JPS5948775B2 - glass sheet assembly - Google Patents

Description

[Detailed description of the invention] The present invention relates to safety glass windows.

More specifically, the present invention provides a transparent layer of plastic material on at least one side that prevents direct contact between the human body and the edge of the glass piece even if the human body collides with a force that shatters the glass sheet. The present invention relates to a glass window including a coated glass sheet, particularly a glass window for an automobile windshield. Even if the driver's head collides with the windshield with great force, the glass is deformed to absorb as much of the impact energy as possible so that the glass does not break through and the impact is cushioned. Various attempts have been made to develop windshield glass for automobiles.

So far, requirements such as those described above have been met only by laminated windshields. However, even if the windshield was not shattered through, there was still a risk of lacerations caused by the edges of the glass fragments. For this reason, various methods have been proposed in which the inner surface of the glass is coated with a protective coating of plastic material to avoid contact between the skin and the glass pieces. In one example of a known glass, the plastic material layer is a 0.311 thick amorphous polyamide sheet.

Other examples include applying sheets of polycarbonate, polyacrylate, cellulose acetate, polyester, polyvinyl chloride, or other plastic materials to the inside surface (the side facing the driver) of a hardened glass sheet. Although such known glasses are certainly effective in preventing scratches, the proposed plastic materials forming the coating layer are universally insufficiently resistant to scratching under the conditions of use. be.

Therefore, there was a need to further protect these coated layers with another durable coating. Another disadvantage of these known glasses is that, in the case of the proposed plastic materials, they have only a slight deformation capacity in the case of customary thicknesses, which leads to a reduction in safety.

However, in the second type of known glass mentioned above, this point can be reversed and the edge of the plastic sheet is not inserted into the frame of the window glass, or at least a part of the edge can detach from the frame. The structure is such that the two can be separated in the event of a collision. The present invention has a laminated structure in which an energy-absorbing plastic layer is interposed between an inner glass sheet and an outer glass sheet, and an elastic plastic layer is adhered to the inner surface of the laminated structure. transparent safety glass, which has the ability to absorb the energy of an object striking the safety glass by substantial plastic deformation that occurs upon impact, and has the ability to protect against lacerations caused by broken glass; The elastic plastic layer applied to the inner surface is transparent, tear-resistant, large and self-righting;
exhibiting sufficient elastic deformation to protect against lacerations from broken glass through substantial plastic deformation of the safety glass without substantially inhibiting the energy absorption of the energy-absorbing plastic and without rupturing itself; The Young's modulus of the plastic layer is 2.0X109dyn/
d or less, the elongation at break is 60% or more, the plastic deformation rate relative to the elongation at break is 2% or less, and the elastic plastic layer is composed of polyurethane that can be reticulated to a low degree. Provide glass.

Particularly good results were obtained when the Young's modulus was 1.2×109dyn/
CT! This is obtained by using a plastic material having an elongation at break of 70% or more and a plastic deformation rate relative to the elongation at break of 1% or less.

Safety is high because the glass sheet and the layer of plastic material are tightly laminated with their edges bonded together, and the plastic layer provides an effective protection against tearing.

Also, since the plastic layer is scratch resistant, it does not require a separate layer to protect it. It has been found that a layer of plastic material having the mechanical properties described above performs two desirable functions.

One of them is that the deformability is extremely high, so that even when the glass sheet is broken and subjected to severe local bending action, it does not tear and can still serve as a protective screen.
Another is that it has an extremely high self-restoring ability, and as it completely restores itself in a short period of time, scratches and dents on the surface can completely return to their original state in a short period of time. This large elastic deformation capacity is not due to the fact that the plastic material exhibits a state of being easily damaged on its surface, as might be thought at first glance, but rather due to the fact that such damage disappears rapidly. Rather, it can be said to be durable. The relationship between the mechanical properties (elastic modulus, elongation at break, and plastic deformation rate relative to elongation at break) of the plastic material layer used in the present invention and tear resistance and self-righting ability will be explained in detail below.

Energy absorbed by the windshield to stop the occupant's head in a vehicle accident when the occupant's head hits the windshield at a speed less than 30 mm/hr (i.e., less than the windshield's penetration limit) The amount is about 40 to 50 mkp. This absorption of energy by the windshield is caused by the deformation of the windshield, especially the intermediate layer (generally made of polyvinyl butyral) sandwiched between the two sheets of glass that make up the windshield.
This is achieved by plastic deformation of That is, the moment the head hits the windshield, the glass sheet is damaged and the intermediate layer is deformed. The deceleration acting on the head should then be kept at a constant value below a certain value to avoid severe head injury. The limit characteristics at which such safety is maintained are the ``Head Injury Criteria'' (Head Injury Criteria H).
IC) and is specified in the US Vehicle Safety Standard 208 Docket 69-7 Announcement 16. Generally, this index is considered to be less than 1,000. Furthermore, even if a windshield consisting of two glass sheets and a polyvinyl butyral interlayer does not penetrate, skin contact with the edges of glass shards in the deformed portion of the windshield can cause varying degrees of injury. .

Even when the inner glass sheet of the laminate is broken, the protrusions of the glass pieces cause injury. To date, injuries such as those mentioned above (
It has been proposed to attach a plastic sheet that acts as an anti-tear layer to the inner surface of the windshield to avoid "tear marks".In general, the anti-tear layer must meet the following requirements: 1. The presence of the anti-tear layer increases the resistance to deformation of the windshield and the aforementioned HIC index must not increase significantly.

2. The anti-tear layer should have sufficient elasticity to cover the glass pieces in the deformation damaged area of the windshield.

That is, the tear-resistant layer must deform simultaneously with the deformation of the windshield, and must not be damaged by the edge of the glass piece. 3. The anti-tear layer must be scratch resistant and self-righting.

In other words, when the surface of this layer is locally scored or scratched, these scars must disappear after a short time. The plastic material layer used in the present invention, which has an elastic modulus of 2.0 x 109 dyn/d or less, an elongation at break of 60% or more, and a plastic deformation rate relative to the elongation at break of 2% or less, satisfies the three requirements mentioned above. do.

The mechanical properties of the plastic material layer used in the present invention will be further explained below. 1) Elastic modulus (2.0X10
Experiments have shown that applying a plastic layer to the inside surface of the windshield significantly increases the HIC index.

It is said that the amount of increase in the HIC index due to the formation of this plastic layer should be substantially less than 10%, but the amount of increase varies greatly depending on the elastic modulus. For a 500 micron thick plastic layer, the modulus of elasticity is 2.
．． At 0×108 dyn/CrlL, the amount of increase in the HIC index is 10%. If the thickness of the plastic layer is 100 microns, its elastic modulus can be increased to 1.0 x 104 dyn/~ without any particular problem, and if the thickness is 50 microns, the HIC index will increase excessively. Modulus of elasticity is 2.0X109dyn without
/d can be increased. On the other hand, a thickness of 50 microns corresponds to the lower limit of tolerance for exhibiting anti-tear functionality (the preferred thickness is 100 microns or more). That is, H.I.C.
The modulus of elasticity of the plastic layer to suppress the index increase to an acceptable range is practically 2.0 x 10 pdyn/Cd.
It should be: Also, from the standpoint of self-restoring properties, the value of the elastic modulus should be 2.0×109 dyn/(177 f or less).

2) Elongation at break (60% or more) When a vehicle occupant's head collides with the windshield, the glass itself breaks at the impact area, but it is desirable that the glass fragments are supported by the plastic layer and do not scatter.

In other words, it is desirable that the windshield (including the plastic layer) deforms into a semi-circular shape at the point of impact. In order for the plastic layer to stretch to a hemispherical shape without breaking, the elongation at break must be 60% or more. 3)
Plastic deformation rate (2% or less) The value of plastic deformation rate is substantially related to self-restorability.

When the plastic deformation rate exceeds 2%, permanent strain clearly remains when scratched, resulting in optical defects. The plastic layer of the present invention with a plastic deformation rate of less than 2% has sufficient self-righting properties and has a scratch resistance of at least 25-30 g.
Note that a plastic deformation rate of 1 to 2% contributes to the absorption of a small amount of energy (0.1 mkp) during a collision. Known plastic materials having the mechanical properties described above and suitable for use in the present invention include low reticulation aliphatic polyurethanes. Such polyurethanes are well known and are used, for example, as paint additives. Also, such polyurethane is covered by German Patent No. 20.
No. 58504, in which it is used to protect polycarbonate sheets. moreover,
Also described in US Pat. No. 3,655,432. Such polyurethanes have adhesive strength that allows them to be bonded directly to glass surfaces without the need for inserting a special adhesive layer. The safety glass window according to the invention can also be a laminated glazing of the known type (two sheets of glass glued together by an intermediate plastic layer).

In this case, the plastic layer serves as a protection against tears, since the impact energy is absorbed by the deformation of the intermediate layer, for example polyvinyl butyral, and the sheet is not penetrated. The thickness of the plastic layer may therefore be small, for example from 0.1 to 17 nm. Preferably it may be 0.2 to 0.5n. The advantage of such an embodiment is that the sheet is simple to manufacture, requiring only the addition of a plastic layer according to the invention to a conventional laminated glass sheet. Next, embodiments of the present invention will be described with reference to the accompanying drawings.

The accompanying drawing is a sectional view of a safety glass window for an automobile windshield according to the present invention. In the drawings, sheets 1 and 3 are silicate glass sheets of conventional thickness.

Sheet 1 constitutes the outer surface of the windshield and has a thickness of, for example, 3 to 4 mm. The inner glass sheet 3 is 2 to 31
The thickness is 1. Both sheets have a minimum thickness of 0.767n
7! They are adhered to each other by an intermediate layer 2 of thermoplastic material made of polyvinyl butyral. On the inside surface of the car, the thickness is 0.2 to 0.57! A deformable plastic material of Tm is disposed. The material forming the coating is a highly reticulating aliphatic polyurethane at ambient temperature having the following properties: Regarding coating of plastic materials. Sheet 3 with material in liquid form
It is obtained by depositing it on top and then heating it to polymerize it.

Alternatively, it can be adhered to the glass in the form of a solid sheet. This adhesion can be effected by known methods, such as by means of an intermediate adhesive layer or by the action of heat, or by adhesion with activators or suitable solvents. The safety glass window of the present invention is particularly suitable for automobile windshields, but can also be used for all types of windows where safety is required as well as windshields.
That is. A window that does not penetrate the glass in the event of a human impact and therefore prevents direct skin contact with the sharp edges of broken glass fragments can be used where needed.

[Brief explanation of the drawing]

The accompanying drawing is a sectional view of a preferred embodiment of a safety glass window according to the invention. In the figure, 1 and 3 are glass sheets, 2 is an intermediate layer, and 4 is a layer of plastic material according to the invention.

Claims (1)

[Claims] 1 It has a laminated structure in which an energy-absorbing plastic layer is interposed between an inner glass sheet and an outer glass sheet, and an elastic plastic layer is adhered to the inner surface of the laminated structure. A transparent safety glass having the ability to absorb the energy of an object it collides with through substantial plastic deformation upon impact and to protect against lacerations caused by broken glass, the safety glass being affixed to its inner surface. The applied elastic plastic layer is transparent, highly tear resistant and self-righting, and furthermore, the elastic plastic layer ruptures by itself upon impact without substantially inhibiting the energy absorption of the energy absorbing plastic. The elastic plastic layer exhibits sufficient elastic deformation to protect against lacerations from broken glass through substantial plastic deformation of the safety glass without causing any damage, and the Young's modulus of the elastic plastic layer is 2.
0x10^9dyn/cm^2 or less, elongation at break 60
% or more and the plastic deformation rate relative to the elongation at break is 2%.
Safety glass, characterized in that the elastic plastic layer is composed of polyurethane that can be reticulated to a low degree.