyl cyclohexane.
The polycarbonates A may be partially or completely replaced by aromatic polyester carbonates. The aromatic polycarbonates of Component A may also contain polysiloxane blocks. Their production is described in DE-OS 3 334 872 and U.S. Pat. No. 3,821,325 for example.
Vinyl (co)polymers according to Component B which can be used according to the invention are those consisting of at least one monomer from the series: styrene, xcex1-methylstyrene and/or ring-substituted styrenes, C1-C8-alkyl methacrylate, C1-C8-alkyl acrylate (B.1) with at least one monomer from the series: acrylonitrile, methacrylonitrile, C1-C8-alkyl methacrylate, C1-C8-alkyl acrylate, maleic anhydride and/or N-substituted maleinimides (B.2).
C1-C8-alkyl acrylates and/or C1-C8-alkyl methacrylates are esters of acrylic acid and/or methacrylic acid and monohydric alcohols with 1 to 8 C atoms. Methacrylic acid methyl ester, ethyl ester and propyl ester are particularly preferred. Methylmethacrylate is quoted as particularly preferred methacrylic acid ester.
Thermoplastic (co)polymers with a composition according to Component B may be formed as a by-product of graft polymerization to produce Component C, particularly when large quantities of monomer are grafted onto small amounts of rubber. The amount of (co)polymer B to be used according to the invention does not include these by-products of the graft polymerization.
The (co)polymers according to Component B are resin-like, thermoplastic and rubber-free.
The thermoplastic (co)polymers B contain 50 to 98, preferably 60 to 95 parts by weight of B.1 and 50 to 2, preferably 40 to 5 parts by weight of B.2.
Particularly preferred (co)polymers B are those consisting of styrene with acrylonitrile and optionally with methyl methacrylate, of xcex1-methylstyrene with acrylonitrile and optionally with methyl methacrylate, or of styrene and xcex1-methylstyrene with acrylonitrile and optionally with methyl methacrylate.
The styrene/acrylonitrile copolymers according to Component B are known and may be produced by radical polymerization, particularly by emulsion, suspension, solution or bulk polymerization. The copolymers according to Component B preferably have molecular weights {overscore (M)}w (weight average, determined by light scattering or sedimentation) between 15,000 and 200,000.
Particularly preferred copolymers B according to the invention are also statistically synthesized copolymers consisting of styrene and maleic anhydride which may be produced from the corresponding monomers by a continuous bulk or solution polymerization with incomplete reactions.
The contents of the two components of the statistically synthesized styrene/maleic anhydride copolymers suitable according to the invention may be varied within wide limits. The preferred maleic anhydride content is 5 to 25 wt. %.
The molecular weights (number average ({overscore (M)}n) of the statistically synthesized styrene/maleic anhydride copolymers according to Component B suitable according to the invention may vary over a wide range. The range of 60,000 to 200,000 is preferred. An intrinsic viscosity of 0.3 to 0.9 (measured in dimethyl formamide at 25xc2x0 C.; see Hoffmann, Krxc3x6mer, Kuhn, Polymeranalytik I, Stuttgart 1977, page 316 ff.) is preferred for these products.
Instead of styrene the vinyl (co)polymers B may also contain ring-substituted styrenes such as p-methylstyrene, vinyl toluene, 2,4-dimethylstyrene and other substituted styrenes such as xcex1-methylstyrene.
Graft polymers C comprise, for example, graft copolymers with rubber-elastic properties, which are substantially obtainable from at least two of the following monomers: chloroprene, buta-1,3-diene, isopropene, styrene, acrylonitrile, ethylene, propylene, vinyl acetate and (meth)acrylic acid ester with 1 to 18 C atoms in the alcohol component; i.e. polymers as are described, for example, in xe2x80x9cMethoden der Organischen Chemiexe2x80x9d (Houben-Weyl), Vol. 14/1, Georg Thieme-Verlag, Stuttgart 1961, p. 393-406 and in C B Bucknall, xe2x80x9cToughened Plasticsxe2x80x9d, Appl. Science Publishers, London 1977. Preferred polymers C are partially crosslinked and contain gel contents of over 20 wt. %, preferably over 40 wt. %, particularly over 60 wt. %.
Preferred graft polymers C comprise:
C.1 5 to 95, preferably 30 to 80 parts by weight of a mixture comprising
C.1.1 50 to 95 parts by weight of styrene, xcex1-methylstyrene, halogen or methyl ring-substituted styrene, C1-C8-alkyl methacrylate, particularly methyl methacrylate, C1-C8-alkyl acrylate, particularly methyl methacrylate or mixtures of these compounds and
C.1.2 5 to 50 parts by weight of acrylonitrile, methacrylonitrile, C1-C8-alkyl methacrylates, particularly methyl methacrylate, C1-C8-alkyl acrylate, particularly methacrylate, maleic anhydride, C1-C4-alkyl- and/or phenyl-N-substituted maleinimides or mixtures of these compounds on
C.2 5 to 95, preferably 20 to 70 parts by weight of polymer with a glass transition temperature below xe2x88x9210xc2x0 C.
Examples of preferred graft polymers C are polybutadienes, butadiene/styrene copolymers and acrylate rubbers grafted with styrene and/or acrylonitrile and/or alkyl (meth)acrylates; i.e. copolymers of the type described in DE-OS 1 694 173 (=U.S. Pat. No. 3,564,077); polybutadienes, butadiene/styrene or butadiene/acrylonitrile copolymers, polyisobutenes or polyisoprenes grafted with alkyl acrylates or methacrylates, vinyl acetate, acrylonitrile, styrene and/or alkyl styrenes, such as are described in DE-OS 2 348 377 (=U.S. Pat. No. 3,919,353).
Examples of particularly preferred polymers C are ABS polymers such as are described in DE-OS 2 035 390 (=U.S. Pat. No. 3,644,574) or in DE-OS 2 248 242 (=GB-PS 1 409 275) for example.
Particularly preferred graft polymers C are graft polymers which are obtainable by graft reaction of
I. 10 to 70, preferably 15 to 50, particularly 20 to 40 wt. %, related to graft product, of at least one (meth)acrylic acid ester or 10 to 70, preferably 15 to 50, particularly 20 to 40 wt. % of a mixture consisting of 10 to 50, preferably 20 to 35 wt. %, related to mixture, of acrylonitrile or (meth)acrylic acid ester and 50 to 90, preferably 65 to 80 wt. %, related to mixture, of styrene, on
II. 30 to 90, preferably 50 to 85, particularly 60 to 80 wt %, related to graft product, of a butadiene polymer with at least 50 wt. %, related to II, of butadiene groups as graft base,
wherein preferably the gel content of the graft base II is at least 70 wt. % (measured in toluene), the degree of graft G 0.15 to 0.55 and the average particle diameter d50 of the graft polymer 0.05 to 2 xcexcm, preferably 0.1 to 0.6 xcexcm.
(Meth)acrylic acid esters I are esters of acrylic acid or methacrylic acid and monohydric alcohols with 1 to 18 C atoms. Methylacrylic acid methyl, ethyl and propyl esters are particularly preferred.
In addition to butadiene groups the graft base II may contain up to 50 wt. %, related to II, of groups of other ethylenically unsaturated monomers such as styrene, acrylonitrile, esters of acrylic or methacrylic acid with 1 to 4 C atoms in the alcohol component (such as methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate), vinyl esters and/or vinyl ethers. The preferred graft base II consists of pure polybutadiene.
The degree of graft G denotes the weight ratio between grafted graft monomers and the graft base and is dimensionless.
The average particle size d50 is the diameter above and below which 50 wt. % of the particles lie in each case. It may be determined by ultracentifuge measurement (W. Scholtan, H. Lange, Kolloid, Z. und Z. Polymere 250 (1972), 782-796).
Examples of particularly preferred polymers C are also graft polymers consisting of
(a) 20 to 90 wt. %, related to C, of acrylate rubber with a glass transition temperature below xe2x88x9220xc2x0 C. as graft base and
(b) 10 to 80 wt. %, related to C, of at least one polymerizable ethylenically unsaturated monomer (cf. C.1) as graft monomer.
The acrylate rubbers (a) of polymers C are preferably polymers of acrylic acid alkyl esters, optionally with up to 40 wt. %, related to (a), of other polymerizable ethylenically unsaturated monomer. C1-C8-alkyl esters, such as methyl, ethyl, butyl, n-octyl and 2-ethyl hexylester; halogen alkyl esters, preferably halogen-C1-C8-alkyl esters, such as chloroethyl acrylate, and mixtures of these monomers, belong to the preferred polymerizable acrylic acid esters.
For crosslinking, monomers with more than one polymerizable double bond may be copolymerized. Preferred examples of crosslinking monomers are esters of unsaturated monocarboxylic acids with 3 to 8 C atoms and unsaturated monohydric alcohols with 3 to 12 C atoms or saturated polyols with 2 to 4 OH groups and 2 to 20 C atoms, such as ethylene glycol dimethacrylate, allyl methacrylate; polyunsaturated heterocyclic compounds such as trivinyl and triallyl cyanurate; polyfunctional vinyl compounds such as di- and tri-vinyl benzenes; but also triallyl phosphate and diallyl phthalate.
Preferred crosslinking monomers are allyl methacrylate, ethylene glycol dimethyl-acrylate, diallyl phthalate and heterocyclic compounds which have at least three ethylenically unsaturated groups.
Particularly preferred crosslinking monomers are the cyclic monomers triallyl cyanurate, triallyl isocyanurate, trivinyl cyanurate, triacryloylhexahydro-s-triazine, triallyl benzenes.
The quantity of crosslinking monomers is preferably 0.02 to 5, particularly 0.05 to 2 wt. %, related to the graft base (a).
In the case of cyclic crosslinking monomers with at least three ethylenically unsaturated groups it is advantageous to limit the quantity to below 1 wt. % of the graft base (a).
Examples of preferred xe2x80x9cotherxe2x80x9d polymerizable, ethylenically unsaturated monomers which may also optionally serve to produce the graft base (a) in addition to the acrylic acid esters, are acrylonitrile, styrene, xcex1-methylstyrene, acrylamides, vinyl-C1-C6-alkylethers, methyl methacrylate, butadiene. Preferred acrylate rubbers as graft base (a) are emulsion polymers which have a gel content of at least 60 wt. %.
Further suitable graft bases are silicone rubbers with graft-active sites, such as are described in published patent applications DE-OS 3 704 657, DE-OS 3 704 655, DE-OS 3 631 540 and DE-OS 3 631 539.
The gel content of the graft base (a) is determined at 25xc2x0 C. in dimethyl formamide (M. Hoffmann, H. Krxc3x6mer, R. Kuhn, Polymeranalytik I and II, George Thieme-Verlag publishers, Stuttgart 1977).
Since in the graft reaction, the graft monomers are not necessarily completely grafted onto the graft base, as is known, according to the invention graft polymers C are also understood to mean those products which are obtained by polymerization of the graft monomers in presence of the graft base.
As flame-proofing agents the moulding compositions according to the invention contain phosphorus compounds according to formula (I),
in which the groups have the meanings quoted above.
The phosphorus compounds according to Component D suitable according to the invention are generally known (see for example Ullmanns Encyklopxc3xa4idie der Technischen Chemie, Vol. 18, p. 301 ff., 1979; Houben-Weyl, Methoden der Organischen Chemie, Vol. 12/1, p. 43; Beulstein, Vol. 6, p. 177). Preferred substituents R1 to R4 comprise methyl, butyl, octyl, chloroethyl, 2-chloropropyl, 2,3-dibromopropyl, phenyl, cresyl, cumyl, naphthyl, chlorophenyl, bromophenyl, pentachlorophenyl and pentabromophenyl. Methyl, ethyl, butyl, phenyl and naphthyl are particularly preferred.
The aromatic groups R1, R2, R3 and R4 may be substituted with halogen and/or C1-C4-alkyl. Particularly preferred aryl groups are cresyl, phenyl, xylenyl, propylphenyl or butylphenyl and also the brominated and chlorinated derivatives thereof.
Independently of each other R5 and R6 preferably mean methyl or bromine.
Y preferably stands for C1-C7-alkylene, particularly for isopropylidene or methylene.
In formula (I), n may be 0 or 1, independently of each other, preferably n is equal to 1.
q may be 0, 1, 2, 3 or 4, preferably q is 0,1 or 2.
N may assume values of 0.1 to 5, preferably 0.3 to 2. Mixtures of different phosphates may also be used as Component D according to the invention. In this case N has an average value of 0.1 to 5, preferably 0.3 to 2. As phosphorus compounds this mixture may also contain monophosphorus compounds (N=0).
Monophosphorus compounds according to formula (I) where N=0 are preferably tributyl phosphate, tris-(2-chloroethyl) phosphate, tris-(2,3-dibromopropyl) phosphate, triphenyl phosphate, tricresyl phosphate, diphenylcresyl phosphate, diphenyloctyl phosphate, diphenyl-2-ethylcresyl phosphate, tri-(isopropylphenyl) phosphate, halogen-substituted aryl phosphates, methyl phosphoric acid dimethyl esters, methyl phosphonic acid diphenyl esters, phenyl phosphonic acid diethyl esters and triphenyl phosphine oxide.
The fluorinated polyolefins E are high-molecular and have glass transition temperatures of above xe2x88x9230xc2x0 C., generally above 100xc2x0 C. Their fluorine contents are preferably 65 to 76, particularly 70 to 76 wt. %. Their average particle diameters d50 are generally 0.05 to 1,000, preferably 0.08 to 20 xcexcm. Generally speaking the fluorinated polyolefins E have a density of 1.2 to 2.3 g/cm3.
Preferred fluorinated polyolefins E are polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene/hexafluoropropylene and ethylene/tetrafluoroethylene copolymers.
The fluorinated polyolefins are known (cf. xe2x80x9cVinyl and Related Polymersxe2x80x9d by Schildknecht, John Wiley and Sons, Inc., New York, 1962, page 484 to 494; xe2x80x9cFluorpolymersxe2x80x9d by Wall, Wiley Interscience, John Wiley and Sons, Inc., New York, Vol. 13, 1970, page 623 to 654; xe2x80x9cModem Plastics Encyclopediaxe2x80x9d, 1970 to 1971, Vol. 47, No. 10A, October 1970, McGraw-Hill, Inc., New York, page 134 and 774; xe2x80x9cModem Plastics Encyclopediaxe2x80x9d, 1975 to 1976, October 1975, Vol. 52, No. 10A, McGraw-Hill, Inc., New York, page 27, 28 and 472 and U.S. Pat. Nos. 3,671,487, 3,723,373 and 3,838,092).
They may be produced by known processes, such as by polymerization of tetrafluoroethylene in aqueous medium with a catalyst forming free radicals, such as sodium, potassium or ammonium peroxydisulphate at pressures of 7 to 71 kg/cm2 and at temperatures of 0 to 200xc2x0 C., preferably at temperatures of 20 to 100xc2x0 C. (For further details see U.S. Pat. No. 2,393,967 for example). Depending on the form of use, the density of these materials may be between 1.2 and 2.3 g/cm3, the average particle size between 0.05 and 1,000 xcexcm.
Preferred fluorinated polyolefins E are tetrafluoroethylene polymers. They have average particle diameters of 0.05 to 20 xcexcm, preferably 0.08 to 10 xcexcm, and a density of 1.2 to 1.9 g/cm3 and are preferably used in the form of a coagulated mixture of emulsions of the tetrafluoroethylene polymers E with emulsions of the graft polymers. C.
Suitable fluorinated polyolefins E which can be used in powder form are tetrafluoroethylene polymers with average particle diameters of 100 to 1,000 xcexcm and densities of 2.0 g/cm3 to 2.3 g/cm3.
To produce a coagulated mixture of C and E, initially an aqueous emulsion (latex) of a graft polymer C with average latex particle diameters of 0.05 to 2 xcexcm, particularly 0.1 to 0.6 xcexcm, is mixed with a finely divided emulsion of a tetrafluoroethylene polymer E in water with average particle diameters of 0.05 to 20 xcexcm, particularly 0.08 to 10 xcexcm; suitable tetrafluoroethylene polymer emulsions conventionally have solids contents of 30 to 70 wt. %, particularly 50 to 60 wt. %. The emulsions of the graft polymers C have solids contents of 25 to 50 wt. %, preferably 30 to 45 wt. %.
The quantity quoted in the description of Component C does not include the content of the graft polymer in the coagulated mixture of graft polymer and fluorinated polyolefins.
In the emulsion mixture the weight ratio of graft polymer C to tetrafluoroethylene polymer E is 95:5 to 60:40. The emulsion mixture is coagulated in known manner, such as by spray-drying, freeze-drying or coagulation by adding inorganic or organic salts, acids, bases or organic solvents miscible with water, such as alcohols, ketones, preferably at temperatures of 20 to 150xc2x0 C., particularly 50 to 100xc2x0 C. If required, drying may take place at 50 to 200xc2x0 C., preferably 70 to 100xc2x0 C.
Suitable tetrafluoroethylene polymer emulsions are conventional commercial products and are offered as Teflon(copyright) 30 N by DuPont, for example.
Finely divided inorganic compounds according to Component F consist of compounds of one or more metals of main groups 1 to 5 and sub-groups 1 to 8 of the periodic system, preferably main groups 2 to 5 and sub-groups 4 to 8, particularly preferably main groups 3 to 5 and sub-groups 4 to 8 with at least one element selected from the group consisting of oxygen, sulfur, boron, phosphorus, carbon, nitrogen, hydrogen and silicon.
Examples of preferred compounds are oxides, hydroxides, hydrous oxides, sulfates, sulfites, sulfides, carbonates, carbides, nitrates, nitrites, nitrides, borates, silicates, phosphates, hydrides, phosphites or phosphonates.
Examples of preferred finely divided inorganic compounds are TIN, TiO2, SnO2, WC, ZnO, Al2O3, AlO(OH), ZrO2, Sb2O3, SiO2, iron oxides, Na2SO4, BASO4, vanadium oxides, zinc borate, silicates such as Al silicates, Mg silicates, one, two, three dimensional silicates, mixtures and doped compounds may also be used. Furthermore these nano-scale particles may be surface-modified with organic molecules, to obtain better compatibility with the polymers. Hydrophobic or hydrophilic surfaces may be produced in this way.
The average particle diameters are not great,r than 200 nm, preferably not greater than 150 nm, particularly 1 to 100 nm.
Throughout, particle size and particle diameter mean the average particle diameter d50, determined by ultracentrifuge measurements according to W. Scholtan et al., Kolloid-Z. und Z. Polymere 250 (1972), p. 782 to 796.
The inorganic compounds may be present as powders, pastes, sols, dispersions or suspensions. Powders may be obtained from dispersions, sols or suspensions by precipitation.
The powders may be incorporated into the thermoplastic plastics by conventional methods, such as by direct mixing or extrusion of the constituents of the moulding compositions and the finely divided inorganic powders. Preferred methods are the production of a masterbatch, e.g. in flame-proofing additives, other additives, monomers, solvents, in Component A or the co-precipitation of dispersions of Components B or C with dispersions, suspensions, pastes or sols of the finely divided inorganic materials.
The moulding compositions according to the invention may contain conventional additives, such as lubricants and mould release agents, nucleating agents, anti-static agents, stabilizers, fillers and reinforcing materials as well as dyes and pigments.
The filled and/or reinforced moulding compositions may contain up to 60, preferably 10 to 40 wt. %, related to the filled and/or reinforced moulding composition, of fillers and/or reinforcing materials. Preferred reinforcing materials are glass fibres. Preferred fillers, which may also have a reinforcing effect, are glass marbles, mica, silicates, quartz, talc, titanium dioxide, wollastonite.
The moulding compositions according to the invention consisting of Components A to F and optionally further known additives such as stabilizers, dyes, pigments, lubricants and mould release agents, fillers and reinforcing materials, nucleating agents and anti-static agents, are produced by mixing the particular constituents in known manner and melt-compounding or melt-extruding them at temperatures of 200xc2x0 C. to 300xc2x0 C. in conventional equipment such as internal mixers, extruders and twin screw extruders, wherein Component E is preferably used in the form of the above-mentioned coagulated mixture.
The moulding compositions according to the invention may optionally contain flame-proofing agents different from compounds of formula (I) in a quantity up to 20 parts by weight. Synergistically acting flame-proofing materials are preferred. Examples of further flame-proofing agents are organic halogen compounds such as decabromobisphenylether, tetrabromobisphenol, inorganic halogen compounds such as ammonium bromide, nitrogen compounds such as melamine, melamine/formaldehyde resins or siloxane compounds. The moulding compositions according to the invention may optionally contain inorganic substances different from the inorganic compounds F, for example, inorganic hydroxide compounds such as Mg, Al-hydroxide, inorganic compounds such as aluminium oxide, antimony oxides, barium metaborate, hydroxoantimonate, zirconium oxide, zirconium hydroxide, molybdenum oxide, ammonium molybdate, zinc borate, ammonium borate, barium metaborate and tin oxide.
The invention therefore also provides a process for producing thermoplastic moulding compositions consisting of Components A to F as well as optionally stabilizers, dyes, pigments, lubricants and mould release agents, fillers and reinforcing materials, nucleating agents and anti-static agents, which is characterized in that after mixing, the components and additives are melt-compounded or melt-extruded in conventional equipment at temperatures of 200 to 300xc2x0 C., wherein Component E is preferably used in the form of a coagulated mixture with Component C.
The individual constituents may be mixed in known manner both successively and simultaneously, and at both approx. 20xc2x0 C. (room temperature) and at higher temperature.
The moulding compositions of the present invention may be used to produce moulded bodies of all kinds. In particular moulded bodies may be produced by injection moulding. Examples of moulded bodies which can be produced are: housing components of all kinds, such as for domestic appliances such as juicers, coffee machines, mixers, for office machines such as computers, printers, monitors or cover panels for the building sector and components for the motor vehicle sector. They are also used in the field of electrical engineering because they have very good electrical properties.
The moulding compositions are particularly suitable for producing thin-walled moulded parts (e.g. data processing housing parts) where the plastics used are required to meet particularly high demands as regards notch impact strength and resistance to stress cracking.
A further form of processing is the production of moulded bodies by blow-moulding or by thermoforming from previously produced sheets or films.

Flame and stress crack resistant polycarbonate molding compositions


The invention relates to a preparation for chemical-mechanical treatment of caries by means of a caries-dissolving two-component liquid. One of the components is an active, caries dissolving component and the other a component which reduces the aggressiveness of the active component to mucous membranes. The active component is a chloride compound comprising active chlorine, i.e. chlorine having a charge state of +1, Cl(+1), which chloride has a somewhat lower reactivity than sodium hypochlorite and then also a somewhat reduced dissolving effect on the carious substance.

The present invention relates to a preparation for chemical-mechanical treatment of caries by means of a caries-dissolving two-component liquid in the form of an active, caries dissolving component and a component which reduces the reactivity and the aggressiveness of the active component to healthy tissue.
In traditional caries treatment the attacked tooth substance is removed mechanically by means of a high-speed drill. Such a caries treatment is often a painful and unpleasant experience for the patient. Some of the patients feel so uncomfortable with the treatment that they wait far too long before they go to the dentist, which means that it is often too late to save the caries attacked teeth. Extraction of the teeth is then the only treatment method that is left.
However, there are other methods which are based on a chemical-mechanical treatment for the removal of the caries attacked tooth substance. A method of this type is described in SE 460258. According to this method a two-component liquid is mixed and then immediately applied on the caries lesion. Functioning in a biological way, the liquid makes the caries attacked substance soft without causing any damage to the tooth or the soft tissue. After 10-15 seconds the dentist can start removing the softened carious substance by scraping. The scraping procedure continues until all carious substance has been removed. Then the cavity is sealed with a suitable filling material.
According to the patent the two-component liquid consists of a sodium hypochlorite component and an amino acid component. The amino acid component consists of three amino acids with different charge states in the side chain. The object of the amino acids is to reduce the reactivity of the hypochlorite component, and then also the aggressivity, to healthy tissue and to direct the desired effect to proteins. This is achieved by a chlorination of the amino groups in the amino acids by the hypochlorite which is then consumed.
Unlike the conventional mechanical caries treatment this biological treatment method is usually not painful at all. Neither does it require any investments in expensive equipments.
According to the treatment method the mixed two-component liquid is applied in drops on the tooth so that the entire carious lesion is covered and the caries affected tissue is softened. After 10-15 seconds a mechanical removal of the softened carious substance can be started. The softened carious dentine (the tooth substance) is removed with the use of a scraping instrument. After some scraping the solution becomes turbid due to suspended carious substance and can be exhausted by suction or wiped away.
The above steps are repeated until the solution remains clear. In order to minimize any discomfort and pain for the patient any removal of the solution by means of a cold air stream or cold water flushing should be avoided. Instead, cotton pellets are used to remove the solution. When the carious substance has been completely removed the cavity is sealed with a suitable filling material.
For most carious lesions the treatment has to be repeated in several steps until the solution remains clear. Due to the repetition of the procedure a relatively large volume of the two-component liquid is required. Since the liquid has a low viscosity it is easily dispersed outside the carious lesion and there is a risk for liquid waste on the surrounding tissue. It might be difficult and/or time-consuming for the dentist to remove such a solution which has been spread or which has been unintentionally spilt outside the carious lesion.
In order to facilitate the handling of such a two-component liquid it is previously known to add a viscosity increasing substance (gel substance) and a coloring agent to the liquid, see SE 96.04210-6. The gel substance should then have such properties that the aggressive influence of the sodium hypochlorite on mucous membranes is reduced, preferably it is a carboxy methyle cellulose, and the coloring agent should have the ability to interact with the carious substance. According to a preferred embodiment the coloring agent consists of Erythrosin (E 127 B).
In addition to the fact that the gel substance and the coloring agent facilitate the application of the preparation by making it more visible and viscous, they have also other advantages in connection with the removal of carious substance. During the treatment of the carious lesion with the additional gel substance the turbidity that appears is an indication of the fact that still more carious tooth substance has to be removed. More gel substance is then applied until no more turbidity appears. This is an indication that all carious substance has been removed. The coloring agent has been introduced for indicating carious tooth substance, in the tooth itself before it has been removed, but also in the gel substance to make the turbidity more visible as the suspended particles in the solution are colored.
Even if it is previously known to use other reactivity reducing components than the above-mentioned amino acids, for instance a gel component according to Swedish patent application 98.00025-0, sodium hypochlorite has been used so far for the active component. The advantage by using sodium hypochlorite is the fact that it has a high reactivity and therefore a rapid and efficient effect on caries. The disadvantage, on the other side, is the fact that it is rapidly consumed so that it might be difficult to control the treatment procedure.
The high reactivity of sodium hypochlorite means that it breaks down almost everything in its way, which makes it toxical in biological tissue. It must be handled very carefully in order to avoid the risk of corroding effects. It must be stored cold and in darkness.
It is an object of the present invention to provide a carious-dissolving preparation which is more easy to handle and which reduces the risk of damaging or affecting biological tissue outside the carious lesion.
It has then turned out that also other chloride compounds than sodium hypochlorite which comprises active chlorine, ie chlorine with a positive charge +1, Cl(+1),xe2x80x94when mixed with a suitable reactivity reducing componentxe2x80x94have a caries dissolving effect. It has not previously been expected that these types of chloride compounds should have a sufficient caries dissolving effect as the reactivity, from a general point of view, is lower than for sodium hypochlorite. However, the lower reactivity also increases the lifetime of the mixture (preparation), reduces the formation rate of chloramine so that the time for action increases. This, in turn, means that the reaction zone of the treatment is increased which makes the treatment procedure more easy and simple to control. The preparation can be used more effectively and makes the treatment as a whole as effective as the use of the more reactive sodium hypochlorite.
Such a xe2x80x9cdelayed reactionxe2x80x9d of the preparation can be especially useful for certain types of carious lesions, such as carious lesions with mineralized zones, in which case the preparation is allowed to act on these zones for a comparatively long time compared to previous treatment procedures.
It can also be especially benefical to use the preparation in such cases in which a somewhat lower reactivity is desired for other reasons, for instance in the treatment of patients with specifically sensitive mucous membranes.
A further advantage by using this type of chlorine compounds instead of sodium hypochlorite is the fact that the component is more easily handled and the storage durability is prolonged.
According to the invention the preparation consists of a chloride compound component of active chlorine, ie chlorine having a charge state of +1, Cl(+1), which chloride has a somewhat lower reactivity than sodium hypochlorite and then also a somewhat reduced dissolving effect on the carious substance, and a reactivity reducing component which, when mixed with the chloride compound component, interacts with the chloride compound, and gives rise to compounds containing active chlorine which, while retaining a caries-dissolving quality, does not show the aggressiveness of chloride compounds towards mucous membranes.
xe2x80x9cActive chlorinexe2x80x9d or chlorine having a charge state of +1, Cl(+1), is too reactive to exist as a free ion. However, it exists in many combinations with other atoms, with different reactivity, such as in simple salts, usually together with oxygen. Some examples of such chloride compounds is potassium hypochlorite (KOCl), calcium hypochlorite (Ca(OCl)2) and ammonium hypochlorite (NH4OCl). However, the chlorine ion can also be bound to carbon, oxygen or nitrogen in an organic compound. Examples of such chloride compounds are substituted dichloramine (RNCl2, where R is some other chemical compound or structure, bound to nitrogen, N, for instance a carbon chain), single chloramine (NH2Cl), substituted (mono)chloramine (RNHCl) or the like. A common feature for these chloride compounds is the contents of active chlorine and a reactivity which is less than the reactivity of sodium hypochlorite.
The object of the reactivity reducing component is to reduce the aggressivity of the preparation to healthy tissue and direct the desired effect towards proteins. This object can be achieved according to the above-mentioned SE 460258 by chlorination of the amino group of the amino acids. However, the acid itself in the amino acid compounds, ie the carboxy group which per definition belongs to each amino acid, has primarily nothing to do with the desired reactivity reducing function, other than affecting the ion activity of the solution and the pH buffering, which also can be achieved by other means. It is the amino part of the amino acid which is chlorinated, and such chlorination is the same for all amines and not just for amino acids. All chloramines then have a potential caries dissolving effect. According to the invention therefore the reactivity reducing component is preferably a component comprising amines, ie compounds comprising NHx, where x=1, 2 or 3, and which can be bound to one or several other chemical compounds, for instance carbon chains.
Another example of a suitable reactivity reducing component is a gel substance component known per se, for instance 2-10% carboxy methyl cellulose which concentration is sufficient for the gel substance alone to reduce the aggressive influence of the sodium hypochlorite on mucous membranes. Preferably, the gel substance component also comprises a coloring agent of 0.04% Erythrosin (E 127 B), acid red or Xantene. Such a component is described more in detail in SE 96.04210-6.
Even if the life-time of the caries-dissolving solution according to the invention is somewhat longer than the previously used preparations it is important that the solution is used immediately in order to have a good effect. In this connection the carboxy methyl cellulose has the advantage that the viscosity of the gel is dramatically reduced when the solution mixed with the chloride compound component gradually becomes inactive with respect to its caries-dissolving ability. The degradation will be clearly visible after approximately 30 minutes in room temperature as the liquid then has lost most of its viscosity. The gel substance then functions, as previously, as an indicator when the solution becomes inactive for caries dissolution.
In the following two examples of a caries dissolving two component solution according to the invention will be described more in detail, in which the reactivity reducing component has been indicated by A and the active component by B.
As illustrated in the example the active component is a chloride compound, 0.5% calcium hypochlorite (example 1) and 0.5% potassium hypochlorite (example 2), respectively.


A pedicle-screw assembly has a screw extending along an axis and having a threaded shaft and a round head, an inner cap part carried on the head and swivelable on the head, and an outer cap part forming with the inner cap part a seat adapted to hold an end of a distraction/stabilizing rod. The outer cap part has formations engageable in a snap fit over the inner cap part, and an element on the outer cap part can be tightened to fix the rod in the seat. The outer cap part is generally U-shaped and formed with a base forming the seat and a pair of legs projecting parallel to the axis, flanking the cap inner part, and having ends engaged in a snap fit around sides of the cap inner part.

The present invention relates to a pedicle screw assembly.
A standard pedicle screw assembly comprises a screw having an externally threaded stem having in turn a head provided with parts allowing it to be secured to one end of a distraction rod. Two such screws inserted into respective vertebrae are secured to such a rod to distract and/or stabilize a spinal column after, for instance, a disk operation.
In a standard such assembly as described in German patent document 4,107,480 the head of the screw has a pair of outwardly projecting parallel ridges with overhanging inner edges. A cap formed with a pair of complementary inwardly open slots that can fit with these ridges has a part-cylindrical recess forming with another part-cylindrical recess on the head of the screw a seat for the rod. The screw is threaded into the vertebrae, an end of the rod is fitted to its outer end, the cap is then slid transverse to the screw axis and parallel to the rod over the rod to capture it, and finally a screw threaded into the cap is tightened to press the rod down against the head of the screw and thereby fix the rod, cap, and screw together.
Since the cap of this system must be slid transversely onto the head of the screw, it is necessary to open the operating field sufficiently to allow such movement. This not only increases the extent of the surgery, but makes it impossible to install two such screws close to each other, for instance on adjacent vertebrae. Furthermore in most systems the actual position of the screw is critical as the rod can only be fitted to it in a limited range of positions.
It is therefore an object of the present invention to provide an improved pedicle screw.
Another object is the provision of such an improved pedicle screw which overcomes the above-given disadvantages, that is which can be installed in very close quarters.
A pedicle-screw assembly has according to the invention a screw extending along an axis and having a threaded shaft and a round head, an inner cap part carried on the head and swivelable on the head, and an outer cap part forming with the inner cap part a seat adapted to hold an end of a distraction/stabilizing rod. The outer cap part has formations engageable in a snap fit over the inner cap part, and an element on the outer cap part can be tightened to fix the rod in the seat.
With this system once the pedicle screws are set, the rod ends can be fitted to the inner cap parts which can be swiveled to accommodate any necessary angular offset. Then the outer cap parts are snapped in place and the assembly is tightened to lock the rod in place. The outer cap part does not have to be slid transversely into position but is moved normally generally axially as it is snapped over the inner cap part, so that little clearance is needed and the operating field does not have to be expanded to accommodate such movement.
The screw head according to the invention has an inner region with a part-spherical outer surface and an end face lying on a plane substantially perpendicular to the screw axis. The head is formed on the end face with a central part-spherical bump centered on the axis. In addition the outer cap part is generally U-shaped and formed with a base forming the seat and carrying the fixing means and a pair of legs projecting parallel to the axis, flanking the cap inner part, and having ends engaged around sides of the cap inner part. Each of the legs has an outer end that hooks under an edge of the respective side of the cap inner part. The outer cap part is formed parallel to and adjacent each leg with a groove so that lateral elastic deformation of the leg is increased.
Interengaging formations on the cap parts block movement of the cap parts relative to each other transverse to the axis. Furthermore, the outer and inner cap surfaces have confronting side faces. The interengaging formations include at least one axially extending ridge on one of the faces and a complementary axially extending slot on the face confronting the one face. The one face having the ridge is on the inner cap part although of course the reverse system would be usable.
The head and inner cap part have surfaces that engage each other and that are roughened. The fixing means is a screw threaded into the outer cap part and tightenable to pull the roughened surfaces of the inner cap part and head axially together. Thus when the assembly is tightened, the cap can no longer swivel on the screw.
The outer and inner cap parts are formed with confronting part-cylindrical concavities forming the seat. The inner cap-part concave seat half has a throughgoing aperture. The fixing screw presses the rod in the seat against the bump. To maximize the range of relative angular position the screw is formed at a base of the head with an annular inset so as to allow a wide range of swiveling of the cap on the head.


A porous layer produced from silicon, germanium or aluminum by applying a wedge-shaped mask to the surface of the layer and by controlled elecrochemical etching along the mask.

1. Field of the Invention
The invention relates to a process for producing a porous layer with the aid of an electrochemical etching process. The invention also relates to an optical component.
2. Description of the Related Art
A process for producing a porous layer with the aid of an electrochemical etching process as well as a process is known.
As state of the art it is known, for example, to produce porous silicon (PS) by electrochemical etching of silicon wafers, especially for the use in the production of computer chips. Layers formed in this manner have a structure similar to a sponge and manifest a multiplicity of interesting characteristics.
One field of application for PS is its use in optical components. It is known, for example, from DE 43 19 413.3-33 or Thin Solid Films, 276 (1996), 143-146 to produce waveguides, transmission filters, reflectors or antireflection layers using layer systems of PS. The optical characteristics of the layer system can be varied by the sequence of individual layers with different optical thicknesses.
The optical thicknesses of these individual layers are influenced for a given doping by their porosities and thicknesses. The porosities and thicknesses are controlled for a predetermined doping by the current density or the duration of the electrochemical etching. With control of the duration of the etching only it is possible, for a predetermined substrate and predetermined current density, to set the desired layer thickness. So as to integrate PS with other components, the surface which is to form such structure by etching must be defined. The conventional structuring of the substrate prior to producing the porous layer with an etching mask gives rise to a curvature of the PS/substrate interface during production (FIG. 1). In experiments, strips of a length of 1 cm and a width corresponding to the respective spacings from the next strip were investigated. As can be seen from FIG. 1, there exists two curvatures, one curvature within a strip and a curvature over all of the strips. These curvatures result disadvantageously in an inhomogeneity of the layer (see FIG. 5).
If the characteristic structure is 100 xcexcm or smaller, the PS/substrate interface is straight (FIG. 2). In the process whereby interface curvature can occur, these small structures can no longer be resolved. For the use of PS which lies below this order of magnitude, the problem of an inhomogeneity of filters and reflectors because of interface curvature no longer exists.
From FIG. 2 it can be seen that a structuring with photolacquer gives rise to a significant underetching of the etching mask. This can be limited by the use of another etching mask material, e.g. silicon nitride (Si3N4), (see M. Krxc3xcger et al, Thin Solid Films 276 (1996) 257-260). With the aid of this mask technique it is possible to fabricate a structure from PS which has both a straight PS/substrate interface and also vertical etching flanks. With these conditions a production of layer systems from porous silicon is possible whose characteristics can be previously determined.
As to production of a multiplicity of porous regions on the same wafer, in the past they could be made only if they were to have the same characteristics. If it was intended that these regions were to constitute pixels of different characteristics, for example, for a filter array of a porous layer system, these could not be simultaneously etched. This resulted in the drawback that previously made porous layers had to be covered so that they would maintain their characteristics during the etching of the new pixels. This procedure is very difficult and expensive to realize and up to now has not truly been possible, since this covering must be removable without leaving residues on the porous layer.
It is thus the object of the invention to provide a process for producing a porous layer with the aid of an electrochemical etching process in which the aforementioned drawbacks are avoided.
The etching for porosidizing the material is carried out in accordance with the invention using an etching mask. It has been recognized that an etching mask of suitable geometry for the desired characteristics of the deep etching must be formed and used in the process of the invention.
It is further noted within the framework of the invention that the simultaneous formation of pixels within a porosidizable structure with different characteristics is possible in a single working procedure when the etching rate of each pixel is not predetermined only by the externally applied current density but is also collaterally determined by the different environments of the pixels. The environments of the pixels can be so formed by the etching mask that the pixels are subject to different current densities and thus have different etching rates. In this manner the desired different characteristics can be generated.
In this way the process according to the invention enables multiple, especially many, working steps to be replaced by a single step of suitable configuration. A further advantage of this process is that a continuous modification of the characteristics of a porous layer is possible. This process can be used for all electrochemical etching procedures.
According to the invention, the process for producing a porous layer with the aid of an electrochemical etching process can use an etching mask for the desired course of deep etching.
According to another aspect of the invention the process according to the invention is advantageously configured in that a wedge-shaped etching mask is selected to provide a continuous course of the deep-etching rate.
According to another feature, the process of the invention is characterized advantageously in that, for the formation of a discrete course of the deep-etching rate, one or a plurality of wedge-shaped step-shaped structured etching masks are used.
The process according to the invention is advantageously so carried out that silicon, germanium or aluminum is selected as the starting material for porous layer formation. These materials have comparatively well known properties with respect to etching.
Optical components with the layer according to the invention are also deemed to be within the invention.

Process for producing a porous layer by an electrochemical etching process


The invention provides an adhesive made from a liquid catalyst cross-linked with an amino resin. The liquid catalyst has improved flexibility and adhesive properties, which are imparted on the adhesive. It is comprised of a cross-linkable polyvinyl acetate, an acid, and an ammonium salt.

This invention relates to the field of adhesives and more particularly to adhesives made by cross-linking liquid catalysts with amino resins.
Amino resins are used in the area of wood products including particleboard, hardwood, plywood, decorative laminate, furniture assembly, etc. Amino resins are supplied in liquid form and are combined with a catalyst at the time of use to form an adhesive substance that is applied to the wood product. This adhesive substance provides adhesion between wood surfaces.
The catalysts are either acidic substances or other materials capable of liberating free acid upon addition to the amino resin. The acidic property of the catalyst promotes cross-linking amino resins and accordingly, the cross-linking or setting of the adhesive substance so that the adhesive substance has the necessary high strength, water resistance and cold flow resistance in order to meet its necessary applications. For example, hardwood floors used for flooring in truck trailer, truck bodies and shipping containers are laminated using a catalyst/amino resin with high strength cross-linking. The quality of lamination can then be verified using Fruehauf Engineering Standards, with one of the most important criteria being the wet shear strength.
The amount and type of catalyst used determines whether the adhesive bond can be cured at room temperature or at higher temperatures. Cure time may vary from a few minutes at high temperatures to a few hours at room temperature. In an application where high frequency heating is required, as for example with laminated pieces of wood flooring, it is common to reduce the time required to cure the adhesive substance.
Current catalysts used in combination with amino resins are in powder form.
A major drawback with a powder catalyst is that powders are not easy to manipulate. Mass transfer of powder materials requires special equipment and/or more human manipulations.
Also, powder catalysts pose certain problems in terms of dust formation during transfer, which may cause toxic effects on humans (irritating mucous membranes and upper respiratory tract).
Care must always be taken to mix homogeneously the blend of powder catalyst and liquid amino resin to avoid any lumping of powder, which will cause a burn or an arc if high frequency heating is used.
While the use of a high level of powder catalyst imparts lower setting time, the amount of powder catalyst mixed with the amino resin is limited to about a maximum of 15% by weight. Increasing the amount of powder catalyst above 15% by weight increases the viscosity and reduces the pot life of the mixture, but decreases the adhesivity and strength of the mixture. Moreover, powder catalysts do not contribute any adhesive property to the mixture and a higher concentration of powder catalyst reduces the relative amount of amino resin in the mixture and therefore reduces the adhesive performance of the resulting mixture.
When properly cured, the resulting bond of the amino resin cross-linked with a powder catalyst is hard and brittle and is characterized by a low impact strength and low elongation point prior to breakage.
Accordingly, there remains a need to develop a catalyst that is commercially beneficial for the wood glue industries and which can be easily mixed at a relatively high concentration with a liquid amino resin to provide a resulting adhesive substance with an adequate viscosity, pot life, and setting time. There also remains a need to provide a catalyst that reduces the cycle time of a high frequency heating press, while contributing adhesive properties to the final adhesive substance.
It is an object of one aspect of the present invention to provide an adhesive with improved properties.
It is a further object of one aspect of the present invention to provide a catalyst with improved cross-linking capabilities and properties that facilitate mixing with an amino resin.
According to one aspect of the present invention, there is provided an adhesive substance made from mixing a liquid catalyst comprising between 52 and 93% of a copolymer, between 3 and 14% of an acid, and, between 4 and 14% of an ammonium salt, with an amino resin.
In a preferred embodiment of the present invention, the liquid catalyst provides adhesive properties to the catalyst/amino resin mixture and it provides excellent bond strength and excellent water resistance to the adhesive substance.
The present invention provides an adhesive made by cross-linking a liquid catalyst with an amino resin. The liquid catalyst is a composition comprised of a copolymer, acid, and ammonium salt. In a preferred embodiment, the liquid catalyst has a storage life of a minimum of three months.
In a preferred embodiment of the present invention, the liquid catalyst composition comprises the following components (all percentages are in weight % to a total of 100%):
(A) Copolymer:
The copolymer is the primary component of the liquid catalyst. It is preferably present in an amount ranging from about 52 to 98 weight %. Most preferably, it is present in an amount of 70 to 78 weight %.
In a preferred embodiment, the copolymer is comprised of vinyl acetate and a comonomer capable of crosslinking. An example of a suitable comonomer is N-methylolacrylamide, which shows improved crosslinking capabilities with polyvinyl acetate.
The polyvinyl acetate and comonomer form an emulsion that is self-crosslinkable. The emulsion functions as a water resistant adhesive, thereby improving the adhesivity and impact strength of the liquid catalyst over the non-adhesive powder catalysts used in the prior art.
A commercially available source of copolymer is the self cross-linking poly-vinyl acetate dispersion available under the trade-mark P-1036(trademark) from Dural, a division of Multibond Inc. This copolymer is a dispersion in water having a solids content of about 51% (51xc2x11%), a pH of 4.0 to 5.0, a Brookfield viscosity at 25xc2x0 C. (spindle 5 at 20 rpm) of 8,000 to 12,000 cps, an average particle size of 0.8xcexc, and a minimum film forming temperature of +15.6xc2x0 C. The copolymer dispersion is non-ionic with a density of 1.07 g/cm3. It has a stabilization system based on polyvinyl alcohol.
N-methylolacrylamide is purchased at a concentration of 48%. The amount of N-methylolacrylamide based on the weight of vinyl acetate may vary from 3 to 10%.
It will be apparent to one skilled in the art that other copolymers may be used within the confines of the invention without deviating from the invention as claimed. For example, a self-crosslinking polyvinyl acrylic or polyacrylic may be used as part of the copolymer dispersion.
(B) Acid:
In a preferred embodiment, the liquid catalyst includes an acid such as citric acid, commercially available under the name citric acid anhydrous. It is present in the liquid catalyst in an amount ranging from 1 to 14 weight %, and preferably in an amount of from 4 to 7 weight % of the liquid catalyst.
The acid is useful in the liquid catalyst because it initiates hardening of the catalyst-amino resin mixture by improving the cross-linking reaction with the amino resin.
A commercially available source of citric acid anhydrous is available from ADM Food Additive Division. It has a solubility in water of 162 g/100 ml at 25xc2x0 C., with a maximum water content of 0.5%, and a maximum lead content of 0.5 ppm. Another suitable acid is salicylic acid.
(C) Ammonium Salt:
In a preferred embodiment, the liquid catalyst also includes an ammonium salt. The preferred ammonium salts are ammonium salts derived from strong acids, such as, ammonium chloride and ammonium sulfate. The ammonium salt cross-links with the amino resin and improves the overall cross-linking of the liquid catalyst. It is preferably present in an amount ranging from about 2 to 14 weight %, and most preferably from 4 to 7 weight % of the liquid catalyst.
It has been found that an amount of ammonium salt higher than 14% results in loss of stability. It shortens the pot life of the liquid catalyst-amino resin mixture and shortens the storage life of the catalyst.
A commercially available source of the ammonium salt is ammonium chloride sold by Van Waters and Rogers, which has a specific gravity of 1.53 g/cm3, a pH of 5.5 in 1% water and a boiling point of 520xc2x0 C.
(D) Ionisable Salt:
The liquid catalyst may also contain an ionisable metal salt, such as sodium chloride. An ionisable metal salt is required if the resulting adhesive substance will be cured using high frequency heating. The ionisable metal salt is employed to adjust the electrical conductivity of the adhesive substance when high frequency heating is used to cure the adhesive substance.
The ionisable metal salt may be present in an amount ranging from about 0 to 3%, and preferably from 1.5 to 3 weight % of the liquid catalyst. It has been found that an amount greater than 3% results in burning and arcing when high frequency heating is used.
(E) Inert Filler:
The liquid catalyst may also contain an inert filler such as nut shell flour or fine hardwood flour. The inert filler may be present in an amount ranging from 0 to 1 weight % and preferably from 0.8 to 1 weight % of the liquid catalyst.
The inert filler thickens the resulting adhesive substance and acts like a water retention agent to hold the adhesive substance in place when it is under heat. Water retention is advantageous to the extent that the rapid heating of the resin mix in the glue line when exposed to high frequency heating will thin, increasing its viscosity. The thinning may take place faster than the chemical action of the resin setting. In such cases, the walnut shell flour or the fine hardwood flour acts as a sponge to hold the adhesive substance in place.
(F) Water:
The liquid catalyst may also include water from the aqueous dispersion of the copolymer and additional water to adjust the solid content and viscosity of the mixture. Total water content is preferably in an amount ranging from 0 to 16 weight %, and most preferably from 10.5 to 14 weight % of the liquid catalyst.
(G) Defoamer:
If necessary, the liquid catalyst may also contain defoamer to prevent excessive foaming during mixing of the liquid catalyst with the amino resin. A commercially available source of a suitable defoamer is Napco NDW, sold by Henkel.
(H) Buffer:
If necessary, the liquid catalyst may also contain a buffer such as tricalcium phosphate for adjusting the pH of the liquid catalyst. A commercially available source of a suitable buffer is tricalcium phosphate, sold by Albright and Wilson.
Amino Resin:
The liquid catalyst is crosslinked to an amino resin to form the resulting adhesive substance. An amino resin is a resin made from the condensation of an amine group with a carbonyl compound and an alcohol. The most commonly used amine compounds are urea, melamine, benzoguanamine, glycoluril, cyclic ureas, thioureas, guanidines, urethanes, cyanamides, etc. The most commonly used carbonyl compounds are aldehydes such as formaldehyde. The most commonly used alcohols are methanol, ethanol and butanol.
Typical amino resins that are used for cross-linking the liquid catalyst include urea formaldehyde resins or melamine urea formaldehyde resins.
Commercial resins exist as mixtures of polymers where each polymer is comprised of many monomers. Each monomer is then a dimer or trimer. The liquid catalyst works with the amino resin, independently of the ratio of dimers/trimers.
The amino resins are usually supplied in liquid form having a solid content of 50-65% and a storage life of about 3 months at 20xc2x0 C.
The Preparation of the Adhesive
In operation, the resulting adhesive substance made from the liquid catalyst of the present invention can be applied with the same conventional equipment as that used with powder catalysts.
The liquid catalyst is pre-mixed to form a uniform composition. The liquid catalyst is then added to an amino resin so that preferably a 20-25% composition of liquid catalyst by weight is present in the mixture.
The combined liquid catalyst and resin are then mixed to create a homogeneous composition. At this stage, the nature of the liquid catalyst is advantageous over powder catalysts used in the prior art in that powder catalysts often form lumps within the adhesive substance which results in arcing when the adhesive application is treated in a high frequency press.
The resulting adhesive substance is then fed into a roller applicator where it is applied to the wood surface. The wood is then transferred to a high frequency press or hot press for drying and curing.
Typically, a high frequency press is used to laminate pieces of wood for an application such as a truck flooring. High frequency heating provides a method for raising the temperature of materials that are normally electrical insulators by placing these materials between metal plates and applying radio frequency voltage. It facilitates coherent electromagnetic radiation of energy. In general, the temperature of the wood in the high frequency press is 165xc2x0 F. to 210xc2x0 F.
The use of a high frequency press is expensive. In general, it takes 165 seconds for one cycle of a high frequency press using a powder catalyst-amino resin mixture. With a liquid catalyst present in a 20-25% weight composition, the time required for high frequency pressing is reduced to 120 seconds per cycle, thereby significantly decreasing the cost of curing.
A hot press is used for applications that do not require lamination on the edges of the wood. A hot press is suitable for applications such as face lamination which application may be made to plywood.
The liquid catalyst of the present invention is advantageous in the above processes in that it facilitates mixing with the amino resin. In addition, the use of a liquid catalyst, and in particular the addition of polyvinyl acetate within the catalyst pre-mix, improves adhesivity and cross-linking the amino resin. Improved cross-linking decreases the cold flow between molecules and accordingly, improves the strength of the catalyst-amino resin mixture.
As shown in Example 1, the viscosity of the liquid catalyst/amino resin mixture is decreased two-fold over that of the powder catalyst/amino resin mixture. Viscosity, being a measure of resistance to flow, is important for maintaining the adhesive properties of the resulting adhesive substance. If the adhesive substance is too viscous, the adhesive will not wet the wood. If the adhesive is too liquid, it will soak into the wood, thereby also proving ineffective.
In addition, as shown in Examples 2, 3 and 4, the wet shear strength of the liquid catalyst/amino resin is improved over that of the powder catalyst/amino resin used in the prior art. According to the Fruehauf Engineering Standards, the minimum required wet shear is 525 psi while the liquid catalyst/amino resin combination of the present invention (with 22% liquid catalyst and 78% amino resin) has a wet shear that is two to three times the minimum strength. The dry shear is also 10% higher than that of powder/amino resin catalysts. Additionally, in most cases, the dry shear and wet shear provide 100% wood shear failure, which is indicative of excellent shear strength.
In a preferred embodiment, the pot life, or time elapsing between the time the resulting adhesive substance is ready for use and the time when the mixture is no longer useable is at least 45 minutes.
It is recommended that the liquid catalyst be mixed with the amino resin at temperatures between 16 and 30xc2x0 C. where the composition of the catalyst is in its liquid state.

Adhesive made from cross-linking liquid catalyst with amino resin


A fiber optic catheter has a short guide wire lumen (less than 10 cm) extending in a proximal direction from its distal end and an intermediate portion reinforced with a tapered mandrel which provides optimal steerability and trackability characteristics. The distal end of the mandrel is coextensive with a proximal portion of the guide wire lumen. The intermediate portion of the catheter may have a marker for visual identification, and the tip of the catheter may include a radiopaque tip marker band for fluoroscopic identification. The short guide wire lumen catheter provides superior flexibility, a low profile, and low-friction engagement with the guide wire.

1. Field of the Invention
The present invention relates to catheters used for surgical operations, and more specifically, to fiber optic catheters used for illuminating and ablating intravascular regions and means for guiding and positioning such catheters.
2. Description of the Related Art
Percutaneous transluminal coronary angioplasty (PTCA) is a technique for opening arterial constrictions and partial blockages called stenoses that arise from deposition of cholesterol and fibrous tissue in the walls of coronary arteries.
The human heart has three main coronary arteries which supply oxygenated blood to the heart. The opening in the aorta which marks the origin of the coronary arteries is called the ostium. In PTCA, the operator makes a puncture in an artery (usually a femoral artery in the groin) and passes a catheter up the artery past the ostium and into the coronary artery. The catheter may be a balloon catheter having at its end a balloon which, when inflated at the position of the stenosis, causes compression, stretching and splitting of the stenotic material and often expansion of the arterial wall, thereby enlarging the blood flow channel. Alternatively, the catheter may be a fiber optic catheter which uses optical fibers disposed within the catheter body to deliver energy from a source of high-intensity light (e.g., a laser) to the stenosis to ablate it. The catheter may also be of the cautery type, which uses a heated element to burn the stenosis away.
PTCA is an established technique and is used as an alternative to a bypass operation in which a section of vein, usually from the patient's leg, is used to bypass the stenosis. PTCA is performed by cardiologists and radiologists whereas by-pass surgery is carried out by cardiac surgeons. The patient in PTCA only has a local anesthetic for insertion of an introducer sheath into the femoral artery. Thereafter, a guide catheter is fed through the sheath to the ostium. The guide catheter is followed by the catheter. After successful dilatation, the patient is kept in the hospital for only one or two days and can return to work within about a week. Thus, the benefit of PTCA can be seen by contrasting it with bypass surgery which requires major surgery under full anesthesia, one or two weeks in hospital, and a substantial period of convalescence.
One type of PTCA catheter is the over-the-wire (OTW) catheter. An OTW balloon catheter has two lumens, one for inflation of the balloon at its distal end and the other for passage of a guide wire. An OTW fiber optic catheter has a coaxial lumen including an innermost lumen for the passage of a guide wire surrounded by optical fibers encapsulated by the outer lumen.
When an OTW catheter is used in PTCA, a puncture is made (again, usually in the femoral artery) and a guide catheter about 100 centimeters long is inserted into the puncture and passed into the ostium. The OTW catheter (about 135 centimeters long) is threaded over the guide wire (about 175 centimeters long) and the catheter and the guide wire are passed up the guide catheter to the ostium. Then, the guide wire is carefully slid down the coronary artery past the stenosis. The OTW catheter is slid out of the guide catheter and down the guide wire until its distal end is at the site of the stenosis. Then, in the case of a balloon OTW catheter, the balloon is inflated to dilate the artery as described above. In the case of a fiber optic catheter, the distal end of the catheter delivers light energy to the stenosis to ablate and remove it.
OTW catheters are a considerable advance over fixed wire catheters, since the guide wire can be positioned and manipulated independently to ensure that the correct artery is selected. OTW catheters also enable a doctor to monitor the position of the catheter more easily than can be done with a fixed tip design. To ensure that a fixed tip catheter is properly positioned, the doctor has to inject X-ray contrast fluid at frequent intervals. This is not obviated by the over-the-wire catheters per se, but the use of a guide wire does enable the doctor to see the wire on an X-ray fluoroscopy screen, thereby allowing him or her to control the position of the catheter.
During a PTCA procedure, it is often necessary to change OTW catheters. With conventional OTW designs, the doctor cannot withdraw the catheter while leaving the guide wire in place without significant effort. Thus, the doctor must first attach an extension to the guide wire so that the total length is about 300 centimeters. As a less preferred alternative, the guide wire can be withdrawn and substituted with one about 300 centimeters long. Thereafter, the catheter is slid off the guide wire and another catheter is substituted.
This procedure for changing catheters is cumbersome because it requires two operators to hold the guide wire, remove the first catheter and feed the replacement onto the wire. If the guide wire is removed and replaced, the patient is exposed to risk because the doctor must pass a guide wire across the stenosis for second time. It also exposes the patient to an unwanted amount of radiation, since the time required to accomplish the procedure is extended.
Some catheters have been developed which have guide wire lumens that are substantially shorter than the overall catheter body length. U.S. Pat. Nos. 5,040,548 and 5,061,273 to Yock, for example, disclose a balloon catheter having a guide wire lumen at least 10-15 centimeters long extending from the catheter's distal tip toward its proximal end. U.S. Pat. No. 4,762,129 to Bonzel discloses a similar balloon catheter where the shortened guide wire lumen is formed in the interior of and is substantially coextensive with the balloon interior. Similarly, U.S. Pat. No. 4,662,368 to Hussein et al. discloses a catheter for removing stenoses by cauterizing them with a heated tip in which the tip has a short channel for accommodating a guide wire.
U.S. Pat. No. 4,468,224 to Enzmann et al. discloses a non-PTCA catheter which, in one embodiment, uses a guide wire threading aperture set at a large angle and disposed at a moderate distance behind the catheter's distal end to introduce a guide wire into the catheter's central lumen.
It is important to note that though the above prior art catheters make use of a shortened guide wire lumen, the lumen must still be of a significant length (e.g., in the Yock device, at least 10 cm). If the guide wire lumen length is too short, the Yock patents teach that the wire cannot reliably guide the catheter to the stenosis. Instead, the flexible catheter will tend to bend and kink, thereby impeding proper positioning.

Fiber optic catheter with shortened guide wire lumen