WO2014148884A1

WO2014148884A1 - New dipping former for producing elastic articles

Info

Publication number: WO2014148884A1
Application number: PCT/MY2014/000038
Authority: WO
Inventors: Weng Kee Richard BOEY
Original assignee: Boey Weng Kee Richard
Priority date: 2013-03-19
Filing date: 2014-03-19
Publication date: 2014-09-25
Also published as: TW201446162A

Abstract

A former assembly for the manufacture of dip product, the assembly comprising: a thermally conductive outer layer in the shape of said product, said outer layer arranged to receive a film of elastomer; a mounting for mounting said former assembly to a former holder for engagement with a conveyor chain; a heating medium within said outer layer, said heating medium in communication with an energy source for heating said medium; wherein said heating medium arranged to apply heat through said outer layer so as to cure said resin.

Description

NEW DIPPING FORMER FOR PRODUCING ELASTIC ARTICLES Field of the Invention The invention relates to the production of dipped products of elastomeric material. In particular, the invention relates to the means of drying and curing the elastomer to form the glove and other dipped products whilst it is on the former assembly.

Background

The production of elastomeric gloves and other dipped products involves a conveyor or batch system having a plurality of formers attached. The formers passes through various stages including a dipping stage where the glove formers are dipped within a liquid elastomeric resin, an oven stage for drying and curing the elastomeric film and an extended drying stage.

It is the oven stage to which the present invention is directed. The conventionaloven comprises a heating source for elevating the space within the oven to a sufficient temperature to both heat the resin so as to cure the gloves, for example, and maintain the oven at a temperature to prevent "cold spots" developing that may affect the curing process. The length of the oven is determined as a function of the speed the conveyor and the time required to cure the resin. Maximizing the rate of production of the gloves requires the conveyor to be travelling at a high speed, and so the length of the oven, to ensure sufficient curing time, needs to be of considerable length, and consequently, requires heating of a considerable volume within the oven. It follows that the energy required to heat this volume is also considerable.

By volume, the gloves and other dipped products, represent an extremely small proportion of the space within an oven. Therefore, the actual energy used to cure the resin, as compared to the energy required to maintain the temperature of the oven is also extremely small. It is estimated that the energy required to heat the oven is in the range of 90 to 95% of the total heat used. That is, the actual energy to cure the resin is only about 5 to 10% of the total energy. The cost of the wasted energy represents a significant cost of the manufacture of the glove, which is ultimately dissipated to the environment.

It follows, therefore, that any reduction or saving in this wasted energy will have a direct effect on the cost of the glove manufacture, and so provide a significant commercial advantage.

Summary of Invention

In a first aspect, the invention provides a former assembly for the manufacture of dip product, the assembly comprising: a thermally conductive outer layer in the shape of said product, said outer layer arranged to receive a film of elastomer; a mounting for mounting said former assembly to a former holder for engagement with a conveyor chain; a heating medium within said outer layer, said heating medium in communication with an energy source for heating said medium; wherein said heating medium arranged to apply heat through said outer layer so as to cure said resin.

By providing a separate heat source within each former, the ovens can be discarded from the conveyor line leading to two substantial advantages. First and foremost, the energy required to cure the glove using the system according to the present invention is only 5 to 10% of that of a prior art system. Further, the infrastructure cost in removing the ovens may lead to a substantial reduction in the amortized cost of the manufacturing plant.

Further, the length of the conveyor line may also be substantialy reduced, as there is no specific length of conveyor required for the oven stage.

Further still, the gloves may be cured at a temperature controlled by the operator at a much higher efficiency than that compared to the prior art. Whereas the prior art systems can waste in a range 90% to 95% of the generated heat to the atmosphere, it is effectively impossible to optimize the amount of energy used to cure each glove. By using a system according to the present invention, the optimal amount of energy to cure each glove may be selected and so in addition to the gross savings from adopting the present invention compared to the prior art, the ability to fine tune the energy output may also be available.

Brief Description of Drawings It will be convenient to further describe the present invention with respect to the accompanying drawings that illustrate possible arrangements of the invention. Other arrangements of the invention are possible and consequently, the particularity of the accompanying drawings is not to be understood as superseding the generality of the preceding description of the invention.

Figures 1 A and 1 B are various views of a glove former shell assembly according to one embodiment of the present invention; Figures 2 A and 2B are various views of a disassembled glove former shell assembly according to a further embodiment of the present invention;

Figure 3 is an isometric view of a glove former inner heater core assembly according to a still further embodiment of the present invention;

Figure 4 is an isometric exploded view of the glove former assembly of Figure 3;

Figure 5 is an isometric view of a glove manufacturing conveyor line utilising electrification to energise the glove former according to a further embodiment of the present invention;

Figure 6 is a side view of internal layer arrangements of a glove former shell assembly, according to another embodiment of the present invention; Figure 7 is a side view of a glove former shell assembly, which incorporates the internal layer arrangements of Figure 6;

Figure 8 is a side view of internal layer arrangements of a glove former shell assembly, according to yet a further embodiment of the present invention.

Detailed Description

The following description will refer to the invention applied to the manufacture of gloves, for convenience. It will be recognised that the invention may be applied to any dip product, including condoms, probe sheaths and other such objects formed by moulds dipping into an elastomer bath. Accordingly, the reference to glove manufacture is not to be read as limiting the application of the invention. The core invention involves providing a heating medium within a glove former assembly so as to transfer heat from the heating medium within the assembly to the elastomer formed on the outer layer, which may be an outer shell, of the former so as to dry and cure the glove. This is contrast to passing the glove former assembly through an oven heated to a temperature to not only cure the elastomeric glove film but also to maintain heat within the oven to a degree beyond that required for the resin curing.

Figures 1 A and I B show one embodiment of the internal heating system for a glove former assembly 5. The assembly 5 includes a thermally conductive outer shell for receiving the elastomeric film. In this embodiment, the outer layer may comprise an outer shell in two halves 10, 15, which may be attached to enclose the heating medium within a void 17 of the outer shell 5. The two halves may be permanent sealed, such as through heat sealing or releasably engaged to provide maintenance to the internal heating medium. Heat for the heating medium (not shown) may be provided through a connection to the holder adjacent the cuff area 20. Heat is then generated so as to apply heat to a surface of the layer 25 in order to cure the elastomer on said surface 25. A characteristic of the internal heat includes ensuring sufficient heat is generated at the extremities 30 of the glove former to establish uniform curing.

Such heating sources will depend upon the heating medium, and may include a convective heat source such as a flowing hot liquid medium, for instance water, or a conductive heat source such as heating a gel resident within the outer shell. In this case, there may be a thermally conductive member intermediate the heating source and the gel to transfer heat directly. In either case, access to the inner portion of the outer layer/shell may be through the cuff 20. This may require a modification of the holder (not shown), such as by providing an annular rotatable ring, and passing the heating conduit through said ring. Other means of heating the glove former assembly may include various forms of electrical heating as will be described with reference to further embodiments.

The outer shell/layer 5 may be of thermally conductive materials, such as modified Polyphenylene Sulfide (PPS), modified Glass Reinforced Plastic (GRP) or a ceramic material sufficient to efficiently conduct heat from the heat source to the elastomeric coating the outer layer Figures 2A and 2B show one such electrical system whereby a glove former assembly 35 has been split in half to show a left side 40 and right side 45. The assembly shown in Figures 2A and 2B may be an internal core upon which an outer layer or shell (not shown) may be added, said outer layer arranged to receive the elastomer and upon which the glove may be formed. By way of example, the inner core of Figures 2A and 2B may substitute for other heating mediums by placing within the outer layer 5 of Figure 1. It will also be appreciated that this configuration of busbars may be mounted on an internal surface of the outer shell rather than to a discrete inner core, and so have the "inner core" integral with the outer shell.

As can be seen, a busbar configuration 55, 60 is distributed throughout the inner core 35 with an isolating strip 50 for isolating the busbar arrays. In this embodiment, the busbars are arranged as elongate filaments positioned in parallel with alternating positive and negative strips. The busbars are connected at an extreme point (not shown) of the former. By applying a current from an electrical power supply (not shown) to the busbars 55, 60, resistive heat is generated, with the greater the concentration of filaments, the higher the heat generated. The resistive heat is then communicated to the outer layer (not shown) so as to heat the glove. An advantage of this arrangement is the ability to place busbars 60 at the extremities through the fingers of the glove, because of the fine arrangement of the filaments, so as to ensure uniform curing of the glove. The busbars may be placed and adhered to the surface of the core. Alternatively, they may be added as a composite within an injected moulded section. A still further alternative may include a damascene construction, whereby the busbars are placed within corresponding recesses within the internal core surface.

In one embodiment, the electrical power supply may operate in the range 5 to 50 volts, and possibly in the narrower range 10 to 30 volts. In so doing, the design system may operate at a low voltage high current. Accordingly, the electrical output is arranged to be at a safe level for human interaction.

In a still further embodiment, the heating medium may be integral with the outer layer/outer shell. For convenience, in this arrangement, the busbars may be placed on an inside face of the former. In this case, the medium may include a substantial portion of the thickness of the former. In certain circumstances, the outer shell and medium may be visually indistinguishable, with the external directed heat transfer from the busbars to the elastomer on an outer surface of the outer shell indicating the notional position of the medium.

Figures 3 and 4 show a further embodiment of the present invention whereby again the inner core 65 includes busbars 70, 80 distributed throughout the core. However, in this embodiment a portion 90 of the inner core includes an electrically conductive layer, for instance graphite. To this end, the busbar configuration includes two discrete arrays 70, 80, with the electrical connection between the arrays 70, 80 provided through the electrically conductive layer. Alternatively, the layer may be a heat generating graphite layer or a conductive polymer layer, such as polyacetylene, polypyrrole, and polyaniline The advantage of this embodiment is to provide resistive heat uniformly about the inner core and not merely proximate to the busbars. This has particular advantage in providing uniformity to the curing process. In particular, the glove extremities 95 such as the fingers require the transfer of sufficient heat to provide a particularly high quality finish to the gloves.

Whereas Figure 3 shows detail of one half of the inner core 65, Figure 4 shows an exploded view of one half of the glove former assembly 105, comprising the thermally conductive outer layer 1 15 and the inner core 65 of Figure 3. The inner core fits within the outer layer 1 15 and may be sealed permanently through heat sealing, or adhesion, or may be selectively disassembled through screws or similar.

Whilst Figure 3 shows the polarity rings 75, 85 attached directly to the inner core, it may be convenient to extend the outer layer for the full length of the inner core, and so have the polarity rings 75, 85 engaged at an end portion 100 of the outer layer, with electrical penetrations through the outer layer to connect with the respective busbars 70, 80.

It will be appreciated that whilst the embodiment of Figures 3 and 4 may provide a high quality finish compared to those embodiments of Figures 1 and 2, the costs of constnicting such a former will correspondingly be higher. It would therefore be within the control of the manufacturer to balance infrastructure costs with the quality level required of the finished product. Nevertheless, all embodiments involving the internal generation of heat from the glove former assembly fall within the scope of the present invention. The busbars 70, 80 are connected to polarity rings 75, 85, for instance with a negative polarity ring 75 connected to the negative busbars 70 which are returned through the electrically conductive layer 130 to the positive polarity ring 85 via the positive busbars 80.

Between halves of the inner core is provided a positive polarity common ring main plate 55 being a plate of conductive metal such as aluminium, copper, steel etc. The electrically conductive plate 55 is to connect the positive polarities.

Figure 5 shows the glove former assembly in context whereby a plurality of glove former assemblies 140 are mounted to holders 175 which are mounted 185 to a conveyor 180 (not shown) so as to form a glove manufacturing conveyor system 135. Here the internal core (not shown) receives a power supply through the polarity rings 145, 150 through electrically conductive tracks 155, 160 specifically a negative track 170 and a positive track 165. The polarity rings remain in contact with the tracks, and so act to rotate the glove formers in the same way the former holder at different stages within the conveyor system engage a separate track in order to rotate the holders. Thus, the means of providing a power supply to the inner core is seamlessly introduced into the conventional design for a glove system to rotate the gloves as required.

Figure 6 is a side view of internal layer arrangements 602-610 of a glove former shell assembly, according to another embodiment of the present invention. Specifically, describing in a top down order of internal layer arrangements 602-610 as depicted in Figure 6, the internal layer arrangements 602-610 include an outer layer 602, a first busbar layer 604, a heat generating layer 606, a second busbar layer 608, and a heat insulating layer 610, said heat generating layer intermediate the first and second busbar layers. The outer layer 602 is formed from a thin layer of thermoplastic material (e.g. modified PPS) which is substantially chemically inert and heat resistant, since the outer layer 602 will interact with and be exposed to the elastomer bath. Immediately underneath the outer layer 602 is the first busbar layer 604, which is an electrically and thermally conductive integral layer (e.g. thin aluminium shell), configured to function as an electrical busbar layer and also as a heat spreader. In this instance, the first busbar layer 604 is electrically arranged with a positive polarity (i.e. "+VE").

It will be appreciated that the first and/or second busbar layers may be filament arranged layers sufficient to be electrically or thermally conductive. Alternatively, and as shown in Figures 6 and 8, said layers may be continuous.

Further, it will be appreciated that the heat generating layer may be continuous, in that it substantial coats the former. Alternatively, the heat generating layer may be a discontinuous layer, such as an array of discrete "patches" placed about the former.

Disposed immediately underneath the first busbar layer 604 is the heat generating layer 606, which is a mixture of carbon nanotube graphite and ceramic power that exhibits Positive Temperature Coefficient (PTC) properties. An example of the ceramic powder, but not limited only to the described, is Barium Titanate, which is mixed in a ratio of approximately between 2% to 40%, preferably 3% to 35% and most preferably 5% to 20% (calculated by weight to weight basis of fine Barium Titanate powder) with the carbon nanotube graphite, and the resulting mixture is then bended and heat cured to form the heat generating layer 606. It is to be appreciated that the heat generating layer 606 is a solid integral layer and is about 1 -2 mm thick. In addition, the heat generating layer 606 is arranged intermediate between the first and second busbar layers 604, 608, as will be appreciated from Figure 6.

Further, immediately underneath the heat generating layer 606 is the second busbar layer 608, which is materially and structurally similar to the first bus bar layer 604, except that the second busbar layer 608 is electrically arranged with a negative polarity (i.e. "-VE"). The first and second busbar layers 604, 608 are collectively electrically connected to an electrical power source (not shown) in order to provide the necessary electrically energy to energise the heat generating layer 606 for generating heat. In other words, the heating generating layer 606 is thus a heat generating medium. Finally, at the bottom most layer of the internal layer arrangements 602-610 of Figure 6 is the heat insulating layer 610 (being formed as an integral layer), which is disposed underneath the second busbar layer 608. The heat insulating layer 610 is arranged to seal and prevent the heat collectively generated by the first busbar layer 604, heat generating layer 606, and second busbar layer 608 from further propagating inwardly of the glove former shell assembly. That is, the heat insulating layer 610 is configured to encourage outwardly, or vertical, propagation of the generated heat towards the outer layer 602 for curing the elastomer formed thereon with the heat. As a result, the outwardly propagating heat becomes more efficiently used, as compared to energy losses through horizontally directed heat transfer flow.

Further, it is to be appreciated that the heat insulting layer 610 may alternatively be in the form of a coating, rather than being formed as an integral layer.

Advantages of the internal layer arrangements 602-610 of Figure 6 include encouraging emanation and propagation of heat generated (by the first busbar layer 604, heat generating layer 606, and second busbar layer 608) outwardly and perpendicularly from, rather than along the plane of the glove former shell assembly to ensure a substantially even distribution of the generated heat for curing the elastomer formed on the outer layer 602 of the glove former shell assembly. It is to be appreciated that the definition of along the plane of the glove former shell assembly means that the heat propagates in a direction along the surface of the glove former shell assembly. In addition, the internal layer arrangements 602-610 of Figure 6 has simplicity in terms of ease in fabricating the arrangements 602-610, and thus will be cost effective. Moreover, the internal layer arrangements 602-610 of Figure 6 is geometry and dimension independent, in that irrespective of the simplicity/complexity of the shape/geometry of the glove former shell assembly, the heat generated can still be substantially distributed in an even manner across the glove former shell assembly.

Figure 7 is a side elevation view of an example glove former shell assembly 700, which incorporates the internal layer arrangements 602-610 of Figure 6. It will be appreciated that glove former shell assembly 700 of Figure 7 also incorporates a pair of polarity rings 145. 150, which are similar to that as afore described for Figure 5, and hence not repeated for brevity. In this instance, the polarity rings 145, 150 are respectively electrically configured with positive and negative polarities (i.e. "+VE" and "-VE"), but will be appreciated that the reverse configuration is also possible, depending on requirements of an intended application.

Figure 8 is a side view of another internal layer arrangements 602-606, 802, 610 of a glove former shell assembly, according to yet a further embodiment of the present invention. In this instance, internal layer arrangements 602-606, 802, 610 of Figure 8 is largely similar to the internal layer arrangements 602-610 of Figure 6, except that the second busbar layer 608 of Figure 6 is now replaced by a variant second busbar layer 802 of Figure 8. Specifically, instead of being an integral layer, the variant second busbar layer 802 is formed using an electrically conductive coating, such as for example silver conductive coating. The variant second busbar layer 802 is also electrically arranged with a negative polarity (i.e. "-VE"). It is to be appreciated that the internal layer arrangements 602-606, 802, 610 of Figure 8 can also be used by the glove former shell assembly 700 of Figure 7. This internal layer arrangements 602-606, 802, 610 of Figure 8 is advantageous in that it provides a greater flexibility to a geometry and complexity that may be adopted for a glove former shell assembly, which is especially useful for glove former shell assemblies arranged to produce surgical gloves, household gloves, or the like which have complex shapes.

Claims

1. A former assembly for the manufacture of dip product, the assembly comprising: a thermally conductive outer layer in the shape of said product, said outer layer arranged to receive a film of elastomer;

a mounting for mounting said former assembly to a former holder for engagement with a conveyor;

a heating medium within said outer layer, said heating medium in

communication with an energy source for heating said medium;

wherein said heating medium is arranged to apply heat through said outer layer so as to cure said resin.

2. The assembly according to claim 1 , wherein said heating medium includes any one of: heated liquid medium, gel and electrically conductive array.

3. The assembly according to claim 2, further including a thermally conductive member intermediate the energy source and the gel for maintaining the gel at a temperature sufficient to cure said elastomer.

4. The assembly according to claim 2, wherein said energy source includes an electrical power supply and said electrically conductive array includes a configuration of busbars mounted to an inner core so as to provide resistive heat on application of said electrical power source, said inner core positioned within said outer layer.

5. The assembly according to claim 4, wherein said inner core having a shape corresponding to the shape of said product, said busbar configuration providing a uniform distribution around said inner core.

6. The assembly according to claim 4 or 5, wherein said inner core comprises two halves, separated by an electrically conductive plate.

7. The assembly according to any one of claims 4 to 6, further including polarity rings mounted adjacent to a cuff of said outer layer, each of said polarity rings electrically connected to positive and negative ends of said busbars so as to provide connectivity to said electrical power supply.

8. The assembly according to claim 7, wherein said polarity rings are arranged to contact respective negative and positive rails, so as to maintain electrical contact for said rings as the glove former assembly moves along said conveyor.

9. The assembly according to any one of claims 4 to 8, wherein said busbar

configuration comprise two discrete arrays, said inner core including an electrically conductive layer, said electrically conductive layer providing an electrical connection between said discrete arrays.

10. The assembly according to claim 9, wherein said electrically conductive layer includes any one, or a combination of: graphite and conductive polymer.

1. The assembly according to any one of claims 4 to 10, wherein the electrical power supply is arranged to operate within the range 5 to 50V.

12. The assembly according to claim 1 1 , wherein the electrical power supply is arranged to operate within the range 10 to 30V.

13. The assembly according to claim 2, wherein said energy source includes an

electrical power supply connected to first and second electrically conductive busbar layers and a heat generating medium intermediate said busbar layers.

14. The assembly according to claim 13, wherein the first busbar layer is positioned over the heat generating layer, said first busbar layer being thermally conductive.

15. The assembly according to claim 13 or 14, wherein the first and/or second

busbar layers are continuous.

16. The assembly according to any one of claims 13 to 15, wherein said heat

generating layer is continuous.

17. The assembly according to claim 15 or 16, wherein the first and/or second

busbar layers include a metallic shell.

18. The assembly according to claim 17, wherein the first busbar layer includes an aluminium shell.

19. The assembly according to any one of claims 13 to 18, wherein the heat

generating medium includes a mixture of carbon nanotube graphite and ceramic powder having Positive Temperature Coefficient (PTC).

20. The assembly according to claim 19, wherein the ceramic powder includes

Barium Titanate powder.