IL25314A - Stable,stretch-oriented light polarizing polymeric film and method of and compositions for manufacturing it - Google Patents

Description

LIGHT POLARIZING POLYMERIC FILM AND METHOD OF AND COMPOSITIONS FOR MANUFACTURING IT This invention relates to a method of manufacture of films and and more particularly to a method forming articles capable of polarizing ligh passing of an The manufacture of polymeric films and polarizing and birefringent articles i the form of films and fibres is well known in the presently known ing films and fibres which are made by stretching and dyeing high polymer plastics are subject to several Some of these shortcomings result from the materials employed and others from the manner in which these articles are These polarizing films or fibres generally lack sufficient and in the presence of elevated tures and and satisfactory weathering In the prior art two kinds of stretch have been taught for orienting and crystallizing polymeric materials containing long chain These two types of stretching have been described in terms of the state of the polymer employed at the time of the stretching operation as state and elastic In the the linear high polymers are in a condition in which they contain little or no solvent or and are not at too elevated a The techni e whi h o V extended is often referred to as The term drawing does no to the temperature of the polymeric material but refers to an extending o the material in a condition which is below the softening 5 or melting point of the While the materials are said to be in the whe the cules of the polymer must have sufficien slip be tended without In this respect the state of the linear high polymer must be distinguished from 10 state which is not capable of being In the case o the stretch there is a tendency for the oriented or crystallized strip to retract or collapse almost to its original length upon or upon in a swelling The 15 traction occurs because at higher temperatures the random vibrations induced in the molecular structure are cient to break apart weak bonds holding the crystalline structure and the same true by the introduction o strong solvents whic enter in between the aligned 20 weakly bound crystalline lattice and break it apart by swelling The solvent molecules enter between the stretched long chain which may be compared to a plurality of elongated weak coil and the release of the forces tending to hold them in permits 25 them to retract toward their original high polymers stretched in the state have been described as having the properties of vulcanized are placed in this by the addition thereto of a considerable proportion of solvent some o the linear high polymers will also present the elasticity which has been characterized by the term Linear high polymers which are in the state have further compared to canized rubber in that when the force stretching said mers is the material will immediately return to almost its original It has been observed that linear h gh polymers which are in a condition characterized by the term when subjected to yield rather uniformly as does a rubber band and continue to stretch throughout the application of the force until they reach the limit of She orientation improves slowl at stretch everywhere along stri being and does not substantial or high orientation until stretched very near the limit of The method or process by which the molecules were stretched or the condition of the material when stretched does not affect or bring about the behaviour or tendency to of the originally randomly oriented in order to achieve it is necessary to produce a condition of stretch as hereinafte set it is an object of the present vention to provide oriented meric sheets and which articles will overcome the deficiencies of presently known Another object of the present invention is to vide birefringent and light polarizing of high optical plastic suppor and form a and stable surface further of present invention is to provide a polarizing film which will not or in the presence of heat or Still a furthe object of the invention is to provide a method of preparing able birefringent and light polarizing Yet another object of the instant invention is to provide a crystallising composition for making such She foregoing of the invention are achieved herein a process for preparing actable polymeric and also light polarizing and birefringent In accordance with this there is provided compositio including by weight of a organic by weight of an inorganic polymer which is capable of binding chemically with the polymer when light izing films are by weight of a in a suitable composition vided then applied to a casting surface and dried form film of random oriented a portion of the film is grasped and extended away from the casting thereby aligning the organic polymer molecules of the extended portion in a direction substantially parallel to the longitudinal axis of the extended the inorganic polymer constituent of the is brought in proximate and parallel physical relationship with the organic polyme As a result of this to its parallel positioned organic polymer chain neighbor by a chemical proximity reaction between functional groups present in each of the polymer the materiel o the if crystallizes with the to produce a light polarizing In the accompanying drawings forming part of the present 1 is a top plan view of a strip of polymer material prepared in accordance with the present inventio showing the manner i it is abruptly changed from the solid amorphous state into a crystalline oriented state by an irreversible cold drawing FIGURE 2 is a view in side elevation of the stretching operation shown in FIGURE 1 with the respective film thicknesses magnified for the sake of FIGURE is a force diagram the cess of FIGURE FIGURE is a fragmentary view of a portion of FIGURE 2 greatly enlarged showing somewhat the manner in which the simultaneous alignment and binding steps of invention acts to produce a permanently oriented polymeric film or FIGURE is a flow sheet which summarizes the sequence of process steps of the present Referring to the and particularly to FIGURES 1 and there is shown the generalized procedure for forming permanently oriented polymeric films in ance with the present A support such as V holds a filffl 12 which has been cast solution and stantially dried to most of the volatile A uniform tension indicated the arrow is applied to a portion of the film such as the strip or fibre 15 which 5 has been lifted from the easting surface resulting in strip or fibre velocity casting surface may also move forward at a velocit during the cess shown in FIGURES 1 and In this invention the velocity is so regulated that line along which the 10 film strip 13 leaves the support hereinafter referred to as the line of is maintained in a stationary position the oriented material drawn off at a velocity at the line of takeoff at which place the film suddenly diminishes in and the film 15 abruptly oriented within a microscopic distance of tion indicated at Over this small the thickness diminishes from with the relationship a She width of the film diminishes more slowly from to and may be as 20 A preferred thickness t of the order of and the distance equals where k is of the order of 1 to As shown the force diagram of the component of force is normal to the surface the angle Θ in FIGURES 2 and is the angle between the extended portion of the film 13 and the casting surface 14 starting with the line of takeoff keep the component of force the angle Θ must also be of the order of the adhesion of the cast film to the force She component of small to keep the film 2 from lifting off the surface at the line of takeoff It has been discovered that the angle of Θ is quite important as a control the stretch ratio since greater stretch ratios be achieved at smaller angles and vice the force is used primarily for extending the f lm which is in the solid state without li ting the balance of the unoriented portion of the 12 from the surface ratio the order of 2 to 10 depending upon the materials the angle and the velocity of the sion Referring now to and there is trated the improved process of forming lms in accordance with the present FIGURE is a pictorial representation of the cess is a schematic diagram in which the steps are summarized in As shown in these the first step in the improved process herei is the formation of a polymeric For the sake of compositions suitable for casting polymeric films or birefringent films without dichroic will be called crystallizing Compositions for easting light polarizing films or fibers will be called polarizing It will be that both compositions are crystallized according to the present Both the and crystallizin compositions are prepared from the following constituents in the CRYSTALLIZING OR COMPOSITION by Weight organic polymer Inorganic material W agent Solvent The linear organic polymer constituent of crystallizing or polarising composition is a long chain such as is know in the which in the state will resist drawing forces a period of ing which the force and then stretch or yield quite suddenly givin an abrupt and highly uniform alignment of the molecules along the line of stretch almost She organic polyme possesses functional groups which will hind chemically with inorganic polymer as will he described in detail A preferred functional group is although o and the may be considered useful this purpose as Another desirable characteristic of the organic polymer constituent is solvent rit the organic as will be apparent to those skilled in the Suitable organic polymer materials include high molecular weight vinyl polyvinyl such as polyvinyl polyvinyl i the including polyvinyl tyral and and other stretchable rming polymers may used as Polyvinyl alcohol is a ticularly useful material because it is stretchable in the solid state and possesses functional side chains which are capable o condensing well with the residual groups of the inorganic It also has a particular affinity for diehroic Suitable inorganic polymers contain residual groups such as those mentioned above for the organic mer which will graft itself to the oriented organic Suitable ar the or equivalent structures formed from phosphorous and the including the acid phosphates and polyphcsphoric polymers and mixtures Fiv to ten percent polytitahate intermixed with a greatly decreases water penetration in the finished most cases it is preferred to utilize substituted derived from isopropyltitanate and titanium which may be pared by methods known to the Sio L a The polyailoxanes general formula where S is including h biphenylyl and terphenyl and a is greater than zero but less than polymers have residual silanol or groups which can form of organic The presence of the inorganic polymer constituent of the provides a highly oriented will not be adversely influenced by polymeric crystal which is compact and by siderable temperature or solvent Polymeric films and light polarising products of exceptional stability in the presence of heat and and with completely and stretch may be produced containing a high proportion of inorganic materials present in varying tions from 30 to of the total weight of the polarizing The nature of the dichroic material is no Any such material known in the art may be A particularly effective dichroic substance is which will intercrystallisse well with the polymeric Others include the class of chemical compounds ciated with direct cotton She amount of dichroic material employed may vary depending upon the kind of polarizer needed and the nature of the dichroic material it has been found that ranges between parts by weight of the position are the most In products such as meric birefringent no dichroic material or The presence of either the plasticlzer the agent the crystallizing or izing compositions is Satisfactory results can be obtained with certain compositions without The She plasticizer generally comprises a liquid monome reacts with either the Inorganic or th organic For which tially acts a temporary will react with a 5 siloxane polymer and remain structure after to provide a suitable polarizing film product ing to this Other include ethylene ethylene hexae and ene ethanol ethanol formamide 15 and Where iodine is used as the dichroic for a crossllnking agent such as acid or borax is very Other known crossllnking such as titanium glyoxal and 20 disocyanate also may be employed to farther insolubilize the solvent in this composition will depend upon the particular polymeric Generally prises mixtures of water and alcohols although other such as may be used as It is preferred in the case of alcohol mixtures to choose an such as or which will evaporate at approximately the as other alcohols which may be selected same so the solvent composition will not be In connection with the generalized composition set forth it is desirable that the polymer constituents be kept within the ranges For when the amount of linear organic polymer is below 30 the composition loses the physical strength necessary for extension and the tion becomes too When the amount of linear organic polymer exceeds 60 parts by on the other the composition lacks the advantages of the ing properties of the inorganic Also when the position contains less 30 parts by weight of the organic the finished product may retract or iorate under certai conditions of hea or than parts by weight of inorganic polymer in the position may result in a mixture which is too brittle to when more than 20 parts by weight of a temporary plasticiaer is the finished or cast film is no sufficiently hard and is less This structure swells and retracts when exposed to She alignment produced at the line of takeoff during sion also is not as irreversible as Each constituent is prepared separately and the mixed together to form the desired ably mixing is out in a certain For it desirable to first combine both polymer constituents thereafter add the dlchrolc material with stirrin til the solution is uniform and flows There may be a certain tendency for the solution to gel at The solutions thus prepared are usually stable stored and may he several days irreversible ing The polarizing solution prepared above is then pressure filtered through a porous ceramic filter and e tated furthe to render the solution homogenous in Bubbles are allowed to and when the solution is free from which takes about the tion is ready for upon a suitable After casting the composition is dried for a period of At this juncture the produced will be substantially dry and in the solid the molecules of the are completely randoml This process is schematically illustrated in PIGUEE 4 which is casting 12 is the amorphous cast 21 and 22 are long Organic polymer molecules having reactive side groups indicated by lines 25 and intermixed therewith is an inorganic pelymeric material schematically illustrated by the thicker lines 23 and 24 groups shown as lines These molecules are present In this region in a randomly configuration in space constituting an of an amorphous When the casting mixture it becomes the cast film 13 is continuously extended and away the casting surface along a straight line Illustrated in FIGURES 1 and In the region shown as on the drawing in 4 over the distance by the material being into parallelism as In the region shorn at in FIGURE the organic polymer has 21 and 22 become fully aligned in a direction substantially parallel longitudinal axis of the tended Simultaneously the inorganic polymer cules and within the are brought into proximate reactive physical relationship with the oriented organic polymer preferably in parallel ship as shown in the molecules of the polymers are drawn parallel so that the functional groups along parallel can reac in situ and thus permanently bind chains together by strong chemical upon a condensed polymer chain 28 is within the reaction0 actually constitutes a new metestable state of matter in which the are dormant in the amorphous and are caused to react as soon as a degree o alignment orientation or crystallihity is achieved by the of linear high polymer into parallelism whereby th components to the actio brought into closer physical Such reaction or has the effect of producing a reversibl In other a material which is simultaneously to the is thereafte resistant to heat or solvent action cannot subsequently be caused to retract with its a possible return to the The dichroic material then is in ing characteristics to the It is believed that the of the atoms or molecules dichroic material become arranged betwee the active groups of the long chain organic mer As the film pulls away from the casting it immediately becomes neutral in shade and and possesses excellent polarising The film may be withdrawn from the casting surface and tended The polarizing fil at this point can be slightly for short time and caused to here to curved if For it is possible to laminate the polarising film shortly after production directly to a curved lens surface to produce ing Due to the residual solvents still remaining in the and to groups as yet adhesion to tain such as glass or is readily tained by chemical when the film is allowed to dry or when expulsion of residual solvent is hastened by for example for 2 hours at followed by to 10 minutes at an extremely hard insoluble surface lamination This lamination does not retract under further heating or solvent action and is stable to general weathering In the proximity a second chemical compound may be formed by condensation which is then removed from the For if hydrogen and alkoxide groups are a free alcohol is produced which porates from the surface in the form of vapor alternative materials may be employed achieve similar also certain variations and which yet withi the the present 1 A polarizin composition is prepared from the following CC and AA Parts Weight High molecular weight polyvinyl alcohol 200 200 600 Powdered polyvinyl alcohol is first mixed into a paste with the alcohol and and then the distilled water added with The composition c then heated with continued stirring to about for several hours until solution is The solution is then filtered through a filter to produce a clear POLYMER BB Parts by Weight plus 150 850 he mixture of the in mixture a stoichiometric concentration of dilute acid reacted completely by subjecting the components to violent tion so that sufficient is achieved to start the reaction whereafter it proceeds to The is During and after the agitation stage the solution rises in temperature to about temperature maintained or a period of about one hour by placing the material in an air oven at this The solution is allowed to cool to room temperature and stored fo about one week at about during which time it thickens and gels due to the of A solution prepared is more stable and gels less quickly than solutions containing a lower tration of the purpose this process this solution can be used up to 4 or days if stored at such low So prepared the ethylorthosilicate comprises two or more monomelic cules joined together by the elimination of the ethyl The silicon atoms are joined by bridges and by reactive into a linear polymeric inorganic chain known as a By this technique a concentration of almost polysilicate in a solution of ethyl alcohol only is Compositions prepared from this solution have a high solids content which permit the of comparatively thick Diehroio rial CO farts by Weight Iodine 200 800 prepare the iodine is added to the the composition heated to the mixture is thereafter agitated until all the iodine is After cooling the solution is filtered through a fritted and Parts by Boric Acid boric acid is highly soluble in the glycerine and is only stirred and filtered t h a Solutions AA and then are mixed together and thereafter Solution is added and stirring tinued a uniform solution is thereafter Solution 00 is added and stirring continued until the solution is uniform and flows Polarizing Composition EE Solution Solution Solution Solids Solids Total AA BB Solids in Total Solution Equals Upon extending polarising composition EE in the manne of the process steps described in detail a stable light polarizing film of high durability and solvent temperature resistance is A crystallizing composition is prepared as in by mixin Solutions A and and then adding Solution extending this able physical characteristics of the light polarizing is A polarizing prepared by Solution AA and B and thereafter adding Solution Upon extending this composition upon a casting surface in the manner a light polarizing film is 4 equivalent quantities of polyvinyl acetate polyvinyl polyvinyl pyrrollidine copolymer polyvinyl copolymer are substituted for polyvinyl alcohol Examples oriented birefringent and light polarizing films are EXAMPLE Using equivalent quantities of polyzirconates and polyphosphates in place of polyslloxane in Examples there are provided birefringent and light polarizin films which are temperature and solvent EXAMPLE 6 When the concentration of Solution AA is varied between 30 and 60 parts by weight of the total Solution BB between 70 and parts by Solution GC between parts by and between parts by weight in the above Examples there are obtained the insufficientOCRQuality

Claims (1)

1. Claims A of manufacture of polymeric film which comprises the steps o orming a composition including at least 30 and not more than 60 parts by weight of a linear organic polymer having reactive functional and not more than 70 and at least 30 parts by weight of a polymer having an inorganic skeletal structure and reactive functional groups in a reactive solven said the functional groups said polymer having an inorganic skeletal structure being reactive with the functional groups of said organic polymer only upon the molecules of said organic applying said composition to a castin drying said composition to form a film of randomly oriented progressively lifting said from said simultaneously with said exerting a stretching tension on said and elongating said by said stretching tension sufficiently to align the molecules of said organic polymer and the molecules of said polymer having an inorganic Skeletal structure in proximate alignment parallel with the direction of said ing whereby said functional groups of said linear polymer reac with said functional groups of polymer having organic skeletal structure to stabilize film in elongated A method according to claim 1 wherein the is rendered light polarizing by the addition in the composition of a A method according to claim 2 the parallel arranged polymer molecules are chemically bound immediately after A method according to claim 2 wherein the polymer having an inorganic skeletal structure is reactive with said organic polyme to a linked and includes the steps reducing the thickness of the ly linear flm to form a of reduced thickness reacting the parallel aligned molecules chemically in A method according to claim wherein the organic polymer is a containing high molecular weight vinyl A method according to claim wherein said organic polymer is polyvinyl said polymer having an inorganic skeletal structure is a and said material is A method according to any one of claims 2 to 6 wherein said dlchroic material is present in and not more than by weight based on the total weight of the components of the A method according to claim wherein said composition includes not more than 20 parts weight a temporary and not more than 2 parts by weight of a acid or A composition the manufacturing of polymeric comprising at least 30 and no more than 60 parts by weight of a linea organic polymer having reactive functional not more tha and at least 30 by of a polymer having an inorganic skeletal structure and reactive functional groups a solvent for said the groups of said polymer having an organic structure being reactive with the functional groups of said organic polyme only upon of the molecules of said said solvent being present in amoun to form a orming A compositio according to claim 9 including not more than 20 parts by weight of a A according to wherein the plastielzer ie a high boiling solvent capable of reacting with at least one of the polymeric A composition according to claim 1 wherein the plastielzer A composition according to includes up to 2 parts by weight of a linking boric acid or A composition according to 9 Wherein the is rendered polarizing by the addition of to b weight of a dichroic material based On the total weight o components of said A according to claim 1 wherein the organic polymer la polyvinyl inyl alcohol inyl acetai or a vinyl alcohol aery A composition according to claim wherein the polymer having an skeletal structure is seleoted from phosphates or A composition according to claim wherein the organic polymer has functional groups selected from or and said polymer having an inorganio skeletal structure has functional groups which include those mentioned A composition according to claim wherein the side group of the organic polymer is hydroxyl and the side group of the polymer having an inorganic skeletal structure is A composition accordin claim including not than 20 parts by weight of a and not more than 2 parts by weight of a A composition as claimed any of claims 9 to 1 which comprises of polyvinyl of a of of boric acid and o glycerine in a solvent comprising of the above solids to the balance of said percentages being by weight based on the total weight of the components of said A film rendered light polarizing by a dichroio and comprising a copolymer from a composition comprising at least and not more than 60 parts by weight of a linear organlo polymer having reactive functional groups and not more than 70 and at least 30 parts b weight of a polymer having an inorganic skeleta structure and reactive functional groups in a reactive solvent for said and at least 5 and not more than 25 parts by weight of the said dichroio A film according o claim 21 wherein said organic polymer is a substantially linear high molecular weight vinyl A film according to 21 wherein said organic polymer polyvinyl alcohol and said is a A film according to claim prepared from a solution wherein th solid content of the solution is about by weight A film according to claim 21 wherein it is elongated by a stretching tensio sufficient to align the molecules o said organic polymer and the moleoules of said polymer having an Inorganic skeletal structure in proximate alignment parallel with the direction of stretching A method of manufacture of polymeric film substantially as herein described with reference to the accompanying A composition for the manufacture of stable oriented polymeric film substantially as herei described with reference to the accompanying A substantially as herein described with reference to the accompanying A product produced in accordance with the method of any one of claims 1 to 8 insufficientOCRQuality