DE19715779A1 - Bonding equipment for joining two information=carrying discs, especially digital versatile discs - Google Patents

Abstract

A process for bonding together two plastic discs, especially for manufacture of digital versatile discs (DVD), involves applying an adhesive (14) onto the surface (19) of one or both discs (11, 12). holding one disc above the other in a vacuum chamber and bringing together before releasing the vacuum. Process equipment includes a vacuum chamber with a base supporting one disc (12) and a cover holding the other disc (11).

Description

The present invention relates to a method and a device for gluing two preferably disc-shaped plastic substrates for example for the production of optical data carriers in the form of DVDs, according to The preamble of claim 1 and that of claim 11.

Optical recording media in the form of conventional ones Compact discs, so-called CDs, have an outer diameter of 120 mm, a center hole with a diameter of 15 mm and a slice thickness of 1.2 mm. In the new generation of optical recording media, the so-called DVD (digital Versatile discs) are two disc parts of 0.6 mm each brought together and glued so that the result is a optical recording medium with the conventional dimensions  a compact disc is obtained. The Disc elements either by a carrier disc element (Carrier) and a blank disc element (Blanc) or two Carrier disc elements are brought together.

For gluing them from a suitable plastic manufactured disc elements or substrates is a Solvent-free hot melt adhesive used, its adhesive power is activated by exposure to heat.

However, the adhesives used so far have some Disadvantages. On the one hand, those with the for Necessary aluminum layer coated with laser reflection Disc elements additionally on the one with aluminum coated side are coated with a UV protective lacquer, a partial, unwanted oxidation and aging of the Avoid aluminum layer as with those currently used Glue air pockets and chemical reactions between Glue and aluminum as well as possibly non-glued zones, cannot be avoided. On the other hand, they own Glue of no optical quality. A good optical one However, quality is included with some types of DVDs such as the DVD9 is essential because of these types of DVDs one for reading the existing ones on the disk Information relevant laser beam through the adhesive layer reads through existing information. Furthermore, the Processing of the previously used glue due to the high  Consistency or toughness of the adhesive with considerable effort connected.

The object of the present invention is therefore a Method and device for gluing two preferably disk-shaped plastic substrates for example. Manufacture of optical recording media in the form of DVDs to create with the or the air pockets and / or non-bonded zones between the two plastic substrates are avoided.

In addition, the additional necessary so far Protective coating of the surfaces coated with aluminum the disc elements are omitted, since in this method the Glue the protective lacquer and the protective lacquer at the same time represents the adhesive at the same time, i.e. both equally Purposes fulfilled and thus a previously necessary Process step (the separate protective coating before Gluing the disc elements) should be omitted. Furthermore, gluing with a good optical Adhesive layer are made possible, so that too Making DVDs allows one for that Reading the information relevant laser beam through can read the adhesive layer through it, as is the case with DVD9 is necessary.  

To solve this problem, one method or Device for gluing two plastic substrates of the type mentioned in claims 1 and 11 respectively Features provided.

The measures according to the invention make it possible to two plastic substrates so adhesive to each other bring that no air pockets and / or there are unglued zones and that the two Plastic substrates keep their flat shape even after bonding maintained.

To apply a sufficiently thin and homogeneous adhesive The characteristics are to achieve on the plastic substrates provided according to claim 2.

According to the features of claim 3, there is an optimal Prerequisite for the adhesive bonding of the two Plastic substrates. It is useful to have the characteristics to provide according to claim 4. To get the physical Controlled and quick start of the adhesion process, the features according to claim 5 are preferably provided. A further optimization of the adhesion process is then realized if the features according to claim 6 are used.  

For an optimal alignment of the fixed to each other adhesive plastic substrates are used according to the characteristics Claim 7.

Preferably, according to the feature of claim 8 used as an adhesive, a UV-curing adhesive varnish, the Drying and curing according to the characteristics of the Claim 9 is accelerated. But it is also possible, according to the feature of claim 10 as an adhesive a two- Use component glue.

Further advantageous refinements of the device for Two-dimensional bonding of two plastic substrates results from the features of the further subclaims.

Further details of the invention are as follows Description can be found in which the invention using the in the drawing shown embodiment closer is described and explained. Show it:

Fig. 1 to 8 of two individual process steps for the flat disc-shaped bonding plastic substrates means on the basis of two shown in these figures in a schematic and longitudinal section of units for the surface bonding of disk-shaped plastic substrates.

For the method for the surface bonding of two disc-like plastic substrate in the form of the same dimensions having disc or disc elements an optical recording medium 11 and 12, for example. A DVD (Digital Versatile Disc) 15, Figs. 1 and 2, a first unit or station 13 , in which both disc elements 11 and 12 are provided with an adhesive 14 .

This first station 13 has a cup-shaped receptacle 16 , which is provided with a retracted upper edge 17 . A rotatably driven holder 18 is provided centrally within the pot-shaped receptacle 16 , onto which the respective disk element 11 , 12 with the surface 19 to be coated with adhesive 14 can be placed upward. The disc element 11 , 12 is centered by a holder projection 21 which penetrates the central hole 20 of the disc element 11 , 12 . By means of a metering arm 23 , viscous adhesive 14 in the form of a bead 24 is applied annularly to the inner region of the disk element 11 , 12 adjacent to the center hole 22 , the holder 18 with the disk element 11 , 12 at a speed of approximately 50 to 100 rpm is driven in rotation. If the adhesive bead 24 is applied, the rotational speed of the holder 18 and thus the disk element 11 or 12 is increased to approximately 2500 to 5000 rpm, so that the adhesive 14 is thrown off the bead shape 24 over the entire surface 19 and is evenly distributed . This results in a uniformly distributed, thin adhesive layer 25 . Possibly. Any remaining or thrown off adhesive 14 is collected in the pot-shaped receptacle 16 in a manner not shown and returned.

A UV-curable adhesive or adhesive varnish is preferably used as the adhesive 14 . The two plastic substrates are, for example, polycarbonate disks 11 , 12 which have an outer diameter of 120 mm, a center hole 22 with a diameter of 15 mm and each have a thickness of 0.6 mm. The disc elements 11 , 12 are formed either by a carrier disc and a blank disc (Blanc) for a single-sided DVD or by two recording discs for a double-sided DVD.

After this application of adhesive, the two disk elements 11 and 12 are moved one after the other or, if the first station 13 is designed twice, in a manner not shown at the same time by means of a handling device into a second station 30 designed as a vacuum device according to FIG. 3. The vacuum device 30 has a base part 31 and a cover part 32 which can be connected to one another in a gas-tight manner to form a vacuum chamber 36 . The base part 31 has a base plate 33 with an annular edge 34 which is provided with a radial opening 37 at at least one circumferential point. The base plate 33 is provided with a cylindrical, centrically stepped shoulder, on the base plate-side and larger-diameter part 38 of the relevant disc element 11 , 12 can be placed and the smaller-diameter part 39 engages through the central hole 22 of the disc element 11 , 12 . The bottom part 31 is also provided with a centering device 40 , which has a plurality of flat radial clamping / centering slides 41 distributed over the circumference, which are provided in the area between the two extension parts 38 , 39 , and a clamping / centering bolt 42 which has the bottom plate 33 and axially penetrates the attachment part 38 in a central position and can act on the radially expandable slide 41 by an axial movement.

The cover part 32 also has a centering device 50 corresponding to the centering device 40 with a plurality of flat clamping / centering slides 51 and a clamping / centering bolt 52 , which are provided in the region of a cylindrical, central, stepped extension 48 , 49 of a cover plate 53 . In the cover plate 53 or the attachment part 48 , the attachment part 49 is surrounded by weights 47 which are arranged on the circumference and which are connected to axial guide pins 46 which are guided axially displaceably in the cover plate 53 .

Referring to FIG. 3, the disc member 11 is placed on the cap part 32 (arrow A) and the disk member 12 to the bottom part 31 (arrow B), the smaller-diameter Vorzentrieransatzteil 39 and 49, the center hole 22 of the disk element 11 and passes through 12. In this case, the disk member 12 is located loosely on the floor part 31, while the disc member 11 is held in pressed-in direction of the arrow A centering / clamping bolt 52 on the lid part 32 is clamped. The two disk elements 11 and 12 are arranged in such a way that the respective surface 19 provided with the adhesive layer 25 points upwards.

According to arrow D in FIG. 3, the cover part 32 with the disc element 11 is brought onto the bottom part 31 of the vacuum device 30 , so that the vacuum chamber 36 is hermetically sealed. Referring to FIGS. 4 and 5 is then aspirated 37 air across the at least one opening and evacuating the vacuum chamber 36. In this state, the adhesive layers 25 on both disc elements 11 and 12 are still moist or wet.

Is the vacuum chamber brought to a predetermined vacuum pressure 36, the clamping / centering device according to Fig. 6 45 dissolved in the cover part 32 (arrow E), so that the upper disc element 11 falls down on the lower disc member 12, wherein the falling movement by the likewise downward weights 47 are supported. The upper disk element 11 with its center hole 22 comes out of the pre-centering attachment part 39 of the cover part 32 via the pre-centering projection 53 of the bottom part 31 . The two adhesive layers 25 come together wet on wet.

Referring to FIG. 7, the vacuum chamber 36 is then vented again, thus occurring in the chamber 36 atmospheric pressure causes even possibly non-contact areas between the adhesive 14 and the two elements 11 and 12 are pressed onto one another. Any contact-free zones or inclusions that are still present are thereby eliminated.

Referring to FIG. 8 of the vacuum chamber after venting 36, the centering / clamping device 40 in the base part 31 is activated (arrow F) so that the axially moved centering / clamping bolt 42, the centering slide 41 is moved so that the center holes 22 of the two disc elements 11 and 12 be brought into exact alignment with each other.

In a manner not shown, after opening the vacuum device 30, the DVD 15 , which is adhesively produced from the two disc elements 11 and 12, is removed from the vacuum device 30 and fed to a UV drying device, in which the UV adhesive 14 is cured, if necessary, with rotation.

If a UV-curable adhesive 14 is also assumed in the method described above, it goes without saying that a two-component adhesive can be used instead of this adhesive.

It is also possible to use the upper disc element by spring force or the like on the lower disc element in the Bring vacuum chamber.

Claims (15)

1. A process for the two-dimensional bonding of two preferably disc-shaped plastic substrates for, for example, producing optical recording media in the form of DVDs, in which an adhesive is applied uniformly and thinly over substantially the entire surface of one or both plastic substrates, characterized in that after the application of the adhesive, the two plastic substrates are placed in a vacuum chamber at a distance from one another, that the two plastic substrates are then placed one on top of the other using a vacuum, and that the vacuum chamber is then ventilated. 2. The method according to claim 1, characterized in that the adhesive on both plastic substrates centrically applied in a ring and over the Substrate surface is thrown off. 3. The method according to claim 1 or 2, characterized in that the bottom of a plastic substrate and that other plastic substrate in the lid side Vacuum chamber is inserted, the other Plastic substrate hanging on the cover side becomes.   4. The method according to claims 1 and 3, characterized characterized in that with or after applying Vacuum in the vacuum chamber the hanging on the cover side Plastic substrate is released and dropped. 5. The method according to claim 4, characterized in that the lid-side hanging plastic substrate weighted on the lower plastic substrate brought. 6. Method according to at least one of the preceding Claims, characterized in that the two on applied to the relevant substrate surfaces Adhesive layers each still wet brought together. 7. Method according to at least one of the preceding Claims, characterized in that the two superimposed plastic substrates after the Vent the vacuum chamber to be centered to each other. 8. The method according to at least one of claims 1 to 7, characterized in that as an adhesive UV-curing adhesive varnish is used. 9. The method according to claims 1 and 8, characterized characterized that the two are adhesive  superimposed plastic substrates in one Brought UV drying station and dried with rotation will. 10. The method according to at least one of claims 1 to 7, characterized in that adhesive is a two- Component glue is used. 11. Device for the two-dimensional bonding of two preferably disc-shaped plastic substrates ( 11 , 12 ), for example for producing optical recording media in the form of DVDs ( 10 ), with an adhesive ( 14 ) over one or both of the plastic substrates ( 11 , 12 ) entire surface ( 19 ) is applied evenly and thinly, characterized in that a vacuum chamber ( 36 ) is provided which has a base-side support ( 31 ) for one plastic substrate ( 12 ) and a cover-side holder ( 32 ) for the other plastic substrate ( 11 ) having. 12. The device according to claim 11, characterized in that the bottom and / or lid-side bracket ( 31 , 32 ) has a clamping / centering device ( 40 , 50 ) for a center hole ( 22 ) of the plastic substrate ( 11 , 12 ). 13. The device according to claim 11 or 12, characterized in that the cover-side holder ( 32 ) has the plastic substrate ( 11 , 12 ) acting force and / or weight elements ( 47 ). 14. Device according to at least one of claims 11 to 13, characterized in that it comprises a rotary device ( 18 ) for throwing off a bead of adhesive ( 24 ) applied to the plastic substrate ( 11 , 12 ) over the substrate surface ( 19 ). 15. Device according to at least one of claims 11 to 14, characterized in that it is a Has UV drying device.