NO164425B - PROCEDURE FOR THE PREPARATION OF A PAPER AND OTHER CELLULOSE-CONTAINING SUBSTANCES. - Google Patents

Description

Laminated safety glass with a polycarbonate layer.

The commercially available laminated safety glass

consists of two glass plates with a thickness of 2 - <l>+, preferably about 3 mm which are connected to each other by a layer of an elastic adhesive having a thickness of 0.05 to 1.0, preferably 0.1

to 0.5 mm, and usually consists of polyvinyl butyral with a plasticizer.

These safety glasses will at room temperature in general

able to withstand shocks with an energy of approximately 1.5 mkp, while they are pierced by stronger shock loads. However, safety glass of this type has the advantage that the bulk of the glass splinters that are formed when the glass is pierced are not released, but fixed

held by the adhesive layer, while the loose splinters fall £?. "kl<9>? SElJ/ia* <lm>idl<9rt>ld "i«~*«*d.t is due to a men's*-

equal body part, e.g. a head, as will often be the case in a car accident, this part of the body is easily exposed to being damaged in the event of serious head injuries, as radially directed splinters form around the hole and are very dangerous for the neck (so-called "neck collar").

It has so far been assumed that laminated safety glass of this type could be improved by increasing the thickness of the adhesive layer or the foil, for example* to between 0.76 and 3 mm, at the same time as increasing the content of the plasticizer and at the same time choosing the glass plates somewhat thinner (see US- patent 2 9^6 711)» These laminated safety glasses have also found application in practice and go under the name

"High Impaot" (Hl-)laminate glass with a butyral foil thickness of 0.76 mm. However, no experience has shown that it. the speed with which a person's head crashes through such a windshield increases significantly, but at the same time the risk of life-threatening cervical vertebrae fractures increases. The reasons for this will be explained in the following.

It has also been proposed to produce laminated safety glass which consists of at least approx. 2 mm thick sheets of high-molecular, linear bisphenol-polycarbonate which is provided with a scratch-resistant surface layer. In an embodiment of this safety glass, the two scratch-resistant surface layers consist of preferably at least 1.5 mm thick glass plates which are connected to the polycarbonate sheet by approximately 0.1 mm thick adhesive layers. In the case of safety glass of this type, the polycarbonate sheet forms the predominant part of the entire laminate, as the glass sheets only serve to give the polycarbonate sheet a scratch-free surface. The other properties of these laminated safety glasses are thus determined practically exclusively by the properties of the polycarbonate sheet.

The most important advantage of these laminated safety glasses consists in the fact that, as a result of the high impact strength of the polycarbonate sheet, they do not shatter, even with strong impacts. It will most likely be the cover plates made of glass that splinter, but these splinters will not be released, as they will still be held by the sticky layer, so that no opening can be formed with radially aligned glass splinters ("neck collar" ).

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] Another advantage of these safety glasses lies in the polycarbonate's favorable light beam absorption properties, as the loss in the visible spectrum is negligible, while the unwanted ultraviolet and infrared rays are practically completely held back. In this connection, mention should also be made of the n better thermal insulation aaanmnl

similar to panes that only consist of glass, which, among other things, means that these laminates with polycarbonate discs have less of a tendency to fog than glass plates.

As far as these laminated safety glasses consist of a sheet of a clear transparent polycarbonate sheet and clear transparent glass sheets and the adhesive layer is also chosen of the clear transparent kind, these glasses can e.g. is used in connection with kiftretbys, especially cars and railway carriages. However, they are less suitable as front or wind protection glasses, as, if they are hit by one of the passengers' heads, for example, they will spring back and, as a result, could cause a serious concussion (pendulum trauma) or even a cervical spine fracture.

The invention is aimed at a laminated safety glass of the kind that consists of two clearly transparent, possibly curved or/and colored® glass plates, between which, with the help of clearly transparent, possibly colored adhesive layers, are glidable Inside* is placed a clearly transparent, possibly colored foil of a hbymola= kylart polycarbonate of bivalent fsnols, that the glass plates; as

is preferably ground and polished on both sides and possibly £or~ tensioned;, has a thickness of between 2S8 and 3S3 mm9 that the polycarbonate foil ha? a thickness of between 0.7 mm and 5 mm and that the adhesive layer has a thickness of between 0.05 and 1.0 mm

It has been shown that a laminated safety glass of dean© art hai?, great use value in mango applicationøpurpose5 thus-.. aasFltfe as rtatQ? in kjtJfføtdyarp such as froatglasa^iato? 1 biles?, and that diaao Safety glass offers staring benefits eåzx they initially bs= skreva© lamioorto sikkQ^hotøglass" in

Also, the thickness of the glass plate and of the buty<p>al-;£bli©a at ds above mentioned© Hl-sikkeshstisglaos© of the same stbrrels© i- \ srdoa.soB the tylkolsen of.glasskiv©a and of lollycarbonafcfoliea vad .. ølkke <y>hetlioset according to foroiiggcridQ ®ppf innolso.j. and. i dot overiaavat©. mor.lfeaasefa'patøat <q>é åét lafefirllg sued ■'ferøiikøa effect that is achieved véå aavenda diasQ. iykkolo©?j aår-dot' gjolSpy :/.;i^-iBse^%.iPoiPE6ia> afij? :W'$ t£& a * v^ an' yes øsqo J era.- oodo Inte*. fé>&&%~ J• ilaøaat;(Bi?-' raédatlit av. dattø øåÉmoåaét*^ kiteriala»<;> ■"' ..<: >- •,,.-Sil^teaQo; Sqs dioso i'dot VQsont&lgo ovéffoasb^.ésaiaQad^.'. tytikéivits'- of :Q2,aadp2i&taa;:'©g^ kuastoto^foliå^-M' doi;iaidlostid fast-§,l&a-,ac fde-^ayo security glass akillQ<g> osg , ffga- åa øyGafor described .

<!> glass by two essential features, namely that the plastic foil is not made of a highly softened butyral foil, but of a non-softened polycarbonate foil and that between this polycarbonate foil and

An adhesive layer is arranged in the glass plate, as the polycarbonate foil does not bond to the glass in this way, while the soft butyral foil itself serves as an adhesive.

However, since the properties of a polycarbonate foil are completely different from the properties of a softened polybutyral foil, the corresponding laminated glasses will behave very differently when they are hit by a passenger's head.

As the thickness of the glass plates in the known laminate glasses is reduced, the so-called "peak front" is significantly reduced compared to the conditions in the older safety glasses. This also applies to the safety glass according to the invention. As a result of the strongly foamed butyral foil, the so-called "onset", i.e. the force-bending ratio upon impact, is also reduced, and in addition to this it should be mentioned that this as well as the smaller "peak foroe" is desirable (see the American patent, column 2, line 57" to I column 3" line 6).This is believed to be strongly connected with it

•softened butyral foils' very large plastic deformability. Then i

In this plastic deformability is incomparably less with the Ipolycarbonate foil, the reduced "onset" with the new plates will not occur or only to a very small extent. Of course, it might seem to you that the laminate glasses according to the invention are less suitable than those described above, but this is in reality not the case, because in the considerations of the properties which are given in the American patent and which are desirable for a safety glass, a significant circumstance •satljcompletely out of consideration. The dangers that occur when a person's head hits a plate do not only consist of injuries as a result of shards of glass or the so-called "neck collar", in skull fractures as a result of too high "peak force", 1 serious concussions as a result of the recoil at hby; "peak foroe" or the body's ejection through a broken route,

while the greatest and most serious danger "consists" in the half-vortex fracture.

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It is known today that these hemispherical fractures occur when the glass foil, [after the glass plates have been damaged, when the foil has stood against. to be damaged and has strong plastic extensibility, bulges out at the point of impact and possibly keeps the head back in its position, while the passenger's body with its great weight is pushed behind,

It is assumed that the shock energy will act on the more or less bent halji vortex column and thereby cause it to crack or break.

From this it appears that the time period in which the forces act plays a rather significant role. Already L. M. Patricl:, Department of Engineering Mechanics at Wayne State University, has ascertained the tolerances for the permitted force resistances depending on

In proportion to the working time of a person's head during concussions of

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j medium degree (see "Human Tolerance to Impact - Basis for Safety j Design"). Recent investigations by D. Ziffer, F. Brtlckner and R. Hein on "Das Verhalten der HalswirbelsHule in Verbindung mit der ; SohHdelbasis und der oberen BrustwirbelsSule bei StUrzen auf Sichsr-heitsglass ftlr Automobilfrontscheiben (Einscheiben-Sicherheitsglas-Verbundsicherheitsglas)", Zentralblatt fttr Verkehrsmedizin , Verkehrs-psychologle und angrenzende Gebiete, December 1967, has shown that the tolerance limit for the duration of action of the restraining forces in macroscopic cervical vertebra injuries is significantly below the above-mentioned tolerance limit for concussions. The extent to which this is the case can be seen from the following figures. With a working time of the effective shock forces of 50 ms, the tolerance limit for concussions according to Patrick is already at 220 kpef.£, but in the case of damage to the cervical vertebra abscess this far down such as at 50 kPaf These values apply to macroscopic damage to the hemi-vortex, e.g. initial drawing 1 intervertebral discs. The tolerance limit lies

even lower;^ if microscopic damage is also to be taken into account, which can also be life-threatening. In general, it must be said that stbttimes of more than 30 ms represent a serious danger for the cervical spinal cord abscess and must therefore be absolutely avoided.

With particularly strongly softened and particularly thick butyral foils according to the above-mentioned American patent, however, the duration of action of the forces on a head hitting the glass plate will be particularly long (see also curve B in the patent document), so that the risk of cervical vertebra fracture is greatly increased. Thus, one has e.g. measured the total stbttimes for slices with a 0.76 mm thick polyvinyl butyral foil of up to 160 ms. This also seems, as it has become known in the meantime, to be the reason why the accidents with a fatal outcome, where the head hit such a safety glass in the car, did not decrease after the introduction of the HI safety glasses.

In the case of the laminated safety glass according to the invention

then the conditions are significantly different.

The total stcSttld is drastically reduced as a result of the polycarbonate's special properties. The polycarbonate foil is deformed

1 locally limited scope immediately below the starting point and is drawn

forebrlg out of the frame without being subjected to any appreciable stretching. As a result of the polycarbonate's small stretchability, the pane will be freed from the frame already after oa0 20 ms, while

if polyvlnyl batyral is used, as already mentioned, it would take up to 160 ms until the glass plate is pulled out of the frame"

It is therefore 1 in accordance with the most recent findings when it comes to cervical vertebra injuries, it is less dangerous to release the entire frame opening than to allow a slow destruction of the stbt energy by plastic deformation of the safety glass.

If the glass plates or/and the polycarbonate plate are too

thin, not all energy will be consumed when the glass plates are broken through and the polycarbonate plate is deformed; the safety glass would then be unable to see through and behave in the same way as the previously known laminated safety glass" If the glass sheets are too thick, they will

Do not break, so that a rebound would occur as mentioned above. If, on the other hand, the polycarbonate sheet is too thick, it will

; Don't be deformed and there will also be a backlash in this case"

According to the invention, the alto& > thickness both of glnso plate and of the polycarbonate plate volgoo should be flame welded to dot at oammsa" /

in elobing of the three plates formed laminate, can withstand less ctbjS out a

•• 'I laf^oscaa^ooOQGVttOOffislJ&boWfføs' røyot?q citOOono^Gao? oOo© cf. ©GpoSsap j /,;> j i>ersons for damages such as fbTg© of atstfieado splinters or as fblgc of the plate returning years Within thick Ise areanoifbigo opi» the p.anelo, one can oa to a certain extent innotillo don stbtgrince until the Wilkea safety glassoo remains less damagedGt , aoolig vod eatoa å •, yoloo tyanero ellor tyker© glossplaefor sllor øa tynnoro ollo? $$slso= sp polycarbonateg)lat©o For <! et ooete o.2>,.dot '& forotrokki d volgo '... '' ! pymnoro. glasopldtos? fcombiaex t with oa phtyl crust polycarbonAtplDto bllci?.

In pvonite j ollos> £. vcIqo oXlo t?o ^pictQ? pifldoio,. thick

ofcal fFOQhevog ct doa.Éo.^ato lokalo fiofG^eaoioæ gv -- , '■•'4.|)61ytex?feonatplDtoa ,.or bptiacot of 'noJ.yDoj?bocatctc ocbl&ge 0QG0É}kcp .

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in and of itself lies hbyt, e.g. of approx. 10° C in the case of polycarbonate is bisphenol A (2,2-bis-phenylol)propane), does not show any cold fluidity and is probably not really to be regarded as plastically deformable, as the plates would otherwise not have permanent dimensional stability, but on the other hand under certain conditions are extendable. The local deformation is therefore a consequence of a stretching process which is associated with the consumption of significant amounts of energy.

Furthermore, the polycarbonate's ability to absorb ultra-violet and infrared rays is so great that a thin foil is sufficient to keep these rays practically completely back. With regard to the optical properties, 1 addition applies to this that glass plates with a thickness of oa 2.5", especially from 2.8 mm and upwards, 1 contrary to thinner glass plates, can easily be ground and polished on both sides, so that one preferably can make use of so-called mirror glass. It is likely that the new laminated safety glass will satisfy the high demands placed on the optical quality to a significantly greater extent, especially when it comes to the front glass panels that are to be used in motor vehicles and which are reg. is curved, than the hitherto used safety glass (compare in this connection e.g. "Verkehrsblatt", Amtsblatt des Bundes-ministers ftlr Verkehr der Bundérepublik Deutschland, 19» year. 1965» hefte 3, pp. 61 - 116, especially p. 89, section 8, 25 (2) and p. 91" v. column 3)*

Of no less importance is the fact that the production of steel bars, especially of curved safety glass by gluing an intermediate thin, usually oval polycarbonate foil between the thicker, possibly pre-curved glass sheets, is technically significantly easier to carry out than connecting a thicker, practically rigid polycarbonate sheet with likewise practically rigid glass plates which can possibly be thinner. It should also be mentioned that the polycarbonate's relatively low thermal conductivity is also advantageous, as the tendency for fogging and frosting due to temperature differences is greatly reduced. For this reason, the aforementioned polycarbonate is particularly suitable in combination with glass for the production of laminated safety glass sheets.

The production of high-molecular thermoplastic polycarbonates with divalent phenols, especially bisphenylol alkanes, is known q e.g. described in the German patents 1 011 178, 971 777 and 971 79U Of these polycarbonates, plates 1 with a thickness of 0.5 to 2 mm can be pulled out of the smelter in a known manner through wide-band nozzles. In order for smooth plates to have practically completely plane-parallel surfaces and thus optical isometry, it is generally advisable to finish them in a manner known per se in a plate press or a calender.

As an adhesive, the agents that are already used in the production of the initially described laminated safety glasses can be used, e.g. silicon rubber and curable polyester-styrene mixtures, preferably those where the mixing ratio of polyester to styrene is at least h:1, as well as blob'.tized epoxy resins and the polyvinyl-butyral foils and the like which are known in connection with the production of laminated safety glass. The known in and of themselves, more or less bubbled polyacrylate adhesives have proven to be particularly advantageous, as they also in the form of relatively thick '.ag have particular optical clarity, an excellent adhesion to glass and polycarbonate and a cohesion that makes them suitable by a slippery name sealant and which also sufficiently retains these properties at temperatures down to about -30° C.

The assembly of the three discs itself is carried out in a manner known in and of itself from the manufacture of laminated security

glass. The new safety glass can be used wherever it is desirable that a window glass is not broken even if it is exposed to strong blows and the risk of flash damage must be excluded. As a result of the special properties described above, the new safety glass is particularly suitable for use in vehicles of any kind, just not for windscreens in cars. i : i Example 1 ., j I A 30 x 30 cm large, 2.i8 mm thick mirror glass plate was pre- | iynt with a 30 x 30 cm large, 0.5 mm thick adhesive foil of a mixed polymer of 65 weight percent 2-ethylhexyl acrylate and 35 weight percent ethyl methacrylate with a relative viscosity of 1.815, measured in a solution of 0.5 g of substance in 100 ml of benzene at 20° C. A 30 x 30 cm, 0.8 mm thick plate of bisphenol-A polycarbonate with a relative viscosity of 1.32 measured with a 0.5 pro- methylene chloride solution at 25° C. On the latter layer, an adhesive foil with the same dimensions and the same composition was also placed and a mirror glass plate with the above-mentioned

dimensions. In order to prevent the five layers from shifting one another during the subsequent treatment, the laminate was held together by means of staples. The laminate was heated in an autoclave to 130° C at a pressure of 100 torr and then slowly cooled to room temperature over the course of 60 minutes, during which the pressure increased to atmospheric pressure. The result was a clearly transparent laminated plate.

Example 2

The procedure was the same as described under example 1, but the glass plates were prestressed mirror glass plates.

Example ^

The procedure was the same as described under example 1, but as adhesive foil one of a mixed polymer of 65% by weight butyl acrylate and 35% by weight methyl methacrylate with a relative viscosity of 175 was used.

Claims (2)

■*•• Laminated safety glass, consisting of two clearly transparent, possibly curved or/and colored glass plates, through which, by means of clearly transparent, possibly colored adhesive layers, a clear transparent, possibly colored foil of at.hby molecular polycarbonate of divalent phenols is inserted, characterized in that the glass plates, which are preferably ground and polished on both sides and possibly prestressed, has a thickness of between 2.8 and 3>3 nm, that the polycarbonate foil has a thickness of between 0.7 and 1.5 mm and that the adhesive layers have a thickness of between 0.05 and 1.0 mm. 2. Safety glass according to claim 1, characterized in that the adhesive layers consist of a polyacrylate adhesive part.