JPS63243320A - Molded polyoxymethylene product used in water - Google Patents

Abstract

PURPOSE:To obtain a molded product, such as rope or not, used in the sea, consisting of a linear material having a tensile strength, tensile elastic modulus and void ratio within specific ranges and having effects on prevention of organisms from attaching for a long period with hardly any deterioration in mechanical properties. CONSTITUTION:For example, polyoxymethylene is melted in an extruder, normally extruded at 180-220 deg.C and cooled with a cooling medium, such as air, water or ethylene glycol, and the resultant undrawn material is drawn at 100-200 deg.C in one or many stages using, e.g. an external hot-pressing method and/or dielectric heating method, to provide a polyoxymethylene wiry material having >=0.9GPa tensile strength, 10-50GPa tensile elastic modules and <=10% void ratio. For example, a number of the above-mentioned wiry materials are twisted or blended with a linear material, such as polyolefin or polyester, to produce the aimed molded product, such as rope for fixed nets or buoy.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to polyoxymethylene molded products (=
related. More specifically, it relates to molded products such as ropes and nets that have the effect of preventing the adhesion of organisms in the ocean, lakes, or rivers and have excellent mechanical properties.

(Prior art) Molded objects such as mooring ropes for marine buoys, fixed nets, and aquaculture nets that remain underwater for long periods of time (2) have their surfaces coated with marine animals such as Fujitbo and bryozoans, green algae such as Aonori laver and Aona, etc. Arrangement of brown algae such as mud and fukuro nori (diatoms etc. adhere to them. As a result, the diameter of ropes and nets increases,
This increases weight, increases flow resistance, reduces maneuverability, increases the risk of runoff due to currents and waves, or clogs the aquaculture net, obstructing the flow of water and causing damage to fish and shellfish. An alarming situation arises that can lead to poor growth, disease outbreaks, and death.

Conventionally, in order to overcome these situations, in order to prevent the adhesion of marine organisms (by applying an anti-adhesion agent to the molded product or to the striatal bodies that make up the molded product): A method has been adopted in which a molded article is constructed from the striatum. For example, Tokukai Showa 4t? -20141
Publication No. 6 also discloses that J-(4t-thiazolyl)benzimidazole and a copper compound are mixed therein. λ
-/3t7rλ publication describes that wires made of copper are twisted together with synthetic fibers to make nets or ropes.

(Problems to be Solved by the Invention) The above-mentioned method for preventing adhesion of marine organisms has the following problems. First, application of the anti-adhesive agent to the surface of the molded product: Second, the anti-adhesive agent easily peels off and falls off due to the surface friction received during work, significantly reducing the anti-adhesive effect.

In addition, the duration of the adhesion prevention effect is lower than that of the coating method (= compared to the method of containing an anti-adhesion agent, which stretches the striatal bodies constituting the molded product). The problem is that the mechanical properties of the molded product deteriorate due to the deterioration of the mechanical properties of the molded product. This is a point that leads to a decline in sexuality.

Furthermore, the anti-adhesive agents used in either method include mercury compounds, arsenic compounds, copper compounds, copper, and tin compounds (two representative examples), and currently organocopper compounds and organotin compounds are the main ones (in terms of two). be.

These problems of toxicity to the human body and environmental pollution cannot be overlooked, and marine pollution caused by organometallic compounds (organic metal compounds) that are leached out when immersed in the sea for a long period of time has become a particularly serious problem.

The purpose of the present invention is to eliminate the above-mentioned drawbacks, to provide a new marine industrial material that exhibits the effect of preventing the adhesion of marine organisms for a long period of time, has excellent mechanical properties, and has extremely low risk of causing marine pollution. (There are two.

(Means for solving the problem) In order to achieve the above-mentioned object (= as a result of extensive research), the present inventor found out that the striatal body (:
The inventors have discovered that good results can be obtained by using a filament made of polyoxymethylene, and have thus arrived at the present invention.

That is, the present invention is a polyoxymethylene filament, which has a tensile strength of θ, 9 GPa or more, a tensile modulus of 7 θ to j0 GPa, and a void ratio of 10 or less. This is a polyoxymethylene molded product used in

In the present invention (2), the striae constituting the molded product are polyoxymethylene striae. Polyoxymethylene is 2≦0
There are various decomposition mechanisms such as thermal decomposition at high temperatures above ℃, oxidative decomposition at lower temperatures, decomposition in the presence of hydrogen ions, decomposition by ultraviolet light, and hydrolysis. When decomposition occurs, formaldehyde is generated (two connections).

When polyoxymethylene striatum is immersed in water, a small amount of formaldehyde is generated. This formaldehyde and formaldehyde-derived substances, such as formic acid, are presumed to have an anti-adhesion effect.Formaldehyde generation It is thought that this is caused by elution of formaldehyde adsorbed into polyoxymethylene striatum into water or by decomposition of polyoxymethylene, but the adhesion prevention effect based on the latter mechanism is permanent. The deterioration of the mechanical properties of the filament due to the decomposition of polyoxymethylene does not pose much of a problem because the decomposition itself is slight and slow, and molded products,
For example, the service life of ropes and nets (2) will not be affected.

The molded product must be composed of polyoxymethylene strands, but if the molded product is a rope or net (- means
A part of the core wire or side wire of the twisted wires constituting these wires is made of a wire other than polyoxymethylene wire, such as polyolefin, polyester, polyamide, polyether other than polyoxymethylene, polyvinylidene chloride, etc. Strip, steel wire, stainless steel wire? - line may also be used.

In invention C2, the tensile strength of the polyoxymethylene filament must be 0.90 Pa or more. When manufacturing molded products such as ropes and nets, damage sustained during the manufacturing process (secondarily, the mechanical properties of the final molded product are usually lower compared to the mechanical properties of the filament, which is the raw material). Put it away.

If the tensile strength of the polyoxymethylene strands is less than 0.9 GPa, the level of characteristic values required for ropes and nets will not be satisfied.

The preferred range of tensile strength is 20 Pa or more.

In the present invention (2), the tensile modulus of the polyoxymethylene filament must be 10~j OGPa.

The tensile elastic modulus is one measure representing the state of the microstructure of the striatal body, and when the tensile elastic modulus is less than /OGPa, the amorphous portion exists in the striatal body in an amount of 1=more. If the proportion of amorphous parts is high, the above-mentioned decomposition of polyoxymethylene and generation of formaldehyde are likely to occur and proceed in a chain reaction, so although the effect of preventing the adhesion of marine organisms is improved, the striatum's It deteriorates severely and cannot be used for a long period of time.On the other hand, when the tensile modulus exceeds OGPa, the proportion of amorphous parts is small, and the decomposition of polyoxymethylene occurs preferentially in the amorphous parts. , the generation of formaldehyde is significantly reduced, and an excellent anti-adhesion effect cannot be expected.

In the present invention, the polyoxymethylene striatum must have a void ratio of 10 or less. If the void ratio exceeds 70, recesses that can serve as initial landing sites for marine organisms will form on the surface of the striatum. They become present in large numbers and promote adhesion.Also, the filaments become easily bent and buckled, resulting in knots and a marked decrease in the hooking strength, which impairs the mechanical properties of the molded product. (-) The void ratio is preferably less than (2).

The polyoxymethylene in the present invention (2) may be obtained by a known polymerization method, and may also contain various additives, antistatic agents, plasticizers, and weather resistance improvers.Polyoxymethylene wire The strips are usually obtained by stretching, but
For example, polyoxymethylene is melted and plasticized in an extruder, extruded at a temperature of usually 0 to 220°C, and then cooled with a cooling medium such as air, water, or ethylene glycol to form an unstretched polyoxymethylene body. , for example, heating to 100A-200°C using an external pressure heating method (Japanese Patent Application Laid-open No. 60-/♂3/2), a dielectric heating method (Japanese Patent Application Laid-Open No. 60-239339), or a combination of both methods. 7
C: It can be produced by stretching in stages or in multiple stages. Furthermore, by changing the cross-sectional shape, external dimensions, or stretching ratio of the unstretched polyoxymethylene body, the linear body having any desired cross-sectional shape and external dimensions can be obtained.

In the present invention (-), molded products include various types of bottom nets for fish, fixed nets such as set nets, subdivided type and partition type aquaculture nets, shellfish aquaculture, ropes for fixed nets, ropes for aquaculture nets, and shellfish aquaculture nets. Examples include nets and ropes such as ropes for aquaculture, ropes for seaweed cultivation, ropes for mooring underwater facilities, ropes for mooring buoys and ships, and special products (ropes for fixed net sidings, ropes for trawl nets). It gives good results when used for mooring ropes, aquaculture nets, etc.

The tensile strength, tensile modulus, and void fraction of the polyoxymethylene filament can be controlled by the stretching temperature, stretching ratio, and stretching tension.

The structure of the molded product of the present invention may differ depending on the purpose of use; for example, a small mesh having a structure of seven strands, a rope made by twisting seven small wires, as shown in Figure 1. Preferable examples include ropes with a similar structure, and nets made of two twisted wires.
It is not limited to this, and various types and structures used in the industry can be used.

Hereinafter, the present invention will be explained in more detail from Example C2.

In addition, the tensile strength, tensile modulus, and void ratio in the examples are based on the following measurement method C2.

Measuring method of tensile strength: A strand is set in the tensile test a at a sample length of −0 cts, and the tensile test is performed at a tensile speed of 0−. The tensile strength is strong when the filament is cut. The strength of the u-pu is obtained by dividing the tensile strength of the rope by the rope cross-sectional area calculated from the rope diameter.

Measuring method of tensile modulus; Tensile testing machine equipped with fixed position wedge grips (2,
Set the striatum with a sample length of 1.

After applying some tension to remove the slack in the striatum, mark the gauge points on the striatum. Gauge distance accurately 351
1, then clamp the gauge point firmly with the differential transformer type extension detection end holder. After installing the detection end on the receiver, perform the test in the same way as a normal tensile test. The elongation is stopped when the elongation is around /96, and the tensile modulus is obtained by extrapolating the linear region of the elongation of the obtained elongation-load curve less than 0.3'4.

Void ratio: Cross-sectional area (S+ cd) and outer dimension of the striatum calculated by dividing the weight (Wt) of the striatum of a certain length (L cya) by the density (ρf/cd) obtained by actually measuring the striatum It is obtained using the following formula from the cross-sectional area (St ad ) calculated by actually measuring .

Void rate”(/S+/a2)X10o(%)However, 8
．． =W/l·ρ (-) (Example) Examples and comparative examples are shown below, and the results of the marine organism adhesion test on each side are listed in Table 1 (two are listed together).

Example/ Polyoxymethylene pellets (manufactured by Asahi Kasei Kogyo ■, (registered trademark >3010") are used as raw materials and melted and extruded at a temperature of 200°C to produce polyoxymethylene with an outer diameter of 2.6 mm and an inner diameter of 0.6 mm. An unstretched tube was molded using the method described in Japanese Patent Application Laid-Open No. 173122/1984 at /4tO℃ and 4tOWcd in the seventh stage, and /7!℃ and 10cm in the second stage.
One step of stretching was carried out under external pressure and heating at θV- to obtain a polyoxymethylene filament with a final stretching ratio of 20 times. The outer diameter of the filament was o, J-1, the tensile strength was /, ≦GPa, the tensile modulus was 4t GPa, and the void ratio was θ.

These seven filaments were twisted together to produce a /×7 rope. The outer diameter of the rope is 15! The apparent tensile strength of chuu is /
, 0 GPa.

Comparative Example/An unstretched polyoxymethylene tube molded in Example/ was treated in the same manner as in Example/ to obtain a polyoxymethylene filament with a final stretching ratio of 5 times.

The outer diameter of the filament is 0.9♂, and the tensile strength is 0.9♂. GP
a, the tensile modulus is 7GPa, the void ratio is 0chi, the outer diameter of a /×7 rope made by twisting seven of the same filaments is 2.2■, and the apparent tensile strength is 0.30Pa. However, it cannot be said that its mechanical properties are superior to those of conventional synthetic fiber ropes.

Example co The polyoxymethylene filament obtained in Example / was used as the core material for a book and a rope, and a total of seven filaments made of polypropylene were twisted together / × B + 7, outer diameter /,! - made a rope. The apparent tensile strength was 0.90 Pa.

Comparative example λ Made of commercially available nylon Otsu, outer diameter O0! A rope of /×7 was made by twisting seven seven filaments of ■. The outer diameter of this rope is /,! ■, apparent tensile strength is 0.3
It was 0Pa.

Example 3 From the polyoxymethylene strands and polypropylene fibers obtained in Example 1, a 6×24 structure as shown in one dormitory area was prepared.
A rope of t was made. The outer diameter of the rope was 22 wm, and the apparent tensile strength was 0.9 GPa.

Adhesion test〉 The ropes of the above examples and comparative examples were tested at / m x / m
Two iron frames (two parallel), Shimaura Oki, Nobeoka City, Miyazaki Prefecture,
An adhesion test was conducted for 4 months from spring to autumn by immersing it in deep water. In addition, the apparent and tensile strength of the rope after the test was measured, and the strength retention rate was evaluated.

These results are shown in Table 1.

In addition, the evaluation of the adhesion test was performed by observing the adhesion state and determining the ratio of the adhesion area to the sample surface area, which is indicated by the following numbers.

4t: No adhesion 3: Adhesion below 1O//~30/-, 3/-jO 0:! From Table 7, it was found that the rope of the present invention not only has an excellent adhesion prevention effect, but also exhibits almost no deterioration in its excellent mechanical properties.

(Effect of the invention) According to the present invention C2, an excellent adhesion prevention effect that is permanent over a long period of time can be obtained, and its excellent mechanical properties are hardly deteriorated. In addition to saving labor, it can be used without deteriorating workability and has a longer service life.Secondly, there are no concerns about toxicity to the human body, fish and shellfish, and marine pollution. Therefore, the polyoxymethylene molded product of the present invention is a new marine industrial material that has great effects in the aquaculture industry, various fishing applications such as fishing wax, and marine applications.

[Brief explanation of the drawing]

FIG. 7 shows an example of the structure of a rope made of polyoxymethylene filaments. 1...Polyoxymethylene striae, 2...Polypropylene fiber Patent applicant Asahi Kasei Corporation Figure 1

Claims (1)

[Claims] Composed of polyoxymethylene filaments, the filaments have a tensile strength of 0.9 GPa or more and a tensile modulus of 10 to 50 G.
A polyoxymethylene molded product for use in water, characterized by having a void ratio of 10% or less.