DE3511396A1 - Prepressing device for laminate assemblies bent in a complex manner and process for prepressing bent laminate assemblies - Google Patents

Abstract

For the temporary pressing of a bent laminate assembly with a thermoplastic film as interlayer material, for example plasticised polyvinyl butyral, which is arranged between a pair of glass panes or transparent plastic sheets which are usually used instead of glass, a first flexible cover of air-impermeable material with a centre part, which has suction channels and bears the laminate assembly in the centre part, and a second flexible cover are used. A suction line is connected to the centre part of the first flexible cover. The covers lie firmly on one another at a distance from the outer edge of the laminate assembly and form a vacuum chamber for the laminate assembly from which vacuum chamber the air, including the air between the layers of the laminate assembly, is removed, at first at room temperature, by applying a subatmospheric pressure for 1 to 3 minutes. Subsequently the temperature is raised to 121 DEG C for a time sufficient to seal at least the edge regions of the laminate assembly together after liquid and gas have first been removed from the laminate, atmospheric pressure acting on the outer surfaces of the flexible covers. A laminate assembly results which is clear in the edge region. The covers can be easily separated from one another in order to remove the prepressed laminate assembly from them and are immediately ready to receive the next assembly. The flexibility of the covers permits adaptation to a wide variety of patterns ... <??>Original abstract incomplete.

Description

3511336

The invention is directed to a method and an apparatus for producing laminated safety glass, especially with complicated curved shapes. Such safety glass usually contains two or more sheets of glass or plastic sheets made of a hard, transparent material, which serves as a replacement for one or more panes of glass, which by means of a layer of thermoplastic Material are glued together. The preferred thermoplastic material is plasticized Polyvinyl butyral. Laminated safety glass is widely used when a Resistance to splintering is important, for example as automobile windshields.

The invention is particularly suitable for the preliminary pressing, also called pre-pressing, of laminate packages, the subsequent final and complete lamination at elevated temperature and subjected to elevated pressure in an autoclave.

Various methods and devices for making laminated safety glass have been developed. The most common way of making laminated windshields in practice consists of two steps. In the first step, a laminate package is made from layers in the desired Order for the lamination are laid one on top of the other and this laminate package becomes a preliminary or subjected to temporary pressing to make all liquid and gases and other vaporizable Remove any fabric between the adjacent layers and close the edges of the laminate at the edge seal so that no liquid can penetrate the laminate during subsequent steps.

In the subsequent final step, the pre-pressed laminate package is sufficiently elevated in temperature and elevated Subjected to pressure in order to achieve a complete and full-surface bond of the layers to one another produce.

Various methods have been developed for the preliminary compression of glass plastic laminate packages. In one of these methods, the laminate package is sent through a nip, whereby a pressure is applied to the Major surfaces of the moving laminate package is exerted. The laminate packages are heated to the Plastic intermediate layer to soften somewhat, so that when the air is pressed out of the surfaces lying on top of one another as it passes through the rollers Edges of the laminate package are sealed. However, the use of nips for prepressing is Can only be used for pre-pressing flat laminates and slightly curved laminate shapes. Laminate packages with complicated sharp bends break as they pass through the nip. The break occurs because it is extremely difficult to keep the pressure at grain

Plicated bending forms evenly in the preliminary Distribute presses.

Laminated windshields have also been made by placing laminate packages in flexible bags enclosed and evacuated to outgas the interlayers. Then the bag and its contents heated to temperatures sufficient to seal the edges of the laminate package. the However, the use of closed bags is not always possible because such bags are complex in shape Can't customize laminate packages. As a result, fragments often occur within the bag. aside from that it is difficult to completely evacuate the closed bag. Break can also only then can be detected when the treatment is finished and the laminate package is removed from the pouch. A Another method of preliminary pressing of laminate packages uses a vacuum chamber around the outer edge made of a flexible open-ended ring with wings, that extend from a base. The wings are attached to the major outer surfaces of the Laminate package applied and the base has a distance from the package to a surrounding the laminate package To form vacuum chamber. This process is extremely laborious and is suitable for mass production not suitable. In practice, this mode of operation was only used if only slightly Numbers of certain shapes are required, for example for the aftermarket. The rings are Although more suitable for complex forms of laminate packages than rollers and closed ones Bag, however, it is necessary to make a corresponding ring for each new size and shape. This requires maintaining a large inventory of rings of different sizes and Shape, each overlaid with the different circumferential lines of the windshields to be manufactured

tune in.

It was therefore tried to carry out the pre-pressing and the final pressing in the same autoclave. Alternatively, an attempt was also made to convert the device used for pre-pressing to the final one Use lamination in the second step. In such a way of working, the speed is extraordinary low and not suitable for mass production because, firstly, the number of laminate packages, which can be arranged in an autoclave of a predetermined size is limited, in particular when each of the laminate packages to be laminated within the autoclave still has the device for the preliminary Must have pressing and second is the heat transfer from the atmosphere of the autoclave each laminate package and between the laminate packages due to the additional heat capacity of the pre-pressing devices much slower, especially the response to temperature changes in the final Laminating in an autoclave. Because the pre-compression device inside the autoclave throughout Lamination is arranged, it is impossible to make repairs to the pre-press device, unless this is taken out of the autoclave. In practice it has been found that it is much more effective to first pre-press each laminate package and out of the pre-press device before placing the prepressed laminates in the autoclave for final lamination will. Each of the pretreated laminates can then be exposed directly to the atmosphere in the autoclave. Removal from the pre-pressing device enables a larger number of pre-pressed laminate packages to be placed in an autoclave. The handling of whole groups of prepressed laminates enables a

Particularly effective work, because all laminates change evenly with the temperature in the autoclave change.

U.S. Patent No. 2,673,822 describes a preliminary pressing apparatus which includes a frame member having a shape corresponding to the outline of the laminate package to be preliminarily pressed. Each Different patterns of a laminate package require a differently designed pre-pressing device. It is therefore necessary to stock a large number of pre-compression devices of this type.

U.S. Patent No. 3,769,133 uses two flexible films are described that form an envelope or bag around the bent laminate package that is pre-pressed should be trained. The two sheets of flexible material must be used to complete the envelope be tightly sealed along the outer perimeter to allow the formation of an evacuable chamber, so that the suction of air and other gases from the envelope can take place in periods of time that match the cycle times for heating, evacuating and applying pressure in the autoclave.

Sealing the laminate packages in an envelope not only allows preliminary pressing, it enables also to leave the package in place during the final lamination step and this wrapper can too serve as packaging for shipment to installation in automobiles. The requirement of the full Sealing the foils around the laminate package prevents repeated use of the envelope, for example for a second lamination. Preliminary pressing is known from US Patent No. 3,852,136, in which the laminate package is introduced into a vacuum chamber encompassing the circumference with a first negative pressure

will and. the laminate package with this edge vacuum chamber is introduced into a larger vacuum chamber at a different negative pressure. Edge vacuum chambers of different Size and outer circumference shapes are for different Patterns required and require high levels Costs. In addition, the attachment of the edge vacuum chambers to each individual laminate package is time-consuming and labor intensive. In addition, the heat transfer in a vacuum chamber is due to the lack of a transfer medium bad.

U.S. Patent No. 3,917,503 uses mismatched folded bags, which are automatically opened, described to curved laminate packages to press temporarily. The access opening of the bag is closed by a flat flap one wall of the flexible bag which is wrapped over the other wall of the bag. As the bag three Has tightly closed sides, there are difficulties in making the bag intricately shaped laminate packages adapt. The lack of adaptation results in broken glass and poor degassing of the laminate package. From U.S. Patent 4,152,188 it is known to apply a flexible membrane to the outer surface of a layer that is connected to the glass should be laminated, whereby first pressure is applied in the middle and this is then gradually spreads outward from the center to prevent the formation of air bubbles inside the package to be laminated to avoid. This mode of operation is limited to individual laminate packages that are handled manually can, however, is not suitable for industrial mass production.

U.S. Patent No. 4,180,426 describes the bent laminate package for preliminary pressing into a

Include fabric or flannel or other porous nonwovens that completely surround it and the Wrapped laminate package between upper and lower sheets of flexible material, which are larger than to arrange the laminate package to be pressed and the edges of the thin foils between solid rings sufficient to press together. The sack formed between the flexible films is then evacuated, while the laminate package in the sack is subjected to negative pressure within an autoclave. this allows the preliminary pressing and the final Lamination to be carried out in the same chamber. Packing and unpacking the laminate packages is a crucial one Disadvantage of this procedure.

From U.S. Patent No. 4,425,406 a vacuum bag is disclosed Glass fiber known, which has a layer of silicone rubber on the outside, around the spaces to be filled between the glass fibers, leaving the inner surface of the bag unchanged and the individual glass fibers are in direct contact with the glass surface of the during lamination Laminates kick. Three of the four edges of the bag are pressure sealed; there is only one left Edge open to accommodate the laminated package. However, this apparatus is for intricately curved shapes Can only be used to a limited extent with large bending depths.

The object of the present invention is to provide an apparatus and a method for preliminary pressing or / To create a laminate package that is suitable for mass production of complicated bent laminate packages is suitable.

This object is achieved by the method according to claim 1 and the device according to claim 6th

Preferred embodiments of the invention are described in the subclaims.

The arrangements to be laminated are according to the invention also called laminate packages ^ and between two separate covers made of flexible rubber material carried. The lower blanket is in the form of a hammock between two adjustable lengthways Beam elements suspended to adjust the deflection of the lower ceiling between the beam elements to be able to. A laminate package made of glass and a plastic wrap that is smaller than the blankets will be used placed in the middle part of the lower ceiling and an upper ceiling that is larger than the laminate package across the board over the laminate package and the frame ~ shaped central part of the lower ceiling, with its outer edges outside the outer circumference of the laminate package.

The lower ceiling is specially designed in the middle part, to form a suction path across the top surface of the middle section and it is in the middle section there is an opening through the thickness of the ceiling to the lower surface. There is a connecting pipe there for a connection line to a vacuum source .

The laminate package is placed between the flexible blankets at a temperature between room temperature and a maximum temperature which is determined by the properties of the flexible intermediate layer, arranged. At that temperature, vacuum is applied to that trapped between the layers of the laminate Remove air and those between the flexible blankets. The evacuated laminate package is then used together with the flexible blankets for about Exposed to elevated temperature for 5 to 15 minutes.

This elevated temperature is sufficient to bond the intermediate layer to the glass that is lying However, below the temperature limit of the intermediate layer and the ceilings. While warming up the vacuum is maintained to provide relatively wide clear areas along the edges of the Laminate package to achieve. These should extend from the edge inwards over a distance of preferably extend more than an inch. 10

To ensure that the top and bottom blankets are outside the perimeter of the laminate package close to each other and allow the generation of negative pressure, weights are provided that at a distance from the outer circumference of the laminate package act from above on the upper flexible ceiling. For elongated laminate packages that form a cylindrical Shape to be bent over one or more transverse axes, the weights are preferably made from a pair of rod weights that are about the width of the top surface of the top Cover next to the edges on the longitudinal ends of the tentative Laminates to be pressed are arranged and a pair of chains extending between the ends the bar weights extend laterally outside the side edges of the laminate package in the longitudinal direction. Through this the upper ceiling is weighted and opened outside the circumference of the laminate package to be pre-pressed printed the lower flexible ceiling. The chains are flexible to adapt to the shape of the laminate package. The shape of the laminate package determines the shape of the hammock in the longitudinal direction from the two flexible ones Blankets made of rubber material.

Preferably, the upper surface of the lower ceiling is equipped with suction ducts in the central area, over the outer circumference of the to be pressed

Reach out the laminate package in the middle section. These suction channels are preferably formed by reducing the thickness of the lower ceiling in the central part. In other words, the lower ceiling has a recessed one Middle part, which is larger than the laminate to be pre-pressed and surrounds the laminate package in a frame-like manner. In the lowered central part, stools are preferably provided, which are arranged in rows and the upper ends of which extend into the plane of the upper surface of the lower ceiling. The stool in adjacent rows are preferably offset from one another.

The flexible blankets are preferably made of reinforced rubber material, preferably one with polyamide fibers reinforced elastomer. The lower surface of the upper ceiling can be provided with suction channels in the same way become like the upper surface of the lower ceiling. However, there are fewer on the upper ceiling Passages required than with the lower ceiling.

The above-described device for preliminary pressing of a laminate package is for repetitive use Use suitable and can be used especially when windshields with different Shapes are to be pre-pressed without having to change the blankets. Only in the case of It is necessary to adjust the supports that hold the blankets in order to achieve extremely different patterns in this way an adaptation to different bending radii and different shapes can be achieved.

It is an essential feature of the present invention that the pair of separate blankets be made of flexible Material is arranged in such a way that the ceilings lie tightly against one another, but without each other the edge parts of the two ceilings in the case of

connect treatment firmly. The two ceilings are tightly seated outside and at a distance from the outer circumference of the provisionally to be pressed Laminate package, so that there is still a suction channel along the outer line of the laminate package. This makes it possible to separate the blankets from each other again after each pre-pressing process and the pre-pressed Remove the laminate package and send it to the final lamination step in an autoclave.

The device for preliminary pressing or pre-pressing can then be filled with a new laminate package will. This mode of operation does not require any further pressing of the glass panes against the plastic intermediate layer along the edges to reinforce the intermediate layer near the outer perimeter, as described in U.S. Patent 2,999,779.

The invention will now be described with reference to the figures.
20th

Fig. 1 is a perspective view of a

group prepared for preliminary pressing ν La ** »» '"a tpAttt
pierung <T ~ carried between a lower flexible blanket and a raised upper flexible blanket, according to the invention

partially cut off parts in order to make other parts visible in their arrangement.

Fig. 2 is a top plan view of the array of Fig. 1 showing different parts of the upper apparatus are not shown in order to make the lower parts visible.

FIG. 3 is an end elevation taken along line 3-3 of FIG.

Figure 4 is an enlarged, partial cross-section of portions of the array and looking in the longitudinal direction part of the grouping as initially arranged relative to the device is and before the start of the preliminary pressing process.

In the figures is a preferred embodiment reproduced the invention. One in general

10 'horizontal base has elongated angle irons 21, which are connected to cross members 22. There are mounting arms with internal threads that are movable along adjustment rods 25 with external thread for individual longitudinal adjustment of the position of each of the fastening arms 23 with internal thread in position relative to the elongated angle irons 21. A crank 24 is provided to hold the threaded rods 25 to rotate with external thread, so that the fastening arms 23 with internal thread in the desired Position can be moved as described later.

A bracket 27 extends obliquely upward and downward from each of the internally threaded fastening arms 23 Outside. A cross connection bracket 29 connects each of the upper ends of the upwardly extending Carriers at each longitudinal end of the device. Each cross connection bracket 29 has an inwardly directed one Approach at each outer end. The approach at each of the longitudinal ends of the device takes the opposite one Ends of a cross bar 33. The device is also equipped with a flexible Floor material 34, the longitudinal ends of which are looped around the cross bar 33, so that the flexible Floor cover 34 in the form of a hammock between the cross bars 33 extends. By moving towards each other and moving the two cross-link brackets away from each other 29 reduces their longitudinal distance and the

The longitudinal shape of the hammock changes compared to the position of the transverse bars changed. These Adjustment allows the hammock to take on a cylindrical shape when the cross-connecting brackets 29 are equidistant from the center on each side and have a truncated conical shape (frusto-conical shape) if the distances are different on both sides.

The flexible floor mat or blanket ~ 5k has a recessed middle part 36 in the middle, in the middle of which there are devices for connecting a vacuum line. The recessed middle part is larger than the largest outer circumference of a laminate package that is to be temporarily pressed in the device according to the invention. The recess is formed as a shoulder in the central part and has a plurality of rows with humps, which extend from the bottom of this recess. The upper ends of the stools are in the same plane as the upper surface of an outer frame portion 37 which surrounds the recessed central portion 36 of the lower flexible ceiling 3 ^. A typical blanket is a 2 mm thick sheet of synthetic elastomer reinforced with polyamide fibers with a recessed central portion 36 that is 1 mm from the top surface of the blanket. In the recessed central part 36, rows of 1 mm high bumps, which have a diameter of 2 mm, are arranged. The distance between the centers of the stools in each row is approximately 3 mm from center to center. The rows are 3 mm apart. The stools in adjacent rows are offset from one another by 1 mm from row to row in order to create passages in the recessed central section 36. The outer frame portion 37 of the lower flexible blanket has smooth top and bottom surfaces. Alternatively,

nen the means for creating evacuation routes have humps that extend over the main surface of the flexible Floor cover 34 protrude in the recessed central part. The recessed central portion 36 of the flexible floor covering 3 ^ carries within its circumference the outer circumference of the laminate package to be bent from two bent Glass panes and a thermoplastic intermediate layer which is to be temporarily pressed together. The term glass is used in general in the following and is also intended to include plastic compositions, for example acrylates or polycarbonates instead of glass, as well as silicate glasses. The intermediate layer is preferably plasticized polyvinyl butyral, but can also be any other known interlayer material, for example polyurethane.

An upper flexible blanket 38 is above the outer frame part 37 of the lower flexible sheet 34 and the laminate package A are arranged for preliminary pressing.

The size of the upper flexible sheet is such that it extends at least 5 cm (2 inches) above the edge of the recessed central portion 36 in the lower flexible floor sheet so that the upper flexible sheet 38 bridges the upper edges of the surface of array A and up to the upper surface of the flexible floor cover ~ 5k extends to form the vacuum edge chamber 39, as shown in FIG. The upper flexible cover 38 is shown with a smooth surface. However, it is within the scope of the invention for the lower surface of the upper flexible cover 38 to be provided with passages which are arranged in the region of the recessed central part 36 of the lower floor cover 34. The surface of the upper flexible blanket 38 facing array A need not be indented as much as that indented

Middle section 36. However, it is desirable that the upper flexible cover 38 have at least one exit passage which extends over the entire distance of the grouping to be pressed. Final grinding 35 are provided at each end of the upper flexible blanket 38 to accommodate transverse bars, not shown, which make it possible to separate the ceilings from each other in order to place the grouping A between them.

The flexible floor cover 34 is provided with an opening extending through its entire thickness, of which an outlet pipe 40 extends downward and the connection between the suction paths of the recessed Center part 36 produces with a vacuum source, so that vacuum can be applied in the space between the recessed central portion 36 of the flexible flooring 34 and the lower surface of the array A, which is to be pre-pressed and also in the vacuum edge chamber 39 between the covers 34 and 38, which surrounds the outer edge of grouping A. This allows air to be sucked out between the individual layers of the grouping and also from the upper surface of the grouping and the lower surface of the upper flexible blanket 34, with the upper flexible blanket 38 snugly on the lower flexible blanket 34 rests outside the grouping. This forms a vacuum rim chamber 39 that contains the grouping A surrounds. The vacuum rim chamber 39 delimits the recessed central part and is in communication with the Vacuum source so that the pressure in the space between the two flexible blankets 34 and 38 is reduced and so can remaining air and other volatiles from the decreasing volume can be removed.

The upper flexible blanket 38 is provided with a series of loops 42 near each end. Every

of these loops 42 carries a rod weight 44 in a position near the longitudinal ends of the recessed Middle part 36. In addition, rings 45 are attached to the end parts of the rod weights 44 for receiving the Ends of flexible chains 46. The latter extend along lines laterally outside the Side edges of the recessed central portion 36 in the flexible floor cover 34. The chains 46 can prevent transverse movement by screwing the chains with additional, loops not shown be secured along the long sides of the upper flexible Ceiling 38 are arranged. This creates a framework of adjustable weights that drop down against the top surface of the upper flexible blanket 38 press in the part that completely surrounds the grouping to be pressed. This will be the outer edge of the space between the flexible blankets 34 and 38 is formed.

The composition of the flexible blankets is such that a vacuum chamber 39 is formed between the blankets which is sealed off from the atmosphere. The composition of the flexible ceilings however, must be chosen so that the upper flexible blanket 38 and the lower flexible blanket 34 are in the temperature range for the usual pressing processes.

In the form shown, the rod weights 44 are threaded through the loops 42 on the upper flexible blanket 38 pushed and connected to flexible chains 46 which have such a mass per unit length that a sufficiently tight fit in the edge parts of the flexible blankets 34 and 38 on one another, however is achieved without a firm bond. Acceptable masses per unit length are 4 to 18, preferably 9 g per centimeter of chains in combination with 2 mm thick blankets for pre-pressing groups of two

23 351Ί

Panes of glass each 2.3 mm thick and one plasticized Intermediate layer of polyvinyl butyral 0.8 mm thick. The arrangement of the weights from the rod weights 44 and the flexible chains 46 must be done around the entire middle part 36 that a suitable Vacuum chamber is formed around the group to be pressed.

To prepare the device for preliminary pressing, the flexible floor cover 34 is suspended between the cross bars 33. The cross bars 33 are fixed inside between the lugs 31 and the carrier 27 moved towards each other that the lower flexible floor cover 34 forms a free-hanging hammock, which is in the desired cylindrical or conical shape hangs. Then a grouping A is made of bent sheets that are laminated together are to be brought into a central position over the recessed central part 36 and the upper flexible blanket 38 over the lower flexible blanket 34 and over the array leading from the recessed central portion 36 is carried, arranged. This is done in such a way that the bar weights 44 extend over the longitudinal ends of the larger frame parts 37 of the flexible floor covering extend approximately 5 cm outside the corresponding longitudinal ends of the recessed central part 36 and the flexible chains 46 over the upper flexible cover 38 extend the length of the side panels of the outer frame 37, the flexible floor cover 34 at a distance of 5 cm laterally outward the longitudinal edges of the recessed central part In the case where the grouping around one substantially a uniform bend radius and the deepest part less than 3 inches (7.6 cm) deeper bar weights 44 and chains 46 can be dispensed with.

A typical and successfully working apparatus has rectangular ceilings with a length of 203 cm (80 inches) χ 122 cm (48 inches) wide and a large recessed center section with a rectangular perimeter 163 cm (64 inches) long and 81 cm (32 inches) wide in the center of the ceilings. The lowered middle parts are provided with a cusp pattern in the recessed middle part, as it was already has been described for the pre-pressing of various commercially available forms of windshields.

The best results have been obtained when the apparatus with the one between the upper and lower Laminate package arranged in flexible blankets a pressure of 98.6 mbar to 234.6 mbar (23 to 27 inches of mercury below standard atmospheric pressure). After one to three minutes of evacuation At room temperature of about 25 ° C, the laminate packages are additionally 8 to at the same negative pressure Evacuated for 18 minutes at a temperature of 121 ° C. Excellent results are obtained when the Device having upper and lower covers made of an elastomer reinforced with polyamide fibers, with a recessed central part on both sides facing the outer surfaces of the laminate package. The result is clear, transparent surfaces with a width of more than 2.54 cm in the entire outer edge area of the Laminate package.

If the floor cover is an elastomer reinforced with polyamide fibers with a recessed central part together with upper covers of the same composition, but with a smooth surface or a slightly roughened surface Surface or completely flat surface for pressing a bent laminate package are used, in most cases there are no significant air pockets to the naked eye

Laminate package recognizable if the following procedure has been carried out: Flexible blankets are used for pressing, of which only the lower one has a recessed central part that extends over the edge of the Laminate package stretches and it is vacuumed for at least two minutes without heating when pressed and then evacuated for at least eight minutes while heating to 121 ° C.

A combination of a 2mm thick lower blanket 34 with cusps in the 1 mm deep lowered middle part 36 with a 2 mm thick smooth upper cover results in air pockets in some cases when prepressing relatively flat windshield shapes in the laminate package. To solve this problem, it has been proposed to have a flat narrow one in the upper ceiling Form longitudinal groove that extends over the entire surface of the ceiling in the area of the laminate package. Stiffer or thicker materials for the upper flexible ceiling solve the problem of air pockets Likewise. At the preliminary pressing of very severely curved windshields this problem was not observed.

Another suitable material for successful work was a neoprene rubber with smooth Surface found. This allows partial heating in the oven to 121 ° C. following 2 minutes Evacuate to a pressure of 778.5 to 914 mbar (23 to 27 inches mercury) at room temperature. Only then does the laminate package take on the hot furnace atmosphere exposed. When trying to use neoprene rubber as a cover material at oven temperatures of 149 ° C, It was found that the rubber, due to the higher temperature, during successive pressing operations Laminate packages of the same shape and the same outer circumference tend to show permanent deformations.

which make it impossible to change the shape and pattern of the laminate package without changing the ceiling power. Synthetic elastomers that are reinforced with polyamide fibers allow a permanent load of 130 ° C. Under these circumstances, flexible blankets can temporarily be exposed to oven temperatures of 121 ° C without damaging the covers or the intermediate layers of the laminate packages. Since the Speed of joining the layers of the laminate package with increasing temperature during the vacuum treatment As the parcel increases, the temperature is chosen as high as possible, with these maximum temperatures with the highest possible temperature loads on the intermediate layers of the laminate package and the flexible ceilings must be in harmony.

The material used for the intermediate layer of the laminate package during prepressing determines whether it is necessary is to cool the ceilings to room temperature during mass production on an industrial basis. For example, allow laminate packages with a plasticized polyvinyl butyral interlayer (DuPont B-140), which has a distinctly rough surface appearance has sufficient ventilation when pre-pressing, even if the ceilings are at the beginning of the pressing process have a temperature of 49 ° C. at Laminate packages with a polyvinyl butyral interlayer (Monsanto TL) proved to be necessary to cool the blankets to a maximum temperature of 32 ° C in order to be able to pre-press successfully.

If you use a base frame or a horizontal base support with an internal thread Fastening arms 23 at each of the four corners of the device are when the shape of the According to general experience, the laminate package to be pre-pressed is only slight for most shapes

Changes necessary. For complicated shapes that differ greatly from the usual slightly curved windshield shapes many vehicles differ, there is a change in the lower ceiling mounting for each Change of form required. This can be done by that either a pair of the fastening arms arranged on one or the other longitudinal side of the device moves, or that one moves all four mounting arms to the position of the cross bars 33 to steer.

The temperature during heating helps to create clear edge areas when pre-pressing the laminate and the To connect the panes of glass at the outer edge sufficiently firmly to the intermediate layer of the laminate package and the penetration of liquid or gases into the package during the subsequent final lamination to prevent at higher temperature and pressure in an autoclave. The out of scope the required force of the laminate package, i.e. the force exerted by the chains and rods on the upper surface of the flexible blanket must be sufficient in order to press the covers tightly against one another at the sides outside the circumference of the laminate package, without however, to permanently connect the flexible ceilings to one another. In this way, the between the Flexible ceiling formed chamber sealed against the outside atmosphere and there can be air and others Liquids or gases not only from the layers of the laminate package to be temporarily pressed, but also between the laminate package and the inner surfaces of the flexible blankets that make up the Package, surrounded, to be removed by evacuation. That required evacuation for 1 to 3 minutes at a relatively low temperature at the start of the evacuation cycle is important to make sure that

Air trapped between the layers of the laminate package is removed before the intermediate layer soft enough to seal the top and bottom glass panes of the package together connect and thereby prevent the removal of trapped air.

Examples

Lam-inat packages with curved glass panes, the bending depth of which is less than 7.5 cm, were between two flexible ceilings arranged, which are provisionally only along the edges perpendicular to the bending axis connected to each other. Successful pre-pressing was through the following evacuation steps at room temperature and subsequent further evacuation reached at elevated temperature.

1. Pre-evacuate one minute at 846 mbar Room temperature and then additional evacuation for 9 minutes at 846 mbar at 135 ° C.

2. 5 minutes pre-evacuation at 846 mbar and then 7 minutes continuation of the evacuation at 141 ° C.

The next series of tests was carried out with temporarily connected only along their edges Ceilings, as in Examples 1 and 2 for pre-pressing laminate packages that were more strongly curved (bending depths from 15 to 20 cm, 6 to 8 inches). These attempts were unsuccessful except in the Cases where the blankets are clipped together outside the perimeter of the laminate packages prior to pre-evacuation became.

At this stage of the experiment it was decided to use bonded or stapled ceilings and separate ceilings only in further attempts to pre-press laminate packages with a bending depth of more than 3 inches (3 inches) to be used.

Four packets of laminate were prepressed using a flexible lower sheet of polyamide fiber reinforced synthetic elastomer with a recessed central portion to provide a suction path and an upper flexible sheet of cotton fiber reinforced neoprene rubber with a smooth surface. Three laminate packages were pre-pressed without pre-evacuation step at room temperature, merely by applying a vacuum of 980 mbar for 10 minutes at 135 ⁰ C. These attempts were unsuccessful. The fourth laminate package was exposed to a negative pressure of 980 mbar at room temperature for 1 minute as a pre-evacuation step. The vacuum treatment was then continued at the same pressure, but at 135 ° C. for 10 minutes. All four laminates had air pockets. From this experiment it was concluded that one should use upper and lower blankets whose coefficients of thermal expansion match, preferably blankets made of the same flexible material.

In the next series of tests, flexible upper and lower blankets made of polyamide fibers were used reinforced synthetic elastomer that had recessed center portions that were larger than that Scope of the laminate packages to be pre-pressed. In these experiments, both the pre-evacuation time was Room temperature and the duration of the subsequent evacuation at 121 ° C varies. In addition, a with Sack filled with lead balls on the upper flexible cover

placed in order to weigh them down outside the circumference of the laminate package to be pressed.

In some attempts, but not always, the samples also showed no pre-evacuation step No trapped air bubbles at room temperature when laminate packages with polyvinyl butyral interlayers Type B-1AO from DuPont were processed. However, this was never the case with pre-pressed Laminate packages with polyvinyl butyral interlayers with softer main surfaces than with the B-140 interlayer material.

One to three minutes pre-evacuation at room temperature and a negative pressure of 778.5 mbar and then Further evacuation lasting at least 8 minutes at a temperature of 121 ° C resulted clear outer margins about an inch wide and a good prepress pattern with no evidence of trapped Air. If the upper ceiling is a smooth ceiling with the same composition as that of the lower one Ceiling was used in combination with a lower ceiling that had a recessed center section as a suction path the same results were obtained as when using two blankets with each recessed middle part, except for occasional experiments in which air pockets were observed were on flat bent laminate packages with a bending depth of less than 3 inches. No air pockets were observed with all laminate packages with a bending depth of more than 3 inches.

Sixteen laminate packages of various practically occurring windshield patterns were temporarily pressed using the best embodiment and arrangement of the ceilings determined in previous experiments were to the effects of the four variables

to compare * The effects to be compared were the presence or absence of a pre-evacuation step at room temperature after arranging the laminate packages between flexible blankets, one of which has a recessed central part as a suction path in the upper surface, the comparison of the heating times of 8 and 12 minutes when a vacuum is applied while heating, the comparison of laminate packages with smooth intermediate layers and _ ■ _ intermediate layers with less smooth surfaces and the comparison of the results of prepressed laminate packages that are simultaneously subjected to heat and vacuum in an oven from 121 ° C were applied with those in an oven which was kept at 150 ° C.

Each laminate package was assessed for the proportion of clear areas and also the width of the sealed edges determined in millimeters after pre-pressing. All prepressed laminate packages were then finally laminated in an oil autoclave at a pressure of 13.8 Pa for 60 minutes at 150 ° C. This Samples were rated for oil penetration. Then the laminated windshields were made Immersed in boiling water for two hours and examined for bubbles.

The results are given in the table below. Each line for each laminate package tested contains the following information. In the first column the test number. The information follows in the next column on pre-evacuation, where P2 means applying a vacuum for 2 minutes at room temperature. The samples that have not been pre-evacuated are marked with PO. In the next column is the application of vacuum at elevated temperature

labeled HE, with 8 or 12 minutes each
was evacuated. The temperature of the oven is given in the next column. H contains an oven temperature of 150 ° C. and L an oven temperature of 121 ° C. The intermediate layer is specified in more detail in the next column, where R denotes a rough surface of the intermediate layer (commercially available material B-140 from DuPont) and S a smooth surface. In the next column, headed clarity, the percentage that was clear in the respective prepressed sample is given. In the next column with the head depth, the width of the seal achieved is given in millimeters of the pre-pressed pattern. The last column shows the number of bubbles observed after testing in hot water.

Sample Preva Warming Tempe Intermediate Clear Depth Bubble no. kuieren mungsratur layer number

duration

1 PO 8th L. R. 10 12th 0 2 PO 8th H R. 15th 14th 0 3 PO 8th L. S. VJt 9 1000+ 4th PO 8th H S. 5 13th 1000+ VJl PO 12th L. R. 15th 17th 0 6th PO 12th H R. 10 21 9 7th PO 12th L. S. 5 18th 260 8th PO 12th H S. 5 18th 313 9 P2 8th L. R. 35 16 0 10 P2 8th H R. 20th 16 0 11th P2 8th L. S. VJl 8th 57 12th P2 8th H S. 5 11th 1000+ 13th P2 12th L. R. 50 24 0 14th P2 12th H R. 75 34 0 15th P2 12th L. S. 5 15th 1000+ 16 P2 12th H S. 5 22nd 500

Five of the 16 laminated windshields showed penetrated oil. Four of them were when the Vacuum exposed to the higher temperature.

All laminated windshields with smooth interlayers exhibited blisters after testing in boiling water compared to only one in eight laminated windshields with interlayers with a relatively rough surface. The mean percentage of clear areas of the pre-pressed laminate packages without pre-evacuation at room temperature was only 9% compared to 25 % with pre-evacuation lasting 2 minutes. The mean percentage of clarity for the prepressed laminate packages that were simultaneously exposed to vacuum and heat for 8 minutes was 12.5 % compared to an average of 21.2 % clear area for the samples where heat and vacuum treatment lasted 12 minutes. The prepressed laminate packages, which were simultaneously subjected to heat and vacuum in a 121 ° C oven, had an average clarity of 16.2 % compared to an average clarity of 17.5 % of the area for the samples that were in one Oven of 150 ° C were treated. The laminate packages with intermediate layers with a rough surface had an average of 28.8% clear areas after prepressing, compared to the average of 5 % clear areas for those with intermediate layers which had smooth surfaces. Comparing the width of the edge seal of the laminate packages pre-evacuated at room temperature compared to those that were not pre-evacuated, the result is 18.3 mm wide edge seal with pre-evacuation and 15.3 mm without pre-evacuation if the simultaneous application with heat and vacuum lasted 12 minutes. After 8 minutes of exposure to heat and vacuum

21.1 mm wide edge sealing is achieved with pre-evacuation compared to only 12.4 mm Edge sealing without pre-evacuation. The middle Edge seal width of prepressed samples in a 150 ° C oven was 18.6 mm Compared to 14.9 mm at an oven temperature of 121 ° C. The mean width of the edge seal was pre-pressed Laminate packages is now 19.3 in the case of intermediate layers with a rough surface in comparison contributes to a mean sealing width of 14.3 mm Use of intermediate layers with smooth surfaces.

This leads to the conclusion that a short pre-evacuation step before the simultaneous application of vacuum and heat, pre-pressed laminates with larger ones clear surfaces, a wider edge seal and less trapped air. The same Benefits are achieved by increasing the time that heat and vacuum are applied simultaneously or by using an intermediate layer with a rougher surface. Such products are available in the stores. Higher temperatures during prepressing give a wider edge seal, however, do not affect the clarity of the prepressed laminate packages. These laminate packages have however, more entrapped air than when applying negative pressure at the lower temperature. aside from that have those exposed to a vacuum at a higher temperature Pattern the tendency for more bubbles on the edges and more oil penetration final lamination in an autoclave.

The results show that it is optimal for the prepressing of glass-plastic laminate packages, upper and lower ceilings of the same composition, whereby the lower ceiling has a recessed central

has part as a suction path, the area of which is larger than the area of the laminate package to be pre-pressed and wherein the top cover can either have a smooth surface if the bending depth of the lamps is greater than 3 inches. With weakly curved Laminate packages with a bending depth of less than 3 inches, it is advantageous to cover the upper ceiling with a Provide a suction path that does not have to be as large as that in the lower ceiling. A pre-evacuation during 1 to 3 minutes at room temperature is particularly advantageous in combination with subsequent exposure of vacuum and heat at an oven temperature of 121 ° C for 8 to 18 minutes. The length of time depends on the bending depth and the complex shape of the laminate package.

On further experiments it was found that the required time for the simultaneous heating and applying a vacuum, also depending on the thickness of the glass.

20 'depends and increases with increasing glass thickness. If the laminate packages to be pre-pressed are both longitudinally are also bent in the transverse direction, it is advantageous to the weight of the rods 44 by chains or to replace other flexible weights which develop the same effect as the chains 46. In this Case it is advantageous to provide variable weights, both in the longitudinal direction and in the transverse direction of the laminate package to be processed to be provided on the ceilings along a line that extends outside the outer circumference of the laminate packs to be pre-pressed. But it is also possible to use fixed bar weights to be arranged at a greater distance from the edge of the laminate package to be pre-pressed. Allowed in this case the flexibility of the blankets to adapt to the shape of the laminate package to be pressed without

3d
Wrinkles appear in the vicinity of the laminate package.

The invention has been described with reference to a device which has a flexible lower cover 34 with Facilities that provide a suction duct in the middle part of the ceiling and a flexible upper ceiling 38, which either has a smooth surface or a smaller area that provides a suction path Is provided. It is within the scope of the invention, the corresponding embodiments of the above and swap lower flexible ceilings. For the usual centering of the laminate package in the lowered position In the middle part of the flexible blanket, it is preferred to have the lower flexible blanket with a lowered middle part equip and form suction paths by providing humps.

Claims (13)

Patent Attorneys ^ (1883) St / kr Dr. Michael Hann Dr. H.-G. Sternagel Marburger Strasse 38 Gießen Applicant: PPG Industries, Inc. Pittsburgh, PA, USA "Prepressing device for complex curved laminate packages and method for pre-pressing curved laminate packages11 Priority: April 2, 1984, US Serial No. 596,184 patent claims 1. Method for preliminary pressing of a laminate package from a pair of curved panes of the same shape made of glass or a transparent glass substitute and an interposed layer of a thermoplastic interlayer material, characterized by placing a laminate package in direct contact with the central part of a hammock from a first flexible ceiling made of a material impermeable to air that does not adhere to the glass or when raised Temperatures at which the intermediate layer of thermoplastic material bonds with the glass, sticks to the glass and which has a central part with suction paths on the surface, such that in the frame-like edging of the central part of the first flexible ceiling part of the surface remains uncovered, Applying a second flexible blanket of an air impermeable material, which is larger than the laminate package and also larger than the central portion of the first blanket, over the laminate package and the first blanket such that the edge of the second flexible blanket is adjacent to and outside the edge of the laminate package and the middle part and closes the part of the first flexible blanket surrounding the laminate package without binding, applying a negative pressure through the thickness of the first flexible blanket in the middle part for at least one minute while the laminate package is at room temperature,
Heating the laminate package to an elevated temperature sufficient to bond the interlayer to the glass panes, however, neither the flexible blankets nor the interlayer material destroyed while maintaining the negative pressure for a time sufficient to form a clear edge on the laminate package, however the ceilings are not permanently connected to one another, lifting the upper flexible ceiling and removing the laminate package from the lower flexible ceiling. 2. The method according to claim 1, characterized in that one additionally on the upper one before heating Surface of the upper flexible blanket elongated weights at a distance from the longitudinal ends of the laminate package and flexible weights laterally spaced from the longitudinal side edges of the Laminate package applies. 3. The method according to claims 1 or 2, characterized in that one used as a second flexible blanket which has a central part with a suction channel which is longer than the corresponding dimension of the provisional to be pressed laminate package and that one the second flexible blanket with the downward facing Middle part is arranged over the entire laminate package. 4. The method according to claims 1 or 2, characterized in that there is a second flexible cover with a smooth surface used and arranged over the laminate package on the first blanket. 5. The method according to claims 1 to 4, characterized in that the laminate has a curvature over its main axis which changes from a given radius along a longitudinal edge to a larger radius of curvature than the one given along the opposite longitudinal edge and the first flexible blanket between the two Girders so that a longitudinal edge extends between girders at a given distance from one another and the other longitudinal edge is between beams at a different distance from each other is located. 6. Device for the preliminary pressing of a laminate package, containing a thermoplastic film made of intermediate layer material, for example plasticized polyvinyl butyral, which is arranged between a pair of glass panes or hard transparent plastic plates as a glass substitute,
characterized by a pair of cross bars (33) with ends (31) bent at right angles, Means (22, 23, 27, 29) for adjusting the longitudinal distance between corresponding ends (31) the cross bars (33), a first flexible blanket (34) of gas impermeable material having an upper and a lower major surface, which is suspended in the form of a hammock between the cross bars (33), with a central part (36) with an outer edge, the circumference of which is greater than that to be arranged within the central part (36) Laminate package, and on their upper main surface in the middle part facilities are present that form a suction path and which in the middle part (36) has an opening extending through the thickness of the flexible cover (34), a second flexible blanket (38) made of gas-impermeable material which is larger than the central part (36) and which is arranged on the first flexible blanket (34) so that it has a central portion (36) on the first flexible blanket (3 * 0 arranged laminate package directly covers and wherein the edge of the second flexible blanket (38) outside the outer edge of the Middle part (36), surrounding this, rests, and the superimposed, not permanently with each other connected flexible covers (34, 38) form a vacuum chamber surrounding the central part (36), Means (40) for connecting the opening in the first flexible blanket (34) to a vacuum source in order to a negative pressure in the suction path and the vacuum chamber formed between the covers (34, 38) to produce a laminate package arranged therein, with the environment outside the two ceilings (34, 38) is at atmospheric pressure. 7. Apparatus according to claim 6, characterized in that on the second flexible cover (38) outside and at a distance from the outer edge of the central part (36) of the first flexible cover (34) elongated lines weights (44, 46) are attached. 8. Apparatus according to claim 7, characterized in that the elongated weights are flexible chains (46), which are arranged on the second flexible blanket (38) and follow the shape of the laminate package (A) can customize. 9. Apparatus according to claim 6, characterized in that the devices forming the suction path a Multiplicity of rows of humps are whose upper ends are in the plane of the upper surface of the first flexible blanket (34). 10. Apparatus according to claim 9, characterized in that the stool from adjacent rows are arranged offset from one another. 11. The device according to claim 6, characterized in that the second flexible blanket (38) has a major surface with a plurality of passageways in it Middle part, which extend over the entire length of the laminate package and that the second flexible Cover (38) is arranged so that the main surface described faces the laminate package and at least one of the passages extends beyond the laminate package. 12. The device according to claim 6, characterized in that the, at the opposite longitudinal ends the first flexible blanket (34) attached transverse rods (33) of obliquely upwardly extending, at the ends of the transverse rods (33) attacking beams (27) are held and the distances between the corresponding ends of the cross bars (33) along the longitudinal edges the first flexible blanket (34) by changing the position of the supports (27) relative to one another can be set differently, for the preliminary Pressing a laminate package that has a curvature about its main axis that changes from a given radius along a longitudinal edge to a greater radius of curvature than the given along the opposite longitudinal edge. 13. Apparatus according to claim 12, characterized in that the corresponding ends of the cross bars (33) along the first longitudinal edge of the first flexible blanket (34) on a relative to the corresponding Ends along the opposite longitudinal edge of the first flexible blanket (34) smaller distance are adjustable.