Patent GB-1174311-A (GB)
Title: Polypivalolactone Fibres and a method for their manufacture
IPC: D01F6/62
Filed: 1967-05-02
Abstract: 1,174,311. Polypivalolactone fibres. KANEGAFUCHI BOSEKI K.K. 2 May, 1967 [2 May, 1966; 23 Aug., 1966], No. 20279/67. Heading B5B. An undrawn fibre consisting essentially of polypivalolactone having an intrinsic viscosity # of at least 0-7, a degree of orientation R of at least 0-85, and an elongability of at least 200% is drawn at a draw temperature T‹ C. in the range defined by the conditional equation: 220 # T # 10. Copolymers prepared by copolymerizing polypivalolactone with up to 25 mol per cent of other lactones e.g. #-propiolactone and α-α-diethyl propiolactone can also be used, as may polypivalolactone blended with other polymers which do not substantially effect the properties of polypivalolactone. The intrinsic viscosity is determined in 6 :4 by weight phenol : orthochlorophenol at 30‹ C, and the degree of orientation R is determined from X-ray diffraction data for the fibres, by a method disclosed in the specification. Preferably, the draw temperature T‹ C. is also within the range defined by the conditional equation: T # -282 + 1744R - 1605R<SP>2</SP>. Desirably, the fibres are made by melt-extruding, through a spinneret orifice having a diameter of at least 0-3 mms. and at an extrusion temperature in the range between 240‹ and 310‹ C., a polymer consisting essentially of polypivalolactone and having an intrinsic viscosity of at least 0-7 and by applying a high stretch to the extruded polymer while the latter is still in the molten or plasticized state so that the spinning deformation ratio A has a value satisfying the conditional equation: A # 1367[#]<SP>-5.612</SP>. The resulting drawn fibre may be elasticized either by heat-treatment or swelling treatment until said drawn fibre has a degree of orientation R of at least 0-9, a degree of crystallinity X of at least 50%, (preferably at least 55%), a long period D of at least 70A (preferably at least 80Š), and an average length La of the amorphous part of at least 30Š (preferably at least 40Š). The drawn fibre, whether or not elasticized may be subjected to a conventional mechanical crimping treatment at a heat-set temperature in the range between 120‹ and 220‹ C, preferably between 140‹ and 200‹ C. Undrawn fibres treated as above should preferably have a retention of elongation of at least 94% at the end of one hour from the time the undrawn fibre is spun, and at least 85% at the end of 24 hours. Where elasticizing is performed by heat-treatment, the heat-treatment should be performed at a predetermined temperature and for a period of time sufficient for the heat-treated fibre to retain a degree of tensile recovery of at least 50% at 50% elongation, (preferably at least 90% at 50% elongation), and a retention of tensile strength of at least 50%. Said heat-treatment may be performed at a temperature in the range between 100‹ and 150‹ C, preferably between 125‹ and 150‹ C. Said heat-treatment may be steam heating or wet heating. Alternatively, the heat-treatment may be dry heating and the temperature of such heat-treatment is then desirably in the range between 150‹ and 220‹ C, the duration of said heat-treatment satisfying the equation: # # 0À00808#<SP>2</SP>-3À15# + 307-6 and also the equation: # # 4À35#<SP>2</SP>-1677# + 161460 where T represents the duration in minutes of said heat-treatment; 0 represents the temperature ‹C. of said heat-treatment. In a preferred dry-heating heat-treatment, the temperature is in the range between 170‹ and 220‹ C, the duration of said heat-treatment being in the range satisfying the equation: ##-0À00271#<SP>2</SP>-1À05# + 319À6 and also the equation: # # 4À35#<SP>2</SP>-1677# + 161460 Where elasticizing is effected by swelling treatment, this is suitably conducted with a swelling bath containing at least one organic compound active to polypivalolactone, i.e. compounds capable of swelling polypivalolactone or capable of dissolving in polypivalolactone, dissolved or dispersed in a liquid medium inert to polypivalolactone. Specified organic compounds include phenol, orthochlorophenol, metachlorophenol, parachlorophenol, orthocresol, metacresol, and paracresol, and their derivatives, chlorinated hydrocarbons, e.g. monochlorobenzene, dichlorobenzene, trichlorobenzene and tetrachlorobenzene, halogenated aliphatic acids, e.g. trichloroacetic acid and trifluoroacetic acid, dimethyl carbamyl compounds, e.g. dimethyl formamide and dimethyl acetamide, dimethyl sulphoxide and nitrobenzene. Such swelling agents may be dissolved or dispersed either singly or in the form of a mixture of two or more of them in the inert liquid medium which may include a solvent as e.g. water, alcohol, glycerine or acetone, or in a dispersion medium, to form a swelling bath. The organic compound is suitably dissolved or dispersed in said liquid medium in a proportion of at least 0-5% by weight of the total weight of the solution or dispersion. A preferred organic swelling bath comprises a high concentrated solution of phenol, metacresol or a mixture thereof, at room temperature. Alternatively, a swelling bath comprising a dilutesolution of chlorophenol at room ternperature may be used. Alternatively, elasticizing may be performed by swelling treatment using as a swelling agent an aqueous solution of at least one inorganic compound selected from the group consisting of chlorides and metals contained in Group II of the Periodic Table, thiocyanates and inorganic acids, said inorganic compound being active to polypivalolactone. A preferred inorganic swelling bath comprises a substantially saturated aqueous solution of at least one inorganic salt selected from the group consisting of chlorides and metals contained in Group II of the Periodic Table and thiocyanates. Specified inorganic compounds include zinc chloride, calcium chloride and magnesium chloride, calcium thiocyanate, potassium thiocyanate and ammonium thiocyanate, and inorganic acids, e.g. sulphuric acid, hydrochloric acid and nitric acid. Fibres so made have an intrinsic viscosity of at least 0À7, a degree of orientation R of at least 0-85 and are preferably at least 0À9, a degree of crystallinity not exceeding 58% and preferably of at least 50%, and especially of at least 55%, a tensile strength of at least 3-5 g.p.d. an initial modulus of at least 20 g.p.d. preferably at least 30 g.p.d., and desirably at least 40 g.p.d., a degree of tensile recovery of at least 90% at 5% elongation and preferably, in addition, of at least 50% at 50% elongation, or alternatively may have a degree of tensile recovery of -at least 90% at 5% elongation and of at least 90% at 50% elongation. Such fibres may have a modulus of at least 0-2 g,p.d. immediately after the yield point in the load-elongation curve, and preferably have a long period of at least 70Š, desirably at least 80Š, and an average length of the amorphous part of at least 30Š desirably at least 40Š, and may have a retention of modulus of at least 70% desirably at least 75%.