Classifications

• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F8/00—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof
  • D01F8/04—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers
  • D01F8/06—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers with at least one polyolefin as constituent
• • 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

• This invention relates to a process for producing composite monofilaments (hereinafter abbreviated to "composite MF”) having heat-adhesive properties and excellent strengths. More particularly it relates to a process for producing composite MF of polyolefin resins having heat-adhesive properties and excellent strengths, obtained by using a low melting polylefin resin component on the sheath side and a high melting polypropylene (hereinafter abbreviated to "high melting PP”) components on the core side, and melt-extruding these components through a sheath-and-core type spinneret, followed by cooling, solidifying and stretching.
• composite MF composite monofilaments
• high melting PP high melting polypropylene
• monofilaments as a single component obtained by melt-extruding a polyolefin resin, followed by cooling and then stretching are superior in mechanical strengths, chemical strengths, corrosion resistance, water resistance, mold-ability, etc.; hence they have been fabricated into ropes, materials of fishing such as fishermen's nets, nets for land such as insect screening, windbreak net, golf net, light-shielding net, filter, sheet for public works, etc, and the resulting products have been widely used.
• MF monofilaments
• the strength of each MF in the longitudinal direction and that in the lateral direction are both 0.26 5 N/tex (3g/d) or more
• the strength of each MF of the above particular nets in the longitudinal and that in the lateral direction are both 0.13 2 N/tex (1.5 g/d) or less, that is, extremely lower; thus a problem has been raised that the particular nets could have been applied only to extremely limited uses such as use for packaging simple, light-weight goods.
• USA-A-4285748 there is disclosed a nonwoven fabric formed from self-bonded sheath/core composite polyolefin filaments.
• the sheath:core ratio is from 5:55 to 30:70 but we have found that for composite filament suitable for making nets the sheath:core ratio should be from 30:70 to 60:40 to give acceptable spinnability and stretchability and adequate backing force.
• the thickening and draw ratio of 'composite filaments suitable for making nets should be from 100 to 1000 denier (11.1 to 111.1 tex) and from 6 to 9 respectively, in contrast to a thicker of 10 to 20 denier (1.11 to 2.27 tex) and a draw ratio of 2 to 6 specified in US-A-4285748.
• the object of the present invention is to provide a process for producing composite MF having heat-adhesive properties, superior strengths, no curl and no peeling between the layers thereof.
• the present invention resides in a process for producing a composite MF having heat-adhesive properties and superior strengths which comprises subjecting a low melting polyolefin resin having a melting point of 135°C or lower, selected from high density polyethylene homopolymer (HDPE) or copolymer composed mainly of ethylene, linear chain low density polyethylene (LLDPE) homopolymer, low melting polypropylene (PP) homopolymer or copolymer composed mainly of propylene and mixtures of the foregoing, and a high melting polypropylene homopolymer or copolymer composed mainly of propylene having a melting point of 150°C or higher, to a sheath-and-core type composite spinning using the former low melting polyolefin resin as the sheath component and the latter high melting polypropylene homopolymer or copolymer composed mainly of propylene as the core component, into an unstretched monofilament, the melt flow index ratio of the former low melting polyolefin
• HDPE and polypropylene used in the present invention
• homopolymer of ethylene or propylene is not only used, but also copolymers of ethylene with propylene, butene-1, etc. composed mainly of ethylene or copolymers of propylene with ethylene, butene-1, etc. composed mainly of propylene may be preferably used.
• added additives which are usually added to polyolefin resins, such as stabilizers, e.g. antioxidant, ultraviolet absorber, etc., coloring agent, lubricant, antistatic agent, delustering agent, etc.
• mixing may be carried out employing a conventional means such as extruder, Banbury @ mixer, tumbler mixer, Henschel° mixer, etc. and in a conventional manner.
• composite extrusion method and apparatus although known techniques may be employed such as composite extrusion by means of two extruders and composite spinnerets of side-by- side or sheath-and-core type, it is preferred in the present invention to employ composite spinnerets of sheath-and-core type which is advantageous in the aspects of spinning, stretching stability and peel resistance of the boundary surface layer between the sheath component and the core component of stretched composite MF.
• the high melting PP and the low melting PP are based on MFR measured according to ASTMS D 1238 (L), and HDPE and LLDPE are based on MI measured according to ASTM D 1238 (E).
• the melt flow index (MFR) of the high melting PP used on the core side of the composite MF may be in the range of 0.3 to 15 which has been used for ordinary MF, but its melting point is required to be 150°C or higher, and as for the FR ratio of the low melting polyolefin resin component on the sheath side to the high melting PP on the core side, when the ratio is in the range of 1.5 to 7, the effectiveness of the present invention is remarkable. If the melting point of the core component is lower than 150°C, its strength as a basic performance of the core component is reduced, and also its shrink properties increase so that when a net prepared by knitting or weaving the above composite MF is subjected to heat set, shrink-deformation is notable.
• the FR ratio is lower than 1.5, spinning and stretching properties are unstable and the resulting net is inferior in heat-adhesive properties. If is is higher than 7, the fluidity of the sheath component in the nozzle is different from that of the core component therein, and also there occurs a large stress strain due to the difference in the crystallization behaviour between the two components or the difference in the volume shrinkage between the two components during the process from molten state to cooling and solidification, so that extruded unstretched MF bends or curls at the exit of the nozzle to make spinnability inferior. Further since the difference between the stretching stress applied to the sheath and core components increases; hence stretching troubles such as stretching breakage, curling of stretched MF, etc. are liable to occur.
• the low melting polyolefin resin used as the sheath component constitutes a component by which adhesive properties due to heat-melt adhesion are imparted to composite MF, and the effectiveness is fully exhibited by single use of HDPE, LLDPE or a low melting PP, but even when two or more kinds thereof are used in admixture, the same effectiveness as in the single use is exhibited. In this case, as for the combination of the components, combinations of polymers having similar fluidities are preferred. When a low melting point PP is used as the sheath component, its melting point is necessary to be 135°C or lower.
• the melting point of the low melting polyolefin resin is preferably 80°C or higher and more preferably 100°C or higher.
• the composite ratio of the sheath component to the core component is preferably in the range of 30:70 to 60:40. If the sheath comoponent is less than 30%, spinnability and stretchability are liable to be inferior, and also since the amount of the heat-adhesive component of the composite MF is reduced, the bonding force at the adhesion part of the mesh of the net becomes weak. On the other hand, if the core component is less than 40%, the strength of the core component as a basic element of the role thereof is reduced.
• the stretching in the present invention general apparatus and process for stretching may be employed which have been employed for ordinary MF.
• the stretch ratio is suitably in the range of 6 to 9 times the original length.
• composite MF since its strength is structurally somewhat lower than that of ordinary MF, if the ratio is lower than 6 times, its strength is low, while if it exceeds 9 times, its strength is sufficient, but due to the fact that composite MF is poor in the compotability of polymers at the boundary surface thereof, the difference in stretchability between the sheath component and the core component becomes remarkable so that troubles such as turnover or peel of the sheath component occur during the stretching step and also it is liable to curl after stretching, which causes troubles of bad take-up during the take-up step such as bad take-up shape or getting out of take-up shape.
• the composite MF of the present invention may usually be preferably used in a thickness of 11.1 to 111.1 tex (100 to 1,000 d).
• the composite MF obtained according to the present invention retains strength characteristics similar to those of ordinary MF and is at the same time provided with heat-adhesive properties.
• the net-form product having its mesh part bonded together by heat-adhesion obtained by subjecting a net-form material prepared by knitting or weaving the above composite MF, to heat treatment by way of a general means such as heating roll, heating calendar, hot air, steam treatment, etc., retains strengths similar to those of net-form products consisting of ordinary MF and hardly causes mesh deformation.
• melt-extrusion was carried out at an extrusion temperature on the core side of 260°C, at an extrusion temperature on the sheath side of 240°C and at a composite spinneret temperature of 260°C, followed by spinning through cooling to obtain an unstretched composite filamant of sheath-and-core type having a composite ratio of 50:50, which was then stretched to 5 to 10 times by means of a wet type, heat stretching apparatus to obtain various kinds of composite MF of 50 tex (450 d).
• PP having a m.p. of 161°C and a MFR of 3.1 spun was carried out under the same conditions as in Example 1 to obtain various unstretched composite filaments of sheath-and-core type, which were then stretched by means of a wet type, heat stretching apparatus to obtain composite MFs of 50 tex (450 d).
• the spinnability and stretchability of the resulting composite MFs and evaluations of the heat-adhesive properties and the residual strength of net-form products prepared from the above composite MFs in the same manner as in Example 1 are shown in Table 3.
• composite MFs were prepared under the same conditions as in Example 1.
• the heat-adhesive properties and the residual strength of net-form properties and the residual strength of met-form products prepared from the above composite MFs were evaluated. The results are shown in Table 4.
• a PP having a m.p. of 161°C and a MFR of 3.1 was used as a core component, and three kinds of mixed resins obtained by mixing the respective two of HDPE, LLDPE or a PP of m.p. 128°C in a ratio of 1:1 by means of a Henschel mixer, followed by extruding and granulating the mixtures by means of an extruder having a bore diameter of 40 mm were used as a sheath component, respectively. Evaluation was made as in Example 1. The results are shown in Table 5.
• PPs having similar MFRs and various melting points were used as core component, and HDPE, LLDPE or a PP of m.p. 128°C was singly used as a sheath component. Evaluation was made as in Example 1. The results are shown in Table 6.

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• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Multicomponent Fibers (AREA)
• Treatment Of Fiber Materials (AREA)

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Publications (3)

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• 1983
  • 1983-07-14 JP JP58128666A patent/JPS6021908A/ja active Granted
• 1984
  • 1984-07-11 DE DE8484304721T patent/DE3468448D1/de not_active Expired
  • 1984-07-11 EP EP84304721A patent/EP0132110B1/en not_active Expired
  • 1984-07-14 KR KR1019840004154A patent/KR870000442B1/ko not_active Expired

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