DE2420355A1 - INTERMEDIATE LAYER MADE OF POLYVINYL BUTYRAL FOR LAMINATED SAFETY GLASS - Google Patents

Description

DR. BERG DIPL.-ING. STAPF DIPL.-ING. SCHWABE DR. DR. SANDMAIR

PATENT LAWYERS 242Q355

8 MUNICH 86, POST BOX 860245

Lawyer file 2k 985 of »/ mn -s - *:;,

MONSANTO COMPANY
ST. LOUIS / MISSOURI / USA

Intermediate layer made of polyvinyl butyral for laminated safety glass

The present invention relates to a composite interlayer made of polyvinyl butyral for laminated safety glass and a process for their production. In particular The present invention relates to a composite intermediate layer for laminated safety glass, which has a graduated color gradient.

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Foil material made of polyvinyl butyral is used as an intermediate layer for laminated glass, which is used in vehicles, especially in wind " Schutzscheiöen, and is used in architectural applications, known. In many applications, the intermediate layer is tinted with a color to give a colored laminate. One The main uses of tinted film foils are in car windshields. In these applications, the intermediate layer is printed with a graduated color that is arranged in such a way that it has a gloss-reducing effect on the top of the composite windshield Forms color gradation band.

The printing process for the on used in windshields Gradient tint applied between layers requires printing on the surface of the polyvinyl butyral film with paint in the form of polka dots. The film is then usually powdered with a material such as sodium bicarbonate to bring unwanted dye transfer to a minimum. Before being used as an intermediate layer, the sodium carbonate dust washed off the foil, which is then dried and coated with the glass. The printing of the interlayer material gives rise to the need to powder and then wash the foils. In addition, the adhesion of the printed part the film on the glass can be adversely affected by the printing process.

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There is a definite need in the art for a graded colored interlayer material of Polyvinyl butyral, which has desired adhesion to "glass" and does not require powdering and washing before use.

SUMMARY OF THE INVENTION

The present invention solves the aforementioned problems known in the art by providing a method for Manufacture of a composite intermediate layer made of polyvinyl butyral, which does not require powdering or washing before use.

The composite intermediate layer produced by this method comprises the union of at least two films Polyvinyl butyral, wherein at least a portion of at least one of the films of polyvinyl butyral on one in direct contact is colored with the other side, which is made of polyvinyl butyral.

DESCRIPTION OF THE DRAWINGS

Figures I to IV. Illustrate cross sections of the inventive Composite interlayers.

FIG. I shows a film 11 made of polyvinyl butyral, printed with ink 12, where the printed side is in direct contact with a second film 13 made of polyvinyl butyral.

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Figure II illustrates two, each with a Faroe 12
printed films 11 made of polyvinyl butyral, where the printed sides are combined.

FIG. III illustrates a film 11 made of polyvinyl butyral which is printed on both sides with an ink 12, the
printed sides are each combined with a different film 13 made of polyvinyl butyral.

FIG. IV illustrates a colored wedge-shaped film made of polyvinyl butyral, which is sandwiched between two films 13 made of polyvinyl butyral is inserted.

Other variations in the design of the above composites are for the after reading the present specification
One skilled in the art can be seen.

Figure V is a schematic diagram showing the extrusion of molten polyvinyl butyral onto the surface of a
Polyvinyl butyral film shows which had been printed with a graduated color.

Figure VI is a schematic diagram showing the
Combination of two sheets of polyvinyl butyral shows, where

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one of which had been printed with a graduated color which is located on the intermediate layer of the resulting composite .

Figure VII is a schematic diagram showing another, more detailed method of combining two foils Shows polyvinyl butyral, one of which had been printed with a graduated color which was applied to the interlayer of the resulting composite is located.

DESCRIPTION OF THE PREFERRED DESIGN

In general, those used in the present invention have Polyvinyl butyral resins have a Staudinger molecular weight of from about 50,000 to 50,000, and preferably from 150,000 to 27O 0OO, and it can be assumed that the resins from 5 to 30 percent by weight hydroxyl groups, calculated as polyvinyl alcohol, 0 to 10 percent by weight ester groups, as polyvinyl esters calculated, and the remainder are essentially made of butyraldehyde. The polyvinyl butyral resin is preferably 9 to 25 percent by weight Hydroxyl groups, calculated as polyvinyl alcohol, and 0 to 3 percent by weight acetate groups, as polyvinyl acetate calculated, and the remainder essentially contains butyraldehyde ..

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It is common to use the alkali titer of the polyvinyl butyral resin set so that the impact resistance of the resulting laminate is optimal. Methods of recruitment of the alkalinity titer are given in U.S. Patents 3,262,835, 3,294,490, 3,396,074, 3,271,235 and 3,231,461, as well as in other patents.

The polyvinyl butyral resin is plasticizer with about 20 to 30 parts, and for normal use in windshields more commonly, plasticized with 30 to 50 parts of plasticizer per 100 parts of resin. This latter concentration becomes im generally for polyvinyl butyral resins, which is 18 to 23 percent by weight Contain vinyl alcohol. In general, the plasticizers commonly used are esters polybasic acid or a polyhydric alcohol. Triethylene glycol di (2-ethyl butyrate) and dibutyl sebacate are particularly suitable and di - (/ 3-butoxyethy 1) adipate. The resulting plasticized resin mixture is then generally in shape extruded from foils, which are then printed as described below.

The thickness of the for the production of the composite film according to the invention The individual foils made of polyvinyl butyral used for laminated safety glass are in the range of 0.0508 mm

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to 1.524 mm (2 to 50 mils), and for use in automotive windshields, in the preferred range of 0.127 to 0.762 mm (5 to 30 mils). The choice of the thickness of the individual foils ultimately depends on that desired in the composite foil Dependent on thickness, and those skilled in the art can easily select films of suitable thickness for any given application.

In one embodiment of the present invention, the surface of the film to be printed is that which is finally coated Contact with another polyvinyl butyral sheet will be relatively smooth so as to provide a better surface for to form the pressure. On the other hand, the surface of the polyvinyl butyral film, which is ultimately with the glass part of the laminated safety glass will be in contact, preferably have a usual rough surface in order to stand still to prevent the drawn foils and to facilitate the ventilation of the composite. The surfaces mentioned above are well known in the art and need no further discussion here.

The techniques for tinting interlayer material for automobile windshields are typically designed to provide a to give graded coloring. In the process of printing a graduated coloration, the color is printed in a pattern such that that at the top of the intermediate layer there is a dark

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step gives, which gradually and evenly into one uncolored, lower section e'er intermediate layer passes. In the resulting connected. The dark section is at the top of the windshield. the windshield. In car windshields the darkest part of the graduated coloration usually has an optical density in the range of 1.70 ois 0.70, which corresponds to a light transmission of 2 to 20%. the Light transmission in the darkest part of the graduated coloration is preferably 4 to 10%.

The present invention is also applicable to printing those polyvinyl butyral films which do not require graded coloring. These are usually not used for windshields, but for those applications where the foils are evenly colored are.

With reference to the drawings, FIG. V explains an embodiment of the present invention where molten polyvinyl butyral is applied to a printed surface of a sheet of polyvinyl butyral is extruded. In Figure V, the polyvinyloutyral sheet material 50 via a deflection roller 51 through a printing station 52 where one side of the film is printed. The printed film is then passed over a series of drive rollers 53 and idler rollers 51 to a terminal point, which is from the outlet of the

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Extruder 56 and a forming roll 57 is formed where molten Polyvinyl butyral on the printed surface of the polyvinyl butyral film is extruded. The resulting composite is a forming roll 57, a stripping roll 54, "a take-off roll 55 and a Deflection roller 51 passed to a winder 58. The resulting Composite with graduated coloring is then taken to storage or shipping.

Referring again to Figure V, the polyvinyl butyral sheet material can also be fed to the printing station directly from the extruder or from another film production device, thus eliminating the need to wind and unwind the film material before it is fed to the printing station.

Figure VI illustrates a film combining operation in which two 0.381 mm (15 mil) films of polyvinyl butyral can be combined to form a 0.762 mm (30 mil) composite with a graduated shade of color on the inner surface. The first film 60 is bright, clear material with usual surfaces on both sides, while the second film 61 is on one side is printed with a graduated color which is used in the resulting sheet material at the top of the windshield appear as the printed ribbon. The printed side is preferably relatively smooth, while the The opposite side of the film has a conventional, rough surface.

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The light-colored film 50 passes through the upper tension rollers 62 into the upper compartment of the combining unit. These idler rollers serve two purposes: (1) they act as a positive drive leg of constant speed; (2) They will be using lower line speeds than the combining rollers 65 driven so that a desired amount of film tension and Stretching is given in the clear film 50 to prevent cross-machine wrinkles and curling or curling underneath To keep control. This film tension is necessary for elimination wrinkles in the combined film due to the growth of the film during heating and the sizing of the stretching in the upper clear film 60 versus the lower printed film 61. The stretching is usually done by measuring the change in width determined by the film. If the stretch in the top slide doesn't match that in the bottom slide, it will The finished product has excessive corrugation. The upper tension rollers run 1 to 30% slower than the combining rolls 65, with 4 to 16% being typical values.

The clear film 50 then passes under a bank of electric infrared preheaters, which the temperature of the incoming Adjusts the slide to a range from 21 to 82c. The preferred one, using an infrared pyrometer just after the arc-shaped flexible rollers 53 measured temperature is 43

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up to 71 ° C. After preheating, the film runs over a flexible, curved roller 63 (Mt. Hope Vari-ßow Roll), which serves to spread the film in the transverse direction to the direction of travel, so eliminate any wrinkles that may have formed due to film growth during heating.

The clear film 60 is then carried to the top turning roll 64 which transfers the film to the top combining rolls 65. The folding roller 64 is depending on the particular film used, as well as other working conditions, at any pressure ranging from a nip pressure of zero (nip open) to a nip pressure of 2.95 kg / cm is enough, operated. The clear film 50 envelops the Combining roller 65 from 15 to 154 until it reaches the combining nip 63 reached. The combining rollers are set to 32 to 82 C, preferably heated to 43 to 71 ° C. The Kombinierklemrastellen pressure is 1.48 to 8.85 kg / cm and preferably 2.95 to 5.90 kg / cm. The surface of the upper combining roll 65 is slightly less sticky than the surface of the lower combining roll 65 to facilitate the transfer of the film to the lower roller.

The polyvinyl butyral film printed with the gradual color shade generally occurs at a temperature of

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21 to 49 C under 10 to 35% stretching by the lower relaxation roller pair 66 in the system section. The film is allowed to move between the pair of slack rollers 65 and the to relax the lower tension roller pair 62 by letting the lower tension roller pair run 3 to 20% slower than that Relaxation roller pair. The printed film 61 goes through the lower tension rollers 62, which run at a web speed that is the same or a little smaller than that of the combining rollers and preferably of the same size as that of the clear film web 60. The lower tension rollers serve the same purpose as the upper tension rollers; namely, they form one in the machine direction Film tension to prevent cross-directional wrinkles and to keep curling under control. The tension roller speed is 1 to 30% less than the combining roll speed, with 4 to 16% less being preferred will.

The foil, which is printed with a graduated color shade, then runs through electrical infrared preheaters, which are set in this way are to give the same temperature as the temperature reached in the upper compartment. The printed film is then through the lower turning roller 64 is transferred to the lower combining roller 65. The film wraps the lower combining roll 65, which is on the same Temperature is heated like the upper combining roller, to about 15 to 154 °.

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After passing through the Korabxnxerklenunsfcelle 69, the combined film (0.762 mm) transferred to a chill roll S7, which includes them with 15 to 154. The surface of the chill roll is usually kept below 21 C. After leaving that Cooling roller 67, the film is wound up and packaged.

While FIG. VI focuses on the combination of two 0.381 mm foils refers to a composite foil of 0.752 mm it can be seen that other film thicknesses have been applied will be able to. There are also wide variations in the film surfaces and film composition »as well as the printing of the Foils allowed. As for the oppression, either or both Foils can be printed with any desired pattern, design or color.

One of the main problems with film composition is wrinkling of the film in the machine and cross directions. These wrinkles are caused by film growth on the combining rolls while heating on the rollers and through from the surface The vapors emitted by the rollers, which are trapped between the film and the roller surface behind the nip of the Korabinierwalzen. are caused.

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The doreii caused the foil to grow during heating Wrinkling can be prevented by limiting the temperature rise Eggs slide on the comining roller by less than 17 ° C Control is held by the slide before going to the combining roller arrives, is preheated or by introducing stretching in the 3aimalauf direction and transverse direction of the film before the Combined orphans reached. The film will grow on the combining rollers by preheating to within 11 C of the film packaging temperature reduced to a size that does not cause wrinkles more is sufficient »A combination of both methods is preferred.

External should be the tensions in the web running direction and Cross direction, the temperature and running speed of the too combining foils should be coordinated as precisely as possible.

FIG. VIT illustrates a film combining method similar to that of FIG. VI, with the exception that different control means are arranged for the tension, the loop sag and the temperature. These process control means are designed to adjust the tension, temperature and running speed of the film webs to be combined in order to achieve optimum properties in the resulting composite ply layer.

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The clear film 80 passes through a first upper pair of tension rollers 82 into the upper compartment of the combining compartment. -This The pair of tension rollers regulates the film tension through the preconditioning heater and wrinkle removal stage comprehensive conditioning compartment through where the film is made wrinkle-free using conventional means. The film tension is carried out in the preconditioning section kept at a minimum level by a first upper tension sensor 83.

A first upper temperature sensor 84 regulates the preconditioning heart, in order to obtain a film temperature in the range of 32 to 82 ° C, preferably 43 to 71 ° C.

The clear film then runs through a second upper pair of tensioning rollers 85 into a relaxation compartment, where the film is allowed to pass between the second upper tension roller pair 85 and the third upper tension roller pair 88 as controlled parabolic Sagging loop. The tension roller pairs S5 and 88 regulate the tension and the parabolic loop in the relaxation compartment. The speed of these tension rollers formed by the tension roller pairs 85 and 80 is controlled by the loop sensor 86. The loop of the film web is held in the detachment compartment, in order to remove as much as possible of the tension inherent in the film, so that the clear film which is in this compartment

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occurs with a degree of shrinkage of 4 to 24%, this with a Shrinkage degree of less than 4% leaves. A temperature sensor 87 is also arranged in the relaxation compartment.

The third upper tension roller pair 88 regulates the tension through the polishing stretching compartment by degrees of stretching in the area from 1 to 30%, preferably 4 to 15%. This pair of rollers is controlled by a second upper tension detector 89,

After the relaxation compartment, the film runs through a heating compartment, where the film temperature is again in the range from 32 to 82 C, preferably 43 to 71 C, is set.

The clear film 80 then runs over a folding roller 90 onto a temperature control roller 91 in order to bring the film temperature to the set the desired combiner temperature. The temperature of the film is measured just before combining and by a third temperature sensor 93, which is arranged just in front of the combination clamping point 94, controlled. After leaving the temperature control roller 91, the clear film 80 runs over an upper flexible, curved roller 92 for the removal of creases and then into the combination nip 94.

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In the meantime, a polyvinyl butyral sheet 81, which had been printed with a graduated color in the lower section of the foil combination compartment, which is in the is essentially the same as that described above.

The printed film passes through a first lower pair of tensioning rollers 35 and then through the Vorkondxtionierungserhxtzer and wrinkle removal stage having Vorkondxtionierungsabtexl through into the lower compartment of the combining compartment. This compartment may be unnecessary in a rowing mode where the foil Conditioned to a certain temperature and made wrinkle-free just before printing and then directly into the combination compartment to be led. In the preconditioning area there is also a first lower tension sensor '^ 6 and a first one lower temperature sensor 97. The printed film S1 then runs through a second lower pair of tensioning rollers 98 and third lower tension roller pair 101 formed relaxation compartment. In the relaxation compartment, the slide is allowed to act as a parabolic Loop where a lower loop sensor 99 and a second temperature sensor 100 determine the sag and temperature measure the foil.

After leaving the third lower tension roller pair 101, the film runs in a similar manner as described above

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Preheating compartment. The foil preheated as in the upper * compartment runs over a folding roller 103 onto a lower temperature control roller 104 and then a lower flexible, curved roller 105 into the combining roller pair 94. A third lower temperature sensor 106 is between the flexible, curved roller 105 and the combination nip 94 arranged.

Referring again to Figure VII, there is a regulating stage 109 intended to record the data on voltage, temperature and loop sag through the sensors in the upper and lower Section, and to set these variables so that the voltage, the temperature and the degree of relaxation in the loop are adapted for the upper and lower sections, so that the composite is optimal Properties are created.

At the combination clamping point 94, the clear film 80 is press-bonded to the graduated tinted film 81 to form a composite to form where the printed area is on the inner layer of the two foils.

After the combination, the composite film 108 runs over a series of cooling rollers 107, which reduce the film temperature to less than 27 ° C and preferably to less than 21 ° C. The composite film is then wound up and ready for storage or shipping brought.

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The roller speeds and nip pressures used in connection with the method explained in FIG. VII and temperatures are the same as those of the process illustrated by Figure VI unless otherwise specified.

The above description of Figure VII indicates upper and lower sections or compartments. However, it is understandable that the operation can also be carried out side by side, in which case the upper and lower compartments in the system to the right and left, or to the first and second parts of the Be plant.

Using the above procedure it is also possible to combine two printed foils.

In the case of three-layer composite films, using of modifications of the method outlined above, the middle layer is also printed on both sides and then between two clear foils must be inserted. Other modifications will become apparent to those skilled in the art upon reading this specification.

The heating steps mentioned throughout the description can be carried out by any means known in the art. The foils can go through any

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the numerous known means, which include electric heaters, infrared heaters, hot air devices, steam-heated devices, include hot water hexed devices, etc., are heated. Conversely, for each cooling step, which to adjust the film temperature is necessary, conventional means such as cold air, cooling roller ^ etc. can be used. In the same Thus, the degree of wrapping around any given roll can vary within wide limits.

The composite layers according to the invention are press-bonded, by a bond strength measured by a 130 degree egg tearing test of at least 0.295 kg / cm. The bond should be sufficient to maintain the uniform nature of the composite film during the Shipping, storage, handling and fabrication to laminated Keep safety glass upright. During layering of the glass The heat and pressure used to produce the laminate also serve to increase the bond strength of the interlayer.

The composite film preferably has a curl value of less than 20. The curl value is measured by cutting a sample of approximately 503 χ 2 cm in the direction of travel of the film web. The sample is then placed in an oven with air circulation for 10 minutes . kept at 43 + _ 1 C »In the oven, half of the sample is taken from a

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flat shield, while the other half hangs down unsupported. The sample is then removed from the oven after 10 minutes and placed on a flat table such that the sheet of film that was supported in the oven is on the table below. The sample is tested and if the ends of the sample curve away from the table surface, the distance from the sample end to the point that is still in contact with the table is measured in millimeters. The measurements at each end of the sample are averaged and the percentage of curling is determined using the following formula s mm rolled film / original length (mm) χ 100 = % curl.

A curl value greater than 20% means that there are remaining tensions in the film, which are caused by this cause the film to curl, causing processing difficulties in the glass coating. the Composite film preferably has a curl value of less than 15% and in particular less than 10%.

A manufactured according to the method explained by FIG. VI, graduated colored composite film with a bond strength of 0.295 kg / cm and a curl value of 3% between two panes of glass, such as those used in the manufacture of car windshields commonly used are inserted.

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The resulting laminated safety glass is optically Density, film beauty and adhesion evaluated and compared to a laminated glass made using a single layer 0.732 mm polyvinyl butyral intermediate layer by customary methods was made. The properties of using the inventive. Laminated glass panes made of composite interlayer are comparable to those made using conventional single layer polyvinyl butyral double layers. were manufactured.

Can be directed to composite interlayers of polyvinyl butyral While the foregoing description, one skilled in the art will readily recognize that the present invention is readily adapted for making composite sheet ·! made of other thermoplastic materials that could be used as intermediate layers for laminated safety glass. Examples of other suitable interlayer materials are polyurethanes, polyamides, poly (ethylene-vinyl acetate), poly (ethylene-vinyl alcohol), etc.

From the foregoing description of the present invention it will be apparent that many variations and modifications are possible without departing from the spirit and scope of this invention to leave.

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Claims (1)

Claims l \ Polyvinyl butyral interlayer for laminated safety glass, the polyvinyl butyral interlayer has at least two interconnected foils made of polyvinyl butyral, characterized in that at least part of one of the polyvinyl butyral poles on one in direct contact with the other side of polyvinyl butyral is printed with a color. 2. intermediate layer according to claim 1, characterized in that. that at least one side of one of the polyvinyl butyral films is printed with a graduated coloration. 3. intermediate layer according to claim 1, characterized in that the entire thickness of the connected intermediate layer in the Range is from 0.0051 to 0.191 cm. ² K process for the production of a composite, graded polyvinyl butyral intermediate layer for laminated safety glass, characterized in that a layer of molten polyvinyl butyral is applied to the surface of a 409845/0887 moving fabric extruded from polyvinyl butyral, which was previously printed with a graduated color. 5. Method of making a composite polyvinyl butyral interlayer for laminated safety glass, characterized in that one a) a first continuous sheet of thermoplastic Material passes between pinch rolls to adjust the machine direction, film tension and stretching of the film granted; b) adjusting the temperature of the film to a range from 38 to 65 ° C; c) removed all wrinkles from the film and then d) the first continuous film is combined with at least one further continuous film, with at least one of the other continuous foils is printed and each additional foil is practically on the treated in the same way as in steps a) to c) - 25 409845/088? has been and
e) the composite material obtained is cooled. 6. The method according to claim 5, characterized in that at least one additional continuous film made of polyvinyl butyral has been printed with a graduated color on both sides and between two other films made of polyvinyl butyral are combined by passing the films through a joining gap with the temperature, tension and speed of each of the foils prior to entering the union gap is essentially the same, 409845/0887 ι ^H ■ Blank page