AU687195B2

AU687195B2 - A glazing laminate having a replaceable sacrificial layer

Info

Publication number: AU687195B2
Application number: AU23368/95A
Authority: AU
Inventors: John Robert Kramer; Larry Vance Young
Original assignee: General Electric Co
Current assignee: SABIC Global Technologies BV
Priority date: 1995-06-30
Filing date: 1995-06-30
Publication date: 1998-02-19
Anticipated expiration: 2015-06-30
Also published as: AU2336895A

Description

S)ur Rcf: 557785 P/00/011 Regulation 3:2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT

I

Applicant(s): General Electric Company One River Road SCHENECTADY New Yoik 12345 UNITED STATES OF AMERICA DAVIES COLLISON CAVE Patent Trade Mark Attorneys Level 10, 10 Barrack Street SYDNEY NSW 2000 Address fur Service: Invention Title: A glazing laminate having a replaceable sacrificial layer The following statement is a full description of this invention, including the best method of performing it known to me:- 5020 A GLAZING LAMINATE HAVING A REPLACEABLE SACRIFICIAL LAYER Background of the Invention The predominant glazing material used by operators of urban transit systems is tempered or laminated glass. Where breakage is a concern, more expensive plastic glazing materials such as polycarbonate sheet are used because it is as clear as glass and virtually unbreakable. The cost of polycarbonate glazing may be as much as a factor of four or five times greater than the cost of similar gauges of glass. While plastic glazing is generally less breakable than glass glazing, it is more susceptible to being defaced by scratches and vandalism than glass glazing. Because the scratches are hard to disguise and when disguised interfere with visibility, scratched or vandalized plastic glazing must be replaced. Use of glass based glazing laminates for transportation applications is not an acceptable alternative insofar as when the glass glazing is broken, the bus or train wherein the glazing material is so damaged must be immediately pulled from service for replacement and repair of the damaged window or glazing material. Thus issues of public safety and convenience militate for less breakable glazing materials.

Glazing laminates are known and used in a variety of applications. One example is automobile safety glass which has typically comprised two layers or sheets of glass separated by an interlayer of a tough transparent plastic such as a plasticized polyvinylacetal. Laminates comprising polycarbonate sheets in contact with plasticized polyvinylacetal sheets are described in U.S. Patents 3,406,086, 3,539,442, and 4,128,694.

A more recent U.S. Patent, 5,126,208 describes a nonsymmetrical glass plastic laminate wherein the plastic may be polycarbonate or polyacrylate. Thus the laminates may either be symmetrical or unsymmetrical about the substrate which may be any one of several 25 optical materials such as glass, polycarbonate, polyacrylate, and the like. The materials being laminated to the substrate must possess both acceptable optical properties and durability and these criteria must also apply to the adhesives used to effect the bonds between the laminate layers.

Summary of the Invention 30 The instant invention pertains to laminates where o ore of the layers may be conveniently replaced. Thus the a o the invention comprises a substrate and a film which are a ly adhered one to the other, thereby facilitating a convenient acement of the film. When the substrate is not a homogeneous material but rather is p:\wpdocs\wls\spcc\557785.spc -2- According to one aspect of the present invention there is provided a laminate which includes a substrate which is a -ore laminate including: a polycarbonate substrate; and (ii) a hardcoat selected from the group consisting of allyl resin, polyester melamine, acrylic melamine, and organopolysiloxane hardcoats, and a film which is a film laminate including: a polycarbonate film; (ii) a hardcoat selected from the group consisting of allyl resin, polyester melamine, acrylic melamine, and organopolysiloxane hardcoats, and an adhesive means for replaceably adhering the film to the substrate whereby the laminate may be repaired by replacing the film.

Preferably, the core laminate additionally contains a primer. Preferably, the film laminate additionally contains a primer. Preferably, the adhesive means is a pressure sensitive adhesive.

According to another aspect of the present invention there is provided a method of assembly a laminate which includes the steps of selecting a substrate which is a core laminate including: a polycarbonate substrate; and (ii) a hardcoat selected from the group consisting of allyl resin, polyester melamine, acrylic melamine, and organopolysiloxane hardcoats, and selecting a film which is a film laminate including: a polycarbonate Sfilm; (ii) a hardcoat selected from the group consisting of allyl resin, polyester melamine, acrylic melamine, and organopolysiloxane hardcoats, and replaceably adhering the film to the substrate whereby the laminate may be repaired by replacing the film.

Preferred embodiments of the invention will be hereinbefore described with reference to the accompanying drawings.

Figure 1 A cross-sectional view of the glazing laminate of the invention showing a Score laminate laminated to a film laminate.

S:"i Figure la A cross-sectional view of the glazing laminate showing a core laminate and 25 a film laminate prior to assembly as the glazing laminate of the invention.

i. Figure 2 A cross-sectional view of the glazing laminate of the invention showing a core laminate laminated to a film laminate wherein the core laminate has additional material laminated to an exterior surface.

Figure 3 A cross-sectional view of the glazing laminate of the invention showing a core laminate laminated to a film laminate wherein the core laminate has such film laminates laminated to both the interior and exterior surfaces of the core laminate.

Detailed Description of the Invention In one embodiment of the instant invention, as shown in Figure 1, a substrate, 4, having an optional primer layer, 5, and a hardcoat layer, 6, comprises a core laminate which laminate is a lamellar composite that is to be laminated to a second lamellar composite which second lamellar composite is a film laminate, 8, having on one side an optional primer layer, 9, and a hardcoat layer, 10, and on the other side a pressure sensitive adhesive, 7, which bonds the substrate or core laminate to the film or film laminate. In this P embodiment, the film may be used either as an interior or an exterior p:\pdocs\ws\spccie\557785.spe -3surface of the glazing laminate of the instant invention.

In Figure la, the embodiment of Figure 1 is shown prior to lamination to produce the laminate of the invention; specifically what is shown is a film laminate additionally comprising a layer of pressure sensitive adhesive prior to being replaceably adhered to the core laminate.

In a second embodiment of the instant invention, as shown in Figure 2, the core laminate as shown in Figure 1 additionally possesses an exterior primer layer, 11, and an exterior hardcoat layer, 12. In this embodiment, the film or film laminate is shown as being on the interior surface of the glazing laminate of the invention.

In a third embodiment of the instant invention, as shown in Figure 3, the glazing laminate as shown in Figure 1 additionally possesses on an exterior side an exterior primer, 13, an exterior hardcoat, 14, laminated to an exterior film, 16, an optional exterior film primer, 17, and an exterior hardcoat, 18 bonded to the exterior surface of the glazing laminate by means of a layer of pressure sensitive adhesive, 15. The exterior film, 16, the optional exterior primer, 17, and the exterior hardcoat, 18, comprise a film laminate as previously defined herein. As a consequence of defining interior and exterior surfaces, the film, 8, becomes an interior film, the optional primer for the film, 9, becomes an optional interior primer for the film, and the hardcoat for the film, 10, becomes an interior hardcoat for the film. The optional interior and exterior film primers may be identical or different. The interior and exterior film hardcoats may be identical or different. The pressure sensitive adhesives used to bond the interior and exterior film "laminates to the substrate may be identical or different.

The various embodiments illustrated in the figures are not meant to limit the scope of the appended claims but are merely illustrative of the variety of applications that may 25 be devised from a glazing laminate having a replaceable sacrificial layer.

•In applications where a useful optical clarity is desirable the materials should be selected for their optical properties. Additionally, when clarity is a consideration, when a pressure sensitive adhesive is utilized to replaceably adhere the film or film laminate to the substrate or core laminate, then the pressure sensitive adhesive should be applied 30 to the film or film laminate such that when the film or film laminate is removed from the substrate or core laminate the pressure sensitive adhesive is also removed from the substrate or core laminate thereby permitting cleaning and/or polishing of the substrate or core laminate prior to replaceably adhering a new or replacement film or film laminate p:\wpdoc.\wls\specic\557785.spe -4to the substrate or core laminate. When transparency or clarity is not as critical to the desired application of the laminate of the invention, if a pressure sensitive adhesive is used to replaceably adhere the film or film laminate to the substrate or core laminate then the pressure sensitive adhesive may remain as a layer laminated to the substrate or core laminate.

The substrate, 4, from which the core laminate is produced is selected from the group of plastic glazing materials known in the art. The preferred glazing material for said substrate is selected from the group consisting of polycarbonate and polymethylmethacrylate. When the substrate, 4, is polycarbonate, it may be desirable to add stabilizers to the polycarbonate to protect it from the deleterious effects of ultraviolet radiation or to include stabilizers for protection from ultraviolet light in the hardcoat and or optional primer such as taught in U.S. patent 4,278,804.

The optional primer is a component, known in the art, that allows the hardcoat to be bonded to the substrate allowing for differences in the coefficient of thermal expansion. In those cases where there is not a good match in the coefficient of thermal expansion between the hardcoat and the substrate, the optional primer becomes desirable because it promotes adhesion between the two layers. Such primers are the subject of teachings and disclosures in the following U.S. patents: 4,313,979; 4,395,463; 4,477,499 and 4,559,271. More recently U.S. patent 5,041,313 is directed to a method for making 20 silicone hardcoat composites and primer compositions therefor whereby the primer and hardcoat are applied to an aromatic thermoplastic substrate. Polycarbonate is such an aromatic thermoplastic.

If there is a sutficiently good match in the coefficient of thermal expansion between the hardcoat and the substrate, the optional primer becomes less desirable or 25 unnecessary. The criterion to be employed in determining the desirability of employing the optional primer is whether a sufficient adhesion would exist between the substrate and the hardcoat such that the optional primer was not necessary to insure good adhesion.

These same considerations apply to the hardcoat and the optional primer used on the film.

When glass is the substrate or a component of the core laminate a match in the thermal 30 coefficient of expansion between the glass and the other layers such as the primer and/or hardcoat and the film or film laminate becomes a more significant consideration. It

S

should be noted that if the film comprises a polycarbonate then ultraviolet stabilizers should be added to either or both of the hardcoat and the optional primer.

p:\wpdocs\\vws\spccc\557785.spc *9 4I 4*1 9 4 .4 9 .4 44 9 4 The hardcoat may be any of several of those known in the art. U.S. patent 4,478,876 discloses a process for coating a solid substrate such as polycarbonatcs, polyesters, polymethyl methacrylate, polyacrylates, and polyamides with an abrasion resistant silicone hardcoat. U.S. patent 3,707,397 discloses an organopolysiloxane hardcoat for polycarbonate. U.S. patent 3,843,390 discloses polyester melamines and acrylic melamine hardcoats. U.S. patent 2,332,461 discloses allyl resin hardcoats.

The preferred means for replaceably adhering the film or film laminate to the substrate or core laminate utilizes a pressure sensitive adhesive. The pressure sensitive adhesive may be any of several of those known in the art. Acrylic based pressure sensitive adhesives are disclosed and enabled in U.S. patents RE 24,906; 3,558,574; 3.535,293; and 3,299,010. Silicone based pressure sensitive adhesives are disclosed and enabled in U.S. patents 2,857,356; 2,736,721; and 2,814,601. U.S. patent 4,370,358 discloses an ultraviolet light curable silicone that cures to a pressure sensitive adhesive.

U.S. patent 4,791,163 discloses an aqueous emulsion of an organic pressure sensitive adhesive and a silicone based pressure sensitive adhesive. More recently, U.S. patent 5.190,827 discloses a solventless organopolysiloxane composition that cures to a pressure sensitive adhesive composition.

A laminate of the instant invention where the materials for the substrate and the film were forms of polycarbonate and the replaceably adhering means was a pressure sensitive adhesive has been prepared and tested in a transportation glazing application for over one hundred and twenty days. The film or film laminate layer of the laminate of the invention has been subjected to damage by the test population and has not suffered any penetration. Thus the substrate or core laminate has been protected by the film or film laminate. Consequently, this new laminate structure satisfies a long felt need for a transportation glazing that is easily repairable when damaged or defaced but which is not as breakable as glass. As a glazing laminate the material has been removed from service, the film or film laminate removed from the substrate or core laminate, a new film or film laminate replaceably adhered to the substrate or core laminate, and the repaired laminate returned to service.

Additionally, a laminate of the invention substantially identical to that tested in actual use was subjected to an accelerated weathering test. After a test period under conditions equivalent in severity to a year in actual use, the laminate was inspected. No loss in optical properties or degradation in color was observed. The laminate suffered no p:\wpdocs\wls\spccic\557785.spc 6 loss in integrity, i.c, no delamination was observed, lhere was no change in the properties of the adhesive utilized to replaceably adhere the flim or l~lm laminate to the substrate or core laminate .4 4 4 J 46 04 4 4 4444 04 *O S 0 4 44 44 4 4 4 4* 4 .4 4* 44 4 4 4 444 4 44..

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Claims

2. The laminate of claim 1 wherein the core laminate additionally contains a primer.
3. The laminate of claim 1 or claim 2 wherein the fim laminate additionally contains 20 a primer.
4. The laminate of any preceding claim wherein the means for replaceably adhering the film of the substrate comprises a pressure sensitive adhesive.
5. A method of assembly a laminate which includes the steps of selecting a substrate which is a core laminate including: a polycarbonate substrate; and (ii) a hardcoat selected from the group consisting of allyl resin, polyester melamine, acrylic melamine, and organopolysiloxane hardcoats, and selecting a film which is a film laminate including: a polycarbonate film; K RA4 N) .1 a r K (va.. .14C p:\wpdocs\ws\specie\5S7785.spe (i i) at hatrdcoat selected fromi the group consistinig of al lyl resinl, polyester meclai ne, acrylic nielam mec, anid organopolysi lox-ane hardcoats, anid replaceably adhierig thle Film to the substrate whereby thle lamninate may be repaired by replacing the film.
6. A laminate substantially as hiereinbefore described with reference to the drawings.
7. A method of assembling a laminate substantially as hereinbefore described with. reference to the accompanying drawings. Dated this 13th day of November, 1997 GENERAL ELECTRIC COMPANY By Their Patent Attorneys DAVIES COLLISON CAVE RA/\ V p:\%vpd ocs\wv s\spccie\5 5785. spe A l~II~A( 1' A acw lam innie stracture COmpnsiflg a substrate or a core lamiante to which a him or lii in lain i nate is rCPhICC[d)lY ndhercd. *0 a a a. a a a. a a a a. *a a a a a. a a a a. a. a a a a. a. a 'a. a a. a a a a a p:\wpdocs~wls\specie\557785.spe