| Full Text |
MILKING DEVICES
The present invention relates generally to devices and components for milking apparatus, in particular to components of such devices such as milk extracting devices, and liners. In particular aspects it relates to a liner comprising a teat receiving flexible sleeve, and optionally a snort milk tubing, preferably but not necessarily integrated •with the i liner, and made from Thermo Plastic Elastomers (TPE), in, combination with thermoplastic polymers.
Background of the Invention
Machine milking has been available for about a century. The basic construction of a. milking device, which is sti 1 in use today is based on an invention patented by Gillies in 1902, and comprises a double chambered teat cup designed to
operate with a pulsating vacuum. The teat cup comprises a flexible sleeve made
j of rubber, forming one flexible wall of a chamber, where the teat cup shell
forms the other wall. In the apace between the two walls a pulsating vacuum is applied whereby the sleeve will expand and contract, thereby causing a massaging action on a teat on which, the teat cup has been applied.
'I
The flexible sleeve is provided as a part of a so called teat cup liner (or inflation in US English; in the present specification and claims the term "liner" will be
used throughout).
A milking apparatus as a whole fcompriaes a number of different components, many of which currently are ma
As an example, a, modern teat c"Cp system is disclosed in US-G, 176,200 (Petterson). It comprises a tubialitr head portion capable of receiving a teat, and a shaft portion forming an inner wall of the pulsating vacuum chamber. The shaft portion is flexible and nonxjtally made of a rubber compound.
In order to be accepted by the market, devices fanning the components of milking apparatus, such as teat cups and liners, must exhibit a number of properties. Examples that can be mentioned are the following:
Good milking performances, e,gj., milk speed, milk yield, slip, strip yield Good teat treatment
Long lifetime of the device and capability of functioning at the same high level of performance over the entire lifetime,
Uniform quality of ttie devices.
i Chemical and physical endurance
Devices should be easy to clean! Devices should be easy to replace
Devicea should be envirdntnentally friendly, e.g., recycling of the material should
i
be possible j
Low energy consumption manufacturing
The product must comply with regulations relating to material and to articles and products that are intended to come into contact with foodstuff.
1 i Currently available components of milking apparatus, such as liners and tubing,
are most often made of rubber materials, which do not meet the above requirements to a totally satisfactory degree.
Applicants' own PCT/SE03/02024 discloses a novel approach to the manufacture of milking devices by using TPB type materials. The invention disclosed offers a number of advantages over prior art devices and methods.
Summary of tie Invention
Despite the improvement that the above described invention provided, there is
i
still room for further improvemer4t.
The present invention therefore seeks to provide improved devices and components usable in milking apparatus that meet all the requirements listed above. The invention shall alsoijenable even more versatile tailoring of devices. This is achieved in accordance [with the invention in a first aspect by a milking device which is defined in claim 1, namely by making a milking device from a combination of a soft and a hard material, namely TPE and thermoplastic material, respectively.
Preferably, the milking device is
an improved teat cup liner.
Thus, there is provided a milking device comprising at least a teat-receiving flexible sleeve, adapted to be positioned on/over a teat. It is characterized in that at least a First portion thereof comprises a material, selected from the group consisting of
thermo-plaatic elastomers (TPE), second portion thereof comprises thermoplastic materials.
as defined in ISO 18064, and in that at least a a material selected from the group consisting of
The milking apparatus is defined in claim 15.
In a third aspect there is provided a method of manufacturing a milking device, the method being defined in claim 16.
The devices according to the invention exhibit the following advantages:
Due to the selection of materials in combination according to the invention, the ingress gates and burrs normaHy occurring in molding processes can be eliminated or at least substantially reduced, which means that tirne-consToming after-treatment for finishing purposes can be eliminated, thereby reducing the production cost.
The two-step molding according to the invention, again due to the specific material selection according to the invention, surprisingly achieves extremely smooth transitions between the different materials in connecting parts of the molded device, i.e. the different materials integrate in a manner that creates no
grooves or depressions, where bacteria or other micro-organisms could thrive, and pose a potential contamination risk. Thereby the strict hygiene requirements on this kind of equipment are met well beyond what is required by current regulations.
Furthermore, by using harder or staffer materials for those parts that are
subjected to stronger forces, the
amount of material required can be reduced,
compared to the prior art devices. E.g. snap fit couplings can be made with much less material. Harder materials tlao offer better tolerances in components. Also, there will in general be at larger freedom in construction/design options.
A particular feature worth mentioning ia that variations in the parameters influencing teat massage can be .reduced with the materials according to the invention.
A liner, as it is designed today, has different parts performing different functions. The sleeve will work dynamically, whereas the connection to the claw will work statically and has the function of a sealing. In one embodiment it is suggested according to the invention that the short milk tubing and the attachment against the teat cup central be made from, a stiff/rigid material. This would render the attachment simpler by means of a quick coupling, in a broad sense, which is much easier to achieve with a rigid material than with soft rubbery material. The sleeve] on the other hand, is made from a soft
rubbery material for the purpose properties.
of achieving optimal massaging and milking
For the particular application of the inventive concept to (teat cup) liners, there are a number of specific and unexpected advantages of using TPE.
Namely, production related advantages are e.g.: the production cost •will be more attractive; it will become easier to obtain closer tolerances in the produced items, thus it will become easier to predict the properties of the final product; the material spillage can be reduced; less variations in the production process gives more uniform product properties from batch to batch; use of the materials
according to the invention will. However, the most unexpected property
make welding possible as a production means. is the high resistance to fatigue.
Environmental advantages to b'e mentioned are: recycling of production scrap material is possible directly back into production, by granulating the spillage; leaser amounts of potentially hirmful additives, thereby making handling will become less hazardous for stall', e.g. no vulcanization gases will be present
Further scope of applicability ofithe present invention will become apparent from the detailed description given hereinafter and the accompanying drawings which are given by way of illustration only, and thus not to be considered limiting on the present invention, and wherein
Fig, 1 shows an example of a prior art device for a milking apparatus, namely a teat cup and a liner; and
Pig, 2 is a schematic illustration a teat cup Ener in cross section,
of an embodiment of the invention in the form of embodying the concept of the present invention,
namely that of uaing different materials in different parts. Detailed Description of Preferred Embodiment*
For the purpose of this application, a "milking device* aa the term is used throughout this application, is taken to mean any device used in milking
systems. |
i
The expression liner" or "teat cup liner" is taken to encompass a device usable together with a milking apparatus or system, that is to be used in the dairy business e,g. in contact with the jtnilk, and therefore must comply with regulations relating to materials and articles intended to come into contact with foodstuffs. A liner comprises at least a teat receiving flexible sleeve, adapted to be positioned on/over a teat, suitably in a close fit. At the end proximal of the teat receiving end, there can be provided a short milk tube, to be attached to
the teat cup central, It can also comprise a supply tubing for pulsating medium,
referred to as a "pulsation tubing". It is to be noted that the liner according to
•j the invention may be used for various different animals, e.g. cows, bufialos,
sheep and goats and other ruminant animals.
"A teat cup" is taken to be a device comprising a housing, "teat cup shell9 in which a liner, as defined above is mounted or formed as an integral part thereof. In particular a teat cup can be a. milk extracting device, i.e. a device constituting a part or component of a milkini [ apparatus that acts on the teat of an animal, or cooperates with other parts of the milking apparatus, such that the udder will release milk in a controlled manner. A teat cup comprises a liner, which in its turn comprises at least a flejtibls teat receiving sleeve, adapted to be positioned on/over a teat in a close fit.
For the purposes of the present application, the expression "thermoplastic polymer" is given the ordinary meaning of that term within the field of polymer technology. Currently, in the present invention, semi-crystalline thermoplastic polymers are preferred, although other types of thermoplastic polymers are possible. Typical examples of preferred thermoplastic polymers are polyolefins
(polypropylene, polyethylene etc}'
and polyamides. It can also encompass
copolymers of polyolefin monomers, and it can further comprise various types of fillers, such as glass fibers, carbon fibers, mineral fibers, metal fibers etc, or other conventional fillers usable in polirmers. It should be noted that thermoplastic
materials are taken to be a class
In Fig. 1, an exemplary prior art teat cup is disclosed. It is provided, with a teat cup liner 1 which is mounted in a teat cup shell 2. The teat cup liner 1 is essentially rotationally symmetrical with respect to a longitudinal axis 3 and comprises an upper tubular head portion 4 and a tubular, flexible teat receiving sleeve portion 5 extending downwardly from the head portion 4. The head portion 4 comprises a first upper end 6 and a second lower end 7. At the upper end 6, the tabular head portion 4 comprises a lip 8 extending radially inwardly and defining an essentially circular central opening. The tubular head portion 4 forma
uiruugn me neaa to me toner space of the teat cup liner for receiving a teat in the sleeve 5. The lower end 7 comprises an annular recess 9 which is engaged by the upper end portion of the teat cup shell 2. The lower part of the sleeve 5 comprises a peripheral surrounding recess 10 which is engaged by the lower end portion of the teat cup sheD 2. The recesses 9 and 10 are shaped in such a manner that a closed apace 11 is formed between the teat cup liner and the teat cup shell 2, which space 11 forms a pulsating chamber of the teat cup.
In its lower part, the teat cup lider 1 connects to prolongation pieces 12 and 13,
j
which form a milk conduit whicf
may be connected to a claw (not disclosed). The
teat cup liner 1 is manufactured! in an elastic material, for instance natural or synthetic rubber.
In accordance with the present invention, by the surprising flexibility in the employment of the class of materials discussed herein, broadly denned by the specified material properties, and exemplified by thermoplastic elastomers, in
combination with thermoplastics!
such as polyolefins (polypropylene (PP),
polyethylene (PE) and the like) or, polyamides (PA), it will in particular become possible to manufacture devices exhibiting different mechanical and physico-chemical properties in different pi irts or regions of the device, thereby enabling a tailoring of properties for specific ..uses. Thereby different portions, i.e. a first portion, a second portion etc, cad be made of different materials. In particular, TPE in a first portion can compline a thermoplastic material which is compatible with and preferably very similar to the thermoplastic material in a second portion.
to have
The term "compatible" is taken ordinary skilled man in the field
the meaning in a broad sense that the of polymer technology would give it.
On the internet at http://www.fil>erset.com/html/^ossary/glc>s_c.htm the following meaning of compatible in to be found: "The ability of different resin systems to be processed in contacjt with each other without degradation of end product properties".
Another meaning of compatible is "capable of being used with or connected to other devices or components without modification*.
These additional meanings are: taken to be encompassed within the definition commonly used in the polymer filed.
In the particular case of this ini wntion, the result of the compatibility is that the two materials in different portions of the device will form a joint that is very much like a weld. Preferably the materials are very similar or even practically identical.
In preferred embodiments the TPE material has a hardness of 50 - 90 shore A, and a tensile strength of 4 - 8 MPa.
The invention ia based on the fin iing that although the TPE materials usable for milking devices, as disclosed in PCT/SE03/02024, increase the design possibilities for milking devices in general, and teat cup liners in particular, they are nevertheless not so versatile from a design or constructional point of view as one could wish for.
The inventors have surprisingly discovered that thennoplastcis [such as polypropylenes, polyerthylenes and/or polyandries) in combination with TPE materials will open up a new dimension of constructional/design possibilities. Thus, by selecting TPE's and thermoplastics having suitable properties, these materials can be combined in a large number of ways. On one hand, different parts can be made from different materials and combined and integrated, i.e. by mechanical (physical) connection
A brief summary of TPE materials given.
suitable for use in the invention will first be
Thermoplastic elastomers (TEE)
Before the development of TPE:ii there were generally speaking only rigid or semirigid articles products that could be manufactured and processed with, the new technology for thermoplastics. The production of thermoplastics is faster, less energy consuming, cleaner and; i is easier to re-use scrap.
For elastomeric materials there was a lack of alternatives for thennoset rubbers. For applications not exposed to extreme temperatures there is no fundamental need for temperature resistant orosslinking-sites. The use of thermoset rubbers will have the accompanying disadvantages of the crosslinlting..
The incentivea for developing thermoplastic materials exhibiting elastic properties without any permanent cro&alinlong sites have therefore been strong,
Thermoplastic elastomers (TPE) properties of a thermoplastic material material.
are materials that combine the processing
with the elastomeric properties of a rubber
Thermoplastic elastomers are two-phase systems. One of the phases is a hard polymer that gives the mechanical strength at service temperatures but becomes fluid when heated above the melting- or glass transition temperature (Tj). The other phase i$ a soft rubbery polymer.
There are principally two ways to
achieve the properties; namely by providing the
material in the form of block copplymers or polymer blends.
Block copolymera meeting the definition of thermoplastic elastomers consist of two phases, one hard and one soft, formed from segments in the same chain of a molecule. The harder segment could be crystalline with a high melting temperature or an amorphous material with a high glass transition temperature. The soft segment is always amorphous with a very low glass transition temperature.
TPE made from polymer blerxdsJare blends of a hard material, almost exclusively semi-crystalline with a high melting temperature in a continuous phase blended with a softer at least mainly amorphous material with a very low glass-transition temperature.
According to ISO 18064 TPE means Thermo Plastic Elastomers in general. The exact definition given in ISO li8064:2003(E) is as follows:
TPE: Thermoplastic elastomer, consisting of a polymer or blend of polymers that has properties at its service temperature similar to those of vulcanized rubber but can be processes and reprocesses at elevated temperature like a thermoplastic."
Thermoplastic Vulcanlsates (T] *V)
Thermoplastic vulcanisates fIP\ thermoplastic continuous phase phase, The dominating system1 is
are two-phase systems consisting of a and a crosslinked rubber as the discontinuous PP/EPDM but there are also PP/NBR systems.
The rubber phase is more vulcanised than TPOrs where the rubbery phase is just
I
partly or not vulcanised. The vulcanisation of the rubber phase results in numerous properly improvements.
General Properties of TPV materials:
Density (kg/dm3) 0.9-1.0
Shore Hardness , 35A-50D
Low temperature limit °C -60
High temperature limit (continuous) °C 135
Compression set resistance at 10.0'C Q
Resistance to hydrocarbon fluids G/E
Resistance to aqueous fluids G/E
Price ratios 2,5-3.0
Thermoplastic Qlefins TPO:s
Thermoplastic oleflns, as defined by ISO, are blends of polypropylene (PP) and ethylene-propylene copolymer (EPM) or ethylene-propylene-diene polymer (EPDM), The term EP(D)M covers both EPDM and EPM.
PP-EP(D)M blends are produced by intensive mixing of PP and EPDM and/or EPM.
The polypropylene is normally an isotactic homopolymer or an isotactic PP with minor content of ethylene. The melting point of these semi-crystalline polymers are in the range 145-165°C,
A TPO can therefore retain many of its mechanical properties at high
temperatures.
An EP(D)M with 50:50 ratio ethylene and propylene are almost completely
amorphous although both polyetiylene and polypropylene are semi-crystalline
polymer. Changing i.e. the ethyleiie content to a higher ratio gives some
| crystallinity. The net effect of a small amount of ethylene crystaUinriy grea%
influences the strength of the rubber.
Properties:
in any ratio, there is theoretically a
PP to EP(D)M reinforced
Since PP and EP(D)M can be blended
continuous spectrum from lightly modified thermoplastic
with thermoplastic.
(Table Remove)
device, and in particular a
In accordance with the present invention, a teat cup liner, as defined previously, is made of a material including one or more materials in combination selected from, a group of materials including the above discussed, and thermoplastic x&irterials, The thermoplastic materials that are contemplated comprise any material selected from polyolefins, such as polypropylene, polyethylene etc;; and poryamides. These materials (TPE vs ) differ in properties mainly in terms of their flexibility. Thus, those portions or parts of the device that need to tie soft, e.g. the teat-receiving parts cf a teat cup liner for a milking apparatus, e.j;, the membrane portion located on the top of the device, said membrane havir ,g a teat receiving opening are made of TPE's. Also, in case the device has a short milk tubing connected or integrated therewith, such tubing is also prisferably made of a TPE.
Those parts having a connecting function, ie. couplings and the like, in particular snap fit couplings for correcting the milk tubing to a liner or parts
having a supporting function, are made of a suffer material, such as
:j thermoplastics, such aa polyolefins (e.g. polypropylene, polyethylene) or
polyamide.
The following list contains examples of properties that a liner having a. flexible sleeve based on TPE, and that is connectable to the teat/ animal and to the overall milking system should exhibit.
- It must fae capable to remove milk from the udder of an animal by means of
vacuum means
- It should be capable of transporting milk within closed systems
- It should be connectable via aa interface to the overall milking system
- The teat should be subjected to masaage
- The flexible sleeve should stimulate the animal
- The flexible sleeve should comply with regulations relating to materials and
articles intended to come.into contact with foodstuffs
I
- The flexible sleeve should be able to act as a barrier and should not be
influenced by the milk
-The flexible sleeve should have!
a tension or compression being constant or
variable
- It should exhibit a sealing function
- The flexible sleeve should be attachable to the teat automatically or manually
- The flexible sleeves functionality should be controllable
- The flexible sleeve is baaed on ia material that ahould withstand the milking
environment ;
- The flexible sleeve is based on ia. material that should be processable
- The flexible sleeve should be possible to fix and seal against an outer hard
shell
- The flexible sleeve should fit teats of all sizes
- Preferably the flexible sleeve should consist of one or many material or
combinations thereof
-The flexible sleeve is based on a
material that consists of TPE or TPE in
combination with other materials i
- Smooth milk-transport should be allowed
The above criteria are met with, a liner having at least a flexible sleeve made of a material that comprises a TPE, as defined in ISO 18064.
The thermoplastic elastomer according to the invention,
- A hardness between 25 shore
- A Young's modulus between
- A tensile strength typically
- A minimum elongation of 50%
material (TPE) used for the milking device sh.oj.zLd exhibit (at least) the following properties: A and 50 shore D O.lMPaandSOMPa above 0.5 MPa
without breakage
Optionally the milking device should exhibit
- A service temperature typical!}
between -60C and +200C
Suitably the material is resistant to acids, in particular formic add, propionic acid, peracetic acid, and/or HzCja, The material is also preferably resistant to alkali, in particular to ammonia! NaOH and KOH, in concentrations commonly used in washing or cleaning procedures used in the dairy industry.
The material should also be resistant to chlorine, ozone and to UV irradiation and thermal oxidation.
In preferred embodiments, the- material exhibits a tear strength between 5 and 50 kN/m, preferably 15-35 kN/iu.
i
In preferred embodiments, the material exhibits a tensile strength of 0.5-40 MPa, preferably 5-20 MPa.
It should also in preferred embodiment exhibit an elongation which is more than 200% before breakage, preferably more than 300%.
The material may be a thermoplastic vulcaniaate (TPV), comprising two phases consisting of a thermoplastic continuous phase end a cross-linked rubber as a
discontinuous phase, wherein the
thermoplastic elastomer comprises a rubber
selected from butadiene rubber; silicons; EPDM; NBR optionally grafted with acrylates or anhydrides,
g-
than the flexible sleeve has.
The thermoplastic elastomer prsferably also comprises a, crystalline polyolefin selected from polyethylene (HDipE, LDPE or LCDPE), polypropylene, or mixtures thereof, for example copolymers. By virtue of the excellent processabUity of the materials selected in accordance with the invention, it becomes possible to tailor liners to a large number of different applications or needs within the field of milking. Thus, it is possible tio manufacture liners in a simple molding process to high dimensional accuracy, while combining different materials in different parts of the product E.g. it is possible to provide the head portion and milk tube with a higher rigidity
A class of TPE materials which are suitable for the purposes of the invention are the SANTOPRENE® materials available from Advanced Elastomer Systems, These are thermoplastic elastomers suited for applications in contact with aqueous food and meet the requirements by the Directive 90/128/EC and its amendments. They can be processed by injection moulding and are fully recyclable.
Below are listed typical test values for three SANTOPKENE® materials (for injection moulded plaques, end gated 100mm x 150mm x 2 mm).
(Table Remove)
Preferred values for the TPE material in a milking device according to the invention are a hardness of 50 - SO ahore A, and a tensile strength of 4 - 8 MPa,
The thermoplastic to be used for the stiffer parts of the device according to the invention should preferably have the following properties:
- A Young's modulus between 80
>0 and 8500 MPa, preferably between 1000 and
6500 MPA, most preferred between 1100 and 1300 MPa
- A tensile strength typically between 25 and 140 MPa, preferably 30 - 60 MPa,
and more preferably 35 - 90 MPa.
!
The thermoplastic material can cptibnally be reinforced with, glass fibers, in which case the overall tensile strength will be in the upper part of the above intervals. Other fillers selected from other fiber materials auch as carbon fibers, mineral fibers, and other conventional fillers can be employed for specific
applications according to need,
In a particular embodiment of the present invention, there is provided a teat
sup liner wherein it is specifically
the flexible teat receiving sleeve portion of the
.terial
liner that is made of such a ma
or material combination. A liner 20
according to the invention is schematically illustrated in cross-section in Fig. 2, as mounted in a likewise schematically represented teat cup shell 21. The liner comprises a head portion 22, a fiepdble sleeve portion 24 for receiving a teat in a substantially close fit. By "close fit" is meant that there will be no significant amounts of air leaking in from between the teat and the sleeve in operationi i.e, during milking. The sleeve extends from the head portion 22 to a connecting
part 27 where a short rnilk tube is connectable to the sleeve 24. Alternatively the milk tube can be integrated with the sleeve.
Suitably the connecting part 271 is made firom the stiffer material (thermoplastics) in order that the liner can. be rigidly attached to the teat cup ahell 21, so as not to cause leakage. It is important that the sleeve be fixed in a defined and particular position in the shell.
Furthermore, the teat cup shell is to he connected to a supply of pulsating
medium in order that the sleeve
of the liner be able to perform its function- This
supply is provided via a pulaaticn tubing connectable to the teat cup ahell 21 at an inlet connector 23, such that the pulsation can act on the aleeve 24.
The most important element of a liner is the flexible sleeve 24, in the sense that it is this element that performs the function by alternatiragly collapsing and opening/ expanding, caused by the pulsating vacuum applied, Thus, in order that the liner be able to fulfil ita technical function, at least the flexible sleeve must meet certain criteria with respect to material properties.
A number of embodiments based] on material selections and material combinations are possible. All su sh variations and modifications are applicable to all devices within the generic definition of the device according to the invention.
Thus, it is possible to make a device according to the invention (e.g. a liner,
possibly comprising a short milk tubing and/or a short pulsation tubing) by
i using several variations or modifications in terms of material combinations, to
provide for suitable properties for1
each specific use or application of the device
according to the invention. Also, different parts of a device may be provided
with different properties, adapted
to the kind of environment that the specific
part or portion of the device will come into contact with.
i
I
In particular it ghouid be noted that it is within the inventive concept to use more than one TPE material in combination with one or more thermoplastic
material. Thereby, e.g. the exterior surface of the flexible sleeve can be given different properties than the inner surface, such as different in terms of hydrophobia /hydrophilic properties, Various degrees of stiffness can also be achieved by using different grades of e.g polyolefins.
the method according to tb e invention will be described,
Suitably the devices described above are manufactured by injection molding of one or more materials according to the desired properties. Alternatively, if the structure is more complicated, injection molding or other molding techniques are preferred. Thus, devices comprising two or more materials in combination, i.e. forming a composite material, can be joined together in several ways. Dual injection of two (or more) materials in sequence in one and the same mold can be used. Another option is to make a "precursor" from one material in a first mold, and then move the "precursor" to a second mold in which one or more further materials are injected. ItJis also possible to injection mold or extrude the
different components separately
using different materials, and then weld the
components together. Certain cc mponents or parts, can be coupled by simply putting one together with the oti ter.
processes in detail to obtain the obtain them, and such methods herein.
However, it wiU pertain to the field of the skilled man to design the molding
desired structures and the set ups necessary to will therefore not be discussed in further
The method according to the invention for making a milking device, in particular a teat cup liner, is in a preferred embodiment a two-step molding process. However, it is within the inventive concept to perform more than two steps for making more complex structures.
Thus, in the first step, in a preferred embodiment, a thermoplastic, preferably
i
portions of the device that are to couplings. The mold comprises a
polypropylene (PP) or polyamide (PA), is injected in a mold defining only those
exhibit a higher stiffness or rigidity, such as core defining an inner lumen of the device.
The core, now carrying the above mentioned stiffer parts, is demolded from the mold, and placed in a second mold, into which, as a second molding step, a suitable TPE is injected. Alternatively, the core can be placed in a second cavity but in the same mold, or even jm the same cavity if the mold is adjustable to a different shape, defining the second molding structure or component.
The second (and further if required) molding step defines the remaining portions of the device to be map e. Because TPS and the thermoplastic are compatible, due to the fact that the matrix material of the TPE is very similar, if not identical to, the thermoplaeiic used in the first step, there will be a very good connection between the materials, and they will in practice be "welded" to each other. Transitions between the two materials, i.e. between stiffer and softer portions, will be near perfect, By "near perfect" we mean that there will be no perceivable steps or groovesi where the two materials meet. Thus, bacteria or other micro-organisms and orgafnic material, such as milk residues, serving as nutrition for bacteria cannot in iaet become trapped in these transition regions. From a hygiene point of view this is essential, and an important feature of the method and of the device according to the invention.
In the upper part of a teat cup Hner, where the teat is located in use, one can provide a suffer part for providing coupling functionality, while at the same time keeping the actual teat contact surface smooth, such that the risk of causing
sores on the teats is minimized
r even eliminated.
In, the particular embodiment shown in Fig. 2, the teat cup liner is made as two separate parts connectable by means of a anap fit coupling 28. Thus, the top or head portion, including the teat-receiving opening 26, is made as a "lid* 22 that can be connected to the remaining part comprising the actual flexible sleeve of the liner. Thereby, the lid is made in a two-step process. Thus, preferably the hard, ring shaped coupling portion is made in a first step, and while warm and still in place on. the mold core, placed in a second mold where the TPE is injected to form the membrane, portion having the teat receiving opening.
The sleeve part, having two couplings, one on the top (in the head portion) for connecting to the lid, and one at the bottom for connecting to a milk tubing or a teat cup shell is also made as outlined above in a two-step process.
Although the above described molded in the first step, and step is the preferred way, it is mold soft parts before the hard two approaches, and the skilled suit either procedure.
the
method wherein the stiff or hard parts are
soft or flexible parts are molded in the second possible to do it the other way around, i.e. to parts. There is no fundamental difference in the man can easily adjust molding parameters to
For certain applications it may :DC required to use more than one TPE for different parts of a device, and/or more than one thermoplastic for different parts. In such a case, the manufacturing process may have to be performed in more than two steps, where one step is used for each material. However, it is also possible that two different: naterials can be injected simultaneously in different parts of the mold. Such variations in the process pertains to the field of the man skilled in the art, ana is per se not part of the invention.
It is to be noted that due to the with thermoplastics, and due to
selection of materials, i.e, TPE in combination the compatibility between these materials, it is
very simple to tailor details in- the design to specific needs.
As an example, it is a straight forward design option to introduce sealing rings directly within the harder portions of the device, by molding the TPE in suitable channels having a ring geometry. Because the materials integrate «o well, there will be provided good sealing functionality.
CLAIMS:
1. A milking device comprising at least a. teat-receiving flexible sleeve,
adapted to be positioned on/over a teat, characterized in that at least a first
portion thereof comprises a material, selected from the group consisting of thermo
plastic elastomers (TPE), as defir ed in ISO 18064, and in that at least a second
portion thereof comprises a material selected from the group consisting of
thermoplastic materials.
2. A milking device as claimed in claim 1, wherein the TPE exhibits the
following properties:
a) & hardness between 25 shore A and 50 shore D;
b) a Young's modulus between O..Q. MPa and 50 MPai
c) a tensile strength above 0.5 MPa; and
d) a mi"JTn'"m elongation, of 50%
without breakage; and
wherein the thermoplastic exhibits the following properties,
i) a Young's modulus between 800 6500 MPA, most preferred between ii) a tensile strength typically beto reen and more preferably 35 - 90 MPa.
and 8500 MPa, preferably between 1000 and 1100 and 1300 MPa
25 and HO MPa, preferably 30 - 60 MPa,
3.
A milking device as claimed in claim 1 or 2, optionally exhibiting a
service temperature between -60'C and -f 20D"C.
4. A milking device aa claimed in any of claims 1-3, wherein the TPS in
the first portion comprises a thermoplastic material which is compatible with
and preferably very similar to thu thermoplastic material in the second portion.
5. A milking device as claimed in any of the preceding claims, wherein
the TPE material has
a hardness of 50 - 90 shore A;
a tensile strength of 4
- 8 MPa.
6. A milking device as claimed in any of claims 1-5, -wherein said
thermoplastic material comprises a material selected from polyoldms, such as polypropylene^ (PP), polyethylenes (PE); and polyamides, or combinations thereof.
1, A milking device as cljs|imed
further portion comprising a diffierent
in any preceding claim, having at least a TPE material from that of the first portion.
8. A milking device as claiimi
surface of at least a part of the device of an inner surface,
ed in any preceding claim, wherein an exterior comprises & different TPE material from that
9. A milking device as claimed in claim 8, wherein the surface properties
differ in terms of hydrophobicity/hydrophilicity.
claimed
10. A milking device as
dements integrated in the device,
in any preceding claim, comprising sealing said sealing elements comprising a TPE material.
11.
A milking device as claimed in any preceding claim, comprising two
parts, a first part comprising said
flexible teat-receiving sleeve, and a second part
comprising a top lid having a membrane with a. teat-receiving opening, said parts being connectable by means of,a .snap-fit coupling, wherein said membrane and
said sleeve are made of a TPE and
said coupling is made of a thermoplastic.
12. A milking device aa claimed in any preceding claim, wherein the
thermoplastic material further comprises fillers selected from fiber materials such
as glass fibers, carbon fibers, mineral fibers, metal fibers, and other conventional
filler a.
13. A milking device as claimed in any preceding claim which is a teat cup
liner, having
a flexible aleeve made of a TPE;
a top portion comprising a membrane with a teat-receiving opening, made of TPE, said top portion and flexible sleeve being connected via a snap-fit coupling made of a thermoplastic;
a bottom part serving as connector for a milk tubing.
14. A milking device as claimed in claim 13, further comprising a short
milk tubing, connected to the bottom part via snap-fit coupling that is made of
a thermoplastic.
15. A milking apparatus comprising a milking device as claimed in any
preceding claim.
16. A method of making a milking device comprising at least a teat-
receiving flexible sleeve, adapted to be positioned on/over a teat, comprising the
steps of:
providing a mold having a cavity and a core;
molding at least one part of said device in said mold using at least one first polymer material;
molding at least one further part of said device using at least one second polymer material;
optionally repeating the steps of molding as required by the design of the device, using the same or other polymer materials; wherein
the polymer materials are selected from TPE polymers and thermoplastic polymers, and wherein a TPE polymer is used for at least one part of the device, and a thermoplastic polymeris used for at least one other part.
17. The method as claimed in claim 16, wherein in the first molding step,
the first polymer material is a TPE, and in the second molding step, the second
polymer material is a thermoplastic.
18. The method as claimed in claim 16, wherein in the first molding step,
the first polymer material is a thermoplastic, and in the second molding step,
the second polymer material is a TPE.
19. The method as claimed in any of claims 16-18, further comprising
demolding the core carrying said at least one part, and placing the core in a
second mold.
20. The method as claimed in any of claims 16-18, further comprising
demolding the core carrying said at least one part, and placing the core in a
second cavity in the same mold.
21. The method as claimed in any of claims 16-18, further comprising
adjusting the mold to define a second shape for molding a further component.
|