GB2521645A - Vacuum metallizers and methods of operating vacuum metallizers - Google Patents

Abstract

A vacuum metallizer for coating a substrate comprises a winding zone 5 and an evaporation zone 4, with a seal 1 being provided between the winding zone and the evaporation zone. The seal 1 is configured to seal the evaporation zone 4 from the winding zone 5 sufficiently to prevent, in use, gas moving between the two zones when the seal is inflated. The metallizer further comprises at least one valve (15; figure 5) which is specifically controllable to deflate and/or inflate said seal. Preferably, two valves (16, 17; figure 5) are provided, one to inflate the seal 1 and one to deflate the seal. Preferably, the seal 1 comprises a flexible inner portion 2 and a more rigid outer portion 3, the inner portion 2 being inflated and deflated to displace the outer portion 3 between open and closed positions. A method of operating the vacuum metallizer is also disclosed.

Description

Vacuum Methllflhodsfoperaflngvacmmethlnz ta Lie Wf eJnvent1Qn The invention relates to vacuum metakizers for coating a substrate and methods of operating a vacuum metallizer. In a preferred embodiment, the invention relates to an inflatab[e/deflatable seal arrangement for use in a vacuum metattizer.

rdtotention The closest prior art known to the appUcant are their own prior art vacuum metallizers incorporating flexible seals to allow sealing between their winding section and theft evaporation section, The prior art flexible seals incorporate two sections, an inner and an outer seal section, The inner section is an inflatable tube and the outer section is a rigid at [east partly protruding i-shaped member. The flexible seal is located on the winding cart of a vacuum metallhzer, During the operation of the metallizer, the winding cart is brought ri dose seating engagement with the internal wall of the vacuum chamber of the evaporation section during the metal deposition phase and is then spaced or withdrawn from the evaporation section whilst a coated roll is removed and exchanged with an uncoated roll of substrate material which is destined to be coated.

in use, tbe, sectlqn of the seat contacts the Internal wall of the vacuum chamber In order to prevent gas molecules from moving between the winding section and the evaporation section of the vacuum metaltizer.

U However, when the winding zone is inserted and retracted from the InternaL wall of vacuum chamber of the evaporation zones friction between the Internet watt and the seat produces damage to both the wall and the seal This friction and resultIng damage it caused by the Inner inflated section of the seal pressing the outer section of the seat againstthewallatatltimes.

One of the objects of the invention is to overcome this prdb im andprcicea4 for use in a vacuum metaltizer which mlnimises the damage of the internal wait andthe seal Mother object is to provide for the spedflc control of the seat during the operation oF the metatlizer. A further object of the Invention (no pro'iide imjavementstotheseal arrangement Further objects of the invention wilt become appartit lb the detailed aspects of the following sections and wiLlte;appatanttathepean skilled In the art of vacuum metallizers. I:

Summary of the invention

n a first broad independent aspect; the inventhn provides, a vacuum metallizer for coating a s,,,,,, te, said metattizer comprising a winding zone and an evapo'ionzone a seat being provided between said winding zone and said evaporation zone said seat being.

configured to seal said evaporation zone from said winding zone suffldent to prevent; in a uses gas moving between said evaporation zone and said wincflng zone when sak, seal i Inflated; said metalluzer further comprising at (east one valve which is specifically controlLable to deflate and/or inflate said seal This configuration Is particularly advantageous betath' It mtnlflitses damage to the seal so and/ort the surface on which it wilt abut. This may. provide a valve which Is additional to any other vabm ditettly controlling the pressure of the evaporation zqn of the vaçwjm metatllzer, so that the Inflation and deflation o the -can be specifically controlled. The? operation of the seal may therefore be contrnlted separately from any of the valves provided for controlling the pressure In the vacuum chamber.

Preferably, said seal comprises first and second portions; said first portion being an inner portion and said second portion being an outer portion; said first portion being Located within said second portion; said second portion being displaceable from a first position where said seal is open to a second position where said seal is dosed; the position of said second portion being dependent on the specifically controlled inflation and/or deflation of said first portion.

This configuration offers the advantage of providing an inflatable/deflatable seal that is specifically controllable in addition to and/or separately from the control of the pressure of the evaporation zone of the vacuum metalUzer. This configuration provides a seal which may be infLated and/or deflated to minimise damage to the seal and the internal wall of the evaporation zone when the winding zone is withdrawn from and brought into contact with the evaporation section of the vacuum metalLizer, This is especially important when taking into account the cyclic nature of the operation of vacuum metatlizers.

Preferably, said metallizer incorporates a wall and said seal connects to a duct which extends through the wall of said metallizer, in preferred embodiments, this configuration allows the pressure in the seaL to be not only specifically controlled but externally controLled since the duct through the wall may provide a conduit to externally disposed control mechanisms such as a valve and a valve controller, As a result of the duct extending through the wall of the metailizer, the infLation and/or deflation of the seal may be seLfreguieted, and may not necessarily depend on the internaL pressure of the metallizer untess specifically controlled to be, Preferably sa?d at least one valve s an external valve This conhgurator provdes the advantage of specifically controlling the internal pressure of the seal externally and in addition to means for controlling the pressure of the evaporation zone of the metallizer, o Preferably, said vacuum metakze compnses two valves wherein a first valve is specifically controllable to cause the inflation of said seal and wherein a second valve is specifically controlLable to cause the deflation of said seat. This configuration alLows the inflaflon and/or deflation of the seal to be specifically controlled in addition to any other valve directly controlling the internal pressure of the evaporation zone of the metallizer. it also allows the seal arrangement to be controlled at a pr&determined beneficial time in operative cycle of the vacuum metallzer.

Preferably, said first valve opens and closes a conduit extending between said seat and the atmosphere. This offers the advantage of providing a specific control for allowing atmospheric air into and inflating the seal when the vacuum metallizer is closed, Preferably, said second valve opens and doses a conduit extending between said evaporation zone and said seal. This offers the advantage of providing a specific control for w creating a vacuum in and deflating the seal prior to withdrawing the winding cart.

Preferably. said first valve is connectable to atmosphere and said second valve is connectable to a vacuum; whereby in a first mode of operation when said first valve is open and said second valve is closed, said seal is inflated; and in a second mode of operatIon when said first valve is closed and said second valve is open, said seal is deflated, Independent control of inflation and/or deflation of the seal allows the internal pressure of the seal to be specifically controlled.

In a second broad independent aspect, the invention provides a method of operating a vacuum metathzer equipped with an inflatable seth provided between a winding zone and an evaporation zone; said method comprising the steps ci providing at least one valve and sDecifically controlling said valve to deflate and/or inflate said seaL This method provides the advantage of operating an inflatable seal for use in a vacuum metallizer whose inflation and/or deflation is specifically controllable by at least one valve, in addition to any other valve directly controlling the internal pressure of the evaporation zone of the vacuum metallizer, This specific control also reduces damage of the seat and/or the surface against which it engages in use as when appropriately controlled friction between the seal and the surface is at Least rninimised if not entirely prevented.

Preferably, said method comprises the steps of providing a first valve; closing said vacuum metalUzer; creating a vacuum in said evaporation zone; and opening said first valve to allow atmospheric air into said seal in order to inFlate said seaL These steps provide the advantage of creating a seat between the winding zone and the evaporation zone of the

S

vacuum metallizer, As a vacuum is created in the evaporation zone, a first vaLve allows atmospheric air to inflate the seaL Preferably, said method comprises the step of closng sad first valve, prior to allowing atmospheric air into said evaporation zone, This avoids or at least substantially Omits the damage of the seal acting against the surface of the vacuum chamber.

Preferably, said method comprises the step.s of providing a second valve; and opening said second valve to create a vacuum inside said seal in order to deflate said seaL As a result to the seal deflates, ceasing contact with the internal wall of the evaporation zone in order to minimise damage on the wall of the evaporation section.

Preferably, said method comprises the steps of dosing said second valve to maintain a vacuum inside said seat; and subsequently opening said vacuum metatlizer to allow is atmospheric air into said evaporation zone. Deflation of the seal reduces the friction between the seal and the ntemal wall of the evaporation zone and therefore damage to either the seal or the internal watt that would otherwise occur.

BSfDecdptiQnf lures Figure 1 shows a prior art embodiment in crosssectionaL view.

Figure 2 shows a prior art embodiment in crosssectional view.

Rgure 3 shows a cross secton of an ernbothment of the mvert on where the seal s at least partially inflated, P Figure 4 shows a perspective view of the rail and the wall of the metallizer, so Figure 5 shows a perspective view of a portion of the exterior of the metatlizer where valves are mounted on an outer surface.

Figure 6 shows a side elevation of the external pipe work and valving of an embodiment of the invention.

Figure 7 shows a perspective view of seal located along the winding cart of the vacuum metallizer, Figure 2 shows a flow diagram of an embodiment of the method of operating a vacuum metaflizer.

This description focuses in figure 1 on the features of the prior art flexible seal which are in w common with the embodiment of the invention. As such the description of the prior art embodiment is deemed particularly relevant in the understanding of the operation of the embodiment of the invention.

Figure 1 shows a prior art embodiment of a flexible seal i for use in a vacuum metaltizer.

The seal comprises an inner section and an outer section, The seal allows sealing between a winding vacuum zone, generally referenced 5, and an evapora tion vacuum zone 4 of a vacuum metalbzer More parnculady, the seal part of a wncng cart which s brought.o abut against an internal wall of a vacuum chamber.

The niner secton s an nflatahle tube? and the oute' sectwn s a tshaped abutment member 3 of inherently flexible material for engagement with the internal wall of a vacuum chamber. Both inflatable tube? and Tshaped abutment member 3 are held in a rail 7. Rail 7 has an opening 8 which extends along its length through which Pshaped abutment member 3 protrudes. The inflation and deflation of the inflatable tube causes the Tshaped abutment member to protrude from and retract from the rail as part of the operation cycle of the metallizer. The flexible seal I is Located on the winding cart of the winding zone 4 of the vacuum metailizer and presses against internal waR 6 of the vacuum chamber (not shown) when the seal is inflated, A supporting surface 9 is provided as part of the winding cart (not shown). An L-sheped beam 10 engages the rear surface 11 of the raft Additional fasteners such as a bolt 12 and a nut 13 further secure the rail in position relative to the. winding cart, In use the vacuum chamber is split into two areas, the winding vacuum zone S and the evaporation zone 4. This allows for the lower pressure evaporation phase of the process to take place whilst the pressure level in the winding area is high. This can be withdrawn from walL 6 during the roll change over phase. The outer section 3 of the seaL 1 contacts the wall 6 of the metallizer in order to prevent gas molecules tram moving between the evaporation zone 4 and the winding zone 5.

However, as the winding cart is abutted against and/or withdrawn from the wall 6, the friction between the wall 6 and the seat 1 tends to progressively damage over a number of cycles of operation both the wall and the seal. In the prior art, this friction and resulting damage is caused by the inner inflated section 2 of the seal pressing the outer section 3 of to the seal 1 against the wall 6 at all times during repeated cycles of the coating process.

Figure 2 shows tube 2 in a relatively deflated configuration where the Tshaped member is drawn frito the cavity of rail 7.

ie Figure 3 shows an embodiment of the invention, Identical numerical references to those of figure 1 have been employed in figure 2 for identical or similar components, nstead of being immediately responsive to changes in the pressure in the vacuum chamber as in figure 1, the inflatable tube 2 of this embodiment is connected to a duct 13 which extends through the wall 14 of the metatlizer to an externally controlled valve 15 (see figures 4 and 5), A supporting surface 29 is provided as part of the winding cart (not shown). An Lshaped beam 3D engages the rear surface 31 of a rail 32. Additional fasteners such as bolt 33 and nut 34 further secure the rail 32 in position relative to the winding cart, The vacuum metalhzer urther compnses at east one valve 15 whch s specthcally controllable to deflate and/or inflate the seaL 1. In a preferred embodiment, the arrangement of at least one valve uses either atmospheric aft or internal vacuum pressure from within the evaporation zone of the metallizeL Figure 3 shows the seal at least partialLy inflated. f deflated it may take the form shown in Figure 2.

The inflation and/or deflation of the seal 1 are specifically controlled by at least one external ye Eve. C'

En a further preferred embodiment, the vacuum metalUzer comprises two valves: a first valve 16 spedficaily controllable to cause the inflation of the seal 1; arid a second valve 17 specifically controllable to cause the deflation of the seal 1. When valve 1$ which is provided between the seal 1 and the atmosphere, is open and the second valve is dosed, S the seal inflates when the surrounding atmosphere is at a relative vacuum level by comparison.

En use, the seal is inflated after the substrata material has been placed in the vacuum metatlizer and the metalUzer has been closed. A vacuum is then created in the vacuum to chamber of the metallizer, Valve 16 subsequently allows atmospheric air into the seal 1 in order to inflate and dose the seal against internal wall 6 of the vacuum chamber. Vacuum metailizing of the substrate material occurs once the seal is closed and gas cannot pass between the winding zone and the evaporation zone of the metallizer, Valve 16 is mourted on an CXLemndI surface of the metathzer and s placed m flud dynamc terms is between duct 13 and outlet 20 which is an open ended pipe to the surrounding atmosphere, Defiaton of the seals actuated by valve liwmch s mounted on Lhe outsde curlace of the metalUzer. Deflation of the seal reduces the friction against the wall 6 of the evaporation zone therefore reducing damage to either the wall or the seal allowing the winding cart to be withdrawn without damaging the wail.

A conduit 19 is provided between the valve 17 and the vacuum chamben whereby when valve 17 is open and the vacuum chamber is in a vacuum condition any air in the tube is also evacuated. Once coating of the substrate material has been carried out valve 16, allowing atmospheric air into the seal, is closed and valve 17 between the vacuum chamber and the seal is opened. The opening of vaLve 17 creates a vacuum within the seal which subsequently deflates the seal. A short time after a vacuum has been created in the seaL valve 17 is closed, This maintains the vacuum condition within the seal. The winding 3o section of the vacuum metallizer is then retracted in order for the coated substrate material to be exchanged with new uncoated substrate materiaL Once this has been done, the winding section is inserted back ready for the metallizing phase of the operation of the vacuum metallizer. Evacuation of air from the vacuum chamber is then initialised and the coating process is restarted.

FigureS shows a further embodiment with external valves 16 and 17. Valve 16 is provided between duct 13 and a conduit 20 leading to an area of atmospheric pressure within the metaUizer whilst valve 17 is provided between duct 13 and a conduit 21 leading to an area of vacuum such as the vacuum chamber. The valves may preferably be electronically controlled in order to open and close at specified points in the operation's cycle.

Figure 7 shows the winding cart 18 of the vacuum metaUizer incorporating a seal 1 for preventing gas from moving between the winding zone and the evaporating zone once the to winding cart and the evaporation chamber are in sealed engagement. The seal incorporates at Least the following sequence: a first portion 22 extending across the width of the metallizer, a bend 23, a second portion 24, a bend 25, a third portion 26, a bend 27 and a fourth portion 28.

is Prior to actuation of the vacuum metallizer, substrate coating material is loaded into the winding cart 18, Once the winding cart 18 has been inserted in the metallizer, a vacuum is created in the chamber and the seal is inflated until it abuts against wall 6. A metal, such as aluminium is then evaporated within the evaporation zone. The substrate material is then passed over the evapo-atoi zone where the evaporated metal condensec onto the substrate creating a coating layer.

Once coating of the substrate material has been completed, a vacuum is created in the seat in order to reduce the friction of the seal against the wall The vacuum metallizer is then opened in order to remove the coated substrate materiaL Figure 8 shows a flow diagram illustrating the method of operating a vacuum metallizer and specifically controlling inflation and/or deflation of a seal.

n a first step, uncoated substrate material is inserted into the winding zone of the vacuum metallfter. The winding zone is then inserted into the vacuum rnetallizer and the metaltizer is closed. Once the vacuum metallizer is closed, a vacuum is created within the metallizer, Air is evacuated using one or preferably more vacuum pumps. Once this has been done a first valve, Located between a seat on the winding zone and the atmosphere is opened to allow atmospheric air into the seaL This valve is additional to any other valve directly controlling the pressure of the evaporation zone of the mete Vizer. The difference in pressure between the air in the seal and the evaporation zone causes the seal? to Liflate, Inflation of the seaL 2 causes it to contact the wall of the evaporation chamber, preventing gas from moving between the evaporation zone and the winding cart9 and vice versa. Once the seal is inflated, evaporation of a coating substance such as aluminium can occur.

Once evaporation of a coating substance has commenced, the substrate material is then passed over the evaporation zone where the evaporated material condenses onto the substrate creating a coating Layer.

FoRowing coating of the substrate material, the first valve is closed, preventing further atmospheric aft from entering the seal. Subsequently a second valve, located between the evaporaton zone and the seat, s opened, creat ng a vacjuri vithn the seal. The second valve is also additional to any other valve directly controlling the pressure in the metallizer The vacuum created causes the seal to deflate and contact beeen the seal and the wall o the evaporation zone ceases. A short time after a vacuum has been created in the seal; the second valve is closed, maintaining the vacuum inside the seat. The vacuum metaltizer is subsequently opened and the winding zone, carrying the coated substrate material, is emoved Coated substrate mnatenat s tien exchanged wth new uncoated substrate material in order for the process to be repeated.