JPS61170310A - Monofilament for grass reaper and its production - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a monofilament used as a rotary blade of a lawn mower and a method for manufacturing the monofilament.

<Conventional technology> In recent years, it has been found to be safe and easy to work with.

BACKGROUND OF THE INVENTION Grass mowers that use synthetic resin monofilament as a rotary blade instead of metal rotary blades have come into use.

The synthetic resin monofilament used in this rotary blade is used under high-speed rotation, so improving its durability is a technical challenge.In particular, the durability against bending at the base of the attachment part due to bending fatigue during high-speed rotation, and impact wear. There is a particular demand for durability against cracking of the tip.

For this reason, various attempts have been made to improve the durability of synthetic resin monofilaments.
No. 141117 discloses a synthetic resin monofilament containing a low-molecular plasticizer, and JP-A-56-5006 discloses a monofilament made of synthetic resin containing a low molecular plasticizer.
The publication also describes a monofilament made of a mixture of polyamide and ethylene-based ionomer resin.
-138312 publication consists of a copolymerized polyamide,
A monofilament rotary blade is disclosed which has a two-layer structure in which the degree of molecular orientation is different between the core portion and the surface layer portion.

<Problems to be Solved by the Invention> However, the products proposed so far are expensive because they use special polymers, etc., and it is difficult to manufacture uniform products, resulting in broken roots.

The durability against tip cracking is not sufficient.

The present invention aims to provide a highly durable monofilament for mowers using a polymer mainly composed of nylon 6, which is a versatile polymer, and a method for producing the monofilament.

Means for Solving the Problems> The present invention achieves the above objects, and the gist thereof is as follows.

+1) Made of nylon 6 copolymerized or mixed with 5 to 20% by weight of nylon 66, with a diameter of 0.9 to 4 m.
has a nearly circular cross section and a tensile strength of 2 g/d or more,
Cutting elongation is 60-120% and flexibility is 8-14m
A monofilament for mowers characterized by g/d.

(2) Diameter 0.9-4 mm made from nylon 6 polymer copolymerized or mixed with 5-20% by weight of nylon 66
When manufacturing a monofilament with a nearly circular cross section,
After melt spinning the polymer and cooling with water, the temperature is 60-95°C.
Stretched 2.5-3.2 times in a hot water bath, followed by stretching 200-35 times under tension of 0.95-1.00 times in a gas atmosphere.
At a temperature of 0°C, the time it takes to reach 1,500 to 2,400°/second,
A method for producing monofilament for mowers, which is characterized by heat treatment.

The present invention will be further explained in detail below.

In the present invention, nylon 6 copolymerized or mixed with nylon 66 refers to a polymer obtained by mixing caprolactam with a nylon salt and copolymerizing the mixture according to a conventional method, or a polymer obtained by mixing nylon 6 polymer and nylon 66 polymer.

First of all, to explain the monofilament for mowers of the first invention, the monofilament of the present invention consists of nylon 66
It is a monofilament made of ~20% by weight copolymerized or mixed nylon 6 and has a diameter of 0.9 to 4 m and an approximately circular cross section. Namely.

The cross-sectional shape of monofilament is almost circular.

It is preferable that the circularity (major axis/minor axis) is 1.2 or less,
In particular, monofilaments with a perfect circle are preferred; monofilaments with a highly flattened cross-section or irregular cross-sections are not preferred because they not only tend to split at the tips during mowing, but also tend to cause unevenness in the cutting ability; is 0.9 to 4 mm,
O,! If it is less than 11+-, the durability will decrease, while if it exceeds 4, the reaping ability will be poor, which is not preferable.

The monofilament of the present invention has a tensile strength of 2 g/d or more and a breaking elongation of 60=120%. In this case, the tensile strength is 2 g/d or more.

Preferably it is 2.2 g/d or more, and the tensile strength is 2 g/d.
If the cutting elongation is less than d, root breakage or tearing will occur frequently, making it impractical.If the cutting elongation is less than 60%, the abrasion resistance will drop significantly and durability will be lacking, while if it exceeds 120χ, the abrasion resistance will slightly increase. However, this is not suitable as it will cause more bending and tearing.

Furthermore, in addition to the above conditions, the monofilament of the present invention must have a flexibility of 8 to 14 mg/d. Flexibility here refers to the degree of flexibility of a monofilament sample after absorbing moisture at a temperature of 20°C and a humidity of 65% RH to reach an equilibrium moisture content. 1) to two fulcrums (2), a horizontal support with a distance between (2 degrees) of 20w + m, each end of which is 5m.
- Support the sample (1) with the tension tool (3) in the center.
Pull downward at a speed of 10ms/win + 1
The force (mg) at the time of m-displacement was measured using a stress detection device, and this value (mg) was divided by the fineness (denier) of the sample (1) and expressed as the value (s+g/d).

This degree of flexibility is an important requirement in the present invention.

If the flexibility is less than 8 mg/d, it will be easier to wrap it around the grass cutter's storage cassette, but the root will be more likely to break or tear, and if it exceeds 14+ mg/d, the tip will crack more often due to impact wear. At the same time, it becomes difficult to wind the mower into the storage cassette, which is not preferable.

As described above, the monofilament of the present invention having the above-mentioned structure has good sharpness and excellent durability against bending at the base of the attachment portion and cracking at the tip.

Next, a method for manufacturing a monofilament for a lawn mower according to the second invention will be explained.

First, the method of the present invention is to form a nylon 6 polymer with a diameter of 0.9% by copolymerizing or mixing 5 to 20% by weight of nylon 66.
To produce a monofilament with a substantially circular cross section of ~4n++++, the polymer is melt-spun, water-cooled, and then stretched 2.5-3.2 times in a hot water bath at 60-95°C. Melt spinning is carried out according to a conventional method, and the melt-spun monofilament is cooled with water at 10 to 30°C. Stretching is carried out in a hot water bath controlled at 60 to 95°C, but in this case, if the temperature of the hot water bath is less than 60°C, the operability during stretching will decrease, while if it exceeds 95°C, temperature control will become difficult and uniform It is unsuitable because a monofilament with excellent properties cannot be obtained and the operability deteriorates. When the stretching ratio is less than 2.5, the elongation at break of the obtained monofilament is too high and the resulting monofilament is often bent or torn off at the base, while when it exceeds 3.2, the elongation at break is low.

This is not preferable because wear resistance decreases and tip cracks occur frequently.

The monofilament spun and drawn as described above is then heated under a tension of 0.95 to 1.00 times in a gas atmosphere at a temperature of 200 to 350 degrees Celsius, at a temperature of 1500 to 2400 degrees Celsius.
Heat treated for a period of seconds.

This heat treatment is necessary to make the monofilament have the specific flexibility mentioned above. If the tension ratio during heat treatment is less than 0.95 times, the flexibility will be high, and if the tension ratio exceeds 1.00 times, the flexibility will be low. If the product of heat treatment temperature and heat treatment time is 150
If it is less than 0 degrees/second, the flexibility will be too low, resulting in decreased wear resistance and more cracks at the tip. If it exceeds 2400 degrees/second, the flexibility will be too high, and the number of bends and tears will increase. However, this is not preferable because it causes problems such as broken fusion bonds.

Note that this heat treatment in a gas atmosphere may be performed in one stage or in two or more stages.
Perform fixed length heat treatment at 250 to 350 °
It is particularly preferable to carry out the heat treatment at a temperature of 0.95 to 1.0 θ times the tension.

In this way, it is possible to easily produce a monofilament for a lawn mower that has the above-mentioned characteristics and is excellent in durability.

One or more monofilaments of the present invention are attached to a rotating body by a known method and used in a lawn mower.

<Example> The present invention will be specifically explained below using examples.

(In Table 1.2, only the samples marked with a circle are examples of the present invention.) Example 1 Penzel was added as a plasticizer to a nylon 6 copolymer with a different copolymerization ratio of nylon 66. Added 2% sulfonic acid butyramide, spinning temperature 230°C, spinning speed 20m/ll1in
After spinning and cooling in a 20 °C water bath.

Stretched at a draw ratio of 2.7 in a hot water bath at 80 °C, followed by a heat treatment temperature of 290 °C in a 6 m long heat treatment zone.

A constant length heat treatment was performed for 6.7 seconds to produce a circular cross-section monofilament with a diameter of 2.5 mm.

The properties of the obtained monofilament were as shown in Table 1. When each of these monofilaments was used as a rotary blade of a mower to cut weeds for 30 minutes at a rotation speed of 8000 rpm, the results shown in Table 1 were obtained.

Table 1 qli V-sai middle listing 5C 關 14 Meng Shufu ■ 1 was set as 2.8 and played all day long.

Example 2 A nylon 6 copolymer obtained by copolymerizing 15% by weight of nylon 66 was melt-spun in the same manner as in Example 1.

After water cooling, the stretching conditions and heat treatment conditions were changed to create a diameter of 2.
．． A monofilament with a circular cross section of 5 mm was produced.

The properties of the obtained monofilament were as shown in Table 2. When these monofilaments were used as the rotary blade of a mower to cut weeds in the same manner as in Example 1, the results shown in Table 2 were obtained.

<Effects of the Invention> As described above, the monofilament of the present invention has specific physical properties, particularly a specific degree of flexibility, and therefore has good sharpness and excellent durability.

There is no possibility of the base of the attachment part breaking due to bending fatigue under high-speed rotation of the mower, or cracking of the tip due to impact wear.

In addition, the method of the present invention involves spinning, water cooling, stretching, and then heat treatment under specific conditions.
A monofilament having the above-mentioned specific degree of flexibility can be obtained more easily and uniformly than in a method in which heat treatment is performed once the monofilament is confirmed. Furthermore, since the method of the present invention uses polymers of the same type, nylon 6 and nylon 66, unlike the method using a mixture of different materials, the original properties of nylon are not impaired. According to the method, a monofilament with excellent durability against root breakage and tip cracking can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the main parts of a flexibility measuring device according to the present invention. 1--Sample 2.2°--Fulcrum 3-----1 Tension tool 4-Stress detection device

Claims (1)

[Scope of Claims] 1) Made of nylon 6 copolymerized or mixed with 5 to 20% by weight of nylon 66, has an approximately circular cross section with a diameter of 0.9 to 4 mm, and has a tensile strength of 2.
A monofilament for a lawn mower, characterized in that it has a cutting elongation of 60 to 120%, and a flexibility of 8 to 14 mg/d. (2) When producing a monofilament having a substantially circular cross section with a diameter of 0.9 to 4 mm from a nylon 6 polymer copolymerized or mixed with 5 to 20% by weight of nylon 66, the polymer is melt-spun, cooled with water, and then Stretched 2.5 to 3.2 times in a 95°C hot water bath, then stretched at 1500 to 2400 degrees at a temperature of 200 to 350°C under tension of 0.95 to 1.00 times in a gas atmosphere.
A method for producing monofilament for mowers, which is characterized by heat treatment for a time of seconds.