JPS6021908A - Manufacture of composite monofilament - Google Patents

Abstract

PURPOSE:To obtain the titled heat-weldable filament having high strength, by using a low-melting polyolefin resin such as a high-density polyethylene as the sheath, and a polypropylene having a specific melting point as the core, and specifying the ratio of the melt flow indices and the ratio of the amounts of both components. CONSTITUTION:A low-melting polyolefin resin selected from a high-density polyethylene, a straight-chain low-density polyethylene, a polypropylene having a melting point of <=130 deg.C of their mixture is used as the sheath component, and a polypropylene having a melting point of >=150 deg.C is used as the core component. A composite undrawn monofilament yarn wherein the ratio of the melt flow indices of the low-melting polyolefin resin to the polypropylene component having a melting point of >=150 deg.C is 1.5-7.0 and the composite ratio of sheath/core is 30:70-60:40 is manufactured by the sheath-core composite spinning of the above components. The objective composite monofilament is obtained by drawing the above undrawn fiber at a draw ratio of 6-9.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a composite monofilament (hereinafter abbreviated as "composite MFJ") that has thermal adhesive properties and excellent strength. Thermal adhesiveness is obtained by melt-extruding a melting point polyolefin resin component using a core side of polypropylene with a high melting point (hereinafter abbreviated as high melting point PPJ) using a sheath-core type die, cooling, solidifying, and stretching. This is a method for producing a polyolefin resin composite MP having the same properties and excellent strength.

In general, single-component monofilament (hereinafter abbreviated as MFJ), which is made by melt-extruding polyolefin resin, cooling and drawing it, has excellent mechanical strength, chemical resistance, corrosion resistance, water resistance, moldability, etc. Therefore, it is widely used and processed into marine materials such as ropes and fishing nets, as well as land nets such as insect nets, windbreak nets, golf nets, shading nets, Filter 1, and civil engineering sheets.

By the way, nets for land use are mainly used by knitting and weaving, and their mechanical strength is strong in practical use. Because it is relatively free, the mesh may shift during knitting, weaving, and when the net product is used or depending on the actual state of use, resulting in the loss of the shielding or protective effect that is the main purpose of the net product, or the appearance of the net product. There are disadvantages such as poor appearance and poor appearance.

On the other hand, there are well-known techniques for making nets that are directly formed into a net shape by melt extrusion using a special rotary die and have meshes joined together, or for nets obtained by further stretching this net molded product in the longitudinal and lateral directions. However, these monofilaments (hereinafter abbreviated as "MFJ") have a MF strength of 1,000 t/d or more in both vertical and horizontal directions, compared to the normal MF' nemets, which have a vertical and horizontal MF strength of 3 t/d or more. Since the strength is extremely low at less than 5 t'/a, there is a problem that it can only be applied to a very limited number of simple and lightweight packaging applications.

In addition, in the field of non-woven fabrics, in recent years composite fibers with heat-fusible properties have been used for various purposes, made into cloth-like fabrics and then heat-treated to heat-seal the mesh parts. However, the fineness of the heat-fusible composite fibers used for this is approximately 1~1.
Because the composite fiber is very thin at 30 denier, when using it as a thick material with a fineness of 100 denier or more, which is normally used as MP, it needs to be made into a fiber bundle, which requires complicated processing and costs accordingly. The disadvantage is that it is very high.

An object of the present invention is to provide a method for producing a composite MF that has thermal adhesive properties, excellent strength, no curling, and no delamination.

That is, the present invention uses high-density polyethylene (hereinafter referred to as jHDPEJ).
It is abbreviated as ) or linear low-density polyethylene (hereinafter [
(abbreviated as LLDPEJ) or polypropylene with a melting point of 135°C or less (hereinafter abbreviated as "low melting point PPJ").

) or a mixture thereof, a low melting point polyolefin resin and a high melting point polypropylene having a melting point of 150° C. or higher, and a composite MF undrawn yarn obtained by composite spinning into a sheath-core type having the former as a sheath and the latter as a core. The melt flow index ratio of the low melting point polyolefin resin component and the high melting point PP component (hereinafter 1
It is abbreviated as '-FR ratio'. ) is 1.5 or more and 7 or less, and the composite ratio is 30:70 to 60:40.6 HDPB and polypropylene (hereinafter abbreviated as PPJ) used in the present invention are both ethylene or polypropylene. Not only a homopolymer of propylene but also a copolymer of propylene mainly composed of ethylene with 1-butene, etc., or a copolymer of ethylene and 1-butene mainly composed of propylene can be preferably used. In addition, these polymers or mixtures thereof require additives such as antioxidants, stabilizers such as ultraviolet absorbers, colorants, lubricants, antistatic agents, matting agents, etc. that are usually added to polyolefin resins. It can be added accordingly.

In the present invention, when HDPE%LLDPE or low melting point PP, etc. are mixed and used as a sheath component, the mixing method can be carried out using conventional equipment and methods such as an extruder, a Panpassie mixer, a tumbler mixer, a Henschel mixer, etc. . In addition, the composite extrusion spinning method and device are possible using known techniques such as composite extrusion using two extruders and a parallel type or sheath-core type composite spinneret, but in the present invention, spinning, drawing, etc. It is preferable to use a sheath-core type composite cap, which is advantageous in terms of stability and difficulty in peeling off the sheath-core component interface layer of the drawn composite MP.

The melt flow index of the high melting point PP used for the core side of the composite MF may be in the range of 0, 3 to 15, which is normally used for MP, but its melting point needs to be 150°C or higher, and the The effect of the present invention becomes remarkable when the FR ratio with respect to the low melting point polyolefin resin component on the sheath side is 1.5 or more and 7 or less. That is, if the melting point of the core component is below 150°C, the strength, which is the basic performance of the core component, will decrease, and furthermore, the shrinkability will increase, causing shrinkage and shrinkage during heat setting after knitting and weaving into a net shape.
Severe deformation is not desirable. FI'L ratio is 1.5
Below 7, the spinning and drawing properties are unstable, and the net thermal adhesion is poor, and above 7, the fluidity of the sheath component and core component in the nozzle is different, and there is also a difference in crystallization behavior between the fraction components or melting. The stress strain due to the difference in volume shrinkage of the sheath-core layer in the process of cooling and solidifying increases, and the extruded undrawn yarn becomes curved or curled at the nozzle exit, deteriorating spinnability. In addition, if the difference in stretching stress applied to the sheath-core components is large, stretching breakage or curling of the drawn yarn becomes more likely, and stretching troubles are more likely to occur.

The low melting point polyolefin resin used as the sheath component is a component that imparts adhesive properties to the composite MP by heat fusion.Although the use of HDPE%LLDPE and low melting point PP alone is sufficient, the effect is apparent. The same effect as using a mixture of two or more types can be obtained, and in this case, it is preferable to use a combination of components that have the same fluidity. When setting low-melting-point PP as a sheath component, it is inevitably necessary to use high temperature for a long time.Even if thermal bonding is possible, the orientation of the composite MP core component returns due to the heat during heat setting and the strength decreases, reducing the strength that the core component is responsible for. This is not preferable because it will impair the maintenance characteristics.

The sheath/core composite ratio of the sheath component and core component is ・30 near o to 60
: A range of 40 is preferred. If the sheath component is less than 30%, the spinning and drawing properties tend to be poor, and furthermore, the thermal adhesive component of the composite MP decreases and the bonding strength of the mesh bonding portion of the net becomes weak, which is not preferable.

On the other hand, if the core component is less than 40 inches, the strength, which is a basic element of the core component, decreases, which is not preferable.

Stretching in the present invention can be carried out using the general equipment and method normally used in MF, and the appropriate stretching ratio is 6 to 9 times. In the case of composite MP, the strength is structurally lower than that of normal MF, so if it is less than 6 times the strength is low, and if it is more than 9 times the strength is sufficient. Due to poor compatibility, the difference in stretchability between the sheath and core components becomes significant, causing problems such as curling or peeling of the sheath components during the stretching process, and the sheath components tend to curl after stretching, resulting in the sheath core components becoming more easily drawn during the winding process. This is undesirable as it may cause problems such as poor winding appearance or winding misalignment. In order to improve the shrinkability of the drawn yarn after the drawing process, it is also preferable to perform relaxation annealing using a general apparatus and method.

The composite MP obtained by the present invention maintains strength characteristics comparable to those of ordinary MP and has thermal adhesive properties. A net-like article knitted and woven using this composite MP is heat-treated by a general method such as a heat roll, a heat calender, or a hot air or steam treatment, and the resulting mesh parts are bonded by thermal adhesive. The net-like material maintains the strength of the net-like material usually made of MF, and becomes a net-like product in which mesh portions are less likely to shift.

The present invention will be explained below using Examples and Comparative Examples. The criteria for evaluation and the symbols in the table are as follows.

1) MI・・・・・・・・・Melt flow index of polyethylene resin (according to AS TMD-1238 (L). That is, orifice hole diameter 2.092±0.002mm, temperature 1
The weight of the sample extruded for 10 minutes under the conditions of 90°C and 2.16 of The procedure is the same as in 1) except that the temperature is 230°C. ) 3) FR ratio・・・・・・・・・MI and MP measured by the ratio of melt flow index of sheath component and core component (1) and 2)
(ratio with R) 4) Composite ratio: Weight ratio of the sheath-core components obtained by extruding each sheath-core component individually and measuring the weight per unit time of the undrawn yarn: 5 ) Spinnability: Condition of extruded undrawn yarn: O: Normal.

Δ: Unstretched - the system curves at the nozzle exit.

×: The undrawn yarn is curved at the nozzle exit, Spinning becomes impossible.

6) Stretchability: Evaluation was made in the stretched state. Note that the * mark indicates that stretching is not possible.

○: Even in drawn yarn, the drawing process It is normal to leave it on.

Δ: The drawn yarn becomes white.

X: Stretched or curled Easy to cause trouble when handling.

7) Peelability of composite MP: Separability between layers of sheath-core component ○: The sheath layer does not peel off even if an attempt is made to forcibly peel it off.

△: If the sheath layer is forcibly peeled off, it will peel off. But normally there is no problem.

×: Easy to peel off during stretching and winding process Ru.

8) Heat-setting (thermal bonding) method for net-like material: A net-like material woven using a composite MF in a conventional manner is left in a hot air heating tank at 140 to 150° C. for 1.5 minutes.

9) Composite MP strength after thermal bonding process...
...Composite MP was sampled from a net-like material whose mesh portions were thermally bonded, and its tensile strength was measured and evaluated.

○: 4. Greater than Ot/d: 3.0-4. Of/dX: 3. Smaller than Of/d Note) Tensile strength measurement conditions ■Tensile tester Tennron manufactured by Toyo Baldwin ■
Mold ■Chuck distance 200mm ■Tension speed 200wII/min ■Room temperature 23℃ ■Humidity 50cm 10) Adhesion of the mesh part of the net-like material...
...Measure the adhesive strength of the mesh area Q: Adhesive strength greater than 30Of △: 〃 10 o ~ 300 f Example-1 and Comparative Example-1 PP with a melting point of 161°C and various MFRs was used as a core component.
HDPE or LLDPE of various MI as sheath component
Or PP with a melting point of 128℃, each singly (using two with a diameter of 4
Using two 0wn extruders and a sheath-core composite nozzle with a diameter of 1.5 m, the window side extrusion temperature was 260°C and the sheath side extrusion temperature was 260°C.
Spinning was performed by melt extrusion cooling at 40° C. and composite die temperature of 260° C. to obtain a sheath-core composite undrawn yarn with a composite ratio of 50:50. This was stretched 5 to 10 times using a wet heating stretching device to obtain various composite MFs of 450 denier. Table 1 shows the results regarding the spinnability and drawability of the extruded undrawn yarn and the peelability between the sheath and core layers of the composite MP. Furthermore, the various composite MFs produced by the above process were woven into a net-like material with a weaving density of 5 vertical fibers/25 mm x 5 fibers/25 mm, and then woven in a hot air heating tank at 140°C to a density of 1.5
Table 2 shows the results of evaluating the thermal adhesion of the mesh portion and the residual strength of the composite MF after heat setting for a minute and taking it out.

From these tables, PP with a high melting point of 161°C is used as the core component, and H
DPE or LLDPB or low melting point PP with a melting point of 128°C
When each is individually used as a sheath component, the FR ratio is 1.5 to 7.0
It was found that a stretched MP with a stable composite structure without peeling can be obtained in the stretching range of 6 to 9 times, and among these, when the sheath component is low melting point PP, it is especially possible to obtain a stretched MP with a stable composite structure (= composite MF that is difficult to peel off). Furthermore, in the net-like material obtained by heat-setting the net-like material made of these composite MPs, the mesh portions are bonded together by thermal adhesion, and the strength is sufficiently maintained. Recognize.

Example-2 and Comparative Example-2 PP with a melting point of 161°C and MFR of 3.1 as a core component and HDPB, LLDPB or a melting point of 128°C as a sheath component
Each of these PPs was used individually and spinning was performed under the same conditions as in Example 1 to obtain sheath-core type composite, undrawn yarns with various composite ratios. This was stretched using a wet heating stretching device to obtain a composite MF of 450 denier. The spinnability and drawability of the undrawn yarn and the resulting composite MFi were evaluated for the thermal adhesion and residual strength of the net-like material in the same manner as in Example-1. The results are shown in Table 3.

From Table 3, the composite ratio of sheath-core components is 30:'i'0~
It can be seen that within the range of 60:40, the spinning drawing stability and the thermal adhesion and residual strength of the composite M and F net-like products are excellent.

Example-3 and Comparative Example-3 A core component of PP with a melting point of 161°C and an MFR of 3.1, and a sheath component of various low melting point Ps with an MFR of 15.5 and different melting points.
Composite MFs were prepared using P alone under the same conditions as in Example 1, and the thermal adhesion and residual strength of the net-like materials were evaluated.

The results are shown in Table 4.

From Table 4, when using low melting point PP for the sheath component, the melting point is 1.
When the temperature exceeds 35℃, the reciprocity between thermal adhesion and residual strength increases depending on the heat setting conditions of the net-like material, and as the melting point increases, the thermal adhesion deteriorates.In order to improve the thermal adhesion, increasing the heat setting temperature On the contrary, it can be seen that the composite MP strength after thermal bonding becomes too low.

Example-4 H
1 each of DPB, LLDPE or PP with a melting point of 128°C:
After mixing in a Hennel mixer at a ratio of 1:1,
The same evaluation as in Example 1 was carried out using the mixed resin extruded and granulated using a zero-throat extruder as the sheath component. The results are shown in Table 5.

Table 5 shows that even when the sheath component is a mixture of HDPK, LLDPE, and low melting point PP, it has the same effect as the single component.

Example-5 and Comparative Example-4 PP'ta with similar MFR and various melting points as core components
0: HDPE, LLDPE or melting point 1 as the sheath component
Table 6 shows the results of evaluation in the same manner as in Example-1 using 28° C. PP alone.

From Table 6, it can be seen that when the melting point of the core component is 150° C. or lower, there is no problem in thermal adhesion, but the residual strength is significantly reduced.

Claims (1)

[Claims] Low melting point polyolefin resin, which is high density polyethylene, linear low density polyethylene, polypropylene with a melting point of 130°C or less, or a mixture thereof, and a melting point of 150°C
A composite monofilament undrawn yarn obtained by composite spinning the above polypropylene into a sheath-core type with the former as a sheath and the latter as a core, comprising a low melting point polyolefin resin component and a polypropylene component having a melting point of 150°C or higher. 7. Melt flow index ratio is 1.5 or more. ○ A material with thermal adhesive properties and strength characterized by stretching 6 to 9 times as follows and the sheath/core composite ratio is 30:'i'o to 6o:4o. A superior method for producing composite monofilaments.