EP1720664A1

EP1720664A1 - Method for the production of dental moulding materials and device therefor

Info

Publication number: EP1720664A1
Application number: EP05715470A
Authority: EP
Inventors: Gottfried Knispel; Klaus-Dieter Nehren; Holger Urbas; Matthias Schaub; Alfred Von Schuckmann
Original assignee: Heraeus Kulzer GmbH
Current assignee: Kulzer GmbH
Priority date: 2004-02-27
Filing date: 2005-02-23
Publication date: 2006-11-15
Also published as: JP2007527283A; WO2005082549A2; US20080264809A1

Description

Process for the production of dental impression materials and devices therefor

The invention relates to an arrangement with low flow resistance, in particular for structurally viscous pastes such as dental materials of various consistencies, dynamic mixers suitable for this, mixer elements, the production of dental impression materials, and methods for mixing components of impression materials, in particular polyether impression materials, and the use of a chamber mixer.

Multi-component mixing systems for product end users have become particularly popular in the dental field. On the one hand, these are hand-operated devices for double cartridges, in which the mixture of relatively small quantities and low viscosities is generated using a static mixer. On the other hand, there are motor-driven mixing bones that drive a so-called dynamic mixer with rotating mixing elements in addition to material handling. In these devices, materials from cartridges as well as plastic bags can be processed. The devices of this type, which are now widely used in the dental field, are designed for two components in a mixing ratio of 5: 1.

The mixing energy is generated by the rotating inner part of the mixer, which mixes the two components into a homogeneous mass as they flow through the mixing nozzle.

The problem of these unequal component sizes described in EP 0 993 863 / US 6,244,740, EP 1 029 585 and EP 1 099 470 / US 6,523,992 is a fluctuating mixing ratio at the beginning of the conveyance, which was solved there by diverting the larger-volume component through a channel and hence later than the smaller volume component in the common mixing room arrives.

EP 1 072 323 A1 also describes a mixing device for the dental field which can process components 1: 1 in addition to a ratio of 5: 1.

However, such a system, which is incompatible with the existing devices, has enormous marketing problems because of the high additional investment costs for the end user.

In terms of quantity, of the impression materials used in the dental field, those with a kneadable consistency make up a very large proportion. It is precisely this consistency that has hitherto prevented their processing in the automotive mixing systems.

On the one hand, the devices reach their performance limits when dispensing the substances, on the other hand, the dynamic mixer generates undesirable heat input into the product due to the high friction. The reaction rate of the multi-component pastes is strongly dependent on the temperature. They are in a pasty state at room temperature for a sufficient period of time and then harden quickly to an elastomer due to the temperature increase in the mouth. The different heat input during mixing for each device type leads to the build-up of elastomeric components outside the oral cavity, which can lead to a distorted impression.

Impression materials that are used in the dental field are usually two-component compounds that crosslink at room temperature to give elastomeric reaction products. These compositions are predominantly based on crosslinkable silicones or on crosslinkable polyethers.

In the dental sector in particular, chemically curing pastes are offered in double cartridges or tubular bags, which the user simultaneously doses, conveys and mixes using a device. The mixing is carried out by mixing attachments, eg dynamic mixers, which are connected to the double cartridges or tubular bags. Examples of such mixers are described, for example, in DE 199 51 504 A1, DE 199 47 331 C2, DE 101 12 904 A1, DE 100 43 489 A1 and DE 100 15 133 C1. Since very different consistencies are used for different applications, there is a need to develop a mixing attachment that can be used universally for all these consistencies. An object of the invention is to provide such a mixing attachment or dynamic mixer.

With low-viscosity consistencies, the best mixing is achieved by high shear in narrow gaps. Due to the increasing use of these mixing devices also for highly viscous pastes, it became necessary to design mixer attachments that are equipped with larger flow cross sections, because otherwise the highly viscous consistencies lead to undesirably high conveying forces and undesired heating of the mix.

In the case of the low-viscosity, and in particular the structurally-viscous pastes with pronounced flow limits, these expanded flow cross sections mean that the components only mix in the area of the rotor and stator surfaces. Plug flow then occurs in areas of greater layer thickness. As a result, poor or even unmixed paste components are removed from the mixer.

In the case of mixers, the blades of which extend as far as possible to the wall of the mixing chamber, the high peripheral speed that occurs there gives a good mixing effect in the outer region of the mixing chamber. In the layer, between the mixer shaft and this outside area, the pumped paste can rotate like a plug together with the inner part of the mixer if there are no baffles ??

The baffles common in apparatus construction are installed on the outside of the pipe or boiler. The dynamic mixers considered here are injection molded parts made of plastic for single use, which should consist of as few parts as possible and should be easy to manufacture. A baffle on the wall of the mixer housing cannot be produced with simple injection molds.

Extensions of the shaft diameter surrounding the mixing shaft have proven to be easy to design baffles. These diameter extensions projecting radially into the mixing chamber from the mixing shaft reduce the flow cross-section at this point, thus forcing the paste out of the plug flow and briefly increasing the flow speed and thus the shear at this point.

For mixing smaller quantities, systems have been established that consist of a manual discharge device, double-chamber cartridge and static mixer. Here the mixing energy generated by the delivery pressure. When flowing through the static mixer, which consists of an outer housing and immovable mixing elements inside, the two separate components that are separate at the beginning are mixed to a homogeneous mass. Both static and dynamic mixers are used as disposable items in the dental field. After the end of mixing, the impression material remaining in it is discarded with the mixer.

With the static mixers, spiral mixers are usually used, which have proven themselves for many years for mixing impression and bite registration masses. There are also static chamber mixers. In these chamber mixers, a large number of chambers are arranged one behind the other and side by side. The material flow is divided into several strands through connection openings between the chambers and these are mixed together when they are brought together again. These mixers are known, for example, from US 5,851,067 and US 5,944,419 and are available for the cartridges used for dental impression materials. However, since they do not provide a better mixture when used with silicone impression materials, they have not become established.

Further chamber mixers are known from EP 1 426 099 A1. Depending on the number of components to be mixed, the chamber mixers have at least two inlet openings and one outlet opening and essentially extend between the inlet openings and the outlet openings, the number of chambers arranged one behind the other in the longitudinal direction generally being significantly greater than the number of the chambers perpendicular to the Chambers arranged along the longitudinal axis.

The mixing quality of the pressed and mixed impression material can be assessed by cutting the paste strand emerging from the mixer at an early stage of crosslinking across the direction of flow. If the mixture is poor, lamellae are formed on the cutting surface due to the presence of layers of different crosslinking states.

The reliability of existing processes is limited with regard to connections that are accidentally inserted incorrectly and the mixing of tough components.

It is an object of the present invention to improve the reliability of known arrangements, methods, mixers and the mixer elements for mixing dental polyether impression materials. sen to improve, especially with regard to the mixing quality and the pressure load for components with high viscosity to reliably handle the problems mentioned.

This invention is therefore based in particular on the task of developing a dynamic mixer for the existing mixing devices which compensates for fluctuations in the mixing ratio and at the same time mixes all the consistencies used in the dental field sufficiently well without developing excessive heat in the product.

These measures are primarily intended to prevent the components from hardening back into the cartridge / bag after the mixing process and at the same time to minimize the dynamic pressure in the mixer. It would also be an advantage if the "large" component that normally precedes the start of funding is somewhat withheld.

The object is achieved by an arrangement, dynamic mixers, mixer parts and mixing methods according to the independent claims. Advantageous refinements are specified in the dependent claims. The features of the dependent claims can be combined according to the invention with features of other claims.

Possible solutions to the problem are mixers in which there is a buffer chamber for receiving the multicomponent which initially emerges to a greater extent than required. There is no separation of the buffer and mixing chambers.

In preferred configurations, the avoidance of the back hardening and the component delay are realized by a buffer chamber which has a deflection element between the inlet opening and the mixing chamber.

Another preferred embodiment consists of devices in which part of the component is initially passed into a chamber which can only vent, but has narrow gaps or holes so that the paste cannot flow through it. This "dead" chamber is not a flow channel. When designing the actual mixing chamber and the mixing blades, the improvements are mainly due to the effect of the thin mixing shaft. Certain wing designs and shapes, which are described in more detail below, have proven to be particularly advantageous.

A channel can be provided for introducing the second component in order to ensure the ratio of the two channels to one another. However, this reduces the restrained effect of the other channel / chamber.

Due to the very high viscosity / degree of filling of dental impression materials required in terms of application technology, every deflection of the material flow or tapering of the flow cross-section is associated with pressure build-up and frictional heat.

Compatibility with existing cartridge systems is expediently sought. This means that all dimensions are specified outside the dynamic mixer. Therefore, the largest possible flow cross-section, few deflections and constrictions should be realized within the mixing housing.

For this reason, elongated channels such as in EP 0 993 863 / US 6,244,740, EP 1 029 585 and EP 1 099 470 / US 6,523,992 are dispensed with. A buffer chamber is used to collect the component entering in excess at the start of delivery, the total flow cross-section of which is significantly larger than that of the product inlet opening.

To make full use of the buffer chamber, at least part of the inlet opening can be covered by a fixed deflecting element.

A buffer chamber, which is filled by a special arrangement of the fixed deflecting element and is not suitable for material flow due to the small size of the ventilation opening at the end, already brings advantages for some consistencies.

In order to make the flow easy even in the mixing area, the cross-sectional area of the mixer shaft should not be more than 1/5 of the inner cross-section of the chamber part equipped with it. This means that at the points where the product flows through, the distance between Mixer shaft and chamber section are brought to at least 4 mm without unnecessarily increasing the outside diameter and thus the volume of contents. In order to produce the smallest possible baffle areas in the material flow direction, the individual mixing elements are advantageously kept so narrow that at least 40% of the inner cross-sectional area of the chamber can also be used as a flow cross-sectional area on the levels occupied by mixing elements.

In order to achieve sufficient mixing quality with a mixer optimized for flow and low friction, the mixing elements are expediently designed and arranged in such a way that they produce product flow which, in addition to being in the plane of rotation and direction of flow, is also directed against the flow and against the centrifugal force. A trapezoidal, triangular or comparable flow opening can be created by trapezoidal design or a corresponding rounding of part of the mixing elements, which alternately directs the product flow inwards and outwards.

By at least partially chamfering or rounding off at least some of the mixing elements in such a way that they produce a partial flow which arises partially counter to the direction of the conveying flow, the mixer according to the invention can produce sufficient mixing qualities even at lower viscosities.

In order to avoid the negative pressure and the entrapment of air bubbles behind the mixing elements, which also deteriorate the mixing quality, the side of the mixing elements facing the chamber part can be at least partially chamfered or rounded off at its edge facing the direction of flow and rotation.

A further improvement in the mixing quality is achieved in that the second component is also introduced into the mixing chamber over the entire available radial width of the surface of the closure part facing the mixing chamber. For this purpose, the inlet opening is expanded to a channel that extends as far as possible, more or less curved or kinked, from the mixer shaft opening to the chamber part.

In a preferred embodiment, at least part of the mixing axis located between the mixing wing planes has an expansion 14, 15 which narrows the flow cross section the mixing axis.

Accordingly, according to the invention, a dynamic mixer with an at least partially largely cylindrical chamber part, with a discharge opening at the front end of the chamber part with a closure part arranged at the rear end of the chamber part with inlet openings for individual components to be introduced and a central opening for one in the chamber part is particularly suitable for dental materials of various consistencies Mixer shaft rotatable about its longitudinal axis, with at least two planes arranged axially one behind the other, each with at least two mixing vanes arranged radially one behind the other, at least part of the mixing axis located between the plane of the mixing vanes (9) having an expansion of the mixing axis that narrows the flow cross section.

In further developments of the mixing shaft of the mixer or ^■ the invention, the flare 14 has a polygonal cross-sectional shape; ^■ The widening 15 has a round cross-sectional shape.

In a likewise preferred embodiment, at least a part of the mixing axis located between the mixing wing planes has a wall running eccentrically in the radial direction.

Accordingly, a dynamic mixer with an at least partially largely cylindrical chamber part, with a discharge opening at the front end of the chamber part, with a closure part arranged at the rear end of the chamber part with inlet openings for individual components to be introduced and a central opening for one in the chamber part is particularly suitable for dental materials of various consistencies Mixer shaft rotatable about its longitudinal axis, with at least two planes arranged axially one behind the other, each with at least two mixing vanes arranged radially one behind the other, at least part of the mixing axle located between the plane of the mixing vanes having a wall running eccentrically in the radial direction.

In special configurations of this mixing axis or this mixer

^■ The mixing axis parts equipped with a non-centric circumference are largely oval and their cross-sectional center does not match that of the chamber part. ^■ The mixing axis parts equipped with a non-centric circumference are largely circular and their center point does not match that of the chamber part. ^■ The axially successive planes (ABCD, EFGH) of the mixing axis parts equipped with a non-centric circumference are radially offset from one another.

Furthermore, a dynamic mixer with a chamber part, with a discharge opening at the front end of the chamber part, with a closure part arranged at the rear end of the chamber part with inlet openings for individual components to be introduced as well as a central opening for a rotatable in the chamber part about its longitudinal axis is particularly suitable for dental materials of various consistencies Mixer shaft, the mixing vanes arranged closest to the closure part sweeping over only a part of the area formed by the closure part, and the bottom plate of the closure part contains at least one flow disturbance which runs in the direction of flow and opposes the direction of rotation.

In advantageous versions of this mixer or its base plate

^{■ The} flow disrupters 17 arranged on the base plate of the closure part 5 extend radially as far as possible over the area of the base plate which is recessed by the mixing blades 16; ^{■ The} flow disruptors 17 arranged on the base plate of the closure part 5 extend axially as far as possible up to the mixing blades 16; ^{■ The} flow disruptors 17 arranged on the base plate of the closure part 5 extend so far in the direction of rotation that, together with the mixing blades 16, they prevent a direct product flow on the base plate between the two product inlet openings 6, 7 in every resting position of the mixing axis 8.

In one embodiment, the dynamic mixer has an at least partially largely cylindrical chamber part and a mixer shaft,

^■ with a discharge opening at the front end of the chamber part, ^■ with a closure part arranged at the rear end of the chamber part with inlet openings for individual components to be introduced, ^■ and a central opening for the mixer shaft rotatable in the chamber part about its and its longitudinal axis, on which there are in each case at least two mixing vanes arranged radially one behind the other in at least two disk-shaped mixing vane planes arranged one behind the other; ^■ and the special feature that at least a part of the mixing axis located between the mixing wing planes has an expansion of the mixing axis that narrows the flow cross section.

The widening is generally designed in such a way that the mixer axis deviates outwards from the cylindrical shape at the point in question. The expansion can e.g. be a curvature or emerge from the mixing axis in a wedge shape, so that the cross section of the widening has an angular or round cross-sectional shape. The side of the widening which protrudes from the chamber part can be chamfered or rounded.

The widening can also be designed in such a way that the mixer axis deviates from the cylindrical shape at the point in question in such a way that a half-spherical and half-elliptical overall cross section is produced.

All deviations from the cylindrical shape can also be arranged offset along the mixing axis, so that different mixing planes can have differently arranged or shaped deviations.

Another way to avoid plug flow is to design the mixing shaft eccentric to the axis of rotation on the levels not occupied by mixing blades. This is e.g. reached when the shaft is shaped with an oval cross section. Similar to a camshaft, the shaft can also be designed in sections in the form of a circle or disk and have planes arranged eccentrically to one another. In the case of an eccentrically offset arrangement of the levels, however, these can also have a polygonal design.

The baffles described above are part of the rotor and are therefore to be understood as a deflection of the axial product flow.

An important area for the mixing effect of reactive components is the area in which they meet for the first time. If unmixed layers remain here, this can lead to undesired spontaneous reactions.

Therefore, baffles have proven to be particularly advantageous in this area. This is implemented, for example, in that the high peripheral speed of the outer region, which is advantageous for mixing, is achieved by mixing blades that extend as far as possible to the housing wall and the closure part base. In the transition area between the closure part and the mixing shaft, the mixing blades are advantageously left out entirely and one or more baffles arranged on the bottom of the closure part.

If these baffles of the closure part are arranged around the mixing shaft in a block, wedge or ramp shape, they can, in conjunction with the mixing blades facing the inlet openings, prevent a direct product flow of the components into the inlet opening of the other component after the mixing process has ended.

According to the invention, arrangements for the production of dental impression materials are provided, in which dental materials of different consistencies are pressed out of storage containers into a mixer in isolation. The outlet openings of the storage containers are suitably matched to the inlet openings of the mixer. This arrangement has several, in particular at least three, preferably at least four of the following elements:

a) a buffer reservoir which is expanded in relation to an inlet opening and is not separated from the mixing space; b) a strand divider arranged in the buffer reservoir; c) element on the smaller-sized opening of the mixer or the storage container, which prevents the larger opening of the storage container or the mixer from being attached; d) a minimum distance between the mixer shaft and chamber wall of more than 4 mm; e) a mixer shaft, the cross-sectional area of which is a maximum of 20% of the cross-sectional area between the chamber wall; f) a mixing shaft including mixing elements, which together have a cross-sectional area of less than 60% of the cross-sectional area between the chamber wall; g) mixer axis with an expansion narrowing the flow cross section; h) mixer shaft whose mixing axis located between the mixing wing planes has a wall running eccentrically in the radial direction; i) closure part with a flow disturbance running in the direction of flow and opposing the direction of rotation; j) the mixing blade arranged closest to the closure part is designed such that it can only cover part of the area formed by the closure part.

In corresponding processes for producing dental impression materials, dental materials of different consistencies are pressed out of storage containers and mixed to form an impression material. For this purpose, the dental materials are pressed from the storage containers into a mixer, the mixer having inlet openings which are matched to the outlet openings of the storage containers and which realize several, in particular at least three, preferably at least four of the following features:

k) a component to be mixed is kneadable and is fed in particular to a mixer with a storage chamber;

I) the storage chamber is not separated from the mixing chamber; m) the components to be mixed are fed to a mixer shaft, the cross-sectional area of which is less than 20% of the cross-sectional area of the chamber part; n) the mixing shaft, together with the mixing elements, occupies less than 60% of the cross-sectional area of the chamber part; o) the strand pressed into the buffer reservoir is divided with a strand divider in the buffer reservoir; p) the smaller inlet opening of the mixer is secured against contacting the larger opening of the storage container by at least one element; q) the mixer axis has at least partially an expansion of the mixer axis which narrows the flow cross section between the mixing wing planes; r) at least some of the mixing elements attached to the mixer shaft (8) partially generate a mass flow against the conveying direction; s) convey the mass to be mixed alternately in the radial direction from the outside in and back.

According to the invention, it was recognized that a static chamber mixer is suitable for mixing the components of polyether impression materials. Polyether impression compounds are understood to mean, inter alia, both products based on silane-terminated polyethers and also based on aziridine-terminated polyethers. Thus, a method for mixing the com- Components of polyether impression materials provided, in which a static chamber mixer is used. For the first time, a static chamber mixer for mixing polyether impression compounds is used, in particular the use of a static chamber mixer for mixing impression compounds based on silane-terminated polyethers or the use of a static chamber mixer for mixing impression compounds based on aziridine-terminated polyethers.

Surprisingly, it has been shown that polyether impression compositions can be mixed particularly well with static chamber mixers, as are known, for example, from EP 1 426 099 A1 and the content of which is expressly incorporated in the disclosure of the present invention. The widely used silicone impression compounds can be mixed equally well with static chamber mixers as well as with static spiral mixers. In contrast, the polyether molding compositions which have recently been used increasingly can surprisingly be mixed much better with chamber mixers than with spiral mixers. It is surprising for the person skilled in the art in that he initially assumes a similar miscibility of the two materials.

This method according to the invention can be carried out, for example, with a mixer according to EP 1 426 0999 A1. The impression materials used are known, for example, from EP 269 819 B1. A conventional double-chamber cartridge, which has the two starting components to be mixed of a silane-terminated polyether impression material in a volume ratio of 2: 1 in its two chambers, is connected to the inlet opening of the chamber mixer. The components are pressed out of the cartridge by the chamber mixer and mixed in the process. It has been shown that the two components are mixed to form a homogeneous product. The so-called lamella formation that occurs when using spiral mixers (the product can be divided into layers in an early state of crosslinking) is completely or almost completely absent in the chamber mixers. With impression compounds based on aziridine-terminated polyether, the formation of lamellae can be avoided by using a chamber mixer.

Embodiments of the invention are described in more detail in the drawings:

Fig. 1 shows a mixer with the buffer chamber 22; Fig. 2 shows the rounded end 20 of the buffer chamber; Fig. 3 shows - compared to Fig. 2 rotated by 90 ° - the chamfered edge 19 of the buffer chamber 22;

4 and 5 show the variant that the end of the buffer chamber is not perpendicular to the plane of rotation;

6 to 8 show deflection elements;

9 and 10 show the buffer chamber 22 between the inlet opening 7 and the mixing chamber 21 with ventilation slots 50, 51, 52;

11 shows ventilation openings 53, 54 which are shaped as round or square holes;

12 to 15 show design options for the mixing elements;

16 shows in cross section a dynamic mixer for dental materials according to the invention;

17 and 18 show the mixer axis in cross section, with a circular and square configuration of the widening;

19 and 20 show configurations and positioning of the oval mixer axis and the mixer blades;

21 and 22 show asymmetrical arrangements of the circular mixer axis;

23 shows the arrangement of the flow disruptors on the closure part;

24 shows in cross section the configuration of the closure part with a flow disruptor.

25 shows the dynamic mixer in the front view, consisting of chamber part 1, mixer shaft 8 and closure part 5 with the two inlet openings 6, 7 and the orientation aid 40.

26 shows the dynamic mixer in the front view, placed on the two outlet ports 44, 46 of the tubular bag 47, 48, in which the two outlet ports 44, 46 of the tubular bag 47, 48 have different diameters, and the outlet port 44 sealingly on the outside 39 the inlet opening 6 is plugged on.

27 shows a side view of the dynamic mixer, placed on the outlet connector 44 of the tubular bag 47, in which the outlet connector 44 is plugged past the orientation aid 40 on the outside 39 sealingly onto the inlet opening 6. 28 shows the dynamic mixer in the front view, placed on the two outlet ports 45, 46 of the tubular bag 47, 48, in which the two outlet ports 44, 46 of the tubular bag 47, 48 have different diameters, and the outlet port 45 on the inside 38 sealingly the inlet opening 6 is inserted.

29 shows a closure part 5 with two web-shaped orientation aids 40 in the vicinity of the inlet opening 6 without touching it.

30 shows a closure part 5 with two strip-shaped orientation aids 41 in the vicinity of the inlet opening 6 without touching it.

31 shows a closure part 5 with a circular orientation aid 42 around the entry opening 6 without touching it.

32 shows a closure part 5 with a semicircular orientation aid 43 in the vicinity of the inlet opening 6 without touching it.

One embodiment of the invention is a dynamic mixer, in particular for dental materials of various consistencies, with a chamber part, with a discharge opening at the front end of the chamber part, with a closure part arranged at the rear end of the chamber part, which has a base plate, with inlet openings for individual components to be introduced and one centric opening for a mixer shaft, which can be rotated in the chamber part about its longitudinal axis, the inlet opening 7 for the component (“multicomponent”) present in larger quantities widening outside the region of the chamber that can be reached by mixing elements to form a buffer reservoir 8. At least one is preferred one of the characteristics

^■ that the individual components are present in mixing ratios different from 1; ^■ that the total area of the inlet openings of one component is not equal to the total area of the inlet openings of another component; ^■ that the buffer reservoir 22 extends around the inlet opening 7, in particular radially on both sides of the inlet opening 7; ■ that at least one end 9 of the buffer reservoir 22 adjoining the closure part 5 is at least partially not at right angles to the plane of rotation;

^■ that at least one end 20 of the buffer reservoir 22 is at least partially shaped as a curve;

■ that at least one end 49 of the buffer reservoir 22 adjoining the closure part 5 is at least partially designed as a slope;

^■ that the buffer reservoir 9 extends at least 90 ° over the base plate;

^■ that at least part of the inlet opening 7 is covered by a fixed deflection element 11;

^■ that the area of the deflecting element 11 facing the mixing chamber is smaller than the sum of the outlet openings 12 of the buffer chamber 22;

^■ that the sum of the flow cross-sectional areas of the buffer chamber is greater than that of the inlet opening 7;

^■ that the deflection element 11 is rounded at its edges;

^■ that the deflection element 11 is chamfered at its edges;

^■ that the deflection element 11 has a separating edge 13 on its side facing the inlet opening for dividing the product flow; and

^■ that the deflecting element 11 is arranged centrally above the inlet opening 7.

A further embodiment consists of a dynamic mixer, in particular for dental materials of various consistencies, with a chamber part 1, with a discharge opening 2 at the front end of the chamber part 3, with a closure part 5 arranged at the rear end of the chamber part 4, with inlet openings 6, 7 for individual components to be introduced , which are present in different proportions and are to be mixed, and a central opening for a mixer shaft 8, which is rotatable in the chamber part 1 about its longitudinal axis, wherein it has a buffer chamber 22 arranged between the inlet opening 7 and the mixing chamber 21, which is not is used as a flow channel for one of the components.

In this embodiment, at least one of the features is preferably present, ■ that the buffer chamber 22 has at least one ventilation opening 50, 51, 52, 53, 54 arranged towards the mixing chamber 21, the cross-sectional area of which is significantly smaller than that of the inlet opening 7;

■ that the ventilation opening 50 is axially slit-shaped at the end of the buffer chamber 22;

■ that the ventilation opening 51, 52 is provided in the form of a slot radially on the outside and / or inside of the buffer chamber 22;

■ that the ventilation openings 53, 54 are shaped as round or square holes and

■ that the ventilation openings 50, 51, 52, 53, 54 narrow towards the mixing chamber.

A further embodiment consists of a dynamic mixer, in particular for dental materials of various consistencies, with a chamber part 1, with a discharge opening 2 at the front end of the chamber part 3, with a closure part 5 arranged at the rear end of the chamber part 4, with inlet openings 6, 7 for individual components to be introduced which are present in proportions which differ from lab and are to be mixed, and a central opening for a mixer shaft 8 which can be rotated about its longitudinal axis in the chamber part 1,

^■ Both components enter the mixing chamber 21 over the available radial width of the closure part 7.

In this embodiment, at least one of the features is preferably present,

^■ that at least one inlet opening 6 branches to a channel 18 which is open towards the mixing chamber side;

^■ that the channel 18 is curved and or kinked, and

^■ That the edge 19 of the groove 18 which is in the direction of rotation is rounded or beveled:

A further embodiment consists of a dynamic mixer, in particular for dental materials of various consistencies, with a chamber part 1, with a discharge opening 2 at the front end of the chamber part 3, with a closure part 5 arranged at the rear end of the chamber part 4 with inlet openings 6, 7 for individual components to be introduced, the are present in proportions other than 1 and are to be mixed, and a central opening for a mixer shaft 8, which can be rotated about its longitudinal axis in the chamber part 1,

■ the distance between mixer shaft 8 and chamber part 1 is nowhere less than 4 mm; or

■ The cross-sectional area of the mixer shaft 8 is less than 20% of the cross-sectional area of the chamber part 1

■ The cross-sectional area of the mixing shaft 8 including the mixing elements 23, 28, 27, 30 is less than 60% of the cross-sectional area of the chamber part 1.

The mixing elements can be designed differently. Mixing elements 23 which have a baffle surface 24 parallel to the mixer axis in the direction of rotation and which are at least partially narrower towards the rear 25, 27 have proven effective.

It is furthermore advantageous that at least some of the mixing elements 23 attached to the mixing shaft 22 partially generate a mass flow against the conveying direction, in that at least one of the surfaces 26 running in the radial plane is beveled against the product flow.

In particular, the position and shape of the mixing elements 28, 29, 30 attached to the mixer shaft 22 can be used to convey the mass to be mixed alternately in the radial direction from the outside in and back.

It can also be advantageous if at least some of the mixing elements 28 attached to the mixer shaft 22 are chamfered and arranged axially to one another in such a way that they form a conical flow channel 31, 32; or that

^■ at least some of the mixing elements 28 are arranged radially one behind the other in such a way that the taper 31, 32 is directed alternately outwards and inwards;

^■ or that at least two of the mixing elements 29, 30 attached to the mixer shaft 22 in the axial direction are partially connected to one another 33, 34, 35, 36.

The connections 33, 34, 35, 36 of the mixing elements 29, 30 are advantageously mounted alternately inside and outside on the radial level. The connection 33, 34 of the mixing elements 30 can describe an arc 37 toward the product flow side.

16 shows the dynamic mixer with an at least partially largely cylindrical chamber part 1, with a discharge opening 2 at the front end of the chamber part 3, with a closure part 5 arranged at the rear end of the chamber part 4 with inlet openings 6 and 7 for individual components to be introduced and one Central opening for a mixer shaft 8 rotatable in the chamber part 1 about its longitudinal axis, with at least two planes 9 arranged axially one behind the other, each with at least two mixing vanes 10 arranged radially one behind the other, with the special feature that at least a part of the mixing axis 8 located between the mixing plane 9 levels one Flow cross section 54 has narrowing widening 14, 15 of the mixing axis 8.

17 shows the polygonal (here: square) design of the widening 14 and the mixing blades 10.

FIG. 18 shows a circular configuration of the widening 15 corresponding to FIG. 17.

19 shows a representation of the mixing axis, which is equipped with radially offset widenings in the planes A-D. This can be clearly seen from the projections in levels B and D.

20 shows the corresponding cross-sectional views of the planes A-D, the axis 57 with the widenings having an oval cross-section.

FIG. 21 shows the variant corresponding to the representation in FIG. 19, in which the axis has eccentrically arranged disks with a spherical cross section in the planes EH. In addition, FIG. 21 shows how the mixing vanes 16 arranged closest to the closure part 5 sweep over only part of the area formed by the closure part 5, and how the bottom plate of the closure part 5 contains at least one flow disturbance 17 that runs in the direction of flow and opposes the direction of rotation. The flow disruptors 17 arranged on the base plate of the closure part 5 extend radially as far as possible over the area of the base plate which is left open by the mixing blades 17; and / or as far as possible axially up to the mixing blades 17. It is an advantageous embodiment if the flow disruptors 17 arranged on the base plate of the closure part 5 extend so far in the direction of rotation that, in every resting position of the mixing axis 8, together with the mixing blades 16, there is a direct product flow on the base plate between the two product inlet openings 6 and 7 prevent.

The surfaces of the flow disturbers 17 facing the direction of rotation preferably have an inclination of 10 ° to 80 ° relative to the base plate. The surface (s) of the flow disruptors 17 facing away from the direction of rotation advantageously have an inclination of 80 ° to 90 ° relative to the base plate

The individual planes E-H are shown in cross section in FIG. 22, the offset arrangement of the disks of the axis 58 being clear.

In FIG. 23 (and in FIG. 24) one can see an embodiment in which two flow interrupters 17 running in the flow direction and opposing the direction of rotation are arranged on the base plate of the closure part. The flow disruptors can extend as far as possible radially over the area of the base plate which is recessed by the mixing blades 16 or largely axially as far as the mixing blades 16. It is desirable if the flow disruptors 17 arranged on the base plate of the closure part 5 extend so far in the direction of rotation that they prevent a direct product flow on the base plate between the two product inlet openings 6, 7 together with the mixing blades 16 in every resting position of the mixing axis 8 , The surface of the flow disturbers 17 facing the direction of rotation generally has an inclination of 10 ° to 80 ° relative to the base plate in the direction of rotation. The surface of the flow disruptors 17 facing away from the direction of rotation advantageously has an inclination of 80 ° to 90 ° relative to the base plate in the direction of rotation.

LIST OF REFERENCE NUMBERS

1 chamber part

2 discharge opening

3 chamber part, front end

4 chamber part, rear end

5 closure part

6 Entry opening of the smaller component

7 Entry opening of the larger component

8 mixer shaft

9 mixing element

10 mixing element

11 fixed deflection element

12 Exit opening of the buffer chamber

13 separating edge for product flow division

14 narrowing expansion of the mixer axis

15 narrowing expansion of the mixer axis

16 mixing element

17 baffles

18 channel, as an entry opening into the mixing room

19 edge

20 radial limitation of the buffer chamber

21 mixing room

22 buffer reservoir / chamber

23 mixing element

24 baffle of the mixing element

25 Bevel of the mixing element on the back

26 surfaces running in the radial plane

27 mixing element

28 Mixing element 29 Mixing element 30 Mixing element 31 conical flow channel 32 conical flow channel 33 axial connection of second mixing elements 34 axial connection of second mixing elements 35 axial connection of second mixing elements 36 axial connection of second mixing elements 37 bend 38 inlet connector, inside 39 inlet connector, outside 40 orientation aid 41 orientation aid 42 orientation aid 43 orientation aid 44 further outlet connection of the small component narrow outlet connection of the small component outlet connection of the large component storage container of the small component storage container of the large component oblique, radial boundary of the buffer chamber ventilation slot of the buffer chamber ventilation slot of the buffer chamber ventilation opening of the buffer chamber ventilation opening of the buffer chamber ventilation opening of the buffer chamber narrowed flow cross-section flow cross-section eccentric axis of the M axis

Claims

claims

1. Arrangement for the production of dental impression materials in which dental materials of different consistencies are pressed and mixed isolated from one another from storage containers through outlet openings in the storage containers into a mixer, the inlet openings of which are matched to the outlet openings of the storage containers, characterized in that the arrangement comprises at least two of the following elements comprises: a) an extended buffer reservoir (22) compared to an inlet opening (7), which is not separated from the mixing chamber, b) a strand divider (13) arranged in the buffer reservoir (22), c) element at the smaller dimensioned opening (6) of the Mixer or the storage container, which prevents the larger opening (46) of the storage container or the mixer from becoming attached, d) a minimum distance between the mixer shaft (8) and the chamber wall of more than 4 mm, e) a mixer shaft (8) whose cross-sectional area has a maximum of 20% the cross-sectional area between the ridge wall, f) a mixer shaft (8) including mixing elements, which together have a cross-sectional area of less than 60% of the cross-sectional area between the chamber wall, g) mixer shaft (8) with a widening of the flow cross-section (14, 15), h) mixer shaft (8) whose mixing axis located between the mixing vane planes has a wall (57, 58) running eccentrically in the radial direction, i) closure part (5) with a flow disturbance (17) running in the flow direction and opposing the direction of rotation, j) the mixing wing (16) arranged closest to the closure part is designed such that it can only cover part of the area formed by the closure part (5).

2. A method for producing dental impression materials in which dental materials of different consistencies are pressed out of storage containers and mixed to form an impression material, for this purpose are pressed from the storage containers into a mixer, the mixer having inlet openings which are matched to the outlet openings of the storage containers, characterized in that that at least two of the following features are realized: k) a component to be mixed can be kneaded and is in particular fed to a mixer with a storage chamber (22); I) the storage chamber (22) is not separated from the mixing chamber (21); m) the components to be mixed are fed to a mixer shaft (8), the cross-sectional area of which is less than 20% of the cross-sectional area of the chamber part (1); n) the mixer shaft (8) together with the mixing elements occupies less than 60% of the cross-sectional area of the chamber part (1); o) the strand pressed into the buffer reservoir (22) is divided with a strand divider (13) in the buffer reservoir; p) the smaller inlet opening (6) of the mixer is secured against contacting the larger opening of the storage container (46) by at least one element; q) the mixer shaft (8) has, at least partially between the mixing wing planes, a widening (14, 15) of the mixer shaft (8) that narrows the flow cross section (54, 55); r) at least some of the mixing elements attached to the mixer shaft (8) partially generate a mass flow against the conveying direction; s) convey the mass to be mixed alternately in the radial direction from the outside in and back.

3. Dynamic mixer, in particular for dental materials of various consistencies, with a chamber part (1), with a discharge opening (2) at the front end of the chamber part (3), with a closure part (5) arranged at the rear end of the chamber part (4), which has a base plate, with inlet openings (6, 7) for individual components to be introduced, and a central opening for a mixer shaft (8) which can be rotated about its longitudinal axis in the chamber part (1), that the inlet opening (7) for the component (“multicomponent”) present in larger quantities widens outside the region (21) of the chamber that can be reached by mixing elements to form a buffer reservoir (22) that is not separated from the mixing space (21).

4. Dynamic mixer according to claim 3, characterized in that the buffer reservoir (22) extends around the inlet opening (7).

5. Dynamic mixer according to claim 3, characterized in that at least one end (20) of the buffer reservoir (8) adjoining the closure part (5) is at least partially shaped as a curve or bevel.

6. Dynamic mixer according to claim 3, characterized in that at least part of the inlet opening (7) is covered by a fixed deflection element (11) spaced apart.

7. Dynamic mixer according to claim 6, characterized in that the area of the deflecting element (11) facing the mixing space is smaller than the sum of the areas of the outlet openings (12) of the buffer chamber (22) into the mixing chamber (21).

8. Dynamic mixer according to claim 6, characterized in that the deflecting element (11) has on its side facing the inlet opening a separating edge (13) for dividing the product flow

9. Dynamic mixer according to claim 3, characterized in that the sum of the flow cross-sectional areas of the buffer chamber (22) is greater than that of the inlet opening (7).

10. Dynamic mixer, in particular for dental materials of various consistencies, with a chamber part (1), with a discharge opening (2) at the front end of the chamber part (3), with a closure part (5) arranged at the rear end of the chamber part (4), which has a base plate, with inlet openings (6, 7) for individual components to be introduced, and a central opening for a mixer shaft (8) which can be rotated about its longitudinal axis in the chamber part (1), characterized in that part of the buffer chamber (22), arranged between the inlet opening (7) and the mixing chamber (21), is arranged outside the direct flow path, the buffer reservoir (22) not being separated from the mixing space (21) by a boundary wall.

11. Dynamic mixer according to claim 10, characterized in that the buffer chamber (22) has at least one ventilation opening (50, 51, 52, 53, 54) arranged towards the mixing chamber (21), the cross-sectional area of which is significantly smaller than that of the inlet opening (7 ) is.

12. Dynamic mixer according to claim 11, characterized in that the vent opening (50) is axially slot-shaped at the end of the buffer chamber (22).

13. Dynamic mixer according to claim 11, characterized in that the vent opening (51, 52) is slit-shaped radially on the outside and / or inside of the buffer chamber (22).

14. Dynamic mixer, in particular for dental materials of various consistencies, with a chamber part, with a discharge opening at the front end of the chamber part, with a closure part arranged at the rear end of the chamber part, which has a base plate, with inlet openings (6, 7) for individual components to be introduced, and a central opening for a mixer shaft (8) which can be rotated in the chamber part (1) about its longitudinal axis, characterized in that both components enter the mixing chamber (21) over the available radial width of the closure part (5).

15. Dynamic mixer according to claim 14, characterized in that at least one inlet opening (6) is formed to a channel (18) open towards the mixing chamber side.

16. Dynamic mixer, in particular for dental materials of various consistencies, with a chamber part (1), with a discharge opening at the front end of the chamber part, with a closure part (5) arranged at the rear end of the chamber part, which has a base plate, with inlet openings (6, 7) for individual components to be introduced, as well as a central opening for a mixer shaft (8) which can be rotated about its longitudinal axis in the chamber part, characterized in that the distance between mixer shaft (8) and chamber part (1) is nowhere less than 4 mm ,

17. Dynamic mixer, in particular for dental materials of various consistencies, with a chamber part (1), with a discharge opening at the front end of the chamber part, with a closure part (5) arranged at the rear end of the chamber part, which has a base plate, with inlet openings (6, 7) for individual components to be introduced, and a central opening for a mixer shaft (8) which can be rotated about its longitudinal axis in the chamber part, characterized in that the cross-sectional area of the mixer shaft (8) is less than 20 % of the cross-sectional area of the chamber part (1) is.

18. Dynamic mixer, in particular for dental materials of various consistencies, with a chamber part (1), with a discharge opening at the front end of the chamber part, with a closure part (5) arranged at the rear end of the chamber part, which has a base plate, with inlet openings (6, 7) for individual components to be introduced, as well as a central opening for a mixer shaft (8) which can be rotated in the chamber part about its longitudinal axis, characterized in that the cross-sectional area of the mixer shaft (8) including the mixing elements (23, 28, 27, 30) is less is more than 60% of the cross-sectional area of the chamber part (1).

19. Dynamic mixer, in particular for dental materials of different consistencies, with a chamber part (1) with a discharge opening (2) at the front end of the chamber part (3), with a closure part (5) arranged at the rear end of the chamber part, which has a base plate, With inlet openings (6, 7) for individual components to be introduced, and a central opening for a mixer shaft (8), which can be rotated in the chamber part (1) about the longitudinal axis of the chamber, characterized in that the inlet opening (7) for the larger The amount of component present (“multicomponent”) extends to the region (21) of the chamber that can be reached by mixing elements to form a buffer reservoir (22), a strand divider being arranged in the buffer reservoir (22).

20. Dynamic mixer comprising a chamber part (1) closed with a closure part (5) and a mixer shaft (8) rotatable in the chamber part (1) about its longitudinal axis, characterized in that the mixing blades (16) arranged closest to the closure part (5) ) only cover part of the area formed by the closure part (5) and the bottom plate of the closure part (5) contains at least one flow disturbance (17) running in the direction of flow and opposite to the direction of rotation.

21. Dynamic mixer according to one of claims 1 to 20, characterized in that it has mixing elements which have a baffle surface parallel to the mixer axis in the direction of rotation and are at least partially narrower towards the rear.

22. Dynamic mixer according to one of claims 1 to 21, characterized in that the position and shape of the mixing elements attached to the mixer shaft (8) convey the mass to be mixed alternately in the radial direction from the outside in and back.

23. Dynamic mixer according to one of claims 1 to 22, characterized in that at least two of the mixing elements attached to the mixer shaft (8) in the axial direction are partially connected to one another.

24. Mixer closure part with two differently dimensioned openings (44, 45, 46), which can be tightly connected to a two-component dental delivery point, characterized in that at least one element (40, 41, 42, 43) is arranged, one or possibly several elements (40, 41, 42, 43) preventing the larger opening (46) of the component feed device from being fitted.

25. Mixer shaft of a dynamic mixer with at least two planes (9) arranged axially one behind the other, each with at least two mixing vanes (10) arranged radially one behind the other, characterized in that at least part of the mixing axis (8) located between the mixing vanes (9) has a flow cross-section (54) narrowing widening (14, 15) of the mixing axis (8).

26. Mixer shaft (8) for rotation about its longitudinal axis in a dynamic mixer with at least two axially one behind the other planes, each with at least two radially one behind the other mixing blades (10), characterized in that at least part of the between the mixing blade levels (9) Mixing axis (48) has a wall (57, 58) extending eccentrically in the radial direction.

27. Use of a dynamic mixer, a mixer closure part or a mixer shaft according to one of the preceding claims for dental materials of different consistency.

28. Use of a static chamber mixer for mixing polyether impression materials.