Patented Oct. 29, 1940 2,219,684 7 LAMINATED PRODUCT Eric -William Reginald Oswald Gib Fawcett, Walton-upon-Thames, son, Northwich, Cheshire,
and Michael Willcox- Perrin, London, England, assignors to Imperial Chemical Industries Limited, a corporation of Great Britain Drawing. Application March 2, 1939, Serial N0. 259,444. In
our copending application- 722, filed February 2,
Serial Number 123,- 1937, which describes new ethylene polymers and their use as adhesives in the preparation of safety gla nated articles.
An object of this invention ss and other lamiis to provide a new and improved type of laminated glass in which the laminae are united through a film or layer of great strength and durability. A still further object is to provide methods for making laminated glass wherein the interlayer comprises a polymer of the type described tioned copending application. appear hereinafter.
These objects are accomplished by uniting two or more laminae by means of a synthetic linear polymer in'the above-men- Other objects will a layer comprising which is produced in accordance with the method described in our aforementioned Patent ,2,153,553.
copending application or in U. S.
More particularly the invention comprises laminated glass composed of two sheets of glass having layer of the ethylene polymer as the sole bonding agent and therebetween a film or which may be used as the interlayer.
The solid polymers of ethylene used in the practice of this invention are, prepared by a process which consists in subjecting ethylene to a pressure in excess of 500 atmospheres under controlled elevated temperature conditions. This procedure results molecular Weight in polymers of ethylene, the of which varies depending particularly upon the pressure employed. By using pressures of more than 1000 atmospheres, solid polymers are formed and under these conditions the polymerization reaction takes place, requiring several hours for completion.
mers may also be made (in a process described in These polyccordance with the the copending application of Paton, Perrin and Williams, Serial Number 157,810) by including in the ethylene a small quantity of oxygen which may be as little as 0.01% but preferably atmospheres and 190 are at least 500 atmospheres to 0.10% at 1500 to 210 C. The pressures and preferably ,at
least 1000 atmospheres and below 3000 atmospheres. and 400 The temperatures are between 100 C. and more particularly from 150 C.
to 250 C. Thus, as a specific instance of obtaining the solid polymers, ethylene containing 0.05% oxygen is compressed in a steel bomb to a total pressure of 1500 rapidly to 210 C., whereup atmospheres and heated a ry udden Great Britain February 4,
change in pressure followed by a slow drop in pressure is observed. After five hours heating at 210 C. the pressure is released and the product cooled. Under these conditions an yield of the solid polymer, based on the ethylene used, is obtained.
The ethylene polymers obtained as outlined above melt within or above the range of about to about C., have an average molecu-,- lar weight in excess of 6000, are essentially saturated products corresponding in compositions substantially to (CH2), and when subjected to X-ray diffraction analysis show a crystalline structure. These polymers are soluble in xylene at its boiling point, are unaffected by prolonged contact with air at ordinary temperatures, and
' are characterized by the formed into films and filaments which yield oriented products on'application of stress herein referred to as cold drawing. The oriented products furnish fiber difiraction patterns on examination with X-rays and exhibit birefringence and parallel extinction when observed under crossed Nicol prisms.
The present invention consists in the application of the above-mentioned solid polymers of ethylene in the preparation of laminated glass. It has been found that solid polymers of ethylene having molecular weights in excess of 10,000 can be made to form a satisfactory bond with glass, and that the laminated articles so formed are substantially unaffected by changes in temperature and humidity which such articles encounter in service. Furthermore, the laminated glass is very good in resistance to the commonly applied break and crush tests, and sensitive to wide variations in temperature. In other words, it is shatter-proof. Depending on the use to which the laminated article is to be put, the interlayer may bra transparent, translucent, or opaque.
The-polymers mentioned above possess to an unusual degree the properties essential to the fact that they can be in this respect is not production of a successful laminated or safety indicated, films, filaments and the like prepared from the solid polymers of ethylene are further characterized by the fact that they yield oriented products on cold drawing; in general, cold drawing improves the toughness, elasticity, and utilthe molten polymers. Fjilms prepared in this manner are generally translucent unless theyare cooled by rapid chilling, e. g., by extruding the polymer in sheet form into a suitable quenching liquid such as water. This rapid chilling or tempering of the hot films also leads to a tougher product. Films can be prepared by fiowing solutions or emulsions of the solid polymers of ethylene on a suitable surface, as, for example, glass, and evaporating the solvent or by regenerating the film or sheet by extrusion into a suitable coagulating bath. Films obtained by these methods are also generally translucent, but they may be made transparent by rapid chilling of the hot films as above stated.
The laminated articles of this invention can be prepared in a number of Ways. A convenient method consists in placing a layer or sheet of the solid polymer of ethylene between two plates of glass and then pressing the plates together under the influence of heat and pressure. Although the thickness of the layer may be varied within wide limits depending upon the type of product desired, for most purposes layers of 0.015 to 0.050 inch thickness are'most desirable. The temperatures employed for this purpose should preferably be below the melting point of the polymer if transparent laminations are desired. After adhesion has been eifected, the article is allowed to cool to room temperature. Still an- 40 other method consists in flowing a solution of the solid polymer of ethylene on the glass plate,
evaporating the solvent or at least the major portion thereof, and then applying the other plate of glass. or a solution, polymer in the form of a powder may be used. The preferred method of efi'ecting lamination consists in applying a suitable adhesive to both sheets of glass, interposing there- 50 between a preformed sheet of polymer, and combining the two sheets of glass by means of heat and pressure.
The following examples in which the parts are by weight illustrate the invention more specifi- 'cally:
Example! Five-inch by five-inch plates of glass were sprayed with adhesive A, hereinafter described, and allowed to dry for 15 minutes at room tem- 0 perature. A coating of a toluene solution of an isobutylene polymer having a molecular weight of about 10,000 was sprayed over the treated glass and allowed to dry 4 hours at C. At the end of this time a sheet of an ethylene polymer having a thickness of approximately 0.02 inch and a molecular weight of about 18,000 was interposed between-two sheets of glass prepared as described above and the assembly heated to about 105 C. under a pressure of about 4 lbs. per sq. in. in a platen press.
in the press just long enough to melt the plastic. The assembly was then removed from the press and allowed to cool in air. The resultant'laminated glass shows shatterproofness not only at- 50 C., but also at 18 C.
The most useful solid poly- Instead of using a preformed mm The assembly was kept Example II A uniform layer of approximately 0.02 inch thickness made from a polymer of ethylene having a molecular weight of about 24,000 was placed on a clean plate. and the assembly heated to about C. -Another warm glass plate was then placed on the first plate and pressure was applied so that the ethylene poiymer formed an adherent interlayer of uniform thickness, and the sandwich allowed to cool to room temperature. The section of laminated glass thus formed was transparent. When the laminated article was struck a sharp blow, a number of radial cracks were formed but the section remained in one piece and still had considerable strength.
Example III A tetrachloroethylene solution of an ethylene polymer having a molecular weight of about 30,000 was poured onto an amalgamated tin plate and the solvent removed by evaporation on a steam heated plate. After most of the solvent had been removed, the plate was cooled and the sheeting stripped. A film was obtained 01' about 0.03 inch in thickness. Pieces of this sheet were then placed on thin tin plate sheeting and heated in an oven until, the material melted and all traces of solvent were removed. The sheets were then quenched rapidly in cold water. The films were then cold rolled to about 0.020 inch in thickness.
Pieces of five-inch by five-inch plate glass were sprayed with adhesive A described in Example I and allowed to dry 15 minutes at room temperature. The coated glass was then sprayed with a toluene solution of an isobutylene polymer having a molecular weight of about 10,000, and the treatedglass allowed to dry for 4 hours at 45 C. At the end of this time the sheet of the ethylene polymer prepared as described above was assembled between the treated glass sheets and the composite heated at 80 C. under a pressure of 50 lbs. per sq. in. The resulting laminated glass was shatterproof at 50 and at 18 C.
(7., room temperature,
Example IV Example V Two panes of window glass 2" x 5' x 54;" were heatedin an ovenat C. Strips of an ethylene polymer (molecular weight about 25,000)
0.20 inch by 0.03 inch thick were applied around the edge of one of the panes and allowed to melt so as to form a continuous border of ethylene polymer around the glass. The other glass pane was then superimposed on the first, the assembly gently pressed, and then allowed to cool to room temperature. A clear composite glass consisting place of adhesive A their low densitymakes it possible to use thinnerof two glass panes, 0.025 inch apart and separated by an air-tight, continuous film of ethylene polymer was obtained.
' Example VI To a hot glass pane 2" x5 x A,? was applied a border of ethylene polymer having a molecular weight of about 25,000 by laying around the edge of the glass a border of the aforementioned ethylene polymer in the form of strips 0.20 inch wide and 0.03 inch thick. The pane was allowed to cool to room temperature, the ethylene polymer edge treated with atoluene solution of an isobutylene' polymer'having a molecular weight of about 14,000, and the solvent allowed to evaporate at room temperature. A composite was prepared by placing over the treated glass another glass and applying pressure in order to cause the ethylene polymer-polyisobutylene film to form an adherent layer between the two glass sheets. The double pane thus obtained was transparent and air-tight.
The foregoing examples are not to be considered as limitative but as illustrative of the products of this invention and methods for their preparation.
Gelatin or plasticized casein may be used in used in Examples I and III.
The film or interlayer used in the preparation of the laminated glass articles of this invention need not. necessarily consist only of ethylene polymer. It is frequently desirable to use a softening or plasticizing agent in conjunction with the ethylene polymer. As an example of a suitable plasticizing agent for this purpose may be mentioned paraffin wax.
This invention provides a simple method for the preparation of laminated glass articles of great'utility. Since the ethylene polymer films have satisfactory bonding qualities, laminated glasses prepared therewith are characterized by strength and'durability. The good strength of the ethylene polymer interlayers, coupled within making burglar-proof glass.
glass and lighter interlayers than is possible in the case of plastic materials previously described for this purpose. This is not only an economic advantage but also an advantage in utility since it makes it possible to prepare laminated articles of less weight.
cause of their good strength and non-shattering properties are useful in safety glass in motor vehicles, airplanes, etc. The invention is also useful Another important' application of this invention is in the preparation of double window glass.
As many apparently widely merits of this invention may be made without departing from the spirit and scope thereof, it is to be understood that we do not limit ourselves to the specific embodiments thereof except as defined in the appended claims.
l. A laminated article comprising two sheets of glass having therebetween a film of a solid polymer of ethylene which melts at temperatures above 100 C. r
2. A laminated article comprising two sheets of glass having therebetween a film of a sold polymer of ethylene which melts at temperatures above 100" C., and which has a molecular weight of at least 6,000. I
3. A laminated article comprising two sheets of glass having therebetween a mer of ethylene capable of being drawn into fibers which upon X-ray examination show orientation along the fiber axis.
4. A laminated article comprising two sheets of glass having therebetween a filmof a solid polymer of ethylene which is solid at normal temperature, which corresponds in composition to (CH2); and which by X-ray difiraction analysis shows a crystalline structure.
ERI WILLIAM FAWCETT. REGINALD OSWALD GIBSON. MICHAEL WILLCOX PERRIN.
different embodi- Theproducts of this invention befilm of a solid polyv