JPS6264845A - Melt-molded polyethylene - Google Patents

Abstract

PURPOSE:To improve the antimicrobial and antifungal activities of fishing implements such as fishing nets, apparatuses and facilities which are used in sea water, by blending copper powder or copper alloy to polyethylene in a specified ratio and melt-molding it. CONSTITUTION:A melt-molded polyethylene can be obtd. by blending at least 10pts.wt. at least one metallic powder having an average particle size of 20mum or below and such a particle size distribution that a residue on a 250-mesh sieve is 80wt% or below, selected from among powders of metallic copper and alloys having a copper content of 60wt% or above, with 90pts.wt. polyethylene and melt-molding the mixture. The obtained moldings have such a density d(g/cc) that a coefficient alpha is greater than 4 in the formula wherein dp is the density of the resin component constituting the molding; dcu is the density of the metallic powder; x is the quantity in wt% of the metallic powder contained in the molding.

Description

[Detailed Description of the Invention] Industrial Application 1 The present invention provides a filament with excellent antibacterial and antifungal properties,
It relates to polyethylene melt-molded products in the shape of sheets, films, pipes, etc.

It is well known that as we enter the era of the 200 nautical mile limit, our country's fisheries resources that can be caught have decreased significantly, and as a countermeasure, fisheries have shifted from fishing to cultivating fisheries, and in particular, aquaculture fisheries are becoming more popular. It is exactly as it is written. At the same time, the development of fishing gear necessary for aquaculture has become active, and there are problems in particular with fishing gear being corroded in seawater or having various types of deposits attached to it. Research on pest control is underway.

Conventionally, ropes and fishing nets used in fishing have been made of synthetic resins such as polyethylene, polypropylene, or nylon; Although it is said that corrosion caused by marine bacteria is less common than other fishing gear, it is well known that a considerable number of microorganisms can grow in spots on the synthetic resin fishing gear, causing the surface of the fishing gear to corrode in a concave shape. It is that you are. That is, rope and i! ! When fishing gear such as a net is immersed in seawater for a certain period of time, organic and inorganic suspended substances suspended in the seawater first adhere to it, and then algae such as Shiomiduro, Itofusa, and Ulva, and hydroids, etc. They adhere to each other, and a large number of minute deposits grow densely, and as time passes, moss insects adhere to the water, creating areas where the water flow becomes stagnant.Furthermore, floating larvae such as Fujibushi occur and easily attach to the water. The water flow within the aquaculture net becomes stagnant, leading to the occurrence of pests and diseases, and hindering the growth of aquaculture.

In order to deal with the above-mentioned problems, various antifouling agents have been commercially available.For example, fishing nets are coated with the antifouling agent by soaking them in a solution of these antifouling agents, and then air-dried to remove the antifouling agent. is applied to fishing nets to give them an antifouling effect, but the effect only lasts for a few months at most, and there is a problem in that the antifouling agent must be applied to fishing nets frequently. The damage caused by the marine organisms described above is not limited to fishing nets, but is also observed in molded products such as sheets, films, and pipes used in devices and equipment that use seawater, and is still a major problem.

The problem that the invention aims to solve: Landfill However, the conventional antifouling methods described above have poor long-term effects, and fishing gear such as fishing nets, as well as equipment and equipment that use seawater, require antifouling agents and disinfectants. There was a problem in that paint had to be applied frequently for maintenance management.

The above-mentioned problems of the prior art can be solved by using, for example, a rope, net, sheet or film made of monofilament produced according to the present invention. That is, when these molded products such as ropes, nets, sheets, or films are immersed in seawater, the metal powder dispersed and kneaded in the melt-molded product of the present invention is ionized in the seawater, and the metal powder is ionized in the seawater. It exhibits a bactericidal effect that inhibits the growth of bacteria and kills algae such as blue midge.

That is, according to the present invention, 90 parts by weight of polyethylene is selected from metallic copper having an average particle size of 20 μm or less and a residual amount on a 250 mesh sieve of 8% by weight or less, and an alloy powder having a copper content of at least 60% by weight. In a molded product that is a melt-molded product containing at least 10 parts by weight of at least one kind of metal powder, if the coefficient α in the density d (g/cc) formula of the melt-molded product obtained by the following equation (1) is greater than 4. A polyethylene melt-molded article is provided having a density such that:

d = dp (1-(x/100)) + (dcu
/α) ・(x/100)-(I) (where dp indicates the density of the resin component constituting the molded product, dcu indicates the density of the metal powder, and X represents the metal powder contained in the molded product. ) The polyethylene melt-molded product according to the present invention can be made into any filament, sheet, film, vibrator, etc. by melt-molding the blend of the polyethylene and metal powder, cooling and drawing. refers to something in the form of

The metal powder used in the present invention has an average particle size of 20
The particle size is 1 μm or less, preferably more than 1 μm and 15 μm or less, particularly preferably more than 1 μm and 12 μm or less. That is, in order to obtain appropriate mechanical performance by melt-molding the obtained resin composition, it is necessary to use metal powder with an average particle size of 20 μm or less.

However, even if the average particle size of the metal powder is 20 μm or less, if the amount of coarse powder remaining on the 250 mesh sieve exceeds 8 weight 5 of the metal powder, the molded product when melt-molding the resin composition may not be sufficient. It is not preferable because it cannot exhibit mechanical performance.

Preferred metal powders have an average particle size of 12 μm or less and 250 μm or less.
The amount of coarse powder remaining on the mesh sieve is 5% of the metal powder.
% by weight or less. Particularly preferred metal powders have an average particle size of 8 μm or less, and the amount of coarse powder remaining on a 250-mesh sieve is 2% by weight or less, and furthermore, the amount of coarse powder remaining on the sieve is 0.5% by weight or less. In this case, particularly excellent performance is exhibited.

The smaller the average particle size of the metal powder, the better its dispersibility in resin.
The mechanical performance of the resin composition is also excellent, and when the average particle size is 1 μm or less, not only is the effect of improving the dispersibility and mechanical performance hardly increased, but the price of the metal powder becomes extremely high (and the price of the metal powder becomes extremely high). For the purposes of the invention, 1 μm in terms of economy.
The use of metal powders having an average particle size of:

Can be used as metal powder in the present invention,
The alloy powder containing at least 60% by weight of copper is
Examples include brass, bronze, and nickel-copper alloys.

The amount of metal powder used in the present invention is 10 parts by weight or more, preferably 10 parts by weight, based on 90 parts by weight of polyethylene.
~50 parts by weight. If the amount added exceeds 50 parts by weight,
It is undesirable because it causes a decrease in the mechanical performance of the resin molded product without particularly increasing the antibacterial and antifouling effects.
On the other hand, if the amount of metal powder blended is too small, the antibacterial and antifungal effects will be lost, which is not preferable. In order to obtain a resin composition of polyethylene and metal powder that is excellent in both moldability and mechanical performance as well as antibacterial and antifungal effects, the preferred amount of metal powder blended is 15 to 45 parts by weight, particularly preferably 2
It is 0 to 40 parts by weight.

The polyethylene used in the present invention is an ethylene homopolymer or contains at least 8 units of ethylene.
0% by weight of ethylene and other comonomers (e.g. propylene, α-olefins such as butene-1, hexene-1,4-methylpentene-1, octene-1, vinyl acetate, methyl acrylate, methyl methacrylate, etc.) ester, acrylic acid, methacrylic acid, maleic anhydride, styrene, vinyl ethyl ether, isoprene, butadiene, etc.), and is produced by conventional radical polymerization or ionic polymerization. be able to. The polyethylene may be a mixture of ethylene alone or a copolymer obtained by the radical polymerization or ionic polymerization, or may be a mixture of other thermoplastic resins (for example, nylon, polypropylene) in an amount of 20% by weight or less. It can be anything.

Further, a polyolefin resin modified by grafting, copolymerization, etc. with a carboxylic acid or a nucleic acid derivative may be mixed. It goes without saying that any additives conventionally known in this field can be used in addition to the above components.

When melt-molding the mixture of the polyethylene and the metal powder obtained in this way, the density of the molded product is as described above (1).
It is important that α in the formula be greater than 4 in order for the molded article to exhibit antibacterial and antifungal properties. In other words, in order for a molded product to exhibit antibacterial and antifungal properties, it is necessary for the copper ions in the molded product to be effectively eluted, and it is necessary to create effective voids around the metal powder. Since there is, the formula (
If α in I) is less than 4, effective elution of copper ions will not be observed and the antibacterial and antifungal effects will be lost, which is not preferable. Moreover, if α is larger than 100, the molded product tends not to exhibit effective mechanical strength. In order to obtain such α, for example, the resin is stretched at a temperature lower than the melting point of the resin after melt molding.

The melt-molded product according to the present invention can be produced, for example, by mixing polyethylene and metal powder using any mixing method, then heating and melting using a general-purpose extruder, extrusion molding, cooling and stretching, and spinning or molding. Filaments, tapes, pipes, films, etc. with excellent antibacterial and antifungal properties can be easily produced.

Particularly effective molded articles can be obtained by multiplying the melt stretching by at least three times during melt molding of the resin. Also,
It can be obtained by stretching twice or more at a temperature below the melting point of the resin forming the molded article.

The various molded products according to the present invention have the characteristic that even if their surfaces are abraded by, for example, seawater, the antibacterial and anti-mildew effects will not be diminished because the metal powder is dispersed and kneaded throughout the molded product. In addition, the melt-molded product according to the present invention can be used for purposes other than fishing, such as nets to prevent the spread of sludge and silt generated during dredging, seawall construction, etc., antibacterial shoe insoles, sanitary sheets, It can also be used for anti-fouling packaging films, nets used outdoors, etc.

EXAMPLES The present invention will be described in detail below, but it goes without saying that the scope of the present invention is not limited to these Examples.

Large koji example 1 - 2.5 kg of metallic copper powder with an average particle size of 5 μm (residual amount on a 250 mesh sieve is 0.3% by weight), 7.5 kg of high-density polyethylene (density 0.950 g/cc),
After uniformly mixing 20 g of di-t-butylhydroxytoluene and 30 g of calcium stearate using a Henschel mixer, pellets of resin composition (1) were obtained by melt-mixing using a 30 mmφ twin-screw extruder.

This resin composition (1) was extruded using a 40+nmφ T-die film molding machine at a T-die temperature of 220°C.
It was cooled with a C chill roll to obtain a 100 μ thick film stretched 8 times. The density of this film is 0,962g/c
c (α in the above formula = 8.9). This film was immersed 1.5 m below the sea surface for 3 months, but no stains were observed, indicating effective antifouling properties.

Example 2 Metallic copper powder with an average particle size of 5 μm (residual amount on a 250 mesh sieve: 0.3%) 2.01 nr, low density polyethylene (density 0.915 g/cc) 8.0 kg and di- 20 g of t-butylhydroxytoluene was mixed uniformly using a Henschel mixer, and then melt-mixed using a 30 mmφ twin-screw extruder to obtain pellets of resin composition (11).

This resin composition (If) was extruded using a 40 mmφ T-die film molding machine at a T-die temperature of 190°C, and
It was cooled with a chill roll to obtain a 100 μm thick film stretched 8 times. The density of this film was 0.927 g/CC (α=9.2 in the above formula). This film was immersed for 3 months at a depth of 1.5 m below the sea surface, but no stains were observed, indicating good antifouling properties.

Example 3 Metallic copper powder with an average particle size of 10 μm 1-8 kg 5 High-density polyethylene (density 0.950 g/cc) 8.0 k
g, ethylene-acrylic acid copolymer (acrylic acid content 8
%, density 0.932g/cc) 0.2 kg, G-
After uniformly mixing 20 g of t-butylhydroxytoluene and 30 g of calcium stearate using a Henschel mixer, pellets of resin composition (III) were obtained by melt-mixing using a 30 n+mφ twin-screw extruder.

This resin composition (IM) was heated to 40TalIl with a monofilament die having 6 small holes between 1mm.
The fibers were drawn and spun 15 times using a φ extruder, cooled in a cooling bath, and then stretched 8 times at 90°C. The density of the resulting drawn yarn was 0.972 g/cc (α in the above formula = 8.3).

A net created by twisting these filaments was used for 3 months.
．． Although it was immersed 5 m below sea level, no stains were observed, indicating good antifouling properties.

Comparative Example 1 Using pellets of the resin composition (1) obtained in Example 1]
A press plate was prepared by press molding using a mold of OcmXlOcmxO, 5 mm (thickness).

The density of this press plate was 1.41 g/cc, and α in the above formula was 3.2.

This press plate was subjected to an underwater immersion experiment in the same manner as in the examples, but it was found that the slime was noticeably covered with barnacles and had no antifouling effect.

Claims (1)

[Claims] 1. 90 parts by weight of polyethylene, selected from metallic copper having an average particle size of 20 μm or less and a residual amount on a 250 mesh sieve of 8% by weight or less, and an alloy powder having a copper content of at least 60% by weight. In a molded article formed by blending at least 10 parts by weight of at least one kind of metal powder and melt-molding, the following formula (
A polyethylene melt-molded product having a density such that the coefficient α in the melt-molded product density d (g/cc) formula shown in I) is greater than 4. d=dp[1-(x/100)]+(dcu/α)・(
x/100)...(I) (In the formula, dp indicates the density of the resin component constituting the molded product, dcu indicates the density of the metal powder, and x represents the weight% of the metal powder contained in the molded product. show.)