Classifications

• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
  • D01D5/00—Formation of filaments, threads, or the like
  • D01D5/28—Formation of filaments, threads, or the like while mixing different spinning solutions or melts during the spinning operation; Spinnerette packs therefor
  • D01D5/30—Conjugate filaments; Spinnerette packs therefor

Definitions

• Self-crimping bicomponent polypropylene filaments are made by conjugate melt spinning two different polypropylene polymers in side-by-side or sheath-core relationship and subsequently relaxing the filaments.
• the polymers have the same intrinsic viscosity but different molecularwe ght distributions.
• Enhanced crimp is effected by drawmg the filaments.
• This invention relates to a process for the production of self-crimping polypropylene filaments or filamentary yarn.
• Filaments or filamentary yarn according to the invention are described as self-crimping for upon release of the tension applied to them during melt-spinning or the subsequent .cold-drawing. steplthey contract and take-up a helically crimped form.
• the tension may be maintained in the filaments between and subsequent to these processes .by, for example, winding the filaments or filamentary yarn on to bobbins and then released at an appropriate stage in the subsequent textile processing.
• self-crirnped staple fibres may be produced bygcutting an uncrimped yarn or tow into staple lengths while allowing relaxation to take place.
• the filamentary yarn may be subjected to a mechanical crimping process before releas- 3,399,259 Patented Ang. 27, less ice ing the tension to impede the self-crimping effect sufficiently to facilitate subsequent textile proeessir ig.v
• self-crimping filaments or filamentaryv yarns produced as in this invention may show theself-crimping effect in the as-spun condition, the effect is much enhanced by drawing the as-spun filaments, preferably tomore than twice but not more than about four times their original length at a temperature not exceeding about C.
• the degree of crimping -effect obtained upon relaxation may be controlled independently of the composition of the composite fibres by. regulating the temperature of the snubbing surface '(pin or roll) upon which drawing is effected. As the temperature'of the snubbing surface is increased so the crimping effect obtained is decreased until at about 100 C. little crimping is achieved.
• a draw ratio of 3.521 we obtained the following results for percentage crimp under a load of 0.5 mg./denier as the temperature of the snubbing surface, in this case a heated feed roll, was increased.
• melt-spinning apparatus for conjugate spinning of side-by-side or sheath-core composite filaments
• such equipment may be used to form composite polypropylene filaments according to the invention.
• side-by-side and sheath-core refer to the relationship of the two components in the individual filaments and the term conjugate spinning refers to the production of such composite filaments.
• the dispersion coefficient, Q which is an expression of the molecular weight distribution of a propylene polymer, is the ratio of weight average molecular weight, MW, to number average molecular weight, fin.
• Benzene was thereafter used as a standard for converting the photomultiplier reading to the absolute scattering intensity by the equation where R, is the Rayleigh ratio of the solution (corrected for solvent scattering) at any angle 0, R is the Rayleigh ratio of pure benzene, I, is the instrument galvanometer deflection forthe solution in excess of that of the solvent, 1,, is the galvanometer reading for pure benzene,
• Sin and (l-l-cos 0) are cor- -mometer made by Dohrman Instrument Co. to a Shell rection factors for the volume of scattering at angle 0 and the use of unpolarised light respectively.
• the membrane was conditioned by immersion for not less than 6 hours in the following sequence of solvent mixtures; water, water/ethanol, ethanol, ethanol/ acetone, acetone, acetone/methyl ethyl ketone (MEK) MEK, MEK/ toluene, toluene, toluene/decalin and decalin.
• the membrane was then conditioned for high temperatures by first of all securing it in position is the osmometer and filling the solvent and solution compartments with solvent. The temperature in the osmometer was then raised by 30 C. stepsuntil a temperature of C. was reached allowing 8 hours conditioning at each temperature.
• the solvent used for the measurements, decalin was vacuum distilled prior to use and oxidation was inhibited 'by the addition of 0.1% w./v. of a phenolic antioxidant.
• Polymer solutions (with a concentration chosen so as to give a pressure head of at least 1.2 cm. of solvent) were prepared at C. in pre-calibrated volumetric flasks and the solutions so prepared were filtered, prior to injection into the osmometer, at 130 C. through two thicknesses of 0.8 Millipore membrane filters (Millipore Corporation of America). The injected solutions were allowed 5 minutes to equilibrate in a 'pre-heater in the osmometer before being allowed to enter the solution compartment wherein a further 10 minutes'equilibration time was allowed. I
• the instrument zero was established by repeatedly filling the solution compartment with solvent and measuring the pressure head each time on the manometer servo read-out dial, the instrument zero being taken as satis factory when three readings agreed to within $0.01 cm. of solvent. The sample outlet was then closed and the equilibrium pressure reading was taken after about 40 minutes. The process was then repeated for another portion of the same solution, whereafter the instrument zero was re-established in the foregoing manner. As solute diffusion was always found to be present, the initial and final instrument values did not agree and the diiference in these readings was used to correct the final solution concentration reading for diffusion. j I
• Polymers having different molecular weight distributions may be produced in several ways. Thus thermal degradation of polypropylene from a higher to a lower viscosity will cause a narrowing of the molecular weight distribution, the product then being used as one component of a composite filament, the other component being, for example, a polymer which has been subjected to a lower degree of degradation. Alternatively a polymer manner in which it may be performed.
• the degree of crimp achieved by (a) substantially free relaxation (0.01 mg./denier) and (b) under a load of 0.5 mg./denier, which is the order of the resistance to relaxation in a loosely twisted multifilamentary or staple fibre yarn such as would be used for example for hand knitting purposes.
• a) substantially free relaxation (0.01 mg./denier) and (b) under a load of 0.5 mg./denier which is the order of the resistance to relaxation in a loosely twisted multifilamentary or staple fibre yarn such as would be used for example for hand knitting purposes.
• a load 0.5 mg./denier
• Conjugate melt spinning apparatus having means for separately supplying two molten polymers to a spinneret at independently controllable rates, is used to produce composite filaments from seven pairs of propylene polymers each pair having the same intrinsic viscosity but different molecular weight distribution and equal proportions of each component.
• the component polymers join at the spinneret orifices to produce composite filaments of the side-by-side type.
• the spinnerets used have 24 to 60 orifices of 0.020 inch (0.051 cm.) diameter as noted hereinafter and in all cases except two (Examples 6 and 8) the denier per filaments of the spun filamentary yarns was 15. In Examples 6 and 8 the spun denier per filament was 20.
• Other spinning conditions and additive substances present in the polymers are given in the following table.
• the proportion of a particular component in the composite filament may be varied between about 1:9 to 9:1 the selfcrimping effect obtained over this range being somewhat dependent upon the difference between the Q values for each component. Thus if the Q value difference is high the proportion of the components may differ more from 1:1 than for small Q value differences.
• Component polymers may contain up to about 20% by weight of other substances, as for example, stabilising substances, delustrants or pigments or substances conferring an aflinity for dyestuffs on the propylene polymers.
• viscosity in relation to the process of the invention, intrinsic viscosity measured in decalin solution at 135 C. using a viscometer capillary diameter of 0.44 mm. is meant; the units of viscosity being decilitres/ gram.
• polymers which, in addition to having a difference between the Q values of a selected pair of at least about 0.5, also have an intrinsic viscosity of not less than 1.0, as little or no self crimping effect is obtained with polymers of lower viscosity, particularly if the difference in Q value for the pair is low.
• the spun yarns were collected on rigid bobbins and drawn using a heated feed roll, whereon drawing took place, drawing apparatus with a draw roll temperature of 20 C. or C. In all examples except No. 5 a draw ratio of 3.521 was applied and in the case of Example 5 a draw ratio of 3.0:1 was applied. The feed roll in all cases was maintained at 55 C.
• a 1.1 composite filament was spun using the apparatus of the foregoing Examples 1-7 and a pair of propylene polymers of Q values 5.9 and 4.65.
• a 36 hole (0.051 cm. diameter) spinneret maintained at 205 C. was used and the spun yarn was collected on bobbins at 457 metres/minute.
• the polymers were of intrinsic viscosity 1.3 and contained of a polyamide to enhance dye affinity.
• the spun filaments each having a denier of were drawn using a hot feed roll at 55 C.
• Exlalmple Ratio A:B Percent crimp at a load oi 0.01 mg./denier 0.5 rug/denier Comparative example B For further comparison a 1:1 composite filament was produced using the apparatus of Examples 1-7 and a pair of propylene polymers having Q values close to the values of the components used in Example 7 but differing in intrinsic viscosity. Thus one component had a Q value of 8.4 and an intrinsic viscosity of 2.1 and the other component had a Q value of 5.2 and an intrinsic viscosity of 1.8. When spun and drawn as in Example 7 this pair of polymers produced a filamentary yarn having a percentage crimp under a load of 0.5 mg./denier of 64%.
• a process for the production of self-crimping polypropylene filaments wherein composite filaments having two propylene polymers distributed along the length of the filaments as distinct components in side-by-side or sheath-core relationship are produced by conjugate melt spinning of two propylene polymers followed subsequently by relaxation of tension in the filaments, characterized in that the two polymers have substantially the same intrinsic viscosity, but different molecular weight distributions and wherein the dispersion coefilcient, defined as the ratio of weight average molecular weight to number average molecular weight, of at least one of the polymers is at least 6.5.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Textile Engineering (AREA)
• Multicomponent Fibers (AREA)
• Nonwoven Fabrics (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=10079212

Family Applications (1)

Country Status (6)

Cited By (20)

Citations (5)

• 1965
  • 1965-04-20 GB GB16543/65A patent/GB1094933A/en not_active Expired
• 1966
  • 1966-04-07 US US540852A patent/US3399259A/en not_active Expired - Lifetime
  • 1966-04-20 ES ES0325732A patent/ES325732A1/es not_active Expired
  • 1966-04-20 BE BE679786D patent/BE679786A/xx unknown
  • 1966-04-20 NL NL6605271A patent/NL6605271A/xx unknown
  • 1966-04-20 DE DE19661660376 patent/DE1660376A1/de active Pending

Patent Citations (5)

Also Published As

Similar Documents