JPH05148707A - Production of polyvinylidene fluoride monofilament - Google Patents

Abstract

PURPOSE:To obtain the subject filament having excellent strength and abrasion resistance and low variation ratio of knotting strength by heat-treating a polyvinylidene fluoride single filament having a specific double refractive index at a temperature lower than melting point of the polymer and heat-treating the single filament at high temperature in a high-temperature inert gas for a short time under tension. CONSTITUTION:A polyvinylidene fluoride monofilament having >=25X10<-3> double refractive index is heat-treated in a liquid or inert gas heated to 50 deg.C to a temperature lower than melting point of the polymer for 1-30sec in relaxing ratio of 3-15% and then heat-treated at high temperature for short time under tension in an inert gas heated to 530-1000 deg.C or heated and drawn in <=1.2 times draw ratio at high temperature for short time to provide the objective polyvinylidene fluoride monofilament having high tensile strength and knotting strength and low variation ratio of knotting strength and high abrasion resistance and remarkably improved in impact knotting strength and useful for aquatic raw material of fishing line, fishing net, lever net, etc., raw material for reinforcement of rubber belt and transportation of sling, rope, etc., engineering raw material of fence, prevention of dropping stone, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing polyvinylidene fluoride monofilament having high tensile strength and high knot strength, and more specifically, it has a high tensile strength and a high knot strength suitable mainly for fishing line and is remarkably The present invention relates to a method for producing a polyvinylidene fluoride monofilament having excellent uniformity, high impact knot strength, and high abrasion resistance.

[0002]

2. Description of the Related Art Polyvinylidene fluoride monofilaments are excellent in toughness, impact resistance, transparency and light resistance, yet have a high specific gravity and are easily sunk in water, and have a refractive index close to that of water and surface reflection of light in water is extremely high. It has a small amount of properties, and has excellent properties especially for fishing lines and fishing nets.

However, in these applications, there is always no unevenness in quality, thinner and stronger, and the property of resisting rubbing against rocks, that is, abrasion resistance is good, and the moment of hitting or towing of fish is instantaneous. Impact resistance, that is, impact resistance is also important.

As a conventional method for producing a vinylidene fluoride resin monofilament, for example, Japanese Patent Laid-Open No. 63-
It is described in Japanese Patent No. 11443. The technique described in this publication uses a drawn filament of a thermoplastic resin monofilament made of vinylidene fluoride resin in a liquid at a temperature not lower than the melting point of the surface constituent resin on the low temperature side and not higher than the main melting point by 30 ° C. or 200 It is a method of performing tension heat treatment for a short time of 0.1 to 8 seconds at a draw ratio of 1.0 to 2.0 times in an inert gas at about 500 ° C.

[0005]

The above-mentioned Japanese Patent Laid-Open Publication No.
The vinylidene fluoride resin monofilament obtained by the method described in Japanese Patent Publication No. 3-11443 is highly evaluated in the market because of its excellent characteristics.

However, the monofilament obtained by this method has excellent tensile strength and knot strength,
Although it has abrasion resistance, it is not always satisfactory in terms of impact knot strength, variation rate of knot strength and wear resistance.

An object of the present invention is to provide a polyvinylidene fluoride having a high tensile strength and a high knot strength, a significantly small change in knot strength, a significantly improved impact knot strength, and improved abrasion resistance. It is to provide a method for producing a monofilament.

[0008]

That is, the present invention provides a polyvinylidene fluoride monofilament having a birefringence of 25 × 10 ⁻³ or more in a liquid heated to a temperature of 50 ° C. or lower than the melting point of the polymer or inactive. Heat treatment in gas at a relaxation rate of 3 to 15% for 1 to 30 seconds, and then at 530 ° C
A method for producing a polyvinylidene fluoride monofilament, which comprises performing a high-temperature short-time tension heat treatment for 1 second or less or a high-temperature short-time heat drawing at an draw ratio of 1.2 times or less in an inert gas heated to 1000 ° C. Is provided.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The polyvinylidene fluoride monofilament used in the method of the present invention is not limited to polyvinylidene fluoride homopolymer, and 80 mol% or more of the repeating structural units of the molecular chain consist of vinylidene fluoride, and the copolymerization component is 20%.
It may be a copolymerized polymer containing less than mol%. Examples of the copolymerization component include tetrafluoroethylene, trifluoromonochloroethylene and hexafluoropropylene.

However, when the content of the copolymerization component is 20 mol% or more, the crystallinity decreases and the strength becomes low, which is not preferable.

The polyvinylidene fluoride monofilament used in the present invention is 0.4 g / cc of dimethylformamide.
It is preferable that the intrinsic viscosity index (η / inh) measured with the solution is 0.8 or more, particularly 1.0 or more.

When the intrinsic viscosity index is less than 0.8, a high-strength monofilament comparable to a fishing line cannot be obtained.

Polyvinylidene fluoride monofilaments used in the method of the present invention include, for example, pigments, dyes, light stabilizers,
Additives such as an ultraviolet absorber, an antioxidant, a crystallization inhibitor and a plasticizer may be contained within a range that does not impair the effects of the present invention.

In the method of the present invention, it is necessary to use a polyvinylidene fluoride monofilament oriented in the fiber axis direction, and the more highly oriented it is, the more remarkable the effect of the present invention becomes. Specifically, a polyvinylidene fluoride monofilament having a birefringence of 25 × 10 ⁻³ or more, preferably 30 × 10 ⁻³ or more is used.

The oriented polyvinylidene fluoride monofilament as described above can be easily obtained by a usual melt spinning / hot drawing method.

When the birefringence is less than 25 × 10 ^-3 , it is not possible to obtain a polyvinylidene fluoride monofilament suitable for fishing line which has high strength and is particularly excellent in knot strength, which is the object of the present invention.

In the method of the present invention, first, the birefringence is 2
A polyvinylidene fluoride monofilament of 5 × 10 ⁻³ or more is subjected to a relaxation heat treatment of 3 to 15% for 1 to 30 seconds using a liquid or an inert gas having a melting point of 50 ° C. or lower than that of the polymer. Due to this relaxation heat treatment, the internal stress strain of the highly oriented polyvinylidene fluoride monofilament is relaxed and the uniformity of the monofilament is improved.
It is considered that the effects of the present invention can be obtained.

As the heat medium used for the relaxation heat treatment, an inert liquid and vapor such as glycerin, silicone oil, polyethylene glycol and water, and an inert gas such as heated air are used.

The temperature of the liquid or gas used in the relaxation heat treatment is 50 ° C. to the melting point of the polymer, preferably 60.
The temperature is ˜150 ° C., and the relaxation rate is 3 to 15%, preferably 5 to 10%. The residence time of the monofilament in this case is such that the liquid and the gas have different thermal conductivities, and the liquid and the vapor have a residence time of 1 to 15 seconds, preferably 2 to 10 seconds.
It is necessary to adopt relaxation heat treatment conditions of 15 to 30 seconds for heated air having a low thermal conductivity. That is, it is set in the range of 1 to 30 seconds, although it depends on the heat medium used.

When the temperature and the relaxation rate are lower than the above and the residence time is shorter than the above, the internal stress strain of the highly oriented monofilament is not relaxed, the high strength is not achieved, and the strength variation rate becomes high, which is not preferable. ..

On the other hand, when the temperature and the relaxation rate are higher than the above and the residence time is longer than the above, the filament is cured,
Moreover, it is not preferable because it is loosened too much to cause spots, the rate of change in strength becomes high, and high strength cannot be achieved.

Next, the polyvinylidene fluoride monofilament subjected to the relaxation heat treatment under each of the above conditions is passed through a high temperature inert gas and subjected to a tension heat treatment at a high temperature for a short time or at a high draw ratio of 1.2 times or less. Perform hot stretching for a short time.

The conditions of the high-temperature short-time tension heat treatment or the high-temperature short-time hot drawing are such that the temperature of the inert gas is much higher than the melting point of the monofilament and is 530 to 1000 ° C., preferably 600 to 800 ° C. The state is maintained or stretched 1.2 times or less, more preferably 1.02 to 1.1 times, and the time of exposure to the high temperature is 1 second or less, preferably 0.02.
~ 0.2 seconds.

By satisfying the heat treatment conditions in the method of the present invention, only the surface layer portion of the monofilament is once melted, and the surface layer of the monofilament is sufficiently orientation-relaxed. By relaxing the orientation of the surface layer of the monofilament in this way, the monofilament itself becomes flexible and the knot strength is improved.

In the relaxation heat treatment and the high temperature short time tension heat treatment or the high temperature short time hot drawing, it is necessary to thicken the orientation relaxation layer as the diameter of the monofilament is larger, and the treatment time is lengthened or the treatment temperature is raised. There is a need.

If the treatment time is too long or the treatment temperature is too high, the orientation relaxation layer becomes too thick, and the tensile strength and knot strength are significantly reduced. If the treatment conditions are satisfied, an orientation relaxation layer having an appropriate thickness is formed on the surface layer of the monofilament, while maintaining the tensile strength at a high value,
The knot strength can be significantly improved. Of course, a monofilament having a birefringence of 25 × 10 ⁻³ or more may be melt-spun, followed by a relaxation heat treatment step and a high temperature short time tension heat treatment step and / or a high temperature short time hot drawing step, which may be continuous or discontinuous. It may be a separate process.

The inert gas used in the present invention may be any one that does not react with the polyvinylidene fluoride monofilament during heat treatment to cause a significant chemical change, and air and nitrogen are particularly preferable.

The method of the present invention will be described below based on Examples. The physical properties of the obtained polyvinylidene fluoride monofilament are the values measured by the following measuring methods.

(A) Intrinsic viscosity index η / inh: A sample was dissolved in dimethylformamide at a concentration of 0.4 g / cc and measured at 30 ° C. using an Ostwald viscometer.

(B) Birefringence Δn: Determined by a usual Bereck compensator method using white light as a light source using a POH type polarizing microscope manufactured by Nippon Kogaku Kogyo Co., Ltd.

(C) Tensile Strength, Tensile Elongation, Knot Strength and Knot Elongation The definition was according to JIS-L1017. That is, a sample is taken in the shape of a strip and placed in a temperature / humidity control room at 20 ° C and 65% RH for 24 hours.
"TENSILON" manufactured by Orientec Co., Ltd.
Using UTM-4-100 type tensile tester, test length 250m
It was measured at m and a pulling speed of 300 mm / min.

(D) Variation rate of nodule strength Calculated by the following formula from the nodule strength of n = 25 measured in the item (C).

Variation rate (CV value) = σ / M × 100 (M
Indicates the average value.) (E) Abrasion resistance A monofilament loaded with a load of 1/20 × D (fineness) is coated with sandpaper # 320, and a stainless steel rod with an outer diameter of 50 mmφ rotates at 180 times / min. Place it on
Traverse speed 70mm / min (traverse width 35m
In m), the number of rotations until the monofilament was moved and cutting was performed.

(F) Impact Knot Strength Using a pendulum impact tester manufactured by Shimadzu, a sample length of 250 mm was set with a knot, and a pendulum arm length of 281.7 mm, a pendulum load of 3.729 kg, a lifting angle of 90 degrees, and a tensile force. Speed 1.
Impact the monofilament under the condition of 5 m / sec,
The strength at the time of cutting was divided by the fineness, and the value was taken as the impact knot strength.
In addition, the monofilament cutting strength is DSA6-
The instantaneous strength at the time of cutting from the 11-type automatic balance type dynamic strain measuring instrument and the photo coder (type 2932) manufactured by Yokogawa Hokushin Electric was recorded and read.

[0035]

[Examples] Tables 1 and 2 show the conditions and results of each experimental example and comparative example.

Comparative Example 1 A polyvinylidene fluoride polymer chip having an intrinsic viscosity index of 1.2 was melted at 260 ° C. by a 15 mmφ extruder, spun through a spinneret having a hole diameter of 1.5 mmφ, and further polyethylene glycol bath at 20 ° C. An unstretched monofilament was obtained by cooling in the inside. The birefringence of the unstretched monofilament obtained here was 1.5 × 10 ⁻³ .

Next, this unstretched monofilament was separated into 16
After being drawn 3.2 times in a polyethylene glycol drawing bath at 0 ° C., it is further drawn twice at 165 ° C., and then polyethylene glycol is removed in a warm water bath at 65 ° C. A polyvinylidene fluoride monofilament was obtained. The birefringence of the obtained monofilament is 3
It was 8.6 × 10 ⁻³ . Subsequently, heat treatment was performed for 0.05 seconds while stretching 1.1 times in an inert gas at 670 ° C.

The tensile strength of the monofilament is 5.3.
g / d, knot strength 4.0 g / d, knot strength variation 14
%, Abrasion resistance 97 times, impact knot strength 3.1 g / d.

Example 1 Two-stage drawing was carried out in the same manner as in Comparative Example 1, and then 90 ° C. and a length of 1 m.
It was passed through a warm water bath of 7% and treated at a relaxation rate of 7%. Continued 67
While stretching 1.1 times in an inert gas at 0 ° C.,
Heat treatment was performed for 5 seconds.

The obtained polyvinylidene fluoride monofilament had a tensile strength of 5.5 g / d, which was almost the same as that of Comparative Example 1, the knot strength was 4.7 g / d, and the knot strength variation rate was 5%. The abrasion resistance was 175 times, and the impact knot strength was 3.7 g / d, and the respective physical properties were remarkably improved as compared with the polyvinylidene fluoride monofilament obtained by the method of Comparative Example 1.

Example 2 An unstretched monofilament obtained in the same manner as in Comparative Example 1 was treated with 6. in a polyethylene glycol stretching bath at 165 ° C.
After being stretched 4 times, it was passed through a warm water bath at 90 ° C. and a length of 1 m and treated at a relaxation rate of 7%. Subsequently, heat treatment was carried out for 0.08 seconds while stretching 1.05 times in an inert gas at 670 ° C. The obtained polyvinylidene fluoride monofilament has a tensile strength of 6.3 g / d and a knot strength of 4.6 g / d.
d, the knot strength variation rate is 6%, the wear resistance is 175 times, the impact knot strength is 3.6 g / d, and even in the case of one-stage stretching, Example 1
Similarly to the polyvinylidene fluoride monofilament obtained by the method of Comparative Example 1, it was remarkably improved.

Examples 3 to 11 and Comparative Examples 2 to 5 According to Example 2, the relaxation heat treatment conditions were changed as shown in Table 1, and the monofilaments were heat-stretched at high temperature for a short time. The evaluation results are shown in Table 2.

[Table 1] Relaxation heat treatment High-temperature short-time heat treatment Heat medium temperature multiplication time Temperature multiplication time (° C) (-) (seconds) (° C) (-) (seconds) Comparative Example 1 − − − − 670 1.05 0.05 Example 1 Water 90 0.93 8 670 1.1 0.05 Example 2 〃 〃 〃 〃 1.05 0.08 Comparative Example 2 〃 〃 0.85 〃 〃 〃 〃 〃 3 〃 〃 0.93 3 〃 〃 0.93 3 〃 〃 〃 〃 Example 4 PEG 130 0.93 6 685 〃 〃 Example 5 〃 150 〃 〃 〃 〃 〃 Example 6 〃 170 〃 〃 〃 〃 〃 Example 〃 〃 〃 〃 〃 〃 30 750 〃 〃 Comparative example 4 〃 200 〃 〃 〃 〃 〃 Example 9 Water 90 0.93 8 670 1.1 〃 Comparative example 5 〃 〃 〃 〃 〃 〃 〃 1.3 〃 5 〃 〃 〃 1.3 〃 〃 500 〃 0.5 Example 12 〃 〃 〃 3 670 1.00 0.08 Example 13 〃 〃 〃 3 670 0.98 0.08 [Table 2] _{Tensile strength Knot strength} Knot strength Abrasion resistance Impact knot strength Change rate (g / d ) (g / d) (%) (times) (g / d) Comparative Example 3 5.9 3.5 15 90 3.0 Example 4 6.4 4.5 5 185 3.7 Example 5 5.8 4.1 7 140 3.5 Example 6 5.5 4.0 11 105 3.2 Implementation Example 6 5.5 4.0 11 105 3.2 Example 7 6.3 4.5 4 181 3.5 Example 8 5.9 4.3 10 160 3.3 Comparative Example 4 5.4 3.4 17 90 3.0 Example 9 6.3 4.5 5 177 3.6 Comparative Example 5 5.8 3.6 8 130 3.3 Example 10 5.9 4.4 6 165 3.5 Example 11 5.9 4.0 7 110 3.3 Example 12 5.8 4.2 7 160 3.5 Example 13 5.5 4.0 5 140 3.4 As shown in Tables 1 and 2, the relaxation heat treatment conditions are in accordance with the method of the present invention. The polyvinylidene fluoride monofilaments of Examples 3 to 8 which were carried out by the above-mentioned method have a significantly improved knot strength and a low knot strength variation rate. Moreover, wear resistance is improved and impact knot strength is also significantly improved.

On the other hand, if the relaxation rate is set to 15% or more as in Comparative Example 2, the running of the monofilament becomes unstable during the relaxation heat treatment, and the variation rate of the knot strength is high and the monofilament is not uniform, which is not preferable.

When the relaxation rate is set to 0% (constant length) as in Comparative Example 3, the internal stress strain of the highly oriented monofilament is not sufficiently relaxed and the knot strength, abrasion resistance and impact knot strength are improved. A non-uniform monofilament that is low and has a high knot strength variation rate.

The relaxation heat treatment by dry heat requires a longer treatment time because the thermal conductivity is smaller than that of other heat mediums, but the dry heat temperature is raised without changing the treatment time. When the treatment (for example, 200 ° C.) is performed, the monofilament becomes hard and the strength becomes low as shown in Comparative Example 4.

Furthermore, a monofilament treated according to the present invention under the conditions of high-temperature short-time tension heat treatment (Example 9-1)
1) has high tensile strength and high knot strength, and has a low knot strength variation rate. In addition, wear resistance is improved and impact knot strength is also significantly improved. That is, a target high-performance polyvinylidene fluoride monofilament can be obtained by subjecting a highly oriented monofilament to an appropriate relaxation heat treatment and an appropriate high temperature short time tension heat treatment.

However, when the processing temperature becomes 500 ° C. or lower,
It is difficult to form an orientation relaxation layer having an appropriate thickness on the surface layer, and it is difficult to cover the heat shortage with the treatment time in a continuous process because it is restricted. When the draw ratio is 1.2 times or more as in Comparative Example 5, a high-strength monofilament cannot be obtained.

[0049]

According to the method of the present invention, polyvinylidene fluoride monofilaments highly oriented in the fiber axis direction are heat-treated in a specific temperature range, treatment time and relaxation rate, and further in a specific temperature range, treatment time and tension heat treatment. By doing
It is possible to obtain a monofilament in which only the surface layer portion is orientation-relaxed, high tensile strength and high knot strength, low knot strength variation rate, high abrasion resistance, and impact knot strength are remarkably improved.

The high knot strength polyvinylidene fluoride monofilament obtained by the method of the present invention is used for marine products such as fishing lines, fishing nets and glue nets, reinforcing and sling rubber belts, transportation materials such as ropes, fences and rockfall prevention. It can be effectively used for applications such as civil engineering materials.

Claims (1)

[Claims] 1. A method for producing a high knot strength polyvinylidene fluoride monofilament, wherein the birefringence is 25 × 10 ^−3.
50 of the above polyvinylidene fluoride monofilaments
C. to a temperature below the melting point of the polymer, in an inert gas heated in a liquid or an inert gas for 1 to 30 seconds at a relaxation rate of 3 to 15%, and then heated to 530 to 1000.degree. Among them, high temperature short time tension heat treatment of less than 1 second,
Alternatively, a method for producing a polyvinylidene fluoride monofilament is characterized in that hot drawing is carried out at a high temperature for a short time at a draw ratio of 1.2 times or less.