WO2007067031A1

WO2007067031A1 - System and method for coating products, and a product obtained with such a system and method

Info

Publication number: WO2007067031A1
Application number: PCT/NL2005/000845
Authority: WO
Inventors: Rutger Willem Frans Smits; Marinus Franciscus Johannes Evers
Original assignee: Otb Group B.V.
Priority date: 2005-12-07
Filing date: 2005-12-07
Publication date: 2007-06-14

Abstract

A system and method for coating relatively large products, such as for instance plastic car windows, wherein the system is provided with: - carriers for the products; - a transport rail along which the product carriers are movable; - a conditioned space bounded by space walls in which the transport rail extends and in which the product carriers are movable; - at least one lock via which a product carrier can be brought into the conditioned space and can be removed from the conditioned space, respectively; - at least one process chamber which is part of the conditioned space; - at least one plasma source of the cascade type, which plasma source is arranged for applying a coating to a product which is present in a said process chamber; and wherein the at least one product carrier has an adjustable length.

Description

Title: System and method for coating products, and a product obtained with such a system and method

The invention relates to a system for coating relatively large products, such as for instance car windows, wherein the system is provided with:

- carriers for the products;

- a transport rail along which the product carriers are movable;

- a conditioned space bounded by space walls in which the transport rail extends and in which the product carriers are movable;

- at least one lock via which a product carrier can be brought into the conditioned space and can be removed from the conditioned space, respectively;

- at least one process chamber which is part of the conditioned space;

- at least one deposition source, which deposition source is arranged for applying a coating to a product which is in a said process chamber.

Such a system is for instance described in European patent applications EP-A-I 365 040 and WO 05/017228. The contents of the two publications are considered to be inserted herein by reference. In particular when very large products need to be provided with a coating, which coating is to be applied with the aid of a deposition source which is continuously switched on, such as for instance a PECVD cascade source, the product carrier, the transport rail and the space walls, as well as the portions of the conditioned space which bound the process chamber will become

contaminated by the coating material.

The object of the present invention is to provide a system with an optimum capacity, i.e. a system which can produce an optimum number of products per time unit, while, in addition, the system operatively uses up a minimum amount of coating material and is operatively minimally subject to contamination.

This object is achieved with the aid of a system of the type described in the opening paragraph, while the system is provided with product carriers with mutually different length dimensions viewed in transport direction of the system, while a control is provided which is arranged for bringing the product carriers from the lock into the conditioned space such that minimal openings are present between the successive products passing the process chambers.

Because the product carriers with different length dimensions are available in the system, when a product or a collection of products is placed on a product carrier, in the selection of the product carrier, the length dimension of the product carrier can be matched as well as possible to the length dimension of the product or the collection of products which is to be placed on the carrier. Because the system is provided with a control which is arranged for bringing the product carriers from the lock into the conditioned space such that minimal openings are present between the successive products passing the process chambers, per linear meter of path, an optimum amount of products can be accommodated. In addition, due to the absence of the openings, it is realized that virtually all coating material actually ends up on the products and not on the space walls. This is because there is virtually always a product opposite the deposition source, such as for instance the plasma plumes formed by the PECVD cascade sources.

According to an embodiment of the system, a robot is provided for automatically placing a product or a collection of products on a product carrier, while the control of the system is arranged for selecting a product carrier with a length dimension which matches the length dimension of the product to be placed or the collection of products to be placed.

Thus, an optimum capacity with a minimum internal contamination of the system is realized automatically. According to a further elaboration of the invention, the at least one product carrier may have an adjustable length.

Because the product carrier has an adjustable length, its length can be matched to the length of the product to be coated or the collection of products to be coated which is to be transported by the product carrier. This provides the system with very much flexibility because the dimensions of the product carriers can always be adjusted to the dimensions of a product to be processed.

According to a further elaboration, a said product carrier is provided with a base including guides for cooperation with the transport rail, the base comprising a first base part and a second base part, the second base part being movable relative to the first base part. Because the base consists of two parts which are movable relative to each other, the length of the base can be varied. Thus, the length of the base and, accordingly, of the product carrier is adjustable.

In an embodiment of the system, with the base, a suspension element is connected by which a product or a collection of products can be connected with the product carrier.

Here, the suspension element may be provided with a first upright which is connected with the first base part, a second upright which is connected with the second base part and a girder which is connected with these uprights near the ends of the uprights remote from the base and which is of length-adjustable design.

Because the girder is of length-adjustable design, its length will change automatical^ with the change of the relative position of the first and the second base part. The girder may, for instance, have a telescopic design.

The invention further provides a method for coating relatively large products, such as for instance plastic car windows, where the length is determined of the product or the collection of products which is to be placed on a product carrier, while a product carrier is selected whose length dimension viewed in transport direction substantially matches the determined product length, while the product or the collection of products to be coated is placed on the product carrier and the product carrier is brought from the lock into the conditioned space such that minimal openings are present between the successive products passing the process chambers, while the products are subjected to at least a coating process in the conditioned space.

Because the lengths of the product carriers are matched to the lengths of the products to be coated or the collection of products to be coated which are to be transported per product carrier, there are no openings or only openings with minimal dimensions between the successive products and therefore a maximum production capacity is realized while the contamination of the interior of the conditioned space is minimized.

The invention further relates to a coated product manufactured with the method according to the invention utilizing a system according to the invention.

According to a further elaboration, the coated product may be a coated plastic car window. Here, the coating may, for instance, be a silicon dioxide coating.

The invention will hereinafter be explained in more detail on the basis of a number of exemplary embodiments, with reference to the drawing, in which:

Fig. 1 shows a perspective view of an exemplary embodiment of the system;

Fig. 2 shows a vertical cross-sectional view of a portion of the process chamber with a product carrier present therein;

Fig. 3 shows a side elevational view of a frame with a number of products connected therewith; Fig. 4 shows a perspective view of a product carrier with variable length;

Fig. 5 shows a series of four product carriers positioned one after the other with products which are too small; and

Fig. 6 shows a series of five product carriers positioned one after the other with dimensions which are matched to those of the products.

Fig. 1 shows a perspective view of an exemplary embodiment of a system for coating products, in particular relatively large products, such as for instance plastic car windows. In Fig. 1, the path designated by reference numeral 1 forms a loading path 1. The path designated by reference numeral 2 forms a processing path 2 extending in a conditioned space. The path with reference numeral 3 is a service path. The path with reference numeral 4 is an unloading path 4. The path with reference numeral 5 is a feedback path 5.

In the whole system, a transport path extends with the aid of which product carriers 6 and/or screen carriers 7 can be transported through the system. For a description of a product carrier 6 and the transport path, reference is made to above-mentioned European patent application

EP-A-I 365 040 whose contents are considered to be inserted herein by reference.

In the loading path 1, product carriers 6 can be loaded with

products P which are to be provided with a coating in the processing path 2. The products may, for instance, be plastic car windows which are to be provided with a silicon dioxide coating. From the loading path 1, the carriers with the products P present thereon are transported to the processing path 2.

The processing path 2 is surrounded by the space walls 19 bounding a conditioned space. The processing path 2 is, for instance, provided with a first loading lock 8. This is followed by a heating station 11, a deposition station 12 and a discharge lock 15. To the conditioned space, various pumps

are connected to maintain the desired pressure in the conditioned space. In general, this will be a low pressure, which is required for the processing process, more in particular the deposition process with the aid of a PECVD cascade source.

To the exit of the processing path 2, a service path 3 connects. In the service path 3, contaminated screens 17 can be removed from the screen carriers 7 and be replaced by cleaned screens 17. Cleaning the screens 17 on site is also possible. Optionally, in the service path 3, product carriers 6 and/or the screen carriers 7 may be subjected to a service or a cleaning.

To the exit of the processing path 2, an unloading path 4 connects as well. In the unloading path 4, product carriers with products P provided with a coating are transported and the products P are removed from the product carriers 6. To the end of the unloading path 4, a feedback path 5 connects which feeds the empty product carriers 6 back to the loading path 1. For instance in the feedback path 5, the product carriers 6 may be adjusted for length. Such an adjustment may also take place in the service path 3.

It will be clear that many variants of the system shown are possible and that the system is only shown by way of example. The different processing steps in the processing path 2 can be varied infinitely and the embodiments and the courses of the different paths 1, 2, 3, 4, 5 can also be varied greatly.

The cross-sectional view shown in Fig. 2 of a portion of a process chamber 12 clearly shows the space walls 19 bounding the conditioned space 20. In the conditioned space 20, two transport rails 21 extend. Over these transport rails 21, a product carrier 6 and/or a screen carrier 7 is movable. To this end, the carrier is provided with permanent magnets 22 and, on the space walls 19, a series of coils 23 is disposed which can be excited such that the carriers 6 and/or 7 are movable along the rails 21 independently from each other. In the exemplary embodiment of Fig. 2, the carrier 6 is both product carrier and screen carrier. The product P is received in a frame 24 connected with the carrier 6 via a frame interface 25. In the present exemplary embodiment, a screen 17 can also be suspended from the frame interface 25. The screen 17 protects the space walls 19 and the transport rails 21 against contamination with coating material during the coating process.

As already indicated in Fig. 2, the products P may be received in a frame 24. The frame 24 then contains a collection of products. Fig. 3 shows such a frame 24 which may be suspended from a product carrier 6 with the aid of a frame interface 25. In the case of plastic car windows P, the frame 24, the frame interface 25 and the products P may all be designed as a single injection-molded piece, while the connections between the frame 24 and the products P are formed by breakable plastic welded joints.

The system is provided with product carriers 6 with mutually different length dimensions viewed in the transport direction. Further, the sj'stem is provided with a control (not shown) which is arranged for bringing the product carriers from the lock 8 into the conditioned space 20 such that minimal openings are present between the successive products P passing the process chambers 11, 12. Optionally, loading the product carriers 6 can be carried out with a robot. Here, it is preferred that the control of the system is arranged for selecting a product carrier with a length dimension which matches the length dimension of the product to be placed.

Fig. 4 shows a perspective view of a product carrier 6 with an adjustable length. The product carrier 6 is mobile over transport rails 21. On the product carrier 6, there is a suspension element 26 from which a frame 24 with products P can be suspended. The product carrier 6 is further provided with a base 27 which is provided with guides 28, in the present exemplary embodiment designed as guide wheels, with the aid of which the base 27 is mobile over the transport rails 21. On the base 27, a number of permanent magnets 22 are provided which can cooperate with coils 23 positioned outside the conditioned space 20 (in the manner as shown in Fig. 3). What is special about the product carrier 6 from Fig. 5 is that its length is adjustable. This allows both the long and short products P to be fed through the system in an efficient manner. For the product carrier 6 from Fig. 4, this adjustable length is realized in that the base 27 is provided with a first base part 27a and a second base part 27b which is movable relative to the first base part 27b. Optionally, the second base part 27b may also be provided with guide wheels 28. Thus, both an upstream end and a

downstream end of the product carrier 6 are guided through the transport rails 21. The suspension element 26 on the product carrier 6 has a first upright 26a on the first base part 27a and a second upright 26b on the second base part 27b. A girder 26c of the suspension element 26 has a telescopic design. It will be clear that other designs for varying the length of the product carrier 6 are also possible. Instead of near the bottom wall of the conditioned space 20, the transport rail 21 may also extend near a side wall or top wall of the conditioned space 20. When the transport rail 21 is located near a side wall or top wall, the product carrier 6 will have an interface with a different design for attaching the product P to the product carrier.

Fig. 5 shows a situation which arises if the product carriers 6 have fixed lengths and when those lengths are not matched to the lengths of the products P placed therein. Firstly, fewer products can be processed per linear meter, which leads to capacity loss of the system. Secondly, the large openings O between the successive products result in more contamination by coating material of the interior of the system. This is because not all coating material deposits on the products but a part thereof will deposit on the space walls 19 when there is no product P opposite the plasma plumes which are formed by the continuously working PECVD cascade sources.

Fig. 6 shows the situation which arises if the product carriers 6 have lengths which do match the lengths of the products placed therein. In Fig. 6, this is realized by using product carriers with adjustable lengths. However, it is also possible that the system is provided with product carriers with mutually different lengths and that a matching product carrier is selected for a product.

In Fig. 6, it can clearly be seen that more products are processed per linear meter, which is favorable to the capacity of the system. In addition, there are hardly any openings between the successive products and therefore there is always a product opposite the plasma plumes which are formed by the continuously working deposition sources, which are

preferably designed as PECVX) cascade sources.

The PECVD cascade sources, of which there may sometimes be up to twelve per product side per process chamber with large products, provide a stable plasma which can be synchronized optimally. The great advantage of PECVD cascade sources is that a targeted plasma can be created therewith, with the aid of which a high deposition rate can be realized. Thus, in a relatively short time, the desired layer thickness is realized. An example of a suitable PECVT) cascade source is described in the international patent application WO 04/105450 whose contents are considered to be inserted herein by reference.

In use of the above-described system, firstly the length is determined of the products or the collection of products which is to be placed on a product carrier 6. Then, a product carrier is selected whose length

substantially matches the length of the product or the collection of products P to be placed on the product carrier 6. After that, the product carrier 6 is brought from the lock 8 into the conditioned space 20 such that minimal openings O are present between the successive products passing the process chambers 11, 12. In the conditioned space 20, the products are subjected to at least a coating process. Because there are no or only minimal openings O between the successive products, the capacity of the system is optimal and the internal contamination of the conditioned space will be minimized. The coating process may, for instance, comprise the application of a silicon dioxide layer to plastic car windows. However, it will be clear that other types of coating may also be applied with the aid of the PECVD cascade sources. Other types of products may also be coated with the aid of the system and the method according to the invention. Options to be considered here are coating car windows from glass in order to eliminate reflection from them or coating other parts in order to provide them with special properties.

The invention is not limited to the exemplary embodiment described, but various modifications are possible within the framework of the invention as defined by the claims.

Claims

1. A system for coating relatively large products (P), such as for instance plastic car windows, wherein the system is provided with:

- carriers (6) for the products (P);

- a transport rail (21) along which the product carriers (6) are movable; - a conditioned space (20) bounded by space walls (19) in which the transport rail (21) extends and in which the product carriers (6) are movable;

- at least one lock (8, 15) via which a product carrier (6) can be brought into the conditioned space (20) and can be removed from the conditioned space (20), respectively;

- at least one process chamber (11, 12) which is part of the conditioned space (20);

- at least one deposition source (33), which deposition source (33) is arranged for applying a coating to a product (P) present in a said process chamber (12); wherein the system is provided with product carriers (6) with mutually different length dimensions viewed in transport direction of the system, wherein a control is provided which is arranged for bringing the product carriers from the lock (8) into the conditioned space such that minimal openings are present between the successive products passing the process chambers (11, 12).

2. A system according to claim 1, provided with a robot for

automatically placing a product or a collection of products on a product carrier (6), wherein the control of the system is arranged for selecting a product carrier (6) with a length dimension which matches the length dimension of the product to be placed.

3. A system according to claim 1 or 2, wherein the product carriers have adjustable lengths.

4. A S3^rstem according to claim 3, wherein a said product carrier is provided with a base (27) with guides (28) for cooperation with the transport rail (21), wherein the base (27) comprises a first base part (27a) and a second base part (27b), wherein the second base part (27b) is movable relative to the first base part (27a).

5. A system according to claim 3 or 4, wherein, with the base (27), a suspension element (26) is connected by which a product (P) or a collection of products (P) can be connected with the product carrier.

6. A system according to claims 4 and 5, wherein the suspension element (26) is provided with a first upright (26a) which is connected with the first base part (27a), a second upright (26b) which is connected with the second base part (27b), and a girder (26c) which is connected with these uprights near the ends of the uprights (26a, 26b) remote from the base and which is of length- adjustable design.

7. A system according to any one of the preceding claims, wherein the at least one deposition source is a PECVD cascade source, which is preferably switched on continuously.

8. A method for coating relatively large products, such as for instance plastic car windows, wherein a system according to any one of claims 1-7 is provided, wherein the length is determined of the product or the collection of products which is to be placed on a product carrier (6), wherein a product carrier (6) is selected whose length dimension viewed in transport direction substantially matches the determined product length, wherein the product or the collection of products to be coated is placed on the product carrier and the product carrier (6) is brought from the lock (8) into the conditioned space (20) such that minimal openings are present between the successive products passing the process chambers (11, 12), wherein the products are subjected to at least a coating process in the conditioned space (20).

9. A coated product manufactured with the method according claim 8 utilizing a system according to any one of claims 1-7.

10. A coated product according to claim 9, wherein the coated product is a car window.