JP2776013B2 - Method for producing high knot strength polyvinylidene fluoride monofilament - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a high knot strength polyvinylidene fluoride monofilament, and more particularly to a method for producing a high knot strength polyvinylidene fluoride monofilament suitable for fishing line. Things.

[Prior art] Polyvinylidene fluoride monofilament has toughness,
Excellent impact resistance, transparency, light resistance, etc., high specific gravity, easy to sink in water, refractive index close to water, very low surface reflection of light in water, especially excellent for fishing line and fishing net Has properties.

Polyvinylidene fluoride monofilaments are always required to improve each of the above-mentioned properties, but are particularly required to be thinner and stronger.

Conventionally, a polyvinylidene fluoride monofilament is described in, for example, JP-A-63-112717.
The polyvinylidene fluoride monofilament described in this publication has a specific range of surface birefringence and average birefringence of a cross section perpendicular to the fiber axis.

[Problems to be Solved by the Invention] The polyvinylidene fluoride monofilament described in JP-A-63-112717 has been highly evaluated in the market for its excellent properties. But,
In particular, since fishing lines have lower strength than nylon monofilaments, monofilaments having high strength, particularly high knot strength, are required. It should be noted here that it is necessary to maintain not only the strength but also other characteristics useful as other tex as a certain level or more.

An object of the present invention is to provide a method capable of producing a high knot strength polyvinylidene fluoride monofilament having higher strength and particularly superior knot strength than polyvinylidene fluoride monofilament obtained in the prior art.

[Means and Actions for Solving the Problems] The constitution of the present invention relates to a method for producing a high knot strength polyvinylidene fluoride monofilament, wherein the birefringence is 25 × 10 ^−3.
The above-mentioned polyvinylidene fluoride monofilament is treated with an inert gas temperature (T ° C.) and a diameter of the monofilament (Dmm).
The heat treatment in an inert gas is performed under the condition that the relation between the temperature and the processing time (τ seconds) satisfies 68D / (T-25) ≦ τ ≦ 680D / (T-25) 1200 ≧ T ≧ 550. And a method of producing a high knot strength polyvinylidene fluoride monofilament.

The polyvinylidene fluoride monofilament used in the method of the present invention is not limited to polyvinylidene fluoride homopolymer, but 80 mol% or more of the repeating structural units of the molecular chain is composed of vinylidene fluoride, and the copolymer component is contained in an amount of less than 20 mol%. May be contained. Examples of the copolymer component include tetrafluoroethylene, trifluoromonochloroethylene, and hexafluoropropylene.

If the copolymer component is contained in an amount of 20 mol% or more, crystallinity is undesirably reduced.

The polyvinylidene fluoride monofilament according to the present invention preferably has an intrinsic viscosity index (ηinh) of 0.8 or more, particularly 1.0 or more, measured with a 0.4 g / cc solution of dimethylformamide.

If it is less than 0.8, a high-strength monofilament suitable for a fishing line cannot be obtained.

In the polyvinylidene fluoride monofilament used in the method of the present invention, for example, additives such as a pigment, a dye, a light stabilizer, an ultraviolet absorber, an antioxidant, a crystallization inhibitor, and a plasticizer are added in a range that does not impair the effects of the present invention. Can be contained.

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

The above-mentioned oriented polyvinylidene fluoride monofilament can be easily obtained by a usual melt spinning and hot drawing method.

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

In the method of the present invention, the polyvinylidene fluoride monofilament having a birefringence of 25 × 10 ⁻³ or more is placed in an inert gas at a temperature (T ° C.) of the inert gas, a diameter (Dmm) of the monofilament, and a treatment time ( τ seconds) is 68D / (T-25) ≦ τ ≦ 680D / (T-25) 1200 ≧ T ≧ 550, more preferably 68D / (T-25) ≦ τ ≦ 340D / (T-25) Heat treatment is performed so as to satisfy 1000 ≧ T ≧ 550.

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

In the above heat treatment, the larger the diameter of the monofilament, the thicker the orientation relaxation layer, and the longer the treatment time.

On the other hand, if the treatment temperature is too high, the orientation relaxation layer becomes too thick, and the tensile strength is significantly reduced. Therefore, the processing temperature (T) is set in the range of 550 ° C to 1200 ° C. Further, if the heat treatment time satisfies the relation of 68D / (T-25) ≦ τ ≦ 680D / (T-25) in relation to the thickness of the monofilament and the processing temperature, it is suitable for the surface layer of the monofilament. As a result, the knot strength can be significantly improved while maintaining the tensile strength at a high value.

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

In the above heat treatment, the polyvinylidene fluoride monofilament is treated while being fixed, relaxed or stretched. Specifically, the heat treatment is performed at a magnification of 0.9 to 1.5 while performing constant length, relaxation or stretching.

Next, the method according to the present invention will be described based on examples. The physical properties of the obtained polyvinylidene fluoride monofilament are measured by the following measuring methods.

(A) Intrinsic viscosity index ηinh: 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: Using a POH-type polarizing microscope manufactured by Nippon Kogaku Kogyo Co., Ltd., using a white light source as a light source, a normal Berek compensator method was used.

(C) Tensile strength, tensile elongation, knot strength and knot elongation According to the definition of JIS-L1017. Take the sample in a skein,
After standing for 24 hours in a temperature and humidity control room at 65 ° C. and 65% RH, it was measured at a test length of 25 cm and a tensile speed of 30 cm / min using a “Tensilon” UTM-4-100 type tensile tester manufactured by Orientec Co., Ltd. .

Example 1 Comparative Example 1 A polyvinylidene fluoride polymer chip having an intrinsic viscosity index of 1.2 was melted at 260 ° C. in a spinning machine, spun through a die having a pore diameter of 1.0 mm, and further cooled in a polyethylene glycol bath at 20 ° C. Thus, an undrawn monofilament was obtained. The birefringence of the undrawn monofilament obtained here was 1.5 × 10 ⁻³ .

Next, the undrawn monofilament was drawn 6.5 times in a polyethylene glycol drawing bath at 165 ° C.
The polyethylene glycol was removed in a hot water bath at 0 ° C. to obtain a polyvinylidene fluoride monofilament having a diameter of 0.23 mm.

The birefringence of the obtained polyvinylidene fluoride monofilament was 39.3 × 10 ⁻³ , and the tensile strength was as high as 6.5 g / d, but the knot strength was 2.7 g / d.

Example 1 A polyvinylidene fluoride monofilament having a diameter of 0.23 mm and a birefringence of 39.3 × 10 ⁻³ obtained in Comparative Example 1 was subjected to a heat treatment for 0.05 seconds while being stretched 1.04 times in an inert gas at 720 ° C.

The tensile strength of the obtained polyvinylidene fluoride monofilament is 6.3 g / d, which is not significantly reduced by the heat treatment, and the knot strength is 4.7 g / d, which is remarkably improved as compared with the polyvinylidene fluoride monofilament obtained by the method of Comparative Example 1. did.

Comparative Example 2 A polyvinylidene fluoride polymer chip having an intrinsic viscosity index of 1.2 was melted at 280 ° C. in a spinning machine, spun through a die having a pore size of 2.0 mm, and further cooled in a polyethylene glycol bath at 20 ° C. to obtain an undrawn monofilament. I got

After stretching the undrawn monofilament 3.2 times in a polyethylene glycol stretching bath at 160 ° C.,
Was performed twice. The diameter of the polyvinylidene fluoride monofilament having an overall draw ratio of 6.4 was 0.52 mm, the tensile strength was 5.4 g / d, but the knot strength was as low as 3.2 g / d. The birefringence of this polyvinylidene fluoride monofilament was 37.4 × 10 ⁻³ .

Example 2 The polyvinylidene fluoride monofilament having a diameter of 0.52 mm and a birefringence of 37.4 × 10 ⁻³ obtained in Comparative Example 2 was subjected to a heat treatment in an inert gas at 650 ° C. for 0.13 seconds. The heat treatment was performed at a fixed length.

The tensile strength of the obtained polyvinylidene fluoride monofilament is 5.3 g / d, which is not significantly reduced by the heat treatment, and the knot strength is 4.6 g / d, which is remarkably improved as compared with the polyvinylidene fluoride monofilament obtained by the method of Comparative Example 2. did.

Examples 3 to 6 and Comparative Examples 3 to 6 Using the polyvinylidene fluoride monofilament having a diameter of 0.23 mm and a birefringence of 39.3 × 10 ⁻³ obtained in Comparative Example 1, the temperature and the treatment time of the inert gas were changed. Then, a heat-treated polyvinylidene fluoride monofilament was obtained.

The treatment conditions were as shown in Table 1, and the characteristics of the obtained polyvinylidene fluoride monofilament were as shown in Table 2.

As shown in the table, the polyvinylidene fluoride monofilament obtained by the method of the present invention has significantly improved knot strength.

[Effects of the Invention] According to the method of the present invention, a polyvinylidene fluoride monofilament monofilament highly oriented in the fiber axis direction is heat-treated in a specific temperature range and treatment time,
Only the surface layer portion is relaxed in orientation, and a monofilament with high knot strength can be obtained while maintaining strength.

Further, the high knot strength polyvinylidene fluoride monofilament obtained by the method of the present invention is used for fishery materials such as fishing lines, fishing nets, glue nets, rubber belt reinforcement / slings, transporting materials such as ropes, and civil engineering such as fences and rockfall prevention. It can be used effectively for applications such as materials.

Claims (1)

(57) [Claims] When producing a high knot strength polyvinylidene fluoride monofilament, a polyvinylidene fluoride monofilament having a birefringence of 25 × 10 ⁻³ or more is converted into an inert gas temperature (T ° C.) and a monofilament diameter (Dmm). Heat treatment in an inert gas under the condition that the relationship between the temperature and the processing time (τ seconds) satisfies 68D / (T-25) ≦ τ ≦ 680D / (T-25) and 550 ≦ T ≦ 1200 A method for producing a high knot strength polyvinylidene fluoride monofilament, characterized by comprising: