The ventilation interface for sleep apnea therapy interfaces a ventilation device to the patient""s airways. The ventilation interface includes a pair of nasal inserts made from flexible, resilient silicone which are oval shaped in cross-section and slightly tapered from a base proximal the ventilation supply to the distal tip end. A bead flange is disposed about the exterior of each insert at the distal end of the insert. In one embodiment, a valve is disposed between the nasal inserts and a source of positive airway pressure, the valve having a rim with a one-way diaphragm pivotally attached to the valve body with an inflatable bladder depending from the rim which seals against an exit port during inspiration and deflates to uncover the exit port on expiration. Another embodiment has nasal inserts without positive airway pressure but with a removable filter in the inserts for filtering inspired air.

1. Field of the Invention
The present invention relates to ventilation devices, and particularly to a ventilation device having a nasal inserts which are inserted into the nostrils and seal against the nostrils without the aid of harnesses, head straps, adhesive tape or other external devices, and having exhalation ports designed to eliminate whistling noises, the ventilation interface having particular utility in various modes of therapy for obstructive sleep apnea. The invention may include a valve used in lieu of the exhalation ports, and may include nasal inserts used with filters for eliminating allergens and irritants from inhaled air but used without positive airway pressure.
2. Description of the Related Art
Sleep apnea is a potentially lethal affliction in which breathing stops recurrently during sleep. Sleep apnea may be of the obstructive type (sometimes known as the pickwickian syndrome) in which the upper airway is blocked in spite of airflow drive; the central type with decreased respiratory drive; or a mixed type. Breathing may cease for periods long enough to cause or to exacerbate cardiac conditions, and may be accompanied by swallowing of the tongue. Sleep apnea frequently results in fitful periods of both day and night sleeping with drowsiness and exhaustion, leaving the patient physically and mentally debilitated.
In recent years it has been found that various forms of positive airway pressure during sleep can be an effective form of therapy for the apnea sufferer. Ventilation can be applied in the form of Continuous Positive Airway Pressure (CPAP) in which a positive pressure is maintained in the airway throughout the respiratory cycle, Bilevel Positive Airway Pressure (BiPAP) in which positive pressure is maintained during inspiration but reduced during expiration, and Intermittent Mechanical Positive Pressure Ventilation in which pressure is applied when an episode of apnea is sensed. Positive airway pressure devices have traditionally employed either a face mask which only covers the patient""s nose, or nasal pillows as the interface between the ventilation device and the patient""s airway. However, there are problems with both of these interfaces.
The face mask requires a harness, headband, or other headgear to keep the mask in position, which many patient""s find uncomfortable, particularly when sleeping. The face mask must seal the mask against the patient""s face, and may cause irritation and facial sores, particularly if the patient moves his head while sleeping, causing the mask to rub against the skin. Face masks are also position dependent, and may leak if the mask changes position with movement of the patient""s head. The face mask applies pressure to the sinus area of the face adjacent to the nose, causing the airways to narrow, thereby increasing the velocity of flow through the airway, but decreasing the pressure against the nasal mucosal walls. This strips moisture from the mucosal wall during inspiration, thereby causing drying and a burning sensation. These factors will often result in the patient""s removal of the mask and discontinuance of positive airway pressure therapy.
Nasal pillows are pillowed style nasal seals which are pressed against the inferior portion of the nares to close the nostril openings. Nasal pillows require a headband or harness to maintain the pressure, resulting in the same patient discomfort noted with face masks. Nasal pillows have about a 0.25xe2x80x3 internal diameter at the nasal entry port where the seal is made. Therefore, pressurized air must pass through a constricted port, increasing the velocity of airflow, with resultant drying and burning of the nasal airways. The narrowed interface diameter of the nasal pillows causes a pressure drop, which is directly proportional to the drop in the number of available air molecules within the closed system. It is the volume of air molecules at the area in the patient""s throat where the apneic events appear that is needed to correct apnea. The narrower the airways or the internal diameter of the nasal interface, the lower the volume of air molecules that will be available and the greater the driving pressure that is required to meet the volume demand. An increase in driving pressure does not fully compensate for the loss in the number of air molecules available.
A further problem with existing ventilation devices is that the carbon dioxide bleed ports for venting exhaled gases are noisy on both nasal face masks and nasal pillows. The whistling noise that occurs while utilizing such devices can prove quite annoying to the patient, awakening the patient and causing the patient to discontinue use of the ventilation device.
A number of devices have been proposed which include a ventilation interface for supplying gases to be inhaled, for collecting exhaled gases, or for mounting sensors for measuring or monitoring respiratory function.
U.S. Pat. Nos. 5,335,654 and 5,535,739, issued on Aug. 9, 1994 to Rapoport and Jul. 16, 1996 to Rapoport et al., respectively, describe a CPAP system using a conventional nasal mask, the innovation comprising a flow sensor in the input line connected to a signal processor to determine the waveform of airflow, which is connected to a flow controller to adjust the pressure of airflow as required. U.S. Des. Pat. No. 333,015, issued Feb. 2, 1993 to Farmer et al. shows an ornamental design for a nasal mask. U.S. Des. Pat. No. 262,322, issued Dec. 15, 1981 to Mizerak, shows an ornamental design for a nasal cannula with a mouth mask.
U.S. Pat. No. 4,782,832, issued Nov. 8, 1988 to Trimble et al., discloses nasal pillows held in the patient""s nose by a harness arrangement, the device having a plenum with two accordion or bellows shaped nipples for fitting against the nostril openings. U.S. Pat. Nos. 4,774,946, issued Oct. 4, 1988 to Ackerman et al., teaches a nasal and endotracheal tube apparatus for administering CPAP to infants, the nose tubes having a bulbous portion for seating in the nares of an infant and a headband with a Velcro(copyright) closure for supporting the cannula and supply tubes.
U.S. Pat. Nos. 5,269,296, issued to Landis on Dec. 14, 1993, and 5,477,852 and 5,687,715, issued to Landis et al. on Dec. 26, 1995, and Nov. 18, 1997, respectively, describe CPAP devices for the treatment of sleep apnea with relatively stiff or rigid nasal cannulae or prongs surrounded by inflatable cuffs to retain the cannulae in the nares, but which also may be supplemented by an inflatable head harness to position the cannulae and hold them in place, the two cannulae being joined by a conduit having vent holes to vent exhaled air. U.S. Pat. No. 5,533,506, issued Jul. 9, 1996 to the present inventor, discloses a nasal tube assembly in which the tubes are tapered, frustro-conical assemblies with a soft membrane over the distal tip and a washer at the base of the nasal tube to prevent the tubes from falling through a support bar connected to a harness, the nasal tubes forming a positive seal with the inside of the nostrils to prevent the escape of gases.
U.S. Pat. No. 5,682,881, issued Nov. 4, 1997 to Winthrop et al., shows a nasal cannula for CPAP therapy with cone shaped nasal prongs in which the cannula is secured to the patient""s upper lip by adhesive tape strips. U.S. Pat. No. 4,915,105, issued Apr. 10, 1990 to Lee, teaches a miniature respiratory breather apparatus in which relatively stiff or rigid nasal tubes have elastomeric packings for sealing the tubes in the nares.
Several patents describe improvements to nasal cannulae, but without sealing the nose tubes against the nostrils to prevent leakage of gas, including: U.S. Pat. No. 3,513,844, issued May 26, 1970 to Smith (metal strip in cannula cross-tube to retain configuration matching patient""s lip); U.S. Pat. No. 4,106,505, issued Aug. 15, 1978 to Salter et al. (cannula body with ends extending upward and rearward); U.S. Pat. No. 4,915,104, issued Apr. 10, 1990 to Marcy (clasp with lanyard supporting supply tubes to ease pressure on ears); U.S. Pat. No. 5,025,805, issued Jun. 25, 1991 to Nutter (cylindrical soft sponge cuff around supply tubes to ease pressure and prevent skin injuries); U.S. Pat. No. 5,046,491, issued Sep. 10, 1991 to Derrick (device for collecting gases exhaled from both nose and mouth); U.S. Pat. No. 5,335,659, issued Aug. 9, 1994 to Pologe (device for mounting optical sensor on nasal septum); U.S. Pat. No. 5,509,409, issued Apr. 23, 1996 to Weatherholt (nasal cannula with face guards); U.S. Pat. No. 5,572,994, issued Nov. 12, 1996 to Smith (rotatable coupling in supply tubing); U.S. Pat. No. 5,636,630, issued Jun. 10, 1997 to Miller et al. (support for supply tubes); U.S. Pat. No. 5,704,916, issued Jan. 6, 1998 to Byrd (novel head strap for nasal cannula); and U.S. Pat. No. 5,704,799, issued Apr. 21, 1998 to Nielsen (device with one-way flow through cannula and flow restrictor to equalize flow into two nose members).
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. Thus a ventilation interface for sleep apnea therapy solving the aforementioned problems is desired.
The ventilation interface for sleep apnea therapy interfaces a ventilation device which provides positive airway pressure (either continuous, bilevel, or intermittent) with the patient""s airways. The ventilation interface includes a pair of nasal inserts made from flexible, resilient silicone which are oval shaped in cross-section and slightly tapered from a base proximal the ventilation supply to the distal tip end. A bead flange is disposed about the exterior of each insert at the distal end of the insert. A bleed port for release of exhaled air is defined through a conical vent projecting normally to the path of the incoming air flow, and continues through a nipple extending to the exterior of the air conduit. In one embodiment, a pair of nasal inserts are integral with a nasal cannula body, with bleed ports axially aligned with each insert. In another embodiment, each insert is independently connected to a separate, thin-walled, flexible supply line.
Advantageously, the construction of the nasal inserts permits the ventilation interface to be retained in the patient""s nares without requiring a harness, head strap, or other retaining device. The nasal inserts do not merely seal the base of the nostrils, but are inserted into the nostrils farther than nasal pillows, as far as the nasal mucosal membrane, and are retained by resilient expansion of the inserts, the flanges engaging notches in the nares, together with the pressure of incoming air, which forms a positive seal to prevent the leakage of air past the inserts. The nasal inserts are constructed according to specifications which permit the inserts to be relatively thin-walled, and are oval-shaped in cross-section to conform to the shape of the nostrils. This construction permits the nasal inserts to have a large internal diameter in order to pass a greater volume of air than nasal pillows or prongs, without significant narrowing of the air passages, thereby maintaining lateral pressure, and avoiding drying and burning of the patient""s nasal passages, as well as supplying a sufficient number of air molecules at the desired pressure to keep the patient""s airways patent. Consequently, the ventilation device is more comfortable for the patient to wear while sleeping than conventional positive airway pressure devices, but at the same time is more effective in treating the patient""s apnea.
The bleed ports are specially designed to avoid the whistling noises commonly experienced with conventional nasal masks and nasal pillows. By projecting the vent structure into the air passage normal to the direction of the air flow from the supply tubes, incoming air must turn ninety degrees and exit through a long, restricted diameter bleed port to vent to the atmosphere, eliminating whistling noises to increase patient comfort. In the embodiment having a nasal cannula body, the bleed ports are axially aligned with the nasal inserts, providing CO2 with a direct path to exit the cannula body. When the nasal inserts are attached to independent supply tubes, the bleed ports are at the base of the nostrils, providing essentially normal exhalation.
When the nasal inserts are directly connected to the supply tubes, the nasal inserts may be even more thin-walled than when attached to a cannula body, resulting in an even greater volume of air supplied through the cannula body, up to a 20% increase in volume. In this case the supply tubes may be similar to heat-shrink tubing, being made from a very thin-walled thermoplastic material that is lightweight and flexible so that the supply tubing may collapse when not in use, but will expand to a predetermined diameter under pressure applied by a ventilator.
Under some circumstances it may prove advantageous to insert a valve between the nasal inserts and the supply lines to control the flow of air through the inserts. The valve may serve as an alternative to the bleed ports, providing isolation between inhaled and exhaled air, or may be connected to an electrical or mechanical control device for BiPAP or Intermittent Mechanical Positive Pressure Ventilation. One valve which may be used includes a valve body having a gate with a rim attached to one wall by a hinge and disposed to pivot between an inspiratory position in which the rim extends transversely across the inside perimeter of the nasal insert, and an expiratory position in which the rim swings downward against a stop. A one-way diaphragm extends across the rim which only permits inspiratory air to pass through the diaphragm. An exit port is defined in a sidewall of the valve body opposite the hinge. A flexible, inflatable bladder depends from the rim and is attached to the sidewalls of the valve body below the exit port. During inspiration incoming air inflates the bladder and raises the rim against a stop positioned above the exit port, the bladder inflating against the exit port and blocking the passage of air through the exit port. On expiration, the pressure of expired air against the one-way diaphragm opens the valve, expired air leaving the valve body through the exit port.
The nasal inserts may also be used without a mechanical ventilation supply, or positive airway pressure, in certain applications. For example, a one-way expiratory diaphragm may be placed across the base of the nasal inserts. A one-way inspiratory diaphragm is disposed in the sidewall of the nasal insert adjacent the base, so that the inspiratory diaphragm is disposed below the bottom of the nostril when the nasal inserts are worn. The inspiratory diaphragm may include a removable filter which is retained against the diaphragm by an elastic mesh, spring clips, hooks, or other retainer means. The filter may be of the type used to filter out dust, pollen, bacteria, allergens, and other nasal irritants. Use of the nasal inserts fitted with the filter while sleeping may be of therapeutic value in the treatment of asthma and other respiratory ailments.
Accordingly, it is a principal object of the invention to provide a ventilation interface for sleep apnea therapy having nasal inserts which seal against the nares and do not require a harness, head strap, or other external devices to maintain pressure for retaining the inserts in or against the patient""s nostrils.
It is another object of the invention to provide a ventilation device having nasal inserts made of flexible, resilient plastic with a bead flange for retaining the inserts in the nares, wherein the walls of the insert are thin-walled and maintain lateral pressure in the nares in order to provide a greater internal diameter for the delivery of a greater volume of air molecules at a constant delivery pressure and without forcing ventilation gases through restricted ports or passageways so that drying and burning of the patient""s nasal airways is avoided while delivering a therapeutic volume of air to maintain the apneic patient""s airways in a patent condition.
It is a further object of the invention to provide a ventilation interface for sleep apnea therapy with equipped with a valve disposed between the nasal inserts and the source of positive airway pressure for controlling the flow of air through the nasal inserts.
Still another object of the invention is to provide a ventilation interface equipped with a removable filter for filtering allergens from inspired air in order to prevent asthmatic and allergic attacks.
It is an object of the invention to provide improved elements and arrangements thereof for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes.
These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings.

Ventilation interface for sleep apnea therapy


A safety barrier transition, comprising partially deformable elements, pivoted by quickly disengageable coupling elements to a fixed barrier, specifically designed for closing, under safety conditions, and quickly re-opening road gaps provided in superhighway traffic dividers.

The present invention relates to a barrier transition for removably closing road gaps and other passage areas through safety barriers.
As is known, superhighways, freeways and two-carriageway roads in general are protected at their central riserve by safety barriers which can be made of a concrete mix, usually a reinforced concrete mix or, more frequently, a metal material, depending on light and heavy vehicle containment characteristics, and on personal safety standards, defined by national and European rules.
The above protective systems are interrupted, at preset distances, by paved areas to allow transiting vehicles to switch off the carriageway, when conditions are required.
The above mentioned areas are usually called xe2x80x9ctraffic divider gapsxe2x80x9d, and have an average span from 20 to 40 m.
The frequency with which the mentioned road gaps occur through the safety barrier, depends on environment conditions, maintenance requirements, provided outlets or the like and, usually corresponds to a rather small spacing, i.e. about a gap each two road kilometers.
Thus, said road gaps actually represent a discontinuity through the side protective system designed for preventing transiting vehicles from stepping over the traffic divider, i.e. the safety barrier.
Such a discontinuity is very dangerous, since traffic accidents, caused by vehicles traversing the road gap, even if they occur with a rather small rate, have very deleterious effects and, because of the continuously increasing vehicle traffic, are anyhow very significative since, in such a case, an uncontrolled vehicle accidentally traversing a read gap, will probably impact against one or more other vehicles driven in the opposite direction on the other carriageway, thereby the sum of the kinetic energies of the impacting vehicles will be such as to cause fatal consequences for the vehicle passengers.
Moreover, if the starting portions of the safety barrier at the ends of the road gaps are not suitably protected, for example by impact attenuators, then an impact against these regions would frequently have very serious consequences for the vehicle passengers.
Thus, in order to overcome the above problems the possibility of eliminating the mentioned road gaps and closing them by fixed constructions of a conventional barrier type has been already considered.
Such an approach, however, could not be a viable one, for example because of emergency and snow removal vehicle circulating problems, to allow vehicles to switch off their carriageway in serious accident conditions in which the carriageway would be interrupted for a long time, and for long duration maintenance operations, requiring the provision of a counter-lane on the opposite carriageway.
Thus, for safety purposes, it is absolutely necessary to provide the road users with an efficient closure system which, on the other hand, can be easily and quickly removed, for example in urgency situations.
Disassemblable metal conventional barriers are commercially available, which, however, do not allow to provide an easy and quick opening of the barrier since, for disassembling them, it would be necessary to remove a comparatively high number of barrier coupling elements. In this connection it should be moreover pointed out that the mentioned coupling elements, being subjected to atmospheric and polluting agents, would render much more difficult a snap operating intervention.
Fixed cable barriers have been also used in some countries with rather good safety results; however this prior technology disclosed, for example, in EP 369659 (British Ropes) does not allow to make easily removable barrier systems, thereby does not solve the existing barrier problems.
A cable safety system which has been specifically designed to overcome the above problems is that disclosed in the Italian Patent No. 1,270,041 and in WO 00/23658 (PCT) to Snoline. This system, however, does not solve the problems affecting large width road gaps since in an impact situation, it provides comparatively great dynamic deforming cambers.
Accordingly, the aim of the present invention is to solve the above mentioned problems, by providing a barrier transition for removably closing road gaps, adapted to resist, in a completely safe condition, against impacts, as required by international rules for light and average weight vehicles, such as motor vehicles and busses, and which, in the meanwhile, can be either completely or partially removed, in a short time without requiring either specifically designed complex tools or skilled operators.
Within the scope of the above mentioned aim, a main object of the present invention is to provide such a barrier transition which, owing to its specifically designed constructional features, is very reliable and safe in operation.
Yet another object of the present invention is to provide such a barrier transition which can be easily made starting from easily available elements and materials and which, moreover, is very competitive from a mere economic standpoint.
According to one aspect of the present invention, the above mentioned aim and objects, as well as yet other objects, which will become more apparent hereinafter, are achieved by a barrier transition for removably closing road gaps, characterized in that said barrier transition comprises suitably contoured protective longitudinal elements arranged symmetrically to a road gap closure line, said protective elements being coupled to one another so as to provide a longitudinally rigid barrier having impact force transmitting end portions.
Said protective elements have advantageously a length equal to that of standard safety metal barriers, i.e. usually of 4 m, and a conventional double or triple corrugation cross-section, and an optional vertically extending multiple pattern.
The protective elements are coupled in opposite pairs, by rigid connection means, such as screws engaged in holes provided near their end portions, and the element pairs are coupled by special blocks which, on a side, are rigidly clamped by screws to the holes of said elements and, on the other side, support either one or two vertical hinge assemblies.
Said hinge assemblies, of strong construction, connect the system to allow it to transmit through said protective elements the stresses from an impacting vehicle, thereby providing a comparatively high flexural stiffness, to in turn reduce the maximum dynamic camber.
Thus, the system substantially operates as a flexible barrier, which is exclusively stressed by tension and strained through a resilient range.
The pin of the hinge assembly can be easily removed to quickly either partially or fully open the transition barrier (i.e. to remove one or more elements thereof), for allowing traffic to pass therethrough.
Each longitudinal protective element is coupled to two vertically extending feet, arranged near its end portions and supporting it on the ground thereon it can freely slide.
To facilitate the opening movement, some or all said feet can comprise a plurality of wheels the height of which can be adjusted by a suitable raising or lifting mechanism coupled to said feet or to said longitudinal protective elements, to allow said wheels to contact the ground, in an extended position thereof, only as the road gap is opened. The wheels can moreover comprise a brake for preventing spontaneous movements on an inclined ground.
To the end elements of the transition, which transition can have any desired length, depending on the existing road gap size, transition fitting of any suitable shape designed to provide a safe connection to the fixed barrier are coupled, said fittings comprising the same panels as said fixed metal barrier having a double or triple corrugation construction, or different modified panels for concrete barriers, in each case provided in a suitable number and arrangement of the holes for coupling and transmitting the impact force to be dissipated by the extended fixed barrier, which, usually, has a length of the order of at least few hundred meters, but which, most probably, continuously extends up to the following road gap with a length of at least two kilometers.
If the existing barrier pertains to a less class and, accordingly, is too weak to absorb the impact force, then it would be anyhow possible to discharge to the ground said impact force, by coupling the transition end elements to a strong pole ground driven or coupled to a suitable foundation adding optional dissipating elements, for providing protection against a local side impact.
If only a portion of the road gap shall be opened, then it is advantageously possible to use a suitable removable pole, to be driven into the ground through a driving pole bush, for anchoring therein the transition portion remaining as the barrier gap is opened.
To further decrease the dynamic camber, the system can also comprise intermediate binding elements, including further removable ground driven poles for reducing the overall system working length and, accordingly, its dynamic deformation.

Safety barrier transition for providing an easily removable closure of road gaps


The invention relates to a housing from a polyamide molding compound containing 70 to 99.5% by weight of at least one thermoplastic polyamide and 0.5 to 30% by weight of at least one polyamide oligomer with linear or branched chain structure with a number average molar mass of 800 to 5000 g/mol with basic end groups which are at least partially NH2 end groups, and carboxyl end groups, one of these end groups being present in excess and the concentration of the end group present in excess being at most 300 mmol/kg.

The invention relates to housings, especially mobile telephone housings, from polyamide moulding compounds containing viscosity-stable polyamide oligomers with significantly improved flowability.
In order to produce conductive thermoplastics, normally conductive substances are used, such as e.g. carbon black, carbon fibres, graphite, metal fibres and metal powders, metallised glass fibres or conductive polymers with conjugated electron system, such as for example polyaniline, poly-para-phenylene vinylene or polythiophene.
In addition to the conductivity, in particular in applications in the automotive field, high requirements, such as e.g. with respect to first-class surface quality, high toughness, low density and high flowability, are also placed on the thermoplastics. As conductivity additive, frequently carbon is used for thermoplastics in various modifications, such as e.g. carbon black, carbon fibres, graphite or graphite fibres or fibrils, the diameter of which is between 1 and 500 nm.
By using carbon black and carbon fibres, the result is frequently an impairment in surface quality, toughness and flowability due to the high concentration which is required, because comparatively high carbon black concentrations are required for the demanded conductivities (R. G. Gilg, "Carbon black for conductive plastic materials" in: Electrically conductive plastic materials, publishers: H. J. Mair, S. Roth, 2nd edition, Carl Hanser Verlag, 1989, Munich, Vienna, page 21-36).
By using carbon nanofibrils, as are offered for sale for example by the company Hyperion Catalysis, only comparatively small quantities need be added in order to achieve sufficient conductivities (U.S. Pat. No. 5,643,502). However homogeneous dispersion of the carbon nanofibrils in the polymer matrix is very difficult since graphite fibres tend to form aggregates. This limits the use of carbon nanofibrils greatly and demands use of master batches. In addition, the availability of carbon nanofibrils is restricted greatly by the complex and very expensive production process.
Carbon black-filled and peroxide-stable moulding compounds are described for example in EP 0 953 796 B1. The advantage of these polyamide moulding compounds in which carbon blacks with a low specific surface are used resides in the very good resistance to sour gas. However, it is disadvantageous that the melt viscosity increases greatly by using carbon black and hence processing with injection moulding machines, in particular when producing thin-walled parts, presents problems since the flowability of the melt is too low.
Highly flowable low-viscosity thermoplastic compositions are of interest for a multiplicity of injection moulding applications. For example, thin-walled components in the electrical, electronics or automotive industry demand low melt viscosities of the thermoplastic compositions in order that filling of the mould is possible with the lowest possible filling pressures. Furthermore, shorter cycle times can also frequently be achieved with low-viscosity polymer compositions. Furthermore, good flowability is extremely important precisely with highly filled polymer compositions, for example with contents of glass or carbon fibres or mineral of above 40%, in particular if carbon black is also added as conductivity additive in addition. Despite high flowability, high mechanical requirements are however placed on the components so that no impairment in the mechanical properties should be caused due to the lowering of the viscosity.
The simplest way to improve the flowability of polymers resides in reducing the molar mass thereof. It must however be taken into account as a disadvantage that the mechanical properties of the polymers are in part drastically impaired.
U.S. Pat. No. 6,548,591 B2 describes a thermoplastic polyamide moulding compound, an improvement in the flow behaviour being achieved by using a low-molecular weight polyamide with a higher melt temperature. Because of the fact that an oligomer which melts higher than the matrix should be used, the result can be incompatibilities between matrix and oligomer. This is revealed for example in the fact that, at 5% by weight of a PA66 oligomer, the impact strength of a high-molecular weight polyamide 6 is reduced from 90 kJ/m2 to 30 kJ/m2.
In EP 0 957 131 B1, the improvement in flow properties of polyamide moulding compounds by the addition of polyamide prepolymers, i.e. polyamide oligomers provided with reactive end groups, is described. These prepolymers have the disadvantage, because of the high end group concentration, amino and carboxyl groups being present at the same time, that they are not viscosity-stable during compounding with the high-molecular weight component and during the subsequent processing. An undesired increase in viscosity occurs, which in turn impairs the flowability.
Because of the high concentration of amino and carboxyl groups of these prepolymers, undesired reactions can also occur with further ingredient components, such as e.g. the stabilisers, glass fibre sizings or impact strength modifiers.
Another possibility is the use of so-called anti-blocking agents, also described as flow aids or internal lubricants which can be added to the high-molecular weight polymer as an additive. Flow aids of this type are known in the literature (such as e.g. from Plastics 2000, 9, page 116-118) and can be for example fatty acid esters of polyols or amides from fatty acids and amines. Fatty acid esters of this type, for example pentaerythritol tetrastearate or ethylene glycol dimontanoate, are however miscible only in a limited fashion with polar thermoplastics, such as polyamides, and have therefore a tendency to migration and concentration on the surface of the moulded article. This can be disadvantageous with respect to adhesion in multilayer composites or of paints and metals in the case of coated moulded articles.
As an alternative to the surface-active flow aids, internal flow aids can be used which are compatible with the polymer. There are suitable for this purpose for example, low-molecular weight compounds or branched or dendritic polymers with a polarity similar to the polymer matrix. Highly branched dendritic systems of this type are described for example in DE 102 55 044 A1.
Flow-improving properties of graft copolymers are known for example from EP 1 217 039 B1. This publication describes an easily flowing polyester moulding compound comprising thermoplastic polyester and a polyamine/polyamide graft copolymer.
The flow-improving effect of fluorocarbon polymers is described in EP 1 454 963 A1. The high price of fluorocarbon polymers, the danger of corrosion and the low effectiveness in polyamides is disadvantageous.
It is therefore the object of the invention to make available a housing from highly flowable polyamide moulding compounds, with which thin-walled components with good mechanical properties can be produced and which do not have the disadvantages of the state of the art.
The object of the invention is achieved by the features of claim 1. The sub-claims reveal advantageous developments.
The housing of the invention is built up of a polyamide moulding compound which contains, relative to the polyamide, 70 to 99.5% by weight at least of a thermoplastic polyamide and 0.5 to 30% by weight at least of a polyamide oligomer with a linear or branched chain structure, with a number average molar mass of 800 to 5000 g/mol with basic end groups which are at least partially NH2 end groups, and carboxyl end groups, one of these end groups being present in excess and the concentration of the end group occurring in excess being at most 300 mmol/kg. According to the invention, the polyamide moulding compounds extend to all polyamides, i.e. crystalline or amorphous polyamides or mixtures thereof.
The subject of the present invention resides hence in that additional proportions of viscosity-stable polyamide oligomers are incorporated in the polyamide moulding compounds.
The polyamide oligomers contained lead to a reduction in the melt viscosity of the moulding compounds and hence to a significantly improved processibility, in particular in the case of thin-walled moulded articles. The polyamide oligomers according to the invention cannot thereby migrate, like e.g. certain low-molecular weight plasticisers, and hence do not form or only slightly form coatings on the moulded articles or the tool surfaces.
Likewise, the surface quality, in particular of reinforced readymade parts, is greatly improved. Because of the fillers, the surface is often rough and spotted or displays indentations and irregularities. The addition of the polyamide oligomers effects a smoother and more uniform surface of the moulded articles and endows them with high gloss.
Possibly added fillers and conductivity additives are wetted well by the polyamide oligomers and hence facilitate incorporation, in particular with high filling degrees.
The polyamide oligomers which are suitable for this purpose are added to the high-molecular weight polyamide in the melt, together with other components of the composition.
Due to the choice of monomers, the polyamide oligomers have only few condensable chain ends, approximately comparable to the end group concentration of the normal polyamides of middle and high molar mass.
Because of this end group configuration of the polyamide oligomers according to the invention, neither a significant polymer build-up with respect to the oligomers nor decomposition of the polymer matrix occurs during compounding or processing so that the polyamide moulding compounds according to the invention are melt-stable. Furthermore, secondary reactions with other ingredient components in practice do not occur. Because of the similar polarity of oligomer and polymer matrix, good compatibility is provided between the components, as a result of which disadvantageous exudation is avoided.
The viscosity-stable polyamide oligomers according to the invention have a linear or branched chain structure, a molar mass less than 5000 g/mol and are distinguished in that at least 50%, preferably 60-80% of the chain ends are not condensation-active and either the basic or the acidic chain ends predominate in total. Independently of the molar mass of the polyamide oligomers, the maximum concentration of primary amino end groups or COOH end groups is 300, preferably 100 mmol/kg.
Both aminic functional groups, such as R3N, R2NH, RNH2, and also carboxylate, i.e. the deprotonated carboxyl functionality, thereby apply as basic component, which can be found on the chain end or in the oligomer structure.
The polyamide oligomers according to the invention have accordingly only very few reactive end groups and are therefore practically no longer condensable with other functionalised constitutional units, such as monomers, oligomers or polymers. In contrast to the known reactive polyamide oligomers, the oligomers according to the invention are extraordinarily stable against decomposition as a pure substance and in a suitable mixture with polyamide moulding compounds and are even able extensively to prevent decomposition of such moulding compounds in the melt.
Polyamides can be constructed from a multiplicity of monomer constitutional units so that a multiplicity of special end properties is also possible. This high variation breadth applies also to the polyamide oligomers according to the invention. By choice and combination of the known polyamide constitutional units and via the targeted adjustment of the molar mass, properties, such as the crystallinity, the melt or glass conversion point, the affinity to substrates and the moisture content, i.e. the basic character of the oligomer, can be specifically adjusted.
It is also possible, in addition to the purely linear chain structure, to produce specifically branched oligomers. The rules which are thereby valid for polyamides, as are displayed e.g. in EP 0 345 645, apply to the specification of the branching structure also in the case of polyamide oligomers, in particular if the molar mass thereof is above 800 g/mol. Hence structure-branched polyamide oligomers are then reproducible and can be produced reproducibly without formation of deposits in the reactor if, in addition to the structure-forming constitutional units, exclusively amino acids and/or lactams are the basic monomers.
A feature relevant to the invention of the polyamide oligomers is not special choice of the constitutional units and their composition per se, but that they are low in condensation-active end groups and in particular that the ratio, remaining after the condensation reaction, of the end groups present in excess to the end group present in deficit is greater than 1:1, preferably greater than 2:1.
The concentration of end groups present in excess is thereby preferably at most 100 mmol/kg. Furthermore, if further amino end groups are present then these are the secondary or tertiary amino end groups which are not or only a little condensable. The substituents at the end-position secondary or tertiary amino end groups are preferably alkyl, cycloalkyl or aryl radicals with more than 4 C-atoms, in particular with 4 to 44 C-atoms. It is of particular significance that the polyamide oligomers can exert an excellent effect during thermoplastic processing of plastic material compounds and, for example the flowability of the melts is improved, the crystallisation speed can be increased and often the mould-release behaviour is substantially improved. Decomposition effects in the sense of a hydrolytic chain cleaving are thereby practically excluded and no corrosion occurs on the processing machines, as are known by COOH-containing compounds.
In order that the polyamide oligomers according to the invention are stable against decomposition per se or in a mixture with high-molecular weight polyamides, the concentration of end groups present in excess is at least 20, preferably at least 50 mmol/kg.
Polyamide moulding compounds containing polyamide oligomers astonishingly have excellent hydrolysis and weathering stability when the oligomer used contains a high concentration—expressed in mmol/kg—of basic groups. In the most advantageous manner, these are inserted into the oligomer structure if the compound used for the chain termination jointly includes, apart from the condensation-active NH2 or COOH group, a sterically screened amino group (sec. or tert. amine), such as for example in the compounds of formulae (I), (II) and (IV). Such special chain-terminating constitutional units are e.g. N-alkylated diamines, such as e.g. cocopropylene diamine or C16-22-alkyl propylene diamine (Duomeen M. by Akzo), 3-cyclohexyl amino propylene diamine but in particular also triacetone diamine. The addition of correspondingly constructed polyamide oligomers into polyamide moulding compounds improves the hydrolysis and weathering stability thereof without expensive stabilisers, such as e.g. must be added specially of the so-called HALS type.
In addition it is possible to use monomer constitutional units jointly for the oligomer production, said monomer constitutional units jointly containing a sterically inhibited phenol structure in the molecule. During the addition to a plastic material compound in particular to a polyamide moulding compound, such an oligomer consequently improves the heat stability thereof in addition. A corresponding monocarboxylic acid, given by way of example, is 3-(3,5-di-tert.-butyl-4-hydroxyphenyl)-propionic acid (Irganox 1310 by Ciba S C), formula (III). If the polyamide oligomer is hence controlled in its molar mass following these possibilities and thus contains the sterically inhibited amine function at one chain end and the sterically inhibited phenol group at the other chain end, then with suitable addition, in particular to a polyamide moulding compound, it has the effect that said moulding compound has at the same time excellent hydrolysis, weathering and heat stability.
Of course, the most varied of combination options for controlling the chain length is possible according to the intended effect. For example only one part of the carboxylic acid can carry the sterically inhibited phenol function and the residual component can be monoalkyl in that a commercial stearic acid is for example jointly used and only a part can be a sterically inhibited amine and the remainder, for example a commercial fatty amine with e.g. 20 C-atoms. It is ensured by means of such special combinations that the polyamide oligomer develops its stabilising effect at the same time and furthermore acts excellently as lubricant and mould-release agent.
Monomers for the production of the polyamide oligomers according to the invention are linear and branched-chain diamines and dicarboxylic acids with 2 to 44 C-atoms, in addition cyclic, condensation-active diamines with aliphatic amine function, such as e.g. 1,3 or 1,4-bisaminomethylcyclohexane or m- and p-xylylene diamine, bicyclic and thereby also repeatedly substituted diamines, such as e.g. 3,3′-dimethyl-4,4′-diamino-dicyclohexylmethane or also—propane or also the so-called TCD-diamine, (3(4),8(9)-bis(aminomethyl)-tricyclo[5.2.1.02,6]decane) or diamines with the norbornane structure. Suitable dicarboxylic acids are furthermore dimerised fatty acids and also iso- and terephthalic acid and naphthalenedicarboxylic acids.
The molar mass control is effected for example such that a monoamine and a monocarboxylic acid are added to the monomer constitutional units which are present in equimolar proportions, for example stearyl amine and stearic acid in the molar ratio of approx. 1:1.
A further possibility for control of the molar masses and end groups is, when using bi- or multifunctional compounds, to compensate for the thereby produced functional end groups of the one type by addition of a monofunctional compound of the other type, such as e.g. combination of a non-volatile ether diamine with the corresponding quantity of stearic acid.
When using amino acids or lactams, also tri- or even multifunctional compounds can be used to adjust the end group type and concentration, such as e.g. trimesic acid or ethylenediaminetetrapropionic acid. For the structural termination, then 3 or 4 equivalents monoamine, such as e.g. stearyl amine, are required. The procedure is thereby implemented such that a predetermined excess of one functionality remains and, for special effects, compounds are jointly used specifically which jointly contain an additional sterically hindered amine function or a sterically hindered phenol function.
A compound class which is very suitable for production of structure-branched oligomers is furthermore the so-called styrene-maleic acid anhydride resins with e.g. 5 to 10 maleic anhydride groups (MA) in the molecule. The MA group thereby reacts in the melt with an amine acid or a lactam with imide formation. This "oligomer arm" is then carboxyl-terminated and the chain termination is effected using a monoamine. Oligomers based on amino acid and lactam with this branching feature also have excellent flowability, even with a comparatively higher molar mass, and are hence particularly suitable for highly filled polyamide formulations with surfaces of excellent gloss.
The commercial production of the oligomers can be effected in reaction vessels, as are used for the production of normal polyamides, and it is subject essentially to the rules which are known for polyamide synthesis.
The polyamide oligomers added to the high-molecular weight polyamide moulding compounds, independently of the concentration, cause a very significant reduction in viscosity (90% in Example 1, approx. 900% in Example 3) so that the MVR can increase by a multiple. This can be detected also in the flow length. Dependent upon the concentration and the type of polyamide oligomer, increases in the flow length of above 100% can be achieved.
Furthermore, the combination of partially crystalline or amorphous polyamides with polyamide oligomers makes possible the production of low-distortion moulded bodies, in particular in highly reinforced or filled systems. During processing of the polyamide moulding compounds which contain PA oligomer and hence are more flowable, lower-stress moulded bodies are produced with as a rule improved surface quality. In particular in the case of amorphous polyamides and blends thereof with partially crystalline polyamides, the addition of polyamide oligomers according to the invention leads to a significant reduction in distortion. This effect appears all the more, the higher the concentration of fibrous and/or particulate fillers. Precisely the addition of small scale, particulate fillers, such as e.g. ground or precipitated calcium carbonate, aluminium silicate (kaolin) or magnesium silicate (talc), or even the addition of ground glass fibres, reduces the flowability of polyamide melts greatly so that processing is made difficult and, with respect to the production of low-distortion moulded articles, no optimum results are achieved. The addition of PA oligomers is able however also in these cases to reduce the melt viscosity of the PA moulding compounds to such an extent that, with optimal processing, moulded articles with low shrinkage and very low distortion are produced. Preferably, the distortion is thereby below 5%, very particular preferred below 3%.
As polyamides for the moulding compound according to the invention, advantageously polycondensates from aliphatic lactams or ω-aminocarboxylic acids with 4 to 44 carbon atoms, preferably 4 to 18 carbon atoms, or those from aromatic aminocarboxylic acids with 6 to 20 carbon atoms are used.
Likewise suitable are polycondensates from at least one diamine and at least one dicarboxylic acid with respectively 2 to 44 carbon atoms. Examples of such diamines are ethylene diamine, 1,4-diaminobutane, 1,6-diaminohexane, 1,10-diaminodecane, 1,12-diaminododecane, m- and p-xylylene diamine, cyclohexyldimethyleneamine, bis-(aminocyclohexyl)methane and the alkyl derivatives thereof.
Examples of dicarboxylic acids are succinic, glutaric, adipinic, pimelic, octanedioic, azelaic and sebacic acid, dodecanedicarboxylic acid, dimer fatty acids with 36 or 44 C-atoms, 1,6-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid and naphthalenedicarboxylic acid.
Particularly suitable partially crystalline polyamides for the moulding compounds according to the invention are thereby homo- and copolyamides based on PA6, PA66, PA46, PA11, PA12, PA1212, PA1012, PA610, PA612, PA69, PA1010, PA6T, PA6T6I, PA6T66, PA9T, PA10T, PA12T, PA12I, mixtures or copolymers thereof based on these polyamides, PA6, PA66, PA11, PA12, PA1212, PA6T6I, PA6T66 being preferred. Preferred also are copolymers based on the above-mentioned polyamides, such as e.g. 12T/12, 10T/12, 12T/106 and 10T/106. Furthermore, also nylon 6/66, nylon 6/612, nylon 6/66/610, nylon 6/66/12, nylon 6/6T and nylon 6/6I can be used according to the invention.
Preferred amorphous or microcrystalline homo- and copolyamides have the following compositions: PA6I, 6I/6T, MXDI/6I, MXDI/MXDT/6I/6T, MXDI/12I, MACMI/12, MACMI/MACMT/12, 6I/MACMI/12, 6I/6T/MACMI/-MACMT/12, PACM6/11, PACM12, PACMI/PACM12, MACM6/11, MACM12, MACMI/MACM12, MACM12/PACM12, 6I/6T/PACMI/PACMT/PACM12/612. As cyclic diamines there are thereby possible, for example MACM (3,3 diamino-4,4-dimethyldicyclohexylmethane), PACM (3,3 diaminodicyclo-hexylmethane) or MXD (m-xylylene diamine).
A particularly preferred embodiment of the polyamide moulding compounds according to the invention provides that the moulding compounds contain in addition to the polyamide a conductivity additive. The conductivity additive is thereby contained in the polyamide moulding compound preferably in a quantity of 1 to 50% by weight, particularly preferred from 3 to 25% by weight, relative to the total polyamide moulding compound.
There are possible as conductivity additive for the polyamide moulding compounds according to the invention, carbon blacks with low and high specific surface and also mixtures thereof and carbon nanofibrils and mixtures of carbon blacks and carbon nanofibrils.
The carbon blacks according to the invention have a specific BET surface, measured according to ASTM standard D3037-89, of greater than 5 m2/g and a dibutylphthalate absorption, measured according to ASTM standard D2414-90, of greater than 50 ml/100 g. However, preferably used are carbon blacks with a specific surface according to the BET method of greater than 200 m2/g and a dibutylphthalate absorption of greater than 300 ml/100 g. Particularly preferred are carbon blacks with a BET surface in the range of 300 to 2000 m2/g and a dibutylphthalate absorption in the range of 350 to 1000 ml/100 g.
In the case of the conductivity carbon blacks according to the invention, the primary particle size is between 0.005 and 0.2 μm preferably between 0.01 and 0.1 μm. On the carbon black surface there can be located a multiplicity of oxygen-containing groups, such as for example carboxyl, lactol, phenol groups, quinoid carbonyl groups and/or pyrone structures.
During selection of the carbon blacks, in particular highly pure types are preferred since these endow the moulding compounds with high peroxide resistance. Highly pure means in this context that the carbon blacks used have an ash content of less than 0.1% by weight, a heavy metal content of less than 50 ppm and a sulphur content of less than 0.05% by weight.
Conductivity carbon blacks can for example be produced from acetylene, from synthesis gas or from the furnace process, from oil carrier gases and air. Production methods are described for example in R. G. Gilg, "Carbon black for conductive plastic materials" in: Electrically conductive plastic materials, publishers: H. J. Mair, S. Roth, 2nd edition, Carl Hanser Verlag, 1989, Munich, Vienna, page 21-36.
Preferred carbon nanofibrils typically have the shape of tubes which are formed from at least one graphite layer. The graphite layers are disposed concentrically around the cylinder axis. Carbon nanofibrils have a length-to-diameter ratio of preferably at least 5:1, preferably of at least 100:1 and particularly preferred of at least 1000:1. The diameter of the nanofibrils is typically in the range of 0.001 to 0.5 μm, preferably in the range of 0.005 to 0.08 μm, particularly preferred in the range of 0.006 to 0.05 μm. The length of the carbon nanofibrils is typically 0.5 to 1000 μm, preferably 0.8 to 100 μm, particularly preferred 1 to 10 μm. The carbon nanofibrils have a hollow, cylindrical core around which the graphite layers are formally wound. This cavity typically has a diameter of 0.001 to 0.1 μm, preferably a diameter of 0.008 to 0.015 μm. In a typical embodiment of the carbon nanofibrils, the wall of the fibrils around the cavity comprises for example 8 graphite layers. The carbon nanofibrils can thereby be present as aggregates of up to 1000 μm diameter, preferably up to 500 μm diameter comprising a plurality of nanofibrils.
The addition of the carbon nanofibrils can be effected before, during or after the polymerisation or polycondensation of the monomers into the polyamide. If the addition of the nanofibrils according to the invention is effected after polymerisation, then it is effected preferably by addition to the polyamide melt in an extruder or in a kneader. By means of the compounding process in the kneader or extruder, in particular the already described aggregates can be extensively or even entirely comminuted and the carbon nanofibrils can be dispersed in the polyamide matrix.
In a preferred embodiment, the carbon nanofibrils can be added in metered amounts as highly concentrated master batches to the polyamides which preferably have the same chemical structure as the polyamide matrix. The concentration of carbon nanofibrils in the master batches is in the range of 5 to 50, preferably 8 to 30, particularly preferred in the range of 12 to 22% by weight. The production of master batches is described for example in U.S. Pat. No. 5,643,502. By using master batches, in particular the comminution of the aggregates can be improved. Due to processing into the moulding compound or moulded body, the carbon nanofibrils can have shorter length distributions in the moulding compound or in the moulded body than used originally. Carbon nanofibrils are offered for sale for example by the company Hyperion Catalysis. Synthesis of the carbon nanofibrils is effected for example in a reactor which contains a gas containing carbon and a metal catalyst, such as described e.g. in U.S. Pat. No. 5,643,502.
As further conductivity additive, the polyamide compositions, alone or in addition to carbon nanofibrils, can also contain particulate carbon compounds, such as carbon black which is suitable for the production of conductivity and is termed by the person skilled in the art also as conductivity carbon black, or graphite powder. This can also include expanded graphite.
According to the invention, graphite powders concern comminuted graphite. The person skilled in the art understands by graphite a modification of carbon, as is described for example in A. F. Hollemann, E. Wiberg, N. Wiberg, "Textbook of inorganic chemistry" 91st-100th edition, page 710-702. Graphite comprises planar carbon layers which are disposed one above the other. Graphite can be comminuted for example by grinding. The particle size is in the range of 0.01 μm to 1 mm, preferably in the range of 1 to 300 μm, for particular preference in the range of 2 to 20 μm.
The addition of the carbon blacks and/or graphites according to the invention can be effected before, during or after polymerisation or polycondensation of the monomers into the polyamide. If the addition of the carbon blacks and/or graphites according to the invention is effected after polymerisation, then it is effected preferably by addition to the thermoplastic melt in an extruder or in a kneader. According to the invention, the carbon blacks and/or graphites can also be added in metered amounts as highly concentrated master batches to polyamides which preferably have the same chemical composition as the polyamide matrix. The concentration of carbon blacks and/or graphites in the master batches is preferably in the range of 3 to 70, preferably from 5 to 50 and particularly preferred in the range of 7 to 35% by weight. According to the invention, the carbon blacks and/or graphites can be mixed also with binders, such as for example waxes, fatty acid esters or polyolefins, for improved meterability. According to the invention, the carbon blacks and/or graphites also with or without additional binders can be pelletised or granulated for example by pressing or compression methods, which likewise serves for better meterability. Also the polyamide oligomers can be already added to the master batches. This is advantageous since they facilitate dispersion of the conductivity additives both in the MB matrix and in the polyamide moulding compounds according to the invention. With such master batches, both the polyamide oligomers and the conductivity additives can be incorporated simultaneously into high-molecular weight polyamide.
In a preferred embodiment, also mixtures of a plurality of graphites, mixtures of a plurality of carbon blacks or mixtures of at least one graphite and at least one carbon black or mixtures of at least one carbon black and carbon nanofibrils can be used.
Conductivity carbon blacks according to the invention under the name Ketjenblack by the company AKZO Nobel, under the name Vulcan by the company Cabot or under the name Printex from the Degussa company can be used. Graphites according to the invention can be used as powders for example from the company Vogel & Prenner, Wiesbaden, Germany or SGL Carbon.
As further component, the thermoplastic moulding compounds can contain preferably a fibrous and/or particulate filler or reinforcing material or a mixture of two or more different fillers and/or reinforcing materials, for example based on talc, mica, silicate, quartz, titanium dioxide, wollastonite, kaolin, amorphous silicic acids, magnesium carbonate, magnesium hydroxide, chalk, limestone, feldspar, barium sulphate, glass balls and/or fibrous fillers and/or reinforcing materials based on carbon fibres, metal fibres and/or glass fibres. Preferably mineral particulate fillers are used based on talc, mica, silicate, quartz, titanium dioxide, wollastonite, kaolin, amorphous silicic acids, magnesium carbonate, chalk, feldspar, barium sulphate, long-term magnetic or magnetisable metal compounds, and/or alloys, glass balls or glass fibres. In particular mineral particulate fillers according to the invention are preferred, based on talc, wollastonite, kaolin and/or glass fibres. The fillers and reinforcing agents can also be surface-treated.
In particular when using glass fibres, in addition to silanes, also polymer dispersions, film-forming agents, branching agents and/or glass fibre processing aids can be used. Particularly preferred according to the invention are also glass fibres which in general have a fibre diameter between 7 and 18, preferably between 9 and 15 μm, and can be added as endless fibres or as cut or ground glass fibres, the fibres being able to be equipped with a suitable sizing system and an adhesive or adhesive system, e.g. on a silane basis.
The polyamide moulding compounds contain fillers and reinforcing materials in quantities of 0 to 95% by weight, preferably from 20 to 65% by weight and particularly preferred from 25 to 50% by weight, relative respectively to the entire polyamide moulding compound.
The combined addition of 10 to 70% by weight of fibrous and also 3 to 40% by weight of particulate fillers and/or reinforcing materials has proved thereby to be particularly advantageous.
Of course the thermoplastic polyamide moulding compounds according to the invention can furthermore contain normal additives which are known in general to the person skilled in the art, alone or in combination, said additives being selected from the group comprising impact strength agents, foreign polymers, adhesives, flameproofing agents, reinforcing agents, such as glass and C fibres, UV or heat stabilisers, stabilisers against weathering, minerals, processing aids, crystallisation accelerators or delayers, antioxidants, flow aids, lubricants, mould-release agents, plasticisers, fireproofing agents, pigments, colour and marking materials and fillers such as carbon black or graphite or also nanoparticles in lamellar form, corresponding to all additives known for polyamides, as are necessary for the respective application.
Also other common polymers, such as polyesters, polyolefins, polycarbonates, AN and ABS polymers, functionalised copolyolefins and ionomers, can be added to the above-described (co)polyamides or mixtures thereof.
As further additives, impact strength modifiers are added to the thermoplastic polyamide moulding compounds according to the invention. These are e.g. copolymers based on polyolefins of low glass conversion temperature which can contain acrylic acid or be grafted with maleic anhydride. In particular, impact strength modifiers, such as ethylene-propylene-copolyolefins or ethylene-propylene-diene-rubbers (EPDM) or acrylate rubbers, may be mentioned here.
In preferred embodiments, the moulding compounds contain furthermore nano-scale fillers. In a particular embodiment of the invention, the nano-scale fillers are either silicon dioxide or silicon dioxide hydrates. In the polyamide moulding compound, certain nano-scale fillers are present in one embodiment as uniformly dispersed, layer-shaped material.
As fillers, long-term magnetic or magnetisable metal compounds and/or alloys can furthermore be used. These are contained preferably in a quantity of 60 to 95% by weight in the polyamide moulding compound.
As fillers, metals or alloys, in particular rare earth metal powders, (including yttrium) of the rare earth metal/iron/boron type, are preferred, Nd/Fe/B, also described as "Neodymium", being particularly preferred.
Also the alloys which are known for magnetic materials, samarium/cobalt and samarium/thulium, ferrites, such as barium- and strontium ferrite and also carbonyl iron powder are advantageous. Suitable metal powders are described for example in the company brochure DR 9632 MAG of the company Delco Remy, Anderson, Ind. 46013, USA and have the title Magnequench® Products.
High quality magnetic products are in particular Nd/Fe/B; SmTm, e.g. Sm2Tm17; SmCo, e.g. SmCo5. In principle however all magnetic and/or magnetisable metal powders and metal compounds are possible. It is thereby advantageous but not necessary that they are coated. Suitable coatings for ferrites are the state of the art.
It should thereby be particularly emphasised that, as the applicant was able to show, the housings, especially the telephone housings, have distortion of less than 6%, preferably less than 3%.
The following examples explain the present invention without restricting it.

This patent is subject to a terminal disclaimer.

Polyamide molding materials with an improved flowability, the production thereof and its use


A U flow radiator 10 with a header tank 12 split into inlet and outlet sides I and O by a lengthwise divider wall 18 has a coolant inlet consisting of a cylindrical pipe 22. A hollow cylindrical barrel 24 co extensive and coaxial with pipe 22 and extending across divider wall 18, with cut outs 26 and 28 opening respectively into both sides I and O. A thin walled, hollow cylindrical sleeve 30 turns within barrel 24 with windows 36 and 38 that alternately block or open the cut outs 26 and 28, or open both partially. A rotary actuator 40 turns sleeve 30 within barrel 24. Coolant can be selectively routed all to the tank outlet side O, by passing the radiator 10 for quick warm up. After warm up, coolant can be routed to I or O in desired proportions to increase or decrease cooling capacity. With high engine cooling demand, all coolant is routed to the inlet side I and all coolant passes through radiator 10.

This invention relates to heat exchangers, such as vehicle engine cooling radiators, and to a flow control valves therefore control valve that is integrated into the inlet of a U flow type radiator in a simple and non flow restrictive fashion.
Flow control in vehicle engine cooling radiators has historically consisted of just a passively acting thermostat which, reacting to coolant temperature, blocks flow into the radiator to a greater or lesser degree, by passing the remainder of the flow through an by pass path external to the radiator. When wide open at the highest coolant temperature, all flow goes through the radiator. This standard system does not offer a high degree of control, generally using a thermally expandable wax material. Other systems attempt to add an extra degree of control by deliberately and externally heating the wax material to expand it, generally electrically heating it. There has been a recent trend, at least in published patents, toward active, electronically controlled flow control valves. An example may be seen in U.S. Pat. No. 6,314,920. The system shown there requires an electronically controlled coolant pump, and the valve is also external to the radiator, requiring an external by pass circuit around the radiator.
Other patents show control valves internal to the header tanks of the radiator, either passively or actively operated. One example is U.S. Pat. No. 5,305,826 shows a plunger operated double valve, either actively or passively controlled, that simultaneously blocks or opens both the inlet into a radiator of the two pass type, as well as blocking or opening a by pass passage between the two passes. As disclosed, the valve, being just downstream of the inlet, would represent a severe flow restriction within the header tank, in addition to the pressure drop that inherently happens as flow enters a header tank inlet and makes a ninety degree turn. Likewise, U.S. Pat. No. 4,432,410 shows a passively acting by pass valve located within the header tank, just downstream of the inlet. This, also, would represent a significant additional flow restriction and pressure drop. Coolant flow induced pressure drop through the inlet, outlet and header tank of a radiator is a serious issue, and features that add significantly to it are not preferred, despite the desirability of having an internal flow control valve, as opposed to an external flow control valve.
The invention provides an actively controllable radiator flow control valve that is internal to the radiator header tank, but which is integrated therewith in such a way as to not add a large pressure drop.
In the embodiment disclosed, the radiator is a U flow design, with two rows of flow tubes, in which one header tank is split between inlet and outlet portions by a dividing wall, with the inlet on one side and the outlet/pump inlet on the other side. The other header tank would act only to return the flow from the inlet to outlet portion of the first header tank. The physical coolant inlet to the first header tank is a cylindrical barrel that extends not only outside of the tank, as a conventional inlet fitting would, but also through the dividing wall and across the whole width of the interior of the tank. The exterior, outer end of the barrel provides the coolant inlet to the tank, while the inner surface provides a stationary outer housing and guide for the movable inner member of the control valve. Windows in the barrel allow open into the inlet and outlet side of the first header tank, one on either side of the dividing wall. The movable portion of the valve is a hollow cylindrical sleeve, closely and rotatably mounted within the outer barrel. One end of the sleeve opposite the inlet end of the outer barrel, can be turned back and forth about its central axis by a motor or similar actuator. Cut outs in the inner sleeve register with the windows in outer barrel, either completely or partially, or not at all, depending on the relative turned position of the inner sleeve.
Coolant flow entering the exterior end of the outer barrel then flows inside the close fitting inner sleeve, essentially just as it would with a conventional radiator tank inlet, and with no significant additional pressure loss. Depending on the relative registration of the inner sleeve and outer barrel cut outs and widows, flow exits the inner sleeve, and flows into either just the outlet side of the header tank, for a complete by pass of the radiator, or just the inlet side of header tank, forcing all flow through the radiator, or a mixed flow. Mixed flow can constitute the normal radiator operation, as determined by sensed engine or coolant temperature and consequent cooling demand, rather than the conventional operation of total flow through the radiator at all times other than initial warm up. This is feasible since a U flow radiator is inherently more efficient and the valve adds little additional pressure drop. Operating the radiator normally with some degree of by pass saves pump work and energy, regardless of how the pump is driven. Total radiator flow can then be reserved for severe engine cooling requirements.

Heat exchanger with integrated flow control valve