NZ208855A

NZ208855A - Transparent polyurethane sheet and use in manufacture of laminated panes

Info

Publication number: NZ208855A
Application number: NZ208855A
Authority: NZ
Inventors: J-L Bravet; D Colmon; G Daude; M-J Moncheaux
Original assignee: Saint Gobain Vitrage
Priority date: 1983-07-11
Filing date: 1984-07-10
Publication date: 1987-10-30
Also published as: DE3468649D1; CA1245798A; FI77253C; HU212186B; ES8507380A1; ES534173A0; JPS6071213A; DK337284A; CS261870B2; FI77253B; IN160868B; AU3045584A; IL72361A; CS534984A2; BR8403427A; HUT40383A; FR2548956A1; NO161966C; PT78884B; PH23091A

Abstract

1. A sheet of transparent plastics material of high optical quality comprising a layer based on polyurethane having energy-absorbing properties, characterised in that the layer having energy-absorbing properties is formed essentially of a polyurethane obtained by reactive casting on a flat horizontal support of a reaction mixture of an isocyanate component of viscosity less than 5 Pas at 40 degrees C and a polyol component, the isocyanate component comprising at least one aliphatic or cycloaliphatic di-isocyanate or an isocyanate prepolymer, the isocyanate component containing urea functions, the content of urea being up to 10% of the total weight of isocyanate component, the content of urea preferably being from 5 to 7%, the polyol component comprising at least one long difunctional polyol of molecular weight from 500 to 4000 and at least one short diol as a chain lengthening agent, the ratio of isocyanate group equivalents to hydroxyl group equivalents is about 1, the proportions of the different polyols are selected such that the number of hydroxyl group equivalents due to the short polyol represents from 20 to 70% of the total hydroxyl groups, and this layer having at a thickness of about 0.5 mm, a flow stress sigma y at -20 degrees C not exceeding 3 daN/mm**2, a rupture stress sigma R at 40 degrees C of at least 2 daN/mm**2, a lengthening at rupture vepsiln R at + 20 degrees C from 250 to 400%, and a tear resistance Ra at + 20 degrees C of at least 9 daN/mm.

Description

<div class="application article clearfix" id="description"> New Zealand Paient Spedficaiion for Paient Number £08855 208855 ■u CrU: ' U-\:$5. . z: Z 'uZ'^3k- C08^S|6«...1«^3 ,... CO? JO I lS„ B02 BOjAQ.., 6 i!6 ll 1.UCT,. 6JC)C5Q|C?^. 3 0 OCT 1987 loci -^"T ■> i-' «. U'1 W •4 \ Q ^ _ NEW ZEALAJID^^;;".^ PATENTS ACTV+9Tf No.: Date: COMPLETE SPECIFICATION SHEET OF TRANSPARENT PLASTICS MATERIAL OF GOOD OPTICAL QUALITY 11 We, SAINT-GOB AIN VITRAGE, a French Company, of "Les Miroirs", 18 avenue d'Alsace, 92400 Courbevoie, France © hereby declare the invention for which Ix/ we pray that a patent may be granted to iftfe/us, and the method by which it is to be performed, to be particularly described in and by the following statement:- " 1 " (followed by page -la-) "! V O 2 0 8 b h o -1a- Sheet of Transparent Plastics Material of Good Optical Quality The invention relates to a sheet of transparent plastics material of good optical quality which may be used on its 5 own or in association with other materials, notably for manufacture of laminated panes comprising a glass sheet and at least one layer of plastics material, for example a vehicle windscreen, the sheet of plastics material having both properties of absorption of energy and properties of 10 resistance to scratching and abrasion. Sheets of plastics material which may be used in laminated panes of the above-mentioned type have already been suggested. Thus in UK Patent Specification 1576394 15 there is described a sheet having two layers, that is a layer of thermoplastics material which, in its application to laminated panes comprising a single sheet of glass, is an intermediate layer having properties of absorption of energy, and a layer of thermohardening material having 20 antilaceration and self-healing properties. The intermediate layer having properties of absorption of energy is a thermoplastic polyurethane obtained from at least one aliphatic di-isocyanate and at least one 25 polyesterdiol or polyetherdiol, the ratio of equivalent NCO groups to equivalent -OH groups being preferably from 0.8 to 0.9. A pane using such a sheet having two layers retains good optical properties and the adhesion between the elements remains good under very variable conditions 30 of temperature and humidity, but the bio-mechanical properties of the pane and especially resistance to shock are not entirely satisfactory. There is also known from European Patent Publication 35 0054491 a sheet having two layers which, may be used for making a laminated pane having the structure described above, the layer fulfilling the function of an -2- 20885 intermediate layer having properties of absorption of energy being based on a polyurethane-polyurea having a linear structure and a content of urea groups of the order of 1-20$ by weight, the polyurethane-polyurea being the 5 reaction product of a prepolymer obtained from a polyol component and an isocyanate component present in excess, with at least one diamine. This intermediate layer having properties of absorption of energy is made by extrusion of a polyurethane-polyurea resin or by casting of a solution 10 of said resin and evaporation of solvents, which in this case also requires a series of successive operation. In the case of extrusion it is necessary to carry out a previous synthesis of the resin to be able to extrude it. 15 Further, to obtain the optical quality necessary for the application envisaged it is necessary to re-pass the sheet. The optical quality obtained is not generally maintained with time as the plastics material retains in 20 its memory its method of manufacture and the properties retained on re-passage are diminished with time. Further, the extrusion of the layer having the properties of absorption of energy gives an assembly problem with the 25 self-healing layer. In the case of casting of a solution it is also necessary to carry out a previous synthesis of the resin. It is then necessary to dissolve the latter in a solvent and 30 cast the solution and evaporate the solvent in a repetitive manner to obtain a layer of thickness compatible with the desired character of absorption of energy. The evaporation of the solvent further constitutes a source of nuisance. 35 This invention suggests a new transparent sheet of high optical quality suitable for use on its own or in t '3 - \. \.V* -3- association with other materials and especially for manufacture of laminated panes as described above, this sheet comprising a layer formed j.n a continuous process of reactive casting, on a flat hoizontal support from which 5 it is detachable, from a reaction mixture of an isocyanate component and an active hydrogen component, notably a polyol component, the isocyanate component comprising at least one aliphatic or cycloaliphatic di-isocyanate or a di-isocyanate prepolymer, this component having a 10 viscosity less than about 5000 centipoises at +40°C, the polyol component comprising at least one difunctional long polyol of molecular weight from 500 to 4000 and at lest one short diol as a chain lengthener. By "reactive casting" is meant casting in the form of a layer or film O 15 of a liquid mixture of components in the monomer or prepolymer state, followed by polymerisation of the mixture by heat. This reactive casting which provides a layer having good mechanical and optical properties is described in greater detail below. 20 The proportions of polyurethane components are chosen to obtain preferably a balanced stoichiometric system, that is to say that the ratio of NCO group equivalents supplied by the diisocyanate component to OH group equivalents 25 supplied by the polyol component, that is to say the long polyol or polyols and the short diol or diols is of the order of 1. When the ratio NCO/OH is less than 1 the more _ it decreases the more the desired mechanical properties for the application become rapidly less satisfactory. 30 When all the components of the polyurethane are difunctional the lower limit of the ratio NCO/OH for obtaining satisfactory mechanical properties is about 0.9- When at least on one of the components is trifunctional, this low limit may be lowered to about 0.8. 35 When the ratio NC0/0H is greater than 1, the more it increases the more certain mechanical properties of the layer obtained by reactive casting are increased, for r ) -r>\ ~ r---~ -4- example the layer becomes more rigid, but given the higher cost of the isocyanate component relative to that of the polyol component, the choice of ratio NCO/OH substantially equal to 1 is a good compromise between the properties obtained and the cost. The proportions between the long polyol and the short diol may vary as a function of the desired properties and also the ratio of the group equivalents, the number of OH group 10 equivalents due to the short diol however representing generally from 20 to 70% of the total group equivalents of the mixture forming the polyol component in the case when the ratio of the NCO group equivalents to the OH groups is of the order of 1. When the proportion of short diol is ^5 increased the layer is hardened and its modulus is generally increased. Suitable diisocyanates which may be used in the invention are chosen notably from the following aliphatic 2Q difunctional isocyanates: hexamethylenediisocyanate (HMDI), 2,2,4-trimethyl-1,6-hexanediisocynate (TMDI), bis 4-isocyanatocyclohexylmethane (Hylene W), bis 3-methyl-4-isocyanatocyclohexylmethane,2,2 bis(4-isocyanatocyclohexyl) propane,3-isocyanatomethyl-3,5,5 trimethylcyclohexyl-25 isocyanate (IPDI), m-xylylenediisocyanate (XDI), m- and p-tetramethylxylylenediisocyanate (m- and p-TMXDI),trans-cyclohexane-1,4 diisocyanate (CHDI), and 1,3 (diisocyanato-methyl)-cyclohexane (XDI hydrogenated). 30 IPDI is preferably used notably for reasons of cost. According to one embodiment of the invention, there is used an isocyanate component containing urea functions. These urea functions improve certain mechanical 35 properties of the layer. The content of urea nay represent up to about 10% of the total weight of isocyanate component having urea functions. Preferably :r -j :x 2088 5 5 the content of urea is from between 5 and 7% of the total weight of said component. For the reason mentioned above there is preferably used 3-isocyanatomethyl-3j5,5 trimethylcyclohexylisocyanate comprising the urea 5 functions (IPDI and derivatives). The long polyols which are suitable are chosen from polyetherdiols or polyesterdiols of molecular weight 500-4000; the polyesterdiols being products of 10 esterification of a diacid such as adipic, succinic, palmitic, azelaic, sebacic, orthophthalic acid, and a diol such as ethyleneglycol, propanediol -1,3,butanediol - 1,4,hexanediol-1,6 and polyetherdiols of general formula 15 H £ 0 (CH2)n J m 0H m wherein n = 2 to 6; m is such that the molecular weight is from 500-4000, or the polyetherdiols of general formula 20 CH3 H - 0CH - CH2 - m OH where m is such that the total of the molecular weight is from 500-4000. It is also possible to use 25 polycaprolactonediols. There is preferably used polytetramethyleneglycol (n = 4) of molecular weight 1000. 30 The lengthening agents for the chains which may be used include short diols of molecular weight less than about 300 and preferably less than 150, such as: ethyleneglycol, 1,2-propanediol, 1,3-propanediol, 1,2, -1,3 or -1,4 butane-diol, -dimethyl-2,2 propanediol 1,3 35 (neopentylglycol), 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, 1,12-dodecanediol, cyclohexanedimethanol, bisphenol A, methyl-2 pentanediol-2,4, methyl-3 pentanediol- 2,4, ethyl-2 hexanediol-1,3, 2 0 8 h b u -6- trimethyl-2,2,4-pentanediol-1,3, diethyleneglycol, tri-ethyleneglycol, tetraethyleneglycol, butyne-2-diol-1,4-butanediol-1,4 and decynediol which are substituted and/or etherified, hydroquinone-bis-hydroxyethylether, bisphenol A etherified by two or four propylene oxide groups, and dimethylolpropanic acid. In general the shorter the diol the harder the layer obtained. Preferably there is used 1,4-butanediol which is a good 10 compromise between obtaining a layer which is not too hard or too flexible which is desired for this type of application as an energy absorber. One of the characteristics of the layer having the 15 properties of absorption of energy is that it is obtained by reactive casting on a planar horizontal support. This reactive casting of which a form is already described for example in UK Patent Specification 2038228 ' to obtain a layer of thermohardening polyurethane from a mixture of 20 trifunctional components provides in surprising manner according to the invention in the case of starting components which are difunctional a layer which is not entirely thermoplastic when the ratio of NCO/OH groups is substantially equal to 1. 25 Reactive casting implies a rapid polymerisation reaction for the layer to be formed in a time compatible with industrial application. This requires a high temperature of the order of about 80 to 140°C, approximately, a 30 temperature at which the secondary linking reactions are produced creating for example allophanate and/or biuret groups between the urethane chains such as: 35 v ii*. ,-N * - fj 2 SEP 198/; t; * 5 10 15 20 25 30 35 : :1 '3 5 S r-nh-c0-0-r' -0 ocn - r - nco r-nh-co-o-r' - 0 r / Ji - co o - r' - 0 , co ' allophanate >h'' \° r_N-co-r' -o- or - R" - NH - CO - NH - R" - OCN - R - NCO - R" - NH - CO - NH - R" - -.4 - - - R" - CO - NH "f R" - ' CO l I » NH ^ -"biuret «\ - -R / NH / CO \ - R" - N - CO - NH - R" - In these operating conditions, even with difunctional components, when the ratio NCO/OH is substantially equal to 1 as indicated previously, the product obtained is not completely thermoplastic, in fact it is infusible and insoluble in the majority of solvents for polyurethanes such as tetrahydrofuran and dimethylformamide. This does not present any disadvantage as the film or sheet is already formed; on the other hand, advantage is taken of the improved mechanical properties of the equal formulation with respect to an equivalent system polymerised at low temperature when only a linear polycondensation is produced. When the ratio NCO/OH is less than 1 and of the order of 0.8 to 0.9, a crosslinking of the type described above is not produced to any significant extent. In one embodiment of polyurethane layer having properties of absorbtion of energy, the polyol component may contain a small proportion of at least one polyol of functionality greater than 2 and especially monomeric aliphatic triols such as glycerol, trimethylolpropane, triols having polyether chains, triols of polycaprolactone, the molecular weight of the triols being generally from 90 to 1000, mixed polyether/polyester polyols of functionality greater than 2, for example functionality between 2 and 3-The addition of a polyol of functionality greater than 2 creates additional bridging linkages between the polyurethane chains and may thus improve the cohesion of the layer. The proportions between the long polyol, the short diol and possibly the polyol of functionality-greater than 2 may vary according to the desired properties. There are generally chosen proportions such that for one hydroxyl equivalent, the long polyol represents about 0.3 to 0.45 equivalent, the short diol about 0.2 to 0.7 equivalent and the polyol of functionality greater than 2 about 0 to 0.35 equivalent. Under these conditions, the layer has the following mechanical characteristics measured according to standards*AFNQR NFT 46.002, 51.034 and 54.108: - a stress at the start of flow 0 y at -20°C not 2 exceeding 3 daN/mm , - a stress at rupture 0""^ at +40°C not less than 2 daN/mm^, - an elongation at rupture at +20°C from 250 to 500%, - resistance to start of tearing Ra at + 20°C greater than or equal to 9 daN/mm thickness. * available on request 20885b "9- It is also possible to make the layer replacing a part of the polyol component with a different product having active hydrogens such as an amine. 5 According to one embodiment of the layer of plastics material according to the invention, the isocyanate component may contain in limited quantities, for example less than 15% of NCO equivalent, at least one tri-isocyanate such as an isocyanate biuret or a tri-10 isocyanate. According to one aspect of the invention, the sheet is formed of a single layer described above. In fact this layer has properties of absorption of energy, as mentioned 15 above, and properties of resistance to scratching and abrasion making it suitable for use as an exterior layer. Thus, it has a resistance to scratching greater than 20 grams, a value measured by the test described below, and a resistance to abrasion with a difference in haze less than 20 this value being measured by the abrasion test described below. To fulfill all the functions required of it, the layer according to the invention should have a thickness 25 generally greater than Q.4mm and preferably greater than 0. 5mm. In a variant, the sheet according to the invention comprises in addition to the layer described above, a 30 layer of self-healing plastics material, that is to say resistant to scratches and abrasion. The self-healing covering layer resistant to scratching of plastics material which is designated in this application 35 as an interior protection layer (PI layer) is for example described in UK Patent Specifications 1436384 and 1461817. This self-healing layer has under normal conditions of temperature a high capacity for elastic . o\\ //*' | **2SEPJ987,!; V» // (v V ■" ^ ^ -10- deformation, a small modulus in elasticity less than 2000 2 2 dN/cm and preferably less than 200 daN/cm , and a lengthening at rupture of more than 60? with less than 2% of plastic deformation and preferably a lengthening at rupture of more than 100? with less than 1% plastic deformation. Preferred layers of this type are thermohardening polyurethanes having a modulus of elasticity of about 25 to 200 daN/cm2 and a lengthening of about 100 to 200^ with less than 1? of plastic deformation. Examples of monomers which are suitable for preparation of these thermohardened polyurethanes are on the one hand aliphatic difunctional isocyanates such as 1,6-hexanedi isocyanate ,2,2,4-trimethyl-1,6-hexanediisocyanate, 2,4,4-trimethyl-1,6-hexanediisocyanate, 1,3-bis(isocyanatomethyl) benzene, bis (4-isocyanatocyclohexyl) methane, bis (3-methyl-4-isocyanatocyclohexyl)methane, 2,2-bis(4- isocyanatocyclohexyl)propane and 3-isocyanatomethyl-3j5,5-trfmethylcyclohexylisocyanate, as well as the biurets isocyanurates and prepolymers of these components having a functionality of 3 or more and on the other hand polyfunctional polyols such as branched polyols such as the polyesterpolyols and polyetherpolyols obtained by reaction of polyfunctional alcohols, notably 1,2,3-propanetriol (glycerol), 2,2- bis (hydroxymethyl)-1-propanol (trimethylolethane), 2,2- bis (hydroxymethyl)-1-butanol (trimethylolpropane ) 1,2,4-butane-triol, 1,2,6-hexane-triol, 2,2-bis(hydroxymethyl)-1,3-propane-diol (pentaerythritol) and 1,2,3,4 ,5,6-hexane-hexol (sorbitol), with the aliphatic diacids such, as malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, and sebacic acid or with the cyclic ethers, such as ethylene oxide, 1,2-propylene oxide and tetrahydrofuran. The molecular weight of the branched polyols are advantageously about 250 to 4000 and preferably about 450 to 2000. Mixtures of different polyisocyanates and 2 0 8 b o monomeric polyols may be used. A particularly preferred thermohardening polyurethane is that described in UK Patent Specification 1461817. The choice of thickness of the layer having properties of absorbtion of energy (AE layer) and that of the self-healing layer (PI layer) and the ratio between these two thicknesses are important factors. According to the invention the total thickness of the two superposed layers is greater than 0.5mm with a thickness of at least 0.4mm for the layer having properties of absorbtion of energy. Further, the adhesion between this layer and the sheet of glass should be greater than about 2 daN/5cm, a value measured using a peeling test as described below. This force of adhesion should not however be too high, especially when there is used an AE layer of relatively small thickness close to the lower usable limit of about 0.4mm. The layer having properties of absorption of energy may contain various additives which generally serve to facilitate its manufacture by reactive casting or which may possibly, as the case requires, further improve certain of its properties. It may contain a catalyst such as a tin catalyst for example dibutyltin dilaurate, tributyltin oxide, tin octoate, or an organomercuric catalyst for example mercury phenyl ester, or an amine catalyst, for example diazabicyclo(2,2,2)-octane, or 1,8 diazabicyclo (5,4,0)-1 decene-7. The layer may contain a stabiliser such as bis (2,2,6,6-tetramethyl-4 piperidyl) sebacate, or a phenolic antioxidant. The layer may also contain a spreading agent such as a G*\ silicone resin, a fluoroalkyl ester, or an acrylic ester. 2 SEP 1987 S| 5 10 20 2088 5 To make the sheet of this variant having two layers the following method may be used: . There is first made a first layer which may be either the 5 adhesive layer having properties of absorption of energy (AE layer), or a layer of self-healing plastics material for interior protection (PI layer) formed notably of a thermohardening polyurethane. And on this first layer, there is formed a second layer. 10 It is thus possible to make first of all a layer of thermohardening polyurethane by casting of . a mixture of components on a casting support. After polymerisation of the monomers and formation of a thermohardening layer of 15 thickness which may vary from 0.1 to 0.8mm, the mixture of reaction components of the layer having properties of absorbtion of energy is cast. It is also possible to work in reverse, that is to say by 20 first forming the layer having energy absorption properties (AE layer). To make a laminated pane which uses the sheet of one or two layers according to the invention, the elements are 25 assembled by using pressure, for example by squeezing between the rollers of a calender, and by the action of heat. It is possible to improve the connection of the elements 30 later by subjecting the laminated pane to an autoclave cycle, for example"one hour at a temperature of about 100 to 140°C and under a pressure of about 3 to 15 bars, or by a stoving, cycle. 35 -Examples of manufacture of laminated panes according to the invention are described in the following. 208855 -13- Example 1 On a moving glass support passing in continuous manner, coated with a separation agent which may, for example, be that described in UK Patent Specification 1590512, that is to say a modified addition product of ethylene oxide, there is cast a homogeneous mixture with the following proportions of: - 1000 g of a polyether of molecular weight of about 450 obtained by condensation of 1,2-propylene oxide with 2,2-bis (hydroxymethyl)- 1-butanol and having a content of hydroxy free radicals of about 10.5 to 1256 containing 1% by weight of stabiliser, 0.05? by weight of a catalyst, that is dibutyltin dilaurate and 0.1? by weight of a spreading agent. - 1020 g of a biuret of 1,6-hexanediisocyanate having a content of free isocyanate radicals of about 23.2?. There is used a casting head such as that described in UK Patent Specification 1562767. There is formed a uniform layer which after polymerisation under the effect of heat, for example about 15 minutes at 120°C, has a thickness of about 0.19mm and self-healing properties. To make the layer having properties of absorption of energy there is first prepared the polyol component by mixing a polytetramethyleneglycol of molecular weight 1000 (for example the product sold commercially under the name Polymeg 1000 by the QUAKER OATS Company), with 1,4-butanediol, the proportions of the two constituents being such that the polytetramethyleneglycol supplies 0.37 equivalents in hyd^oxyl groups whereas the butanediol-1,4 gives 0.63. 208b5b I' * -14- w In the polyol component there is incorporated a stabiliser in an amount of 0.5? by weight of the total weight of the polyol component and the isocyanate component, a spreading agent in an amount of 0.05? by weight calculated in the 5 same way and a catalyst that is dibutyltin dilaurate in an amount of 0.02? by weight calculated in the same way. The isocyanate component used is 3-isocyanatomethyl-3j5,5-trimethylcyclohexylisocyanate (IPDI) having urea O 10 functions obtained by partial hydrolysis of the IPDI and having a content of free NCO groups of about 31-5? by weight. I The components are taken in quantities such that the 15 NCO/OH ratio is 1. After degassing in vacuum of the components the mixture brought to about 40°C is cast by means of a casting head, as described in UK Patent Specification 1562767, 20 the layer of self-healing polyurethane formed previously. There is thus formed a layer of about 0.53mm thickness which is subjected to a polymerisation cycle consisting of 25 minutes heating at about 120°C. 25 The sheet of two layers is withdrawn from the glass support and it may be manipulated easily, stored and used immediately afterwards for manufacture of laminated panes according to the invention. p 30 To make the pane, there is assembled the sheet having two layers obtained previously with a glass sheet which is heated of 2.6mra thickness. The glass may possibly be ' hardened or tempered. The assembly as mentioned above may be carried out in two stages, a first, stage consisting of 35 preliminary assembly obtained by passage of the elements forming the pane 'between two rollers of a calendar. For this purpose there may be used for example a device o j s -r / * -15- described in European Patent Publication 0 015 209, the AE layer being applied against the internal surface of the glass and a second stage consisting of disposing the laminated product obtained in an autoclave, where, for 5 about an hour it is subjected to a pressure of about 10 bars at a temperature of about 135°C. This autoclave cycle may possibly be replaced by a stoving cycle without increased pressure. 10 The pane obtained has excellent optical quality and perfect transparency. The adhesion obtained between the glass sheet and the layer having the properties of absorption of energy is 15 measured for the manufactured pane by a peeling test described below. There is cut a strip of 5cm width from the covering sheet having two layers. An end of the strip is unstuck and 20 there is applied thereto a pulling force perpendicular to the surface of the glass with a pulling speed of 5cm per minute. The operation is carried out at 20°C. The force of traction necessary for unsticking of the strip is noted. Operating thus there is obtained a traction force 25 of 10 daN/5cm. Trials for resistance to shock at different temperatures are carried out on the pane made according to this example. 30 The first trial for resistance to shock is carried out with a steel ball of weight 2.260kg (heavy ball test) which is caused to fall on the central part of a square sample of laminated glass of 30.5cm side, held on a rigid 35 frame. There is determined the approximate height from which 90? of the samples tested at the chosen temperature resist fall of the ball without the ball passing through. '5 ".X 0 -16- For the laminated pane according to the example the value obtained is 8 metres. Another trial for resistance to shock is carried out with 5 a steel ball of 0.227kg and 38mm diameter. A trial is carried out at a temperature of -20°C, another carried out at a temperature of +40°C. The values obtained are respectively 11 and 13 metres. 10 Taking account of European standard*R 43 which is now in force, the desired results are at least 4 metres with the heavy ball, at least 8.5 metres with the light ball at -20°C and at least 9 metres with the light ball at +40°C. O 15 The PI layer exhibits surface properties which are adequate for use in a laminated pane and especially a resistance to scratching and abrasion measured as described below: 20 The resistance to scratching is measured-using a scratch test called "MAR resistance test" using an ERICHSEN type 413 machine* There is measured the load required for a diamond head to give a persistent scratch on a layer of the plastics material supported by a glass sheet. The 25 load should be at least 20 grams for the layer of plastics material to have self-healing properties. 30 Resistance to abrasion is measured according to European Standard R 43. A sample of the pane is subjected to abrasion using an abrasive mill. After 100 rotations of the mill there is measured with a spectrophotometer the difference in haze between the abraded and non-abraded parts. The difference in haze (Ahaze) should be less than 4? for the layer to have anti-abrasive properties. A pane according to the example has all the !4SEPl987^ Characteristics rendering it suitable as a windscreen for a vehicle. * details available on request 2088 55 -17- Comparison Example The procedure of Example 1 is followed with the same starting components and the same proportions for manufacture of the AE layer except that this layer is not 5 obtained by reactive casting but by a plurality of successive castings of a solution of polyurethane prepared by synthesis in solution in order to obtain a thickness of 0.53mm. 10 Trials for resistance to shock carried out under the same conditions as Example 1 provide the following values: - 3.5 metres with a heavy ball, 4 metres and 3 metres with a light ball at respective temperatures of -20°C and 15 +40°C. The peeling test provides a value of 8 daN/5 cm. ! j These values are insufficient which shows that the 20 reactive casting used in Example 1 gives the AE layer the j i desired properties. ( \ i Example 2 The procedure of Example 1 is carried out except that 25 there are made layers with different thicknesses, that is a self-healing layer (P I) of 0.41mm thickness and an AE layer of 0.29 mm thickness. The laminated pane obtained has the following 30 characteristics: The peeling test gives a value of 10 daN/5cm. The heavy ball test and the two tests with a light ball give respective values of 3-5, 9 and 9 metres which is 35 insufficient. These poor values are due to the insufficient thickness of the layer having properties of absorption of energy. -X v. > 2088 5 -18- Example 3 The procedure of Example 1 is followed, except that there is made a P I layer of 0.315 mm thickness and an AE layer of 0.415mm thickness. 5 The peeling test gives the value of 10 daN/5cra. The tests with the heavy ball and the light ball give respective values of 4.5, 10 and 13 metres which is satisfactory. 10 Example 4 The procedure of Example 1 is carried out except that there is made a PI layer of 0.32mm thickness, an AE layer of 0.42mm thickness and the surface of the glass before assembly is subjected to a known treatment with an 15 adhesion promoter such as a silane to obtain a higher value of adhesion. The peel test gives a value of 20 daN/5cm. The heavy ball test gives a value of 3.5 metres. This value for 20 resistance to shock which is insufficient is due to an adhesion which is too strong of the AE layer to the glass in the case where this layer has a relatively small thickness. This example is to be compared with Example 3> which despite the use of layers of the same thicknesses 25 provides a satisfactory pane owing to a smaller force of adhesion. Example 5 The procedure of Example 1 is carried out except that 30 there is made a PI layer■of 0.46mm thickness and an AE layer of 0.56mm thickness and the glass is treated for assembly as in Example 4. The peeling test provides a value of 20 daN/5cm whereas 35 the tests with the heavy and light ball give respective values of 8, 11.5 and 13 metres. I. >" ^ ^ rr^ rr:, P=- ■% -19- t '■ J j) This example is to be compared with Example 4. It shows that despite a strong adhesion, the use of the AE layer of high thickness provides satisfactory values of mechanical resistance. 5 Example 6 The procedure of Example 1 is carried out except that the starting polyol component for the AE layer is formed of a mixture of polytetramethyleneglycol of molecular weight 10 1000, 1,4-butanediol and polycaprolactotriol (for example the product sold under the name Niax 301 by UNION CARBIDE), in relative proportions such that for a hydroxyl equivalent there is used 0.35, 0.55 and 0.10 equivalents in the respective polyols. 15 There are made layers of 0.160mm thickness for the PI layer and 0.660mm thickness for the AE layer. The pane obtained has optical and mechanical 20 characteristics which are completely satisfactory. The values measured for different tests are as follows: an adhesion of 3 daN/5cm, and values of ball tests of 9, 13 and 13 metres. 25 Example 7 The procedure of Example 6 is followed except that the proportions of different polyols are respectively 0.35 OH equivalents for the Polymeg 1000, 0.45 OH equivalents for the 1,4-butanediol and 0.20 OH equivalents for the Niax 30 301. There are made layers of 0.31mm thickness for the PI layer and 0.48mm thickness for the AE layer. 35 The values measured in tests are as follows: an adhesion of 3 daN/5cm, values of 4.5, 10 and 12 metres for balls, which is satisfactory. Example 8 The procedure of Example 7 is followed except that there are used thicknesses of 0.39mm for the PI layer and 0.39mm for the AE layer. 5 The values measured are as follows: an adhesion of 4, values of 3, 8 and 8 for the balls, which is insufficient. This example compared with Example 7 shows that for a same 10 thickness for the sheet having two layers there exists a ratio of thickness between the AE layer and the PI layer which, according to the value, gives a pane which may or may not be satisfactory. 15 The following examples relate to a variant of the sheet of the invention formed of a single layer and to panes using it. Example 9 20 To make the layer of plastics material, there is first prepared the polyol component by mixing a polytetramethylene glycol of molecular weight 1000 (for example Polymeg 1000 produced by the Quaker Oats company) 25 with butanediol-1,4, the proportions of the constituents being such that the polytetramethylene glycol supplies 0.37 equivalent of hydroxy groups whereas the butanediol-1,4 supplies 0.63. 30 There is incorporated in the polyol component a stabiliser in an amount of 0.5? by weight of the total weight of polyol component and isocyanate component, a spreading agent in an amount of 0.05? by weight calculated in the same way and a dibutyltin dilaurate catalyst in an amount 35 of 0.02? by weight calculated in the same way. The isocyanate component used is 3-isocyanato methyl 3,5,5 trimethylcyclohexyldiisocyanate (IPDI) having urea functions obtained by partial hydrolysis of the IPDI and -2i- 2 08855 having a content of NCO groups of about 31-5% by weight. The components are used in quantities such that the NCO/OH ratio is 1. After degassing under vacuum of the components, the mixture at 40°C is cast using a casting GG Kt a/o ifkttf? head such as described in -French1 Patent—PubliGation ■ ■23|I717&, on a moving glass support covered with a separating agent. There is thus formed a layer of homogeneous thickness of about 0.755mm, which is subjected to a polymerisation cycle, that is to say a temperature of 120°C for about 25 minutes. After polymerisation the layer is removed from the glass support and forms a sheet which may be stored or used immediately afterwards for making laminated panes. To manufacture the pane the sheet of plastics material is assembled with a sheet 2.6mm thick of heated glass. The glass may be hardened or tempered. This assembly may be carried out in two stages, as described in Example 1. The pane obtained has excellent optical quality and a perfect transparency. The adhesion obtained between the glass sheet and the polyurethane layer is 10 daN/5cm. Trials for shock resistance at different temperatures are carried out on the pane of this example. For the laminated pane the value obtained with a heavy ball at +20°C is 12 metres. Shock resistance trials using the light ball give at -20°C a value of 12 metres and at +40°C a value of 11 metres. The scratch resistance for the pane of this example is 32 grammes. 20885 -22- The layer according to the example has a haze difference after abrasion of 0.94?. Example 10 5 The procedure of Example 9 is followed except that the polyol component is formed of a mixture of polytetramethylene glycol of molecular weight 1000, butanediol-1,4 and polycaprolactonetriol (for example as 10 sold commercially as Niax 301 by Union Carbide) in proportions suoh that, for one equivalent of hydroxyl, these components contribute 0.35, 0.45 and 0.20 respectively. 15 There is made a layer of 0.70mm thickness.' The pane obtained has mechanical and optical characteristics which are satisfactory. The values obtained on testing are: - adhesion of 11 daN/5cm, values of 8 metres with a 2o heavy ball, 11 and 11 metres respectively with a light ball at -20°C and +40°C, - a resistance to scratching of 35g and a haze difference on abrasion of 1.2?. 25 Example 11 The procedure of Example 10 is followed except that the polyol component is formed of 0.35 equivalent parts of 30 long polyol, 0.55 parts of short diol and 0.10 parts of triol for 1 equivalent of polyol component. There is formed a layer of 0.66mm thickness. The values obtained with different tests are: 35 - adhesion of 11 daN/5cm, values of 10 metres with a heavy ball, 13-5 and 15.5 metres with a light ball at -20°C and +40°C respectively, a scratch resistance of 25°C, and a haze difference on abrasion of 1.2?. </div>

Claims

<div class="application article clearfix printTableText" id="claims"> -23- jp The sheet of the invention has been described in connection with laminated panes but it may be used with advantage in other applications, either alone or with other transparent or opaque materials. Example 12 The procedure of Example 1 is. followed except that polymerisation of the layer is carried out at 60°C for 20 hours. Shock resistance trials carried out as in Example 1 give the following values: - 6 metres with heavy ball, 6 and 13-5 metres with light ball at -20°C and +40°C respectively. The value obtained with the light ball at -20°C is not sufficient. This result shows the effect of the polymerisation temperature used during reactive casting. In this case the temperature is too low. '{I'' 2086 WHAT,j^Wb CLAIM k- _24_ -Claims

1- A transparent sheet of plastics material of high optical quality comprising a layer having properties of 5 absorption of energy and formed essentially of a polyurethane obtained by reactive casting, on a flat horizontal support, of a reaction mixture of an isocyanate component having a viscosity less than 5000 centipoises at +40°C and a polyol component, the isocyanate component 10 comprising at least one aliphatic or cycloaliphatic di-isocyanate or diisocyanate prepolymer, the polyol component comprising at least one long difunctional polyol of molecular weight from 500 to 4000 and at least one short diol as a chain lengthening agent, the short diol having 15 molecular weight not exceedinq 300.

2. Sheet according to claim 1, characterised in that the isocyanate component contains urea functions, the amount of urea being up to 10% of the total weight of isocyanate component, the amount of urea being preferably from 5 to 20 7%. 3. Sheet according to one of claims 1 and 2, characterised in that the isocyanate component comprises 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate . 25 4. Sheet according to one of claims 1 to 3, characterised in that the isocyanate component and the polyol component of the polyurethane having properties of absorption of energy are used in such quantity that the 30 ratio of the isocyanate group equivalents to hydroxyl group equivalents is about 1. 5. Sheet according to one of claims 1 to 4, characterised in that the proportions of the different 35 polyols are chosen such that the number of hydroxyl group equivalents of the short diol is 20 to 70$ of the total of -25- ^08855 the hydroxyl groups when the ratio of the OH group equivalents to NCO equivalents isof the order of 1. 6. Sheet according to one of claims 1 to 5, characterised in that the isocyanate component is formed essentially of

3-isocyanatomethyl-3,5,5- trimethylcyclohexylisocyanate having urea groups formed by partial hydrolysis and in that the polyol component is formed essentially of polytetramethyleneglycol of molecular weight about 1000 and butanediol-1,4. 7. Sheet according to one of claims 1 to 6, characterised in that the polyol component comprises at least one polyol of functionality greater than 2. 8. Sheet according to claim 7, characterised in that the polyol of functionality greater than 2 is a triol. 9. Sheet according to one of claims 1 to 8, characterised in that for one total hydroxyl equivalent for the polyol component of the polyurethane having properties of absorption of energy, the long polyol contributes 0.30 to 0.45 equivalent, the short diol 0.2 to 0.7 equivalent and the polyol of functionality greater than 2, 0 to 0.35 equivalent. 10. Sheet according to one of claims 1 to 9, characterised in that the polyurethane layer having properties of absorption of energy comprises a catalyst, spreading agent and a stabiliser. 11. Sheet according to one of claims 1 to 10, characterised in that the adhesion between the layer having properties of absorption of energy and a glass sheet is greater than 2 daN/5cm. ' 10 208855 -26- 12. Sheet according to one of claims 1 to 11, characterised in that the layer of plastics material having properties of absorption of energy has at a thickness of about 0.5mm a stress at the start of flow CT"y at -20 C not more than 3 daN/mm , a stress at rupture CJ^R at + 40°C greater than 2 daN/mm2, an elongation at rupture £ R at +20°C from 250 to 500% and a resistance at the start of tearing Ra at +20°C greater than or equal to 9 daN/mm. 13. Sheet according to claim 12, characterised in that the sheet of plastics material having properties of absorption of energy has a scratch resistance greater than 20g and an 15 abrasion resistance such that the haze difference is less than 4%. 14. Sheet according to one of claims 1 to 13, characterised in that it also comprises a self-healing 20 layer based on a thermohardening polyurethane. 15. Sheet according to claim 14, characterised in that it has a thickness of at least 0.5mm, with a thickness of at lest 0.4mm for the layer having properties of absorption 25 of energy. 16. Sheet according to one of claims 1 to 15, characterised in that the layer of polyurethane having properties of absorption of energy is obtained by 30 polymerisation at a temperature between 80° -140°C during reactive casting. 17. Sheet according to one of claims 1 to 16, characterised in that the isocyanate . component also 35 comprises at least one tri-isocyanate. I *2sfP/9«7„;-27-;208855;10;18. Application of a sheet of transparent plastics material according to one of claims 1 to 15 to the manufacture of laminated panes.;19. Application of a transparent sheet of plastics material according to claim 18, characterised in that the laminated pane comprises only one glass sheet and said sheet of plastics material. ,-,fk d SE;DATED THIS-//^ DAY 0? rklJMA'V 19 S"7;»PAH a £VSGU 7m TilG ArFL:."A?iT3;15;—';20;25;30;35;i* l-2S£Pl9S7^ </div>