DE2324631A1 - IMPACT-RESISTANT LIGHT TRANSLUCENT LAMINATE, ESPECIALLY LAMINATED GLASS - Google Patents

Description

The Sierracin Corporation, incorporated under the laws of the State of California, 12780 San Fernando Road, Sylmar . California 91342 (V.St.A.)

Impact resistant translucent laminate, especially laminated glass

It has been safety windshields and for years Other vehicle windows are known to have a film of polyvinyl butyral as a layer between them Glass panes or other solid sheets contain, to some extent the layer of polyvinyl butyral degrades the consequences of an accident due to the impact of occupants in vehicle collisions, namely because of the so-called. "Ability to catch the head". The US safety regulations for motor vehicles require that the windshields of the vehicles under standard test impact a head shape a "Severity Index" (measure of the severity of the injury) of less than 1000 have. The Severity Index ie.t in this

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iD 2800 BREMEN 1

EDUARD-QRUNOW-STHAS8E 27

TELEPHONE (0421) * 7 20 48

Relationship a measure of the braking forces that the Head shape when impacting a windshield part is experienced and used by the automotive industry related to the likelihood of concussion.

The common safety glass windscreens comply with the provisions of the Severity Index but nevertheless become the cause of serious injuries in various ways. For example, a flying one Object that is on the outer or "outboard" pane of glass a common safety glass windshield, splintering the inboard or "inboard" glass cause, so that the vehicle occupants are obviously endangered. In a car crash the impact of occupants against the inner pane of glass if it leads to breakage of the pane, usually accompanied by cuts and occasionally leads to disaster, i.e. puncture through the windshield. Recent studies of the splinter problem have led to the proposal that Reinforce the outboard pane of automobile windshields relative to the inner panes; see e.g. the U.S. Patent 3,282,772 to David. During this Patent reduces the fragmentation effect to a certain extent in the event of an external impact, it has the opposite Effect in the event of an internal impact, e.g. of the heads of vehicle occupants. The thicker outer pane reduces the area of the outer pane that breaks in the event of an internal impact, thereby reducing to a certain extent Dimensions of the area of the intermediate layer is reduced, which is available for energy absorption in the event of such an impact. This allows the Severity Index can be increased unnecessarily. In addition, the truth

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likelihood of cuts occurring if the inner glass pane is broken in the internal impact of an occupant's head.

It has also been proposed to have vehicle windows through Metal coating of certain plastic films in a vacuum process and subsequent installation of the metal-coated films in the Construction of a safety glass windshield with one or more common polyvinyl butyral interlayer films To make it electrically heatable: see, for example, U.S. Patent 3,310,458 to Mattimoe. In general Metallizable films have a greater tensile strength than the interlayer films with which together they are used. For this and other reasons, the use of metal-coated films some mechanical effects on the finished windshield. However, these include known constructions likewise an inboard pane made of glass or another rigid, fragile material, and can therefore still shatter in the event of an external impact and cut injuries in the event of an internal impact cause. The need for a vehicle window that is free of these weaknesses without a suitable classification in the Severity Index is lost, has not been satisfied by this day.

The translucent laminates of the present invention include in the order from a first to a second surface a * sheet of glass or plastic (e.g. made of polymethyl methacrylate or polycarbonate), an interlayer film and an unbreakable one Film, its coated or uncoated, the interlayer film not facing surface with the second

• rigid

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Surface collapses.

The features and advantages of the invention will become apparent from the following description of the preferred embodiments and from the accompanying drawings. It demonstrate:

1 shows the representation of a connected curved safety glass windshield;

Fig. 2 is a partial cross-section of a

first embodiment of the invention assembled in layers; and

3 is a partial cross-section of a joined curved laminate according to FIG a second embodiment according to the invention.

The interlayer film of common safety glass windshields as in Fig. 1 is usually between several associated panes of glass, for example the outboard pane 10 and the inboard window 11, with the inboard window facing the occupants and is one of the security risks described above. The glass panes that belong together are usually "countersunk", i.e. two Glass blanks are supported on top of each other at the edges and heated to such an extent that the weight of the Discs causes the discs to deflect to the desired extent. A common byproduct of the Forming process is the multiple curvature, i.e. the Slices are curved around two orthogonal axes at least in some of their sections. That kind of curvature is to be distinguished from a simple curvature around an axis, such as is the case with a cylinder. These concave curvature in the interior of the vehicle

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It is apparent from Figure 1 and is hereinafter referred to as "compound curvature. ¹¹ composite Curved called glass panes for automotive windshields can also be prepared by pressing between heated glass plates mold jaws or compression molding.

FIG. 2 shows a partial cross section of a windshield constructed according to the invention. This embodiment of a translucent laminate has a first outer surface 12 and a second outer surface and comprises in sequence from face 12 to face 13 a rigid disc 14, e.g. or tempered soda lime glass, an interlayer film 15 and an unbreakable film 16.

Correspondingly, FIG. 3 shows an electrically heatable embodiment of a windshield according to the invention. This embodiment also comprises an outboard glass pane 17 and an intermediate plastic layer. An unbreakable film 19 lies on the inner surface of the composite-curved laminate. A thin, translucent and electrically conductive layer 20 lies between the intermediate layer 18 and the unbreakable film 19. By resistively heating the conductive The windshield is de-iced or freed from condensate. The power connection of the electrical Conductive coating can be done via power connection rails (not shown), e.g. during a preceding processing step in the layering of the intermediate layer and the unbreakable film along the edges of the electrically conductive layer. Suitable connecting rails are the subject U.S. Patent 3,612,745 to Warren, incorporated herein by reference.

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As used herein, the term "interlayer film" refers to a film or layer of translucent material with flow properties which optionally allow structuring of the outer surface of the film for degassing during subsequent laminate formation by heat and pressure and sufficient adhesion to the rigid glass and plastic panes allow the invention to maintain the cohesion of the laminate even in the event of a severe impact. The intermediate layers used according to the invention have a limit elongation of over 150 % and a tensile strength of less than

2 2

475 kp / cm, preferably less than 352 kp / cm, measured according to the standard test method ASTM D 412-68 of the American Society for Testing Material, Philadelphia, Pennsylvania. If the stretch is too small, it may be due to If the layer breaks, the ability of the laminate to restrain an occupant's head in the event of an impact is significant be reduced. If the tensile strength is too great, the Severity Index and accordingly that The risk of concussions for the vehicle occupants will increase significantly.

Typical materials for the interlayer include films of polyurethane, polyvinyl butyral, polyvinyl acetal, and polyvinyl chloride, usually about 0.127 mm to 1.52 mm thick, and preferably 0.762 mm. More than 1.52 mm in thickness is too costly and can raise manufacturing problems. A thickness of less than 0.127 mm is difficult to manufacture and can be too thin for the surface structuring. The interlayer material is usually, but not necessarily, plasticized with conventional plasticizers such as dioctyl phthalate, tricresol phosphate, dibutyl phthalate, dibutyl sebacate (DBS), Tri-Address: 1916 Race Street, Philadelphia 309848/0965

7324R31

ethylene glycol di- (2-ethyl-butyrate) which is known under the name 3GH, as well as with other common alkyl phthalate or alkyl ester plasticizers. For example, polyvinyl butyral, which at 21 percent by weight 3GH is plastic

2 is adorned, a tensile strength of 328 kp / cm and a limit elongation of 200 %. Polyvinyl butyral plasticized with 37.5 percent by weight DBS has a tensile strength of 214 kgf / cm and a limit elongation of 250 %. Suitable polyurethane compounds have a

2 2

Tensile strength between 316 kp / cm and 457 kp / cm and a limit elongation between 400% and 480%. Plasticized PVC compounds have a tensile strength between 98.4

2
kg / cm and 394 kg / cm

150 % and 500% up.

2 2

kp / cm and 394 kp / cm and a limit strain between

Intermediate layers on polyvinyl butyral besis are preferably used in the impact-resistant laminate. This Material allows the surface to be roughened prior to laroinization so that the composite laminate can be degassed during manufacture. The surface roughness disappears due to the heating and pressure during lamination, so that the finished laminate is very is translucent and has excellent optical properties. Polyvinyl butyral also has a great adhesion to glass and the plastic materials used for the unbreakable film. The available Manufacturing processes and equipment for the lamination of common safety glass are well suited for use with laminates containing polyvinyl butyral.

A thickness of the intermediate layer of about 0.762 mm is excellent for the high-impact laminate, since

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with this thickness connecting bars for an electrically heated embodiment are suitably embedded without creating unnecessary tension in the glass pane, which could lead to premature breakage. In a laminate with or without electrical heating, this layer thickness has excellent properties for catching the head. a windshield without an unnecessarily high severity index.

As used herein, the term "unbreakable film" refers to a plastic material that is thinner Layer has sufficient strength to make the 'laminate give great impact resistance and yet has sufficient extensibility to avoid shattering. A windshield made of such a laminate is highly effective in catching of the head, and cuts in the impact of occupants are significantly reduced, if not completely eliminated. A certain flexibility is necessary in order to avoid a high severity index.

The typical materials for the unbreakable film preferably have an ultimate elongation of less than

2 about 150 % and a tensile strength in excess of 352 kgf / cm, each parameter being defined in accordance with ASTM D 412-68. These limits are not absolutely binding in every case, as can be seen from the suitability of fluorinated ethylene-propylene copolymers that allow elongation

2 of 300% and a tensile strength between 176 kp / cm and 211 kp / cm, and polytetrafluoroethylene, which has an extensibility between 100 and 350 % and

2 a tensile strength between about 105 kp / cm and 281 kp /

2
cm. These materials can do something

thicker films are needed compared to other 309848/0965

suitable unbreakable films.

If the impact-resistant laminate is as in the embodiment 3 comprises an electrically conductive layer, the unbreakable film is the support on which preferably such a layer is applied prior to the assembly of the laminate. In this case it should Material for the unbreakable film is the vacuum evaporation process withstand, i.e. its heat distortion temperature should be above 49 ° C and preferably above 66 ° C lie. The material for the unbreakable film should be be relatively free of plasticizers so that it does not degas in a vacuum chamber. The material should also be sufficiently dimensionally stable in order to destroy the electrical connection of the carried by it Layer in the handling of the film and in the temperature treatment during the formation of the impact-resistant laminate and also to be avoided if heated during use.

The thickness of the unbreakable film can be between about 25.4 Jt and 254a , preferably between about 76.2 / t and 152.4 U,. A thickness of less than 25.4 m is too small for good head-catching properties and energy absorption, and a thickness of more than 254 μ can unnecessarily increase the severity index of the laminate. The energy absorption properties of the material used in the laminate are important for reducing the consequences of a head impact in a vehicle accident and decrease with increasing thickness. Furthermore, the plastics materials must have flexibility so that the protective layers can accommodate the composite curvature of the rigid layers used in windshields. A suitable measure of flexibility is also

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in those embodiments of concern where the unbreakable layer is vacuum metallized. The flexibility decreases with increasing thickness. A maximum thickness of the unbreakable film about 2 μ of 54 has proved to be a practical upper limit for most purposes ,, based on a balance between all of the above aspects.

A layer of polyethylene terephthalate with a thickness of about 76 _r 2u to 152.4 / i represents a preferred unbreakable film from essentially all points of view. Energy absorption and the severity index without the risk of shattering the film with the consequent possibility of cuts. As the film is thicker than about 152.4 tu , it becomes increasingly difficult to match the film to the composite curvature of a windshield because the thicker material is more difficult to stretch.

Suitable materials are shown in the table below listed for the unbreakable film, as well as the .Limit elongation and the tensile strength with which it are currently available.

"Tensile strength" is in the table as well as in the frame

the rest of the description mainly the resistance to deformation or the flexural strength against the effects of pressure to understand. In the table, the unit "p.s.i."

2 in the physical system of measurement about 0.0703 kg / cm.

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TABEL

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Unbreakable film Extensibility 70 tensile strenght
(psi) 16,400 Cellulose acetate 15 - 40 8,000 - 16,000 Cellulose triacetate 10 - 100 9,000 - 9,000 Cellulose acetate butyrate 50 - 80 5,000 - 5,000 Cellulose propionate 60 - 30th 4,000 - 10,000 Ethyl cellulose 20 - 12th 8,000 - 8,800 Polymethyl methacrylate 4 - 8,200 -

(injection-molded, biaxially stretched) Polytrifluorochloroethylene copolymer
Polyvinyl fluoride polycarbonate

Polypropylene (biaxially oriented)

Polymethyl methacrylate (Type A injected)

Polymethyl methacrylate (type B injection molded), polyethylene terephthalate polyester
Vinylidene chloride vinyl chloride copolymer polyvinyl chloride

(Poured liquid, not plasti

Vinyl chloride acetate copolymer (not plasticized)

regenerated cellulose

50-150

5,000 - 10,000

115 - 250 7,000 - 18,000 85 - 10 5 8,400 - 8,800 50 - 200 12,000 - 33,000 75 5, 100 12th 7,800 60 - 165 20,000 - 35,000 35 - 8,000 - 20,000 adorns '. 100
) 6,000 - 9,000 3 - 100 5,500 - 8,000 10 - 50 7,000 - 18,000

In the embodiment according to Finur 3, the electrical conductive coating 20 made of one of various metals such as gold, silver or copper, the has been applied in the usual way by vacuum vapor deposition or sputtering. The metal coating is like this

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thin so that it is translucent, and is preferably so thick that its resistivity is of the order of magnitude from about 2 to 100 ohms per FE. The term "translucent" refers to the property of a material or structure to transmit visible light without substantial scattering, so that the otherworldly objects can be clearly recognized. Preferably, the material is selected so that the invention Layered windows let through at least 70% of the incident light.

The exposed, not facing the intermediate layer surface of the film unbreakable film can optionally an abrasion resistant coating 21 a thickness of wear of about 1.25 to 7.62 u *. Various chemically formed organosilicon layers are suitable. Other transparent coatings that are resistant to mechanical and chemical effects can be applied by vacuum vapor deposition, atomization or the like. Optionally, the abrasion-resistant layer can be made of translucent plastics, alkyd, phenol-formaldehyde and melamine-formaldehyde resins, and various polyesters. The task of such a coating is to protect the carrier film from physical damage which, through scratching or chemical action, would reduce its transparency.

The plastic films are joined to the rigid plate under elevated temperature and pressure. So can e.g. a rigid glass plate, a plastic interlayer film and an unbreakable plastic film placed on top of one another will. These plastic layers are then made by a substantially rigid, possibly the curvature

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the part corresponding to the glass pane is pressed against the rigid pane. Elevated temperature and pressure, e.g. before. 14.1 kp / cm or 125 ° C, leave the interlayer material Adhere firmly to the unbreakable film and to the glass pane. For gluing the rigid and plastic layers, hydrostatic lamination techniques similar to those currently in use may also be suitable Techniques for bonding interlayer films between rigid sheets of glass in manufacturing of safety glass are analogous.

In an impact test carried out in the usual way by a large automobile manufacturer with a safety gear at a speed of about 48 km / h, four common car windshields with two panes of 0.3? cm thickness, between which an intermediate layer of 0.076 cm thick polyvinyl butyral was enclosed, compared with two windshields according to the invention. The latter consisted of a log from the outboard to the inboard surface. Float glas (float glass), an interlayer film made of polyvinyl butyral with a thickness of G, 381 mm, 0.762 mm and 1.143 mm for the various windshields and with a 0.127 mm thick unbreakable film made of polyethylene terephthalate polyester, the surface of which is adjacent to the interlayer film was provided with a translucent, vacuum-deposited metal layer, while the opposite or outer surface of the unbreakable film was provided with a polysiloxane coating of about 2.54 microns thick. All windshields were tested using standard windshield evaluation procedures. These methods are described in the "Proceedings of the Stapp Car Crash Conferences" _f published by

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the "Society of Automotive Engineers". The procedure includes a simulated collision at 48 km / h speed, with a human-like "dummy" manikin sitting in front of the test windshield. A double A layer of wet chamois leather on the head of the "dummy" doll is used to evaluate the cutting effect as a result the impact of the head shape on the windshield.

In the case of the windshields according to the invention, the wet chamois blanket on the "dummy" head shape at all not cut, and in no case was the unbreakable polyester film punctured. The severity Index was satisfactory on all windshields. When the usual windshields occurred, however in any case cuts.

In another test procedure, heavy stones were hit against the outboard glass pane of an inventive flat laminate of glass, intermediate layer and unbreakable film thrown with sufficient energy, to shatter the inboard window of a standard car windshield. The glass was in high Dimensions broken and the unbreakable film on the inside of the specimen bowed inward. Yet you could rub your hand over the film without any consequences, and of course no splintering was observed on the inboard side.

It should be emphasized that in such a. Testing demonstrated very desirable properties without sacrificing an acceptable severity index value can be achieved, despite the sharp divergence of the present Invention of what was heretofore common in the manufacture of "safety" windshields and corresponding windows was common.

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Overall, a translucent laminate has been described that can be used, for example, for vehicle windows, and that in turn a sheet of glass or other rigid sheet, for example made of polyvinyl butyral Interlayer film and an e.g. eus polyethylene terephthalate polyester existing unbreakable film, the one not facing the interlayer film Surface of the unbreakable film coincides with an outer surface of the laminate. This outer surface may further comprise a thin layer, which physical or chemical destructive effects on prevents the unbreakable film. The unbreakable film can optionally be overlaid on top of the interlayer film facing surface an electrically conductive coating wear.

Numerous modifications and ab-, Changes to the present invention are obvious. Even though the invention described with particular emphasis on its use for car windshields with composite curvature it is evident that according to the invention built-up laminates are well suited for other applications in transportation and construction everywhere are where shock and splinter resistance or avoidance of cuts are important considerations. These or other uses of the invention remain in Framework of the invention.

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Claims (12)

Claims 1. Impact-resistant, translucent laminate, especially laminated glass for vehicle windows, marked by a rigid disc (14, IV) serving as the outer front (10), and by one serving as the inner front (11) unbreakable plastic film (16, 19) with high resistance to deformation, and with a rigid one Disc and intermediate layer (15, 18) glued to the unbreakable film, the elasticity of which is greater than the stretchability of the unbreakable film. 2. Laminate according to claim 1, characterized in that the deformation resistance of the intermediate layer is less than the resistance to deformation of the unbreakable film. 3. Laminate according to one of the preceding claims, characterized in that the deformation resistance the intermediate layer is less than about 457 kg / cm ^ (6500 p.s.i., ' and that the resistance to deformation of the plastic film 2
is greater than about 352 kp / cm (500 psi '). 4. Laminate according to one of the preceding claims, thereby characterized in that the extensibility limit of the intermediate layer is greater than 150% and the extensibility arenas of the plastic film is less than 150%. 5. Laminate according to one of the preceding claims, characterized characterized in that the intermediate layer consists of translucent plastic. 309848/0965 7324631 6. Laminate according to one of the preceding claims, characterized in that the layer thickness of the Intermediate layer is approximately in the range from 0.127 mm to 1.52 mm. 7. Laminate according to one of the preceding claims, characterized in that the layer thickness of the unbreakable Film is approximately in the range of 0.0254 mm to 0.254 mm. 8. Laminate according to one of the preceding claims, characterized in that the unbreakable film is a PolyMthyl enterephthalate / polyester film with one layer thickness is approximately between 0.0762 mm and 0.152 mm. 9. Laminate according to one of the preceding claims, characterized in that the interlayer film is a Layer of polyvinyl butyral about 0.762 mm. 10. Laminate according to one of the preceding claims, characterized by an abrasion-resistant and chemically resistant film (21) on the intermediate layer facing surface of the unbreakable film. 11. Laminate according to one of the preceding claims, characterized in that a translucent, electrically conductive film (20) lies between the unbreakable film and the intermediate layer. 12. Laminate according to one of the preceding claims, characterized in that the rigid outer front panel is curved with the convex surface outwards and that the unbreakable film is on the concave surface. 309848/0965 Blank page