USRE21904E

USRE21904E - Laminated light polabizer

Info

Publication number: USRE21904E
Authority: US
Publication date: 1941-09-23

Description

Sept. Z, 1941. L Re 21,904

' -LAMINATED LGH' POLARIZER Original Filed A u 15, 1936 NVENTOR ATTORNEY Reisued Sept. 23, 1941 v LAMINATED GET Edwin E. Land. Boston, Masa., asior, by meme inmentsg to Polaroid Corporation. Dover, Del.. a oo-poratlon of Delaware Original No. amazzo, dated Amt Lasse; se. risi No. 90,190, August s, sas; Application to: reisse na; 1940. se- No. saose 4 13 Ciaims. r .(01. 88-65) This invention relates to a new and improved laminated light-poiarlzer.

An object oi' the invention is to provide a lisht-polarizer in laminated form comprising a sheet-like light-polarizing element'having adhesively afllxed thereto a plurality of sheets of glass or other protectivemedia.

Another' object of the invention is to provide such a light-polarizer wherein the sheet-like light-polarizing element may comprise a 'set plastic having dispersed and embedded therein a multiplicity of polarizing particies oriented with their :polarizing axes in substantial parallelism.

Further objects of the invention are to provide a laminated polarizing element wherein such a set plastic polarizer is adhesively aflixed to two sheets oi' siass' by means of an adhesive comprlsing a substantial amount of plasticizer as compared with the plasticizer in the polarizing pl-astic; to provide such a lamination wherein a different -plasticizer is used in the cement from that employed in the polarizer; toprovide such a lamination wherein the index oi' refraction of the adhesive coincides with that of the set plastic polarizer; and to'provide such a lamination wherein the adhesive is a non-solvent 'of the plastic'polarizer.

A still further object of the invention is to provide a laminated polarizer comprising succes- `sive1y a sheet of glass; an adhesive containing a large; amount of plasticizing material, a sheet of light-polarizing material comprising` a set plastie and a minimum of plasticizing material, a second layer oi' adhesive comprising a large amount of plasticizing material, and -a second sheet of glass.

A still further 'object of 'the invention is to provide a laminated light-polarizing element possessing a maximum of shatter-prooi properties.

, Other objects of the invention will in part be obvious and will in part appear hereinater.

The invention accordingly comprises the article possessing the features, properties, and the relation of elements which are exemplifled in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a -iuller understanding of the nature andobjects of the invention reference should be had to the accompanying drawing. which represents in an enlarged and somewhat dia"grammatic view a cross-section o! a laminated polarizlng element embodying the presentainvention. y

The present invention contemplates the production oi a laminated light-polarizing material comprising essentially a central layer of lightpoiarizing material in sheet-like for-m. two outer layer-s of glass or other like material, and intermediate layers` of adhesive adapted to join permanently the polarizing layer to the outer layers of glass or other material. I

The polarizing material employed may comprise a material sold commercially under the trade-name "Polarioid." This material comprises a set plastic medium having embedded therein a' mass of polarizing particles such, for example, as particles of herapathite, with their polarizing axes oriented to substantial paralielism. The material possesses certain distinct advantages. It may be obtained in sheet-like form,

the sheets are thin, pliable, easily shipped and' handled, and they may be cut to any desired size. The material possesses an unlimited-angular aperture and is highly efllcient as a lightpola-izer.

` Where Polaroidis employed as the sheet-like polarizing material in the lamina'tion of the pres- -ent invention, the adhesive should comprise a plastlcizer which does not deleteriously aflect the crystals of herapathite or which is not a solvent for cellulose acetate, cellulose acetate .being the material employed esthe transparent suspending medium in Polaroid.

It is to be understood that while Polaroid is a preferred polarizing material, other suitable materials may. if desired, be employed. In /every case, however, the adhesive employed in the present invention should preierably contain a plasticizer which is either inert in the quantities used, with respect to the polarize', or which is a nonsolvent for the polarizer.

Where Polaroid is employed the suitable adhesive may comprise a mixture of a highly polymerized vinyl acetate, such as the material sold commercially as Vlnylite Als," and dibutylphthalate, in' the proportion approximately of 300 grams of vinyl acetate to 100 cc. of dibutylphthalate. In such a mixture dibutyl-phthalate acts as the plasticizer' and is a'non-solvent for cellulose acetate. such a cementitious material may also function as a water-prooflng 'agent..

The mixture of Vinyiite and dibutyl-phthalate may preferably .beheated to a temperature approximately of 250 F., and may be cooked at that temperature for a period .ot from two to three hours. It is to be understood, however, that these temperatures and periods of time are not critical, but that the materials should be mixed and heated until they are thoroughly plas- !orced !rom the gun on to the glass 'sheets employed in the manutacture ot the laminated polarizer; I! desired the prepared adhesive mixture may be extruded or otherwise !ormed into thin sheets. which may be cut to size and placed upon suitable glass sheets. I

It is to be understood that the adhesive is preferably applied to two sheets o! siass or similazmaterial which, 'during this stage of the process, may be maintained ata temperature oi' approximately212 I". Here again the temperature is by no means critical. It is. preterable to work this stage of the process with the materials in heated condition, so that they may be maintained in a fairly plastic condition. I! desired, however, the adhe'sive may be applied cold to the glass and the glass and adhesive then heated.

The sheet-like 'polariaing material, suitably cleaned, may then be applied to the adhesive on one o! the giass plates, and the other plate placed on top ol' the polarizing sheet and the assembiy then placed in any suitable press or other holding mechanism, and subiected to a uniform pressure, preierably in the nelghborhood oi 150 to 200 pounds per square inch and !or a. period oi' from one to two minutes. Here again the pressure employed and the 'time during which the pressure may be applied are not critical. If a smaller pressure is employedit will be understood that the lamination will be held under the pressure !or a somewhat higher period. Throughout the period of pressing it is preferable to maintain the lamination at a temperature, for example, of i'rom 200 to-2l2 I". 'The lamination is then removed from the press and the extruded adhesive rolled or cut from around the edges of the lamination. The entire assembly is then suitably cleaned.

In the drawing, III represents the glass plates..

ll the layers of adheslve, and 12 the lightpolarizing material.

While a mixture oi' Vinylite, and dibutyl- *phthalate has been described as the preferred cementing material, it is to be understood `that other materials may be employed. For example, other vinylcompounds may be employed, or an acrylic' ac'id .ester may be employed as the adhesive with suitable plasticizing media. Even where Vinylite is employed it is to be understood that other plasticizers -may be employed, provided, however, that the plasticizer is a non-solvent tor the polarizing material in the 'laminatiom The index of rel'raction for Polaroid which. it'

the present invention. Il' it is desired, howu ever, to change the plastlcizing material and still to employ Vinylite in the .cement. other pla'stics suitable to the present invention maybe diethyl-phthalate or isoamyl-phthalate.

While glass has been. described as the medium employed in 'connection with the laminatlon oi, the present invention. it is to be understood that other media may be employed as the outer or protective elements. For example' synthetic plastics such as the material sold as "Plexigum,"

a polymerized acrylic acid ester, or.sheet cel- I lulosic compounds, or other similar media may be employed. It is to be understood that where media other than glass are employed it may be desirable to supply a cementitiojis material which may be plastic at lower temperatures than that of the cement described in connection with the preferred embodiment of the invention above.

It is also to be understood that, it desired, a single layer of adhesive may be employed to afflx the polarizing element to a supporting mem-- 'to employ a somewhat harder cement than that described above, tor-example a cement whereln less plasticizer' is employed. Where this modification of the process is employed it is to be understood that the prepared 'sheets of light-polarizing material employed with the cementitious coating applied ther'eto 'maybe kept 'available for lamlnation with glass or other material ove 'a somewhat extended period.

It is to be understood furthermore that under certain circumstances it may be deslrable to employ Canada balsam as the cement; This material is not, however, to be preferred. It is ex- 'pensive and possesses a dis tinctive yellowish color. It has the advantage, however, of being harder than the cement 'described in connection with the preferred embodiment of the invention when cold and' somewhat more easily rendered Dlastic when'heated. Canada balsam is, 'however, not useful where shatter-prooi' properties are to be desired. i i

The lamination ot-the? preferred embodiment` of the invention described above possesses very excellent' 'shatter-prooi' properties, i. e. shatterprooi! inthe sense used in the` automotive windshield industry. Polaroid, which' is ordinarily employed'as' the preferred light-polarizing material, usually contains very little plasticizer and hence possesses' great tensile `strength.` The cement material described above maintains a very fine bond between the light-polarizing material and the' giass over-a wide range of temperature variations. r

Where desired the product of the present invention may be produced in relatively thin form. For example, the glass or other material employed as the cover plates need only be thick enough to resist breakage under the pressures employed in the preparation of the lamination. The llght-polarizing sheet need be-no thicker than, !or example, .005 of an inch, and the layers o! adhesive may be even thinner.

Since certain changes may be made in the above product and different embodiments oi' the invention could be made-without departing :rom the :cope thereoi, itis intended that all matter contained' in the above description or shown 'in the, accompanying drawing shall be interpreted as illustrative andnot in a limiting sense.

It is also to be understood that the following claim: are intended to cover al otthe generic a and specific features oi the invention herein described, and all statements oi the sccpe oi' the invention which. as a matter of language, might be said to fall therebetween. a

Having described my invention, what I claim as'new and desire to secure by Letters Patent is:

1. A lamination comprising a plurality oi transparent elements having sandwiched therebetween and bonded thereto a sheet-like light-polarizing body comprising a set suspending medium having a mass ot oriented polarizing particles embedded therein, the lamination also comprising bonding material having a substantially higher plasticizer content thansaid set suspending medium and being substantially inert with respect to said light-polarizing` body.

2. A lamination comprising a plurality ot trans-` parent elements having sandwiched therebetween and bonded thereto a sheet-like light-polarizing body comprising a set suspending medium having a mass' ot oriented polarizing particles embedded therein,-the lamination also comprising bonding material, said material being substantially inrt with respect to said light-polarizing body and having an index of retraction coinciding substantially with that oi' said set suspending medium.

3. A lamination comprising a plurality oi' transparent elements having sandwiched therebetween a sheet-like light-polarizing body comprising a set suspending medium having a mass oi oriented polarizing particles embedded therein, and means tor cementing said light-polarizing body to said layer comprising a highly polymerized vinyl compound and a relatively large amount of plasticizer, a light-polarizing layer comprising a set suspension o! oriented polarizing particlea in a cellulosic medium comprising a relatively small amount oi plasticizer, a second adhesive layer and a second glaas sheet, the plasticizer in said adhesive bein a non-solvent otsaid ,celiulosic medium and ot said polarizing particles.

8. A lamination comprising a plurality of transparent elements having sandwiched therebetween and bondedthereto a sheet oi plastic having a relatively low plasticizer content, the lamination 'also comprising bonding material having a substantially higher plasticizer content than said plastic. 9. A lamination comprising a sheet oi giass, an

. adhesive having a relatively high plasticizer content; a sheet oi transparent plastic having a rela -tively low plasticizer content, an adhesive having a relativev high plasticizer content, and a second sheet ot glass, the adhesive layer-s bonding the plastic to the sheets of siass.

10. A laminated plate ot non-glare safety giass comprising a pair oi glass sheets, a layer ot plasticized polymerized vinyi resin adhe-ent to the inner face of each glass sheet, and a relatively thin sheet of hard cellulosic material'intermediate the vinyl resin layers and adhered thereto, the cellulosic material having dispersed and embedded therein a multipicity ot light polarizing particles with their polarizing axes oriented to substantial parallelism, the sheet ot cellulosic material having relatively little 'plasticizer' as com-` pared with the layers oi' vinyl resin.

11. A laminated plate oi non-glare safety glass comprising a pair of glass sheets. a layer oi' plastransparent elements, said means comprising a vinyl compound having a substantially higher plasticizer content than said set suspending medium.

4. A sheet oi' light-polarizing material having each oi its iaces coated with a substantially waterprooi', transparent cement having substantially the same index of reiraction as said sheet.

5. A shatter-prooi, light-polarizing lamination comprising a plurality oi sheets ot glass, a sheet of light-polarizing material comprising a set plastic material and a minimum amount oi plasticizer, and a cement for uniting said sheets comprising a plastic and a relatively large amount oi plasticizer.

ticized polymerized vinyl resin adherent to' the inner face of each glass sheet, and a relatively thin sheet of hard cellulosic material intermediate the vinyl resin layers and adhered thereto, the cellulosic' material having dispersed and embedded therein a multiplicity of light-polarizing particles with their polarizing axes oriented to substantial paralielism.

12. A iaminated plate of non-glare safety glass comprising a pair or glass sheets, a layer o! plasticized, polyme'rized vin'yl resin adherent to the 'inner face o! each glass sheet, and a relatively thin sheet of a transparent plastic intermediate the vinyl resin layers and adhered'thereto, said 6. A shatter-proor, light-polarizing lamination i comprising a plurality oi sheets of glass, a sheet of light-polarizing material comprising a set plastic material and a minimum amount ol plasticizer, and a cement !or uniting said sheets com aprising a vinyl compound and a relatively large amount oi plasticiser.

'7. In combination, a glass sheet, an adhesive sheet having dispersed and embedded therein a muitipiicity of light-polarizing particles with their polarizing axes orlented to substantial parallelism.

13. A lamination comprising a'plurality of transparent elements having sandwiched therebetween and bonded thereto a sheet-like lightpolarizing body comprising a set suspending medium having a mass of oriented polarizing particles embedded therein, the lamination also com'- prising bonding material comprising plasticized polymerized vinyl resin.

` EDWIN E. LAND.