Europaisches Patentamt J European Patent Office © Publication number: 0 189 873 B1 Office europeen des brevets © EUROPEAN PATENT SPECIFICATION @ Date of publication of patent specification: 14.08.91 © Int. Cl.5: C08L 27/24, C08L 33/12 © Application number: 86100994.2 © Date of filing: 24.01.86 © Method and composition for improved melt processability of chlorinated polyvinyl chloride. Priority: 28.01.85 US 695765 @ Proprietor: The B.F. Goodrich Company 600 South Main Street Date of publication of application: Akron Ohio 4431 8(US) 06.08.86 Bulletin 86/32 © Inventor: Lehr, Marvin Harold Publication of the grant of the patent: 1252 Briarhill Spur 14.08.91 Bulletin 91/33 Akron, OH 4431 3(US) Designated Contracting States: DE FR GB IT ® Representative: von Kreisler, Alek, Dipl.-Chem. et al References cited: Deichmannhaus am Hauptbahnhof DE-A-1 669 911 W-5000 Koln 1(DE) CHEMICAL ABSTRACTS, vol. 75, no. 8, 23 August 1971, Columbus, OH (US); p. 37, no. 50071 t CHEMICAL ABSTRACTS, vol. 85, no. 26, 26 December 1976, Columbus, OH (US); p. 37, no. 193633v 0Q 00 oo a oo Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition LJJ shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid (Art. 99(1) European patent convention). Rank Xerox (UK) Business Services EP 0 189 873 B1 Description FIELD OF THE INVENTION 5 This invention relates to chlorinated polyvinyl chloride and to methods for enhancing the melt processability of chlorinated polyvinyl chloride. More particularly, this invention relates to blends of chlorinated polyvinyl chloride with other polymeric materials providing enhanced melt processability. -v Specifically, this invention pertains to miscible blends of chlorinated polyvinyl chloride with other polymeric materials providing enhanced melt processability. 10 BACKGROUND OF THE INVENTION While polymer blends have been reported in the literature from time to time, only within the past generation have polymer blends become sufficiently numerous and the advantages of polymer blends 75 sufficiently apparent to warrant widespread investigation. While originally considered rare, miscible polymer blends more recently have been noted with increasing frequency. Miscible blends of a second polymer and a first polymer have found utility in providing enhanced properties such as plasticization, tensile strength, melt processability, and increased resistance to heat distortion. Particularly in applications where polymeric materials are to be subjected to injection molding conditions, it is desirable that the modifying polymers 20 blended into a polymer being injection molded be miscible in the first polymer; miscibility enhances the opportunity for avoiding weld-line strength difficulties and defects in finished, injection molded parts. The prediction of miscibility between polymer pairs is still an art in infancy; miscibility is believed dependent upon a number of factors that include reactions between functional moieties pendant from one or more of the polymers, hydrogen bonding, and the like. Various suggestions have appeared for assisting in 25 the selection of miscible polymer pairs including an application of Flory's equation of state as set forth by L. P. McMaster, 6 Macromolecules, 760 (1973). Other suggestions for useful tools in assessing miscible polymer pairs have included: two-dimensional solubility parameters, inverse gas chromatography; crystallization characteristics of polymer blends; and evaluation of glass transition temperature shifts, as suggested by L. M. Robeson, 24 Polymer Engineering 30 and Science, p.p. 589 (June 1984). That the prediction of miscible polymer pairs is still an art, rather than a science, is indicated by, for example, by chlorinated polyethylene having 42 weight percent chlorine being miscible in polyvinyl chloride, while chlorinated polyethylene havng a chlorine content less than 42% being immiscible in poiyvinyl chloride as shown by Robeson, supra, at p.p. 588. The prediction of properties of miscible blends is also uncertain. While some blend properties such as 35 tensile strength may follow simple additivity rules, for example as noted for polycarbonate/polyester blends by Joseph, E.A., et al 23 Polymer p.p. 112 (1982), other blends may show synergistic enhancement of tensile properties as discussed by Olabisi, O., et al, 176 Adv. Chem. Serv., p.p. 559 (1979). Blends characterized by the components being immiscible typically are found to exhibit a tensile strength minimum while blends having components characterized by slight miscibility and a dual glass transition temperature 40 may exhibit both a tensile minimum and a maximum as discussed by Fried, J.R. et al, 50 Journal of Applied Physics, p.p. 6052 (1979). There is some significant indication that polymer blends tend to exhibit partial miscibility, and that graphical depictions of such partial miscibility tend to be of the minimum solution temperature type, that is those solubility curves having a minimum critical solution temperature below which a polymer pair exists in 45 miscible state and above which, two phases are present, one phase being rich in a first polymer and the second phase being rich in a second polymer; Robeson, supra, p.p. 588. One possible explanation for a lack of solubility between polymer pairs may, in some cases, be related to the minimum critical solution temperature being lower than a glass transition temperature for one or both of the polymers; the polymers being below a glass transition temperature; a melt state for one or both of the polymers being non existent. 50 A number of substances forming a miscible melt with polyvinyl chloride have been identified in the " literature, Robeson, supra, at p.p. 588, however, chlorinated polyvinyl chloride appears to have received * less attention. Polyvinyl chloride and chlorinated polyvinyl chloride being chemically different compounds and particularly where properties of a miscible blend of two polymers is in part dependent upon such factors as hydrogen bonding and pendant functional moieties, the simple fact that polyvinyl chloride forms a ^ 55 miscible pair with a second polymer is not a particularly good indicator that chlorinated polyvinyl chloride will also form a miscible pair with the second polymer. While chlorinated polyvinyl chloride is possessed generally of performance characteristics and, particu- larly temperature performance characteristics, superior to polyvinyl chloride, enhanced performance char- EP 0 189 873 B1 acteristics associated with a blend of chlorinated polyvinyl chloride and a second polymer together in a miscible melt state could find substantial industrial utility. Chemical Abstracts 85, (1976) 193633v discloses a mixture of 40 parts polymethylmethacrylate and 60 parts chlorinated polyvinyl chloride with a chlorine content of 64 %. The softening point of the final blend of ° 5 102 C is the same as that of the chlorinated polyvinyl chloride component. DE-A-16 69 911 discloses a mixture of polymethacrylate and chlorinated polyvinyl chloride with a chlorine content of 63 % in a 1 : 1 ratio. As a second component to be used with chlorinated PVC having a chlorine content of 60-67 % polymethylmethacrylate is disclosed. 10 DISCLOSURE OF THE INVENTION The present invention provides a composition of matter that is a substantially homogeneous single phased material comprising a blend of chlorinated polyvinyl chloride having a chlorine content not less than 60 % nor greater than 66 % by weight and polymethylmethacrylate, the polymethylmethacrylate comprising 75 not more than 80 % by weight of the blend, the blend being possessed of a single glass transition temperature that is greater than the glass transition temperature predicted by application of the Fox ° equation which is greater by at least 3 C than either of the components and the chlorinated polyvinyl chloride has a weight average molecular weight of from 73.000 to 140.000 and the polymethylmethacrylate has a weight average molecular weight of from 27.000 to 71 .000. 20 The composition of the instant invention is melt processable, is a substantially homogeneous substan- tially single phased material and demonstrates a glass transition temperature substantially in excess of that predicted by the so-called Fox equation, as described by Couchman, P.R., 11 Macromolecules, p.p. 1156, (1978). The composition of the instant invention is substantially homogeneous notwithstanding heating to a 25 temperature of at least 200 °C and typically, remains homogeneous to a temperature of not less than ° 230 C. The composition, upon being formed into a structure by melt processing techniques and subse- quent cooling at a rate not less than 40 °C per minute, typically is substantially free of weld-line weaknesses. Blending chlorinated polyvinyl chloride and PMMA in a proportion not exceeding 80% by weight PMMA 30 at a temperature and under suitable pressure conditions whereby the chlorinated polyvinyl chloride and PMMA are substantially miscible, forms a single, substantially continuous phase. The resulting blended chlorinated polyvinyl chloride/PMMA possesses improved flow characteristics in the melt state, a substan- tially singular glass transition temperature, improved weld-lined fault properties, and enhanced heat distortion temperature. 35 The above and other features