JPS60181314A - Manufacture of polyvinylidene fluoride monofilament having high knot strength - Google Patents

Abstract

PURPOSE:To produce the titled filament having high knot strength and useful as a fishing line, etc., by preparing an undrawn monofilament by the melt-spinning and cooling of polyvinylidene fluoride, carrying out the first-stage drawing of the monofilament under specific condition, and subjecting to the second-stage drawing at a specific draw ratio after relaxed heat-treatment, etc. CONSTITUTION:The objective monofilament is manufactured by the two-stage drawing of an undrawn monofilament prepared by the melt-spinning and cooling of polyvinylidene fluoride. The two-stage drawing process comprises (1) the first- stage drawing at >=(Tm-60 deg.C) [Tm is melting point ( deg.C) of polyvinylidene fluoride] at a draw ratio E1 of 4.0-6.0, (2) the heat-treatment under relaxed condition at >=(Tm-30 deg.C) and a heat-treatment ratio E2 of 0.85-1.0, and (3) the second-stage drawing at >=(Tm-30 deg.C) and a draw ratio E3 to give a total draw ratio (E1XE2XE3) of >=5.5.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing polyvinylidene fluoride monofilaments which have high knot strength and are particularly suitable for fishing applications such as fishing lines and nets, and for various industrial applications.

Polyvinylidene fluoride monofilament has excellent toughness, impact resistance, transparency, and light resistance.Moreover, it has a high specific gravity (1,8), easily sinks in water, and has a low refractive index of water (1,35).
It has a refractive index close to (1,42) and has extremely low surface reflection in water.

It is particularly effectively used as a fishing line material.

In general, the physical properties required for fishing line include the above-mentioned characteristics as well as relatively high tensile strength and knot strength, but conventional polyvinylidene fluoride monofilament has relatively low knot strength and knot strength. There are drawbacks. That is, conventional methods for producing polyvinylidene fluoride monofilament include a method in which melt spinning is followed by one or two stages of stretching, and then tension heat treatment at 80°C or higher (Japanese Patent Publication No. 15599/1983); A method of stretching 2.5 to 10 times with
-5359) and a method of first stretching between the first inflection point and the second inflection point of the birefringence value curve or kink 1 rate curve, and then second stretching (Japanese Patent Publication No. 53-22574) ), but although these methods provide sufficient tensile sag, the knot strength is limited by the wire diameter U, 1
At most, only about 4.2 g/d can be obtained at 5 m. Generally, the knot strength of a monofilament decreases in inverse proportion to its wire diameter, so if the wire diameter is further increased using the conventional method described above, the knot strength will further decrease.

However, recently, polyvinylidene fluoride used for fishing lines has been increasingly used in red wire diameters, and even for wire diameters of 0.2 m or more, there is a strong demand for knot strength of 4.2 g/d or more. It has become.

Therefore, the present inventors conducted intensive studies with the aim of obtaining a polyvinylidene fluoride monofilament with a wide diameter and high knot strength.As a result, when performing two-step drawing of the monofilament after melt spinning, the first drawing step was later,
The present invention was achieved by discovering that the above object can be effectively achieved by performing a relaxation heat treatment under specific conditions and then performing a first and second stretching.

That is, in the present invention, after melt-spinning polyvinylidene fluoride,
When carrying out two-stage drawing of the undrawn monofilament obtained by cooling, first, the drawing ratio ( E+) is in the range of 4.0 to 6.0, then stretched at a temperature of (Tm, -30°C) or higher, and relaxed under conditions such that the heat treatment ratio (E2) is 0.85 to tO. After heat treatment, the total stretching ratio (E,
The present invention provides a method for producing a highly knotted vinylidene monofilament once made into a polymorphous material, which is characterized by carrying out two-stage drawing at a null drawing ratio (Ex 2).

What is polyvinylidene fluoride used in the present invention?

A polyvinylidene fluoride homopolymer or copolymer containing 95% by weight or more of a vinylidene fluoride component. Here, the copolymerization component that accounts for less than 5% of electric charge is tetrafluoroethylene.

trifluoromonochloroethylene, trifluoroethylene,
Examples include monofluoroethylene, hexafluoropropylene, and mixtures thereof, and among these, tetrafluoroethylene and trifluoromonochloroethylene are preferred. Further, polyvinylidene fluoride having a vinylidene fluoride component of 95% by weight or more may be blended with other vinylidene fluoride homopolymer and/or copolymer. However, if the content of the vinylidene fluoride component in the polymer or polymer mixture is less than 95% by weight, it is not preferable because the crystallinity decreases and it becomes difficult to achieve the characteristics aimed at by the present invention.

The polyvinylidene fluoride used in the present invention preferably has an intrinsic viscosity index (ηinh) of 0.8 or more, particularly 1.0 or more, as measured with an α4g/CC solution of dimethylformamide, and it is sufficient when ηinh is 07 or less. In some cases, it may not be possible to obtain suitable physical properties.

Furthermore, the polyvinylidene fluoride used in the present invention includes, for example, pigments, dyes, light stabilizers, ultraviolet absorbers, antioxidants,
Additives such as crystallization inhibitors and plasticizers can be added during the polymerization process, after the polymerization, or just before spinning, as long as they do not impede the characteristics that characterize them.

In the present invention, when polyvinylidene fluoride is spun into melt 1a, usual conditions using an extrusion spinning machine can be adopted, such as a polymer temperature of 230 to 320°C,
Extrusion pressure 10-500kg/2 scratches, mouth hole diameter 0.1-3
The spinning speed can be appropriately selected from a range of 0.3 to +OOm7 minutes.

After passing through a short gas zone, the spun monofilament is cooled in a cooling bath, where the cooling medium used may include water, glycerin, and liquid compounds inert to polyvinylidene fluoride, such as polyethylene glycol. It will be done.

The cooled monofilament is sent to the first drawing zone after the cooling medium is removed by a conventional method, and the atmosphere (bath) during drawing and heat setting of the present invention is composed of two materials, such as polyethylene glycol, glycerin, and silicone.・Heating medium baths in which liquids such as oil are heated, dry heat gas baths, superheated or pressurized steam baths, etc. are used.

The primary stretching conditions of the present invention are that the stretching temperature is (Tm -60°C)
above, especially at a temperature above (Tm-40°C), the -th drawing ratio (K+) is 4.0 to 6.0, especially 4.3 to 5.0
It is necessary to select conditions that fall within the range of . Note that Tm in the present invention is the melting point of polyvinylidene fluoride (C°C), and a chip or bulk polymer is heated at a temperature increase rate of 10°C in a nitrogen atmosphere using a PerkinElmer DT-2B differential scanning calorimetry needle. It means the crystal melting peak temperature (if several melting peaks appear overlapping, the peak temperature of the highest endothermic peak) when copper is determined in /min (°C).

In the first stage stretching, the stretching temperature is less than (Tm-50°C).

This is undesirable because it causes fibrillation and whitening of the monofilament. Regarding the upper limit of the first-stage stretching temperature, when using a liquid heat medium with high thermal efficiency as the stretching atmosphere, it is preferably approximately below the melting point of polyvinylidene fluoride, and when using a low thermal efficiency such as dry heated gas, Temperatures significantly exceeding the melting point of polyvinylidene fluoride are also permissible. This can be similarly applied to the upper limit temperature in the subsequent relaxation heat treatment and secondary stretching.

Further, if the -next draw ratio is less than 4.0, uneven stretching occurs and the yarn quality is impaired, and if it exceeds &0, it becomes difficult to obtain a monofilament with high knot strength, which is not preferable.

In the present invention, after the above-mentioned second drawing is completed, the monofilament is made into a relaxed state and then heat-treated in that state. , cracks). The temperature in this relaxation heat treatment is (
Tm - 30°C) or above, and above (Tm - 20°C), and the heat treatment magnification (Ex) is 0.85 to 1. O.

In particular, it is important to select conditions within the range of 0.9 to α9B. Here, if the heat treatment temperature is lower than the above, high nodule strength cannot be achieved, which is not preferable, and (E2
) is less than 0.85, the yarn is likely to sag, resulting in uneven wire diameter, and when it exceeds 1.0, it is not possible to correct the unstable structure inside the fiber, making it impossible to achieve high knot strength, which is not preferable.

In the present invention, a second stage of stretching is then performed, and the stretching ratio is further increased to further increase Young's modulus and strength of the monofilament. The second stage stretching condition is that the stretching temperature is (Tm
The stretching ratio (Ea) is selected such that the total stretching ratio (E1×E2 If the stretching temperature is lower than the above, the desired stretching ratio cannot be achieved, and if the total stretching ratio is less than 5.5, the stretching effect is small and the desired physical properties cannot be obtained, which is not preferable.

In the primary stretching and secondary stretching in the present invention, one or both of them may be carried out in two steps as long as the above-mentioned stretching excess (T+ and Ta) and stretching ratio (E+ and Es) are satisfied. The process can be divided into t parts or more. Further, after the completion of the secondary stretching, in order to completely remove the adhering heating medium and form a more stable fiber structure, it is preferable to pass the monofilament in a relaxed state through a warm water bath.

Thus, the polyvinylidene fluoride monofilament obtained by industrially stably spinning by the method of the present invention has a high knot strength of 4.2 g/d or more even with a wire diameter of 0.2 g, is transparent, and has a high Young's modulus. Since it also has excellent tensile properties, it is particularly useful for fishing applications such as fishing lines and fishing nets as fishing line and fishing line, and for various products.

The present invention will be explained in further detail by giving examples below.

In addition, the tensile strength and elongation in the examples and the knot strength and elongation are respectively J Engineering 5-Lj0705.1. + (standard tensile strength and elongation) and 5, 2. + (standard knot strength and elongation) is a value measured according to the measurement method.

Example-1 A polyvinylidene fluoride polymer chip (melting point Tm = 177°C) with an intrinsic viscosity index (η1nh) of 1.2 at 50°C of a dimethylformamide solution of 0.4 g/CQ was spun at 260° C. using an extruder type spinning machine. ℃ 1 melting, pore size 1.
The fibers were spun through an Owa spinneret and further cooled in a polyethylene glycol bath at 20°C. The birefringence Δn of the undrawn yarn obtained here was 1.5 X l O-''.

Next, this undrawn yarn was drawn to 4.5 times (Icl) in a polyethylene glycol first-stage drawing bath at 160°C, and subsequently subjected to relaxation heat treatment at 0.95 times (E2) in a polyethylene glycol bath at 165°C. After that, it was further stretched 1.50 times (I!i
3) and further stretched by 5% in a hot water bath at 80°C to obtain a total stretching ratio (p, XE2XE
, ) 6.4 monofilaments were obtained.

The obtained monofilament had excellent physical properties as shown in Table 1.

Example 2 and Comparative Examples 1 to 4 The properties of monofilaments obtained by using undrawn yarn obtained under the same conditions as Example 1 and varying the drawing conditions and heat treatment conditions as shown in Table 1 are as follows. It was as shown in Table-1.

As is clear from the results in Table 1, the method of the present invention (!*
According to Examples 1 and 2), a monofilament having a knot strength of <i> and other physical properties well balanced can be obtained.

On the other hand, when the relaxation heat treatment is omitted (Comparative Example 1) and when the negative draw ratio (E+) is too high (Comparative Example 2), only monofilaments with low knot strength are obtained, and when the total draw ratio is less than 5.5. In (Ratio Example 3), only a monofilament having low knot strength and low tensile strength can be obtained.

Furthermore, when the heat treatment is performed under tension (Comparative Example 4), although the tensile strength is comparable, only a monofilament with low knot strength is obtained.

Patent applicant Higashi Shikikai Co., Ltd. Azuma Monofilament Kyuni Company

Claims (1)

[Claims] When performing two-step drawing of an undrawn monofilament obtained by melt-spinning and cooling polyvinylidene fluoride, first (Tm
-60°C) or above [where Tm indicates the melting point of polyvinylidene fluoride (C°C)...the same shall apply hereinafter], the stretching ratio (IC+) is in the range of 4.0 to &0. (Tm - 30℃) or higher, heat treatment magnification (
E2) is subjected to relaxation heat treatment under conditions such that (L85 ~ 1.0), and then further at a temperature of (Tm-'50°C) or higher, a 1m stretching ratio (11xl [tlXEi)] is 5.5 or higher ( E3) A method for producing a high knot strength polyvinylidene fluoride monofilament, which is characterized by carrying out two-step drawing.